WO2018120015A1

WO2018120015A1 - Coordinated multiple network access nodes for unlicensed channel access

Info

Publication number: WO2018120015A1
Application number: PCT/CN2016/113484
Authority: WO
Inventors: Rongzhen Yang; Hujun Yin; Rong Zhang; Xiaoran FANG; Shoujiang MA; Longcheng ZHU
Original assignee: Intel Corporation
Priority date: 2016-12-30
Filing date: 2016-12-30
Publication date: 2018-07-05

Abstract

A method for central coordination of Network Access comprising determining a timing of a synchronized transmission opportunity; generating a random backoff value; receiving channel availability data from a plurality of Network Access Nodes during a period corresponding to the random backoff value; determining a transmission decision for each of the plurality of Network Access Nodes based on the received channel availability data; transmitting the transmission decision to the plurality of Network Access Nodes; and performing wireless communication during the synchronized transmission opportunity via the Network Access Nodes selected for transmission based on the transmission decision.

Description

COORDINATED MULTIPLE NETWORK ACCESS NODES FOR UNLICENSED CHANNEL ACCESS

Technical Field

Various embodiments relate generally to methods and devices for optimizing quality of service in radio communication settings.

Background

Although the unlicensed spectrum may be desirable in certain respects, compared to the licensed spectrum, the procedures for collision avoidance in the unlicensed spectrum have rendered the unlicensed spectrum cumbersome for high density environments. Because current protocols implement collision avoidance using a permutation of the Listen Before Talk ( “LBT” ) rule, environments with multiple Network Access Nodes will defer to each other to avoid a collision, thereby resulting in only one Network Access Node transmitting at a given time, which may result in undesirably slow data connections in area of increased density.

Brief Description of the Drawings

In the drawings, like reference characters generally refer to the same parts throughout the different views. The drawings are not necessarily to scale, emphasis instead generally being placed upon illustrating the principles of the Disclosure. In the following description, various embodiments of the Disclosure are described with reference to the following drawings, in which:

FIG. 1 shows an exemplary method for Carrier Sense Multiple Access scheduling；

FIG. 2 shows an exemplary method for managing random backoff；

FIG. 3 shows an exemplary configuration of Network Access Nodes without central control；

FIG. 4 shows an exemplary transmission schedule of two Network Access Nodes based on an LBT rule；

FIG. 5 shows an exemplary transmission schedule of four Network Access Nodes based on an LBT rule；

FIG. 6 shows an exemplary configuration of centrally controlled Network Access Nodes；

FIG. 7 shows an exemplary schedule of two centrally controlled Network Access Nodes；

FIG. 8 shows an exemplary general-purpose computing platform for multiple Network Access Node control；

FIG. 9 shows an exemplary general-purpose computing platform for multiple Network Access Node control with virtual machine management；

FIG. 10 shows an exemplary transmission schedule of multiple Network Access Nodes with central control；

FIG. 11 shows an exemplary procedure for central management of a plurality of Network Access Nodes；

FIG. 12 shows an exemplary procedure for random backoff management；

FIG. 13 shows an exemplary circuit configuration for central coordination of Network Access Nodes for channel access； and

FIG. 14 shows an exemplary method for central coordination of Network Access Nodes for channel access.

Description

The following detailed description refers to the accompanying drawings that show, by way of illustration, specific details and aspects in which the Disclosure may be practiced.

The word “exemplary” is used herein to mean “serving as an example, instance, or illustration. ” Any embodiment or design described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments or designs.

The words “plural” and “multiple” in the description and the claims expressly refer to a quantity greater than one. Accordingly, any phrases explicitly invoking the aforementioned words (e.g. “a plurality of [objects] ” , “multiple [objects] ” ) referring to a quantity of objects expressly refers more than one of the said objects. The terms “group (of) ” , “set [of] ” , “collection (of) ” , “series (of) ” , “sequence (of) ” , “grouping (of) ” , etc., and the like in the description and in the claims, if any, refer to a quantity equal to or greater than one, i.e. one or more. The terms “proper subset” , “reduced subset” , and “lesser subset” refer to a subset of a set that is not equal to the set, i.e. a subset of a set that contains less elements than the set.

A “circuit” as user herein is understood as any kind of logic-implementing entity, which may include special-purpose hardware or a processor executing software. A circuit may thus be an analog circuit, digital circuit, mixed-signal circuit, logic circuit, processor, microprocessor, Central Processing Unit ( “CPU” ) , Graphics Processing Unit ( “GPU” ) , Digital Signal Processor ( “DSP” ) , Field Programmable Gate Array ( “FPGA” ) , integrated circuit, Application Specific Integrated Circuit ( “ASIC” ) , etc., or any combination thereof. Any other kind of implementation of the respective functions which will be described below in further detail may also be understood as a “circuit. ” It is understood that any two (or more) of the circuits detailed herein may be realized as a single circuit with substantially equivalent functionality, and conversely that any single circuit detailed herein may be realized as two (or more) separate circuits with substantially equivalent functionality. Additionally, references to a “circuit” may refer to two or more circuits that collectively form a single circuit.

As used herein, “memory” may be understood as a non-transitory computer-readable medium in which data or information can be stored for retrieval. References to “memory” included herein may thus be understood as referring to volatile or non-volatile memory, including random access memory ( “RAM” ) , read-only memory ( “ROM” ) , flash memory, solid-state storage, magnetic tape, hard disk drive, optical drive, etc., or any combination thereof. Furthermore, it is appreciated that registers, shift registers, processor registers, data buffers, etc., are also embraced herein by the term memory. It is appreciated that a single component referred to as “memory” or “a memory” may be composed of more than one different type of memory, and thus may refer to a collective component comprising one or more types of memory. It is readily understood that any single memory component may be separated into multiple collectively equivalent memory components, and vice versa. Furthermore, while memory may be depicted as separate from one or more other components (such as in the drawings) , it is understood that memory may be integrated within another component, such as on a common integrated chip.

The term “base station” used in reference to an access point of a mobile communication network may be understood as a macro base station, micro base station, Node B, evolved NodeB ( “Enb” ) , Home eNodeB, Remote Radio Head ( “RRH” ) , relay point, etc., and may include base stations implemented with conventional base station architectures (e.g. distributed, “all-in-one” , etc. ) and base stations implemented with centralized base stations architectures (e.g. Cloud Radio Access Network ( “Cloud-RAN” ) or Virtual RAN ( “Vran” )) . As used herein, a “cell” in the context of telecommunications may be understood as a sector served by a base station. Accordingly, a cell may be a set of geographically co-located antennas that correspond to a particular sectorization of a base station. A base station may thus serve one or more cells (or sectors) , where each cell is characterized by a distinct communication channel. Furthermore, the term “cell” may be utilized to refer to any of a macrocell, microcell, femtocell, picocell, etc. In light of this Disclosure’s focus on C-RAN architecture, this Disclosure has selected the term Network Access Node to refer to any node by which a terminal device can connected to a wireless network, whether a base station, a distributed base station under a C-RAN paradigm, a Remote Radio Head, or otherwise.

For purposes of this disclosure, radio communication technologies may be classified as one of a Short-Range radio communication technology, Metropolitan Area System radio communication technology, or Cellular Wide Area radio communication technology. Short Range radio communication technologies include Bluetooth, WLAN (e.g. according to any IEEE 802.11 standard) , and other similar radio communication technologies. Metropolitan Area System radio communication technologies include Worldwide Interoperability for Microwave Access ( “WiMax” ) (e.g. according to an IEEE 802.16 radio communication standard, e.g. WiMax fixed or WiMax mobile) and other similar radio communication technologies. Cellular Wide Area radio communication technologies include GSM, UMTS, LTE, LTE-Advanced ( “LTE-A” ) , CDMA, WCDMA, LTE-A, General Packet Radio Service ( “GPRS” ) , Enhanced Data Rates for GSM Evolution ( “EDGE” ) , High Speed Packet Access ( “HSPA” ) , HSPA Plus ( “HSPA+” ) , and other similar radio communication technologies. Cellular Wide Area radio communication technologies also include “small cells” of such technologies, such as microcells, femtocells, and picocells. Cellular Wide Area radio communication technologies may be generally referred to herein as “cellular” communication technologies. It is understood that exemplary scenarios detailed herein are demonstrative in nature, and accordingly may be similarly applied to various other mobile communication technologies, both existing and not yet formulated, particularly in cases where such mobile communication technologies share similar features as disclosed regarding the following examples.

This Disclosure discusses the coordination of a plurality of Network Access Nodes in an unlicensed spectrum. This Disclosure contemplates that there are currently a variety of method and protocols for managing transmissions on an unlicensed spectrum, such as Long Term Evolution-Unlicensed ( “LTE-U” ) , Licensed Assisted Access ( “LAA” ) , Long Term Evolution Wi-Fi Link Aggregation ( “LWA” ) , and MulteFire. This Disclosure expressly contemplates the methods and principles discussed herein being applicable to each of these unlicensed spectrum protocols. Moreover, this Disclosure contemplates that additional unlicensed protocols are likely to become available. References to any unlicensed spectrum protocols are made without limitation, such that they are presumed to apply to each and every unlicensed protocol. Furthermore, where MulteFire is specifically referenced, it is without limitation and should be considered to be applicable to each unlicensed spectrum protocol. It is specifically contemplated the that methods and principles discussed herein may apply to cloud-based Wi-Fi Access Points.

The term “network” as utilized herein, e.g. in reference to a communication network such as a mobile communication network, encompasses both an access section of a network (e.g. a radio access network ( “RAN” ) section) and a core section of a network (e.g. a core network section) . The term “radio idle mode” or “radio idle state” used herein in reference to a mobile terminal refers to a radio control state in which the mobile terminal is not allocated at least one dedicated communication channel of a mobile communication network. The term “radio connected mode” or “radio connected state” used in reference to a mobile terminal refers to a radio control state in which the mobile terminal is allocated at least one dedicated uplink communication channel of a mobile communication network.

Unless explicitly specified, the term “transmit” encompasses both direct (point-to-point) and indirect transmission (via one or more intermediary points) . Similarly, the term “receive” encompasses both direct and indirect reception. The term “communicate” encompasses one or both of transmitting and receiving, i.e. unidirectional or bidirectional communication in one or both of the incoming and outgoing directions.

Because unlicensed frequency bands may be subject to transmission collision, systems for mobile communication on unlicensed frequency bands generally employ a permutation of Carrier Sense Multiple Access ( “CSMA” ) to for collision avoidance. FIG. 1 shows a method for Carrier Sense Multiple Access scheduling 100. According to this method, at the start of a transmission 101, the transmitter assembles a frame 102 for transmission. The transmitter then attempts a transmission 103. In attempting the transmission 103, the transmitter determines whether the communications channel is busy 104, which can mean that a wireless communication is being transmitted on the communications channel. Where the communications channel is busy, the transmitter waits for a period equal to a random backoff time 105 to permit the channel to clear. The backoff time is random, rather than a programmed default time, to reduce the likelihood of repeated conflicts between two devices. After waiting for the random backoff time, the transmitter again assesses whether the communications channel is busy 104. When the transmitter is able to determine that the communications channel is available, the transmitter transmits a first portion of the frame 106. The transmitter then assesses whether a collision was detected 107. If a collision is detected, then the transmitter engages in the random backoff protocol procedure 108. Where no collision is detected, the transmitter determines whether the transmission is finished 109. If the transmission is not finished, the transmitter transmits the next portion of the frame 110 and again assesses whether a collision was detected 107. Where the transmission is finished, the transmission protocol is completed based on a successful transmission 111.

FIG. 2 shows a method for a random backoff protocol procedure 201. The system initially determines whether the maximum number of attempts for transmission have been made 202. If the maximum number of attempts have been made, then the transmission efforts are terminated 203. Where the maximum number of attempts have not been made, the systems waits for the length of the random backoff 204 and then determines whether the transmission channel is still busy 205. Where the transmission channel is not busy, then the system will resume transmission 206. Where the transmission channel is still busy, then the system will double the random backoff variable 207 and reassess the question of whether the maximum number of transmission attempts have been made 202.

FIG. 3 shows a configuration of Network Access Nodes using an unlicensed frequency band, without central control 300. In FIG. 3 two Network Access Nodes, 301 and 303, receive and transmit within the radio coverages of 302 and 304, respectively. Each Network Access Node is in at least occasional wireless communication with a plurality of terminal devices 305. Because the Network Access Nodes are not centrally managed, and because the Network Access Nodes’

radio coverages

302 and 304 overlap, the LBT protocol requires that they defer to one another in the initiation of wireless transmission. This results in only one Network Access Node being able to transmit at a given time, while the remaining Network Access Nodes defer to the transmitting Network Access Node.

FIG. 4 shows a transmission schedule of two Network Access Nodes based on an LBT protocol. Network Access Node #1 401 has a schedule of upload and download, or transmission and reception. Network Access Node #2 402 has a schedule of upload and download, or transmission and reception. The transmission and reception periods are denoted by the shaded portions 404 for Network Access Node #1 401 and 406 for Network Access Node #2 402. In addition, each Network Access Node schedule contains LBT periods, such as 403, 405, and 407. During the LBT periods, the Network Access Nodes listen to the channel (s) for transmission and/or reception, to determine whether the channel (s) is (are) free. During the LBT period, the Network Access Node will not transmit, but will rather only listen, as demonstrated by the unmarked resource blocks in 403, 405, and 407. Where two Network Access Nodes have an overlapping coverage area, such as Network Access Node #1 401 and Network Access Node #2 402, they will normally defer to one another for transmission, such that only one Network Access Node transmits at a given time, as shown in 404 for Network Access Node #2 402 and 406 for Network Access Node #1 401. The periods of

transmission

404 and 406 may comprise periods of download 408 and/or periods of upload 409. Although various portions of FIG. 4 are labeled as being MulteFire specific, this method may apply to other transmission protocols for unlicensed spectrum and is not limited to MulteFire. As shown in FIG. 4, this method of implementing the LBT rule in Network Access Nodes that are not centrally managed results in only one Network Access Node being permitted to transmit or receive at a time.

FIG. 5 shows a schedule of four Network Access Nodes with overlapping coverage based on an LBT rule 500, as shown by Network Access Node #1 501, Network Access Node #2 502, Network Access Node #3 503, and Network Access Node #4 504. The periods denoted as a Frame 505 are periods of transmission or reception for the various Network Access Nodes. The Network Access Nodes implement the random backoff rule by instituting periods of backoff of random lengths 506. Where one Network Access Node is transmitting or receiving, the remaining Network Access Nodes defer to the transmitting or receiving Network Access Node 507, so as to keep the channel clear.

FIG. 6 shows a configuration of centrally controlled Network Access Nodes 600. Network Access Node 601 has coverage area 602, and Network Access Node 603 has coverage area 604. Various terminal devices 605 are connected to one of the Network Access Nodes. A processing component 605 is operatively coupled to the Network Access Nodes by a hard connection 607, such as an optical cable. With the hard-connection, the processing component 605 is able to manage the transmission schedules of the Network Access Nodes, and transmission between the processing component 606 and the

Network Access Nodes

601 and 603 is able to occur rapidly.

FIG. 7 shows a transmission schedule of two Network Access Nodes with processing component management 700. Network Access Node #1 701 and Network Access Node #2 702 are operatively coupled, for example via an optical cable 607, to a processing component 605. The Network Access Nodes utilize an LBT protocol by instituting sensing periods or LBT periods 703, during which the Network Access Nodes listen to the channel (s) for transmission of other devices. Upon determining that the channel is clear, the processing component instructs both

Network Access Nodes

701 and 702 to begin a period of transmission 704 and/or reception. Where the Network Access Nodes are centrally managed, it is no longer necessary for the Network Access Nodes to defer to one another, as would otherwise be required under the LBT and random backoff rules, and therefore the Network Access Nodes can transmit at the same time 704. Where the Network Access Nodes transmit during the same periods 704, it is not necessary for each Network Access Node to transmit the same information. Rather, each Network Access Node may transmit different data corresponding to the terminal devices connected to the respective Network Access Node.

FIG. 8 shows a general-purpose computing platform for multiple Network Access Node control. A processing component is a computing, memory, and software resource management module 801 which manages a plurality of

Network Access Nodes

802 and 803.

FIG. 9 shows a general-purpose computing platform for multiple Network Access Node control with virtual machine management. A virtual machine management software program 901 operates a cell management and coordination application 902 along with a plurality of Network Access Nodes 903.

FIG. 10 shows a transmission schedule of either Network Access Nodes with central control 1000. A plurality of Network Access Nodes 1001 is centrally controlled to effectuate a centralized random backoff 1001 in an LBT protocol. During the centralized random backoff 1001, the Network Access Nodes listen to the channel (s) to determine whether the channel (s) is (are) clear. The central control then implements a period of transmission for some or all of the Network Access Nodes. Where each of the Network Access Nodes senses a clear channel during the centralized random backoff 1001, each of the Network Access Nodes will transmit during the transmission period, as shown in 1002. During the centralized random backoff period, it is possible that one or more Network Access Nodes will sense that a channel is not clear, as demonstrated by Network Access Node #5 in 1003. In this case, the central control will instruct the one or more Network Access Nodes with an occupied channel not to transmit during the next transmission period. In this case, only the Network Access Nodes with a clear channel will transmit during the transmission period, as shown in 1004, where Network Access Nodes #1-4 and Network Access Nodes #6-8 sensed a clear channel and are therefore instructed to transmit in 1004, and where Network Access Node #5 sensed an occupied channel in 1003 and is therefore instructed not to transmit in the transmission period. This may result in periods where a Network Access Node that was instructed not to transmit receives an open channel during the transmission period but defers transmission until the next transmission period where it is instructed to transmit, as shown in 1005.

FIG. 11 shows a procedure for central management of a plurality of Network Access Nodes 1100, comprising starting central management 1101, where the coordinated channel access is triggered to decide the transmission timing and frame structure of each connected Network Access Node； implementing a centralized random backoff sub-procedure based on Received Signal Strength ( “RSS” ) values from different RRHs or cells 1102, where the processing component executes the centralized random backoff procedure, with input from all Network Access Nodes for RSS values； implementing a channel access decision with frame structure for each Network Access Node or cell being sent by a message 1103 where the transmission decision made in 1102 will be sent to each cell by using function call back or VMM message mechanism； each cell then transmits a transmit frame, or not, based on the channel access decision 1104, where each cell will, or will not, transmit a wireless frame based on the received decision, wherein each Network Access Node has the same frame structure of download/upload ratio； and a completion or end 1105, where the main procedure of coordinated channel access is complete.

FIG. 12 shows a procedure for random backoff management 1200 comprising initializing the communication session to determine whether to transmit for each Network Access Node or cell 1201； a random backoff algorithm initialization 1202 wherein a sub-procedure is initiated to determine the contention window ( “CW” ) , wherein the CW_min is the low boundary of the CW, the CW_max is the high boundary for the CW, and the clear channel assessment level ( “CCA_Level” ) is compared to the collected RSS as an indication of whether the channel is clear, and the initial value of CW is set as CW_min； a random backoff value generation from CW 1203, wherein one random number is generated in the range 0～CW, V represents the random backoff time T_BF, wherein the relationship between V and T_BF is T_BF ＝ V × T_U, wherein T_U is the minimum time unit used in the system； a collection of all RSS values from the Network Access Nodes during the backoff time to make transmission decisions 1204, wherein the processing component collects the RSS values, referred to as RSS_i, from each Network Access Node and reaches a transmission decision, D_i, by comparing the RSS_i, with the CCA_Level, as a pseudo code, such that if RSS_i＜CCA_Level， then D_i ＝ 1 otherwise D_i ＝ 0, where D_i ＝ 1 means to transmit a radio frame of the i^th cell and D_i ＝ 0 means not to transmit the radio frame of the i^th cell, and then all D_i values are cached to be accessed by 1202； a determination of whether the communication session for the Network Access Nodes has ended 1205, wherein, and upon completion, the transmission procedure stops 1207, and where it is not complete, the module updates the algorithm parameter CW as stated in 1206, wherein the CW value is updated by the rule as a pseudocode, where if sum (D_i) ＝＝ 0， then CW ＝ CW × 2 and if CW ＞ CW_maxthen CW ＝ CW_min, and wherein after execution of 1206, the procedure returns to 1203.

FIG. 13 shows a circuit configuration for central coordination of Network Access Nodes for channel access 1300 comprising a central logic circuit 1301, a random backoff management circuit 1302, a censing circuit 1303, and a storage element 1304.

FIG. 14 shows a method for central coordination of Network Access comprising: determining a timing of a synchronized transmission opportunity 1401； generating a random backoff value 1402； receiving channel availability data from a plurality of Network Access Nodes during a period corresponding to the random backoff value 1403； determining a transmission decision for each of the plurality of Network Access Nodes based on the received channel availability data 1404； transmitting the transmission decision to the plurality of Network Access Nodes 1405； and performing wireless communication during the synchronized transmission opportunity via the Network Access Nodes selected for transmission based on the transmission decision 1406.

General use of unlicensed spectrum

The spectrum for wireless communication is designated as either licensed spectrum or unlicensed spectrum. The licensed spectrum comprises one or more ranges of frequencies, for which a license is required to transmit. In contrast, the unlicensed spectrum comprises one or more ranges of frequencies for which no license is required to transmit. Although Wi-Fi technology generally occurs on the unlicensed spectrum, the bulk of Long Term Evolution ( “LTE” ) transmission occurs on the licensed spectrum. The ability to use the unlicensed spectrum for voice and /or data communications is increasingly meaningful and desirable.

5^th Generation wireless technology ( “5G” ) is currently in development and is likely to be implemented in the coming years. In light of the communications schemes in development for 5G, the ability to use the unlicensed spectrum similarly appears to be increasingly important. Already protocols are underway to permit or bolster the use of the unlicensed spectrum, such as Long Term Evolution License Assisted Access ( “LTE LAA” ) , Long Term Evolution Unlicensed ( “LTE-U” ) , Long Term Evolution and Wi-Fi Link Aggregation ( “LWA” ) , MulteFire, and the next generations of Wi-Fi. Collectively, these protocols, as well as other protocols already in existence and those in developed or yet to be developed, are unlicensed spectrum radio access technologies ( “USRATs” ) . In light of the protocols in place to manage the unlicensed spectrum, there is a need to improve network efficiency for these new or broader applications of unlicensed spectrum communication.

In addition, development in Software Defined Networks ( “SDN” ) has evolved into Network Function Virtualization with the technical trend from core network functions to radio access network, named as Software Defined Accessing ( “SDA” ) .

According to one aspect of the Disclosure, MulteFire is selected as a USRAT to present this optimization of a cloud radio access network ( “C-RAN” ) architecture, since MulteFire provides performance similar to LTE, but with a similar simplicity to Wi-Fi. To the extent that MulteFire is discussed within this Disclosure, the principles, methods, circuit configurations, apparatuses, etc. discussed herein also apply to other USRATs. The USRAT technology discussed herein can be used as an LTE or 5G-based technology for small cells operating solely, or partially, in an unlicensed spectrum, and for enhanced data and voice services to local area deployments. The USRAT technology discussed herein can be used for future radio access protocols available in tandem with, or subsequent to, 5G. It is suitable for any band that needs over-the-air contention for fair sharing.

Because the unlicensed spectrum is subject to use from a variety of platforms, and because there is little control over the number of unlicensed spectrum nodes or terminal devices within a given location, USRATs must have mechanisms to identify and, where possible, avoid channel collision. In current implementations, a hallmark of unlicensed spectrum channel accessing is Carrier Sense Multiple Access ( “CSMA” ) -based random accessing design with enhancements, wherein the CSMA technology follows the rule of Listen-Before-Talk ( “LBT” ) .

CSMA 100 is a method to avoid transmission collision by employing a combination of LBT and a random backoff procedure. According to one aspect of the Disclosure, the LBT requires that a Network Access Node listens to a transmission channel for wireless communication before the Network Access Node initiates a transmission. This LBT procedure greatly reduces the risk of the Network Access Node creating a transmission conflict by transmitting on a channel that is actively in use by a terminal device or another Network Access Node. Where a Network Access Node employs the LBT rule and discovers an occupied channel, the Network Access Node implements a random backoff time, during which the Network Access Node waits for the channel to clear and reassesses the status of the channel. The backoff time is random to avoid the implementation of standardized wait times, which could lead to multiple devices implementing the same wait times, and ultimately to avoid the scenario where multiple, uncoordinated devices seek repeatedly to transmit at the same time.

According to another aspect of the Disclosure, the random backoff time is modified during an occupied channel. Where an occupied channel is detected 107, the random backoff procedure 108 is activated, whereby the Network Access Node waits for the random backoff period and again assesses whether the channel is clear 205. Where the channel is still busy, and assuming that the maximum number of transmission attempts has not been made 202, the Network Access Node waits an additional random backoff time and again determines whether the channel is available. If the channel becomes available, the Network Access Node resumes transmission 206. If the channel continues to be unavailable, eventually, the Network Access Node will reach a maximum number of attempts, and the Network Access Node will discontinue the transmission efforts.

Although this method may result in collision avoidance, it also results in Network Access Nodes deferring to one another in an implementation where multiple Network Access Nodes are present within an area of wireless communication. Under this protocol, where a plurality of Network Access Nodes seeks to begin a wireless transmission, the CSMA protocol and the LBT rule will generally result in only one Network Access Node transmitting at a given time. This can result in increased delay for each Network Access Node present within a signal area. For example, where two Network Access Nodes are present within a signal area, the individual Network Access Nodes may transmit at half the rate of a single Network Access Node in that area.

Network Access Nodes will have many spectrum access collisions in an unlicensed spectrum deployment due to a distributed channel accessing mechanism based on random backoff. FIG. 5 shows one example of deployment with multiple Network Access Nodes with overlapped cell coverage in the same unlicensed band, which may be a very common occurrence in high density 5G usage. In this figure, the multiple Network Access Nodes with overlapped cell coverage perform LBT with random backoff, which causes the multiple Network Access Nodes to defer to each other, thereby extending the time between transmission opportunities for each Network Access Node.

This transmission delay for multiple Network Access Nodes can result in slow-downs or even a functional halt to transmission in areas of high density. For example, in an airport setting, where there may be multiple terminal devices seeking to transmit or receive information, and where multiple Network Access Nodes may be present within a limited space to accommodate the multiple terminal devices, the LBT and random backoff rules may result in lengthy periods between transmission opportunities, thereby leading to slow or infrequent transfer and ultimately user dissatisfaction.

Centralized Network Access Node management, generally

The C-RAN technology is a means to link multiple LTE base stations on one server or many core servers, wherein multiple Network Access Nodes are connected to one or more servers that centrally manage the Network Access Nodes. In a C-RAN configuration, the Network Access Nodes may be RRHs. According to one aspect of the Disclosure, a USRAN feature is used to centrally coordinate the channel accessing of a plurality of Network Access Nodes. According to another aspect of the Disclosure, this central coordination can result in a time accuracy on the microsecond level, thus achieving much better spectrum utility rates than otherwise available and avoiding channel access collisions. This can result in increased aggregated throughput by eliminating the need for a first Network Access Node to defer to a second Network Access Node, as shown in 400.

Unlicensed Spectrum Deployment

Improvements to unlicensed spectrum deployment for USRAN can be gained by employing a C-RAN-type link for central control of a plurality of Network Access Nodes while implementing new protocols for management of LBT and random backoff protocols. According to one aspect of the Disclosure, where a plurality of Network Access Nodes is present, the Network Access Nodes are connected to a general-purpose computing platform for central control of transmission schedule. The operative coupling between Network Access Nodes is a wired or hard-connection, rather than a wireless connection, and according to another aspect of the Disclosure may be an optical cable. Under this configuration, an optical cable extends from the processing component platform to each of the plurality of Network Access Nodes, as demonstrated in 600, where the processing component 606 is collected via an optical cable 607 to Network Access Node 601 and Network Access Node 603. Alternatively, and where desirable in a given implementation, the optical cables can be arranged from a processing component platform, to a first Network Access Node, and then subsequently to a second Network Access Node in a rely fashion. This rely format may be extended to have a plurality of Network Access Nodes connected in series in a relay fashion. These connection methods whereby the Network Access Node is connected as a hub, or whereby the Network Access Nodes are connected in series, may further be combined within the same installation. The optical cable supports a baseband signal transmission for scheduling and synchronization of Network Access Node transmissions.

This method of coordinated channel access fulfills the LBT and random backoff rules for the unlicensed spectrum. Moreover, this method permits synchronized frame structures and transmission opportunities between a plurality of Network Access Nodes. Due to spectrum reuse, these synchronized transmission opportunities will significantly improve the overall system performance.

Central Coordination on Unlicensed Frequency Bands

According to one aspect of the Disclosure, this combination of unlicensed band technology with C-RAN capacity results in coordinated Multiple-Network Access Node channel access that may provide improvement in wireless system throughput on unlicensed bands. According to one aspect of the Disclosure, the processing component executes one centralized random backoff algorithm in a centralized module. This executes the random backup algorithm by using the channel sensing information from all connected Network Access Nodes to evaluate the channel status, and once the processing component obtains this data, it decides which Network Access Nodes will participate in a synchronized transmission opportunity. According to one aspect of the Disclosure, the number of Network Access Nodes to participate in a transmission opportunity may range from 0 to NAN_i, where NAN_i is the total number of Network Access Nodes connected to the processing component.

A transmission opportunity is a time interval with an starting boundary and an ending boundary during which a Network Access Node may perform a transmission. The Network Access Node is permitted to send as many frames as possible during a transmission opportunity, such that the transmission may end when either the Network Access Node completes a transmission of data, or when the Network Access Node reaches the upper boundary of the transmission opportunity. In the event that a frame is too large for a given transmission opportunity, the Network Access Node must fragment the frame into smaller frames that are capable of being transmitted within the duration of the transmission opportunity.

Known methods of implementing channel access in the context of multiple Network Access Nodes in the unlicensed spectrum are based on the LBT rule with a random backoff algorithm. This random backoff method may be known as Enhanced Distributed Channel Access ( “EDCA” ) , which is depicted in 500 and found in Institute of Electric and Electrical Engineers LAN/MAN Standards Committee 802.11. The random backoff algorithm is executed by generating a pseudorandom number Vi within a range of 0 to CW, where CW is the contention window. The CW is configured to have a CW_min and a CW_max. According to one aspect of the Disclosure, the initial value of CW_min for example can be set to 15. According to another aspect of the Disclosure, the maximum value of CW_max, for example, can be set to 1023. These proffered values notwithstanding, the values of CW_min and CW_max can be set or adjusted to meet the needs of a given limitation and are principally unbounded, such that the values could range from O to infinity.

The CW is initially set as the value of CW_min, and the CW is configured to change in response to failed transmission attempts. According to one aspect of the Disclosure, the processing component doubles the CW after each unsuccessful transmission until the CW reaches or exceeds the CW_max, at which point the processing component returns the CW to the initial value.

During the length of V_i, the processing component will arrange for each Network Access Node to perform an enhanced clear channel assessment by assessing the RSS during a period of channel listening. The processing component compares the RSS data to a threshold determine whether the channel is available or unavailable. The Network Access Node and /or the processing component makes this determination of available or unavailable by assessing a RSS of the channel and comparing the RSS to the CCA_Level. If the RSS is greater than the CCA_Level, the channel is unavailable. If the RSS is less than the CCA_Level, the channel is available.

The CCA is a known method of channel assessment. It is defined by Institute of Electrical and Electronics Engineers 802.11-2007. During the CCA, the Network Access Node performs a carrier sense detection, during which the Network Access Node listens to the channel to detect a signal. The CCA comprises carrier sense and energy detection. During carrier sense, the Network Access Node assesses any signal or noise within the channel for a Wi-Fi heading. During energy detection, the Network Access Node receives energy present on the current channel based on the noise floor, any undecodable or corrupted transmissions, any sources of interference, and /or any ambient energy.

In a CCA determination, a measurement of power ratio is performed and then compared to a threshold to determine whether a channel is busy or clear. According to one aspect of the Disclosure, this measurement may be in decibel-milliwatts.

In a CCA determination, the receiver may perform energy detection to determine whether there is energy in the channel. This energy detection may be performed by using a power meter. The power meter may be used to determine a power level, such as the RSS of a real signal. When the power meter is applied to an unoccupied channel, the power meter will detect the noise floor, which may be approximately -95dBm, depending on the environment. When a transmission takes place, however, the power level will change to reflect the power associated with the transmission. CCA works by comparing the detected power with a threshold to determine whether the channel is clear.

In conventional Wi-Fi application, for example, the CCA threshold level is -82 dBm for a 20Mhz band. Thus, in a conventional Wi-Fi Application, a CCA measurement can be performed and then compared against the -82 dBm threshold. Thus, in this case, if the measured RSS in a 20Mhz band is higher than -82dBm, the channel will be determined to be busy. If the measured RSS in a 20Mhz band is lower than -82dBm, the channel will be determined to be clear. In different protocols and different usage cases, the CCA level can be set as a different value based on pre-defined rules or the specific application. According to one aspect of the disclosure, the CCA level may be greater than -82 dBm. According to another aspect of the disclosure, the CCA level may be less than -82 dBm. The CCA level may be adjusted or configured for the wireless communication system in use.

The processing component may decide to transmit on all Network Access Nodes corresponding to an available channel. Upon determining the Network Access Nodes for the next transmission opportunity, this determination being known as the “transmission decision, ” the processing component notifies each Network Access Node of the transmission decision. According to one aspect of the Disclosure, this notification is performed by instantaneous message communication. In a MulteFire Context this may be performed by built-in instantaneous message provided by the MulteFire specifications.

The main procedure of coordinated channel access is shown in 1100. According to this procedure, a coordinated channel access procedure is triggered to decide the transmission timing and frame structure of each connected Network Access Node, as shown in 1101. According to one aspect of the Disclosure, the process may run within the module of computing and other resource management shown in FIG. 8 or in the cell management and coordination application shown in FIG. 9. The centralized scheduler obtains input from each Network Access Node comprising, at least, RSS values and, using said RSS values, reaches a transmission decision, and executes a centralized random backoff procedure 1102. The centralized scheduler sends the transmission decision to each Network Access Node, thereby informing each Network Access Node whether it is scheduled to transmit in the next transmission opportunity； the decision is sent by using function call back or by using a VMM message mechanism 1103.

At the beginning of the transmission opportunity, each Network Access Node will transmit in accordance with the transmission decision and the demand for transmission 1104. That is to say that a Network Access Node will transmit during the transmission opportunity where it has been both designated in the transmission decision as a Network Access Node for transmission, and where the Network Access Node in fact has data to transmit.

The centralized random backup procedure plays a key role in coordinated channel access and meets requirements of the unlicensed spectrum. FIG. 12 shows a method for performing a random backoff procedure. At the initialization of a communication session, the processing component initiates the random backoff algorithm procedure to determine the Network Access Nodes that will transmit in an upcoming transmission opportunity 1201. The key parameters for random backoff execution are initialized 1202, such that CW_min is the value of the low boundary for the CW； CW_max is the value of the high boundary for the CW； and CCA_level is the Clear Channel assessment threshold value, to be compared to the collected RSS value as an indication of whether the channel is clear.

Upon determining whether the channel is clear, the random backoff value is generated as:

T_BF ＝ V × T_U (1)

wherein V is a random number, or pseudo-random number, generated in the range from 0 to CW； T_U is a minimum time unit used for the system implementation； and T_BF is the length of time of the random back off 1203. According to one aspect of the Disclosure, T_U may be set to four microseconds in a MulteFire or Wi-Fi implementation. According to another aspect of the Disclosure, the structure of the random backoff time being a function of a random variable multiplied by a minimum time unit in the system results in the random backoff time corresponding to the time units of the system of implementation.

During the random backoff time T_BF, the Network Access Nodes may continually collect their corresponding RSS values and will deliver these RSS values to the processing component. The processing component makes a transmission decision using the RSS information, and by comparing the RSS information with a CCA level, such that, for any given Network Access Node, i, if the RSS_i < CCA_Level, then D_i ＝ 1； otherwise D_i ＝ 0, wherein D_i ＝ 1 means to transmit on the _ith Network Access Node, and D_i ＝ 0 means not to transmit on the _ith Network Access Node 1204.

After the Network Access Nodes have transmitted in accordance with the transmission decisions, the processing component identifies whether the communication sessions of all Network Access Nodes have ended 1205. If all Network Access Nodes have completed the transmission, then the transmission is complete and the random backoff procedure ends 1207. Where fewer than all Network Access Nodes have completed the transmission, then the module must update the algorithm parameter CW, such that if the sum (D_i) ＝＝ 0， then CW ＝ CW × 2 and if CW>CW_MAX, then CW＝CW _MIN 1206. (2)

Virtual Machine Management

As shown in FIGS. 8 and 9, the method described herein may be performed by a single operating system without virtual machine management ( “VMM” ) to reduce the implementation complexity, or, alternatively, by VMM. Where this is performed by a single operating system without VMM, the module of computing and other resource management plays a central role in the designation of Network Access Nodes, resource scheduling, designation as a module inside of single operating system, and also support for the coordination among those created base stations.

Alternatively, this may be achieved by a VMM that can support many operating systems on one general-purpose computing platform. According to one aspect of the Disclosure, the VMM may manage and schedule computing and other resources, as well as create the operating systems that accommodate two kinds of applications such as cell management and coordination applications, which inform the VMM of USRAN-related operating system creation, resource scheduling, or any of the assignment, destruction, performance, or coordination of active USRAN Network Access Node applications； or such as a Network Access Node application that runs inside of a client output signal created by the VMM, and implements the full stack of one MulteFire base station.

According to one aspect of the Disclosure, the methods and devices described herein provide unique features that can enable new intercell optimizations. According to another aspect of the Disclosure, the processing component can perform the resulting intercell coordination within one microsecond and can possibly reach the lag of less than 100 ns.

This Disclosure refers repeatedly to Network Access Nodes, which is intended to broadly reference any kind of transceiver-equipped network access point, to which a terminal device may connect. This may include, but is not limited to, Remote Radio Heads, base stations, cloud radio access network base stations, Wi-Fi base stations, and cloud Wi-Fi base stations. This may include any network access point in LTE, 5G, or any other radio acesss technology, or USRAN.

The term network availability data has been used to refer to data that permits a determination of whether a channel for an unlicensed frequency is clear. It is contemplated in this Disclosure that network availability data refers to clear channel assessment or enhanced clear channel assessment data, as well as radio signal strength data. The term network availability data is selected, however, to be non-limiting, such that alternative or future channel listening protocols may be used in this sensing process during the random backoff period.

The random backoff period is a random or pseudorandom period, which is calculated by multiplying a random variable with a minimum time unit for the installation or protocol used, whether MulteFire, Wi-Fi, or otherwise, wherein the minimum time unit is the minimum units of time measured for a transmission, such as a transmission time interval. The random or pseudorandom variable may be determined within a window of 0 to CW, wherein CW has a lower and an upper limit. The calculation of the random backoff value under this method assures that the random backoff value corresponds to a compatible time interval for the protocol used. As described herein, it is anticipated that the random backoff value may change during the sensing and /or transmission process by doubling the CW. As described herein, where a Network Access Node senses a transmission channel that is occupied or unavailable, the CW will be doubled, thereby doubling the random backoff value for the Network Access Node. This doubling procedure can be repeated until either the Network Access Node determines that the transmission channel is available, or until the CW reaches the CW_max, at which time the CW will be returned to CW_min.

According to one aspect of the Disclosure, the minimum time unit to be multiplied with the CW to determine the random backoff time is 4 microseconds. This corresponds to the minimum time unit in Wi-Fi and MulteFire protocols. It is expressly anticipated that the minimum time unit can be greater or smaller than 4 microseconds. It is expressly anticipated that the minimum time unit is selected to correspond to the minimum time unit for whichever unlicensed spectrum protocol is implemented, whether said unlicensed spectrum protocol is currently known or unknown.

According to one aspect of the Disclosure, the Network Access Node selection process described herein is a method for determining which Network Access Nodes within a plurality of Network Access Nodes will transmit during a given transmission opportunity following a random backoff period. Each Network Access Node performs a sensing operation, during which the Network Access Node gathers channel availability data, such as the radio signal strength and clear channel assessment. The processing component compares this data to reach a transmission decision for the corresponding Network Access Node. The processing component performs this operation for each Network Access Node within the plurality of Network Access Nodes. The set of Network Access Nodes for a synchronized transmission opportunity is the set of Network Access Nodes for which the processing component has reached a transmission decision that said nodes will transmit during the next transmission opportunity.

According to another aspect of the Disclosure, a storage element is disclosed, in which the results of the transmission decisions are stored. This may include a D_i value for each Network Access Node, a set of Network Access Nodes selected for a transmission opportunity, a set of Network Access Nodes not selected for a transmission opportunity, or otherwise. The storage element may comprise software and /or hardware. This may be a memory as describe herein, such as, but not limited to, RAM, ROM, solid state memory, hard drive memory, or any other kind of storage element.

Upon determining the set of Network Access Nodes for a transmission opportunity, the processing component notifies the Network Access Nodes of the results of the transmission decision. According to one aspect of the Disclosure, the processing component will inform each Network Access Node of the transmission decision, regardless of whether the decision is to transmit or not to transmit. According to another aspect of the Disclosure, the processing component will inform only the Network Access Nodes that are selected for transmission of the transmission decision. According to another aspect of the Disclosure, the processing component will inform only the Network Access Nodes that are not selected for transmission of the transmission decision. Until this final aspect, the Network Access Nodes are set by default for transmission at the transmission opportunities until informed otherwise.

The processing component notifies the Network Access Nodes of the transmission decision over the operative coupling which attaches the processing component to the Network Access Nodes. This provides rapid communication of the transmission decision and allows for faster transmission coordination than a wireless communication of a transmission decision. With this operative coupling, the processing component may obtain high coordination speeds, thereby increasing efficiency and transmission output.

The central computing functions of the Disclosure may be performed by a central computer, CPU, server, mainframe, or any other suitable computing platform. These central computing functions may be performed by a virtual machine manager.

For a given transmission opportunity, it is contemplated that the transmission opportunity will be of a duration set by the processing component and congruent with the standards of the unlicensed spectrum protocol in use. The transmission opportunity will be of uniform length for all Network Access Nodes selected to transmit during the transmission opportunity, except for which one or more Network Access Nodes completes a transmission before reaching the end of the transmission opportunity. During a transmission opportunity, the Network Access Nodes may transmit as many frames as they are able, until the conclusion of the transmission opportunity. It is expressly contemplated that each Network Access Node selected for transmission during a transmission opportunity may transmit information different from the other Network Access Nodes during the transmission opportunity. In this manner, the multiple Network Access Nodes do not function as a mere broadening of a single transmission signal, but rather are able to transmit a breadth of information corresponding to requests of their terminal devices.

The following Examples pertain to various aspects of the Disclosure:

In Example 1, a system for central coordination of Network Access Nodes is disclosed, comprising:

a plurality of Network Access Nodes, configured to transmit and receive wireless signals； a processing component, operatively coupled to the plurality of Network Access Nodes； wherein the processing component determines a timing of a synchronized transmission opportunity；

generates a random backoff value；

receives channel availability data from a plurality of Network Access Nodes during a period corresponding to the random backoff value；

determines a transmission decision for each of the plurality of Network Access Nodes based on the received channel availability data； and

performs wireless communication during the synchronized transmission opportunity via the Network Access Nodes selected for transmission based on the transmission decision.

In Example 2, the system of Example 1 is disclosed, wherein the Network Access Nodes are Remote Radio Heads.

In Example 3, the system of Example 1 is disclosed, wherein the Network Access Nodes are cloud radio access network base stations.

In Example 4, the system of Example 1 is disclosed, wherein the Network Access Nodes are cloud Wi-Fi base stations.

In Example 5, the system of any one of Examples 1 to 4 is disclosed, wherein the channel availability data are radio signal strength data.

In Example 6, the system of any one of Examples 1 to 4 is disclosed, wherein the channel availability data are clear channel assessment data.

In Example 7, the system of any one of Examples 1 to 4 is disclosed, wherein the channel availability data further comprise radio signal strength data and clear channel assessment data.

In Example 8, the system of any one of Examples 1 to 7 is disclosed, further comprising the system operating according to a MulteFire protocol.

In Example 9, the system of any one of Examples 1 to 7 is disclosed, further comprising the system operating according to a Wi-Fi protocol.

In Example 10, the system of any one of Examples 1 to 7 is disclosed, further comprising the system operating according to a Long Term Evolution Unlicensed protocol.

In Example 11, the system of any one of Examples 1 to 7 is disclosed, further comprising the system operating according to a Licensed Assisted Access protocol.

In Example 12, the system of any one of Examples 1 to 7 is disclosed, further comprising the system operating according to a Long Term Evolution Wi-Fi Link Aggregation protocol.

In Example 13, the system of Example 1 is disclosed, further comprising the processing component determining the random backoff value by multiplying a minimum time unit by a random or pseudorandom number.

In Example 14, the system of Example 13 is disclosed, wherein the minimum time unit is a transmission time interval.

In Example 15, the system of Example 13 is disclosed, wherein the minimum time unit is 4 microseconds.

In Example 16, the system of any one of Examples 13 to 15 is disclosed, wherein the minimum time unit is a minimum time unit in a Wi-Fi or MulteFire protocol.

In Example 17, the system of any one of Examples 13 to 16 is disclosed, wherein the random or pseudorandom number is a number ranging from zero to a clearance window.

In Example 18, the system of any one of Examples 13 to 17 is disclosed, wherein the random or pseudorandom number is a number ranging from zero to a clearance window, and wherein the clearance window has a clearance window minimum and a clearance window maximum.

In Example 19, the system of Example 17 or 18 is disclosed, further comprising the processing component recalculating a random backoff time for a Network Access Node not scheduled for transmission during a transmission opportunity by doubling the clearance window.

In Example 20, the system of any one of Examples 18 through 19 is disclosed, further comprising the processing component identifying a clearance window that has exceeded the maximum clearance window and setting the clearance window equal to the minimum clearance window.

In Example 21, the system of any one of Example 1 to 20 is disclosed, further comprising the processing component determining the transmission decision by comparing a radio signal strength with a predetermined clear channel assessment value.

In Example 22, the system of any one of Examples 1 to 21 is disclosed, further comprising the processing component determining the transmission decision of whether a Network Access Node will transmit at a next transmission opportunity using a comparison of a radio signal strength and a predetermined clear channel assessment value.

In Example 23, the system of any one of Examples 1 to 22 is disclosed, further comprising the processing component scheduling a Network Access Node for the synchronized transmission opportunity is disclosed, wherein a radio signal strength value for the Network Access Node is less than a predetermined clear channel assessment value.

In Example 24, the system of any one of Examples 1 to 22 is disclosed, further comprising the processing component excluding a Network Access Node from the synchronized transmission opportunity is disclosed, wherein a radio signal strength value for the Network Access Node is greater than a predetermined clear channel assessment value.

In Example 25, the system of any one of Examples 1 to 24 is disclosed, further comprising a memory, in which the processing component stores the transmission decision.

In Example 26, the system of any one of Examples 1 to 24 is disclosed, further comprising a memory, in which a Network Access Node stores the transmission decision.

In Example 27, the system of any one of Examples 1 to 26 is disclosed, further comprising the processing component determining whether each of the Network Access Nodes has a transmission of a wireless communication during the synchronized transmission opportunity.

In Example 28, the system of Example 27 is disclosed, further comprising the processing component determining that each of the Network Access Nodes completed transmission of the wireless communication during the synchronized transmission opportunity and terminating a transmission protocol for the Network Access Nodes.

In Example 29, the system of any one of Examples 1 to 28 is disclosed, further comprising a virtual machine manager, configured to create a client operating system to operate the system for central coordination of Network Access Nodes on an unlicensed frequency.

In Example 30, the system of any one of Examples 1 to 29 is disclosed, further comprising the processing component communicating a transmission decision to the Network Access Nodes using a message communication system.

In Example 31, the system of Example 30 is disclosed, wherein the message communication system is a C-MulteFire message system.

In Example 32, the system of Example 30 is disclosed, wherein the message communication system is a functional callback system.

In Example 33, the system of Example 30 is disclosed, wherein the message communication system is a virtual machine manager message system.

In Example 34, the system of any one of Examples 1 to 33 is disclosed, further comprising the processing component communicating a transmission decision to the Network Access Nodes using a message communication system is disclosed, wherein the message communication system is one of a C-MulteFire message system, a functional callback system, or a virtual machine manager message system.

In Example 35, the system of any one of Examples 1 to 34 is disclosed, further comprising the Network Access Nodes transmitting during a synchronized transmission opportunity based on a transmission decision received from the message communication system.

In Example 36, the system of any one of Examples 1 to 35 is disclosed, further comprising a plurality of Network Access Nodes performing a synchronized transmission opportunity is disclosed, wherein the synchronized transmission opportunity is of identical length for all Network Access Nodes.

In Example 37, the system of any one of Examples 1 to 36 is disclosed, further comprising a plurality of Network Access Nodes performing a synchronized transmission opportunity is disclosed, wherein the synchronized transmission opportunity has a common start time and a common end time for all transmitting Network Access Nodes.

In Example 38, a circuit configuration for central coordination of Network Access Nodes is disclosed, comprising:

a central logic circuit, configured to determine a transmission decision for a plurality of Network Access Nodes；

a random backoff management circuit, configured to determine a random backoff value；

a sensing circuit, configured to receive channel availability data； and

a storage element, configured to store a transmission decision； wherein

the random backoff management circuit generates a random backoff value；

the sensing circuit receives channel availability data from a plurality of Network Access Nodes during a period corresponding to the random backoff value； and

the central logic circuit determines a timing of a synchronized transmission opportunity；

determines a transmission decision for each of the plurality of Network Access Nodes based on the received channel availability data；

provides the transmission decision to the plurality of Network Access Nodes； and

In Example 39, the circuit configuration of Example 38 is disclosed, wherein the Network Access Nodes are Remote Radio Heads.

In Example 40, the circuit configuration of Example 38 is disclosed, wherein the Network Access Nodes are cloud radio access network base stations.

In Example 41, the circuit configuration of Example 38 is disclosed, wherein the Network Access Nodes are cloud Wi-Fi base stations.

In Example 42, the circuit configuration of any one of Examples 38 to 41 is disclosed, wherein the channel availability data are radio signal strength data.

In Example 43, the circuit configuration of any one of Examples 38 to 41 is disclosed, wherein the channel availability data are clear channel assessment data.

In Example 44, the circuit configuration of any one of Examples 38 to 41 is disclosed, wherein the channel availability data further comprise radio signal strength data and clear channel assessment data.

In Example 45, the circuit configuration of any one of Examples 38 to 44 is disclosed, further comprising the circuit configuration operating according to a MulteFire protocol.

In Example 46, the circuit configuration of any one of Examples 38 to 44 is disclosed, further comprising the circuit configuration operating according to a Wi-Fi protocol.

In Example 47, the circuit configuration of any one of Examples 38 to 44 is disclosed, further comprising the circuit configuration operating according to a Long Term Evolution Unlicensed protocol.

In Example 48, the circuit configuration of any one of Examples 38 to 44 is disclosed, further comprising the circuit configuration operating according to a Licensed Assisted Access protocol.

In Example 49, the circuit configuration of any one of Examples 38 to 44 is disclosed, further comprising the circuit configuration operating according to a Long Term Evolution Wi-Fi Link Aggregation protocol.

In Example 50, the circuit configuration of any one of Examples 38 to 49 is disclosed, further comprising the central logic circuit determining the random backoff value by multiplying a minimum time unit by a random or pseudorandom number.

In Example 51, the circuit configuration of Example 50 is disclosed, wherein the minimum time unit is a transmission time interval.

In Example 52, the circuit configuration of Example 50 is disclosed, wherein the minimum time unit is 4 microseconds.

In Example 53, the circuit configuration of Example 50 is disclosed, wherein the minimum time unit is a minimum time unit in a Wi-Fi or MulteFire protocol.

In Example 54, the circuit configuration of any one of Examples 50 to 53 is disclosed, wherein the random or pseudorandom number is a number ranging from zero to a clearance window.

In Example 55, the circuit configuration of nay one of Examples 50 to 54 is disclosed, wherein the random or pseudorandom number is a number ranging from zero to a clearance window, and wherein the clearance window has a clearance window minimum and a clearance window maximum.

In Example 56, the circuit configuration of any one of Examples 50 to 55 is disclosed, further comprising the central logic circuit recalculating a random backoff time for a Network Access Node not scheduled for transmission during a transmission opportunity by doubling the clearance window.

In Example 57, the circuit configuration of Examples 50 or 56 is disclosed, further comprising the central logic circuit identifying a clearance window that has exceeded the maximum clearance window and setting the clearance window equal to the minimum clearance window.

In Example 58, the circuit configuration of any one of Examples 38 to 57 is disclosed, further comprising the central logic circuit determining the transmission decision by comparing a radio signal strength with a predetermined clear channel assessment value.

In Example 59, the circuit configuration of any one of Examples 38 to 58 is disclosed, further comprising the central logic circuit determining the transmission decision of whether a Network Access Node will transmit at a next transmission opportunity using a comparison of a radio signal strength and a predetermined clear channel assessment value.

In Example 60, the circuit configuration of any one of Examples 38 to 59 is disclosed, further comprising the central logic circuit scheduling a Network Access Node for the synchronized transmission opportunity is disclosed, wherein a radio signal strength value for the Network Access Node is less than a predetermined clear channel assessment value.

In Example 61, the circuit configuration of any one of Examples 38 to 60 is disclosed, further comprising the central logic circuit excluding a Network Access Node from the synchronized transmission opportunity is disclosed, wherein a radio signal strength value for the Network Access Node is greater than a predetermined clear channel assessment value.

In Example 62, the circuit configuration of any one of Examples 38 to 61 is disclosed, further comprising a memory, in which the central logic circuit stores the transmission decision.

In Example 63, the circuit configuration of any one of Examples 38 to 61 is disclosed, further comprising a memory, in which a Network Access Node stores the transmission decision.

In Example 64, the circuit configuration of any one of Examples 38 to 63 is disclosed, further comprising the central logic circuit determining whether each of the Network Access Nodes has a transmission of a wireless communication during the synchronized transmission opportunity.

In Example 65, the circuit configuration of Example 64 is disclosed, further comprising the central logic circuit determining that each of the Network Access Nodes completed transmission of the wireless communication during the synchronized transmission opportunity and terminating a transmission protocol for the Network Access Nodes.

In Example 66, the circuit configuration of any one of Examples 38 to 65 is disclosed, further comprising a virtual machine manager, configured to create a client operating circuit configuration to operate the circuit configuration for central coordination of Network Access Nodes on an unlicensed frequency.

In Example 67, the circuit configuration of any one of Examples 38 to 66 is disclosed, further comprising the central logic circuit communicating a transmission decision to the Network Access Nodes using a message communication circuit configuration.

In Example 68, the circuit configuration of Example 67 is disclosed, wherein the message communication circuit configuration is a C-MulteFire message circuit configuration.

In Example 69, the circuit configuration of Example 67 is disclosed, wherein the message communication circuit configuration is a functional callback circuit configuration.

In Example 70, the circuit configuration of Example 67 is disclosed, wherein the message communication circuit configuration is a virtual machine manager message circuit configuration.

In Example 71, the circuit configuration of Example 67 is disclosed, wherein the message communication circuit configuration is one of a C-MulteFire message circuit configuration, a functional callback circuit configuration, or a virtual machine manager message circuit configuration.

In Example 72, the circuit configuration of any one of Examples 38 to 71 is disclosed, further comprising the Network Access Nodes transmitting during the synchronized transmission opportunity based on a transmission decision received from the message communication circuit configuration.

In Example 73, the circuit configuration of any one of Examples 38 to 72 is disclosed, further comprising a plurality of Network Access Nodes performing a synchronized transmission opportunity is disclosed, wherein the synchronized transmission opportunity is of identical length for all Network Access Nodes.

In Example 74, the circuit configuration of any one of Examples 38 to 73 is disclosed, further comprising a plurality of Network Access Nodes performing a synchronized transmission opportunity is disclosed, wherein the synchronized transmission opportunity has a common start time and a common end time for all transmitting Network Access Nodes.

In Example 75, an apparatus for central coordination of Network Access Nodes is disclosed, comprising:

a plurality of Network Access Nodes, configured to transmit and receive wireless signals；

a processing component, connected by optical cable to the plurality of Network Access Nodes；

wherein the processing component determines a timing of a synchronized transmission opportunity；

generates a random backoff value；

In Example 76, the apparatus of Example 75 is disclosed, wherein the Network Access Nodes are Remote Radio Heads.

In Example 77, the apparatus of Example 75 is disclosed, wherein the Network Access Nodes are cloud radio access network base stations.

In Example 78, the apparatus of Example 75 is disclosed, wherein the Network Access Nodes are cloud Wi-Fi base stations.

In Example 79, the apparatus of any one of Examples 75 to 78 is disclosed, wherein the channel availability data are radio signal strength data.

In Example 80, the apparatus of any one of Examples 75 to 78 is disclosed, wherein the channel availability data are clear channel assessment data.

In Example 81, the apparatus of any one of Examples 75 to 78 is disclosed, wherein the channel availability data further comprise radio signal strength data and clear channel assessment data.

In Example 82, the apparatus of any one of Examples 75 to 81 is disclosed, further comprising the apparatus operating according to a MulteFire protocol.

In Example 83, the apparatus of any one of Examples 75 to 81 is disclosed, further comprising the apparatus operating according to a Wi-Fi protocol.

In Example 84, the apparatus of any one of Examples 75 to 81 is disclosed, further comprising the apparatus operating according to a Long Term Evolution Unlicensed protocol.

In Example 85, the apparatus of any one of Examples 75 to 81 is disclosed, further comprising the apparatus operating according to a Licensed Assisted Access protocol.

In Example 86, the apparatus of any one of Examples 75 to 81 is disclosed, further comprising the apparatus operating according to a Long Term Evolution Wi-Fi Link Aggregation protocol.

In Example 87, the apparatus of any one of Examples 75 to 86 is disclosed, further comprising the processing component determining the random backoff value by multiplying a minimum time unit by a random or pseudorandom number.

In Example 88, the apparatus of Example 87 is disclosed, wherein the minimum time unit is a transmission time interval.

In Example 89, the apparatus of Example 87 is disclosed, wherein the minimum time unit is 4 microseconds.

In Example 90, the apparatus of Example 87 is disclosed, wherein the minimum time unit is a minimum time unit in a Wi-Fi or MulteFire protocol.

In Example 91, the apparatus of any one of Examples 87 to 90 is disclosed, wherein the random or pseudorandom number is a number ranging from zero to a clearance window.

In Example 92, the apparatus of one of Examples 87 to 91 is disclosed, wherein the random or pseudorandom number is a number ranging from zero to a clearance window, and wherein the clearance window has a clearance window minimum and a clearance window maximum.

In Example 93, the apparatus of Example 91 or 92 is disclosed, further comprising the processing component recalculating a random backoff time for a Network Access Node not scheduled for transmission during a transmission opportunity by doubling the clearance window.

In Example 94, the apparatus of any one of Examples 91 or 92 is disclosed, further comprising the processing component identifying a clearance window that has exceeded the maximum clearance window and setting the clearance window equal to the minimum clearance window.

In Example 95, the apparatus of any one of Examples 75 to 94 is disclosed, further comprising the processing component determining the transmission decision by comparing a radio signal strength with a predetermined clear channel assessment value.

In Example 96, the apparatus of any one of Examples 75 to 95 is disclosed, further comprising the processing component determining the transmission decision of whether a Network Access Node will transmit at a next transmission opportunity using a comparison of a radio signal strength and a predetermined clear channel assessment value.

In Example 97, the apparatus of any one of Examples 75 to 96 is disclosed, further comprising the processing component scheduling a Network Access Node for the synchronized transmission opportunity is disclosed, wherein a radio signal strength value for the Network Access Node is less than a predetermined clear channel assessment value.

In Example 98, the apparatus of any one of Examples 75 to 97 is disclosed, further comprising the processing component excluding a Network Access Node from the synchronized transmission opportunity is disclosed, wherein a radio signal strength value for the Network Access Node is greater than a predetermined clear channel assessment value.

In Example 99, the apparatus of any one of Examples 75 to 98 is disclosed, further comprising a memory, in which the processing component stores the transmission decision.

In Example 100, the apparatus of any one of Examples 75 to 99 is disclosed, further comprising a memory, in which a Network Access Node stores the transmission decision.

In Example 101, the apparatus of any one of Examples 75 to 100 is disclosed, further comprising the processing component determining whether each of the Network Access Nodes has a transmission of a wireless communication during the synchronized transmission opportunity.

In Example 102, the apparatus of Example 101 is disclosed, further comprising the processing component determining that each of the Network Access Nodes completed transmission of the wireless communication during the synchronized transmission opportunity and terminating a transmission protocol for the Network Access Nodes.

In Example 103, the apparatus of any one of Examples 75 to 102 is disclosed, further comprising a virtual machine manager, configured to create a client operating apparatus to operate the apparatus for central coordination of Network Access Nodes on an unlicensed frequency.

In Example 104, the apparatus of any one of Examples 75 to 103 is disclosed, further comprising the processing component communicating a transmission decision to the Network Access Nodes using a message communication apparatus.

In Example 105, the apparatus of Example 104 is disclosed, wherein the message communication apparatus is a C-MulteFire message apparatus.

In Example 106, the apparatus of Example 104 is disclosed, wherein the message communication apparatus is a functional callback apparatus.

In Example 107, the apparatus of Example 104 is disclosed, wherein the message communication apparatus is a virtual machine manager message apparatus.

In Example 108, the apparatus of any one of Examples 75 to 107 is disclosed, further comprising the processing component communicating a transmission decision to the Network Access Nodes using a message communication apparatus is disclosed, wherein the message communication apparatus is one of a C-MulteFire message apparatus, a functional callback apparatus, or a virtual machine manager message apparatus.

In Example 109, the apparatus of any one of Examples 75 to 108 is disclosed, further comprising the Network Access Nodes transmitting during the synchronized transmission opportunity based on a transmission decision received from the message communication apparatus.

In Example 110, the apparatus of any one of Examples 75 to 108 is disclosed, further comprising a plurality of Network Access Nodes performing a synchronized transmission opportunity is disclosed, wherein the synchronized transmission opportunity is of identical length for all Network Access Nodes.

In Example 111, the apparatus of any one of Examples 75 to 111 is disclosed, further comprising a plurality of Network Access Nodes performing a synchronized transmission opportunity is disclosed, wherein the synchronized transmission opportunity has a common start time and a common end time for all transmitting Network Access Nodes.

In Example 112, a method for central coordination of Network Access is disclosed, comprising:

determining a timing of a synchronized transmission opportunity；

generating a random backoff value；

receiving channel availability data from a plurality of Network Access Nodes during a period corresponding to the random backoff value；

determining a transmission decision for each of the plurality of Network Access Nodes based on the received channel availability data；

transmitting the transmission decision to the plurality of Network Access Nodes； and

performing wireless communication during the synchronized transmission opportunity via the Network Access Nodes selected for transmission based on the transmission decision.

In Example 113, the method of Example 112 is disclosed, wherein the Network Access Nodes are Remote Radio Heads.

In Example 114, the method of Example 112 is disclosed, wherein the Network Access Nodes are cloud radio access network base stations.

In Example 115, the method of Example 112 is disclosed, wherein the Network Access Nodes are cloud Wi-Fi base stations.

In Example 116, the method of any one of Examples 112 to 115 is disclosed, wherein the channel availability data are radio signal strength data.

In Example 117, the method of any one of Examples 112 to 115 is disclosed, wherein the channel availability data are clear channel assessment data.

In Example 118, the method of any one of Examples 112 to 115 is disclosed, wherein the channel availability data further comprise radio signal strength data and clear channel assessment data.

In Example 119, the method of any one of Examples 112 to 115 is disclosed, further comprising the method operating according to a MulteFire protocol.

In Example 120, the method of any one of Examples 112 to 115 is disclosed, further comprising the method operating according to a Wi-Fi protocol.

In Example 121, the method of any one of Examples 112 to 115 is disclosed, further comprising the method operating according to a Long Term Evolution Unlicensed protocol.

In Example 122, the method of any one of Examples 112 to 115 is disclosed, further comprising the method operating according to a Licensed Assisted Access protocol.

In Example 123, the method of any one of Examples 112 to 115 is disclosed, further comprising the method operating according to a Long Term Evolution Wi-Fi Link Aggregation protocol.

In Example 124, the method of any one of Examples 112 to 123 is disclosed, further comprising determining the random backoff value by multiplying a minimum time unit by a random or pseudorandom number.

In Example 125, the method of Example 124 is disclosed, wherein the minimum time unit is a transmission time interval.

In Example 126, the method of Example 124 or 125 is disclosed, wherein the minimum time unit is 4 microseconds.

In Example 127, the method of any one of Examples 124 to 126 is disclosed, wherein the minimum time unit is a minimum time unit in a Wi-Fi or MulteFire protocol.

In Example 128, the method of any one of Examples 124 to 127 is disclosed, wherein the random or pseudorandom number is a number ranging from zero to a clearance window.

In Example 129, the method of Example 128 is disclosed, further comprising the clearance window having a clearance window minimum and a clearance window maximum.

In Example 130, the method of Example 128 or 129 is disclosed, further comprising doubling the clearance window for a Network Access Node not scheduled for a synchronized transmission opportunity.

In Example 131, the method of any one of Examples 128 to 130 is disclosed, further comprising identifying a clearance window that has exceeded the maximum clearance window and setting the clearance window equal to the minimum clearance window.

In Example 132, the method of any one of Example 112 to 131 is disclosed, further comprising determining a transmission decision by comparing a radio signal strength with a clear channel assessment.

In Example 133, the method of any one of Example 112 to 132 is disclosed, further comprising determining a transmission decision of whether a Network Access Node will transmit at a next transmission opportunity using a comparison of the radio signal strength and the clear channel assessment.

In Example 134, the method of any one of Examples 112 to 133 is disclosed, further comprising including a Network Access Node within the synchronized transmission opportunity is disclosed, wherein a radio signal strength value for the Network Access Node is less than a clear channel assessment value.

In Example 135, the method of any one of Examples 112 to 134 is disclosed, further comprising excluding a Network Access Node from the synchronized transmission opportunity is disclosed, wherein a radio signal strength value for the Network Access Node is greater than a corresponding clear channel assessment value.

In Example 136, the method of any one of Examples 112 to 135 is disclosed, further comprising storing in a memory a determination of whether a Network Access Node is scheduled for transmission during the synchronized transmission opportunity.

In Example 137, the method of any one of Examples 112 to 136 is disclosed, further comprising determining that each of the Network Access Nodes completed a transmission during a transmission opportunity and terminating a transmission protocol for the Network Access Nodes.

In Example 138, the method of any one of Examples 112 to 137 is disclosed, further comprising a virtual machine manager, configured to create a client operating system.

In Example 139, the method of any one of Examples 112 to 138 is disclosed, further comprising the central logic circuit communicating a transmission decision to the Network Access Nodes using a message communication system.

In Example 140, the method of Example 139 is disclosed, wherein the message communication system is a C-MulteFire message system.

In Example 141, the method of Example 139 is disclosed, wherein the message communication system is a functional callback system.

In Example 142, the method of Example 139 is disclosed, wherein the message communication system is a virtual machine manager message system.

In Example 143, the method of Example 139 is disclosed, wherein the message communication system is any one of a C-MulteFire message system, a functional callback system, or a virtual machine manager message system.

In Example 144, the method of any one of Examples 139 to 143 is disclosed, further comprising the Network Access Nodes transmitting during the synchronized transmission opportunity based on a transmission decision received from the message communication system.

In Example 145, the method of any one of Examples 112 to 144 is disclosed, further comprising a plurality of Network Access Nodes performing a synchronized transmission opportunity is disclosed, wherein the synchronized transmission opportunity is of identical length for all Network Access Nodes.

In Example 146, the method of any one of Examples 112 to 144 is disclosed, further comprising a plurality of Network Access Nodes performing a synchronized transmission opportunity is disclosed, wherein the synchronized transmission opportunity has a common same start time and a common end time for all Network Access Nodes.

In Example 147, a means to centrally coordinate Network Access Nodes is disclosed, comprising, wherein said means:

determines a timing of a synchronized transmission opportunity；

generates a random backoff value；

transmits the transmission decision to the plurality of Network Access Nodes； and

In Example 148, a machine-readable storage including machine-readable instructions is disclosed, such that, when executed, to implement a method or realize an apparatus as Exampleed in any preceding Example.

In Example 149, a machine-readable medium including code, when executed, is disclosed, to cause a machine to perform the method of any one of Examples 40 to 74.

In Example 150, an apparatus for central coordination of Network Access Nodes is disclosed comprising:

wherein the processing component generates a random backoff value；

receives channel availability data from the plurality of Network Access Nodes during a period corresponding to the random backoff value；

determines a set of Network Access Nodes for a synchronized transmission opportunity based on the received channel availability data；

schedules a synchronized transmission opportunity for the set of Network Access Nodes for a wireless communication； and

performs wireless communication during the synchronized transmission opportunity using the set of Network Access Nodes.

In Example 151, the system of any one of Examples 1 to 37 is disclosed, wherein the system is configured to transmit on an unlicensed frequency.

In Example 152, the method of any one of Examples 112 to 146 is disclosed, further comprising centrally coordinating network access on an unlicensed frequency.

In Example 153, the circuit configuration of any one of Examples 38 to 74 is disclosed, wherein the circuit configuration centrally coordinates Network Access Nodes to perform wireless transmission on an unlicensed frequency.

In Example 154, the apparatus of any one of Examples 75 to 111 is disclosed, wherein comprising the apparatus is configured to transmit wireless signals on an unlicensed spectrum.

Claims

A system for central coordination of Network Access Nodes comprising:

a plurality of Network Access Nodes, configured to transmit and receive wireless signals；

a processing component, operatively coupled to the plurality of Network Access Nodes；

wherein the processing component determines a timing of a synchronized transmission opportunity；

generates a random backoff value；

receives channel availability data from a plurality of Network Access Nodes during a period corresponding to the random backoff value；

determines a transmission decision for each of the plurality of Network Access Nodes based on the received channel availability data； and

performs wireless communication during the synchronized transmission opportunity via the Network Access Nodes selected for transmission based on the transmission decision.
The system of claim 1, wherein the Network Access Nodes are Remote Radio Heads.
The system of claim 1 or 2, wherein the channel availability data further comprise radio signal strength data and clear channel assessment data.
The system of claim 1 or 2, further comprising the system operating according to a MulteFire protocol.
The system of claim 1 or 2, further comprising the system operating according to a Wi-Fi protocol.
The system of claim 1, further comprising the processing component determining the random backoff value by multiplying a minimum time unit by a random or pseudorandom number.
The system of claim 6, wherein the random or pseudorandom number is a number ranging from zero to a clearance window, and wherein the clearance window has a clearance window minimum and a clearance window maximum.
The system of claim 7, further comprising the processing component recalculating a random backoff value for a Network Access Node not scheduled for transmission during a transmission opportunity by doubling the clearance window.
The system of claim 7, further comprising the processing component identifying a clearance window that has exceeded the maximum clearance window and setting the clearance window equal to the minimum clearance window.
The system of claim 1, further comprising the processing component determining the transmission decision of whether a Network Access Node will transmit at a next transmission opportunity using a comparison of a radio signal strength and a predetermined clear channel assessment value.
The system of claim 1, further comprising the processing component scheduling a Network Access Node for the synchronized transmission opportunity, wherein a radio signal strength value for the Network Access Node is less than a predetermined clear channel assessment value.
The system of claim 1, further comprising the processing component excluding a Network Access Node from the synchronized transmission opportunity, wherein a radio signal strength value for the Network Access Node is greater than a predetermined clear channel assessment value.
The system of claim 1, further comprising a storage element, in which the processing component stores the transmission decision.
The system of claim 1, further comprising the processing component communicating a transmission decision to the Network Access Nodes using a message communication system, wherein the message communication system is one of a C-MulteFire message system, a functional callback system, or a virtual machine manager message system.
The system of claim 1, further comprising a plurality of Network Access Nodes performing a synchronized transmission opportunity, wherein the synchronized transmission opportunity is of identical length for all Network Access Nodes.
A circuit configuration for central coordination of Network Access Nodes comprising:

a central logic circuit, configured to determine a transmission decision for a plurality of Network Access Nodes；

a random backoff management circuit, configured to determine a random backoff value；

a sensing circuit, configured to receive channel availability data； and

a storage element, configured to store a transmission decision； wherein

the random backoff management circuit generates a random backoff value；

the sensing circuit receives channel availability data from a plurality of Network Access Nodes during a period corresponding to the random backoff value； and

the central logic circuit determines a timing of a synchronized transmission opportunity；

determines a transmission decision for each of the plurality of Network Access Nodes based on the received channel availability data；

provides the transmission decision to the plurality of Network Access Nodes； and performs wireless communication during the synchronized transmission opportunity via the Network Access Nodes selected for transmission based on the transmission decision.
The circuit configuration of claim 16, wherein the channel availability data further comprise radio signal strength data and clear channel assessment data.
The circuit configuration of claim 16, further comprising the central logic circuit determining the random backoff value by multiplying a minimum time unit by a random or pseudorandom number.
The circuit configuration of claim 16, further comprising the central logic circuit scheduling a Network Access Node for the synchronized transmission opportunity, wherein a radio signal strength value for the Network Access Node is less than a predetermined clear channel assessment value.
A method for central coordination of Network Access comprising:

determining a timing of a synchronized transmission opportunity；

generating a random backoff value；

receiving channel availability data from a plurality of Network Access Nodes during a period corresponding to the random backoff value；

determining a transmission decision for each of the plurality of Network Access Nodes based on the received channel availability data；

transmitting the transmission decision to the plurality of Network Access Nodes； and performing wireless communication during the synchronized transmission opportunity via the Network Access Nodes selected for transmission based on the transmission decision.
The method of claim 20, wherein the Network Access Nodes are Remote Radio Heads.
The method of claim 20, further comprising determining the random backoff value by multiplying a minimum time unit by a random or pseudorandom number.
The method of claim 22, wherein the minimum time unit is a transmission time interval.
The method of claim 20, further comprising determining a transmission decision of whether a Network Access Node will transmit at a next transmission opportunity using a comparison of radio signal strength and clear channel assessment.
The method of claim 20, further comprising excluding a Network Access Node from the synchronized transmission opportunity, wherein a radio signal strength value for the Network Access Node is greater than a corresponding clear channel assessment value.