GB2581173A - Resource allocation - Google Patents

Abstract

A method of managing pre-configured uplink transmission resources in a cellular wireless communications network. A base station of the cellular network transmits a request to the core network 201 for information regarding discontinuous reception (DRX) parameters for a user equipment (UE) connected to the base station. After receiving the DRX parameters the base station allocates 203 pre-configured uplink or downlink resources to the UE based at least in part on the DRX parameters. The information about the DRX parameters may indicate the location in time of paging occasions (PO) for the UE. This allows the base station to allocate pre-configured uplink resources such that they do not collide with paging occasions within the DRX cycle. A base station to perform the method is also provided.

Description

Resource Allocation

Technical Field

[1] The following disclosure relates to management of transmission resources in a cellular wireless communications network, and in particular to the allocation of uplink resources.

Background

[2] Wireless communication systems, such as the third-generation (3G) of mobile telephone standards and technology are well known. Such 3G standards and technology have been developed by the Third Generation Partnership Project (3GPP). The 3rd generation of wireless communications has generally been developed to support macro-cell mobile phone communications. Communication systems and networks have developed towards a broadband and mobile system.

[3] In cellular wireless communication systems User Equipment (UE) is connected by a wireless link to a Radio Access Network (RAN). The RAN comprises a set of base stations which provide wireless links to the UEs located in cells covered by the base station, and an interface to a Core Network (CN) which provides overall network control. As will be appreciated the RAN and CN each conduct respective functions in relation to the overall network. For convenience the term cellular network will be used to refer to the combined RAN & CN, and it will be understood that the term is used to refer to the respective system for performing the disclosed function.

[4] The 3rd Generation Partnership Project has developed the so-called Long Term Evolution (LTE) system, namely, the Evolved Universal Mobile Telecommunication System Territorial Radio Access Network, (E-UTRAN), for a mobile access network where one or more macro-cells are supported by a base station known as an eNodeB or eNB (evolved NodeB). More recently, LTE is evolving further towards the so-called 5G or NR (new radio) systems where one or more cells are supported by a base station known as a gNB. NR is proposed to utilise an Orthogonal Frequency Division Multiplexed (OFDM) physical transmission format.

[5] A trend in wireless communications is towards the provision of lower latency and higher reliability services. For example, NR is intended to support Ultra-reliable and low-latency communications (URLLC) and massive Machine-Type Communications (mMTC) are intended to provide low latency and high reliability for small packet sizes (typically 32 bytes). A user-plane latency of 1ms has been proposed with a reliability of 99.99999%, and at the physical layer a packet loss rate of 10-5 or 1O6 has been proposed.

[6] mMTC services are intended to support a large number of devices over a long life-time with highly energy efficient communication channels, where transmission of data to and from each device occurs sporadically and infrequently. For example, a cell may be expected to support many thousands of devices.

[7] Discontinuous Reception (DRX) is a process that allows a UE to shut down its receiver to conserve power during periods when no signals are expected. The UE wakes up at defined windows during which a signal may be transmitted to the UE. Typically the wake-up window is defined to coincide with paging occasions (PO) for the UE.

[8] A UE in Idle mode always uses DRX (iDRX) to reduce power consumption. While in idle mode the UE only has very limited communication with the base station and only wakes up from DRX at POs.

[9] A Paging Occasion (PO) is a subframe where P-RNTI may be transmitted on PDCCH to page the UE. The UE wakes up once per DRX cycle (T) for a PO that occurs in the cycle. A Paging Frame (PF) is one Radio Frame, which may contain one or multiple Paging Occasion(s).

[10] In order to reduce control signalling an eNB may allocate recurring uplink transmission resources to a UE using a technique known as Preconfigured Uplink Resources (PUR). PUR allows an eNB to allocate resources to a UE which that UE may then use for uplink transmission without first transmitting a grant request or random access request. The UE thus has recurring uplink transmission resources which it can utilise for transmissions as desired. Those resources occur at predictable times such that the UE can plan transmissions and there is no unpredictable latency such as during a grant request process.

[11] PURs may be available to a UE while in idle mode, such that the UE can wake up for the PUR, make its transmission, and then return to sleep.

[12] A difficulty may arise as, particularly during iDRX, the eNB is not always aware of when POs will occur and hence cannot schedule PURs with confidence that a collision with a PO will not occur. Collisions are clearly undesirable.

[13] There is therefore a requirement for a system which permits the use of PURs without a risk of collision with a PO, particularly when a UE is in idle mode and has very limited opportunities to communicate with a base station.

Summary

[14] This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.

[15] There is provided a method of managing pre-configured uplink transmission resources in a cellular wireless communications network, the method performed at a base station of the cellular wireless communications network and comprising the steps of transmitting a request to the core network of the cellular wireless communications network for information regarding DRX parameters for a UE connected to the base station; receiving from the core network information regarding DRX parameters for the UE; and allocating pre-configured uplink or downlink resources to the UE based at least in part upon the DRX parameters.

[16] The information regarding DRX parameters may indicate the location in time of Paging Occasions for the UE.

[17] The information regarding DRX parameters may be transmitted form the core network to the base station in an assistance information IE.

[18] The UE may be in iDRX while the method is performed.

[19] The pre-configured uplink resources may be located based on a time offset from each paging occasion of the UE.

[20] The time offset may be defined as a number of subframes.

[21] More than one discrete set of pre-configured uplink or downlink resources at different times may be allocated between adjacent paging occasions of the UE.

[22] The discrete sets of pre-configured uplink or downlink resources may be evenly distributed between paging occasions.

[23] The periodicity of the pre-configured uplink or downlink resources may be defined relative to the periodicity of the paging occasions.

[24] The periodicity of the pre-configured uplink or downlink resources may be defined relative to the periodicity of the DRX cycle.

[25] A fallback configuration may be provided in the event of a reconfiguration by which the paging occasions become too closely spaced to allow all pre-configured uplink or downlink resources to be utilised.

[26] All pre-configured uplink or downlink resources may occur in non-Paging Time Windows.

[27] At least some pre-configured uplink or downlink resources may occur in Paging Time Windows, optionally with different configuration to those occurring in non-Paging Time Windows.

[28] The DRX parameters may be eDRX parameters.

[29] The eDRX parameters may include at least one of hyperframe periodicity and Paging Timing Window length.

[30] There is also provided a base station configured to perform the method described herein.

[31] The non-transitory computer readable medium may comprise at least one from a group consisting of: a hard disk, a CD-ROM, an optical storage device, a magnetic storage device, a Read Only Memory, a Programmable Read Only Memory, an Erasable Programmable Read Only Memory, EPROM, an Electrically Erasable Programmable Read Only Memory and a Flash memory.

Brief description of the drawings

[32] Further details, aspects and embodiments of the invention will be described, by way of example only, with reference to the drawings. Elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. Like reference numerals have been included in the respective drawings to ease understanding.

[33] Figure 1 shows a schematic diagram of selected components of a cellular communications network; and [34] Figure 2 shows a method of PUR allocation. Detailed description of the preferred embodiments [35] Those skilled in the art will recognise and appreciate that the specifics of the examples described are merely illustrative of some embodiments and that the teachings set forth herein are applicable in a variety of alternative settings.

[36] Figure 1 shows a schematic diagram of three base stations (for example, eNB or gNBs depending on the particular cellular standard and terminology) forming a cellular network. Typically, each of the base stations will be deployed by one cellular network operator to provide geographic coverage for UEs in the area. The base stations form a Radio Area Network (RAN). Each base station provides wireless coverage for UEs in its area or cell. The base stations are interconnected via the X2 interface and are connected to the core network via the Si interface. As will be appreciated only basic details are shown for the purposes of exemplifying the key features of a cellular network.

[37] The base stations each comprise hardware and software to implement the RAN's functionality, including communications with the core network and other base stations, carriage of control and data signals between the core network and UEs, and maintaining wireless communications with UEs associated with each base station. The core network comprises hardware and software to implement the network functionality, such as overall network management and control, and routing of calls and data.

[38] Collisions between PO and PUR can be addressed by the UE taking the decision to ignore one of the two. That is, the UE may decide to ignore the PO and make a transmission in PUR, or ignore the PUR to listen to the PO. However, this may be undesirable as the UE must decide which of PO and PUR is less important and may make the incorrect choice.

[39] The UE may have a set preference whether to skip the PO or PUR. This choice can depend on various factors including the type of application currently utilizing communication resources. The UE may inform the cellular network that it will skip PO or PUR in case of a collision. This may enable the UE and eNB to better manage resources. For example, the network may not cancel a PUR allocation if nothing is received from the UE, but there is an indication the PUR will be skipped in case of a conflict. In order to avoid exchanging messages for configuring PUR, assistance information for PUR may be added to a previous message such as RRCConnectionRequest, RRCConnectionSetupComplete, etc. [40] If there is no preset preference, and a PO is skipped, the UE can use the PUR itself to inform the network of the skip. If the PUR is skipped, the cellular network should not count this towards a counter for implicit release of the PUR.

[41] If a DL period after PUR is defined, it may be possible to receive an RRC Paging message in the DL resources rather than during the PO. For non-time-sensitive applications this may not be disadvantageous provided the base station knows to make the transmission.

[42] The UE may inform the eNB of potential collisions. However, this is likely to be inefficient in the use of control signaling as the length of potential collisions is of undefined length, and potential collisions may not ultimately occur, for example if paging is not required during a PO, or there is no uplink data during the colliding PUR.

[43] Figure 2 shows a flow chart of a method for managing PUR allocations, particularly applicable where a UE is in iDRX.

[44] At step 200 an eNB intends to allocate PURs for a UE connected to the eNB. The UE may, or may not, be in iDRX. At step 201 the eNB transmits a message to the Core Network (CN) of the cellular network requesting information indicating the timing of POs for the UE. The information may be explicitly PO information or may be DRX information from which PO timing can be inferred. At step 202 the ON transmits the requested information to the eNB.

[45] As will be appreciated references to DRX are intended to cover all relevant types of DRX, in particular including eDRX. The principles disclosed herein may be particularly appropriate in conjunction with eDRX due to the extended length of sleep periods in eDRX. The parameters transmitted to the eNB may related to all types of DRX, or may be specific to one or more type of DRX.

[46] The requested information may be transmitted from the ON to eNB in an assistance information IF as set out in the following tables:- [47] Core Network Assistance Information IE/Group Name Presence Range IE type and Semantics

reference description

UE Identity M 9.3.x.x Index Value UE Specific DRX 0 Paging DRX 9.3.x.x UE extended DRX 0 Paging eDRX 9.3.x.x [48] Paging DRX IE/Group Name Presence Range IE type and Semantics

reference description

Paging DRX M ENUMERATED (32, 64, 128, 256, ...) [49] Paging eDRX IE/Group Presence Range IE type and reference Semantics

Name description

Paging eDRX Cycle M ENUMERATED (hfhalf, hf1, hf2, hf4, hf6, hf8, hf10, hf12, hf14, hf16, hf32, hf64, hf128, hf256, ...) TeDRx defined in TS 36.304 [20]. Unit: [number of hyperframes].

Paging Time Window 0 ENUMERATED (s1, s2, s3, s4, s5, s6, s7, s8, s9, s10, 511, s12, 513, 514, s15, s16, ...) Unit: [1.28 second].

[50] At step 203 the UE allocates PURs to avoid collisions with the POs indicated in the information received from the CN. For example, the PURs may be allocated with a small offset to the POs. Positioning the PURs close to, but not colliding with the POs, may be efficient for power consumption as the UE may only need to wake up once for both the PO and PUR. For example, the PUR may be defined at a fixed number of subframes from each PO occasion.

[51] Based on the received information the UE may schedule more than one occurrence of PURs in each time-period by ensuring all occurrences are in non-PTW (Paging Time Window) regions of the (e)DRX cycle. The non-PTVV region is typically significantly longer than the PTW region. It is also possible, in an alternative configuration, to locate PURs in PTW regions of the (e)DRX cycle.

[52] An additional PUR may be defined in a backup capacity. Reusing the parameters from DRX, resources according to the first PUR will be allocated at a predetermined offset (e.g. X subframes) after a missed PUR. The offset could also be negative, i.e. before the PO, but that may be more complicated and inefficient, needing to take into account the maximum possible repetitions.

[53] PUR cycle length may be the same, or a multiple of the DRX (PO) period. For example, PUR-period = {... 1/8, ... 1/2, 1, 2, ..., 8, ...} where a value of 1/8 indicates one PUR for every 8 POs, while a value of 8 may indicate 8 PURs after each PO.

[54] When more than one occurrence of PURs is allocated for each PO the PURs may be distributed in any convenient manner between POs. For example, the PURs may be spread evenly, or a set distance between each other. The first PUR may be set at predetermined distance from the preceding PO. The spread may be indicated by a specific indicator, for example PUS-spread = homogenous[True] could spread PURs evenly between POs, or PURspread = {1/4, 1/3, 2/3} to set 3 PURs to (rounded down) relative distances. Generally, the PUS locations may be defined relative to the PO spacing.

[55] Defining PURs relative to PO spacing may avoid reconfiguration when DRX parameters change as the elements of the system can re-calculate positions based on the spacing and relative positions. A fallback configuration may also be defined to be applied if there becomes insufficient space between POs for the configured number of PURs. This may be due to proximity of POs, or the number of repetitions required on the uplink. If there is not enough space for the configured PURs the number may be reduced according to a predetermined pattern. For example, 8-4-2-1-0 PURs between POs. Such a system may significantly reduce configuration signaling and help to mitigate the problem of configuring FUR on release.

[56] The parameters for configuring PURs may be optional and only transmitted if required, thus reducing control signaling. For example, a fallback procedure may not always be required.

[57] The above disclosure has been given in relation to allocation of PURs, but the same principles, methods, and systems are applicable to the allocation of Preconfigured Downlink Resources (PDRs). The examples disclosed herein should thus be read as referring to both PURs and PDRs.

[58] PURs are available for use by the UE according to the defined standards. Such standards not permit the UE to hold data which is ready for transmission until the next PURs, but rather require that only data ready for transmission immediately prior to the PURs is transmitted in the resources. These rules may be modified to permit UEs to retain data until PURs are available and transmit the data in those resources when they occur.

[59] Although not shown in detail any of the devices or apparatus that form part of the network may include at least a processor, a storage unit and a communications interface, wherein the processor unit, storage unit, and communications interface are configured to perform the method of any aspect of the present invention. Further options and choices are described below.

[60] The signal processing functionality of the embodiments of the invention especially the gNB and the UE may be achieved using computing systems or architectures known to those who are skilled in the relevant art. Computing systems such as, a desktop, laptop or notebook computer, hand-held computing device (PDA, cell phone, palmtop, etc.), mainframe, server, client, or any other type of special or general purpose computing device as may be desirable or appropriate for a given application or environment can be used. The computing system can include one or more processors which can be implemented using a general or special-purpose processing engine such as, for example, a microprocessor, microcontroller or other control module.

[61] The computing system can also include a main memory, such as random access memory (RAM) or other dynamic memory, for storing information and instructions to be executed by a processor. Such a main memory also may be used for storing temporary variables or other intermediate information during execution of instructions to be executed by the processor. The computing system may likewise include a read only memory (ROM) or other static storage device for storing static information and instructions for a processor.

[62] The computing system may also include an information storage system which may include, for example, a media drive and a removable storage interface. The media drive may include a drive or other mechanism to support fixed or removable storage media, such as a hard disk drive, a floppy disk drive, a magnetic tape drive, an optical disk drive, a compact disc (CD) or digital video drive (DVD) read or write drive (R or RVV), or other removable or fixed media drive. Storage media may include, for example, a hard disk, floppy disk, magnetic tape, optical disk, CD or DVD, or other fixed or removable medium that is read by and written to by media drive. The storage media may include a computer-readable storage medium having particular computer software or data stored therein.

[63] In alternative embodiments, an information storage system may include other similar components for allowing computer programs or other instructions or data to be loaded into the computing system. Such components may include, for example, a removable storage unit and an interface, such as a program cartridge and cartridge interface, a removable memory (for example, a flash memory or other removable memory module) and memory slot, and other removable storage units and interfaces that allow software and data to be transferred from the removable storage unit to computing system.

[64] The computing system can also include a communications interface. Such a communications interface can be used to allow software and data to be transferred between a computing system and external devices. Examples of communications interfaces can include a modem, a network interface (such as an Ethernet or other NIC card), a communications port (such as for example, a universal serial bus (USB) port), a PCMCIA slot and card, etc. Software and data transferred via a communications interface are in the form of signals which can be electronic, electromagnetic, and optical or other signals capable of being received by a communications interface medium.

[65] In this document, the terms 'computer program product', 'computer-readable medium' and the like may be used generally to refer to tangible media such as, for example, a memory, storage device, or storage unit. These and other forms of computer-readable media may store one or more instructions for use by the processor comprising the computer system to cause the processor to perform specified operations. Such instructions, generally 45 referred to as 'computer program code' (which may be grouped in the form of computer programs or other groupings), when executed, enable the computing system to perform functions of embodiments of the present invention. Note that the code may directly cause a processor to perform specified operations, be compiled to do so, and/or be combined with other software, hardware, and/or firmware elements (e.g., libraries for performing standard functions) to do so.

[66] The non-transitory computer readable medium may comprise at least one from a group consisting of: a hard disk, a CD-ROM, an optical storage device, a magnetic storage device, a Read Only Memory, a Programmable Read Only Memory, an Erasable Programmable Read Only Memory, EPROM, an Electrically Erasable Programmable Read Only Memory and a Flash memory. In an embodiment where the elements are implemented using software, the software may be stored in a computer-readable medium and loaded into computing system using, for example, removable storage drive. A control module On this example, software instructions or executable computer program code), when executed by the processor in the computer system, causes a processor to perform the functions of the invention as described herein.

[67] Furthermore, the inventive concept can be applied to any circuit for performing signal processing functionality within a network element. It is further envisaged that, for example, a semiconductor manufacturer may employ the inventive concept in a design of a stand-alone device, such as a microcontroller of a digital signal processor (DSP), or application-specific integrated circuit (ASIC) and/or any other sub-system element.

[68] It will be appreciated that, for clarity purposes, the above description has described embodiments of the invention with reference to a single processing logic. However, the inventive concept may equally be implemented by way of a plurality of different functional units and processors to provide the signal processing functionality. Thus, references to specific functional units are only to be seen as references to suitable means for providing the described functionality, rather than indicative of a strict logical or physical structure or organisation.

[69] Aspects of the invention may be implemented in any suitable form including hardware, software, firmware or any combination of these. The invention may optionally be implemented, at least partly, as computer software running on one or more data processors and/or digital signal processors or configurable module components such as FPGA devices.

[70] Thus, the elements and components of an embodiment of the invention may be physically, functionally and logically implemented in any suitable way. Indeed, the functionality may be implemented in a single unit, in a plurality of units or as part of other functional units. Although the present invention has been described in connection with some embodiments, it is not intended to be limited to the specific form set forth herein. Rather, the scope of the present invention is limited only by the accompanying claims. Additionally, although a feature may appear to be described in connection with particular embodiments, one skilled in the art would recognise that various features of the described embodiments may be combined in accordance with the invention. In the claims, the term 'comprising' does not exclude the presence of other elements or steps.

[71] Furthermore, although individually listed, a plurality of means, elements or method steps may be implemented by, for example, a single unit or processor. Additionally, although individual features may be included in different claims, these may possibly be advantageously combined, and the inclusion in different claims does not imply that a combination of features is not feasible and/or advantageous. Also, the inclusion of a feature in one category of claims does not imply a limitation to this category, but rather indicates that the feature is equally applicable to other claim categories, as appropriate.

[72] Furthermore, the order of features in the claims does not imply any specific order in which the features must be performed and in particular the order of individual steps in a method claim does not imply that the steps must be performed in this order. Rather, the steps may be performed in any suitable order. In addition, singular references do not exclude a plurality. Thus, references to 'a', 'an', 'first', 'second', etc. do not preclude a plurality.

[73] Although the present invention has been described in connection with some embodiments, it is not intended to be limited to the specific form set forth herein. Rather, the scope of the present invention is limited only by the accompanying claims. Additionally, although a feature may appear to be described in connection with particular embodiments, one skilled in the art would recognise that various features of the described embodiments may be combined in accordance with the invention. In the claims, the term 'comprising' or "including" does not exclude the presence of other elements.

Claims (16)

1. Claims 1. A method of managing pre-configured uplink transmission resources in a cellular wireless communications network, the method performed at a base station of the cellular wireless communications network and comprising the steps of transmitting a request to the core network of the cellular wireless communications network for information regarding DRX parameters for a UE connected to the base station; receiving from the core network information regarding DRX parameters for the UE; and allocating pre-configured uplink or downlink resources to the UE based at least in part upon the DRX parameters.
2. 2. A method according to claim 1, wherein the information regarding DRX parameters indicates the location in time of Paging Occasions for the UE.
3. 3. A method according to claim 1 or claim 2, wherein the information regarding DRX parameters is transmitted form the core network to the base station in an assistance information IF.
4. 4. A method according to any preceding claim, wherein the UE is in iDRX while the method is performed.
5. 5. A method according to any preceding claim, wherein the pre-configured uplink or downlink resources are located based on a time offset from each paging occasion of the UE.
6. 6. A method according to claim 5, wherein the time offset is defined as a number of subframes.
7. 7. A method according to any preceding claim, wherein more than one discrete set of pre-configured uplink or downlink resources at different times are allocated between adjacent paging occasions of the UE.
8. 8. A method according to claim 7, wherein the discrete sets of pre-configured uplink or downlink resources are evenly distributed between paging occasions.
9. 9. A method according to any preceding claim, wherein the periodicity of the pre-configured uplink or downlink resources is defined relative to the periodicity of the paging occasions.
10. 10. A method according to any of claims 1 to 7, wherein the periodicity of the pre-configured uplink or downlink resources is defined relative to the periodicity of the DRX cycle.
11. 11. A method according to claim 7, wherein a fallback configuration is provided in the event of a reconfiguration by which the paging occasions become too closely spaced to allow all pre-configured uplink or downlink resources to be utilised.
12. 12. A method according to any preceding claim, wherein all pre-configured uplink or downlink resources occur in non-Paging Time Windows.
13. 13. A method according to any of claims 1 to 11, wherein at least some pre-configured uplink or downlink resources occur in Paging Time Windows, optionally with different configuration to those occurring in non-Paging Time Windows.
14. 14. A method according to any preceding claim, wherein the DRX parameters are eDRX parameters.
15. 15. A method according to claim 14, wherein the eDRX parameters include at least one of hyperframe periodicity and Paging Timing Window length.
16. 16. A base station configured to perform the method of any of claims 1 to 15.