KR102642581B1 - Method and appratus for random access using layered preambles - Google Patents

Abstract

A random access technology using a hierarchical preamble is disclosed. A method of operating a terminal of a communication system, comprising: receiving quality requirement information and membership preamble information for preamble groups from a base station; selecting a preamble based on the quality requirement information and the belonging preamble information based on a terminal quality request; transmitting a first message including the selected preamble to the base station; And a method of operating a terminal may be provided, including receiving a second message that is a response signal to the first message from the base station.

Description

Random access method and device using hierarchical preamble {METHOD AND APPRATUS FOR RANDOM ACCESS USING LAYERED PREAMBLES}

The present invention relates to random access technology, and more specifically, to random access technology using a hierarchical preamble that allows controlling the possibility of collision and reception error rate according to the quality requirements of the terminal.

With the advancement of information and communication technology, various wireless communication technologies can be developed. Representative wireless communication technologies may include long term evolution (LTE) and new radio (NR), which are defined in the 3rd generation partnership project (3GPP) standard. LTE may be a wireless communication technology among 4G (4th Generation) wireless communication technologies, and NR may be a wireless communication technology among 5G (5th Generation) wireless communication technologies.

In order to handle the rapid increase in wireless data after the commercialization of the 4G communication system (e.g., a communication system supporting LTE), the frequency band of the 4G communication system (e.g., a frequency band below 6 GHz) as well as the 4G communication system A 5G communication system (e.g., a communication system supporting NR) that uses a frequency band higher than the frequency band (e.g., a frequency band of 6 GHz or higher) may be considered. The 5G communication system can support enhanced Mobile BroadBand (eMBB), Ultra-Reliable and Low Latency Communication (URLLC), and massive Machine Type Communication (mMTC).

In such wireless communication technology, the terminal can randomly select a preamble and attempt random access to the base station. Accordingly, a collision may occur when multiple terminals attempt to access the base station using the same preamble. To solve this problem, a method may be known in which the base station controls the area of accessible resources according to the quality-of-service (QoS) requirements of the terminal, assuming uniform preamble resources. However, through this method, the base station can reduce the possibility of collision for a terminal requiring high quality, but it cannot reduce the reception error rate after avoiding collision.

The purpose of the present invention to solve the above problems is to provide a random access method and device using a hierarchical preamble that can reduce the possibility of collision for a terminal requiring high quality and reduce the reception error rate after avoiding collision. It is provided.

The random access method using a hierarchical preamble according to the first embodiment of the present invention to achieve the above object is a method of operating a terminal in a communication system, and includes quality requirement information for preamble groups from a base station and the preamble groups. Receiving preamble information for each member; selecting one preamble group from among the preamble groups based on the quality requirement information based on a terminal quality request; selecting a preamble within the one preamble group based on the belonging preamble information; transmitting a first message including the selected preamble to the base station; And it may include receiving a second message that is a response signal to the first message from the base station.

Here, the preamble groups are composed of a first preamble group and a second preamble group formed by dividing a raw preamble group composed of CAZAC (constant amplitude zero autocorrelation) sequences with a prime sequence length based on mutual correlation, The intercorrelation of preambles belonging to the first preamble group may be smaller than the intercorrelation of preambles belonging to the second preamble group.

Here, the CAZAC sequence is a Zadoff-Chu sequence, and the prime number may be any one of 839 and 139.

Here, the method may further include receiving transmission power information about the preamble groups from the base station, and the selected preamble may be transmitted using transmission power according to the transmission power information.

Here, the preamble groups include preamble group 1 for a first type of terminal whose quality request delay time is less than a threshold and preamble group 2 for a second type of terminal whose quality request delay time is more than a threshold, and the first The transmission power for preamble group 1 may be greater than the transmission power for the second preamble group 2.

Here, it further includes receiving configuration information of a random access channel (RACH) occurrence bundle and the number of RACH occurrences included in the RACH occurrence bundle from the base station, and the selected preamble is included in the configuration information. It can be transmitted in the RACH organization indicated by .

Here, the first message may be MsgA, and the second message may be MsgB.

Meanwhile, the random access method using a hierarchical preamble according to the second embodiment of the present invention to achieve the above object is a method of operating a base station in a communication system, and includes preamble groups, preambles belonging to the preamble groups, and the preamble. Establishing groups' quality requirements; Transmitting preamble group setting information including information about the preamble groups, information about the belonging preambles, and information about the quality requirements to a terminal; Receiving a first message including a preamble selected based on the preamble group setting information according to a quality requirement from the terminal; detecting the preamble in the first message; And it may include transmitting a second message that is a response signal to the first message to the terminal.

Here, the step of setting the preamble groups, belonging preambles, and quality requirements includes forming an original preamble group whose preambles are CAZAC sequences with a prime sequence length; allocating the preambles in the original preamble group to the belonging preambles of the preamble groups; and setting the quality requirements for the preamble groups.

Here, the step of allocating the preambles in the raw preamble group to the belonging preambles of the preamble groups includes excluding preambles having a cross-correlation value of a first threshold or more from the preambles in the raw preamble group; calculating a cross-correlation of the remaining preambles in the original preamble group; and allocating the remaining preambles to the belonging preambles of the preamble groups based on the calculated cross-correlation.

Here, setting the quality requirements for the preamble groups includes setting quality requirement steps by distinguishing quality requirement criteria; and mapping the quality requirement steps to the preamble groups.

Here, the step of setting the quality requirements for the preamble groups includes setting the quality requirements for the preamble groups using quality request specifiers that indicate a preamble group that the base station can select. It can be characterized.

Here, the step of detecting the preambles in the first message includes calculating the correlation by applying the preamble matrix of one preamble group to the received signal matrix of the first messages received from a plurality of terminals including the terminal. step; detecting preambles belonging to one preamble group using the calculated correlation; removing received signals corresponding to the detected preambles from the received signal matrix; and detecting the preamble from the first message by detecting preambles belonging to the remaining preamble groups in the received signal matrix from which the received signal has been removed.

Meanwhile, a random access device using a hierarchical preamble according to a third embodiment of the present invention to achieve the above object includes, as a terminal, a processor; a memory that communicates electronically with the processor; and instructions stored in the memory, and when the instructions are executed by the processor, the instructions provide the terminal with quality requirement information for preamble groups from the base station and each of the preamble groups. Receive affiliation preamble information for; selecting one preamble group from among the preamble groups based on the quality requirement information based on a terminal quality request; select a preamble within the one preamble group based on the belonging preamble information; transmitting a first message including the selected preamble to the base station; and may operate to cause the base station to receive a second message that is a response signal to the first message.

Here, the preamble groups are composed of a first preamble group and a second preamble group formed by dividing a raw preamble group composed of CAZAC sequences with a decimal sequence length based on mutual correlation, and belong to the first preamble group. The inter-correlation of preambles may be smaller than the inter-correlation of preambles belonging to the second preamble group.

Here, the commands operate to further cause the terminal to receive transmission power information for the preamble groups from the base station, and the selected preamble is transmitted using transmission power according to the transmission power information. It can operate to cause.

Here, the commands operate to further cause the terminal to receive a RACH application bundle and configuration information of the number of RACH applications included in the RACH application bundle from the base station, and the selected preamble is included in the configuration information. It may operate to cause transmission in the RACH direction indicated by.

The base station can configure preambles that reflect the various quality requirement levels of the terminals and provide them to the terminals.

Additionally, terminals can attempt random access by selecting a preamble according to a desired quality requirement level from preambles reflecting various quality requirement levels and transmitting it to the base station.

Additionally, random access capacity can be increased by allowing the base station to configure preambles according to quality requirement levels and use them for random access of the terminal.

In addition, the base station configures preambles according to quality requirement levels and uses them for random access of the terminal, thereby reducing the possibility of preamble collision for a terminal that requires a high quality requirement level.

In addition, the base station can configure a preamble that can accommodate various quality requirement levels and provide it to the terminal, thereby avoiding preamble collisions and lowering the reception error rate.

1 is a conceptual diagram showing a first embodiment of a communication system.
Figure 2 is a block diagram showing a first embodiment of a communication node constituting a communication system.
Figure 3 is a conceptual diagram showing a second embodiment of a communication system.
Figure 4 is a flowchart showing a first embodiment of a random access method using a hierarchical preamble.
FIG. 5 is a flowchart showing a first embodiment of a process for setting preamble groups in FIG. 4.
FIG. 6 is a flowchart showing a first embodiment of the preamble selection process of FIG. 4.
Figure 7 is a conceptual diagram showing a first embodiment of preamble indexes for each preamble group.
FIG. 8 is a flowchart showing a first embodiment of the preamble detection process of FIG. 4.

Since the present invention can make various changes and have various embodiments, specific embodiments will be illustrated in the drawings and described in detail. However, this is not intended to limit the present invention to specific embodiments, and should be understood to include all changes, equivalents, and substitutes included in the spirit and technical scope of the present invention. The embodiments illustrated and described in detail in the drawings can be applied to a 2 step random access procedure and a 4 step random access procedure.

Terms such as first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The above terms are used only for the purpose of distinguishing one component from another. For example, a first component may be named a second component, and similarly, the second component may also be named a first component without departing from the scope of the present invention. The term and/or includes any of a plurality of related stated items or a combination of a plurality of related stated items.

When a component is said to be "connected" or "connected" to another component, it is understood that it may be directly connected to or connected to the other component, but that other components may exist in between. It should be. On the other hand, when it is mentioned that a component is “directly connected” or “directly connected” to another component, it should be understood that there are no other components in between.

The terms used in this application are only used to describe specific embodiments and are not intended to limit the invention. Singular expressions include plural expressions unless the context clearly dictates otherwise. In this application, terms such as “comprise” or “have” are intended to designate the presence of features, numbers, steps, operations, components, parts, or combinations thereof described in the specification, but are not intended to indicate the presence of one or more other features. It should be understood that this does not exclude in advance the possibility of the existence or addition of elements, numbers, steps, operations, components, parts, or combinations thereof.

Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by a person of ordinary skill in the technical field to which the present invention pertains. Terms defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the context of the related technology, and unless explicitly defined in the present application, should not be interpreted in an idealized or excessively formal sense. No.

Hereinafter, preferred embodiments of the present invention will be described in more detail with reference to the attached drawings. In order to facilitate overall understanding when describing the present invention, the same reference numerals are used for the same components in the drawings, and duplicate descriptions for the same components are omitted.

1 is a conceptual diagram showing a first embodiment of a communication system.

Referring to FIG. 1, the communication system 100 includes a plurality of communication nodes 110-1, 110-2, 110-3, 120-1, 120-2, 130-1, 130-2, 130-3, 130-4, 130-5, 130-6). Here, the communication system may be referred to as a “communication network”. Each of the plurality of communication nodes may support at least one communication protocol. For example, each of the plurality of communication nodes may use a communication protocol based on code division multiple access (CDMA), a communication protocol based on wideband CDMA (WCDMA), a communication protocol based on time division multiple access (TDMA), and a frequency division multiple access (FDMA)-based communication protocol. access)-based communication protocol, OFDM (orthogonal frequency division multiplexing)-based communication protocol, OFDMA (orthogonal frequency division multiple access)-based communication protocol, SC (single carrier)-FDMA-based communication protocol, NOMA (non-orthogonal multiple access) access)-based communication protocols, SDMA (space division multiple access)-based communication protocols, etc. Each of the plurality of communication nodes may have the following structure.

Figure 2 is a block diagram showing a first embodiment of a communication node constituting a communication system.

Referring to FIG. 2, the communication node 200 may include at least one processor 210, a memory 220, and a transmitting and receiving device 230 that is connected to a network and performs communication. Additionally, the communication node 200 may further include an input interface device 240, an output interface device 250, a storage device 260, etc. Each component included in the communication node 200 is connected by a bus 270 and can communicate with each other. However, each component included in the communication node 200 may be connected through an individual interface or individual bus centered on the processor 210, rather than the common bus 270. For example, the processor 210 may be connected to at least one of the memory 220, the transmission/reception device 230, the input interface device 240, the output interface device 250, and the storage device 260 through a dedicated interface. .

The processor 210 may execute a program command stored in at least one of the memory 220 and the storage device 260. The processor 210 may refer to a central processing unit (CPU), a graphics processing unit (GPU), or a dedicated processor on which methods according to embodiments of the present invention are performed. Each of the memory 220 and the storage device 260 may be comprised of at least one of a volatile storage medium and a non-volatile storage medium. For example, the memory 220 may be comprised of at least one of read only memory (ROM) and random access memory (RAM).

Referring again to FIG. 1, the communication system 100 includes a plurality of base stations (110-1, 110-2, 110-3, 120-1, 120-2) and a plurality of terminals. It may include (130-1, 130-2, 130-3, 130-4, 130-5, 130-6). Each of the first base station 110-1, the second base station 110-2, and the third base station 110-3 may form a macro cell. Each of the fourth base station 120-1 and the fifth base station 120-2 may form a small cell. The fourth base station 120-1, the third terminal 130-3, and the fourth terminal 130-4 may belong to the coverage of the first base station 110-1. The second terminal 130-2, the fourth terminal 130-4, and the fifth terminal 130-5 may belong to the coverage of the second base station 110-2. The fifth base station 120-2, the fourth terminal 130-4, the fifth terminal 130-5, and the sixth terminal 130-6 may belong to the coverage of the third base station 110-3. . The first terminal 130-1 may belong to the coverage of the fourth base station 120-1. The sixth terminal 130-6 may belong to the coverage of the fifth base station 120-2.

Here, each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 includes a NodeB, an evolved NodeB, a base transceiver station (BTS), Radio base station, radio transceiver, access point, access node, road side unit (RSU), digital unit (DU), cloud digital unit (CDU) , may be referred to as a radio remote head (RRH), radio unit (RU), transmission point (TP), transmission and reception point (TRP), relay node, etc. A plurality of terminals (130-1, 130-2, 130-3, 130-4, 130-5, 130-6) each include an access terminal, a mobile terminal, a station, It may be referred to as a subscriber station, mobile station, portable subscriber station, user equipment (UE), node, device, etc.

A plurality of communication nodes (110-1, 110-2, 110-3, 120-1, 120-2, 130-1, 130-2, 130-3, 130-4, 130-5, 130-6) Each may support cellular communication (e.g., long term evolution (LTE), advanced (LTE-A), etc. defined in the 3rd generation partnership project (3GPP) standard). Each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 may operate in a different frequency band or may operate in the same frequency band. Each of the plurality of base stations (110-1, 110-2, 110-3, 120-1, 120-2) may be connected to each other through ideal backhaul or non-ideal backhaul, and ideal backhaul Alternatively, information can be exchanged with each other through non-ideal backhaul. Each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 may be connected to a core network (not shown) through ideal backhaul or non-ideal backhaul. Each of the plurality of base stations (110-1, 110-2, 110-3, 120-1, 120-2) transmits the signal received from the core network to the corresponding terminal (130-1, 130-2, 130-3, 130). -4, 130-5, 130-6), and the signal received from the corresponding terminal (130-1, 130-2, 130-3, 130-4, 130-5, 130-6) is sent to the core network. can be transmitted to.

Each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 can support OFDMA-based downlink (DL) transmission and SC-FDMA-based uplink. (uplink, UL) transmission can be supported. In addition, each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 transmits multiple input multiple output (MIMO) (e.g., single user (SU)-MIMO, MU (multi user)-MIMO, massive MIMO, etc.), CoMP (coordinated multipoint) transmission, carrier aggregation transmission, transmission in unlicensed band, device to device (D2D) ) may support communication (or ProSe (proximity services), etc. Here, each of the plurality of terminals (130-1, 130-2, 130-3, 130-4, 130-5, 130-6) is a base station Operations corresponding to (110-1, 110-2, 110-3, 120-1, 120-2), by the base station (110-1, 110-2, 110-3, 120-1, 120-2) Supported operations can be performed.

For example, the second base station 110-2 may transmit a signal to the fourth terminal 130-4 based on the SU-MIMO method, and the fourth terminal 130-4 may transmit a signal to the fourth terminal 130-4 based on the SU-MIMO method. A signal can be received from the second base station 110-2. Alternatively, the second base station 110-2 may transmit a signal to the fourth terminal 130-4 and the fifth terminal 130-5 based on the MU-MIMO method, and the fourth terminal 130-4 and the fifth terminal 130-5 can each receive a signal from the second base station 110-2 by the MU-MIMO method. Each of the first base station 110-1, the second base station 110-2, and the third base station 110-3 may transmit a signal to the fourth terminal 130-4 based on the CoMP method, and the fourth terminal 130-4 may transmit a signal to the fourth terminal 130-4. The terminal 130-4 can receive signals from the first base station 110-1, the second base station 110-2, and the third base station 110-3 using the CoMP method. Each of the plurality of base stations (110-1, 110-2, 110-3, 120-1, 120-2) has a terminal (130-1, 130-2, 130-3, 130-4, Signals can be transmitted and received based on 130-5, 130-6) and CA methods. The first base station 110-1, the second base station 110-2, and the third base station 110-3 each coordinate D2D communication between the fourth terminal 130-4 and the fifth terminal 130-5. (coordination), and each of the fourth terminal 130-4 and the fifth terminal 130-5 communicates D2D through coordination with each of the second base station 110-2 and the third base station 110-3. can be performed.

Meanwhile, in such a communication system, the terminal can randomly select a preamble and attempt random access to the base station. Accordingly, collisions may occur when multiple terminals access the base station using the same preamble. If a preamble collision occurs like this, the base station may have difficulty receiving the preamble. To solve this, the base station can reduce the possibility of collision by increasing the number of preambles. However, if the length of the preamble is constant, the correlation also increases with the number of preambles, and the signal quality of the received signal received by the base station may decrease due to the increasing number of preambles. Moreover, in cases where the quality requirements (QoS) required by the terminal are diverse, the base station can operate limited preamble resources accordingly. In this regard, there may be a known method for the base station to control the area of accessible resources according to the quality requirements (QoS) of the terminal, assuming uniform preamble resources. However, through this method, the base station can reduce the possibility of collision for a terminal requiring high quality, but it cannot reduce the reception error rate after avoiding collision. Accordingly, there may be a need for a random access method and device using a hierarchical preamble that can reduce the possibility of collision for a terminal that requires high quality in a communication system and at the same time reduce the reception error rate after avoiding collision.

Meanwhile, for convenience of explanation here, quality requirements can be assumed to be in two stages. However, quality requirements can extend to several levels. Parameters of these quality requirements may include latency. Accordingly, quality requirements can be divided into quality requirement level 1, which must guarantee a short delay time, and quality requirement level 2, which allows a relatively long delay time. Here, a short delay time may mean a delay time of less than 1 ms, and a long delay time may mean a delay time of 1 ms or more. Accordingly, there may be first-type terminals that require a short delay time and must satisfy quality requirement level 1, and there may be second-type terminals that allow relatively long delay times and may satisfy quality requirement level 2. there is.

Figure 3 is a conceptual diagram showing a second embodiment of a communication system.

Referring to FIG. 3, the communication system may consist of a base station 310 and N terminals 320-1 to 320-N. Here, the base station 310 may have M receiving antennas, and the terminals 320-1 to 320-N may have one transmitting antenna. N terminals 320-1 to 320-N can transmit preambles and data to the base station 320 in synchronization. Here, N may be equal to or smaller than M. N and M can be natural numbers. In this way, the communication system may be composed of a base station 310 and a large number of terminals (320-1 to 320-N) synchronized to the base station 310. A large number of terminals (320-1 to 320-N) ), some terminals may be activated from time to time and transmit data to the base station 310 through a random access procedure. The random access procedure may start when the activated terminal transmits a preamble signal. Then, the base station 310 may be activated. The preamble can be detected by receiving a preamble signal from the activated terminal. The base station 310 can send a random access response to the activated terminal according to the detected preamble. In the random access procedure, several terminals The same preamble can be selected and the same preamble signal can be transmitted to the base station 310. In this way, if several terminals select the same preamble and transmit the same preamble signal, the base station 310 cannot distinguish between each terminal and random access of the terminals fails. This can be done. If the base station 310 allocates a unique preamble to all terminals 320-1 to 320-N, the risk of collision can be avoided. However, in an MTC (machine type communication) application, terminals 320 -1~320-N) may be very numerous, so if a unique preamble is assigned to all terminals (320-1~320-N), the signal space may become excessively large. At this time, all terminals (320- When the ratio of active terminals is small compared to 1~320-N), the base station 310 can control the risk of collision even if the preamble is shared.

In general, the lower the peak-to-average power ratio (PAPR) of the preamble signal transmitted by the terminal, the higher the efficiency of the power amplifier. Additionally, if the preamble signals transmitted by the terminal configure the signal space to be orthogonal to each other, the base station can use a linear reception device. This characteristic of the preamble signal is called CAZAC (constant amplitude zero autocorrelation), and this can be satisfied by Zadoff-Chu sequence, Alltop sequence, etc. For example, sequence length A sequence where is a prime number Can be defined as Equation 1 below. here, may be any one of 839 and 139. here, may be a root sequence index, may be an integer, It can be. and, may be a cyclic shift value. and, may be a sample index, may be an integer, and It can be.

Figure 4 is a flowchart showing a first embodiment of a random access method using a hierarchical preamble.

Referring to FIG. 4, in the random access method using a hierarchical preamble, the base station can set a quality request level (S410). Here, the base station may set the quality requirement level to level 2, for example. However, the quality requirement level can be extended to several levels. Parameters for setting these quality requirement levels may include delay time. Accordingly, the base station can set the quality requirement level by dividing it into quality requirement level 1, which requires a short delay time, and quality requirement level 2, which requires a relatively long delay time. Here, a short delay time may mean a delay time of less than 1 ms, and a long delay time may mean a delay time of 1 ms or more. Next, the base station can set preamble groups (S420). Additionally, the base station can map the set preamble groups to each quality requirement level.

FIG. 5 is a flowchart showing a first embodiment of a process for setting preamble groups in FIG. 4.

Referring to FIG. 5, in the process of setting preamble groups, the base station sets the sequence length to a decimal number according to Equation 1. CAZAC sequences can be generated (S421). And, the base station can form a raw preamble group using the generated CAZAC sequences as preambles. Here, the number of preambles constituting the raw preamble group is It could be a dog. For example, if the prime number is 839, the number of preambles forming the raw preamble group may be 838*839=703,082. And, the raw preamble group is small If is 839, set It can be expressed as and can be defined as Equation 2 below.

Next, the base station may exclude some preambles with high mutual correlation from the preambles constituting the raw preamble group (S423). That is, the base station is included in the raw preamble group. By calculating the cross-correlation for the preambles, preambles corresponding to the calculated cross-correlation is greater than or equal to the first threshold can be excluded. Here, the first threshold may be a value preset in the base station by the administrator. In particular, if a Doppler shift occurs due to the terminal moving at high speed, or if delay spread occurs due to a signal transmitted from the terminal reaching the base station through multiple paths, a preamble with an adjacent cyclic shift Interference may increase and correlation may increase. The base station cyclically shifts on the raw preamble group. subsampling interval By selecting the corresponding preambles, some preambles whose cross-correlation may exceed the first threshold can be excluded. At this time, the base station uses a subsampling interval in the raw preamble group. When is 22, the raw preamble group consisting of the corresponding preambles is a set It can be expressed as Equation 3 below. here, can mean the number of samples, decimal can be 839, and the subsampling interval is If is 22 may be 39 or less. set can have 838*39=32682 elements.

Next, the base station A preamble with low cross-correlation in the raw preamble group consisting of the remaining preambles from the preambles. Preamble group 1 can be formed by selecting one (S424). That is, the base station A preamble whose cross-correlation is less than or equal to the second threshold in the raw preamble group consisting of the remaining preambles from the preambles. You can select any number to form preamble group 1. Here, preamble group 1 may be preambles suitable for use by first type terminals. In this way, the base station can use the second threshold as a standard for selecting some preambles with low mutual correlation from the raw preamble group. For example, if the second threshold is 0, the sample index Number of samples in preambles where is 0 Cyclic shift to 39 You can form an orthogonal preamble group by taking . or by allowing a higher second threshold, the sample index Number of samples in preambles with 1 Cyclic shift to 25 by adding Preamble group 1 with 64 can be formed. At this time, preamble group 1 formed in this way is a set It can be expressed as and can be configured as in Equation 4.

Next, the base station can form preamble group 2 by excluding preamble group 1 from the raw preamble group (S425). In other words, the base station is a set of raw preamble groups excluding some preambles. Set of preamble group 1 in Set of preamble group 3 excluding can be formed, at this time, the set Can be expressed as Equation 5 below.

Meanwhile, the 3GPP NR standard can specify up to two groups (A/B) of preamble. Additionally, the terminal can select a group based on the reference signal received power (RSRP) measurement and the size of the message (MsgA). However, the 3GPP NR standard divides up to 64 preambles into two groups, which may be insufficient to support preambles allocated to the second type UE. Therefore, the base station Preamble group 2, consisting of preambles, can be newly defined. Setting information for preamble group 2 is , power offset information for group A/B, and judgment criteria according to the urgency of the message. For example, the base station When setting, you can specify the ratio to the maximum value. Additionally, the base station can set the power offset to a value of 0 dB or less.

Again, referring to FIG. 4, the base station may transmit system information and/or a radio resource control (RRC) message including preamble group configuration information to the terminals (S430). Accordingly, terminals can receive system information and/or RRC messages including preamble group configuration information from the base station. Here, the preamble group setting information may include information about the set preamble groups and quality requirement information indicating the degree of quality requirement required by the set preamble groups. Additionally, the preamble group setting information may include setting information of transmission power to be used for transmitting the set preamble groups. Here, the information about the preamble groups may include information that the set preamble groups are preamble group 1 and preamble group 2. Additionally, the information about the preamble groups may include information about the affiliated preambles included in preamble group 1 and the affiliated preambles included in preamble group 2. In addition, the setting information of the transmission power to be used for transmitting preamble groups can be set to a first transmission power in preamble group 1, a second transmission power to be set in preamble group 2, and the first transmission power is greater than the second transmission power. You can. Next, the quality requirement information may include that the set quality requirement stages consist of quality requirement stage 1 and quality requirement stage 2.

Additionally, the quality requirement information may include quality requirement standards that indicate the level of quality required by each quality requirement step. For example, the quality requirement information may include a quality requirement standard that quality requirement level 1 has a delay time of less than 1 ms, and quality requirement step 2 may include a quality requirement standard that the delay time is 1 ms or more. In contrast, the quality requirement information may include a quality requirement specifier indicating a preamble group that can be selected based on a requirement threshold. Here, the quality request indicator may, for example, instruct to select a preamble from preamble group 2 only when the quality request is below the request threshold. Looking at this in detail, the quality request indicator may instruct to select a preamble from preamble group 2 only when the delay time constituting the quality request is less than or equal to the delay threshold. At this time, the delay threshold may be 1ms. In this way, the communication system can additionally set preamble group 2 to absorb the connection demand of terminals trying to connect to group A/B, and the effect of making the connection of group A/B more smooth can be expected.

Next, the terminals can select preambles according to the desired quality requirements based on the preamble group setting information in the system information (S440). For example, when a terminal requires a quality delay of 1 ms or less, it can select one preamble from the preambles belonging to preamble group 2.

FIG. 6 is a flowchart showing a first embodiment of the preamble selection process of FIG. 4.

Referring to FIG. 6, during the preamble selection process, the terminals determine whether the desired quality request belongs to quality request level 1 or quality request level 2 based on the quality requirement information of the preamble group setting information in the system information and/or RRC message. It is possible to determine whether it belongs (S441). Afterwards, the terminals can select preamble groups according to the quality requirement levels determined based on the quality requirement information (S442). For example, UEs can select preamble group 1 if the desired quality requirement satisfies the quality requirement criteria of quality requirement level 1. In contrast, UEs can select preamble groups 2 if the desired quality requirement satisfies the quality requirement criteria of quality requirement level 2. Next, the terminals can randomly select preambles from the selected preamble groups (S443).

Again, referring to FIG. 4, the terminals can transmit the selected preambles to the base station (S450). At this time, the terminals can apply the first transmission power to preamble group 1 and the second transmission power to preamble group 2 according to the transmission power setting information received from the base station. At this time, terminals may be able to multiplex preambles at certain frequencies and time intervals. If the terminals transmit preambles sufficiently far apart in frequency and time resource space, the base station can distinguish them through filtering. The 3GPP NR standard can express the divided resource space area as a RACH (random access channel) occurrence, and set the arrangement for it. The base station may transmit arrangement information of RACH events set through system information and/or RRC messages to the terminals. Then, the terminals can receive placement information of RACH events through system information and/or RRC messages from the base station. Terminals can configure a RACH occasion bundle by combining a plurality of adjacent RACH occasions in the resource space, and add the number of occasions included in the RACH occasion bundle to the configuration information, thereby creating a coded random access (coded random access) random access) technology can be used. RACH application bundles can span frequency and time axes, for example, can be set to 4FDM (frequency division multiplexing), 2TDM (time division multiplexing), and repeat the same preamble to all 8 adjacent RACH applications. At this time, the terminals can facilitate reception by the base station by arbitrarily muting the four RACH applications. Here, the terminals can configure a RACH application bundle, and in the RACH application bundle The number of included RACH events can be set, but unlike this, the base station can configure a RACH event bundle by combining multiple adjacent RACH events in the resource space, and the number of RACH events included in the RACH event bundle can be set. The base station can transmit RACH application bundle configuration information and configuration information of the number of RACH applications included in the RACH application bundle to the terminals. The terminals can receive RACH application bundle configuration information and RACH error information from the base station. Setting information on the number of RACH applications included in the application bundle may be received, and the terminals may receive configuration information on the number of RACH applications included in the RACH application bundle and the RACH application bundle configuration information received from the base station. Accordingly, a RACH application bundle can be configured, and code random access technology can be utilized by setting the number of RACH applications included in the RACH application bundle.

Meanwhile, terminals can use the discrete Fourier transform spread orthogonal frequency division multiplexing (DFT-S-OFDM) modulation method to respond to multi-path fading channels. However, to facilitate analysis, it can be assumed that the terminals use a single-path fading channel, and the synchronization error of each terminal may not be considered. Meanwhile, the base station can receive preambles transmitted from terminals. At this time, if the preamble signals received by the base station are expressed as a matrix, Received signal matrix, which is a matrix It can be expressed as Equation 6 below:

here, may be the number of receiving antennas of the base station, may be the length of the preamble. also, is the preamble index in preamble group 1. It can represent the sum of wireless channels from the selected terminals to the base station. and, is the preamble index in preamble group 2. It can represent the sum of wireless channels from the selected terminals to the base station. also, May represent the average received power of a signal transmitting the preamble selected in preamble group 1. and, May represent the average received power of a signal transmitting the preamble selected in preamble group 2. class Is It can be assumed that also, may be a preamble included in preamble group 1. and, may be a preamble included in preamble group 2. Meanwhile, may mean a thermal noise matrix.

Figure 7 is a conceptual diagram showing a first embodiment of preamble indexes for each preamble group.

Referring to FIG. 7, preamble indexes 1 to 1 in the preamble indexes for each preamble group. may indicate the index of preambles belonging to preamble group 1 and may be used for the first type terminal. here, silver It can be. and, inside may indicate the index of preambles belonging to preamble group 2, and may be used for a second type terminal. Preambles belonging to preamble group 1 may be orthogonal. In contrast, preamps belonging to preamble group 2 may be non-orthogonal. Additionally, preambles belonging to preamble group 1 may be transmitted with high transmission power, and preambles belonging to preamble group 2 may be transmitted with lower transmission power than preambles belonging to preamble group 1.

Meanwhile, the base station receives the received signal matrix Preambles transmitted by terminals can be extracted from Two hypotheses can be tested. As a result, it may be difficult for the base station to handle the computational complexity when the number of preambles increases exponentially. Accordingly, the base station can detect the preamble in two stages (S460).

FIG. 8 is a flowchart showing a first embodiment of the preamble detection process of FIG. 4.

Referring to Figure 8, during the preamble detection process, the base station receives the signal matrix Preamble matrix of preamble group 1 Multiply as shown in Equation 7 to obtain the correlation can be calculated (S461).

Afterwards, the base station can detect preambles included in preamble group 1 transmitted from terminals using the calculated correlation (S462). At this time, since orthogonality exists between preambles included in preamble group 1, interference may not exist. In contrast, there may be interference from the preamble belonging to preamble group 2, but since the reception power can be assumed to be small, the reception performance degradation due to this can be considered small.

Next, the base station receives the signal matrix A successive interference cancellation (SIC) process can be performed to remove detected preambles belonging to preamble group 1 as shown in Equation 8 below (S463).

here, may refer to a set of preamble indices detected in preamble group 1. And, in Equation 8 is the unit matrix It can be defined as in Equation 9 below.

may mean an orthogonal projection matrix. Equation 8 is an orthogonal matrix and orthogonal matrices A matrix consisting only of column vectors not detected in If rewritten using , it can be as shown in Equation 10 below.

Next, the base station can detect preambles belonging to preamble group 2 in the received signal matrix from which the detected preambles have been removed (S464). At this time, if the number of terminals that selected and transmitted preambles belonging to preamble group 2 is small, Most of them may be 0, and most of them may be 0. index of It is possible to detect preambles belonging to preamble group 2 by obtaining a set of . Thermal noise N as well as wireless channel status Since it is also a random variable, variational inference is required for the transmitted preamble set, and various algorithms are known to perform this. In particular, by applying the coordinated ascent variational inference (CAVI) algorithm, preambles belonging to preamble group 2 can be detected from the received signal matrix with relatively low complexity by individually updating the activation probability for each preamble.

Again, referring to FIG. 4, the base station may transmit preamble response signals according to the detected preambles to the terminals (S470).

Methods according to the present invention may be implemented in the form of program instructions that can be executed through various computer means and recorded on a computer-readable medium. Computer-readable media may include program instructions, data files, data structures, etc., singly or in combination. Program instructions recorded on a computer-readable medium may be specially designed and constructed for the present invention or may be known and usable by those skilled in the computer software art. Examples of computer-readable media may include hardware devices specifically configured to store and execute program instructions, such as ROM, RAM, flash memory, etc. Examples of program instructions may include machine language code such as that created by a compiler, as well as high-level language code that can be executed by a computer using an interpreter, etc. The above-described hardware device may be configured to operate with at least one software module to perform the operations of the present invention, and vice versa.

Additionally, the above-described method or device may be implemented by combining all or part of its components or functions, or may be implemented separately.

Although the present invention has been described above with reference to preferred embodiments, those skilled in the art may make various modifications and changes to the present invention without departing from the spirit and scope of the present invention as set forth in the claims below. You will understand that you can do it.

Claims (17)

As a method of operating a terminal of a communication system,
Receiving quality requirement information for preamble groups and belonging preamble information for each of the preamble groups from a base station;
selecting one preamble group from among the preamble groups based on the quality requirement information based on a terminal quality request;
selecting a preamble within the one preamble group based on the belonging preamble information;
transmitting a first message including the selected preamble to the base station; and
Receiving a second message, which is a response signal to the first message, from the base station,
The preamble groups have a cross-correlation of the remaining CAZAC sequences after removing CAZAC sequences whose cross-correlation is greater than the first threshold from the raw preamble group consisting of CAZAC (constant amplitude zero autocorrelation) sequences with a prime sequence length. It consists of a first preamble group made up of CAZAC sequences less than or equal to a threshold and a second preamble group made up of the remaining CAZAC sequences excluding the first preamble group, wherein the first threshold is greater than the second threshold. , How the terminal operates. delete In claim 1,
The CAZAC sequence is a Zadoff-Chu sequence, and the prime number is one of 839 and 139. In claim 1,
Further comprising receiving transmission power information for the preamble groups from the base station,
A method of operating a terminal, characterized in that the selected preamble is transmitted using transmission power according to the transmission power information. In claim 1,
The preamble groups include the first preamble group for a first type of terminal whose quality request delay time is less than a threshold and the second preamble group for a second type of terminal whose quality request delay time is greater than or equal to a threshold, A method of operating a terminal, characterized in that the transmission power for the first preamble group is greater than the transmission power for the second preamble group. In claim 1,
Further comprising receiving, from the base station, a random access channel (RACH) occasion bundle and setting information on the number of RACH occasions included in the RACH occasion bundle,
The selected preamble is transmitted in the RACH organization indicated by the configuration information. In claim 1,
The first message is MsgA, and the second message is MsgB. A method of operating a base station of a communication system, comprising:
Setting preamble groups, preambles belonging to the preamble groups, and quality requirements of the preamble groups;
Transmitting preamble group setting information including information about the preamble groups, information about the belonging preambles, and information about the quality requirements to a terminal;
Receiving a first message including a preamble selected based on the preamble group setting information according to a quality requirement from the terminal;
detecting the preamble in the first message; and
It includes transmitting a second message that is a response signal to the first message to the terminal,
The preamble groups consist of a first preamble group and a second preamble group formed by dividing a raw preamble group composed of CAZAC (constant amplitude zero autocorrelation) sequences with a prime sequence length based on mutual correlation,
The step of setting the preamble groups, preambles belonging to the preamble groups, and quality requirements of the preamble groups,
forming the original preamble group with the CAZAC sequences having a prime sequence length as preambles;
Excluding preambles having a cross-correlation value greater than or equal to a first threshold from the preambles in the original preamble group;
Generating the first preamble group with preambles having a cross-correlation of less than or equal to a second threshold in the raw preamble group consisting of preambles excluding preambles having a cross-correlation of more than the first threshold. step; and
Generating the first preamble group from the original preamble group consisting of the remaining preambles and generating the second preamble group from the remaining preambles. In claim 8,
The step of setting the preamble groups, preambles belonging to the preamble groups, and quality requirements of the preamble groups,
allocating the preambles in the original preamble group to the belonging preambles of the preamble groups; and
A method of operating a base station, comprising setting the quality requirements for the preamble groups. delete In claim 9,
The step of setting the quality requirements for the preamble groups includes:
Setting quality requirement stages by classifying quality requirement criteria; and
A method of operating a base station, comprising mapping the quality requirement steps to the preamble groups. In claim 9,
The step of setting the quality requirements for the preamble groups is characterized by setting the quality requirements for the preamble groups using quality request specifiers that indicate a preamble group that the base station can select. How a base station operates. In claim 8,
Detecting the preambles in the first message includes:
calculating a correlation by applying the preamble matrix of one preamble group to the received signal matrix of first messages received from a plurality of terminals including the terminal;
detecting preambles belonging to one preamble group using the calculated correlation;
removing received signals corresponding to the detected preambles from the received signal matrix; and
A method of operating a base station comprising detecting preambles belonging to remaining preamble groups in the received signal matrix from which the received signal has been removed and detecting the preamble in the first message. As a terminal,
processor;
a memory that communicates electronically with the processor; and
Contains instructions stored in the memory,
When the instructions are executed by the processor, the instructions cause the terminal to receive quality requirement information for preamble groups and membership preamble information for each of the preamble groups from a base station;
selecting one preamble group from among the preamble groups based on the quality requirement information based on a terminal quality request;
select a preamble within the one preamble group based on the belonging preamble information;
transmitting a first message including the selected preamble to the base station; and
Operate to cause the base station to receive a second message that is a response signal to the first message,
The preamble groups have a cross-correlation of the remaining CAZAC sequences after removing CAZAC sequences whose cross-correlation is greater than the first threshold from the raw preamble group consisting of CAZAC (constant amplitude zero autocorrelation) sequences with a prime sequence length. It consists of a first preamble group made up of CAZAC sequences less than or equal to a threshold and a second preamble group made up of the remaining CAZAC sequences excluding the first preamble group, wherein the first threshold is greater than the second threshold. , terminal. delete In claim 14,
The commands allow the terminal to
Operate to further cause receiving transmission power information for the preamble groups from the base station,
The terminal operates to cause the selected preamble to be transmitted using transmission power according to the transmission power information. In claim 14,
The commands allow the terminal to
Operates to further cause receiving a RACH application bundle and configuration information of the number of RACH applications included in the RACH application bundle from the base station, and the selected preamble is transmitted in the RACH organization indicated by the configuration information. A terminal that operates to cause something.

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