WO2023071055A1 - 多天线mimo场景下随机接入资源的配置与更新方法 - Google Patents

多天线mimo场景下随机接入资源的配置与更新方法 Download PDF

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WO2023071055A1
WO2023071055A1 PCT/CN2022/084960 CN2022084960W WO2023071055A1 WO 2023071055 A1 WO2023071055 A1 WO 2023071055A1 CN 2022084960 W CN2022084960 W CN 2022084960W WO 2023071055 A1 WO2023071055 A1 WO 2023071055A1
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random access
base station
rach
rach resource
resources
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PCT/CN2022/084960
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English (en)
French (fr)
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袁建涛
殷锐
万安平
房涛
王景霖
单添敏
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浙大城市学院
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Priority to US17/795,644 priority Critical patent/US11979205B1/en
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W72/00—Local resource management
    • H04W72/50—Allocation or scheduling criteria for wireless resources
    • H04W72/53—Allocation or scheduling criteria for wireless resources based on regulatory allocation policies
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06N—COMPUTING ARRANGEMENTS BASED ON SPECIFIC COMPUTATIONAL MODELS
    • G06N3/00—Computing arrangements based on biological models
    • G06N3/02—Neural networks
    • G06N3/04—Architecture, e.g. interconnection topology
    • G06N3/044—Recurrent networks, e.g. Hopfield networks
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06N—COMPUTING ARRANGEMENTS BASED ON SPECIFIC COMPUTATIONAL MODELS
    • G06N3/00—Computing arrangements based on biological models
    • G06N3/02—Neural networks
    • G06N3/04—Architecture, e.g. interconnection topology
    • G06N3/045—Combinations of networks
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
    • H04B7/0413—MIMO systems
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W74/00—Wireless channel access
    • H04W74/002—Transmission of channel access control information
    • H04W74/006—Transmission of channel access control information in the downlink, i.e. towards the terminal
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W74/00—Wireless channel access
    • H04W74/08—Non-scheduled access, e.g. ALOHA
    • H04W74/0833—Random access procedures, e.g. with 4-step access

Definitions

  • the invention belongs to the field of wireless communication, and in particular relates to a method for configuring and updating random access resources at a base station side in a multiple-input multiple-output (MIMO) system.
  • MIMO multiple-input multiple-output
  • the International Telecommunication Union clarified the three main application scenarios of 5G according to the requirements of data transmission rate, delay, number of connections and reliability of terminal services, namely: enhanced mobile broadband (enhanced mobile broadband, eMBB), massive Machine Type Communications (mMTC) and Ultra-Reliable and Low Latency Communications (URLLC).
  • enhanced mobile broadband enhanced mobile broadband
  • mMTC massive Machine Type Communications
  • URLLC Ultra-Reliable and Low Latency Communications
  • the above three application scenarios have different requirements on indicators such as speed, reliability, and delay.
  • eMBB is mainly oriented to human-centered wide-area continuous coverage and local hotspot coverage communication, which is used to meet the data transmission of large-traffic services and bring users a faster and more extreme experience
  • mMTC is mainly oriented to the Internet of Things involving a large number of nodes.
  • RACH uplink random access channel
  • 4G, 5G the configuration of uplink random access channel (Random Access CHannel, RACH) resources in cellular wireless communication (such as 4G, 5G) uses several fixed configurations.
  • RACH resources when the number of uplink random access users in the system When the number of RACH resources is small, the RACH resources are not fully utilized, resulting in idle waste of RACH resources; on the contrary, when the number of uplink random access users in the system is large and the RACH resources are insufficient, multiple uplink users will initiate on the limited RACH resources.
  • random access serious access conflicts are caused, and users cannot access the wireless communication system to receive services within a short period of time.
  • the RACH resources are fixedly configured. Under the fixed RACH resource configuration, when the number of uplink random access users in the system is small, the RACH resources cannot be fully utilized, resulting in waste of RACH resource restrictions; Conversely, when the number of uplink random access users in the system is large, insufficient RACH resources cause multiple uplink users to initiate random access on limited RACH resources, resulting in serious conflicts, and users cannot access the wireless system to receive services in a short time. In addition, when a user initiates a random access request in an existing communication system, it is considered a conflict if more than one user uses the same RACH resource.
  • the purpose of the present invention is to overcome the deficiencies in the prior art and provide a method for configuring and updating random access resources in a MIMO system.
  • This method for configuring and updating random access resources in a MIMO system includes the following steps:
  • Step 2 the base station broadcasts the available RACH resource R2 through the system information block SIB2; in the 5G NR system, due to the use of multi-antenna MIMO technology, when the base station is configured with K receiving antennas, the maximum spatial degree of freedom is K, and each base station Sequences or signals that can distinguish up to K users at a time;
  • Step 3 the user who has uplink data to be sent initiates a random access process on the RACH resource configured by the base station;
  • Step 4 In the multiple-input multiple-output MIMO system, the spatial degree of freedom formed by multiple antennas of the base station is represented by K, the number of users who initiate random access on a certain RACH resource is represented by N, and the result on this RACH resource is represented by F To represent, redefine the S state, I state, and C state; the initial value of N is 0.
  • the base station predicts and estimates the value of N, it is obtained from the paging configuration of the base station in the non-contention-based random access method, and is obtained by the long-short-term memory network (LSTM, Long Short-Term Memory network) in the contention-based random access method ) is estimated.
  • LSTM Long Short-Term Memory network
  • Step 5 the base station compares the RACH resource utilization rate ⁇ that is counted with the preset RACH resource utilization rate threshold value ⁇ Threshold , and determines whether ⁇ exceeds the preset threshold value ⁇ Threshold ; if satisfying ⁇ Threshold , execute step 6 to step 7; otherwise, execute step 8;
  • Step 7 the base station obtains the updated number of RACH resources according to the RACH resource update function
  • the update function is as follows:
  • the non-negative number ⁇ M is the weight value when the base station updates the RACH resource for the Mth time, and is used to control the update amount of the RACH resource; Represents an upward rounding operation, which is used to ensure that the number of RACH resources after each update is an integer multiple of the minimum number of resource blocks in the cellular communication system; The number of newly added RACH resources to make the configured RACH resource utilization not lower than the set threshold; by adjusting the non-negative number ⁇ M to ensure that the number of each increase is close to the optimal configuration, and return to step 3 to step 5, Until ⁇ Threshold ;
  • the base station in step 1 includes: a processor and a transceiver, the processor and the transceiver are connected; the processor is used for updating parameter values during the RACH process, and the transceiver is used for broadcasting RACH configuration and parsing the received Preamble code.
  • the base station further includes a memory for storing RACH updated configuration information and intermediate quantities in the RACH process, such as statistics of S/I/C status.
  • the transceiver is specifically a receiver and a transmitter;
  • the processor is a central processing unit (Central Processing Unit, CPU), a general purpose processor, a digital signal processing (Digital Signal Processing, DSP), an integrated circuit (Application Specific Integrated Circuit, ASIC), Field-Programmable Gate Array (Field-Programmable Gate Array, FPGA), other programmable logic devices, transistor logic devices, hardware components;
  • the processor and the transceiver are connected through a bus.
  • the memory is read-only memory (read-only memory, ROM), other types of static storage devices that can store static information and instructions, random access memory (random access memory, RAM), and other types that can store information and instructions.
  • ROM read-only memory
  • RAM random access memory
  • dynamic storage devices Electrically Erasable Programmable Read-Only Memory (EEPROM), Compact Disc Read-Only Memory (CD-ROM) or other optical disc storage, optical disc storage (including Compact Disc, LaserDisc, Compact Disc, Digital Versatile Disc, Blu-ray Disc, etc.) or magnetic disk storage media.
  • step 2 when the base station is configured with K receiving antennas, the spatial degree of freedom is K at most, and idle (Idle, referred to as I), success (Success, referred to as S), and collision (Collision, referred to as C) on each RACH resource )
  • I idle
  • S success
  • C collision
  • the RACH resource feedback result is the I state, it means that the Preamble sequence sent by the user is not detected on the RACH resource, and the RACH is idle;
  • the RACH resource feedback result is S state, it means that at least one but no more than K preamble sequences sent by users are detected, and the preamble sequences sent by users on this RACH are successful;
  • the RACH resource feedback result is C state, it means that more than K users are detected to send Preamble sequences, and a collision occurs on the RACH.
  • S state As a preference, the S state, I state, and C state are defined as follows:
  • the I state indicates that the RACH resource feedback result is an idle state
  • the S state indicates that the user on the RACH successfully sends the Preamble sequence
  • the C state indicates that a conflict has occurred on the RACH
  • the base station counts the utilization rate ⁇ of RACH resources according to the total number of S states, the total number of I states and the total number of C states on all RACH resources detected:
  • N S is the total number of S states on all RACH resources
  • N I is the total number of I states on all RACH resources
  • N C is the total number of C states on all RACH resources
  • R 1 is the random access preamble set The number of Preamble codes
  • R 2 is the number of available RACH resources
  • n is the utilization rate of all RACH resources.
  • the relevant standard table in step 8 is Table 5.7.1-2 in 3GPP specification TS38.211.
  • the present invention proposes a configuration and update method for uplink random access RACH resources on the base station side in a MIMO system; the present invention can gradually and dynamically optimize the configuration of RACH resources according to the number of base station antennas and the utilization threshold of RACH resources, so that the MIMO system can On the premise of satisfying the user/service access success probability requirements, the waste of random access RACH resources in the system is reduced.
  • the designed uplink random access resource configuration is related to the antenna configuration on the base station side, which can make full use of the space diversity characteristics of MIMO to improve resource utilization; and the configuration update method is executed on the base station side, only needing to change the random access resources on the base station side configuration information, no hardware changes are required.
  • the user terminal can be compatible with the random access protocol procedure in the traditional cellular wireless communication system without any modification.
  • FIG. 1 is a network architecture diagram applicable to an embodiment of the present invention
  • FIG. 2 is a flowchart of an implementation manner of random access in an existing cellular wireless communication system
  • FIG. 3 is a flowchart of a method for configuring and updating uplink random access resources according to the present invention
  • Fig. 4 is a flow chart of the base station in the MIMO system using the LSTM network to estimate the number of users;
  • FIG. 5 is a schematic structural diagram of a base station provided by an embodiment of the present invention.
  • base station 500 base station 500, processor 501, transceiver 502, memory 503, LSTM network 600, fully connected network A700, fully connected network B800.
  • the random access process is initiated by the user on the fixed random access resource configured by the base station; the random access in the existing cellular communication system
  • the basic process of the protocol needs to complete two handshake processes, which are divided into four steps:
  • the base station sets random access-related configuration messages through the broadcasted System Information Block 2 (SIB2), such as the time-frequency domain location information of PRACH, the number of configured RACH channels, etc.
  • SIB2 System Information Block 2
  • the first handshake process consists of the first step and the second step.
  • the user sends Msg1 (random access preamble, that is, Preamble code), and the base station receives Msg1.
  • the user obtains random access related configuration information from the system information block 2 (System Information Block 2, SIB2) broadcast by the base station, and then from the random access preamble (Preamble code) set (the Preamble code in the random access preamble set
  • R 1 the number of codes
  • R 1 the number of codes
  • PRACH Physical Random Access CHannel
  • the base station detects and decodes Msg1 in the subframe configured with PRACH resources, and obtains the Preamble code identifier.
  • the base station feeds back Msg2 (random access response), and the user receives Msg2.
  • the base station sends Msg2 to the user on the Physical Downlink Share Channel (PDSCH), and sends a DCI indicating the position of Msg2 on the Physical Downlink Control Channel (PDCCH) .
  • Msg2 contains the Preamble code identifier decoded in the first step, the user identifier (user identification code), the uplink scheduling grant (Uplink Grant, UL Grant) indicating the time-frequency domain position of Msg3 and the retransmission information (backoff parameter) wait.
  • the user listens to the PDCCH channel in the random access response (Random Access Response, RAR) window in order to obtain the downlink control message indicating the position of Msg2 on the PDSCH, and receives and decodes Msg2 on the PDSCH at the corresponding position. If the preamble code identifier obtained by the user's decoding is consistent with its own preamble code identifier, it will enter the contention resolution process, that is, the third step; otherwise, the user will randomly select a value between 0 and the backoff parameter as the backoff value. On the first PRACH resource after 0, execute the first step.
  • RAR Random Access Response
  • the result of the Preamble code detected by the base station on the RACH resource may appear in three situations: success (Success, abbreviated as S), conflict (Collision, abbreviated as C), idle (Idle, abbreviated as I).
  • success Success, abbreviated as S
  • conflict Collision, abbreviated as C
  • idle Idle, abbreviated as I.
  • the base station feeds back the results of random access user states according to the initially configured random access channel resources.
  • LSTM Long Short- Term Memory
  • the base station estimates the number of active users N i from the observed state of the random variable T i ,
  • BW is the number of time slots contained in the backoff window length (BackoffWindow, BW) of random access
  • N i A is the newly activated user who has new data arriving in the ith random access time slot and is waiting to initiate random access
  • N ik,F (k) is the number of users who re-initiate random access on the i-th random access slot after the preamble collision on the ik-th random access slot leads to random access failure. Therefore, the random access detection result P(N i ) (that is, the probability distribution function of the number of active users N i ) is modeled as follows:
  • the memory window length L of the LSTM network should be set to a larger value, such as several times the length of the BW . This is because the user who has a random access conflict needs to randomly select a backoff value between 0 and BW when reinitiating random access.
  • L is set too small, the LSTM network will not be able to remember all retransmitted users; correspondingly, if L is set too large, the memory resources of the computer will be wasted. By setting a reasonable L, redundant information can be discarded, and the training of the neural network model can be accelerated.
  • the utilization rate ⁇ of RACH resources is defined as The ratio of the total number of S states (N S ) to the sum of the total number of I states (N I ) and the total number of C states N C on all RACH resources, ⁇ can be expressed as
  • the second handshake process that is, the contention resolution process, includes the third and fourth steps.
  • the user sends Msg3 (scheduled transmission), and the base station receives Msg3.
  • the user parses Msg2 to obtain the UL Grant and the user identification code, and sends Msg3 carrying the user code identifier to the base station at the time-frequency domain position of the Uplink Shared Channel (UL-SCH) indicated by the UL Grant.
  • the base station listens to the Msg3 message on the UL-SCH.
  • the base station feeds back Msg4 (conflict resolution), and the user receives Msg4.
  • the base station receives and decodes Msg3, and if it can decode correctly to obtain the user identification code, it sends Msg4 to the user on the PDSCH within the duration of the contention resolution timer, and at the same time sends a downlink control message carrying the location of Msg4 on the PDCCH.
  • the user listens to the PDCCH channel within the duration of the contention resolution timer in order to receive the downlink control message, and receives Msg4 at the corresponding position of the PDSCH, indicating that the user successfully completes the random access.
  • the number of Msg3 transmissions is increased by 1, and it is judged whether the maximum number of Msg3 transmissions is exceeded. If it is not exceeded, execute the third step; if it exceeds, add 1 to the number of Msg1 transmissions to determine whether the maximum number of Msg1 transmissions is exceeded. If not, execute the first step after performing backoff according to the retransmission parameters; If it exceeds, it is considered that the random access of the user has failed.
  • ⁇ is a function of R 1 , R 2 and N.
  • the base station can reasonably configure the total number of Preamble codes R 1 in the random access preamble set and the number of RACH resources R 2 configured by the base station according to the required RACH resource utilization rate ⁇ .
  • R 1 is generally fixed, when the number of uplink random access users N is given, the minimum number of RACH resource configurations R 2 that satisfies the RACH resource utilization threshold ⁇ Threshold can be easily derived from the following optimization problem.
  • the result of the Preamble code detected by the base station on the RACH resource has nothing to do with the number of antennas of the base station.
  • the spatial degrees of freedom formed by multiple antennas can simultaneously distinguish the data of K users on the base station side. That is, when a user initiates random access, it can be considered as a conflict if more than K users use the same RACH resource. Therefore, the existing random access protocols do not make good use of the space advantage of MIMO in the new generation cellular system.
  • Embodiment 1 of the present application provides a network architecture diagram to which the method for updating random access resource configuration shown in FIG. 1 is applicable; including a base station and user equipment.
  • the random access process is triggered by a user or a base station.
  • the trigger conditions include the user's initial access, such as the UE changing from the RRC_IDLE state to the RRC_CONNETTED state; wireless link re-establishment, ensuring that the UE re-establishes wireless connection and handover after the wireless link fails.
  • the user initiates the random access process on the random access resource RACH configured by the base station; in the random access process triggered by the base station, the base station first notifies the user through broadcast or paging signaling, and then the user A random access procedure is initiated on the random access resource RACH configured by the base station.
  • the result on the RACH resource may appear in three situations: success (Success, abbreviated as S), collision (Collision, abbreviated as C), idle (Idle, abbreviated as I) .
  • success S
  • collision collision
  • Idle idle
  • I idle
  • S success
  • S collision
  • Idle idle
  • S/I/C state the definition of the S/I/C state in the MIMO system is different from the definition of the S/I/C state in the traditional cellular communication system.
  • N represents the number of users who initiate random access on a certain RACH resource
  • F represents the result on this RACH resource.
  • the S/I/C state is defined as follows
  • the rate ⁇ is defined as the ratio of the total number of S states ( NS ) to the sum of the total number of I states (N I ) and the total number of C states N C on all RACH resources detected by the base station, and ⁇ can be expressed as
  • N S is a function of the number of users N, the number of base station antennas K, the total number of preamble codes R 1 in the random access preamble set, and the number of RACH resources R 2 configured by the base station.
  • N S It is no longer possible to write out its expression intuitively like NS in traditional cellular networks. Therefore, the base station can no longer assist the base station to intuitively configure the number of RACH resources R 2 simply according to the required RACH resource utilization rate ⁇ .
  • Embodiment 2 of the present application provides a method for updating random access resource configuration applicable to a network architecture of Embodiment 1 as shown in FIG. 3 :
  • Step 2 The base station broadcasts the available random access RACH resource configuration R 2 through a system information block (SIB2).
  • SIB2 system information block
  • Step 3 The user who has uplink data to send initiates a random access process on the RACH resource configured by the base station.
  • the fourth step the base station counts the utilization rate ⁇ of random access RACH resources according to the total number of S states ( NS ) and the total number of I states (N I ) and the total number of C states N C on all RACH resources detected
  • N the number of users who initiate random access on a certain RACH resource
  • F the result on this RACH resource.
  • Step 5 the base station compares the statistical random access RACH resource utilization ratio ⁇ with the preset random access RACH resource utilization threshold value ⁇ Threshold , and determines whether ⁇ exceeds the preset threshold value ⁇ Threshold ( ⁇ Threshold ). If satisfied, go to step six; otherwise, go to step eight.
  • Step 6 The base station increases the value of the RACH resource update times M by 1.
  • Step 7 The base station obtains the updated number of RACH resources according to the RACH resource update function
  • the update function is as follows:
  • the non-negative number ⁇ M is the weight value when the base station updates the RACH resource for the Mth time, and is used to control the update amount of the resource; Represents an upward rounding operation to ensure that the number of RACH resources after each update is an integer multiple of the minimum number of resource blocks in the cellular communication system; It is the number of newly added RACH resources to make the configured RACH resource utilization not lower than the set threshold.
  • the non-negative number ⁇ M can be adjusted to ensure that the number of each increase is getting closer to the optimal configuration, and return to the third step.
  • Step 8 The base station searches for the configuration closest to the value of R 2 in Table 5.7.1-2 in the 3GPP specification TS38.211 for configuration, and the base station resets the utilization rate ⁇ of the RACH resource to an initial value of 0.
  • the update times of RACH resources M 1, and the update process of RACH resources ends.
  • the feedback result is I, which means that no user is detected to send a Preamble sequence on the RACH resource;
  • the feedback result is S, which means that a user is detected to send a Preamble sequence, so the transmission is successful ;
  • C indicates that multiple users have been detected to send their Preamble sequences, and a conflict has occurred.
  • the base station when the base station is equipped with K receiving antennas, the base station can distinguish the sequences/signals of up to K users each time. Therefore, at this moment, idle/success/collision (Idle/Success/Collision, I/S/C) on each RACH resource is explained as follows: the feedback result is that I represents that the user does not detect that the user sends a Preamble sequence on this RACH resource; It means that K users are detected to send Preamble sequences, so the transmission is successful; C means that more than K users are detected to send their Preamble sequences, and a collision occurs.
  • I idle/success/collision
  • FIG. 4 is a flow chart of estimating the number of users by the base station of the MIMO system using the LSTM network in this embodiment.
  • the initial value of N is 0 because the number of random access users cannot be accurately obtained. Every time when the RACH resource configuration is updated, the base station re-predicts and estimates the value of N.
  • the non-contention-based random access method it is obtained by the paging configuration of the base station; in the contention-based random access method, the base station uses the long-short-term memory network as shown in Figure 4 according to the detection result of the last random access Preamble code ( LSTM, Long Short-Term Memory) estimated.
  • LSTM Long Short-Term Memory
  • the base station can obtain the state of the Preamble. That is, the S/I/C state of each Preamble code sent by the base station in the MIMO system.
  • the triplet T i ⁇ I i , S i , C i ⁇ is used to represent the state set of the Preamble code on the ith random access slot in the MIMO system.
  • T i ⁇ I i ,S i ,C i ⁇
  • the base station estimates the number of active users N i from the observed state of the random variable T i ,
  • BW is the number of time slots contained in the backoff window length (Backoff Window, BW) of random access
  • N i, A is the new activation of new data arriving in the ith random access time slot waiting to initiate random access
  • Ni ik,F (k) is the number of users who re-initiate random access on the i-th random access slot after the preamble collision on the ik-th random access slot causes the random access to fail. Therefore, the random access detection result P(N i ) (that is, the probability distribution function of the number of active users N i ) is modeled as follows:
  • the base station of the MIMO system predicts and estimates the number of random access users based on the LSTM network
  • the network includes an LSTM unit and two fully connected (Fully Connected, FC) networks.
  • the number of hidden layer nodes is set to be the same as the backoff window length BW.
  • the input of the fully connected network A700 is BW dimension, and the output is BW/2 dimension;
  • the input of the fully connected network B800 is BW/2 dimension, and the output is 1 dimension;
  • the output dimension is reduced from the BW dimension to 1 dimension, and the probability distribution function P(N i ) for estimating and predicting the number N i of active users who initiate and wait to initiate random access in the MIMO system is output.
  • the memory window length L of the LSTM network should be set to a larger value, because random When re-initiating random access, users with access conflicts should randomly select a backoff value between 0 and BW to re-initiate random access. If L is set too small, the LSTM network will not be able to remember all retransmitted users; correspondingly, if L is set too large, the memory resources of the computer will be wasted. By setting a reasonable L, redundant information can be discarded, and the training of the neural network model can be accelerated. During training, set the memory window length of the LSTM network to the maximum BW length.
  • FIG. 5 provides a schematic structural diagram of a base station in this embodiment.
  • the base station in this embodiment of the present invention may be the base station provided in any of the embodiments shown in FIG. 2 to FIG. 4 .
  • the base station 500 shown in FIG. 5 includes: a processor 501 and a transceiver 502 .
  • the processor 501 is used to update parameter values during the RACH process
  • the transceiver 502 is used to implement functions such as broadcasting of RACH configuration and parsing received Preamble codes.
  • the processor 501 is connected to the transceiver 502, for example, through a bus.
  • the base station 500 may also include a memory 503 for storing configuration information of RACH updates and intermediate quantities in the RACH process, such as statistics of S/I/C status. It should be noted that this embodiment does not limit the number of processors 501 and transceivers 502, and the structure of the base station 500 does not limit this embodiment.
  • Transceiver 502 may be implemented by a receiver and a
  • the processor 501 may be a central processing unit (Central Processing Unit, CPU), a general purpose processor, a digital signal processing (Digital Signal Processing, DSP), an integrated circuit (Application Specific Integrated Circuit, ASIC), field programmable Logic gate array (Field-Programmable Gate Array, FPGA) or other programmable logic devices, transistor logic devices, hardware components or any combination thereof. It may implement or execute the logical blocks, modules and circuits in conjunction with the invention.
  • the processor 501 may also be a combination that implements computing functions, for example, a combination of one or more microprocessors, a combination of a DSP and a microprocessor, and the like.
  • the memory 503 may be a read-only memory (read-only memory, ROM) or other types of static storage devices that can store static information and instructions, a random access memory (random access memory, RAM) or other types that can store information and instructions It can also be an electrically erasable programmable read-only memory (Electrically Erasable Programmable Read-Only Memory, EEPROM), a read-only disc (Compact Disc Read-Only Memory, CD-ROM) or other optical disc storage, optical disc storage (including compact discs, laser discs, optical discs, digital versatile discs, Blu-ray discs, etc.), magnetic disk storage media or other magnetic storage devices, or can be used to carry or store desired program code in the form of instructions or data structures and can be programmed by a computer Any other medium accessed, but not limited to.
  • ROM read-only memory
  • RAM random access memory
  • EEPROM Electrically erasable programmable Read-only memory
  • CD-ROM Compact Disc Read-Only Memory
  • CD-ROM
  • the processor 501 and the transceiver 502 described in the embodiment of the present invention can execute the random access process in the existing cellular wireless communication system shown in FIG. The executed random access method will not be repeated here.
  • the computer-readable storage medium may be an internal storage unit of any base station, such as a hard disk or memory of the base station.
  • the computer-readable storage medium can also be an external storage device of the base station, such as a plug-in hard disk equipped on the base station, a smart memory card (Smart Media Card, SMC), a secure digital (Secure Digital, SD) card, a flash memory card (Flash Card) )wait.
  • the computer-readable storage medium may also include both an internal storage unit of the base station and an external storage device.
  • the computer readable storage medium is used to store computer programs and other programs and data required by the base station.
  • the computer-readable storage medium can also be used to temporarily store data that has been output or will be output.

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Abstract

一种多天线MIMO场景下随机接入资源的配置与更新方法，包括步骤：基站初始化；基站通过系统信息块SIB2广播可用的RACH资源；上行有数据待发送的用户在基站配置的RACH资源上发起随机接入过程；对S状态、I状态、C状态进行重新定义；根据基站天线数目、RACH资源的利用率门限值动态优化RACH资源的配置。

Description

多天线MIMO场景下随机接入资源的配置与更新方法
本申请要求于2021年10月25日提交中国专利局、申请号为202111239199.X、发明名称为“多天线MIMO场景下随机接入资源的配置与更新方法”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本发明属于无线通信领域，尤其涉及多输入多输出(MIMO)系统中的一种基站侧随机接入资源的配置与更新方法。
背景技术
2015年9月，国际电信联盟根据终端业务的数据传输速率、时延、连接数和可靠性等方面的要求，明确了5G的三大主要应用场景，分别是：增强移动宽带(enhanced Mobile Broadband，eMBB)、大规模机器通信(massive Machine Type Communications，mMTC)和超高可靠低延时通信(Ultra-Reliable and Low Latency Communications，URLLC)。上述三种应用场景对速率、可靠性和时延等指标的要求各不相同。其中，eMBB主要面向以人为中心的广域连续覆盖和局部热点覆盖通信，用于满足大流量业务的数据传输，为用户带来更高速、更极致的体验；mMTC主要面向涉及海量节点的物联网数据采集与传输等应用，该类场景下业务具有低功耗和海量连接等特点；URLLC主要面向对传输时延和通信可靠性要求极高的特殊行业应用。为了更好地支撑多样化的应用场景，探索无线网络支撑具有苛刻QoS要求的业务的可能性，需要根据无线系统的业务负载(用户数)来配置资源，只有准确的估计出无线网络中的业务负载(用户数)才能更好地利用有线的无线资源。
目前蜂窝无线通信(如4G，5G)中上行随机接入信道(Random Access CHannel，RACH)资源的配置使用几种固定的配置，在固定RACH资源的配置下，当系统中上行随机接入用户数目较少时，RACH资源得不到充分利用，造成RACH资源的闲置浪费；反之，当系统中上行随机接入用户数目较多时，RACH资源不足又会出现多个上行用户在有限的RACH资源上发起随机接入的情况，造成严重的接入冲突，用户无法在短时间内接入无线通信系统中接受服务。
在现有的蜂窝无线通信系统中RACH资源固定配置，在固定RACH资源 的配置下，当系统中上行随机接入用户数目较少时，RACH资源得不到充分利用，造成RACH资源的限制浪费；反之，当系统中上行随机接入用户数目较多时，RACH资源不足使得多个上行用户在有限的RACH资源上发起随机接入，造成冲突严重，用户无法短时间内接入无线系统接收服务。此外，现有通信系统中用户发起随机接入请求时，多于一个用户使用同样的RACH资源即认为是冲突的。而实际上，在MIMO系统中，由于空间自由度的存在，基站侧配置K根接收天线时，最多可以同时区分开K个用户同时发送的数据。也即，当用户发起随机接入时，多于K个用户使用同样的RACH资源才会被认为是冲突的。因此，现有的随机接入协议中RACH资源的配置没有随用户数目动态变化及时进行调整，也未能很好地将新一代蜂窝系统中MIMO技术的空间优势发挥出来。
发明内容
本发明的目的是克服现有技术中的不足，提供一种MIMO系统中随机接入资源的配置与更新方法。
这种MIMO系统中随机接入资源的配置与更新方法，包括以下步骤：
步骤1、基站初始化：配置可用的RACH资源R 2，即在国家标准化组织3GPP规范TS38.211中表5.7.1-2随机/或根据用户数目的统计信息给出一种可选的RACH配置；并将RACH资源利用率η的初始值设置为0，将RACH资源的更新次数M的初始值设置为M＝0；
步骤2、基站通过系统信息块SIB2广播可用的RACH资源R 2；而在5G NR系统中，由于采用了多天线MIMO技术，当基站配置有K根接收天线时空间自由度最大为K，基站每次可以区分出最多K个用户的序列或信号；
步骤3、上行有数据待发送的用户在基站配置的RACH资源上发起随机接入过程；
步骤4、多输入多输出MIMO系统中基站多根天线所构成的空间自由度用K来表示，某个RACH资源上发起随机接入的用户数用N表示，在该RACH资源上的结果用F来表示，对S状态、I状态、C状态进行重新定义；N的初始值为0。基站预测和估计N的取值时，在基于非竞争的随机接入方式中由基站的寻呼配置得到，在基于竞争的随机接入方式中由长短期记忆网络(LSTM， Long Short-Term Memory)估计得到。
步骤5、基站将统计到的RACH资源利用率η与预先设定的RACH资源利用率门限值η Threshold进行比较，并判定η是否超过预设的门限值η Threshold；若满足η<η Threshold，则执行步骤6至步骤7；否则，执行步骤8；
步骤6、基站将RACH资源的更新次数M的数值增加1：M＝M+1；
步骤7、基站按照RACH资源更新函数来得到更新后的RACH资源数
Figure PCTCN2022084960-appb-000001
更新函数如下：
Figure PCTCN2022084960-appb-000002
上式中，非负数α M是基站第M次更新RACH资源时的权重值，用于控制RACH资源的更新量；
Figure PCTCN2022084960-appb-000003
表示向上取整运算，用于保证每次更新后的RACH资源数目为蜂窝通信系统中最小资源块数目的整数倍；
Figure PCTCN2022084960-appb-000004
为使配置的RACH资源利用率不低于设定的阈值而新增加的RACH资源数目；通过调节非负数α M来确保每次增加的数目接近最优配置，并返回执行步骤3至步骤5，直至η≥η Threshold；
步骤8、在3GPP相关标准表中寻找最接近于此时R 2值的RACH资源配置，对基站进行配置；重新将基站内RACH资源的利用率η设置为初始值0，RACH资源的更新次数也设置为M＝0，结束RACH资源的更新过程。
作为优选，步骤1中基站包括：处理器和收发器，处理器和收发器相连；处理器用于RACH过程中更新参数值，收发器用于实现RACH配置的广播与解析接收到的Preamble码。
作为优选，步骤1中基站还包括存储器，存储器用于存储RACH更新的配置信息以及RACH过程中的中间量，如S/I/C状态的统计等。
作为优选，收发器具体为接收器和发射器；处理器为中央处理器(Central Processing Unit，CPU)、通用处理器、数字信号处理(Digital Signal Processing，DSP)、集成电路(Application Specific Integrated Circuit，ASIC)、现场可编程逻辑门阵列(Field-Programmable Gate Array，FPGA)、其他可编程逻辑器件、晶体管逻辑器件、硬件部件中的至少一种；处理器和收发器通过总线相连。
作为优选，存储器为只读存储器(read-only memory，ROM)、可存储静态 信息和指令的其他类型的静态存储设备、随机存取存储器(random access memory，RAM)、可存储信息和指令的其他类型的动态存储设备、电可擦可编程只读存储器(Electrically Erasable Programmable Read-Only Memory，EEPROM)、只读光盘(Compact Disc Read-Only Memory，CD-ROM)或其他光盘存储、光碟存储(包括压缩光碟、激光碟、光碟、数字通用光碟、蓝光光碟等)或磁盘存储介质。
作为优选，步骤2中当基站配置有K根接收天线时空间自由度最大为K，每个RACH资源上的空闲(Idle，简称I)、成功(Success，简称S)、冲突(Collision，简称C)具体为：
当该RACH资源反馈结果为I状态时，表示该RACH资源上没有检测到用户发送的Preamble序列，该RACH空闲；
当该RACH资源反馈结果为S状态时，表示检测到至少一个但不超过K个用户发送的Preamble序列，该RACH上用户发送的Preamble序列成功；
当该RACH资源反馈结果为C状态时，表示检测到多于K个用户发送Preamble序列，该RACH上发生了冲突。
作为优选，S状态、I状态、C状态定义如下：
Figure PCTCN2022084960-appb-000005
上式中，I状态表示RACH资源反馈结果为空闲状态，S状态表示RACH上用户发送Preamble序列成功；C状态表示RACH上发生了冲突；
基站根据检测到的所有RACH资源上S状态总数、I状态总数和C状态总数，统计RACH资源的利用率η：
Figure PCTCN2022084960-appb-000006
上式中，N S为所有RACH资源上S状态的总数；N I为所有RACH资源上I状态的总数；N C为所有RACH资源上C状态总数；R 1为随机接入前导码集合中的Preamble码数目；R 2为可用的RACH资源个数；η为所有RACH资源 的利用率。
作为优选，步骤8中相关标准表为3GPP规范TS38.211中的表5.7.1-2。
本发明的有益效果是：
本发明提出了MIMO系统中基站侧上行随机接入RACH资源的配置与更新方法；本发明可根据基站天线数目、RACH资源的利用率门限值来逐步动态优化RACH资源的配置，使MIMO系统在满足用户/业务接入成功概率需求的前提下，减少系统中随机接入RACH资源的浪费。
同时，设计的上行随机接入资源的配置与基站侧天线配置相关可充分利用MIMO的空间分集特性来提升资源的利用率；且配置更新方法在基站侧执行，只需要基站侧更改随机接入资源的配置信息，不需要进行硬件的更改。同时，用户终端也不需要进行任何更改，即可兼容传统蜂窝无线通信系统中的随机接入协议流程。
说明书附图
为了更清楚地说明本发明实施例或现有技术中的技术方案，下面将对实施例中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图仅仅是本发明的一些实施例，对于本领域普通技术人员来讲，在不付出创造性劳动性的前提下，还可以根据这些附图获得其他的附图。
图1为本发明实施例适用的网络架构图；
图2为现有的蜂窝无线通信系统中的随机接入实施方式流程图；
图3为本发明的上行随机接入资源的配置与更新方法流程图；
图4为MIMO系统中基站使用LSTM网络估计用户数的流程图；
图5为本发明实施例提供的一种基站的结构化示意图。
附图标记说明：基站500、处理器501、收发器502、存储器503、LSTM网络600、全连接网络A700、全连接网络B800。
具体实施方式
下面结合实施例对本发明做进一步描述。下述实施例的说明只是用于帮助理解本发明。应当指出，对于本技术领域的普通人员来说，在不脱离本发明原理的前提下，还可以对本发明进行若干修饰，这些改进和修饰也落入本发明权 利要求的保护范围内。
如图2所示，在现有的蜂窝系统(如5GNR系统)中，随机接入过程是由用户在基站配置的固定的随机接入资源上发起的；现有蜂窝通信系统中的随机接入协议基本流程需要完成2次握手过程，共分4步：
初始化：基站通过广播的系统信息块2(System Information Block 2，SIB2)设置随机接入相关的配置消息，如PRACH的时频域位置信息、RACH信道的配置个数等。
第一次握手过程包含第一步和第二步。
第一步，用户发送Msg1(随机接入前导码，即Preamble码)，基站接收Msg1。用户从基站广播的系统信息块2(System Information Block 2，SIB2)中得到随机接入相关的配置消息，然后从随机接入前导码(Preamble码)集合(将随机接入前导码集合中的Preamble码数目记为R 1)中随机选择一个Preamble码，并在基站指示的R 2个RACH资源，即物理随机接入信道(Physical Random Access CHannel，PRACH)上发送Msg1。相应地，基站在配置了PRACH资源的子帧中检测并解码Msg1，得到Preamble码标识。
第二步，基站反馈Msg2(随机接入响应)，用户接收Msg2。基站根据检测到的Preamble码的结果，在物理下行共享信道(Physical Downlink Share Channel，PDSCH)上发送Msg2给用户，并在物理下行控制信道(Physical Downlink Control Channel，PDCCH)上发送指示Msg2位置的DCI。其中，Msg2中包含了第一步中解码得到的Preamble码标识、用户标识(用户识别码)、指示Msg3时频域位置的上行调度授权(Uplink Grant，UL Grant)和重传信息(backoff参数)等。用户在随机接入响应(Random Access Response，RAR)窗内侦听PDCCH信道，以便得到指示Msg2在PDSCH上的位置的下行控制消息，并在对应位置的PDSCH上接收并解码Msg2。如果用户解码得到的Preamble码标识与自身的Preamble码标识一致时，则进入竞争解决过程，即第三步；否则，用户将在0到backoff参数之间随机选择一个数值作为退避值，当退避到0后的首个PRACH资源上，执行第一步。
在第一步中，由于用户随机选择RACH资源中的某一个在上面发起随机接入，所以在第二步中，基站在RACH资源上检测到的Preamble码的结果可 能会出现三种情况：成功(Success，简写为S)，冲突(Collision，简写为C)，空闲(Idle，简写为I)。基站根据初始配置的随机接入信道资源上随机接入的用户状态反馈结果。也即，若某个RACH资源上没有用户发起随机接入(发送Preamble码)，则该RACH资源上的结果是空闲(I)；若某个RACH资源上有且只有1个用户发起随机接入(发送Preamble码)，则该RACH资源上的结果是成功(S)；否则，该RACH资源上的结果是冲突(C)。因此，用N表示某个RACH资源上发起随机接入的用户数，用F表示在该RACH资源上的结果，有
Figure PCTCN2022084960-appb-000007
这里，N的初始值为0。在每一次RACH资源配置更新时，基站重新预测和估计N的取值。在基于非竞争的随机接入方式中由基站的寻呼配置得到；在基于竞争的随机接入方式中基站根据上一次随机接入Preamble码的检测结果使用长短期记忆网络(LSTM，Long Short-Term Memory)估计得到。基于竞争的随机接入方式中Preamble码检测期间，基站可以获取Preamble的状态。即MIMO系统中基站发送的每个Preamble码的S/I/C状态。使用三元组T i＝{I i,S i,C i}表示MIMO系统中第i个随机接入时隙上Preamble码的状态集合。
MIMO系统中基站为了由观测到的随机变量T i的状态来估计激活用户数N i，
Figure PCTCN2022084960-appb-000008
其中，BW是随机接入的退避窗长(BackoffWindow，BW)内包含的时隙数目；N i,A是第i个随机接入时隙上有新数据到达等待发起随机接入的新激活用户数；N i-k,F(k)是第i-k个随机接入时隙上Preamble冲突导致随机接入失败后在第i个随机接入时隙上重新发起随机接入的用户数。因此，随机接入检 测结果P(N i)(即激活用户数N i的概率分布函数)建模如下：
P1：
Figure PCTCN2022084960-appb-000009
s.t.T k，k＝1,...,i
其中，T k(k＝1,...,i)是MIMO系统中基站发送的每个Preamble码的S/I/C状态的观测值；N i是需要预测的结果，分别将T k和N i作为设计的神经网络的输入和输出。MIMO系统中基站使用LSTM网络估计任一随机接入时隙上发起随机接入的用户数N i时，LSTM网络的记忆窗长L要设置为较大的值，比如设置为BW长度的几倍。这是因为随机接入冲突的用户重新发起随机接入时要在0到BW之间随机选择退避值重新发起随机接入。如果L设置太小，会使得LSTM网络无法记忆全部重传的用户；对应地，如果L设置太大，会浪费计算机的内存资源。通过设置合理的L，即可以丢弃冗余信息，又可以加速神经网络模型的训练。
当N个用户随机选择R 1个随机接入前导码集合中的Preamble码，等概率地在基站配置的R 2个RACH资源上发起随机接入时，RACH资源的利用率η定义为基站检测到的所有RACH资源上S状态总数(N S)与I状态总数(N I)和C状态总数N C之和的比值，η可以表示记为
Figure PCTCN2022084960-appb-000010
第二次握手过程，即竞争解决过程，包含第三步和第四步。
第三步，用户发送Msg3(调度传输)，基站接收Msg3。用户解析Msg2得到UL Grant和用户识别码，并在UL Grant指示的上行共享信道(Uplink Shared Channel，UL-SCH)的时频域位置上向基站发送携带用户码标识的Msg3。基站则在UL-SCH上侦听Msg3消息。
第四步，基站反馈Msg4(冲突解决)，用户接收Msg4。基站接收并解码Msg3，如果能够正确解码得到用户识别码，则在竞争解决定时器时长内的PDSCH上向用户发送Msg4，同时在PDCCH上发送携带Msg4位置的下行控制消息。用户在竞争解决定时器时长内侦听PDCCH信道，以便接收到下行控 制消息，并在PDSCH的相应位置上接收Msg4，表明用户成功完成随机接入。当用户在竞争解决定时器溢出时仍未接收到Msg4，则将Msg3传输次数加1，并判断是否超过Msg3传输允许的最大次数。如果没有超过，则执行第三步；如果超过，则将Msg1的传输次数加1，判断是否超过Msg1传输允许的最大次数，如果不超过，则按照重传参数执行退避后再执行第一步；如果超过，则视为用户随机接入失败。
由RACH资源的利用率η可以知道，η是R 1、R 2和N的函数。在上式中，基站可以根据需求的RACH资源利用率η需求来合理的配置随机接入前导码集合中的Preamble码总数R 1以及基站配置的RACH资源数R 2。鉴于一般情况下R 1是固定的，上行随机接入用户数N给定时，可以由下列优化问题很容易推导出满足RACH资源的利用率门限值η Threshold的最小RACH资源配置数R 2。
Figure PCTCN2022084960-appb-000011
从上述随机接入流程可以看出在现有的随机接入过程中，基站在RACH资源上检测到的Preamble码的结果与基站天线数无关。而实际上，在MIMO系统中，当基站配置K(K>1)根天线时，由多天线形成的空间自由度，是可以在基站侧同时区分开K个用户的数据的。也即，当用户发起随机接入时，多于K个用户使用同样的RACH资源才可以被认为是冲突的。因此，现有的随机接入协议没有很好地将新一代蜂窝系统中MIMO的空间优势发挥出来。
实施例一
本申请实施例一提供了一种如图1所示随机接入资源配置的更新方法适用的网络架构图；包括基站、用户设备。在该网络架构中，随机接入过程是由用户或基站触发的。触发条件包含用户的初始接入，如UE从RRC_IDLE态到RRC_CONNETTED态；无线链路重建立，保证UE在无线链路失败后重新建立无线连接和切换等条件。由用户触发的随机接入过程，用户在基站配置的随机接入资源RACH上发起随机接入过程；由基站触发的随机接入过程基站先 通过广播或寻呼信令通知用户，再由用户在基站配置的随机接入资源RACH上发起随机接入过程。
与传统蜂窝通信系统一样，在MIMO系统中，RACH资源上的结果可能会出现三种情况：成功(Success，简写为S)，冲突(Collision，简写为C)，空闲(Idle，简写为I)。当某个RACH资源上没有用户发起随机接入，则该RACH资源上的结果是空闲(I)；当某个RACH资源上有用户但不超过K个用户发起随机接入，则该RACH资源上的结果是成功(S)；否则，该RACH资源上的结果是冲突(C)。但由于MIMO系统中S/I/C状态的定义与传统蜂窝通信系统中S/I/C状态定义不同。在一个基站配置K根天线的MIMO系统中，用N表示某个RACH资源上发起随机接入的用户数，用F表示在该RACH资源上的结果，S/I/C状态定义如下
Figure PCTCN2022084960-appb-000012
和传统蜂窝通信系统类似，当N个用户随机选择R 1个随机接入前导码集合中的Preamble码，等概率地在基站配置的R 2个RACH资源上发起随机接入时，RACH资源的利用率η定义为基站检测到的所有RACH资源上S状态总数(N S)与I状态总数(N I)和C状态总数N C之和的比值，η可以表示记为
Figure PCTCN2022084960-appb-000013
其中，N S是用户数N、基站天线数K、随机接入前导码集合中的Preamble码总数R 1，以及基站配置的RACH资源数R 2的函数，但与传统蜂窝通信系统不同，N S不能再像传统蜂窝网络中的N S一样可以直观地写出其表达式。因此，基站也不能再能简单地根据需求的RACH资源利用率η需求来辅助基站直观地配置RACH资源数R 2。
实施例二
在实施例一的基础上，本申请实施例二提供了一种如图3所示适用于实施例一种网络架构的随机接入资源配置的更新方法：
第一步：基站初始化配置可用的随机接入资源R 2，即在国际标准化组织3GPP规范TS38.211中表5.7.1-2随机给出一种可选的RACH配置。并将RACH资源的利用率η的初始值为0，RACH资源的更新次数M＝0。
第二步：基站在广播上通过系统信息块(SIB2)广播可用的随机接入RACH资源配置R 2。
第三步：上行有数据要发送的用户在基站配置的RACH资源上发起随机接入过程。
第四步：基站根据检测到的所有RACH资源上S状态总数(N S)与I状态总数(N I)和C状态总数N C，统计随机接入RACH资源的利用率η
Figure PCTCN2022084960-appb-000014
这里，在一个基站配置K根天线的MIMO系统中，用N表示某个RACH资源上发起随机接入的用户数，用F表示在该RACH资源上的结果，S/I/C状态定义如下：
Figure PCTCN2022084960-appb-000015
第五步：基站将统计到的随机接入RACH资源利用率η与预先设定的随机接入RACH资源利用率门限值η Threshold比较，并判定η是否超过预设的门限值η Threshold(η<η Threshold)。若满足，转到第六步；否则，转到第八步。
第六步：基站将RACH资源更新次数M的数值增加1。
第七步：基站按照RACH资源更新函数来得到更新后的RACH资源数
Figure PCTCN2022084960-appb-000016
更新函数如下：
Figure PCTCN2022084960-appb-000017
其中，非负数α M是基站第M次更新RACH资源时的权重值，用于控制资源的更新量；
Figure PCTCN2022084960-appb-000018
表示向上取整运算，是为了保证每次更新后的RACH资源数目为蜂窝通信系统中最小资源块数目的整数倍；
Figure PCTCN2022084960-appb-000019
是为了使配置的RACH 资源利用率不低于设定的阈值而新增加的RACH资源数目。这里，可以通过调节非负数α M来确保每次增加的数目越来越近最优配置，并返回第三步。
第八步：基站在3GPP规范TS38.211中的表5.7.1-2中寻找最接近于此时R 2值的配置进行配置，基站重新将RACH资源的利用率η设置为初始值为0，RACH资源的更新次数M＝1，结束RACH资源的更新过程。
需要说明的是，在上述第二步中，传统的4G网络中每个RACH资源上可能有0个、1个或者多个用户发送自己的Preamble序列，即每个RACH资源上的空闲/成功/冲突(Idle/Success/Collision，I/S/C)解释如下：反馈结果为I表示该RACH资源上没有检测到用户发送Preamble序列；为S表示检测测到1个用户发送Preamble序列，因而发送成功；为C表示检测到多个用户发送其Preamble序列，发生了冲突。而在5G NR系统中，由于采用了多天线MIMO技术，当基站配置有K根接收天线时基站每次可以区分出最多K个用户的序列/信号。因此，此时每个RACH资源上的空闲/成功/冲突(Idle/Success/Collision，I/S/C)解释如下：反馈结果为I表示该RACH资源上没有检测到用户发送Preamble序列；为S表示检测测到K个用户发送Preamble序列，因而发送成功；为C表示检测到多于K个用户发送其Preamble序列，发生了冲突。
图4为本实施例中MIMO系统基站使用LSTM网络估计用户数的流程图。MIMO系统中，基站配置RACH资源时，由于无法准确获取随机接入的用户数，因此N的初始值为0。在每一次RACH资源配置更新时，基站重新预测和估计N的取值。在基于非竞争的随机接入方式中由基站的寻呼配置得到；在基于竞争的随机接入方式中基站根据上一次随机接入Preamble码的检测结果使用如图4所示长短期记忆网络(LSTM，Long Short-Term Memory)估计得到。基于竞争的随机接入方式中Preamble码检测期间，基站可以获取Preamble的状态。即MIMO系统中基站发送的每个Preamble码的S/I/C状态。使用三元组T i＝{I i,S i,C i}表示MIMO系统中第i个随机接入时隙上Preamble码的状态集合。T i＝{I i,S i,C i}
MIMO系统中基站为了由观测到的随机变量T i的状态来估计激活用户数N i，
Figure PCTCN2022084960-appb-000020
其中，BW是随机接入的退避窗长(Backoff Window，BW)内包含的时隙数目；N i,A是第i个随机接入时隙上有新数据到达等待发起随机接入的新激活用户数；N i-k,F(k)是第i-k个随机接入时隙上Preamble冲突导致随机接入失败后在第i个随机接入时隙上重新发起随机接入的用户数。因此，随机接入检测结果P(N i)(即激活用户数N i的概率分布函数)建模如下：
P1：
Figure PCTCN2022084960-appb-000021
s.t.T k，k＝1,...,i
其中，T k(k＝1,...,i)是MIMO系统中基站发送的每个Preamble码的S/I/C状态的观测值；N i是需要预测的结果，分别将T k和N i作为设计的神经网络的输入和输出。
在本实施例中，MIMO系统基站基于LSTM网络预测和估计随机接入用户数的网络中包含LSTM单元和两个全连接(Fully Connected，FC)网络。LSTM网络600的循环线长度为BW长度的最大值；对于LSTM单元而言，其输入为MIMO系统中第i个随机接入时隙上Preamble码的状态集合，即三元组T i＝{I i,S i,C i}，因此，输入节点设置数目设置为3；隐层节点数目越多，网络的训练性能越好，然而训练复杂度也会随之增加，为兼顾系统性能和降低复杂度，隐层节点数目设置与退避窗长BW相同。其中全连接网络A700的输入为BW维，输出为BW/2维；全连接网络B800的输入为BW/2维，输出为1维；对全连接网络(全连接网络A700和全连接网络B800)而言，输出维度从BW维降到1维，输出用于估计预测MIMO系统中发起等待发起随机接入的激活用户数N i的概率分布函数P(N i)。
在本实施例中，MIMO系统中基站使用LSTM网络估计任一随机接入时隙上发起随机接入的用户数N i时，LSTM网络的记忆窗长L要设置为较大的值， 因为随机接入冲突的用户重新发起随机接入时要在0到BW之间随机选择退避值重新发起随机接入。如果L设置太小，会使得LSTM网络无法记忆全部重传的用户；对应地，如果L设置太大，会浪费计算机的内存资源。通过设置合理的L，即可以丢弃冗余信息，又可以加速神经网络模型的训练。训练时将LSTM网络的记忆窗长设置为最大BW长度。
图5为本实施例提供了一种基站的结构化示意图。本发明实施例中的基站可以是图2至图4所示任一实施例提供的基站。图5所示的基站500包括：处理器501和收发器502。其中，处理器501用于RACH过程中更新参数值，收发器502用于实现RACH配置的广播与解析接收到的Preamble码等功能，处理器501和收发器502相连，例如通过总线相连。基站500还可以包括存储器503，用于存储RACH更新的配置信息以及RACH过程中的中间量，比如S/I/C状态的统计等。需要说明的是本实施例对处理器501和收发器502的数量不做限定，该基站500的结构并不构成对本实施例的限定。收发器502可以通过接收器和发射器来实现。
在本实施例中，处理器501可以是中央处理器(Central Processing Unit，CPU)，通用处理器，数字信号处理(Digital Signal Processing，DSP)，集成电路(ApplicationSpecific Integrated Circuit，ASIC)，现场可编程逻辑门阵列(Field-ProgrammableGate Array，FPGA)或者其他可编程逻辑器件、晶体管逻辑器件、硬件部件或者其任意组合。其可以实现或执行结合本发明的逻辑方框，模块和电路。处理器501也可以是实现计算功能的组合，例如包含一个或多个微处理器组合，DSP和微处理器的组合等等。
存储器503可以是只读存储器(read-only memory，ROM)或可存储静态信息和指令的其他类型的静态存储设备，随机存取存储器(random access memory，RAM)或者可存储信息和指令的其他类型的动态存储设备，也可以是电可擦可编程只读存储器(Electrically Erasable Programmable Read-Only Memory，EEPROM)、只读光盘(Compact Disc Read-Only Memory，CD-ROM)或其他光盘存储、光碟存储(包括压缩光碟、激光碟、光碟、数字通用光碟、蓝光光碟等)、磁盘存储介质或者其他磁存储设备、或者能够用于携带或存储具有指令或数据结构形式的期望的程序代码并能够由计算机存取的任何其他介质，但 不限于此。
具体实现中，本发明实施例中所描述的处理器501、收发器502可执行图2所示的现有的蜂窝无线通信系统中的随机接入流程或图3所示的本发明中基站所执行的随机接入方法，在此不再赘述。
计算机可读存储介质可以是任一基站的内部存储单元，例如基站的硬盘或内存。计算机可读存储介质也可以是基站的外部存储设备，例如基站上配备的插接式硬盘，智能存储卡(Smart Media Card,SMC)，安全数字(Secure Digital,SD)卡，闪存卡(Flash Card)等。进一步地，计算机可读存储介质还可以既包括基站的内部存储单元也包括外部存储设备。计算机可读存储介质用于存储计算机程序以及基站所需的其他程序和数据。计算机可读存储介质还可以用于暂时地存储已经输出或者将要输出的数据。
本说明书中各个实施例采用递进的方式描述，每个实施例重点说明的都是与其他实施例的不同之处，各个实施例之间相同相似部分互相参见即可。
本文中应用了具体个例对本发明的原理及实施方式进行了阐述，以上实施例的说明只是用于帮助理解本发明的方法及其核心思想；同时，对于本领域的一般技术人员，依据本发明的思想，在具体实施方式及应用范围上均会有改变之处。综上所述，本说明书内容不应理解为对本发明的限制。

Claims (8)

  1. 一种多天线MIMO场景下随机接入资源的配置与更新方法，其特征在于，包括以下步骤：
    步骤1、基站初始化：配置可用的RACH资源R 2；并将RACH资源利用率η的初始值设置为0，将RACH资源的更新次数M的初始值设置为M＝0；
    步骤2、基站通过系统信息块SIB2广播可用的RACH资源R 2；当基站配置有K根接收天线时空间自由度最大为K，基站每次区分出K个用户的序列或信号；
    步骤3、上行有数据待发送的用户在基站配置的RACH资源上发起随机接入过程；
    步骤4、为多输入多输出MIMO系统中的每个基站配置多根天线，构成的空间自由度用K来表示；用N表示RACH资源上等待发起随机接入的激活用户数，用F表示在该RACH资源上的结果，对S状态、I状态、C状态进行重新定义；N的初始值为0，基站重新预测和估计N的取值时，在基于非竞争的随机接入方式中，RACH资源上等待发起随机接入的激活用户数N由基站的寻呼配置得到；在基于竞争的随机接入方式中，基站根据上一次随机接入Preamble码的检测结果使用长短期记忆网络估计得到RACH资源上等待发起随机接入的激活用户数N；
    步骤5、基站将统计到的RACH资源利用率η与预先设定的RACH资源利用率门限值η Threshold进行比较，并判定η是否超过预设的门限值η Threshold；若满足η<η Threshold，则执行步骤6至步骤7；否则，执行步骤8；
    步骤6、基站将RACH资源的更新次数M的数值增加1：M＝M+1；
    步骤7、基站按照RACH资源更新函数来得到更新后的RACH资源数
    Figure PCTCN2022084960-appb-100001
    更新函数如下：
    Figure PCTCN2022084960-appb-100002
    上式中，非负数α M是基站第M次更新RACH资源时的权重值；
    Figure PCTCN2022084960-appb-100003
    表示对α M和R 2的乘积进行向上取整运算；通过调节非负数α M来确保每次增加的数目接近最优配置，并返回执行步骤3至步骤5，直至η≥η Threshold；
    步骤8、在相关标准表中寻找最接近于此时R 2值的RACH资源配置，对基站进行配置；重新将基站内RACH资源的利用率η设置为初始值0，RACH资 源的更新次数也设置为M＝0，结束RACH资源的更新过程。
  2. 根据权利要求1所述多天线MIMO场景下随机接入资源的配置与更新方法，其特征在于，步骤1中基站包括：处理器(501)和收发器(502)，处理器(501)和收发器(502)相连；处理器(501)用于RACH过程中更新参数值，收发器(502)用于配置RACH的广播与解析接收到的Preamble码。
  3. 根据权利要求1所述多天线MIMO场景下随机接入资源的配置与更新方法，其特征在于，步骤1中基站还包括存储器(503)，存储器(503)用于存储RACH更新的配置信息以及RACH过程中的中间量。
  4. 根据权利要求2所述多天线MIMO场景下随机接入资源的配置与更新方法，其特征在于，收发器(502)包括接收器和发射器；处理器(501)为中央处理器、通用处理器、数字信号处理、集成电路、现场可编程逻辑门阵列、其他可编程逻辑器件、晶体管逻辑器件、硬件部件中的至少一种；处理器(501)和收发器(502)通过总线相连。
  5. 根据权利要求3所述多天线MIMO场景下随机接入资源的配置与更新方法，其特征在于，存储器(503)为只读存储器、静态存储设备、随机存取存储器、动态存储设备、电可擦可编程只读存储器、只读光盘、光碟存储或磁盘存储介质。
  6. 根据权利要求1所述多天线MIMO场景下随机接入资源的配置与更新方法，其特征在于，步骤2中当基站配置有K根接收天线时空间自由度最大为K，每个RACH资源上的空闲、成功、冲突具体为：
    当该RACH资源反馈结果为I状态时，表示该RACH资源上没有检测到用户发送的Preamble序列，该RACH空闲；
    当该RACH资源反馈结果为S状态时，表示检测到至少一个但不超过用户发送Preamble序列，该RACH上用户发送Preamble序列成功；
    当该RACH资源反馈结果为C状态时，表示检测到多于K个用户发送Preamble序列，该RACH上发生了冲突。
  7. 根据权利要求1所述多天线MIMO场景下随机接入资源的配置与更新方法，其特征在于，步骤4中S状态、I状态、C状态重新定义如下：
    S状态、I状态、C状态定义如下：
    Figure PCTCN2022084960-appb-100004
    上式中，I状态表示RACH资源反馈结果为空闲状态，S状态表示RACH上用户发送Preamble序列成功；C状态表示RACH上发生了冲突；N的初始值为0；
    在每一次RACH资源配置更新时，基站重新预测和估计N的取值；在基于非竞争的随机接入方式中，RACH资源上等待发起随机接入的激活用户数N由基站的寻呼配置得到；在基于竞争的随机接入方式中，基站根据上一次随机接入Preamble码的检测结果使用长短期记忆网络估计得到RACH资源上等待发起随机接入的激活用户数N；基于竞争的随机接入方式中Preamble码检测期间，基站获取Preamble的状态；使用三元组T i＝{I i,S i,C i}表示MIMO系统中第i个随机接入时隙上Preamble码的状态集合；MIMO系统中基站由观测到的随机变量T i的状态来估计激活用户数N i，
    Figure PCTCN2022084960-appb-100005
    其中，BW是随机接入的退避窗长内包含的时隙数目；N i,A是第i个随机接入时隙上有新数据到达等待发起随机接入的新激活用户数；N i-k,F(k)是第i-k个随机接入时隙上Preamble冲突导致随机接入失败后在第i个随机接入时隙上重新发起随机接入的用户数；因此，随机接入检测结果P(N i)建模如下：
    Figure PCTCN2022084960-appb-100006
    s.t.  T k，k＝1,...,i
    其中，T k，k＝1,...,i是MIMO系统中基站发送的每个Preamble码的S/I/C状态的观测值；N i是需要预测的结果，分别将T k和N i作为长短期记忆网络的输入和输出；
    基站根据检测到的所有RACH资源上S状态总数、I状态总数和C状态总数，统计RACH资源的利用率η：
    Figure PCTCN2022084960-appb-100007
    上式中，N S为所有RACH资源上S状态的总数；N I为所有RACH资源上I状态的总数；N C为所有RACH资源上C状态总数；R 1为随机接入前导码集合中的Preamble码数目；R 2为可用的RACH资源个数；η为所有RACH资源的利用率。
  8. 根据权利要求1所述多天线MIMO场景下随机接入资源的配置与更新方法，其特征在于，步骤8中相关标准表为3GPP规范TS38.211中的表5.7.1-2。
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