A HARQ-based URLLC bandwidth optimization method, device, equipment and medium

Abstract

The present invention discloses a URLLC bandwidth optimization method, apparatus, device and medium based on HARQ. The method comprises: step S1: establishing a URLLC finite block length model; step S2: establishing a delay model and a reliability model under the URLLC finite block length model, and obtaining a total delay and a decoding failure probability respectively; step S3: constraining the total delay and the decoding failure probability respectively, and obtaining a maximum number of HARQ retransmissions η; step S4: obtaining a system bandwidth lower limit w based on the maximum number of HARQ retransmissions η. m , and the system required bandwidth w and the w m For comparison, when w>w m When w≤w m When the w m As the minimum bandwidth of the system, m = 0, 1, ..., 4, representing the sequence number corresponding to the subcarrier spacing. The present invention ensures low latency and high reliability of URLLC services while optimizing bandwidth to achieve the purpose of saving resources.

Description

Technical Field

[0001] The present invention belongs to the field of wireless communication technology, and in particular relates to a URLLC bandwidth optimization method, device, equipment and medium based on HARQ. Background Art

[0002] The core service that the 5th Generation Mobile Communication Network (5G) is expected to enable, Ultra-Reliable and Low-Latency Communication (URLLC), needs to provide users with millisecond-level end-to-end latency and a service reliability guarantee of nearly 99.999% (i.e., a packet loss rate of less than 10%) when transmitting 32-bit data packets. -5 ). Similar to LTE (Long-Term Evolution) technology, Hybrid Automatic Repeat reQuest (HARQ) technology can also be applied to New Radio (NR) technology to improve reliability. However, blindly pursuing reliability may cause end-to-end delay to exceed the limit. Therefore, the reasonable design of the retransmission scheme is a huge challenge to ensure the millisecond-level low latency and high reliability requirements of URLLC. Most existing technologies only focus on methods to achieve high reliability, or only focus on methods to achieve low latency, but lack delay analysis related to reliability, retransmission and bandwidth.

[0003] In their paper, "5G Ultra-Reliable and Low-Latency Systems Design" (EuCNC), C.-P. Li, J. Jiang, W. Chen, T. Ji, and J. Smee proposed a method to meet URLLC latency requirements by shortening the Transmission Time Interval (TTI) and the time required to retransmit packets. However, this method lacks an analysis of the bandwidth resources required for transmission, potentially resulting in wasted bandwidth.

[0004] In their paper “Resource allocation and HARQ optimization for URLLC traffic in 5G wireless networks” (IEEE J. Sel. Areas Commun), A. Anand and G. de Veciana proposed a scheme to control the maximum number of transmissions and minimize bandwidth using the square root configuration rule (Sum of Squares due to Regression algorithm, SSRO). The disadvantage of this method is that there is no queuing delay analysis based on URLLC services, nor is it considered in scenarios where URLLC packets can be transmitted on demand. These factors must be considered when there are multiple URLLC users, such as when controlling a swarm of drones or a queue of autonomous vehicles. Summary of the Invention

[0005] The present invention provides a HARQ-based URLLC bandwidth optimization method, device, equipment and medium to solve at least one of the above technical problems.

[0006] In a first aspect, the present invention provides a URLLC bandwidth optimization method based on HARQ, comprising:

[0007] Step S1: Establishing a URLLC finite block length model;

[0008] Step S2: Under the URLLC finite block length model, a delay model and a reliability model are established to obtain the total delay and decoding failure probability respectively;

[0009] Step S3: Constraining the total delay and the decoding failure probability respectively to obtain the maximum number of HARQ retransmissions η;

[0010] Step S4: Based on the HARQ maximum retransmission number η, the system bandwidth lower limit w is obtained m , and the system required bandwidth w and the w m For comparison, when w>w m When w≤w m When the w m As the minimum bandwidth of the system, where m = 0, 1, ..., 4, representing the sequence number corresponding to the subcarrier spacing.

[0011] The above technical solution, through mathematical analysis of the reliability, latency, and allocated bandwidth of 5G gNB (next generation NodeB) control, ensures low latency and high reliability of URLLC services while optimizing bandwidth and achieving the goal of saving resources.

[0012] Optionally, step S1 further includes:

[0013] Use a channel with a channel factor of r to transmit data packets of finite block length, where r is calculated as follows:

[0014]

[0015]

[0016]

[0017] Where L is the number of bits contained in a data packet of finite block length; The user's signal to interference plus noise ratio (SINR); is the probability of decoding failure; is the channel capacity; is the channel dispersion; Q -1 (p) is the inverse function of Q with respect to p.

[0018] Optionally, step S2 further includes:

[0019] The total delay T total The calculation formula is as follows:

[0020]

[0021] Among them, T queue is the queuing delay; T trans is the transmission delay; T UE T is the processing time of the packet at the UE; gNB The delay of packet processing in gNB; is the number of HARQ retransmissions; t A The waiting time from when a data packet is ready for transmission to the start of the next TTI;

[0022] When using CC-HARQ transmission, the probability of decoding failure for the kth transmission is The calculation formula is as follows:

[0023]

[0024] Wherein, g is a parameter derived from the Modulation and Coding Scheme (MCS); is the maximum SINR when the decoding failure probability is 1; is the SINR of the user during the k-th transmission.

[0025] Optionally, when CC-HARQ is used for transmission, when the receiver uses Maximum Ratio Combination (MRC) to decode the kth packet,

[0026] Optionally, when transmitting URLLC services in mini-time slots, the queuing delay T queue The calculation formula is as follows:

[0027]

[0028] Among them, T gNB is the processing time of the packet in the gNB; TTI is the basic time unit for dynamic scheduling resources; t A The waiting time after a data packet is ready for transmission until the next TTI begins.

[0029] Optionally, step S3 further includes:

[0030] T total <T d ;

[0031]

[0032] Among them, T total is the total delay, T d is the constraint delay; δ is the reliability constraint.

[0033] Optionally, step S4 further includes:

[0034]

[0035] in,

[0036]

[0037]

[0038] Where m = 0, 1, ..., 4, representing the sequence number corresponding to the subcarrier spacing; λ down is the total average downlink arrival rate; α is the number of packets with a finite block length of L bits; p i is the i-th decoding failure rate during the k-th transmission.

[0039] In a second aspect, the present invention further provides a HARQ-based URLLC bandwidth optimization device, comprising:

[0040] The first establishment module is used to establish a URLLC finite block length model;

[0041] The second establishment module is used to establish a delay model and a reliability model under the URLLC finite block length model to obtain a total delay and a decoding failure probability respectively;

[0042] A constraint module, configured to constrain the total delay and the decoding failure probability respectively to obtain a maximum number of HARQ retransmissions η;

[0043] The bandwidth optimization module is used to obtain the system bandwidth lower limit w based on the HARQ maximum retransmission number η m , and the system required bandwidth w and the w m For comparison, when w>w m When w≤w m When the w m As the minimum bandwidth of the system, where m = 0, 1, ..., 4, representing the sequence number corresponding to the subcarrier spacing.

[0044] In a third aspect, the present invention further provides a network-side device, including a memory, a transceiver, and a processor:

[0045] A memory for storing a computer program; a transceiver for sending and receiving data under the control of the processor; and a processor for reading the computer program in the memory and executing the URLLC bandwidth optimization method based on HARQ as described in the first aspect above.

[0046] In a fourth aspect, the present invention further provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the URLLC bandwidth optimization method based on HARQ as described in the first aspect above.

[0047] Compared with the prior art, the present invention has the following beneficial effects:

[0048] By mathematically analyzing the reliability, latency, and allocated bandwidth of 5G gNB control, we optimized bandwidth and achieved resource savings while ensuring low latency and high reliability for URLLC services. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] In order to more clearly illustrate the technical solutions in the present invention or the prior art, a brief introduction is given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0050] Figure 1 1 is a flow chart of a HARQ-based URLLC bandwidth optimization method according to an embodiment of the present invention;

[0051] Figure 2 2. A model diagram of a URLLC finite block length system according to an embodiment of the present invention;

[0052] Figure 3 is a 2-symbolst TTI diagram according to an embodiment of the present invention;

[0053] Figure 4 is a processing delay diagram under different subcarrier spacings of 5G NR according to an embodiment of the present invention;

[0054] Figure 5 This is a delay simulation diagram under different subcarrier spacings according to an embodiment of the present invention;

[0055] Figure 6 This is a simulation diagram of decoding failure probability under different SINRs according to an embodiment of the present invention;

[0056] Figure 7 This is a simulation diagram comparing the performance of two algorithms based on different packet arrival rates according to an embodiment of the present invention;

[0057] Figure 8 2 is a schematic structural diagram of a HARQ-based URLLC bandwidth optimization device according to an embodiment of the present invention;

[0058] Figure 9 It is a structural diagram of a network side device according to an embodiment of the present invention. DETAILED DESCRIPTION

[0059] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0060] The present invention targets URLLC services and utilizes different subcarrier spacing and mini-slots to shorten time intervals and establish an expression for queuing delay and transmission delay. CC-HARQ (Chase Combining HARQ) is then used to establish an expression for decoding failure probability (reliability). The bandwidth optimization problem is established based on delay, reliability, and system constraints. Finally, bandwidth requirements are optimized by controlling the maximum retransmission parameter of the hybrid automatic repeat request (HARQ) mechanism in URLLC.

[0061] The following combination Figures 1-9 Specific embodiments of the present invention are described.

[0062] like Figure 1 As shown, the URLLC bandwidth optimization method based on HARQ includes the following steps:

[0063] Step S1: Establishing a URLLC finite block length model;

[0064] Specifically, if Figure 2 As shown, there are multiple users (assuming they are of the same type and have the same SINR) and the system model has only one base station serving the URLLC service. When the gNB analyzes the Channel State Information (CSI), each packet of a certain class is transmitted and served based on the queueing order. The 5G gNB base station uses the 3 GHz and mmWave frequency bands (based on the Release 16 3GPP standard on URLLC) to transmit data packets to multiple users and allocates resources through a flexible subcarrier spacing system. The gNB transmits α finite blocks of length L to the i-th user equipment (UE) (among M users). i The i-th user equipment is denoted as U i (i=1,2,...M). In order to transmit a packet containing Li bits of information, a channel factor of r is required. i channels, where:

[0065]

[0066]

[0067]

[0068] Where Li is the number of bits contained in a data packet of finite block length; is the SINR of Ui; is the probability of decoding failure of Ui; is the channel capacity of Ui; is the channel dispersion of Ui; Q -1 (p) is the inverse function of Q with respect to p.

[0069] Step S2: Under the URLLC finite block length model, a delay model and a reliability model are established to obtain the total delay and decoding failure probability respectively;

[0070] Step S2.1: Establish a time delay model.

[0071] A simple way to meet URLLC QoS (Quality of Service) is to reduce the duration of TTI and HARQ RTT (Round-Trip Time) to allow more HARQ retransmissions for high reliability. Reducing TTI duration includes using fewer Orthogonal Frequency Division Multiplexing (OFDM) symbols in one TTI and shortening OFDM symbols by increasing the subcarrier spacing. Short OFDM symbols can also enable more efficient pipeline processing, resulting in a tighter HARQ RTT timeline. This solution uses a 2-symbols mini-time slot method to transmit URLLC services, such as Figure 3 shown.

[0072] T UE and T gNB The values ​​are fixed and depend on the capabilities of the UE and gNB. Assuming that each subframe consists of 14 OFDM symbols, the processing delay and subframe duration of 5GNR at different subcarrier spacing are as follows: Figure 3 As shown, and the duration of the mini-time slot TTI is as follows Figure 4 shown.

[0073] It is assumed that the number of transmitted data packets in the gNB follows a Poisson distribution. Since each user application has a different packet length, a general distribution is required to model the service time. Since packets are transmitted one by one, the system adopts the M / G / 1 queuing model. The M / G / 1 queuing model applies a Poisson-distributed packet arrival rate and a general distribution for the service rate, with packets being served one by one. When a packet is generated, it is placed in the gNB's queue. Queuing delay and transmission delay occur at the gNB. If the receiver cannot decode a packet, it returns a NACK requesting retransmission up to φ times. Once decoding is successful, no ACK is returned. The total delay should be less than the delay constraint. The transmission delay can be expressed as:

[0074] T=T queue +Ttrans +T UE +T gNB ;

[0075] Among them, T queue is the queuing delay; T trans is the transmission delay, T gNB is the packet processing time in gNB, T UE It is the processing time of the packet at the receiving end UE.

[0076] Assume that the data packet can arrive at the gNB buffer at any time within the TTI (2-symbols) interval. From the start of TTI t A The initial offset time is uniformly distributed, i.e., t A ~U(0,TTI). Once the data packet arrives at the gNB buffer, the gNB consumes T gNB It is processed and prepared for transmission. Then, once the time alignment is complete, it is transmitted. The data packet is transmitted over a TTI, which is T trans =TTI. Finally, UE consumes T UE Therefore, the waiting time for a packet in the gNB buffer before transmission is:

[0077]

[0078] in, is the smallest integer greater than x; T gNB is the packet processing time in the gNB; t A Used for time alignment, it indicates the waiting time from when a data packet is ready for transmission to the start of the next TTI.

[0079] According to the Poisson Arrivals See Time Average (PASTA) property, the average downlink arrival rate of each retransmission round is down The service rate is u, and the average service time is The reserved interval is The interval changes to v refers to the reservation interval. The frame format supported by the 5G system is defined in the 3GPP standardization and can be assumed to follow a fixed frame format. Therefore, the uplink request can be assumed to be periodic, where the constant interval results in For the convenience of analysis, it can be assumed that

[0080] Assume that a packet is retransmitted φ times before being correctly decoded by the UE. Consider the packet time alignment problem. Therefore, the delay of each transmitted packet can be written as:

[0081]

[0082] Since the required channel usage is determined by the message length, the channel r i The relationship between the decoding failure probability and SINR in the function and the bandwidth allocation according to the communication characteristics (such as message arrival rate), where the service time can be expressed as

[0083]

[0084] Among them, s i is the period of transmission time; k i is the number of channels used per unit bandwidth and per unit time, h i is the allocated transmission bandwidth. To derive the expected r, L and The expected approximation can be applied to the derivative r i In the formula.

[0085]

[0086] The distribution of packet length (L i The E(L) can be obtained through traffic monitoring, or it can be approximated by the message length distribution function. i ), Since transmission delay and queuing delay are needed to analyze the overall delay, the transmission delay can be simplified to

[0087] Step S2.2: Establish a reliability model.

[0088] In HARQ schemes, packet decoding may fail at the receiver, leading to retransmissions. Based on delay constraints, the number of transmission attempts is limited by the maximum number of retransmissions, η. Various HARQ schemes can be considered, such as IR-HARQ (Incremental Redundancy HARQ) and CC-HARQ (Chase Combining HARQ).

[0089] In this system, the HARQ scheme is CC-HARQ. If the reception decoding fails, the gNB will retransmit the same packet. The total average downlink arrival rate at the gNB is in is the number of retransmission attempts, is the PER (probability error) at the kth transmission, Based on the block fading channel model, p k As shown in the following formula:

[0090]

[0091] Among them, g is the parameter derived from MCS, The maximum SINR when the decoding failure probability is 1 can be calculated based on the MCS. In the CC-HARQ scheme, the receiver combines the received (k-1) packets and uses MRC (Maximum Ratio combination) to decode the kth packet, where In the formula (For example, if k = 2, then ).

[0092] Step S3: Constraining the total delay and the decoding failure probability respectively to obtain the maximum number of HARQ retransmissions η;

[0093] T total <T d ;

[0094]

[0095] Among them, T total is the total delay, T d is the constraint delay; δ is the reliability constraint, for example, T d Can be constrained to 1ms, δ can be set to 10 -5 , you can also set 10 -6 The value of δ can be obtained by setting the PER value.

[0096] Step S4: Based on the HARQ maximum retransmission number η, the system bandwidth lower limit w is obtained m , and the system required bandwidth w and the w m For comparison, when w>w m When w≤w m When the w m As the minimum bandwidth of the system, where m = 0, 1, ..., 4, representing the sequence number corresponding to the subcarrier spacing.

[0097] Specifically, the system load ρ < 1 is necessary to maintain a stable queue system. The bandwidth lower bound becomes λ down E[r i ]<W to maintain stability. Therefore, based on Δf=15(2 m )(m=0,1,2,3,4)kHz, the lower bound of a stable queuing system is shown below.

[0098]

[0099] Where λ down is the downlink arrival rate.

[0100]

[0101]

[0102]

[0103]

[0104] Since in the system model, the bandwidth Therefore, under the maximum retransmission parameter of the hybrid automatic repeat request (HARQ) mechanism in URLLC, the minimum bandwidth required by the system is W * If: the bandwidth W>W m , that is, W * =W; otherwise, W * =W m .

[0105] The effects of the present invention are further described below in conjunction with simulation experiments:

[0106] 1. Simulation experiment conditions:

[0107] The software platforms for the simulation experiment of the present invention are: Windows 10 operating system and Matlab2021a.

[0108] The simulation experiment of the present invention uses a certain type C user, the number of users M=10, and the delay constraint T d =1ms, PER constraint δ=10 -6 .

[0109] 2. Simulation content and results analysis:

[0110] The simulation experiment of the present invention adopts a short TTI of 2-symbols for transmission. The total delay simulation under different subcarrier spacing is as follows: Figure 5 Under different SINR, the decoding failure probability simulation is as follows: Figure 6 And under Δf = 120kHz, the performance is compared with the SSRO algorithm (homogeneous transmission model) in terms of message arrival rate, message length and SINR (i.e. p1 = p2 = ... p φ ), the decoding failure probability of each transmission round is the same, that is, repeated encoding. ) performance comparison, simulation as Figure 7 .

[0111] The following combination Figure 5 、 Figure 6 and Figure 7 The effect of the simulation diagram is further described.

[0112] Depend on Figure 5As can be seen, as the subcarrier spacing increases, the symbol duration shortens, and the delay also decreases. At Δf = 120 kHz and Δf = 240 kHz, the total delay is less than the delay constraint of 1 ms within the maximum number of transmissions 1-7.

[0113] from Figure 6 It can be seen that if the maximum number of transmissions increases, the probability of decoding failure allowed in each round will also increase. As SINR increases, reliability becomes higher. When SINR = 20dB, when the number of retransmissions is greater than or equal to 4 times, the high reliability of URLLC service is met. -5 This is because under the CC-HARQ scheme, each retransmission transmits the same data packet as the initial transmission, and decoding is performed on all transmitted data packets, which greatly improves the decoding accuracy.

[0114] from Figure 7 As can be seen, while meeting URLLC requirements, the proposed method requires less bandwidth than SSRO, with the performance gain of the proposed scheme increasing with the packet arrival rate. This is because SSRO blocks and discards packets when there is insufficient bandwidth to immediately support transmission, while the proposed algorithm places packets in the gNB's transmission queue, which has the effect of saving bandwidth.

[0115] The above simulation experiments show that this method, for URLLC services, shortens time intervals by using different subcarrier spacing and mini-slots; employs CC-HARQ (Chase Combining HARQ) for retransmission; establishes a bandwidth optimization problem by considering latency, reliability, and system constraints; and finally optimizes bandwidth requirements by controlling the maximum retransmission parameter of the Hybrid Automatic Repeat Request (HARQ) mechanism in URLLC. This method not only ensures low latency and high reliability for URLLC services, but also conserves bandwidth resources, making it a very practical method for transmitting URLLC services.

[0116] The HARQ-based URLLC bandwidth optimization device provided by the present invention is described below. The HARQ-based URLLC bandwidth optimization device described below and the HARQ-based URLLC bandwidth optimization method described above can refer to each other.

[0117] like Figure 8 As shown, the URLLC bandwidth optimization device based on HARQ includes:

[0118] The first establishment module is used to establish a URLLC finite block length model;

[0119] The second establishment module is used to establish a delay model and a reliability model under the URLLC finite block length model to obtain a total delay and a decoding failure probability respectively;

[0120] A constraint module, configured to constrain the total delay and the decoding failure probability respectively to obtain a maximum number of HARQ retransmissions η;

[0121] The bandwidth optimization module is used to obtain the system bandwidth lower limit w based on the HARQ maximum retransmission number η m , and the system required bandwidth w and the w m For comparison, when w>w m When w≤w m When the w m As the minimum bandwidth of the system, where m = 0, 1, ..., 4; represents the sequence number corresponding to the subcarrier spacing.

[0122] Optionally, step S1 further includes:

[0123] Use a channel with a channel factor of r to transmit data packets of finite block length, where r is calculated as follows:

[0124]

[0125]

[0126]

[0127] Where L is the number of bits contained in a data packet of finite block length; The user's signal to interference plus noise ratio (SINR); is the probability of decoding failure; is the channel capacity; is the channel dispersion; Q -1 (p) is the inverse function of Q with respect to p.

[0128] Optionally, step S2 further includes:

[0129] The total delay T total The calculation formula is as follows:

[0130]

[0131] Among them, T queue is the queuing delay, T trans is the transmission delay, T UE is the packet processing time at the UE; T gNBis the delay in packet processing, is the number of HARQ retransmissions, t A The waiting time after a data packet is ready for transmission until the next TTI begins.

[0132] When using CC-HARQ transmission, the probability of decoding failure for the kth transmission is The calculation formula is as follows:

[0133]

[0134] Wherein, g is a parameter derived from the Modulation and Coding Scheme (MCS); is the maximum SINR when the decoding failure probability is 1; is the SINR of the user during the k-th transmission.

[0135] Optionally, when CC-HARQ is used for transmission, when the receiver uses Maximum Ratio Combination (MRC) to decode the kth packet,

[0136] Optionally, when transmitting URLLC services in mini-time slots, the queuing delay T queue The calculation formula is as follows:

[0137]

[0138] Among them, T gNB is the processing time of the packet in the gNB; TTI is the basic time unit for dynamic scheduling resources; t A The waiting time after a data packet is ready for transmission until the next TTI begins.

[0139] Optionally, step S3 further includes:

[0140] T total <T d ;

[0141]

[0142] Among them, T total is the total delay, T d is the constraint delay; δ is the reliability constraint.

[0143] Optionally, step S4 further includes:

[0144]

[0145] in,

[0146]

[0147]

[0148] Where m = 0, 1, ..., 4, representing the sequence number corresponding to the subcarrier spacing; λ down is the total average downlink arrival rate; α is the number of packets with a finite block length of L bits; p i is the i-th decoding failure rate during the k-th transmission.

[0149] Figure 9 A schematic diagram of the structure of the network side device provided in the embodiment of the present application is shown as follows: Figure 9 As shown, the network side device includes a memory 920, a transceiver 910 and a processor 900; wherein, the processor 900 and the memory 920 can also be arranged physically separately.

[0150] The memory 920 is used to store computer programs; the transceiver 910 is used to send and receive data under the control of the processor 900.

[0151] Specifically, the transceiver 910 is configured to receive and send data under the control of the processor 900 .

[0152] Among them, Figure 9 In the embodiment of the present invention, the bus architecture may include any number of interconnected buses and bridges, specifically linking together various circuits of one or more processors represented by processor 900 and memory represented by memory 920. The bus architecture may also link together various other circuits such as peripheral devices, voltage regulators, and power management circuits, which are well known in the art and therefore will not be further described in this application. The bus interface provides an interface. The transceiver 910 may be a plurality of components, i.e., a transmitter and a receiver, providing a unit for communicating with various other devices over a transmission medium, such as a wireless channel, a wired channel, an optical cable, or the like.

[0153] The processor 900 is responsible for managing the bus architecture and general processing, and the memory 920 can store data used by the processor 900 when performing operations.

[0154] The processor 900 may be a CPU, an ASIC, an FPGA, or a CPLD, and the processor may also adopt a multi-core architecture.

[0155] The processor 900 calls the computer program stored in the memory 920 to execute any of the methods provided in the embodiments of the present application according to the obtained executable instructions, for example:

[0156] Step S1: Establishing a URLLC finite block length model;

[0157] Step S2: Under the URLLC finite block length model, a delay model and a reliability model are established to obtain the total delay and decoding failure probability respectively;

[0158] Step S3: Constraining the total delay and the decoding failure probability respectively to obtain the maximum number of HARQ retransmissions η;

[0159] Step S4: Based on the HARQ maximum retransmission number η, the system bandwidth lower limit w is obtained m , and the system required bandwidth w and the w m For comparison, when w>w m When w≤w m When the w m As the minimum bandwidth of the system, where m = 0, 1, ..., 4, representing the sequence number corresponding to the subcarrier spacing.

[0160] On the other hand, the present invention also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, is implemented to perform the HARQ-based URLLC bandwidth optimization method provided by the above methods, the method comprising:

[0161] Step S1: Establishing a URLLC finite block length model;

[0162] Step S2: Under the URLLC finite block length model, a delay model and a reliability model are established to obtain the total delay and decoding failure probability respectively;

[0163] Step S3: Constraining the total delay and the decoding failure probability respectively to obtain the maximum number of HARQ retransmissions η;

[0164] Step S4: Based on the HARQ maximum retransmission number η, the system bandwidth lower limit w is obtained m , and the system required bandwidth w and the w m For comparison, when w>w m When w≤w m When the w m As the minimum bandwidth of the system, where m = 0, 1, ... 4, representing the sequence number corresponding to the subcarrier spacing.

[0165] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, i.e., they may be located in one location or distributed across multiple network units. Some or all of the modules may be selected based on actual needs to achieve the objectives of the present embodiment. Persons of ordinary skill in the art will be able to understand and implement the present invention without inventive effort.

[0166] Through the description of the above embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus a necessary general hardware platform, or of course, by hardware. Based on this understanding, the essence of the above technical solution or the part that contributes to the existing technology can be embodied in the form of a software product. The computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, a magnetic disk, an optical disk, etc., and includes a number of instructions for enabling a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment or certain parts of the embodiments.

[0167] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A URLLC bandwidth optimization method based on HARQ, characterized in that: include: Step S1: Establishing a URLLC finite block length model; Step S2: Under the URLLC finite block length model, a delay model and a reliability model are established to obtain the total delay and decoding failure probability respectively; Step S3: Constraining the total delay and the decoding failure probability respectively to obtain the maximum number of HARQ retransmissions η; Step S4: Based on the HARQ maximum retransmission number η, the system bandwidth lower limit w is obtained m , and the system required bandwidth w and the w m For comparison, when w>w m When w≤w m When the w m As the minimum bandwidth of the system, where m = 0, 1, ..., 4, representing the sequence number corresponding to the subcarrier spacing.

2. The HARQ-based URLLC bandwidth optimization method according to claim 1, wherein: Step S1 further comprises: Use a channel with a channel factor of r to transmit data packets of finite block length, where r is calculated as follows: Where L is the number of bits contained in a data packet of finite block length; is the SINR of the user; is the probability of decoding failure; is the channel capacity; is the channel dispersion; Q -1 (p) is the inverse function of Q with respect to p.

3. The HARQ-based URLLC bandwidth optimization method according to claim 2, wherein: Step S2 further comprises: The total delay T total The calculation formula is as follows: Among them, T queue is the queuing delay; T trans is the transmission delay; T UE is the packet processing time at the UE; T gNB is the packet processing delay at the gNB; is the number of HARQ retransmissions; t A The waiting time from when a data packet is ready for transmission to the start of the next TTI; When using CC-HARQ transmission, the probability of decoding failure for the kth transmission is The calculation formula is as follows: Where g is a parameter derived from the modulation and coding strategy MCS; is the maximum SINR when the decoding failure probability is 1; is the SINR of the user during the k-th transmission.

4. The HARQ-based URLLC bandwidth optimization method according to claim 3, wherein: When CC-HARQ is used for transmission, the receiver uses maximum ratio joint MRC to decode the kth packet.

5. The HARQ-based URLLC bandwidth optimization method according to claim 3, wherein: When transmitting URLLC services in mini-time slots, the queuing delay T queue The calculation formula is as follows: Among them, T gNB is the processing time of the packet in the gNB; TTI is the basic time unit for dynamic scheduling resources; t A The waiting time after a data packet is ready for transmission until the next TTI begins.

6. The HARQ-based URLLC bandwidth optimization method according to claim 3, wherein: Step S3 further comprises: T total <T d ; Among them, T total is the total delay, T d is the constraint delay; δ is the reliability constraint.

7. The HARQ-based URLLC bandwidth optimization method according to claim 3, wherein: Step S4 further comprises: in, Wherein, m = 0, 1, ... 4, represents the sequence number corresponding to the subcarrier spacing; λ down is the total average downlink arrival rate; α is the number of packets with a finite block length of L bits; p i is the i-th decoding failure rate at the k-th transmission, and E[r] is the expectation of r.

8. A URLLC bandwidth optimization device based on HARQ, characterized in that: include: The first establishment module is used to establish a URLLC finite block length model; The second establishment module is used to establish a delay model and a reliability model under the URLLC finite block length model to obtain a total delay and a decoding failure probability respectively; A constraint module, configured to constrain the total delay and the decoding failure probability respectively to obtain a maximum number of HARQ retransmissions η; The bandwidth optimization module is used to obtain the system bandwidth lower limit w based on the HARQ maximum retransmission number η m , and the system required bandwidth w and the w m For comparison, when w>w m When w≤w m When the w m As the minimum bandwidth of the system, where m = 0, 1, ... 4, representing the sequence number corresponding to the subcarrier spacing.

9. A network-side device comprising a memory, a transceiver, and a processor: memory for storing computer programs; a transceiver, configured to transmit and receive data under the control of the processor; A processor, configured to read the computer program in the memory and execute the HARQ-based URLLC bandwidth optimization method according to any one of claims 1 to 7.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the HARQ-based URLLC bandwidth optimization method according to any one of claims 1 to 7 is implemented.

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