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CN119583019A - Adaptive HARQ optimization method based on channel conditions and LTE-A system - Google Patents

Adaptive HARQ optimization method based on channel conditions and LTE-A system
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Publication number
CN119583019A
CN119583019ACN202411873384.8ACN202411873384ACN119583019ACN 119583019 ACN119583019 ACN 119583019ACN 202411873384 ACN202411873384 ACN 202411873384ACN 119583019 ACN119583019 ACN 119583019A
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harq
client
base station
retransmission
current
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杨鹏举
汪春晖
兰涛
彭心爽
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Hunan Leading Wisdom Telecommunication and Technology Co Ltd
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Hunan Leading Wisdom Telecommunication and Technology Co Ltd
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Abstract

Translated fromChinese

本申请涉及一种基于信道条件的自适应HARQ优化方法及LTE‑A系统,通过在连接过程中,当参数优化事件触发时,基站根据客户端的自身处理能力参数以及当前的信道条件,对HARQ的进程数以及反馈时间进行自适应优化,并将优化后的HARQ参数进行封装发送至对应的客户端,客户端根据的优化后的参数进行配置,在进行数据传输时,基站在下行控制信息中指示HARQ进程的反馈时间,使得客户端确定ACK或NACK反馈的时隙位置,当触发重传机制,基站根据客户端当前的信道条件和当前重传次数,自适应的选择当前次重传的冗余版本并将选择的冗余版本发送至客户端。采用本方法能够减少通信延迟并提升在进行HARQ数据传输的失效性和可靠性。

The present application relates to an adaptive HARQ optimization method based on channel conditions and an LTE‑A system, in which, during the connection process, when a parameter optimization event is triggered, the base station adaptively optimizes the number of HARQ processes and feedback time according to the client's own processing capability parameters and the current channel conditions, and encapsulates the optimized HARQ parameters and sends them to the corresponding client. The client configures according to the optimized parameters. When performing data transmission, the base station indicates the feedback time of the HARQ process in the downlink control information, so that the client determines the time slot position of the ACK or NACK feedback. When the retransmission mechanism is triggered, the base station adaptively selects the redundant version of the current retransmission according to the client's current channel conditions and the current number of retransmissions, and sends the selected redundant version to the client. The use of this method can reduce communication delays and improve the failure and reliability of HARQ data transmission.

Description

Adaptive HARQ optimization method based on channel condition and LTE-A system
Technical Field
The present application relates to the field of wireless communications technologies, and in particular, to a channel condition based adaptive HARQ optimization method and an LTE-a system.
Background
In the current LTE-a system, hybrid automatic repeat request (HARQ) is one of key technologies for realizing reliable data transmission. The HARQ protocol allows for correcting erroneous data packets by retransmitting the request (retransmission request) when errors are detected at the receiving end, thereby improving the reliability of the communication process. This mechanism combines the advantages of Forward Error Correction (FEC) and automatic repeat request (ARQ) to ensure correct reception of data by redundant transmission.
In conventional LTE-a network implementations, the HARQ timing configuration is typically a preset fixed value, according to which the base station (eNodeB) sends scheduling information (scheduling grant) and Downlink Control Information (DCI) to the User Equipment (UE). Such a fixed HARQ timing configuration cannot flexibly cope with changes in network conditions, especially when the processing power and channel conditions of the user equipment change. For example, when the user equipment is in an edge coverage area or in a fast moving state, the channel quality may change rapidly, resulting in that the preset HARQ configuration is no longer adapted to the current network conditions, thereby affecting the overall data transmission efficiency and system performance.
Meanwhile, the fixed number of HARQ processes in the prior art is configured to limit the flexibility of the system. Under high load or high dynamic channel conditions, a fixed number of HARQ processes may lead to a malallocation of resources, further affecting the user experience and the transmission stability of the network. These limitations indicate that the conventional HARQ timing and process configuration strategies need to be further optimized to improve the adaptation and performance of the LTE-a system in diverse environments.
Disclosure of Invention
In view of the foregoing, it is desirable to provide an adaptive HARQ optimization method based on channel conditions and an LTE-a system that can reduce communication delay and improve the failure and reliability of data transmission.
An adaptive HARQ optimization method based on channel conditions, the method implemented between a client and a base station, the method comprising:
In the process of establishing connection between the client and the base station, when an HARQ parameter optimization event is triggered, the base station adaptively optimizes the number of HARQ processes and the feedback time according to the self HARQ processing capacity parameter of the client and the current channel condition, encapsulates and sends the optimized HARQ parameter to the corresponding client, and the client configures according to the optimized HARQ parameter;
When data transmission is carried out between the client and the base station, the base station indicates the feedback time of the HARQ process in the downlink control information, so that the client determines the time slot position of ACK or NACK feedback;
And when the HARQ feedback of the client is NACK or feedback is not detected, triggering a retransmission mechanism, and adaptively selecting a redundancy version of current retransmission by the base station according to the current channel condition of the client and the current retransmission times, and sending the selected redundancy version to the client until the client feeds back ACK.
In one embodiment, the HARQ parameter optimization event trigger includes a periodic trigger and an event trigger, where the event trigger includes:
When the channel quality index change or the channel condition change of the client exceeds a preset threshold value;
When the HARQ retransmission failure rate of the client exceeds a preset threshold value;
and when the position change of the client exceeds a preset threshold value.
In one embodiment, when estimating the current signal conditions:
In each subframe, the client performs channel estimation on CRS or CSI-RS on a downlink physical signal to obtain a current channel quality index, and feeds back the channel quality index to the base station;
And the base station calculates according to the channel quality index and the reference signal transmitting power and the antenna configuration of the downlink channel to obtain the current channel condition of the client, wherein the channel condition comprises the downlink channel capacity and the SINR grade of the client.
In one embodiment, the base station adaptively optimizes the number of HARQ processes and the feedback time according to the self HARQ processing capability parameter of the client and the current channel condition, including:
Determining the maximum transmission times of HARQ according to the SINR grade in the current channel condition of the client and the self HARQ processing capacity parameter;
determining the maximum process number of the uplink HARQ according to the soft buffer size in the self HARQ processing capacity parameter of the client;
And determining the HARQ feedback time according to the maximum time delay in the self HARQ processing capacity parameter of the client.
In one embodiment, when data is transmitted between the client and the base station, the client performs ACK/NACK feedback through a physical uplink control channel, and uses a physical uplink control channel resource indication to map to a physical resource block for transmission, where the physical uplink control channel resource indication uses a dynamic and semi-static dual-mode mapping mechanism.
In one embodiment, the adaptively selecting, by the base station, the redundancy version of the current retransmission according to the current channel condition and the current retransmission number of the client includes:
if the current SINR level is reduced, the base station selects RV1 version or RV2 version;
and if the current SINR level is improved, the base station selects RV0 version.
In one embodiment, the selection of redundancy versions also follows the following rules:
if the retransmission is the first retransmission, selecting RV version sequence of the redundancy versions as RV0 version, RV2 version, RV3 version and RV1;
for multiple retransmissions, the redundancy version is selected to cycle between RV1 version, RV2 version, RV3 version.
In one embodiment, when the base station and the client perform data retransmission, a continuous retransmission and adaptive HARQ collision avoidance mechanism is adopted.
The application also provides an LTE-A system, which comprises a base station and a plurality of clients, wherein the self-adaptive HARQ optimization method based on the channel condition is implemented between the base station and each client.
According to the self-adaptive HARQ optimization method based on the channel condition and the LTE-A system, when the HARQ parameter optimization event is triggered in the process of establishing connection between the client and the base station, the base station adaptively optimizes the number of HARQ processes and the feedback time according to the self HARQ processing capacity parameter of the client and the current channel condition, packages and sends the optimized HARQ parameter to the corresponding client, the client configures according to the optimized HARQ parameter, when data transmission is carried out between the client and the base station, the base station indicates the feedback time of the HARQ process in the downlink control information, so that the client determines the time slot position of ACK or NACK feedback, when the HARQ feedback of the client is NACK or feedback is not detected, a retransmission mechanism is triggered, the base station adaptively selects the redundancy version of current retransmission according to the current channel condition and the current retransmission times of the client, and sends the selected redundancy version to the client until the client feeds back the ACK. By adopting the method, communication delay can be reduced, and the invalidity and reliability of HARQ data transmission can be improved.
Drawings
Fig. 1 is a flow chart of an adaptive HARQ optimization method based on channel conditions in one embodiment
Fig. 2 is a schematic flow diagram of HARQ parameter optimization in one embodiment;
FIG. 3 is a schematic diagram of a connection established via UE Capability Information messages in one embodiment;
Fig. 4is a schematic diagram of HARQ parameter configuration in one embodiment;
fig. 5 is a schematic diagram of determining transmission parameters and feedback time by a UE according to DCI in one embodiment;
fig. 6 is a schematic diagram of data transmission after HARQ parameter optimization in one embodiment;
FIG. 7 is a schematic diagram of a data transmission process in one embodiment;
FIG. 8 is a schematic diagram of a data retransmission process in one embodiment;
fig. 9 is an internal structural diagram of a computer device in one embodiment.
Detailed Description
The present application will be described in further detail with reference to the drawings and examples, in order to make the objects, technical solutions and advantages of the present application more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the application.
In the LTE-a network architecture, the HARQ protocol plays a critical role as one of core mechanisms for ensuring the reliability of data transmission, and the conventional HARQ timing fixed configuration may not be fully adapted to dynamic changes of the network environment, such as fluctuation of channel quality and difference of processing capability of terminal devices, which directly affects the instantaneity and reliability of data transmission.
In view of the above technical problems, as shown in fig. 1, the present application provides an adaptive HARQ optimization method based on channel conditions, where the method is implemented between a client and a base station, and specifically includes the following steps:
Step S100, when the HARQ parameter optimization event is triggered in the process of establishing connection between the client and the base station, the base station adaptively optimizes the number of HARQ processes and the feedback time according to the self HARQ processing capacity parameter of the client and the current channel condition, encapsulates and sends the optimized HARQ parameter to the corresponding client, and the client configures according to the optimized HARQ parameter.
Step S110, when data transmission is carried out between the client and the base station, the base station indicates the feedback time of the HARQ process in the downlink control information, so that the client determines the time slot position of ACK or NACK feedback.
In step S120, when the HARQ feedback of the client is NACK or feedback is not detected, a retransmission mechanism is triggered, and the base station adaptively selects a redundancy version of current retransmission according to the current channel condition and the current retransmission times of the client, and sends the selected redundancy version to the client until the client feeds back the ACK.
The method provided in the application aims to solve the defect that the hybrid automatic repeat request (HARQ) timing fixed configuration in the existing LTE-A system is presented in front of dynamic network conditions and device performance differences. In particular, how to enable the HARQ timing to be dynamically adjusted according to real-time network conditions and processing capabilities of the user equipment, so as to reduce communication delay and improve timeliness and reliability of data transmission. The configuration that focuses on optimizing the number of HARQ processes is aimed at enabling the base station to flexibly allocate resources according to the current network load and channel conditions. The optimization can improve the resource utilization rate of the system and reduce transmission conflict and delay caused by fixed resource allocation.
The present method provides a mechanism to cope with situations where the channel conditions of the user equipment may change rapidly in the edge coverage or high speed mobile state. This includes enhancing the overall reliability of the communication by dynamically adjusting HARQ feedback timing and employing adaptive retransmission strategies to ensure reduced data transmission error rates under extreme network conditions.
Through the improvements, the method greatly improves the adaptability and performance of the LTE-A system in complex and changeable network environments, and meets the increasing demands of modern wireless communication on high speed and high reliability.
In this embodiment, the method specifically optimizes the HARQ parameters in three phases in the existing HARQ transmission, including a HARQ parameter configuration phase, a data transmission phase, and a data retransmission node.
In step S100, during RRC (Radio Resource Control (radio resource control) protocol) connection establishment, the UE (user equipment, i.e., client) encapsulates its HARQ processing Capability parameter in featureGroupIndicators field in the UE-EUTRA-Capability IE through UE Capability Information message (UL-DCCH MESSAGE), and sends the HARQ processing Capability parameter to the base station.
In this embodiment, the HARQ processing capability parameters of the client itself include processing delay capability, soft buffer size, and parallel processing capability.
After receiving UE Capability Information (user equipment capability information) messages, the base station stores the analyzed UE HARQ capability parameters in the uplinkPowerControl and antennaInfo subfields of the PhysicalConfigDedicated field for subsequent adaptive configuration through dedicatedRadioResourceConfig IE of the RRC Connection Reconfiguration message (DL-DCCH MESSAGE).
Further, when estimating the signal condition of the current client, the current channel condition of the client is obtained by performing channel estimation on CRS or CSI-RS on the downlink physical signal in each subframe by the first client, obtaining a current channel quality index, feeding back the channel quality index to the base station, and then performing calculation by the base station according to the channel quality index in combination with the reference signal transmitting power and antenna configuration of the downlink channel, wherein the channel condition comprises the downlink channel capacity and SINR grade of the client.
Specifically, in each subframe, the UE performs channel estimation on CRS or CSI-RS on a downlink physical channel (such as PDCCH and PDSCH), calculates a channel quality indicator (such as SINR and CQI), and feeds back parameters such as quantizedCQI and subbandCQI to the base station through a Format 2/2a/2b of a Physical Uplink Control Channel (PUCCH) or a CSI reporting mode of a Physical Uplink Shared Channel (PUSCH).
Specifically, after receiving CSI feedback of the UE, the base station extracts a CQI value, and calculates the current downlink channel capacity and SINR level of the UE by combining the reference signal transmission power (configured by pdsch-ConfigDedicated IE) and the antenna configuration (configured by antennaInfo IE) of the downlink channel, for optimization of the adaptive HARQ parameters. The prior art may be used to calculate the current downlink channel capacity and SINR level of the UE, and will not be described herein.
In this embodiment, the HARQ parameter optimization event trigger includes a periodic trigger and an event trigger, where the event trigger includes when a channel quality index change or a channel condition change of the client exceeds a preset threshold, or when a HARQ retransmission failure rate of the client exceeds a preset threshold, or when a location change of the client exceeds a preset threshold.
Specifically, the periodic triggering refers to parameter evaluation on parameters every fixed preset period, and whether there is event triggering or not.
Further, when a certain parameter optimizing event is triggered, the base station adaptively optimizes the number of HARQ processes and the feedback time according to the self HARQ processing capacity parameter of the client and the current channel condition, wherein the self-adaptive optimization comprises the steps of determining the maximum transmission times of the HARQ according to the SINR grade in the current channel condition of the client and the self HARQ processing capacity parameter, determining the maximum number of uplink HARQ processes according to the soft buffer size in the self HARQ processing capacity parameter of the client, and determining the HARQ feedback time according to the maximum time delay in the self HARQ processing capacity parameter of the client.
Specifically, when the maximum number of transmissions of HARQ is optimized:
if (SINR > sinr_threshold_high ≡ue processing capability level = =high)
{
MaxHARQ-tx=3;// channel conditions are good and UE processing power is strong, a smaller number of retransmissions is used
Else if (SINR < sinr_threshold_low|ue processing capability level= LOW) {
Reliability is ensured by increasing the retransmission times when maxHARQ-tx=6;// channel conditions are poor or UE processing capability is weak
} else {
MaxHARQ-tx=4;// default value in general
}
Specifically, when the maximum number of processes of the uplink HARQ is optimized:
if (UE soft BUFFER size > = high_buffer_threshold += HIGH & UE parallel processing capability += HIGH)
{
if (CQI>= CQI_THRESHOLD_HIGH) {
NumberOfConfUlSCHProcess = 8;// maximum number of processes used when the resources are sufficient and the channel is good
} else {
NumberOfConfUlSCHProcess = 6;// channel typically uses medium number of processes
}
} else {
NumberOfConfUlSCHProcess = 4;// less number of processes is used when UE capability is limited
}
Specifically, when the HARQ feedback time is optimized:
if (UE processing delay < = low_latency &sinr > sinr_threshold_high)
{
Harq-FeedbackTiming = 4;// processing is fast and uses shorter feedback time when channel is good
Else if (UE processing delay > = high_latency|sinr < sinr_threshold_low) {
Harq-FeedbackTiming = 8;// increasing feedback time when slow or channel difference is processed
} else {
Harq-FeedbackTiming =6;// default values for general case
}
In the embodiment, when the HARQ parameters are optimized, a protection mechanism is further arranged, wherein the protection mechanism comprises setting the maximum step length of parameter adjustment and maintaining the upper and lower limit values of the parameters so as to ensure that the minimum interval of parameter updating is set within a reasonable range to avoid frequent adjustment, and returning to a conservative configuration when continuous multiple transmission failures occur.
In this embodiment, the base station encapsulates the optimized HARQ parameters in a physical configdedicated subfield of radioResourceConfigDedicated IE through RRC Connection Reconfiguration message, and notifies the UE to update the configuration, where the ul-SCH-Config field contains maxHARQ-Tx and numberOfConfUlSCHProcess parameters, and the HARQ-FeedbackConfig field contains HARQ-FeedbackTiming parameters of each HARQ process.
Further, the base station indicates, in the DCI format of each Uplink Grant (Uplink Grant), the feedback time of the HARQ process corresponding to the current Grant through the "HARQ Feedback Timing Indicator" field, and covers RRC configuration. After the UE decodes the DCI, the value of the field is extracted and used for determining the time slot position of the HARQ ACK/NACK feedback.
As shown in fig. 2, a schematic diagram of the HARQ parameter optimization process is shown.
An example is also provided for the HARQ parameter optimization procedure described above for illustration.
The UE reports its HARQ processing capability through UE Capability Information message during RRC connection setup, as shown in fig. 3. And then, the CSI feedback reported by the UE in the subframe n is expressed as:
The base station estimates the downlink channel capacity and SINR at 150mbps,22db, respectively.
The base station then configures HARQ parameters in RRC Connection Reconfiguration messages, as shown in fig. 4.
Then, in subframe n+4, the base station transmits UL Grant (DCI Format 0), expressed as:
the UE then determines transmission parameters and feedback time from the DCI as shown in fig. 5.
Finally, the UE performs uplink data transmission in subframe n+8, and sends ACK/NACK feedback in subframe n+12, as shown in fig. 6.
In step S110, data transmission and HARQ feedback sister are short-lived between the base station and the client. And the base station allocates Uplink transmission resources for each UE according to the optimized HARQ parameters in the step S100, and generates corresponding Uplink Grant (UL Grant). The key parameters included in the UL Grant include HARQ Process Number, i.e., an HARQ process number corresponding to the indication of the current transmission. New Data Indicator (NDI), i.e. whether new data is transmitted, redundancy Version (RV), i.e. indicating redundancy version, for HARQ combining and decoding, TBS (Transport Block Size), i.e. indicating transport block size.
Further, the base station encapsulates UL Grant in Downlink Control Information (DCI) and transmits the UL Grant to the UE through a Physical Downlink Control Channel (PDCCH). The DCI Format includes DCI Format 0 for scheduling of uplink shared channel (UL-SCH), and DCI Format 4 for scheduling of uplink multi-antenna transmission.
In this embodiment, the "HARQ Feedback Timing Indicator" field of the base station in the DCI indicates the feedback time of the HARQ process corresponding to the current transmission, and is used for determining the time slot position of the ACK/NACK feedback by the UE, so that, on one hand, the UE can timely feedback the ACK/NACK, the base station adjusts the transmission policy accordingly, and improves the reliability of data transmission, on the other hand, the base station is helpful for precisely allocating resources, flexibly scheduling, improving the utilization efficiency of system resources, reducing the power consumption of the UE, and enhancing the compatibility and expansibility of the system, adapting to different scenes and technical evolution, and providing a powerful support for efficient and stable operation of the wireless communication system.
And at the client, the UE monitors the PDCCH, decodes DCI matched with the self C-RNTI, and extracts the UL Grant information. The UE determines the HARQ process used by the current transmission according to HARQ Process Number in the UL Grant, judges whether the HARQ process is new data transmission according to NDI, if the NDI is 1, the UE empties the buffer of the HARQ process, if the NDI is 0, the UE indicates data retransmission, and the UE reserves the buffer of the HARQ process for soft combining. And the UE decodes the received data according to RV and TBS in the UL Grant, if the received data is transmitted for the first time (RV 0), the UE directly decodes the received data, and if the received data is retransmitted (RV 1-RV 3), the UE carries out soft combination with the data in the buffer memory and then decodes the received data.
When the client transmits the HARQ feedback, the slot position of the ACK/NACK feedback is determined according to the HARQ feedback time (HARQ-FeedbackTiming) configured in step S100 and "HARQ Feedback Timing Indicator" in the DCI. And the UE transmits HARQ ACK/NACK feedback through Format 1a/1b of a Physical Uplink Control Channel (PUCCH) in a designated time slot, wherein if the data decoding is successful, the UE transmits ACK, and if the data decoding is failed, the UE transmits NACK.
In this embodiment, the client performs ACK/NACK feedback through the physical uplink control channel, and uses mapping of the physical uplink control channel resource indication to the physical resource block for transmission, where the physical uplink control channel resource indication uses a dynamic and semi-static dual-mode mapping mechanism. The resource allocation method and the system not only can flexibly allocate resources according to real-time conditions through dynamic mapping to cope with sudden and changing scenes, improve the flexibility of resource allocation and the adaptability of the system, but also can reduce signaling overhead and provide stable resource allocation for periodic services by means of semi-static mapping, and can optimize resource utilization, improve spectrum efficiency and reduce feedback delay, so that the system can better balance the flexibility and stability of resource allocation under various service scenes, and improve the overall communication performance.
As shown in fig. 7, a specific flowchart in step S110 is shown.
In step S110, if the base station detects that the HARQ feedback of the UE is NACK or does not detect feedback, the retransmission mechanism is triggered, i.e. the step in step S120 is implemented. The base station firstly searches the state information of the HARQ process corresponding to the UE in the buffer memory according to the RNTI and the HARQ process number of the UE, wherein the state information comprises the current retransmission times, RV used in the last transmission, a buffered data block and the like.
In this embodiment, the base station adaptively selects the redundancy version of the current retransmission according to the current channel condition and the current retransmission times of the client, wherein the base station selects the RV1 version or the RV2 version if the current SINR level is reduced, and selects the RV0 version if the current SINR level is increased.
Specifically, the base station adaptively selects a Redundancy Version (RV) for retransmission according to the channel condition (CQI level) estimated in step S100 and the current number of retransmissions. When the channel condition is deteriorated (CQI level is lowered), the base station tends to select a more reliable RV scheme (e.g., RV1, RV 2) to improve the retransmission success rate, and when the channel condition is improved (CQI level is raised), the base station tends to select a RV scheme (e.g., RV 0) with a higher coding rate to improve the data throughput. Meanwhile, RV is selected according to the following rule that for the first retransmission, RV sequence is RV 0- > RV 2- > RV 3- > RV1, and for multiple retransmissions, RV circulates among RV1, RV2 and RV3, and RV0 is not used any more. The adaptive RV selection strategy can ensure the reliability of retransmission and maximize the data throughput.
Further, after determining the RV used for retransmission, the base station generates a retransmission UL Grant, and fills key parameters including HARQ Process Number, which is the same as the initial transmission, indicating the HARQ process number corresponding to the retransmission, new Data Indicator (NDI), which is set to 0, indicating the current transmission as retransmission, redundancy Version (RV), which is filling in the self-adaptively selected RV value, TBS (Transport Block Size), which is the same as the initial transmission.
In this embodiment, the selection of redundancy versions also follows the rule that if a scene is retransmitted for the first time, the RV version sequence of the redundancy versions is RV0 version, RV2 version, RV3 version and RV1 version, and if a scene is retransmitted for multiple times, the redundancy versions are selected to cycle between RV1 version, RV2 version and RV3 version. This differentiated policy can better balance transmission efficiency and reliability.
The redundancy version selection mode provided by the method effectively realizes dynamic balance between two targets of guaranteeing retransmission reliability and maximizing data throughput.
Next, the base station encapsulates the retransmission UL Grant in DCI and transmits the same to the UE through PDCCH. After receiving the retransmission UL Grant, the UE judges retransmission according to the HARQ process number and the NDI, reads data from the corresponding HARQ buffer, and decodes and soft combines according to RV. Soft combining means that the UE combines the data received by retransmission with the data which has not been successfully decoded before, so as to improve the decoding success rate. The maximum soft buffer capability supported by the UE may be configured by maxSoftBufferSize parameters in the RRC configured ul-SCH-Config IE.
The whole retransmission process is repeated until one of the following two conditions appears, the first condition is that the UE successfully decodes the data and feeds back the ACK, the base station considers that the transmission of the HARQ process is completed, the resources can be released, the second condition is that the maximum retransmission times (defined by the maxHARQ-Tx parameters configured by RRC) are reached, the base station considers that the transmission of the HARQ process is failed, and the RLC layer processing is reported.
In the retransmission process, the base station dynamically adjusts MCS (Modulation and Coding Scheme) parameters, TBS parameters and the like according to the change of the channel condition so as to further optimize the retransmission performance. For example, when the channel condition is improved, the MCS level and TBS size are properly increased, and the retransmission success rate is ensured, and at the same time, the data throughput is improved, and when the channel condition is deteriorated, the MCS level and TBS size are properly decreased, and the reliability of the retransmission is ensured.
In order to reduce retransmission delay and improve resource utilization efficiency, in the present embodiment, a continuous retransmission and adaptive HARQ collision avoidance mechanism is used when a base station and a client perform data retransmission.
Wherein the continuous retransmission (Continuous Transmission) allows the base station to allocate retransmission resources immediately after detecting the NACK, without waiting for the next scheduling period, reducing retransmission latency. The self-adaptive HARQ conflict avoidance (ADAPTIVE HARQ Collision Avoidance) mechanism avoids the conflict of retransmission resources of different UE by dynamically adjusting the HARQ ACK/NACK feedback time and the retransmission resource allocation time, and improves the resource utilization efficiency.
As shown in fig. 8, a specific flow chart of the data retransmission process in step S120 is shown.
In the adaptive HARQ optimization method based on the channel condition, the uplink HARQ retransmission performance of the LTE-A system is optimized from multiple dimensions, including adaptive RV selection, dynamic MCS and TBS adjustment, continuous retransmission, adaptive HARQ conflict avoidance and the like, the retransmission success rate can be remarkably improved, the retransmission time delay can be reduced, the data throughput can be improved, meanwhile, the retransmission reliability and the resource utilization efficiency can be considered, and the LTE-A system can be better adapted to the diversified service requirements of the 5G heterogeneous network and the complex and changeable transmission environment.
Specifically, in the adaptive HARQ parameter configuration, the UE reports the HARQ processing Capability to the base station through the UE-EUTRA-Capability IE in the UE Capability Information message, the base station stores the UE HARQ Capability parameter for subsequent adaptive configuration through dedicatedRadioResourceConfig IE in the RRC Connection Reconfiguration message, the base station estimates the current channel capacity and SINR level according to CSI feedback (such as CQI, PMI, etc.) of the UE, dynamically optimizes the HARQ parameter configuration in combination with the HARQ Capability of the UE, and the base station notifies the UE of the adaptive HARQ parameters (such as maximum transmission times, process number, feedback time, etc.) through the RRC message and DCI field.
Specifically, in the data transmission and HARQ feedback process, the base station transmits an uplink Grant (UL Grant) to the UE, indicates transmission parameters, and the UE transmits HARQ ACK/NACK feedback in a designated time slot according to the Grant transmission data. The base station indicates key parameters such as HARQ process number, new Data (NDI), redundancy Version (RV), transmission Block Size (TBS) and the like of current transmission in the UL Grant, the base station indicates the ACK/NACK feedback time slot position of the UE through a 'HARQ Feedback Timing Indicator' field in DCI, the UE judges whether to empty soft buffer according to the NDI in the UL Grant, decodes and soft combines the received data according to the RV and the TBS, and the UE sends HARQ ACK/NACK feedback in a designated time slot through Format 1a/1b of a PUCCH and maps the dynamic or semi-static PUCCH Resource Indication (PRI) to a Physical Resource Block (PRB) for transmission.
Specifically, when retransmitting data, the base station adaptively selects a Redundancy Version (RV) of retransmission according to channel conditions and retransmission times, dynamically adjusts MCS and TBS, and introduces a continuous retransmission and adaptive HARQ collision avoidance mechanism to improve retransmission efficiency. And the base station adaptively selects RV according to CQI feedback and retransmission times of the UE. When the channel condition is deteriorated, a more reliable RV scheme is selected, when the channel condition is improved, a RV scheme with higher coding rate is selected, and the base station dynamically adjusts the retransmitted MCS and TBS. When the channel condition is improved, the MCS level and TBS size are appropriately increased, and when the channel condition is deteriorated, the MCS level and TBS size are appropriately decreased. And a continuous retransmission mechanism, which allows the base station to immediately allocate retransmission resources after detecting NACK, thereby reducing retransmission waiting time. And the self-adaptive HARQ conflict avoidance mechanism is used for dynamically adjusting the HARQ ACK/NACK feedback time and the retransmission resource allocation time and avoiding retransmission resource conflicts of different UEs.
Further, compared with the prior art, the method has the technical advantages that:
The prior art generally configures HARQ parameters based on only a single factor in channel conditions or UE capabilities, lacking comprehensive consideration. On the basis of reporting detailed HARQ processing capacity by UE, the method combines factors such as channel capacity, SINR grade and the like estimated by a base station in real time to dynamically optimize HARQ parameters from multiple dimensions, including maximum transmission times, process number, feedback time and the like, so that the HARQ configuration is more refined and self-adaptive, and the HARQ strategy can be flexibly adjusted according to the actual conditions and network environments of different UEs, thereby improving the transmission reliability and efficiency.
In addition, in terms of data transmission and HARQ feedback, the prior art often adopts a fixed time slot configuration and resource mapping mode, and is difficult to adapt to actual transmission requirements and network conditions. The method realizes more flexible and accurate transmission control by dynamically indicating key parameters such as HARQ process numbers, NDI, RV, TBS and the like in the UL Grant and indicating the ACK/NACK feedback time slot position in the DCI. Meanwhile, a dynamic PUCCH Resource Indication (PRI) mechanism is introduced, so that the allocation and mapping of HARQ feedback resources can be optimized according to actual conditions, and resource waste and conflict are reduced. These improvements effectively improve the efficiency and reliability of data transmission.
In terms of retransmission mechanisms, the prior art generally employs fixed RV selections and MCS/TBS configurations, lacking the ability to dynamically optimize according to actual transmission conditions. The method introduces a self-adaptive RV selection strategy, dynamically selects an optimal RV scheme according to the channel condition and retransmission times, and maximizes throughput while guaranteeing the reliability of retransmission. In addition, the retransmission performance is further optimized by dynamically adjusting the MCS and TBS. Meanwhile, the invention also introduces a continuous retransmission and self-adaptive HARQ conflict avoidance mechanism, which can reduce retransmission waiting time and resource conflict and obviously improve retransmission efficiency. The improvement ensures that the retransmission mechanism is more intelligent and efficient, and can be adaptively optimized according to the actual transmission condition, thereby greatly improving the system performance.
Finally, compared with the prior art, the method is mainly optimized for the traditional LTE system, the characteristics and the requirements of the 5G heterogeneous network are fully considered, and the HARQ mechanism can be better adapted to the diversified service requirements of the 5G network, such as high speed, low time delay, high reliability and the like, and the complex and changeable transmission environment by introducing multidimensional self-adaptive HARQ parameter configuration, flexible and efficient data transmission and feedback mechanisms, intelligent self-adaptive retransmission strategies and the like. The method provides a complete set of HARQ optimization schemes from end to end, and can remarkably improve the transmission performance and user experience of the 5G heterogeneous network.
In summary, compared with the prior art, the method is comprehensively innovated and optimized in the aspects of HARQ parameter configuration, data transmission, feedback, retransmission mechanism and the like, greatly improves the self-adaptability, flexibility, reliability and efficiency of transmission, better meets the diversified requirements of the 5G heterogeneous network, and has obvious technical advantages and application value.
It should be understood that, although the steps in the flowchart of fig. 1 are shown in sequence as indicated by the arrows, the steps are not necessarily performed in sequence as indicated by the arrows. The steps are not strictly limited to the order of execution unless explicitly recited herein, and the steps may be executed in other orders. Moreover, at least some of the steps in fig. 1 may include multiple sub-steps or stages that are not necessarily performed at the same time, but may be performed at different times, nor do the order in which the sub-steps or stages are performed necessarily performed in sequence, but may be performed alternately or alternately with at least a portion of other steps or sub-steps of other steps.
In one embodiment, there is also provided an LTE-a system including a base station and a plurality of clients, and the above-described adaptive HARQ optimization method based on channel conditions is implemented between the base station and each of the clients.
For specific limitations of the LTE-a system, reference may be made to the above limitation of the adaptive HARQ optimization method based on channel conditions, and no further description is given here. The respective modules in the above-described LTE-a system may be implemented in whole or in part by software, hardware, and combinations thereof. The above modules may be embedded in hardware or may be independent of a processor in the computer device, or may be stored in software in a memory in the computer device, so that the processor may call and execute operations corresponding to the above modules.
In one embodiment, a computer device is provided, which may be a terminal, and the internal structure thereof may be as shown in fig. 9. The computer device includes a processor, a memory, a network interface, a display screen, and an input device connected by a system bus. Wherein the processor of the computer device is configured to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of the operating system and computer programs in the non-volatile storage media. The network interface of the computer device is used for communicating with an external terminal through a network connection. The computer program, when executed by a processor, implements a method of adaptive HARQ optimization based on channel conditions. The display screen of the computer equipment can be a liquid crystal display screen or an electronic ink display screen, and the input device of the computer equipment can be a touch layer covered on the display screen, can also be keys, a track ball or a touch pad arranged on the shell of the computer equipment, and can also be an external keyboard, a touch pad or a mouse and the like.
It will be appreciated by persons skilled in the art that the architecture shown in fig. 9 is merely a block diagram of some of the architecture relevant to the present inventive arrangements and is not limiting as to the computer device to which the present inventive arrangements are applicable, and that a particular computer device may include more or fewer components than shown, or may combine some of the components, or have a different arrangement of components.
In one embodiment, a computer device is provided comprising a memory and a processor, the memory having stored therein a computer program, the processor when executing the computer program performing the steps of:
In the process of establishing connection between the client and the base station, when an HARQ parameter optimization event is triggered, the base station adaptively optimizes the number of HARQ processes and the feedback time according to the self HARQ processing capacity parameter of the client and the current channel condition, encapsulates and sends the optimized HARQ parameter to the corresponding client, and the client configures according to the optimized HARQ parameter;
When data transmission is carried out between the client and the base station, the base station indicates the feedback time of the HARQ process in the downlink control information, so that the client determines the time slot position of ACK or NACK feedback;
And when the HARQ feedback of the client is NACK or feedback is not detected, triggering a retransmission mechanism, and adaptively selecting a redundancy version of current retransmission by the base station according to the current channel condition of the client and the current retransmission times, and sending the selected redundancy version to the client until the client feeds back ACK.
In one embodiment, a computer readable storage medium is provided having a computer program stored thereon, which when executed by a processor, performs the steps of:
In the process of establishing connection between the client and the base station, when an HARQ parameter optimization event is triggered, the base station adaptively optimizes the number of HARQ processes and the feedback time according to the self HARQ processing capacity parameter of the client and the current channel condition, encapsulates and sends the optimized HARQ parameter to the corresponding client, and the client configures according to the optimized HARQ parameter;
When data transmission is carried out between the client and the base station, the base station indicates the feedback time of the HARQ process in the downlink control information, so that the client determines the time slot position of ACK or NACK feedback;
And when the HARQ feedback of the client is NACK or feedback is not detected, triggering a retransmission mechanism, and adaptively selecting a redundancy version of current retransmission by the base station according to the current channel condition of the client and the current retransmission times, and sending the selected redundancy version to the client until the client feeds back ACK.
Those skilled in the art will appreciate that implementing all or part of the above described methods may be accomplished by way of a computer program stored on a non-transitory computer readable storage medium, which when executed, may comprise the steps of the embodiments of the methods described above. Any reference to memory, storage, database, or other medium used in embodiments provided herein may include non-volatile and/or volatile memory. The nonvolatile memory can include Read Only Memory (ROM), programmable ROM (PROM), electrically Programmable ROM (EPROM), electrically Erasable Programmable ROM (EEPROM), or flash memory. Volatile memory can include Random Access Memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in a variety of forms such as Static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double Data Rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link (SYNCHLINK) DRAM (SLDRAM), memory bus (Rambus) direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM), among others.
The technical features of the above embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.
The above examples illustrate only a few embodiments of the application, which are described in detail and are not to be construed as limiting the scope of the application. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the application, which are all within the scope of the application. Accordingly, the scope of protection of the present application is to be determined by the appended claims.

Claims (9)

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CN107733578A (en)*2016-08-122018-02-23电信科学技术研究院A kind of method and device fed back to downlink data
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