CN1946015A - Method for determining re-transmitting data block size and base station, data transmission method - Google Patents

Abstract

The invention discloses a method for determining the size of a retransmission data block, a base station, and a data transmission method. During the data transmission process, when the receiver feeds back NACK to request retransmission, the resource quantity allocation unit of the base station allocates system resources required for retransmission The number of units is less than the number of system resource units allocated for the initial transmission of the system, the scheduler schedules system resource units for the retransmission process according to the allocation result, and the retransmission data block size setting unit of the base station determines the retransmission data block size according to the scheduling result; The transmitted data block. Since the present invention first determines the system resources during retransmission, and then determines the amount of retransmitted data according to the transmission capacity of the determined system resources, it can ensure that the size of the retransmitted data block completely matches the amount of retransmitted system resources, avoiding the transmission of system resources. It reduces the waste of capacity, reduces the signaling information that needs to be transmitted, and reduces the complexity of system resource scheduling.

Description

A method for determining the size of a retransmission data block, a base station, and a data transmission method

technical field

The present invention relates to communication technology, in particular to Hybrid Automatic Repeat request (HARQ, Hybrid Automatic Repeat request) technology in the communication field.

Background technique

With the increasing demand for high-speed multimedia data services, wireless communication requires wider frequency band resources to meet the transmission of broadband data services, and the limited utilization of frequency bands has become a bottleneck restricting the development of broadband data services. How to maximize the data transmission rate, that is, how to maximize the frequency band utilization efficiency has become one of the key links of the third generation mobile communication and future communication systems. At the same time, the demand for high-speed multimedia services has prompted the wireless mobile communication system to adopt new technologies to increase the transmission rate and system capacity.

At present, in the communication system, technologies such as system resource scheduling, Adaptive Modulation and Coding (AMC, Adaptive Modulation and Coding), and hybrid automatic repeat request (HARQ) can be used to improve system performance.

System resource scheduling refers to the unified processing of physical resources available in the system, selecting user terminals (UE, User Equipment) and assigning them different physical resources, where the physical resources may be time resources, frequency resources, code resources, etc. For example, system scheduling can allocate a certain physical resource to a user terminal with a "better" channel condition on the physical resource based on channel quality indication information (CQI, Channel Quality Indication) fed back by the user terminal.

AMC and HARQ technologies are developed based on the characteristics of wireless communication. The actual wireless communication channel has two characteristics: time-varying characteristics and fading characteristics. Time-varying characteristics are caused by relative motion between user terminals, reflectors, scatterers, or simply due to slight changes in the transmission medium. Therefore, the channel capacity of the wireless channel is also a time-varying random variable. To maximize the use of the channel capacity, one of the methods is to make the transmission rate also a quantity that varies with the channel capacity. In this context, adaptive technology is increasingly being applied to the evolution transmission scheme of the third generation mobile communication system and future systems. For a wireless communication system, its channel conditions, business types, and business distribution will change with time and space. The use of adaptive technology can make the system more flexible and intelligent to make adaptive adjustments according to these changes, so as to improve Improve transmission quality and increase system capacity. In general, such adaptive strategies are classified into two categories: adaptive radio resource management and adaptive radio transmission technology.

In order to meet the high-performance requirements of wireless mobile communication systems, the available adaptive transmission technologies mainly focus on the physical layer (PHY) and media access layer (MAC). At the physical layer, there are traditional diversity technology and space diversity technology using multiple antennas. At the media access layer, it mainly includes link adaptation technology (AMC) and link retransmission technology (ARQ, Automatic Repeat request) .

The basic principle of AMC technology is to change the format of modulation and coding to make it adapt to the channel conditions within the limits of the system, and the channel conditions can be estimated by sending feedback, that is, to determine the capacity of the current channel according to the channel conditions, and according to the capacity Determine the appropriate coding and modulation methods, etc., in order to maximize the transmission of information and achieve a relatively high rate. AMC technology mainly includes the combination of RCPT (Rate CompatiblePuncturing Turbo codes) and high-order modulation (MSPK & M-QAM), hybrid automatic repeat request HARQ (Hybrid Automatic Repeat request) and multiple-input multiple-output antenna (MIMO, Multiple-Input Multiple -Out-put) technology, etc.

In the AMC system, generally in the case of good channel conditions, less redundant coding and high-order modulation are used to increase the data rate; while in the case of poor channel conditions, correction is used adaptively. The combination of error-resistant coding and low-order modulation improves anti-interference ability.

ARQ technology is also a link adaptive technology, which refers to the transmission mechanism that ensures the reliability of transmission through retransmission, and requires retransmission of data packets when the previous transmission attempt fails. Communication links with ARQ technology are generally closed-loop links, and there is a feedback response signal ACK (ACKnowledgement) & NACK (Negative ACKnowledgement). At present, the main ARQ technologies include selective retransmission (SR, Selective Repeat) and stop waiting for retransmission (SAW, Stop And Wait).

HARQ is a technology that combines forward error correction coding (FEC, Forward Error Correction) and ARQ. It introduces the FEC subsystem in the ARQ system. The FEC subsystem is used to correct frequent error patterns to reduce the number of retransmissions , so that retransmission is requested only in rare error patterns, which increases system reliability and increases system transmission efficiency.

Therefore, in the HARQ communication system, when each data packet sent in the HARQ communication system contains parity bits for error correction and error detection, if the number of error bits in the received packet is within the error correction capability, the error is corrected by itself ; When the error is serious and has exceeded the error correction capability of the FEC, let the originator retransmit. HARQ can automatically adapt to changes in channel conditions and is insensitive to measurement errors and time delays. In this way, the reliability of the HARQ communication system is higher than that of the FEC system, and the transmission efficiency is higher than that of the ARQ system.

Due to the time-varying nature of the channel, the error of channel condition measurement, the effective modulation mode and the limited number of coding rate MCS (Modulation and Coding Scheme), AMC needs to be combined with HARQ. When AMC and HARQ are combined, better results can be obtained: AMC provides rough data rate selection, while HARQ can fine-tune the data rate according to data channel conditions.

According to the combination method, there are two types of HARQ: CC (Chase Combining) method and IR (Incremental Redundancy) method. In the CC mode, the data bits of the previous transmission are repeatedly sent during retransmission; in the IR mode, the data bits sent during retransmission include redundant bits that have not been sent in the previous transmission.

In addition, according to adaptability, HARQ that can change the modulation method during retransmission is called Adaptive HARQ (Adaptive HARQ); HARQ that cannot change the modulation method during retransmission and can only use the same modulation method as the initial transmission is called HARQ. Non-adaptive HARQ (Non-adaptive HARQ). Compared with non-adaptive HARQ, adaptive HARQ is more adaptable to changes in conditions such as channels and system resources, so its performance is better, but its complexity is also greater.

At present, when HARQ retransmits, there are mainly two retransmission modes: the data block size is constant and the data block size is reduced.

Solution 1 of the prior art: the size of the data block remains unchanged during HARQ retransmission, and the size of the retransmitted data block is the same as that of the initial transmission, that is, the retransmitted data volume is equal to the initial transmission. This scheme can be used in CC mode or IR mode. The modulation mode during retransmission can be adaptive or non-adaptive. When this scheme is applied to non-adaptive HARQ, the modulation mode during retransmission is the same as that during initial transmission, and the amount of system resources occupied is also the same as that during initial transmission. Therefore, the system resource scheduling and MCS selection algorithm during retransmission are very simple. When this scheme is applied to adaptive HARQ, the modulation method during retransmission can be adaptively changed according to channel conditions and other factors, so it may be different from the modulation method during initial transmission, resulting in a decrease in the amount of data that can be transmitted per unit resource. Changes, so the amount of system resources that need to be allocated for retransmission also changes accordingly.

However, the main disadvantage of the above-mentioned solution 1 of the prior art is that the amount of data transmitted during retransmission may be too much, which easily causes waste of system resources. Because each retransmission transmits the same amount of data as the initial transmission, the obtained retransmission gain is relatively large. The signal-to-noise ratio or decoding capability of the final data block may exceed actual needs, causing unnecessary waste of resources and reducing system throughput.

When this scheme is applied to adaptive HARQ, the amount of resources to be scheduled needs to be recalculated during retransmission, and the complexity of system resource scheduling and MCS selection algorithms increases accordingly.

Existing technical solution 2: The size of the data block is reduced during HARQ retransmission, and the size of the retransmitted data block is smaller than that of the initial transmission. For example, the amount of data retransmitted each time is equal to 1/N of the initial transmission, where N is An integer greater than 1. In this way, the granularity of adjusting the power/decoding capability of the initial transmission becomes smaller during retransmission, reducing resource waste during retransmission, thereby improving system throughput.

This scheme is generally used in the IR mode, and the modulation mode during retransmission can be adaptive or non-adaptive. When this scheme is applied to non-adaptive HARQ, the modulation mode during retransmission is the same as that during the initial transmission. If the amount of data retransmitted is equal to 1/N of the initial transmission, the amount of system resources occupied is also 1/N of the initial transmission. , so the algorithm for resource scheduling and MCS selection during retransmission is relatively simple. When this solution is applied to adaptive HARQ, the amount of resources that need to be scheduled during retransmission is related to the modulation mode during retransmission, and is adaptively changed.

However, the main disadvantage of the second prior art solution is that since the scheduling of system resources has a minimum allocation unit, reducing the size of the data block during retransmission may cause the size of the data block to not completely match the capacity of the allocated system resources. For example, the size of the retransmission data block is determined as equal to 1/N of the initial transmission. Assuming that the initial transmission allocates M minimum allocation units, where M and N are integers greater than 1, and non-adaptive HARQ is used, then the retransmission should be Allocate M/N minimum allocation units. Since M/N is not necessarily an integer, the actual amount of allocated resources should be K minimum allocation units, where K is the smallest integer greater than or equal to M/N, or the largest integer smaller than M/N. In this way, when K>M/N, the capacity of allocated system resources will be slightly larger than the amount of retransmitted data, and the data bits sent during retransmission need to be repeated or filled in other ways to fill these extra resources, which may cause certain problems. Waste of resources; when K<M/N, the capacity of allocated system resources will be slightly less than the amount of retransmitted data, and the data bits sent during retransmission need to be punched to remove these bits that exceed the transmission capacity of system resources, which may cause Some performance loss. After bit stuffing or puncturing is adopted, 1/N of the data volume for initial transmission does not completely match the data volume for retransmission (capacity of allocated system resources), which also increases the control signaling information required for retransmission.

With adaptive HARQ, this problem also exists because the required amount of system resources must be re-determined according to the reduced data block size.

When this scheme is applied to adaptive HARQ, the amount of resources that need to be scheduled during retransmission is also related to the modulation mode during retransmission, and will change adaptively, so the system resource scheduling and MCS selection algorithms are more complicated.

Contents of the invention

In view of this, a preferred embodiment of the present invention provides a method for determining the size of a retransmission data block in HARQ, a base station, and a data transmission method, which can effectively reduce waste of system resources, reduce control signaling information required for retransmission, and enable System resource scheduling is simple and easy to implement.

A method for determining the size of a retransmitted data block, comprising the following steps:

When retransmission occurs, the number of system resource units allocated for retransmission is less than the number of system resource units allocated for the initial transmission of the system;

Determine the modulation mode used on the system resources obtained in the retransmission process;

The retransmission data block size is determined according to the system resource units obtained in the retransmission process and the modulation mode determined on these system resource units.

A base station, wherein: the base station includes a scheduler and a retransmission data block size setting unit, the scheduler further includes a resource quantity allocation unit, and when retransmission occurs, the resource quantity allocation unit allocates the system resource units required for retransmission less than The number of system resource units allocated for the initial transmission of the system, the scheduler schedules the system resource units for the retransmission process according to the allocation result, and the retransmission data block size setting unit obtains the system resource units and the modulation determined on it according to the retransmission process The method determines the retransmission data block size.

A data transmission method, wherein, comprising the steps of:

During data transmission, when the receiver feeds back NACK to request retransmission, the number of system resource units allocated by the system for retransmission is less than the number of system resource units allocated by the system for initial transmission;

Determine the modulation mode used on the system resources obtained in the retransmission process;

Determine the size of the retransmitted data block according to the system resource unit obtained in the retransmission process and the modulation method adopted;

Perform rate matching according to the determined retransmission data block size;

The retransmitted data block is sent after being modulated according to the determined modulation mode.

Compared with the prior art, in the technical solution provided by the preferred embodiment of the present invention, when retransmitting, since the amount of system resources is determined first, and then the amount of retransmitted data is determined according to the transmission capacity of the system resources, the retransmission can be guaranteed. The size of the data block fully matches the amount of retransmission system resources, which can avoid the waste of system resource transmission capacity as much as possible, and can also reduce the control signaling information required for retransmission. Also, because the amount of system resources that should be scheduled during retransmission is determined first, the complexity of system resource scheduling can be reduced.

Description of drawings

FIG. 1 is a block diagram of a data downlink transmission process in a preferred first embodiment of the present invention.

Fig. 2 is a block diagram of a data uplink transmission process in a preferred first embodiment of the present invention.

Fig. 3 is a structural block diagram of a base station in a preferred first embodiment of the present invention.

Fig. 4 is a flowchart of determining the size of a data block in a preferred first embodiment of the present invention.

Detailed ways

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be described in further detail below in conjunction with specific implementation methods and accompanying drawings.

The technical solution of the present invention can be used in multiple communication systems, such as code division multiple access system (CDMA, Code Divsion Multiple Access), wideband code division multiple access system (WCDMA, Wideband Code Division Multiple Access) , Orthogonal Frequency Division Multiplexing (OFDM, Orthogonal Frequency Division Multiplexing) and other communication systems. In various communication systems, data transmission can be divided into uplink transmission and downlink transmission. Uplink means that the sender is a user terminal and the receiver is a base station; downlink means that the sender is a base station and the receiver is a user terminal.

In this preferred first embodiment, the sender can be a user terminal, and the receiver is a base station; When sending data, in order to select an effective coding and modulation method, it is necessary to know the current channel condition information. The following describes the downlink and uplink data transmission processes respectively through FIG. 1 and FIG. 2 .

As shown in FIG. 1 , it is a flow chart of downlink data transmission in a preferred first embodiment of the present invention, and the data transmission process can be described as follows.

Step 101a, the user terminal detects the channel condition of the downlink, and feeds back the channel condition information to the base station;

The user terminal detects the channel condition of the downlink through the downlink pilot, and then feeds back to the base station through Channel Quality Indication (CQI, Channel Quality Indication).

Step 102a: After receiving the channel condition information fed back by the user terminal, the base station determines the modulation and coding method used for data transmission according to the channel condition information, and schedules resources for data transmission, and notifies the user terminal of the scheduling result, modulation and coding method and other information ;

The base station schedules system resources for user terminals with downlink data transmission requirements according to the received channel condition information and according to corresponding criteria such as fairness PF principle, maximum throughput (max throughput) principle, round robin principle, etc. (such as time resources, frequency resources, code resources, etc.), determine the modulation and coding method and the size of the transmission block, and notify the user terminal of the above information such as system resource allocation, modulation method, and transmission block size.

The modulation and coding method mainly refers to the combination of RCPT (Rate Compatible Puncturing Turbocodes) and modulation method (MPSK & M-QAM).

Step 103a, the base station encodes and modulates the data, and sends it on the corresponding scheduled system resources;

The base station codes and modulates the data according to the determined modulation and coding mode, and sends it to the user terminal on the corresponding system resource according to the scheduling result.

Step 104a, the user terminal receives and decodes the code block, and if the decoding is incorrect, feeds back NACK to the base station and requests retransmission;

The user terminal receives and decodes the data in the allocated corresponding system resource, and performs ACK or NACK feedback according to the decoding result. If this transmission is a retransmission, the user terminal needs to combine the received data with the data of this data block received in the previous transmission before decoding.

If the decoding is correct, the user terminal feeds back an ACK to the base station, and this transmission ends.

If the decoding is incorrect, the user terminal feeds back NACK to the base station and requires retransmission.

Step 105a, if the feedback is NACK, perform HARQ retransmission, that is, enter a similar cyclic process as above, return to step 102a, and the scheduler determines the modulation and coding method for retransmission again according to the channel conditions fed back by the user terminal, which is the retransmission process Scheduling system resources, notifying the user terminal of relevant information, and starting retransmission. The transmission ends until the user terminal feeds back an ACK or reaches the maximum number of retransmissions.

In addition, when a large transmission block needs to be divided into several sub-blocks, each sub-block is individually added with a cyclic redundancy check (CRC, Cyclical Redundancy Check) code. It is also possible to retransmit all the sub-blocks transmitted last time.

What is described above is the downlink data transmission process. In the uplink data transmission process, the data transmission is slightly different, as shown in FIG. 2 , which is mainly described as follows.

Step 101b, the base station measures the uplink channel condition, determines the modulation and coding mode for uplink data transmission according to the channel condition information, schedules system resources for uplink transmission, and notifies the user terminal of relevant information;

The base station schedules system resources for user terminals requesting uplink resource scheduling based on the measured uplink channel condition information and corresponding criteria such as fairness PF principle, maximum throughput (max throughput) principle, round robin principle, etc. (including frequency resources, code resources and time resources, etc.), determine the modulation and coding scheme, and notify the user terminal of the scheduled system resource and modulation scheme.

Step 102b, the user terminal sends data according to the scheduled system resource and modulation mode;

Step 103b, the base station receives and decodes the code block, and if the decoding is incorrect, feeds back NACK to the user terminal, requesting HARQ retransmission;

The base station receives and decodes data in corresponding allocated system resources, and performs ACK or NACK feedback according to the decoding result. If this transmission is a retransmission, the base station needs to combine the received data with the data of this data block received in the previous transmission before decoding.

If the decoding is correct, the base station immediately feeds back an ACK to the user terminal, and this transmission ends.

If the decoding is incorrect, the base station feeds back NACK to the user terminal, requesting retransmission.

Step 104b, if the feedback is NACK, perform HARQ retransmission, that is, enter a similar cycle process as above, return to step 101b, the scheduler determines the modulation and coding method for retransmission again according to the channel conditions measured by the base station, and schedules the retransmission process System resources, and notify the user terminal of relevant information, and start retransmission. The transmission ends until the base station feeds back an ACK or reaches the maximum number of retransmissions.

In addition, when a large transmission block needs to be divided into several sub-blocks, each sub-block is individually added with a cyclic redundancy check (CRC, Cyclical Redundancy Check) code. It is also possible to retransmit all the sub-blocks transmitted last time.

Regarding the HARQ retransmission process, the following description will be used for detailed description.

In order to effectively reduce the waste of system resources, make the system resource scheduling and MCS selection algorithm simple and easy to implement, and make the data block size fully match the allocated system resource capacity, reduce the signaling information that needs to be transmitted, before HARQ retransmission , it is necessary to set the size of the retransmitted data block.

As shown in FIG. 3 , it is a block diagram of a base station that can set the size of a retransmission data block in a preferred first embodiment.

The base station mainly includes a channel condition acquisition unit 201, a scheduler 202, an MCS selection unit 203, a retransmission data block size setting unit 204, a coding and rate matching unit 205, a modulation unit 206, and a transmitting unit 207, wherein the scheduler 202 further includes a resource For the quantity allocation unit 2021, the main working process of the base station can be shown in FIG. 4 .

Step 301, acquiring channel condition information;

Before data retransmission, in order for the scheduler 202 of the base station to schedule appropriate system resources and the MCS selection unit 203 to select a suitable modulation scheme, the scheduler 202 and the MCS selection unit 203 need to obtain channel condition information. According to whether the retransmission process is uplink transmission or downlink transmission, the channel condition acquiring unit 201 acquires channel condition information in different ways.

If it is a downlink transmission process, the channel condition acquisition unit 201 acquires downlink channel quality information by receiving the CQI fed back by the user terminal; if it is an uplink transmission process, the channel condition acquisition unit 201 of the base station acquires uplink channel quality information through measurement.

Step 302, allocating the number of system resource units required for retransmission is less than the number of system resource units allocated by the system for the initial transmission, and scheduling system resources for the retransmission process according to the determined number of system resource units;

The resource quantity allocation unit 2021 of the scheduler 202 allocates the number of system resource units required for retransmission according to the principle that the system resources (such as time resources, frequency resources, code resources, etc.) used for retransmission are reduced compared with the initial transmission, and the scheduler 202 System resources are scheduled for the retransmission process according to the determined number of system resource units. For example, the resource quantity allocation unit 2021 can allocate the system resource quantity for this retransmission as 1/N of the system resource quantity used for the initial transmission, where N is an integer or fraction greater than 1, and 1/N of the system resource unit quantity used for the initial transmission is an integer, that is, the number of system resource units for retransmission is an integer; when 1/N of the number of system resource units used for the initial transmission is a non-integer number, the resource quantity allocation unit 2021 allocates the number of system resource units for retransmission It is an integer greater than or less than 1/N of the number of system resource units used for initial transmission. For further convenience, it can be an adjacent integer greater than or less than 1/N of the number of system resource units used for initial transmission. For example, when the value of N is 2, the amount of system resources occupied during the retransmission is reduced to half of the initial transmission, that is, the resource quantity allocation unit 2021 allocates half of the system resources during the initial transmission to the retransmission process.

Step 303, determine the modulation mode used on the system resources obtained in the retransmission process;

The MCS selection unit 203 selects different modulation schemes according to whether the retransmission process is adaptive retransmission or non-adaptive retransmission.

If it is adaptive retransmission, the MCS selection unit 203 determines the modulation scheme according to the channel condition information on the system resource units allocated by the scheduler 202 for retransmission.

If it is a non-adaptive retransmission, the MCS selection unit 203 determines that the modulation mode of the retransmission is the same as the modulation mode of the initial transmission.

The modulation unit 206 modulates the coded and rate-matched data according to the modulation mode selected by the MCS selection unit 203 .

Step 304, calculating the retransmission data block size according to the system resource units obtained in the retransmission process and the modulation method adopted;

The retransmission data block size setting unit 204 calculates the retransmission data block size (number of bits) according to the system resource unit determined by the scheduler 202 and the modulation mode on these system resources determined by the MCS selection unit 203 during retransmission. The coding and rate matching unit 205 will perform channel coding and rate matching on the data according to the size of the retransmission data block indicated by the retransmission data block size setting unit 204, so that the size of the data block after channel coding is equal to that of the retransmission data block size setting unit 204 Indicates the block size of the retransmitted data. Since the system resource required for retransmission is determined first (step 302), and then the size of the retransmission data block is determined (step 304) according to the transmission capability of the system resource (step 303), the size of the retransmission data block can be compared with the retransmission system The resources are fully matched (no bit stuffing), which can effectively reduce control signaling.

Step 305, the base station notifies the user terminal of the necessary information used in the retransmission process, such as the system resources allocated to it, the modulation mode, etc., and starts the retransmission process;

In step 306, the sender performs encoding, rate matching and modulation on the data, and sends the retransmission data.

For the downlink, "the sender performs encoding, rate matching and modulation on the data" in step 306 may occur before step 305 .

In order to more clearly illustrate that the technical solution provided by the preferred embodiment of the present invention can effectively reduce the waste of system resources compared with the existing technology, and make the system resource scheduling and MCS selection algorithm simple and easy to implement, the following is a comparison of some parameters in specific embodiments. The existing technical solutions are compared and explained in detail.

Taking an Orthogonal Frequency Division Multiplexing (OFDM, Orthogonal Frequency Division Multiplexing) system as an example below, the solution of the present invention will be further described in detail.

In an OFDM system, when resource scheduling is performed, the time-frequency resources allocated to users have a minimum allocation unit. This minimum allocation unit is called RU (Resource Unit) in this paper. RU is time-frequency two-dimensional, and in the frequency domain Occupies several subcarriers and occupies a certain length of continuous OFDM symbols in time.

The following behavior is an example. Assume that each RU can carry 150 modulation symbols. The base station needs to send a data packet to the UE. It is 16QAM modulation and a coding rate of 4/5, then the size of the coded data block is 2400/(4/5)=3000bit, and each RU can carry 150×4=600bit, and a total of 5 RUs are required.

After receiving this data block, the UE will feed back to the base station and request retransmission when it finds that the transmission is wrong after detection. When retransmitting, there are two retransmission modes: non-adaptive HARQ and adaptive HARQ.

The retransmission method adopted in the preferred second embodiment of the present invention is a non-adaptive HARQ retransmission method. When retransmission occurs, the number of RUs required for retransmission is determined according to the principle that the system resources used for retransmission are reduced compared with the initial transmission. For example, it may be determined that the amount of system resources occupied during retransmission is 1/N of the amount of system resources used for initial transmission, where N is an integer or fraction greater than 1. Set the value of N to 2, that is, the amount of system resources occupied by retransmission is reduced to half of the initial transmission, that is, 2.5 RUs, because the minimum unit of system resource scheduling is 1 RU, and 2.5 RUs are not system resources that can be allocated The integer multiple of the smallest unit, so the amount of system resources represented by these system resource units (RU) should be an integer less than or greater than 5/2 RU of the system resources occupied by the initial transmission, and can be smaller than or greater than the initial transmission. The adjacent integers of 5/2 RUs of the system resource amount, such as the adjacent integer 3 greater than 2.5 in this embodiment, so in this preferred second embodiment, the scheduler in the base station will 3 RUs are scheduled, and 3 RUs are allocated to it.

After allocating system resources, because it is non-adaptive HARQ, the modulation mode used on these 3 RUs during retransmission is still the modulation mode 16QAM of the initial transmission. According to the allocated RUs and the modulation mode on each RU, it can be easily obtained how much data can be transmitted on these time-frequency resources. In the preferred second embodiment, the amount of data that can be transmitted during retransmission is 3*150*4=1800 bits, and 3*150*4=1800 bits can be transmitted by scheduling 3 RUs using 16QAM. In this way, the size of the retransmission data block completely matches the resource amount of the retransmission system (no bit stuffing), which can reduce control signaling, and the size of the data block sent during retransmission is 1800 bits. The 1800-bit data can be redundant information or data bits transmitted during initial transmission, which depends on the combination method adopted by HARQ. If the IR combination is adopted, after the receiving end combines the retransmission data and the initial transmission data, the coding rate of the received data block is reduced from 4/5 at the time of initial transmission to 1/2.

After the base station determines the time-frequency resources to be occupied by the retransmission process, the modulation method used, and the size of the data block to be sent, it can notify the UE of the relevant information through signaling, and then start to send the retransmitted data.

The following compares the differences in occupied system resources and system throughput performance between the technical solution of the preferred second embodiment and the prior art 1 and the prior art 2.

If the existing technology 1 is used, that is, the size of the retransmitted data block is as large as that of the initial transmission, the size of the transmitted data block during retransmission is 3000 bits, and the amount of system resources occupied by retransmission in the preferred second embodiment is 1800 bits. It can be seen that the amount of system resources occupied by retransmission in this preferred second implementation mode is much less than that in the prior art one.

If the existing technology 2 is used, that is, the size of the retransmitted data block is smaller than that of the initial transmission, such as 1/N of the initial transmission, in order to facilitate comparison with the technical solution of the preferred second embodiment, N is also used =2, then the size of the retransmitted data block in the second prior art is 3000/2=1500bit. Because non-adaptive HARQ is used, the modulation method used on each RU is still 16QAM during retransmission, and 2 RUs can only transmit 2×150×4=1200 bits with 16QAM, so 3 RUs need to be scheduled for the retransmission process, and 3 One RU can transmit 1800 bits, which is greater than the 1500 bits to be transmitted, so it is necessary to perform bit stuffing or other operations on the retransmitted data block.

However, in the preferred second implementation manner, since it is first determined that the amount of system resources occupied by retransmission is 1800 bits, scheduling 3 RUs and using 16QAM can transmit 3×150×4=1800 bits. Then, according to the allocated RUs and the modulation mode on each RU, it is determined that the amount of data that can be transmitted during retransmission is 3×150×4=1800 bits. In this way, the size of the retransmitted data block completely matches the amount of retransmission system resources (no bit Filling), which can reduce the control signaling, so this preferred second implementation manner can make full use of the transmission capacity of system resources.

The retransmission method adopted in the preferred third embodiment of the present invention is an adaptive HARQ retransmission method. When retransmission occurs, the number of RUs required for retransmission is determined according to the principle that the system resources used for retransmission are reduced compared with the initial transmission. In the preferred third embodiment of the present invention, similar to the second embodiment, it is determined that the amount of system resources for retransmission is 1/2 of the initial transmission, that is, the amount of system resources occupied by retransmission is reduced to half of the initial transmission, and the retransmission The transmission process requires 3 RUs for scheduling, and 3 RUs are allocated to it.

After allocating system resources, adaptive HARQ is adopted, and the base station determines the modulation schemes that should be used on these three RUs according to the allocated CQI (Channel Quality Indication Information) on these three RUs. When the channel condition is better during retransmission, the modulation method used on these 3 RUs can adopt 64QAM, then the amount of data that can be transmitted during retransmission is 3×150×6=2700bit, and the scheduling of 3 RUs can transmit 3 ×150×6=2700bit. In this way, the size of the retransmission data block completely matches the resource amount of the retransmission system (no bit stuffing), which can reduce control signaling, and the size of the data block sent during retransmission is 2700 bits. When the channel condition is poor during retransmission, the modulation method used on these 3 RUs can only use QPSK, then the retransmission data block size is 3×150×2=900bit, and scheduling 3 RUs can transmit 3× 150×2=900bit. In this way, the size of the retransmission data block fully matches the resource amount of the retransmission system (no bit stuffing), which can reduce control signaling, and the size of the data block sent during retransmission is 900 bits.

The following compares the differences in occupied system resources and system throughput performance between the technical solution of the preferred third embodiment and the prior art 1 and the prior art 2.

If the existing technology 1 is used, that is, the size of the retransmitted data block is the same as that of the initial transmission, and the size of the transmitted data block during retransmission is 3000 bits. Since adaptive HARQ is used, the modulation method during retransmission needs to be based on channel conditions, etc. Factors are adaptively changed, and the amount of system resources that need to be allocated during retransmission is also adaptively changed. Therefore, it is necessary to re-determine how many RUs are scheduled for retransmission, and how many RUs should be scheduled is related to the channel conditions (indicated by CQI) on each RU. After scheduling RUs, the base station then determines the modulation method to be used on these RUs. , this process is more complicated.

When the channel condition is better during retransmission, 4 RUs are allocated, and the modulation mode determined on these 4 RUs is 64QAM. In this way, the scheduled 4 RUs can transmit 4×150×6=3600 bits, which is more than the 3000 bits of the retransmitted data block. At this time, bit stuffing or other operations need to be performed on the retransmitted data block.

If the existing technology 2 is used, that is, the size of the retransmitted data block is smaller than that of the initial transmission, such as 1/2 of the initial transmission, then the retransmitted data block size is 3000/2=1500bit. Because adaptive HARQ is adopted, the modulation mode during retransmission needs to be adaptively changed according to factors such as channel conditions, and the amount of system resources that need to be allocated during retransmission is also adaptively changed. Therefore, it is also necessary to re-determine the number of RUs to be scheduled during retransmission. After scheduling the RUs, the base station then determines the modulation mode to be used on these RUs.

When the channel condition is better during retransmission, 2 RUs are allocated, and the modulation mode determined on these 2 RUs is 64QAM. In this way, the two scheduled RUs can transmit 2×150×6=1800 bits, which is more than the 1500 bits of the retransmitted data block, and bit stuffing or other operations need to be performed on the retransmitted data block.

Therefore, compared with prior art 1 and prior art 2, since the amount of system resources required for retransmission is known in this preferred third embodiment, the number of RUs to be scheduled is also known, so the whole process is relatively simple. And when retransmitting, first determine the amount of system resources, and then determine the amount of retransmitted data according to the transmission capacity of the system resources, so that the size of the retransmitted data block is completely matched with the amount of retransmitted system resources (without bit stuffing), which can reduce control information. make.

To sum up, the technical solution of the present invention reduces the amount of system resources allocated to the retransmission process and refines the granularity of retransmission gain adjustment during retransmission, so unnecessary waste of retransmission gains can be reduced. Improve system throughput.

And when retransmitting, the amount of system resources is determined first, and then the amount of retransmitted data is determined according to the transmission capacity of the system resources, which can ensure that the size of the retransmitted data block exactly matches the amount of retransmitted system resources, and can avoid system resource transmission as much as possible A waste of capacity. Also, because the amount of system resources that should be scheduled during retransmission is determined first, the complexity of system resource scheduling can be reduced.

However, the above is only a preferred embodiment of the present invention, and is not intended to limit the protection scope of the present invention. Any person familiar with the technical field should recognize that within the scope of the spirit and principles of the present invention, any Modifications, equivalent replacements, improvements, etc., should all be included within the protection scope of the present invention.

Claims (15)

1. the method for a definite data retransmission block size is characterized in that, comprises the steps:

When taking place to retransmit, distribute the required system resource element number of re-transmission to be less than system and just pass institute's distributed system resources element number;

Determine the modulation system that adopts on the system resource that this retransmission processes obtains;

The modulation system of determining on the system resource unit that obtains according to this retransmission processes and these system resource unit is determined the data retransmission block size.

2. the method for a kind of definite data retransmission block size as claimed in claim 1, it is characterized in that, the required system resource element number of described distribution re-transmission is less than system's required system resource element number of first biography and is specially: distributing the system resource element number when retransmitting is the 1/N of first biography system for use in carrying Resource Unit quantity, wherein N is integer or the mark greater than 1, and the system resource element number when retransmitting is an integer.

3. the method for a kind of definite data retransmission block size as claimed in claim 2, it is characterized in that: when the described 1/N that just passes system for use in carrying Resource Unit quantity was non-integer, the system resource element number that then described distribution retransmits was to be greater than or less than the integer that just passes system for use in carrying Resource Unit quantity 1/N.

4. the method for a kind of definite data retransmission block size as claimed in claim 2, it is characterized in that: when the described 1/N that just passes system for use in carrying Resource Unit quantity was non-integer, the system resource element number that then described distribution retransmits was to be greater than or less than the adjacent integer that just passes system for use in carrying Resource Unit quantity 1/N.

5. the method for a kind of definite data retransmission block size as claimed in claim 1 is characterized in that: the modulation system of described re-transmission is determined according to the channel condition on the used system resource unit of the re-transmission of current acquisition.

6. base station, it is characterized in that: this base station comprises that scheduler, data retransmission block size are provided with the unit, scheduler further comprises the resource quantity allocation units, when taking place to retransmit, the required system resource element number of resource quantity allocation units distribution re-transmission is less than system and just passes institute's distributed system resources element number, scheduler is given this retransmission processes dispatching patcher Resource Unit according to this allocation result, and the data retransmission block size is provided with the unit and determines the data retransmission block size according to system resource unit and upward definite modulation system thereof that this retransmission processes obtains.

7. a kind of base station as claimed in claim 6, it is characterized in that: this base station also comprises channel condition acquiring unit and MCS selected cell, channel condition when the channel condition acquiring unit obtains current retransmit, the MCS selected cell is determined modulation system on it according to retransmitting channel condition on the institute distributed system resources unit.

8. a kind of base station as claimed in claim 6, it is characterized in that: the resource quantity allocation units distribute the system resource element number when retransmitting to be the first 1/N that passes system for use in carrying Resource Unit quantity, wherein N is integer or the mark greater than 1, and the system resource element number when retransmitting is an integer.

9. a kind of base station as claimed in claim 6, it is characterized in that: this base station also comprises coding and rate-matched unit, encode and rate-matched to the data bit according to the data retransmission block size that the data retransmission block size is provided with the unit indication in this coding and rate-matched unit, the data block size after the rate-matched equals the data retransmission block size that the data retransmission block size is provided with the unit indication.

10. a data transmission method is characterized in that, comprises the steps:

In the transmission data procedures, when the recipient fed back NACK and requires to retransmit, system assignment retransmitted required system resource element number and is less than system and just passes institute's distributed system resources element number;

Determine the modulation system that adopts on the system resource that this retransmission processes obtains;

Determine the data retransmission block size according to the system resource unit of this retransmission processes acquisition and the modulation system of employing;

Carry out rate-matched according to the data retransmission block size of determining;

Send the data block that retransmits according to the modulation system modulation back of determining.

11. a kind of data transmission method as claimed in claim 10, it is characterized in that: described distribution retransmits required system resource element number and is less than system and just passes institute's distributed system resources element number and be specially: distribute system resource element number when retransmitting for just passing the 1/N of system for use in carrying Resource Unit quantity, wherein N is integer or the mark greater than 1, and the system resource element number when retransmitting is an integer.

12. a kind of data transmission method as claimed in claim 11, it is characterized in that: when the described 1/N that just passes system for use in carrying Resource Unit quantity was non-integer, the system resource element number that then described distribution retransmits was to be greater than or less than the integer that just passes system for use in carrying Resource Unit quantity 1/N.

13. a kind of data transmission method as claimed in claim 11, it is characterized in that: when the described 1/N that just passes system for use in carrying Resource Unit quantity was non-integer, the system resource element number that then described distribution retransmits was to be greater than or less than the adjacent integer that just passes system for use in carrying Resource Unit quantity 1/N.

14. a kind of data transmission method as claimed in claim 10, it is characterized in that: before determining the modulation system that adopts on the system resource that this retransmission processes obtains, measure current channel condition, the channel condition during then according to current the re-transmission on the system for use in carrying Resource Unit is determined described modulation system.

15. a kind of data transmission method as claimed in claim 10, it is characterized in that: describedly carry out rate-matched according to the data retransmission block size and be specially according to the data retransmission block size data are carried out rate-matched, the data block size after the rate-matched equals determined data retransmission block size.