WO2009097808A1

WO2009097808A1 - Method for link adaptation in wideband wireless mobile comunication systems, system and apparatus thereof

Info

Publication number: WO2009097808A1
Application number: PCT/CN2009/070285
Authority: WO
Inventors: Yang Yu; Shaohui Sun; Yingmin Wang
Original assignee: Da Tang Mobile Communications Equipment Co., Ltd.
Priority date: 2008-02-03
Filing date: 2009-01-22
Publication date: 2009-08-13
Also published as: CN101499828B; CN101499828A

Abstract

A method for link adaptation in wide-band wireless mobile communication systems is disclosed. By analyzing state information of the channel, the channel variety factor is calculated. Then a decision is taken to determine whether the state of the current channel varies dramatically based on the channel-varying factor. If so, signals are transmitted by using BR-OFDMA (Block Repeat- Orthogonal Frequency Division Multiple Access) mode; otherwise, signals are transmitted by using OFDMA (Orthogonal Frequency Division Multiple Access) mode. The corresponding wide-band wireless mobile communication system and apparatus are also disclosed. The method, system and apparatus can enhance the spectrum efficiency under high-speed mobile circumstance.

Description

Link adaptive method, system and device for broadband wireless mobile communication system

The present invention relates to mobile communication technologies, and in particular, to a broadband wireless mobile communication system link adaptation method, system and apparatus. Background of the invention

At present, broadband wireless mobile communication has become the main development direction of mobile communication. In the International Advanced Telecommunications (ITU) of the International Telecommunications Union (ITU), the maximum bandwidth of wireless mobile communication is 100MHz, and the maximum transmission rate is up to 1Gbps, which can satisfy users' wireless. Great demand for mobile communications. Through broadband wireless mobile communication, users can enjoy high-speed data download, online shopping, mobile video chat and mobile TV and many other wireless mobile services.

In a cellular mobile communication system for broadband wireless mobile communication, a wireless channel is a multipath time-varying channel, including propagation loss, fast fading, slow fading, and interference variation, so that the quality of the received signal is also affected by channel conditions. variable. In practical applications, in order to improve system capacity and spectrum utilization, link adaptation technology is generally used in the communication process. This technology has been widely recognized as an important means to effectively improve spectrum utilization in broadband wireless mobile communication systems. one. The link adaptation technology performs effective adjustment of the transmission parameters according to the obtained channel state information, such as time, frequency or spatial characteristic information, to implement adaptive transmission. Therefore, the channel state information needs to be able to accurately reflect the actual state of the channel.

Generally, channel state information is measured by a user terminal (UE, User Equipment). And feedback to the base station. However, for high-speed mobile UEs, for example, high-speed railways can now reach speeds of 250Km/h, while maglev trains can reach speeds of 400Km/h. In these scenarios, channel state changes relatively quickly, in many cases. When the base station receives the channel state information fed back by the UE, the actual channel state has undergone a new change, that is, there is a measurement error between the channel state information received by the base station and the actual channel state. Therefore, using link adaptation technology in a high-speed moving scenario will result in worse performance, especially for Time Division Duplexing (TDD) systems, where feedback delay is large, and link adaptation techniques are applied. The impact will be more significant.

For example, existing link adaptation techniques generally refer to technologies such as adaptive power control or Adaptive Modulation and Coding (AMC). Taking AMC as an example, the technique is sensitive to measurement error and delay. Therefore, whether the UE can accurately and real-time feedback channel state information will have the correct choice for the AMC modulation and coding scheme (MCS). Great impact. MCS, as an important indicator of modulation and coding in AMC, will have a significant impact on the performance of AMC, especially in low to medium SNR channels. At the same time, the measurement result report delay (refer to the time between the UE obtaining the channel state information and the base station selecting the MCS) also reduces the reliability of the channel estimation. The delay mentioned here mainly refers to the processing time of the UE and the processing of the base station. Time and delay caused by multiplexing and scheduling.

In order to overcome the impact of AMC on system performance due to measurement error and delay sensitivity, the solution proposed in Long Term Evolution (LTE) is to combine AMC with Hybrid Automatic Retransmission Request ( HARQ). ) Technology combined. HARQ is an error correction method that combines Automatic Retransmission Request (ARQ) and Forward Error Correction (FEC) to automatically correct received data within the scope of error correction capability. Wrong, if the error correction range is exceeded, the sender is required to resend the data. This method can increase the system The reliability of the system can improve the transmission efficiency of the system. By combining HARQ with AMC technology, HARQ encoding and retransmission combining functions can be utilized to reduce the impact of increased error rate due to transmission rate greater than channel capacity on system performance.

However, for a high-speed channel environment, the introduction of AMC and HARQ technology solutions will bring a series of problems, such as:

1) The channel status information is inaccurate, resulting in inaccurate MCS selection, and the MCS selection is inaccurate and causes data to be retransmitted multiple times, which in turn leads to an increase in transmission delay. For time-sensitive services, this delay cannot be tolerated. of;

2) HARQ technology puts forward higher requirements on the transceiver storage device: For the receiving end, the receiving end needs to buffer the decoding error data, until the retransmitted data is received and the decoding is correct, the buffered data will be cached. Release, if there is more data to be retransmitted, the buffer space that needs to be occupied will be very large. Similarly, for the sender, the data that is not acknowledged needs to be buffered until the correct acknowledgement message sent by the receiver is received. , in order to release the cached data;

3) The data encoding and decoding process is complicated;

4) Reduce the frequency usage of the system: Since the data retransmission occupies the system time-frequency resources, the system capacity is reduced. Summary of the invention

In view of this, the main object of the present invention is to provide a link adaptive method for a broadband wireless mobile communication system, which can improve the spectrum utilization rate of the system in a high-speed mobile scenario.

Another object of the present invention is to provide a broadband wireless mobile communication system capable of improving the spectrum utilization rate of a system in a high speed mobile scenario.

Still another object of the present invention is to provide a broadband wireless mobile communication device capable of improving spectrum utilization of a system in a high speed mobile scenario. To achieve the above objective, the technical solution of the present invention is implemented as follows: A link adaptation method for a broadband wireless mobile communication system, the method comprising: analyzing channel state information, calculating a channel change factor, according to the channel change The factor determines whether the current channel state changes drastically;

If yes, the block repeat orthogonal frequency division multiple access method is used for signal transmission; if not, the orthogonal frequency division multiple access method is used for signal transmission.

A broadband wireless mobile communication system, the system includes: a base station and a user terminal; the user terminal is configured to analyze channel state information, calculate a channel change factor, and report the channel change factor to the base station;

The base station is configured to determine, according to the received channel change factor, whether the current channel state changes drastically, and if yes, use a block-repetitive orthogonal frequency division multiple access method to perform signal transmission; if not, use orthogonal frequency division multiple The address mode is used for signal transmission.

A broadband wireless mobile communication device, the device comprising: a computing unit, a determining unit

^^射单元;

The calculating unit is configured to calculate a channel change factor according to the acquired channel state information;

The determining unit is configured to determine, according to the channel change factor, whether the current channel state changes drastically;

The transmitting unit is configured to perform signal transmission by using a block-repetitive orthogonal frequency division multiple access method when the judgment result of the determining unit is a drastic change of the current channel state; otherwise, the signal is performed by using an orthogonal frequency division multiple access method. emission.

It can be seen that, by using the technical solution of the present invention, the channel state information is analyzed, the channel change factor is calculated, and the current channel state is determined to be drastically changed according to the calculated channel change factor; if yes, the block repeat orthogonal frequency division is used. The address mode performs signal transmission; if not, the orthogonal frequency division multiple access method is used for signal transmission. Compared with the prior art, this The solution of the invention can adopt different strategies for link adaptive scheduling according to different application scenarios, thereby improving the spectrum utilization rate of the system. BRIEF DESCRIPTION OF THE DRAWINGS

The above and other features and advantages of the present invention will become more apparent to those skilled in the <

1 is a flow chart of an embodiment of a link adaptation method for a broadband wireless mobile communication system according to the present invention.

2 is a schematic structural diagram of an embodiment of a broadband wireless mobile communication system according to the present invention. FIG. 3 is a schematic structural diagram of an embodiment of a broadband wireless mobile communication device according to the present invention. Mode for carrying out the invention

The present invention will be further described in detail below with reference to the accompanying drawings.

In order to solve the problems existing in the prior art, the present invention proposes a new link adaptation method for a broadband wireless mobile communication system, which selects different signal transmission modes according to different channel states, so as to improve the system in a high-speed mobile scene. Capacity and spectrum utilization. The specific implementation idea is: analyzing the channel state information, calculating a channel change factor, determining whether the current channel state changes drastically according to the channel change factor; if yes, using block repetition orthogonal frequency division multiple access (BR-OFDMA) , Block Repeat- Orthogonal Frequency Division Multiple Access) performs signal transmission; if not, it adopts OFDMA mode for signal transmission, and can use adaptive schemes such as AMC and HARQ in signal transmission. The solution of the present invention is particularly suitable for use in a TDD broadband wireless mobile communication system.

The scheme of the present invention will be further described in detail below with reference to specific embodiments. FIG. 1 is a flowchart of a link adaptation method for a broadband wireless mobile communication system according to the present invention. Figure. As shown in Figure 1, the following steps are included:

Step 101: The channel state information is analyzed, the channel change factor is calculated, and the current channel state is determined to be drastically changed according to the calculated channel change factor. If yes, step 102 is performed; otherwise, step 103 is performed.

The judgment of the channel state change situation is the first problem to be considered in the solution of the present invention. Generally, the channel state information used in the link adaptation scheme is the Signal to Interference Noise Ratio (SINR) of the time-frequency resource block PRB. However, the SINR itself does not indicate the channel state change. degree.

The duration in which the UE is in a state of a certain moving speed is often much larger than the statistical period of the wireless communication system. Therefore, an extreme situation can be envisaged. For maglev trains, the starting time is usually 40s, that is, the speed change from quiescent state to acceleration to 400Km/h is only 10Km/h. The amount of change does not substantially affect the channel state in which the UE is located. For a broadband wireless mobile communication system, 200 times of 5 ms subframes will be experienced within the time of Is, and the channel variation can be fully investigated. Therefore, a relatively long time window, such as ls, can be set. In this time window, the average rate of change of the SINR sequence is examined, and the average rate of change of the SINR sequence is used as a channel variation factor to reflect the channel state change. The specific implementation is as follows:

1) In the preset time window, such as Is, the SINR sequence 0, _αι , α ₂ , ..., a _{N is} measured, and the measurement interval is seconds. The specific measurement method is prior art and will not be mentioned.

2) Calculate the rate of change sequence of the SINR sequence HA, ... A - where Α· ₌ ι "' ⁺¹ _"' ι, ₌ ο, ι,···, ν_ι.

¹ τ

3) Calculate the average rate of change of the SINR sequence. After calculating the average rate of change of the SINR sequence, compare it with a preset threshold to determine whether the average rate of change of the SINR sequence is greater than a preset threshold, and if so, It indicates that the current channel state changes drastically; if not, it indicates that the current channel state change is relatively stable.

The above scheme for using the average rate of change of the SINR sequence as the channel variation factor can make full use of the measurement information in the existing link adaptation scheme, and has good compatibility. In practical applications, other parameters can also be used as channel change factors to reflect the degree of change in channel state. T匕 ^ mouth:

It is assumed that the pilot channel response of the kth subcarrier on the mth OFDM symbol is H _m , _k by channel estimation, and the pilot channel response of the kth subcarrier on the m+1th OFDM symbol is H _m+W , then The correlation coefficient between pilots can be calculated as r= E(H _m , H: _{+hk ) o} where E

( ) indicates the expected value. If the calculated inter-pilot correlation coefficient ^ is large, it indicates that the channel state change is relatively stable; otherwise, the channel state change is relatively severe.

In order to correspond to the case where the average rate of change of the SINR sequence is used as the channel change factor, the reciprocal of the correlation coefficient y between pilots is used as the channel change factor in the embodiment of the present invention. When the channel state change condition is judged, the reciprocal of the inter-pilot correlation coefficient γ is compared with the preset threshold value, and it is determined whether the reciprocal of the inter-pilot correlation coefficient γ is greater than a preset threshold, and if so, the current The channel state changes drastically; if not, it indicates that the current channel state change is relatively stable.

In addition to the above two methods, in practical applications, the combination of the average rate of change of the SINR sequence and the correlation coefficient y between the pilots may be used as the channel variation factor, and the specific combination manner may be set as needed. For example, the simplest combination method may be adopted: an average rate of change of the SINR sequence + a correlation coefficient between pilots, or a weight coefficient and the like before the average rate of change of the SINR sequence and the correlation coefficient y between the pilots. After that, it is judged whether the result obtained by combining the average rate of change of the SINR sequence and the reciprocal of the inter-pilot correlation coefficient y is greater than a preset threshold, and if so, the current channel state is drastically changed; Then, the current channel state change is relatively stable.

In practical applications, the specific values of the various thresholds used in the above processes can be set according to actual needs.

Step 102: Perform signal transmission by using the BR-OFDMA method, and then end the process. The BR-OFDMA mentioned here refers to the combination of OFDMA and Code Division Multiple Access (CDMA) technology. On the basis of OFDM modulation, block repetition is used instead of chip repetition in conventional CDMA. Substituting the block repetition code for the spreading code to obtain the code domain spreading gain; using different or low correlation block repetition codes between different cells or users, and using the multi-user joint detection receiving method at the receiving end to eliminate inter-cell or user Interference to improve system performance.

The BR-OFDMA technology is used in the high-speed mobile scenario. Therefore, in the embodiment of the present invention, when the current channel state is determined to be drastically changed, the BR-OFDMA mode is used for signal transmission, and the specific implementation includes: Matching, grouping according to the channel state of the UE, grouping UEs with similar channel states into the same group; determining block repetition factor (RF, Repeat Factor) and block repetition pattern corresponding to each group of UEs, and using UEs in each group The same RF and block repeat pattern; signal transmission is performed according to the determined RF and block repeat patterns. The key steps of user matching, RF, and block repeat pattern determination are described below:

1) User match

In BR-OFDMA, a BR-OFDMA resource block occupies RF basic time-frequency resource blocks and can support RF user data. Each user uses 1/RF of transmit power.

In a cell, there are usually multiple UEs in a high-speed mobile state. Therefore, in actual applications, each RF UE is divided into a group, and UEs in each group use the same RF and the same block repetition pattern. In this way, there will be a problem of user matching, and UEs in the same group need to have similar channel states. The specific grouping manner is: acquiring channel change factors and path loss values corresponding to each UE. The acquisition of the channel change factor has been introduced in step 101. The acquisition of the path loss value is prior art and will not be described again. Then, the UEs are sorted according to the size of the path loss value, and then sorted according to the channel change factor in the UEs with similar path loss values, thereby finding UEs with similar path loss values and channel change factors, These UEs are grouped together to determine their corresponding RF and block repetition patterns.

2) RF

The implementation complexity of the multi-user joint detection algorithm in BR-OFDMA is related to RF. In order to reduce the implementation complexity, a smaller RF should be used, and for calculation convenience, the value of RF should be an integer power of 2. For example, 4, 8 or 16 and so on. However, if the RF value is small, it will not be able to improve the spectrum utilization of the system in high-speed mobile scenarios. For example, if RF=1, BR-OFDMA will degenerate into the traditional OFDMA. Generally, the larger the RF, the more obvious the diversity gain effect, and the more obvious the effect of overcoming the fast decay. Therefore, in practical applications, it is necessary to comprehensively consider the above various factors to properly determine the value of the RF. In this embodiment, the RF may be determined according to the size of the channel change factor. For example, the larger the channel variation factor is, the more severe the current channel state changes, and the larger the value of the RF.

3) block repeating pattern

The mapping of block repetitions in the time-frequency domain can have multiple modes, such as time domain block repetition, frequency domain block repetition, time-frequency two-dimensional block repetition, continuous resource block repetition, and distributed resource block repetition. Different mapping methods have different effects on system performance. For example, time-frequency block repetition is advantageous for obtaining time-domain diversity gain, so it is suitable for high-speed moving scenes, but it is not conducive to obtaining frequency-domain diversity gain. Frequency-domain block repetition is beneficial for obtaining frequency-domain diversity gain, so it is suitable for multi-path expansion comparison. Large scenes; The impact of time-frequency two-dimensional block repetition on system performance is a compromise between the two. However, distributed resource block repetition can obtain better diversity gain, but it will increase the overhead indicated by the resource allocation instruction. It can be seen that each of the above repeated mapping modes has its advantages and disadvantages. Do not apply to different situations.

In the embodiment of the present invention, several typical block repetition patterns may be preset, and the block repetition pattern used in the UE communication may be controlled according to the following two control modes: one is a short period control mode, according to a channel change The size of the factor is selected, that is, whether the channel change factor is greater than a preset threshold, and if so, a block repeat pattern suitable for a high-speed moving scene in a preset block repeat pattern, such as a time domain block repeat pattern, is selected. Otherwise, select a block repeat pattern suitable for non-high-speed moving scenes in a preset block repeat pattern, such as a frequency domain block repeat pattern or a time-frequency two-dimensional block repeat pattern. The other is the long-cycle control mode. The block repeat pattern is adjusted according to the calculated block error rate. If the block error rate is large, the currently used block repeat pattern is adjusted to the opposite scene repeat pattern. For example, if the block repetition pattern currently used is a time domain block repetition pattern, if the calculated block error rate is greater than a preset threshold, it indicates that the currently used block repetition pattern is not applicable to the current channel state. So you can adjust it to a frequency domain block repeat pattern. The statistical method of the block error rate is prior art and will not be mentioned.

In the embodiment of the present invention, in the process of transmitting signals by using the BR-OFDMA method, in order to further improve the spectrum utilization rate of the system, the AMC technology can also be used to adjust the signal coding modulation mode during signal transmission. It is well known to those skilled in the art that in the implementation of the AMC technology, the selection of the MCS is a very critical step, and the selection of the MCS is usually based on the signal-to-noise ratio in the channel state information, so that the signal-to-noise ratio is obtained. problem.

The signal-to-noise ratio experienced by the BR-OFDMA is different from that of the conventional OFDM. In the embodiment of the present invention, two ways of obtaining the signal-to-noise ratio in the BR-OFDMA are proposed: one is to measure the signal to noise ratio (SNR, Signal to Noise) Ratio data, the average value of the measured SNR data is calculated in a preset time window, and the MCS is determined according to the average value; the other is to calculate the average value of the user's signal to interference and noise ratio, The average determines the MCS. For the first mode, the SNR data is measured in the same manner as in the prior art, and the average value of the calculated SNR data can better reflect the signal to noise ratio level of the channel where the UE is located. However, two aspects need to be corrected: On the one hand, although the multi-user joint detection algorithm in BR-OFDMA can largely eliminate the interference between multiple users, due to the nonlinearity of the channel, the interference between users will also There is a partial residual. Therefore, the basic MCS needs to be retracted according to the size of the RF. Generally, the larger the RF, the less the backoff. On the other hand, the larger the signal-to-noise ratio change will affect the system performance. The MCS needs to be rolled back according to the variance of the SNR. Generally, the smaller the variance of the SNR, the less the backoff.

For the second way:

The system matrix of the nth symbol in the multi-user joint detection algorithm of BR-OFDMA is: -

Where c) is the ith block repetition code of user k, which is the ith channel response of user k.

Assuming that the noise sequence is independent of each other (diagonal matrix), a stationary noise sequence (the variance is also equal to the elements on the diagonal) (white noise), then the covariance matrix of the noise sequence

. Where I is a unit matrix and _σ ² is a diagonal matrix.

The correlation matrix t„= A: ^T A _n . Then for the SINR of user k, it can be defined as = ^ ₇ .

The mean value of X _n ^k can better reflect the BR-OFDMA medium-to-noise ratio, so it can be used as a reference for selecting MCS, that is, MCS is selected according to the signal to interference and noise ratio. Step 103: Perform signal transmission by using the OFDMA method, and then end the process.

In the process of transmitting signals by OFDMA, adaptive schemes such as AMC and HARQ can be further adopted. The specific implementation is the same as in the prior art, and will not be described again.

Based on the above method, a broadband wireless mobile communication system and apparatus are simultaneously proposed in the embodiments of the present invention.

2 is a schematic structural diagram of an embodiment of a broadband wireless mobile communication system according to the present invention. As shown in FIG. 2, the system includes: a base station 202 and a UE 201:

The UE 201 is configured to analyze channel state information, calculate a channel change factor, and send it to the base station 202;

The base station 202 is configured to determine, according to the received channel change factor, whether the current channel state changes drastically. If yes, the BR-OFDMA mode is used for signal transmission; if not, the OFDMA mode is used for signal transmission.

The UE 201 includes: a computing unit 2011 and a reporting unit 2012;

The calculating unit 2011 is configured to: in the preset time window, measure the SINR sequence, α, α, α, ..., α _Ν , the measurement interval is seconds; calculate the change rate sequence of the SINR sequence β ₀ , β,, β ₂ , ... Α - where ^ = ^{l M} ~ ' ^l , i = o, i, -, Nv, and calculate the average rate of change of the SINR τ sequence = ∑Α ; on the "3⁄4 unit 2012, used to report the average rate of change of the SINR to the base station 202;

Alternatively, the calculating unit 2011 is configured to calculate a pilot inter-correlation coefficient y = E(H _m , H: _{+ k} ), where H _m , _k , H: ₊₁ , _k are obtained by channel estimation, respectively representing the mth And the pilot channel response of the kth subcarrier on the m+1th OFDM symbol, E ( ) indicates the expected value; the reporting unit 2012 is configured to report the correlation coefficient y between the pilots to the base station 202; Alternatively, the calculating unit 2011 is configured to calculate an average rate of change of the SINR sequence within a preset time window, and calculate a correlation coefficient γ between the pilots Ε (Ε _Μ , υ , where

^ , ₊₁ , _Α obtained by channel estimation, respectively representing the pilot channel response of the kth subcarrier on the mth and m+1th OFDM symbols, E ( ) indicating the expected value; reporting unit 2012, for using the SINR The average rate of change and the correlation coefficient y between pilots are reported to the base station 202.

The base station 202 specifically includes: a determining unit 2021 and a transmitting unit 2022;

The determining unit 2021 is configured to determine whether an average change rate of the SINR sequence, or a correlation coefficient between pilots or an average rate of change of the SINR sequence and a correlation coefficient y between pilots is greater than a preset threshold, and if yes, determine The current channel state changes drastically;

The transmitting unit 2022 is configured to perform signal transmission by using a BR-OFDMA mode when the judgment result of the determining unit 2021 is a drastic change of the current channel state; otherwise, the OFDMA mode is used for signal transmission.

The transmitting unit 2022 includes: a first transmitting unit 2022A and a second transmitting unit 2022B; a first transmitting unit 2022A for performing signal transmission by using a BR-OFDMA method; and a second transmitting unit 2022B for performing signals by using an OFDMA method. Transmitting; wherein, the first transmitting unit 2022A further includes: a grouping subunit 20221, a determining subunit 20222, and a transmitting subunit 20223;

a packet subunit 20221, configured to perform grouping according to a channel state of the UE, and group UEs having similar channel states into the same group;

The determining subunit 20222 is configured to determine a block repetition factor and a block repetition pattern corresponding to each group of UEs, and the UEs in each group use the same block repetition factor and the block repetition pattern;

The transmitting subunit 20223 is configured to perform signal transmission according to the determined block repetition factor and the block repetition pattern.

FIG. 3 is a schematic structural diagram of an embodiment of a broadband wireless mobile communication device according to the present invention. Such as As shown in FIG. 3, the device includes: a calculating unit 301, a determining unit 302, and a transmitting unit 303. The calculating unit 301 is configured to calculate a channel change factor according to the acquired channel state information.

The determining unit 302 is configured to determine, according to the calculated channel change factor, whether the current channel state changes drastically;

The transmitting unit 303 is configured to perform signal transmission by using a BR-OFDMA mode when the judgment result of the determining unit 302 is a drastic change of the current channel state; otherwise, the OFDMA mode is used for signal transmission.

The computing unit 301 further includes: a receiving subunit 3011 and a computing subunit 3012;

The receiving sub-unit 3011 is configured to receive, in a preset time window, the measured SINR sequence measurement interval is seconds; and the calculating sub-unit 3012 is configured to calculate a change rate sequence of the SINR sequence, ... _Ν ― ― , where,

^= ^l ' ⁺¹ ~ ' ^l , i = 0,l,--,Nl; and calculate the average rate of change τ of the SINR sequence

Set the threshold, and if so, determine the current channel state to change drastically.

Alternatively, the receiving subunit 3011 is configured to receive the pilot channel response H _m , _k , H: ₊₁ , _k , H _m , _k , H: ₊₁ , _k obtained by the UE through channel estimation, respectively, indicating mth and mth, respectively. a pilot channel response of the kth subcarrier on the +1 OFDM symbol; a calculation subunit 3012 for calculating a correlation coefficient between pilots according to the received, 7=E(H _m , H: _{+ k} ), E( ) The determination unit 302 determines whether the reciprocal of the correlation coefficient y between the pilots is greater than a preset threshold, and if so, determines that the current channel state changes drastically.

Alternatively, the receiving subunit 3011 is configured to receive the UE in a preset time window, and measure The SINR sequence obtained and reported... The measurement interval is seconds, and the pilot channel response obtained by the UE through channel estimation, H _m , ₊₁ respectively represent the guide of the kth subcarrier on the mth and m+1th OFDM symbols Frequency channel response;

The calculating subunit 3012 is configured to calculate a rate of change sequence β of the SINR sequence according to the received SINR sequence. υ,......,β _Ν — _γ , where

^ = ^l ' ⁺¹ ~ ' ^l , i = 0,l,--,Nl , and calculate the average rate of change of the SINR sequence τ β = ^ΥΛ·, and, based on the received correlation coefficient between the pilots,

Y = E(H _mk H _+lk ), E ( ) represents an expected value; the determining unit 302 determines whether the combined result of the average rate of change of the SINR sequence and the correlation coefficient y between pilots is greater than a preset threshold, and if so, Determine the current channel state to make drastic changes.

The transmitting unit 303 includes: a first transmitting unit 303A and a second transmitting unit 303B. The first transmitting unit 303A is configured to perform signal transmission by using a BR-OFDMA method, and the second transmitting unit 303B is configured to perform signals by using an OFDMA method. Launch

The first transmitting unit 303A further includes: a grouping subunit 3031, a determining subunit 3032, and a transmitting subunit 3033;

a packet subunit 3031, configured to perform grouping according to a channel state of the UE, and group UEs having similar channel states into the same group;

The determining subunit 3032 is configured to determine a block repetition factor and a block repetition pattern corresponding to each group of UEs, and the UEs in each group use the same block repetition factor and the block repetition pattern;

The transmitting subunit 3033 is configured to perform signal transmission according to the determined block repetition factor and the block repetition pattern.

In addition, the first transmitting unit 303A may further include: an adjusting subunit 3034, configured to encode and modulate a signal during signal transmission by using an adaptive coding and modulation method. Make adjustments.

It should be noted that, in order to avoid the illustration being too complicated and unclear, neither the first transmitting unit nor the second transmitting unit is shown in Figs. 2 and 3. For the specific working process of the system and device embodiment shown in FIG. 2 and FIG. 3, please refer to the corresponding description in the method embodiment, and the description is not repeated.

In summary, with the technical solution of the present invention, link adaptive scheduling can be performed by using different strategies according to different application scenarios. For non-high-speed mobile UEs, UEs that are moving at low and medium speeds can use traditional OFDMA for signal transmission, and can further combine AMC and HARQ technologies to improve system throughput. For high-speed mobile UEs, BR can be used. - The OFDMA method performs signal transmission and can be further combined with AMC technology to improve the spectrum utilization of the system.

The above is only the preferred embodiment of the present invention, and is not intended to limit the present invention. Any modifications, equivalents, improvements, etc., which are made within the spirit and principles of the present invention, should be included in the present invention. Within the scope of protection.

Claims

Claim

A link adaptation method for a broadband wireless mobile communication system, the method comprising:

Performing analysis on channel state information, calculating a channel change factor, and determining whether the current channel state changes drastically according to the channel change factor;

2. The method according to claim 1, wherein the channel change factor is an average rate of change of a signal to interference and noise ratio sequence;

The calculating the channel change factor comprises: calculating an average rate of change of the dry signal to noise ratio sequence within a preset time window;

Determining whether the current channel state is drastically changed according to the channel change factor comprises: determining whether the average rate of change of the signal to interference and noise ratio sequence is greater than a preset threshold, and if so, determining that the current channel state is drastically changed.

3. The method according to claim 1, wherein the channel change factor is a reciprocal of a correlation coefficient between pilots;

The calculating the channel change factor comprises: calculating a correlation coefficient between pilots, r=E(H _m , _H : _+hk ), wherein the H _m , H ^ are obtained by channel estimation, respectively representing the mth sum a pilot channel response of the kth subcarrier on the m+1th orthogonal frequency division multiplexing symbol, where the E( ) indicates an expected value;

Determining whether the current channel state is drastically changed according to the channel change factor comprises: determining whether a reciprocal of the correlation coefficient y between the pilots is greater than a preset threshold, and if so, determining that the current channel state is drastically changed.

4. The method according to claim 1, wherein the channel change factor a combination of an average rate of change of the signal to interference ratio sequence and a reciprocal of the inter-pilot correlation coefficient; the calculating the channel variation factor comprises: calculating an average rate of change of the signal to interference and noise ratio sequence within a preset time window; Calculate the correlation coefficient between pilots

_{7 = Ε (Η Μ Η:} +1), wherein the H _M, H: ₊₁ obtained by channel estimation, represent the first and the m + 1-m orthogonal frequency division multiplexing symbols k-th subcarriers Pilot channel response, said E ( ) indicating an expected value;

Determining whether the current channel state is drastically changed according to the channel change factor comprises: determining whether a result of combining the average rate of change of the signal to interference and noise ratio sequence and the reciprocal of the inter-pilot correlation coefficient y is greater than a preset The threshold value, if yes, determines the current channel state to change drastically.

The method according to claim 2 or 4, wherein the average rate of change of the statistical signal to interference ratio sequence comprises:

Measuring, in the preset time window, a signal to interference and noise ratio sequence measurement interval of seconds;

Calculating a rate of change sequence A, A, A, ..., β of the signal to interference and noise ratio sequence, wherein

^= ^{l M} ~ ' ^l , i = 0,l,-,NV,

τ Calculates the average rate of change of the signal to interference ratio sequence = ∑ A.

The method according to claim 2, 3 or 4, wherein the performing signal transmission by using the block repeated orthogonal frequency division multiple access method comprises:

Grouping according to the channel state of the user terminal, and classifying user terminals having similar channel states into the same group;

Determining a block repetition factor and a block repetition pattern corresponding to each group of user terminals, and the user terminals in each group use the same block repetition factor and block repetition pattern; Signal transmission is performed according to the determined block repetition factor and the block repetition pattern.

The method according to claim 6, wherein the grouping according to the channel state of the user terminal comprises:

Counting a channel change factor and a path loss value corresponding to each user terminal; sorting each user terminal according to the path loss value to find a user terminal having a similar path loss value;

The user terminals having similar path loss values are sorted according to the channel change factor size, and user terminals having similar path loss values and channel change factors are found, and are grouped into one group.

The method according to claim 6, wherein the determining a block repetition factor corresponding to each group of user terminals comprises:

The block repetition factor is determined according to a channel change factor corresponding to each group of user terminals, and the larger the channel variation factor, the larger the determined block repetition factor.

The method according to claim 6, wherein the determining a block repetition pattern corresponding to each group of user terminals comprises:

Presetting one or more block repetition patterns respectively applicable to different scenes; determining whether a channel change factor corresponding to each group of user terminals is greater than a preset threshold, and if yes, selecting the preset block repetition pattern for high speed Moving a block repeating pattern of the scene; otherwise, selecting a block repeating pattern suitable for the non-high speed moving scene in the preset block repeating pattern;

Or, preset one or more block repetition patterns respectively applicable to different scenes; adjust the currently used block repetition pattern according to the calculated error block rate, and if the error block rate is greater than a preset threshold, the current use is The block repeat pattern is adjusted to repeat the pattern for the opposite scene of the applicable scene.

The method according to claim 1, wherein the performing the signal transmission process by using the block repetition orthogonal frequency division multiple access method further comprises: adopting adaptive code modulation The method adjusts the signal coding modulation mode during signal transmission.

The method according to claim 10, wherein the adjusting the signal coding and modulation mode in the signal transmission process by using the adaptive code modulation mode comprises: acquiring a signal to noise ratio of a channel where the user terminal is located, according to the method The signal to noise ratio determines a modulation coding scheme required in adaptive code modulation;

The obtaining a signal to noise ratio, and determining a modulation coding scheme required for adaptive code modulation according to the signal to noise ratio, includes:

Measuring a signal-to-noise ratio, calculating an average value of the measured signal-to-noise ratio in a predetermined time window, and determining a modulation and coding scheme required for adaptive code modulation according to the average value; or The average of the signal to interference and noise ratio of the channel on which the user terminal is located determines the modulation and coding scheme required in the adaptive code modulation based on the average value.

12. A broadband wireless mobile communication system, the system comprising: a base station and a user terminal;

The user terminal is configured to analyze channel state information, calculate a channel change factor, and report the channel change factor to the base station;

The system according to claim 12, wherein the user terminal comprises: a calculating unit and a reporting unit;

The calculating unit is configured to measure a signal to interference and noise ratio sequence "., , . . . , α _Ν in a preset time window, and the measurement interval is seconds; and calculate a rate of change sequence of the signal to interference and noise ratio sequence Α, Α, Α, ... A—i, where A = '"' + "'' XU- Nl ; and the average rate of change of the τ signal dry noise ratio sequence is calculated = 丄∑ ; For the letter to dry The average rate of change β of the noise ratio sequence is reported to the base station;

Alternatively, the calculating unit is configured to calculate a pilot inter-correlation coefficient ^, the r=E(H _m , K _{+ )} , where the H _m , H: _{+1 are} obtained by channel estimation, respectively, representing the mth a pilot channel response of the kth subcarrier on the m+1th orthogonal frequency division multiplexing symbol, the E ( ) indicating an expected value; the reporting unit, configured to report the correlation coefficient y between the pilots Giving the base station;

Or the calculating unit, configured to: in a preset time window, calculate an average rate of change of the signal to interference and noise ratio sequence and calculate a correlation coefficient between the pilots, where the reporting unit is configured to use the signal to interference and noise ratio sequence The average rate of change β and the inter-pilot correlation coefficient y are reported to the base station.

The system according to claim 13, wherein the base station comprises: a determining unit and a transmitting unit;

The determining unit is configured to determine an average change rate of the signal to interference and noise ratio sequence, or the inter-pilot correlation coefficient y, or an average rate of change β of the signal to interference and noise ratio sequence, and the pilot Whether the combined result of the correlation coefficient y is greater than a preset threshold, and if so, determining that the current channel state is drastically changed;

The system according to claim 14, wherein the transmitting unit comprises: a first transmitting unit and a second transmitting unit; the first transmitting unit, configured to use block repetition orthogonal frequency division multiple access The method is configured to perform signal transmission, where the second transmitting unit is configured to perform signal transmission by using an orthogonal frequency division multiple access method, where the first transmitting unit further includes: a grouping subunit, a determining subunit, and a transmitting subunit; The grouping subunit is configured to group according to a channel state of the user terminal, and divide the user terminals having similar channel states into the same group;

The determining subunit is configured to determine a block repetition factor and a block repetition pattern corresponding to each group of user terminals, and the user terminals in each group use the same block repetition factor and a block repetition pattern; The determined block repetition factor and the block repetition pattern are used for signal transmission.

A broadband wireless mobile communication device, the device comprising: a calculation unit, a determination unit, and a transmission unit;

The device according to claim 16, wherein the calculating unit comprises: a receiving subunit and a calculating subunit;

The receiving subunit is configured to receive a signal to interference and noise ratio sequence ^, , , . . . , α _Ν measured and reported by the user terminal in a preset time window, and the measurement interval is seconds;

The calculation subunit is configured to calculate a change rate sequence βΜ, . . . , β^ of the signal to interference and noise ratio sequence, wherein the Α = ^Ι ' ⁺¹ — "''' OU - 1 ; The average rate of change of the τ dry noise ratio sequence = β _ι ; the determining unit determines whether the average rate of change of the signal to interference and noise ratio sequence is greater than a preset threshold, and if so, determines that the current channel state changes drastically.

The receiving subunit is configured to receive a pilot channel response H _m , _k , H: _+u obtained by the user terminal through channel estimation, _where the m and m+1th orthogonal frequency division multiplexing symbols are respectively represented a pilot channel response of the kth subcarrier;

The calculating sub-unit, according to the H _m, H; _{+ u} guide inter-frequency correlation coefficient calculating y, the fans _{_{_{r = E (H m, k}}} H: +1, k of the E () indicates finding a desired value ;

The determining unit determines whether the reciprocal of the inter-pilot correlation coefficient ^ is greater than a preset threshold, and if so, determines that the current channel state changes drastically.

The receiving subunit is configured to receive a signal to interference and noise ratio sequence ^, , , ..., α _Ν measured and reported by the user terminal in a preset time window, the measurement interval is seconds, and the user The pilot channel response H _m , _k , H: ₊₁ , _k obtained by the channel estimation by the terminal, and the H represents the pilot of the kth subcarrier on the mth and m+1th orthogonal frequency division multiplexing symbols, respectively. a channel response; the calculating subunit, configured to calculate a sequence of rate of change of the signal to interference and noise ratio sequence according to the signal to interference and noise ratio sequence "., , , . _Ν ^ , where, the

Α· = ^Ι ' ⁺¹ — "'Άο,υ- 1 , and calculate the average rate of change τ w of the signal to interference and noise ratio sequence to calculate the correlation coefficient between pilots

_Y = E(H _m , _k H: _+u ), the Ε ( ) represents the expected value;

The determining unit determines whether the combined result of the average rate of change of the signal to interference and noise ratio sequence and the inter-pilot correlation coefficient y is greater than a preset threshold, and if so, determines that the current channel state changes drastically.

The apparatus according to claim 16, wherein the transmitting unit comprises: a first transmitting unit and a second transmitting unit; the first transmitting unit, configured to use block repetition orthogonal frequency division multiple access The method is configured to perform signal transmission, where the second transmitting unit is configured to perform signal transmission by using an orthogonal frequency division multiple access method, where the first transmitting unit further includes: a grouping subunit, a determining subunit, and a transmitting subunit;

The grouping subunit is configured to group according to a channel state of the user terminal, and divide the user terminals having similar channel states into the same group;

The apparatus according to claim 20, wherein the first transmitting unit further comprises: an adjusting subunit, configured to adjust a signal encoding and modulation mode in the signal transmitting process by using an adaptive coded modulation mode.