CN102457321B - Method for predicting down link SINR (Signal-to-Interference and Noise Ratio) in wireless communication system, equipment and base station - Google Patents

Abstract

The invention provides a method for predicting down link SINR (Signal-to-Interference and Noise Ratio) in wireless communication system, equipment and base station. The equipment comprises an MSE (Mean-Square Error) estimator for computing an MSE of an estimated channel of an SRS (Sounding Reference Signal) relative to the channel estimation of an actual channel according to the SINR of the SRS transmitted by UE, and outputting the MSE estimated by the channel to a synthesizer, a transmission delay counter for counting transmission delay between the time for the UE to transmit the SRS and the time for transmitting the down link of the UE, and outputting the transmission delay to the synthesizer, and the synthesizer for generating a predicted SINR according to the MSE estimated by the channel and received by the MSE estimator, the transmission delay received by the transmission delay counter, and down link CQI (Channel Quality Indication) feed back by the UE, and wave beam forming weight of an transmission antenna.

Description

Down link SINR Forecasting Methodology, equipment and base station in wireless communication system

Technical field

The present invention relates to down link signal interference-to-noise ratio (SINR) Forecasting Methodology and equipment and base station in a kind of multi-aerial radio communication system using wave beam forming, can get off to predict better the actual SINR for beamforming transmission in the situation of the impact of considering mean square error (MSE) and transmission delay (TD), and SINR based on predicted provides higher system performance gain.

Background technology

Wave beam forming is multiple antenna communication, for example very important technology in LTE TDD (Long Term Evolution-time division duplex) communication system.This technology can improve throughput of system and the area of coverage.The SRS (detection reference signal) of eNB (base station) based on sending from UE (subscriber equipment) produces beam forming weight, then, in the time this UE being scheduled to transmission, these weights is applied to downlink transmission.

Beam forming weight need to be carried out self adaptation adjusting according to channel condition information, therefore the precision height correlation of the performance of wave beam forming and channel estimating.If these weights are mated with the instantaneous channel status in when transmitting, system performance gain will be larger.Otherwise system performance gain is by poorer than desired.

Exist following two principal elements can affect the precision of the channel estimating of SRS:

1) MSE with respect to the channel estimating between actual channel according to the estimation channel of SRS.Conventionally, the lower SINR (Signal Interference and Noise Ratio) on SRS will cause larger MSE.

2) UE transmits the TD (transmission delay) between the time of SRS and the time of the DL of this UE (down link) transmission generation.Because become when channel is, if the time interval between SRS transmission and DL transmission is oversize, beam forming weight is by expired and lose effectiveness.

Summary of the invention

The above-mentioned defect of considering prior art has proposed the present invention.Therefore, the object of the invention is to propose down link SINR Forecasting Methodology and equipment and the base station in a kind of multi-aerial radio communication system using wave beam forming, can in the case of considering the impact of MSE and TD, predict better the actual SINR for beamforming transmission, and SINR based on predicted provides higher system performance gain.

To achieve these goals, according to the present invention, down link signal interference-to-noise ratio SINR predict device in a kind of multi-aerial radio communication system using wave beam forming has been proposed, comprise: mean square error estimator, according to the SINR of the detection reference signal SRS sending from user equipment (UE), calculate the estimation channel of SRS with respect to the mean square error MSE of the channel estimating of actual channel, and the MSE of described channel estimating is outputed to synthesizer; Transmission delay counter, the transmission delay between the moment to UE transmission SRS and the moment that the down link of this UE is transmitted is counted, and described transmission delay is outputed to synthesizer; And synthesizer, the downlink channel quality instruction CQI of the described transmission delay receiving according to the MSE of the described channel estimating receiving from mean square error estimator, from transmission delay counter, UE feedback and the beam forming weight of transmitting antenna produce the SINR of prediction.

Preferably, the SINR of described prediction is for downlink wireless control, and described downlink wireless control comprises user's scheduling, resource distribution, link adaptation and the transmission policy management of media access control MAC layer.

Preferably, the down link CQI of described UE feedback comprises the SINR under non-beamforming transmission strategy.

Preferably, the beam forming weight of described transmitting antenna is to utilize the detection reference signal SRS sending from UE to carry out channel response to estimate to produce.

Preferably, the SINR of described SRS obtains in physical layer.

Preferably, described multi-aerial radio communication system is long-term advancing time division duplex LTE TDD communication system.

According to the present invention, the base station in a kind of multi-aerial radio communication system using wave beam forming has also been proposed, comprising: above-mentioned down link signal interference-to-noise ratio SINR predict device.

Preferably, described base station also comprises: user's scheduler, resource allocator, link adaptation device and transmission policy manager, be respectively used to according to the SINR of the prediction receiving from down link SINR predict device, carry out user's scheduling, resource distribution, link adaptation and the transmission policy management of media access control MAC layer.

Preferably, described base station also comprises: SRS channel estimator, for obtaining the estimation channel response of the detection reference signal SRS sending from UE and the SINR of described SRS, to described estimation channel response is outputed to beam forming weight generator, and the SINR of described SRS is outputed to described down link SINR predict device; And beam forming weight generator, for producing beam forming weight according to the estimation channel response of the SRS signal sending from SRS channel estimator, and described beam forming weight is outputed to described down link SINR predict device.

In addition, to achieve these goals, according to the present invention, down link signal interference-to-noise ratio SINR Forecasting Methodology in a kind of multi-aerial radio communication system using wave beam forming has also been proposed, comprise: according to the SINR of the detection reference signal SRS sending from user equipment (UE), calculate the estimation channel of SRS with respect to the mean square error MSE of the channel estimating of actual channel; Transmission delay between moment to UE transmission SRS and the moment that the down link of this UE is transmitted is counted; And produce the SINR of prediction according to the downlink channel quality instruction CQI of the MSE of described channel estimating, described transmission delay, UE feedback and the beam forming weight of transmitting antenna.

Brief description of the drawings

By reference to below in conjunction with accompanying drawing to adopted detailed description of preferred embodiment, above-mentioned purpose of the present invention, advantage and feature will become apparent, wherein:

Fig. 1 shows according to the block diagram of the structure of the down link SINR predict device of the embodiment of the present invention;

Fig. 2 shows the block diagram comprising according to the structure of the base station of the down link SINR predict device of the embodiment of the present invention;

Fig. 3 shows according to the flow chart of the operation of the down link SINR Forecasting Methodology of the embodiment of the present invention; And

Fig. 4 shows the emulation comparison diagram that utilizes the system throughput flow gain of the present invention of SINR prediction and do not utilize the system throughput flow gain of the prior art of SINR prediction.

Embodiment

Current, in order to solve the problem of precision of channel estimating of SRS, following two kinds of methods are proposed:

Method 1) MSE (or SINR of SRS) that estimates to layer 2 (MAC layer, that is, media access control layer) reporting channel of layer 1 (physical layer).Layer 2 compares the value of the MSE of the channel estimating of report and threshold value.If the MSE value of report, higher than threshold value, switches to the transmission policy of corresponding UE TxDiv (transmission diversity).

Method 2) increase SRS transmission density to reduce TD.For example, if UE in beamforming transmission pattern, the SRS transmission cycle of this UE is configured to 2ms, 5ms or 10ms.Once SRS resource cannot meet this requirement, the transmission policy of corresponding UE is switched to TxDiv.

For method 1, be difficult to suitable threshold value is set, because the MSE of channel estimating is not only depended in the gain of wave beam forming, but also depend on instantaneous channel condition information.All UE with larger MSE are switched to TxDiv by not good scheme at present.

For method 2, can spend larger expense and configure the little SRS cycle for all wave beam forming UE.Secondly, the larger SRS cycle not necessarily can cause larger TD.Possibly, Downlink scheduler is chosen in this UE of scheduling in the UE transmission SRS signal short period afterwards and also can obtains good beam forming gain.Allow all UE with the larger SRS cycle only use TxDiv can significantly reduce systematic function.

The basic thought of down link SINR predict device of the present invention is to predict the actual SINR for beamforming transmission according to MSE and TD.Therefore, the SINR of this prediction has considered the impact of channel estimation errors and transmission delay well.The SINR of this prediction is made up of two parts: correct Prediction part and error part.Correct Prediction part is enjoyed beam forming gain, and error part cannot obtain any beam forming gain, this SINR situation in more can realistic transmission.The SINR of this prediction can be for downlink wireless control, and this downlink wireless control comprises user's scheduling, resource distribution, link adaptation and the transmission policy management of media access control MAC layer.The SINR of this prediction reduces along with the increase of MSE and TD.Lower prediction SINR causes the lower probability that is scheduled, conservative MCS (Modulation and Coding Scheme) to select and the higher probability that is switched to TxDiv, and this is just in time the wireless link control program that is applicable to the UE with high channel estimation MSE and larger TD.Therefore, need to just not tackle for the special processing of wave beam forming the impact of MSE and these two kinds of unfavorable factors of TD.In addition, can use known user's scheduling, resource distribution, link adaptation and transmission policy management (for example transmission is switched) SINR of algorithm based on predicted that higher system performance gain is provided.

The preferred embodiments of the present invention are described below with reference to the accompanying drawings.

Fig. 1 shows according to the block diagram of the structure of the down link SINR predict device of the embodiment of the present invention.

As shown in Figure 1, down link SINR predict device according to the present invention comprises MSE estimator 101, transmission delay counter 103 and synthesizer 105.MSE estimator 101 for example, according to the SINR (obtaining UL (up) SRS SINR from physical layer) of the SRS sending from user equipment (UE), calculate the estimation channel of SRS with respect to the MSE of the channel estimating of actual channel, and the MSE of this channel estimating is outputed to synthesizer 105.Transmission delay counter 103 to the transmission delay between the UE transmission moment of SRS and the moment of the downlink transmission of described UE generation (, be transferred to current transmission intercal elapsed time from SRS) count, and this transmission delay is outputed to synthesizer 105.Synthesizer 105 produces the SINR of prediction according to the MSE of the described channel estimating receiving from MSE estimator 101, the described transmission delay receiving from transmission delay counter 103, the downlink channel quality instruction (CQI) of UE feedback and the beam forming weight of transmitting antenna.

As mentioned above, according to the present invention, synthesizer 103 can be considered MSE and TD, and the two predicts the actual SINR for beamforming transmission better on the impact of beamforming transmission.Based on predicted SINR, the present invention can provide higher system performance gain.

Fig. 2 shows the block diagram comprising according to the structure of the base station of the down link SINR predict device of the embodiment of the present invention.

As shown in Figure 2, eNB according to the present invention comprises SRS channel estimator 201, beam forming weight generator 203, above-mentioned down link SINR predict device 205, user's scheduler 207, resource allocator 209, link adaptation device 211 and transmission policy manager 213.

SRS channel estimator 201 obtains the estimation channel response of the SRS sending from UE and the SINR of this SRS, to this estimation channel response is outputed to beam forming weight generator 203, and this SINR is outputed to this down link SINR predict device 205.Beam forming weight generator 203 produces beam forming weight according to the estimation channel response of the SRS signal sending from SRS channel estimator 201, and described beam forming weight is outputed to this down link SINR predict device 205.User's scheduler 207, resource allocator 209, link adaptation device 211 and transmission policy manager 213, respectively according to the SINR of the prediction receiving from down link SINR predict device 205, are carried out user's scheduling, resource distribution, link adaptation and the transmission policy management of MAC layer.

In addition, although also not shown in Fig. 2, this eNB can also comprise for providing the device of the down link CQI being fed back by UE to this down link SINR predict device 205, to produce as mentioned above the SINR of prediction.

The performed operation separately of this down link SINR predict device included MSE estimator 101, transmission delay counter 103 and synthesizer 105 will be described in detail below.

As mentioned above, MSE estimator 101 is for obtaining the estimation channel of SRS with respect to the MSE of the channel estimating of actual channel.Substantially, this MSE estimator 101 obtains this MSE by UL SRS SINR (being estimated by physical layer).

Suppose

be on time t in subband k UE antenna to the channel of the s transmitting antenna of base station;

be on time t in subband k UE antenna to the estimation channel response of the s transmitting antenna of base station;

Channel estimation errors is:

$Q_k^s\left(t\right)=H_k^s\left(t\right)-{\hat{H}}_k^s\left(t\right)$

Here can think, be independent of

in addition,, owing to being height correlation for the antenna of wave beam forming, can derive (for incoherent antenna, can be by this error being averaged to calculate on all antennas

${\mathrm{\δ}}_k^2\left(t\right)=E\left\{{\left(Q_k^s\left(t\right)\right)}^2\right\},$ For s=1...S.

Wherein, E{} is mathematic expectaion computing.Conventionally

depend on the current SINR of adopted channel estimation method and received SRS signal.If adopt MMSE (least mean-square error) estimator to carry out channel estimating, corresponding error can be write:

${\mathrm{\δ}}_k^2=\frac{E\left\{{\left(H_k^s\left(t\right)\right)}^2\right\}}{E\left\{{\left(H_k^s\left(t\right)\right)}^2\right\}{\mathrm{SINR}}_k+1},$

$=\frac{{\mathrm{\σ}}_{H,k}^2}{{\mathrm{\σ}}_{H,k}^2{\mathrm{SINR}}_k+1}$

Wherein

be in subband k UE antenna to the UL SRSSINR of the s antenna of base station.

can measure and on average obtain when long, and for s=1...S.,

equal

Thus, MSE can be defined as:

${\mathrm{\γ}}_k=\frac{{\mathrm{\δ}}_k^2}{{\mathrm{\σ}}_{H,k}^2},$

, the ratio of evaluated error power and channel power.

As mentioned above, transmission delay counter 103 be used for calculate to UE transmit SRS time and be addressed to described UE downlink transmission occur time between transmission delay, for example, the delay between probe transmission and PDSCH (physical down link sharing channel) transmission intercal.

Suppose it is the moment of transmitting the up-to-date SRS of object UE on subband k;

that the moment for the downlink transmission of this UE occurs in supposition on subband k.

This transmission delay TD can be estimated as:

${\mathrm{\τ}}_k=t_k^{\mathrm{DL}\_\mathrm{TX}}-t_k^{\mathrm{SRS}}$

In LTE (Long Term Evolution) communication system, T _kcan measure according to the quantity of subframe.

As mentioned above, synthesizer 105 produces the SINR of prediction according to the beam forming weight of MSE, the described transmission delay receiving from transmission delay counter 103, the down link CQI being fed back by UE and the transmitting antenna of the described channel estimating receiving from MSE estimator 101.

Particularly, at t+ τ _ktime channel response can be modeled as:

$H_k^s(t+{\mathrm{\τ}}_k)={\mathrm{\ρ}}_k{H}_k^s\left(t\right)+{\mathrm{\η}}^s(t+{\mathrm{\τ}}_k)$

Wherein, η ^s(t+ τ) is to be distributed as

plural Gaussian random variable, and for rayleigh fading channel, ρ _kcan be calculated as ρ=J ₀(2 π f _dτ _k) (f _ddoppler frequency shift).It can further be written as:

$H_k^s(t_k+{\mathrm{\τ}}_k)={\mathrm{\ρ}}_k{H}_k^s\left(t_k\right)+{\mathrm{\η}}^s(t_k+{\mathrm{\τ}}_k)$

$={\mathrm{\ρ}}_k{\hat{H}}_k^s\left(t_k\right)+{\mathrm{\ρ}}_k{Q}_k^s\left(t_k\right)+{\mathrm{\η}}^s(t_k+{\mathrm{\τ}}_k)$

Suppose

be the beam forming weight of respective antenna s in subband k, it transmits to produce according to the SRS in time interval t.So the SINR of corresponding PDSCH is predicted to be:

${\mathrm{\ϵ}}_k=E\left\{\frac{1}{S}{\left|\underset{s=1}{\overset{S}{\mathrm{\Σ}}}{W}_k^s\left(t\right)({\mathrm{\ρ}}_k{\hat{H}}_k^s\left(t\right)+{\mathrm{\ρ}}_k{Q}_k^s\left(t\right)+{\mathrm{\η}}^s(t+{\mathrm{\τ}}_k))\right|}^2\right\}\frac{P_k}{I_k+N_0}---\left(1\right)$

$={\mathrm{\ρ}}_k^2(1-{\mathrm{\γ}}_k)G_k^{\mathrm{BF}}{\mathrm{SINR}}_k+({\mathrm{\ρ}}_k^2{\mathrm{\γ}}_k+(1-{\mathrm{\ρ}}_k^2)){\mathrm{SINR}}_k$

P _kthe total transmitting power in subband k, I _kthe interference power on subband k, and N ₀it is the noise power in subband.Can obtain interfere information and noise power information by CQI (channel quality instruction) report from UE. the beam forming gain of estimating, and SINR _kbe the SINR (, the down link CQI being fed back by UE) under non-beamforming transmission strategy, it can be from reporting to obtain from the CQI of UE.

As shown in above formula (1), only can strengthen a part for channel power by wave beam forming, and this ratio is

this part reduces along with the increase of MSE or TD, and other ratio

can regard non-wave beam forming part as.

Conventionally, for various condition, for example, channel variation characteristic in other channel estimator type, UE speed and time domain, the present invention only needs to change ρ _kand γ _kvalue.

Fig. 3 shows according to the flow chart of the operation of the down link SINR Forecasting Methodology of the embodiment of the present invention.

As shown in Figure 3, according to down link SINR Forecasting Methodology of the present invention, in step 301, according to the SINR of the SRS sending from user equipment (UE), calculate the estimation channel of SRS with respect to the MSE of the channel estimating of actual channel.Then,, in step 303, the transmission delay that UE was transmitted between the moment of SRS and the moment of the downlink transmission of described UE generation is counted.Finally, in step 305, produce the SINR of prediction according to the MSE of described channel estimating, described transmission delay, down link CQI that UE feeds back and the beam forming weight of transmitting antenna.

Thus, the present invention can predict the actual SINR of the downlink transmission of utilizing wave beam forming.This actual SINR can distribute for resource, user's scheduling, link adaptation and transmission policy management.Thus, can be in the case of considering that preferably channel estimation errors and transmission delay, on the impact of beamforming transmission, provide higher system performance gain.

Fig. 4 shows the emulation comparison diagram that utilizes the system throughput flow gain of the present invention of SINR prediction and do not utilize the system throughput flow gain of the prior art of SINR prediction.

In Fig. 4, provide the simulation result that utilizes SINR prediction and do not utilize the comparison of the system throughput flow gain of SINR prediction in LTE TDD system.This bandwidth is 10MHz, and antenna amount in eNB and UE is respectively 8 and 2.ENB estimates channel response with MMSE algorithm.In a TTI (Transmission Time Interval), exist 100 movable users to wait for and be scheduled, its speed is 30km/h.Dispatch delay scope is from 4ms to 10ms.According to this simulation result, can observe, utilize that the system throughput flow gain of the present invention of SINR prediction is about compared with not utilizing the situation of SINR prediction has improved 8% to 12%.

Method of the present invention is easy to realize, because need to not deal with this impact of two unfavorable factors (TD and MSE) on beamforming transmission for the special processing of wave beam forming.In addition, the present invention can manage the impact of these unfavorable factors with existing scheduling, link adaptation and transmission handoff algorithms, and higher system performance gain is provided.

In addition, method of the present invention has better performance than the method for prior art.The method of prior art is processed MSE and TD independently, and uses fixing threshold value to be switched to TxDiv.And method of the present invention can be considered the synthetic impact of MSE and TD, and without assign thresholds, any MSE and TD value are carried out to unified processing.

Although below show the present invention in conjunction with the preferred embodiments of the present invention, one skilled in the art will appreciate that without departing from the spirit and scope of the present invention, can carry out various amendments, replacement and change to the present invention.Therefore, the present invention should not limited by above-described embodiment, and should be limited by claims and equivalent thereof.

Claims (12)

1. the down link signal interference-to-noise ratio SINR predict device in the multi-aerial radio communication system that uses wave beam forming, comprising:

Mean square error estimator, according to the SINR of the detection reference signal SRS sending from user equipment (UE), calculates the estimation channel of SRS with respect to the mean square error MSE of the channel estimating of actual channel, and the MSE of described channel estimating is outputed to synthesizer;

Transmission delay counter, the transmission delay between the moment to UE transmission SRS and the moment that the down link of this UE is transmitted is counted, and described transmission delay is outputed to synthesizer; And

Synthesizer, the downlink channel quality instruction CQI of the described transmission delay receiving according to the MSE of the described channel estimating receiving from mean square error estimator, from transmission delay counter, UE feedback and the beam forming weight of transmitting antenna produce the SINR of prediction.

2. down link SINR predict device according to claim 1, wherein, the SINR of described prediction is for downlink wireless control, and described downlink wireless control comprises user's scheduling, resource distribution, link adaptation and the transmission policy management of media access control MAC layer.

3. down link SINR predict device according to claim 1, wherein, the down link CQI of described UE feedback comprises the SINR under non-beamforming transmission strategy.

4. down link SINR predict device according to claim 1, wherein, the beam forming weight of described transmitting antenna is to utilize the detection reference signal SRS sending from UE to carry out channel response to estimate to produce.

5. down link SINR predict device according to claim 1, wherein, the SINR of described SRS obtains in physical layer.

6. down link SINR predict device according to claim 1, wherein, described multi-aerial radio communication system is long-term advancing time division duplex LTE TDD communication system.

7. the base station in the multi-aerial radio communication system that uses wave beam forming, comprising: down link signal interference-to-noise ratio SINR predict device according to claim 1.

8. base station according to claim 7, also comprise: user's scheduler, resource allocator, link adaptation device and transmission policy manager, be respectively used to according to the SINR of the prediction receiving from down link SINR predict device, carry out user's scheduling, resource distribution, link adaptation and the transmission policy management of media access control MAC layer.

9. base station according to claim 7, also comprise: SRS channel estimator, for obtaining the estimation channel response of the detection reference signal SRS sending from UE and the SINR of described SRS, to described estimation channel response is outputed to beam forming weight generator, and the SINR of described SRS is outputed to described down link SINR predict device; And

Beam forming weight generator, for producing beam forming weight according to the estimation channel response of the SRS signal sending from SRS channel estimator, and outputs to described down link SINR predict device by described beam forming weight.

10. base station according to claim 7, wherein, described multi-aerial radio communication system is long-term advancing time division duplex LTE TDD communication system.

11. 1 kinds of down link signal interference-to-noise ratio SINR Forecasting Methodologies in the multi-aerial radio communication system that uses wave beam forming, comprising:

According to the SINR of the detection reference signal SRS sending from user equipment (UE), calculate the estimation channel of SRS with respect to the mean square error MSE of the channel estimating of actual channel;

Transmission delay between moment to UE transmission SRS and the moment that the down link of this UE is transmitted is counted; And

Produce the SINR of prediction according to the downlink channel quality instruction CQI of the MSE of described channel estimating, described transmission delay, UE feedback and the beam forming weight of transmitting antenna.

12. methods according to claim 11, wherein, described multi-aerial radio communication system is long-term advancing time division duplex LTE TDD communication system.

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