CN103138817A - Method and device used for choosing up link transmission antenna - Google Patents

Abstract

The invention provides a method and a device used for choosing an up link transmission antenna. The method used for choosing the up link transmission antenna comprises the following steps: base station equipment respectively receiving an inquiry reference signal sent via two antennas from user equipment; according to the inquiry reference signal, determining the up link transmission antenna; according to the determined up link transmission antenna, generating an antenna choosing indicating signal; and sending the antenna choosing indicating signal to the user equipment. Compared with the prior art, the device used for choosing the up link transmission antenna chooses a suitable antenna for the user equipment to transmit SRS according to SRS quality and transmission delaying of antenna of each user equipment, balances signal channel estimation quality of down link signal channels of two antennas of a user equipment end, improves the down link transmit beamforming performance, especially double flow signal channel transmit beamforming performance.

Description

A kind of method and apparatus for selecting the ul transmissions antenna

Technical field

The present invention relates to communication technical field, relate in particular to a kind of for select the technology of ul transmissions antenna at beam-forming system.

Background technology

In multiple antenna communication, for example in LTE TDD, wave beam forming (beamforming) is an important technology.This technology can improved system throughput, increase the coverage of system.ENB inquires after reference signal (Sounding Reference Signals, SRS) based on what subscriber equipment sent, generates beam shape-endowing weight value, and these weights are applied in downlink transmission with subscriber equipment.

In modern wireless communication systems, for example in LTE, subscriber equipment has two antennas usually.In rich scattering environments, the correlation of these two antennas is little.Therefore in up link, for obtaining whole channel condition informations (channel state information, CSI), need to carry out antenna and switch, with the performance of improved system.Especially in the situation that double-current channel rays figuration, full CSI will significantly increase the performance of system.

Because beam shape-endowing weight value should be adjusted according to CSI, the accuracy height correlation of the performance of wave beam forming and channel estimating.If in transmitting procedure, weights conform to instantaneous channel status, and system gain will be larger, otherwise systematic function is poorer.Usually, in the TDD system, Downlink channel estimation is inquired after reference signal according to the up link of user device transmissions and is obtained.

Two kinds of main factors are arranged, affect the accuracy of channel estimating:

1, the estimation channel of SRS and the mean square error between real channel (Mean Square Error, MSE).Usually, the lower signal to noise ratio (SINR) of SRS will cause larger MSE.

2, the time of subscriber equipment transmission SRS and base station and this subscriber equipment are set up the propagation delay time (Transmission Delay, TD) of down link.Become when due to channel being, if the time interval of SRS transmission and DL transmission is oversize, beam shape-endowing weight value will be out-of-date.

The low correlation that declines between two antennas due to subscriber equipment, the channel estimating quality of two antennas of this subscriber equipment is with difference.Therefore, need to consider that this is on the impact of wave beam forming generation.If channel quality is uneven, for example, the channel quality of an antenna is more far short of what is expected than another, is equivalent to due to not the mating of channel estimating, and real channel sequence is near 1.This will reduce the throughput of system of double-current channel rays figuration.

In prior art, LTE adopts the Open loop and closed loop antenna switching scheme, for subscriber equipment carries out ul transmissions.In the situation that select open-loop antenna, subscriber equipment can freely switch transmit antenna, and need to be from the signal of eNB.In the situation that select closed loop antenna, eNB to subscriber equipment, determines to adopt which antenna to transmit at the subscriber equipment end by transmitting antenna designator (antenna indicator).In the LTE agreement, determine to come transmitting SRS with open-loop antenna, use closed loop antenna when going physically shared channel (PUSCH) transmission.The reason of employing such scheme is only to have considered the performance of ul transmissions herein.The SRS transmission is only as the reference of selecting the up link antenna.But in the situation that downlink beamforming, especially in the situation that used double-current channel rays figuration, if the decline of the antenna of subscriber equipment end is serious, estimation channel corresponding to this antenna is with insincere, and the performance of downlink transmission will reduce.

Summary of the invention

The purpose of this invention is to provide a kind of method and apparatus for selecting the ul transmissions antenna.

According to an aspect of the present invention, provide a kind of for select the method for ul transmissions antenna at the base station equipment end at beam-forming system, wherein, the method comprises:

A receives respectively and inquires after reference signal from subscriber equipment via what two antennas sent;

B determines the ul transmissions antenna according to the described reference signal of inquiring after;

The c basis is determined described ul transmissions antenna, generates a day line options designator;

D is sent to described subscriber equipment with described day line options designator.

According to another aspect of the present invention, also provide a kind of in the method for beam-forming system at subscriber equipment end assisted Selection ul transmissions antenna, wherein, the method comprises:

A sends to base station equipment respectively and inquires after reference signal via two different antennas;

B is received from the sky line options designator that described base station equipment sends;

C sends the described reference signal of inquiring after to described base station equipment again according to the described day specified ul transmissions antenna of line options designator.

According to a further aspect of the invention, also provide a kind of for select the base station equipment of ul transmissions antenna at beam-forming system, wherein, this equipment comprises:

Inquire after receiving system, be used for receiving respectively and inquire after reference signal from subscriber equipment via what two antennas sent;

Antenna is determined device, is used for according to the described reference signal of inquiring after, and determines the ul transmissions antenna;

Instruction generating device is used for generating a day line options designator according to the determining of described ul transmissions antenna;

The indication dispensing device is used for described day line options designator is sent to described subscriber equipment.

According to a further aspect of the invention, also provide a kind of for the subscriber equipment at beam-forming system assisted Selection ul transmissions antenna, wherein, this equipment comprises:

First inquires after dispensing device, is used for via two different antennas, sends to base station equipment respectively and inquires after reference signal;

The indication receiving system is used for being received from the sky line options designator that described base station equipment sends;

Second inquires after dispensing device, is used for again sending the described reference signal of inquiring after to described base station equipment according to the described day specified ul transmissions antenna of line options designator.

Compared with prior art, the present invention is according to SRS quality and the propagation delay time of each subscriber equipment antenna, for subscriber equipment selects a suitable antenna with transmitting SRS, balance the channel estimating quality of down channel of two antennas of subscriber equipment end, improved the performance of downlink beamforming, especially double-current channel rays figuration.

Description of drawings

By reading the detailed description that non-limiting example is done of doing with reference to the following drawings, it is more obvious that other features, objects and advantages of the present invention will become:

Fig. 1 illustrates the equipment schematic diagram that is used for selecting the ul transmissions antenna according to one aspect of the invention;

Fig. 2 illustrates the schematic diagram that is used for selecting the ul transmissions antenna in accordance with a preferred embodiment of the present invention;

Fig. 3 illustrates the method flow diagram that is used for selecting the ul transmissions antenna according to a further aspect of the present invention.

In accompanying drawing, same or analogous Reference numeral represents same or analogous parts.

Embodiment

Below in conjunction with accompanying drawing, the present invention is described in further detail.

Fig. 1 illustrates the equipment schematic diagram that is used for selecting the ul transmissions antenna according to one aspect of the invention; Base station equipment 1 comprises that inquiring after receiving system 11, antenna determines device 12, instruction generating device 13 and indication dispensing device 14; Subscriber equipment 2 comprise first inquire after dispensing device 21, the indication receiving system 22 and second inquire after dispensing device 23.

Work in coordination between each device of base station equipment 1 and subscriber equipment 2, to select the ul transmissions antenna.Particularly, first in subscriber equipment 2 inquired after dispensing device 21 via two different antennas, sends to base station equipment respectively and inquires after reference signal; The receiving system 11 of inquiring after in base station equipment 1 receives respectively and inquires after reference signal from subscriber equipment via what two antennas sent; Antenna determines that device 12 according to the described reference signal of inquiring after, determines the ul transmissions antenna; Instruction generating device 13 bases are determined described ul transmissions antenna, are generated a day line options designator; Indication dispensing device 14 is sent to described subscriber equipment with described day line options designator; Indication receiving system 22 in subscriber equipment 2 is received from the sky line options designator that described base station equipment sends; Second inquires after dispensing device 23 according to the described day specified ul transmissions antenna of line options designator, again sends the described reference signal of inquiring after to described base station equipment.

At this, subscriber equipment 2 once can choice for use antenna 0 or antenna 1 carry out the SRS transmission.Base station equipment 1 is that subscriber equipment 2 is selected a suitable antenna accordingly, in downlink control channel, sky line options designator is sent to this subscriber equipment 2.In a single day subscriber equipment 2 receives this day line options designator, in next SRS chance, comes transmitting SRS with specified antenna in this day line options designator.

Preferably, antenna in base station equipment 1 determines that device 12 is according to the described reference signal of inquiring after, and in conjunction with described estimation channel and the mean square error between real channel (Mean Square Error, MSE) of inquiring after reference signal, determine described ul transmissions antenna.Particularly, suppose

It is the channel of s transmit antenna on the t moment, a k bandwidth;

It is the estimation channel response of s transmit antenna on the t moment, a k bandwidth;

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

Can derive thus:

Wherein, s=1K S.

Usually,

The current signal to noise ratio (SINR) of the SRS signal that depends on channel estimation method and receive.

If adopt and minimize mean square error algorithm, correlated error is:

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

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

Wherein,

It is the signal to noise ratio of the up link SRS of s transmit antenna on the wide k of subband.

Can obtain according to measurement report,

Equal

Wherein, s=1K S. mean square error can be defined as:

It is the ratio of error power and channel power.Antenna determine device 12 according to inquire after receiving system 11 received inquire after reference signal, and in conjunction with the mean square error of being known by aforesaid way, determine the ul transmissions antenna.

Preferably, antenna in base station equipment 1 determines that device 12 is according to the described reference signal of inquiring after, and send the described time of inquiring after reference signal and set up propagation delay time (the Transmission Delay of down link with described subscriber equipment in conjunction with described subscriber equipment, TD), determine described ul transmissions antenna.Particularly, suppose

The time of transmitting on the wide k of subband for last SRS of the antenna s of target UE;

It is the time that builds on the downlink transmission between subscriber equipment on the wide k of subband; Propagation delay time is:

In the LTE system,

Can calculate according to the quantity of subframe.Antenna determine device 12 according to inquire after receiving system 11 received inquire after reference signal, and in conjunction with the propagation delay time of being known by aforesaid way, determine the ul transmissions antenna.

More preferably, antenna in base station equipment 1 determines that device 12 is according to the described reference signal of inquiring after, and in conjunction with the described estimation channel of reference signal and the mean square error between real channel of inquiring after, and described subscriber equipment sends the described time of inquiring after reference signal and sets up the propagation delay time of down link with described subscriber equipment, determines described ul transmissions antenna.Particularly, at t+t _kChannel response constantly can be calculated by following formula:

$H_k^s(t+t_k^s)=r_k^s{H}_k^s\left(t\right)+h^s(t+t_k^s)$

Wherein,

It is the Gaussian noise stochastic variable.To rayleigh fading channel,

Can be calculated as

(f _DDoppler frequency shift).Can further derive:

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

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

Usually, to any different condition, such as other channel estimating types, UE speed, channel variation etc. in time domain, only need to change

With Value.

As can be known, along with the increase of propagation delay time and mean square error, channel estimation error is also along with increase.Therefore, based on r _kWith Utilize following formula to come calculating parameter:

$M\left(s\right)=f\left(\right\{r_k^s\},\{g_k^s\left\}\right)$

Notice that useful part is here

The power of this part is

Therefore, an example that defines this parameter is:

$M\left(s\right)=\underset{k=1}{\mathrm{\Σ}}{\left({\mathrm{\ρ}}_k^s\right)}^2(1-{\mathrm{\γ}}_k^s)$

Thus, antenna determines that device 12 selects to have the antenna that minimizes M (s), with as the ul transmissions antenna.

The basic thought of selecting the ul transmissions antenna is the channel estimating quality that guarantees each subscriber equipment antenna.At this, the channel estimating quality is determined by mean square error and propagation delay time.Base station equipment 1 can constantly be selected an antenna for subscriber equipment, and with the accuracy of the improvement channel estimating corresponding with this antenna, but this will extend the propagation delay time of the estimation channel corresponding with other antennas.Therefore, suppose that the speed of subscriber equipment is very low, can increase the chance of the ul transmissions of the serious subscriber equipment antenna of decline, and keep the quality of the channel estimating of other antennas.ENB can merge several SRS that receive and improve the channel estimating quality.

Fig. 2 has provided a simulation result, is used for comparison in LTE TDD system, adopts day line options and does not adopt the throughput of day line options.Suppose that bandwidth is 10MHz, the antenna amount in eNB is 8, the antenna amount in subscriber equipment is 2.ENB estimates channel response with the maximization mean square error.In down link, adopt double-current channel rays figuration, the speed of subscriber equipment is 30km/h.In up link, the many 10dB of the relative down link of the average signal-to-noise ratio of the SRS that receives.Propagation delay time is from 4ms to 10ms.As seen from the figure, can obtain the gain of 1dB in the intermediate range of SINR.

Fig. 3 illustrates the method flow diagram that is used for selecting the ul transmissions antenna according to a further aspect of the present invention.

Work in coordination between each step of base station equipment 1 and subscriber equipment 2, to select the ul transmissions antenna.Particularly, in step S1, subscriber equipment 2 sends to base station equipment respectively and inquires after reference signal via two different antennas; Base station equipment 1 receives respectively inquires after reference signal from subscriber equipment via what two antennas sent; In step S2, base station equipment 1 is determined the ul transmissions antenna according to the described reference signal of inquiring after; In step S3, base station equipment 1 basis is determined described ul transmissions antenna, is generated a day line options designator; In step S4, base station equipment 1 is sent to described subscriber equipment with described day line options designator; Subscriber equipment 2 is received from the sky line options designator that described base station equipment sends; In step S5, subscriber equipment 2 sends the described reference signal of inquiring after to described base station equipment again according to the described day specified ul transmissions antenna of line options designator.

At this, subscriber equipment 2 once can choice for use antenna 0 or antenna 1 carry out the SRS transmission.Base station equipment 1 is that subscriber equipment 2 is selected a suitable antenna accordingly, in downlink control channel, sky line options designator is sent to this subscriber equipment 2.In a single day subscriber equipment 2 receives this day line options designator, in next SRS chance, comes transmitting SRS with specified antenna in this day line options designator.

Preferably, in step S2, base station equipment 1 is according to the described reference signal of inquiring after, and in conjunction with described estimation channel and the mean square error between real channel (Mean Square Error, MSE) of inquiring after reference signal, determines described ul transmissions antenna.Particularly, suppose

It is the channel of s transmit antenna on the t moment, a k bandwidth; It is the estimation channel response of s transmit antenna on the t moment, a k bandwidth;

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

Can derive thus: Wherein, s=1K S.

Usually,

The current signal to noise ratio (SINR) of the SRS signal that depends on channel estimation method and receive.

If adopt and minimize mean square error algorithm, correlated error is:

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

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

Wherein,

It is the signal to noise ratio of the up link SRS of s transmit antenna on the wide k of subband.

Can obtain according to measurement report, Equal

Wherein, s=1K S. mean square error can be defined as:

It is the ratio of error power and channel power.In step S2, base station equipment 1 is according to the received reference signal of inquiring after in step S1, and in conjunction with the mean square error of being known by aforesaid way, determines the ul transmissions antenna.

Preferably, in step S2, base station equipment 1 is according to the described reference signal of inquiring after, and send the described time of inquiring after reference signal and set up propagation delay time (the Transmission Delay of down link with described subscriber equipment in conjunction with described subscriber equipment, TD), determine described ul transmissions antenna.Particularly, suppose

The time of transmitting on the wide k of subband for last SRS of the antenna s of target UE; It is the time that builds on the downlink transmission between subscriber equipment on the wide k of subband; Propagation delay time is:

In the LTE system,

Can calculate according to the quantity of subframe.In step S2, base station equipment 1 is according to the received reference signal of inquiring after in step S1, and in conjunction with the propagation delay time of being known by aforesaid way, determines the ul transmissions antenna.

More preferably, in step S2, base station equipment 1 is according to the described reference signal of inquiring after, and in conjunction with the described estimation channel of reference signal and the mean square error between real channel of inquiring after, and described subscriber equipment sends the described time of inquiring after reference signal and sets up the propagation delay time of down link with described subscriber equipment, determines described ul transmissions antenna.Particularly, at t+t _kChannel response constantly can be calculated by following formula:

$H_k^s(t+t_k^s)=r_k^s{H}_k^s\left(t\right)+h^s(t+t_k^s)$

Wherein,

It is the Gaussian noise stochastic variable.To rayleigh fading channel,

Can be calculated as

(f _DDoppler frequency shift).Can further derive:

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

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

Usually, to any different condition, such as other channel estimating types, UE speed, channel variation etc. in time domain, only need to change

With Value.

As can be known, along with the increase of propagation delay time and mean square error, channel estimation error is also along with increase.Therefore, based on r _kWith

Utilize following formula to come calculating parameter:

$M\left(s\right)=f\left(\right\{r_k^s\},\{g_k^s\left\}\right)$

Notice that useful part is here

The power of this part is

Therefore, an example that defines this parameter is:

$M\left(s\right)=\underset{k=1}{\mathrm{\Σ}}{\left({\mathrm{\ρ}}_k^s\right)}^2(1-{\mathrm{\γ}}_k^s)$

Thus, in step S2, base station equipment 1 selects to have the antenna that minimizes M (s), with as the ul transmissions antenna.

The basic thought of selecting the ul transmissions antenna is the channel estimating quality that guarantees each subscriber equipment antenna.At this, the channel estimating quality is determined by mean square error and propagation delay time.Base station equipment 1 can constantly be selected an antenna for subscriber equipment, and with the accuracy of the improvement channel estimating corresponding with this antenna, but this will extend the propagation delay time of the estimation channel corresponding with other antennas.Therefore, suppose that the speed of subscriber equipment is very low, can increase the chance of the ul transmissions of the serious subscriber equipment antenna of decline, and keep the quality of the channel estimating of other antennas.ENB can improve the channel estimating quality in conjunction with several SRS that receive.

To those skilled in the art, obviously the invention is not restricted to the details of above-mentioned one exemplary embodiment, and in the situation that do not deviate from spirit of the present invention or essential characteristic, can realize the present invention with other concrete form.Therefore, no matter from which point, all should regard embodiment as exemplary, and be nonrestrictive, scope of the present invention is limited by claims rather than above-mentioned explanation, therefore is intended to be included in the present invention dropping on the implication that is equal to important document of claim and all changes in scope.Any Reference numeral in claim should be considered as limit related claim.In addition, obviously other unit or step do not got rid of in " comprising " word, and odd number is not got rid of plural number.A plurality of unit of stating in the device claim or device also can be realized by software or hardware by a unit or device.The first, the second word such as grade is used for representing title, and does not represent any specific order.

Claims (8)

1. one kind is used for selecting the method for ul transmissions antenna at the base station equipment end at beam-forming system, and wherein, the method comprises:

A receives respectively and inquires after reference signal from subscriber equipment via what two antennas sent;

B determines the ul transmissions antenna according to the described reference signal of inquiring after;

The c basis is determined described ul transmissions antenna, generates a day line options designator;

D is sent to described subscriber equipment with described day line options designator.

2. method according to claim 1, wherein, described step b comprises:

-according to the described reference signal of inquiring after, and in conjunction with the described estimation channel of reference signal and the mean square error between real channel of inquiring after, determine described ul transmissions antenna.

3. method according to claim 1 and 2, wherein, described step b comprises:

-according to the described reference signal of inquiring after, and send the described time of inquiring after reference signal and set up the propagation delay time of down link with described subscriber equipment in conjunction with described subscriber equipment, determine described ul transmissions antenna.

4. one kind is used in the method for beam-forming system at subscriber equipment end assisted Selection ul transmissions antenna, and wherein, the method comprises:

A sends to base station equipment respectively and inquires after reference signal via two different antennas;

B is received from the sky line options designator that described base station equipment sends;

C sends the described reference signal of inquiring after to described base station equipment again according to the described day specified ul transmissions antenna of line options designator.

5. base station equipment that is used for selecting at beam-forming system the ul transmissions antenna, wherein, this equipment comprises:

Inquire after receiving system, be used for receiving respectively and inquire after reference signal from subscriber equipment via what two antennas sent;

Antenna is determined device, is used for according to the described reference signal of inquiring after, and determines the ul transmissions antenna;

Instruction generating device is used for generating a day line options designator according to the determining of described ul transmissions antenna;

The indication dispensing device is used for described day line options designator is sent to described subscriber equipment.

6. base station equipment according to claim 5, wherein, described antenna determines that device is used for:

-according to the described reference signal of inquiring after, and in conjunction with the described estimation channel of reference signal and the mean square error between real channel of inquiring after, determine described ul transmissions antenna.

7. according to claim 5 or 6 described base station equipments, wherein, described antenna determines that device is used for:

-according to the described reference signal of inquiring after, and send the described time of inquiring after reference signal and set up the propagation delay time of down link with described subscriber equipment in conjunction with described subscriber equipment, determine described ul transmissions antenna.

8. subscriber equipment that is used at beam-forming system assisted Selection ul transmissions antenna, wherein, this equipment comprises:

First inquires after dispensing device, is used for via two different antennas, sends to base station equipment respectively and inquires after reference signal;

The indication receiving system is used for being received from the sky line options designator that described base station equipment sends;

Second inquires after dispensing device, is used for again sending the described reference signal of inquiring after to described base station equipment according to the described day specified ul transmissions antenna of line options designator.

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