CN101262265B - A delay diversity transmission and receiving method for time division duplex wireless communication system - Google Patents

Abstract

The invention discloses a delay diversity transmitting and receiving method of a time division duplex wireless communication system, which comprises that based on a pilot frequency part of the system, the channel estimation is carried out on an upstream channel to obtain an estimated channel impulse response; a received power of each upstream antenna is calculated on the basis of the estimated channel impulse response. Furthermore, a downstream power transmitting factor is calculated according to the received power of each upstream antenna. Different antennas are weighted by a power weight factor at different times and the same data are transmitted through different channels to a receiving terminal; at the receiving terminal, transmitted data delay transmitted by different antennas are merged and received; an estimated value of downstream transmitted data is calculated. By the use of the relevant information of the upstream channel and the downstream channel in the TDD wireless communication system, the method of the invention is adaptive to distribute the transmitted power of each antenna when the delay diversity is transmitted, and also utilizes a multipath diversity receiver at the receiving terminal or uses a joint detection method when in multiuser, thus obtaining higher performance gain.

Description

A kind of delay diversity emission and the method that receives of TDD radio communication system

Technical field

The present invention relates to the wireless mobile communications field, relate in particular to a kind of delay diversity emission and the method that receives of TDD wireless communication system.

Background technology

Wireless channel the time to become multipath fading be a key factor that influences radio communication.The multipath of wireless channel can cause the decline of received signal, particularly in signal bandwidth during less than channel width.Traditionally, base station receiver utilizes space diversity to solve this problem.

In theory, power control is the best approach of opposing channel fading.If transmitting terminal is known channel condition in advance, elder generation offsets the influence that decline brings with signal skew with this in emission so.But this method needs transmitting terminal that bigger dynamic range is arranged, become when because of wireless channel being in addition, so transmitting terminal can't be known the condition of channel in advance, therefore in most of scattering environments, system for power and limited bandwidth, adopt antenna collection method to offset channel fading, transmission error rates is the best way under the fading environment to reduce.

In the third generation and even back three generations's mobile communication system, a large amount of high speed data transmission service makes the burden of down link more and more heavier.Traditional antenna diversity is to adopt many antennas to carry out receive diversity at receiving terminal (travelling carriage), and the signal quality that adopts folding to obtain.Rake receiver (Rake receiver) for example, but, adopt reception antenna of a high price because travelling carriage is size-constrained, increased user's equipment cost.From theoretical and practical application, find that all the transmit diversity of identical exponent number has identical diversity gain with receive diversity.Therefore in order to adapt to the requirement of 3-G (Generation Three mobile communication system), adopt transmit diversity techniques at transmitting terminal; On multiple antenna, transmit, and the design independently decline of maintenance in different channels that will transmit, and again each path signal is merged at receiving terminal, thereby having a strong impact on of multipath fading reduced.Transmit diversity can realize that same transmitting makes some each travelling carriages obtain transmitting gain, and the transmitting gain of traditional receive diversity is just at a travelling carriage.

Traditional time-delay transmit diversity techniques belongs to Open-Loop Transmit Diversity, and promptly transmitting terminal is launched signal not understanding under the situation of channel status in advance from each antenna.The advantage of this method is that system is simple, and diversity performance is not subjected to the influence of channel variation.

Lucent Technologies is 99123680 at the application number on November 8th, 1999, publication number CN1253430A, the Chinese patent application that name is called " be used for the transmit diversity of radio link and receive balanced " has proposed to launch by a plurality of antennas each standalone version of same signal.Between each antenna or spatially spaced apart, or polarization mode is mutually orthogonal, makes each standalone version of same signal can not be subjected to relevant decline.Constant time lag of previous standalone version signal lag that a standalone version signal of launching from a relevant antenna compares from another antenna emission.Constant time lag is at least this a bit period.Each standalone version signal that receives carries out equilibrium in an equalizer or RAKE architecture, obtain a composite signal.RAKE architecture has relevant RAKE fingers, and between the adjacent RAKE fingers fixing time-delay is arranged.

But owing to there is not channel information, traditional time-delay transmit diversity techniques efficient is not high and array gain can not be provided.The mode that the time-delay emission diversity scheme that Alcatel-Lucent for example referred to above patented method adopts is divided equally energy to the employing of each antenna fails to reach best performance in the good TDD system of up-downgoing channel symmetry.

Summary of the invention

The technical problem to be solved in the present invention just provides a kind of delay diversity emission and the method that receives of TDD radio communication system, utilize TDD system up-downgoing correlation between channels information, make system self-adaption ground distribute each antenna transmitting power, thereby systematic function is optimized more according to channel situation.

In order to solve the problems of the technologies described above, the invention provides a kind of delay diversity emission and the method that receives of TDD radio communication system, comprise the steps:

(1) pilot portion according to system carries out channel estimating to up channel, obtains the estimated channel impulse response;

(2), calculate the received power of up each antenna, and calculate corresponding descending power Emission Factor according to the received power of up each antenna according to the estimated channel impulse response;

(3) pass through the weighting of described descending power Emission Factor by different antennas constantly in difference, give receiving terminal through the data that different channels transmit is identical;

(4) merge reception in the receiving terminal emission data that time-delay is launched to different antennae;

(5) estimated value of calculating downlink data.

Further, in the described step (1), k user of t ascending time slot of channel through the estimated matrix of the channel impulse response of channel post-processing is

Expression is to the estimated matrix of channel impulse response, and its size is N * W, and wherein N is a number of antennas, and W is long for the channel estimation window window; H wherein _w ^{(k, n)}(t) the expression t channel impulse response estimation value in w tap in the channel estimation window of k user on n root antenna constantly.

Further, in the described step (2), corresponding power is on k user's of t ascending time slot the n root antenna

$P_n^{(k,t)}=\underset{w=1}{\overset{W}{\mathrm{\Σ}}}{\left|h_w^{(k,n)}\left(t\right)\right|}^2$

H wherein _w ^{(k, n)}(t) be the t channel impulse response estimation value in w tap in the channel estimation window of k user on n root antenna constantly.

Further, in the described step (2), the power division factor of t descending time slot of corresponding k the user of n root antenna is:

${\mathrm{\α}}_n^{(k,t)}=\frac{P_n}{\underset{n=1}{\overset{N}{\mathrm{\Σ}}}{P}_n}=\frac{\underset{w=1}{\overset{W}{\mathrm{\Σ}}}{\left|h_w^{(k,n)}\left(t\right)\right|}^2}{\underset{n=1}{\overset{N}{\mathrm{\Σ}}}\underset{w=1}{\overset{W}{\mathrm{\Σ}}}{\left|h_w^{(k,n)}\left(t\right)\right|}^2}$

Wherein N is a number of antennas, and W is long for the channel estimation window window, h _w ^{(k, n)}(t) be the t channel impulse response estimation value in w tap in the channel estimation window of k user on n root antenna constantly.

Further, in the described step (3), the time-delay emission data Data_send (n) after the process power weightings of n root antenna are:

Data_send(n)＝α _nS(t-τ _n)

Wherein S (t)=Cd (t) is that C is the spectrum-spreading and scrambling matrix through the data to be launched after the spectrum-spreading and scrambling, and d (t) is an initial data, the corresponding time-delay of each antenna τ launch time _nBe τ _n=(n-1) Δ τ, Δ τ is the time-delay Transmission Time Interval.

Further, described Δ τ＞T _c, T _cBe the correlated time of channel, thereby the data that guarantee each antenna time-delay emission arrive receiving terminal through different fading channels.

Further, in the described step (4), comprising:

Receiving terminal receives each antenna to be launched constantly in different time-delays, through the following line delay emission data that arrive behind the different channels, the data e of the n root antenna that wherein receives emission _d ⁿFor:

$e_d^n={\mathrm{\α}}_n\·C\·d(t-{\mathrm{\τ}}_n){\·H}_n+n_d$

H wherein _nBe the pairing independent down channel impulse response of n root antenna, n _dBe white Gaussian noise;

The time-delay emission data e that receiver end merges all antennas is:

$e=\underset{n=1}{\overset{N}{\mathrm{\Σ}}}{e}_d^n=\underset{n=1}{\overset{N}{\mathrm{\Σ}}}{\mathrm{\α}}_n\·C\·d(t-{\mathrm{\τ}}_n){\·H}_n+n_d.$

Further, in the described step (5), utilize rake Rake reception or joint detection algorithm to calculate the estimated value of downlink data.

Further, in the described step (5), adopt associated detecting method,, calculate the estimated value of original user emission data according to ZF linear block balance criterion

For:

R wherein _nBe the correlation matrix of noise, A is the sytem matrix according to channel estimating and spectrum-spreading and scrambling matrix composition.

Further, in the described step (5), adopt associated detecting method,, calculate the estimated value of original user emission data according to minimum mean square error criterion For:

R wherein _dIt is the correlation matrix of user symbol.

The present invention has following beneficial effect:

1. make TDD system self-adaption ground distribute each antenna transmitting power according to channel situation;

2. under the situation of not obvious increase computational complexity, make full use of the symmetry of TDD system up-downgoing channel, realized that the delay diversity that will originally belong to the open loop diversity algorithm becomes the closed loop diversity method that can adjust power parameter according to channel variation adaptively, further improves diversity gain;

3. adaptability is better in the TDD system, is very suitable for Project Realization and handles.

Description of drawings

Fig. 1 is the flow chart of the embodiment of the invention.

Embodiment

The present invention is described in detail below in conjunction with drawings and the specific embodiments.

As shown in Figure 1, present embodiment comprises the steps:

Step 101 is carried out channel estimating according to the pilot portion of system to up channel, obtains the estimated channel impulse response;

Step 102 calculates corresponding descending power Emission Factor according to the received power of up each antenna;

Step 103, is launched identical data and is arrived receiving terminal through behind the different channels constantly by different antenna process descending power Emission Factor weightings in difference;

Step 104 is merging reception through behind the independent channel respectively in the receiving terminal emission data that time-delay is launched to different antennae;

Step 105 utilizes Rake to receive or joint-detection (suggestion is adopted during the multi-user) algorithm computation obtains the estimated value of downlink data.

With the TD-SCDMA wireless communication system is example, and an application example of the present invention is described in detail.Suppose that its base station end aerial array adopts N root antenna.Mainly may further comprise the steps:

1) uplink channel estimation:

According to the pilot portion of up reception data, adopt channel estimation methods, then k user of t ascending time slot of channel is expressed as through the estimated matrix of the channel impulse response of channel post-processing

Expression is to the estimated matrix of channel impulse response, and its size is N * W, and wherein N is a number of antennas, and W is long for the channel estimation window window; And wherein

Expression t is the channel impulse response estimation value in w tap in the channel estimation window of k user on n root antenna constantly.

2) calculate the descending power Emission Factor:

Obtain according to step 1) that corresponding power is on k user's of t ascending time slot the n root antenna

$P_n^{(k,t)}=\underset{w=1}{\overset{W}{\mathrm{\Σ}}}{\left|h_w^{(k,n)}\left(t\right)\right|}^2---\left(2\right)$

Then the descending power Emission Factor computing formula of t descending time slot of corresponding k the user of n root antenna is as follows:

${\mathrm{\α}}_n^{(k,t)}=\frac{P_n}{\underset{n=1}{\overset{N}{\mathrm{\Σ}}}{P}_n}=\frac{\underset{w=1}{\overset{W}{\mathrm{\Σ}}}{\left|h_w^{(k,n)}\left(t\right)\right|}^2}{\underset{n=1}{\overset{N}{\mathrm{\Σ}}}\underset{w=1}{\overset{W}{\mathrm{\Σ}}}{\left|h_w^{(k,n)}\left(t\right)\right|}^2}---\left(3\right)$

Wherein

Be w the pairing estimation channel impulse response estimation of tap value in the estimating window of n root antenna after k user's process of t ascending time slot channel post-processing in the step 1;

3) down link weighting time-delay emission:

The delay diversity launch scenario that adopts in the down link is meant: constantly by different antenna process descending power Emission Factor weightings, launch identical data through arriving the process of receiving terminal behind the different channels in difference.τ launch time wherein delays time _nCorresponding one by one with number of antennas, i.e. τ _nThe individual moment is by n root antenna downlink.

The corresponding time-delay of each antenna τ launch time _nCan calculate by following formula:

τ _n＝(n-1)·Δτ (4)

Wherein Δ τ must satisfy Δ τ＞T for the time-delay Transmission Time Interval _c, T _cRepresent the correlated time of channel, thereby the data that guarantee each antenna time-delay emission arrive receiving terminal through different fading channels.

The time-delay after the process power weightings of n root antenna emission data Data_send (n) then, be expressed from the next into:

Data_send(n)＝α _nS(t-τ _n) (5)

Wherein S (t)=Cd (t) is that C is the spectrum-spreading and scrambling matrix through the data to be launched after the spectrum-spreading and scrambling, and d (t) is an initial data.

4) receiving terminal merges:

The following line delay emission data that each antenna is launched constantly in different time-delays arrive receiving terminal through behind the different channels, and wherein the data of n root antenna emission arrive the receiving terminal postscript and make e _d ⁿ, be shown below:

$e_d^n={\mathrm{\α}}_n\·C\·d(t-{\mathrm{\τ}}_n){\·H}_n+n_d---\left(6\right)$

H wherein _nBe the pairing independent down channel impulse response of n root antenna, n _dBe white Gaussian noise.

Because many antenna time-delay emissions, the time-delay emission data that merge all antennas at receiver end are Data_recieved, and note is made e, is shown below:

$e=\underset{n=1}{\overset{N}{\mathrm{\Σ}}}{e}_d^n=\underset{n=1}{\overset{N}{\mathrm{\Σ}}}{\mathrm{\α}}_n\·C\·d(t-{\mathrm{\τ}}_n){\·H}_n+n_d---\left(7\right)$

5) data estimator calculates: according to the pairing reception data of employing delay diversity launch scenario that obtain at receiving terminal in the step 4), following step is utilized the Rake receiver exactly or is adopted joint detection algorithm that it is detected when the multi-user, thereby obtains the estimated value to the original transmitted data

Wherein can adopt associated detecting method during the multi-user, provide two kinds of different computational methods below:

According to ZF linear block balance (ZF-BLE) criterion, original user emission data d is estimated as:

R wherein _nIt is the correlation matrix of noise.A is the sytem matrix according to channel estimating and spectrum-spreading and scrambling matrix composition.

According to least mean-square error (MMSE) criterion, the user launches being estimated as of data d

R wherein _dIt is the correlation matrix of user symbol.

The present invention adopts the power division factor of utilizing uplink channel information to calculate descending each antenna, and the delay data to each antenna carries out power weightings when downlink, and carry out the method that diversity merge to receive at receiving terminal and realized that the delay diversity that will originally belong to the open loop diversity algorithm becomes the closed loop diversity method that can adjust power parameter according to channel variation adaptively, further improve the communication system performance that adopts deversity scheme.

The present invention makes full use of the symmetry of TDD system up-downgoing channel under the situation of not obvious increase computational complexity, further improve diversity gain, is beneficial to very much Project Realization.

But should be understood that above-mentioned description at preferred embodiment of the present invention is comparatively concrete, can not therefore think the restriction to scope of patent protection of the present invention, scope of patent protection of the present invention should be as the criterion with claims.

Claims (9)

1. emission of the delay diversity of a TDD radio communication system and the method that receives comprise the steps:

(1) pilot portion according to system carries out channel estimating to up channel, obtains the estimated channel impulse response;

(2), calculate the received power of up each antenna, and calculate corresponding descending power Emission Factor according to the received power of up each antenna according to the estimated channel impulse response;

(3) pass through the weighting of described descending power Emission Factor by different antennas constantly in difference, give receiving terminal through the data that different channels transmit is identical; Wherein, time-delay τ launch time _nCorresponding one by one with number of antennas, i.e. τ _nThe individual moment is by n root antenna downlink; The time-delay after the process power weightings of n root antenna emission data Data_send (n) then, be expressed from the next into:

Data_send(n)＝α _nS(t-τ _n) (5)

Wherein S (t)=C.d (t) is that C is the spectrum-spreading and scrambling matrix through the data to be launched after the spectrum-spreading and scrambling, and d (t) is an initial data, α _nBe the descending power weighted factor.

(4) merge reception in the receiving terminal emission data that time-delay is launched to different antennae;

(5) estimated value of calculating downlink data.

2. method according to claim 1 is characterized in that, in the described step (1), k user of t ascending time slot of channel through the estimated matrix of the channel impulse response of channel post-processing is

Expression is to the estimated matrix of channel impulse response, and its size is N * W, and wherein N is a number of antennas, and W is long for the channel estimation window window; Wherein

Expression t is the channel impulse response estimation value in w tap in the channel estimation window of k user on n root antenna constantly.

3. method according to claim 1 and 2 is characterized in that, in the described step (2), corresponding power is on k user's of t ascending time slot the n root antenna

$P_n^{(k,t)}=\underset{w=1}{\overset{W}{\mathrm{\Σ}}}{\left|h_w^{(k,n)}\left(t\right)\right|}^2$

Wherein

Be the t channel impulse response estimation value in w tap in the channel estimation window of k user on n root antenna constantly, W is long for the channel estimation window window.

4. method according to claim 3 is characterized in that, in the described step (2), the power division factor of t descending time slot of corresponding k the user of n root antenna is:

${\mathrm{\α}}_n^{(k,n)}=\frac{P_n}{\underset{n=1}{\overset{N}{\mathrm{\Σ}}}{P}_n}=\frac{\underset{w=1}{\overset{W}{\mathrm{\Σ}}}{\left|h_w^{(k,n)}\left(t\right)\right|}^2}{\underset{n=1}{\overset{N}{\mathrm{\Σ}}}\underset{w=1}{\overset{W}{\mathrm{\Σ}}}{\left|h_w^{(k,n)}\left(t\right)\right|}^2}$

Wherein N is a number of antennas, and W is long for the channel estimation window window,

Be the t channel impulse response estimation value in w tap in the channel estimation window of k user on n root antenna constantly.

5. method according to claim 1 is characterized in that, described Δ τ＞T _c, T _cBe the correlated time of channel, thereby the data that guarantee each antenna time-delay emission arrive receiving terminal through different fading channels.

6. method according to claim 1 is characterized in that, in the described step (4), comprising:

Receiving terminal receives each antenna to be launched constantly in different time-delays, through the following line delay emission data that arrive behind the different channels, the data of the n root antenna that wherein receives emission

For:

$e_d^n={\mathrm{\α}}_n\·C\·d(t-{\mathrm{\τ}}_n)\·H_n+n_d$

H wherein _nBe the pairing independent down channel impulse response of n root antenna, n _dBe white Gaussian noise;

The time-delay emission data e that receiver end merges all antennas is:

$e=\underset{n=1}{\overset{N}{\mathrm{\Σ}}}{e}_d^n=\underset{n=1}{\overset{N}{\mathrm{\Σ}}}{\mathrm{\α}}_n\·C\·d(t-{\mathrm{\τ}}_n)\·H_n+n_d.$

7. method according to claim 1 is characterized in that, in the described step (5), utilizes rake Rake reception or joint detection algorithm to calculate the estimated value of downlink data.

8. method according to claim 6 is characterized in that, in the described step (5), adopts associated detecting method, according to ZF linear block balance criterion, calculates the estimated value of original user emission data

For:

R wherein _nBe the correlation matrix of noise, A is the sytem matrix according to channel estimating and spectrum-spreading and scrambling matrix composition.

9. method according to claim 6 is characterized in that, in the described step (5), adopts associated detecting method, according to minimum mean square error criterion, calculates the estimated value of original user emission data

For:

R wherein _dIt is the correlation matrix of user symbol.

Images