CN102014401B - Channel estimate method and system in multi-antenna descending system, and base station as well as terminal thereof - Google Patents

Abstract

The present invention discloses a channel estimate method and a system in the multi-antenna descending system, and a base station as well as a terminal thereof. The method comprises the following steps: shifting basic trainning sequence to generate K trainning sequence offsets, selecting K' trainning sequence offsets from K trainning sequence offsets to distribute to the master antennas in M antennas; respectively distributing a trainning sequence offset from the residual trainning sequence offsets to each auxiliary antenna, wherein the number of auxiliary antenna is M-1; to the signal from the master antenna, calculating channel estimate of each user according to the trainning sequence offset corresponding to each user; to the signal from the auxiliary antenna, calculating the total channel estimate value of all users on the auxiliary antenna according to the trainning sequence offset distributed to the auxiliary antenna; obtaining the emission power proportion of each user according to the channel estimate result of each user on master antenna, then calculating the channel estimate of each user on auxiliary antenna according to the emission power proportion and the total channel estimate value of all users on the auxiliary antenna. The present invention has an advantage of increasing the number of users sustained by the system.

Description

Channel estimation method and system in multi-antenna downlink system, base station and terminal

Technical Field

The present invention relates to mobile communication technologies, and in particular, to a channel estimation method and system, a base station, and a terminal in a Time Division Duplex (TDD) multi-antenna Code Division Multiple Access (CDMA) downlink system.

Background

In a mobile communication system, since a transmission signal is affected by a wireless channel when transmitted in the wireless channel, a receiving end needs to recover the transmission signal from a received signal according to the degree of the effect of the wireless channel on the transmission signal. The degree of influence of the radio channel on the transmission signal is represented by a Channel Impulse Response (CIR) of the radio channel. Since the wireless channel has a large randomness, it will cause CIR variation and cause distortion in amplitude, phase and frequency of the received signal, and therefore, the CIR of the channel needs to be estimated to correctly recover the transmitted signal from the received signal. The process of estimating the CIR of the channel is called channel estimation.

In a Time Division Duplex (TDD) Code Division Multiple Access (CDMA) system, a slot format of a signal frame is shown in fig. 1, and a data field 1 and a data field 2 are respectively located at both sides of a training sequence (Midamble), and a guard interval (GP) is located at the end of the slot. In some slot formats, there is other information between the data field and the training sequence, which is not listed here. Channel estimation for TDD CDMA systems is based on a training sequence, and then data symbols for data domain 1 and data domain 2 are demodulated based on the CIR of the channel estimation.

In a wireless channel, a transmission signal does not travel along a single path, but encounters various object obstructions, and reaches a receiving end through different paths such as reflection, scattering, refraction, diffraction and the like, so that the transmission signal becomes a composite signal which reaches through each path. As a result of multipath propagation, different reflected waves of the same transmitted signal arrive at the receiving end at different times (i.e., with different delays) and with different phases. Generally, the system will set the maximum transmission delay supported by the system, and the signals received within the time corresponding to the maximum transmission delay are considered as different reflected waves of the same transmitted signal, so the time corresponding to the maximum transmission delay can be vividly defined as channel estimation windows, each channel estimation window comprising several paths.

Since multiple users usually communicate simultaneously, the signal received by the receiving end is usually the superposition of multiple paths of multiple users, and then the superposed training sequence and the superposed user data part are separated from the received signal, the separated superposed training sequence and the training sequence generated locally are used to perform channel estimation, and the separated user data part is jointly detected according to the channel estimation result and the spreading and scrambling sequences generated locally, so as to estimate the data symbol of each user.

However, when performing channel estimation, since a received signal is usually a superposition of multiple paths of multiple users, it is necessary to perform channel estimation for each user. In the prior art, in order to improve the channel estimation speed, in a single antenna system, a training sequence of each user is usually constructed by using a basic training sequence according to a certain rule, for example, the training sequence of each user is constructed in a cyclic shift manner, so that a training sequence channel matrix at a receiving end has cyclic correlation. Taking a basic training sequence with a length of 128 chips as an example, if the basic training sequence is shifted by 8 chips each time, 16 shifted training sequences (abbreviated as training sequence offsets) can be obtained, and since each training sequence offset corresponds to one user, a single antenna system using the training sequence allocation method can support 16 users.

However, for a mimo system, i.e. a multi-antenna system, a different training sequence needs to be allocated to the same user on each antenna, so that the receiving end calculates channel estimates of the users on different antennas. In this case, if the training sequence of each user is obtained for each antenna in the single-antenna system, the number of users that can be supported in the multi-antenna system decreases as the number of antennas increases. Taking the case of two antennas as an example, for the training sequence with the length of 128 chips, if the training sequence still shifts 8 chips at a time, the obtained 16 training sequence shifts are equally distributed on the two antennas, and a different training sequence shift is distributed to the user on each antenna, so that the number of users supported at this time is 8, and thus the number of users supported is obviously reduced.

Disclosure of Invention

In view of this, the present invention provides a channel estimation method in a multi-antenna downlink system, and provides a base station, a terminal and a channel estimation system in the multi-antenna downlink system, so as to increase the number of users that can be supported by the multi-antenna system.

The channel estimation method in the multi-antenna downlink system provided by the invention comprises the following steps:

A. shifting a basic training sequence to generate K training sequence offsets, selecting K' training sequence offsets from the K training sequence offsets to distribute to a main antenna set in M antennas, wherein each user on the main antenna uses one training sequence offset; distributing a training sequence offset for each of M-1 auxiliary antennas set in the M antennas from the rest training sequence offsets, wherein K' users on each auxiliary antenna share one training sequence offset; wherein K, M and K 'are both integers greater than 0, and K' + M-1 is less than or equal to K;

B. calculating the channel estimation of each user on the main antenna according to the training sequence offset corresponding to each user in the K' training sequence offsets of the signals from the main antenna; calculating the total channel estimation value of all users on each auxiliary antenna according to the training sequence offset distributed to the auxiliary antenna for the signal from each auxiliary antenna;

and calculating the channel estimation of each user on each auxiliary antenna according to the transmitting power proportion and the total channel estimation value of all users on each auxiliary antenna.

Preferably, the

Wherein,

representing the infimum under the even number value;

alternatively, the K' = K-M + 1.

Preferably, step a further comprises: and setting the mapping relation between each training sequence offset obtained by aiming at different odd values of K' and the spread spectrum code resource used for transmitting the user signal.

Preferably, the step a is executed in the base station, and the step B is executed in the terminal;

before the step A, the method further comprises the following steps: the base station controller indicates the value of M and the value of K' to the base station;

before the step B, further comprising: the base station controller indicates the value of M and the value of K' to the terminal;

the base station and the terminal are according to the formula

Determining the value of K, wherein,

indicating that the supremum is taken to be even.

Preferably, the K' training sequence offsets are: the first K' of the K resulting training sequence offsets are shifted in order.

The base station in the multi-antenna downlink system provided by the invention comprises:

a training sequence distribution module, which is used for shifting the basic training sequence to generate K training sequence offsets, selecting K' training sequence offsets from the K training sequence offsets to distribute to a main antenna set in M antennas, wherein each user on the main antenna uses one training sequence offset; distributing a training sequence offset for each of M-1 auxiliary antennas set in the M antennas from the rest training sequence offsets, wherein K' users on each auxiliary antenna share one training sequence offset; wherein K, M and K 'are both integers greater than 0, and K' + M-1 is less than or equal to K;

a signal transmission module, configured to send a signal to a terminal on the M antennas according to the allocation result of the training sequence allocation module, where the signal transmission module is configured to calculate, for the terminal, a channel estimation of each user on the main antenna according to a training sequence offset corresponding to each user in the K' training sequence offsets; according to the channel estimation result of each user on the main antenna, the transmitting power proportion of each user is obtained, for the signal from each auxiliary antenna, the channel estimation total value of all users on the auxiliary antenna is calculated according to the training sequence offset distributed to the auxiliary antenna, and the channel estimation of each user on the auxiliary antenna is calculated according to the channel estimation total value and the transmitting power proportion of each user.

Preferably, the base station further comprises: and the information receiving module is used for receiving the indication information which comprises the value of M and the value of K 'from the base station controller and providing the value of M and the value of K' to the training sequence distribution module.

Preferably, theWherein,representing the infimum under the even number value;

alternatively, the K' = K-M + 1.

The terminal in the multi-antenna downlink system provided by the invention comprises:

the main antenna channel estimation module is used for calculating the channel estimation of each user on the main antenna according to the training sequence offset corresponding to each user for the signal from the main antenna;

the auxiliary antenna channel estimation module is used for obtaining the transmitting power proportion of each user according to the channel estimation result of each user on the main antenna; calculating the total channel estimation value of all users on each auxiliary antenna according to the training sequence offset distributed to the auxiliary antenna for the signal from each auxiliary antenna, and calculating the channel estimation of each user on each auxiliary antenna according to the total channel estimation value and the transmitting power proportion of each user;

the signal from the primary antenna and the signal from each secondary antenna are generated by the base station according to the following method: shifting a basic training sequence to generate K training sequence offsets, selecting K' training sequence offsets from the K training sequence offsets to distribute to a main antenna set in M antennas, wherein each user on the main antenna uses one training sequence offset; distributing a training sequence offset for each of M-1 auxiliary antennas set in the M antennas from the rest training sequence offsets, wherein K' users on each auxiliary antenna share one training sequence offset; wherein K, M and K 'are both integers greater than 0, and K' + M-1 is less than or equal to K.

Preferably, the secondary antenna channel estimation module includes:

the power proportion calculation submodule is used for obtaining the transmitting power proportion of each user according to the channel estimation result of each user on the main antenna;

a channel estimation total value calculation submodule for calculating the channel estimation total value of all users on each auxiliary antenna according to the training sequence offset distributed to the auxiliary antenna for the signal from each auxiliary antenna;

and the channel estimation calculation submodule is used for calculating the channel estimation of each user on each auxiliary antenna according to the transmitting power proportion of each user obtained by the power proportion calculation submodule and the channel estimation total value of all the users on each auxiliary antenna calculated by the channel estimation total value calculation submodule.

The channel estimation system in the multi-antenna downlink system provided by the invention comprises:

the base station is used for shifting the basic training sequence to generate K training sequence offsets, selecting K 'training sequence offsets from the K training sequence offsets and distributing the K' training sequence offsets to a main antenna set in M antennas, wherein each user on the main antenna uses one training sequence offset; distributing a training sequence offset for each of M-1 auxiliary antennas set in the M antennas from the rest training sequence offsets, wherein K' users on each auxiliary antenna share one training sequence offset; wherein K, M and K 'are both integers greater than 0, and K' + M-1 is less than or equal to K;

the terminal is used for calculating the channel estimation of each user on the main antenna according to the training sequence offset corresponding to each user in the K' training sequence offsets of the signals from the main antenna; according to the channel estimation result of each user on the main antenna, the transmitting power proportion of each user is obtained, for the signal from each auxiliary antenna, the channel estimation total value of all users on the auxiliary antenna is calculated according to the training sequence offset distributed to the auxiliary antenna, and the channel estimation of each user on the auxiliary antenna is calculated according to the channel estimation total value and the transmitting power proportion of each user.

It can be seen from the above scheme that, in the present invention, K training sequence offsets are generated by a basic training sequence cyclic shift, K' training sequence offsets are selected from the K training sequence offsets and allocated to a main antenna set in M antennas, and each user on the main antenna uses one training sequence offset; distributing a training sequence offset for M-1 auxiliary antennas set in M antennas from the rest training sequence offsets, wherein K 'users on each auxiliary antenna share one training sequence offset, and calculating the channel estimation of each user on the main antenna according to the channel estimation method in the single-antenna system in the prior art by aiming at the signals from the main antenna, namely according to the training sequence offsets corresponding to each user in the K' training sequence offsets; considering the characteristics that the channel conditions experienced by the signals of each user are the same and the transmission power is different when the signals are transmitted, particularly when the downlink signals are transmitted, the total channel estimation value of all the users on the auxiliary antenna is calculated according to the training sequence offset allocated to the auxiliary antenna, the transmission power proportion of each user is obtained according to the channel estimation result of each user on the main antenna, and the channel estimation of each user on each auxiliary antenna is calculated according to the transmission power proportion and the total channel estimation value of all the users on each auxiliary antenna, namely, the user data which can be supported in the scheme is the user data which can be supported on the main antenna, namely K' users.

Drawings

FIG. 1 is a diagram illustrating a slot format of a signal frame in the prior art;

fig. 2 is an exemplary flowchart of a channel estimation method in a multi-antenna system according to an embodiment of the present invention;

fig. 3a to fig. 3g are schematic diagrams of mapping relationships when K' takes values of 15, 13, 11, 9, 7, 5, and 3, respectively, in an embodiment of the present invention;

fig. 4 is an exemplary structural diagram of a channel estimation system in a multi-antenna system in an embodiment of the present invention;

FIG. 5 is a schematic diagram of an internal structure of a base station according to an embodiment of the present invention;

fig. 6 is a schematic diagram of an internal structure of a terminal according to an embodiment of the present invention;

fig. 7 is a schematic diagram of an internal structure of the auxiliary antenna channel estimation module in the terminal shown in fig. 6.

Detailed Description

In the invention, considering that the channel conditions experienced by each user signal are the same and the transmitting power is different when the signal is sent, especially when the downlink signal is sent, one antenna in a plurality of antennas can be used as a main antenna to distribute a plurality of training sequence offsets for the main antenna so as to support more users, and other antennas are used as auxiliary antennas to distribute one training sequence offset for each auxiliary antenna; then, for the signal from the main antenna, calculating the channel estimation of each user on the main antenna according to the channel estimation method in the single antenna system in the prior art; for the signal from each auxiliary antenna, the total channel estimation value of all users on the auxiliary antenna is calculated according to the training sequence offset distributed to the auxiliary antenna, and because the transmitting power proportion of the users on each antenna is the same, the transmitting power proportion of each user can be obtained according to the channel estimation result of each user on the main antenna, and the channel estimation of each user on each auxiliary antenna is calculated according to the transmitting power proportion and the total channel estimation value of all users on each auxiliary antenna.

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to the following embodiments and the accompanying drawings.

Fig. 2 is an exemplary flowchart of a channel estimation method in a multi-antenna system according to an embodiment of the present invention. In this embodiment, it is assumed that M antennas are used for signal transmission, one antenna of the M antennas is used as a main antenna, and the other M-1 antennas are used as auxiliary antennas, and it is assumed that K training sequence offsets are total after a basic training sequence is shifted according to a predetermined shift interval, as shown in fig. 2, the process includes the following steps:

step 201, generating K training sequence offsets from a basic training sequence cyclic shift, selecting K 'training sequence offsets from the K training sequence offsets, and allocating the K' training sequence offsets to a main antenna set in M antennas, wherein each user on the main antenna uses one training sequence offset; and respectively allocating a training sequence offset to M-1 auxiliary antennas set in the M antennas from the rest training sequence offsets, wherein K' users on each auxiliary antenna share one training sequence offset. Wherein K, M and K 'are both integers greater than 0, and K' + M-1 is less than or equal to K.

In this step, the CIR window length can be determined according to the number M of the antennas and the number K' of users on the M antennas; and shifting the basic training sequence according to the window length to obtain K training sequence offsets, wherein K = K' + M-1.

Step 202, calculating the channel estimation of each user on the main antenna according to the training sequence offset corresponding to each user in the K' training sequence offsets of the signals from the main antenna; according to the channel estimation result of each user on the main antenna, the transmitting power proportion of each user is obtained, for the signal from each auxiliary antenna, the channel estimation total value of all users on the auxiliary antenna is calculated according to the training sequence offset distributed to the auxiliary antenna, and the channel estimation of each user on the auxiliary antenna is calculated according to the channel estimation total value and the transmitting power proportion of each user.

Step 201 in this embodiment may be performed in the base station, and then the base station may transmit signals on M antennas according to the above assignment result of the midamble shifts, where on the primary antenna, each user uses a different midamble shift, and in the secondary antenna, each user uses the same midamble shift.

One antenna of the M antennas is used as a main antenna, and other M-1 antennas are used as auxiliary antennas in various ways, wherein one antenna of the M antennas can be statically set as the main antenna in advance, and the other antennas are auxiliary antennas; one antenna in the M antennas can be dynamically set as a main antenna and the other antennas can be set as auxiliary antennas according to a preset period, a preset condition, a random selection mode and the like; or may be otherwise arranged.

The method of selecting K' midamble shifts from the K midamble shifts to allocate to the main antenna set in the M antennas may have at least two schemes:

the first scheme is as follows:

according to the default midamble allocation scheme in the prior art, one value sequence of K is 16, 14, 12, 10, 8, 6, 4, 2. In this scheme, if the value of K ' is still selected according to the value sequence, since M-1 training sequence offsets among the K training sequence offsets need to be allocated to the auxiliary antenna, the number of training sequence offsets K ' on the main antenna must be selected from even values smaller than K, and table 1 shows values of K ' under different values of K and M in the first embodiment.

TABLE 1

As can be seen from table 1, for the case where M is an even number, K-K '> M-1, and therefore, there are various ways of selecting M-1 midamble shifts from the remaining K-K' midamble shifts; for the case where M is odd, K-K '= M-1, so the remaining K-K', i.e., M-1 training sequence offsets can be directly allocated to the secondary antennas.

Therefore, in the scheme, the method has the advantages that,

wherein,

indicating that even values are infinitesimally bounded.

In this embodiment, preferably, the K 'midamble shifts may be first K' midamble shifts from the K midamble shifts obtained by sequential shifting.

In the prior art, in order to enable a receiving end to analyze a signal from a transmitting end, a mapping relationship between a default midamble shift and spreading code resources is preset, and the receiving end can find a midamble corresponding to each user according to the mapping relationship and the spreading code resources for transmitting a user signal. In the scheme, the value of K 'is a value in a value sequence {16, 14, 12, 10, 8, 6, 4, 2} of K in the prior art, and if K' training sequence offsets are the first K 'training sequence offsets in the K training sequence offsets obtained by sequential shifting, the mapping relationship between each training sequence offset and the spreading code resource obtained by aiming at different values of K' can adopt a default mapping relationship in the prior art.

Scheme II:

according to the default midamble allocation scheme in the prior art, one value sequence of K is 16, 14, 12, 10, 8, 6, 4, 2. In this solution, the midamble shift on the main antenna is always allocated according to the condition of K-M +1= K ', and table 2 shows the values of K' under different values of K and M in the second embodiment.

TABLE 2

In this embodiment, preferably, the K 'midamble shifts may be first K' midamble shifts from the K midamble shifts obtained by sequential shifting.

In this scheme, the value of K' may be a value in a value sequence {16, 14, 12, 10, 8, 6, 4, 2} of K in the prior art, or an odd value other than the value sequence of K in the prior art. Therefore, in the present solution, if the K 'training sequence offsets are the first K' training sequence offsets in the K training sequence offsets obtained by sequential shifting, for the case that the value of K 'is an even number, the mapping relationship between each training sequence offset and the spreading code resource obtained by taking values of even numbers of different K' may adopt the default mapping relationship in the prior art; for the case that the value of K 'is odd, the mapping relationship between each training sequence offset obtained for different values of K' and the spreading code resource used for transmitting the user signal needs to be preset, and the specific setting mode can be various.

Fig. 3a to 3g respectively show a mapping relationship diagram when the value of K' is 15, 13, 11, 9, 7, 5, and 3.

As shown in fig. 3a, when K' is 15, the first midamble offset m is the spreading code resource with spreading factor of 16⁽¹⁾Corresponding to the first spreading code c₁₆ ⁽¹⁾Second training sequence offset m⁽²⁾Corresponding to the second spreading code c₁₆ ⁽²⁾The third training sequence offset m⁽³⁾Corresponding to a third spreading code c₁₆ ⁽³⁾And so on until the fourteenth midamble offset m⁽¹⁴⁾Corresponding to the fourteenth spreading code c₁₆ ⁽¹⁴⁾Then, the fifteenth training sequence offset m⁽¹⁵⁾Corresponding to the fifteenth spreading code c₁₆ ⁽¹⁵⁾And a sixteenth spreading code c₁₆ ⁽¹⁶⁾。

As shown in fig. 3b, when K' is 13, the first midamble offset m is the spreading code resource with spreading factor of 16⁽¹⁾Corresponding to the first spreading code c₁₆ ⁽¹⁾Second training sequence offset m⁽²⁾Corresponding to the second spreading code c₁₆ ⁽²⁾The third training sequence offset m⁽³⁾Corresponding to a third spreading code c₁₆ ⁽³⁾And so on until the tenth training sequence offset m⁽¹⁰⁾Corresponding to the tenth spreading code c₁₆ ⁽¹⁰⁾After that, the eleventh training sequence is offset by m⁽¹¹⁾Corresponding to the eleventh spread spectrumCode c₁₆ ⁽¹¹⁾And a twelfth spreading code c₁₆ ⁽¹²⁾The twelfth training sequence offset m⁽¹²⁾Corresponding to the thirteenth spreading code c₁₆ ⁽¹³⁾And a fourteenth spreading code c₁₆ ⁽¹⁴⁾Thirteenth training sequence offset m⁽¹³⁾Corresponding to the fifteenth spreading code c₁₆ ⁽¹⁵⁾And a sixteenth spreading code c₁₆ ⁽¹⁶⁾。

As shown in fig. 3c, when K' is 11, the first midamble offset m is the spreading code resource with spreading factor of 16⁽¹⁾Corresponding to the first spreading code c₁₆ ⁽¹⁾Second training sequence offset m⁽²⁾Corresponding to the second spreading code c₁₆ ⁽²⁾The third training sequence offset m⁽³⁾Corresponding to a third spreading code c₁₆ ⁽³⁾And so on until the sixth midamble offset m⁽⁶⁾Corresponding to the sixth spreading code c₁₆ ⁽⁶⁾Then, a seventh training sequence offset m⁽⁷⁾Corresponding to the seventh spreading code c₁₆ ⁽⁷⁾And eighth spreading code c₁₆ ⁽⁸⁾The eighth training sequence offset m⁽⁸⁾Corresponding to the ninth spreading code c₁₆ ⁽⁹⁾And a tenth spreading code c₁₆ ⁽¹⁰⁾And so on until the eleventh midamble offset m⁽¹¹⁾Corresponding to the fifteenth spreading code c₁₆ ⁽¹⁵⁾And a sixteenth spreading code c₁₆ ⁽¹⁶⁾。

As shown in fig. 3d, when K' is 9, the first midamble offset m is the spreading code resource with spreading factor of 16⁽¹⁾Corresponding to the first spreading code c₁₆ ⁽¹⁾Second training sequence offset m⁽²⁾Corresponding to the second spreading code c₁₆ ⁽²⁾The third training sequence offset m⁽³⁾Corresponding to a third spreading code c₁₆ ⁽³⁾And a fourth spreading code c₁₆ ⁽⁴⁾Fourth training sequence offset m⁽⁴⁾Corresponding to the fifth spreading code c₁₆ ⁽⁵⁾And a sixth spreading code c₁₆ ⁽⁶⁾And so on until the ninth midamble offset m⁽⁹⁾Corresponding to the fifteenth spreading code c₁₆ ⁽¹⁵⁾And a sixteenth spreading code c₁₆ ⁽¹⁶⁾。

As shown in fig. 3e, when K' is 7, the first midamble offset m is the spreading code resource with spreading factor of 16⁽¹⁾Corresponding to the first spreading code c₁₆ ⁽¹⁾And a second spreading code c₁₆ ⁽²⁾Second training sequence offset m⁽²⁾Corresponding to a third spreading code c₁₆ ⁽³⁾And a fourth spreading code c₁₆ ⁽⁴⁾And so on until the sixth midamble offset m⁽⁹⁾Corresponding to the eleventh spreading code c₁₆ ⁽¹¹⁾And a twelfth spreading code c₁₆ ⁽¹²⁾Then, a seventh training sequence offset m⁽⁷⁾Corresponding to the thirteenth spreading code c₁₆ ⁽¹³⁾A fourteenth spreading code c₁₆ ⁽¹⁴⁾The fifteenth spreading code c₁₆ ⁽¹⁵⁾And a sixteenth spreading code c₁₆ ⁽¹⁶⁾。

As shown in fig. 3f, when K' is 5, the first midamble offset m is the spreading code resource with spreading factor of 16⁽¹⁾Corresponding to the first spreading code c₁₆ ⁽¹⁾And a second spreading code c₁₆ ⁽²⁾Second training sequence offset m⁽²⁾Corresponding to a third spreading code c₁₆ ⁽³⁾And a fourth spreading code c₁₆ ⁽⁴⁾The third training sequence offset m⁽³⁾Corresponding to the fifth spreading code c₁₆ ⁽⁵⁾The sixth spreading code c₁₆ ⁽⁶⁾Seventh spreading code c₁₆ ⁽⁷⁾And eighth spreading code c₁₆ ⁽⁸⁾Fourth training sequence offset m⁽⁴⁾Corresponding to the ninth spreading code c₁₆ ⁽⁹⁾The tenth spreading code c₁₆ ⁽¹⁰⁾Eleventh spreading code c₁₆ ⁽¹¹⁾And a twelfth spreading code c₁₆ ⁽¹²⁾The fifth training sequence offset m⁽⁵⁾Corresponds to the thirteenthSpreading code c₁₆ ⁽¹³⁾A fourteenth spreading code c₁₆ ⁽¹⁴⁾The fifteenth spreading code c₁₆ ⁽¹⁵⁾And a sixteenth spreading code c₁₆ ⁽¹⁶⁾。

As shown in fig. 3g, when K' is 3, the first midamble offset m is the spreading code resource with spreading factor of 16⁽¹⁾Corresponding to the first spreading code c₁₆ ⁽¹⁾A second spreading code c₁₆ ⁽²⁾A third spreading code c₁₆ ⁽³⁾And a fourth spreading code c₁₆ ⁽⁴⁾Second training sequence offset m⁽²⁾Corresponding to the fifth spreading code c₁₆ ⁽⁵⁾The sixth spreading code c₁₆ ⁽⁶⁾Seventh spreading code c₁₆ ⁽⁷⁾And eighth spreading code c₁₆ ⁽⁸⁾The third training sequence offset m⁽³⁾Corresponding to the ninth spreading code c₁₆ ⁽⁹⁾The tenth spreading code c₁₆ ⁽¹⁰⁾Eleventh spreading code c₁₆ ⁽¹¹⁾The twelfth spreading code c₁₆ ⁽¹²⁾Thirteenth spreading code c₁₆ ⁽¹³⁾A fourteenth spreading code c₁₆ ⁽¹⁴⁾The fifteenth spreading code c₁₆ ⁽¹⁵⁾And a sixteenth spreading code c₁₆ ⁽¹⁶⁾。

Step 202 in this embodiment may be executed in the terminal, and at this time, the values of M and K' in step 201 may also be notified to the base station and the terminal by the base station controller (RNC).

When the RNC informs the values of M and K 'through high-level signaling, the information field (IE) configured by the existing training sequence can be expanded, the field indicating the value of K in the existing information field is defined as the value indicating K', and the field indicating the value of M is correspondingly increased. For the K 'value in the second scheme described in step 201, the value range of K' may be further expanded to odd values, such as 15, 13, 11, 9, 7, 5, and 3, in the information field. Table 3 shows an information table obtained by extending the existing information field when the value of K' in the second scheme described in step 201 is taken.

TABLE 3

As shown in bold in table 3, the Integer odd value, i.e. Integer (1,3,5,7,9,11,13,15), is added to the training sequence configuration (Midamble configuration) field and its definition may be consistent with the case in the protocol ts25.221.note1. in this table, the bits required for the training sequence configuration will be extended from 3 to 4 in version (Release) 7, and a new field, i.e. the Number of transmit Antennas (Number of Antennas) is added as shown in bold, where the maximum Number of Antennas may be maxnumberber of Antennas.

In step 202, after obtaining the values of K' and M, the terminal can obtain the values according to

Determining the value of K, wherein,

indicating that the supremum is taken to be even.

Then, the window length W of CIR can be calculated according to the value of K and the length L of the basic training sequence, that is, the window length W of CIR can be calculated

Wherein,indicating taking an integer value infimum.

Because the receiving end can find the midamble shift corresponding to each user according to the mapping relationship between the midamble shift and the spreading codes and the spreading code resources for transmitting user signals, the midamble shift of the kth user on the main antenna can be obtained as shown in the following formula:

$m^{k,1}={(m_1^{\left(k\right)},m_2^{\left(k\right)},...,m_{L+W-1}^{\left(k\right)})}^T,k=1,...,K^{\′}$

the superposed training sequence offset received on the primary antenna can be as follows:

${\mathrm{<figure-callout\; id="1"\; label="S"\; filenames="H2009100923608E00013.png,H2009100923608E00021.png"\; state="\{\{state\}\}">S</figure-callout>}}_1=\underset{k=1}{\overset{K^{\&prime;}}{\mathrm{\&Sigma;}}}\sqrt{P_{k,1}}{m}^{k,1},k=1,...,K^{\&prime;}$

the midamble offset transmitted on the mth antenna of the M-1 secondary antennas can be represented as follows:

$S_m=\underset{k=1}{\overset{K^{\&prime;}}{\mathrm{\&Sigma;}}}\sqrt{P_{k,m}}{m}^m=m^m\underset{k=1}{\overset{K^{\&prime;}}{\mathrm{\&Sigma;}}}\sqrt{P_{k,m}},k=1,...,K^{\&prime;},m=2,...,M$

wherein P is_k,1Is the power of user k on the main antenna, P_k，mIs the power of user k on the mth one of the M-1 auxiliary antennas, M^k，1Is the training sequence offset, m, of user k on the main antenna^mIs the midamble offset for all users on the mth antenna of the M-1 secondary antennas.

At the receiving end, the channel estimation process for all users on the main antenna is the same as the multi-user channel estimation algorithm of the single-antenna system in the prior art, the total channel estimation value with the total power of all users on the auxiliary antenna can be obtained by calculation according to the training sequence offset distributed to the auxiliary antenna, and then, the user power proportion result obtained from the main antenna can be used for distinguishing the channel estimation of each user on each auxiliary antenna.

After transmission through the multipath channel, the total received signal on each antenna can be expressed as: e = G · H + n.

Wherein, G = [ G =^(1，1)G^(2，1)…G^(K′，1)G⁽²⁾G⁽³⁾…G^(M)]，G^(k，1)Is the training sequence offset matrix, G, for the kth user on the main antenna^(m)Is the training sequence offset matrix used by all users on the mth auxiliary antenna, and has:

$G^{(k,1)}=\left[\begin{array}{cccc}{m}_W^{(k,1)}& m_{W-1}^{(k,1)}& ...& m_1^{(k,1)}\\ .& & & \\ .& m_W^{(k,1)}& ...& m_2^{(k,1)}\\ .& & & \\ .& .& & .\\ .& .& ...& .\\ .& .& & .\\ m_{W+L-1}^{(k,1)}& m_{W+L-1}^{(k,1)}& ...& m_L^{(k,1)}\end{array}\right],$ $G^{\left(m\right)}=\left[\begin{array}{cccc}{m}_W^{\left(m\right)}& m_{W-1}^{\left(m\right)}& ...& m_1^{\left(m\right)}\\ .& & & \\ .& m_W^{\left(m\right)}& ...& m_2^{\left(m\right)}\\ .& .& & .\\ .& .& & .\\ .& .& ...& .\\ .& .& & .\\ m_{W+L-1}^{\left(m\right)}& m_{W+L-2}^{\left(m\right)}& ...& m_L^{\left(m\right)}\end{array}\right]$

wherein W is the CIR window length; l is the length of the basic training sequence, e.g., L = 128; h is the channel impulse response matrix for different antennas, which can be expressed as:

$H={[\sqrt{{\mathrm{<figure-callout\; id="1"\; label="P"\; filenames="H2009100923608E00013.png,H2009100923608E00021.png"\; state="\{\{state\}\}">P</figure-callout>}}_{\mathrm{1,1}}}{h}^{\left(\mathrm{1,1}\right)}...\sqrt{P_{K^{\&prime;},1}}{h}^{(K^{\&prime;},1)}\underset{k=1}{\overset{K^{\&prime;}}{\mathrm{\&Sigma;}}}\sqrt{P_{k,2}}{h}^{\left(2\right)}...\underset{k=1}{\overset{K^{\&prime;}}{\mathrm{\&Sigma;}}}\sqrt{P_{k,M}}{h}^{\left(M\right)}]}^T$

wherein,

(K =1, …, K') is the channel impulse response of the kth user on the primary antenna,

is the channel impulse response on the mth auxiliary antenna. Thus, the sizes of G and H are L × (K '+ M-1) W and (K' + M-1) W × 1, respectively.

According to the channel estimation algorithm in the prior art, Fast Fourier Transform (FFT) can be used to simplify the calculation, and the output result can be expressed as

Wherein m is_LIs the basic training sequence of a cell. Then, the channel estimation of all K' users on the main antenna and the channel estimation with the total power of all users on the auxiliary antenna are summedAll values can be obtained from

Extracting the raw materials.

From the channel estimates for all K' users on the main antenna, the transmit power ratio for each user can be calculated, expressed as:

${\mathrm{<figure-callout\; id="1"\; label="p"\; filenames="H2009100923608E00013.png,H2009100923608E00021.png"\; state="\{\{state\}\}">p</figure-callout>}}_1=\sqrt{{\mathrm{<figure-callout\; id="1"\; label="P"\; filenames="H2009100923608E00013.png,H2009100923608E00021.png"\; state="\{\{state\}\}">\; <figure-callout\; id="1"\; label="P"\; filenames="H2009100923608E00013.png,H2009100923608E00021.png"\; state="\{\{state\}\}">P</figure-callout>\; </figure-callout>}}_{\mathrm{1,1}}}/\underset{k=1}{\overset{K^{\&prime;}}{\mathrm{\&Sigma;}}}\sqrt{P_{k,1}},....,p_{K^{\&prime;}}=\sqrt{P_{K^{\&prime;},1}}/\underset{k=1}{\overset{K^{\&prime;}}{\mathrm{\&Sigma;}}}\sqrt{P_{k,1}}$

since the transmit power ratios of the users on each transmit antenna are the same, the channels of all K' users on each secondary antenna can be estimated:

$h^{(k,2)}=p_k\underset{k=1}{\overset{K^{\&prime;}}{\mathrm{\&Sigma;}}}\sqrt{P_{k,2}}{h}^{\left(2\right)},....,h^{(k,M)}=p_k\underset{k=1}{\overset{K^{\&prime;}}{\mathrm{\&Sigma;}}}\sqrt{P_{k,M}}{h}^{\left(M\right)}(k=\mathrm{1,2},...,K^{\&prime;})$

the channel estimation method in the multi-antenna system in the embodiment of the present invention is described in detail above, and the channel estimation system in the multi-antenna system in the embodiment of the present invention is described in detail below.

Fig. 4 is an exemplary structural diagram of a channel estimation system in a multi-antenna system according to an embodiment of the present invention. As shown in fig. 4, the system includes: a base station and a terminal.

In this embodiment, the base station may be configured to generate K training sequence offsets from a basic training sequence cyclic shift, select K 'training sequence offsets from the K training sequence offsets, and allocate the K' training sequence offsets to a main antenna set in M antennas, where each user on the main antenna uses one training sequence offset; and respectively allocating a training sequence offset to M-1 auxiliary antennas set in the M antennas from the rest training sequence offsets, wherein K ' users on each auxiliary antenna share one training sequence offset, K, M and K ' are integers which are larger than 0, and K ' + M-1 is less than or equal to K.

The terminal can be used for calculating the channel estimation of each user on the main antenna according to the training sequence offset corresponding to each user in the K' training sequence offsets for the signals from the main antenna; obtaining the transmitting power proportion of each user according to the channel estimation result of each user on the main antenna; and calculating the total channel estimation value of all users on each auxiliary antenna according to the training sequence offset distributed to the auxiliary antenna for the signal from each auxiliary antenna, and calculating the channel estimation of each user on the auxiliary antenna according to the total channel estimation value and the transmitting power proportion of each user.

The system may further include an RNC for notifying the determined value of M and the value of K' to the base station and the terminal, respectively.

When the base station in the system of this embodiment is implemented in detail, there may be multiple implementations, one of which may be as shown in fig. 5, and fig. 5 illustrates an internal structure diagram of the base station in the embodiment of the present invention. The base station may include: the device comprises a training sequence distribution module and a signal transmission module.

The training sequence distribution module is used for generating K training sequence offsets from a basic training sequence cyclic shift, selecting K 'training sequence offsets from the K training sequence offsets and distributing the K' training sequence offsets to a main antenna set in M antennas, wherein each user on the main antenna uses one training sequence offset; and respectively allocating a training sequence offset to M-1 auxiliary antennas set in the M antennas from the rest training sequence offsets, wherein K ' users on each auxiliary antenna share one training sequence offset, K, M and K ' are integers which are larger than 0, and K ' + M-1 is less than or equal to K.

And the signal transmission module is used for transmitting signals on the M antennas according to the distribution result of the training sequence distribution module. Wherein, on the main antenna, each user uses different training sequence offsets, and in the auxiliary antenna, each user uses the same training sequence offset.

If the value of M and the value of K' are notified to the base station and the terminal by the RNC, the base station may further include: and the information receiving module is used for receiving the indication information which comprises the value of M and the value of K 'from the base station controller and providing the value of M and the value of K' to the training sequence distribution module.

Consistent with the channel estimation method of the embodiments of the present invention, the system described in the present invention

Wherein,

representing the infimum under the even number value; or, K' = K-M + 1.

When the terminal in the system of this embodiment is implemented in detail, there may be multiple implementations, one of which may be as shown in fig. 6, and fig. 6 shows an internal structure diagram of the terminal in the embodiment of the present invention. The terminal may include: the device comprises a main antenna channel estimation module and an auxiliary antenna channel estimation module.

The main antenna channel estimation module is used for calculating the channel estimation of each user on the main antenna according to the training sequence offset corresponding to each user for the signal from the main antenna.

The auxiliary antenna channel estimation module is used for obtaining the transmitting power proportion of each user according to the channel estimation result of each user on the main antenna; and calculating the total channel estimation value of all users on each auxiliary antenna according to the training sequence offset distributed to the auxiliary antenna for the signal from each auxiliary antenna, and calculating the channel estimation of each user on the auxiliary antenna according to the total channel estimation value and the transmitting power proportion of each user.

In a specific implementation, the secondary antenna channel estimation module may also have multiple implementation forms, and fig. 7 shows an internal structural diagram of one implementation form. As shown in fig. 7, the secondary antenna channel estimation module may include: the device comprises a power ratio calculation sub-module, a channel estimation total value calculation sub-module and a channel estimation calculation sub-module.

The power ratio calculation submodule is used for obtaining the transmitting power ratio of each user according to the channel estimation result of each user on the main antenna.

And the channel estimation total value calculation sub-module is used for calculating the channel estimation total value of all users on each auxiliary antenna according to the training sequence offset distributed to the auxiliary antenna for the signal from each auxiliary antenna.

And the channel estimation calculation submodule is used for calculating the channel estimation of each user on each auxiliary antenna according to the transmitting power proportion of each user obtained by the power proportion calculation submodule and the channel estimation total value of all users on each auxiliary antenna calculated by the channel estimation total value calculation submodule.

In an actual MIMO system, antennas are irrelevant, antenna ports represent real antennas, and the number of the antenna ports is the number of the real antennas; for the MIMO system with the 8-antenna intelligent antenna structure, the antenna ports represent a virtual concept, the number of the antenna ports is the number of the virtual antennas, and various schemes can be provided when the virtual antennas are specifically realized. The antennas described in the present invention are actually all antenna ports, and for the purpose of simple and visual description, the present invention adopts the expression of "antenna", and in practical application, the antenna ports should be understood.

In addition, the user described in the above description of the present invention generally refers to a multiflow user (including a dual stream user), that is, a description of a case where multiflow transmission (including a dual stream transmission) is adopted by all users in a downlink system. In practical application, a situation of single-stream and dual-stream coexistence sometimes exists, and in this case, in the embodiment of the present invention, after K training sequence offsets are generated by shifting a basic training sequence, K ' training sequence offsets may be selected from the K training sequence offsets according to the number K ' of multi-stream users in a user and allocated to a main antenna set in M antennas, where the K ' multi-stream users on the main antenna use one training sequence offset respectively; and respectively allocating a training sequence offset to M-1 auxiliary antennas set in the M antennas from the rest training sequence offsets, wherein K' multi-stream users on each auxiliary antenna share one training sequence offset. Wherein K, M and K 'are both integers greater than 0, and K' + M-1 is less than or equal to K.

Then, calculating the channel estimation of each multi-stream user on the main antenna according to the training sequence offset corresponding to each multi-stream user for the signal from the main antenna; calculating the total channel estimation value of all multi-stream users on each auxiliary antenna according to the training sequence offset distributed to the auxiliary antenna for the signal from each auxiliary antenna; and calculating the channel estimation of each multi-stream user on each auxiliary antenna according to the transmitting power proportion and the total channel estimation value of all multi-stream users on each auxiliary antenna.

And shifting by the base training sequence to generate K training sequence offsets may comprise: determining the length of a CIR window according to the number M of the antennas and the number Ku of users on the M antennas; and shifting the basic training sequence according to the window length to obtain K training sequence offsets, wherein K = Ku + M-1 and Ku is greater than or equal to K'.

If the Ku users include Kd single-stream users, Kd training sequence offsets can be selected from the K training sequence offsets and distributed to Kd single-stream users on M antennas according to the number Kd of single-stream users in the users; and calculating the channel estimation of each single-stream user on each antenna according to the training sequence offset corresponding to each single-stream user for the signal from each antenna.

From the above description of the embodiments, it is clear to those skilled in the art that the present invention can be implemented by a general-purpose computer device (which can be understood as a hardware platform with certain versatility) with software added with the capability of running the software; of course, the method can also be realized by adopting a hardware design mode. In addition, the modules in the base station and the terminal in the system described in the embodiment of the present invention may also be divided in other different manners, and are not limited to the manners listed in the embodiment of the present invention. Based on this understanding, the technical solutions of the present invention may be embodied in the form of a software product, which is stored in a storage medium and includes several instructions for enabling the aforementioned general-purpose hardware platform to execute the solutions according to the embodiments of the present invention.

The above-mentioned embodiments are intended to illustrate the objects, aspects and advantages of the present invention, and it should be understood that the above-mentioned embodiments are merely preferred embodiments of the present invention, and are not intended to limit the scope of the present invention, and any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the scope of the present invention.

Claims (11)

1. A channel estimation method in a multi-antenna downlink system is characterized in that:

A. shifting a basic training sequence to generate K training sequence offsets, selecting K' training sequence offsets from the K training sequence offsets to distribute to a main antenna set in M antennas, wherein each user on the main antenna uses one training sequence offset; distributing a training sequence offset for each of M-1 auxiliary antennas set in the M antennas from the rest training sequence offsets, wherein K' users on each auxiliary antenna share one training sequence offset; wherein K, M and K 'are both integers greater than 0, and K' + M-1 is less than or equal to K;

B. calculating the channel estimation of each user on the main antenna according to the training sequence offset corresponding to each user in the K' training sequence offsets of the signals from the main antenna; calculating the total channel estimation value of all users on each auxiliary antenna according to the training sequence offset distributed to the auxiliary antenna for the signal from each auxiliary antenna;

and calculating the channel estimation of each user on each auxiliary antenna according to the transmitting power proportion and the total channel estimation value of all users on each auxiliary antenna.

2. The method of claim 1, wherein the method comprises

Wherein,

representing the infimum under the even number value;

alternatively, the K' = K-M + 1.

3. The method of claim 2, wherein step a is preceded by the further step of: and setting the mapping relation between each training sequence offset obtained by aiming at different odd values of K' and the spread spectrum code resource used for transmitting the user signal.

4. The method of claim 1, wherein step a is performed in a base station and step B is performed in a terminal;

before the step A, the method further comprises the following steps: the base station controller indicates the value of M and the value of K' to the base station;

before the step B, further comprising: the base station controller indicates the value of M and the value of K' to the terminal;

the base station and the terminalAccording to the formula

Determining the value of K, wherein,

indicating that the supremum is taken to be even.

5. The method of any one of claims 1 to 4, wherein the K' training sequence offsets are: the first K' of the K resulting training sequence offsets are shifted in order.

6. A base station in a multi-antenna downlink system, the base station comprising:

a training sequence distribution module, which is used for shifting the basic training sequence to generate K training sequence offsets, selecting K' training sequence offsets from the K training sequence offsets to distribute to a main antenna set in M antennas, wherein each user on the main antenna uses one training sequence offset; distributing a training sequence offset for each of M-1 auxiliary antennas set in the M antennas from the rest training sequence offsets, wherein K' users on each auxiliary antenna share one training sequence offset; wherein K, M and K 'are both integers greater than 0, and K' + M-1 is less than or equal to K;

a signal transmission module, configured to send a signal to a terminal on the M antennas according to the allocation result of the training sequence allocation module, where the signal transmission module is configured to calculate, for the terminal, a channel estimation of each user on the main antenna according to a training sequence offset corresponding to each user in the K' training sequence offsets; according to the channel estimation result of each user on the main antenna, the transmitting power proportion of each user is obtained, for the signal from each auxiliary antenna, the channel estimation total value of all users on the auxiliary antenna is calculated according to the training sequence offset distributed to the auxiliary antenna, and the channel estimation of each user on the auxiliary antenna is calculated according to the channel estimation total value and the transmitting power proportion of each user.

7. The base station of claim 6, wherein the base station further comprises: and the information receiving module is used for receiving the indication information which comprises the value of M and the value of K 'from the base station controller and providing the value of M and the value of K' to the training sequence distribution module.

8. Base station according to claim 6 or 7, characterized in that said

Wherein,

representing the infimum under the even number value;

alternatively, the K' = K-M + 1.

9. A terminal in a multi-antenna downlink system, the terminal comprising:

the main antenna channel estimation module is used for calculating the channel estimation of each user on the main antenna according to the training sequence offset corresponding to each user for the signal from the main antenna;

the auxiliary antenna channel estimation module is used for obtaining the transmitting power proportion of each user according to the channel estimation result of each user on the main antenna; calculating the total channel estimation value of all users on each auxiliary antenna according to the training sequence offset distributed to the auxiliary antenna for the signal from each auxiliary antenna, and calculating the channel estimation of each user on each auxiliary antenna according to the total channel estimation value and the transmitting power proportion of each user;

the signal from the primary antenna and the signal from each secondary antenna are generated by the base station according to the following method: shifting a basic training sequence to generate K training sequence offsets, selecting K' training sequence offsets from the K training sequence offsets to distribute to a main antenna set in M antennas, wherein each user on the main antenna uses one training sequence offset; distributing a training sequence offset for each of M-1 auxiliary antennas set in the M antennas from the rest training sequence offsets, wherein K' users on each auxiliary antenna share one training sequence offset; wherein K, M and K 'are both integers greater than 0, and K' + M-1 is less than or equal to K.

10. The terminal of claim 9, wherein the secondary antenna channel estimation module comprises:

the power proportion calculation submodule is used for obtaining the transmitting power proportion of each user according to the channel estimation result of each user on the main antenna;

a channel estimation total value calculation submodule for calculating the channel estimation total value of all users on each auxiliary antenna according to the training sequence offset distributed to the auxiliary antenna for the signal from each auxiliary antenna;

and the channel estimation calculation submodule is used for calculating the channel estimation of each user on each auxiliary antenna according to the transmitting power proportion of each user obtained by the power proportion calculation submodule and the channel estimation total value of all the users on each auxiliary antenna calculated by the channel estimation total value calculation submodule.

11. A channel estimation system in a multi-antenna downlink system, the system comprising:

the base station is used for shifting the basic training sequence to generate K training sequence offsets, selecting K 'training sequence offsets from the K training sequence offsets and distributing the K' training sequence offsets to a main antenna set in M antennas, wherein each user on the main antenna uses one training sequence offset; distributing a training sequence offset for each of M-1 auxiliary antennas set in the M antennas from the rest training sequence offsets, wherein K' users on each auxiliary antenna share one training sequence offset; wherein K, M and K 'are both integers greater than 0, and K' + M-1 is less than or equal to K;

the terminal is used for calculating the channel estimation of each user on the main antenna according to the training sequence offset corresponding to each user in the K' training sequence offsets of the signals from the main antenna; according to the channel estimation result of each user on the main antenna, the transmitting power proportion of each user is obtained, for the signal from each auxiliary antenna, the channel estimation total value of all users on the auxiliary antenna is calculated according to the training sequence offset distributed to the auxiliary antenna, and the channel estimation of each user on the auxiliary antenna is calculated according to the channel estimation total value and the transmitting power proportion of each user.

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