CN102195915B - Cooperative multi-point transmission method and equipment - Google Patents

Abstract

The invention discloses a coordinated multi-point transmission method and equipment thereof. The method includes weighting the data signal by using the phase adjustment value, so that the mobile terminal can combine the data signals received from a plurality of coordinated stations to form a combined signal with the maximum signal strength; and send the weighted data signal to the mobile terminal. The above technical solution enables the mobile terminal to obtain enhanced data streams constantly.

Description

Coordinated multipoint transmission method and device thereof

technical field

Embodiments of the present invention generally relate to the communication field, and more specifically, relate to a coordinated multipoint transmission method and equipment thereof.

Background technique

Coordinated multipoint (CoMP) transmission is a promising technology in Long Term Evolution-Advanced (LTE-Advanced), which can be used to effectively reduce inter-cell interference (ICI), improve cell-edge coverage, and increase system throughput quantity. Joint Transmission (JT) is one of the CoMP schemes, in which data streams are shared within a CoMP cooperating set, jointly processed by multiple cells, and sent to multiple users. Users combine signals after receiving them to increase signal power and reduce inter-cell interference.

Figure 6 shows an example of such a multi-site joint transmission. In FIG. 6 , eNB1 , eNB2 and eNB3 cooperate to provide services for UE1 in eNB1 , and eNB1 , eNB2 and eNB3 are referred to as coordinated sites. The data streams from each cooperating site are respectively weighted using a transmit precoder selected according to the local channel state (CSI) from each cooperating site to UE1. Assuming that eNB1, eNB2, and eNB3 correspond to UE1's precoders as W11, W12, and W13 respectively, if the data streams sent from each coordinated site to UE1 are the same, the signal received by UE1 can be expressed as:

Y＝(H ₁₁ W ₁₁ +H ₁₂ W ₁₂ +H ₁₃ W ₁₃ )X+NI

Wherein, X is the data stream before precoding sent from the cooperative site to UE1, and NI is the interference and noise introduced during the sending process.

In the above equation, signals from different cooperating sites have different phase information, therefore, the equivalent mixed channel H ₁₁ W ₁₁ +H ₁₂ W ₁₂ +H ₁₃ W ₁₃ is not always possible at any time Get enhanced data flow.

Contents of the invention

Embodiments of the present invention propose a coordinated multi-point transmission method and equipment thereof, so as to constantly obtain enhanced data streams.

According to one aspect of the present invention, a coordinated multipoint transmission method is provided, including performing weighting processing on data signals using phase adjustment values, so that the mobile terminal can combine data signals received from multiple coordinated sites, forming a combined signal with maximum signal strength; sending the weighted data signal to the mobile terminal.

According to another aspect of the present invention, a coordinated multipoint transmission method is provided, including receiving and combining data signals from a plurality of coordinated sites, wherein the data signals are used in each of the plurality of coordinated sites using a corresponding The phase-adjustment values of , are weighted so that the combined signal has the greatest signal strength.

According to yet another aspect of the present invention, a base station is provided, including a phase weighting unit, configured to use a phase adjustment value to perform weighting processing on data signals, so that the mobile terminal can perform a weighting process on the data signals received from multiple base stations. Combining to form a combined signal with maximum signal strength; the transceiver unit of the base station is used to send the weighted data signal to the mobile terminal.

According to still another aspect of the present invention, a mobile terminal is provided, including: a terminal transceiving unit, configured to receive and combine data signals from a plurality of coordinated sites, wherein the data signal is transmitted at each of the plurality of coordinated sites One is weighted using the corresponding phase adjustment value so that the combined signal has the maximum signal strength.

According to yet another aspect of the present invention, a coordinated multipoint transmission system is provided, including a plurality of the above-mentioned base stations and mobile terminals, and a backhaul used for communication between the base stations.

According to the technical solution disclosed in the embodiments of the present invention, after the data signal transmitted by the cooperative station reaches the mobile terminal, the combined signal obtained by the mobile terminal can reach the maximum signal strength, thereby constantly obtaining an enhanced data stream.

Description of drawings

The embodiment of the present invention is described in detail in conjunction with accompanying drawing, can better understand the present invention, wherein:

FIG. 1 shows an exemplary cell deployment and cluster structure applied by an embodiment of the present invention;

Fig. 2 shows the transmission system of the embodiment of the present invention;

FIG. 3 shows a structural block diagram of a base station according to an embodiment of the present invention;

FIG. 4 shows a structural block diagram of a mobile terminal according to an embodiment of the present invention;

Fig. 5 shows the method flowchart of the embodiment of the present invention;

Fig. 6 shows a transmission system of a prior art solution.

Detailed ways

The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, and unnecessary details and functions for the present invention will be omitted during the description to avoid confusing the understanding of the present invention.

Fig. 1 shows a cell deployment and cluster structure applied in the embodiment of the present invention. In the structure shown in Fig. 1, there are 7 stations in total (as shown by the dots in Fig. 1 ), and each station has 3 diamond-shaped cells. Three adjacent cells from different sites form a cluster (shown as the shaded area in Fig. 1). Joint transmission and joint scheduling are performed in each cluster. Those skilled in the art should understand that the structure shown in FIG. 1 is only used to conveniently and clearly illustrate the technical solutions proposed by the embodiments of the present invention, rather than limiting the application scenarios of the present invention. It can be clearly seen from the following detailed description of the embodiments of the present invention that the method and device proposed in the embodiments of the present invention are applicable to any cell deployment and cluster structure involving multiple sites.

An embodiment of the present invention proposes a transmission system, as shown in FIG. 2 , the transmission system includes multiple base stations, mobile terminals and backhauls to be described below. It should be appreciated that although three base stations eNB1, eNB2 and eNB3 and one mobile terminal UE1 are schematically shown in FIG. 2, in actual network deployment, there may be more or fewer base stations and more The communication between the mobile terminal and each base station can also be carried out in other ways.

Embodiments of the present invention provide a base station. As shown in Figure 3, the base station includes a phase weighting unit 320 for phase weighting the data signal; a base station transceiver unit 330 for processing the phase weighted data signal into a signal suitable for space wireless transmission, without limitation , the functions of the base transceiver unit 330 may include digital-to-analog conversion, frequency up-conversion, power amplification, and the like.

The base station may also include an optimal precoder 310, configured to perform optimal precoding on the data signal before performing phase weighting on the data signal, and the data signal input to the optimal precoder may have been encoded, modulated, interleaved, etc. in advance deal with.

The base transceiver unit 330 also sends the downlink reference signal to the mobile terminal and receives feedback from the mobile terminal on the downlink reference signal, which may be sent in a broadcast manner without limitation. The base station may further include an information extraction unit 340 configured to extract optimal phase adjustment value information from the feedback received by the base station transceiver unit 330 . The phase weighting unit 320 is configured to perform configuration according to the optimal phase adjustment value information, so that the signals sent subsequently are weighted with the optimal phase adjustment value. The optimal phase adjustment value information here may be the optimal phase adjustment value itself, or any numerical value that can uniquely represent the optimal phase adjustment value.

In addition, the optimal precoding information for the base station may also be included in the feedback from the mobile terminal.

Embodiments of the present invention also provide a mobile terminal. As shown in FIG. 4, the mobile terminal includes a terminal transceiving unit 410, configured to perform radio frequency processing on downlink reference signals sent by each coordinated base station. Without limitation, functions of the terminal transceiving unit 410 may include low noise amplification (LNA), frequency down conversion, analog-to-digital conversion, and the like. The phase calculation unit 420 is used to calculate the optimal phase adjustment value according to the processed signal and feed it back to the corresponding cooperative base station through the terminal transceiver unit 410. Here, the optimal phase adjustment value is the maximum received wireless signal strength. The data flow phase adjustment value of the cooperative base station.

The mobile terminal also includes a precoding determination unit 440, configured to calculate an optimal precoding matrix for each base station according to the signal processed by the terminal transceiver unit 410, and feed back the corresponding base station through the terminal transceiver unit 410.

The terminal transceiving unit 410 is also configured to perform radio frequency processing on the data signal sent by each coordinated base station, wherein the data signal is phase-weighted on each coordinated base station. The mobile terminal also includes a demodulation unit 430, configured to perform signal baseband operations on the data from the terminal transceiver unit 410, such as demodulation, deinterleaving, decoding and so on.

Although the base station and the mobile terminal in the embodiment of the present invention are described above in the form of separate functional modules, each component shown in FIG. 3 or FIG. Components can also be integrated in a chip or a device in practical applications. The base station and mobile terminal may also include any elements and devices used for other purposes.

The functions of the devices shown in FIG. 3 and FIG. 4 will be described in detail below in conjunction with FIG. 5 .

In a downlink (DL) multi-site coordinated transmission scheme, one or more inter-cell interferences become useful signals for increasing signal power. For example, in FIG. 6 , UE1 is served by three neighboring eNBs. UE1 can measure the DL channel state information (CSI) according to the DL reference signals from the three eNBs, and thus determine the optimal precoder that matches the corresponding CSI. Like the example in FIG. 6, the cooperating eNB's The optimal precoders are denoted as W11, W12 and W13, respectively. Different channels from different eNBs have different phase directions, and in the embodiment of the present invention, selecting an appropriate phase direction adjustment for each cooperating station can enhance the strength of the combined signal.

Taking the direction of the data stream of the serving base station eNB1 as a reference, assume that the angles at which the two data streams of eNB2 perform phase correction are θ ₁ and θ ₂ , and assume that the angles at which the two data streams of eNB2 perform phase correction are θ ₃ and θ ₄ .

As shown in FIG. 5, in step 510, the optimal precoder 310 in the eNB cooperates to precode the data signal, and in step 520, the phase weighting unit 320 introduces different phase correction matrices to the coded data signal, and The phase-weighted data signal and the downlink reference signal are transmitted via the base transceiver unit 330 . In step 530, the terminal transceiver unit 410 of UE1 receives and detects the data signal and the downlink reference signal, wherein the received data signal can be expressed as:

$\mathrm{<span\; class="notranslate">\; Y</span>}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 11</span>}}{\mathrm{<span\; class="notranslate">\; W</span>}}_{\mathrm{<span\; class="notranslate">\; 11</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 12</span>}}{\mathrm{<span\; class="notranslate">\; W</span>}}_{\mathrm{<span\; class="notranslate">\; 12</span>}}{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 13</span>}}{\mathrm{<span\; class="notranslate">\; W</span>}}_{\mathrm{<span\; class="notranslate">\; 13</span>}}{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}^{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; NI</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

Among them, the phase correction matrix of eNB2 is $m_{\mathrm{\&theta;}}^2=\left(\begin{array}{cc}{e}^{j{\mathrm{\&theta;}}_1}& 0\\ 0& e^{j{\mathrm{\&theta;}}_2}\end{array}\right)$

The phase correction matrix of eNB3 is $m_{\mathrm{\&theta;}}^3=\left(\begin{array}{cc}{e}^{j{\mathrm{\&theta;}}_3}& 0\\ 0& e^{j{\mathrm{\&theta;}}_4}\end{array}\right)$

In order to select the optimal phase adjustment value, in step 540, according to the formula (2), the phase calculation unit 420 calculates the maximum value for the capacity of the combined signal according to the received downlink reference signal, thereby obtaining the optimal phase adjustment value:

$\underset{<span\; class="notranslate">\; \{</span>{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; \}</span>}{\mathrm{<span\; class="notranslate">\; arg</span>}\mathrm{<span\; class="notranslate">\; max</span>}}\underset{\mathrm{<span\; class="notranslate">\; k</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}{<span\; class="notranslate">\; |</span><span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 11</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; W</span>}}_{\mathrm{<span\; class="notranslate">\; 11</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 12</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; W</span>}}_{\mathrm{<span\; class="notranslate">\; 12</span>}}\left(\begin{array}{cc}{\mathrm{<span\; class="notranslate">\; e</span>}}^{\mathrm{<span\; class="notranslate">\; j</span>}{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}& \mathrm{<span\; class="notranslate">\; 0</span>}\\ \mathrm{<span\; class="notranslate">\; 0</span>}& {\mathrm{<span\; class="notranslate">\; e</span>}}^{\mathrm{<span\; class="notranslate">\; j</span>}{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}\end{array}\right)<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 13</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; W</span>}}_{\mathrm{<span\; class="notranslate">\; 13</span>}}\left(\begin{array}{cc}{\mathrm{<span\; class="notranslate">\; e</span>}}^{\mathrm{<span\; class="notranslate">\; j</span>}{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}}& \mathrm{<span\; class="notranslate">\; 0</span>}\\ \mathrm{<span\; class="notranslate">\; 0</span>}& {\mathrm{<span\; class="notranslate">\; e</span>}}^{\mathrm{<span\; class="notranslate">\; j</span>}{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; 4</span>}}}\end{array}\right)<span\; class="notranslate">\; |</span><span\; class="notranslate">\; |</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

Wherein, the magnitude of the downlink reference signal is 1 by default. Wherein, H ₁₁ (k) represents the channel value of H ₁₁ on the kth frame or the kth carrier, and its value can be obtained by actual measurement. k is the width of the time domain or the frequency domain, and the value range of k can be a few frames in the time domain, or dozens of subcarriers in the frequency domain. Preferably, the value range of k should not be too large.

When the equation (2) obtains the maximum value, it can be considered that each optimal phase adjustment value is obtained. Preferably, the optimal phase adjustment value obtained when solving formula (2) can be selected from the following set of phase angles:

${\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; N</span>}}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ,</span><span\; class="notranslate">\; \&Center\; Dot;</span><span\; class="notranslate">\; \&Center\; Dot;</span><span\; class="notranslate">\; \&Center\; Dot;</span><span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; 4</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ,</span><span\; class="notranslate">\; \&Center\; Dot;</span><span\; class="notranslate">\; \&Center\; Dot;</span><span\; class="notranslate">\; \&Center\; Dot;</span><span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; N</span>}$

where N is the granularity of phase correction.

If N is set to 2, there are two optional phase angles, namely {+1, -1}, and each phase correction requires 1-bit feedback.

则每一个相位校正需要2比特的反馈。If N is set to 4, there are four optional phase angles, namely

Each phase correction then requires 2 bits of feedback.

If N is set to 2 ^m , m bits of feedback are required for each phase correction.

The phase calculation unit 420 feeds back the best phase adjustment value information to each cooperating eNB through the terminal radio frequency unit 410. The best phase adjustment value information can be the best phase adjustment value itself, or any information that can uniquely represent the best phase adjustment value. value.

On the user side, there are two kinds of feedback to determine the transmission weight information (precoding matrix index and/or optimal phase adjustment value):

First, determine the optimal precoder to match the local DL channel state information (CSI) from the cooperative eNB, and feed back the corresponding precoding matrix index (PMI) to its serving eNB, and then the serving eNB sends the PMI through the backhaul to other cooperative eNBs. Each coordinated eNB uses its own precoding matrix to precode the data signal in step 510 . Wherein, the optimal precoder is obtained by solving according to the channel of each cell, and the specific solution method is known to those skilled in the art, and will not be repeated here.

Second, if a phase correction algorithm is used to further enhance the received signal strength, only a small amount of additional bits are needed to feed back the adjustment of the phase direction.

After the base transceiver unit 330 of the corresponding eNB receives the feedback information, in step 550, the information extraction unit 340 extracts the optimal phase adjustment value information and/or the precoding matrix index, so that the optimal precoder unit 310 uses the precoding The coding matrix index precodes the data signal, and the phase weighting unit 320 uses the optimal phase adjustment value information to weight the precoded data signal. After the weighted data signal is processed by the respective transceiver units 330 and 410 of the corresponding eNB and UE1, in step 560 the demodulation unit 430 performs baseband signal processing, such as demodulation, deinterleaving and decoding, etc.

It should be noted that the transmission of the downlink reference signal is not necessarily related to the transmission of the data signal, so although the above description with reference to FIG. or optimal phase adjustment value) is described in a process, but those skilled in the art should know that these two processes can be independent, that is, the generation and transmission of weighting information can be performed before or during data signal transmission or any stage thereafter, and the generation and transmission of weighted information can also be realized when there is no data signal transmission.

In the following, a system-level simulation is used to evaluate the system performance of the multi-site joint transmission combined with phase correction proposed by the embodiment of the present invention.

The system consumption and policy parameters are as follows:

·Rhombic sector

·Transmitter: 4×2CL-MIMO

Receiver: MMSE detector

·Do not use HARQ

· 11 MCS types, target BLER=0.01

Proportional fair (PF) scheduler

· Channel estimation error = 3dB

· Cell edge user threshold: -1dB

· Multi-site joint transmission scheme based on single user MIMO (SU-MIMO)

・Phase correction with 1 bit feedback

· Two-stream transmission

· Codebook-based PMI selection

Table 1 System-level simulation results

Transmission scheme Average cell throughput (kbps) 5% User Throughput (kbps) SU-MIMO 9439(1.00) 177.4(1.00) Multi-site joint transmission 9477(1.00) 224.1(1.26) Multi-site joint transmission (with phase correction) 9413(1.00) 244.5(1.38)

Table 1 shows the simulation results, it can be seen that compared with single-cell SU-MIMO, the multi-site transmission scheme obtains 26% (=(224.1-177.4)/177.4) cell edge throughput gain without loss of average throughput . When the phase correction algorithm is additionally used, the multi-site joint transmission scheme can also obtain 12% (=(244.5-177.4)/177.4-26%) user throughput gain of the edge cell without losing the average cell throughput. Further simulation also shows that when the granularity (N) of phase correction increases, the system performance of multi-site joint transmission can be further improved.

Those skilled in the art should easily recognize that different steps of the above method can be implemented by programming a computer. Here, some embodiments also include machine-readable or computer-readable program storage devices (e.g., digital data storage media) and encoded machine-executable or computer-executable program instructions, wherein the instructions perform some or all of the methods described above. All steps. For example, the program storage devices may be digital memories, magnetic storage media such as a magnetic disks and magnetic tapes, hardware or optically readable digital data storage media. Embodiments also include programmed computers that perform said steps of the methods described above.

The description and drawings merely illustrate the principles of the invention. It should thus be appreciated that those skilled in the art can suggest different constructions which, although not explicitly described or shown herein, embody the principles of the invention and are included within its spirit and scope. Furthermore, all examples mentioned herein are expressly intended primarily for educational purposes only to assist the reader in understanding the principles of the invention as well as the ideas contributed by the inventors to advance the art, and should be construed as not a reference to these specifically mentioned examples. and conditional restrictions. Moreover, all statements herein referring to principles, aspects, and embodiments of the invention, as well as specific examples thereof, encompass equivalents thereof.

The above description is only used to realize the embodiment of the present invention, and those skilled in the art should understand that any modification or partial replacement that does not depart from the scope of the present invention should belong to the scope defined by the claims of the present invention. Therefore, The protection scope of the present invention should be based on the protection scope of the claims.

Claims (11)

1. a cooperative multi-point transmission method, comprising:

Use is weighted processing by the determined phase adjustment value of mobile terminal to data-signal, so that described mobile terminal can merge the data-signal receiving from a plurality of collaborative site, forms the combined signal with maximum signal;

The data-signal of processing through weighting is sent to described mobile terminal;

Wherein, by added bit, carry out the adjustment of feedback phase direction, if wherein the granularity N of phasing is set to 2 ^m, each phasing needs the feedback of m bit.

2. method according to claim 1, also comprises:

Before the described phase adjustment value of use is weighted data-signal, described data-signal is carried out to optimum precoding.

3. method according to claim 1 and 2, also comprises:

To described mobile terminal, send downlink reference signal;

Receive the feedback of described mobile terminal to described downlink reference signal, and from described feedback, extract described phase adjustment value and/or for carrying out the pre-coding matrix index of optimum precoding.

4. a cooperative multi-point transmission method, comprising:

Receive and merge the data-signal from a plurality of collaborative site, wherein, described data-signal is used and corresponding by the determined phase adjustment value of mobile terminal, has carried out weighting processing in each of described a plurality of collaborative site, so that the signal after merging has maximum signal strength signal intensity; Wherein, described mobile terminal carrys out the adjustment of feedback phase direction by added bit, if wherein the granularity N of phasing is set to 2 ^m, each phasing needs the feedback of m bit.

5. method according to claim 4, also comprises:

Receive the downlink reference signal that described a plurality of collaborative site sends;

According to described downlink reference signal, determine for each phase adjustment value and/or the pre-coding matrix index for carrying out optimum precoding in described a plurality of collaborative site in described a plurality of collaborative site;

Described phase adjustment value and/or described precoding matrix index feedback are arrived to described a plurality of collaborative site.

6. a base station, comprising:

Phase weighting unit, for using, by the determined phase adjustment value of mobile terminal, data-signal is weighted to processing, so that described mobile terminal can merge the data-signal receiving from a plurality of collaborative site, form the combined signal with maximum signal;

Base station transceiver unit, for sending to described mobile terminal by the data-signal of processing through weighting;

Wherein, described mobile terminal carrys out the adjustment of feedback phase direction by added bit, if wherein the granularity N of phasing is set to 2 ^m, each phasing needs the feedback of m bit.

7. base station according to claim 6, also comprises:

Optimum precoding unit, before data-signal being weighted at the described phase adjustment value of use, carries out optimum precoding to described data-signal.

8. according to the base station described in claim 6 or 7, wherein, described base station transceiver unit is also for sending downlink reference signal to described mobile terminal;

Described base station also comprises:

Information extraction unit for receiving the feedback of described mobile terminal to described downlink reference signal, and is extracted described phase adjustment value and/or for carrying out the pre-coding matrix index of optimum precoding from described feedback.

9. a mobile terminal, comprising:

Terminal Transmit-Receive Unit, be used for receiving and merging the data-signal from a plurality of collaborative site, wherein, described data-signal is used and corresponding by the determined phase adjustment value of described mobile terminal, has carried out weighting processing in each of described a plurality of collaborative site, so that the signal after merging has maximum signal strength signal intensity;

Wherein, described mobile terminal carrys out the adjustment of feedback phase direction by added bit, if wherein the granularity N of phasing is set to 2 ^m, each phasing needs the feedback of m bit.

10. mobile terminal according to claim 9, wherein, the downlink reference signal that described terminal Transmit-Receive Unit also sends for receiving described a plurality of collaborative site;

Described mobile terminal also comprises:

Phase place determining unit, for according to described downlink reference signal, determines for each phase adjustment value in described a plurality of collaborative site; And/or

Precoding determining unit, for according to described downlink reference signal, is identified for the pre-coding matrix index that carries out optimum precoding in described a plurality of collaborative site.

11. 1 kinds of cooperative multipoint transmission systems, comprise according to the base station described in any one in claim 6 to 8, according to the mobile terminal described in claim 9 or 10 and the backhaul for communicating by letter between described base station.

Images