JP6130719B2 - Precoding method, system and apparatus - Google Patents

Description

  The present invention relates to relay cooperative multi-antenna communication technology in wireless communication technology, and more particularly to a precoding method, system, and apparatus based on relay cooperative communication technology.

  With the continuous development of communication technology, people's demands for performance such as transmission rate, transmission reliability, resource utilization rate and communication security are increasing. As a result, the relay cooperative communication technology becomes one of important means that can improve communication quality against multipath fading.

  Multi-antenna technology and relay cooperative communication technology allow a relay node to simply amplify, compress or encode, or decode and re-encode information from the source side before transmitting it to the sink. This is the basic idea. Finally, the sink performs decoding using all received information. In such a transmission model, the relay node plays a certain role in assisting communication between the source and the sink. This provides a certain spatial diversity and improves the communication quality.

  However, in the cooperative communication system of single source / single relay / single sink, one orthogonal data transmission takes two orthogonal channels due to the simplex mode of the relay node. Such spatial diversity characteristics also reduce frequency efficiency compared to the direct transmission from source to sink taking only one orthogonal channel.

  At the Toronto Conference of the 3rd Generation Partnership Project (3GPP) in 2004, the famous Long Term Evolution (LTE) project is proposed. This is a transitional technology between 3G and 4G technologies and a global standard of 3.9G. LTE has improved and enhanced 3G air access technology, with orthogonal frequency division multiplexing (OFDM) and multiple-input multiple-output (MIMO) as the only standards for wireless network evolution, with a 20 MHz spectral bandwidth Peak rates of 326 Mbit / s and 86 Mbit / s upstream can be provided, improving cell edge user performance, increasing cell capacity, and reducing system delay. Type II relay is an important proposal for relay in LTE projects. Such a relay has no cell ID and provides diversity for the signal of the main eNB, or aims to increase cell capacity by performing cooperative transmission with the main eNB. In the type II relay scenario, a direct communication link exists between the source and sink. According to such a network topology configuration, the method of performing precoding in consideration of direct link information and relay link information is naturally applicable to a multi-source type II relay scenario. Therefore, how to perform precoding in consideration of direct link information and relay link information in such a network topology configuration is one of the problems to be solved in the current LTE project.

  Embodiments of the present invention provide a precoding method, system, and apparatus for performing precoding matrix design in consideration of direct link information and relay link information between a source and a sink in a network topology having relay nodes. ing.

  The precoding method provided in the embodiments of the present invention includes a first source to a sink, a second source to a sink, a first source to a relay node, a second source to a relay node, and a relay node. Channel status information from the sink to the first source to the sink, from the second source to the sink, from the first source to the relay node, from the second source to the relay node, and from the relay node to the sink Based on the state information, determine precoding matrices of the first source, the second source, and the relay node, respectively, and determine the determined precoding matrices of the first source, the second source, and the relay node, respectively, Feedback to the second source and the relay node, the first source, the second source and the relay node , Respectively, based on the precoding matrix of the mobile station performs precoding on transmission target data includes. Here, the first source and the second source are a first mobile terminal and a second mobile terminal, respectively, and the sink is a base station (eNodeB).

Determining channel state information from the first source to the sink, from the second source to the sink, from the first source to the relay node, from the second source to the relay node, and from the relay node to the sink is eNodeB. Assigns a reference signal channel to each of the first mobile terminal, the second mobile terminal and the relay node based on the availability of the channel, where the reference signal channel is assigned to the first mobile terminal, the second mobile terminal and the relay node. The three reference signal channels assigned to each other are orthogonal to each other, and the first mobile terminal transmits the first reference signal to the relay node and the eNodeB via the reference signal channel assigned to the local station, and the second mobile terminal The terminal transmits the second reference signal to the relay node and the eNodeB via the reference signal channel assigned to the own station. Node, the first reference signal and a second reference signal received, the channel state information H _r1 and H _r2 from the first mobile terminal and the second mobile terminal to the relay node estimated respectively, relay node, the own station A third reference signal, H _r1 and H _r2 are transmitted to the eNodeB via the reference signal channel of the first reference signal, and the eNodeB receives the first reference signal, the second reference signal, and the third reference signal based on the received first reference signal, Channel state information H _d1 , H _d1 and H _dr from the mobile terminal, the second mobile terminal and the relay node to the eNodeB are estimated, respectively, and based on the estimated channel state information H _dr from the relay node to the sink eNodeB, Extracting channel state information H _r1 and H _r2 from the first mobile terminal and the second mobile terminal to the relay node.

  Based on channel state information from the first source to the sink, from the second source to the sink, from the first source to the relay node, from the second source to the relay node, and from the relay node to the sink, the first source, the second Determining the precoding matrices of the two sources and the relay nodes, respectively, for the purpose of optimizing the total throughput between the first source, the second source and the sink, is optimized for the first source, the second source and the relay node Determining a precoding matrix of.

Ｇを固定し、第１ソースとシンクとの間の総スループットを最大化させるように、第１ソースのプリコーディング行列Ｆ_１を求めるステップＣと、
ＧおよびＦ_１を固定し、第２ソースとシンクとの間の総スループットを最大化させるように、第２ソースのプリコーディング行列Ｆ_２を求めるステップＤと、
Ｆ_１およびＦ_２を固定し、第１ソース、第２ソースとシンクとの間の総スループットを最大化させるように、中継ノードのプリコーディング行列Ｇを求めるステップＥと、
求められたＦ_１、Ｆ_２およびＧの値が収束したかどうかを判断し、求められたＦ_１、Ｆ_２およびＧの値が収束した場合、求められたＦ_１、Ｆ_２およびＧを近似最適解とし、求められたＦ_１、Ｆ_２およびＧの値が収束していない場合、ステップＣに戻るステップＦと、を含む。 Determining the precoding matrix of the first source, the second source and the relay node for the purpose of optimizing the total throughput between the first source, the second source and the sink is:
First, after decoding the second source signal, subtracting the second source signal, and then predetermining the decoding order of the sink nodes so as to decode the first source signal;
Initialize relay node precoding matrix G,

Determining a first source precoding matrix F ₁ to fix G and maximize the total throughput between the first source and sink;
Determining the second source precoding matrix F ₂ to fix G and F ₁ and maximize the total throughput between the second source and sink;
Determining F ₁ and F ₂ and determining a precoding matrix G of the relay node so as to maximize the total throughput between the first source, the second source and the sink;
To determine whether a value of the obtained _F 1, _{F 2} and G has converged, if the value of _F 1, _{F 2} and G obtained has converged, approximating the _F 1, _{F 2} and G obtained Step F which returns to Step C when the values of F ₁ , F ₂ and G obtained as the optimal solution are not converged is included.

Determining the first source precoding matrix F ₁ is:

Determining the second source precoding matrix F ₂ is:

Obtaining the precoding matrix G of the relay node

Determining whether the determined values of F ₁ , F ₂ and G have converged determines whether the determined F ₁ , F ₂ and G are

  The communication system provided in an embodiment of the present invention includes a first source, a second source, a relay node, and a sink, wherein the sink is from the first source to the sink, from the second source to the sink, Determine channel state information from the first source to the relay node, from the second source to the relay node, and from the relay node to the sink, respectively, and from the first source to the sink, from the second source to the sink, from the first source Based on the channel state information from the relay node, from the second source to the relay node, and from the relay node to the sink, the precoding matrices of the first source, the second source, and the relay node are determined, respectively. A precoding matrix of one source, a second source, and a relay node is respectively represented as a first source, a second source, and Fed back to relay node, said first source, second source and the relay node, respectively, based on the precoding matrix of the mobile station performs precoding on transmission target data.

  Here, the sink is an eNodeB, and the first source and the second source are a first mobile terminal and a second mobile terminal, respectively.

The eNodeB provided in the embodiment of the present invention is:
A reference signal channel is assigned to each of the first mobile terminal, the second mobile terminal, and the relay node based on the channel availability, and is assigned to the first mobile terminal, the second mobile terminal, and the relay node. A reference signal channel allocating means in which the three reference signal channels are orthogonal,
First reference signal receiving means for receiving the first reference signal, the second reference signal and the third reference signal transmitted by the first mobile terminal, the second mobile terminal and the relay node via their reference signal channels;
Estimating channel state information H _d1 , H _d2 and H _dr from the first mobile terminal, the second mobile terminal and the relay node to the eNodeB based on the first reference signal, the second reference signal and the third reference signal, First channel estimation means for extracting channel state information H _r1 and H _r2 from the first mobile terminal and the second mobile terminal to the relay node based on the estimated channel state information H _dr from the relay node to the sink eNodeB; ,
Based on the channel state information from the first mobile terminal to the eNodeB, from the second mobile terminal to the eNodeB, from the first mobile terminal to the relay node, from the second mobile terminal to the relay node, and from the relay node to the eNodeB, Precoding matrix design means for determining precoding matrices of one mobile terminal, second mobile terminal and relay node,
Precoding matrix feedback means for feeding back the determined precoding matrices of the first mobile terminal, the second mobile terminal and the relay node to the first mobile terminal, the second mobile terminal and the relay node, respectively.

The relay node provided in the embodiment of the present invention is:
First reference signal channel receiving means for receiving a reference signal channel assigned by the base station (eNodeB) to the own station;
Second reference signal receiving means for receiving the first reference signal and the second reference signal transmitted by the first mobile terminal and the second mobile terminal via their respective reference signal channels;
Second channel estimation means for estimating channel state information H _r1 and H _r2 from the first mobile terminal and the second mobile terminal to the relay node based on the first reference signal and the second reference signal, respectively;
First reference signal transmission for transmitting the reference signal of the own station and the channel state information H _r1 and H _r2 from the first mobile terminal and the second mobile terminal to the relay node to the eNodeB via the reference signal channel of the own station Means,
first transmission precoding matrix receiving means for receiving the precoding matrix of the own station fed back from the eNodeB and precoding the data to be transmitted based on the precoding matrix of the own station.

The mobile terminal provided in the embodiment of the present invention is:
Second reference signal channel receiving means for receiving a reference signal channel assigned by the base station (eNodeB) to the own station;
A second reference signal transmitting means for transmitting the reference signal of the local station to the relay node and the eNodeB via the reference signal channel of the local station;
second transmission precoding matrix receiving means for receiving the precoding matrix of the own station fed back from the eNodeB and precoding the data to be transmitted based on the precoding matrix of the own station.

  A precoding method, system and apparatus according to an embodiment of the present invention perform precoding matrix design in consideration of direct link information and relay link information between a source and a sink in a network topology having relay nodes. Can do.

It is a figure which shows the example of the network topology model in the Example of this invention. 3 is a flowchart of a precoding method in an embodiment of the present invention. It is a flowchart of the determination method of the channel state information in the Example of this invention. 5 is a flowchart of a precoding matrix determination method according to an embodiment of the present invention. It is a figure which shows the structure of the precoding system in the Example of this invention. It is a figure which shows the internal structure of the base station (eNodeB) in the Example of this invention. It is a figure which shows the internal structure of the relay node in the Example of this invention. It is a figure which shows the internal structure of the mobile terminal in the Example of this invention.

  In order to improve spectral efficiency and overcome the problem of reduced spectral efficiency due to the simplex characteristics of relay nodes in the prior art, in the embodiment of the present invention, two multi-antenna sources are routed through one multi-antenna relay node. It is assumed that communication is performed simultaneously with one multi-antenna sink, and the relay node performs amplification processing on the received signal and then transfers the signal to the sink.

  An example of the network topology model according to the embodiment of the present invention is as shown in FIG. As can be seen from FIG. 1, this network topology includes a first source MSa, a second source MSb, a relay node RN, and a sink eNodeB, where the first source MSa, the second source MSb, the relay node RN and the sink Each eNodeB is a multi-antenna. A direct communication link exists between the first source MSa and the second source MSb and the sink eNodeB. In this way, the first source MSa and the second source MSb can simultaneously communicate with the sink eNodeB via the relay node RN, while the first source MSa and the second source MSb are also At the same time, the information is transmitted directly to the sink eNodeB via the direct communication link with the sink, and finally the sink eNodeB is received from the first source MSa, the second source MSb and the relay node RN. All the information is decrypted to obtain information from the first source MSa and the second source MSb, respectively. In this network topology model, the transmission power of each of the first source, the second source, and the relay node is limited, so how to design a precoding matrix between the antennas of the two sources and the relay node. To maximize the total throughput between the two sources and sinks is the main problem to be solved in the embodiment of the present invention.

In order to solve this problem, an embodiment of the present invention provides a precoding method. As shown in FIG. 2, the realization flow is mainly as follows.
Step 101 for determining channel state information from the first source to the sink, from the second source to the sink, from the first source to the relay node, from the second source to the relay node, and from the relay node to the sink;
Based on channel state information from the first source to the sink, from the second source to the sink, from the first source to the relay node, from the second source to the relay node, and from the relay node to the sink, the first source, the second Determining 102 pre-coding matrices for two sources and relay nodes respectively;
Feeding back the determined first source, second source and relay node precoding matrices to the first source, second source and relay node, respectively;
Each of the first source, the second source, and the relay node includes a step 104 of performing precoding on data to be transmitted based on the precoding matrix of the local station.

  Up to this point, the above precoding process ends. Thereafter, the first mobile terminal, the second mobile terminal, and the relay node start data transmission.

  In the embodiment of the present invention, the above steps 101 to 103 can be completed by a sink or other device in the network.

  In the embodiment of the present invention, the first source and the second source may be a first mobile terminal and a second mobile terminal, respectively, and the sink may be a base station (eNodeB). In this case, the steps 101 to 103 can be completed by the eNodeB. Specifically, in this case, as shown in FIG. 3, the step 101 may specifically include the following steps.

  In step 201, the eNodeB assigns a reference signal channel to each of the first mobile terminal, the second mobile terminal, and the relay node based on channel availability, where the first mobile terminal The three reference signal channels assigned to the terminal, the second mobile terminal and the relay node are orthogonal.

In this step 201, allocating the reference signal channel to each of the first mobile terminal, the second mobile terminal, and the relay node means that the eNodeB has channel state information from the first mobile terminal and the second mobile terminal to the relay node. It is intended to obtain H _r1 and H _r2 and channel state information H _d1 , H _d2 and H _dr from the first mobile terminal, the second mobile terminal, and the relay node to the sink.

  In step 202, the first mobile terminal transmits the first reference signal to the relay node and the eNodeB via the reference signal channel assigned to the own station, and the second mobile terminal transmits the reference signal assigned to the own station. The second reference signal is transmitted to the relay node and the eNodeB via the channel.

In step 203, the relay node estimates channel state information H _r1 and H _r2 from the first mobile terminal and the second mobile terminal to the relay node based on the received first reference signal and second reference signal, respectively.

In step 204, the relay node transmits the third reference signal, H _r1 and H _r2 to the eNodeB via its own reference signal channel.

In step 205, the eNodeB, based on the received first reference signal, second reference signal, and third reference signal, channel state information H _d1 from the first mobile terminal, the second mobile terminal and the relay node to the eNodeB, H _d2 and H _dr are estimated, respectively, and based on the estimated channel state information H _dr from the relay node to the sink eNodeB, channel state information H _r1 and H _r from the first mobile terminal and the second mobile terminal to the relay node Extract _r2 .

Through the above steps 201 to 205, the eNodeB receives the channel state information H _r1 and H _r2 from the first mobile terminal and the second mobile terminal to the relay node, and from the first mobile terminal, the second mobile terminal and the relay node. Channel state information H _d1 , H _d2 and H _dr up to the sink can be obtained.

  In step 102 of the embodiment of the present invention, the precoding matrix of the first source, the second source and the relay node is determined for the purpose of optimizing the total throughput between the two sources and the sink. Can do. When the two sources are the first mobile terminal and the second mobile terminal and the sink is the base station (eNodeB), in step 102 of the embodiment of the present invention, the first mobile terminal, the second mobile terminal, and the eNodeB For the purpose of optimizing the total throughput between the first mobile terminal, the precoding matrix of the first mobile terminal, the second mobile terminal and the relay node can be determined.

  Specifically, the optimization objective function representing the optimization objective can be obtained by the following derivation process.

First, on the first orthogonal data channel, the first mobile terminal and the second mobile terminal simultaneously transmit their vector data signals x ₁ = F ₁ s ₁ and x ₂ = F ₂ s ₂ to the relay node and the eNodeB. Here, F ₁ and F ₂ represent precoding matrices of the first mobile terminal and the second mobile terminal, respectively, and s ₁ and s ₂ represent the power transmitted from the first mobile terminal and the second mobile terminal, respectively. Representing each normalized data signal, it is assumed that in the second orthogonal data channel, the relay node multiplies the received mixed data signal with the precoding matrix G and then forwards it to the eNodeB. As described, the first orthogonal data channel and the second orthogonal data channel may be time division orthogonal channels or may be frequency division orthogonal channels. Further, it is necessary to assume that the first orthogonal data channel and the second orthogonal data channel are maintained as they are in the same data transmission. Under such assumptions, the eNodeB can create a received data signal matrix based on data signals received on two orthogonal data channels, and the equation is as shown in Equation 1 below.

  Thereafter, based on the principles of Shannon information theory, the following can be obtained. That is, the maximum total throughput that two sources transmit to the sink via two orthogonal data channels is as shown in Equation 2 below.

Thus, it is stated that the above optimization objective is to find the solutions of F ₁ , F ₂ and G that maximize C _sum under the power control constraints of the first mobile terminal, the second mobile terminal and the relay node. Can do. That is, the optimization objective function that represents the optimization objective can be expressed as Equation 3 below.

Research can find that due to the non-convexity of the optimization objective function 3, it is difficult to directly obtain optimal closed-form solutions of F ₁ , F ₂ and G.

Thus, in an embodiment of the present invention, a simplified iterative method is provided that can obtain approximate optimal solutions of F ₁ , F _2, and G that satisfy the above optimization objective function.

そのため、Ｃ_１およびＣ_２の表現式に基づき、以下のソースプリコーディング行列設計を行うことができる。 First, based on the information theory, for example, after decoding the data of the second mobile terminal, after subtracting the data of the second mobile terminal, the decoding order is set so that the data of the first mobile terminal is decoded. Assuming in advance, the throughput from the first mobile terminal and the second mobile terminal to the sink is the following equation:

Therefore, the following source precoding matrix design can be performed based on the expressions of C ₁ and C ₂ .

  As shown in FIG. 4, the procedure for realizing this iterative method mainly includes the following steps.

In step 300, the eNodeB first decrypts the data of the second mobile terminal, then subtracts the data of the second mobile terminal, and then decrypts the data of the first mobile terminal,

In step 301,

In step 302, based on F ₁ obtained in step 301,

In step 303, G is obtained based on F ₁ and F ₂ obtained in steps 301 and 302, and specifically includes the following steps.

First, an equivalent equation as shown in Equation 4 below is created.

To find this problem, we need to do the following decomposition:

Further, the limit condition of the transmission power of the relay node is further equivalent as follows.

With the new power limit condition

In step 304, if the value of _F 1, _{F 2} and G obtained is determined whether the convergence, the value of _F 1, _{F 2} and G obtained has converged, the process proceeds to step 305, the determined If the values of F ₁ , F ₂ and G have not converged, return to the above step 301 and repeat.

The determination of whether or not the calculated values of F ₁ , F ₂ and G in this step have converged specifically means that the determined F ₁ , F ₂ and G are the following convergence criteria:

In step 305, the obtained F ₁ , F ₂ and G are set as approximate optimum solutions.

As described above, the approximate optimum solutions of F ₁ , F ₂ and G can be obtained by the above steps 301 to 305.

Thereafter, in step 103 of the embodiment of the present invention, the eNodeB is assigned to the first mobile terminal, the second mobile terminal, and the relay node after obtaining approximate optimal solutions of F ₁ , F ₂ and G, respectively. The obtained approximate optimum solutions of F ₁ , F ₂ and G are fed back to the first mobile terminal, the second mobile terminal and the relay node via the orthogonal reference signal channel. Next, in step 104, the first mobile terminal, the second mobile terminal, and the relay node perform precoding based on the received F ₁ , F _2, and G, respectively. Up to this point, the above precoding process ends. The first mobile terminal, the second mobile terminal and the relay node can transmit signals and start data transmission according to the precoding matrix of the local station.

As should be explained, those skilled in the art will understand that the above iterative method may be applied to any network topology configuration of multi-antenna nodes including two sources, one relay and one sink. Can do. That is, after knowing the channel state information of the source and the relay, the source and the sink, and the relay and the sink, all of the two sources and the sink The precoding matrices F ₁ , F _2, and G of the first source, the second source, and the relay node can be obtained so as to maximize the total throughput during.

  As described above, the precoding method provided in the embodiment of the present invention is a precoding matrix in a network topology having a relay node, considering direct link information and relay link information between a source and a sink. Design can be done. Also, in the precoding matrix design method according to the embodiment of the present invention, since two mobile terminals can be simultaneously serviced via two orthogonal data channels, one orthogonal data channel is averaged. The goal of serving one source user per can be achieved, and thus frequency efficiency can be improved nearly twice as compared to the conventional single source, single relay and single sink models. In addition, the precoding matrix design method according to the embodiment of the present invention can find an approximate optimum precoding matrix of a source and a relay node that maximizes the total throughput between two sources and sinks. Therefore, the total throughput between the source and the sink can be maximized under the condition that the transmission power of each of the source and the relay node is limited, which is 10% compared with the precoding matrix design method with the equal power distribution. The above throughput gain can be obtained.

  Corresponding to the above precoding method, an embodiment of the present invention provides a communication system. As shown in FIG. 5, the configuration mainly includes a first source, a second source, a relay node, and a sink.

  Here, the sink determines channel state information from the first source to the sink, from the second source to the sink, from the first source to the relay node, from the second source to the relay node, and from the relay node to the sink. The first source based on the channel state information from the first source to the sink, from the second source to the sink, from the first source to the relay node, from the second source to the relay node, and from the relay node to the sink. , Determine the precoding matrices of the second source and the relay node, respectively, and feed back the determined precoding matrices of the first source, the second source, and the relay node to the first source, the second source, and the relay node, respectively. , The first source, the second source and the relay node respectively Based on the grayed matrix, it performs precoding on transmission target data.

Here, the sink may be a base station (eNodeB), and the first source and the second source may be a first mobile terminal and a second mobile terminal. In this case, as shown in FIG. 6, the internal configuration of the eNodeB is specifically as follows:
A reference signal channel is assigned to each of the first mobile terminal, the second mobile terminal, and the relay node based on the channel availability, and is assigned to the first mobile terminal, the second mobile terminal, and the relay node. Reference signal channel allocation means 11 in which the three reference signal channels are orthogonal,
First reference signal receiving means 12 for receiving the first reference signal, the second reference signal and the third reference signal transmitted by the first mobile terminal, the second mobile terminal and the relay node via their reference signal channels;
Estimating channel state information H _d1 , H _d2 and H _dr from the first mobile terminal, the second mobile terminal and the relay node to the eNodeB based on the first reference signal, the second reference signal and the third reference signal, First channel estimation means 13 for extracting channel state information H _r1 and H _r2 from the first mobile terminal and the second mobile terminal to the relay node based on the estimated channel state information H _dr from the relay node to the sink eNodeB When,
Based on the channel state information from the first mobile terminal to the eNodeB, from the second mobile terminal to the eNodeB, from the first mobile terminal to the relay node, from the second mobile terminal to the relay node, and from the relay node to the eNodeB, Precoding matrix design means 14 for determining precoding matrices of one mobile terminal, second mobile terminal and relay node, respectively;
Precoding matrix feedback means 15 for feeding back the determined precoding matrices of the first mobile terminal, the second mobile terminal and the relay node to the first mobile terminal, the second mobile terminal and the relay node, respectively.

  As an explanation, except for the eNodeB, the sink may be another sink device such as a wireless sensor sink node.

  In the embodiment of the present invention, the precoding matrix design means 14 pre-optimizes the first mobile terminal, the second mobile terminal and the relay node for the purpose of optimizing the total throughput between the two sources and the sink. The coding matrix may be determined, or the precoding matrices of the first mobile terminal, the second mobile terminal and the relay node may be determined using an iterative method as shown in FIG.

As shown in FIG. 7, the internal configuration of the relay node is specifically as follows.
First reference signal channel receiving means 21 for receiving a reference signal channel assigned by the eNodeB to the own station;
Second reference signal receiving means 22 for receiving the first reference signal and the second reference signal transmitted by the first mobile terminal and the second mobile terminal via their reference signal channels;
Second channel estimation means 23 for estimating channel state information H _r1 and H _r2 from the first mobile terminal and the second mobile terminal to the relay node based on the first reference signal and the second reference signal,
First reference signal transmission for transmitting the reference signal of the own station and the channel state information H _r1 and H _r2 from the first mobile terminal and the second mobile terminal to the relay node to the eNodeB via the reference signal channel of the own station Means 24;
first transmission precoding matrix receiving means 25 for receiving the precoding matrix of the own station fed back from the eNodeB and precoding the data to be transmitted based on the precoding matrix of the own station.

As shown in FIG. 8, the internal configurations of the first mobile terminal and the second mobile terminal are basically the same. Specifically,
Second reference signal channel receiving means 31 for receiving a reference signal channel assigned by the eNodeB to the own station;
A second reference signal transmission means 32 for transmitting the reference signal of the local station to the relay node and the eNodeB via the reference signal channel of the local station;
and a second transmission precoding matrix receiving means 33 for receiving the precoding matrix of the own station fed back from the eNodeB and precoding the data to be transmitted based on the precoding matrix of the own station.

  Thereafter, the first mobile terminal and the second mobile terminal can start data transmission by transmitting data to the eNodeB and the relay node according to the precoding matrix of the local station.

  As described above, the precoding matrix design system and apparatus provided in the embodiments of the present invention considers direct link information and relay link information between a source and a sink in a network topology having relay nodes. Precoding matrix design can be performed. In addition, in the precoding matrix design system according to the embodiment of the present invention, since two mobile terminals can be simultaneously serviced via two orthogonal data channels, one orthogonal data channel is averaged. The goal of serving one source user per can be achieved, and thus frequency efficiency can be improved nearly twice as compared to the conventional single source, single relay and single sink models. In addition, the precoding matrix design method according to the embodiment of the present invention can find an approximate optimum precoding matrix of a source and a relay node that maximizes the total throughput between two sources and sinks. Therefore, it is possible to maximize the total throughput between the source and the sink under the condition that the total transmission power of the source and the relay node is limited, and more than 10% as compared with the precoding matrix design method of the equal power distribution Throughput gain can be obtained.

Also, as should be explained, in order to obtain better performance, the reception antenna for the mobile terminal side of the relay node is usually an omnidirectional antenna, while the transmission antenna for the eNodeB side is a directional antenna, Generally, the receiving antenna gain of the relay node is smaller than the transmitting antenna gain. However, by comparison, when the distance between the two transport terminals is relatively close and both are close to the relay node but far from the eNodeB, the receiving antenna for the mobile terminal side of the relay node adopts a directional antenna. The transmission antenna for the eNodeB side adopts an omnidirectional antenna, or adopts a directional antenna as well, that is, if a transmission antenna and a reception antenna having higher gain are adopted, better performance is obtained. Can be found. Based on the above research, the method according to the above embodiments can be further improved. For example, when executing step 101, the first source to the sink, the second source to the sink, and the first source to the relay Determine channel state information H _r1 , H _r2 , H _d1 , H _d2 and H _dr from the second source to the relay node, and from the relay node to the sink, to the first source, the second source and the relay After determining the precoding matrix of the node, switching the transmit and receive antennas of the relay node to replace the same channel information, again from the first source to the relay node, from the second source to the relay node, and the channel state information _{H r1} from the relay node to the sink _{', H r2'} to determine and _{H dr} ', thus The first source in the case, it is necessary to determine the precoding matrix of the second source and the relay node. A set of precoding matrices with better performance (ie, greater total throughput) is then selected based on the throughput and fed back to the first source, the second source and the relay node.

  The above are only preferred embodiments of the present invention and do not limit the present invention. Various modifications, equivalent replacements, improvements and the like made within the spirit and principle of the present invention should all be included in the protection scope of the present invention.

11 Reference signal channel allocation means 12 First reference signal reception means 13 First channel estimation means 14 Precoding matrix design means 15 Precoding matrix feedback means 21 First reference signal channel reception means 22 Second reference signal reception means 23 Second channel Estimating means 24 First reference signal transmitting means 25 First transmission precoding matrix receiving means 31 Second reference signal channel receiving means 32 Second reference signal transmitting means 33 Second transmission precoding matrix receiving means

Claims (14)

A precoding method,
Determining channel state information from the first source to the sink, from the second source to the sink, from the first source to the relay node, from the second source to the relay node, and from the relay node to the sink;
Based on channel state information from the first source to the sink, from the second source to the sink, from the first source to the relay node, from the second source to the relay node, and from the relay node to the sink, the first source, the second Determine the precoding matrices of the two sources and relay nodes respectively;
Feedback the determined precoding matrices of the first source, the second source and the relay node to the first source, the second source and the relay node, respectively;
Each of the first source, the second source, and the relay node performs precoding on data to be transmitted based on the precoding matrix of the local station.
A precoding method characterized by comprising: The first source and the second source are a first mobile terminal and a second mobile terminal, respectively, and the sink is a base station (eNodeB).
The precoding method according to claim 1, wherein: Determining channel state information from the first source to the sink, from the second source to the sink, from the first source to the relay node, from the second source to the relay node, and from the relay node to the sink;
The eNodeB allocates a reference signal channel to each of the first mobile terminal, the second mobile terminal, and the relay node based on channel availability, where the eNodeB assigns the first mobile terminal, the second mobile terminal, and the relay node The three reference signal channels assigned to it are orthogonal,
The first mobile terminal transmits the first reference signal to the relay node and the eNodeB via the reference signal channel assigned to the local station,
The second mobile terminal transmits the second reference signal to the relay node and the eNodeB via the reference signal channel assigned to the local station,
The relay node estimates channel state information H _r1 and H _r2 from the first mobile terminal and the second mobile terminal to the relay node based on the received first reference signal and second reference signal,
The relay node transmits the third reference signal, H _r1 and H _r2 to the eNodeB via its own reference signal channel,
Based on the received first reference signal, second reference signal and third reference signal, the eNodeB receives channel state information H _d1 , H _d2 and H from the first mobile terminal, the second mobile terminal and the relay node to the eNodeB. Each of _dr is estimated, and channel state information H _r1 and H _r2 from the first mobile terminal and the second mobile terminal to the relay node are extracted based on the estimated channel state information H _dr from the relay node to the sink eNodeB. ,
The precoding method according to claim 2, further comprising: Based on the channel state information from the first source to the sink, from the second source to the sink, from the first source to the relay node, from the second source to the relay node, and from the relay node to the sink, the first source, Determining the second source and relay node precoding matrices, respectively,
Determining the precoding matrices of the first source, the second source and the relay node for the purpose of optimizing the total throughput between the first source, the second source and the sink;
The precoding method according to claim 1 or 2, further comprising: Determining the precoding matrix of the first source, the second source and the relay node for the purpose of optimizing the total throughput between the first source, the second source and the sink is:
First, after decoding the second source signal, subtracting the second source signal, and then predetermining the decoding order of the sink nodes so as to decode the first source signal;
Initialize relay node precoding matrix G,

Step B to
Determining a first source precoding matrix F ₁ to fix G and maximize the total throughput between the first source and sink;
Determining the second source precoding matrix F ₂ to fix G and F ₁ and maximize the total throughput between the second source and sink;
Determining F ₁ and F ₂ and determining a precoding matrix G of the relay node so as to maximize the total throughput between the first source, the second source and the sink;
To determine whether a value of the obtained _F 1, _{F 2} and G has converged, if the value of _F 1, _{F 2} and G obtained has converged, approximating the _F 1, _{F 2} and G obtained the optimum solution, when the value of F _1, F ₂ and G obtained has not converged, the step F back to step C,
The precoding method according to claim 4, further comprising: Determining the first source precoding matrix F ₁ is:

The precoding method according to claim 5, wherein: Determining the second source precoding matrix F ₂ is:

The precoding method according to claim 5, wherein: Obtaining the precoding matrix G of the relay node

The precoding method according to claim 5, wherein: It is determined whether the calculated values of F ₁ , F ₂ and G have converged by determining whether the calculated F ₁ , F ₂ and G are the following convergence criteria:

The precoding method according to claim 5, wherein: A communication system,
Including a first source, a second source, a relay node and a sink, wherein
The sink determines channel state information from the first source to the sink, from the second source to the sink, from the first source to the relay node, from the second source to the relay node, and from the relay node to the sink, respectively. Based on channel state information from the first source to the sink, from the second source to the sink, from the first source to the relay node, from the second source to the relay node, and from the relay node to the sink, the first source, the second Determining two source and relay node precoding matrices respectively, and feeding back the determined first source, second source and relay node precoding matrices to the first source, second source and relay node, respectively;
Each of the first source, the second source, and the relay node performs precoding on data to be transmitted based on a precoding matrix of the local station.
A communication system characterized by the above. The sink is a base station (eNodeB), and the first source and the second source are a first mobile terminal and a second mobile terminal, respectively.
The communication system according to claim 10. A base station (eNodeB),
A reference signal channel is assigned to each of the first mobile terminal, the second mobile terminal, and the relay node based on the channel availability, and is assigned to the first mobile terminal, the second mobile terminal, and the relay node. A reference signal channel allocating means in which the three reference signal channels are orthogonal,
First reference signal receiving means for receiving the first reference signal, the second reference signal and the third reference signal transmitted by the first mobile terminal, the second mobile terminal and the relay node via their reference signal channels;
Estimating channel state information H _d1 , H _d2 and H _dr from the first mobile terminal, the second mobile terminal and the relay node to the eNodeB based on the first reference signal, the second reference signal and the third reference signal, First channel estimation means for extracting channel state information H _r1 and H _r2 from the first mobile terminal and the second mobile terminal to the relay node based on the estimated channel state information H _dr from the relay node to the sink eNodeB; ,
Based on the channel state information from the first mobile terminal to the eNodeB, from the second mobile terminal to the eNodeB, from the first mobile terminal to the relay node, from the second mobile terminal to the relay node, and from the relay node to the eNodeB, Precoding matrix design means for determining precoding matrices of one mobile terminal, second mobile terminal and relay node,
Precoding matrix feedback means for feeding back the determined precoding matrices of the first mobile terminal, the second mobile terminal and the relay node to the first mobile terminal, the second mobile terminal and the relay node, respectively;
A base station comprising: A relay node,
First reference signal channel receiving means for receiving a reference signal channel assigned by the base station (eNodeB) to the own station;
Second reference signal receiving means for receiving the first reference signal and the second reference signal transmitted by the first mobile terminal and the second mobile terminal via their respective reference signal channels;
Second channel estimation means for estimating channel state information H _r1 and H _r2 from the first mobile terminal and the second mobile terminal to the relay node based on the first reference signal and the second reference signal, respectively;
First reference signal transmission for transmitting the reference signal of the own station and the channel state information H _r1 and H _r2 from the first mobile terminal and the second mobile terminal to the relay node to the eNodeB via the reference signal channel of the own station Means,
first transmission precoding matrix receiving means for receiving the precoding matrix of the own station fed back from the eNodeB and precoding the data to be transmitted based on the precoding matrix of the own station;
A relay node characterized by including: A mobile terminal,
Second reference signal channel receiving means for receiving a reference signal channel assigned by the base station (eNodeB) to the own station;
A second reference signal transmitting means for transmitting the reference signal of the local station to the relay node and the eNodeB via the reference signal channel of the local station;
second transmission precoding matrix receiving means for receiving the precoding matrix of the own station fed back from the eNodeB and precoding the data to be transmitted based on the precoding matrix of the own station;
A mobile terminal comprising:

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