WO2013000173A1 - 一种上行多用户协同通信的方法 - Google Patents
一种上行多用户协同通信的方法 Download PDFInfo
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- WO2013000173A1 WO2013000173A1 PCT/CN2011/076739 CN2011076739W WO2013000173A1 WO 2013000173 A1 WO2013000173 A1 WO 2013000173A1 CN 2011076739 W CN2011076739 W CN 2011076739W WO 2013000173 A1 WO2013000173 A1 WO 2013000173A1
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B7/00—Radio transmission systems, i.e. using radiation field
- H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
- H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
- H04B7/0413—MIMO systems
- H04B7/0456—Selection of precoding matrices or codebooks, e.g. using matrices antenna weighting
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B7/00—Radio transmission systems, i.e. using radiation field
- H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
- H04B7/022—Site diversity; Macro-diversity
- H04B7/026—Co-operative diversity, e.g. using fixed or mobile stations as relays
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/06—Receivers
- H04B1/10—Means associated with receiver for limiting or suppressing noise or interference
- H04B1/1027—Means associated with receiver for limiting or suppressing noise or interference assessing signal quality or detecting noise/interference for the received signal
- H04B1/1036—Means associated with receiver for limiting or suppressing noise or interference assessing signal quality or detecting noise/interference for the received signal with automatic suppression of narrow band noise or interference, e.g. by using tuneable notch filters
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B7/00—Radio transmission systems, i.e. using radiation field
- H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
- H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
- H04B7/0413—MIMO systems
- H04B7/0417—Feedback systems
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B7/00—Radio transmission systems, i.e. using radiation field
- H04B7/14—Relay systems
- H04B7/15—Active relay systems
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W88/00—Devices specially adapted for wireless communication networks, e.g. terminals, base stations or access point devices
- H04W88/02—Terminal devices
- H04W88/04—Terminal devices adapted for relaying to or from another terminal or user
Definitions
- the present invention relates to the field of wireless communication technologies, and in particular, to a method for uplink multi-user cooperative communication.
- Uplink multi-user cooperative communication provides a means of utilizing spatial resources, and multiple participating entities share limited resources through cooperation to improve the utilization of wireless resources.
- Uplink multi-user cooperative communication is more common in traditional mobile communication cellular networks.
- the role of each node in the whole signal transmission process is fixed and single, and the division of labor between transmission and signal processing of various types of nodes is clear. In practical systems, this explicit division of labor is closely related to system requirements such as geographic location and node configuration of each node:
- the source node generally corresponding to the mobile station (MS) in the uplink, is distributed in various locations in the cell, and also has certain mobility characteristics. Due to the portability of the user and the size of the device, the mobile station has certain difficulties in configuring the high-order antenna. Therefore, the number of antenna elements is small, the transmission power is relatively small, and the signal processing complexity on the source node side cannot be too high. Due to the confidentiality of the information communicated by the mobile station users, multiple source nodes cannot transmit signals to each other.
- relay node corresponding to a relay station (relay node) installed in a traditional mobile communication cell
- the location of the relay site is relatively fixed, especially when it is required to be installed in certain areas or when access density is high.
- the relay node needs to have certain signal processing capability, and its signal processing complexity is between the source node and the target node. Since the relay node mostly performs signal processing operations, the implementation of the upper layer protocol is not as good as the mobile node.
- the station is as important as the base station.
- the target node corresponding to a base station (BS) in a traditional mobile communication cellular network, is generally installed at a fixed position in the cell, and is limited by size and transmission power, and can be equipped with a high-order antenna and has a high Signal processing complexity.
- the base station should have strong multi-stream detection processing capability to distinguish multiple data streams of multiple mobile station users accessing the uplink.
- the capacity potential of cooperative communication has not been fully developed and used so far.
- the relative fixedness of relay nodes occupies limited resources of system communication. How to liberate relay nodes has become an urgent problem to be solved.
- the precoding technique can effectively improve the spectrum efficiency of the system by utilizing the channel state information. Therefore, how to improve the system capacity, throughput and reduce the bit error rate by designing appropriate precoding becomes another problem to be solved.
- the technical problem to be solved by the present invention is to provide an uplink multi-user cooperative communication method, which effectively improves system capacity, throughput, and reduces the block error rate.
- a method for uplink multi-user cooperative communication of the present invention is applied to a system including at least a first source node, a second source node, and a target node, where the first source node and the second source node are present. a direct transmission link between the target nodes.
- the method includes the following steps: when the first source node sends a signal to the target node, the second source node is converted to the relay of the first source node.
- the target node obtains a receiving signal of the target node according to a signal directly sent by the first source node and a signal forwarded by the second source node by using a maximum ratio combining manner
- the noise ratio, the distributed precoding strategy is set according to the received signal to noise ratio, and the optimal precoding is selected according to the real-time channel condition as a precoding vector used when the first source node sends a signal to the target node.
- the step is also sent to the second source node, where: the first source node performs precoding processing on the signal with the initially set first precoding vector.
- the first precoding vector uses a first right singular vector of the channel transfer matrix of the direct transmission link between the first source node and the target node.
- the first right singular vector of the channel transfer matrix is obtained by performing decomposition singular value decomposition on a channel transfer matrix of a direct transmission link between the first source node and the target node.
- the target node and the second source node respectively receive the signal sent by the first source node by using a matched filtering manner. Further, the first source node and the second source node both transmit signals by using a closed loop transmission manner. Further, the step of converting the second source node to the relay node of the first source node, and forwarding the signal to the target node, includes: the second source node normalizing the received signal, and initializing The set second precoding vector is precoded and forwarded to the target node, and the second precoding vector uses the first right singular vector of the channel transfer matrix of the direct transmission link between the second source node and the target node.
- the first right singular vector of the channel transfer matrix is obtained by performing decomposition singular value decomposition on a channel transfer matrix of a direct transmission link between the second source node and the target node.
- the normalizing operation of the received signal by the second source node includes: setting an amplifying forwarding coefficient, so that the signal forwarded by the second source node satisfies a normalization condition.
- the step of converting the second source node to the relay node of the first source node, forwarding the signal to the target node further includes: channel transfer of the direct transmission link between the second source node and the target node
- the matrix is decomposed by singular value to obtain a U-matrix, and the target node receives the signal forwarded by the second source node by using the conjugate transposition vector of the first column of the U-array.
- the step of selecting the optimal precoding as the precoding vector used when the first source node transmits the signal includes: selecting the optimal precoding as the first precoding vector; selecting the optimal precoding as the first source After the step of transmitting a precoding vector used by the node, the method further includes: acquiring, according to the optimal precoding, a received signal to noise ratio of the target node under a current channel condition.
- the source nodes Before the transmission process, there is no need to set a fixed relay node in the network.
- the relationship between the two source nodes is equivalent, and each information needs to be transmitted to the target node.
- the source nodes can form a cooperative relationship and bear each other.
- the relay node of the source node signal can communicate with each other.
- the source node can communicate with each other. Because the source node has a cooperative relationship, the transmission role of the source node of the present invention is not fixed. In some specific transmission phases, the source node can serve as a temporary medium. Following the node, this way can effectively improve system capacity, throughput and reduce bit error rate.
- 1 is a schematic diagram of a wireless communication system to which the present invention is applicable.
- 2 is a flowchart of a method of an overall scheme according to an embodiment of the present invention
- Figure 3 shows a comparison of the block error rate performance of the cooperative access scheme and the direct access scheme in the process of consistent change of the average signal-to-noise ratio between the two source nodes and the target node.
- Figure 4 shows a comparison of the throughput performance of the cooperative access scheme and the direct access scheme in the process of consistent change of the average signal-to-noise ratio between the two source nodes and the target node.
- Figure 5 shows a comparison of the capacity performance of the cooperative access scheme and the direct access scheme in the process of consistent change of the average signal-to-noise ratio between the two source nodes and the target node.
- Figure 6 shows the average signal-to-noise ratio (SNR) of the fixed source node to the target node is 5dB, and the channel-to-average signal-to-noise ratio of the second source node to the target node is gradually increased.
- SNR signal-to-noise ratio
- Figure 7 shows the average signal-to-noise ratio (SNR) of the fixed source node to the target node is 5dB, and the channel-to-average signal-to-noise ratio of the second source node to the target node is gradually increased.
- SNR signal-to-noise ratio
- the core idea of the present invention is: when the first source node sends a signal to the target node, the second source node is converted to the relay node of the first source node, and the signal is forwarded to the target. a node; the target node obtains a received signal to noise ratio of the target node according to the signal directly sent by the first source node and the signal forwarded by the second source node, according to the received signal to noise ratio setting according to the received signal to noise ratio
- the precoding strategy combines the real-time channel conditions to select the optimal precoding as the precoding vector used by the first source node to transmit signals to the target node.
- the first source node and the second source node each have a direct transmission link to the target node.
- the method of the invention should For a system including at least a first source node S, a second source node, and a target node, there is a direct transmission link H, H 2 between the target node /), a channel marking the source node S to the source node
- the transfer matrix is ⁇ .
- the channel transfer matrix from the source node to the source node S is .
- the number of nodes of the source node and the destination node are 2 and 1, respectively.
- Step 10 The first source node sends a symbol to the target node in a closed loop manner, and the target node receives the received signal in a matched filtering manner.
- the first source node performs precoding processing on the signal by using the initially set first precoding vector, where the first precoding vector uses the first right singularity of the channel transfer matrix of the direct transmission link between the first source node and the target node Vector; obtaining a first right singular vector of the channel transfer matrix by performing decomposition singular value decomposition on the channel transfer matrix;
- Step 20 The broadcast characteristic of the wireless propagation environment, when the transmission symbol of the first source node is sent to the target node, is also received by the second source node, and the second source node is also received by the matched filtering manner.
- Step 30 The second source node performs power normalization on the received transmit signal, and then forwards the signal to the target node.
- the forwarding process of the second source node is performed in a closed loop transmission manner, and is pre-coded by the initially set second precoding vector, and then forwarded to the target node, and the second precoding vector is directly used between the second source node and the target node.
- the channel matrix is decomposed by SVD (singular value) to obtain a U matrix, and the target node uses the conjugate transposition vector of the first column of the U array to receive the signal forwarded by the second source node;
- Step 40 The target node now has two transmit symbols of the first source node, one of which is transmitted by the first source node directly to the target node in step 10, and the other is forwarded by the second source node to the target node in step 30.
- the distributed precoding design strategy at the first source node is designed according to the received signal to noise ratio of the signal, according to the strategy.
- the optimal precoding is set as the first precoding vector used when the first source node sends a signal to the target node to improve system capacity, throughput, and reduce the block error rate.
- the method may further include: acquiring, according to the optimal precoding, an accurate received signal to noise ratio of the target node under current channel conditions.
- each network node is equipped with two antennas.
- the protocol of the source node mutual cooperation scheme designed by the invention is divided into four transmission phases:
- Transmission phase I S ⁇ send symbols to and /) in closed loop mode, ;
- Transmission Phase II ⁇ Send symbol x 2 to S and /) in closed loop mode
- Transmission phase III closed loop to /) forward S transmission symbol
- Transmission phase IV S, closed-loop to /) forwarded transmit symbol.
- the source node S sends a symbol to the target node in a closed loop manner, and transmits a pre-coded first right singular vector corresponding to the channel transfer matrix, and the target node receives the received signal in a matched filtering manner.
- the transmission symbol of the source node S is pre-coded and sent to the target node, it is also received by the source node, and the source node also uses the matching filtering method. Receive.
- the source node sends a symbol to the target node closed loop, and its precoding matrix uses the first right singular vector of the corresponding channel transfer matrix.
- the target node uses matched receive filtering for the received signal.
- the transmission symbol ⁇ 2 of the source node is pre-coded and transmitted to the target node, it is also received by the source node S.
- the source node S is also received by the matched filtering method.
- the source node forwards the power normalized pair to the target node.
- the forwarding process uses a closed-loop transmission method to use the first right singular vector of the channel transition matrix of the target node as the precoding vector used for transmitting the transmitted signal of S.
- the target node receives the conjugate transpose vector of the first column of the U array after the corresponding channel matrix SVD decomposition.
- the target node now has two estimates of the transmitted symbols of the source node S, one in the transmission phase I, the source node s is transmitted directly to the target node; the other is in the transmission phase III, from the source node to the target Node forwarded.
- the target node estimates the two transmitted symbols using the maximum ratio combining mode
- the distributed precoding design strategy in the transmission phase I at the source node s is designed according to the received signal to noise ratio of the signal.
- the source node S forwards the estimated value of the transmitted signal ⁇ received in the second phase to the target node.
- the forwarding process of S uses a closed-loop transmission mode, and the first right singular vector of the channel transfer matrix from S to the target node is used as the precoding matrix used for the S-transmitted transmission signal, and the target node uses the corresponding channel matrix SVD to decompose the U.
- the conjugate transpose of the first column of the array is received.
- the target node now has two estimates of the source node's transmitted symbol ⁇ 2 , one in the transport phase II, the source node is transmitted directly to the target node; the other is in the transport phase IV, from the source node S Forwarded by the target node.
- the target node estimates the two transmitted symbols, the maximum ratio combining mode is adopted, and the signal is received according to the signal. Ratio, design the distributed precoding design strategy in transport phase II at the source node.
- the method of the present invention is applied to a system including at least a first source node, a second source node, and a target node/), and the number of nodes of the source node and the target node are 2 and 1, respectively.
- the corresponding number of antennas for each node is N S , N D .
- the source node's transmit signal is assumed to be 1 ⁇ 2
- the channel transfer matrix from the source node S to the source node is H.
- the channel transfer matrix from the source node S to the source node is H.
- the channel transfer matrix from the source node to the source node S is.
- a scheme in which two source nodes respectively perform closed-loop access using a direct transmission link to a target node is referred to as a direct access scheme
- the cooperative communication method of the present invention is referred to as a coordinated access scheme.
- the following describes the direct access scheme and the coordinated access scheme separately, and compares the technical advantages of the cooperative communication method of the present invention with FIG. 3-7:
- the two source nodes independently transmit their respective transmission symbols without information interworking and cooperative transmission.
- the source node S and the respectively transmitted symbols and ⁇ , ⁇ use closed-loop transmission mode, use the first right singular vector of the channel matrix to transmit energy, and send a single data stream to the target node.
- the spatial channel transfer matrix of the node performs SVD decomposition:
- the target node uses zero-forcing (ZF) equalization.
- ZF zero-forcing
- G D represents the equalization matrix of the destination node
- H eg represents the equivalent channel experienced by the equivalent transmitted symbol of the source node
- n D represents the received noise of the destination node
- the post-processing signal-to-noise ratio of the data stream transmitted by the two source nodes can be derived from the above formula:
- the H f table shows the number, indicating the noise power.
- the source node mutual cooperation scheme distinguishes, and the scheme in which the two source nodes respectively utilize the direct transmission link of the target node for closed-loop access is called a direct access scheme.
- a direct access scheme the scheme in which the two source nodes respectively utilize the direct transmission link of the target node for closed-loop access.
- the source node S sends a symbol ⁇ to the target node in a closed loop manner. Transmit precoding into the first right singular vector of the corresponding channel transfer matrix:
- the target node's received signal for the transmitted symbol is:
- A H 1 p 1 x 1 + n A (7) where represents the reception noise of the destination node for the symbol ⁇ directly sent.
- the receiving signal is received by matched filtering:
- the received signal to noise ratio of the transmitted symbol is:
- the H f table shows the number, indicating the noise power.
- n is the reception noise of the symbol X sent by the source node to S.
- the source node is also received using matched filtering:
- the source node's received signal-to-noise ratio for the S transmitted signal is:
- the source node sends a symbol ⁇ 2 to the target node closed loop, and its precoding matrix uses the first right singular vector of the corresponding channel transfer matrix H 2 .
- P 2 V 2 (:,1),
- the receiving signal of the target node to the transmitted signal is:
- 11 represents the reception noise of the destination node for the directly transmitted symbol ⁇ 2 .
- Filtering The received signal to noise ratio of the number x 2 is:
- the H f table shows the number, indicating the noise power.
- the source is:
- the H f table shows the number, indicating the noise power.
- the transmitted signal estimate from s received in the first phase will be forwarded to the target node.
- the amplification and forwarding coefficient A so that the power of the conversion signal satisfies the normalization condition
- ⁇ .
- the signal-to-noise ratio is in the forwarded signal, and the power of the signal portion is the power of the noise portion is _ ⁇ .
- the source node forwards the power-normalized transmit signal estimate for S to the target node.
- the forwarding process uses a closed-loop transmission method, and the first right singular vector of the channel transfer matrix of the target node is used as a precoding vector used for transmitting the transmitted signal of s, and the target node uses the u-array decomposed by the corresponding channel matrix SVD.
- the conjugate transpose vector of the first column is received. That is, the received signal of the target node is:
- the received signal-to-noise ratio of the transmitted S-transmitted symbols of the target node during the third-stage transmission is:
- the target node now has two estimates of the transmitted symbols of the source node S, one in the transmission phase I, the source node s is transmitted directly to the target node; the other is in the transmission phase III, from the source node Forwarded by the target node.
- the target node estimates the maximum ratio of the two transmitted symbols X,
- the H f table shows the number, indicating the noise power.
- X is satisfied.
- the dish and ⁇ respectively channel transfer matrix H.
- the design method that can be inferred from the above judgment branch.
- the design principle of Pl should be such that the source node S's transmitted symbol X has the largest signal-to-noise ratio at the target node. So combine the above pairs.
- the simplification analysis, Pl 's design principles can be further simplified to:
- the precoding at the source node s can be further designed as:
- the precoding at the source node S can be further designed as: make
- the received signal-to-noise ratio of the target node to the source node S transmitted signal can be accurately calculated.
- the distributed precoding design strategy in the transport phase I at the source node S is given above.
- the source node S forwards the estimated value of the transmitted signal ⁇ received in the second phase to the target node.
- the amplifying and forwarding coefficient ⁇ ⁇ set at the time of transmission should make the power of the forwarded signal satisfy the power normalization condition ⁇ 3 ⁇ 4
- ⁇ ⁇
- the signal-to-noise ratio is .
- the power of the signal portion is ", and the power of the noise portion is ⁇ .
- the source node s forwards the estimated value of the transmitted signal of the power normalized pair to the target node.
- the forwarding process of S uses a closed-loop transmission mode, and the first right singular vector of the channel transfer matrix from S to the target node is used as the precoding matrix used by the S-transmitted transmission signal, and the target node uses the corresponding channel matrix SVD to decompose the U.
- the conjugate transpose of the first column of the array is received. That is, the received signal of the target node is:
- n D the reception noise of the destination node.
- the target node's received signal-to-noise ratio is ⁇
- the received signal to noise ratio of the transmitted symbols forwarded by the target node during the fourth phase transmission is:
- the mini ( ⁇ , (35) target node now has two estimates of the source node's transmitted symbol ⁇ , one in the transport phase II, the source node is transmitted directly to the target node; the other is in the transport phase IV
- the target node forwards to the target node by the source node S.
- the target node estimates the two transmitted symbols, and the received signal to noise ratio of the signal after the maximum ratio combining mode is:
- the H f table shows the number, indicating the noise power.
- ⁇ ⁇ 2 £ ⁇ is satisfied.
- the dish and the channel transfer matrix are respectively.
- the design principle of p 2 should be such that the source node's transmitted symbol x 2 receives the maximum signal-to-noise ratio at the target node. Therefore, the above pair is combined.
- the rationalization of p 2 can be further simplified to:
- the precoding vector of the source node S 2 can be further designed as:
- the precoding at the source node s 2 can be further designed as:
- the selected optimal precoding p 2 is brought back
- the received signal-to-noise ratio of the target node to the source node transmit signal ⁇ can be accurately calculated.
- the distributed precoding design strategy in the transport phase II at the source node is given above.
- FIG 3 shows the block error rate performance (BLER) of the cooperative access scheme and the direct access scheme in the process of consistently changing the average signal-to-noise ratio (SNR) of the two source nodes to the target node.
- BLER block error rate performance
- Figure 4 shows the throughput performance of the cooperative access scheme and the direct access scheme in the process of consistently changing the average signal-to-noise ratio (SNR) of the two source nodes to the target node.
- SNR signal-to-noise ratio
- Figure 5 shows the capacity performance (Capacity) comparison between the coordinated access scheme and the direct access scheme in the process of consistently changing the average signal-to-noise ratio (SNR) of the two source nodes to the target node.
- Capacity capacity performance comparison between the coordinated access scheme and the direct access scheme in the process of consistently changing the average signal-to-noise ratio (SNR) of the two source nodes to the target node.
- SNR signal-to-noise ratio
- Figure 6 shows that when the average signal-to-noise ratio (SNR) of the channel from the first source node to the target node is fixed to 5 dB, and the channel-to-signal-to-noise ratio (S 2 -D link SNR ) of the second source node to the target node is gradually increased,
- SNR signal-to-noise ratio
- S 2 -D link SNR channel-to-signal-to-noise ratio
- Figure 7 shows that when the channel-to-signal-to-noise ratio (S 2 -D link SNR ) of the second source node to the target node is gradually increased, the channel-to-signal-to-noise ratio (S 2 -D link SNR ) of the second source node to the target node is fixed.
- the cooperative access scheme is compared with the capacity performance (Capacity) of the direct access scheme.
- the performance of the cooperative access scheme of the present invention is far superior to the existing direct access scheme in terms of capacity performance, throughput performance, or block error rate performance, and the cooperative access scheme of the present invention can effectively improve The system's capacity, throughput, and can effectively reduce the block error rate.
- a fixed relay node Before the transmission process, a fixed relay node is not set in the network, and the relationship between the two source nodes is equivalent, and each information needs to be transmitted to the target node.
- the source nodes can form a cooperative relationship and bear each other.
- the relay node of the source node signal can exchange information between the source nodes; because the source node has a cooperative relationship, the transmission role of the source node of the present invention is not fixed, and the source node can serve as a temporary in some specific transmission stages.
- Relay node in this way, system capacity, throughput, and bit error rate can be effectively improved.
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Abstract
本发明公开了一种上行多用户协同通信的方法,应用于至少包括第一源节点、第二源节点和目标节点的系统,第一源节点、第二源节点均存在到目标节点之间的直接传输链路;所述方法,包括如下步骤:第一源节点向目标节点发送信号时一并发送给第二源节点,第二源节点转换为第一源节点的中继节点,将所述信号转发至所述目标节点;所述目标节点根据第一源节点直接发来的信号和由第二源节点转发来的信号以采用最大比合并方式得到目标节点的接收信噪比,根据所述接收信噪比设置分布式预编码策略,并结合实时的信道条件选择最优的预编码作为第一源节点向目标节点发送信号时使用的预编码矢量。本发明可以有效提高系统容量、吞吐量,降低误块率。
Description
一种上行多用户协同通信的方法
技术领域
本发明涉及无线通信技术领域, 具体涉及一种上行多用户协同通信的方 法。
背景技术
上行多用户协同通信提供了一种利用空间资源的手段, 多个参与通信的 实体之间通过协作方式共享有限资源以提高无线资源的利用率。 上行多用户 协同通信多见于传统移动通信蜂窝网络中。 在单中继节点和多中继节点的上 行多用户协同通信中, 每个节点在整个信号传输过程中所承担的角色是固定 且单一的, 各类节点间进行传输和信号处理的分工明确, 在实际系统中, 这 种明确的分工与各个节点的地理位置和节点配置等系统需求是紧密相联系 的:
源节点, 一般对应上行链路中的移动台 ( Mobile Station, MS ) , 分布在 小区中各个位置, 还带有一定的移动性特征。 移动台由于用户便携性和设备 尺寸的限制, 配置高阶天线具有一定的困难, 因此天线单元数目较少, 发射 功率相对较小, 源节点侧的信号处理复杂度也不能过高。 由于移动台用户通 信的信息保密性限制, 多个源节点之间不能相互发射信号。
中继节点,对应于架设于传统移动通信蜂窝小区中的中继站( Relay Node,
RN )。 中继站点的位置相对固定, 尤其需要架设在某些需要特定区域或者在 用户密度较大发生接入拥塞问题时使用。 中继节点需要具备一定的信号处理 能力, 其信号处理复杂度介于源节点和目标节点之间, 由于中继节点多是进 行信号处理操作, 所以对于中继站点而言, 高层协议的实现不如移动台和基 站那样重要。
目标节点, 对应于传统移动通信蜂窝网络中的基站( Base Station, BS ) , 一般架设于小区中某一固定位置, 受尺寸和发射功率的限制较小, 可以装配 高阶天线, 并具有较高的信号处理复杂度。 对于上行多用户协同系统而言,
基站应具备较强的多流检测处理能力, 以区分上行接入的多个移动台用户的 多个数据流。
但是, 目前协同通信蕴含的容量潜力迄今为止还没有被充分地开发使用, 中继节点的相对固定占用了系统通信的有限的资源, 如何解放中继节点成为 了亟待解决的问题。 而且, 预编码技术通过利用信道状态信息也可以有效地 提高系统的频谱效率, 因此, 如何通过设计合适的预编码来提高系统容量、 吞吐量并降低误码率成为了又一亟待解决的问题。
发明内容
有鉴于此, 本发明所要解决的技术问题是提供了一种上行多用户协同通 信的方法, 有效提高系统容量、 吞吐量, 降低误块率。
为达上述的目的, 本发明的一种上行多用户协同通信的方法, 应用于至 少包括第一源节点、 第二源节点和目标节点的系统, 第一源节点、 第二源节 点均存在到目标节点之间的直接传输链路; 所述方法, 包括如下步骤: 第一 源节点向目标节点发送信号时一并发送给第二源节点, 第二源节点转换为第 一源节点的中继节点, 将所述信号转发至所述目标节点; 所述目标节点根据 第一源节点直接发来的信号和由第二源节点转发来的信号以釆用最大比合并 方式得到目标节点的接收信噪比, 根据所述接收信噪比设置分布式预编码策 略, 并结合实时的信道条件选择最优的预编码作为第一源节点向目标节点发 送信号时使用的预编码矢量。
进一步地, 第一源节点向目标节点发送信号时, 也一并发送给第二源 节点的步骤, 包括: 第一源节点以初始设定的第一预编码矢量对信号进行 预编码处理后向目标节点及第二源节点发送,第一预编码矢量釆用第一源 节点与目标节点间的直接传输链路的信道转移矩阵的第一右奇异矢量。
进一步地, 通过对第一源节点与目标节点间的直接传输链路的信道转 移矩阵进行分解奇异值分解得到所述信道转移矩阵的第一右奇异矢量。
进一步地, 目标节点及第二源节点均釆用匹配滤波方式对第一源节点发 来的信号进行接收。
进一步地,第一源节点和第二源节点均釆用闭环发送方式进行信号发送。 进一步地, 第二源节点转换为第一源节点的中继节点, 将所述信号转发 至所述目标节点的步骤, 包括: 第二源节点对所接收的信号进行归一化, 并 以初始设定的第二预编码矢量进行预编码处理后向目标节点转发, 第二预编 码矢量釆用第二源节点与目标节点间的直接传输链路的信道转移矩阵的第一 右奇异矢量。
进一步地, 通过对第二源节点与目标节点间的直接传输链路的信道转 移矩阵进行分解奇异值分解得到所述信道转移矩阵的第一右奇异矢量。
进一步地, 第二源节点对所接收的信号进行归一化的操作, 包括: 设置 放大转发系数, 使得由第二源节点转发的信号满足归一化条件。
进一步地, 第二源节点转换为第一源节点的中继节点, 将所述信号转发 至所述目标节点的步骤, 还包括: 第二源节点与目标节点间的直接传输链 路的信道转移矩阵经奇异值分解后得到 U阵, 目标节点釆用所述 U阵的第 一列的共轭转置矢量接收由第二源节点转发来的信号。
进一步地, 选择最优的预编码作为第一源节点发送信号时使用的预编码 矢量的步骤, 包括: 选择最优的预编码作为第一预编码矢量; 选择最优的预 编码作为第一源节点发送信号时使用的预编码矢量的步骤之后, 还包括: 根 据所述最优的预编码获取当前信道条件下所述目标节点的接收信噪比。
与现有的方案相比, 本发明所获得的技术效果:
在传输过程之前, 网络中不需要设置固定的中继节点, 两个源节点之间 关系等同, 均需要传送各自信息给目标节点; 在传输过程中, 源节点之间可 以形成协作关系, 互相承担对方源节点信号的中继传输任务, 源节点之间可 以互通信息; 由于源节点存在协作关系, 本发明的源节点的传输角色不固定, 在某些特定传输阶段, 源节点可以充当临时的中继节点, 通过这种方式可以 有效地提高系统容量、 吞吐量并降低误码率。
附图概述
图 1是本发明适用的无线通信系统示意图。
图 2为本发明实施例的整体方案的方法流程图;
图 3给出了在两个源节点到目标节点的平均信噪比进行一致性变化 的过程中, 协同接入方案与直接接入方案的误块率性能对比示意图。
图 4给出了在两个源节点到目标节点的平均信噪比进行一致性变化 的过程中, 协同接入方案与直接接入方案的吞吐量性能对比示意图。
图 5给出了在两个源节点到目标节点的平均信噪比进行一致性变化 的过程中, 协同接入方案与直接接入方案的容量性能对比示意图。
图 6给出了固定第一个源节点到目标节点的信道平均信噪比为 5dB , 逐渐增大第二个源节点到目标节点的信道平均信噪比时, 协同接入方案 与直接接入方案的吞吐量性能对比示意图。
图 7给出了固定第一个源节点到目标节点的信道平均信噪比为 5dB , 逐渐增大第二个源节点到目标节点的信道平均信噪比时, 协同接入方案 与直接接入方案的容量性能对比示意图。 本发明的较佳实施方式
下面结合附图和具体实施方式对本发明作进一步说明。
以下将配合图式及实施例来详细说明本发明的实施方式, 藉此对本发明 如何应用技术手段来解决技术问题并达成技术功效的实现过程能充分理解并 据以实施。
本发明的核心构思在于: 第一源节点向目标节点发送信号时一并发送给 第二源节点, 第二源节点转换为第一源节点的中继节点, 将所述信号转发至 所述目标节点; 所述目标节点根据第一源节点直接发来的信号和由第二源节 点转发来的信号以釆用最大比合并方式得到目标节点的接收信噪比, 根据所 述接收信噪比设置预编码策略, 并结合实时的信道条件选择最优的预编码作 为第一源节点向目标节点发送信号时使用的预编码矢量。
第一源节点、 第二源节点均存在到目标节点之间的直接传输链路。
首先, 参照图 1 , 对本发明的发明场景进行说明。 本发明的方法应
用于至少包括第一源节点 S、 第二源节点 和目标节点 的系统, 、 均存在到目标节点 /)之间的直接传输链路 H,、 H2 , 标记源节点 S到源节 点 的信道转移矩阵为 Η。, 源节点 到源节点 S的信道转移矩阵为 。 源节点和目标节点的节点数量分别为 2和 1。 每个节点相应的天线数分 为 NS , ND 。 如果假设源节点的发射信号为 χ , 源节点的发射信号功率 满足 £( ·½) = Λ^。
如图 2所示, 为本发明整体方案的方法流程图, 执行如下操作: 步骤 10 , 第一源节点釆用闭环方式向目标节点发送符号, 目标节点对接 收信号釆用匹配滤波方式接收;
第一源节点以初始设定的第一预编码矢量对信号进行预编码处理, 第一预编码矢量釆用第一源节点与目标节点间的直接传输链路的信道转 移矩阵的第一右奇异矢量; 可以通过对所述信道转移矩阵进行分解奇异值 分解得到所述信道转移矩阵的第一右奇异矢量;
步骤 20 , 由无线传播环境的广播特性, 第一源节点的发射符号发送至目 标节点时, 也同样可以被第二源节点接收到, 第二源节点同样釆用匹配滤波 方式接收;
步骤 30 , 第二源节点对所接收的发射信号进行功率归一化后, 向目标节 点转发;
第二源节点的转发过程釆用闭环发送方式, 以初始设定的第二预编码矢 量进行预编码处理后向目标节点转发, 第二预编码矢量釆用第二源节点与目 标节点间的直接传输链路的信道转移矩阵的第一右奇异矢量;
所述信道矩阵经过 SVD (奇异值)分解后得到 U阵, 目标节点釆用此 U 阵的第一列的共轭转置矢量来接收由第二源节点转发来的信号;
步骤 40 , 目标节点现在拥有两份第一源节点的发射符号, 一份是步骤 10 中第一源节点直接向目标节点传输的,另一份是步骤 30中由第二源节点向目 标节点转发的; 目标节点对这两份发射符号釆用最大比合并方式后, 根据信 号的接收信噪比, 设计第一源节点处的分布式预编码设计策略, 依据该策略
并结合实时的信道条件, 设置最优的预编码作为第一源节点向目标节点发送 信号时使用的第一预编码矢量以提高系统容量、 吞吐量, 并降低误块率。
步骤 40之后, 还可以包括: 根据所述最优的预编码获取当前信道条件 下所述目标节点的精确的接收信噪比。
在上述流程中, 如对照图 1 的应用场景, 当 S作为上述流程中的第一源 节点时, 则 作为上述流程中的第二源节点, 转换为中继节点; 当 作为上 述流程中的第一源节点时, 则 S作为上述流程中的第二源节点, 转换为中继 节点。
以下以一实施例对本发明的整体方案进行说明。
考虑一个最简单的多用户互协同上行多用户协同系统, 含有三个节点, 其中两个源节点需要发送各自数据至目标节点。 两个源节点之间在必要时可 以进行信息互通, 并可以在必要时从源节点转换为对方源节点的中继节点, 中继转发另一源节点的发送信号至目标节点。 两个源节点均存在到目标节点 之间的直接传输链路。 为了便于应用多天线技术, 每个网络节点均装配 2根 天线。
本发明所设计的源节点互协同方案的协议分为四个传输阶段:
传输阶段 I: S釆用闭环方式向 和 /)发送符号 χ, ;
传输阶段 II: 釆用闭环方式向 S和/)发送符号 x2 ;
传输阶段 III: 闭环向/)转发 S的发射符号;
传输阶段 IV: S,闭环向 /)转发 的发射符号。
传输阶段 I
在第一个传输阶段中, 源节点 S釆用闭环方式向目标节点发送符号, 发 送预编码为对应信道转移矩阵的第一右奇异矢量, 目标节点对接收信号釆用 匹配滤波方式接收。
由无线传播环境的广播特性, 源节点 S的发射符号经过预编码处理后发 送至目标节点时, 同样被源节点 接收到, 源节点 同样釆用匹配滤波方式
接收。
传输阶段 π
在第二个传输阶段中, 源节点 向目标节点闭环发送符号, 其预编码矩 阵釆用相应信道转移矩阵的第一右奇异矢量。 目标节点对接收信号釆用匹配 接收滤波。
由无线传播环境的广播特性, 源节点 的发射符号 χ2经过预编码处理后 发送至目标节点时, 同样被源节点 S接收到。 源节点 S同样釆用匹配滤波方 式接收。
传输阶段 III
在第三阶段传输过程中, 源节点 向目标节点转发经过功率归一化的对
S的发射信号估计值。 的转发过程釆用闭环发送方式, 以 到目标节点的 信道转移矩阵的第一右奇异矢量作为 转发 S的发射信号所使用的预编码矢 量。目标节点釆用对应信道矩阵 SVD分解后的 U阵的第一列的共轭转置矢量 进行接收。
目标节点处现在拥有两份对源节点 S发射符号的估计, 一份是在传输阶 段 I中, 源节点 s直接向目标节点传输的; 另一份是在传输阶段 III中, 由源 节点 向目标节点转发的。 目标节点对所述两份发射符号的估计釆用最大比 合并方式后, 根据信号的接收信噪比, 设计源节点 s处的传输阶段 I 中的分 布式预编码设计策略。
传输阶段 IV
与第三个传输阶段类似, 第四阶段的传输过程中, 源节点 S转发在第二 阶段所接收到的来自 的发射信号 ^的估计值至目标节点。 S的转发过程釆 用闭环发送方式, 以 S到目标节点的信道转移矩阵的第一右奇异矢量作为 S 转发 的发射信号所使用的预编码矩阵, 目标节点釆用对应信道矩阵 SVD分 解后的 U阵的第一列的共轭转置进行接收。 目标节点处现在拥有两份对源节 点 发射符号 χ2的估计 , 一份是在传输阶段 II中, 源节点 直接向目标节点 传输的; 另一份是在传输阶段 IV中, 由源节点 S向目标节点转发的。 目标节 点对所述两份发射符号的估计釆用最大比合并方式后, 根据信号的接收信噪
比, 设计源节点 处的传输阶段 II中的分布式预编码设计策略。
以下以一应用实例对本发明进行说明。
如上述系统场景, 如图 1所示, 本发明的方法应用于至少包括第一源 节点 、 第二源节点 和目标节点 /)的系统, 源节点和目标节点的节点数 量分别为 2和 1。 每个节点相应的天线数分别为 NS , ND。 如果假设源节点的 发射信号为 ½ , 源节点的发射信号功率满足 « ·½) = Λ^。 假设两个源节 点到目标节点之间均存在直接传输链路( link ) , 第 i G {1, 2})个源节点到目标 节点的直接传输链路的信道转移矩阵称为 H,.。 为了区别, 标记源节点 S到源 节点 的信道转移矩阵为 H。, 才艮据信道对偶性, 源节点 到源节点 S的信道 转移矩阵为 。
两个源节点各自利用到目标节点的直接传输链路进行闭环接入的方案称 为直接接入方案, 本发明的协同通信方法称为协同接入方案。 为了对比显示 本发明的协同接入方案的技术优势, 以下分别对直接接入方案和协同接入方 案进行说明, 并结合图 3-7来比较本发明协同通信方法的技术优势:
1 )直接接入方案
作为对比方案, 两个源节点独立发送各自的发送符号, 不进行信息互通 和协同传输。 源节点 S和 分别发送符号 和^ , 釆用闭环发送方式, 利用 信道矩阵的第一右奇异矢量集中发射能量, 发送单个数据流给目标节点。
则 S和 的发射预编码矩阵 Pl、 p2分别为相应的信道转移矩阵的第一右 奇异矢量:
,
P2 = V2 (:, 1),
其中, GD表示目的节点的均衡矩阵, Heg表征源节点的等效发射符号所经历 的等效信道, nD表示目的节点的接收噪声。
其中, Hf表示范数, 表示噪声功率。
2 )协同接入方案
下面讨论的, 源节点互协同方案进行区分, 两个源节点各自利用到目标 节点的直接传输链路进行闭环接入的方案称为直接接入方案。 下面在各个传 输阶段信号处理的探讨过程中, 逐步分析源节点 S和 的分布式预编码方案 设计策略。
传输阶段 I
在第一个传输阶段中 , 源节点 S釆用闭环方式向目标节点发送符号 χι。 发送预编码为对应信道转移矩阵 的第一右奇异矢量:
P^ Y C, 1),
目标节点对 发射符号的接收信号为:
其中, Hf表示范数, 表示噪声功率。 由无线传播环境的广播特性, 源节点 S的发射符号 X,经过预编码处理发 送至目标节点时, 也同样可以被源节点 接收到。 对 s发射符号的接收信 号为:
其中, n 表示源节点 对于 S发来的符号 X,的接收噪声。 源节点 同样釆用匹配滤波方式接收:
s2 =(H0P,†yS2
(11)
其中, Hf表示范数, 表示噪声功率。 传输阶段 II
在第二个传输阶段中, 源节点 向目标节点闭环发送符号 χ2 , 其预编码 矩阵釆用相应信道转移矩阵 H2的第一右奇异矢量。 P2=V2(:,1),
其中, Hf表示范数, 表示噪声功率。 传输阶段 m
在第三个传输阶段中 , 将向目标节点转发第一阶段所接收到的来自 s 的发射信号估计值 。 为了满足发射节点的发射功率限制, 需要设置放大转 发系数 A, ,使得转 ^信号的功率满足归一化条件 |Α, Λ¾ | = Ι。 由于之前分析 所得, 在源节点 的接收信号 中, 信号噪声比为 则在转发信号中, 信号部分的功率为^ 噪声部分的功率为 _^。 在第三阶段传输过程中, 源节点 向目标节点转发经过功率归一化的对 S的发射信号估计值 。 的转发过程釆用闭环发送方式, 以 到目标节点 的信道转移矩阵的第一右奇异矢量作为 转发 s的发射信号所使用的预编码 矢量,目标节点釆用对应信道矩阵 SVD分解后的 u阵的第一列的共轭转置矢 量进行接收。 也即, 目标节点的接收信号为:
= S2(HA +U (:,l)nD (20)
其中 U2、 S2、 ¼由112进行 SVD分解得到, 也即满足 (13); 此82的第一个对 角线元素, 即为 H2最大的奇异值为^ nD表示目的节点的接收噪声。 则目标 节点的接收信号如上式所示。 若 ^中不含噪声部分,则目标节点的接收信噪比为 ^=^^,其中,
' 1 σ
表示噪声功率。 由此可以推导出目标节点在第三阶段传输过程中对于 转发 的 S发射符号的接收信噪比为:
而
Ϊ2ΪΙ 目标节点处现在拥有两份对源节点 S发射符号 的估计, 一份是在传输 阶段 I中, 源节点 s直接向目标节点传输的; 另一份是在传输阶段 III中, 由 源节点 向目标节点转发的。 目标节点对两份发射符号 X,的估计釆用最大比 合并
其中, Hf表示范数, 表示噪声功率。 一般而言,满足 ≤||HPl|X。其中 皿和^分别信道转移矩阵 H。的 最小和最大的奇异值。 基于此, 可以对 (23)进一步化简:
若^ ~ <^, 则 (23)式可简化为 :
σ σ σ 若 Λ2 (23)式可筒化为
σ一> 则 -E σ^L+,; 若 ~^<y2< Λ0 , 则应根据实时信道情况对 (23)式进行化简。
' σ σ
由上述判断分支,可以推知 的设计方法。 Pl的设计原则应是使源节点 S 的发射符号 X,在目标节点处接收信噪比最大。 因此结合上述对 ?。的化简分 析, Pl的设计原则可以进一步简化为:
在此情形下, 源节点 s处的预编码可以进一步设计为:
令
W = H 1 +H H (25)
并对其进行 SVD分解:
uwswy = W (26)
由于 W是共轭对称阵, 也即\^=\¥, 因此 (26)中, UW = VW
此时, 为了最大化^^+ 。!^, 可令:
=Uw(:,l) (27)
则在此情形下, 源节点 S,处的预编码可以进一步设计为:
令
W = Η¾ (30)
并对其进行 SVD分解:
υ» = W" (31)
由于 W' '同样为共轭对称矩阵, 因此为了最大化 iHji , 可令:
Pl = U'w(:,l) (32) 若 ^〈^〈^ ^ , 则应根据实时的信道条件, 由 (23)判断 的设计策 σ σ
略应遵从 (24)还是应遵从 (28), 由此可相应得到 的设计方案 (应选取的最 优的预编码)应为 (27)还是 (32)。
在得到具体信道条件下 的设计策略后, 选取的最优的预编码 Pl带回到
(23), 便可以精确计算目标节点对源节点 S发射信号 的接收信噪比。 以上给 出了源节点 S处的传输阶段 I中的分布式预编码设计策略。
传输阶段 IV
与第三个传输阶段类似, 第四阶段的传输过程中, 源节点 S转发在第二 阶段所接收到的来自 的发射信号 ^的估计值 至目标节点。同样,发射 时所设置的放大转发系数 βΐΑ应使转发信号的功率满足功率归一化条件 ·¾| = ΐ ο 在源节点 S的接收信号 中, 信号噪声比为 。 则在转发信 号中, 信号部分的功率为」 , 噪声部分的功率为^ ~。 在第四阶段传输过程中, 源节点 s向目标节点转发经过功率归一化的对 的发射信号估计值 , 。 S的转发过程釆用闭环发送方式, 以 S到目标节点 的信道转移矩阵的第一右奇异矢量作为 S转发 的发射信号所使用的预编码 矩阵,目标节点釆用对应信道矩阵 SVD分解后的 U阵的第一列的共轭转置进 行接收。 也即, 目标节点的接收信号为:
= S1 (l,l)^1¾ +U1 ff (:,l)nD (33)
= ΑΛ ^2Λ + u,ff (:,1) 其中 U,、 S,、 γ由!!,进行 SVD分解得到, 也即满足 (6)。 此 ^的第一个
对角线元素, 也即 最大的奇异值为 , nD表示目的节点的接收噪声。 则目 标节点的接收信号如上式所示。
^,其中, σ 若 中不含噪声部分,则目标节点的接收信噪比为 Ά
σ
表示噪声功率。 由此可以推导出目标节点在第四阶段传输过程中对于 S转发 的 发射符号的接收信噪比为:
而 mini (Ά, (35) 目标节点处现在拥有两份对源节点 发射符号 ^的估计, 一份是在传输 阶段 II中, 源节点 直接向目标节点传输的; 另一份是在传输阶段 IV中, 由 源节点 S向目标节点转发的。 目标节点对所述两份发射符号的估计釆用最大 比合并方式后信号的接收信噪比为:
Η0Ρ
|Η2Ρ σ
σ Ho
其中, Hf表示范数, 表示噪声功率。 一般而言,满足 ≤|Η ρ2£≤λΙ,。其中 皿和 分别信道转移矩阵 Η。的 最小和最大的奇异值。 由此可对 (36)进一步化简: 若^ , 则 (36)式可简化为 - - + Ρ
σ σ
Η2Ρ:
若 > , 则 (36)式可简化为 D 若 , 则应根据实时信道情况对 (36)式进行化简
若 ^ 则 2的设计原则为:
在此情形下, 源节点 S2的预编码矢量可进一步设计为: 令
W = HfH2+H H (38)
并对其进行 SVD分解:
UwSwV =W (39)
由于 W是共轭对称阵, 也即 Wff =W, 因此 (39)中, UW = VW
此时, 为了最大化 |H2P2 +|Hp2 ,可令:
P2=uw(- 1) (40)
然而由于在给定信道条件下, ^是定值, 因此 2的设计原则可以进一步 简化为: σ
则在此情形下, 源节点 s2处的预编码可以进一步设计为:
由于 W' '同样为共轭对称矩阵, 因此为了最大化 |H2p2 , 可令:
p2 = U'w(:,l) (45)
若 <^<^ , 则应根据实时的信道条件, 由 (36)判断 p2的设计策 略应遵从 (37)还是应遵从 (41), 进而得到 2的设计方案(应选取的最优的预编 码)应该遵从 (40)还是 (45)。
在得到具体信道条件下 2的设计策略后, 选取的最优的预编码 p2带回到
(36),便可以精确计算目标节点对源节点 发射信号 ^的接收信噪比。 以上给 出了源节点 处的传输阶段 II中的分布式预编码设计策略。
以下为上述直接接入方案和协同接入方案实现后得到的一系列仿真结 果:
图 3给出了在两个源节点到目标节点的平均信噪比 (SNR ) 进行一 致性变化的过程中,协同接入方案与直接接入方案的误块率性能( BLER ) 对比。
图 4给出了在两个源节点到目标节点的平均信噪比 (SNR ) 进行一 致性变化的过程中, 协同接入方案与直接接入方案的吞吐量性能 ( Throughput ) 对比。
图 5给出了在两个源节点到目标节点的平均信噪比 (SNR ) 进行一 致性变化的过程中,协同接入方案与直接接入方案的容量性能( Capacity ) 对比。
图 6给出了固定第一个源节点到目标节点的信道平均信噪比为 5dB , 逐渐增大第二个源节点到目标节点的信道平均信噪比 ( S2-D link SNR ) 时, 协同接入方案与直接接入方案的吞吐量性能 (Throughput ) 对比。
图 7给出了固定第一个源节点到目标节点的信道平均信噪比为 5dB , 逐渐增大第二个源节点到目标节点的信道平均信噪比 ( S2-D link SNR ) 时, 协同接入方案与直接接入方案的容量性能 (Capacity ) 对比。
可以看到, 无论是容量性能、 吞吐量性能还是误块率性能, 本发明 的协同接入方案的表现都远远优于现有的直接接入方案, 本发明的协同接 入方案可以有效提高系统的容量、 吞吐量, 并且能够有效降低误块率。
上述说明示出并描述了本发明的若干优选实施例, 但如前所述, 应当理 解本发明并非局限于本文所披露的形式, 不应看作是对其他实施例的排除, 而可用于各种其他组合、 修改和环境, 并能够在本文所述发明构想范围内, 通过上述教导或相关领域的技术或知识进行改动。 而本领域人员所进行的改 动和变化不脱离本发明的精神和范围, 则都应在本发明所附权利要求的保护 范围内。
工业实用性
在传输过程之前, 网络中不设置固定的中继节点, 两个源节点之间关系 等同, 均需要传送各自信息给目标节点; 在传输过程中, 源节点之间可以形 成协作关系, 互相承担对方源节点信号的中继传输任务, 源节点之间是可以 互通信息的; 由于源节点存在协作关系, 本发明的源节点的传输角色不固定, 在某些特定传输阶段, 源节点可以充当临时的中继节点; 通过这种方式可以 有效地提高系统容量、 吞吐量并降低误码率。
Claims
1、 一种上行多用户协同通信的方法, 其特征在于, 应用于至少包括第 一源节点、 第二源节点和目标节点的系统, 第一源节点、 第二源节点均存在 到目标节点之间的直接传输链路; 所述方法, 包括如下步骤:
第一源节点向目标节点发送信号时一并发送给第二源节点, 第二源节点 转换为第一源节点的中继节点, 将所述信号转发至所述目标节点;
所述目标节点根据第一源节点直接发来的信号和由第二源节点转发来的 信号以釆用最大比合并方式估算目标节点的接收信噪比, 根据所述估算的接 收信噪比设置分布式预编码策略, 并结合实时的信道条件选择最优的预编码 作为第一源节点发送信号时使用的预编码矢量。
2、 如权利要求 1所述的方法, 其特征在于, 第一源节点向目标节点 发送信号时, 也一并发送给第二源节点的步骤, 进一步包括:
第一源节点以初始设定的第一预编码矢量对信号进行预编码处理后 向目标节点及第二源节点发送,第一预编码矢量釆用第一源节点与目标节 点间的直接传输链路的信道转移矩阵的第一右奇异矢量。
3、 如权利要求 2所述的方法, 其特征在于,
通过对第一源节点与目标节点间的直接传输链路的信道转移矩阵进 行分解奇异值分解得到所述信道转移矩阵的第一右奇异矢量。
4、 如权利要求 1或 2所述的方法, 其特征在于,
目标节点及第二源节点均釆用匹配滤波方式对第一源节点发来的信号 进行接收。
5、 如权利要求 1所述的方法, 其特征在于,
第一源节点和第二源节点均釆用闭环发送方式进行信号发送。
6、 如权利要求 1 所述的方法, 其特征在于, 第二源节点转换为第一 源节点的中继节点, 将所述信号转发至所述目标节点的步骤, 进一步包括: 第二源节点对所接收的信号进行归一化, 并以初始设定的第二预编码矢 量进行预编码处理后向目标节点转发, 第二预编码矢量釆用第二源节点与目 标节点间的直接传输链路的信道转移矩阵的第一右奇异矢量。
7、 如权利要求 6所述的方法, 其特征在于,
通过对第二源节点与目标节点间的直接传输链路的信道转移矩阵进 行分解奇异值分解得到所述信道转移矩阵的第一右奇异矢量。
8、 如权利要求 6 所述的方法, 其特征在于, 第二源节点对所接收的 信号进行归一化的操作, 进一步包括:
设置放大转发系数, 使得由第二源节点转发的信号满足归一化条件。
9、 如权利要求 6 所述的方法, 其特征在于, 第二源节点转换为第一 源节点的中继节点, 将所述信号转发至所述目标节点的步骤, 还包括:
第二源节点与目标节点间的直接传输链路的信道转移矩阵经奇异值 分解后得到 U阵, 目标节点釆用所述 U阵的第一列的共轭转置矢量接收由第 二源节点转发来的信号。
10、 如权利要求 1所述的方法, 其特征在于,
选择最优的预编码作为第一源节点发送信号时使用的预编码矢量的步 骤, 包括: 选择最优的预编码作为第一预编码矢量;
选择最优的预编码作为第一源节点发送信号时使用的预编码矢量的步骤 之后, 还包括: 根据所述最优的预编码获取当前信道条件下所述目标节点的 接收信噪比。
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