提出了一种长期演进项目的后续演进(long term evolution-advanced,LTE-A)中的信漏噪比联合校准多用户多流波束赋形方案。基于信漏噪比准则进行波束赋形消除多用户间干扰,实现LTE-A下的多用户多流波束赋形传输;建立信道校准机制,补偿实...提出了一种长期演进项目的后续演进(long term evolution-advanced,LTE-A)中的信漏噪比联合校准多用户多流波束赋形方案。基于信漏噪比准则进行波束赋形消除多用户间干扰,实现LTE-A下的多用户多流波束赋形传输;建立信道校准机制,补偿实际通信系统中的射频增益影响,恢复信道互易性,提升实际通信系统中的误码率性能。在适用于LTE-A的空间信道扩展模型(spatial channel model extension,SCME)信道环境下进行了仿真,仿真结果表明,该方法相比常用的基于信干噪比准则的块对角化方案误码率性能有明显提升,且能在存在射频增益影响的非理想环境中恢复信道互易性,提升系统传输性能。展开更多
不同基站和用户间由于距离变化等使传播时延不同而造成小区间的迟延干扰,严重恶化了系统性能。为此,探讨了如何利用SLNR(Signal to Leakage Noise Ratio)预编码抑制小区间的迟延干扰,给出了小区协作的系统模型及小区间迟延干扰分析。针...不同基站和用户间由于距离变化等使传播时延不同而造成小区间的迟延干扰,严重恶化了系统性能。为此,探讨了如何利用SLNR(Signal to Leakage Noise Ratio)预编码抑制小区间的迟延干扰,给出了小区协作的系统模型及小区间迟延干扰分析。针对存在迟延的LTE(Long Term Evolution)系统设计了一种基于SLNR准则的迟延SLNR预编码,以抑制小区间的迟延干扰,降低接收终端的复杂度。同时,对迟延SLNR预编码在LTE系统多基站协作环境下的性能进行了仿真。仿真结果表明,该方法对小区间的迟延干扰有较好的抑制作用,对不同天线配置性能均较理想,与接收端处理方案比较性能有所改进。虽然信道估计误差对性能有一定影响,但在可接受范围。展开更多
针对多小区下行多进单出(multiple-input single-output,MISO)干扰信道,在控制每个用户信漏噪比(signal to leakage plus noise ratio,SLNR)低于门限值的概率小于中断概率的约束条件下,以最小化系统总加权发射功率为优化目标设计线性预...针对多小区下行多进单出(multiple-input single-output,MISO)干扰信道,在控制每个用户信漏噪比(signal to leakage plus noise ratio,SLNR)低于门限值的概率小于中断概率的约束条件下,以最小化系统总加权发射功率为优化目标设计线性预编码。利用半定松弛和Bernstein-type不等式,将非凸的具有随机性的原始优化问题转换为确定性凸优化问题。仿真结果表明,所提出的预编码设计比worst-case等比较方案耗费的总加权发射功率更少。展开更多
Coordinated multi-point （CoMP） transmission is put forward in the long term evolution-advanced （LTE-A） system to improve both average and cell-edge throughput. CoMP-joint pro- cessing （JP） scheme can get a large...Coordinated multi-point （CoMP） transmission is put forward in the long term evolution-advanced （LTE-A） system to improve both average and cell-edge throughput. CoMP-joint pro- cessing （JP） scheme can get a larger cell-edge throughput and a lower bit error rate （BER） than the CoMP-coordinated beamform- ing （CB） scheme, but it also has higher complexity due to data sharing. A hybrid coordinated strategy with parameter c~, which indicates the proportion of users employing the CoMP-JP scheme, is proposed to apply the CoMP-JP scheme to improve the poorer communication quality of cell edge and employ the CoMP-CB scheme for other users to enhance average throughput and spec- tral efficiency. This paradigm selects users defined by the certain threshold of signal to interference plus noise power ratio （SINR） corresponding to the parameter a to the CoMP-JP scheme. This paper compares the BER performance between the block diag- onalization （BD） based precoding and the linear precoders by maximizing signal to leakage and noise ratio （SLNR）, and also in- dicates that the SLNR based precoding algorithm gets lower BER than the BD based precoding algorithm with certain signal-to-noise ratios （SNRs）. Finally, this paper discusses that the system perfor- mance is partially affected by the percentage of CoMP-JP users and concludes that 50% of users sorted to communicate under the CoMP-JP scheme will reach the best system performance.展开更多
In this paper, the design of linear leakage-based precoders is considered for multiple-input multiple-output （MIMO） downlinks. Our proposed scheme minimizes total transmit power under each user＇s signal-to-leakage-...In this paper, the design of linear leakage-based precoders is considered for multiple-input multiple-output （MIMO） downlinks. Our proposed scheme minimizes total transmit power under each user＇s signal-to-leakage-plus-noise ratio （SLNR） constraint. When the base station knows perfect channel state information （CSI）, suitable reformulation of design problem allows the successful application of semidefinite relaxation （SDR） techniques. When the base station knows imperfect CSI with limited estimation errors, the design problem can be solved using semidefinite program （SDP）. At the same time, it can dynamically allocate each user＇s SLNR threshold according to each user＇s channel state, so it is more feasible than other similar S1NR-based precoding methods. Simulation results show that using large SLNR thresholds, the proposed design has better bit error rate （BER） performance than maximal-SLNR precoding method at high signal-to-noise ratio （SNR）. Moreover, when the base station knows imperfect channel state information, the proposed precoder is robust to channel estimation errors, and has better BER preformance than other similar SINR-based precoding methods.展开更多
Well-controlled resource allocation is crucial for promoting the performance of multiple input multiple output orthogonal frequency division multiplexing(MIMO-OFDM) systems. Recent studies have focused primarily on tr...Well-controlled resource allocation is crucial for promoting the performance of multiple input multiple output orthogonal frequency division multiplexing(MIMO-OFDM) systems. Recent studies have focused primarily on traditional centralized systems or distributed antenna systems(DASs), and usually assumed that one sub-carrier or sub-channel is exclusively occupied by one user. To promote system performance, we propose a sub-channel shared resource allocation algorithm for multiuser distributed MIMO-OFDM systems. Each sub-channel can be shared by multiple users in the algorithm, which is different from previous algorithms. The algorithm assumes that each user communicates with only two best ports in the system. On each sub-carrier, it allocates a sub-channel in descending order, which means one sub-channel that can minimize signal to leakage plus noise ratio(SLNR) loss is deleted until the number of remaining sub-channels is equal to that of receiving antennas. If there are still sub-channels after all users are processed, these sub-channels will be allocated to users who can maximize the SLNR gain. Simulations show that compared to other algorithms, our proposed algorithm has better capacity performance and enables the system to provide service to more users under the same capacity constraints.展开更多
In wideband multi-pair two-way relay networks, the performance of beamforming at a relay station(RS) is intimately related to the accuracy of the channel state information(CSI) available. The accuracy of CSI is determ...In wideband multi-pair two-way relay networks, the performance of beamforming at a relay station(RS) is intimately related to the accuracy of the channel state information(CSI) available. The accuracy of CSI is determined by Doppler spread, delay between beamforming and channel estimation, and density of pilot symbols,including transmit power of pilot symbols. The coefficient of the Gaussian-Markov CSI error model is modeled as a function of CSI delay, Doppler spread, and signal-to-noise ratio, and can be estimated in real time. In accordance with the real-time estimated coefficients of the error model, an adaptive robust maximum signal-to-interferenceand-noise ratio(Max-SINR) plus maximum signal-to-leakage-and-noise ratio(Max-SLNR) beamformer at an RS is proposed to track the variation of the CSI error. From simulation results and analysis, it is shown that: compared to existing non-adaptive beamformers, the proposed adaptive beamformer is more robust and performs much better in the sense of bit error rate(BER); with increase in the density of transmit pilot symbols, its BER and sum-rate performances tend to those of the beamformer of Max-SINR plus Max-SLNR with ideal CSI.展开更多
文摘提出了一种长期演进项目的后续演进(long term evolution-advanced,LTE-A)中的信漏噪比联合校准多用户多流波束赋形方案。基于信漏噪比准则进行波束赋形消除多用户间干扰,实现LTE-A下的多用户多流波束赋形传输;建立信道校准机制,补偿实际通信系统中的射频增益影响,恢复信道互易性,提升实际通信系统中的误码率性能。在适用于LTE-A的空间信道扩展模型(spatial channel model extension,SCME)信道环境下进行了仿真,仿真结果表明,该方法相比常用的基于信干噪比准则的块对角化方案误码率性能有明显提升,且能在存在射频增益影响的非理想环境中恢复信道互易性,提升系统传输性能。
文摘不同基站和用户间由于距离变化等使传播时延不同而造成小区间的迟延干扰,严重恶化了系统性能。为此,探讨了如何利用SLNR(Signal to Leakage Noise Ratio)预编码抑制小区间的迟延干扰,给出了小区协作的系统模型及小区间迟延干扰分析。针对存在迟延的LTE(Long Term Evolution)系统设计了一种基于SLNR准则的迟延SLNR预编码,以抑制小区间的迟延干扰,降低接收终端的复杂度。同时,对迟延SLNR预编码在LTE系统多基站协作环境下的性能进行了仿真。仿真结果表明,该方法对小区间的迟延干扰有较好的抑制作用,对不同天线配置性能均较理想,与接收端处理方案比较性能有所改进。虽然信道估计误差对性能有一定影响,但在可接受范围。
文摘针对多小区下行多进单出(multiple-input single-output,MISO)干扰信道,在控制每个用户信漏噪比(signal to leakage plus noise ratio,SLNR)低于门限值的概率小于中断概率的约束条件下,以最小化系统总加权发射功率为优化目标设计线性预编码。利用半定松弛和Bernstein-type不等式,将非凸的具有随机性的原始优化问题转换为确定性凸优化问题。仿真结果表明,所提出的预编码设计比worst-case等比较方案耗费的总加权发射功率更少。
基金supported by the National Science and Technology Major Project of China(2013ZX03001024-003)
文摘Coordinated multi-point （CoMP） transmission is put forward in the long term evolution-advanced （LTE-A） system to improve both average and cell-edge throughput. CoMP-joint pro- cessing （JP） scheme can get a larger cell-edge throughput and a lower bit error rate （BER） than the CoMP-coordinated beamform- ing （CB） scheme, but it also has higher complexity due to data sharing. A hybrid coordinated strategy with parameter c~, which indicates the proportion of users employing the CoMP-JP scheme, is proposed to apply the CoMP-JP scheme to improve the poorer communication quality of cell edge and employ the CoMP-CB scheme for other users to enhance average throughput and spec- tral efficiency. This paradigm selects users defined by the certain threshold of signal to interference plus noise power ratio （SINR） corresponding to the parameter a to the CoMP-JP scheme. This paper compares the BER performance between the block diag- onalization （BD） based precoding and the linear precoders by maximizing signal to leakage and noise ratio （SLNR）, and also in- dicates that the SLNR based precoding algorithm gets lower BER than the BD based precoding algorithm with certain signal-to-noise ratios （SNRs）. Finally, this paper discusses that the system perfor- mance is partially affected by the percentage of CoMP-JP users and concludes that 50% of users sorted to communicate under the CoMP-JP scheme will reach the best system performance.
基金supported by the National Natural Science Foudation of China (60972046)the S&T Major Special Project (2009ZX03003-11-05, 2010ZX03003-003)the Scientific Research Program Funded by Shaanxi Provincial Education Commission (2010JK666)
文摘In this paper, the design of linear leakage-based precoders is considered for multiple-input multiple-output （MIMO） downlinks. Our proposed scheme minimizes total transmit power under each user＇s signal-to-leakage-plus-noise ratio （SLNR） constraint. When the base station knows perfect channel state information （CSI）, suitable reformulation of design problem allows the successful application of semidefinite relaxation （SDR） techniques. When the base station knows imperfect CSI with limited estimation errors, the design problem can be solved using semidefinite program （SDP）. At the same time, it can dynamically allocate each user＇s SLNR threshold according to each user＇s channel state, so it is more feasible than other similar S1NR-based precoding methods. Simulation results show that using large SLNR thresholds, the proposed design has better bit error rate （BER） performance than maximal-SLNR precoding method at high signal-to-noise ratio （SNR）. Moreover, when the base station knows imperfect channel state information, the proposed precoder is robust to channel estimation errors, and has better BER preformance than other similar SINR-based precoding methods.
基金Project supported by the National High-Tech R&D Program(863) of China(Nos.2012AA01A502 and 2012AA01A505)
文摘Well-controlled resource allocation is crucial for promoting the performance of multiple input multiple output orthogonal frequency division multiplexing(MIMO-OFDM) systems. Recent studies have focused primarily on traditional centralized systems or distributed antenna systems(DASs), and usually assumed that one sub-carrier or sub-channel is exclusively occupied by one user. To promote system performance, we propose a sub-channel shared resource allocation algorithm for multiuser distributed MIMO-OFDM systems. Each sub-channel can be shared by multiple users in the algorithm, which is different from previous algorithms. The algorithm assumes that each user communicates with only two best ports in the system. On each sub-carrier, it allocates a sub-channel in descending order, which means one sub-channel that can minimize signal to leakage plus noise ratio(SLNR) loss is deleted until the number of remaining sub-channels is equal to that of receiving antennas. If there are still sub-channels after all users are processed, these sub-channels will be allocated to users who can maximize the SLNR gain. Simulations show that compared to other algorithms, our proposed algorithm has better capacity performance and enables the system to provide service to more users under the same capacity constraints.
基金Project supported by the Open Research Fund of National Mobile Communications Research Laboratory,Southeast University,China(No.2013D02)the Open Research Fund of National Key Laboratory of Electromagnetic Environment,China Research Institute of Radiowave Propagation(No.201500013)+2 种基金the National Natural Science Foundation of China(Nos.61271230,61472190,and 61501238)the Research Fund for the Doctoral Program of Higher Education of China(No.20113219120019)the Jiangsu Provincial Science Foundation Project,China(No.BK20150786)
文摘In wideband multi-pair two-way relay networks, the performance of beamforming at a relay station(RS) is intimately related to the accuracy of the channel state information(CSI) available. The accuracy of CSI is determined by Doppler spread, delay between beamforming and channel estimation, and density of pilot symbols,including transmit power of pilot symbols. The coefficient of the Gaussian-Markov CSI error model is modeled as a function of CSI delay, Doppler spread, and signal-to-noise ratio, and can be estimated in real time. In accordance with the real-time estimated coefficients of the error model, an adaptive robust maximum signal-to-interferenceand-noise ratio(Max-SINR) plus maximum signal-to-leakage-and-noise ratio(Max-SLNR) beamformer at an RS is proposed to track the variation of the CSI error. From simulation results and analysis, it is shown that: compared to existing non-adaptive beamformers, the proposed adaptive beamformer is more robust and performs much better in the sense of bit error rate(BER); with increase in the density of transmit pilot symbols, its BER and sum-rate performances tend to those of the beamformer of Max-SINR plus Max-SLNR with ideal CSI.
