Interference cancellation scheme without feedback is proposed for X channels with four antennas at each user. Space-time codeword with Alamouti structure is designed for each user. Codewords are combined according a c...Interference cancellation scheme without feedback is proposed for X channels with four antennas at each user. Space-time codeword with Alamouti structure is designed for each user. Codewords are combined according a certain rule. The unwanted codewords are cancelled by linear operation on the received signals. Then, multi-user interference is mitigated by the orthogonal property of the Alamouti code. Comparing with the existing scheme for the same scene, feedback information is not required in the proposed scheme. So the transmission efficiency is improved.展开更多
A multiple-input multiple-output interleave division multiple access (MIMO-IDMA) system with Triple Polarized Division Multiplexing (TPDM) is presented in this paper. The present methodology replaces three indepe...A multiple-input multiple-output interleave division multiple access (MIMO-IDMA) system with Triple Polarized Division Multiplexing (TPDM) is presented in this paper. The present methodology replaces three independent linearly polarized antennas with a single triple polarized antenna at both the transmitter and receiver. The users in the communication link are accommodated and separated using a user-specific interleaver combined with low rate spreading sequence. To eliminate the effects of multi-stream interference (MSI), minimum mean square error (MMSE) algorithm based on successive interference cancellation (SIC) Multi-user detection (MUD) technique is employed at the receiver. Furthermore, log-maximum a posteriori probability (MAPP) decoding algorithm is implemented at the mobile stations (MSs) to overcome the effects of multi-user interference (MUI) effects. The paper also evaluates the effects of coded MIMO-IDMA in the downlink communication by adopting the Stanford University Interim (SUI) and Long-term Evolution (LTE)channel model specifications. In comparison with the traditional uncoded system, the present solution considering turbo coded triple-polarized MIMO-IDMA system with iterative decoding algorithm provides better bit error rate (BER) with reduced signal to noise ratio (SNR). The simulation results also show that though the SNR requirement is higher for the proposed technique compared to the conventional uni-polarized antenna based MIMO-IDMA system, it gives the advantages of achieving higher data rate with reduced cost and space requirements in the context of a downlink (DL).展开更多
In this paper, we propose two joint transmit-receive iterative algorithms without the cooperation between different base stations based on the idea of interference alignment (IA) to improve the throughput of relay bac...In this paper, we propose two joint transmit-receive iterative algorithms without the cooperation between different base stations based on the idea of interference alignment (IA) to improve the throughput of relay backhaul links in cellular networks for the case of imperfect channel knowledge,which can be implemented with small changes to existing TD-LTE standards. Unlike the previous interference alignment algorithms' only reducing the sum interference to the other receivers at the transmitter or the sum received Multi-user interference (MUI) at the receiver, our algorithm shapes the transmission of each data stream at transmitters in order not only to minimize interference to the other users, but also to minimize the interference between different streams objected to the same user, suppressing the MUI and Multi-stream interference (MSI) at receivers. The proposed algorithm I is to maximize the SINR at receivers. But the complexity is relatively high. Algorithm II only needs linear operations and sacrifices a little performance for much lower complexity compared to the Maximize SINR iterative algorithm which needs the inversion operation of matrix. It is also proved that the algorithm converges monotonically. The simulation results show that the techniques have considerable performance gain compared with the previous algorithms. Further research about power allocation is also discussed.展开更多
Multiple Path Interference (MPI) and Multiple Access Interference (MAI) are important factors that affect the performance of Chinese Area Positioning System (CAPS). These problems can be solved by using spreading sequ...Multiple Path Interference (MPI) and Multiple Access Interference (MAI) are important factors that affect the performance of Chinese Area Positioning System (CAPS). These problems can be solved by using spreading sequences with ideal properties and multi-user detectors. Chaotic sequences based on Chebyshev map are studied and the satellite communication system model is set up to investigate the application of chaotic sequences for CAPS in this paper. Simulation results show that chaotic sequences have desirable correlation properties and it is easy to generate a large number of chaotic sequences with good security. It has great practical value to apply chaotic sequences to CAPS together with multi-user detecting technology and the system performance can be improved greatly.展开更多
For reducing the inter-user interference in multi-user multiple-input multiple-output(MU-MIMO) wireless communication systems,e.g.,MIMO-orthogonal frequency division multiplexing(MIMO-OFDM) systems,it is often des...For reducing the inter-user interference in multi-user multiple-input multiple-output(MU-MIMO) wireless communication systems,e.g.,MIMO-orthogonal frequency division multiplexing(MIMO-OFDM) systems,it is often desirable to the complex preprocessing at the transmitter.This paper proposes a multi-user beamforming algorithm with sub-codebook selection.Based on the minimal leakage criterion,the codebook selection,limited feed-forward and minimum mean square error(MMSE) detection are combined in the proposed algorithm.This avoids the complex channel matrix decomposition and inversion.Consequently,the computational complexity at the transmitter is significantly reduced.Simulation results show that the proposed algorithm performs better than existing beamforming algorithms.展开更多
To minimize transmitting power,an adaptive resource allocation algorithm is proposed for multi-user multiple input multiple output-orthogonal frequency division multiplexing(MIMO-OFDM)downlink with correlated channels...To minimize transmitting power,an adaptive resource allocation algorithm is proposed for multi-user multiple input multiple output-orthogonal frequency division multiplexing(MIMO-OFDM)downlink with correlated channels,which,based on the user’s grouping according to their spatial correlations,combines the shared manner and the exclusive manner to allocate sub-carriers.Between different groups the shared manner with a null steering method based on group marginal users is applied,whereas within a group the exclusive manner is applied.The simulations show that the power efficiency and spectral efficiency are improved;the base station transmitting antenna number and the computational complexity is decreased.展开更多
The authors in this article investigated how to cancel multi-user interference with low feedback amount over 3-user multiple input multiple output (MIMO) interference channel using space-time code and precoders. Spa...The authors in this article investigated how to cancel multi-user interference with low feedback amount over 3-user multiple input multiple output (MIMO) interference channel using space-time code and precoders. Space-time block code with coding rate 2 was designed, also zero vectors were introduced into each codeword. The multi-user interference is mitigated by pre-coding at the transmitters and nonlinear operation and unidirectional cooperation link at the receivers. Compared with the existing scheme for the same scene, the proposed scheme greatly reduces feedback amount and improves the sum degrees of freedom (DOF). Simulation demonstrates the validity of the proposed scheme.展开更多
With the development of micro-satellite technology,traditional monolithic satellites can be replaced by micro-satellite clusters to achieve high flexibility and dynamic reconfiguration capability.For satellite cluster...With the development of micro-satellite technology,traditional monolithic satellites can be replaced by micro-satellite clusters to achieve high flexibility and dynamic reconfiguration capability.For satellite clusters based on the frequency division-code division multiple access(FD-CDMA)communication system,the inter-satellite ranging precision is usually constrained due to the influence ofmulti-address interference(MAI).Themulti-user detection(MUD)is a solution to MAI,which can be divided into two categories:the linear detector(LD)and the non-linear detector(NLD).The general idea of the LD is aiming to make a better decision during the symbol decision process by using the information of all channels.However,it is not beneficial for the signal phase tracking precision.Instead,the principle of the NLD is to rebuild the interference signal and cancel it from the original one,which can improve the ranging performance at the expense of considerable delays.In order to enable simultaneous ranging and communication and reduce multi-node ranging performance degradation,this paper proposes an NLD scheme based on a delay locked loop(DLL),which simplifies the receiver structure and introduces no delay in the decision process.This scheme utilizes the information obtained from the interference channel to reconstruct the interference signal and then cancels it from the original delayed signal.Therefore,the DLL input signal-to-interference ratio(SIR)of the desired channel can be significantly improved.The experimental results show that with the proposed scheme,the standard deviation of the tracking steady error is decreased from 5.59 cm to 3.97 cm for SIR=5 dB,and 13.53 cm to 5.77 cm for SIR=-5 dB,respectively.展开更多
Multi-access interference(MAI)is the main source limiting the capacity and quality of the multiple-input multipleoutput orthogonal frequency division multiplexing(MIMO-OFDM)system which fulfills the demand of high-spe...Multi-access interference(MAI)is the main source limiting the capacity and quality of the multiple-input multipleoutput orthogonal frequency division multiplexing(MIMO-OFDM)system which fulfills the demand of high-speed transmission rate and high quality of service for future underwater acoustic(UWA)communication.Therefore,multi-user detection(MUD)is needed at the receiver of the MIMO-OFDM system to suppress the effect of MAI.In this research,MUD is achieved by using a criterion based adaptive recursive successive interference cancellation(RSIC)scheme at the receiver of a MIMO-OFDM system whose transceiver model in underwater communication is implemented by using the Bellhop simulation system.The proposed scheme estimates and eliminates the MAI through user signal detection and subtraction from received signals at the receiver of the MIMO-OFDM system in underwater environment.The bit error rate(BER)performance of the proposed scheme is analyzed by using weight filtering and weight selection criteria.By Matlab simulation,it is shown that the BER performance of the proposed scheme outperforms the conventional matched filter(MF)detector,the adaptive successive interference cancellation(SIC)scheme,and the adaptive RSIC scheme in the UWA network.展开更多
The article investigates how to send perfect space-time codes with low feedback amount and symbol-by-symbol decoding for X channel using precoders. It is assumed that two users are introduced with two antennas and two...The article investigates how to send perfect space-time codes with low feedback amount and symbol-by-symbol decoding for X channel using precoders. It is assumed that two users are introduced with two antennas and two receivers. Each user employs a rate-2 space-time block code and follows certain rule when sending codewords. The multi-user interference is eliminated by pre-coding at the transmitter and linear processing at the receiver. Compared with the existing scheme for the same scene, the proposed scheme greatly reduces feedback amount and improves the transmission efficiency, while keeping the same decoding complexity. Simulations demonstrate the validity of the proposed scheme.展开更多
An adaptive multi-user detector was developed for direct-sequence code division multiple access(DS-CDMA)systems corrupted by non-Gaussian channel noise,which can be quite detrimental to the performance of the multi-us...An adaptive multi-user detector was developed for direct-sequence code division multiple access(DS-CDMA)systems corrupted by non-Gaussian channel noise,which can be quite detrimental to the performance of the multi-user detectors based on classical white Gaussian assumption.This receiver simultaneously combats multiple-access interference(MAI)and non-Gaussian impulsive noise.The channel parameters are estimated and transmitted signals are jointly detected by a simple recursive algorithm derived from the EM/SAGE algorithm.Analytical and simulation results show that the proposed technique is robust with wider applicability than conventional multi-user detectors in terms of near-far resistance and bit-error ratio(BER)when either MAI or non-Gaussian impulsive noise is dominant.展开更多
文摘Interference cancellation scheme without feedback is proposed for X channels with four antennas at each user. Space-time codeword with Alamouti structure is designed for each user. Codewords are combined according a certain rule. The unwanted codewords are cancelled by linear operation on the received signals. Then, multi-user interference is mitigated by the orthogonal property of the Alamouti code. Comparing with the existing scheme for the same scene, feedback information is not required in the proposed scheme. So the transmission efficiency is improved.
文摘A multiple-input multiple-output interleave division multiple access (MIMO-IDMA) system with Triple Polarized Division Multiplexing (TPDM) is presented in this paper. The present methodology replaces three independent linearly polarized antennas with a single triple polarized antenna at both the transmitter and receiver. The users in the communication link are accommodated and separated using a user-specific interleaver combined with low rate spreading sequence. To eliminate the effects of multi-stream interference (MSI), minimum mean square error (MMSE) algorithm based on successive interference cancellation (SIC) Multi-user detection (MUD) technique is employed at the receiver. Furthermore, log-maximum a posteriori probability (MAPP) decoding algorithm is implemented at the mobile stations (MSs) to overcome the effects of multi-user interference (MUI) effects. The paper also evaluates the effects of coded MIMO-IDMA in the downlink communication by adopting the Stanford University Interim (SUI) and Long-term Evolution (LTE)channel model specifications. In comparison with the traditional uncoded system, the present solution considering turbo coded triple-polarized MIMO-IDMA system with iterative decoding algorithm provides better bit error rate (BER) with reduced signal to noise ratio (SNR). The simulation results also show that though the SNR requirement is higher for the proposed technique compared to the conventional uni-polarized antenna based MIMO-IDMA system, it gives the advantages of achieving higher data rate with reduced cost and space requirements in the context of a downlink (DL).
基金Sponsored by the Important National Science & Technology Specific Projects of China (Grant No. 2009ZX03004-001)the Cooperation Project with Huawei Technologies Company (Grant No. YBWL2010242)
文摘In this paper, we propose two joint transmit-receive iterative algorithms without the cooperation between different base stations based on the idea of interference alignment (IA) to improve the throughput of relay backhaul links in cellular networks for the case of imperfect channel knowledge,which can be implemented with small changes to existing TD-LTE standards. Unlike the previous interference alignment algorithms' only reducing the sum interference to the other receivers at the transmitter or the sum received Multi-user interference (MUI) at the receiver, our algorithm shapes the transmission of each data stream at transmitters in order not only to minimize interference to the other users, but also to minimize the interference between different streams objected to the same user, suppressing the MUI and Multi-stream interference (MSI) at receivers. The proposed algorithm I is to maximize the SINR at receivers. But the complexity is relatively high. Algorithm II only needs linear operations and sacrifices a little performance for much lower complexity compared to the Maximize SINR iterative algorithm which needs the inversion operation of matrix. It is also proved that the algorithm converges monotonically. The simulation results show that the techniques have considerable performance gain compared with the previous algorithms. Further research about power allocation is also discussed.
基金Supported by the National Basic Research Program of China (Grant No. 2007CB815500)the National High Technology Research and Development Program of China (Grant No. 2007AA12z343)
文摘Multiple Path Interference (MPI) and Multiple Access Interference (MAI) are important factors that affect the performance of Chinese Area Positioning System (CAPS). These problems can be solved by using spreading sequences with ideal properties and multi-user detectors. Chaotic sequences based on Chebyshev map are studied and the satellite communication system model is set up to investigate the application of chaotic sequences for CAPS in this paper. Simulation results show that chaotic sequences have desirable correlation properties and it is easy to generate a large number of chaotic sequences with good security. It has great practical value to apply chaotic sequences to CAPS together with multi-user detecting technology and the system performance can be improved greatly.
基金support by the National Natural Science Foundation of China (60702060)the 111 Project
文摘For reducing the inter-user interference in multi-user multiple-input multiple-output(MU-MIMO) wireless communication systems,e.g.,MIMO-orthogonal frequency division multiplexing(MIMO-OFDM) systems,it is often desirable to the complex preprocessing at the transmitter.This paper proposes a multi-user beamforming algorithm with sub-codebook selection.Based on the minimal leakage criterion,the codebook selection,limited feed-forward and minimum mean square error(MMSE) detection are combined in the proposed algorithm.This avoids the complex channel matrix decomposition and inversion.Consequently,the computational complexity at the transmitter is significantly reduced.Simulation results show that the proposed algorithm performs better than existing beamforming algorithms.
基金supported by the National Natural Science Foundation of China (Grant No.60572039).
文摘To minimize transmitting power,an adaptive resource allocation algorithm is proposed for multi-user multiple input multiple output-orthogonal frequency division multiplexing(MIMO-OFDM)downlink with correlated channels,which,based on the user’s grouping according to their spatial correlations,combines the shared manner and the exclusive manner to allocate sub-carriers.Between different groups the shared manner with a null steering method based on group marginal users is applied,whereas within a group the exclusive manner is applied.The simulations show that the power efficiency and spectral efficiency are improved;the base station transmitting antenna number and the computational complexity is decreased.
基金supported in part by the National Natural Science Foundation of China (51174263)
文摘The authors in this article investigated how to cancel multi-user interference with low feedback amount over 3-user multiple input multiple output (MIMO) interference channel using space-time code and precoders. Space-time block code with coding rate 2 was designed, also zero vectors were introduced into each codeword. The multi-user interference is mitigated by pre-coding at the transmitters and nonlinear operation and unidirectional cooperation link at the receivers. Compared with the existing scheme for the same scene, the proposed scheme greatly reduces feedback amount and improves the sum degrees of freedom (DOF). Simulation demonstrates the validity of the proposed scheme.
基金supported by the China National Funds of Distributed Young Scientists(61525403)the Fundamental Research Funds for the Central Universities(2018QNA4053)
文摘With the development of micro-satellite technology,traditional monolithic satellites can be replaced by micro-satellite clusters to achieve high flexibility and dynamic reconfiguration capability.For satellite clusters based on the frequency division-code division multiple access(FD-CDMA)communication system,the inter-satellite ranging precision is usually constrained due to the influence ofmulti-address interference(MAI).Themulti-user detection(MUD)is a solution to MAI,which can be divided into two categories:the linear detector(LD)and the non-linear detector(NLD).The general idea of the LD is aiming to make a better decision during the symbol decision process by using the information of all channels.However,it is not beneficial for the signal phase tracking precision.Instead,the principle of the NLD is to rebuild the interference signal and cancel it from the original one,which can improve the ranging performance at the expense of considerable delays.In order to enable simultaneous ranging and communication and reduce multi-node ranging performance degradation,this paper proposes an NLD scheme based on a delay locked loop(DLL),which simplifies the receiver structure and introduces no delay in the decision process.This scheme utilizes the information obtained from the interference channel to reconstruct the interference signal and then cancels it from the original delayed signal.Therefore,the DLL input signal-to-interference ratio(SIR)of the desired channel can be significantly improved.The experimental results show that with the proposed scheme,the standard deviation of the tracking steady error is decreased from 5.59 cm to 3.97 cm for SIR=5 dB,and 13.53 cm to 5.77 cm for SIR=-5 dB,respectively.
文摘Multi-access interference(MAI)is the main source limiting the capacity and quality of the multiple-input multipleoutput orthogonal frequency division multiplexing(MIMO-OFDM)system which fulfills the demand of high-speed transmission rate and high quality of service for future underwater acoustic(UWA)communication.Therefore,multi-user detection(MUD)is needed at the receiver of the MIMO-OFDM system to suppress the effect of MAI.In this research,MUD is achieved by using a criterion based adaptive recursive successive interference cancellation(RSIC)scheme at the receiver of a MIMO-OFDM system whose transceiver model in underwater communication is implemented by using the Bellhop simulation system.The proposed scheme estimates and eliminates the MAI through user signal detection and subtraction from received signals at the receiver of the MIMO-OFDM system in underwater environment.The bit error rate(BER)performance of the proposed scheme is analyzed by using weight filtering and weight selection criteria.By Matlab simulation,it is shown that the BER performance of the proposed scheme outperforms the conventional matched filter(MF)detector,the adaptive successive interference cancellation(SIC)scheme,and the adaptive RSIC scheme in the UWA network.
基金supported by the National Natural Science Foundation of China (51174263)the Natural Science Foundation of Henan (132300410461)
文摘The article investigates how to send perfect space-time codes with low feedback amount and symbol-by-symbol decoding for X channel using precoders. It is assumed that two users are introduced with two antennas and two receivers. Each user employs a rate-2 space-time block code and follows certain rule when sending codewords. The multi-user interference is eliminated by pre-coding at the transmitter and linear processing at the receiver. Compared with the existing scheme for the same scene, the proposed scheme greatly reduces feedback amount and improves the transmission efficiency, while keeping the same decoding complexity. Simulations demonstrate the validity of the proposed scheme.
基金supported by the National Natural Science Foundation of China(No.60072001).
文摘An adaptive multi-user detector was developed for direct-sequence code division multiple access(DS-CDMA)systems corrupted by non-Gaussian channel noise,which can be quite detrimental to the performance of the multi-user detectors based on classical white Gaussian assumption.This receiver simultaneously combats multiple-access interference(MAI)and non-Gaussian impulsive noise.The channel parameters are estimated and transmitted signals are jointly detected by a simple recursive algorithm derived from the EM/SAGE algorithm.Analytical and simulation results show that the proposed technique is robust with wider applicability than conventional multi-user detectors in terms of near-far resistance and bit-error ratio(BER)when either MAI or non-Gaussian impulsive noise is dominant.