In recent years,as giant satellite constellations grow rapidly worldwide,the co-existence between constellations has been widely concerned.In this paper,we overview the co-frequency interference(CFI)among the giant no...In recent years,as giant satellite constellations grow rapidly worldwide,the co-existence between constellations has been widely concerned.In this paper,we overview the co-frequency interference(CFI)among the giant non-geostationary orbit(NGSO)constellations.Specifically,we first summarize the CFI scenario and evaluation index among different NGSO constellations.Based on statistics about NGSO constellation plans,we analyse the challenges in mitigation and analysis of CFI.Next,the CFI calculation methods and research progress are systematically sorted out from the aspects of interference risk analysis framework,numerical calculation and link construction.Then,the feasibility of interference mitigation technologies based on space,frequency domain isolation,power control,and interference alignment mitigation in the NGSO mega-constellation CFI scenario are further sorted out.Finally,we present promising directions for future research in CFI analysis and CFI avoidance.展开更多
Co-frequency and co-time full duplex(CCFD) is a promising technique for improving spectral efficiency in next generation wireless communication systems. However, for the applications of CCFD in a cellular network, sev...Co-frequency and co-time full duplex(CCFD) is a promising technique for improving spectral efficiency in next generation wireless communication systems. However, for the applications of CCFD in a cellular network, severe co-channel interference is an essential problem. Specifically, there are two significant interferences, i.e., inter-terminal interference(ITI) and inter-cell interference(ICI), which lead to an obvious performance degradation. In this paper, two techniques are proposed for suppressing the ITI and ICI in a CCFD cellular system, respectively. The first technique is obtained by modeling the three-node CCFD system as the Z-channel. After deriving the sum-capacity of the Z-channel, a sum-capacity-achieving scheme based on successive interference cancellation(SIC) is proposed. The second technique is designed by combining the fractional frequency reuse scheme with CCFD. The performance gains of the proposed two techniques in terms of signalto-interference plus noise ratio(SINR) and sumcapacity are analyzed. Simulation results show that the proposed scheme can achieve significant interference suppression performance and higher system capacity, especially for cell edge users.展开更多
An asynchronous transmission scenario for non-orthogonal multiple access(NOMA)user signals with arbitrary phase offset is investigated in this paper.To improve the system performance in the user power-balanced conditi...An asynchronous transmission scenario for non-orthogonal multiple access(NOMA)user signals with arbitrary phase offset is investigated in this paper.To improve the system performance in the user power-balanced conditions,we adopt a synthetic detection method at the receiver,i.e.,the jointly optimal maximal likelihood detection aided triangular successive interference cancellation(JO ML-TSIC)method.Analytical bit error rate(BER)solutions are obtained for a two-user case with the optimal,intentional onehalf symbol period time delay implemented between the user signals.Furthermore,closed-form BER solutions for the case using the triangular successive interference cancellation(TSIC)detection method are also derived for comparisons.Numerical results show that the JO ML-TSIC receiver for the asynchronous system outperforms the TSIC receiver as well as the synchronous successive interference cancellation(SIC)receiver in all the conditions concerned.The results also show that the superiority of the JO ML-TSIC receiver is strengthened when the signals experience flat Rayleigh fading channels compared to the TSIC and the synchronous SIC receivers.展开更多
In this paper, Moose scheme is used for frequency offset estimation in OFDMA uplink svstems due to that the signals from different users can be easily distinguished in frequency domain. However, differential multiple ...In this paper, Moose scheme is used for frequency offset estimation in OFDMA uplink svstems due to that the signals from different users can be easily distinguished in frequency domain. However, differential multiple access interference （MAI） will deteriorate the frequency offset estimation performances, especially in interleaved OFDMA system. Analysis and simulation results manifest that frequency offset estimation by Moose scheme in block OFDMA system is more robust than that in interleaved OFDMA systern. And an iterative interference cancellation method has been proposed to suppress the differential MAI interference for interleaved OFDMA system, in which Moose scheme is the special case of the number of iteration is equal to one. Simulation results demonstrate that the proposed method can improve the performance with the increase of the number of iterations. In consideration of the performance and complexity, the proposed method with two iterations is selected. And the full comparison results of the proposed iterative method with two iterations and that with one iteration （conventional Moose scheme） are given in the paper, which sufficiently demonstrate that the performance gain can be obtained by the interference cancellation operation in interleaved OFDMA system.展开更多
The V-BLAST system with asynchronous transmission mode first proposed by Shao can achieve full diversity only by using a simple linear detection scheme under zero forcing （ZF） criterion; therefore it gives a reasona...The V-BLAST system with asynchronous transmission mode first proposed by Shao can achieve full diversity only by using a simple linear detection scheme under zero forcing （ZF） criterion; therefore it gives a reasonable tradeoff between complexity and performance. In this paper, we propose two types of successive interference cancellation （SIC） detection schemes for the asynchronous V-BLAST system, one is characterized by applying Mr successive interference cancellators before a maximal ratio combiner （where Mr is the number of receive antennas）, and the other has a maximal ratio combiner before a successive interference cancellator. Since Type Ⅰ consumes more energy of the previously detected signals to recover a signal, Type Ⅱ can offer a better performance and simulations demonstrate its validity.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
文摘In recent years,as giant satellite constellations grow rapidly worldwide,the co-existence between constellations has been widely concerned.In this paper,we overview the co-frequency interference(CFI)among the giant non-geostationary orbit(NGSO)constellations.Specifically,we first summarize the CFI scenario and evaluation index among different NGSO constellations.Based on statistics about NGSO constellation plans,we analyse the challenges in mitigation and analysis of CFI.Next,the CFI calculation methods and research progress are systematically sorted out from the aspects of interference risk analysis framework,numerical calculation and link construction.Then,the feasibility of interference mitigation technologies based on space,frequency domain isolation,power control,and interference alignment mitigation in the NGSO mega-constellation CFI scenario are further sorted out.Finally,we present promising directions for future research in CFI analysis and CFI avoidance.
基金jointly supported by the HongKong,Macao and Taiwan Science & Technology Cooperation Program of China(Grant no.2015DFT10170)the Beijing Higher Education Young Elite Teacher Project
文摘Co-frequency and co-time full duplex(CCFD) is a promising technique for improving spectral efficiency in next generation wireless communication systems. However, for the applications of CCFD in a cellular network, severe co-channel interference is an essential problem. Specifically, there are two significant interferences, i.e., inter-terminal interference(ITI) and inter-cell interference(ICI), which lead to an obvious performance degradation. In this paper, two techniques are proposed for suppressing the ITI and ICI in a CCFD cellular system, respectively. The first technique is obtained by modeling the three-node CCFD system as the Z-channel. After deriving the sum-capacity of the Z-channel, a sum-capacity-achieving scheme based on successive interference cancellation(SIC) is proposed. The second technique is designed by combining the fractional frequency reuse scheme with CCFD. The performance gains of the proposed two techniques in terms of signalto-interference plus noise ratio(SINR) and sumcapacity are analyzed. Simulation results show that the proposed scheme can achieve significant interference suppression performance and higher system capacity, especially for cell edge users.
基金supported by the National Natural Science Foundation of China (Grant No. 62022019)
文摘An asynchronous transmission scenario for non-orthogonal multiple access(NOMA)user signals with arbitrary phase offset is investigated in this paper.To improve the system performance in the user power-balanced conditions,we adopt a synthetic detection method at the receiver,i.e.,the jointly optimal maximal likelihood detection aided triangular successive interference cancellation(JO ML-TSIC)method.Analytical bit error rate(BER)solutions are obtained for a two-user case with the optimal,intentional onehalf symbol period time delay implemented between the user signals.Furthermore,closed-form BER solutions for the case using the triangular successive interference cancellation(TSIC)detection method are also derived for comparisons.Numerical results show that the JO ML-TSIC receiver for the asynchronous system outperforms the TSIC receiver as well as the synchronous successive interference cancellation(SIC)receiver in all the conditions concerned.The results also show that the superiority of the JO ML-TSIC receiver is strengthened when the signals experience flat Rayleigh fading channels compared to the TSIC and the synchronous SIC receivers.
文摘In this paper, Moose scheme is used for frequency offset estimation in OFDMA uplink svstems due to that the signals from different users can be easily distinguished in frequency domain. However, differential multiple access interference （MAI） will deteriorate the frequency offset estimation performances, especially in interleaved OFDMA system. Analysis and simulation results manifest that frequency offset estimation by Moose scheme in block OFDMA system is more robust than that in interleaved OFDMA systern. And an iterative interference cancellation method has been proposed to suppress the differential MAI interference for interleaved OFDMA system, in which Moose scheme is the special case of the number of iteration is equal to one. Simulation results demonstrate that the proposed method can improve the performance with the increase of the number of iterations. In consideration of the performance and complexity, the proposed method with two iterations is selected. And the full comparison results of the proposed iterative method with two iterations and that with one iteration （conventional Moose scheme） are given in the paper, which sufficiently demonstrate that the performance gain can be obtained by the interference cancellation operation in interleaved OFDMA system.
基金Supported by the National Natural Science Foundation of China (Grant Nos. 60832007, 60901018, 60902027)the National High-Tech Research & Development Program of China (Grant No. 2009AA01Z236)
文摘The V-BLAST system with asynchronous transmission mode first proposed by Shao can achieve full diversity only by using a simple linear detection scheme under zero forcing （ZF） criterion; therefore it gives a reasonable tradeoff between complexity and performance. In this paper, we propose two types of successive interference cancellation （SIC） detection schemes for the asynchronous V-BLAST system, one is characterized by applying Mr successive interference cancellators before a maximal ratio combiner （where Mr is the number of receive antennas）, and the other has a maximal ratio combiner before a successive interference cancellator. Since Type Ⅰ consumes more energy of the previously detected signals to recover a signal, Type Ⅱ can offer a better performance and simulations demonstrate its validity.
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。
