To address the problems of network congestion and spectrum resources shortage in multi-user large-scale scenarios,this paper proposes a twice random access OFDMA-NOMA-RA protocol combining the advantages of orthogonal...To address the problems of network congestion and spectrum resources shortage in multi-user large-scale scenarios,this paper proposes a twice random access OFDMA-NOMA-RA protocol combining the advantages of orthogonal frequency division multiple access(OFDMA)and non-orthogonal multiple access(NOMA).The idea of this protocol is that OFMDA is used to divide the entire frequency field into multiple orthogonal resource units(RUs),and NOMA is used on each RU to enable more users to access the channel and improve spectrum efficiency.Based on the protocol designed in this paper,in the case of imperfect successive interference cancellation(SIC),the probability of successful competition subchannels and the outage probability are derived for two scenarios:Users occupy the subchannel individually and users share the subchannel.Moreover,when two users share the channel,the decoding order of the users and the corresponding probabilities are considered.Then,the system throughput is obtained.To achieve better outage performance in the system,the optimal power allocation algorithm is proposed in this paper,which enables the optimal power allocation strategy to be obtained.Numerical results show that the larger the imperfect SIC coefficient,the worse the outage performance of weak users.Compared with pure OFDMA and NOMA,OFDMA-NOMA-RA always maintains an advantage when the imperfect SIC coefficient is less than a specific value.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
A novel iterative receiver for multiple input multiple output (MIMO) systems was introduced. Its basis concept is that the reliability of extrinsic information will be strengthened with continuous iterations. Extrinsi...A novel iterative receiver for multiple input multiple output (MIMO) systems was introduced. Its basis concept is that the reliability of extrinsic information will be strengthened with continuous iterations. Extrinsic information of present iteration is added with prior information of last iteration to obtain performance gain. The simulation results show that the improved iterative receiver can approach the 5th iteration performance of conventional soft interference cancellation (SIC)-minimum mean square error (MMSE) iterative receiver after the 2nd iteration with less computational complexity. Compared with conventional iterative receiver, the improved iterative receiver has 1dB performance gain at bit error rate (BER) of 10~ -5 , with four transmit antennas and four receive antennas system.展开更多
带内全双工水声通信(In-Band Full Duplex Underwater Acoustic Communication,IBFD-UWAC)因其频谱利用率可达传统半双工模式的两倍,已成为水声通信领域的研究热点之一。由于本地发射强功率自干扰信号会导致通信系统误码率性能无法达到...带内全双工水声通信(In-Band Full Duplex Underwater Acoustic Communication,IBFD-UWAC)因其频谱利用率可达传统半双工模式的两倍,已成为水声通信领域的研究热点之一。由于本地发射强功率自干扰信号会导致通信系统误码率性能无法达到正常需求,因此自干扰抵消(Self-interference Cancellation,SIC)技术成为IBFD-UWAC中的核心问题。针对经过模拟SIC或空间自干扰抑制后的残余干扰信号问题,文章利用硬件在环(Hardware In-Loop,HIL)仿真,基于Simulink^(■)Desktop Real-time平台,实现了实时SIC,并利用瞬时状态误差判断期望信号到达情况,提出一种基于期望信号到达阈值的改进Sigmoid函数可变步长最小均方(Improved Sigmoid function based Variable Step Size,LMS,ISVS-LMS)算法,该算法大大降低了期望信号对SIC过程带来的影响。分析、仿真及实验表明:该方法可实现实时带内全双工水声通信的自干扰抵消,且算法的收敛速度以及稳态效果均有显著提升。展开更多
Intelligent reflecting surface(IRS)has been widely regarded as a promising technology for configuring wireless propagation environments.In this paper,we utilize IRS to assist transmission of a secondary user(SU)in a c...Intelligent reflecting surface(IRS)has been widely regarded as a promising technology for configuring wireless propagation environments.In this paper,we utilize IRS to assist transmission of a secondary user(SU)in a cognitive radio-inspired rate-splitting multiple access(CR-RSMA)system in which a primary user's(PU's)quality of service(QoS)requirements must be guaranteed.Without introducing intolerable interference to deteriorate the PU's outage performance,the SU conducts rate-splitting to transmit its signal to the base-station through the direct link and IRS reflecting channels.For the IRS-assisted CR-RSMA(IRS-CR-RSMA)scheme,we derive the optimal transmit power allocation,target rate allocation,and successive interference cancellation decoding order to enhance the outage performance of the SU.The closed-form expression for the SU's outage probability achieved by the IRS-CR-RSMA scheme is derived.Various simulation results are presented to clarify the enhanced outage performance achieved by the proposed IRS-CR-RSMA scheme over the CR-RSMA scheme.展开更多
凭借能够提升频谱利用率的优势,带内全双工(In-Band Full Duplex,IBFD)技术有望成为现代无线通信系统的潜在方案。然而,在应用过程中却面临自干扰抵消(Self-Interference Cancellation,SIC)的巨大挑战。SIC可以从空域、模拟域和数字域3...凭借能够提升频谱利用率的优势,带内全双工(In-Band Full Duplex,IBFD)技术有望成为现代无线通信系统的潜在方案。然而,在应用过程中却面临自干扰抵消(Self-Interference Cancellation,SIC)的巨大挑战。SIC可以从空域、模拟域和数字域3个方面来单独或组合实现。该文重点研究了IBFD数字SIC。针对传统数字SIC性能受到收发链路器件非理想因素限制的问题,该文建立了一种射频辅助链路的IBFD系统,利用有用信号和自干扰信号的有界性,设计了一种基于有界成分分析的数字SIC方法。在视距(Line Of Sight,LOS)和非视距(Non-Line Of Sight,NLOS)两种信道场景下,利用仿真和实测数据进行了验证分析。结果表明,相比较于最小二乘方法和独立成分分析方法,所提有界成分分析方法改善了SIC效果,并提高了系统误码率性能。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
基金funded in part by the National Natural Science Foundation of China under Grant 61663024in part by the Hongliu First Class Discipline Development Project of Lanzhou University of Technology(25-225305).
文摘To address the problems of network congestion and spectrum resources shortage in multi-user large-scale scenarios,this paper proposes a twice random access OFDMA-NOMA-RA protocol combining the advantages of orthogonal frequency division multiple access(OFDMA)and non-orthogonal multiple access(NOMA).The idea of this protocol is that OFMDA is used to divide the entire frequency field into multiple orthogonal resource units(RUs),and NOMA is used on each RU to enable more users to access the channel and improve spectrum efficiency.Based on the protocol designed in this paper,in the case of imperfect successive interference cancellation(SIC),the probability of successful competition subchannels and the outage probability are derived for two scenarios:Users occupy the subchannel individually and users share the subchannel.Moreover,when two users share the channel,the decoding order of the users and the corresponding probabilities are considered.Then,the system throughput is obtained.To achieve better outage performance in the system,the optimal power allocation algorithm is proposed in this paper,which enables the optimal power allocation strategy to be obtained.Numerical results show that the larger the imperfect SIC coefficient,the worse the outage performance of weak users.Compared with pure OFDMA and NOMA,OFDMA-NOMA-RA always maintains an advantage when the imperfect SIC coefficient is less than a specific value.
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The Science and Technology Committee of Shanghai Municipality ( No 06DZ15013,No03DZ15010)Shanghai Research Centerfor Wireless Communications
文摘A novel iterative receiver for multiple input multiple output (MIMO) systems was introduced. Its basis concept is that the reliability of extrinsic information will be strengthened with continuous iterations. Extrinsic information of present iteration is added with prior information of last iteration to obtain performance gain. The simulation results show that the improved iterative receiver can approach the 5th iteration performance of conventional soft interference cancellation (SIC)-minimum mean square error (MMSE) iterative receiver after the 2nd iteration with less computational complexity. Compared with conventional iterative receiver, the improved iterative receiver has 1dB performance gain at bit error rate (BER) of 10~ -5 , with four transmit antennas and four receive antennas system.
文摘带内全双工水声通信(In-Band Full Duplex Underwater Acoustic Communication,IBFD-UWAC)因其频谱利用率可达传统半双工模式的两倍,已成为水声通信领域的研究热点之一。由于本地发射强功率自干扰信号会导致通信系统误码率性能无法达到正常需求,因此自干扰抵消(Self-interference Cancellation,SIC)技术成为IBFD-UWAC中的核心问题。针对经过模拟SIC或空间自干扰抑制后的残余干扰信号问题,文章利用硬件在环(Hardware In-Loop,HIL)仿真,基于Simulink^(■)Desktop Real-time平台,实现了实时SIC,并利用瞬时状态误差判断期望信号到达情况,提出一种基于期望信号到达阈值的改进Sigmoid函数可变步长最小均方(Improved Sigmoid function based Variable Step Size,LMS,ISVS-LMS)算法,该算法大大降低了期望信号对SIC过程带来的影响。分析、仿真及实验表明:该方法可实现实时带内全双工水声通信的自干扰抵消,且算法的收敛速度以及稳态效果均有显著提升。
基金supported in part by National Natural Science Foundation of China under Grant 62071202in part by Shandong Provincial Natural Science Foundation under Grants ZR2020MF009,ZR2020MF075in part by Shandong Key Laboratory of Intelligent Buildings Technology undert Grant SDIBT202004.
文摘Intelligent reflecting surface(IRS)has been widely regarded as a promising technology for configuring wireless propagation environments.In this paper,we utilize IRS to assist transmission of a secondary user(SU)in a cognitive radio-inspired rate-splitting multiple access(CR-RSMA)system in which a primary user's(PU's)quality of service(QoS)requirements must be guaranteed.Without introducing intolerable interference to deteriorate the PU's outage performance,the SU conducts rate-splitting to transmit its signal to the base-station through the direct link and IRS reflecting channels.For the IRS-assisted CR-RSMA(IRS-CR-RSMA)scheme,we derive the optimal transmit power allocation,target rate allocation,and successive interference cancellation decoding order to enhance the outage performance of the SU.The closed-form expression for the SU's outage probability achieved by the IRS-CR-RSMA scheme is derived.Various simulation results are presented to clarify the enhanced outage performance achieved by the proposed IRS-CR-RSMA scheme over the CR-RSMA scheme.
文摘凭借能够提升频谱利用率的优势,带内全双工(In-Band Full Duplex,IBFD)技术有望成为现代无线通信系统的潜在方案。然而,在应用过程中却面临自干扰抵消(Self-Interference Cancellation,SIC)的巨大挑战。SIC可以从空域、模拟域和数字域3个方面来单独或组合实现。该文重点研究了IBFD数字SIC。针对传统数字SIC性能受到收发链路器件非理想因素限制的问题,该文建立了一种射频辅助链路的IBFD系统,利用有用信号和自干扰信号的有界性,设计了一种基于有界成分分析的数字SIC方法。在视距(Line Of Sight,LOS)和非视距(Non-Line Of Sight,NLOS)两种信道场景下,利用仿真和实测数据进行了验证分析。结果表明,相比较于最小二乘方法和独立成分分析方法,所提有界成分分析方法改善了SIC效果,并提高了系统误码率性能。
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.
