Non-orthogonal multiple access(NOMA)is viewed as a key technique to improve the spectrum efficiency and solve the issue of massive connectivity.However,for power domain NOMA,the required overall transmit power should ...Non-orthogonal multiple access(NOMA)is viewed as a key technique to improve the spectrum efficiency and solve the issue of massive connectivity.However,for power domain NOMA,the required overall transmit power should be increased rapidly with the increasing number of users in order to ensure that the signal-to-interference-plus-noise ratio reaches a predefined threshold.In addition,since the successive interference cancellation(SIC)is adopted,the error propagation would become more serious as the order of SIC increases.Aiming at minimizing the total transmit power and satisfying each user’s service requirement,this paper proposes a novel framework with group-based SIC for the deep integration between power domain NOMA and multi-antenna technology.Based on the proposed framework,a joint optimization of power control and equalizer design is investigated to minimize transmit power consumption for uplink multi-antenna NOMA system with error propagations.Based on the relationship between the equalizer and the transmit power coefficients,the original problem is transformed to a transmit power optimization problem,which is further addressed by a parallel iteration algorithm.It is shown by simulations that,in terms of the total power consumption,the proposed scheme outperforms the conventional OMA and the existing cluster-based NOMA schemes.展开更多
Recently cellular networks have been densely and heterogeneously deployed indoors and outdoors to expand the network capacity,and thus the in-building propagation loss and the transmit power diversity of access points...Recently cellular networks have been densely and heterogeneously deployed indoors and outdoors to expand the network capacity,and thus the in-building propagation loss and the transmit power diversity of access points will exacerbate link heterogeneity and result in partial unidirectional strong interference.To make full use of the strong interference feature,we propose the successive interference cancellation and alignment(SICA)scheme in the K-user interference channel with partial unidirectional strong interference.SICA is designed to transmit two kinds of data streams simultaneously,the alignment streams and superposition streams.The alignment streams will follow the interference alignment criterion to maintain the optimal degrees of freedom(DoF)performance;the superposition streams are handled via successive interference cancellation at all the strongly interfered receivers to improve the overall achievable rate.The joint transceiver designs for SICA is modeled as a weighted sum rate(WSR)maximization problem,and then can be alternately solved for a local optimum according to the optimality equivalence between WSR and its corresponding weighted mean square error(WMMSE)problem.Simulation results have confirmed the sum rate improvement and DoF optimality of the proposed SICA scheme.展开更多
With a cross-layer design approach, a novel random access protocol is proposed in this paper, which is based on conventional slotted ALOHA (S-ALOHA) using successive interference cancellation (SIC) technique to se...With a cross-layer design approach, a novel random access protocol is proposed in this paper, which is based on conventional slotted ALOHA (S-ALOHA) using successive interference cancellation (SIC) technique to separate collided packets and cooperative transmission to exploit the physical layer advantages. And a general theoretic analysis model is presented to obtain its throughput, which is also suitable for analyzing the performance of other protocols (such as S-ALOHA and S-ALOHA with cooperative transmission (C-ALOHA)) and is shown to be right and effective. Numerical results demonstrate that the proposed protocol can improve the maximal throughput by 190% and 132% over a Rayleigh fading channel, respectively, as compared with S-ALOHA and C-ALOHA. And the results show that our protocol can provide an effective random access method with high throughput for wireless transmission.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
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
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
In this paper, we investigate the downlink performance of cell-free massive multi-input multi-output non-orthogonal multiple access(CF-m MIMO-NOMA) system with conjugate beamforming precoder and compare against the or...In this paper, we investigate the downlink performance of cell-free massive multi-input multi-output non-orthogonal multiple access(CF-m MIMO-NOMA) system with conjugate beamforming precoder and compare against the orthogonal multiple access(OMA) counterpart. A novel achievable closed-form spectral efficiency(SE) expression is derived, which characterizes the effects of the channel estimation error, pilot contamination, imperfect successive interference cancellation(SIC) operation, and power optimization technique. Then, motivated by the closedform result, a sum-SE maximization algorithm with the sequential convex approximation(SCA) is proposed, subject to each AP power constraint and SIC power constraint. Numerical experiments indicate that the proposed sum-SE maximization algorithms have a fast converge rate, within about five iterations. In addition, compared with the full power control(FPC) scheme, our algorithms can significantly improve the achievable sum-SE. Moreover, NOMA outperforms OMA in many respects in the presence of the proposed algorithms.展开更多
Non-orthogonal multiple access (NOMA) has been recognized as a promising multiple access technique for the next generation cel-lular communication networks. In this paper, we first discuss a simple NOMA model with t...Non-orthogonal multiple access (NOMA) has been recognized as a promising multiple access technique for the next generation cel-lular communication networks. In this paper, we first discuss a simple NOMA model with two users served by a single-carrier si-multaneously to illustrate its basic principles. Then, a more general model with multicarrier serving an arbitrary number of users on each subcarrier is also discussed. An overview of existing works on performance analysis, resource allocation, and multiple-in-put multiple-output NOMA are summarized and discussed. Furthermore, we discuss the key features of NOMA and its potential re-search challenges.展开更多
Aiming for ultra-reliable low-latency wireless communications required in industrial internet of things(IIoT)applications,this paper studies a simple cognitive radio non-orthogonal multiple access(CR-NOMA)downlink sys...Aiming for ultra-reliable low-latency wireless communications required in industrial internet of things(IIoT)applications,this paper studies a simple cognitive radio non-orthogonal multiple access(CR-NOMA)downlink system.This system consists of two secondary users(SUs)dynamically interfered by the primary user(PU),and its performance is characterized by the outage probability of the SU communications.This outage probability is calculated under two conditions where,a)the transmission of PU starts after the channel state information(CSI)is acquired,so the base station(BS)is oblivious of the interference,and b)when the BS is aware of the PU interference,and the NOMA transmission is adapted to the more comprehensive knowledge of the signal to interference plus noise ratio(SINR).These results are verified by simulations,and their good agreement suggests our calculations can be used to reduce the complexity of future analysis.We find the outage probability is reduced when the SUs move further away from the primary transmitter or when the signal from PU is less powerful,and the BS always has better performance when it is aware of the interference.The findings thus emphasize the importance of monitoring the channel quality and realtime feedback to optimize the performance of CR-NOMA system.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
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 design of random media access control(MAC) protocol has been attracting great attention for satellite communication networks,where the propagation delay is long and the traffic load is varying.Advanced coded rando...The design of random media access control(MAC) protocol has been attracting great attention for satellite communication networks,where the propagation delay is long and the traffic load is varying.Advanced coded random access schemes tend to provide resource allocation strategies for massive uncoordinated devices,where multiple packet replicas from each user are transmitted in random slots of the frame and successive interference cancellation(SIC) iterations are tracked to recover collided packets at the receiver.It is assumed that each active user just has a single information packet to be transmitted.In this paper,an MAC layer random access scheme named Multi-Packets Transmitted Irregular Repetition Slotted Aloha(M-IRSA) is proposed.Different from the existing advanced random access schemes,the M-IRSA scheme supports various number of packet transmission per user by using pre-coding procedure.Joint decoding combined with SIC iterations and local decoding is analyzed.The simulation results show that the proposed scheme is more efficient compared with the IRSA scheme without packet loss rate(PLR) loss.展开更多
It has been shown that transmit correlation causes a signal-to-noise ratio (SNR) loss in the zero forcing (ZF) receiver for V-BLAST (Vertical Bell LAbs LAyered Space-Time) system. In this paper, we investigate t...It has been shown that transmit correlation causes a signal-to-noise ratio (SNR) loss in the zero forcing (ZF) receiver for V-BLAST (Vertical Bell LAbs LAyered Space-Time) system. In this paper, we investigate the transmit correlation effect on the ZF receiver with successive interference cancellation (SIC). We show that such an unfavorable condition leads to twofold effects on the performance degradation. In addition to the immediate SNR loss, the transmit correlation can increase the propagation factor to spread decision error significantly. These two effects are evaluated analytically. We derive the probability density function (pdf) of the effective SNR at each decoded stream, and hence accurately quantify the SNR loss. We also calculate the decision error propagation factor in terms of its second moment. In particular, we show that transmit correlation can cause a stable component of error propagation which does not decline during the SIC procedure. Finally, we conduct the simulation to verify the analytical results.展开更多
Due to the potential capacity-boosting for wireless communications,radio vortex wireless communication(RowComm)over orthogonal states/modes of orbital angular momentum(OAM)has been paid much attention to in recent yea...Due to the potential capacity-boosting for wireless communications,radio vortex wireless communication(RowComm)over orthogonal states/modes of orbital angular momentum(OAM)has been paid much attention to in recent years.A uniform circular array(UCA),as an efficient and convenient antenna structure,can transmit/receive multiple OAM beams with different OAM-modes simultaneously when the transmitter and receiver are aligned.However,for high-order OAMmodes,the OAM beams are divergent accompanied by severe attenuation.Thus,it is difficult to directly use high-order OAM-modes to achieve high capacity for RowComms.To obtain high capacity potentially offered by OAM-modes,in this paper we transform the singular UCA into the concentric UCAs,where high capacity can be achieved using multiple parallel low-order OAM-modes instead of all high-order OAM-modes,to increase the capacity of transmitter-receiver aligned Row-Comms.In particular,we study two cases:1).concentric UCAs based RowComms without co-mode interference;2).concentric UCAs based RowComms with co-mode interference.We propose a co-mode-interference-free and a co-mode-interference-contained mode-decomposition schemes to recover transmitted signals for these two cases,respectively.Additionally,we develop optimal power allocation schemes to maximize the capacity for these two cases.Numerical simulations are presented to validate and evaluate that our developed concentric UCAs based low-order RowComms can significantly increase the capacity as compared with that of singular UCA based RowComms.展开更多
In fifth-generation wireless communication networks, Non-Orthogonal Multiple Access(NOMA) has attracted much attention in both academic and industrial fields because of its higher spectral efficiency in comparison w...In fifth-generation wireless communication networks, Non-Orthogonal Multiple Access(NOMA) has attracted much attention in both academic and industrial fields because of its higher spectral efficiency in comparison with orthogonal multiple access. Recently, numerous uplink NOMA techniques have been proposed,some of which are based on Successive Interference Cancellation(SIC) and others on Joint Decoding(JD, or simultaneous decoding). In this study, we analyze the outage capacities of SIC and JD in the case of single-block transmission over a two-user Gaussian multiple-access channel with partial channel state information at transmitter from the perspective of information theory. Results of the analysis and numerals show that compared to SIC, JD can achieve a sum-rate gain of up to 10% or sum-power gain of 0.8 dB.展开更多
Non-orthogonal time-frequency division multiplexing (NTFDM) transmission scheme has been proposed to further improve the bandwidth efficiency and overcome the drawbacks of the conventional orthogonal frequency divis...Non-orthogonal time-frequency division multiplexing (NTFDM) transmission scheme has been proposed to further improve the bandwidth efficiency and overcome the drawbacks of the conventional orthogonal frequency division multiplexing (OFDM) method. Based on such approach, the fast signal detection algorithm, semidefinite programming (SDP) detection, has been studied. As the coefficient matrix tends to be ill conditioned, the modified SDP algorithm combined with successive interference cancellation (SIC) has been developed. The improved algorithm is a good tradeoff between performance and detection complexity. Simulation results show that the proposed algorithm can achieve better performance than cutting plane aided SDP method.展开更多
With the advances of the 4th generation (4G) mobile communications targeting multi-user QoS-guaranteed multimedia services, multiple input multiple output (MIMO) combined with multi-level quadrature amplitude modu...With the advances of the 4th generation (4G) mobile communications targeting multi-user QoS-guaranteed multimedia services, multiple input multiple output (MIMO) combined with multi-level quadrature amplitude modulation (M-QAM) technique gains great popularity for its capability of supporting high data rate. In this article, the statistical distribution of signal to noise plus interference ratio (SINR) in each recursive step of optimal ordered zero-forcing perfect successive interference cancellation (ZF-OOPSIC) detection is deduced based on order statistics theory. The symbol error rate (SER) of M-QAM MIMO system with ZF-OOPSIC detector is analyzed under fiat Rayleigh fading channel. This precise analytical SER result could be taken as the lower bound of various zero-forcing ordered successive interference cancellation (ZF-OSIC) receivers. Combining the analytical SER expression for linear zero-forcing (ZF) receiver as upper bound, the rough range of SER for various ZF-OSIC detectors could be obtained. Monte Carlo (MC) simulations validate the analytical results and prove the conclusions.展开更多
基金supported in part by the National Natural Science Foundation of China under Grant 62171235 and Grant 62171237in part by the Qinglan Project of Jiangsu Provincein part by the Open Research Foundation of National Mobile Communications Research Laboratory of Southeast University under Grant 2023D01.
文摘Non-orthogonal multiple access(NOMA)is viewed as a key technique to improve the spectrum efficiency and solve the issue of massive connectivity.However,for power domain NOMA,the required overall transmit power should be increased rapidly with the increasing number of users in order to ensure that the signal-to-interference-plus-noise ratio reaches a predefined threshold.In addition,since the successive interference cancellation(SIC)is adopted,the error propagation would become more serious as the order of SIC increases.Aiming at minimizing the total transmit power and satisfying each user’s service requirement,this paper proposes a novel framework with group-based SIC for the deep integration between power domain NOMA and multi-antenna technology.Based on the proposed framework,a joint optimization of power control and equalizer design is investigated to minimize transmit power consumption for uplink multi-antenna NOMA system with error propagations.Based on the relationship between the equalizer and the transmit power coefficients,the original problem is transformed to a transmit power optimization problem,which is further addressed by a parallel iteration algorithm.It is shown by simulations that,in terms of the total power consumption,the proposed scheme outperforms the conventional OMA and the existing cluster-based NOMA schemes.
基金supported by the National Natural Science Foundation of China(62101415)the Guangdong Basic and Applied Basic Research Foundation(2020A1515110757).
文摘Recently cellular networks have been densely and heterogeneously deployed indoors and outdoors to expand the network capacity,and thus the in-building propagation loss and the transmit power diversity of access points will exacerbate link heterogeneity and result in partial unidirectional strong interference.To make full use of the strong interference feature,we propose the successive interference cancellation and alignment(SICA)scheme in the K-user interference channel with partial unidirectional strong interference.SICA is designed to transmit two kinds of data streams simultaneously,the alignment streams and superposition streams.The alignment streams will follow the interference alignment criterion to maintain the optimal degrees of freedom(DoF)performance;the superposition streams are handled via successive interference cancellation at all the strongly interfered receivers to improve the overall achievable rate.The joint transceiver designs for SICA is modeled as a weighted sum rate(WSR)maximization problem,and then can be alternately solved for a local optimum according to the optimality equivalence between WSR and its corresponding weighted mean square error(WMMSE)problem.Simulation results have confirmed the sum rate improvement and DoF optimality of the proposed SICA scheme.
基金Supported by the National Natural Science Foundation of China (Grant No. 60672079)the open research fund of National Mobile Communications Research Laboratory, Southeast University (Grant No. N200814)the Project of Natural Science Foundation of Jiangsu Province(Grant No. BK2007002)
文摘With a cross-layer design approach, a novel random access protocol is proposed in this paper, which is based on conventional slotted ALOHA (S-ALOHA) using successive interference cancellation (SIC) technique to separate collided packets and cooperative transmission to exploit the physical layer advantages. And a general theoretic analysis model is presented to obtain its throughput, which is also suitable for analyzing the performance of other protocols (such as S-ALOHA and S-ALOHA with cooperative transmission (C-ALOHA)) and is shown to be right and effective. Numerical results demonstrate that the proposed protocol can improve the maximal throughput by 190% and 132% over a Rayleigh fading channel, respectively, as compared with S-ALOHA and C-ALOHA. And the results show that our protocol can provide an effective random access method with high throughput for wireless transmission.
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.
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.
基金supported in part by the National Key Research and Development Program of China under Grant 2018YFC1314903the National Natural Science Foundation of China under Grants 61861039,61372124,and 61427801+1 种基金the Science and Technology Project Foundation of Gansu Province under Grant 18YF1GA060the Postgraduate Research&Practice Innovation Program of Jiangsu Province under Grant SJKY19_0740 and KYCX20_0709。
文摘In this paper, we investigate the downlink performance of cell-free massive multi-input multi-output non-orthogonal multiple access(CF-m MIMO-NOMA) system with conjugate beamforming precoder and compare against the orthogonal multiple access(OMA) counterpart. A novel achievable closed-form spectral efficiency(SE) expression is derived, which characterizes the effects of the channel estimation error, pilot contamination, imperfect successive interference cancellation(SIC) operation, and power optimization technique. Then, motivated by the closedform result, a sum-SE maximization algorithm with the sequential convex approximation(SCA) is proposed, subject to each AP power constraint and SIC power constraint. Numerical experiments indicate that the proposed sum-SE maximization algorithms have a fast converge rate, within about five iterations. In addition, compared with the full power control(FPC) scheme, our algorithms can significantly improve the achievable sum-SE. Moreover, NOMA outperforms OMA in many respects in the presence of the proposed algorithms.
文摘Non-orthogonal multiple access (NOMA) has been recognized as a promising multiple access technique for the next generation cel-lular communication networks. In this paper, we first discuss a simple NOMA model with two users served by a single-carrier si-multaneously to illustrate its basic principles. Then, a more general model with multicarrier serving an arbitrary number of users on each subcarrier is also discussed. An overview of existing works on performance analysis, resource allocation, and multiple-in-put multiple-output NOMA are summarized and discussed. Furthermore, we discuss the key features of NOMA and its potential re-search challenges.
基金This work is funded by National Major Project(No.2017ZX03001021-005)National Key R&D Program of China(No.2017YFB1001600)+1 种基金Standard Development and Test bed Construction for Smart Factory Virtual Mapping Model and Digitized Delivery(No.MIIT 2019-00899-3-1)2018 Sugon Intelligent Factory on Advanced Computing Devices(No.MIIT 2018-265-137).
文摘Aiming for ultra-reliable low-latency wireless communications required in industrial internet of things(IIoT)applications,this paper studies a simple cognitive radio non-orthogonal multiple access(CR-NOMA)downlink system.This system consists of two secondary users(SUs)dynamically interfered by the primary user(PU),and its performance is characterized by the outage probability of the SU communications.This outage probability is calculated under two conditions where,a)the transmission of PU starts after the channel state information(CSI)is acquired,so the base station(BS)is oblivious of the interference,and b)when the BS is aware of the PU interference,and the NOMA transmission is adapted to the more comprehensive knowledge of the signal to interference plus noise ratio(SINR).These results are verified by simulations,and their good agreement suggests our calculations can be used to reduce the complexity of future analysis.We find the outage probability is reduced when the SUs move further away from the primary transmitter or when the signal from PU is less powerful,and the BS always has better performance when it is aware of the interference.The findings thus emphasize the importance of monitoring the channel quality and realtime feedback to optimize the performance of CR-NOMA system.
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.
文摘The design of random media access control(MAC) protocol has been attracting great attention for satellite communication networks,where the propagation delay is long and the traffic load is varying.Advanced coded random access schemes tend to provide resource allocation strategies for massive uncoordinated devices,where multiple packet replicas from each user are transmitted in random slots of the frame and successive interference cancellation(SIC) iterations are tracked to recover collided packets at the receiver.It is assumed that each active user just has a single information packet to be transmitted.In this paper,an MAC layer random access scheme named Multi-Packets Transmitted Irregular Repetition Slotted Aloha(M-IRSA) is proposed.Different from the existing advanced random access schemes,the M-IRSA scheme supports various number of packet transmission per user by using pre-coding procedure.Joint decoding combined with SIC iterations and local decoding is analyzed.The simulation results show that the proposed scheme is more efficient compared with the IRSA scheme without packet loss rate(PLR) loss.
基金Supported in part by Shanghai Research Center for Wireless Communications (SHRCWC) cooperative projectin part by the Ministry of Science and Technology of China (Grant Nos. 2008DFA12190, 2008DFA12090)
文摘It has been shown that transmit correlation causes a signal-to-noise ratio (SNR) loss in the zero forcing (ZF) receiver for V-BLAST (Vertical Bell LAbs LAyered Space-Time) system. In this paper, we investigate the transmit correlation effect on the ZF receiver with successive interference cancellation (SIC). We show that such an unfavorable condition leads to twofold effects on the performance degradation. In addition to the immediate SNR loss, the transmit correlation can increase the propagation factor to spread decision error significantly. These two effects are evaluated analytically. We derive the probability density function (pdf) of the effective SNR at each decoded stream, and hence accurately quantify the SNR loss. We also calculate the decision error propagation factor in terms of its second moment. In particular, we show that transmit correlation can cause a stable component of error propagation which does not decline during the SIC procedure. Finally, we conduct the simulation to verify the analytical results.
文摘Due to the potential capacity-boosting for wireless communications,radio vortex wireless communication(RowComm)over orthogonal states/modes of orbital angular momentum(OAM)has been paid much attention to in recent years.A uniform circular array(UCA),as an efficient and convenient antenna structure,can transmit/receive multiple OAM beams with different OAM-modes simultaneously when the transmitter and receiver are aligned.However,for high-order OAMmodes,the OAM beams are divergent accompanied by severe attenuation.Thus,it is difficult to directly use high-order OAM-modes to achieve high capacity for RowComms.To obtain high capacity potentially offered by OAM-modes,in this paper we transform the singular UCA into the concentric UCAs,where high capacity can be achieved using multiple parallel low-order OAM-modes instead of all high-order OAM-modes,to increase the capacity of transmitter-receiver aligned Row-Comms.In particular,we study two cases:1).concentric UCAs based RowComms without co-mode interference;2).concentric UCAs based RowComms with co-mode interference.We propose a co-mode-interference-free and a co-mode-interference-contained mode-decomposition schemes to recover transmitted signals for these two cases,respectively.Additionally,we develop optimal power allocation schemes to maximize the capacity for these two cases.Numerical simulations are presented to validate and evaluate that our developed concentric UCAs based low-order RowComms can significantly increase the capacity as compared with that of singular UCA based RowComms.
基金supported by the National Natural Science Foundation of China (No. 61471219)the R&D Project of Science and Technology Innovation Commission of Shenzhen, China (No. JCYJ20140419122040614)
文摘In fifth-generation wireless communication networks, Non-Orthogonal Multiple Access(NOMA) has attracted much attention in both academic and industrial fields because of its higher spectral efficiency in comparison with orthogonal multiple access. Recently, numerous uplink NOMA techniques have been proposed,some of which are based on Successive Interference Cancellation(SIC) and others on Joint Decoding(JD, or simultaneous decoding). In this study, we analyze the outage capacities of SIC and JD in the case of single-block transmission over a two-user Gaussian multiple-access channel with partial channel state information at transmitter from the perspective of information theory. Results of the analysis and numerals show that compared to SIC, JD can achieve a sum-rate gain of up to 10% or sum-power gain of 0.8 dB.
基金the National Natural Science Foundation of China (90604035)
文摘Non-orthogonal time-frequency division multiplexing (NTFDM) transmission scheme has been proposed to further improve the bandwidth efficiency and overcome the drawbacks of the conventional orthogonal frequency division multiplexing (OFDM) method. Based on such approach, the fast signal detection algorithm, semidefinite programming (SDP) detection, has been studied. As the coefficient matrix tends to be ill conditioned, the modified SDP algorithm combined with successive interference cancellation (SIC) has been developed. The improved algorithm is a good tradeoff between performance and detection complexity. Simulation results show that the proposed algorithm can achieve better performance than cutting plane aided SDP method.
基金supported by the Specialized Major Science and Technology Project of China (2008ZX03003-004,2009ZX03003-009)the National Natural Science Foundation of China (60872048)+1 种基金Sino-Sweden Cooperative Project (2008DFA12110)Sino-Australia Collaborations Project
文摘With the advances of the 4th generation (4G) mobile communications targeting multi-user QoS-guaranteed multimedia services, multiple input multiple output (MIMO) combined with multi-level quadrature amplitude modulation (M-QAM) technique gains great popularity for its capability of supporting high data rate. In this article, the statistical distribution of signal to noise plus interference ratio (SINR) in each recursive step of optimal ordered zero-forcing perfect successive interference cancellation (ZF-OOPSIC) detection is deduced based on order statistics theory. The symbol error rate (SER) of M-QAM MIMO system with ZF-OOPSIC detector is analyzed under fiat Rayleigh fading channel. This precise analytical SER result could be taken as the lower bound of various zero-forcing ordered successive interference cancellation (ZF-OSIC) receivers. Combining the analytical SER expression for linear zero-forcing (ZF) receiver as upper bound, the rough range of SER for various ZF-OSIC detectors could be obtained. Monte Carlo (MC) simulations validate the analytical results and prove the conclusions.