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Design Framework of Unsourced Multiple Access for 6G Massive IoT
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作者 Chunlin Yan Siying Lyu +2 位作者 Sen Wang Yuhong Huang Xiaodong Xu 《China Communications》 SCIE CSCD 2024年第1期1-12,共12页
In this paper,ambient IoT is used as a typical use case of massive connections for the sixth generation(6G)mobile communications where we derive the performance requirements to facilitate the evaluation of technical s... In this paper,ambient IoT is used as a typical use case of massive connections for the sixth generation(6G)mobile communications where we derive the performance requirements to facilitate the evaluation of technical solutions.A rather complete design of unsourced multiple access is proposed in which two key parts:a compressed sensing module for active user detection,and a sparse interleaver-division multiple access(SIDMA)module are simulated side by side on a same platform at balanced signal to noise ratio(SNR)operating points.With a proper combination of compressed sensing matrix,a convolutional encoder,receiver algorithms,the simulated performance results appear superior to the state-of-the-art benchmark,yet with relatively less complicated processing. 展开更多
关键词 channel coding compressed sensing massive Internet-of-Things(IoT) sparse interleaverdivision multiple access(SIDma) the sixth generation(6G)mobile communications unsourced multiple access
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A Deep Reinforcement Learning-Based Technique for Optimal Power Allocation in Multiple Access Communications
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作者 Sepehr Soltani Ehsan Ghafourian +2 位作者 Reza Salehi Diego Martín Milad Vahidi 《Intelligent Automation & Soft Computing》 2024年第1期93-108,共16页
Formany years,researchers have explored power allocation(PA)algorithms driven bymodels in wireless networks where multiple-user communications with interference are present.Nowadays,data-driven machine learning method... Formany years,researchers have explored power allocation(PA)algorithms driven bymodels in wireless networks where multiple-user communications with interference are present.Nowadays,data-driven machine learning methods have become quite popular in analyzing wireless communication systems,which among them deep reinforcement learning(DRL)has a significant role in solving optimization issues under certain constraints.To this purpose,in this paper,we investigate the PA problem in a k-user multiple access channels(MAC),where k transmitters(e.g.,mobile users)aim to send an independent message to a common receiver(e.g.,base station)through wireless channels.To this end,we first train the deep Q network(DQN)with a deep Q learning(DQL)algorithm over the simulation environment,utilizing offline learning.Then,the DQN will be used with the real data in the online training method for the PA issue by maximizing the sumrate subjected to the source power.Finally,the simulation results indicate that our proposedDQNmethod provides better performance in terms of the sumrate compared with the available DQL training approaches such as fractional programming(FP)and weighted minimum mean squared error(WMMSE).Additionally,by considering different user densities,we show that our proposed DQN outperforms benchmark algorithms,thereby,a good generalization ability is verified over wireless multi-user communication systems. 展开更多
关键词 Deep reinforcement learning deep Q learning multiple access channel power allocation
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The Extended Hybrid Carrier-Based Multiple Access Technology for High Mobility Scenarios 被引量:1
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作者 Ge Song Xiaojie Fang Xuejun Sha 《China Communications》 SCIE CSCD 2024年第1期53-68,共16页
The hybrid carrier(HC)system rooted in the carrier fusion concept is gradually garnering attention.In this paper,we study the extended hybrid carrier(EHC)multiple access scheme to ensure reliable wireless communicatio... The hybrid carrier(HC)system rooted in the carrier fusion concept is gradually garnering attention.In this paper,we study the extended hybrid carrier(EHC)multiple access scheme to ensure reliable wireless communication.By employing the EHC modulation,a power layered multiplexing framework is realized,which exhibits enhanced interference suppression capability owing to the more uniform energy distribution design.The implementation method and advantage mechanism are explicated respectively for the uplink and downlink,and the performance analysis under varying channel conditions is provided.In addition,considering the connectivity demand,we explore the non-orthogonal multiple access(NOMA)method of the EHC system and develop the EHC sparse code multiple access scheme.The proposed scheme melds the energy spread superiority of EHC with the access capacity of NOMA,facilitating superior support for massive connectivity in high mobility environments.Simulation results have verified the feasibility and advantages of the proposed scheme.Compared with existing HC multiple access schemes,the proposed scheme exhibits robust bit error rate performance and can better guarantee multiple access performance in complex scenarios of nextgeneration communications. 展开更多
关键词 extended hybrid carrier system high mo-Received:Jun.09 2023 Revised:Nov.20 2023 Editor:Yuanwei Liu bility communications multiple access
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Downlink network-coded multiple access with diverse power
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作者 Bohao Cao Zheng Xiang +2 位作者 Peng Ren Qiao Li Baoyi Xu 《Digital Communications and Networks》 SCIE CSCD 2024年第4期956-964,共9页
Normally,in the downlink Network-Coded Multiple Access(NCMA)system,the same power is allocated to different users.However,equal power allocation is unsuitable for some scenarios,such as when user devices have differen... Normally,in the downlink Network-Coded Multiple Access(NCMA)system,the same power is allocated to different users.However,equal power allocation is unsuitable for some scenarios,such as when user devices have different Quality of Service(QoS)requirements.Hence,we study the power allocation in the downlink NCMA system in this paper,and propose a downlink Network-Coded Multiple Access with Diverse Power(NCMA-DP),wherein different amounts of power are allocated to different users.In terms of the Bit Error Rate(BER)of the multi-user decoder,and the number of packets required to correctly decode the message,the performance of the user with more allocated power is greatly improved compared to the Conventional NCMA(NCMA-C).Meanwhile,the performance of the user with less allocated power is still much better than NCMA-C.Furthermore,the overall throughput of NCMA-DP is greatly improved compared to that of NCMA-C.The simulation results demonstrate the remarkable performance of the proposed NCMA-DP. 展开更多
关键词 Network-coded multiple access Physical-layer network coding Multi-user decoder Power allocation Throughput Downlink network
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Max-Min Fair RIS-Aided Rate-Splitting Multiple Access for Multigroup Multicast Communications 被引量:1
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作者 Tiantian Li Haixia Zhang +1 位作者 Shuaishuai Guo Dongfeng Yuan 《China Communications》 SCIE CSCD 2023年第1期184-198,共15页
Rate-splitting multiple access(RSMA)can cope with a wide range of propagation conditions in multigroup multicast communications through rate splitting optimization.To breakthrough the grouprate limited bottleneck,reco... Rate-splitting multiple access(RSMA)can cope with a wide range of propagation conditions in multigroup multicast communications through rate splitting optimization.To breakthrough the grouprate limited bottleneck,reconfigurable intelligent surface(RIS)technique can be introduced to assist wireless communications through enhancing the channel quality.In RIS-aided RSMA multigroup multicasting,how to provide fair and high-quality multiuser service under power and spectrum constraints is essential.In this paper,we propose a max-min fair RIS-aided rate-splitting multiple access(MMF-RISRSMA)scheme for multigroup multicast communications,where the rate fairness is obtained by maximizing the minimum group-rate.In doing so,we jointly optimize the beamformers,the rate splitting vector at the transmitter,as well as the phase shifts at RIS.To solve it,we divide the original optimization problem into two subproblems and alternately optimize the variables.The beamforming and rate splitting optimization subproblem is solved by using the successive convex approximation technique.The phase shift optimization subproblem is solved through the penalty function method to achieve a rank-one locally optimal solution.Simulations demonstrate that the proposed MMF-RIS-RSMA scheme can obtain significant performance gain in terms of the minimum group-rate. 展开更多
关键词 multigroup multicast communications rate-splitting multiple access(RSma) reconfigurable intelligent surfaces(RIS) max-min fairness(MMF)
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Power-Domain Collision-Tolerant Random Access Method with Auxiliary Beam for Satellite Internet of Things:A New Solution
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作者 Xu Yuanyuan Liu Ziwei +1 位作者 Bian Dongming Zhang Gengxin 《China Communications》 SCIE CSCD 2024年第8期236-248,共13页
There are numerous terminals in the satellite Internet of Things(IoT).To save cost and reduce power consumption,the system needs terminals to catch the characteristics of low power consumption and light control.The re... There are numerous terminals in the satellite Internet of Things(IoT).To save cost and reduce power consumption,the system needs terminals to catch the characteristics of low power consumption and light control.The regular random access(RA)protocols may generate large amounts of collisions,which degrade the system throughout severally.The near-far effect and power control technologies are not applicable in capture effect to obtain power difference,resulting in the collisions that cannot be separated.In fact,the optimal design at the receiving end can also realize the condition of packet power domain separation,but there are few relevant researches.In this paper,an auxiliary beamforming scheme is proposed for power domain signal separation.It adds an auxiliary reception beam based on the conventional beam,utilizing the correlation of packets in time-frequency domain between the main and auxiliary beam to complete signal separation.The roll-off belt of auxiliary beam is used to create the carrier-to-noise ratio(CNR)difference.This paper uses the genetic algorithm to optimize the auxiliary beam direction.Simulation results show that the proposed scheme outperforms slotted ALOHA(SA)in terms of system throughput per-formance and without bringing terminals additional control burden. 展开更多
关键词 beamforming non-orthogonal multiple access random access satellite Internet of Things
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Joint multiple resource allocation for offloading cost minimization in IRS-assisted MEC networks with NOMA
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作者 Guang Chen Yueyun Chen +4 位作者 Zhiyuan Mai Conghui Hao Meijie Yang Shuangshuang Han Liping Du 《Digital Communications and Networks》 SCIE CSCD 2023年第3期613-627,共15页
Effective resource allocation can exploit the advantage of intelligent reflective surface(IRS)assisted mobile edge computing(MEC)fully.However,it is challenging to balance the limited energy of MTs and the strict dela... Effective resource allocation can exploit the advantage of intelligent reflective surface(IRS)assisted mobile edge computing(MEC)fully.However,it is challenging to balance the limited energy of MTs and the strict delay requirement of their tasks.In this paper,in order to tackle the challenge,we jointly optimize the offloading delay and energy consumption of mobile terminals(MTs)to realize the delay-energy tradeoff in an IRS-assisted MEC network,in which non-orthogonal multiple access(NOMA)and multiantenna are applied to improve spectral efficiency.To achieve the optimal delay-energy tradeoff,an offloading cost minimization model is proposed,in which the edge computing resource allocation,signal detecting vector,uplink transmission power,and IRS phase shift coefficient are needed to be jointly optimized.The optimization of the model is a multi-level fractional problem in complex fields with some coupled high dimension variables.To solve the intractable problem,we decouple the original problem into a computing subproblem and a wireless transmission subproblem based on the uncoupled relationship between different variable types.The computing subproblem is proved convex and the closed-form solution is obtained for the edge computing resource allocation.Further,the wireless transmission subproblem is solved iteratively through decoupling the residual variables.In each iteration,the closed-form solution of residual variables is obtained through different successive convex approximation(SCA)methods.We verify the proposed algorithm can converge to an optimum with polynomial complexity.Simulation results indicate the proposed method achieves average saved costs of 65.64%,11.24%,and 9.49%over three benchmark methods respectively. 展开更多
关键词 Mobile edge computing Intelligent reflective surface Task offloading multiple resource allocation Non-orthogonal multiple access
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Hybrid Deep Learning-Based Adaptive Multiple Access Schemes Underwater Wireless Networks
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作者 D.Anitha R.A.Karthika 《Intelligent Automation & Soft Computing》 SCIE 2023年第2期2463-2477,共15页
Achieving sound communication systems in Under Water Acoustic(UWA)environment remains challenging for researchers.The communication scheme is complex since these acoustic channels exhibit uneven characteristics such a... Achieving sound communication systems in Under Water Acoustic(UWA)environment remains challenging for researchers.The communication scheme is complex since these acoustic channels exhibit uneven characteristics such as long propagation delay and irregular Doppler shifts.The development of machine and deep learning algorithms has reduced the burden of achieving reli-able and good communication schemes in the underwater acoustic environment.This paper proposes a novel intelligent selection method between the different modulation schemes such as Code Division Multiple Access(CDMA),Time Divi-sion Multiple Access(TDMA),and Orthogonal Frequency Division Multiplexing(OFDM)techniques using the hybrid combination of the convolutional neural net-works(CNN)and ensemble single feedforward layers(SFL).The convolutional neural networks are used for channel feature extraction,and boosted ensembled feedforward layers are used for modulation selection based on the CNN outputs.The extensive experimentation is carried out and compared with other hybrid learning models and conventional methods.Simulation results demonstrate that the performance of the proposed hybrid learning model has achieved nearly 98%accuracy and a 30%increase in BER performance which outperformed the other learning models in achieving the communication schemes under dynamic underwater environments. 展开更多
关键词 Code division multiple access time division multiple access convolutional neural networks feedforward layers
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Intelligent reflecting surface-assisted cognitive radio-inspired rate-splitting multiple access systems
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作者 Peixu Liu Gang Jing +2 位作者 Hongwu Liu Liang Yang Theodoros A.Tsiftsis 《Digital Communications and Networks》 SCIE CSCD 2023年第3期655-666,共12页
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
关键词 Rate-splitting multiple access(RSma) Intelligent reflecting surface(IRS) Successive interference cancellation(SIC) Cognitive radio
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Non-Orthogonal Multiple Access(NOMA) for Future Downlink Radio Access of 5G 被引量:12
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作者 LI Anxin LAN Yang +1 位作者 CHEN Xiaohang JIANG Huiling 《China Communications》 SCIE CSCD 2015年第S1期28-37,共10页
Multiple access(MA) technology is of most importance for 5G. Non-orthogonal multiple access(NOMA) utilizing power domain and advanced receiver has been considered as a promising candidate MA technology recently. In th... Multiple access(MA) technology is of most importance for 5G. Non-orthogonal multiple access(NOMA) utilizing power domain and advanced receiver has been considered as a promising candidate MA technology recently. In this paper, the NOMA concept is presented toward future enhancements of spectrum efficiency in lower frequency bands for downlink of 5G system. Key component technologies of NOMA are presented and discussed including multiuser transmission power allocation, scheduling algorithm, receiver design and combination of NOMA with multi-antenna technology. The performance gains of NOMA are evaluated by system-level simulations with very practical assumptions. Under multiple configurations and setups, the achievable system-level gains of NOMA are shown promising even when practical considerations were taken into account. 展开更多
关键词 multiple access NOma power ALLOCATION RECEIVER design MIMO
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Symbol Error Rate Performance Analysis of Non-Orthogonal Multiple Access for Visible Light Communications 被引量:3
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作者 Hongji Huang Jinyuan Wang +3 位作者 Jie Wang Jie Yang Jian Xiong Guan Gui 《China Communications》 SCIE CSCD 2017年第12期153-161,共9页
Non-orthogonal multiple access(NOMA) is considered as one of promising radio access techniques for visible light communications(VLC) in next-generation wireless communications systems.In order to provide theoretical s... Non-orthogonal multiple access(NOMA) is considered as one of promising radio access techniques for visible light communications(VLC) in next-generation wireless communications systems.In order to provide theoretical support for designing VLC-NOMA,we derive its analytic expressions for the symbol error rate(SER).Specifically,NOMA is first incorporated with appropriate VLC to establish a VLC-NOMA framework.Afterwards,mathematical expressions of the SER for the VLC-NOMA are developed.Moreover,numerical results are provided carefully to demonstrate that the proposed VLC-NOMA scheme outperforms than state-of-the-art orthogonal frequency division multiple access(OFDMA) one in terms of SER performance.Finally,relationships between the SER performance and the number of users,power allocation coefficient and semi-angle are well investigated,which can give us a scientific guide to devise the VLC-NOMA system for achieving better SER performance. 展开更多
关键词 VISIBLE light communication(VLC) non-orthogonal multiple access(NOma) SYMBOL ERROR rate (SER)
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Non-Orthogonal Multiple Access in Cell-Free Massive MIMO Networks 被引量:8
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作者 Yao Zhang Haotong Cao +1 位作者 Meng Zhou Longxiang Yang 《China Communications》 SCIE CSCD 2020年第8期81-94,共14页
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
关键词 non-orthogonal multiple access CF-mMIMO successive interference cancellation power optimization sequential convex approximation
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Unsourced Multiple Access for 6G Massive Machine Type Communications 被引量:4
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作者 Yuanjie Li Jincheng Dai +5 位作者 Zhongwei Si Kai Niu Chao Dong Jiaru Lin Sen Wang Yifei Yuan 《China Communications》 SCIE CSCD 2022年第3期70-87,共18页
Unsourced multiple access(UMA)is a multi-access technology for massive,low-power,uncoordinated,and unsourced Machine Type Communication(MTC)networks.It ensures transmission reliability under the premise of high energy... Unsourced multiple access(UMA)is a multi-access technology for massive,low-power,uncoordinated,and unsourced Machine Type Communication(MTC)networks.It ensures transmission reliability under the premise of high energy efficiency.Based on the analysis of the 6G MTC key performance indicators(KPIs)and scenario characteristics,this paper summarizes its requirements for radio access networks.Following this,the existing multiple access models are analyzed under these standards to determine UMA's advantages for 6G MTC according to its design characteristics.The critical technology of UMA is the design of its multiple-access coding scheme.Therefore,the existing UMA coding schemes from different coding paradigms are further summarized and compared.In particular,this paper comprehensively considers the energy efficiency and computational complexity of these schemes,studies the changes of the above two indexes with the increase of access scale,and considers the trade-off between the two.It is revealed by the above analysis that some guiding rules of UMA coding design.Finally,the open problems and potentials in this field are given for future research. 展开更多
关键词 unsourced multiple access machine type communications 6G massive random access uncoordinated
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Outage Performance of Non-Orthogonal Multiple Access Based Unmanned Aerial Vehicles Satellite Networks 被引量:18
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作者 Ting Qi Wei Feng Youzheng Wang 《China Communications》 SCIE CSCD 2018年第5期1-8,共8页
With rapid development of unmanned aerial vehicles(UAVs), more and more UAVs access satellite networks for data transmission. To improve the spectral efficiency, non-orthogonal multiple access(NOMA) is adopted to inte... With rapid development of unmanned aerial vehicles(UAVs), more and more UAVs access satellite networks for data transmission. To improve the spectral efficiency, non-orthogonal multiple access(NOMA) is adopted to integrate UAVs into the satellite network, where multiple satellites cooperatively serve the UAVs and mobile terminal using the Ku-band and above. Taking into account the rain fading and the fading correlation, the outage performance is first analytically obtained for fixed power allocation and then efficiently calculated by the proposed power allocation algorithm to guarantee the user fairness. Simulation results verify the outage performance analysis and show the performance improvement of the proposed power allocation scheme. 展开更多
关键词 non-orthogonal multiple access(NOma) outage performance power allocation satellite networks unmanned aerial vehicles (UAVs)
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Uplink Grant-Free Pattern Division Multiple Access (GF-PDMA) for 5G Radio Access 被引量:12
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作者 Wanwei Tang Shaoli Kang +1 位作者 Bin Ren Xinwei Yue 《China Communications》 SCIE CSCD 2018年第4期153-163,共11页
Massive machine type communication(m MTC) is one of the key application scenarios for the fifth generation mobile communication(5 G). Grant-free(GF) transmission can reduce the high signaling overhead in m MTC. Non-or... Massive machine type communication(m MTC) is one of the key application scenarios for the fifth generation mobile communication(5 G). Grant-free(GF) transmission can reduce the high signaling overhead in m MTC. Non-orthogonal multiple access(NMA) can support more users for m MTC than orthogonal frequency division multiple access(OFDMA). Applying GF transmission in NMA system becomes an active topic recently. The in-depth study on applying GF transmission in pattern division multiple access(PDMA), a competitive candidate scheme of NMA, is investigated in this paper. The definition, latency and allocation of resource and transmission mechanism for GF-PDMA are discussed in detail. The link-level and system-level evaluations are provided to verify the analysis. The analysis and simulation results demonstrate that the proposed GF-PDMA has lower latency than grant based PDMA(GB-PDMA), possesses strong scalability to confront collision and provides almost 2.15 times gain over GF-OFDMA in terms of supporting the number of active users in the system. 展开更多
关键词 pattern division multiple access(PDma) grant-free UPLINK massive machinetype communication (mMTC) 5G
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Performance Characterization and Receiver Design for Random Temporal Multiple Access in Non-Coordinated Networks 被引量:1
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作者 Yin Lu Jun Fang +1 位作者 Zhong Guo J.Andrew Zhang 《China Communications》 SCIE CSCD 2019年第6期173-184,共12页
Random access is a well-known multiple access method for uncoordinated communication nodes.Existing work mainly focuses on optimizing iterative access protocols,assuming that packets are corrupted once they are collid... Random access is a well-known multiple access method for uncoordinated communication nodes.Existing work mainly focuses on optimizing iterative access protocols,assuming that packets are corrupted once they are collided,or that feedback is available and can be exploited.In practice,a packet may still be able to be recovered successfully even when collided with other packets.System design and performance analysis under such a situation,particularly when the details of collision are taken into consideration,are less known.In this paper,we provide a framework for analytically evaluating the actual detection performance in a random temporal multiple access system where nodes can only transmit.Explicit expressions are provided for collision probability and signal to interference and noise ratio(SINR)when different numbers of packets are collided.We then discuss and compare two receiver options for the AP,and provide detailed receiver design for the premium one.In particular,we propose a synchronization scheme which can largely reduce the preamble length.We also demonstrate that system performance could be a convex function of preamble length both analytically and via simulation,as well as the forward error correction(FEC)coding rate. 展开更多
关键词 RANDOM TEMPORAL multiple access non-coordination NETWORKS packet COLLISION
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Collaborative Multiple Access And Energy-Efficient Resource Allocation in Distributed Maritime Wireless Networks 被引量:3
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作者 Xueyan Cao Hongming Zhang Mugen Peng 《China Communications》 SCIE CSCD 2022年第4期137-153,共17页
With the rapid increasing of maritime activities, maritime wireless networks(MWNs) with high reliability, high energy efficiency, and low delay are required. However, the centralized networking with fixed resource sch... With the rapid increasing of maritime activities, maritime wireless networks(MWNs) with high reliability, high energy efficiency, and low delay are required. However, the centralized networking with fixed resource scheduling is not suitable for MWNs due to the special environment. In this paper,we introduce the collaborative relay communication in distributed MWNs to improve the link reliability, and propose an orthogonal time-frequency resource block reservation based multiple access(RRMA) scheme for both one-hop direct link and two-hop collaborative relay link to reduce the interference. To further improve the network performance, we formulate an energy efficiency(EE) maximization resource allocation problem and solve it by an iterative algorithm based on the Dinkelbach method. Finally, numerical results are provided to investigate the proposed RRMA scheme and resource allocation algorithm, showing that the low outage probability and transmission delay can be attained by the proposed RRMA scheme. Moreover,the proposed resource allocation algorithm is capable of achieving high EE in distributed MWNs. 展开更多
关键词 maritime wireless networks distributed multiple access resource allocation energy efficiency maximization
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Uplink Performance Evaluation of CDMA Communication System with RAKE Receiver and Multiple Access Interference Cancellation 被引量:1
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作者 Ayodeji J. Bamisaye Michael O. Kolawole 《International Journal of Communications, Network and System Sciences》 2010年第6期540-547,共8页
In CDMA communication systems, all the subscribers share the common channel. The limitation factor on the system’s capacity is not the bandwidth, but multiuser interference and the near far problem. This paper models... In CDMA communication systems, all the subscribers share the common channel. The limitation factor on the system’s capacity is not the bandwidth, but multiuser interference and the near far problem. This paper models CDMA system from the perspective of mobile radio channels corrupted by additive white noise generated by multipath and multiple access interferences. The system’s receiver is assisted using different combining diversity techniques. Performance analysis of the system with these detection techniques is presented. The paper demonstrates that combining diversity techniques in the system’s receivers markedly improve the performance of CDMA systems. 展开更多
关键词 CDma MULTIPATH Diversity multiple access INTERFERENCE CANCELLATION RAKE Receiver Parallel INTERFERENCE CANCELLATION
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Resource Allocation Based on User Pairing and Subcarrier Matching for Downlink Non-Orthogonal Multiple Access Networks 被引量:1
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作者 Zhixin Liu Changjian Liang +2 位作者 Yazhou Yuan Kit Yan Chan Xinping Guan 《IEEE/CAA Journal of Automatica Sinica》 SCIE EI CSCD 2021年第3期679-689,共11页
The traditional orthogonal multiple access(OMA)is unable to satisfy the needs of large number of smart devices.To increase the transmission rate in the limited spectrum resource,implementation of both non-orthogonal m... The traditional orthogonal multiple access(OMA)is unable to satisfy the needs of large number of smart devices.To increase the transmission rate in the limited spectrum resource,implementation of both non-orthogonal multiple access(NOMA)and successive interference cancelation(SIC)is essential.In this paper,an optimal resource allocation algorithm in NOMA is proposed to maximize the total system rate in a multi-sector multi-subcarrier relay-assisted communication network.Since the original problem is a non-convex problem with mixed integer programming which is non-deterministic polynomial-time(NP)-hard,a three-step solution is proposed to solve the primal problem.Firstly,we determine the optimal power allocation of the outer users by using the approach of monotonic discrimination,and then the optimal user pairing is determined.Secondly,the successive convex approximation(SCA)method is introduced to transform the non-convex problem involving central users into convex one,and the Lagrangian dual method is used to determine the optimal solution.Finally,the standard Hungarian algorithm is utilized to determine the optimal subcarrier matching.The simulation results show that resource allocation algorithm is able to meet the user performance requirements with NOMA,and the total system rate is improved compared to the existing algorithms. 展开更多
关键词 Non-orthogonal multiple access(NOma) power control rate maximization subcarrier matching user pairing
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Joint Non-Orthogonal Multiple Access (NOMA) & Walsh-Hadamard Transform: Enhancing the Receiver Performance 被引量:2
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作者 Muhammad Rehan Usman Arsla Khan +1 位作者 Muhammad Arslan Usman Soo young Shin 《China Communications》 SCIE CSCD 2018年第9期160-177,共18页
Non-orthogonal multiple access(NOMA) is a new access method to achieve high performance gains in terms of capacity and throughput, so it is currently under consideration as one of the candidates for fifth generation(5... Non-orthogonal multiple access(NOMA) is a new access method to achieve high performance gains in terms of capacity and throughput, so it is currently under consideration as one of the candidates for fifth generation(5 G) technologies. NOMA utilizes power domain in order to superimpose signals of multiple users in a single transmitted signal. This creates a lot of interference at the receive side. Although the use of successive interference cancellation(SIC) technique reduces the interference, but to further improve the receiver performance, in this paper, we have proposed a joint Walsh-Hadamard transform(WHT) and NOMA approach for achieving better performance gains than the conventional NOMA. WHT is a well-known code used in communication systems and is used as an orthogonal variable spreading factor(OVSF) in communication systems. Application of WHT to NOMA results in low bit error rate(BER) and high throughput performance for both low and high channel gain users. Further, it also reduces peak to average power ratio(PAPR) of the user signal. The results are discussed in terms of comparison between the conventionalNOMA and the proposed technique, which shows that it offers high performance gains in terms of low BER at different SNR levels, reduced PAPR, high user throughput performance and better spectral efficiency. 展开更多
关键词 Bit error rate (BER) non-orthogonal multiple access (NOma) orthogonal frequency division multiplexing (OFDM) peak to average power ratio (PAPR) successive interference cancellation (SIC) throughput and Walsh-Hadamard transform (WHT).
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