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
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
Non-orthogonal multiple access (NOMA) technology has recently been widely integrated into multi-access edge computing (MEC) to support task offloading in industrial wireless networks (IWNs) with limited radio resource...Non-orthogonal multiple access (NOMA) technology has recently been widely integrated into multi-access edge computing (MEC) to support task offloading in industrial wireless networks (IWNs) with limited radio resources. This paper minimizes the system overhead regarding task processing delay and energy consumption for the IWN with hybrid NOMA and orthogonal multiple access (OMA) schemes. Specifically, we formulate the system overhead minimization (SOM) problem by considering the limited computation and communication resources and NOMA efficiency. To solve the complex mixed-integer nonconvex problem, we combine the multi-agent twin delayed deep deterministic policy gradient (MATD3) and convex optimization, namely MATD3-CO, for iterative optimization. Specifically, we first decouple SOM into two sub-problems, i.e., joint sub-channel allocation and task offloading sub-problem, and computation resource allocation sub-problem. Then, we propose MATD3 to optimize the sub-channel allocation and task offloading ratio, and employ the convex optimization to allocate the computation resource with a closed-form expression derived by the Karush-Kuhn-Tucker (KKT) conditions. The solution is obtained by iteratively solving these two sub-problems. The experimental results indicate that the MATD3-CO scheme, when compared to the benchmark schemes, significantly decreases system overhead with respect to both delay and energy consumption.展开更多
为提高非正交多址接入(non-orthogonal multiple access,NOMA)增强型设备到设备(device-to-device,D2D)组链路的鲁棒性和能效,考虑非理想信道状态信息(channel station information,CSI),提出一种能效优化的鲁棒资源分配算法.首先,在保...为提高非正交多址接入(non-orthogonal multiple access,NOMA)增强型设备到设备(device-to-device,D2D)组链路的鲁棒性和能效,考虑非理想信道状态信息(channel station information,CSI),提出一种能效优化的鲁棒资源分配算法.首先,在保证子信道分配、蜂窝用户和D2D组最小速率以及D2D组最大传输功率约束下,建立最大最小鲁棒能效模型;其次,考虑最坏情况法将信道不确定性建模为有界信道估计误差,并用泰勒级数展开式、凸松弛、变量转换法将原多变量耦合问题转化为凸优化问题;最后,用拉格朗日对偶理论求解.仿真结果表明,所提出的算法将传输速率控制在最低速率阈值以上,具有良好的鲁棒性,与其他算法相比能效提高了8.3%.展开更多
无小区大规模多输入多输出(Multiple-Input Multiple-Output,MIMO)与非正交多址接入(Non-Orthogonal Multiple Access,NOMA)都是未来6G的使能技术。无线携能通信(Simultaneous Wireless Information and Power Transfer,SWIPT)技术在进...无小区大规模多输入多输出(Multiple-Input Multiple-Output,MIMO)与非正交多址接入(Non-Orthogonal Multiple Access,NOMA)都是未来6G的使能技术。无线携能通信(Simultaneous Wireless Information and Power Transfer,SWIPT)技术在进行信息解码的同时收集能量,与无小区大规模MIMO-NOMA优势互补。文中基于SWIPT研究无小区大规模MIMO-NOMA系统中的能量效率问题,通过联合优化功率分配系数和SWIPT的时隙切换(Time Switching,TS)系数,提高系统的能量效率。为了最大化能量效率,采用布谷鸟算法设计功率分配系数。考虑一种特殊情况,将所有终端的TS系数设置相同,进而推导了最佳TS系数的封闭表达式。仿真结果表明,相较于几种已有方案,文中提出的优化方案可以显著提升系统的能量效率。展开更多
The major challenge faced by the fifth generation(5G) mobile network is higher spectral efficiency and massive connectivity,i.e.,the target spectrum efficiency is 3 times over 4G,and the target connection density is o...The major challenge faced by the fifth generation(5G) mobile network is higher spectral efficiency and massive connectivity,i.e.,the target spectrum efficiency is 3 times over 4G,and the target connection density is one million devices per square kilometer.These requirements are difficult to be satisfied with orthogonal multiple access(OMA) schemes.Non-orthogonal multiple access(NOMA) has thus been proposed as a promising candidate to address some of the challenges for 5G.In this paper,a comprehensive survey of different candidate NOMA schemes for 5G is presented,where the usage scenarios of5 G and the application requirements for NOMA are firstly discussed.A general framework of NOMA scheme is established and the features of typical NOMA schemes are analyzed and compared.We focus on the recent progress and challenge of NOMA in standardization of international telecommunication union(ITU),and 3rd generation partnership project(3GPP).In addition,prototype development and future research directions are also provided respectively.展开更多
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
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
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
In recent years, non-orthogonal multiple access(NOMA) has attracted a lot of attention as a novel and promising power-domain us-er multiplexing scheme for Long-Term Evolution(LTE) enhancement and 5G. NOMA is able to c...In recent years, non-orthogonal multiple access(NOMA) has attracted a lot of attention as a novel and promising power-domain us-er multiplexing scheme for Long-Term Evolution(LTE) enhancement and 5G. NOMA is able to contribute to the improvement ofthe tradeoff between system capacity and user fairness(i.e., cell-edge user experience). This improvement becomes in particularemphasized in a cellular system where the channel conditions vary significantly among users due to the near-far effect. In this arti-cle, we provide an overview of the concept, design and performance of NOMA. In addition, we review the potential benefits and is-sues of NOMA over orthogonal multiple access(OMA) such as orthogonal frequency division multiple access(OFDMA) adoptedby LTE, and the status of 3GPP standardization related to NOMA.展开更多
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
文摘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.
基金supported by Priority Research Centers Program through the National Research Foundation of Korea(NRF) funded by the Ministry of Education, Science and Technology (2018R1A6A1A03024003)
文摘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.
基金supported by the National Natural Science Foundation of China under Grants 92267108,62173322 and 61821005the Science and Technology Program of Liaoning Province under Grants 2023JH3/10200004 and 2022JH25/10100005.
文摘Non-orthogonal multiple access (NOMA) technology has recently been widely integrated into multi-access edge computing (MEC) to support task offloading in industrial wireless networks (IWNs) with limited radio resources. This paper minimizes the system overhead regarding task processing delay and energy consumption for the IWN with hybrid NOMA and orthogonal multiple access (OMA) schemes. Specifically, we formulate the system overhead minimization (SOM) problem by considering the limited computation and communication resources and NOMA efficiency. To solve the complex mixed-integer nonconvex problem, we combine the multi-agent twin delayed deep deterministic policy gradient (MATD3) and convex optimization, namely MATD3-CO, for iterative optimization. Specifically, we first decouple SOM into two sub-problems, i.e., joint sub-channel allocation and task offloading sub-problem, and computation resource allocation sub-problem. Then, we propose MATD3 to optimize the sub-channel allocation and task offloading ratio, and employ the convex optimization to allocate the computation resource with a closed-form expression derived by the Karush-Kuhn-Tucker (KKT) conditions. The solution is obtained by iteratively solving these two sub-problems. The experimental results indicate that the MATD3-CO scheme, when compared to the benchmark schemes, significantly decreases system overhead with respect to both delay and energy consumption.
文摘为提高非正交多址接入(non-orthogonal multiple access,NOMA)增强型设备到设备(device-to-device,D2D)组链路的鲁棒性和能效,考虑非理想信道状态信息(channel station information,CSI),提出一种能效优化的鲁棒资源分配算法.首先,在保证子信道分配、蜂窝用户和D2D组最小速率以及D2D组最大传输功率约束下,建立最大最小鲁棒能效模型;其次,考虑最坏情况法将信道不确定性建模为有界信道估计误差,并用泰勒级数展开式、凸松弛、变量转换法将原多变量耦合问题转化为凸优化问题;最后,用拉格朗日对偶理论求解.仿真结果表明,所提出的算法将传输速率控制在最低速率阈值以上,具有良好的鲁棒性,与其他算法相比能效提高了8.3%.
文摘无小区大规模多输入多输出(Multiple-Input Multiple-Output,MIMO)与非正交多址接入(Non-Orthogonal Multiple Access,NOMA)都是未来6G的使能技术。无线携能通信(Simultaneous Wireless Information and Power Transfer,SWIPT)技术在进行信息解码的同时收集能量,与无小区大规模MIMO-NOMA优势互补。文中基于SWIPT研究无小区大规模MIMO-NOMA系统中的能量效率问题,通过联合优化功率分配系数和SWIPT的时隙切换(Time Switching,TS)系数,提高系统的能量效率。为了最大化能量效率,采用布谷鸟算法设计功率分配系数。考虑一种特殊情况,将所有终端的TS系数设置相同,进而推导了最佳TS系数的封闭表达式。仿真结果表明,相较于几种已有方案,文中提出的优化方案可以显著提升系统的能量效率。
基金supported by the National High Technology Research and Development Program of China (863 Program, No. 2015AA01A709)
文摘The major challenge faced by the fifth generation(5G) mobile network is higher spectral efficiency and massive connectivity,i.e.,the target spectrum efficiency is 3 times over 4G,and the target connection density is one million devices per square kilometer.These requirements are difficult to be satisfied with orthogonal multiple access(OMA) schemes.Non-orthogonal multiple access(NOMA) has thus been proposed as a promising candidate to address some of the challenges for 5G.In this paper,a comprehensive survey of different candidate NOMA schemes for 5G is presented,where the usage scenarios of5 G and the application requirements for NOMA are firstly discussed.A general framework of NOMA scheme is established and the features of typical NOMA schemes are analyzed and compared.We focus on the recent progress and challenge of NOMA in standardization of international telecommunication union(ITU),and 3rd generation partnership project(3GPP).In addition,prototype development and future research directions are also provided respectively.
基金supported by National Natural Science Foundation of China grants(No.61401069,No.61271240,No.61501254)Jiangsu Specially Appointed Professor Grant(RK002STP16001)+2 种基金Innovation and Entrepreneurship of Jiangsu High-level Talent Grant(CZ0010617002)High-level talent startup grant of Nanjing University of Posts and Telecommunications(XK0010915026)“1311 Talent Plan” of Nanjing University of Posts and Telecommunications
文摘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.
基金supported in part by the National Natural Science Foundation of China (No. 91638205, 91438206, 61771286, 61621091)
文摘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.
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.
文摘In recent years, non-orthogonal multiple access(NOMA) has attracted a lot of attention as a novel and promising power-domain us-er multiplexing scheme for Long-Term Evolution(LTE) enhancement and 5G. NOMA is able to contribute to the improvement ofthe tradeoff between system capacity and user fairness(i.e., cell-edge user experience). This improvement becomes in particularemphasized in a cellular system where the channel conditions vary significantly among users due to the near-far effect. In this arti-cle, we provide an overview of the concept, design and performance of NOMA. In addition, we review the potential benefits and is-sues of NOMA over orthogonal multiple access(OMA) such as orthogonal frequency division multiple access(OFDMA) adoptedby LTE, and the status of 3GPP standardization related to NOMA.
基金This work was partly supported by the Natural Science Foundation of Hebei Province(F2019203095)the National Natural Science Foundation of China(61873223,61803328)the National Key R&D Program of China(2018YFB1702100)。
文摘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.
