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
Four types of variable-rate convolutional network codes are investigated over a single-source finite cyclic network. It is found that variable-rate generic, dispersion and broadcast can be implemented on the same netw...Four types of variable-rate convolutional network codes are investigated over a single-source finite cyclic network. It is found that variable-rate generic, dispersion and broadcast can be implemented on the same network without changing the local encoding kernels of the non-source nodes. The efficient implementation has the advantage that each non-source node only needs to store one copy of the local encoding kernel within a session. However, it is also shown by an example that variable-rate multicast may not always be implemented under the above condition.展开更多
This paper considers a secure multigroup multicast multiple-input single-output(MISO)communication system aided by an intelligent reflecting surface(IRS).Specifically,we aim to minimize the transmit power at Alice via...This paper considers a secure multigroup multicast multiple-input single-output(MISO)communication system aided by an intelligent reflecting surface(IRS).Specifically,we aim to minimize the transmit power at Alice via jointly optimizing the transmit beamformer,artificial noise(AN)vector and phase shifts at the IRS subject to the secrecy rate constraints as well as the unit modulus constraints of IRS phase shifts.To tackle the optimization problem,we first transform it into a semidefinite relaxation(SDR)problem,and then alternately update the transmit beamformer and AN matrix as well as the phase shifts at the IRS.In order to reduce the high computational complexity,we further propose a low-complexity algorithm based on second-order cone programming(SOCP).We decouple the optimization problem into two sub-problems and optimize the transmit beamformer,AN vector and the phase shifts alternately by solving two corresponding SOCP subproblem.Simulation results show that the proposed SDR and SOCP schemes require half or less transmit power than the scheme without IRS,which demonstrates the advantages of introducing IRS and the effectiveness of the proposed methods.展开更多
为缓解基站的视频流量过载,本文针对时延敏感的实时视频业务,设计一种D2D协作视频多播传输方案。该方案采用可伸缩视频编码(Scalable Video Coding, SVC)对视频流进行编码处理,利用SVC流的分层结构特征来应对多播信道间的差异性。在SVC...为缓解基站的视频流量过载,本文针对时延敏感的实时视频业务,设计一种D2D协作视频多播传输方案。该方案采用可伸缩视频编码(Scalable Video Coding, SVC)对视频流进行编码处理,利用SVC流的分层结构特征来应对多播信道间的差异性。在SVC编码的基础上,为了改善用户观看体验及提升用户所接收的视频质量,所提出的协作式视频传输方案引入有效吞吐量这一概念,在一定时延约束下,根据信道反馈信息灵活地对不同信道上的不同SVC视频层进行码率调整。仿真结果表明,所提出的方案能够有效地减小端到端时延,有效丢失率,提高有效吞吐量。展开更多
Fong et al.analyzed variable-rate linear network coding for linear broadcast.However,the authors didn't investigate it for the other three types of linear network codes.In this paper,by simple and clear proofs,it ...Fong et al.analyzed variable-rate linear network coding for linear broadcast.However,the authors didn't investigate it for the other three types of linear network codes.In this paper,by simple and clear proofs,it is found that there are similar results for variable-rate linear generic and linear dispersion if the field size is large enough.It means that linear generics and linear dispersions of different dimensions can be implemented on the same network,while each non-source node is required to store only one copy of the local encoding kernel within a session.Moreover,an example is given to show that there isn't a similar result for linear multicast.展开更多
提出了一种新的基于数据包束探测(packet-bunch probe)和TCP吞吐量公式的多速率多播拥塞控制方案PTMCC(packet-bunch probe and TCP-formula based multicast congestion control)。这种接收端驱动的拥塞控制,采用数据包束来探测网络的...提出了一种新的基于数据包束探测(packet-bunch probe)和TCP吞吐量公式的多速率多播拥塞控制方案PTMCC(packet-bunch probe and TCP-formula based multicast congestion control)。这种接收端驱动的拥塞控制,采用数据包束来探测网络的可用带宽,利用TCP吞吐量公式得到TCP友好速率,并采用了新的速率调节算法。仿真实验表明,PTMCC在收敛性、灵敏性以及TCP友好性上具有较好的性能。展开更多
The optimal rate control problem in networks with unicast and multiratemulticast sessions is investigated. A penalty function approach is used to solve a convex programformulation of this problem, and then a heuristic...The optimal rate control problem in networks with unicast and multiratemulticast sessions is investigated. A penalty function approach is used to solve a convex programformulation of this problem, and then a heuristic rate control algorithm is derived. The algorithmis distributed, and suitable both for source-driven unicast sessions and receiver-driven multicastsessions. To obtain practical viability, the computational burden on core routers as well asend-hosts is kept very low, also is the overhead of network congestion feedback. Simulation resultsshow that the algorithm guarantees TCP (Transmission Control Protocol)-based unicast sessionscoexisting with multirate multicast sessions in a fair and friendly manner. It is also shown thatvarious fairness criteria of resource allocation could be achieved by choosing appropriate utilityfunctions, and resource-utilizing efficiencies would be likewise different.展开更多
We propose two rate control schemes for multi-antenna multicast in OFDM systems, which aim to maximize the minimum average rate over all users in a multicast group. In our system, we do not require all multicast users...We propose two rate control schemes for multi-antenna multicast in OFDM systems, which aim to maximize the minimum average rate over all users in a multicast group. In our system, we do not require all multicast users to successfully recover the signals received on each subcarrier. In contrast, we allow certain loss for multicast users, such that the multicast transmission rate can be increased. We assume that the loss-repairing can be completed at upper protocol layers via advanced fountain codes. Following this principle, we formulate the rate control problem via beamforming in multi-antenna multicast to optimize the minimum achievable rate for all multicast users. While the computation complexity to solve for the optimal beamformer is prohibitively high, we propose a suboptimal iterative rate control scheme. Moreover, we modify the above optimization problem by selecting a ?xed proportion of users on each subcarrier. The beamformer searching process will then be performed only based on the selected users on each subcarrier, such that the complexity can be further reduced. We also solve this new problem with a low complexity approach. Theoretical analyses and simulation results show that our proposed two rate control schemes can have higher minimum average rate than the baseline scheme without rate control, while achieving low complexity.展开更多
异构网络中视频流分层组播的层速率优化问题主要涉及分层数、分层速率和用户链路带宽,针对层速率优化NP-hard问题,本文提出一种基于用户簇的分层组播层速率优化UC-LRAO(layer rate allocation optimization with user cluster)算法.根...异构网络中视频流分层组播的层速率优化问题主要涉及分层数、分层速率和用户链路带宽,针对层速率优化NP-hard问题,本文提出一种基于用户簇的分层组播层速率优化UC-LRAO(layer rate allocation optimization with user cluster)算法.根据用户数对视频流进行分层,确定每层用户数和各用户承载分层视频流的带宽,采用最大流–最小割的Edmonds-Karp算法和层内网络编码实现每层用户视频流的传输链路所需带宽的分配.基于预定视频流分层的层数要求,利用用户分簇对原分层重新合并,从而优化分配分层速率和链路带宽.仿真结果表明所提出的算法可以提高系统吞吐量.展开更多
基金supported in part by the Project of International Cooperation and Exchanges NSFC under Grant No.61860206005in part by the National Natural Science Foundation of China under Grant No.62201329,No.62171262in part by Shandong Provincial Natural Science Foundation under Grant ZR2021YQ47。
文摘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.
基金supported by the National Natural Science Foundation of China and the Research Grants Council of Hong Kong Joint Research Scheme (60731160626)the National Natural Science Foundation of China (60821001)+1 种基金the Fundamental Research Funds for the Central Universities (BUPT2009RC0220)the 111 Project (B08004)
文摘Four types of variable-rate convolutional network codes are investigated over a single-source finite cyclic network. It is found that variable-rate generic, dispersion and broadcast can be implemented on the same network without changing the local encoding kernels of the non-source nodes. The efficient implementation has the advantage that each non-source node only needs to store one copy of the local encoding kernel within a session. However, it is also shown by an example that variable-rate multicast may not always be implemented under the above condition.
基金supported in part by the National Natural Science Foundation of China under Grants 62071234,61901121 and 61771244in part by the Natural Science Research Project of Education Department of Anhui Province of China under Grant KJ2019A1002.
文摘This paper considers a secure multigroup multicast multiple-input single-output(MISO)communication system aided by an intelligent reflecting surface(IRS).Specifically,we aim to minimize the transmit power at Alice via jointly optimizing the transmit beamformer,artificial noise(AN)vector and phase shifts at the IRS subject to the secrecy rate constraints as well as the unit modulus constraints of IRS phase shifts.To tackle the optimization problem,we first transform it into a semidefinite relaxation(SDR)problem,and then alternately update the transmit beamformer and AN matrix as well as the phase shifts at the IRS.In order to reduce the high computational complexity,we further propose a low-complexity algorithm based on second-order cone programming(SOCP).We decouple the optimization problem into two sub-problems and optimize the transmit beamformer,AN vector and the phase shifts alternately by solving two corresponding SOCP subproblem.Simulation results show that the proposed SDR and SOCP schemes require half or less transmit power than the scheme without IRS,which demonstrates the advantages of introducing IRS and the effectiveness of the proposed methods.
文摘为缓解基站的视频流量过载,本文针对时延敏感的实时视频业务,设计一种D2D协作视频多播传输方案。该方案采用可伸缩视频编码(Scalable Video Coding, SVC)对视频流进行编码处理,利用SVC流的分层结构特征来应对多播信道间的差异性。在SVC编码的基础上,为了改善用户观看体验及提升用户所接收的视频质量,所提出的协作式视频传输方案引入有效吞吐量这一概念,在一定时延约束下,根据信道反馈信息灵活地对不同信道上的不同SVC视频层进行码率调整。仿真结果表明,所提出的方案能够有效地减小端到端时延,有效丢失率,提高有效吞吐量。
基金Sponsored by the National Natural Science Foundation of China and the Research Grants Council of Hong Kong Joint Research Scheme(Grant No.60731160626)the National Natural Science Foundation of China(Grant No.60821001and61003287)+1 种基金the 111 Project(Grant No.B08004)the Fundamental Research Funds for the Central Universities(Grant No.BUPT2009RC0220)
文摘Fong et al.analyzed variable-rate linear network coding for linear broadcast.However,the authors didn't investigate it for the other three types of linear network codes.In this paper,by simple and clear proofs,it is found that there are similar results for variable-rate linear generic and linear dispersion if the field size is large enough.It means that linear generics and linear dispersions of different dimensions can be implemented on the same network,while each non-source node is required to store only one copy of the local encoding kernel within a session.Moreover,an example is given to show that there isn't a similar result for linear multicast.
文摘提出了一种新的基于数据包束探测(packet-bunch probe)和TCP吞吐量公式的多速率多播拥塞控制方案PTMCC(packet-bunch probe and TCP-formula based multicast congestion control)。这种接收端驱动的拥塞控制,采用数据包束来探测网络的可用带宽,利用TCP吞吐量公式得到TCP友好速率,并采用了新的速率调节算法。仿真实验表明,PTMCC在收敛性、灵敏性以及TCP友好性上具有较好的性能。
文摘The optimal rate control problem in networks with unicast and multiratemulticast sessions is investigated. A penalty function approach is used to solve a convex programformulation of this problem, and then a heuristic rate control algorithm is derived. The algorithmis distributed, and suitable both for source-driven unicast sessions and receiver-driven multicastsessions. To obtain practical viability, the computational burden on core routers as well asend-hosts is kept very low, also is the overhead of network congestion feedback. Simulation resultsshow that the algorithm guarantees TCP (Transmission Control Protocol)-based unicast sessionscoexisting with multirate multicast sessions in a fair and friendly manner. It is also shown thatvarious fairness criteria of resource allocation could be achieved by choosing appropriate utilityfunctions, and resource-utilizing efficiencies would be likewise different.
文摘We propose two rate control schemes for multi-antenna multicast in OFDM systems, which aim to maximize the minimum average rate over all users in a multicast group. In our system, we do not require all multicast users to successfully recover the signals received on each subcarrier. In contrast, we allow certain loss for multicast users, such that the multicast transmission rate can be increased. We assume that the loss-repairing can be completed at upper protocol layers via advanced fountain codes. Following this principle, we formulate the rate control problem via beamforming in multi-antenna multicast to optimize the minimum achievable rate for all multicast users. While the computation complexity to solve for the optimal beamformer is prohibitively high, we propose a suboptimal iterative rate control scheme. Moreover, we modify the above optimization problem by selecting a ?xed proportion of users on each subcarrier. The beamformer searching process will then be performed only based on the selected users on each subcarrier, such that the complexity can be further reduced. We also solve this new problem with a low complexity approach. Theoretical analyses and simulation results show that our proposed two rate control schemes can have higher minimum average rate than the baseline scheme without rate control, while achieving low complexity.
文摘异构网络中视频流分层组播的层速率优化问题主要涉及分层数、分层速率和用户链路带宽,针对层速率优化NP-hard问题,本文提出一种基于用户簇的分层组播层速率优化UC-LRAO(layer rate allocation optimization with user cluster)算法.根据用户数对视频流进行分层,确定每层用户数和各用户承载分层视频流的带宽,采用最大流–最小割的Edmonds-Karp算法和层内网络编码实现每层用户视频流的传输链路所需带宽的分配.基于预定视频流分层的层数要求,利用用户分簇对原分层重新合并,从而优化分配分层速率和链路带宽.仿真结果表明所提出的算法可以提高系统吞吐量.
