In this paper,a power allocation to maximize tradeoff between spectrum efficiency(SE)and energy efficiency(EE)is considered for the downlink non-orthogonal multiple access(NOMA)system with arbitrarily clusters and arb...In this paper,a power allocation to maximize tradeoff between spectrum efficiency(SE)and energy efficiency(EE)is considered for the downlink non-orthogonal multiple access(NOMA)system with arbitrarily clusters and arbitrarily users,where the subcarriers of clusters are mutually orthogonal to each other.Specifically,an optimization problem of maximizing SE-EE tradeoff is formulated by optimizing power allocation among users under the constraints of user rate requirements.Then,the optimization problem is decomposed into a group of sub-problems with the aim of maximizing SE-EE tradeoff for each cluster,which is solved by using bisection method and monotonicity of function.Finally,the power allocation optimization problem among users is transformed into that between clusters,and a two steps inter-cluster power allocation algorithm is developed to solve this problem.Simulation results show that SE-EE tradeoff of the proposed scheme is better than that of the existing schemes.展开更多
The authors in this article investigated how to cancel multi-user interference with low feedback amount over 3-user multiple input multiple output （MIMO） interference channel using space-time code and precoders. Spa...The authors in this article investigated how to cancel multi-user interference with low feedback amount over 3-user multiple input multiple output （MIMO） interference channel using space-time code and precoders. Space-time block code with coding rate 2 was designed, also zero vectors were introduced into each codeword. The multi-user interference is mitigated by pre-coding at the transmitters and nonlinear operation and unidirectional cooperation link at the receivers. Compared with the existing scheme for the same scene, the proposed scheme greatly reduces feedback amount and improves the sum degrees of freedom （DOF）. Simulation demonstrates the validity of the proposed scheme.展开更多
We investigate how to cancel interference by using space time code and codeword space alignment for multiple-input multiple-output （MIMO） Y channel consisting of three users and a relay. All the nodes adopt Alamouti...We investigate how to cancel interference by using space time code and codeword space alignment for multiple-input multiple-output （MIMO） Y channel consisting of three users and a relay. All the nodes adopt Alamouti code. During the multiple access （MA） stage, two codewords within each reciprocal codeword pair are aligned through pre-coding. The relay decodes the elements of each codeword pair using the orthogonal property of effective channel matrix of Alamouti codeword. During the broadcast （BC） stage, the interference between codeword pairs at each user is eliminated by the orthogonal property of effective channel matrix of Alamouti codeword, instead of the interference alignment （IA） pre-coding. Thus, channel state information （CSI） is not required during the BC stage, which greatly reduce the amount of feedback.展开更多
基金This work was supported by the Henan Scientific and Technological Research Project Research(172102210023)Department of Education of Henan Province‘ Research on Clustering and Frequency Band Allocation in JT-CoMP’(19A510013).
文摘In this paper,a power allocation to maximize tradeoff between spectrum efficiency(SE)and energy efficiency(EE)is considered for the downlink non-orthogonal multiple access(NOMA)system with arbitrarily clusters and arbitrarily users,where the subcarriers of clusters are mutually orthogonal to each other.Specifically,an optimization problem of maximizing SE-EE tradeoff is formulated by optimizing power allocation among users under the constraints of user rate requirements.Then,the optimization problem is decomposed into a group of sub-problems with the aim of maximizing SE-EE tradeoff for each cluster,which is solved by using bisection method and monotonicity of function.Finally,the power allocation optimization problem among users is transformed into that between clusters,and a two steps inter-cluster power allocation algorithm is developed to solve this problem.Simulation results show that SE-EE tradeoff of the proposed scheme is better than that of the existing schemes.
基金supported in part by the National Natural Science Foundation of China (51174263)
文摘The authors in this article investigated how to cancel multi-user interference with low feedback amount over 3-user multiple input multiple output （MIMO） interference channel using space-time code and precoders. Space-time block code with coding rate 2 was designed, also zero vectors were introduced into each codeword. The multi-user interference is mitigated by pre-coding at the transmitters and nonlinear operation and unidirectional cooperation link at the receivers. Compared with the existing scheme for the same scene, the proposed scheme greatly reduces feedback amount and improves the sum degrees of freedom （DOF）. Simulation demonstrates the validity of the proposed scheme.
基金supported by Opening Foundation of Opening Project of Mine Informatization of Henan (KY2015-01)the Fundamental Research Funds for the Universities of Henan Province (NSFRF140126)
文摘We investigate how to cancel interference by using space time code and codeword space alignment for multiple-input multiple-output （MIMO） Y channel consisting of three users and a relay. All the nodes adopt Alamouti code. During the multiple access （MA） stage, two codewords within each reciprocal codeword pair are aligned through pre-coding. The relay decodes the elements of each codeword pair using the orthogonal property of effective channel matrix of Alamouti codeword. During the broadcast （BC） stage, the interference between codeword pairs at each user is eliminated by the orthogonal property of effective channel matrix of Alamouti codeword, instead of the interference alignment （IA） pre-coding. Thus, channel state information （CSI） is not required during the BC stage, which greatly reduce the amount of feedback.
