In this paper, a downlink multiple-input-multiple-output (MIMO) non-orthogonal multiple access (N... more In this paper, a downlink multiple-input-multiple-output (MIMO) non-orthogonal multiple access (NOMA) scenario is considered. We investigate a dynamic user clustering problem from a fairness perspective. In order to solve this optimization problem, three sub-optimal algorithms, namely top-down A, top-down B, and bottom up, are proposed to realize different tradeoffs of complexity and throughput of the worst user. In addition, for each given user clustering case, we optimize the power allocation coefficients for the users in each cluster by adopting a bisection search based algorithm. Numerical results show that the proposed algorithms can lower the complexity with an acceptable degradation on throughput compared with the exhaustive search method. It is worth noting that top-down B algorithm can achieve a good tradeoff between complexity and throughput among the three proposed algorithms.
In this paper, the application of simultaneous wireless information and power transfer (SWIPT) to... more In this paper, the application of simultaneous wireless information and power transfer (SWIPT) to non-orthogonal multiple access (NOMA) networks in which users are spatially randomly located is investigated. A new cooperative SWIPT NOMA protocol is proposed, in which near NOMA users that are close to the source act as energy harvesting relays to help far NOMA users. Since the locations of users have a significant impact on the performance, three user selection schemes based on the user distances from the base station are proposed. To characterize the performance of the proposed selection schemes, closed-form expressions for the outage probability and system throughput are derived. These analytical results demonstrate that the use of SWIPT will not jeopardize the diversity gain compared to the conventional NOMA. The proposed results confirm that the opportunistic use of node locations for user selection can achieve low outage probability and deliver superior throughput in comparison to the random selection scheme.
In this paper, a downlink multiple-input-multiple-output (MIMO) non-orthogonal multiple access (N... more In this paper, a downlink multiple-input-multiple-output (MIMO) non-orthogonal multiple access (NOMA) scenario is considered. We investigate a dynamic user clustering problem from a fairness perspective. In order to solve this optimization problem, three sub-optimal algorithms, namely top-down A, top-down B, and bottom up, are proposed to realize different tradeoffs of complexity and throughput of the worst user. In addition, for each given user clustering case, we optimize the power allocation coefficients for the users in each cluster by adopting a bisection search based algorithm. Numerical results show that the proposed algorithms can lower the complexity with an acceptable degradation on throughput compared with the exhaustive search method. It is worth noting that top-down B algorithm can achieve a good tradeoff between complexity and throughput among the three proposed algorithms.
In this paper, the application of simultaneous wireless information and power transfer (SWIPT) to... more In this paper, the application of simultaneous wireless information and power transfer (SWIPT) to non-orthogonal multiple access (NOMA) networks in which users are spatially randomly located is investigated. A new cooperative SWIPT NOMA protocol is proposed, in which near NOMA users that are close to the source act as energy harvesting relays to help far NOMA users. Since the locations of users have a significant impact on the performance, three user selection schemes based on the user distances from the base station are proposed. To characterize the performance of the proposed selection schemes, closed-form expressions for the outage probability and system throughput are derived. These analytical results demonstrate that the use of SWIPT will not jeopardize the diversity gain compared to the conventional NOMA. The proposed results confirm that the opportunistic use of node locations for user selection can achieve low outage probability and deliver superior throughput in comparison to the random selection scheme.
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Papers by Zhiguo Ding
in comparison to the random selection scheme.
in comparison to the random selection scheme.