On Optimizing Feedback-Rate Allocation for Downlink MIMO-NOMA With Quantized CSIT

Autor: Kritsada Mamat, Wiroonsak Santipach
Jazyk: angličtina
Rok vydání: 2020
Předmět:
Zdroj: IEEE Open Journal of the Communications Society, Vol 1, Pp 1551-1570 (2020)
Druh dokumentu: article
ISSN: 2644-125X
DOI: 10.1109/OJCOMS.2020.3028642
Popis: We consider multiple-input multiple output (MIMO) non-orthogonal multiple access (NOMA) downlink channels with zeroforcing beamforming transmission. The base station has multiple transmit antennas while all mobile devices have single receive antenna. With a limited feedback rate, channel direction information (CDI) needs to be quantized and fed back from mobile users to a base station. Thus, the accuracy of the quantized channel state information at the transmitter (CSIT) will depend on the feedback rate. To increase spectral efficiency, 2 active users in some clusters share the same beamforming vector and thus, will interfere fully with each other. Given a total-feedback rate, we analyze the feedback allocation for clusters with single active user and 2 active users. The objective is to either minimize the maximum outage probability or maximize the minimum rate among all active users in a cell. We show that the proposed feedback allocation is close to the optimum. Some numerical examples show that the resulting rate performance with the proposed feedback allocation is increased by 100% over that with the uniform feedback allocation.
Databáze: Directory of Open Access Journals