It is well known that the use of traditional transmit beamforming at a base station (BS) to manage interference in serving multiple users is effective only when the number of users is less than the number of transmit antennas at the BS. Nonorthogonal multiple access (NOMA) can improve the throughput of users with poorer channel conditions by compromising their own privacy, because other users with better channel conditions can decode the information of users with poorer channel conditions. NOMA still prefers that the number of users is less than the number of antennas at the BS transmitter. This letter resolves such issues by allocating separate fractional time slots for serving users with similar channel conditions. This enables the BS to serve more users within a time unit while the privacy of each user is preserved. The fractional times and beamforming vectors are jointly optimized to maximize the system's throughput. An efficient path-following algorithm, which invokes a simple convex quadratic program at each iteration, is proposed for the solution of this challenging optimization problem. Numerical results confirm its versatility.
Bibliographical noteKAUST Repository Item: Exported on 2021-04-06
Acknowledged KAUST grant number(s): OSR-2016-CRG5-2958-0
Acknowledgements: This work was supported in part by a National Research Foundation of Korea (NRF) grant funded by the Korean government (MSIT)
(No. NRF-2017R1A5A1015596), in part by the Basic Science Research Program through the NRF funded by the Ministry of Education
(No. 2017R1D1A1B03030436), in part by a U.K. Royal Academy of Engineering Research Fellowship under Grant RF1415/14/22 and by the U.K.Engineering and Physical Sciences Research Council (EPSRC) under Grant EP/P019374/1, and in part by KAUST Grant No. OSR-2016-CRG5-2958-0 and U.S. National Science Foundation Grant ECCS-1647198. The associate editor coordinating the review of this letter and approving it for publication was N. Tran.
This publication acknowledges KAUST support, but has no KAUST affiliated authors.
ASJC Scopus subject areas
- Modeling and Simulation
- Computer Science Applications
- Electrical and Electronic Engineering