TY - GEN
T1 - Sum Spectral Efficiency Optimization for Rate Splitting in Downlink MU-MISO
T2 - 2021 IEEE Wireless Communications and Networking Conference Workshops, WCNCW 2021
AU - Park, Jeonghun
AU - Choi, Jinseok
AU - Lee, Namyoon
AU - Shin, Wonjae
AU - Poor, H. Vincent
N1 - Publisher Copyright:
© 2021 IEEE.
PY - 2021/3/29
Y1 - 2021/3/29
N2 - In this paper, we consider a downlink multiple-input multiple-output (MIMO) system, where a rate splitting approach is applied to serve multiple users more efficiently. We formulate a sum spectral efficiency maximization problem with respect to precoders when noisy channel state information is available at the transmitter. Finding even a suboptimal solution is a very challenging task by its non-convexity and non-smoothness. To resolve this challenge, we first approximate the non-smooth minimum function by using a LogSumExp technique, and reformulate the problem as a form of the product of Rayleigh quotients, considering channel estimation error. Then we derive the first-order optimality condition. A key observation of the obtained condition is that it can be cast as a nonlinear eigenvector-dependent eigenvalue problem so that finding a leading eigenvector is equivalent to finding a local optimal solution. To this end, we propose an algorithm inspired by a power iteration method, referred to as a generalized power iteration for rate splitting. Simulation results show that the proposed method enhances the achievable performance when channel acquisition error exists.
AB - In this paper, we consider a downlink multiple-input multiple-output (MIMO) system, where a rate splitting approach is applied to serve multiple users more efficiently. We formulate a sum spectral efficiency maximization problem with respect to precoders when noisy channel state information is available at the transmitter. Finding even a suboptimal solution is a very challenging task by its non-convexity and non-smoothness. To resolve this challenge, we first approximate the non-smooth minimum function by using a LogSumExp technique, and reformulate the problem as a form of the product of Rayleigh quotients, considering channel estimation error. Then we derive the first-order optimality condition. A key observation of the obtained condition is that it can be cast as a nonlinear eigenvector-dependent eigenvalue problem so that finding a leading eigenvector is equivalent to finding a local optimal solution. To this end, we propose an algorithm inspired by a power iteration method, referred to as a generalized power iteration for rate splitting. Simulation results show that the proposed method enhances the achievable performance when channel acquisition error exists.
UR - http://www.scopus.com/inward/record.url?scp=85106005152&partnerID=8YFLogxK
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U2 - 10.1109/WCNCW49093.2021.9420033
DO - 10.1109/WCNCW49093.2021.9420033
M3 - Conference contribution
AN - SCOPUS:85106005152
T3 - 2021 IEEE Wireless Communications and Networking Conference Workshops, WCNCW 2021
BT - 2021 IEEE Wireless Communications and Networking Conference Workshops, WCNCW 2021
PB - Institute of Electrical and Electronics Engineers Inc.
Y2 - 29 March 2021
ER -