MMSE Transmit Optimization for Multiuser Multiple-Input Single-Output Broadcasting Channels in Cognitive Radio Networks

• Huijin Cao,
• Yanhui Lu,
• Jun Cai,

Vol. 7, No. 9, September 29, 2013
10.3837/tiis.2013.09.003, Download Paper (Free):

• cognitive radio
• broadcast channel
• multiple access channel
• multi-user MISO
• MMSE.

Abstract

In this paper, we address the problem of linear minimum mean-squared error (MMSE) transmitter design for the cognitive radio (CR) multi-user multiple-input single-output (MU-MISO) broadcasting channel (BC), where the cognitive users are subject to not only a sum power constraint, but also a interference power constraint. Evidently, this multi-constraint problem renders it difficult to solve. To overcome this difficulty, we firstly transform it into its equivalent formulation with a single constraint. Then by utilizing BC-MAC duality, the problem of BC transmitter design can be solved by focusing on a dual MAC problem, which is easier to deal with due to its convexity property. Finally we propose an efficient two-level iterative algorithm to search the optimal solution. Our simulation results are provided to corroborate the effectiveness of the proposed algorithm and show that this proposed CR MMSE-based scheme achieves a suboptimal sum-rate performance compared to the optimal DPC-based algorithm with less computational complexity.

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