Open AccessOptimized BD‐ZF Precoder for Multiuser MIMO‐VFDM Cognitive Transmission
Author(s) -
Yao Rugui,
Xu Juan,
Li Geng,
Wang Ling
Publication year - 2016
Publication title -
etri journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.295
H-Index - 46
eISSN - 2233-7326
pISSN - 1225-6463
DOI - 10.4218/etrij.16.0115.0023
Subject(s) - mimo , throughput , transmission (telecommunications) , computer science , interference (communication) , algorithm , subspace topology , channel (broadcasting) , topology (electrical circuits) , mathematics , computer network , telecommunications , wireless , combinatorics , artificial intelligence
In this paper, we study an optimized block‐diagonal zero‐forcing (BD‐ZF) precoder in a two‐tiered cognitive network consisting of a macro cell (MC) and a small cell (SC). By exploiting multiuser multiple‐input and multiple‐output Vandermonde‐subspace frequency‐division multiplexing (VFDM) transmission, a cognitive SC can coexist with an MC. We first devise a cross‐tier precoder based on the idea of VFDM to cancel the interference from the SC to the MC. Then, we propose an optimized BD‐ZF intra‐tier precoder (ITP) to suppress multiuser interference and maximize the throughput in the SC. In the case where the dimension of a provided null space is larger than that required by the BD‐ZF ITP, the optimized BD‐ZF ITP can collect all limited channel gain by optimizing rotating and selecting matrices. Otherwise, the optimized BD‐ZF ITP is validated to be equivalent to the conventional BD‐ZF ITP in terms of throughput. Numerical results are presented to demonstrate the throughput improvement of the proposed optimized BD‐ZF ITP and to discover the impact of imperfect channel state information.