Scheduling and Pre-Conditioning in Multi-User MIMO TDD Systems

Abstract—The downlink transmission in multi-user multipleinput multiple-output (MIMO) systems has been extensively studied from both communication-theoretic and information-theoretic perspectives. Most of these papers assume perfect/imperfect channel knowledge. In general, the problem of channel estimation is studied separately. However, in interference-limited communication systems with high mobility, the problem of channel estimation is tightly coupled with the problem of maximizing throughput of the system. In this paper, scheduling and preconditioning in the presence of reciprocal time-division duplex (TDD) training are considered. In the case of homogeneous users, a scheduling scheme is proposed and an improved lower bound on the sum capacity is derived. The problem of choosing training sequence length to maximize net throughput of the system is also studied. In the case of heterogeneous users, a modified pre-conditioning method is proposed and an optimized pre-conditioning mat...

• Type: Conference
• Year: 2008
• Where: ICC
• Authors: Jubin Jose, Alexei Ashikhmint, Phil Whiting, Sriram Vishwanath
• Keywords: Channel Estimation, Communications, ICC 2008, Perfect/imperfect Channel Knowledge, Scheduling Scheme