• Alternative title-1: Effective Multiuser MIMO Schemes for Wireless Cellular Networks
  • Alternative title-2: Digital feedback beamforming systems for wireless networks
  • Author: J. S. Kim, et al.

Abstract Edit

In this thesis, we discuss multiple-input and multiple-output (MIMO) antenna technology, which can enhance the throughput performance of downlink cellular systems without using more bandwidth and more power. MIMO can improve spectral efficiency with respect to number of the equipped multiple antennas. This paper focus on a fundamental limit of a single user MIMO (SU-MIMO) system in cellular downlink systems, which recently requires high rate throughput for high quality multimedia mobile services. The fundamental limit of a SU-MIMO system is that in the downlink cellular system, the performance of MIMO is limited by the number of multiple receiver antennas at the mobile terminals although the number of multiple transmit antennas at the base station is large. It is impractical for hand-held mobile terminals to mandate more than two receiver antennas because of its physical size and additional RF cost especially in the cellular carrier frequency bands of around 1 to 2GHz.

Multiuser MIMO (MU-MIMO) can be a solution to overcome the limit of SU-MIMO systems since multiple receiver antennas is not necessary in MU-MIMO systems. If the downlink channel information is available at the transmitter, the MU-MIMO systems can improve the system spectral efficiency even with a single receiver antennas at the mobile. The MU-MIMO systems remove spatial interference signals, which have to be canceled by multiple receiver antennas at the mobile terminals in MIMO systems, by precoding techniques at the transmitter.

In practical systems non perfect precoding algorithms are applied as the perfect channel state information is unavailable at the transmitter. The limited uplink feedback resource results in the partial channel state information feedback. The non perfect precoding algorithms can reduce computational complexity at the transmitter. Thus, in this paper we investigate three types of precoding algorithms for limited feedback signaling according to the complexity level and then, propose high performance and low cost feedback signaling strategies, for each precoding algorithm.

Introduction Edit

Main article: LFMIMOSDMA-Introduction

Common System Model Edit

Main article: LFMIMOSDMA-Common System Model

Conclusion Edit