System performance of Single-User MIMO in LTE downlink

Orthogonal Frequency-Division Multiplexing is a multi-carrier modulation scheme, where information symbols are transmitted in parallel over the channel by using a set of subcarriers. One of the main advantages is increased robustness against frequency selective fading and narrowband interference. In this paper we study the performance of two dual-codeword Single-User Multiple-Input Multiple-Output (SU-MIMO) schemes, i.e. per antenna rate control (PARC) and Precoded MIMO (PREC), in an OFDM deployment. For PARC we consider 2times2 and 4times4 antenna configurations and for Precoded MIMO 4times4 antenna configuration only. Our study is performed with a downlink Long Term Evolution (LTE) system simulator. The results indicate that in terms of average sector throughput the four-stream schemes outperform the dual-stream scheme by approximately 75-90%. Moreover, the four-stream schemes have significant coverage gain compared to the dual-stream scheme. When comparing the four-stream schemes against each other, the relative gain of the precoded scheme in average sector throughput is about 5-6%. From coverage perspective, PREC is about 13-20% better than PARC.