Effect of Intra-Subframe Frequency Hopping on Closed-Loop Type Transmit Diversity with Precoding for Uplink DFT-Precoded OFDMA

This paper proposes applying intra-subframe frequency hopping (FH) to closed-loop (CL) type transmit diversity using codebook based precoding for a shared channel carrying user traffic data in the uplink discrete Fourier transform (DFT)-precoded Orthogonal Frequency Division Multiple Access (OFDMA). In the paper, we present two types of precoding schemes associated with intra-subframe FH: individual precoding vector selection between 2 slots where a 1-msec subframe comprises 2 slots among the reduced precoding codebooks, and common precoding vector selection between 2 slots. We investigate the effect of intra-subframe FH on the CL type transmit diversity with precoding in terms of the block error rate (BLER) performance while maintaining the same number of feedback bits required for notification of the selected precoding vector as that for CL type precoding based transmit diversity without FH. Computer simulation results show that CL type transmit diversity with precoding using intra-subframe FH is very effective in reducing the required average received signal-to-noise power ratio (SNR) when the fading maximum Doppler frequency, fD, is higher than approximately 50 Hz both for 2- and 4-antenna transmission in the uplink DFT-precoded OFDMA.