Measured Throughput in Adaptive V-Blast Systems with Limited Feedback

Abstract

Measured channel data are used to analyze the throughput of V-BLAST systems with transmit selection based on limited feedback from the receiver. The achievable throughput is found to be very dependent on the channel conditions in particular its spatial diversity, which may vary significantly with location indicating the need for adaptivity. The rate at which the subsets must be updated is also investigated and related to the differing channel conditions.

Limited Feedback Precoding in Realistic MIMO Channel Conditions

“…The other was measured on a parallel street with no line-of-sight to the transmitter, and is denoted 'Laurier'. More detail on the topographical characteristics, and the resulting spatial channel responses, can be found in [3]. Fig.…”

“…The variation in channel characteristics over a small geographic region, also observed in [3], dictates the requirement for adaptive transmission. This necessitates the feedback of channel information from the receiver to the transmitter.…”

“…Time-variation of the channel gains, quantisation errors and feedback errors also contribute to imperfect CSI [2]. Furthermore, mobile urban microcellular channels have been seen to exhibit significant spatial correlation [3], which reduces their theoretical capacity as well as rendering some MIMO techniques ineffective.…”

Mobile Channel Prediction with Application to Transmitter Antenna Selection for Alamouti Systems

“…Another set of measurements were taken in the same urban street corridor as the transmitter and are denoted 'Slater'. The different routes consist of varying degrees of spatial correlation as reported in [17]. Laurier exhibits dense scattering Rayleigh envelope characteristics and a relatively small level of spatial correlation and, as a result, little improvement is expected from a matrix predictor.…”