Impact of space-time block codes on 802.11 network throughput

Abstract — Space-Time Block Codes (STBC) represent a recent, exciting development in the field of physical layer (PHY) data transmission. By employing more than one antenna at the transmitter, and by properly coding data across the transmit antennas, STBC-equipped PHYs promise increased data rates with minimal decoding complexity at the receiver. This article presents a comprehensive study of how the STBC gains at the PHY translate to significant network performance improvement in 802.11a Wireless LANs. We base our study on a detailed, across-all-layers, simulation of an 802.11a system; we have extended the ns simulator with an implementation of the 802.11a PHY, which allows us to assess the impact of STBC not only at the PHY layer, but at the higher layers as well. An extensive set of simulations illustrates the merits of STBC, and sheds light on how performance can be improved for TCP traffic. Essentially, STBC presents to TCP a “smoother” wireless channel; the latter phenomenon is corroborated by a brief theoretical analysis as well.