Practical Beamforming based on RSSI Measurements using Off-the-shelf Wireless Clients

Sriram Lakshmanan and Raghupathy Sivakumar
GNAN Research Group
School of Electrical and Computer Engineering
Georgia Institute of Technology

Karthik Sundaresan and Sampath Rangarajan
NEC-Laboratories America

The 9th Internet Measurement Conference (IMC 2009), Chicago, Illinois, USA, November 4-6, 2009.


WLANs have become an important last-mile technology for providing internet access within homes and enterprises. In such indoor deployments, the wireless channel suffers from significant multipath scattering and fading that degrades performance. Beamforming is a smart antenna technology that adjusts the transmissions at the transmitter to reenforce the signals received through multiple paths at the receiver. However, doing this requires the accurate estimation of the channel coefficients at the receiver and its knowledge at the transmitter which off-the-shelf WiFi clients are incapable of doing. In this work, we develop a novel procedure that uses Received Signal Strength Indicator (RSSI) measurements at the receiver along with an intelligent estimation methodology at the transmitter to achieve beamforming benefits. Using experiments in an indoor office scenario with commercial WiFi clients, we show that the scheme achieves significant performance improvements across diverse scenarios.

Presentation: [pdf (773KB)]      Full Paper: [pdf (439KB)]