Fergie's Tech Blog

Packet Loss Problems Surface in Wi-Fi Networks

Loring Wirbel writes on EE Times:

Development engineers at VeriWave Inc. have discovered an unexpected problem with the physical layer convergence procedure (PLCP) in existing 802.11 Wi-Fi networks. The glitch could have practical implications in voice-over-Wi-Fi and Radius authentication in wireless networks, the engineers said.

VeriWave CTO Tom Alexander discovered the problem while working for the 802.11 Task Group on test generation and wireless performance. "You could maybe say it should have been foreseen with only a single bit of parity in the PLCP header," said Eran Karoly, vice president of marketing at VeriWave. "At first, it might seem of interest only to geeks, but this is a problem that could affect voice quality of Wi-Fi more than delay or jitter, and also create some end-user problems in network authentication."

PLCP headers are common convergence protocols used in IP, ATM and wireless networks. In the case of 802.11, a single parity bit in the header can allow header corruption to take place as packet rate and length fields are computed. Typical frame errors can lead to packets being retransmitted, but in PLCP corruption, the network may remain blind to the problem, and the packet is simply dropped.

posted by Fergie @ 11/09/2006 03:56:00 PM