Behind-the-scenes of IEEE 802.11a based multi-radio mesh networks: a measurement driven evaluation of inter-channel interference

摘要

To successfully develop IEEE 802.11a based wirelessmesh network solutions that can achieve the reliability andcapacities required to offer high quality triple play servicesthe use of multiple radios in each mesh node is essential.Unfortunately, the co-location of multiple antennas in a singledevice leads to a number of interference problems. In this paperthe impact of non-overlapping channel interference in IEEE802.11a based multi-radio nodes is investigated. A detailedexplanation of the performance decreases and their relationto radio settings is presented. The primary contribution ofthis paper is the discovery of a channel interference effectwhich is present over the entire 802.11a frequency space.This interference appears if two radios are located less than50 cm from each other and both are attempting to operateas usual. The results were obtained by conducting experimentsin a well planned testbed to produce reliable andreproducible results. The presented results incorporate multipleparameters including transmission power, modulation codingscheme, channel separation and physical layer effects such asadjacent channel interference, carrier sensing, retransmissionsand packet distortion.