IEEE 802.11 Contention-Based Medium Access for Multiple Channels

Inhalt:
The IEEE 802.11(TM) medium access protocol is based on carrier sensing, and contention, i.e., collision avoidance of frame transmissions from different radio stations. This contention-based protocol is discussed in this paper and extended for the usage in multiple parallel frequency channels, in which a multi-channel station groups channels for increasing its own achievable throughput. We discuss a capture effect that occurs if single-channel and multi-channel stations operate in parallel. Methods to enable multi-channel stations and single-channel stations to coexist by sending out redundant preambles, frame headers, and control frames on each individual frequency channel before the channels are grouped, are studied. Single-channel “legacy” stations operating in one of the grouped channels can then detect that the data frame that follows is not intended for them. We provide a first analytical evaluation for the expected efficiency of the proposed modifications.