FREQUENCY DIVISION MULTIPLE ACCESS FOR WLAN

摘要

Systems beyond 3G will demand higher throughput for individual users and more flexibility with respect to the exploitation of offered frequency channels. One example is the WLAN standard IEEE 802.11a with modifications for Road Access (IEEE 802.11a/RA), which is proposed by the Intelligent Transportation Society, ITS, for inter-vehicle communication. Different frequency channels at 5.9 GHz are allocated, e.g., for safety-related purposes, road travel information, as well as entertainment. Since those systems operate in a decentralized manner without the need of an infrastructure, a solution for simultaneous operation on several frequencies is needed. For that purpose a novel concept, which is called decentralized FDMA (dFDMA), is introduced. It takes into account the complexity of the hardware, the distributed character of self-organizing networks, and the efficient exploitation of the scarce frequency spectrum. Simulation results indicate an efficient exploitation of all available frequency channels, guaranteeing at the same time the reception of safety-related messages on a pre-defined channel. Moreover, this approach is not restricted to DSRC systems, but also WLAN that should support higher throughput can benefit from this novel concept. It therefore paves the path towards future evolution of WLAN.