Simulcast packet transmission in distributed wireless networks

In most communication systems, the physical-layer communications from a radio are either unicast, meaning intended for one neighbor radio, or broadcast, meaning intended for all of a radio's neighbors. The implication is that most transmissions are either adapted to a specific radio's capability or designed for the worst radio channel among a group of radios. Unequal error-protection modulation or coding schemes can be used to transmit multiple messages simultaneously, where some messages can only be received by radios with better link conditions. When used in this application, such a transmission scheme is referred to as multicast signaling or simulcasting. Simulcasting has been previously shown to improve link efficiency for a scenario in which a single transmitter communicates with multiple receivers. In this paper, we evaluate the performance of simulcasting in a distributed, or ad hoc, wireless network. Performance results are presented for different channel and mobility models, as well as for different medium-access control parameters. The results indicate that simulcasting can improve the throughput in ad hoc wireless networks.