Effects of simulcasting on the performance of multi-hop wireless local area networks

Indoor Wireless Local Area Networks (WLANs) enable un-tethering of computers and thus facilitate node mobility. This adds a new set of networking benefits but also creates networking issues that do not exist in wired networks. Signals in wireless channels are susceptible to co-channel interference and suffer from attenuation within the medium. As a result, reliable node connectivity only extends out to a relatively short distance which is determined by available node transmit power. At the network laver WLANs present a time-varying topology to network routers; in some cases sections of a network may become disjoint from others. Several approaches have been proposed and implemented to deal with these problems. In general these tend to focus on specific layers of the network, and in many cases require variable transmit power capability at the network nodes.; We propose a new mode of operation which addresses connectivity in ad-hoc WLANs without requiring variable transmit power capability in node transceivers. These goals are achieved by merging (at the physical layer) simultaneous packet transmissions from multiple transmitting nodes, a technique called simulcasting.; A framework for modeling simulcasting is developed and is used to quantify the performance of simulcast networks. This model predicts improved connectivity and reduced delay under certain conditions. Using a network simulation package, we adapt a set of reference protocols to achieve simulcasting and study some aspects of performance under this mode of operation. In addition, this adaptation identifies implementation issues in a real-world networking environment. Suggestions for modification of the reference components for improved performance in this mode of operation are presented.; The proposed technique enables a new way to achieve connectivity or reliable transmission of high priority traffic in ad-hoc WLANs. Data rates at which the simulcasting technique is applicable scale with device technology, thus providing a path for increased utilization as technology evolves.