A new approach to peer-to-peer wireless LANs based on ultra wide band technology
The advent of Ultra Wide Band (UWB) technology offers a unique opportunity to consider a new type of peer-to-peer wireless Local Area Network (LAN) that requires neither access at a peak data rate commensurate with the full bandwidth of the medium nor a conventional medium access protocol. Rather, due to the extraordinarily high bandwidth afforded by UWB, which is typically much greater than the peak bandwidth required by any ad-hoc radio node, one might imagine a network for which pairs of nodes are interconnected by one or more dedicated (non-shared) radio channels created by time, frequency, or code division multiplexing. In this paper, we consider a network containing N ad-hoc nodes and 2N independent radio channels. Starting with (1) an N x N power matrix, where element p (i,j) represents the power needed for a successful transmission from node i to node j including the effects of path loss and shadow fading, and (2) a second N x N traffic matrix where element t (i,j) represents the exogenous traffic originating from node i and destined for node j, we seek to assign radio channels and multi-hop route the traffic between source-destination pairs such that the resulting connectivity pattern and traffic flow minimize the average transmit energy needed to deliver a packet between an arbitrarily chosen pair of nodes. With no medium access protocol needed, collisions cannot occur and retransmissions become unnecessary. Moreover, the available capacity grows with the number of channels created (or, alternatively, as some common set of channels are re-used on a non-interfering basis via sufficient spatial separation). In this fashion, such a UWB ad-hoc network takes on the characteristics of a multi-hop Wavelength-Division Multiplexed (WDM) network well known from the multihop lightwave network art, although the constraints and dynamics are certainly different. Since the optimum connectivity and flow problem is shown to be NP hard, several heuristics are considered and compared. These heuristics seek, first, to establish a "good" connectivity graph, and then to flow the traffic in an optimum fashion. Our results suggest that application of these techniques may provide a distinct wireless LAN advantage achievable only via UWB radio technology, and several opportunities for future work based on this novel approach to ad-hoc local area radio networks are identified and discussed.
wireless lans ultra wideband networks wireless multihop networks wireless peer-to-peer networks