Multiband media access control in impulse-based UWB ad hoc networks

We propose a MAC protocol for use in multihop wireless networks that deploy an underlying UWB ( Ultra Wide Band)-based physical layer. We consider a multiband approach to better utilize the available spectrum, where each transmitter sends longer pulses in one of many narrower frequency bands. The motivation comes from the observation that, in the absence of a sophisticated equalizer, the size of a slot for transmitting a UWB pulse is typically dictated by the delay spread of the channel. Therefore, using a wider frequency band to shorten the transmission time for each pulse does not increase the data rate in proportion to the available bandwidth. Our approach allows data transmissions to be contiguous and practically interference free, and, thus, highly efficient. For practicality, we ensure the conformance of our approach to FCC-imposed emission limits. We evaluate our approach via extensive simulations, and our results demonstrate the significant advantages of our approach over single-band solutions: The throughput increases significantly and the number of collisions decreases considerably. Finally, we analyze the behavior of our MAC protocol in a single-hop setting in terms of its efficiency in utilizing the multiple bands.