Ultra Wide Band (UWB) technology offers a promis- ing high capacity solution for wireless networks with short-range links. However, MAC and higher-layer ad hoc network protocols that exploit the UWB technology are yet to mature. In this paper, we propose a MAC protocol for use in multi-hop wireless networks that deploy an underlying UWB based physical layer. We adopt a multi-band approach wherein we divide the available UWB band- width into multiple simultaneously usable bands. The motivation comes from the following observation: in the absence of a sophis- ticated equalizer, the size of a slot for transmitting a UWB pulse is typically dictated by the delay spread of the channel. There- fore, using a wider frequency band to shorten the transmission time for each pulse may not increase the data rate in proportion to the available bandwidth. Thus, we consider a multi-band ap- proach to better utilize the available spectrum, where each trans- mitter sends longer pulses in one of many narrower frequency bands. Unlike previous single hopped schemes that rely on time- hopping, our approach allows data transmissions to be contigu- ous, and thus, highly efficient. The approach also ensures that data communications are practically interference free and are only subject to thermal noise effects. To ensure that our proposed ap- proach is tightly knit with the underlying physical layer, we discuss physical-layer dependencies and the conformance of our approach to FCC-imposed emission limits. We evaluate our approach via ex- tensive simulations. Our simulation results demonstrate the signif- icant advantages of our approach over single-band solutions: the throughput increases significantly, and the number of collisions decreases considerably.
['Ioannis Broustis', 'Srikanth V. Krishnamurthy', 'Michalis Faloutsos', 'Mart L. Molle', 'Jeffrey R. Foerster']
A multiband mac protocol for impulse-based UWB ad hoc networks