| The method of pulse discrimination and rate adaptation techniques have been shown to yield significant performance improvement for Impulse Radio (IR) networks in powerful pulse interfering environments. In this work, we present a technique where receivers autonomously estimate the interference environment on a packet time scale. We show how the combination of these techniques significantly reduces transponder complexity, network interference, average transmitted power, and improves system throughput. We illustrate these advantages by developing a method for estimating packet transmission failure in uncoordinated, unslotted ALOHA Ultra Wideband (UWB) networks. Similar analysis of failure rates in narrow band systems are frequently based on the assured destruction for partial packet overlap. Data corruption from packet collisions in IR is less likely given the low pulse transmission duty cycle and spreading redundancy, making destruction based on partial packet overlap much less certain.
We adapt methods developed for packet failure in narrowband systems to the unique characteristics of IR to illustrate the advantages of pulse discrimination and rate adaptation. The resulting analysis shows good agreement with simulations of packet interference resulting from individual chip collisions. Optimum chip/bit spreading rates based on known interferers at the beginning of the packet are derived from this analysis and are used as part of an adaptive rate protocol. We also show how simple pulse counters can be used for estimating the number of interferes with only minor performance loss compared to the known interferer case. Both methods result in an optimized throughput with an overall reduction in pulse density as compared to more common fixed chip/bit rate methods.
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