IEEE 802.15.4a-based Impulse Radio Ultra-Wideband system with joint channel equalization and decoding

Abstract

The paper proposes a modification of the hybrid PPM/BPSK modulation described in the IEEE 802.15.4a Impulse Radio Ultra-Wideband (IR-UWB) Physical Layer (PHY) specifications. Proposed modulation is intended for reception by the coherent IEEE 802.15.4a IR-UWB PHY receivers; it considerably reduces the distance between PPM positions compared to the IEEE 802.15.4a IR-UWB PHY specifications. In this way, proposed modulation considerably reduces the time that the receiver needs to be turned on during the symbol period, i.e. it reduces receiver duty-cycle and hence it reduces receiver power consumption. However, due to a large Inter-Position Interference (IPI) that this small PPM distance inflicts, a need for equalization arises. The paper shows how the Viterbi algorithm used for the decoding of the IEEE 802.15.4a IR-UWB PHY systematic convolutional code can be exploited for simultaneous equalization and decoding by changing its metric. As numerical simulations show, this decoding and equalization method results in relatively small performance loss compared with the case when IPI is negligible.