UBC Theses and Dissertations
Bluetooth receiver design based on Laurent’s decomposition Ibrahim, Noha
Bluetooth is a widely used communication standard for wireless personal area networks (WPAN). The Bluetooth transmit signal is Gaussian frequency shift keying (GFSK) modulated. GFSK belongs to the family of continuous-phase modulation (CPM) signals, which achieve a good trade-off between power and bandwidth efficiency and, due to constant envelope modulation, allow for low-complexity transmitter implementation. Bluetooth devices often employ a simple discriminator receiver, which is highly suboptimum in terms of power efficiency compared to the optimum receiver. Other approaches proposed in the literature consider trellis-based detection using the Viterbi or forward-backward algorithm. These schemes achieve significant performance improvements over discriminator detectors while entailing a considerably higher computational complexity. The main challenges faced when designing a Bluetooth sequence detector is the varying modulation index, which results in a varying trellis structure, and the time-variant channel phase, making coherent detection which assumes perfect channel phase estimation an almost impossible task. In this research work, we present a receiver design for Bluetooth transmission based on Laurent's decomposition of the Bluetooth transmit signal. The main features of this receiver are its low-complexity compared to alternative solutions, its excellent performance close to the theoretical limit, and its high robustness against frequency offsets, phase noise, and modulation index variations, which are characteristic for lowcost Bluetooth devices. In particular, we show that the devised noncoherent decision feedback equalization receiver achieves a similar performance as a recently proposed 2-state noncoherent sequence detector, while it is advantageous in terms of complexity. The new receiver design is therefore highly attractive for a practical implementation.
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