Using maximal ratio combining and subcarrier selection to improve the OFDM receiver performance in IEEE802.15.4g

Abstract

In this work we propose the use of Diversity Combining Techniques with frequency despreading as an efficient way to improve the BER performance of the IEEE802.15.4g OFDM mode, as well as, to reduce the SNR required for the Physical Layer Header (PHR) detection. As alternatives, we propose the use of Maximal Ratio Combining (MRC), Subcarrier Selection (SC) or a combination of SC and MRC (SMRC). An ordinary Frequency Despreader (FD) with equalization process already provides a BER performance improvement thanks to the use of Spreading Factors (SF) of 2 χ and 4 χ applied in frequency domain, in the PHR and OFDM data subcarriers for BPSK and QPSK modulations. The simulations results show that, applying these techniques to the frequency spreading, it is possible to achieve an improvement of up to 1.5 dB when compared to the FD. This work is part of a project which aims the implementation of an Integrated Circuit capable of handling the 3 PHYs defined in the IEEE802.15.4g standard, which are based on FSK, O-QPSK and OFDM.