Using Multiple Chains in Cross-Correlation Receivers to Improve Sensitivity

Cross-correlation can be used in energy detection applications, such as spectrum analyzers, but also frequency shift keying (FSK) receivers, to improve noise suppression. To achieve higher signal-to-noise ratio (SNR), integration in time may be used, but could make it rather slow for communication purposes. In order to achieve better data-rates in low SNR conditions, we propose to use multiple chains instead of the traditional two chains. In this paper, we show an analysis of the SNR improvement and the power consumption penalty for BFSK modulation when using more chains. It shows that for low noise correlation between the chains, the improvement in sensitivity is proportional to the number of chains. Also, we develop a figure-of-merit to evaluate the optimum number of chains for different parameters of the receiver design. Furthermore, two examples from literature are analyzed. At their optimum number of chains, they both show $\sim$6dB improvement in sensitivity with similar or even better figure-of- merit.