A cross-correlation sub-sampling receiver for low power applications in a low SINR environment

Abstract

Wireless sensor networks have recently emerged in a wide range of applications. Many attributes are essential for such networks such as: low cost, small form-factor, limited peak power consumption and the ability to operate in harsh interference scenarios. Most of these networks do not require high data-rates to operate. In this respect, sub-sampling receivers have shown promising results but suffer from noise folding and interference aliasing. In this paper, a sub-sampling receiver in combination with cross-correlation is used to enhance sensitivity and interference robustness while maintaining the sub-sampling advantages. An architecture which uses two different sampling frequencies is proposed. It shows ∼2dB SNR improvement compared to traditional architectures due to cross-correlation and an additional ∼2dB for each doubling of integrations. For a BER of 10 −3 , the required SIR is reduced with 4.5dB, 11.5dB and 14.5dB after using cross-correlation with the same, half and quarter data-rate used respectively. These improvements allow for a lower-power and lower-cost implementation.

Multi-Receiver Cross-Correlation Technique for (B)FSK Radios

“…Such signal detection in FSK discriminators can be improved through XC technique. We demonstrated this in [7], [8] through theoretical calculations and MATLAB simulations.…”

“…As shown in Fig. 1, the C xc samples are generated by repeatedly applying the timewindowed FX-correlator 1 on the incoming receiver signals at the expense of longer measurement time and narrower bandwidth and hence, lower date [2], [3], [7]. For example, reference [2] reported about 12 dB improvement in the SNR at the output of a 2-path cross-correlated receiver by increasing the measurement time by a factor of 273 (273 ≈ 2 8 ; 8 × 1.5 = 12 dB).…”

“…In a BFSK receiver, XC reduces the required SNR at the output of each receiver to demodulate with a certain bit error rate (BER), assumed in this paper to be 10 −3 [7]. Using the mathematical model developed in [8], the SNR benefit of multi-receiver XC in a BFSK system was estimated.…”

“…Recently, we proposed to use XC for data-communication in receivers targeting wireless sensor networks [7], [8]. Among digital modulation schemes, Frequency Shift Keying (FSK) is chosen as it can be demodulated using the energy detection principle in the frequency discriminator [8], [9].…”

“…The SNR improvement due to XC, in general, increases with the number of cross-correlated output samples averaged at the expense of measurement time [2]. Since the measurement time in BFSK receivers is constrained by its data rate, the SNR increment due to XC is limited [7]. To overcome this trade-off, we proposed 'multi-receiver XC' that uses more than two receiver paths (or simply '2-paths') to generate more cross-correlated output samples in a given This work is licensed under a Creative Commons Attribution 4.0 License.…”