Wireless nanosensor networks (WNSNs) which consists of numerous nanosensors, offer a number of promising applications in diverse fields like biomedical, environment, industrial, military etc. The extremely small size and the envisaged application environments in which WNSNs are expected to operate give rise to many issues for reliable wireless communication at nanoscale, which require re-design of the existing macroscale communication protocols. The promising virtues of carrier-less pulse-based modulation techniques, mainly energy efficiency, high reliability etc., make it appropriate for designing WNSNs communication protocols. The performance of four different carrier less modulations for WNSNs, such as PAM, OOK, PPM and BPSK will be compared in this paper. In terms of Bit Error Rate (BER), complexity, energy efficiency and capacity these modulation schemes have different characteristics and exhibit different performance levels. Our study shows that if lower complexity is essential, the best option is to look out for OOK or PPM. PAM has poor performance in terms of energy efficiency and reliability. BPSK will be the first choice if higher power efficiency and robustness against error are the major issues to be considered.

Keywords : WNSN;BER; Pulse based modulation; Complexity;Energy Efficiency.