Signalling and detection of parallel Triple Layer Wireless Sensor Networks with M-ary orthogonal modulation

Recent advances in the underlying technologies of WSNs (Wireless Sensor Networks) have led to its use in different applications, in fields as diverse as battlefield applications, temperature control and healthcare. Research in the different aspects of WSNs is therefore in full swing, in both academia and the industry. One of the key constraints that a WSN system poses is the limited energy resource that is available at each sensor node, and in many applications, this energy cannot be replenished. Much of the energy is used in signal detection in a WSN system, the receivers trying to get a reasonably well bit error rate (BER) performance which comes at the cost of increased signal to noise ratio (SNR), that is increased energy usage. To solve this problem, the usage of Walsh codes is suggested, to perform M-ary orthogonal modulation for WSN systems. This method, as is shown through comparative simulations of their BER performances, has several key advantages, the most important one being - compared to traditional modulation schemes, for which higher modulation orders mean worse BER performance, the performance of this scheme, for reasonably high SNRs, gets significantly better and starts attaining the AWGN pattern, which is highly desirable. Different physical parameters (number of nodes, modulation order, diversity combing scheme) have been varied in the simulations, and their effects on the relative performances of the scheme recorded and analysed. A better BER performance compared to traditional modulation schemes was seen and the optimal values for the changed parameters found.