Energy and spectral tradeoff for uncoded system with MQAM modulation

International audienceThe energy consumption of wireless communicating devices as well as their autonomy are two important factors in energy constrained system such as Wireless Sensor Networks (WSNs). The spectral efficiency is another important metric. The main goal is to study the trade-off between the energy consumption of the system and it’s spectral efficiency when varying system parameters. In this paper, an uncoded system using M-ary Quadrature Amplitude Modulation (MQAM) in which the spectral efficiency is assumed proportional to its bandwidth efficiency is used. In order to find the balance between spectral and energy requirements, the considered system parameters are studied. First, a general and comprehensive power model for both transmitter and receiver is developed. Next, by considering Additive White Gaussian Noise (AWGN) channel for point-to-point communication, the total energy consumption is evaluated. A new approximation for the Bit Error Rate (BER) is adopted. Then, the effect of communication distance and the occupied signal bandwidth on the optimum spectral efficiency are studied. We show the influence of varying the circuit consumption. For a fixed BER, we demonstrate that for each of those parameters, an optimum spectral efficiency can be found