chapter  3
50 Pages

Adaptive Modulation, Adaptive Power Allocation, and Adaptive Medium Access

This chapter investigates the physical (PHY) layer characteristics and implementation issues of adaptive modulation (AM) and adaptive sleep (AS) with adaptive modulation (ASAM) for energy-constrained wireless sensor networks. It investigates the network energy consumption by considering data rate and transmit power. The chapter presents the literature review of link adaptation and feedback communication systems. It explains the fundamentals of different adaptive techniques. The chapter describes the ASAM algorithm and adaptive power allocation policy. It presents the simulation results. The chapter considers two techniques of power adaptation—power allocation and adaptive sleep. AM or link adaptation allows for dynamic adjustment of the communication systems, according to the characteristics of the time-varying channel. Adaptive modulation techniques dynamically change the data rates according to the channel conditions. Adaptive sleep technique has been proposed so that node sleep time can be adjusted based on current fading conditions.