Cross layer design in multi-hop networks with adaptive modulation along with constellation rearrangement

Distributed nature of wireless sensor network raises a number of design challenges, especially when energy-efficiency and Quality of Service requirements are to be taken into consideration. These challenges can only be met by allowing closer cooperation and mutual adaptation between the protocol layers, referred to as a cross-layer design paradigm. In this paper, we explain the operating stages for adaptive sleep with adaptive modulation based on the MAC layer protocol. By using adaptive sleep with adaptive modulation the total time for completing one packet is adaptively reduced. Therefore, not only the transmission time is adapted by adaptive modulation, but also the sleep time is varied by adaptive sleep. A cross-layer, optimization scheme, based on adaptive sleep with adaptive modulation along with constellation rearrangement and power control, is proposed in this paper for minimizing energy cost and enhancing the network longevity. The adaptive sleep with adaptive modulation along with constellation rearrangement algorithm changes the modulation scheme dynamically by using constellation rearrangement while adjusting the node sleep periods and power levels. The paper considers several variations of these schemes and analyzes and compares their performance under various traffic intensity based on extensive computer simulations. Finally the proposed scheme is evaluated through NS2 simulations in terms of throughput.