Wireless Ad Hoc and Sensor Networks

282 Wireless Ad Hoc and Sensor Networks0.8Energy efficiencyEnergy-efficiency (Kbits/Joule)0.70.60.50.40.30.2PDP0.1Modified RBAR00 200 400 600 800 1000 1200 1400Per-flow rate (Kbps)FIGURE 6.25Data transmitted per joule for varying per flow rate.consumption and decreases the end-to-end throughput. The proposedscheme achieves up to 131% higher energy-efficiency than the modifiedRBAR protocol.6.11 Hardware Implementation of DPCImplementation of novel wireless network protocols is traditionally evaluatedthrough the use of network simulators such as NS2, OPNET, orMATLAB (Zawodniok and Jagannathan 2004, Holland et al. 2001, Kamermanand Monteban 1997). Although simulations provide a basis for comparisonof protocol performances on a large scale, they lack the ability toevaluate the protocol against hardware constraints. Additionally, suchapproaches provide necessary feedback of hardware redesign to meet theneeds of the protocol. In fact, very few protocols are implemented inhardware because it is quite difficult to access and modify the physicallayer. Therefore, in this work, a hardware implementation is shown forthe distributed adaptive power control (DAPC) protocol or, simply, DPCprotocol. Though this is applied to an ad hoc type network, the idea canbe demonstrated for cellular networks, wireless sensor networks, andRFID networks.In wireless systems and networks, the radio channel can be highly unpredictableand can fundamentally limit the performance of any wireless communicationsystem. Channel uncertainties such as path loss, shadowing,