Energy Efficient Packet Size Optimization for Wireless Ad Hoc Networks

PhDEnergy efficiency is crucial for ad hoc networks because of limited energy stored in the battery. Recharging the nodes frequently is sometimes not possible. Therefore, proper energy utilization is paramount. One possible solution of increasing energy efficiency is to optimize the transmitted packet size. But, we claim that only optimal packet size can not boost the energy efficiency in the noisy channel due to high packet loss rate and overhead. Hence, to reduce the overhead size and packet loss, compression and Forward Error Correction (FEC) code are used as remedy. However, every method has its own cost. For compression and FEC, the costs are computation energy cost and extra processing time. Therefore, to estimate the energy-optimize packet size with FEC or compression, processing energy cost and delay need to be considered for precise estimation. Otherwise, for delay sensitive real time applications (such as: VoIP, multimedia) over ad hoc network, energy efficient optimal packet size can be overestimated. We will investigate without degrading the Quality of Service (QoS) with these two different techniques FEC and compression, how much energy efficiency can be achieved by using the energy efficient optimal packet size for different scenarios such as: single hop, multi-hop, multiple source congested network etc. This thesis also shows the impact of time variable channel, packet fragmentation, packet collision on the optimal packet size and energy efficiency. Our results show that, for larger packets, error correction improves the energy efficiency in multi-hop networks only for delay tolerant applications. Whereas for smaller packets, compression is more energy efficient most of the cases. For real-time application like VoIP the scope of increasing the energy efficiency by optimizing packet after maintaining all the constraints is very limited. However, it is shown that, in many cases, optimal packet size improves energy efficiency significantly and also reduces the overall packet loss

Reliable data delivery in low energy ad hoc sensor networks

Reliable delivery of data is a classical design goal for reliability-oriented collection routing protocols for ad hoc wireless sensor networks (WSNs). Guaranteed packet delivery performance can be ensured by careful selection of error free links, quick recovery from packet losses, and avoidance of overloaded relay sensor nodes. Due to limited resources of individual senor nodes, there is usually a trade-off between energy spending for packets transmissions and the appropriate level of reliability. Since link failures and packet losses are unavoidable, sensor networks may tolerate a certain level of reliability without significantly affecting packets delivery performance and data aggregation accuracy in favor of efficient energy consumption. However a certain degree of reliability is needed, especially when hop count increases between source sensor nodes and the base station as a single lost packet may result in loss of a large amount of aggregated data along longer hops. An effective solution is to jointly make a trade-off between energy, reliability, cost, and agility while improving packet delivery, maintaining low packet error ratio, minimizing unnecessary packets transmissions, and adaptively reducing control traffic in favor of high success reception ratios of representative data packets. Based on this approach, the proposed routing protocol can achieve moderate energy consumption and high packet delivery ratio even with high link failure rates. The proposed routing protocol was experimentally investigated on a testbed of Crossbow's TelosB motes and proven to be more robust and energy efficient than the current implementation of TinyOS2.x MultihopLQI