Advancements in digital circuitry, wireless transceivers and microelectro- mechanical systems have paved the way for the development of integrated sensor systems operating inside the unlicensed spread spectrum. Inch scale sensors can work unattended for long periods of time while energy harvesting techniques can extend their lifetime. A main challenge in these networks is energy efficiency. This thesis presents the design, implementation and evaluation of two routing protocols for a variety of applications with the main focus on energy efficiency.

After reviewing the theory of opportunistic routing and opportunistic spectrum access, a scalable solution that combines the advantages of these approaches is presented. The CNOR protocol explores the spectrum availability while it uses opportunistic routing to take advantage of the broadcast nature of wireless communications. CNOR is designed for WSNs with limited power resources.

Next, ECUR protocol for Self-powered WSNs is introduced. ECUR uses a novel prioritization metric for the neighbour nodes. ECUR protocol balances the residual energy level in a node with the packet advancement. Also, it takes into consideration the limited memory and processing capacity of the nodes.

Lastly, the system implementation of the protocols is presented. Both protocols are examined through a novel Self-Powered Wireless Sensor Network testbed that was developed.