Energy-Aware and Time-Critical Geo-Routing in Wireless Sensor Networks

Abstract

Volunteer forwarding, as an emerging routing idea for large scale, location-aware wireless sensor networks, has recently received significant attention. However, several critical research issues raised by volunteer forwarding, including communication collisions, communication voids, and time-critical routing, have not been well addressed by the existing work. In this paper, we propose a priority-based stateless geo-routing (PSGR) protocol that addresses these issues. Based on PSGR, sensor nodes are able to locally determine their priority to serve as the next relay node using dynamically estimated network density. This effectively suppresses potential communication collisions without prolonging routing delays. PSGR also overcomes the communication void problem using two alternative stateless schemes, rebroadcast and bypass. Meanwhile, PSGR supports routing of time-critical packets with different deadline requirements at no extra communication cost. Additionally, we analyze the energy consumption and the delivery rate of PSGR as functions of the transmission range. Finally, an extensive performance evaluation has been conducted to compare PSGR with competing protocols, including GeRaf, IGF, GPSR, flooding, and MSPEED. Simulation results show that PSGR exhibits superior performance in terms of energy consumption, routing latency, and delivery rate, and soundly outperforms all of the compared protocols.

Keywords:

• Wireless Sensor Networks
• Geo-routing Protocols
• Location Awareness
• Communication Void Problem
• Communication Collisions

Wang-Chien Lee and Yingqi Xu were supported in part by National Science Foundation grant IIS-0328881 and National Science Foundation grant CNS-0626709.

Notes

¹The maximum number of rebroadcasts is to conserve the energy in case that a permanent void exists in the network.

²The sweeping rule is also called the right/left hand rule in [6, 20]. The rule states that, by sweeping the edge between the current holder and the previous holder with certain sweeping direction (counter-clockwise or clockwise), the first swept node is chosen as the next hop for bypass.

³The scheduling policies may require synchronization between the relay nodes and the source node, which can be achieved by existing algorithms [9, 26].

⁴For the sake of simplicity, we do not consider the routing timeliness requirement in the following analysis, and leave it for future work.

⁵In IEEE 802.11, the colliding broadcast packets are simply discarded without retransmission.

⁶Note that due to the movement of sensor nodes, all void regions are dynamically formed.

⁷The error introduced to the location of a sensor node remains the same, as long as the sensor node does not move.