An Energy Efficient MAC Protocol for Densely Deployed Wireless Sensor Networks

Recent advancements in developing the low power micro sensors have attracted the researchers around the globe to build Wireless Sensor Networks (WSN) for various fields of interests. A typical architecture of a WSN consists of many sensing devices that are capable of probing the surroundings and deliver the collected data, using a radio, to a command center. The lifetime of a WSN mostly depends on the batteries that are very hard to replace or recharge. The major sources of energy wastage are collision, overhearing, packet overhead and idle listening. An efficient Medium Access Control (MAC) protocol can save significant amount of energy. In many MAC protocols such as IEEE 802.11 or CDMA (IS-95) nodes must listen to the channel to receive possible traffic while TDMA allows nodes to sleep in the intermediate timeslots. A combination of TDMA and CDMA can greatly improve the efficiencies of WSN. An interesting use of WSN is a Wireless Navigation System for Riverine Transportations (WNSRT) that may contain a large number of densely deployed sensors placed all over the riverways. This system should posses Low Latency, Scalability, Energy Efficiency, and Spectrum Efficiency. The TD-SCDMA based architecture proposed in this paper can optimize these requirements and reduce the significant infrastructure costs.