In a sensor node, most of the battery energy is consumed by the radio. Therefore, the network’s communication protocol, which determines how the radios are operated, has a decisive influence on battery lifetime.

The previous work on Medium Access Control (MAC) protocols fall into one of two categories: random access schemes and Time Division Multiple Access (TDMA) schemes. Random access schemes all have the advantage of accommodating random access. However, the nodes consume a lot of power because they constantly listen to the channel, overhear the packets that are not destined to them, and may have their transmissions collide. Some of the proposed protocols advanced to reduce these effects by putting the radio in sleep mode achieve power savings up to a factor of four at the cost of considerable increase in hardware or control complexity.

The TDMA schemes on the other hand are more power efficient since they allow the nodes in the network to enter
inactive states until their allocated time slots. However, the previously proposed TDMA schemes do not take advantage of the fact that all sensor data are destined for a single access point and introduce distributed synchronization overhead.

In view of this, a new protocol called PEDAMACS had been proposed for out traffic surveillance networks.