ZigBee is based on IEEE 802.15.4 which specifies the physical layer and medium access control (MAC) for low-cost and low-power LR-WPAN. The technology can be applied in intelligent key, A/C operation and steering wheel inside vehicles. There are two types of devices in ZigBee, FFD and RFD. A FFD can communicate with RFDs and other FFDs, while a RFD can only communicate with a FFD. In ZigBee physical layer, it follows IEEE 802.15.4 standard and operates in unlicensed RF worldwide (2.4GHz global, 915MHz Americas or 868 MHz Europe). A superframe contained an active portion and an inactive portion is used in the MAC layer of ZigBee. The active portion includes CAP and CFP. In the inactive partition, the coordinator can enter sleep mode to save its power. Three main topologies of ZigBee are star, mesh, and tree. However, ZigBee is successfully produced into a low-cost controller applied for automotive applications, including vehicle control and status monitoring. According to the forecast of ON World in 2005 (ON WORLD, 2009), the deployed wireless sensing network nodes will increase to 127 million in 2010 from 1.2 million in 2005. It can be applied in home automation, battlefield surveillance, health care applications and vehicular environments. A wireless sensor network (WSN) constitutes a lot of wireless sensing nodes. In addition, a node in WSN consists of one or more sensors, a radio transceiver, and a microcontroller. The sensor can be used for sensing temperature, pressure, sound, vibration, motion or position, etc. to collect status from devices or environments. The transceiver is used to relay the information of the collected status computed by the microcontroller to a center node, called a gateway or sink. Therefore, a WSN belongs to one type of wireless ad-hoc networks. However, the nodes in a WSN are usually smaller than that in traditional wireless ad-hoc networks regarding node size, computing power, memory size, and transmission rage. In other words, the transmission ability, computing power, and memory size of WSN nodes are limited.
Low-cost routing in selfish and rational wireless ad hoc networks
