The Internet has become ubiquitous and there has been tremendous growth in wireless communications in recent years. Many wireless communication techniques are commercially available, such as the Wireless LAN, Bluetooth, GSM, GPRS and CDMA. Because an all-IP network will be a trend, access to the Internet via wireless communication devices has become an important issue.
To reduce power consumption and reuse the limited radio spectrum resources, a cellular network was formed. Cell size is one of the factors in the channel reuse rate. Basically, the channel reuse rate in a smaller cell size is higher than the channel reuse rate in a bigger cell size. Micro-mobility is therefore the inevitable direction for future mobile systems. Frequent and fast movements usually characterize micro-mobility. A cellular architecture would then present a challenge to the frequent handover procedures for a smaller cell size would usually induce a higher handoff frequency.
In addition to cellular networks, the ad-hoc network is another network architecture for wireless networks. The ad-hoc network is a non-infrastructure architecture; in which nodes can access services from one another regardless where they are. An excellent routing protocol is crucial for an ad-hoc networking to function at high performance. The main difference between a cellular environment and ad-hoc network is that the ad-hoc method has no fixed infrastructure, allowing nodes to communicate with one another at any time and anywhere.
We have mentioned that micro-mobility in a cellular environment would introduce a greater number of handoffs than before. The handoff probability drives the mobile IP mechanism due to signal changes. Using the Mobile IP mechanism, handoff breaking would take place within a micro-mobility environment. Therefore, in this paper, some handoff strategies that take the advantage of the ad-hoc mechanism to improve the handoff performance are investigated.