Mobile controlled handoff by using dyanamic channel assignement

Abstract

In cellular networks, blocking occurs when a base station has no free channel to allocate to a mobile user. One distinguishes between two kinds of blocking, the first is called new call blocking and refers to blocking of new calls, and the second is called handoff blocking and refers to blocking of ongoing calls due to the mobility of the users. There are many methods of allocating a channel upon a new call arrival or handoff attempt. A good channel allocation is the one that yields high spectral efficiency for a specified grade of service (including link quality, probability of new call blocking, and the probability of forced terminations) and given degree of computational complexity It also keeps the planned cell boundaries intact, allocates a channel to MS quickly, maintains the best speech quality for the MS at any instant, and relives undesired network congestions. In this paper a simple and dynamic mobile controlled handoff based on quality of service is proposed which initiates a handoff procedure when RSS (Received signal strength) from serving BS falls below the threshold level. By using DCA (Dynamic Channel Assignment) info regarding the GOS (grade of services) and Quality of Service parameters at BS's whose RSS is greater than the serving BS is acquired by MS. By examine the parameters MS will choose the best BS to make a successful handoff with good voice quality. Forced terminations are generally perceived to severely degrade the quality of service. For this reason first priority of allocating channel is given to the handoff requests more readily then to new cell arrivals. This reduces the probability of forced termination at the expense of a (slight) increase in probability of new call blocking. These results are represented graphically in the paper.