# A Channel Allocation Mechanism for Cellular Networks
## 1 Introduction  
In recent years, the rise in economic growth and information technology advancement has improved the quality of personal communication systems (PCS). Moreover, people now pay more attention to the quality of service in cellular systems. As the number of mobile stations (MS) rises, how to provide the high quality of service in cellular systems has become a big challenge. The cellular system is composed of cells. A cell is the specific coverage of the _base station_ (BS), and it overlaps the coverage of neighboring cells. BS are fixed and interconnected through a fixed network. The structure of the cellular network is the connective coverage of the cell. Moreover, every cell only has limited channels to provide communication services. Among cellular systems, Global System for Mobile Communications (GSM) and Universal Mobile Telecommunications System (UMTS) are well known[1; 2; 3; 4]. They can decide whether to accept the call or not depending on the available number of the channels. When an MS wants to communicate with another user, it must first obtain a free channel provided by BS. If the BS has no free channel, the call will fail. Therefore, the number of channels for Handover In BSs that are reserved is an important issue for cellular systems. The number channels provided by BS is limited, and almost everyone has at least one cellphone at the moment, so the channels of BS are usually fully connected.  
When the channels of BS are fully occupied, the MSs will encounter the situation of call drop or call block [5]. If the MS wants to communicate with another MS, it must request a free channel from the BS to generate a new call. If a channel is free, it is assigned to the MS. If the BS has no free channel to allocate to the MS, the BS will drop the new call request from MS. If the communicating call moves from the old cell to the new cell, it has to request from the new cell a free channel. If the new cell has no free channel, the call block occurs. The call block causes more loss than the call drop because it stops the ongoing call. This study solves the problem through reserving channels for Handover In BS, but how many channels of the BS to reserve is an important issue.  
Therefore, there is much research that is working on the quality of cellular telephone system improvement. A number of studies have investigated the method to reserve the number of channels. These can be divided into two methods: one method is a static algorithm for channel allocation and another method is a dynamic algorithm [4; 6; 7; 8; 9; 10; 11; 12; 13]. However, the static allocation algorithms are unsuitable in dynamic environments.  
This paper will provide a dynamic channel allocation (DCA) mechanism. This study considers the traffic information to analyze the communication behavior and proposes a method to design the DCA mechanism in personal communication systems. This study uses the communication behavior of MSs and the MS movement to estimate the status of channel use in cells. Moreover, this study uses the above information to provide a method that decides how many channels have to be reserved in the cellular telephone system. Therefore, this study uses the proposed mechanism to dynamically adjust the number of channels reserved in each BS according to the variation of traffic information. Simulation results show that the call block probability (CBP) by using the DCA mechanism is lower than by the static channel allocation (SCA) mechanism. In cellular systems, the CBP is an important factor for measuring the quality of service [14; 15]. Therefore, this study will consider the factor of CBP and prove that the proposed mechanism is better than the SCA mechanism.