4248 IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY, VOL. 58, NO. 8, OCTOBER 2009 Reliability-Based Channel Allocation Using Genetic Algorithm in Mobile Computing Lutfi Mohammed Omer Khanbary and Deo Prakash Vidyarthi, Member, IEEE Abstract—Mobile computing involves bulk data transmission over the transmission media. To achieve highly reliable data trans- mission, wireless mobile networks require efficient reliable link connectivity, regardless of terminal mobility and, thus, a reliable traffic performance. Mobile networks consist of mobile hosts, base stations, links, etc. that are often vulnerable to failure. It is desirable to design a reliable network, in terms of services of both the base stations and the communication channels of the network, for the reliable transmission of the data. An attempt is made to employ those channels that offer a reliable communication at any given time. The objective of this study is to design an appropriate reliability-based model for channel allocation that retains the overall system reliability with acceptable system performance. The system may achieve acceptable performance not only during normal operations but also under various component failures. A genetic algorithm, which is a search procedure based on evolution- ary computation, is suited to solve a class of complex optimization problems. The potential of the genetic algorithm is used, in this paper, to improve the reliability of the mobile communication system. The proposed model designs a reliable mobile communi- cation system, irrespective of the mobile hosts that change their position due to mobility. A simulation experiment to evaluate the performance of the proposed algorithm is conducted, and results reveal the effectiveness of this model. Index Terms—Byzantine failure, channel allocation, channel reuse, failure, genetic algorithm (GA), handoff, reliability. I. I NTRODUCTION A CELLULAR system divides a geographical communi- cation area into smaller regions called cells, which are usually hexagonal for analytical and experimental purposes. A typical mobile network environment consists of cells, each of which is serviced by a base station (BS) located at the center of the cell. The BS provides a connection end point for the roaming mobile hosts (MHs). The BS is interconnected by wired or wireless media [1]–[3]. The channel-allocation problem deals with the allocation of frequency channels of the given network to the MHs. Two important concepts in channel allocation are cellular reuse of channels and handoff [1], [2]. The fundamental and elegant concept of cells relies on the channel or frequency reuse, i.e., the usage of the same channel by different MHs separated by a minimum distance [4], without interfering with each other (cochannel interference). Handoff occurs when a user moves Manuscript received August 11, 2008; revised November 25, 2008 and January 28, 2009. First published April 3, 2009; current version published October 2, 2009. The review of this paper was coordinated by Dr. P. Lin. The authors are with the School of Computer and Systems Sciences, Jawaharlal Nehru University, New Delhi 110 067, India (e-mail: dpv@mail. jnu.ac.in). Color versions of one or more of the figures in this paper are available online at http://ieeexplore.ieee.org. Digital Object Identifier 10.1109/TVT.2009.2019666 from the coverage area of one BS to the adjacent one while it is still involved in communication. A new channel will be as- signed to the MHs to continue the ongoing communication. The new channel may be within the same cell (intracell handoff) or in a different cell (intercell handoff). These issues are important in microcellular systems where the cell radius is small [1], [5]. A channel-allocation algorithm consists of two phases: 1) channel acquisition and 2) channel selection. The task of the channel acquisition phase is to collect the information of free available channels from the interference cells and ensure that the two cells within the minimum reuse distance do not share the same channel. The channel-selection phase deals with the selection of a channel from the available free channels to get better channel utilization in terms of channel reuse [6]. Wireless channels are scant resources, and there is a need to properly manage these resources. Fixed channel allocation (FCA) and dynamic channel allocation (DCA) are well-known channel-allocation schemes. In FCA, the assignment of fre- quencies to cell is static and does not vary. This approach is easier to implement but is inefficient, because the traffic load varies from time to time. DCA dynamically allocates the chan- nels. One better method, in the case of heavy load on one cell and light load on the neighboring cell, is to borrow channels from the neighbor cells. Cells with heavy traffic are dynami- cally assigned more channels. This scheme, which is a variant of DCA, is known as borrowing channel allocation (BCA) and is quite common in global systems for mobile communications [3], [4], [7]. However, it requires careful traffic analysis. There are few other ways of dealing with the excess load in mobile networks in addition to channel borrowing, such as channel sharing and cell splitting [8]. The growing importance of mobile networks has stimulated active research into how data can reliably be transmitted over the mobile communication network. This approach suggests allocating channels to the MHs in the presence of various failures in the form of uncertainties. The failure includes signal fading, channel interference, weak transmission power, path loss, etc. This paper suggests a novel idea of channel allocation based on the reliability aspect of the system. Reliability is the ability of a system to successfully perform its functions in routine and in hostile or unexpected circum- stances. Reliability is the probability that the network, with various components, performs its intended function for a given time period when operated under normal (or stated) environ- mental conditions. The unreliability of a connection is the probability that the experienced outage probability for the con- nection is larger than a predefined maximum tolerable value. The connection reliability is related to the traffic parameters [9]. 0018-9545/$26.00 © 2009 IEEE Authorized licensed use limited to: National Central University. Downloaded on December 16, 2009 at 02:26 from IEEE Xplore. Restrictions apply.