Advances in Computer Science and Information Technology (ACSIT) p-ISSN: 2393-9907; e-ISSN: 2393-9915; Volume 3, Issue 2; January-March, 2016, pp. 128-131 © Krishi Sanskriti Publications http://www.krishisanskriti.org/Publication.html Selection of Hysteresis Margin for Optimum Handover Triggering in Next Generation Cellular Systems Sudesh Pahal 1 , Vineet Gulia 2 , Nishank Chauhan 3 and Ashish Goel 4 1 Maharaja Surajmal Institute of Technology, New Delhi, E-mail: 1 pahal.sudesh@gmail.com, 2 vineetgulia10@gmail.com, 3 nishankchauhan007@gmail.com, 4 goelashish008@gmail.com Abstract—Handover, a process of transferring connection of a mobile unit from an access point to another access point, is a challenging aspect in next generation cellular systems. The major difficulties experienced during handover between various technologies include high handover delay, large number of handovers and poor quality of service experienced by mobile users. This paper attempts to find an appropriate handover point in order to deal with handover related problems and to provide a promising quality to mobile users. The handover decision is taken on the basis of received signal strength and hysteresis margin. The variation of the received signal strength of current access point and the target access point with distance is followed to choose a suitable point for triggering handover. It is observed from the results obtained through Matlab simulation that the handover trigger point gets affected by variation in the hysteresis margin. In addition, the velocity of mobile users also has great impact on handover parameters such as handover trigger point, hysteresis delay and total handover delay. INDEX TERM: Handover, Received signal strength, hysteresis margin, hysteresis delay, handover trigger point 1. INTRODUCTION A wireless local area network (WLAN) is a protocol that uses high frequency radio waves to connect with two or more devices at the same time to share some data. An access point is involved in a WLAN in order to connect it to internet. While using the WLAN users can move in the coverage area to get the benefits of it. 2.4 GHz and 5 GHz are the commonly used frequency in the wireless local area network. In Wi-Fi unlicensed spectrum is used mainly referred as ISM bands. It enables users to use the radio spectrum without any restriction. Handoff management is a process of maintaining a connection when the mobile unit moves across the two access point. It involves three stages in first stage the mobile unit gets out of reach from one access point and enters in the second access point then in the second stage it connect with the second access point but during that time there will be a handover delay which is affected by various factors like velocity of the mobile unit etc. and in the final stage the connection is set up with the second access point [1]. Handover delay occurs because of the time taken by Received signal strength algorithm.MAC layer and higher layers are mainly focused when handover delay is analyzed .Hysteresis margin is used to provide a buffer for the initiation of the handover process. It is the difference between the signal strength from the target access point and the current access. Whenever the difference between the target and current access point becomes more than hysteresis margin, handover is triggered. For different values of hysteresis margin different handoff performance will be obtained. An optimum value of hysteresis margin is to be selected in order to have minimum delay [2]. Hysteresis delay is the time difference between the moment at which handover is triggered at a particular value of hysteresis margin and the triggering point when hysteresis margin is 0 [7]. For a particular hysteresis margin the hysteresis delay is different for different velocities. Handover delay is the summation of hysteresis delay and the time taken in the processing of handover procedures. This research paper consists of five sections: In section II, the related work regarding this research paper is explained. In section III, the proposed work which include the system model and the analytical methods is discussed. In section IV, the simulations results are shown. In section V, the conclusion of the research paper is explained. 2. RELATED WORK Few authors have elaborated the impact of hysteresis margin used in handoff that if the value of hysteresis margin is too high then the handoff delay may result in terminated