40 International Journal of Communication Networks and Information Security (IJCNIS) Vol. 9, No. 1, April 2017 Enhanced Handover Mechanism in Long Term Evolution (LTE) Networks Mohsin Khan 1 , Majid Ashraf 1 , Haseeb Zafar 1 and Tufail Ahmad 2 1 University of Engineering & Technology, Peshawar, Pakistan 2 CECOS University of Information Technology and Emerging Sciences, Peshawar, Pakistan mhsnkhaan@gmail.com, [majid, haseeb] @uetpeshawar.edu.pk, tufailuetian@yahoo.com Abstract: Femtocell is a low power base station, wireless access point designed especially for homes and small organizations. It is promising technology for operators to improve their capacity and for users to give indoor coverage. As mobile users are increasing day by day so the legacy system is unable to provide such a high data rates to all these users. In this case femtocells play a key role to offload the data traffic from macro base station. The implementation of femtocell has posed so many challenges like interference, localization, access control and mobility management. The aim of this paper is to present an enhanced algorithm for handover in Hand-In scenario. In already existing algorithms handover is decided on the basis of a single parameter but here we have simulated an algorithm that considers multiple parameters instead of a single parameter for handover. Through this algorithm, the most suitable femtocell will be selected for handover, hence number of handovers will be decreased. Simulation results show that the system performance has been improved. Keywords: Femtocell, Handover, Interference, Macro-cell, Hand-In, Mobility Management. 1. Introduction Nowadays, one can observe that the capacity demand for mobile wireless communication has increased up to a larger extent and the mobile operators are trying to bring innovative and low cost solution to meet the requirements of users. According to a survey by International Telecommunication Union, data capacity is used 5% more by the smartphone users comparatively to standard phone users. The annual penetration of smartphones is 30% while demand for capacity is 70-200% per year. Current legacy network cannot compete with this data explosion as these are already saturated and having capacity crises. Due to limited availability of resources the existing technology cannot utilize the advance applications in an efficient way and there are issues that need to be solved. This prominent increase in the data traffic has got the attention of researchers to this area to bring about new ideas and such network topologies that efficiently fulfill the demands of the users [1]. A study on wireless usage indicate that 2/3 of the voice and 90% of data traffic is indoor so researchers suggested to offload the data traffic from macro- cells which will be a great relief for operators and as well as subscribers. Too much attention was given to the transmitting signals in order to find their better formats and also to the improvement of transmitter and receiver technology. Other approach for solving the problem of capacity and coverage is to bring the transmitter and receiver into close vicinity of each other. Operators lost their interest in this approach as this was not economically viable due to the deployment of Base Stations (BS). Hence, network operators opted for small cells known as femtocells as a solution for the improvement of network coverage that specifically address the indoor mobile users. For the service providers, this integration of femtocells in macro-cell not only offloads the traffic but also brings reduction in the investment capital, operational costs and maintenance cost [2]. Moreover, it also makes the cellular network reliable. Advantage to the indoor user is high data rate while they are surfing internet in their homes and offices in an urban area. These small cell base stations are also termed as Femto Access Points (FAPs), and are short range and low power i.e. 10-30m and 10-100mW respectively [3]. It has got the benefit of Plug-and-Play device so that users can easily operate these devices. Femtocells work in the licensed spectrum owned by the operator and are connected to the core network through DSL, cable or optical fiber. It is installation is quite different from macro-cells, as these are Plug and Play devices so a user can easily install and maintain it in an unplanned manner. This uncoordinated nature of femtocells has created problem of Radio Resource Management and handover. For the integration of femtocells in the LTE-A existing network it is necessary that there should be efficient procedures for the handovers [4]. The integration on femtocells into macro-cell results in a two-tier network and the handovers algorithms that are used in rationally in macro cell cannot satisfy the mobility of user in such a two-tier network. In the literature, there are various handover schemes that are based on different parameters as decision parameters but they are not sufficient for tow-tier network. We have presented an algorithm that considers more than one parameter for the handover decision. 2. Background Over the past couple of years there has been a drastic increase in the users of data traffic and legacy wireless system was unable to provide such services to the users. In order to compete with the challenges International Telecommunications Union Radio sector (IMT-R) introduced a set of requirements called International Mobile Telecommunication Advanced (IMT-Advanced) to take a step towards next generation i.e. 4G [5]. In response to such requirements of IMT-A, 3GPP submitted its technology as a candidate for the next generation and it was called LTE-A. LTE-A can also be termed as 4G as it has got the improved performance comparatively to early 3G and 3G LTE