International Conference on Computer and Communication Engineering (ICCCE 2012), 3-5 July 2012, Kuala Lumpur, Malaysia 978-1-4673-0479-5/12/$31.00 ©2012 IEEE Advanced Handover Techniques in LTE- Advanced system Ibraheem Shayea, Mahamod Ismail, Rosdiadee Nordin Dept. of Electrical, Electronic & Systems Engineering Universiti Kebangsaan Malaysia 43600 UKM Bangi, Selangor, Malaysia Shaia2009@yahoo.com, {mahamod, adee }@eng.ukm.my Abstract— There are always increasing demands of high speed data applications in wireless systems with fast and seamless access to voice and multimedia services and QoS guaranteed such as in Fourth Generation (4G) Long Term Evolution (LTE)- Advanced system. Moreover, as mobility speeds support is expected to reach up to 500 km/h, the handover will occur more frequent, thus the system performance in terms of delay and packet loss will be degraded. Hence, efficient radio resource management including handover techniques, load balancing and interference management are essential. In this paper, we present a comprehensive survey on the advanced handover techniques, requirements and features for LTE-Advanced system. Also, advanced handover techniques are highlighted and discussed such as Fractional Soft Handover (FSHO), Semi Soft Handover (SSHO) and multi-carrier handover (MCHO) that incorporate backward compatibility to the existing system. Meanwhile, FSHO technique based on CA with 5CCs are investigated in term of cell throughput and user’s handover numbers. The result shows that, FSHO with 5 CCs improves LTE-Advanced system in term of cell throughput and numbers of user handover better than Non- CA. Consequently, the existing handover techniques that have been proposed have several advantages, but they are not sufficient to solve hard handover problems. Therefore, a new handover technique is essential required to support fast and seamless handover in LTE-Advanced system. As a result, an advanced handover technique is proposed by combining FSHO, SSHO, and MCHO techniques that can enhance the system performance in term of latency, outage probability and handover reliability especially at cell boundary. Also, the expected output from this hybrid technique can reduce transmission overhead on the network cells by balancing the traffic load in the network cells. Keywords- LTE- Advanced; Advanced Handover techniques; Fast and Seamless Handover. I. INTRODUCTION With the strong demand for multimedia services and broadband wireless applications with higher data rate and wider bandwidth with fast and seamless connectivity everywhere and any time. The IMT-Advanced system has initiated the standardization process for the next-generation mobile communication systems (4G) [1]. Meanwhile, the strong competitive increased between the new wireless technologies pushed Third Generation Partnership Project (3GPP) to developing a new mobile communication standard to keep abreast of recent developments in wireless technology and achieving the ambitious performance goals of IMT-Advanced mobile systems [1]. For that, 3GPP submitted Long Term Evolution (LTE)-Advanced Release 10 (R10) system to ITU, in order to meet the requirements of the candidate IMT-Advanced system as Fourth Generation (4G) technology. LTE-Advanced system expected to meet and in many times exceed IMT-Advanced system requirements. The supporting for high mobility speed is one of IMT-Advanced system requirements that should be achieved in 4G. LTE-Advanced system can supports for high mobility speed up to 500 km/h [2]. Moreover, LTE-Advanced is expected to support high Data Rate up to 1Gbps in downlink (DL) and up to 500Mbps in uplink (UL). Also, LTE-Advanced system air interface specifications enhanced link layer handover mechanisms providing short handover interruption time [1]. Accessing multimedia services and broadband wireless application in LTE-Advanced system with high Users Equipment (UE) speed will degrade the reliability and efficiency of the wireless system, especially during handover from the source to the target eNBs. So, the increasing use of wireless technology with very high mobility speed will increase the frequent handover occur. For that, the fast and seamless connectivity with minimum delay during handover from source to target eNBs under different UE speed is one of the greatest goals that are necessary for new wireless systems. LTE- Advanced system is one of the latest mobile communication systems that suffer from lack of fast and seamless connectivity to the UEs. The handover in LTE-Advanced system is purely based on hard handover. Hard handover is fairly simple with less complexity compared to the soft handover. On the other side, there are some limitations on the hard handover, such as high data loss, disruption time, high outage probability and carrier interferences, thus cause unreliable handover procedure [2], especially for multimedia services and broadband applications. Also, by using hard handover technique, it is difficult to maintain the QoS requirement due to the delay in handover that occurs during eNB migration [3], Meanwhile, providing fast and seamless access to multimedia services and broadband internet application with minimum delay requirements is one of the main goals that should be achieved in LTE-Advanced system, which can be achieved by supporting handover from source to target eNBs [4]. At the moment, there are several Universiti Kebangsaan Malaysia (UKM). 74