REDUCING THE EFFECTS OF PING-PONG HANDOVER IN INTRA-LTE NETWORKS USING FUZZY LOGIC

Improving system performance in terms of data rate, latency, mobility and cost is the scope of Long Term Evolution (LTE) system. All IP architecture with distributed mobility management that have been implemented in LTE and the handover (HO) decision is performed by the evolved base station (eNB). The ping-pong movement in LTE is one of the most crucial problems which reduce the performance of the HO. In this paper, the impact of ping-pong handover on inter eNB handover in LTE networks is investigated. The object of the present work is to provide a method for reducing the number of ping-pong HOs in intra E-UTRA networks. A novel HO algorithm, based on keeping the old path between the source eNB and SGW/MME during the ping-pong movement and delaying the completion HO part, is presented. The ping-pong avoidance algorithm for intra E-UTRA can be a tool to reduce the number of ping-pong HOs and control the demands of the network resources. Analysis results -based on fuzzy logic technique- of the proposed algorithm showed that the probability of ping-pong HO can be reduced efficiently as the difference between the received signal strength from the target and the source (SS(target-source)) and the timer value are higher than 3dB and 1.5 sec respectively.

AVOIDANCE OF PING-PONG HANDOVER IN BEYOND 3rd GENERATION MOBILE NETWORKS

Handover technique in LTE networks suffers from Ping-pong Handover, which can be defined as a call is handed over to a new eNB and it then is handed back to the source eNB (evolved NodeB) within pre-defined and short time. Ping-pong handover can reduce the quality connection and increases the number of handovers which in turn raise the network load and generally degrade the network performance. The work aims to present a novel approach to reduce the undesirable effects of ping-pong handover in beyond third Generation Mobile Networks. The study guided to suggest an algorithm to select whether the user movement belongs to ping-pong type of movement or not and propose a technique to reduce the number of ping-pong handovers in Networks. The suggested algorithm is based on performing the handover process in two steps (separated by timer). First step starts the handover preparation and execution as soon as the received signal strength from the target eNodeB becomes higher than that received from the source eNodeB. And delay the completion part of the HO technique for a time equal to the timer value. The research focused on the ping-ping phenomenon taking into account maintained the dropped calls rates at lowest levels. The optimal timer values are determined based on the width of overlapping area, user velocity and type of eNodeB. Moreover, the effects of tilting antennae on the probability of ping-pong handover are studied. Analysed and simulated results (using Matlab and TRIAS) showed that the timer values of the proposed algorithm reconciled with the mathematical results. Also, results clarified that tilting eNBs’ antennas decrease the probability of dropped calls. Comparison results illustrated that there is a significant reduction in the probability of ping-pong HOs, without any increasing in the probability of dropped calls for different scenarios. In future work, the proposed algorithm can be evolved and applied to heterogeneous networks and LTE advanced.