Enhancing QoS parameters of group mobility model in WiMAX networks for military applications

WiMAX (Worldwide interoperability for microwave access) is an anticipating technology in rendering the wireless link over large distances since they provide eminent data rate, could be deployed at a small price and covers a big region. It is based on IEEE 802.16e standard, which specify five dissimilar service classes of data delivery for providing better QoS (Quality of Service) demand of certain applications like VoIP, video conference, Web, etc. Mobility in a network represents nodes distribution and movement over the network. Group mobility is a concept in which a group of MN´s moves at a same time particularly in the same direction with small space of the interval between individual nodes in a particular group. Such a Group mobility scenario is usually seen in military and emergency applications, in which battalion MNs moves in a same direction with a minor separation between the MNs in a group. There are various challenges associated with group mobility concept. In the group handover, as a lot of users in a group try to initiate a handover at the same time, it causes network congestion and increases the probability that the handover would be blocked. When a group of MNs moves out of coverage of currently serving BS (Base Station) into another BS, multiple handovers has to be performed at the same time which introduces large handover latency due to collision and back off. At the same time, MS does not get the coverage when the serving mobile BS moves out of its coverage and the other BS is far away from it. So, when a leader MS concept is introduced, it paves a solution for all these problems. The Leader MN integrates numerous handover processes from the group of MN´s into solitary, which could eradicate the collision of the ranging request at the base station and reduce the latency found in the network. In addition, it also overcomes communication crack problems by handling local communication by acting as a temporary BS when there is no suitable target BS - o perform handover. The main aim of this paper is to analyse the impact of VoIP on the group mobility concept with leader MN in WIMAX networks using various service classes. Some QoS parameters are analysed for the network with the leader MN concept using different service classes for VoIP applications. The results demonstrate that, ertPS and rtPS paves as a good service for VoIP applications. Since ertPS and rtPS are real time service classes, it outperforms other service classes in various aspects. It also reveals that the introduction of leader MN concept results in better reduction of handover latency, Average Delay, Jitter and paves a way for improvement in other QoS parameters like Throughput, PDR (Packet Delivery Ratio) and MOS (Mean Opinion Score). The delay is found to be high for the network with no leader MN concept as the there is no integration of the ranging request of the individual MNs in a group into a single request and no local communication handling to defeat the communication breakage. Also, as the network QoS parameters are analyzed by increasing the number of groups in a network, it is found that there is degradation in their performance due to the congestion that occurs in the network. Thus the introduction of leader MN overcomes all these drawbacks and shortens the latency incurred in the network and also improves QoS parameters.