Reduction of handover delay in WiMAX for high mobility

Khan, Imran (2017) Reduction of handover delay in WiMAX for high mobility. Doctoral thesis, Anglia Ruskin University.

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In emerging technologies, WiMAX is identified as a cheaper replacement to mobile and wireless technologies such as 3G, 4G or any other future generation technologies and can provide highspeed data transfer over long distances and at suitable Quality of Service (QoS) at high mobility. WiMAX requires support and capacity for high mobility to avoid the loss of quality of service. The goal of faster mobility can be achieved, but WiMAX needs the support of an effective handover mechanism to ensure continuous and without any interruption in data transfer. This thesis focusses to solve the handover problem in mobile WiMAX (IEEE 802.16e and IEEE802.16m) and to find and identify the factors which directly affect the handover process. There is a range of factors which can affect the mobility process in Mobile WiMAX. The acceptable handover delay is 50 ms as per IEEE WiMAX standards (, 2012). This study has identified that there is a total of 16 factors which have direct and indirect effect but after detailed simulation and analysis, it has been found out that only 7 factors could be used to improve handover delay in WiMAX and that’s why the initial RIVERBED simulations tried to identify the extent of these factors which directly affect the handover delay in WiMAX. The following parameters that are directly linked to the handover success are identified are as follows: a) Link goes down faster b) Scan iteration c) Interleaving Interval d) Timeout Parameter e) Frame Duration f) Client Timeout g) Scan Duration The simulation experiments on individual factors has identified that these factors result in a minimum handover delay at specific values which are called best performing values. When these best performing values of the 7 factors were applied to single WiMAX experiment, the improvement was identified, which showed that there have been better handover delay results due to the better-received signal strength, better average delay per Second and the throughput was drastically improved. There was further need to improve the handover decisions and therefor handover algorithm was used for this purpose. The handover algorithm used was a dual trigger algorithm which improved the handover delay, but resulted in packet loss and consequently resulted in retransmissions. To solve to problem of handover delay without downgrading the WiMAX signal, a new algorithm was suggested and tested which has shown results in lowering the handover delay and increasing the signal level. The handover improvement was done in stages and therefore there was a gradual improvement in handover delay in each individual stage. The overall problem has been divided into stages considering that the solution is dependent on many factors. The development of the WiMAX model is the main issue in this research. Different types of scenarios were adopted on RIVERBED simulations to produce significant data for analysis and validation.

Item Type: Thesis (Doctoral)
Keywords: WiMAX, Mobile Broadband, Handover Delay, Handover Algorithm
Faculty: Theses from Anglia Ruskin University
Depositing User: Lisa Blanshard
Date Deposited: 30 Jan 2019 11:02
Last Modified: 09 Sep 2021 18:58

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