Loading...

Analysis & Improvement of Handover Process in Wireless Heterogeneous Networks

Bazrafkan, Armin | 2016

468 Viewed
  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 48972 (05)
  4. University: Sharif University of Technology
  5. Department: Electrical Engineering
  6. Advisor(s): Pakravan, Mohammad Reza
  7. Abstract:
  8. Wireless technology is growing rapidly. We have seen the evolution of these networks from first to fourth generation. Along with this growth, number of users needing wireless data services supporting real-time multimedia applications with high quality of service is growing annually. The challenge is to have the best connection anytime anywhere. Radio access technologies (RATs) consist of different types. Each RAT has its own technological characteristics. Operators constantly are seeking to increase their subscribers by providing high quality services so they can earn more profit. On the other hand users try to have a better experience from provided data services according to their application. Considering these facts, in order to offer more diverse services with higher qualities, a structure named heterogeneous networks is necessary for integrating and interworking of these RATs. In this environment, a user may go from one RAT to another which is called vertical handover (VHO). Optimizing the process of VHO can influence the delay, quality of service, cost and packet loss. In this thesis improvement and novel approaches are proposed for different parts of VHO. For initiation phase, new triggers are proposed which are based on IEEE 802.21, context information from mobile terminal and path prediction algorithms. These triggers reduce the number of HOs and Ping-Pong effect probability and increase the user satisfaction. Considering the fact that normalization method is one of the main causes of rank abnormality phenomena, a new normalization function is proposed. This function model the user prefrenceses and application sensetiviy with respect to each criterion properly and does not have any negative influence on the rank abnormality probability. For assigning weights to the decision criteria a new approach based on fuzzy concept is proposed. The weighting method solve the problem of not considering the interdependency of the criteria and eliminates the ambiguity of the opinion of the decision maker in defining the relative importance of the criteria. Finally a new MADM algorithm for network selection is introduced which has a high capability in differentiating the alternatives and has high resiliency to changes. Simulation results confirm the excellence of the proposed HO process compared with rival approaches
  9. Keywords:
  10. Heterogeneous Networks ; Normalization ; Service Quality ; Handover ; User Movement ; Network Selection

 Digital Object List

 Bookmark

  • تصویبنامه
  • به نام خدا
  • دانشگاه صنعتي شريف
  • دانشکده مهندسی برق
  • پایاننامه کارشناسي ارشد