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Vertical handoff and TCP performance optimizations using cross layer approach


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Vertical handoff and TCP performance optimizations using cross layer approach

  1. 1. VERTICAL HANDOFF AND TCP PERFORMANCE OPTIMIZATION USING CROSS LAYER APPROACH Department of Electronics & Electrical Communication Engineering Indian Institute of Technology, Kharagpur May 2012 by Anurag Mondal Roll No : 10EC64R04 Under the guidance of Prof. Rajashri Roy
  2. 2.  This thesis focuses on finding a solution to the vertical mobility problem together with data transmission over TCP.  The basic objective is how to utilize the asymmetric data rates in overlapping heterogeneous wireless networks to the fullest. The objective is to find a method that will give better performance than a traditional handoff algorithm based on a received signal strength threshold.
  3. 3.  The motivation for addressing the given problem areas is to develop wireless packet switched communications by facilitating a holistic approach for handoff and mobility management in heterogeneous wireless networks.  The cross-layer approach involves taking into consideration on handoff technique that are employed in the physical layer solutions in cellular networks and on the other hand mobility management solutions that are employed in the Transport layer.
  4. 4. Requirements Of Handoff Mechanism  Bandwidth  Handoff Latency  Power Consumption  Network Cost  Received Signal strength (RSS)
  5. 5. Heterogeneous Network Architecture Fig1: Heterogeneous network architecture integrating with Wi-Fi, and UMTS/B3G
  6. 6. Different Approaches of Vertical Handoff  Vertical Handoff based on Hysteresis Technique and Predictive RSS  Vertical Handoff based on Polynomial Regression-Based Prediction  Cross Layer-BasedTechnique for Increasing TCPThroughput inVertical Handover
  7. 7. The RSS-based scheme with hysteresis is adopted to avoid unnecessary handoff due to the ping-pong effect. Fig 2:Handoff points in different handoff approaches.[6]
  8. 8. Handoff Detection Algorithm based on Polynomial Regression-Based Prediction Scenario: Considering two kinds of wireless networks in the system B3G & WLAN . Mobile node is currently in a WLAN network. Fig3: Vertical Handoff based on RSS prediction
  9. 9. Fig 4: Message flow in the cross-layer mechanism [6]
  10. 10. RTT RTTminnew_max predictive .BW BW  RTT cnwd BWpredictive RTT RTTmin opt cnwdcnwd 
  11. 11. factorRSS RSS _10 )9.37distance.3( 100 .log.10 )()( dPLPdRSS trans  )10log(..10)( nSdPL 
  12. 12. Fig 5: Signal strength received by the MobileTerminal
  13. 13. Fig 6: Random Movement of the MobileTerminal
  14. 14. Now, using the above simulation characteristic, the number of vertical handover is calculated over different velocity (1-25m/s). Fig 7: No. ofVertical Handoff against velocity of the Mobile Terminal
  15. 15. Now, the mobile terminal is considered to moving in the wireless environment, and the situation of data transmission is considered. It is considered that mobile terminal receiving data throughout the simulation. Data received is considered as TCP packets. Fig 8: Data received by the Mobile Terminal
  16. 16. Next, a comparison between the throughput of the TCP (proposed by [6]) and throughput of TCP proposed by thesis is plotted against the no. of Vertical Handoff. Fig 9: Comparison of the Data rate ofTCP [6] and Modified TCP proposed with no.Vertical Handoff
  17. 17. The plots below show a comparison between the congestion windows during vertical handoff. Fig 10: Comparison of the Congestion Window ofTCP [6] and Modified TCP proposed duringVertical Handoff
  18. 18. Now a comparison between the number of packet drops for both the algorithm is calculated. We can see that the no. of packet drop is comparatively lower in proposed algorithm. Fig 11 :Comparison of the Packet Drop of TCP [6] and Modified TCP proposed
  19. 19. Similarly, a plot for comparison of Efficiency of TCP for both the algorithm shows a better result in the proposed algorithm. Fig 12: Comparison of the Efficiency ofTCP [6] and Modified TCP proposed