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

3.  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.

4.  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.

7. Requirements Of Handoff Mechanism
 Bandwidth
 Handoff Latency
 Power Consumption
 Network Cost
 Received Signal strength (RSS)

8. Heterogeneous Network Architecture
Fig1: Heterogeneous network architecture integrating with Wi-Fi, and
UMTS/B3G

9. 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

10. 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]

14. 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

16. Fig 4: Message flow in the cross-layer mechanism [6]

17. RTT
RTTminnew_max
predictive
.BW
BW 
RTT
cnwd
BWpredictive
RTT
RTTmin
opt cnwdcnwd 

22. factorRSS
RSS _10
)9.37distance.3(
100
.log.10
)()( dPLPdRSS trans 
)10log(..10)( nSdPL 

23. Fig 5: Signal strength received by the MobileTerminal

24. Fig 6: Random Movement of the MobileTerminal

25. 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

26. 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

27. 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

28. 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

29. 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

30. 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