Vertical handoff and TCP performance optimizations using cross layer approach
VERTICAL HANDOFF AND TCP PERFORMANCE
USING CROSS LAYER APPROACH
Department of Electronics & Electrical Communication Engineering
Indian Institute of Technology, Kharagpur
Roll No : 10EC64R04
Under the guidance of
Prof. Rajashri Roy
This thesis focuses on finding a solution to the vertical
mobility problem together with data transmission over
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
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
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.
Requirements Of Handoff Mechanism
Received Signal strength (RSS)
Heterogeneous Network Architecture
Fig1: Heterogeneous network architecture integrating with Wi-Fi, and
Different Approaches of Vertical
Vertical Handoff based on Hysteresis
Technique and Predictive RSS
Vertical Handoff based on Polynomial
Cross Layer-BasedTechnique for Increasing
TCPThroughput inVertical Handover
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.
Handoff Detection Algorithm based on Polynomial
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
Fig 4: Message flow in the cross-layer mechanism 
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
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
Next, a comparison between the throughput of the TCP
(proposed by ) and throughput of TCP proposed by thesis is
plotted against the no. of Vertical Handoff.
Fig 9: Comparison of the Data rate ofTCP  and Modified TCP proposed with no.Vertical Handoff
The plots below show a comparison between the congestion windows
during vertical handoff.
Fig 10: Comparison of the Congestion Window ofTCP  and Modified TCP
proposed duringVertical Handoff
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  and Modified TCP
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  and Modified TCP proposed