الفهرس 
Mobile Technology Evolution Paths
System DescriptionOnly 14 pages are availabe for public view
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Abstract
Fourth Generation (4G) system is seen as a full integration of all the
coexisting systems. 4G network is ALL IP (AlP) network that provides
seamless capabilities ensuring End-user mobility, Terminal mobility and
session mobility.
Third Generation Partnership Project (3GPP) standardized IP Multimedia
Subsystem (fMS) to provide real time multimedia communication over
cellular. The Voice CaU Continuity (VCC) function is an IMS AppLication
Server supports handoff between Circuit Switched (CS) domain and
Packet Switched domain as voice over packet. VCC employs Session
Initiation Protocol (SIP) to setup new communication leg and to release
the old legs.
SIP supports four types of Mobility, including terminal mobility, session
mobility, service mobility and person mobility. Additionally, it is cost
effective and simple application layer protocol. SIP required few specific
entities, such as the proxy servers and the redirect server. Additionally,
based on the fact that SIP has already been selected by as the signaling
standard in 3G wireless systems, it becomes more attractive to have the
SIP protocol as a complete solution for both of signaling and mobility
management in 3G wireless networks and heterogeneous systems. In other
words, mobility management comes as a part of the signaling system
without any extra cost. Also the characteristics of lower layer protocols are
understandably invisible to SIP.y
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Our contribution in this work is a development of a detailed queuing
model to estimate the end to end delay during handoff between two
different systems (Vertical Handoft) using SIP protocol and based on VCC
Application Server (Mobility Agent) and considering two transport options
User Datagram Protocol (UDP) and Transmission Control Protocol (TCP).
In addition to the model itself, the design parameters for all signaling
nodes and signaling channel capacity are identified to be used as reference
design in real network.
Our mode I shows that:
• As channel capacity increases, the end to end delay decreases. It is
decreased by 44-60% when the channel bandwidth increases from
9.2Kbps to 64Kbps depending on FER, while it slightly decreases
for RAB equals 128Kbps, so we concluded that the optimum
signaling channel RAB is 64 Kbps.
• The application of low-layer retransmission mechanisms, such as
Radio Link Protocol (RLP) results to more optimized handoff than
the increase of channel capacity even in environment with high
FER the end to end delay remains small (4-5 sec) for both of TCP
& UOP. Using RLP will enhance end to end delay with average
37% for both of TCP & UOP at low channel capacity while the
enhancements is on average 8-11 % for channel capacity equal 64
Kbps or higher.
• The use of UOP instead of TCP can make the session handoff 618%
percent shorter for Frame Error Rate (FER) lower than 4 %.• When UDP is used with RLP, the overall handoff delay is reduced
by 28% with respect to TCP for all FER.
• As processing servers load increases, the end to end delay
increases, when the load is doubled the end to delay increases by
10-30% according to the channel capacity and the type of transport
options.
The model has been verified against testbed measurements from
Huawei Technologies Seamless Mobility Lab in Shenzhen-China and
other researches. Results show 4-6% difference between the
. measurements and simulation results, while with other researches there
is a difference 2-8% when FER less than 10.2 at channel capacity 19.2
Kbps and 14-16% for channel capacity 9.6Kbps. The difference
between our model and other researches is mainly due considering
more delay elements in our model.