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CHAPTER 1 Introduction : Integration of the IEEE 802.11 wireless LANs (WLANs) and 3G networks, such as Universal Mobile Telecommunication Service (UMTS), has been intensively studied recently due to their complementary characteristics. The 3GPP has been continuously evolving to support multimedia services which require high data rates in cellular networks. Nowadays, a UMTS network can support services with maximum data rate of 2Mbps while a 2.5G cellular network, such as General Packet Radio Ser
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CHAPTER 1
Introduction :
Integration of the IEEE 802.11 wireless LANs (WLANs) and 3G networks, such
as Universal Mobile Telecommunication Service (UMTS), has been intensively studied
recently due to their complementary characteristics. The 3GPP has been continuously
evolving to support multimedia services which require high data rates in cellular
networks. Nowadays, a UMTS network can support services with maximum data rate of
2Mbps while a 2.5G cellular network, such as General Packet Radio Service (GPRS), can
only provide 100-200 kbps. UMTS networks are gaining popularities and being deployed
globally in countries such as UK, Japan and USA. To further increase the data rate at the
downlink side, High Speed Downlink Packet Access (HSDPA) was introduced by the
3GPP research community providing data rate up to 14Mbps. Deployment of HSDPA
networks has been commercially launched, but network operators may be reluctant to
completely replacing existing legacy networks which are fully functional as it would
require an extremely high installation cost. Meanwhile, the commercial success of the
IEEE 802.11 protocol makes the access point-based WLAN networks widely deployed in
hot-spot areas such as offices, airports and coffee shops. The IEEE 802.11b can provide
data rate up to 11Mb/s in 2.4 GHz. The IEEE 802.11a and IEEE 802.11g can provide up
to 54 Mb/s in 5GHz and 2.4GHz bands, respectively. But WLANs have disadvantages of
having small coverages. The coverage by an access point (AP) of a WLAN is up to
several hundred meters in radius and a cell covered by a UMTS Node B is usually several
kilometers in radius. Such complimentary characteristics of these two popular networks
have stimulated research efforts to integrate UMTS and WLAN networks so that mobile
stations can choose the network that has better network quality when they are covered by
1
both networks. The hardware requirement for integrating UMTS and WLAN networks is
mainly to build dual-mode user equipment (UE) which has the capability of accessing
either network. After such a dual-mode UE is available and software’s at each network’s
operational components are updated, a ubiquitous wireless environment with high data
rate enabled in hot spot areas can be set up. The integrated WLAN/UMTS systems, the
access control problem arises to decide which network it should be admitted to and when
it should switch from one network it should be admitted to and when it should switch
from one network to the other through vertical handover. The decision can be made by a
new software layer named as IP Switch layer which resides in the UE and keeps
monitoring the situation of current cell. Once the traffic in one network becomes higher
and the network efficiency gets impaired, the IP switch layer delivers the packets from
the upper layer to the other network’s interface. In this paper, we propose a network
access decision algorithm based on the utility-based access control framework. Utility
function is a concept borrowed from economics and has been used for scheduling and
allocating resources in wireless communication systems. In our proposed framework,
admission control and vertical handover decisions are made through evaluating some
utility functions implemented in UMTS’s Node B, RNC and WLAN’s AP. The utility
functions are designed so that each network’s capacity is considered to achieve load
balancing between UMTS and WLAN networks.
2
1.1 EXISTING SYSTEM:
When a mobile station is covered by both networks in the integrated
WLAN/UMTS systems, the access control problem arises to decide which network it
should be admitted to and when it should switch from one network to the other through
vertical handover. The decision can be made by a new software layer named as IP Switch
layer which resides in the UE and keeps monitoring the situation of current cell. Once the
traffic in one network becomes higher and the network efficiency gets impaired, the IP
switch layer delivers the packets from the upper layer to the other network’s interface.
PROPOSED SYSTEM:
we propose a network access decision algorithm based on the utility-based access
control framework. Utility function is a concept borrowed from economics and has been
used for scheduling and allocating resources in wireless communication systems. In our
proposed framework, admission control and vertical handover decisions are made
through evaluating some utility functions implemented in UMTS's Node B, RNC, and
WLAN's AP. The utility functions are designed so that each network's capacity is
considered to achieve load balancing between UMTS and WLAN networks.
We implemented a dual-mode UE in the NS-2 software.
3
CHAPTER 2
UMTS:
UMTS is a Third Generation (3G) wireless protocol that is part of the
International Telecommunications Union’s IMT-2000 vision of a global family of 3G
mobile communications systems. UMTS is expected to deliver low-cost, high-capacity
mobile communications, offering data rates up to 2 Mbps. NS2 UMTS Specialized Model
allows you to model UMTS networks to evaluate end-to-end service quality, throughput,
drop rate, end-to-end delay, and delay jitter through the radio access network and core
packet network. It can also be used to evaluate the feasibility of offering a mix of service
classes given quality of service requirements. UMTS model features include:
Based on WCDMA
Support for 4 QoS classes: Background, Conversational, Interactive, Streaming
Support for UE, Repeater, Node B, RNC, SGSN, GGSN with ATM and IP
Network connectivity
Dedicated (DCH) and Common / Shared Channels (RACH, FACH, DSCH)
Multiplexing of logical channels to transport channels
Acknowledged / Unacknowledged / Transparent RLC modes
Radio Access Bearer setup, release, negotiation, renegotiation, preemption
Open Source Admission Control
Outer loop power control
Hard / Soft / Softer handover
GTP Support up to RNC
4
Universal Mobile Telecommunications System (UMTS) is one of the third-
generation (3G) mobile telecommunications technologies, which is also being developed
into a 4G technology. Currently, the most common form of UMTS uses W-CDMA as the
underlying air interface. UMTS and its use of W-CDMA is standardized by the 3GPP,
and is the European answer to the ITU IMT-2000 requirements for 3G cellular radio
systems.
2.1 FEATURES OF UMTS:
UMTS, using W-CDMA, supports up to 21 Mbit/s data transfer rates in theory
(with HSDPA), although at the moment users in deployed networks can expect a transfer
rate of up to 384 kbit/s for R99 handsets, and 7.2 Mbit/s for HSDPA handsets in the
downlink connection. This is still much greater than the 9.6 kbit/s of a single GSM error-
corrected circuit switched data channel or multiple 9.6 kbit/s channels in HSCSD (14.4
kbit/s for CDMAOne), and—in competition to other network technologies such as
CDMA2000, PHS or WLAN---offers access to the World Wide Web and other data
services on mobile devices.
Precursors to 3G are 2G mobile telephony systems, such as GSM, IS-95, PDC,
CDMA PHS and other 2g technologies deployed in different countries. In the case of
GSM, there is an evolution path from 2G, to GPRS, also known as 2.5G. GPRS supports
a much better data rate (up to a theoretical maximum of 140.8 kbit/s, though typical rates
are closer to 56 kbit/s) and is packet switched). It is deployed in many places where GSM
is used. E-GPRS, or EDGE, is a further evolution of GPRS and is based on more modern
coding schemes. With EDGE the actual packet data rates can reach around 180 kbit/s
(effective). EDGE systems are often referred as “2.75G Systems”.
5
Since 2006, UMTS networks in many countries have been or are in the process of
being upgraded with High Speed Downlink Packet Access (HSDPA), some things known
as 3.5G. Currently, HSDPA enables downlink transfer speeds of up to 21 Mbit/s. Work is
also progressing on improving the uplink transfer speed with the High-Speed Uplink
Packet Access (HSUPA). Longer term, the 3GPP Long Term Evolution project plans to
move UMTS to 4G speeds of 100 Mbit/s down and 50 Mbit/s up, using a next generation
air interface technology based upon Orthogonal frequency-division multiplexing.
The first national consumer UMTS networks launched in 2002 with a heavy
emphasis on telco-provided mobile applications such as mobile TV and video calling.
The high data speeds of UMTS are now most often utilized for Internet access:
experience in Japan and elsewhere has shown that user demand for video calls is not
high, and telco-provided audio/video content has declined in popularity in favour of high-
speed access to the World Wide Web – either directly on a handset or connected to a
computer via Wi-Fi, Bluetooth, Infrared or USB.
6
CHAPTER 3
UMTS 3G Mobile Wireless Network Architecture:
Universal Mobile Telecommunications System (UMTS), standardized by the
3GPP, is the 3G mobile communication technology successor to GSM and GPRS. UMTS
combines the W-CDMA, TD-CDMA, or TD-SCDMA air interfaces, GSM’s Mobile
Application Part (MAP) core, and the GSM family of speech codecs.
W-CDMA is the most popular cellular mobile telephone variant of UMTS in use.
UMTS, using W-CDMA, supports up to 14.0 Mbit/s data transfer rates in theory with
High Speed Downlink Packet Access (HSDPA), although the performance in deployed
networks could be much lower for both uplink and downlink connections.
3.1 RADIO ACCESS CORE NETWORK
A major difference of UMTS compared to GSM is the air interface forming
Generic Radio Access Network (GeRAN). It can be connected to various backbone
networks like the Internet, ISDN, GSM or to a UMTS network. GeRAN includes the
three lowest layers of OSI model. The network layer (OSI 3) protocols form the Radio
Resource Management protocol (RRM). They manage the bearer channels between the
mobile terminals and the fixed network including the handovers.
The UMTS standard is an extension of existing networks based on the GSM and
GPRS technologies. In UMTS release 1, a new radio access network UMTS terrestrial
radio access network (UTRAN) is introduced. UTRAN, the UMTS radio access network
(RAN), is connected via the Iu to the GSM Phase 2+ core network (CN). The Iu is the
UTRAN interface between the radio network controller (RNC) and CN; the UTRAN
7
interface between RNC and the packet-switched domain of the CN (Iu-PS) is used for PS
data and the UTRAN interface between RNC and the circuit-switched domain fo the CN
(Iu-CS) is used for CS data.
3.2 UTRAN
UTRAN is subdivided into individual radio network systems (RNSs), where each
RNS is controlled by an RNC. The RNC is connected to a set of Node B elements, each
of which can serve one or several cells. Two new network elements, namely RNC and
Node B, are introduced in UTRAN.
The RNC enables autonomous radio resource management (RRM) by UTRAN. It
performs the same functions as the GSM BSC, providing central control for the RNS
elements (RNS and Node Bs).
Node B is the physical unit for radio transmission/reception with cells. Node B
connects with the UE via the W-CDMA Uu radio interface and with the RNC via the Iub
asynchronous transfer mode (ATM)-based interface. Node B is the ATM termination
point.
Figure 1: UMTS-WLAN Interworking Architecture
8
UMTS Network Architecture: From the Radio Access to Core Network
Modeling UMTS Power Saving based on M/G/1 Queue with Vacations
o We investigated the power saving mechanism of UMTS. UMTS DRX is
exercised between the network and a mobile station (MS) to save the
power of the MS. The DRX mechanism is controlled by two parameters:
the inactivity timer threshold tI and the DRX cycle tD. Queueing analytic
and simulation models were proposed to study the effects of tI and tD on
output measures including the expected queue length, the expected packet
waiting time, and the power saving factor.
9
Main achievements and outcomes
o Research or technology outcomes
To the best of our knowledge, our work is the first one to model
UMTS power saving mechanism by using M/G/1 queue with
vacations.
3.3 Wireless LAN (WLAN):
A wireless LAN (WLAN) is a wireless local area network that links two or more
computers or devices using spread-spectrum or OFDM modulation technology based to
enable communication between devices in a limited area. This gives users the mobility to
move around within a broad coverage area and still be connected to the network.
3.4 Benefits
The popularity of wireless LANs is a testament primarily to their convenience,
cost efficiency, and ease of integration with other networks and network components.
The majority of computers sold to consumers today come pre-equipped with all necessary
wireless LAN technology. Benefits of wireless LANs include:
10
Convenience
The wireless nature of such networks allows users to access network resources
from nearly any convenient location within their primary networking environment (home
or office). With the increasing saturation of laptop-style computers, this is particularly
relevant.
Mobility
With the emergence of public wireless networks, users can access the internet
even outside their normal work environment. Most chain coffee shops, for example, offer
their customers a wireless connection to the internet at little or no cost.
Productivity
Users connected to a wireless network can maintain a nearly constant affiliation
with their desired network as they move from place to place. For a business, this implies
that an employee can potentially be more productive as his or her work can be
accomplished from any convenient location. For example, a hospital or warehouse may
implement Voice over WLAN applications that enable mobility and cost savings.
Deployment
Initial setup of an infrastructure-based wireless network requires little more than a
single access point. Wired networks, on the other hand, have the additional cost and
complexity of actual physical cables being run to numerous locations (which can even be
impossible for hard-to-reach locations within a building).
11
Expandability
Wireless networks can serve a suddenly-increased number of clients with the
existing equipment. In a wired network, additional clients would require additional
wiring.
Cost
Wireless networking hardware is at worst a modest increase from wired
counterparts. This potentially increased cost is almost always more than outweighed by
the savings in cost and labor associated to running physical cables.
Disadvantages
Wireless LAN technology, while replete with the conveniences and advantages
described above, has its share of downfalls. For a given networking situation, wireless
LANs may not be desirable for a number of reasons. Most of these have to do with the
inherent limitations of the technology.
Security
Wireless LAN transceivers are designed to serve computers throughout a structure
with uninterrupted service using radio frequencies. Because of space and cost, the
antennas typically present on wireless networking cards in the end computers are
generally relatively poor. In order to properly receive signals using such limited antennas
throughout even a modest area, the wireless LAN transceiver utilizes a fairly
considerable amount of power. What this means is that not only can the wireless packets
be intercepted by a nearby adversary's poorly-equipped computer, but more importantly,
a user willing to spend a small amount of money on a good quality antenna can pick up
12
packets at a remarkable distance; perhaps hundreds of times the radius as the typical user.
In fact, there are even computer users dedicated to locating and sometimes even cracking
into wireless networks, known as wardrivers. On a wired network, any adversary would
first have to overcome the physical limitation of tapping into the actual wires, but this is
not an issue with wireless packets. To combat this consideration, wireless networks users
usually choose to utilize various encryption technologies available such as Wi-Fi
Protected Access (WPA). Some of the older encryption methods, such as WEP are
known to have weaknesses that a dedicated adversary can compromise. (See main article:
Wireless security.)
Range
The typical range of a common 802.11g network with standard equipment is on
the order of tens of meters. While sufficient for a typical home, it will be insufficient in a
larger structure. To obtain additional range, repeaters or additional access points will
have to be purchased. Costs for these items can add up quickly. Other technologies are in
the development phase, however, which feature increased range, hoping to render this
disadvantage irrelevant
Reliability
Like any radio frequency transmission, wireless networking signals are subject to
a wide variety of interference, as well as complex propagation effects (such as multipath,
or especially in this case Rician fading) that are beyond the control of the network
administrator. One of the most insidious problems that can affect the stability and
reliability of a wireless LAN is the microwave oven. In the case of typical networks,
modulation is achieved by complicated forms of phase-shift keying (PSK) or quadrature
13
amplitude modulation (QAM), making interference and propagation effects all the more
disturbing. As a result, important network resources such as servers are rarely connected
wirelessly.
Speed
The speed on most wireless networks (typically 1-108 Mbit/s) is reasonably slow
compared to the slowest common wired networks (100 Mbit/s up to several Gbit/s).
There are also performance issues caused by TCP and its built-in congestion avoidance.
For most users, however, this observation is irrelevant since the speed bottleneck is not in
the wireless routing but rather in the outside network connectivity itself. For example, the
maximum ADSL throughput (usually 8 Mbit/s or less) offered by telecommunications
companies to general-purpose customers is already far slower than the slowest wireless
network to which it is typically connected. That is to say, in most environments, a
wireless network running at its slowest speed is still faster than the internet connection
serving it in the first place. However, in specialized environments, higher throughput
through a wired network might be necessary. Newer standards such as 802.11n are
addressing this limitation and will support peak throughput in the range of 100-200
Mbit/s.
3.5 Types of Wireless LANs :
Peer-to-peer
Peer – to - Peer or a-hoc wireless LAN
An ad-hoc network is a network where stations communicate only peer to peer
(P2P). There is no base and no one gives permission to talk. This is accomplished using
the Independence Basic Services Set (IBBS)
14
A peer-to-peer (P2P) network allows wireless devices to directly communicate
with each other. Wireless devices within range of each other can discover and
communicate directly without involving central access points. This method is typically
used by two computers so that they can connect to each other to form a network.
If a signal strength meter is used in this situation, it may not read the strength
accurately and can be misleading , because it registers the strength of the strongest signal,
which may be the closest computer.
802.11 specs define the physical layer (PHY) and MAC (Media Access Control)
layers. However, unlike most other IEEE specs, 802.11 includes three alternative PHY
standards: diffuse infrared operating at 1 Mbit/s in; frequency-hopping spread spectrum
operating at 1 Mbit/s or 2 Mbit/s. A single 802.11 MAC standard is based on
CSMA/CA(Carrier Sense Multiple Access with Collision Avoidence). The 802.11
speciation includes provisions designed to minimize collision. Because two mobile units
may both be in range of a common access point, but not in range of each other. The
802.11 has two basic modes of operation; Ad hoc mode enables peer-to-peer transmission
between mobile units. Infrastructure mode in which mobile units communicate through
an access point that serves as a bridge to a wired network infrastructure is the more
common wireless LAN application the one being covered. Since wireless communication
used a more open medium for communication in comparison to wired LANs, the 802.11
designers also included shared-key encryption mechanism: Wired Equivalent Privacy
(WEP) Wi-Fi Protected Access (WPA, WPA2), to secure wireless computer networks.
15
Bridge :
A bridge can be used to connect networks, typically of different types. A wireless
Ethernet bridge allows the connection of devices on a wired Ethernet network to a
wireless network. The bridge acts as the connection point to the Wireless LAN.
A Wireless Distribution System is a system that enables the wireless
interconnection of access points in an IEEE 802.11 network. It allows a wireless network
to be expanded using multiple access points without the need for wired back bone to
link them, as is traditionally required. The notable advantage of WDS over other
solutions is that it preserves the MAC addresses of client packets across links between
across links between access points.
An access point can be either a main, relay or remote base station. A main base
station is typically connected to the wired Ethernet. A relay base station relays data
between remote base stations, wireless clients or other relay stations to either a main or
another relay base station. A remote base station accepts connection from wireless clients
and passes them to relay or main stations. Connection between “clients” are made using
MAC address rather than by specifying IP assignments.
All base stations in a Wireless Distribution System must be configured to use the
same radio channel, and share WEP keys or WPA keys if they are used. They can be
configured to different services set identifiers. WDS also requires that every base stations
be configured to forward to others in the system.
16
WDS may also be referred to as repeater mode it appears to bridge and accept
wireless clients at the same time (unlike traditional bridging). It should be noted,
however, that throughput in this method is haved for all clients connected wirelessly.
When it is difficult to connect all of the access points in a network by wires, it is
also possible to put up access points as repeaters.
3.6 Roaming:
Roaming between Wireless Local Area Networks
There are 2 definitions for wireless LAN roaming:
Internal Roaming (1): The Mobile Stations (MS) moves from one access point (AP) to
another AP within a home network because the signal strength is too weak. An
authentication of MS via 802.1 x (e.g. with PEAP). The billing of QoS is in the home
network. A Mobile Station roaming from one access point to another often interrupts the
flow of data between the Mobile Station and an application connected to the network.
The Mobile Station, for instance, periodically monitors the presence of alternatives
access points (ones that will provide a better connection). At some point, based upon
proprietary mechanism, the Mobile Station decides to re-associate with an access point
having a stronger wireless signal. The Mobile Station, however, may lose a connection
with an access point before associating with another access point. In order to provide
reliable connection with applications, the Mobile Stations must generally include
software that provides session persistence.
17
External Roaming (2): The MS (client) moves into a WLAN of another Wireless
Internet Services Provider (WISP) and takes their services (Hotspot). The user can
independently of his home network use another foreign network, if this is open for
visitors. There must be special authentication and billing systems for mobile services in a
foreign network.
3.7 Related work
Several network architectures for integrating WLAN/UMTS systems have been
proposed. The proposed architectures can be grouped into two categories based on the
independence between the two networks [(14)], tight coupling and loose coupling. In the
loose coupling architecture, two networks are integrated beyond the Core Network (CN)
of UMTS. They are connected through gateways of the Internet. Communication between
the two networks are realized through standard IP protocols and the mobility of mobile
stations is managed through protocols such as Mobile IP. The loose coupling architecture
enables the two networks deployed independently but results in longer delay for signaling
and vertical handovers. In the tight coupling architecture, two networks are integrated at
UMTS’s CN, which has lower delay for signaling and vertical handover but has higher
implementation complexity. 3 GPP has been working on standardisation for integrating
cellular and WLAN systems in which interworking architecture and interworking
scenarios are desired. A policy based access control framework for cellular/WLAN
systems was proposed where policies are designed to archive load balancing, but details
of the proposed scheme such as performance analysis are not available.
18
CHAPTER 4
SYSTEM MODEL
Inspired by the Dual Mode Terminal (DMT) implemented a dual-mode UE
(DMUE) which can switch between UMTS and WLAN networks. Our DMUE is
different from the DMT in which our DMUE can be adopted in loose coupling
interworking systems where the UMTS and WLAN networks are connected by a router,
whereas DMT is only applicable in tight coupling interworking systems. The protocols in
UMTS and WLAN are independent. Packets arriving at the router are routed according to
the subnet address of each network. Once packets are delivered to the UMTS or WLAN
network, communication protocols of the corresponding network are then applied. The
main difference of UMTS and WLAN mobile stations is in the MAC and the physical
layers. In the DMUE, we created a new software layer, called IP switch layer, below the
IP layer and above UMTS’s GPRS Mobility Management (GMM) layer and WLAN’s
Address Resolution Protocol (ARP) layer. In the protocol stack of the DMUE, a network
access decision is made at the IP switch layer. Each DMUE has multiple pre-assigned IP
addresses with different subnets, and one IP address is called the primary IP address,
others are called the subordinate IP addresses. The primary IP address is the one and only
one IP address which is recognizable to the layers above IP switch layer. All the IP
addresses should be registered first such that each individual IP address has a unique
MAC address. Otherwise, an invalid IP address can cause packets to be discarded during
the packet transmission. Each AP of WLAN or Node B of UMTS has a unique IP subnet.
When a DMUE is roaming close to a Node B or an AP which has an identical subnet as
the DMUE’s, this Node B or AP becomes a connection candidate. When the IP switch
19
layer receives a PDU from the upper layer, the primary IP address in the packet header is
replaced by the IP address of a selected candidate at the IP switch layer according to
some specific network selection algorithm. When the IP switch layer receives a PDU
from the lower layer, the IP address is reinstated to the primary IP address. By this
method, the network access decision is completely transparent to the layers above the IP
switch layer. A network access decision can be made by either the DMUE itself or the
server. If the decision is made by the server, another entity is needed to act as a Common
Radio Resource Management (CRRM). Generally, a CRRM gathers the information on
the load and average packet delay of each base station and finds a best solution for the
system overall load balancing. Decisions are then broadcasted to all DMUEs through
base stations. In this paper, our focus is on the first method, i.e., the network access
decision is made by the DMUE. Instead of broadcasting network access decisions
directly to DMUEs, each base station broadcasts “virtual prices” to the neighboring
DMUEs. Since all DMUEs are independent entities, they may use different network
access decision algorithms based on the “virtual price” to choose an appropriate network.
In Figure 3, when a DMUE gets a “virtual price” packet from the lower layer, it will pass
this “virtual price” to “get_price_info” processor to make a network access decision.
4.1 Utility function for the UMTS:
In the UMTS networks, the admission control procedure is started when a new
service is requested. The request includes traffic’s QoS requirement such as data rate,
delay requirement, etc. After the UTRAN (RNC and Node B) of the UMTS network
receives the request, it will decide whether to grant the request based on the network
condition. The network condition is evaluated by the UTRAN through computing load
20
factors for uplink and downlink .In UMTS systems, load factors are always controlled to
be below than a threshold, say max ç ( max ç < 1). In most UMTS systems, 0.75 is a
value commonly used for both uplink and downlink threshold of max ç . In this paper, we
assume the uplink and downlink load factors have the same value of max ç . When a
service request comes, the UTRAN estimates the new resulting load factors of both
uplink and downlink.
Utility function for the WLAN:
A WLAN network has more bandwidth than a UMTS network does. A desirable
scenario in the integrated WLAN/UMTS networks would be that in a hotspot area, i.e.,
covered by WLAN, most of the stations are connected to the WLAN to enjoy the high
data rate of WLAN, while in the area outside hotspots, i.e., only covered by UMTS, static
or mobile stations are connected to UMTS to enjoy the large coverage of UMTS.
However, WLAN does not have explicit QoS control. When the WLAN is heavily
loaded, some QoS metric such as delay cannot be guaranteed. Moreover, as pointed out
in WLAN achieves less throughput when the network is saturated than that when the
network is not saturated. As the traffic load (number of stations) increases, severe
collisions occur, which results in that the stations can barely transmit a packet
successfully. Thus, the WLAN network should be closely monitored such that the
network is not overbusy. An indicator reflecting the WLANutilization adopted in the
literature is busyness ratio which is defined as the ratio of the time that the network is
sensed busy. So stations are admitted/handovered to a WLAN network only when its
busyness ratio b R is less than a threshold Given the current busyness ratio b R and its
21
upper bound th R , the utility function for WLAN indicating the available bandwidth to
accommodate new stations .
4.2 Network access decision:
Each AP of WLAN and Node-B of UMTS calculates its own utility function
(either periodically or triggered by events). The computed utilities are then broadcasted.
Once a station receives the utility from either UMTS or WLAN network, it will compare
the received utility with the utility of the host network to decide whether to switch
Network k. Notice that to avoid unnecessary oscillation, i.e., a station keeps switching
back and forth between two networks, a variable, utility_gap, is introduced such that only
when the utility of a candidate network is larger than the utility of host network by
utility_gap, the station changes the network. Secondly, as the network utility is
broadcasted, all stations will receive it almost at the same time as the transmission time in
the media is negligible. Then, all the stations will try to switch to the network that has
higher utility. As a result, the network that has higher utility before will be loaded very
quickly (i.e., low utility) and the network that has lower utility before will be depleted
(i.e., high utility), which leads the stations to switch the network again. To avoid this
undesirable network trembling, each station keeps a random number stay T . Each station
has to stay in a network for at least stay T seconds before switching to another network.
22
CHAPTER 5
UTILITY FUNCTION ALGORITHM
The algorithm is based on both UMTS and WLAN utility functions like current
busy ratio, data packet size and current uplink and downlink load factors and bandwidth.
The busy ratio of is associated by the above factors. The notations are R b is the Busy
Ratio and ηmax.
When the WLAN is heavily loaded, some QoS metric such as delay cannot be
guaranteed. Moreover, as pointed out in [11], WLAN achieves fewer throughputs when
the network is saturated than that when the network is not saturated. As the traffic load
(number of stations) increases, severe collisions occur, which results in that the stations
can barely transmit a packet successfully. Thus, the WLAN network should be closely
monitored such that the network is not overbusy. An indicator reflecting the WLAN
utilization adopted in the literature is busyness ratio, which is defined as the ratio of the
time that the network is sensed busy.
NETWORK ACCESS DECISION
Each AP of WLAN and Node-B of UMTS calculates its own utility function
(either periodically or triggered by events). The computed utilities are then broadcasted.
Once a station receives the utility from either UMTS or WLAN network, it will compare
the received utility with the utility of the host network to decide whether to switch
network.
23
1. Algorithm NetworkAccessDecision ()
2. {
3. if the utility comes from UMTS then
4. new_utility = f UMTS ;
5. else
6. new_utility = f WLAN ;
7. endif
8. new_network_id = the id of the network where the
new utility comes from;
9. if current_network_id = new_network_id then
10. current_utility = new_utility;
11. else
12. if new_utility > current_utility + utility_gap then
13. switch to the network with id being
new_network_id;
14. endif
15. endif
16. }
24
CHAPTER 6
3G Radio Network Controller
Third Generation (3G) is a generic name for technologies that support high-
quality voice, high-speed data and video in wireless cellular networks. In Europe, W-
CDMA/3G services are called the Universal Mobile Telephony System (UMTS). An
overview of the UMTS wireless network UTRAN (Terrestrial Radio Access Network) is
shown below.
The UMTS Terrestrial Radio Access Network (UTRAN) includes the Radio
Network Controller (RNC), the 3G Base stations (Node Bs) and the air interface (Tower)
to the mobile equipment (ME).
A brief description of the different network elements and interfaces in a UMTS
network is provided in the following table:
3G Network Functions
MSC The Mobile Switching Center (MSC) switch, including the Visitor Location
Register (VLR), is a switch that serves the Mobile Equipment (ME) in its
current location for Circuit Switched (CS) services.
GMSC The Gateway MSC (GMSC) switch serves the UMTS network at the point
where it is connected to the external CS network.
MGW The MSC and GMSC handle control Funtionality, but user data goes through
the Media Gateway (MGW), which performs the actual switching for user data
and network inter-working processing.
25
SGSN The Serving GPRS Support Node (SGSN) covers functions similar to the MSC
for packet data, including VLR type functionality
GGSN The Gateway GPRS Support Node (GGSN) connects the Packet-Switched (PS)
core network to other networks such as the Internet.
Node B A 3G Base station (Node B) handles radio channels, including the
multiplexing/demultiplexing of user voice and data information.
RNC The Radio Network Controller (RNC) is responsible for controlling and
managing the multiple base stations (Node Bs) including the utilization of
radio network services.
6.1. RNC Node B
The Radio Network Controller (RNC) is responsible for controlling and managing
the multiple base stations (Node Bs). The RNC also performs user data processing to
manage soft handoff and the utilization of radio network services. This processing
requires significant packet handling and manipulation, as well as complex higher-level
protocols. The density of the selector function is a major factor determining the capacity
of an RNC.
The rising cost of the infrastructure needed to provide sufficient capacity for
advanced mobile Internet services is a key challenge facing cellular operators and other
mobile telecommunications service providers. Wireless equipment manufacturers must
be able to add more flexibility and processing power to line cards without inflating
system cost or exceeding the power budget.
26
Specific design challenges for RNC include:
Increased application complexity to support evolving 3gpp standards
Market demands for more data services, requiring modular and reusable hardware
and software building blocks
Standardization requirements, such as Advanced TCATM, driven by reductions in
CAPEX/OPEX and time-to-market
Move from feature-based to cost-driven systems cost per channel and MIPS per
watt as the main selection criteria
27
6.2 Overview of GPRS and UMTS
GPRS and UMTS are evolutions of the global system for mobile communication
(GSM) networks. GSM is a digital cellular technology that is used worldwide,
predominantly in Europe and Asia. GSM is the world’s leading standard in digital
wireless communications.
GPRS is a 2.5G mobile communications technology that enables mobile wireless
service providers to offer their mobile subscribers packet-based data services over GSM
networks. Common applications of GPRS include the following: Internet access,
intranet/corporate access, instant messaging, and multimedia messaging. GPRS was
standardized by the European Telecommunications Standards Institute (ETSI), but today
is standardized by the Third Generation Partnership Program (3GPP).
UMTS is a 3G mobile communications technology that provides wideband code
division multiple access (CDMA) radio technology. The CDMA technology offers higher
throughput, real-time services, and end-to-end quality of service (QoS), and delivers
pictures, graphics, video communications, and other multimedia information as well as
voice and data to mobile wireless subscribers. UMTS is standardized by the 3GPP.
*Gateway GPRS support node (GGSN)—a gateway that provides mobile cell
phone users access to a public Data network (PDN) or specified private IP networks. The
GGSN function is implemented via Cisco IOS software on the Cisco 7200 series router or
on the Cisco Multi-Processor WAN Application Module (MWAM) installed in a Catalyst
6500 series switch or Cisco 7600 series Internet router. Cisco IOS GGSN Release 4.0 and
later provides both the 2.5G GPRS and 3G UMTS GGSN functions.
28
*Serving GPRS support node (SGSN)—connects the radio access network
(RAN) to the GPRS/UMTS core and tunnels user sessions to the GGSN. The SGSN
sends data to and receives data from mobile stations, and maintains information about the
location of a mobile station (MS). The SGSN communicates directly with the MS and the
GGSN. SGSN support is available from Cisco partners or other vendors.
6.3 Benefits
The 2.5G GPRS technology provides the following benefits:
Enables the use of a packet-based air interface over the existing circuit-switched
GSM network, which allows greater efficiency in the radio spectrum because the radio
bandwidth is used only when packets are sent or received.
Supports minimal upgrades to the existing GSM network infrastructure for
network service providers who want to add GPRS services on top of GSM, which is
currently widely deployed
Supports enhanced data rates in comparison to the traditional circuit-switched
GSM data service
Supports larger message lengths than Short Message Service (SMS)
Supports a wide range of access to data networks and services, including
VPN/Internet service provider (ISP) corporate site access and Wireless Application
Protocol (WAP).
In addition to the above, the 3G UMTS technology includes the following:
Enhanced data rates of approximately
144 kbps—Satellite and rural outdoor
384 kbps—Urban outdoor
29
2048 kbps—Indoor and low-range outdoor
Supports connection-oriented Radio Access Bearers with specified Qos enabling
end-to-end Qos
6.4 GGSN Interworking
GGSN Release 5.0 and later is a fully-compliant 2.5G and 3.5G GGSN that provides
the following features:
Release 99 (R99), Release 98 (R98) and Release 97 (R97)support and compliance
GTPv0 and GTPv1 messaging
IP Packet Data Protocol (PDP) and PPP PDP types
Cisco Express Forwarding (CEF) switching for GTPv0 and GTPv1, and for IP
and PPP PDP types
Support of secondary PDP contexts for GTPv1 (up to 11)
Virtual APN
VRF support per APN
Multiple APNs per VRF
VPN support
Generic routing encapsulation (GRE) tunneling
Layer 2 Tunneling Protocol (L2TP) extension for PPP PDP type
PPP Regeneration for IP PDP type
802.1Q virtual LANs (VLANs)
Security features
Duplicate IP address protection
PLMN range checking
30
Blocking of Foreign Mobiles
Anti-spoofing
Mobile-to-mobile redirection
Quality of service (QoS)
Support of UMTS classes and interworking with differentiated services (DiffServ)
Delay QoS
Canonical Qos
GPRS QoS(R97/R98) conversion to UMTS QoS (R99) and the reverse
Call Admission Control
Per-PDP policing
Dynamic address allocation
External DHCP server
External RADIUS server
Local pools
Anonymous access
RADIUS authentication and accounting
Accounting
Wait accounting
Per-PDP accounting
Authentication and accounting using RADIUS server groups mapped to APNs
3GPP vendor-specific attributes (VSAs) for IP PDP type
Transparent mode accounting
Class attribute
Interim updates
31
Session idle timer
Packet of Disconnect (PoD)
Dynamic Echo Timer
GGSN interworking between 2.5G and 3G SGSNs with registration authority
(RA) update from
2.5G to 2.5G SGSN
2.5G to 3G SGSN
3G to 3G SGSN
3G to 2.5G SGSN
Charging
Time trigger
Charging profiles
Tertiary charging gateway
Switchback to primary charging gateway
Maintenance mode
Multiple trusted PLMN IDs
GGSN-IOS SLB messaging
Session timeout
32
CHAPTER 7
ABOUT NS2:
Ns2 – Network Simulator Tool
Ns2 is a simulation tool built by South-California University and regenerated by ISI
and some others. The NS2 was built using three languages. TCL script, C++, C.
Here, TCL used for control, C++ for data and most of the header files were created
by C.
In NS2 Scripting, we can simulate a wired, wireless and Satellite networks using
ns script. And the ns scripted files are saved with the extension of *.tcl.
(TCL: Tool Command Language).
Ns Goals –
1. It supports the application for network research and education eg: Protocol design,
protocol comparison and traffic studies etc.
2. Provide a collaborative environment with freely distributed, open source and allow
easy comparison of similar protocols, Increase confidence in results. Possible to get
multiple levels of detail in on simulator.
3. It supports the FreeBSD, Linux, Solaris, Windows and Mac.
Ns Functionalities:
It supports the wired/wireless network simulations.
33
Wire world :
Router – DV, LS, PIM-SM
Transportation – TCP, UDP
Traffic Sources web, FTP, Telnet, CBR, Stochastic
Queuing disciplines – drop-tail, RED, FQ, SFQ,DRR
Qos – Intserv and Diffserv
In wired Network, we can create connection between two nodes through TCP as
well as UDP protocols and generating traffic using protocols like FTP ( File Transfer
Protocol), Telnet ( Tele Network), CBR ( Constant bit Rate)
And we can specify the queuing discipline also, the no of queuing disciplines are
in as2. they are drop-tail, RED, FQ,SFQ , DRR.
Wireless World:
Using Adhoc routing and Mobile IP.
Directed diffusion, sensor-MAC.
In Wireless Network also , we can create connection between two nodes through
TCP as well as UDP protocols and generating traffic using protocols like FTP ( File
Transfer Protocol), Telnet (Tele Network), CBR(Constant Bit Rate).
And we need to import some Wireless Supported classes for creating wireless
network.
Ns2 provides various utilities like Tracing and visualization.
34
The visualization achieve by NAM (Network AniMator) and NAM Editor
provides GUI interface to generate Ns scripts (Normally we use TCL script).
The Trace Analysis can achieve by XGraph.
7.1 Ns programming :
Create the event scheduler
Turn on tracing
Create network
Setup routing
Insert errors
Create transport connection
Create traffic
Transmit application-level data
Creating Event Scheduler
Create event scheduler
Set ns [ new Simulator]
Schedule events
$ns at <time><event>
<event>: any legitimate ns/tcl commands
$ns at 5.0 “finish”
Start scheduler
$ns run
35
Tracing and Monitoring I
o Packet tracing:
On all links : $ns trace-all [open out.tr.w]
On one specific link: $ns trace-queue $n0 $n1$tr
<Event> <time> <from> <to> <pkt> <size> -- <fid> <src> <dst> <seq> <attr>
+ 1 0 2 cbr 210 -------- 0 0.0 3.1 0 0
- 1 0 2 cbr 210 -------- 0 0.0 3.1 0 0
R 1.00234 0 2 cbr 210 --------- 0 0.0 3.1 0 0
We have new trace format
Evet tracing (support TCP right now)
Record “event” in trace file : $ns eventtrace-all
E 2.267203 0 4 TCP slow_start 0 210 1
Tracing and Monitoring II
Queue monitor
set qmon [$ns monitor-queue $n0 $n1 $q_f $sample_interval]
Get statistics for a queue
$qmon set pdrops_
Record to trace file as an optional
29.000000000000142 0 1 0.0 0.0 4 4 0 1160 1160 0
Flow monitor
set fmon [$ns_makeflowmon Fid]
$ns_attach-fmon $slink $fmon
$fmon set pdrops_
36
Tracing and Monitoring III
Visualize trace in nam
$ns namtrace-all [open test.nam w]
$ns namtrace-queue $n0 $n1
Variable tracing in nam
Agent/TCP set nam_tracevar_true
$tcp tracevar srrt_
$tcp tracevar cwnd_
Monitor agent variables in nam
$ns add-agent-trace $tcp $tcp
$ns monitor-agent-trace $tcp
$srm0 tracevar cwnd_
$ns delete-agent-trace $stp
7.2 Creating Network
Nodes
set n0 [$ns node]
set n1 [ $ns node]
Links and queuing
$ns <link_type>$n0 $n1 <bandwidth> <delay> < queue_type>
<link_type>:duplex-link, simplex-link
<queue_type>: DropTail, RED, CBQ, FQ, SFQ, DRR, diffserv RED
queues
37
Creating Network: LAN
$ns make-lan <node_list> <bandwidth> <delay> <II_type> <ifq_type>
<mac_type> <channel_type>
<II_type>:LL
<ifq_type>: Queue/Drop Tail,
<mac_type>: MAC/802_3
<channel_type>: Channel
Setup Routing
Unicast
$ns rtproto <type>
type>: Static, Session, DV, Cost, Multi-path
Multicast
$ns multicast (right after [new Simulator])
$ns mrtproto <type>
<type>: CrtMcast, DM,ST,BST
Other types of routing supported: source routing , hierarchical routing
Creating Connection and Traffic
UDP
set udp [new Agent/UDP]
set null [ new Agent/Null]
$ns attach-aget $n0 $udp
$ns attach-agent $n1 $null
$ns connect $udp $null
38
CBR
set src [ new Application/Traffic/CBR]
Exponential or Pareto on-off
set src { new Application/Traffic/Exponential]
set src [ new Application /Traffic/pareto]
Creating Connection and Traffic II
TCP
set tcp [ newAgent/TCP]
set tcpink [new Agent/TCPSink]
$ns attach-agent $n0 $tcp
$ns attach-agent $n1 $tcpsink
$ns onnect $tcp $tcpsink
FTP
set ftp [ new Application/FTP]
$ftp attach-agent $tcp
Telnet
set telnet [ new Application/Telnet]
$telnet attach-agent $tcp
39
7.3 ns→nam Interface
Color
Node manipulation
Link manipulation
Topology layout
Protocol state
nam Interface : color
Color mapping
$ns color 40 red
$ns color 41 blue
Color ↔ flow id association
$tcp0 set fid_40 ;# red packets
$tcp 1 set fid_41 ;# blue packets
nam interface : Nodes
color
$node color red
Shape (can’t be changed after sim starts)
$node shape box ;#circle,box,hexagon
Marks (concentric “shapes”)
$ns at 1.0 “$n0 add-mark m0 blue box”
$ns at 2.0 “$n0 delete-mark m0”
Label (single string)
40
$ns at 1.1 “$n0 label \”web cache 0\””
nam Interface : Links
Color
$ns duplex-link-op $n0 $n1 color “green”
Label
$ns duplex-link-op $n0 $n1 label “abced”
Dynamics (automatically handled)
$ns rtmodel Deterministic {2.0 0.9 0.1} $n0 $n1
Asymmetric links not allowed
nam Interface: Topo Layout
“Manual “ layout : specify everything
$ns duplex-link-op $n(0) $n(1) orient right
$ns duplex-link-op $n(1) $n(2) orient right
$ns duplex-link-op $n(2) $n(3) orient right
$ns duplex-link-op $n(3) $n(4) orient 60 deg
Annotation and Animation Rate
Add textual explanation to your simulation
$ns at 3.5 “$ns trace-annotate \”packet drop\””
set animation rate
$ns 0.0 “$ns set-animation-rate 0.1 ms”
41
CHAPTER 8
Simulation Results
In the simulation scenario, we create a UMTS network with one Node B and a
WLAN with one AP DMUEs in the intersection coverage area of the two networks. Each
DMUE has two IP address, one is in the UMTS subnet 192.168.6.0, the other is in the
WLAN subnet 192.168.5.0. An application of UDP video uploading from each DMUE to
the server is applied. Each video frame has size 17280 bytes, and a constant inter-arrival
time 4 seconds. All DMUEs enter the network between 0 and 200 seconds. The total
simulation time is 3600 seconds.
In Case 1, each UE randomly select either UMTS or WLAN and initiates a
connection. Admission to the UMTS cell is done based on the load factor as implemented
in OPNET UMTS module. There is no specific admission control in WLAN, and any
user can try to share the bandwidth as specified in the 802.11 protocol. No switching
between the two networks is performed.
In Case 2, each DMUE randomly select either UMTS or WLAN and initiates a
connection as in Case 1. However, in this case, switching,i.e., vertical handovers are
performed based on the utility values as discussed. As a result, some of the DMUEs
initially connected to the UMTS network switch to the WLAN network.
The DMUE’s uplink transmit load in Case 2 is displayed in Figure 4. We notice
that vertical handovers are done from UMTS to WLAN network since the utility value of
the latter is larger than that of the former,i.e., the WLAN has a larger remaining
42
bandwidth. From the simulation result shown in Figure 5, we see that the overall
throughput measured at the server with utility based approach in Case 2 is much larger
than Case 1. At the end of the simulation, in Case 1, all five UEs still reside in the WLAN
network but only one UE resides in the UMTS network, other four are all dropped
because UMTS has a relatively small capacity, and it is not able to accommodate all five
UEs. In Case 2, nine DMUEs reside in the WLAN network, and none resides in the
UMTS network. Among the previous five DMUEs assigned to the UMTS network, four
successfully switch to the WLAN network and the other one was not admitted by the
UMTS network, four successfully switch to the WLAN network and the other one was
not admitted by the UMTS network in the initiation due to insufficient capacity. One may
argue that the WLAN-first algorithm, i.e., try to connect to WLAN if available, should
work even better. Whenthe total capacity of UMTS cells sharing the coverage area with
the WLAN is relatively small as in our simulation scenario, it may be true. But in reality,
multiple UMTS cells have overlapping area and the total capacity can be close to the
capacity of WLAN. In this case, it is not obvious whether the WLAN-first algorithm
performs well. Finally, in Case 1 of our simulation, either of the networks is selected with
59% resulting in very poor performance due to the unbalanced capacities of the two
networks. Without having capacity information, 50% of random selection seems to be a
reasonable choice by any UE.
43
44
45
WLAN / UMTS Interlink
46
CHAPTER 9
CONCLUSION
In this paper, we designed a dual-mode mobile station module DMUE which works
in the WLAN/UMTS interworking system. Based on the DMUE design, we proposed a
utility-based access control frame work for integrated WLAN/UMTS system. In our
frame work, the UMTS’s UTRAN and the WLAN’s AP measure their respective network
conditions and reflect network conditions numerically by dynamically calculating
utilities. Each network’s utility is broadcasted to all DMUEs. DMUE’s network access
decision is made by comparing the received utilities. The simulation results using NS-2
show that our proposed scheme performs significantly better than the reference one. Our
developed models are not yet available NS-2 community, but will be made available after
further analysis is performed.
47
CHAPTER 10
FEATURE IMPLEMENTATION
Overview:
Demand for wireless LAN hardware has experienced phenomenal growth during
the past several years, evolving quickly from novelty into necessity. As a measure of this
expansion, WLAN chipset shipments in 2005 surpassed the 100-million-unit mark, a
more than tenfold increase from 2001 shipments of less than 10 million units.
Thus far, demand has been driven primarily by users connecting notebook
computers to networks at work and to the Internet at home as well as at coffee shops,
airports, hotels, and other mobile gathering places. As a result, Wi-Fi® technology is
most commonly found in notebook computers and Internet access devices such as routers
and DSL or cable modems. In fact, more than 90 percent of all notebook computers now
ship with built-in WLAN.
he growing pervasiveness of Wi-Fi is helping to extend the technology beyond the
PC and into consumer electronics applications like Internet telephony, music streaming,
gaming, and even photo viewing and in-home video transmission. Personal video
recorders and other A/V storage appliances that collect content in one spot for enjoyment
around the home are accelerating this trend.
48
Wi-Fi® Standards Comparison:
The first WLAN standard to become accepted in the market was 802.11b, which
specifies encoding techniques that provide for raw data rates up to 11 Mbps using a
modulation technique called Complementary Code Keying, or CCK, and also supports
Direct-Sequence Spread Spectrum, or DSSS, from the original 802.11 specification. The
802.11a standard, defined at about the same time as 802.11b, uses a more efficient
transmission method called Orthogonal Frequency Division Multiplexing, or OFDM.
OFDM, as implemented in 802.11a, enabled raw data rates up to 54 Mbps. Despite its
higher data rates, 802.11a never caught on as the successor to 802.11b because it resides
on an incompatible radio frequency band: 5 GHz versus 2.4 GHz for 802.11b.
Note: All of the WLAN standards provide for multiple transmission options,
so that the network can drop to lower (albeit easier to maintain) data rates as
environmental interference challenges communications. In the most favorable
circumstances, 802.11a and 802.11b support data rates up to 54 Mbps and 11 Mbps
respectively.)
In June 2003, the IEEE ratified 802.11g, which applied OFDM modulation to the
2.4-GHz band. This combined the best of both worlds: raw data rates up to 54 Mbps on
the same radio frequency as the already popular 802.11b. WLAN hardware built around
802.11g was quickly embraced by consumers and businesses seeking higher bandwidth.
In fact, consumers were so eager for a higher-performing alternative to 802.11b that they
began buying WLAN client and access-point hardware nearly a year before the standard
was finalized.
49
Today, the vast majority of computer network hardware shipping supports
802.11g. Increasingly, as technology improves and it becomes easier and less costly
tosupport both 2.4 GHz and 5 GHz in the same chipset, dual-band hardware is becoming
more commonplace. Much of the WLAN client hardware available today, in fact,
supports both 802.11a and 802.11g.
A similar scenario to the draft 802.11g phenomenon is now unfolding with
802.11n. The industry came to a substantive agreement with regard to the features to be
included in the high-speed 802.11n standard in early 2006. And though it will likely be
2007 before the standard is ratified, the specification is stable enough for draft-n Wi-Fi
cards and routers to already be making their way to store shelves.
IP BASED CORE NETWORK
50
Table 1. Major Components of Draft 802.11n
Feature DefinitionSpecification
Status
Better OFDMSupports wider bandwidth & higher code rate to bringmaximum data rate to 65 mbps
Mandatory
Space-DivisionMultiplexing
Improves performance byparsing data into multiple streams transmitted through multiple antennas
Optional forup to fourspatialstreams
Diversity
Exploits the existence of multiple antennas to improve range and reliability. Typically employed when the numberof antennas on the receiving end is higher than the number of streams being transmitted.
Optional forup to fourantennas
MIMO PowerSave
Limits power consumption penalty of MIMO by utilizingmultiple antennas only onas-needed basis
Required
40 MHzChannels
Effectively doubles data rates by doubling channel width from 20 MHz to 40 MHz
Optional
Aggregation
Improves efficiency by allowing transmission bursts of multiple data packets between overhead communication
Required
ReducedInter-frameSpacing(RIFS)
One of several draft-n features designed to improve efficiency. Providesa shorter delay between OFDM transmissions than in 802.11a or g.
Required
GreenfieldMode
Improves efficiency by eliminating support for 802.11a/b/g devices in an all draft-n network
Currentlyoptional
51
Table 2. Primary IEEE 802.11 Specifications
802.11a 802.11b 802.11g 802.11n
StandardApproved
July 1999 July 1999 June 2003 Not yet ratified
Maximum DataRate
54 Mbps 11 Mbps 54 Mbps 600 Mbps
Modulation OFDM DSSS or CCKDSSS or CCKor OFDM
DSSS or CCK orOFDM
RF Band 5 GHz 2.4 GHz 2.4 GHz 2.4 GHz or 5 GHz
Number ofSpatialStreams
1 1 1 1, 2, 3, or 4
Channel Width 20 MHz 20 MHz 20 MHz 20 MHz or 40 MHz
52
REFERENCES:
1. OPNET network simulator, http://www.opnet.com/.
2. IEEE 802.11 WG, Part 11:Wireless LAN Medium Access Control (MAC) and
Physical Layer (PHY) specification, Standard, IEEE, Aug.1999.
3. IEEE 802.11b WG, Part 11: Wireless LAN Medium Access Control (MAC) and
Physical Layer (PHY) specification: High-speed Physical Layer Extension in the
2.4 GHz Band, IEEE, Sep. 1999.
4. IEEE 802.11a WG, Part 11: Wireless LAN Medium Access Control (MAC) and
Physical Layer (PHY) specification: High-speed Physical Layer Extension in the
5 GHz Band, IEEE, Sep. 1999.
5. IEEE 802.11g, Further Higher-Speed Physical Layer Extension in the 2.4 GHz
Band, 2003.
6. 3GPP. 3rd Generation partnership Project; Technical Specification Group Radio
Access Network; RRC Protocol Specification for Release 1999. Techinical
Specification 3G TS 25.331 version 3.5.0 (2000- 12),2000.
7. 3GPP TK 22.934, Feasibility study on 3GPP system to wireless local area
network (WLAN) interworking, v. I .0.0, Release 6, Feb. 2002.
53
8. 3GPP, Group Services and System Aspects; 3GPP Systems to Wireless Local
Area Network (WLAN) Interworking; System Description (Release 6), TS
23.234, v. 6.2.0, Sept. 2004.
9. W. Song, W. Zhuang, and Y. Cheng, Load Balancing for Cellular/WLAN
Intergrated Networks, IEEE Network, issue 1,pp.27- 33, 2007.
10. Giuseppe Bianchi, Performance Analysis of the IEEE 802.11 Distributed
Coordination Function, IEEE Journal on Selected Areas in Communications, vol.
18, no.3, March 2000.
11. H. Zhai, X. Chen, and Y. Fang, How Well Can the IEEE 802.11 Wireless LAN
Support Quality of Service, IEEE Trans. Wireless Commun, vol. 4, no. 6, Nov.
2005, pp. 3084C94.
12. R. Agrawal, V. Subramanian and R. Berry, Joint Scheduling and Resource
Allocation in CDMA Systems, Proc. of 2nd Workshop on Modeling and
Optimization in Mobile, Ad Hoc, and Wireless Networks WiOpt 04), Cambridge,
UK, March 24-26, 2004.
13. J. Huang, V. Subramanian, R. Agrawal, and R. Berry, Downlink Scheduling and
Resource Allocation for OFDM Systems, Conference on Information Sciences
and Systems (CISS), Princeton University, NJ, USA, March 2006.
14. M. Buddhikot, G. Chandranmenon, S. Han, Y. W. Lee, S. Miller and L.
Salgarelli, Integration of 802.11 and Third-Generation Wireless Data Networks,
Proc. IEEE INFOCOM, Apr. 2003.
54
15. F. Siddiqui,S. Zeadally and S. Fowler, A Novel Architecture for Roaming
between 3G and Wireless LANs, 1st International Conference on Multimedia
Services Access Networks, MSAN’05, 2005.
16. H. Holma, A. Toskala, WCDMA for UMTS Radio Access for Third Generation
Mobile Communications, John Wiley & Sons, 3rd edition, 2004.
55
TABLE OF CONTENTS
CHAPTER
NO.TITLE
PAGE
NO
ABSTRACT iii
ACKNOWLEDGEMENT iv
LIST OF FIGURES AND TABLES vii
LIST OF ABBREVATIONS viii
1 INTRODUCTION 1
1.1 Existing System and Proposed System 3
2
2.1
UMTS
Features
4
5
3
3.1
3.2
3.3
3.4
3.5
3.6
3.7
3G WIRELESS NETWORK ARCHITECTURE
Radio Access Core Network
UTRN
Wireless LAN
Benefits
Types of Wireless LAN
Roaming
Related Works
7
7
8
10
10
14
17
18
4
4.1
4.2
SYSTEM MODEL
Utility function for UMTS/WLAN
Network Access Decision
19
20
22
5 UTILITY FUNCTION ALGORITHM 23
6
6.1
6.2
6.3
6.4
3G RADIO NETWORK CONTROLLER
RNC Node B
Overview of GPRS and UMTS
Benefits
GGSN Inter Working
25
26
28
29
30
56
7
7.1
7.2
7.3
ABOUT NS2
NS2 Programming
Creating Network
Nam Interface
33
35
37
40
8 SIMULATION RESULTS 42
9 CONCLUSIONS 47
10 FUTURE WORK 48
REFERENCES 53
57
LIST OF FIGURES AND TABLES
FIGURE NO.
CAPTION PAGE NO
1 UMTS-WLAN Interworking Architecture 8
2 UMTS Network Architecture 9
3 UTRN 10
4 Roaming Scinario 27
5 IP based Core Network 50
6 Routing of Mobile calls to CS or PSTN (3GPP) 52
TABLES
1 3G Network Functions 25
2 Major Components of Draft 802.11n 51
3 Primary IEEE 802.11 Specifications 52
58
LIST OF ABBREVATIONS:
RNC Radio Network Controller
RNS Radio Network Subsystem
RRC Radio Resources Control (3GTS 25.331)
SGSN Serving GPRS Support Node
SLR Source Local Reference (SCCP)
DLR Destination Local Reference (SCCP)
SCCP Signaling Connection Control Part (ITU-T Q.710 – Q714)
SM Session Management
SMS Short Message Services
SRNC Serving Radio Network Controller
SSCOP Service Specific Connection Oriented Protocol (ITU-T Q.2110)
TBF Temporary Block Flow
TCP Transmission Control Protocol
TLLI Temporary Logical Link Identifier
UDP User Datagram Protocol
UMTS Universal Mobile Telecommunication System for the time beyond
the year 2000
UTRAN UMTS Terrestrial Radio Access Network
VCI Virtual Channel Identifier
VPI Virtual Path Identifier
W-CDMA Wideband Code Division Multiple Access
59
60