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Chapter 2: Literature Review

2.1 Introduction

The main purpose of bandwidth utilization efficiency is to provide services so that users

can get higher data rates and wider coverage. However there is no single network that can

provide this kind of services [30]. 4G network is expected to integrate LAS-CDMA,

OFDM, MC-CDMA, UWB and Network-LMDS so that higher data rates and wider

coverage can be achieved [31]. In this integration, the users will be served by either one

of those networks. As a result, an important problem occurred in which in these

overlapping areas most of the network resources is not fully utilized since only one of

those networks serve the users.

The bandwidth utilization efficiency is so important for operators, because the

wireless communication cost and their profit are based on the network resources. Thus,

how to get the highest benefit from the available network resources is a key issue in the

wireless communication networks. In the research, we focus on the two bandwidth

integration of WLAN and CDMA2000 networks to efficiently utilize the two network

resources.

This chapter reviews the relevant literature to explain the existing researches. The

flow of the relevant literature is presented in the Figure 2-1 which focuses on the

evolution of wireless communication networks and bandwidth utilization efficiently for

4G. We have divided this chapter into eight sections. In the first section, we give a

general introduction. Section two discusses the developed evolution of wireless mobile

communication networks. Section three highlights the fourth generation wireless mobile

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internet networks. WLAN protocol and frame will be presented in section four and the

PPPoE protocol in section five. In section six, we present the relevant literature on

bandwidth utilization. The related researches will then be presented in section seven

before we give the conclusions in section eight.

Figure 2-1: The Flow of the Literature

2.2 Evolution of Wireless Networks

The first generation (1G) wireless mobile communication system was an analog system

which was used for public voice service with the speed up to 2.4kbps [32]. The second

generation (2G) is based on digital technology and infrastructure network [33]. As

compared to the first generation, the second generation can support text messaging. The

success and the growth in demand for online information via the internet prompted the

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development of cellular wireless system with improved data connectivity, which

ultimately lead to the third generation systems (3G) [34].

3G systems refer to the developing technology standards for the next generation of

mobile communications systems [35]. One of the main goals of the standardization

efforts of 3G is to create a universal infrastructure that is able to support existing and

future services. This requires that the infrastructure be designed so that it can evolve as

technology changes, without compromising the existing services on the existing networks.

Separation of access technology, transport technology, service technology and user

application from each other make this demanding requirement possible [36].

The goal of 3G wireless systems is to provide wireless data service with data rates of

144kbps to 384kbps in wide coverage areas, and 2Mbps in local coverage areas [37].

Possible applications included wireless web-based access, E-mail, as well as video

teleconferencing and multimedia services consisting of mixed voice and data streams.

Generally speaking, 3G means the third generation of wireless technology including

several features, which are enhanced roaming, broadband data services with video and

multimedia, superior voice quality, up to 2Mbps of always-on data services. Several

problems with current 3G are: the speed is still too slow for multimedia data, difficult to

roam globally and can not interoperate across networks. As a result, the 4th generation

(4G) wireless system has been proposed by academic researches and government projects.

The speeds of 4G can theoretically be promised up to 1Gbps. 4G is an evolution to move

beyond the limitations and problems of 3G [38].

2.3 The Forth Generation (4G) Wireless Networks

4G is a research item for next-generation wide-area cellular radio, which focuses on 4G

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technologies, 4G networks and 4G systems [39]. 4G technologies shall include three

basic areas of connectivity which are personal area networking (such as Bluetooth), local

high-speed access points on the network such as wireless LAN technologies and cellular

connectivity. Under this umbrella, 4G can provide services for a wide range of mobile

devices that support global roaming and each device will be able to interact with

internet-based information.

At the moment, many countries have established projects for 4G systems

development [40, 41]. However, the organization that first started this project is the

Defense Advanced Research Projects Agency (DARPA), which is the same organization

that first developed the wired internet [42].

Figure 2-2: 4G Technologies [42]

Figure 2-2 shows that 4G technologies integrate with different current existing and

future wireless network technologies including fixed wireless broadband, wireless LAN,

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3G-WCDMA and CDMA2000 to ensure that mobile node can have a freedom of

movement and seamless roaming from one technology to another. These will ensure that

mobile users can be supported by different technologies through a continuous and always

best connection as well.

Figure 2-3: 4G Networks [43]

Figure 2-3 shows that 4G networks can be supported by network connection like

Bluetooth, WiFi 802.11 family, WiMax 802.16 family, cellular and satellite networks [43

and 44]. Therefore, by integrating all of these networks, 4G can provide total coverage,

seamless roaming and best connected services. Each of these technologies will be briefly

explained in the following paragraph.

The Bluetooth is designed for personal area, which can cover theoretically 10 meters.

On a technical level, Bluetooth is an open specification for a cutting-edge technology that

enables short-range wireless connections between desktop and laptop computers and a

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host of other peripheral devices- on a globally available frequency band (2.4GHz) for

worldwide compatibility.

802.11 802.11b 802.11a 802.11g

Raw Data Rate (Mbps)

1,2 1,2,5.5,11 6,9,12,1824,36,48,54

1,2,5.5,6,9,11,12,22,24,33,36,54

Frequency(Hz) 2.4G 2.4G 5G 2.4G

Available Spectrum

83.5MHz 83.5MHz 300MHz 83.5MHz

Modulation Encoding

FHSS/DSSS/PSK/PPM

DSSS/CCK OFDM DSSS/OFDM

Max MSDU 2304 2304 --- ---

Table 2-1: Comparison of IEEE 802.11 WLAN Standards [43]

The WiFi 802.11 family is designed for local area, which can cover up to 100 meters.

The IEEE 802.11 [45] has become wireless Ethernet networking technology standard,

and the products based on the standard have been made. To ensure interoperability

between these products, an organization named Wi-Fi was created. The original IEEE

802.11 standard and each of its supplemental standards are shown in Table 2-1, which

provides a basic overview of the current versions of the 802.11 technologies [46]. The

IEEE 802.11 family of WLANs has been widely utilized around the world.

The WiMax is designed for metropolitan area, which can cover few kilometers.

WiMAX, the Worldwide Interoperability for Microwave Access, is a telecommunications

technology aimed at providing wireless data over long distances in a variety of ways,

from point-to-point links to full mobile cellular type access. It is based on the IEEE

802.16 standard, which is also called WirelessMAN. The name WiMAX was created by

the WiMAX Forum, which was formed in June 2001 to promote conformance and

interoperability of the standard [47]. The IEEE 802.16d stands for fixed WiMax which

cannot be handoffed from one base station to another, whereas the IEEE 802.16e stands

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for mobile WiMax which can roam/handoff between different base stations.

The cellular networks are designed for wide area, which can cover any surface on

earth. It has experienced three generation in its life. 4G integrate three standards

(WCDMA, CDMA2000 and TD-SCDMA) of 3G into CDMA2000.

Figure 2-4 shows that the 4G system is an all IP-based wireless mobile network

system [48]. The features of 4G system may be summarized with one word—integration

[49]. The 4G systems are about seamlessly integrating terminals, networks, and

applications to satisfy increasing user demands. The issues related with the integration

will be presented as follows.

4G terminal interfaces are quite different from current existing interfaces [50]. The

current existing terminal interfaces are related with keyboard, display, and tablet such as

PC and mobile phone. 4G terminal interfaces however will be based on speech, touch,

vision, soft button, etc. In addition, the enhanced interfaces of 4G terminals will have

multiple user interfaces, adaptive techniques such as smart antennas, software radio, and

smart transceivers to further enhance interoperability through simultaneous support of

several radio interfaces in a single terminal. These enhanced new interfaces can support a

terminal to roam across different air interface standards and to connect with different

wireless access points, such as Bluetooth, WLAN and CDMA2000, by exchanging

configuration software. Therefore, 4G terminals can monitor and interact with the

physical world to report human or environmental factors, and it will be aware of location

and context.

The main function of 4G networks is as a platform, on which terminals and

applications can rapidly exchange information. Some new techniques have been

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developed to achieve adaptability of 4G networks such as smart antennas, software radio,

and advanced base station. To make networks portable and adaptable, Ad hoc wireless

networks are deployed. It can dynamically share unlicensed radio spectrum. Network

reconfiguration is very important for seamless interconnection to mobile user. It can be

obtained by the reconfiguration of protocol stacks and programmability of network nodes.

Thus, when a channel condition change or a low or high data rate user appears, network

reconfiguration can adapt them dynamically. In addition, network resource is allocated

according to traffic load, channel condition, and service environment. Channel condition,

traffic load and service environment will be dynamically monitored and controlled via

techniques such as distributed control of network functionalities.

Figure 2-4: 4G Systems [50]

For applications, the most important thing is a user’s requirements, which can be

delivered in a way that the user preferred. Thus, adaptability will be one of the basic

requirements for mobile user applications, and because of the adaptability, the mobile

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user can move in various locations and speeds. There are some techniques used for

adaptability such as adaptive multimedia and unified messaging [51 and 52]. These

techniques can ensure the request services can be received by the mobile user, and run on

the mobile node through a most suitable form. In this case, the most efficient channel can

be selected after the application negotiates with the network based on the mobile node

request, such as WLAN channel or CDMA2000 channel. In order to adapt the different

network requirements and the varying traffic conditions, the request services must be

tolerable. Therefore, services and applications can be smoothly delivered across

multiple domains of operators and service providers.

The core features of 4G are diversity and adaptability of targets, leading to seamless

integration in order to support the most efficient application by the user’s demands. Thus,

the final requirements of 4G should fulfill the situation that if a consumer can do his work

at home or in his office while wired to the internet, then he/she must be able to do it

wirelessly in a fully mobile environment.

2.4 WLAN Protocol and Frame Structure

2.4.1 WLAN Protocol Structure

WLAN protocol only covers the medium access (MAC) and physical (PHY) layers like

the other 802.x LAN standards. Figure 2-5 shows the basic reference of the protocol

model [53 and 54]. The physical layer is subdivided into a physical layer convergence

protocol (PLCP) and the physical medium dependent (PMD) sublayers. The basic tasks

of the MAC layer are medium access, fragmentation of user data, and encryption. The

PLCP sublayer provides a carrier sense signal, called clear channel assessment (CCA),

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and provides a common PHY interface for the MAC that is independent of the

transmission technology. The PMD sublayer handles modulation and encoding/decoding

of signals. The function of data link layer is to fragment user data and encrypt them into

certain interfaces. In our research, the function of the proposed new protocol is to make a

choice of the two interfaces. The new protocol design is based on WLAN protocol frame

structure as in Figure 2-5.

Data Link Layer MAC SubLayer MAC Sublayer Management Entity

Station Management Entity Physical Layer

PLCP Sublayer PHY Sublayer Management Entity

PMD Sublayer

Figure 2-5: IEEE 802.11 Protocol Reference Modes [53]

2.4.2 WLAN Frame Structure

Figure 2-6 specifies the basic WLAN frame structure [53]. Each frame consists of the

following basic components:

� A MAC header, which comprises frame control, duration, address, and sequence

control information;

� A variable-length frame body, which contains information specific to the frame type;

� A frame check sequence (FCS), which contains an IEEE 32-bit cyclic redundancy

code (CRC).

Octets: 2 2 6 6 6 2 6 0-2312 4

Frame Control Duration/ID Address 1 Address 2 Address 3 Sequence Control Address 4 Frame Body FCS

MAC Header

Figure 2-6: IEEE 802.11 Frame Structures [53]

The primary responsibility of the WLAN frame is to control medium access, but it

can also provide optional support for roaming, authentication, and power conservation.

The basic services provided by the frame are the mandatory asynchronous data service

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and an optional time-bounded service. Our new protocol frame will be based on this

frame structure.

2.5 PPPoE Protocol

Beside the CDMA2000 and WLAN protocol, the PPP over Ethernet (PPPoE) protocol is

used to establish the internet session in our research [55]. The PPPoE protocol provides

the ability to connect a network of mobile node over a simple bridging access device to a

remote Access Concentrator. With this model, each mobile node utilizes its own PPP

stack and the user is presented with a familiar user interface. Access control, billing and

type of service can be done on a per-user, rather than a per-site.

PPPoE has two distinct stages. There is a discovery stage and a PPP session

stage. When a mobile node wishes to initiate a PPPoE session, it must first perform

discovery to identify the Ethernet MAC address of the peer and establish a PPPoE

SESSION_ID. To provide a point-to-point connection over Ethernet, each PPP session

must learn the Ethernet address of the remote peer, as well as establish a unique session

identifier. PPPoE includes a discovery protocol that provides this. While PPP defines a

peer-to-peer relationship, discovery is inherently a client-server relationship. In the

discovery process, a mobile node discovers an Access Concentrator (the server). Based

on the network topology, there may be more than one Access Concentrator that the

mobile node can communicate with. The discovery stage allows the mobile node to

discover all Access Concentrators and then will select one. When discovery completes

successfully, both the mobile node and the selected Access Concentrator have the

information they will use to build their point-to-point connection over Ethernet. The

discovery stage remains stateless until a PPP session is established. Once a PPP session is

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established, both the mobile node and the Access Concentrator must allocate the

resources for a PPP virtual interface.

The PPPoE packet is located in the data area of the Ethernet frame - Ether Type: In

PPPoE this indicates whether it contains a PPPoE-Discovery or a PPPoE-Session. It takes

the following values: 0x8863 – PPPoE Discovery deals with the search for a PoP (point

of presence) using Ethernet broadcast, the creation of a connection to it, and the

interruption of this connection. 0x8864 - PPPoE Session deals with the configuration and

control of the connection, for example, with the assignment of IP-addresses. The PPPoE

protocol structure shows in Figure 2-7 as follows:

4 8 16 32bit

Ver Type Code Session-ID

Length Payload

Figure 2-7: PPPoE Protocol Structure [55]

As the structure shown above, the functionality and the length will be listed as

follows:

• VER – the VER means the version of the PPPoE, which must be set to 0x1;

• TYPE – the type means the packet type, which must be set to 0x1;

• CODE – the code is defined for the PPP Discovery and PPP Session stages;

• SESSION_ID – the session_ID is an unsigned value in network byte order. Its

value is defined for Discovery packets. The value is fixed for a given PPP session

and, in fact, defines a PPP session along with the Ethernet SOURCE_ADDR and

DESTINATION_ADDR. A value of 0xffff is reserved for future use and MUST

NOT be used;

• LENGTH - The value, in network byte order, indicates the length of the PPPoE

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payload. It does not include the length of the Ethernet or PPPoE headers.

2.6 Bandwidth Utilization

2.6.1 Bandwidth Utilization Research in Wireless Mobile Networks

Wireless bandwidth is the width or capacity of a wireless communications channel, which

is measured in Herz (Hz). The actual wireless bandwidth size is the difference between

the lowest and highest frequency in the band, which determines how much information

can be transmitted at once [56].

The relative importance of bandwidth in wireless communications is that the size, or

bandwidth, of a channel will impact transmission speed [57]. With the number of mobile

internet users growing and accessing increasingly rich multimedia and interactive content

wirelessly, transmitting signals through multiple antennas to serve multiple users at the

same time are important.

One of the researches that discusses about bandwidth utilization is done by Dr.

Sangarapillai Lambotharan and his group in Loughborough University’s communication

department. His group is developing a technique to make better use of the available

spectrum, increase coverage and provide better services [58]. The purpose of their

research is to utilize wireless bandwidth efficiently in three different aspects i.e. to get

higher data rates, wider coverage and efficient network resources usage. As an example,

if there are two possible networks, i.e., cellular network and WLAN network that are

within coverage of the mobile users, handoff from the cellular network to the WLAN

network is the best solution in bandwidth utilization research.

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2.6.2 Bandwidth Utilization Research in 4G Wireless Mobile Internet

Networks

There is no single wireless network that can provide high data rates and wide coverage

for applications to a large number of mobile users [59]. 4G wireless mobile internet

networks integrates cellular communication systems and wireless LANs with fixed

internet network together to provide network connectivity in an efficient and scalable

way [60, 61, 62 and 63]. Many researches continue to evolve, which related with

integration of services [64 and 65], integration of access technologies [66] and integration

of protocols [67].

In [64], the authors present the convergence of cellular and WLAN technologies.

Their focuses are on the evolution of various radio technologies, and the evolution toward

pure IP-based networks, and the interworking of varied wireless access technologies. The

authors make the case that WLAN should not be perceived as a competitor or

replacement for mobile cellular systems, but rather a complementing component of the

network. In this research, they present the interworked network as three layers: the

cellular layer, the hot spot layer and the personal network layer. They identify the need

for a new medium access layer to interconnect the three layers and ensure transparent

delivery across this architecture.

In the research of [66], the user’s demand requirements provide by the location-based

services. Therefore, the integration of services is based on location technologies. The

location-based technology has reached today a satisfactory level of accuracy and

resolution. However, once the location information has been rendered available to the

user and/or the network, it could be exploited for other purposes than providing services

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to the user. Some works have shown how the location information can be used to improve

radio resource management or mobility management (i.e., horizontal handover) by

properly designed mechanisms [67]. However, the location information, together with the

knowledge of the user condition (e.g. distance, signal strength, et.), could also be used to

guarantee an optimized inter-system Radio Resource Management and efficient

integration of different RANs (Radio Access Networks). All of these researches are trying

to make the bandwidth utilization efficiently in 4G wireless mobile internet.

2.7 Related Works in 4G Networks

At the moment, researchers have been working to improve bandwidth utilization

efficiency in 4G wireless mobile internet works. In addition, the international bodies,

3GPP2 has issued the integrated architecture focusing on 4G networks [68]. However,

3GPP2 does not give any solution to interworking problems. In order to solve the

interworking problems, efficient multimode protocol architecture for complementary

radio interfaces in 4G networks was developed to integrate multiple protocols [69, 70 and

71]. These researches, however do not consider the QoS on the multi protocols

architecture. In order to improve the QoS, the researches in the CDMA2000-WLAN

Interworking has proposed several solutions [72, 73 and 74]. All of these related works

will be presented in the following sub-sections.

2.7.1 CDMA2000-WLAN Integration

4G will integrate all access networks for future network supplying higher data rates,

wider coverage and allowing global roaming. This integration however, introduces

interworking problem between the integrated networks. 3GPP2, the standardization

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organization of CDMA2000, has issued CDMA2000-WLAN integrated architecture [64].

These two technologies have complementary characteristics. The CDMA2000 network

can provide full mobility over a wide area network and mature management schemes

with moderate data rate. For example, CDMA2000 1x EV-DO can provide up to 3.1 Mb/s

in forward link and 1.8Mb/s in reverse link. On the other hand, WLAN can achieve

higher data rate at lower cost over local area coverage. IEEE 802.11b and 802.11g,

working in 2.4GHz frequency band, can support a data rate up to 11Mb/s and 54 Mb/s

respectively, while IEEE 802.11a can offer a data rate up to 54Mb/s in 5GHz frequency

band. The descriptions show that integrating them will allow CDMA2000 and WLAN

networks to complement each other, and will potentially provide cellular operators with

higher network bandwidth, wider network coverage, better user experience and richer

applications.

Figure 2-8 shows the reference model of CDMA2000 and WLAN interworking as

defined by 3GPP2. The PDIF (Packet Data Interworking Function) works as a gateway

and to protect resources and packet data services from unauthorized access in the

convergence architecture of CDMA2000-WLAN networks, in which is responsible for

the routing of packets to/from the mobile node (MN). It routes packets from MN to the

Internet. In addition, it will have the following features:

i. Allocates IP addresses to mobile nodes in WLAN network;

ii. Provides IP connectivity to CDMA2000 network and/or other external networks;

iii. Manages end-to-end tunnel between itself and mobile node;

iv. Enforces serving CDMA2000 policies, such as packet filtering and routing;

v. Supports user authentication and transfer of authorization policy information;

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vi. Supports Mobile IP functionalities;

Figure 2-8: CDMA2000-WLAN Interworking Model

In 3GPP2, there is no limitation on the type of IEEE 802.11 wireless access for

WLAN interworking. The purpose of interworking between CDMA2000 networks and

WLAN is to provide access to both CDMA2000 and WLAN networks simultaneously.

This will allow higher data rates and efficiently utilization of network resources.

Although 3GPP2 has issued the integrated architecture for the WLAN and

CDMA2000 networks, it does not give any solution about the interworking problem.

Research on multimode protocol for 4G networks has proposed a solution of

interworking problem which is presented in the following sub-section.

2.7.2 Multimode Protocol for 4G Networks

Whereas the 4G networks intend to issue a solution of “one radio interface fits all” [75],

the user demands require a multitude of solutions tailored for specific communication

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environments [76]. Current research efforts are therefore targeting the efficient realization

of a flexible radio interface and network architecture. In [75], multimode and unified

protocol architecture for complementary radio interfaces in 4G networks has been

presented. The article presented a protocol reference architecture that enables the efficient

integration of multiple modes in a complementary way, which facilitates the coexistence

and cooperation of different modes in all mode nodes of future wireless mobile internet

networks. The article focuses on multimode reference architecture which is related with:

• A proof of concept and its evaluation are presented as the example of relay-based

4G networks and IEEE 802.16 (WiMAX);

• Optimized switching between modes and coexistence of different modes is

realized;

• The separation of protocol software into generic and specific parts is the basis for

the multimode protocol reference architecture; and

• The realization of a flexible radio interface based on generic protocol functions of

the data link layer is illustrated.

In the research of [75], the article presented an example of convergence architecture

of IEEE 802.16 and data link layer protocols to optimize switching between modes and

coexistence of different modes. The basis of the protocol for the multimode protocol

reference architecture is separated into generic and specific parts. The generic part is

assumed to be an identified set of common functions from integrating radio interfaces.

The specific part is unique to a certain kind of radio interface mode and can not be found

in any other mode. Both of the generic and specific parts form together a complete

protocol layer. In the article, the authors have defined both generic and specific protocol

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stack functions, and separation of them through parameterization.

In [76], the multimode protocol for 4G networks has given a solution for the

interworking problem, but it does not consider the quality of service. These solutions are

proposed by several researches and are presented in the following sub-section.

2.7.3 QoS Based Handoff for CDMA2000-WLAN Interworking

Many researches [77, 78 and 79] have focused on the interworking problems in the

integrated architecture of CDMA2000-WLAN. However, the interworking with

guaranteed QoS remains a challenge under the integrated architecture. These researches

can be divided into two cases. In [77], resource management for network interworking is

considered. This case simply separates voice and data service for admission control, in

which it does not consider the QoS degradation in the new network. The second case is

QoS based techniques for CDMA2000-WLAN interworking [78 and 79]. In the research

of [78], the authors proposed a solution for smart seamless handoff with QoS guarantee

which mobile nodes conduct the QoS negotiation with the new network during handoff.

Based on the results, on QoS requirements of current sessions and on local policies,

mobile nodes could transfer selected sessions to the new interface. Decisions are notified

to network side by mobile IP registration request messages. However, mobile IP is

utilized to achieve service continuity over heterogeneous networks. A new enhancement

on mobile IP is employed to guarantee the QoS requirement for diverse services.

In [79], the authors assumed that dual-interfaced mobile node can support both

CDMA2000 specifications and WLAN air interface. It should also support mobile IP to

achieve session continuity. In a WLAN interworking scenario, WLAN access is

authenticated by the AAA server that could be located in the CDMA2000 serving

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network or in the home network. Thus, the interworking with QoS guarantee can be as

follows:

• Before handoff, mobile node detects the signal of a new access network; it will try

to attach the new access network according to a particular trigger scheme. In this

case, mobile node supports the make-before-break scheme;

• During handoff, mobile node negotiates QoS with the new access network

through the new network interface, while keeping ongoing sessions in the current

network. After QoS negotiation, mobile node sends out a mobile IP Registration

Request message to update its binding in home agent. Mobile node may then

break the previous network connection. To achieve a better QoS experience,

mobile node transfers parts of the ongoing sessions to the new access network

based on the QoS consideration. This could be done by Service Differentiation

Information (SDI) extension of mobile IP Registration Request (RRQ) message.

Mobile node may indicate the transferred session description in the SDI extension

of RRQ to home agaent. The SDI extension includes parameters that define

sessions (e.g., Source/Destination IP Address, Source/Destination Port, DSCP,

etc.); and

• After handoff, home agent stores the SDI in the related binding cache entry. When

home agent receives packets from the external network, it can determine the

routing of these packets based on the binding information and SDI. After

receiving mobile IP Registration Reply (RRP) message, mobile node switches the

selected sessions to the new access network.

From the handoff steps above, we can see that the QoS based handoff for

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CDMA2000-WLAN interworking has experienced three phases: before handoff, during

handoff and after handoff. The scheme has considered the QoS guarantee to achieve the

better services from CDMA2000 to WLAN.

The disadvantage to the scheme is that the mobile node is served by the WLAN

network after handoff. Meanwhile, the CDMA2000 network is serving for few users.

Since WLAN bandwidth is much wider than CDMA2000 network, in order to get higher

data rates, most of mobile nodes will handoff to WLAN from CDMA2000.

2.8 Conclusions

In this chapter, we started with the presentation of a historical perspective of the 3G and

4G wireless cellular networks, and then, section 2.2 and 2.3 explained the basic

techniques involved in the 4G wireless mobile internet networks. The 4th Generation (4G)

wireless mobile internet networks will integrate current existing networks (i.e., IPv6,

OFDM, CDMA2000, WCDMA and TD_SCDMA) and Wi-Fi (i.e., Wireless LAN)

networks with fixed internet to support wireless mobile internet as the same quality of

service as fixed internet, which is an evolution not only to move beyond the limitations

and problems of 3G, but also to enhance the quality of services, to increase the bandwidth

and to reduce the cost of the resources. The discussion than introduces the evolution of

wireless networks and the 4G wireless mobile internet networks.

Handoff/roaming are not easy between different networks and in the integrated area

of 4G wireless mobile internet network. It is necessary to integrate these networks to

provide efficient services for mobile users. The discussion of the related researches has

been than introduced.

In order to get higher data rates, the one of way is utilizing 4G bandwidth efficiently.

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The discussion of bandwidth utilization than introduces the bandwidth utilization in 4G

wireless mobile internet networks. Following the discussion, it results in that our research

focusing on the bandwidth integration of CDMA2000 and WLAN networks. We propose

Dual-bandwidth data path between CDMA2000 and WLAN networks.

This chapter has also discusses and presents the purposes of bandwidth utilization

including to increase data rates, coverage and to make network resource utilize efficiently.

3GPP2 has issued the integrating architecture for 4G networks in order to increase the

data rates and coverage. The researches of multimode protocol for 4G networks and QoS

based handoff for CDMA2000-WLAN interworking have given a solution for the

bandwidth utilization efficiency as well.

We explained WLAN protocol and frame structure in section 2.4. In section 2.5, we

have presented the PPPoE protocol and its structure. Section 2.6 provided bandwidth

utilization including wireless bandwidth utilization and bandwidth utilization in 4G

wireless mobile internet networks. The current existing researches related with bandwidth

utilization are presented in section 2.7. Finally, we give a conclusion for this chapter in

section 2.8.

In order to operationalize the bandwidth utilization efficiency, the first we need to

develop the Dual-bandwidth data path design and the Bandwidth Optimization Control

Protocol design. Further discussion on this suggestion will be designed in the following

chapter 3.