Bhanuprakash123

4G CELLULAR NETWORK WITH WIMAX

A SEMINAR REPORT ON

4G CELLULAR ETWORK WITH WiMAX Submitted to

JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY, ANANTHAPUR

In partial fulfilment of the requirement for the award of degree of

BACHELOR OF TECHNOLOGY

IN

ELECTRONICS AND COMMUNICATION ENGINEEING

BY

K.LAKSHMI BHANU PRAKASH REDDY 11691A0445

DEPARTMENT OF ELECTRONICS AND COMMUNICATION ENGINEERING

MADANAPALLE INSTITUTE OF TECHNOLOGY AND SCIENCE,

(Approved by AICTE, New Delhi, Affiliated to JNTU, Ananthapur)

Madanapalle–517325, Andhra Pradesh.

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MADANAPALLE INSTITUTE OF TECHNOLOGY & SCIENCE

(Approved by AICTE, New Delhi, Affiliated to JNTU, Ananthapur)

DEPARTMENT OF ELECTRONICS AND COMMUNICATION ENGINEERING

BONAFIDE CERTIFICATE

This is to certify that this technical seminar report “4G CELLULAR ETWORK WITH WiMAX”

submitted in partial fulfilment of the requirement for the award of the degree for bachelor technology in electronics and communication engineering is a result of the bonafide work carried out by K.LAKSHMI BHANU PRAKASH REDDY (11691A0445). He is bonafide student of this college studying IV year B.Tech during academic year 2011-2012.

Prof. A R REDDY, M.Tech, Ph.D

Head of the department,

Dept. of ECE.

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Acknowledgement

I extend my sincere gratitude towards Prof.Dr.A.R.REDDY, Head of the Department, Dept of E.C.E for giving me his valuable knowledge and wonderful technical guidance. I also thank all the other faculty members of ECE department and my friends for their help and support.

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ABSTRACT

Different aspects of wireless networks are changing as a result of the continuous needs in terms of speed, data rates and quality of service. Such aspects are required to be adaptable within the same network or among networks of different technologies and service providers. Consequently, Worldwide Interoperability for Microwave Access (WiMAX) is one of the future generation networks (4G) that needs further study. However, a major consideration for WiMAX to achieve mobility is the handover mechanism that concerns with the mobile station movement within the range of network coverage from one base station to another similar homogeneous or different homogeneous network. In this paper, an intensive analysis to handover mechanism in WiMAX followed by comparisons to WiMAX performance with UMTS and WiFi networks is carried out. QualNet 4.5.1 simulator is used to simulate the comparison process homogeneously and heterogeneously. Performance metrics of Throughput, End-to-End (E-2-E) Delay and Jitter in the comparison during handover process in/between the wireless networks are used. The simulation results are evaluated to identify the performance of the handover process over WiMAX-WiMAX, WiMAX-UMTS and WiMAX-WiFi with respect to the selected metrics. The environment of Wi-MAX-WiMAX has shown substantial enhancement of the system Throughput, reduction of E-2-E Delay and Jitter.

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CONTENTS

PAGE NO

CHAPTER 1:INTRODUCTION

1.1Purpose and Scope------------------------------------------------

1.2 Overview of WiMAX Technology------------------------------ 1.3 Fundamental WiMAX Concepts--------------------------------

CHAPTER 2: Operating Topologies

2.1 Point-to-Point (P2P)-----------------------------------------------

2.2 Point-to-Multipoint (PMP)----------------------------------------

2.3 Multi-Hop Relay----------------------------------------------------

2.4 Mobile----------------------------------------------------------------

CHAPTER 3:ARCHITECTURE

3.1Architecture of WiMAX network------------------------------------3.2Standards for WiMAX--------------------------------------------------

3.3 Features of WiMAX-----------------------------------------------------

3.4Modulation & Multiplexing Schemes---------------------------

3.5 Objectives-----------------------------------------------------------

3.6 Problem Analysis---------------------------------------------------

3.7 Literature Review---------------------------------------------------

CHAPTER 4: Methodology

4.1QualNet Simulator---------------------------------------------------

4.2 Performance Metrics-------------------------------------------------

4.2.1 Throughput------------------------------------------------------------

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4.2.2 End-to-End (E-2-E) Delay----------------------------------------

4.2.3 Jitter-------------------------------------------------------------

4.3 Simulation Parameters--------------------------------------------

4.4 Simulation Environments----------------------------------------

4.5 Results--------------------------------------------------------------

4.5.1 Throughput Result-----------------------------------------------

4.5.2 End-to-End Delay Result---------------------------------------

4.5.3 Jitter Result-------------------------------------------------------

CHAPTER 5:SWOT ANALYSIS - 4G with WiMAX

5.1 WI-MAX Security Features-----------------------------------------

5.2 Security Associations ------------------------------------------------

5.3 Security Threats-------------------------------------------------------

CHAPTER 6:Countermeasures

6.1 Management Countermeasures --------------------------------------6.2 Operational Countermeasures----------------------------------------6.3 Comparisons of WiMAX and LTE--------------------------------

Discussion---------------------------------------------------------------------------------

Conclusion and Future Work----------------------------------------------

References----------------------------------------------------------------------

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LIST OF FIGURES

Figure 1: WiMAX Possible environments

Figure2: P2P Topology

Figure 3:PMP Topology

Figure 4:Multi-Hop Topology

Figure 5:Mobile Topology

Figure 6:OFDMA Resource Block Scheduling

Figure7:Cumulative numberof WiMAX deployment per frequency

Figure 8:QualNet layer model

Figure 9:WiMAX Security Framework

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LIST OF TABLES

Table 1:WiMAX Standards

Table 2:Simulation Parameters

Table 3: Comparisons of WiMAX and LTE

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CHAPTER-1

Introduction

The world is moving to the age of velocity in every field especially the wireless networks field. To go along with it, it is needful to have faster facilities, more importantly in the wireless networks. The need is to provide mobile wireless with higher data rates, Quality of Service (QoS) and adaptability within the same network or among networks of different technologies and service providers. The users should be able to get its potential whatever they are using (PC, cell phone, electronic pad, etc. wise), and where ever they are sitting; at home, walking and even driving [1].

Worldwide Interoperability for Microwave Access (WiMAX) is one of the future generations (4G) promising networks to cover some of the consumers' needs. It is an emerging technology that is designed to deliver fixed, and more recently, mobile broadband connectivity. It promises to deliver last-mile wireless broadband internet access capable of carrying data intensive applications. The 2005 version of WiMAX provides data rate up to 40Mbits/s and 2011 version can support data rate up to 1 Gbitls for fixed stations [1]. It is one of the latest developments and considered as a 4G (Fourth Generation) technology. WiMAX supports data rate up to 75 Mbitls which is higher than conventional cable modem and digital WiMAX subscriber line (DSL) connections which are all wired access technologies The WiMAX trade name is used to group a number of wireless technologies that have emerged from the Institute of Electrical and Electronics Engineers (IEEE) 802.16 Wireless Metropolitan Area Network (MAN) standards [3]. The main standards introduce mobility and currently receive a great deal of interest in the telecoms world [2]. Figure 1 show environments that can be employed in WiMAX [1].

The IEEE community has defined the IEEE 802.16e amendment (i.e. mobile WiMAX) to support mobility. Mobile WiMAX of IEEE 802.16e defines wireless communication for mobiles, moving at speed of 125 KMPH in the range of 2-6 GHz (802.16e). IEEE 802.16e is implemented with Orthogonal Frequency-Division Multiple Access (OFDMA) as its physical layer scheme [4]. Full mobility technology is different from one network to another, and each technology has its own mobility characteristics [5]. To ensure high level of mobility, it is important for WiMAX to have an efficient handover mechanism [6].

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This paper investigates the WiMAX mobility capabilities and issues related to homogenous (between the same types of networks) and heterogeneous (between different types of networks) mobility. Specifically, the paper focuses on the handover performance of the WiMAX in comparison with similar WiMAX network or with other networks. For performance evaluation, Throughput, End-to-End (E-2-E) Delay and Jitter metrics are used as networks performance quality criteria to investigate the WiMAX mobility capabilities and efficiency of handover process in the comparison with other wireless technologies.

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1.1 Purpose and Scope:

The purpose of this document is to provide information to organizations regarding the

security capabilities of wireless communications using WiMAX networks and to provide

recommendations on using these capabilities. WiMAX technology is a wireless metropolitan

area network (WMAN) technology based upon the IEEE 802.16 standard. It is used for a

variety of purposes, including, but not limited to, fixed last-mile broadband access, long-

range wireless backhaul, and access layer technology for mobile wireless subscribers

operating on telecommunications networks.

The scope of this document is limited to the security of the WiMAX air interface and

user subscriber devices, to include: security services for device and user authentication; data

confidentiality; data integrity; and replay protection. This document does not address

WiMAX network system specifications, which address core network infrastructure and are

primarily employed by commercial network operators.4 This publication, while containing

requirements specific to Federal agencies, serves to provide security guidance for

organizations considering the implementation of WiMAX systems.

1.2. OVERVIEW OF WIMAX TECHNOLOGY:

A wireless metropolitan area network (WMAN) is a form of wireless networking that

has an intended coverage area—a range—of approximately the size of a city. A WMAN is

typically owned by a single entity such as an Internet service provider, government entity, or

large corporation. Access to a WMAN is usually restricted to authorized users and subscriber

devices.

The most widely deployed form of WMAN technology is WiMAX technology, which is

based in large part on the IEEE 802.16 standard. The industry trade association, the WiMAX

Forum5, coined the WiMAX trademark and defines the precise content and scope of WiMAX

technology through technical specifications that it creates and publishes. Early iterations of

WiMAX technology (based on IEEE 802.16-2004 and earlier) were designed to provide fixed

last-mile broadband wireless access. The IEEE 802.16e-2005 amendment added support for

enhanced user mobility. The latest standard, IEEE 802.16-2009, consolidates IEEE 802.16-

2004 and IEEE 802.16e-2005 in addition to IEEE 802.16 amendments approved between

2004 and 2008. IEEE also released IEEE 802.16j-2009 to specify multi-hop relay

networking. This section explains the fundamental concepts of WiMAX technology,

including its topologies, and discusses the evolution of the IEEE 802.16 standard.

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1.3 Fundamental WiMAX Concepts:

WiMAX networks have five fundamental architectural components:

Base Station (BS): The BS is the node that logically connects wireless subscriber devices to

operator networks. The BS maintains communications with subscriber devices and governs

access to the operator networks. A BS consists of the infrastructure elements necessary to

enable wireless communications, i.e., antennas, transceivers, and other electromagnetic wave

transmitting equipment. BSs are typically fixed nodes, but they may also be used as part of

mobile solutions—for example, a BS may be affixed to a vehicle to provide communications

for nearby WiMAX devices. A BS also serves as a Master Relay-Base Station in the multi-

hop relay topology . Subscriber

Station (SS): The SS is a stationary WiMAX-capable radio system that communicates with a

base station, although it may also connect to a relay station in multi-hop relay network

operations. Mobile Station (MS): An

MS is an SS that is intended to be used while in motion at up to vehicular speeds. Compared

with fixed (stationary) SSs, MSs typically are battery operated and therefore employ

enhanced power management. Example MSs include WiMAX radios embedded in laptops

and mobile phones. This document uses the term SS/MS to refer to the class of both MS and

stationary SS.6. Relay Station (RS): RSs

are SSs configured to forward traffic to other RSs or SSs in a multi-hop Security Zone (which

is discussed in Section 3.5). The RS may be in a fixed location (e.g., attached to a building)

or mobile (e.g., placed in an automobile). The air interface between an RS and an SS is

identical to the air interface between a BS and an SS. Operator Network: The

operator network encompasses infrastructure network functions that provide radio access and

IP connectivity services to WiMAX subscribers. These functions are defined in WiMAX

Forum technical specifications as the access service network (radio access) and the

connectivity service network7 (IP connectivity). WiMAX devices communicate using two

wireless message types: management messages and data messages. Data messages transport

data across the WiMAX network. Management messages are used to maintain

communications between an SS/MS and BS, e.g., establishing communication parameters,

exchanging security settings, and performing system registration events (initial network

entry, handoffs, etc.) IEEE 802.16 defines frequency bands for operations based on signal

propagation type. In one type, it employs a radio frequency (RF) beam to propagate signals

between nodes. Propagation over this beam is highly sensitive to RF obstacles, so an

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unobstructed view between nodes is needed. This type of signal propagation, called line-of-

sight (LOS), is limited to fixed operations and uses the 10 to 66 gigahertz (GHz) frequency

range. The other type of signal propagation is called non-line-of-sight (NLOS). NLOS

employs advanced RF modulation techniques to compensate for RF signal changes caused by

obstacles that would prevent LOS communications. NLOS can be used for both fixed

WiMAX operations (below 11 GHz) and mobile operations (below 6 GHz). NLOS signal

propagation is more commonly employed than LOS because of obstacles that interfere with

LOS communications and because of strict regulations for frequency licensing and antenna

deployment in many environments that hinder the feasibility of using LOS.

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CHAPTER:2

2.Operating Topologies

There are four primary topologies for IEEE 802.16 networks: point-to-point, point-to-

multipoint, multi-hop relay, and mobile. Each of these topologies is briefly described below.

2.1 Point-to-Point (P2P)

A point-to-point (P2P) topology consists of a dedicated long-range, high-capacity wireless

link between two sites.

Figure2: P2P Topology

Typically, the main or central site hosts the BS, and the remote site hosts the SS, as seen in

Figure 2-1. The BS controls the communications and security parameters for establishing the

link with the SS. The P2P topology is used for high-bandwidth wireless backhaul8 services at

NLOS a maximum operating range of approximately 48 kilometers (km) (30 miles) using

LOS signal propagation, and eight km (five miles) using NLOS.

2.2 Point-to-Multipoint (PMP)

A point-to-multipoint(PMP) topologyis composed of a central BS supporting multiple SSs,

providing network access from one location to many. It is commonly used for last-mile

broadband access, 9 private enterprise connectivity to remote offices, and long-range wireless

backhaul services for multiple sites. PMP networks can operate using LOS or NLOS signal

propagation. Each PMP BS has a maximum operating range of 8 km (5 miles), but it is

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typically less than this due to cell configuration and the urban density of the target coverage

area.

Figure 3:PMP Topology

2.3 Multi-Hop Relay

A multi-hop relay topology, defined by IEEE 802.16j-2009, extends a BS’s coverage

area by permitting SSs/MSs to relay traffic by acting as RSs. Data destined to an SS/MS

outside of the BS’s range is relayed through adjacent RSs. An RS can only forward traffic to

RSs/SSs within its Security Zone. A Security Zone is a set of trusted relationships between a

BS and a group of RSs. Data originating outside of a BS’s coverage area is routed over

multiple RSs, increasing the network’s total geographical coverage area, as seen in Figure 2-

3. Multi-hop relay topology typically uses NLOS signal propagation because its purpose is to

span large geographic areas containing multiple RF obstacles; however, technically it can

operate using LOS propagation as well. The maximum operating range for each node in a

multi-hop relay topology is approximately 8 km (5 miles), but the actual operating range is

typically less depending on environmental conditions (e.g., building obstructions) and

antenna configuration.

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Figure 4:Multi-Hop Topology

2.4 Mobile

A mobile topologyis similar to a cellular network because multiple BSs collaborate to

provide seamless communications over a distributed network to both SSs and MSs.

Figure 5:Mobile Topology

This topology combines the coverage area of each member BS and includes measures

to facilitate handoffs of MSs between BS coverage areas, as seen by the car MS in Figure 2-

4. It uses advanced RF signaling technology to support the increased RF complexity required

for mobile operations. Each BS coverage area is approximately 8 km (5 miles). Mobile

WiMAX systems operate using NLOS signal propagation on frequencies below 6 GHz.

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CHAPTER-3

ARCHITECTURE:

3.1Architecture of WiMAX network

All WiMAX devices such as MS, BS, AAA server, HA server, ASN Gateway are IP based nodes. These nodes can directly plugged into IT backbone network. The BS is used to perform the air interface and manage the radio resources. The data is being received from mobile stations and send to mobile stations by air interface. The ASN Gateway performed QOS policy management and mobility management between BSes, is also used to bridged multiple BSes to backend core service network. A server is an authentication server. It is an open source software which performs authentication process, HA performs mobile IP. Its function is to implement roaming between ASN Gateways. HA is also an open source software.

3.2Standards for WiMAX

IEEE 802.16 is a series of Wireless Broadband technologies, standardized by the Institute of Electrical and electronics Engineers (IEEE).The IEEE 802.16 group was formed in 1998 to develop wireless broadband. The following Table.l shows the IEEE 802.16 standard.

3.3Features of WiMAX

WiMAX is a wireless network that has a high class set of features with a lot of flexibility in terms differentiates it from other metropolitan area wireless access technologies are: 1 .OFDM-based physical layer, 2. Very high peak data rates, 3. Scalable bandwidth and data rate support, 4. Adaptive modulation and coding (AMC), 5. Link-layer retransmissions, 6.Support for TDD and FDD, 7.Orthogonal frequency division multiple access (OFDMA), 8.Flexible and dynamic per user resource allocation, 9. Support for advanced antenna techniques, 10. Quality-of-service support, 11.Robust security, 12. Support for mobility, 13. IP-based architecture.

3.4MODULATION&MULTIPLEXING-SCHEMES: To transfer data over the "air interface", modulation schemes are used. A combination of varying modulation schemes are used in LTE and WiMAX networks. These modulation schemes can be QPSK (Quadrature Phase-Shift Keying) or QAM (Quadrature Amplitude Modulation), and the multiplexing schemes such as Input Multiple Output). OFDMA in the physical layer is used by mobile WiMAX and OFDM and SC-FDMA in the physical layer is used by LTE which allows the deployment in different frequency ranges.

SI.

No

Year Features Status

1 802.16 2001 W S

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2 802.16.2 2001 Recommended practice for coexistence S

3 802.16c 2002 System profiles for 10-66 GH z S

4 802.16a 2003 Physical layer and MAC definitions for 2-11 GHz S

5 P802.16b License-exempt frequencies(Project withdrawn) W

6 P802.16d Maintenance and System profiles for 2-11GHz(project merged into 802.16-

M

7 802.16 2004 Air Interface for Fixed Broadband Wireless Access System(rollup of 802.16-

S

8 P802.16.2a Coexistence with 2-11 GHz and 23.5-3.5GHz(project merged into 802.16.2-

M

9 802.16.2 2004 Recommended practice for eoexistence(Maintenance and rollup of 802.16.2-

C

10 802. 16f 2005 Management Information Base (MIB) for 802.16-2004 S

11 802.16-

2004/Cor.l

2005 Corrections for fixed operations(co-published with 802.16e-2005)

S

12 802.16e 2005 Mobile Broadband Wireless Access System S

13 802.16k 2007 Bridging of 802.16(an amendment to IEEE 802.1D C

14 802.16g 2007 Mobile Management Information Base(Project merged into 802.16-2009

M

15 802.16 2009 Air Interface for Fixed and Mobile Broadband Wireless Access System

C

16 802.16j 2009 Multihop relay C

17 802.16h 2010 Improved Coexistence Mechanisms for License-Exempt Operation

C

18 802.16m 2011 Advanced Air Interface with data rates of 100Mbits/s mobile and 1Gbits/s

C

19 P802.16n Higher Reliability Networks In Progress P

20 P802.16p Enhancements to support Machine -to-Machine Applications

P

OFDM (Orthogonal Frequency Division Multiplexing) and MIMO (Multiple

S=Superseded W=Withdrawn, M=Merged, C=Current, P=Progress

Table 1:WiMAX Standards.

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A.QPSK:

QPSK is a phase-shifting modulation scheme. To send data the carrier frequency phase is shifted. Here in QPSK we can send two symbols by shifting the frequency in four different phases (0, 90, 180, 270 degrees).

B.QAM:

QAM is a combination of two techniques, i.e. PSK (Phase-Shift Keying) and ASK (Amplitude-Shift Keying) for modulation. Hence it allows higher transfer rates. To distinguish between symbols (high = 1, low = 0) ASK uses different frequency amplitudes. More symbols can be transferred by varying number of amplitudes and phases. Wireless telecommunication networks widely uses digital 16-QAM (16 Symbols, 4 Bits) or 64-QAM (64 Symbols, 6Bits) modulation schemes.

C.OFDM: OFDM is a frequency division multiplexing modulation scheme which divides the data transmission over several streams, and assigns one for each orthogonal subcarrier. In wireless technologies such as WLAN, DVB-T or DAB OFDM is already been successfully used. Also it allows a large number (several hundreds) of narrow-band subcarriers. In comparison with other multi-carrier extension such as the WCDMA (Wideband Code Division Multiple Access) multicarrier evolution, a 20 MHz bandwidth could consist of four 5 MHz (sub)carriers. OFDM uses IFFT (Inverse Fast Fourier Transform) and FFT (Fast Fourier Transform) for signal modulation. Figure 1 shows the OFDM spectrum with the subcarrier division and the subcarrier spacing _f = 1=Tu, where Tu isthe per-subcarrier modulation symbol time. The subcarrier spacing can range from a few kHz up to several hundred kHz. The subcarrier spacing for 3GPP LTE is about 15 kHz, whereas WiMAX uses 11 kHz. Figure also shows theorthogonality between the subcarriers that allows for highspectral efficiency. Major disadvantage of OFDM is that it has a higher PAPR (Peak-to-average power ratio, also refer to as the crest factor or PAR) which leads toa higher power consumption. For this reason, 3GPP LTE uses Single Carrier FDMA, which is also referred as DFTS-OFDM (Discrete Fourier Transform Spread OFDM). SC-FDMA is a single carrier modulation which is basically a normal OFDM with a DFT-based precoding. The main advantage of this approach is that it reduces the variations of instantaneous transmit power, which eventually implies anincrease of power amplifier efficiency. With this approach LTE is able to avoid the obstacles of OFDM in the aspect of power consumption.

D.OFDMA:

Often OFDMA and OFDM are used as synonymous. OFDMA allows the use of OFDM modulation for multiple user access. Users can be allocated to any of the subcarriers in the

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used frequency band to enable this. In addition, it allows a flexible and better scheduling of resource allocation and services. Subcarriers are pooled to resource blocks to provide a good applicability (12 subcarriers per time slot). These blocks can be scheduled to different users as shown in figure 2. Furthermore certainenhancements or variations are used in LTE and WiMAX, such as SOFDMA (Scalable OFDMA) and SC-FDMA (Single Carrier - Frequency Division Multiple Access).

Fig.6: OFDMA Resource Block Scheduling

E.SOFDMA:

SOFDMA provides scalability support to OFDMA. Both OFDMA-based systems, LTE and WiMAX support variable bandwidth sizes. The main goal of SOFDMA is to keep the subcarrier spacing constant.

F.SC-FDMA:

The basic obstacle of OFDM is high power consumption. The power consumption of the data transmission is very crucial in the uplink where often mobile terminals are especially

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used. For this reason, 3GPP LTE uses Single Carrier FDMA, which is also referred as DFTS-OFDM (Discrete Fourier Transform Spread OFDM). SC-FDMA is a single carrier modulation which is basically a normal OFDM with a DFT-based precoding. The main advantage of this approach is that it reduces the variations of instantaneous transmit power, which eventually implies anincrease of power amplifier efficiency. With this approach LTE is able to avoid the obstacles of OFDM in the aspect of power consumption.G.MIMO:

MIMO (Multiple Input Multiple Output) is one of the fundamental technologies used in the 4G networks which is already used in 802.11n (WLAN-n standard). The basic principle behind this technology is the spatial multiplexing. Multiple antennas at the sender and the receiver side are needed for this approach. The data stream is divided into multiple smaller data streams in MIMO where in these smaller data streams are then sent and received over multiple antennas. This approach takes advantage of the multi-path propagation of radio signals and the peak data rates increase, because of the multiple antennas. However, with the use of multiple antennas also the power consumption increases. There are several different configurations for MIMO. The often used terms 4x4 (4 sending antennas, 4 receiving antennas), 4x2 or 2x2represent the MIMO configuration. Similar approaches are SIMO (Single Input Multiple Output) which is often used in battery powered User Terminals, MISO (Multiple Input Single Output) or the well-known approach with one antenna on each side SISO (Single Input Single Output).

3.5Objectives

Due to the importance and the complication of the mobile wireless networks, such as the WiMAX, UMTS and WiFi networks [7], an analysis study that aids in understanding the mobility problems, mobility insights from requirements, parameters and configurations in Mobile WiMAX network is presented in this research. The main objective focuses of the research are as follows:

1. To analysis mobile WiMAX network with regards to network topology acquisition, the base station and the main management messages that rules the mobility in WiMAX systems.

2. To evaluate mobile WiMAX network by performing an actual handover process to a new target base station.

3. To compare WiMAX performance with UMTS and WiFi wireless networks with respect to Throughput, E-2-E Delay and Jitter.

3.6 Problem Analysis

There are number of means to support mobility in communication devices such as roaming, portability, and covering mobility with a faster speed (vehicle speed) [9]. However, one of the important concerns of mobility concept for communication devices is how to motivate end users to use this technology, together with the emerging services for mobile devices presented by the service provider e.g. using packet data for streaming

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multimedia files.As there are many wireless networks technologies, there is a need to gather and analyze information about these technologies to be filtered and collected in a trendy presentation [10]. Communication devices such as smart phones and laptops capabilities are getting more complex and emergent services that are supplied by the network provider like streaming audio/video through packet data are more desirable [6]. More so, there are different methods behind the cutting edge of the overall system performance for instance portability, full mobility and roaming. These methods often differ among various network technologies as the mobility characteristics of each [10].

For the reasons above, it is vital to present a comprehensive study about mobile WiMAX and awarenessof its mobility capabilities especially in the motion state andcomparing it with other types of technologies. Consequentlyon one hand, knowing how WiMAX supports infra-network mobility, and is it better Mn the other contemporary technologies? And on the other hand, the handover mechanism as it is considered as an important process included within mobile WiMAX technology is not intensively reviewed [11]. As a matter of fact, researchers elaborated a handover in general or simulated the handover homogeneously within one network [7, 12].

3.7Literature Review

Worldwide Interoperability for Microwave Access (WiMAX) is a new wireless technology that can be used tobuild a wide coverage area networks with high Throughput [13], and high security [14] as shown in Figure 1. It is intended for Wireless Metropolitan Area Network (WMAN). WiMAX used to be the buzzword of wireless communication industry for the last six years. It is able to provide Broadband Wireless Access (BWA) up to 30 miles (50 km) for fixed stations, and 3-10 miles (5-15 km) for mobile stations [14]. IEEE authorized in 1999 a new working group known as 802.16. The group published its first standard, IEEE 802.16a, in January 2003 [15]. The standards of WiMAX are identified as 802.16-2004 (October 2004), 802.16e (December 2005), 802.16j (Jun 2009) and 802.16m (still under development) [16]. Figure 2 shows the number of WiMAX deployments over time per frequency.

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Figure 7:Cumulative number of WiMAX deployment per frequency

Daan P. have elaborated the different activities that occurred within the three important organizations: The 802.16 working group of the IEEE for technology development and standardization, the WiMAX forum for product certification and the ITU (International Telcomunication Union) for international recognition. Theypresented a comprehensive overview about the evolution of WiMAX in terms of standardization and certification. Furthermore, they highlighted the steps that have been considered in cooperating with the ITU to improve the international esteem of the technology. Finally, WiMAX trend analysis has also been discussed.

Ray proposed a fast and simple scheme for Mobile Station (MS)-controlled handover mechanism for mobile WiMAX environment. They suggested Received Signal Strength (RSS) and path-loss formula in estimating MS distance from any neighboring Base Stations (BS). The MS monitors the received signal strength that serves specificBS periodically. The MS-controlled approach simulation of Mobile WiMAX network outcomes show an observable reduction to handover latency accompanied by increase in network scalability.

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CHAPTER-4

Methodology

Since the WiMAX is a new technology, it is difficult to get a realistic comparison regarding a specific area of concern under specific circumstances within its architecture. Because of the lack practical experience with WiMAX and most of the experiments or simulations already done were focused on one specific area of concern. This research contributes comprehend study on mobile WiMAX network handover process performance.

The simulation of the handover process in mobile WiMAX is implemented using QualNet 4.5.1 simulator. Three performance matrices selected to be used in the experiment are: Throughput E-2-E delay, and Jitter within WiMAX environment. The obtained results are compared with the results obtained from the handover simulation process of WiMAX to WiFi network and WiMAX to UMTSnetwork. Finally, the Uplink Channel Descriptor (UCD) and the Down Link Channel Descriptor (DCD) are simulated within two different time intervals during the handover process. In this section the research methodology is presented to illustrate how the research is carried out to meet its objectives.

4.1QualNet Simulator

QualNet [19] is a state-of-the-art simulator for large, heterogeneous networks and the distributed applications that execute on such networks. QualNet [20] is simulating software that can be run on several platforms like Windows, Linux, 0 SX, and Solaris and it is capable of simulating wireless networks such as WiMAX [21]. QualNet has been used to simulate high-fidelity models of wireless networks with as many as 50,000 mobile nodes [22]. It uses architecture analogues of the TCP/IP network protocol stack which is a layered architecture.

The technology used in QualNet consists of 5 layers (top to bottom) as shown in Figure 3. The layers that are adjacent in the protocol stack communicate using well defined protocol. In general, the communication only occurs between adjacent layers (possible to be altered by the developers) [23].

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Figure 8:QualNet layer model

Figure 3 shows the QualNet layer model inwhich Constant Bit Rate (CBR) application and IEEE 802.16e MAC are used in the simulation. CBR application is generally used to simulate multimedia traffic (time critical traffic types). It can be configured to simulate a large number of real network applications by mimicking their traffic pattern and by filling traffic at a constant rate into the network. It can be accurately simulated by appropriately configuring the CBR application in QualNet. The simulated traffic sources CBR is generated using 4 mobile nodes performing handover process homogenously and heterogeneously with two time intervals, 5 and 10 seconds (UCD, DCD).

4.2Performance Metrics

Performance metrics is used to measure and evaluate the handover processes homogeneously and heterogeneously within WiMAX environment. Three parameters have been selected for the evaluations which are Throughput, E-2-E and Jitter.

4.2.1Throughput

The average Throughput represented by: the ratio of total amount of data that reaches its destination to the time taken for the data to transfer from the source to the destination. The data packets received at the physical layer are sent to thehigher layers if they are destined for this station. Throughputis usually described by bytes or bits per second (Bps or bps).

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TraiTx

_znenition ;nsws C

BR)

Data Trannussiou

Rmrcui2 hmtols

IEEE so2.16o

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4.2.2 End-to-End (E-2-E) Delay

The average End-to-End (E-2-E) Delay is the time taken for a packet to be transmitted across a network from source to destination. This metric describes the packet delivery time whereas the lower the E-2-E Delay, the better the application performance. The E-2-E Delay value is averaged over the number of packets. It is mathematically represented by the following equation.

Total E-2-E delayAverage E - 2 - E delay = xo.a f packets received

4.2.3 Jitter

The Jitter is the deviation in the time among packets arriving at the destination side, caused by network congestion, timing drift, or route changes. It signifies the Packets from the source till they reach their destination with different delays. A packet's delays vary with its location in the queues of the routers along the path between source and destination. This location is not predictable due to network circumstances. Equation below describes the Jitter calculation:

Jitter = Receptiom Time ofpacket(/)-Reception Time ofpacket(I-1)

4.3 Simulation Parameters

Various parameters have been used in all simulation scenarios to analyze the handover behavior under specific circumstances both homogeneously and heterogeneously. The simulation parameters that are used in this research are listed in Table 1. The speed of mobile nodes during handover process is 8OKMPH; the size of the field is 1500m x 1500m. During the simulation, all nodes start performing handover from 0 second until the time of simulation ends (25s).

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4.4 Simulation Environments

Table2:SimulationParameters

The QualNet simulator v.4.5.1 has been used to simulate the proposed scenarios for studying the handover process between WiMAX, WiFi and UMTS networks .UMTS and WiFi are chosen as they are common networks used nowadays and their technologies are almost similar. Therefore, it's possible to establish new connections between them heterogeneously.

The simulation of the handover process between the mentioned homogeneous and heterogeneous networks is conducted to evaluate the Throughput, E-2-E Delay and jitter. In each simulation scenario, the UCD and DCD messages are modified within two time intervals (5 and 10 seconds) during handover to find out which time interval performs better in each performance metric. The Constant Bit Rate (CBR) application is used to simulate the assumed scenarios in QualNet v.4.5.1

Four different experiments are conducted to evaluate the WiMAX handover mechanism. The first experiment is conducted to evaluate the average Throughput of the system during handover process. The second experiment compares the difference in the inter packet arrival times at the receiver (jitter) with respect to the total number of MS for every routing protocol. The purpose of the third experiment is to analyze the E-2-E Delay of the system during handover process. Finally, the fourth experiment is about comparing the time intervals of the UCD and DCD messages during handover process within two time intervals (5 and 10 seconds), regarding to the three performance metrics just mentioned above to find out which time interval performs the best during the handover process.

4 . 5 R e s u l t s

Results obtained from the handover simulation process are discussed in this section. The Throughput, E-2-E Delay and Jitter of each simulated environment of the three (WiMAX WiMAX, WiMAX-WiFi and WiMAX-UMTS) is discussed in the following sup-sections:

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Parameter Val~5 range radius (m) 1000

AP range radius (m) 500

errain-dimensions (m) 1500,15005-AP distance (m) 1200

requency band (GHZ) 2.4

Handover RSS trigger -78.0

Handover RSS margin 3.0

Channel bandwidth (MHZ) 20

e duration (ms) 20

T size 2048MS velocity [m.s-'] 20

BS Pt 20/5

AP Pt 20/1

MS transmit power Pt = height (M) 15/1.Somulation time (s) 25

Traffic CBR


4.5.1Throughput Result

Average Throughput is the ratio of total amount of data that reaches its destination to the time taken for the data to travel from the source to the destination. Figure 6 shows theaverage Throughput of the three handover environment with respect to the number of moving nodes.The average Throughput in WWAX-WiMAX handover is obviously the highest since it involves the same technology. In another words, the similarity in the BS type is high which saves any extra management signaling. WiMAX-UMTS comes in second, with slightly lower Throughput compared to WiMAX WiMAX. WiMAX WiFi comes in last, with much lower Throughput compared to WiMAX-WiMAX and WiMAX-UMTS. It is also observed that as the number of moving nodes increases, the average Throughput slightly decreases. Figure 6 depicts that the WiMAX-WiFi has much lower Throughput compared to the other two as a result of lower performance of the WiFi network compared with WiMAX and UMTS. It is also recorded that the Throughput drops dramatically with moremoving nodes due to the high load on the network with more nodes.

The system Throughput of WiMAX-WiMAX environment with variant values of UCD and DCD messages. Two time interval (5 and 10s) is configured in each simulation run. In first run, the time interval of UCD and DCD messages is 5seconds for each. In second run, the time interval is 10 seconds for each.

4.5.2End-to-End Delay Result

In general, the average of E-2-E Delay matrix for all simulation environments (WiMAX WiMAX, WiMAX-UMTS and WiMAX-WiFi) increases as the number of MSs in the network increases (see Figure 8). This is expected in wireless environments due to queuing delays at every hop node (BS or AP). Neither the WiMAX-WiMAX nor the WiMAX-UMTS utilize their effects on average E-2-E Delay for traffic; hence it appears to be minimal. However, the average E-2-E Delay for the different numbers of MSs with the WiMAX-WiMAX and WiMAX-UMTS are lower than with the WiMAX-WiFi under all scenarios. Similar to the result in Section A, the WiMAX-WiMAX and WiMAX-UMTS handover give the best performance while the WiMAX-WiFi gives the worst performance due to WiFi network lower performance compared with WiMAX and UMTS in addition to the variety in the technology specifications quality.

4.5.3 Jitter Result

The simulation result of the overall mobility Jitter performance with various number of moving MSs for all simulated environments is shown in Figure 10. The WiMAX-WiMAX and WiMAX-UMTS environments perform with lower Jitter compared with WiMAX-WiFi environment due to the variance in the technology specifications quality.

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CHAPTER-5

SWOT ANALYSIS - 4G With Wimax:

Considering 4G characteristics, expected scenarios and market trends, we can find out strengths, weaknesses, opportunities and threats of 4G with better understandings. The lists and findings follow.

Strengths in 4G:

- 4G visions take into account installed base and past investments- Strong position of telecommunications vendors expected in the marketplace.- Faster data transmission and higher bit rate and bandwidth, allow more

business applications and commercialization

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- Has advantage for personalized multimedia communication tools

Weakness in 4G:

_ No large user community for advanced mobile data applications yet.

_ Growing divergence between telecommunications vendors and operators._ Not possible to offer full internet experience due to limited speed and bandwidth._ Comparatively higher cost to use and deploy infrastructure compared fast mobile generation.

Opportunities in 4G:

- Evolutionary approach may yield opportunities for the 4G- Emphasis on heterogeneous networks capitalizes on past investments- Strategic alliance and coalition opportunities with traditional non-

telecommunication industries- Sophisticated and mature commercialization of 4G technology would encourage

more applications of e-commerce and m-commerce- Worldwide economy recover stimulates consumption and consumer

confidence, therefore bring in opportunities for telecommunication sections

- It is expected and predicted that consumers will continue to replace handsetswith newer technology at a fast rate.

- Desirable higher data capacity rates, the growth opportunity for 4G is very bright and hopeful.

Threats in 4G:

- Faster rate of growth and developments in other region- Since 3G mobile is still in the market, it squeezes the market competition in the mobile

industry.5.1 WI-MAX Security Features

This section discusses the security mechanisms included in IEEE 802.16-2004, IEEE

802.16e-2005, IEEE 802.16-2009, and IEEE 802.16j-200915; it illustrates their functions and

provides a foundation for the security recommendations in Section 4. The IEEE 802.16

standards specify two basic security services: authentication and confidentiality.

Authentication involves the process of verifying the identity claimed by a Wi-MAX device.

Confidentiality is limited to protecting the contents of Wi-MAX data messages so that only

authorized devices can view them. IEEE 802.16e-2005 and IEEE 802.16-2009 share the same

authentication and confidentiality mechanisms; they both support user authentication and

device authentication.

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The IEEE 802.16 standards do not address other security services such as availability

and confidentiality protection for wireless management messages 16; if such services are

required, they must be provided through additional means. Also, while IEEE 802.16 security

protects communications over the WMAN link between an SS/MS and a BS, it does not

protect communications on the wired operator network behind the BS. End-to-end (i.e.,

device-to-device) security is not possible without applying additional security controls not

specified by the IEEE standards.

Wi-MAX systems provide secure communications by performing three steps:

authentication, key establishment, and data encryption. Figure 3-1 is a high-level overview of

the security framework. The authentication procedure provides common keying material for

the SS/MS and the BS and facilitates the secure exchange of data encryption keys that ensure

the confidentiality of Wi-MAX data communications. The remainder of this section explains

the basics of the Wi-MAX security framework, authentication, key establishment, and data

encryption.

Figure 9:WiMAX Security Framework

5.2 Security Associations

A security association (SA) is a shared set of security parameters that a BS and its SS/MS use

to facilitate secure communications. Similar in concept to Internet Protocol Security

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(IPSec),18 an SA defines the security parameters of a connection, i.e., encryption keys and

algorithms. SAs fall into one of three categories: authorization, data (for unicast19 services),

and group (for multicast20 services). A distinct SA is established for each service offered by

the BS. For example, a uncast service would have a unique data encryption SA, whereas a

multicast service would have a unique group SA. Authorization SAs facilitate authentication

and key establishment to configure data and group SAs. Authorization SAs contain the

following attributes: X.509 certificates. X.509 digital certificates allow Wi-MAX

communication components to validate one another. The manufacturer’s certificate is used

for informational purposes, and the BS and SS/MS certificates contain the respective devices’

public keys. The certificates are signed by the device manufacturer or a third-party

certification authority.

Authorization key (AK). AKs are exchanged between the BS and SS/MS to authenticate one

another prior to the traffic encryption key (TEK) exchange. The authorization SA includes an

identifier and a key lifetime value for each AK.

Key encryption key (KEK). Derived from the AK, the KEK is used to encrypt TEKs during

the TEK exchange.

Message authentication Keys Derived from the AK, the message authentication keys

validate the authenticity of key distribution messages during key establishment. These keys

are also used to sign management messages to validate message authenticity.

Authorized data SA list. Provided to the SS/MS by the BS, the authorized data SA list

indicates which data encryption SAs the SS/MS is authorized to access.

Data SAs establish the parameters used to protect unicast data messages between BSs

and SSs/MSs. Data SAs cannot be applied to management messages, which are never

encrypted. A data SA contains the following security attributes:

SA identifier (SAID). This unique 16-bit value identifies the SA to distinguish it from other

SAs.

Encryption cipher to be employed. The connection will use this encryption cipher

definition to provide wireless link confidentiality.

Traffic encryption key (TEK).

TEKs are randomly generated by the BS and are used to encrypt Wi-MAX data

messages. Two TEKs are issued to prevent communications disruption during TEK rekeying;

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the first TEK is used for active communications, while the second TEK remains dormant.21

Data encryption SA type indicator.

This indicator identifies the type of data SA. There are three types: Primary

SA. This SA is established as a unique connection for each SS/MS upon initialization with

the BS. There is only one primary SA per SS/MS.

Static SA. This SA secures the data messages and is generated for each service defined by

the BS.

Dynamic SA. This SA is created and eliminated in response to the initiation and termination

of specific service flows. Group SAs contain the keying material used to secure multicast

traffic. Group SAs are inherently less secure than data SAs because identical keying material

is shared among all members of a BS’s group. Group SAs contains the following attributes

5.3 SECURITY THREATS :

A. WiMAX Security Attacks

Jamming and packet scrambling are the general kinds of attacks that can most affect WiMAX's physical layer. Signals in the lower frequencies that cross or are in close proximity to the WiMAX antenna can produce second and third harmonic waves that interfere and can overload the WiMAX signal. Because WiMAX is transmitted over frequency bands that are licensed, unintentional jamming is rare. Taking a spectrum analysis at intervals can mitigate constant jamming, whether malicious or not [11]. Within the MAC Layer of the network stack, digital certificates work very well for establishing the identity of a mobile station to a base station.

However, a simple one-way authentication could allow an opportunity for intruders to create a rogue base station and snoop traffic. Authentication using EAP-TLS will enable both the base station and the mobile station to use X.509 certificates to establish their legitimacy. Two of the most destructive attacks can be MITM (Man in the middle attack) and DoS (Denial of Service attack) attacks.

Power efficiency:Both LTE and WiMAX offer power ving mechanisms. They can be both sent into an offtte where less or even no power is needed. LTE can also -n the transmitter off while

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having a call when there are iger breaks. Also LTE uses SC-FDMA in the uplink, iich is more power efficient than OFDMA. This makes bile devices use less power, which increases their ttery life.

The following threats affect all WiMAX systems:

RF jamming:

All wireless technologies are susceptible to RF jamming attacks. The threat arises from an

adversary introducing a powerful RF signal to overwhelm the spectrum being used by the

system, thus denying service to all wireless nodes within range of the interference. RF

jamming is classified as a DoS attack. The risk associated with this threat is identical for

IEEE 802.16-2004, IEEE 802.16e-2005, and IEEE 802.16-2009 WiMAX systems.

Scrambling:

Scrambling attacks, which are the precise injections of RF interference during the

transmission of specific management messages, affect all wireless systems. These attacks

prevent proper network ranging and bandwidth allocations with the intent to degrade overall

system performance [Nas08]. Scrambling attacks are more difficult to identify than jamming

attacks because they are engaged for short time periods and are not a constant source of

interference. The risk associated with this threat is identical for IEEE 802.16-2004, IEEE

802.16e-2005, and IEEE 802.16-2009.

Subtle management message manipulation:

Exploitation of unauthenticated management messages can result in subtle DoS, replay, or

misappropriation31 attacks that are difficult to detect. These attacks spoof management

messages to make them appear as though they come from a legitimateor SS/MS, allowing

them to deny service to various nodes in the WiMAX system. A water torturattack is an

example of a subtle DoS in which an adversary drains a client node’s battery by sending a

constant series of management messages to the SS/MS [Joh04]. IEEE 802.16e-2005 and

IEEE 802.16-2009 provide integrity protection for certain unicast management messages

following initial network registration with an appended integrity protection digest. All other

IEEE 802.16e-2005 and IEEE 802.16-2009 management messages, and all IEEE 802.16-

2004 management messages, are susceptible to attacks involving manipulation. Man-in-the-

middle. Man-in-the-middle attacks occur when an adversary deceives an SS/MS to appear as

a legitimate BS while simultaneously deceiving a BS to appear as a legitimate SS/MS. This

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may allow an adversary to act as a pass-through for all SS/MS communications and to inject

malicious traffic into the communications stream. An adversary can perform a man-in-the-

middle attack by exploiting unprotected management messages during the initial network

entry process. This is because the management messages that negotiate an SS’s/MS’s security

capabilities are not protected. If an adversary is able to impersonate a legitimate party to both

the SS/MS and BS, an adversary could send malicious management messages and negotiate

weaker security protection between the SS/MS and BS [Han06]. This weaker security

protection may allow an adversary to eavesdrop and corrupt data communications. Mandating

the use of AES-CCM in IEEE 802.16e-2005 and IEEE 802.16-2009 helps mitigate this attack

because it appends a unique value to each data packet, which, in turn, prevents the man-in-

the-middle traffic relays between BS and SS/MS. IEEE 802.16-2004 does not offer adequate

protection against man-in-the-middle attacks Eavesdropping. Eavesdropping occurs when

an adversary uses a WiMAX traffic analyzer within the range of a BS or SS/MS. The large

operating range of WiMAX networks helps to shield eavesdroppers from detection;

eavesdropping mitigation relies heavily on technical controls that protect the confidentiality

and integrity of communications. The adversary may monitor management message traffic to

identify encryption ciphers, determine the footprint

of the network, or conduct traffic analysis regarding specific WiMAX nodes. Data messages

collected during eavesdropping can also be used to decipher DES-CBC encryption; however,

AES provides robust data message confidentiality that cannot be circumvented through

eavesdropping. The risk associated with eavesdropping management messages is identical for

IEEE 802.16-2004, IEEE 802.16e-2005, and IEEE 802.16-2009. The risk associated with

eavesdropping data messages is significant for IEEE 802.16-2004 systems due to weak

encryption. IEEE 802.16e-2005 and IEEE 802.16-2009 systems offer the stronger AES

cipher to protect data messages from eavesdropping.

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CHAPTER-6

Countermeasures

This section presents countermeasures that may be used to reduce or mitigate the risks

inherent to WiMAX systems. These countermeasures do not guarantee security and cannot

prevent all possible attacks. The optimum security design is a dynamic intersection of threat

risk and the cost of countermeasures that will change in response to technology.

Organizations should implement countermeasures commensurate with their acceptable level

of risk.

The WiMAX management, operational, and technical countermeasures described in the

following sections take an approach similar to that of NIST SP 800-48 Revision 1, Guide to

Securing Legacy IEEE 802.11 Wireless Networks [Sca08]. IEEE 802.11 and IEEE 802.16

share many management and operational controls but strongly differ in their technical

controls. WiMAX systems should leverage the countermeasures found in this Special

Publication, in FIPS PUB 199, and in NIST SP 800-53. FIPS PUB 199, Standards for

Security Categorization of Federal Information and Information Systems establishes three

security categories—low, moderate, and high—based on the potential impact of a security

breach involving a particular system [NIS04]. NIST SP 800-53, Recommended Security

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Controls for Federal Information Systems and Organizations, provides recommendations for

minimum management, operational, and technical security controls for information systems

based on the FIPS PUB 199 impact categories [NIS09]. Regardless of a system’s sensitivity

classification, WiMAX security should be incorporated throughout the entire lifecycle of

WiMAX solutions [Kis08].

6.1 Management Countermeasures :

Management countermeasures generally address any problem related to risk, system planning, or

security assessment by an organization’s management. Organizations should develop a wireless

security policy that addresses WiMAX technology. A security policy is an organization’s foundation

for designing, implementing, and maintaining properly secured technologies. WiMAX policy should

address the design and operation of the technical infrastructure and the behavior of users.

Policy considerations for WiMAX systems should include the following:

Roles and responsibilities

Which users or groups of users are authorized to use the WiMAX system

Which office or officer provides the strategic oversight and planning for all WiMAX

technology programs

Which parties are authorized and responsible for installing and configuring WiMAX

equipment

WiMAX infrastructure

Physical security requirements for WiMAX assets .

The use of standards-based WiMAX system technologies.

Types of information permitted over the WiMAX system, including acceptable use

guidelines .

How WiMAX transmissions should be protected, including requirements for the use

of encryption and for cryptographic key management .

WiMAX client device security

Conditions under which WiMAX client devices are allowed to be used and operated

Standard hardware and software configurations that must be implemented on WiMAX

devices to ensure the appropriate level of security

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WiMAX security assessments

Frequency and scope of WiMAX security assessments

Standardized approach to vulnerability assessment, risk statements, risk levels, and

corrective actions .

6.2 Operational Countermeasures:

Operational countermeasures include controls that are executed by people, e.g., personnel

security, physical environment protection, configuration management, security awareness and

training, and incident response. These controls are documented in a system security plan

(SSP) which should be maintained by all parties involved with WiMAX system operations.

SSPs are living documents that provide an overview of the security requirements of a system

and describe the controls in place to meet those requirements; this includes all system

hardware and software, policies, roles and responsibilities, and other documentation

materials. Documentation itself is a security control, as it formalizes security and operational

procedures to a given system.

Physical security is fundamental to ensuring that only authorized personnel have access to

WiMAX equipment. Physical security includes measures such as physical access control

systems, personnel security and identification, and external boundary protection. For

example, integrating Federal personal identity verification (PIV)35 into physical access

controls can reduce the risk of unauthorized access to WiMAX systems.36 WiMAX system

administrators and users should receive training to address the specific challenges and threats

to wireless technologies. While it is difficult to prevent unauthorized users from attempting to

access a WiMAX system because of its expansive coverage area, the use of additional

security mechanisms may help prevent the theft, alteration, or misuse of WiMAX

infrastructure components.

WiMAX operates on licensed or unlicensed RF spectrum. The most prevalent spectrum

used to accommodate WiMAX is the 2.5 GHz licensed range, but WiMAX solutions are also

viable across several unlicensed spectrum ranges. Organizations should understand the

implications of spectrum allocation as it impacts system availability. Due to the proliferation

of unlicensed wireless technologies, interference may become an implementation obstacle

when operating in unlicensed spectrum. Regardless of which spectrum frequency is used,

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organizations should use counter-interference technologies37 in addition to site surveys to

ensure system availability.

Prior to deployment, site surveys construct the foundation for a WiMAX system’s design

to ensure system availability. Long distance radio transmissions should be tailored and

optimized for RF obstacles and interference sources. Site surveys help limit range to provide

an organization operational awareness of a system’s coverage area.

Site survey tools include terrain maps, global positioning systems, RF propagation

models, spectrum analyzers, packet analyzers, and additional tools which provide a more

thorough understanding of the environment’s RF landscape. Conducting a WMAN site

survey requires specialized skills, and it is typically provided as part of the overall vendor

solution. Organizations should, at a minimum, involve themselves in the site survey process

and document its findings in the system security plan.

As with all wireless technologies, operational countermeasures may not provide protection

against general wireless threats such as DoS, eavesdropping, man-in-the-middle, and message

replay. Operational controls often require highly specialized expertise and rely upon both

management and technical controls

6.3 Comparisons of WiMAX and LTE:

Parameters WiMAX LTE

Release and Deployment

2005 2009

Generation 4G(Wimax 802.16m) 4G(Advanced LTE)

Transfer rates46 Mbps in the downlink and up to 4 Mbps in

300 Mbps in the downlink and 75 Mbps

Power efficiencyBoth offer power saving mechanisms. They can be both sent into an off-state where less or

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Quality of service Frame is separated in a downlink and an uplink

subframe that allocates resources for different

LTE frames don't separate their frames in

uplink and downlink subframes.

Security Concerning security aspects both, LTE and WiMAX, are on the same level

Physical layer DL:OFDMA

UL:OFDMA

DL:OFDMA

UL:SCFDMA

Duplex mode TDD(Time Division Duplex)TDD & FDD(Time & Frequency

User mobility 60-120 kmps Up to 350kmps

Coverage Up to 50km Up to 100km

Channel bandwidth 3.5,5,7,8.75,10MHz 1.4,3,5,10,15,20 MHz

Spectral efficiency DL:1.91bps/Hz(2*2)

UL:0.84 bps/Hz(1*2)

DL:1.91bps/Hz(2*2 )

UL:0.72 bps/Hz(1*2 )

Latency Link layer:about 20ms

Handoff:about 35-50ms

Link layer:< 20ms

Handoff:about:<50ms

VoIP capacity 20 Users per sector/MHz(TDD) 80 Users per sector z D D )

Other qualities Full IP-based architecture,3G compatible, QoS support

Table 3:Comparisons of WiMAX and LTE

7. Discussion:

The main focus is to investigate the handover process in Mobile WiMAX in terms of its rules and address management and the main issues related to it. There is a limited related works that investigate the handover scenarios in networks' simulation analysis. They concentrate more on the transportation of subscribers (Mobile Stations) within WiMAX environment and with another environments (e.g. UMTS or WiFi), and suggest other fundamentals like scheduling and QoS as future works.

Two of the most important requirements for wireless communication technologies are to be applicable and universally desirable. Mobile WiMAX 802.16e handover mechanism analysis is the main target for this research. The focal point here is to introduce a complete understanding about handover process in WiMAX network, as it is considered as the most important process to achieve mobility within wireless networks. Work evaluation has been done by simulating handover process with different situations homogeneously and

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heterogeneously. The main task of the simulation process is to determine what parameters are affected during handover process in mobile networks homogeneously within WiMAX environment and heterogeneously to UMTS and WiFi networks.

The results show the ability to evaluate the performance of handover procedure within WiMAX and the other networks that have been chosen for this research. Based on the obtained results, a comparison among the three different networks has identified the best environment to establish a "handover".

Regarding to channel descriptor, the purpose of the DCD messages is to specify the characteristics of a given downlink physical channel. The BS transmits them at a given interval, which can have a maximum value of 10 seconds. It's the same for UCD, in that it specifies the characteristics of the uplink channel and is transmitted at a given interval, which cannot exceed 10 seconds.

The WiMAX-WiMAX case has been simulated using two time intervals (5 and 10) seconds under the three differential matrices (Throughput, E-2-E Delay and jitter) expecting that the time interval 5s will achieve the best results due to the short time it takes to update the current information compared to 10s.

8.Conclusion and Future Work

We discuss the simulation results of the handover process over WiMAX WiMAX, WiMAX UMTS and WiMAX WiFi environments/networks. The simulation scenarios are simulated to compare the results of each environment's behavior with handover process using the QualNet simulator v4.5.1. The environment (WiMAX-WiMAX) has shown substantial enhancement of the system Throughput, reduction of E-2-E delay, and reduction of Jitter. This is mainly due to the similarity in the BS type which saves any extra management signaling. For example, between WiMAX BS and UMTS BS, the management messages signaling require longer time compared with WiMAX WiMAX BSs.

In addition, the best environment (WiMAX-WiMAX) is simulated with various values of the time intervals of UCD and DCD management messages as a deep analysis. However, all related simulation results show that the shorter time interval of both UCD and DCD messages improves the overall network performance and the handover process.

The handover process of mobile WiMAX to improve its performance in terms of Delay and moving speed. Thus, the handover optimization in mobile WiMAX is the recommendation for future work.

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9.References

[1] IEEE802.16 Working Group. "IEEE Standard for Local andMetropolitan Area Networks, Part16: Air interface for fixedbroadband wireless access systems,"IEEE Std802 (2004).

L. M. Carlberg, and A Dammander, "WiMAX-A study of mobility and a MAC-layer implementation in GloMoSim,"Master's Thesis in Computing Science (2006)

[2] Anita Garhwal, ParthaPratim Bhattachary "Performance Enhancement of WiMAX System using Adaptive Equalizer" Department of Electronics and Communication Engineering, Faculty ofEngineering and Technology Mody Institute of Technology & Science (Deemed University).

[3] Jeffery G. Andrews, ArunabhaGhosh, RiasMuhamed, "Fundamentals of WiMAX: Understanding Broadband Wireless Networking", Prentice Hall, 2007.

[4] Igor Bilogrevic, MurtuzaJadliwala and Jean-Pierre Hubaux "Security Issues in Next ]Applications (Al), L C E P F L , Lausanne, Switzerland 2010.

[5] Q. B. Mussabbir, "Mobility management across converged IP-based heterogeneous access networks," PhD Thesis. School of Engineering and Design, Brunel Universit (2010).

[6] International Telecommunication Union (ITU), "Broadband mobile communications towards a converged world," Micworkshop on shaping the future mobile information society, Seoul. 2004.

[7] F. Akyildiz, J. Xie and S. Mohanty. "A survey of mobility management in next-generation all-IP-based wireless systems," II ireless Communications, IEEE 11.4

[8] Z. Becvar, P. Mach and R. Bestak, "Initialization of handover procedure in WiMAX networks," ICT-MobileSummit 2009 Conference Proceedings, 2009.

[9] I. Liao, Q. Qi, X. Zhu, Y. Cao, and T. Li, "Enhanced MS handoff mechanism for QoS support over heterogeneous network," The Computer Journal 53.10 (2010): 1719-1737.

[10] I.R. Santhi and G. S. Kumaran, "Migration to 4 G: Mobile IP based solutions," Telecommunications, 2006. AICT-ICIW'06. International Conference on Internet and Web Applications and Services/Advanced International Conference on. IEEE, 2006.

WiMAX.com, "What is WiMAX," WMax.com Broadband Solutions, Inc. 2011. <http://www.wimax.com/general/what-is-wi=>

[11] A. Shami, M. Maier, and C. Assi. Broadband Access Networks: Technologies and Deployments. Springer Verlag, 2009.

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[12] F. Muratore.UMTS: Mobile communications for the future. John Wiley & Sons, Inc., 2000.

[13] QualNet 4.5 Programmer's Guide, Scalable Network Technologies, Inc., 2008. <http://www.eurecom. fr/-chenj lQuaINet03.pdf.>

[14] QualNet Product Family, Scalable Network Technologies, Inc., 2010. <http://www.scalable-networks.com/pdf/QualNet

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