PERFORMANCE ANALYSIS OF RADIO OVER FIBER BASED

ON IEEE 802.11a

SITI IDANI AZURIATI BINTI ABDUL AZIZ

UNIVERSITI TEKNOLOGI MALAYSIA

PERFORMANCE ANALYSIS OF RADIO OVER FIBER BASED

ON IEEE 802.11a

SITI IDANI AZURIATI BINTI ABDUL AZIZ

A project report submitted in partial fulfilment of the

requirements for the award of the degree of

Master of Engineering (Electrical – Electronics & Telecommunications)

Faculty of Electrical Engineering

Universiti Teknologi Malaysia

APRIL 2011

iii

To my beloved husband

iv

ACKNOWLEDGEMENT

In preparing this thesis, I was in contact with many people, researchers,

academicians, and practitioners. They have contributed towards my understanding

and thoughts. In particular, I wish to express my sincere appreciation to my main

thesis supervisor, Assoc Professor Dr. Razali Ngah, for encouragement, guidance,

critics and friendship. I am also very thankful to a Phd student, Teguh Prakoso for his

guidance, advices and motivation. Without their continued support and interest, this

thesis would not have been the same as presented here.

I am also indebted to my husband, Mohd Saiful Mahdzir for funding my

Master study. My sincere appreciation also extends to all my colleagues and others

who have provided assistance at various occasions. Their views and tips are useful

indeed. Unfortunately, it is not possible to list all of them in this limited space. I am

grateful to all my family members.

v

ABSTRACT

In future wireless communication system, the essential for increased capacity

per unit area leads to higher operating frequencies and smaller radio cells. To reduce

the system installation and maintenance cost of such system, it is very important to

make the Remote Access Point (RAP) or Base Station (BS) as simple as possible.

This may be achieved by consolidating signal processing functions at central station

(CS). This is the reason why Radio over Fiber (RoF) is introduced. RoF technology

entails the use of optical fiber transmission link to distribute Radio frequency (RF)

signals from a CS to BS. The purpose of this project is to analyze the performance of

a RoF system based on IEEE 802.11a standard by experiment. The idea of

employing IEEE 802.11a standard is due to several advantages: the low cost of

equipment, its operation in the unlicensed spectrum and its higher data rates.

However, original IEEE 802.11a standard is designed for service range of less than

1km. So, it cannot provide a high speed link for long distance. Fortunately, this

problem is more on the Medium Access Control (MAC) layer only. By modifying

the parameter in the MAC layer, it is possible to overcome the problem. A RoF

system design is proposed in this project by using one of the modified protocols. The

results show that the performance of the proposed system is excellent for more than

5km of service range. Previous study has been shown that the standard IEEE 802.11a

MAC protocol working procedure is feasible for point to point links of up to 2.7 km

only when IEEE 802.11a technology is used. Combining the results, it is concluded

that a RoF system based on IEEE 802.11a with higher speed and longer distance is

achievable.

vi

ABSTRAK

Dalam sistem komunikasi tanpa wayar masa hadapan, keperluan untuk

menambahkan kapasiti per unit kawasan membawa kepada frekuensi operasi yang

lebih tinggi dan sel radio yang lebih kecil. Untuk mengurangkan kos pemasangan

dan penyelenggaraan sistem, adalah penting untuk stesen tapak (BS) menjadi

seringkas yang boleh. Ini dapat dicapai dengan menjalankan semua fungsi

pemprosesan isyarat di stesen pusat (CS). Oleh sebab inilah, radio atas gentian (RoF)

diperkenalkan. Teknologi RoF melibatkan penggunaan talian penghantaran gentian

optik untuk menyebarkan isyarat frekuensi radio (RF) dari CS ke BS. Projek ini

bertujuan untuk menganalisa perlaksanaan system RoF berdasarkan piawai IEEE

802.11a secara eksperimen. Idea menggunakan piawaian IEEE 802.11a adalah

kerana beberapa kelebihan: kos peralatan yang rendah, beroperasi pada spektrum

tanpa lesen dan kadar penghantaran data yang lebih tinggi. Walau bagaimanapun,

pada mulanya piawaian IEEE 802.11a direkabentuk untuk jarak operasi kurang dari

1km. Oleh itu, ia tidak boleh melakukan penghantaran untuk jarak yang jauh. Tetapi,

masalah ini hanyalah pada lapisan kawalan akses media (MAC). Dengan mengubah

parameter dalam lapisan MAC, masalah ini mungkin boleh diatasi. Satu rekabentuk

sistem RoF dicadangkan dalam projek ini dengan menggunakan salah satu protokol

yang telah diubahsuai. Keputusan menunjukkan perlaksanaan sistem yang

dicadangkan adalah cemerlang sehingga melebihi jarak 5km. Kajian sebelum ini

telah menunjukkan prosedur kerja IEEE 802.11a boleh melakukan penghantaran

isyarat titik ke titik sehingga 2.7km. Bila semua keputusan diambilkira, dapatlah

disimpulkan bahawa sistem RoF menggunakan IEEE 802.11a dengan kelajuan yang

lebih tinggi dan jarak yang lebih jauh dapat dicapai.

vii

TABLE OF CONTENTS

CHAPTER TITLE PAGE

DECLARATION

DEDICATION

ACKNOWLEDGEMENTS

ABSTRACT

ABSTRAK

TABLE OF CONTENTS

LIST OF TABLES

LIST OF FIGURES

LIST OF ABBREVIATIONS

LIST OF SYMBOLS

LIST OF APPENDICES

ii

iii

iv

v

vi

vii

xi

xii

xiv

xvi

xvii

1 INTRODUCTION

1.1 Project Background

1.2 Problem Statement

1.3 Objective

1.4 Scopes

1.5 Project Report outline

1

1

2

4

4

4

2 RADIO OVER FIBER TECHNOLOGY

2.1 Introduction

2.2 Radio over Fiber

2.3 Benefits of RoF Technology

6

6

6

8

viii

2.3.1 Low Attenuation Loss

2.3.2 Large Bandwidth

2.3.3 Immunity to Radio Frequency interference

2.3.4 Easy Installation and Maintenance

2.4 Limitation in RoF technology

2.5 Applications of RoF Technology

2.6 Optical Transmission Link

2.6.1 Optical Fiber

2.6.2 Optical Transmitters

2.6.3 Optical Receivers

2.7 RoF Analog optical Links

2.7.1 Basic Radio Signal Generation Methods

2.7.2 RoF Link Configurations

9

9

10

10

10

11

12

12

13

13

14

15

16

3 IEEE 802.11 WLAN STANDARDS

3.1 Introduction

3.2 WLAN Standards

3.2.1 IEEE 802.11-1997 (802.11 Legacies)

3.2.2 IEEE 802.11a

3.2.3 IEEE 802.11b

3.2.4 IEEE 802.11g

3.2.5 IEEE 802.11-2007

3.3 RoF Based WLAN Requirement

3.4 The Advantages of Using IEEE 802.11 standard

3.5 Feasibility of Applying RoF into WLAN

3.6 IEEE 802.11 Radio Design

3.7 IEEE 802.11 MAC Protocol

3.7.1 The PCF Protocol

3.7.2 The DCF Protocol

3.8 Current and Past Researches

3.8.1 Analysis of IEEE 802.11 RoF Home Network

3.8.2 Propagation delay Influence in IEEE 802.11

20

20

21

22

23

24

24

25

25

27

28

29

30

31

32

34

34

35

ix

3.8.3 A High Gain Photonic Antenna for High Speed

3.8.4 Performance Impairments in SMF RoF System

36

37

4 RESEARCH METHODOLOGY

4.1 Introduction

4.2 Methodology

4.3 Proposed System

4.3.1 Nstreme2 Protocol

4.4 Components of Radio over Fiber for Experiments

4.4.1 Routerboard

4.4.2 WLAN Cards

4.4.3 PSI-1601 Microwave Photonic Links

4.4.4 Fiber Farm

4.4.5 Antenna

4.4.6 Connectors

38

38

38

39

40

41

41

42

45

47

48

50

5 RESULTS AND ANALYSIS

5.1 Introduction

5.2 Mikrotik Routerboard Set-up

5.2.1 Point-to-point Links Connection

5.2.2 Nstreme2 Application

5.3 Experiments

5.3.1 Experiment 1: Testing the Equipments used

5.3.1.1 Experiment 1(a): Power and frequency

5.3.1.2 Experiment 2(b): Power from PSI-1601

5.3.2 Experiment2: Performance Analysis of Nstreme2

5.3.3 Experiment3: Performance Analysis of RoF Link

51

51

51

52

55

59

59

59

60

63

69

x

6 CONCLUSION AND FUTURE WORK

6.1 Conclusion

6.2 Future Work

75

75

76

REFERENCES

Appendices A-E

78

81-86

xi

LIST OF TABLES

TABLE NO.

3.1

3.2

3.3

4.1

4.2

4.3

4.4

4.5

4.6

5.1

5.2

5.3

TITLE

Evolution of WLAN standards

802.11 networks standards

Main Parameters of the OFDM

RB433 Specifications

R52 Specifications

WLM54AG 6B-SuperAG Specifications

Specification of PS-1601 Microwave Photonic Links

Technical specifications for fiber farm

Technical specifications for panel antenna

Experimental Result for 100m distance (P16 to P04)

Experimental Result for 1km distance (P16 to Institut

Ibnu Sina)

Experimental Result for Experiment 3

PAGE

21

22

27

42

44

45

46

48

49

67

67

68

xii

LIST OF FIGURES

FIGURE NO.

1.1

2.1

2.2

2.3

2.4

3.1

3.2

3.3

4.1

4.2

4.3

4.4

4.5

4.6

4.7

4.8

4.9

5.1

TITLE

Components of a narrowband wireless access network

The concept of radio over fiber system

Optical transmission link

Intensity-modulation direct-detection (IMDD) analogue

optical link.

Representative RoF link configurations (a) EOM, RF

modulated signal (b) EOM, IF modulated signal (d) direct

modulation

Timing diagram of a IEEE 802.11 successful

transmission

The PCF of the 802.11 MAC protocol

The DCF of the 802.11 MAC protocol

Flowchart of the experiment process

Proposed system for broadband internet backhaul link

based on WLAN and RoF technology

Mikrotik routerboard

R52 wireless card used in one station

WLM54AG 6B-SuperAG

PSI-1601 Microwave photonic links

Fiber farm

Panel antenna

SMA connector, FC/APC cable and power splitter

Links connection

PAGE

3

8

12

16

19

29

31

32

39

40

42

43

43

46

47

49

50

52

xiii

5.2

5.3

5.4

5.5

5.6

5.7

5.8

5.9

5.10

5.11

5.12

5.13

5.14

5.15

5.16

5.17

5.18

5.19

5.20

5.21

5.22

5.23

5.24

5.25

5.26

5.27

5.28

5.29

Access point configuration result

IP address for access point

Station (client) configuration result

IP address for station (client)

Ping from access point to station

Nstreme2 link connection

First WLAN card, second WLAN card and Nstreme2

interface setting

Enabling Nstreme2

Assigning IP address and creating the bridge

First WLAN card, second WLAN card and Nstreme2

interface setting

Enabling Nstreme2

Assigning IP address and creating the bridge

Experimental setup for testing the radio card

Experimental setup for testing the RoF link

Experiment 2 (b)

Result from portable spectrum analyzer

Spectrum analyzer with lower noise level

Experimental setup for Nstreme2

Experimental setup for point to point (P2P)

Communication from P04 to P16

Station at Institut Ibnu Sina

Station at P16

Communication between P16 to Institut Ibnu Sina

Planned experimental setup for experiment 3

Actual experimental setup for experiment 3

Different lengths of fiber used in experiment 3

Fiber farm used to demonstrate the fiber length

Graph speed versus fiber length

53

53

54

54

55

55

56

56

57

57

58

58

60

61

61

62

62

63

63

64

64

65

65

69

70

70

71

73

xiv

LIST OF ABBREVIATIONS

RAP - Remote Access Point

BS - Base Station

CS - Central Station

RS - Remote Station

RoF - Radio over Fiber

MU - Mobile Unit

WTU - Wireless Terminal Unit

BB - Base Band

IF - Intermediate Frequency

RF - Radio Frequency

DCF - Distributed Coordination Function

MAC - Medium Access Control

2G - Second Generation

3G - Third generation

CDMA - Code Division Multiple Access

GPRS - General Packet Radio Service

xv

WLAN - Wireless Local Area Network

SMF - Single Mode Fiber

EMI - Electromagnetic Interference

NF - Noise Figure

DR - Dynamic Range

RIN - Relative Intensity Noise

OFDM - Orthogonal Frequency Division Multiplexing

BER - Bit Error Rate

AM - Amplitude Modulation

FM - Frequency Modulation

PM - Phase Modulation

ASK - Amplitude Shift Keying

FSK - Frequency Shift Keying

PSK - Phase Shift Keying

OOK - On-off Keying

BB - Baseband

PD - Photodiode

IMDD - Intensity Modulation Direct Detection

PSTN - Public Switched Telephone Network

LD - Laser Diode

EOM - External Optical Modulator

MH - Mobile Host

SDRAM - Synchronous Dynamic Random Access Memory

DDR - Double Data Rate

CPU - Central Processing Unit

xvi

LIST OF SYMBOLS

km - Kilometer

µs - Microsecond

nm - Nanometer

mm - Milimeter

G - Giga

H - Hertz

T - Tera

dB/km - Decibels per Kilometer

xvii

LIST OF APPENDICES

APPENDIX

A

B

C

D

E

TITLE

Nstreme2 Group Settings

Experiment 2 (P16 to P04) details result

Experiment 2 (P16 to Ibnu Sina) details

result

Experiment 3 details result

Data sheets

PAGE

81

82

83

84

85

86

1

CHAPTER 1

INTRODUCTION

1.1 Project Background

In cellular networks, the current trends now are to reduce cell size to

accommodate more users and to operate in the microwave/millimeter wave

frequency bands to avoid spectral congestion in lower frequency bands. This requires

a large number of base stations (BS) to cover a service area. The base station also

must be cost effective to make it success in market. This requirement has led to the

development of system where functions such as signal routing or processing,

handover and frequency allocation are carried out at a central control station (CS),

rather than at the BS. An interesting way for connecting a CS with BSs in such a

radio network is through an optical fiber network, since fiber has low loss, immunity

to EMI and broad bandwidth. The radio signals from CS are transmitted over optical

fiber and will be radiated by remote antennas. The cost is reduced since the BS or

Remote Station (RS) needs to perform only simple functions, and it is in small size.

Besides that, the resources provided by the CS can be shared among many antenna

BSs. This technique of modulating the radio frequency (RF) subcarrier onto an

optical carrier for distribution over a fiber network is known as radio over fiber

(RoF) technology [1].

2

Interest in RoF network has been gaining increasing popularity for RF

distribution networks. This project examines the link transmission quality and

performance characteristics of RoF between the CS and RS by experiment. The

signal used in this project is 5GHz signal compliant to IEEE 802.11a standard.

Signal strength, speed and throughput of the experimental link are presented as a

performance indicator to show the effectiveness of RoF signal distribution. A

proposed system of RoF based on IEEE 802.11a is used for this purpose.

1.2 Problem Statement

Figure 1.1 illustrates the configuration of narrowband wireless access systems

(e.g. GSM). The central office handles call processing and switching, while the Base

Stations (BS) act as the radio interfaces for the Mobile Units (MU) or Wireless

Terminal Units (WTU). The BSs may be linked to the central station (CS) through

either analogue microwave links or digital fiber optic links. Once the baseband

signals are received at the BS, they are processed and modulated onto the appropriate

carrier. The radius covered by the signal from the BS is the cell radius.

All the MU/WTU within the cell, share the radio frequency spectrum. In

general, low carrier frequencies offer low bandwidth. Low-frequency RF signals

allow for larger cells, due to the longer reach of the radio waves. The larger cells

enable high mobility, but lead to poor spectrum efficiency, since the spectrum is

shared by all MUs/WTUs operating within the cell. Therefore, for broadband

wireless communication systems to offer the needed high capacity, it appears

inevitable to increase the carrier frequencies and to reduce cell sizes [2].

The need for increased capacity per unit area leads to higher operating

frequencies (above 6GHz) and smaller radio cells. To reduce the system installation

and maintenance costs of such system, it is imperative to make the remote access

point (RAP) as simple as possible. This may be achieved by consolidating signal

3

processing functions at a centralized headend or central station. Because of this, RoF

technology is introduced and IEEE 802.11a is a very attractive standard due to

several advantages.

Figure 1.1: Components of a narrowband wireless access network [8]

However, in RoF systems, the longer the fiber length the higher the delay

imposed to the system. For example, using 1km of fiber introduces approximately

5µs of delay to each packet that passes through. This extra propagation delay poses a

challenge to the system design since this delay exceeds the 1µs propagation delay

boundary defined in the IEEE 802.11 standard where only wireless propagation is

assumed [6]. As a result, the performance of the distributed coordination function

(DCF) of the medium access control (MAC) layer may degrade significantly or even

break down entirely. It is noted that network fails long before physical layer

limitations due to the timeout values defined within the MAC protocol.

4

1.3 Objective

The objective of this project is to analyze the performance of RoF system by

experiment. A proposed system of RoF is used for this purpose. The performance

parameter such as signal strength, speed and throughput is measured by experiment.

The measurement of the performance parameter is analyzed.

1.4 Scopes

In order to achieve the objective of this project, there are following scopes

will be covered:

(i) To study and understand the concept of RoF system.

(ii) This project will focus on set up and analyze the performance of RoF system.

(iii) The equipments that will be used for the experiment are recognized.

(iv) The analysis will be carried out by experiment.

1.5 Project Report Outline

The project report consists of six chapters which include Introduction; RoF

Technology; IEEE 802.11 WLAN Protocol; Research Methodology; Results and

Analysis, and finally Conclusion and Future Works.

For Chapter Two, RoF technology, will explain about the introduction of

RoF, its advantage, its application and its optical transmission link.

5

In Chapter Three, IEEE 802.11 WLAN standards will cover about the

characteristics of IEEE 802.11 standards, the IEEE 802.11 MAC protocol and the

feasibility of applying RoF into WLAN standard. Besides that, this chapter also

shows brief explanation about current and past researches regarding the issue on this

project.

Chapter Four is explained about the research methodology. While Chapter

Five shows the result and analysis of this project. And lastly, the conclusion and

future work are stated in Chapter Six.

78

REFERENCES

1. K. Lee, “Radio over Fiber for Beyond 3G,” 2005 IEEE International Topical

Meeting on Microwave Photonics, 2005, pp. 9-10

2. M. J. Cryan, M. Dragas, J. Kung, V. Jain, F. Fornetti, T. Houle, R. Varazza,

and M. Hill, “A 2.4-GHz wireless-over-fiber transceiver using photonic

active integrated antennas (PhAIAs),” Microwave and Optical Technology

Letters, vol. 48, pp. 233-237, 2006

3. T. Prakoso, R.Ngah, T. A. Rahman, Z. Ghassembloy, “A High Gain Active

Photonic Antenna for high speed Backhaul Link: A System Analysis”, 17th

International Conference on Telecommunications (ICT2010), 4-7 April 2010,

Doha Qatar.

4. A. Cerquira, D.C Valente e Silva. “Performance Analysis of a Radio over

Fiber System based on IEEE 802.15.4 standard in a real optical network”,

Mikrowave and Optical Technology Letters, Vol. 51, August 2009.

5. M.L. Yee, A. N. Oma, M. Sauer, “Performance Analysis of IEEE 802.16e

WIMAX Radio over Fiber Distributed Antenna System”, Microwave

Symposium Digest, 2009. MTT’09. IEEE MTT-S International

6. B. K Sabet, M. Mjeku, N. J Gomes, “Performance Impairments is Single

Mode Radio over Fiber Systems Due to MAC Constraints”, Journal of

Lightwave Technology, Vol. 26, Issue 15, pp. 2540-2548, 2008

7. B. K Hong, “Radio over Fiber based Network Architecture”, Master Thesis,

Berlin 2003.

8. N. O Anthony, “Radio over Fiber Technology for Broadband Wireless

Communication System”, PhD thesis, Zambia, 2005.

9. D. Novak, “Fiber Optics in Wireless Applications”, OFC 2004 Short Course

217, 2004.

10. D. Wake, “Radio over Fiber Systems for Mobile Applications in Radio over

Fiber Technologies for Mobile Communications Networks”, H. Al-

Raweshidy, and S. Komaki, ed. (Artech House, Inc, USA, 2002).

79

11. A. Powell, “Radio over Fiber Technology: Current Applications and Future

Potential in Mobile Networks – Advantages and Challenges for a Powerful

Technology in Radio over Fiber Technologies for Mobile Communications

Networks”, H. Al-Raweshidy, and S. Komaki, ed. (Artech House, Inc, USA,

2002).

12. LAN / MAN Standard Committee, “DRAFT Supplement to the IEEE

P802.11a/D7.0 Standard”, IEEE Standards Department, USA, 1999.

13. E. I. Ackerman and C. H. Cox, “RF Fiber-Optic Link Performance”, IEEE

Microwave, pp. 50.58, Dec. 2001.

14. H. Al-Raweshidy and S. Komaki, editors, “Radio over Fiber Technologies

for Mobile Communications Networks”, Norwood: Artech House, 2002.

15. W. David, N. Anthony, J.G. Nathan, “Radio over fiber Link Design for Next

Generation Wireless Systems”, Journal of Lightwave Technology, vol. 28,

issue 16, pp. 2456-2464, 2010.

16. S.P. Chul, Y.K. Yeo, L.C. Ong, “Demonstration of the GbE Service in the

Converged Radio over Fiber/Optical Networks”, Journal of Lightwave

Technology, Vol. 28, Issue 16, pp. 2307-2314,2010.

17. W. Xu, Z. Xiaoping, Z. Hanyi, “BER Performance Analysis of Radio over

Fiber System with Different Modulation Schemes”, Optical Transmission

Systems, Switching, and Subsystems VII. Edited by Chiaroni, Dominique.

Proceedings of the SPIE, Volume 7632, pp. 76321V-76321V-6 ,2009.

18. B. L. Dang and I. Niemegeers, “Analysis of IEEE 802.11 in Radio over Fiber

Home Networks,” Proceedings of the IEEE Conference on Local Computer

Networks 30th

Anniversary: IEEE Computer Society, 2005.

19. K.K. Leung, M. V. Clark, B. McNair, Z. Kostic, L. J. Cimini, and J. H

Winters, “Outdoor IEEE 802.11 Cellular Networks: Radio and MAC Design

and Their Performance,” IEEE Transactions on Vehicular Technology,

vol.56, pp.2673-2684, September 2007.

20. E. Lopez-Aguilera, J. Casademont, and J. Cotrina, “Propagation delay

influence in IEEE 802.11 outdoor networks,” Journal Wireless Networks,

Volume 16 Issue 4, May 2010

21. L. Kleinrock, Queueing Systems, Vol. 2: Computer Applications, Hoboken,

NJ: Wiley, 1976, p.398.

80

22. IEEE 802.11: Wireless LAN Medium Access Control (MAC) and Physical

Layer (PHY) Specifications. (2007 revision). IEEE-SA. 12 June 2007.