dwdm effects of single model optical fiber in radio over fiber system

8/22/2019 DWDM Effects of Single Model Optical Fiber in Radio Over Fiber System

1/3

DWDM Effects of Single Model Optical Fiber in Radio over Fiber System

Ehsan Dadrasnia

Dept. of Electrical Engineering

Faculty of Engineering

University of Malaya

Kuala Lumpur, [email protected]

Faisal Rafiq Mahamd Adikan

Dept. of Electrical Engineering

Faculty of Engineering

University of Malaya

Kuala Lumpur, [email protected]

Abstract One of the problems in the new generation ofradio over fiber networks that requires to be concentrated, isdecreasing the quantity of bit error rate in the lowest powerpenalty. This works studies a new technology for increasingthe capacity of radio network backbone transmissionchannels by combining the two particular radio signal andoptical power technologies. This paper also evaluates theresults of down-link 5Gbps OOK signal of four radio basestations over 50km dense wavelength division multiplexingsingle mode fiber. The outcomes show that the total receivedoptical power penalty is about 0.2dB at bit error rate of 10-9

and quality factor of greater than 7. This amount of bit error

rate can be supposed as a negligible value in the performanceof radio over fiber system for multimedia and real timeapplications.

Keywords-OOK signal; radio over fiber; multiplexing;

DWDM; power penalty; bit error rate.

I. INTRODUCTION

In modern and high-tech communication system, theplan of new generation networks is increasing efficiency,supporting the large number of subscribers and sub-channels in networks. Moreover, the operators try tosupport their users in high level of data rate, anywhere and

anytime. For these reason, indeed, a strong platform isrequired in designing the new telecommunicationnetworks. This paper investigates to model four radiobase-stations that receive high bit-rate radio signals fromthe main control office over one optical fiber link at sametime by dense wavelength division multiplexing (DWDM)technique.

Radio over fiber (ROF) combines two technologies,

radio frequency (RF) and optical light-wave. The

advantages of ROF system is low attenuation loss (about

0.2 [1] to 0.3dB/km [2]), high-speed bandwidth

(approximately 1Tbps [3]), protection from radio

frequency interference, simple installation and low system

maintenance, reduced power with reduced equipments,

supporting of multi-operator with multi- serviceoperation, dynamic resource allocation based on the

wavelength division multiplexing modulation and

providing privacy and security. On the other hand, the

wireless technology provides mobility characteristics for

the great number of mobile users. The indoor wireless

optical communications was invented in 1979 by Gfeller

and Bapst [4]. The first idea of radio over fiber was in

1990 that was used for cordless or mobile telephone

service [5]. It was offered to use the diffuse emissions in

the infrared band for indoor communications [6]. The

wavelength division multiplexing systems have been

developed in the early 1990s. They contain numerous of

various wavelength channels to support the total

throughput, even if it arrives nearly to 1Tbps [7].Particularly, the optical fibers link the back-bone of

the networks in core sides or among central control

offices that is shown in Fig.1. The radio systems addressthe user sides or base stations by providing mobility in

down-link and up-link. The radio users can utilize

wireless, digital cellular communication (e.g. GSM),

microwave or any different type of radio signal. However,

each of mentioned signals would need specific optical

modulators and detectors according to the range of radio

signal frequency.

II. SETUP RADIO OVER FIBER BY DWDM

Fig.2 indicates a simple WDM technology betweenmultiplexer and de-multiplexer where each sender and itsreceiver uses a specific wavelength along an optical fiber.Dense wavelength division multiplexing furthers thetransmission capacity of trunk lines [8]. In general, themodern high-speed DWDM technologies have been builtof many transmission spans. It is composed of an erbium-doped fiber amplifier, a single-mode fiber transmissionsection and a part of dispersion compensating fiber or achirped fiber bragg grating (FBG) [9]. DWDM supports144 wavelengths with 2nm spacing. It allows multiplewavelengths to be combined into one optical signal andincreases the total data rate on one fiber to 1012bps [3,10].

Figure 1. Simple systems radio over fiber system in up/down links [7] .

Optical Fiber

39978-1-4244-7406-6/10/$26.00 c2010 IEEE


2/3

This work models four radio base-stations that receive

5Gbps down-link on-off keying (OOK) radio signal from

main control office. The main control office transmitsdata for the each mentioned radio base-station by dense

wavelength division multiplexing at the same time over

50km single mode optical fiber. This modeling also uses

the direct optical modulator with power -10dBm at

reference range wavelength of 1500nm to 1506nm as

electro-optic component for converting radio signal to

optical light-wave power in main control office. Those

optical powers will be retransferred into radio electrical

signal by PIN photo-detector as opto-electrical device

after traveling through optical fiber by internal total

reflection law. This procedure is for transforming optical

carriers to electrical current based on the correspondingwavelength in radio base-stations. Table.I illustrates the

important and main parameters which are used for the

OOK radio signal over 50km SMF optical fiber.

Figure 2. Wavelengths multiplexing technique [11].

TABLE I. PARAMETERS USED FOR OOK RADIO SIGNAL OVER FIBER

Component name Specificaction / Value

Number of radio trasnmitter

OOK radio signal bit-rate

Laser power (EO)

Fiber optical mode

Channles spacing

Fiber lentgh

Fiber Attenuation loss

Dispesrion index

multiplexing technuqie

Photo-detector (OE)

Photo-detector responsivity

Tempereture

4 base stations

5Gbps

-10dBm

Single mode fiber (SMF)

2nm

50km

0.2dB/km

16.75 ps/nm/km

DWDM

PIN photo-diode

1A/W

25oC

III. RESULT AND DISCUSSION

Reliable and comfortable radio networks are demandedin the modern communication system. Radio over fibersystem indicates an advanced technology for transmissiondata. The radio signal has been sent by mobile user, wouldbe modulated and transmitted over an optical fiber channelin light-wave styles. This is the result of the lowattenuation loss and great bit-rate of optical fiber and alsoradio mobility [12].

The spectrum of the separated optical carriers is shownin Fig.3. The generated 5Gbps OOK radio signals in maincontrol office concurrently send in down-link status for theradio base-stations over single mode fiber by DWDMtechnique. The main control office defines four differentwavelength channels in DWDM technique for each radiobase-station. DWDM supports these channels by spacingof 2nm for avoidance of any interference duringtransmission data. The peak of optical power also occurs atreference wavelengths that have been defined in singlemode fiber and DWDM. Then, down-link 5Gbps OOKradio signals are transmitted just over 50km DWDMsingle mode fiber link without any interference at large bit-rate. Based on the Fig.3 the four stations would transmit

radio signal by unique wavelength. They work on 1500nm(CH1 for first radio transmitter) to 1506nm (CH4 forfourth radio transmitter) by spacing channels of 2nm.

Furthermore, Fig.4 compares the measure of bit errorrate (BER) sensitivity versus total received optical powerbetween back-to-back and 50km length of single modefiber by DWDM technique in the mentioned down-linkradio over fiber system for all transmission channels. Theattenuation loss of fiber is assumed to be 0.2dB/km inoptical transmission link. According to the outcomes fromFig.4, the penalty of total received optical power after50km DWDM single mode fiber is about 0.2dB. Forinstance, the receiver sensitivity power at BER of 10

-10for

the 50km DWDM fiber link is 0.2dB more than back-to-

back. This value of power penalty can be neglected in thedown-link 5Gbps OOK radio signal over optical fiber.This optical power difference is almost constant for allBER quantity and best performance of simulated systemwould be occurred at BER of 10

-12. Lin et al. meuasred

that the power penalty is less than 0.2dB in BER of 10-9

for 4Gbps OOK radio signal over 25km SMF opticaltransmission [13]. The results also show that the signaldelay is insignificant value during this modeling and it isless than 310

-10(sample) in fiber attenuation loss of

0.2dBm/km. The amount of Q factor in this case would bemore than 7. It can be seen that based on the mentionedoutcomes in this paper and others previous works, radioover fiber helps to develop the reliable real-time next

generation networks by significant performance andefficiency.

40 2010 2nd International Conference on Electronic Computer Technology (ICECT 2010)


3/3

Figure 3. Down-link OOK radio signal in four base-stations over50km single mode fiber by DWDM technique.

Figure 4. The measure BER of 5Gbps down-link OOK radio signalover 50km DWDM single mode fiber versus total received optical power

for all transmission channels.

IV. CONCLUSION

It can be concluded that by combining the significantfeatures of both radio and optical technologies, it ispossible to define a transmission system with high

efficiency and performance. This paper has studied thatdense wavelength division multiplexing is an applicableoption (channel spacing 2nm) for developing backbone ofradio over fiber network. It can be concluded that OOKradio signal over DWDM single mode optical fiber wouldbe a suitable solution for the multimedia and real time

network such as fiber to home network (FTTH) with highquality [14].

REFERENCES

[1] H. Al-Raweshidy, Radio Over Fiber Technologies for Mobile

Communications Networks: Artech house Inc., 2002.

[2] A. Ngoma, "Radio-over-fiber technology for broadband wirelesscommunication systems," Eindhoven,The Netherlands, PhD Thesis

9038617232, 2005.

[3] G. P. Agrawal, Fiber-Optic Communication Systems: A John Wiley &

Sons Inc., 2002.

[4] A. J. Cooper, "Fiber/Radio for the provision of cordless/mobile

telephony services in the access," Electronic Letter, vol. 26, pp. 2054-2056, Nov 1990.

[5] S. Hranilovic, Wireless Optical Communication Systems: Springer.,

2005.

[6] F. R. Gfeller and U. Bapst, "Wireless in-house communication via

diffuse infrared radiation," Proceedings of the IEEE,, vol. 67, pp. 1474

1486, November 1979.

[7] C. H. Lee, Microwave Photonics (Optical Science and Engineering

Series): CRC Press., 2006.

[8] K. Kitayama, et al., "Dispersion effects of FBG filter and optical SSB

filtering in DWDM millimeter-wave fiber-radio systems," Lightwave

Technolog, vol. 20, pp. 1397- 407, 2002.

[9] M. Marciniak, "Application of Radio over Fiber Technology to Enable

Converged Optical and Wireless Next Generation Networking," inSecond International Conference on Access Networks & Workshops,

AccessNets '07., 2007, pp. 1-7.

[10] J. R. Vacca, Optical Networking Best Practices Handbook: A John

Wiley & Sons Inc., 2007.

[11] G. P. Agrawal, Lightwave Technology :Telecommunication Systems: A

John Wiley & Sons Inc., 2005.

[12] M. Schwartz, Mobile Wireless communication: Cambridge University

Press., 2005.

[13] C. T. Lin, et al., "Optical direct-detection OFDM signal generation for

radio-over-fiber link using frequency doubling scheme with carriersuppression," Optics Express, vol. 16, April 2008.

[14] D.Opatic, "Radio over Fiber Technology for Wireless Access," Ericsson,Zagreb, Technology2004.

CH1 CH2 CH3 CH4

Back-to-BackAfter 50km

DWDM

2010 2nd International Conference on Electronic Computer Technology (ICECT 2010) 41

dwdm effects of single model optical fiber in radio over fiber system

Documents