wdm optical interfaces for future fiber radio systems phần 9 pot

5.32: Measured BER curves as a function of received optical power for the multiplexed uplink signal, S U3 , C U3 after transmission over 10 km of SMF with the back-to-back 0.0 km SMF c

performance significantly In addition, the optical spectrum in Fig 5.31(b) shows that the uplink signal is contaminated by the out-of-band reflected crosstalk from the downlink direction, which is approximately -17 dB This unwanted power can be removed (as shown in Fig 5.31c) by the suitable selection of an optical BPF that follows the EDFA in order to minimise the out-of-band ASE noise as shown in Fig 5.27 Also, in a practical network each of the WI-DWDM uplink signals will be demultiplexed at the CO before detection, therefore the out-of-band crosstalk from the downlink path does not require any special attention, and will merge with the typical crosstalk caused by the filtering characteristic of the demultiplexer

To measure the BER, the filtered uplink signal was subsequently detected and data was recovered using the data recovery circuit previously described in the downlink path Fig 5.32 shows the measured BER curves for the back-to-back condition (with the MUX/DEMUX scheme but no transmission fibre) and after transmission over 10 km of SMF for the signal, (SU3, CU3) The result exhibits a negligible 0.3 dB power penalty at a BER of 10-9 which can be attributed to experimental errors Therefore, the recovered optical spectra and the BER curves

-6 -7 -8 -9

-6 -7 -8 -9

with 0.0 KM SMF with 10 KM SMF

Fig 5.32: Measured BER curves as a function of received optical power for the multiplexed

uplink signal, (S U3 , C U3 ) after transmission over 10 km of SMF with the back-to-back (0.0 km SMF) curve as a reference The uplink signal was generated using an optical carrier separated by

500 GHz from the downlink carrier

clearly demonstrate the functionality of the proposed DEMUX/MUX scheme in multiplexing the uplink signals with optical carriers at wavelengths equal to the difference between the downlink optical carriers and 5 × FSR

5.7.4.2 Uplink by Reusing Downlink Optical Carrier

Fig 5.33(a) shows the measured optical spectrum of the downlink signal after recovering 50% of the carrier, while Figs 5.33(b) – (c) present the optical spectra for the recovered optical carrier and the generated uplink (SU3, CU3) before entering the

1555.9 1556.3 1556.7 Wavelength (nm)

C U3

-60 -40

C U3

-60 -40

-80

-20

S U3

1555.9 1556.3 1556.7 Wavelength (nm)

C U3

-60 -40

-80

-20

S U3

(c)

Fig 5.33: Measured optical spectra of: (a): the downlink signal, (SD3 , C D3 ) after recovering 50%

carrier, (b): the recovered optical carrier, and (c): the uplink signal, (SU3 , C U3 ) generated using the

recovered carrier

DEMUX/MUX scheme respectively As expected, due to recovering 50% of optical carrier, the CSR of the downlink signal is reduced by 3 dB, which eventually contributes in improving the link performance, as illustrated in Section 5.4.2 Spectra of Fig 5.33(b)-(c) show that uplink DE-MZM experiences an unusual insertion loss of 16 dB resulting in a weaker uplink signal Such situation can be avoided by placing a suitable DE-MZM having lower OSSB+C generation loss (typical loss < 9 dB)

Fig 3.34(a) presents the multiplexed uplink signal at the CO after transmission over 10 km of SMF, while Fig 5.34(b) presents the unwanted crosstalk at the CO from the downlink path (in the absence of uplink signal in the link) The spectra indicate that due to traversing through the AWG, the uplink signal is contaminated

by the unwanted in-band and out-of-band crosstalk by the reflections from the downlink path, which is approximately -12 dB here As before, the out-of-band crosstalk from the downlink path does not require any special attention, and will merge with typical crosstalk caused by the filtering characteristics of the demultiplexer However, the in-band crosstalk may need to be addressed and managed when deploying such systems in practical networks Fig 5.34(a) also

1555.9 1556.3 1556.7 Wavelength (nm)

-60 -40

-70 -50

-20 -30

-60 -40

-70 -50

-20 -30

-60 -40

-70 -50

-20 -30

Fig 5.34: Optical spectra measured at the CO for: (a): multiplexed uplink signal, (SU3 , C U3 ) after

transmission over 10 KM SMF, and (b): unwanted crosstalk from the downlink path due to

reflections

confirms the CSR of the multiplexed uplink (SU3, CU3) as 5 dB, although before the proposed DEMUX/MUX scheme it was shown as 14 dB (shown in Fig 5.33c) As stated before, this reduction in CSR also improves the sensitivity of the link significantly

To quantify the signal degradation due to transmission over 10 km of SMF, uplink (SU3, CU3) was detected and BER curves measured, both at the beginning (back-to-back) and at the end of the fibre link using the same PD and data recovery circuit

described earlier The recovered BER curves are presented in Fig 5.35 and it can be seen that the uplink (SU3, CU3) experiences a negligible 0.4 dB power penalty at a BER of 10-9, which can be attributed to experimental errors The presented recovered optical spectra and the BER curves clearly demonstrate the functionality of the proposed DEMUX/MUX scheme in multiplexing uplink signals that are generated by employing a wavelength reuse technique which simplifies the BS by

Carrier Reused Uplink

Carrier Reused Uplink

Fig 5.35: Measured BER curves as a function of received optical power for the multiplexed

uplink (S U3 , C U3 ) after transported over 10 km SMF with the back-to-back (0.0 km SMF) curve as

reference, where uplink signal was generated by reusing the downlink optical carrier

eliminating the light source from the uplink path while realising compact, low-cost and light-weight BSs

5.8 Effects of Optical Crosstalk on the Proposed System Technologies

Section 5.4.1 has described the characteristics of the 8 × 8 AWG used in demonstrating the system technologies throughout the Sections 5.4 to 5.7 The characterised results indicate that the proposed schemes incorporating such AWG are contaminated by the adjacent and nonadjacent channels crosstalk of -16 dB to -25 dB and -29 dB to -46 dB respectively The demultiplexed results in Sections 5.6.1 and 5.7.3 also confirm presence of crosstalk from -18 to -30 dB in the demultiplexed signals Moreover, the multiplexed results of the simultaneous MUX/DEMUX scheme described in Section 5.7.4 demonstrate that uplink signals generated by using

37.5 GHz

155Mb/s BPSK

A1 A2 A3 A4 B5

B7 B8 A8

OSSB 3 +C 3

PD and Data Recovery BPF

B7 B8 A8

OSSB 3 +C 3

PD and Data Recovery BPF

OSSB 1 +C 1

OSSB 2 +C 2

S 3 , C 3

Fig 5.36: Experimental setup used to characterise optical crosstalk effects on the performance of

the optical mm-wave signals, using the proposed schemes incorporating AWG.

optical carriers spaced at 500 GHz from the downlink signals are contaminated by as much as -17 dB optical crosstalk, which increases to -12 dB with the uplink signals generated by reusing the downlink optical carriers Therefore, there is the potential to incur performance degradation of the proposed system technologies through optical crosstalk Fig 5.36 shows the simplified experimental setup developed to characterise the effects of optical crosstalk while transmitting the optical mm-wave

signals through the proposed system technologies incorporating AWG Three OSSB+C modulated optical mm-wave signals, each carrying 37.5 GHz-band 155 Mb/s BPSK data, were generated by using three optical carriers at the wavelengths

C1 (1556.0 nm), C2 (1556.2 nm) and C3 (1556.4 nm) The modulated signals were then applied to the AWG as shown in Fig 5.36, where signals (S1, C1) and (S2, C2) follow separate VOAs before being applied The output at port B5 was recovered in

-30

-70 -60 -50

Nonadjacent Crosstalk -30

-70 -60 -50

Nonadjacent Crosstalk

Fig 5.37: Measured optical spectrum of the recovered signal (S3 , C 3 ) with adjacent and

nonadjacent channel crosstalk from neighboring signals (S 2 , C 2 ) and (S 1 , C 1 ) respectively

channel crosstalk from the signals (S2, C2) and (S1, C1) respectively The VOAs are inserted to vary the optical powers of (S1, C1) and (S2, C2) that result in variable optical crosstalk with the recovered signal (S3, C3) Also carrier C3 was provisioned two loop-backs before combining with S3, as the optical mm-wave signals are expected to undergo two loop-backs while multiplexing (as described in Section 5.3) The spectrum of the recovered signal (S3, C3) is shown in Fig 5.37, where the

respective crosstalk components are mentioned in the insets In order to observe the effects of such crosstalk, the adjacent channel crosstalk is varied with a 3–dB interval from -9 dB to -24 dB and the respective BER curves were measured as shown in Fig 5.38 From the Fig 5.38, it can also be seen that another two BER curves were plotted with (i) adjacent channel crosstalk removed, but nonadjacent channel crosstalk present, and (ii) both adjacent and nonadjacent channel crosstalk removed The BER curves indicate that the demonstrated schemes will endure noticeable

Received Optical Power (dBm)

Fig 5.38: Measured BER curves as a function of received optical power for various crosstalk

levels contaminating the recovered signal (S 3 , C 3)

crosstalk induced penalties with the presence of crosstalk levels more than -21 dB, which diminishes to zero when it is less than -21 dB

In order to quantify the gradual changes in performance due to crosstalk, power penalties incurred by the signal (S3, C3) (at a BER of 10-9) at various crosstalk levels are compared and the results are plotted in Fig 5.39 This graph shows that a power penalty of 0.5 dB is observed for an optical crosstalk level of -16 dB, which however increases to 1 dB when the crosstalk level increases to -12 dB

0.4 0.8 1.2 1.6

Fig 5.39: Measured crosstalk induced power penalties, with the gradual increase of crosstalk

levels in the transmitted signals by the demonstrated system technologies for WI-DWDM

mm-wave fibre-radio systems

5.9 Conclusion

This chapter presented novel system technologies incorporating arrayed waveguide grating filters for future wavelength-interleaved DWDM mm-wave fibre-

radio networks WI-MUXs with the capacity to multiplex optical mm-wave signals

to the wavelength interleaving schemes for these networks are proposed, which also improves the link performance by enabling reductions in CSRs of the multiplexed signals WI-DEMUX, capable of demultiplexing wavelength interleaved signals in these networks, is also proposed Moreover, a single MUX-DEMUX scheme for simultaneous multiplexing and demultiplexing is proposed that offers a route towards

a simple network architecture by realising simplified and cost-effective CO and RNs The proposed schemes are based on standard AWG technology, therefore, are suitable for integration with the other conventional technologies found in the optical access or metro domain These schemes incorporating a commercially available 8 × 8 AWG are demonstrated experimentally with three optical mm-wave signals spaced at

25 GHz, each of them carrying 37.5 GHz RF signal with 155 Mb/s BPSK data The error-free (at a BER of 10-9) recovery of data confirms the functionality of the proposed schemes without significant power penalty observed while transported the signals over 10 km of SMF The AWG characteristics affecting the performance of the demonstrated schemes have been investigated experimentally

5.10 References

[1] H Schmuck, R Heidemann, and R Hofstetter, “Distribution of 60 GHz signals to more than

1000 base stations,” Electron Lett., vol 30, pp 59 – 60, Jan 1994

[2] R Heidemann and G Veith, “MM-wave photonics technologies for

Gbit/s-wireless-local-loop”, Proc OECC’98, Chiba, Japan, pp 310 – 311, 1998

[3] J O’Reilly and P Lane, “Remote delivery of video services using mm-waves and optics,” J Lightwave Technol., vol 12, no 2, pp 369-375, 1994

[4] M Shibutani, T Kanai, W Domom, W Emura, and J Namiki, “Optical fiber feeder for

microcellular mobile communication system (H-O15),” IEEE J on Sel Areas in Communications, vol 11, pp 1118-1126, 1993

[5] W I Way, “Optical fibre-based microcellular systems: an overview,” IEICE Trans Commun., vol E 76-B, no 9, pp 1078-1090, 1993

[6] O K Tonguz and J Hanwook, “ Personal communications access networks using subcarrier

multiplxed optical links,” J Lightwave Technol., vol 14, pp 1400-1409, 1996

[7] P Mahonen, T Saarinen, Z Shelby, and L Munoz, “Wireless Internet over LMDS:

architecture and experimental implementation,” IEEE Communications Magazine, vol 39,

pp 126-132, 2001

[8] S Ohmori, Y Yamao, and N Nakajima, “The future generations of mobile communications based on broadband access technologies,”IEEE Communications Magazine vol 38, no 12,

pp 134-142, 2000

[9] J Zander, “Radio resource management in future wireless networks: requirement and

limitations,” IEEE Communications Magazine, vol 35, no 8, pp 30-36, 1997

[10] T Ihara, and K Fujumura, “Research and development trends of millimetre-wave

short-range application systems,” IEICE Trans Commun., vol E 79-B, no 12, pp 1741-1753,

1996

[11] D Wake, D Johansson, and D G Moodie, “Passive pico-cell—New in wireless network

infrastructure,” Electron Lett., vol 33, pp 404-406, 1997

[12] G H Smith, D Novak, and Z Ahmed, "Technique for optical SSB generation to overcome dispersion penalties in fiber-radio systems," Electron Lett., vol 33, pp 74-75, 1997

[13] G H Smith, D Novak, and Z Ahmed, “Overcoming chromatic dispersion effects in

fiber-wireless systems incorporating external modulators,” IEEE Trans Microwave Theory Tech., vol 45, no 8, pp 1410-1415, 1997

[14] L.T Nichols, and R D Esman, “Single sideband modulation techniques and applications,”

Proc Conference on Optical Fiber Communication (OFC'99), San Diego, CA, USA,

THW1-1, 1999

[15] K Kitayama, “Highly spectrum efficient OFDM/PDM wireless networks by using optical

SSB modulation,” Journal of Lightwave Technol., vol 16, no 6, pp 969-976, 1998

[16] A B Sahin, O H Adamczyk, and A E Willner, “Dispersion division multiplexing technique for doubling the spectral efficiency of subcarrier multiplexed data transmission

over fiber optical links,” Proc Conference on Optical Fiber Communication (OFC'01),

Anaheim, CA, USA, paper WCC4, 2001

[17] R P Braun, G Grosskopf, D Rohde, F Schmidt, and G Walf, “Fiber-optic millimeter-wave generation at 64 GHz and spectral efficient data transmission for mobile communications,”

Proc Conference on Optical Fiber Communication (OFC'98), Washington DC, USA, vol 2,

pp 17-18, 1998

[18] A Narasimha, X J Meng, M C Wu, and E Yablonovitch, “Tandem single sideband

modulation scheme to double the spectral efficiency of analog fiber links,” Electron Lett.,

vol 36, no 13, pp 1135–1136, June 2000

[19] A Narasimha, X Meng, C F Lam, M C Wu, and E Yablonovitch, “Maximizing spectral

ation in WDM systems by microwave domain filtering of tandem single sidebands,” IEEE Trans Micro Theo Tech., vol 49, no 10, pp 2042-2027, 2001.

[20] G H Smith, D Novak, and C Lim, “A millimeter wave full-duplex fiber-radio star-tree

architecture incorporating WDM and SCM,” IEEE Photon Technol Lett., vol 10, no 11,

pp 1650-1652, 1998

[21] R A Griffin, P M Lane, and J J O’Reilly, “Radio-over-fiber distribution using an optical

millimeter-wave/DWDM overlay,” Proc Conference on Optical Fiber Communication and the International Conference on Integrated Optics and Optical Fiber Communications (OFC/IOOC'99),San Diego, CA, USA, vol 2, pp 70-72, 1999

[22] C Lim, A Nirmalathas, D Novak, R Waterhouse, and G Yoffe, “A WDM architecture for

millimeter-wave fiber-radio systems incorporating baseband transmission,” IEEE Top Meet

On Microwave Photonics (MWP '99), vol.1, pp 127-130, 1999

[23] M A Al-mumin and G Li, “WDM/SCM optical fiber backbone for 60 GHz wireless

systems,” Proc IEEE Top Meet on Microwave Photonics (MWP2001), Long Beach, CA,

USA, pp 61-64, 2001

[24] K Kojucharow, M Sauer, H Kaluzni, D Sommer, F Poegel, W Nowak, A Finger, and D Ferling, “Simultaneous electrooptical upconversion, remote oscillator generation, and air transmission of multiple optical WDM channels for a 60-GHz high-capacity indoor system,”

IEEE Transactions on Microwave Theory and Techniques, vol.47, pp 2249-2256, 1999

[25] C Lim, A Nirmalathas, D Novak, R S Tucker, and R Waterhouse, “Wavelength- Interleaving Technique to Improve Optical Spectral efficiency In MM-wave WDM Fiber

radio” Lasers and Electro-Optics Society (LEOS ‘01), The 14th Annual Meeting of the IEEE,

San Diego, CA, USA vol 1, pp 54 –55, 2001

[26] C Lim, A Nirmalathas, D Novak, R S Tucker, and R Waterhouse, “Technique for increasing optical spectrum efficiency in millimeter wave WDM fiber-radio,” Electron Lett , vol 37, pp 1043 –1045, 2001

[27] H Toda, T Yamashita, K Kitayama, T Kuri, “A DWDM MM-Wave Fiber Radio system

by optical frequency interleaving for high spectra efficiency,” IEEE Top Meet On Microwave Photonics (MWP '01), pp 85-88, 2001

[28] C Lim, A Nirmalathas, D Novak, and R Waterhouse, “Capacity analysis for a WDM radio backbone incorporating wavelength-interleaving,” Optical Fiber Communication Conference, vol 1, pp 355-357, 2002

fiber-[29] C Lim, A Nirmalathas, D Novak, and R B Waterhouse, “Network performance and capacity analysis for a ring WDM fiber-radio backbone incorporating wavelength-

interleaving,” in Proc OECC Yokohama, Japan, pp 194-195, 2002

[30] C Lim, A Nirmalathas, D Novak, and R B Waterhouse, “Capacity analysis for WDM fiber-radio backbones with star-tree and ring architecture incorporating wavelength

interleaving,” J Lightwave Technol., vol 21, no 12, pp 3308-3315, 2003

[31] C Lim, A Nirmalathas, D Novak, and R Waterhouse, “Capacity analysis and optimum

channel allocations for a WDM ring fiber-radio backbone incorporating wavelength

interleaving with a sectorized antenna interface,” IEEE Top Meet On Microwave Photonics (MWP '02), pp 371-374, 2002

[32] C Marra, A Nirmalathas, C Lim, D Novak, B Ashton, L Poladian, W S T Rowe, T Wang, and J A Besley, “Wavelength-interleaved OADMs incorporating optimized multiple

phase-shifted FBGs for fiber-radio systems,” J Lightwave Technol., vol 21, no 1, pp 32-39,

1210 – 1218, 2005

[36] A Nirmalathas, C Lim, M Attygalle, D Novak, R Waterhouse, and M Bakaul, "Recent

progress in fiber-wireless networks: Technologies and architectures" Proc ICOCN2003,

Bangalore, India, Oct 2003 (invited)

[37] M Bakaul, A Nirmalathas, and C Lim, “Experimental verification of cascadability of WDM

optical interfaces for DWDM Millimeter-wave fiber-radio base station,” IEEE Top Meet On Microwave Photonics (MWP '04), pp 169 –172, 2004

[38] M Bakaul, A Nirmalathas, and C Lim., “Performance characterization of single as well as cascaded WDM optical interfaces in millimeter-wave fiber-radio networks”, IEEE Photon Technol Lett., vol 18, no 1, pp 115-117, 2006

[39] H Toda, T Yamashita, T Kuri, and K Kitayama, “25 GHz channel spacing DWDM multiplexing using an arrayed waveguide grating for 60 GHz band radio on fiber systems,” in

Proc International Topical meeting on Microwave Photonics (MWP’03), Budapest, Hungary, pp 287-290, 2003

[40] M Bakaul, A Nirmalathas, C Lim, D Novak, and R Waterhouse, “Simplified multiplexing

scheme for wavelength-interleaved DWDM millimeter-wave fiber-radio systems”, Proc European Conf Optical Commun (ECOC2005), Glasgow, Scotland, vol 4, pp 809 – 810,

2005

[41] M Bakaul, A Nirmalathas, C Lim, D Novak, and R Waterhouse, “Efficient multiplexing

scheme for wavelength-interleaved DWDM millimeter-wave fiber-radio systems”, IEEE Photon Technol Lett., vol 17, no 12, pp 2718-2720, 2005

[42] T Saito, T Ota, T Toratani, and Y Ono, “16-ch Arrayed Waveguide Grating Module with

100-GHz Spacing,” Furukawa Review, no 19, pp 47-52 , 2000

[43] K A McGreer, “Arrayed Waveguide Gratings for Wavelength Routing”, IEEE Communications Magazine, December 1998

[44] C Dragone, “Efficient Techniques for widening the passband of a wavelength router”, J of Lightwave Technol., vol 16, no 10, pp 1895 – 1906, 1998

[45] P Munoz, D Pastor and J Capmany, “Analysis and design of arrayed waveguide gratings

with MMI couplers”, Optics Express, vol 9, no 7, 2001

[46] K.Okamoto and A Sugita, “Flat Spectral response Arrayed Waveguide Grating multiplexer

with parabolic waveguide horns” Electron Lett., vol 32, pp 1661-1662, 1996

[47] S Suzuki, “Arrayed Waveguide Gratings for dense-WDM systems”, in Proc IEEE/LEOS Summer Topical Meeting on WDM components Technology, Montreal, Canada, pp 80 – 81,

Aug 11-15, 1997

[48] T Kamalakis and T Sphicopoulos, “An Efficient Technique for the Design of an

Arrayed-Waveguide Grating with Flat Spectral Response”, J Lightwave Technol., vol 19, no 11, pp

1716-1725, 2001

[49] M C Parker and S D Walker, “A Fourier-Fresnel Integral-Based Transfer Function Model

for a Near-Parabolic Phase Profile Arrayed Waveguide Grating”, IEEE Photon Technol Lett., vol 11, no 8, pp 1018-1020, 1999

[50] M K Smit, C V Dam, “Phasar based WDM-devices: principles, design and applications”,

IEEE J Selected Topics in Quantum Electron., vol 2, no 2, pp 236-250, 1996

[51] A Klekamp and R Munzer, “Imaging Errors in Arrayed Waveguide Gratings”, IEEE Optical and Quantum Electron., vol 35, pp 333-345, 2003

[52] P Munoz, D Pator, and J Capmany “Modelling and Design of Arrayed Waveguide

Gratings”, J Lightwave Technol., vol 20, no 4, pp 661-674, 2002

[53] J Lam and L Zhao “Design Trade-offs For Arrayed Grating DWDM MUX/DEMUX”, in Proc SPIE WDM and Photonic Switching Devices for Network Applications, vol 3949, pp

90-98, April 2000

[54] H Yamada, K Takada and S Mitachi, “Crosstalk Reduction in a 10 GHz Spacing

Arrayed-Waveguide Grating by Phase-Error Compensation,” J of Lightwave Technol., vol 16, no 3,

pp 364-371, 1998

[55] C Lim, M Attygalle, A Nirmalathas, D Novak, and R Waterhouse, “Optimum modulation

depth for performance improvement in fiber-radio links,” IEEE Top Meet On Microwave Photonics (MWP '04), Maine, USA, pp 89-92, 2004

[56] C Lim, A Nirmalathas, D Novak, and R Waterhouse, “Capacity analysis and optimum

channel allocations for a WDM ring fiber-radio backbone incorporating wavelength

interleaving with a sectorized antenna interface,” IEEE Top Meet On Microwave Photonics (MWP '02), pp 371-374, 2002

[57] A Nirmalathas, C Lim, M Attygalle, D Novak, R Waterhouse, and M Bakaul, "Recent

progress in fiber-wireless networks: Technologies and architectures" Proc ICOCN2003,

Bangalore, India, Oct 2003 (invited)

[58] H Toda, T Yamashita, K Kitayama, T Kuri, “Demultiplexing using an arrayed-waveguide grating for frequency-interleaved DWDM radio-on-fiber systems with 25-GHz channel

spacing,” Proc Int Soc Opt Eng (SPIE), vol 4906, USA, pp 99-106, 2002

[59] H Toda, T Yamashita, K.-I Kitayama, and T Kuri, "A demultiplexing scheme using an arrayed-waveguide grating for a DWDM mm-wave fiber-radio system by optical frequency

interleaving," Proc 8th Microoptics Conference (MOC'01), C2, pp 40-43, Osaka, Japan,

2001

[60] H Toda, T Yamashita, T Kuri, K I Kitayama,, “Demultiplexing using an waveguide grating for frequency-interleaved DWDM millimeter-wave radio-on-fiber

arrayed-systems,” J Lightwave Technol., vol 21, pp 1735-1741, 2003

[61] A Nirmalathas, C Lim, D Novak, R Waterhouse, “Optical interfaces without light sources for base station designs in fiber-wireless systems incorporating WDM,” IEEE Top Meet On Microwave Photonics (MWP '99), vol.1 pp.119-122, 1999

[62] A Nirmalathas, D Novak, C Lim, R Waterhouse, “Wavelength Reuse in the WDM Optical

Interface of a Millimeter-Wave Fiber-Wireless Antenna Base Station,” IEEE Trans Microwave Theory Tech., vol 49, pp 2006-2012, 2001

[63] M Bakaul, A Nirmalathas, C Lim, D Novak, and R Waterhouse, “Simplified multiplexing

systems”, in Proc International Topical meeting on Microwave Photonics (MWP2005),

Seoul, South Korea, pp 63-66, 2005

[64] M Bakaul, A Nirmalathas, C Lim, D Novak, and R Waterhouse, “Simultaneous multiplexing and demultiplexing of wavelength-interleaved channels in DWDM millimeter-

wave fiber-radio networks, submitted to J Lightwave Technol., 2005