OFC/NFOEC 2008 OThP3.pdf which is inherent to the OFm principle yields an increase of the Stimulated Brillouin Scattering(SBS) threshold and thus it enables to transport significantly higher optical power levels and generate stronger microwave signal from the antenna Experimentally it was observed that the OFM system on a 25 km SMF link exhibited a much higher SBS threshold than the IM-DD system(ic. 7 dB higher, from 10 to 50 mW) 4. Radio over multimode fiber in in-building networks Multimode(silica or plastic) optical fiber is widely used in in-building networks, due to its ease of installation. Its modal dispersion, however, is hampering radio signal transport. The OFM technique has shown to be robust against modal dispersion; it has been derived mathematically that its generated harmonics scale with the fiber's frequency characteristics. Thanks to the very pure microwave carrier generated with the OFM technique, transmission of 16-QAM and 64-QAM signals up to 120 Mbit/s in the 24-30 GHz band has successfully been demonstrated over 4.4 km of silica 50um core graded index fiber [4]. Using five subcarriers, over the same link simultaneous transmission of five 64-QAM signals with a total bitrate of 210 Mbit/s has been demonstrated [5]. Also a 100 Mbit/s 16-QAM bidirectional system at 17.2 GHz over 100m of 50um core graded-index POF has been shown, where for upstream transmission the microwave signal received at the antenna site is downconverted with the 17.2 GHz microwave carrier generated at the headend; see Fig. 5 [6]. When creating pico-cells for broadband wireless communication at high microwave frequencies, the required line-of-sight prevents communication between rooms However, transparent transport of the microwave signals by means of radio-over-fiber techniques can establish communication between two or more rooms. Fig. 6 shows how with a transparent optical switch in the HCC (Home Communication Controller) rooms can flexibly be interconnected, and thus their pico-cells can be merged into a reconfigurable"wireless virtual private network", without interference with other wireless VPN-S. The remote antenna concept will add latency with respect to the conventional case where the wireless protocols are terminated in the base station at the antenna site. This will reduce the network's throughput. For centrally scheduled MAC protocols, such as WiMAX, it has been shown that this reduction will be only small(<1%)when fiber link lengths re less than 500 metres 四向 ntenna Unit 一AA单二m<画日 Fig 6 Flexible inter-room wireless communication using switched Fig 5 16-QAM 100 Mbit/s 17.2 GHz bi-directional RoF links radio-over-POF link 5. Conclusions Radio-over-Fiber technologies can provide transport of broadband microwave signals for SMF and MMF based networks. Flexible al routing and dispersion-robust transport techniques, such as Optical Frequency Multiplying, enable to improve the networks throughput and operational efficiency 6. References [1R.A Griffin, P.M. Lane, J.J. O'Reilly, "Radio-over-fibre distribution using an optical millimeter-wave/DWDM overlay", Proc. OFC 99, San Diego,Feb.22-25,1999 WD6 22]A MJ al fibre/ wireless lan ao etworks, in Broadband Optical Access Networks and Fiber-to-the-Home: System Technologies and Development Strategies. New York: Wiley, 2006 3] A. Ng'oma, G-J. Rijckenberg, A M.J. Koonen, "Building extended-recah radio-over-fiber links by exploiting Optical Frequency Multiplications dispersion tolerance", Proc. IEEE Int. Microwave Symp, Honolulu, June 3-8, 2007 nks", Proc. of Int. Top Meeting on Microwave Phot, Grenoble, Oct 3-6, 2006 5] H. Yang, M. Garcia Larrode, G-J. Rijckenberg, A Ng'oma, E. Tangdiongga, A M.J.Koonen, "Radio-over-fibre transmission of multi-carrier 64-QAM radio signal at 18 GHz", Proc. of Broad Band Europe, Antwerp, Dec 3-6, 2007 Polymer Optical Fiber-based System for Distributing 100 Mbps WiMAX Signals Exceeding 17 GHz, Proc. of AP-MWP2007, Jeju Island, South Korea, April 25-27, 2007which is inherent to the OFM principle yields an increase of the Stimulated Brillouin Scattering (SBS) threshold, and thus it enables to transport significantly higher optical power levels and generate stronger microwave signals from the antenna. Experimentally it was observed that the OFM system on a 25 km SMF link exhibited a much higher SBS threshold than the IM-DD system (i.c. 7 dB higher, from 10 to 50 mW). 4. Radio over multimode fiber in in-building networks Multimode (silica or plastic) optical fiber is widely used in in-building networks, due to its ease of installation. Its modal dispersion, however, is hampering radio signal transport. The OFM technique has shown to be robust against modal dispersion; it has been derived mathematically that its generated harmonics scale with the fiber’s frequency characteristics. Thanks to the very pure microwave carrier generated with the OFM technique, transmission of 16-QAM and 64-QAM signals up to 120 Mbit/s in the 24-30 GHz band has successfully been demonstrated over 4.4 km of silica 50µm core graded index fiber [4]. Using five subcarriers, over the same link simultaneous transmission of five 64-QAM signals with a total bitrate of 210 Mbit/s has been demonstrated [5]. Also a 100 Mbit/s 16-QAM bidirectional system at 17.2 GHz over 100m of 50µm core graded-index POF has been shown, where for upstream transmission the microwave signal received at the antenna site is downconverted with the 17.2 GHz microwave carrier generated at the headend; see Fig. 5 [6]. When creating pico-cells for broadband wireless communication at high microwave frequencies, the required line-of-sight prevents communication between rooms. However, transparent transport of the microwave signals by means of radio-over-fiber techniques can establish communication between two or more rooms. Fig. 6 shows how with a transparent optical switch in the HCC (Home Communication Controller) rooms can flexibly be interconnected, and thus their pico-cells can be merged into a reconfigurable “wireless virtual private network”, without interference with other wireless VPN-s. The remote antenna concept will add latency with respect to the conventional case where the wireless protocols are terminated in the base station at the antenna site. This will reduce the network’s throughput. For centrally scheduled MAC protocols, such as WiMAX, it has been shown that this reduction will be only small (<1%) when fiber link lengths are less than 500 metres. Fig. 5 16-QAM 100 Mbit/s 17.2 GHz bi-directional radio-over-POF link HCC access network fibres (POF) Fig. 6 Flexible inter-room wireless communication using switched RoF links 5. Conclusions Radio-over-Fiber technologies can provide transport of broadband microwave signals for SMF and MMF based networks. Flexible optical routing and dispersion-robust transport techniques, such as Optical Frequency Multiplying, enable to improve the network’s throughput and operational efficiency. 6. References [1] R.A. Griffin, P.M. Lane, J.J. O’Reilly, “Radio-over-fibre distribution using an optical millimeter-wave/DWDM overlay”, Proc. OFC’99, San Diego, Feb. 22-25, 1999, paper WD6 [2] A.M.J. Koonen and A. Ngoma, “Integrated broadband optical fibre/ wireless LAN access networks,” in Broadband Optical Access Networks and Fiber-to-the-Home: System Technologies and Development Strategies. New York: Wiley, 2006 [3] A. Ng’oma, G.-J. Rijckenberg, A.M.J. Koonen, “Building extended-recah radio-over-fiber links by exploiting Optical Frequency Multiplication’s dispersion tolerance”, Proc. IEEE Int. Microwave Symp., Honolulu, June 3-8, 2007 [4] M. Garcia Larrode, A.M.J. Koonen, J.J. Vegas Olmos, “Transmission of microwave signals beyond the modal bandwidth of multimode fiber links”, Proc. of Int. Top. Meeting on Microwave Phot., Grenoble, Oct. 3-6, 2006 [5] H. Yang, M. Garcia Larrode, G.-J. Rijckenberg, A. Ng’oma, E. Tangdiongga, A.M.J. Koonen, “Radio-over-fibre transmission of multi-carrier 64-QAM radio signal at 18 GHz”, Proc. of BroadBand Europe, Antwerp, Dec. 3-6, 2007 [6] A. Ng’oma, J. Zeng, H.P.A. van den Boom, Y. Watanabe, A.M.J. Koonen, “Bi-Directional Polymer Optical Fiber-based System for Distributing 100 Mbps WiMAX Signals Exceeding 17 GHz”, Proc. of AP-MWP2007, Jeju Island, South Korea, April 25-27, 2007 a828_1.pdf OThP3.pdf OFC/NFOEC 2008