Analysis of Sub-Carrier Multiplexed Radio Over Fiber Link for the Simultaneous Support of WLAN and WCDMA Systems

The present third generation (3G) wireless technology can provide data oriented applications. However, the bit rate is limited to around 2 Mbps with limited mobility. Today, more applications demand high data rate and reasonable mobility. Therefore, by integrating 3G cellular system and wireless local area network (WLAN), there is a potential to push the data rate higher. This integration means 3G cellular users can enjoy high data rate at a location that is within WLAN coverage area. Similarly, WLAN users also can have data services as long as they are under the coverage of the 3G cellular system. The 3G cellular system has a much larger coverage than the WLAN. In this paper, we present the first step toward an integration of the two systems. This paper presents a fiber-wireless architecture that simultaneously supports the wideband code division multiple access (WCDMA) system and the IEEE 802.11b WLAN. Our approach uses sub-carrier multiplexed (SCM) architecture to combine and transmit 2.4 GHz WLAN and 1.9 GHz WCDMA signals through an optical fiber from a central base station (CBS) to a radio access point (RAP, single antenna unit). After the fiber, the signals continue to propagate through the air interface to respective mobile stations. The WLAN access point is also located at the CBS. For the SCM architecture, we investigate three areas: i) the signal to noise ratio of the uplink and the downlink, ii) the cell coverage area for the WCDMA and WLAN systems, and iii) the throughput of the IEEE 802.11b WLAN. Our results show that with up to 2.5 km cell radius, better than 18 dB SNR is possible with 5 km fiber link for WLAN system. Simultaneously, the WCDMA system has at least 18 dB SNR for a cell coverage radius of 8 km. These numbers depend on the relative RF power of each system in the fiber.Roland M.C. Yuen received a Bachelor of Electrical Engineering degree in 2003 from Ryerson University, Toronto, Canada. He is pursuing a Master of Applied Science degree at Ryerson University. He has a conference paper. His research interests are in the area of optical and wireless communications.Currently, he works on unique fiber based architecture to extend the capability of cellular networks and support wireless LANs simultaneously.Xavier N. Fernando () obtained B.Sc. Eng. (First Class Honors) degree from Sri Lanka, where he was first out of 250 students. He got Master’s degree from the Asian Institute of Technology (Bangkok) Ph.D. from the University of Calgary, Canada in affiliation with TRLabs. He has worked for AT&T for three years as an R&D Engineer. Currently he is an Assistant Professor at Ryerson University, Toronto, Canada.Dr. Fernando one US patent and about 38 peer reviewed publications in journals and conference proceedings. His research focuses on signal processing for cost-effective broadband multimedia delivery via optical wireless networks. Dr. Fernando′s work won the best research paper award in the Canadian Conference of Electrical and Computer Engineering for the year 2001. His student projects won both the first and second prize at Opto Canada – the SPIE regional conference in Ottawa in 2002. He is a senior member of IEEE, member of SPIE, Chair of the IEEE Communications Society Toronto Chapter and licensed Professional Engineer in Ontario, Canada. He has many research grants including Canadian Foundation of Innovations (CFI), Ontario Innovations Trust (OIT) and Natural Sciences and Engineering Research Council (NSERC) of Canada.