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

Abstract

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.

Performance Improvement and Cost Reduction Techniques for Radio Over Fiber Communications

“…Similarly, the harmonics in the photo-detected signal are located at mf 1 Hz and mf 2 Hz, while the second-order and third-order intermodulation products are located at f i ± f j Hz and f h ± f i − f j Hz, respectively, where h, i, j ∈ {1, 2, ..N }, and h, i and j are SCM channel indices [50]. For example, the non-linearity in a ROF link that employs the SCM of two RF frequencies, namely the WCMDA frequency of f 1 = 1.9 GHz and the WLAN IEEE 802.11b frequency of f 2 = 2.4GHz, is discussed in [51]. As seen in Fig.…”

Pilot‐aided estimation and equalisation of a Radio‐over‐Fibre system in Wideband Code Division Multiple Access

“…, is the gain of the pre-amplifier which matches the output power of the transmit RRC filter to the input power of the optical subsystem [8], IBO is the input back-off on a linear scale, m P is the maximum input RF power to the optical subsystem before the pre-amplifier, ) max( …”

Multimedia Hotspots Supporting Wireless LAN and Cellular CDMA Access

“…Using P5,i as the symbol power of the ith WCDMA signal, the WCDMA signal per symbol that is received at the RAP is given as: oo n Swcdma (t) = E:1~2 P, di, k (t) Ci (t) COS (gO,t) (1) where, Ai is the Rayleigh distributed signal amplitude and Ai = V~2P5,i, di,k(t) is the random data sequence, ci(t) is the coded waveform and wc, is the carrier frequency. Similarly, IEEE 802.11 signal that also employs DSSS has the same form …”

“…In order to support large coverage area, many hotspots are required which is a technical and economical challenge. On the other hand, next generation cellular networks supporting relatively low speed services, to large radio cells could be combined with V/LAN hotspots [1]. This integration will provide network connectivity everywhere and high date rate in strategic locations.…”