Carrying microwave signals in a GIPOF-based wireless LAN

By applying fast sweeping of the laser wavelength at the headend station and a multipassband optical filter at the antenna stations, multi-GHz radio signals can be distributed cost-effectively using GIPOF links in a wireless LAN. Data signal transparency and simple antenna stations are obtained. First simulations have shown the feasibility of the system concept. Introduction Wireless LANs are making fast progress in penetrating the in-house communication market, in particular in business and academic environments. The growth in the number of users as well as in the bandwidth required per user generates a clear need for increasing the capacity to be provided wirelessly. High bitrate wireless connections to the users require high carrier frequencies and small radio cells. Current wireless LAN products operating in the ISM band (2.4 GHz) offer capacities of 11 Mbit/s per carrier frequency; HIPERLAN/2 systems transport up to 54 Mbit/s per carrier in the 5.2 GHz band, and systems offering more than 100 Mbit/s will require carrier frequencies beyond 10 GHz (60 GHz systems are being investigated). With increasing data speeds and carrier frequencies, ever-smaller radio cells are deployed. Each of these cells needs an antenna, and the high bitrate data signals most advantageously are brought to the antennas via optical fibre. To facilitate an adequate coverage, a typical residential home or small business office needs to be partitioned in many cells, and an in-house network wired with optical fibre is needed. At the same time, the wiring needs to be easy to install, and easy to extend. Polymeric optical fibre meets these requirements because of its large core diameter and high numerical aperture, and because it can be easily bent, spliced and coupled to other devices. However, for transporting high bitrate signals, the limited bandwidth-timeslength product of this fibre type is a point of concern. On the other hand, in-house distances are relatively short. Significant progress has been made in transporting highspeed digital signals through GIPOF-based networks [1], [2]. For transporting analog wireless radio signals through GIPOF networks, however, to our knowledge no studies have been reported so far. This paper describes a novel approach to tackle this issue.