Radio over Fibre Access Network Architecture based on new optimized RSOA Devices with large modulation bandwidth and high linearity

With the wide availability of broadband Internet access driving upwards the bandwidth needs of network applications, at the same time as users increasingly shift towards mobile devices and on-the-road connectivity, there is a demand for higher-capacity wireless networks, as present customers want to enjoy the same quality for mobile multimedia services as for fixed networks. In this context, WLAN hot-spots or thirdgeneration (3G) wireless networks are already able to establish wide-area wireless connectivity for services such as voice telephone, video calls, and wireless data, all in a mobile environment. Radio over Fiber (RoF) technology enables different types of services to be combined into a homogenous infrastructure using DAS, which is very attractive for next generation wireless networks [1]. DAS consists of a large number of Remote Antenna Units (RAU) over the coverage area and a Central Unit (CU). In order to obtain a wide service coverage area, many RAUs should be connected to a Central Unit (CU) via an optical fiber network. Efficient architectures have been proposed using WDM techniques, allowing a Reconfigurable Radio over Fiber network (RoFnet) [2]. The high bit rates envisioned for 4th generation wireless networks (4G) can be provided by a hybrid optical-radio infrastructure which is being developed in the FUTON (Fibre optic networks for distributed, extendible heterogeneous radio architectures and service provisioning) project [3]. For uplink RoF systems using WDM, each RAU requires an optical source, such as a directly modulated laser (DML) [4,5].