For the further provision of broadband services over wireless media, current trends in cellular networks are to reduce cell size to accommodate more users. It demands a large number of base stations (BSs) to cover the service area. This requirement has led to the development of system architecture where functions such as data routing, handover and resource allocation are carried out at a central station (CS), rather than at the BSs. An attractive solution for linking a CS with several BSs in such a radio network is via an optical fiber network, since fiber has low loss, broad bandwidth and is immune to Electro-Magnetic Interference (EMI). The transmission of radio signals over fiber has been proposed as a method of minimizing costs: the remote antenna in BS or radio access point needs to perform only simple functions; it is small in size, simple in design and low in cost. The resources and functions provided by the CS can be shared among many BSs. Today the dominant market for RoF technology is the distribution of radio signals over fiber to extend the range and capacity of radio system indoors, and called active Distributed Antenna System (DAS). The idea is to split the transmitted signal among several sites, separated in space so as to provide coverage over the same area but with reduced total power (EIRP) and improved reliability and radio coverage. A single antenna radiating at high power is replaced by a group of low-power antennas to cover the same area. In the project CapilR, the Radio over fiber system is designed for WLAN 802.11g. It means that we must meet the specified Signal Noise Report (SNR) requirements at uplink. However, the optical equipments cause some limitations like noise, nonlinearities, distortions and dispersion. Therefore, signal impairments such as noise and distortion, which are important in analogue communication systems, tend to limit the Noise Figure (NF) and 3rd Order Intercept Point (TOI or IP3), then Dynamic Range (DR) of the RoF links. Due to the low IP3 and high NF of optical link (laser diode + optic-fiber +photodiode + Trans- impedance Amplifier (TIA)), DR of the RF signals must be reduced to: - Meet the SNR requirements (min. level of output signal power > noise + SNR + margin) - Avoid the nonlinearities (max. level of output signal power < OIP3 – 20 dB) In order to solve this problem, we use the Automatic Gain Control (AGC) loop technology, typically composed by a Variable Gain Amplifier (VGA), a detector and an amplifier. The output power of loop can be dynamically adjusted and stay at the same level for different input signal powers. Optical fiber in RoF system is transparent to radio interface (e.g. modulation, frequency, bit rate, crest factor and so on). Thus, in principle, multiple services standards on a single fiber can be supported at the same time. However, The AGC loop doesn’t support multiple standards system. In this case, the power difference between noise and IP3 must be maximized.