hi zulkarnain..
Radio over fiber (RoF) refers to a technology whereby light is modulated by a radio signal and transmitted over an optical fiber link to facilitate wireless access, such as 3G and WiFi simultaneous from the same antenna.
Advantages of ROF Technology
Some of the advantages and benefits of the RoF technology are discussed follow:
(i)Low complexity: RoF makes use of the concept of a remote station (RS). This station only consists of an optical-to-electrical (O/E) (and an optional frequency up or down converter), amplifiers, and the antenna. This means that the resource management and signal generation circuitry of the base station can be moved to a centralized location and shared between several remote stations, thus simplifying the architecture
(ii) Low Attenuation Loss: Electrical distribution of high-frequency microwave signals
either in free space or through transmission lines is problematic and costly .
Therefore, distributing high frequency radio signals electrically over long distances
requires expensive regenerating equipment.
(ii) Large Bandwidth: Optical Fibers offer enormous bandwidth. There are three main
transmission windows, which offer low attenuation, namely the 850 nm, 1310 nm,
and 1550 nm wavelengths.
(iii)Immunity to Radio Frequency Interference: Immunity to Electromagnetic Interference
(EMI) is a very attractive property of optical Fiber communications, especially for
microwave transmission. This is so because signals are transmitted in the form of
light through the Fiber. Because of this immunity, fiber cables are preferred even
for short connections at mm-waves.
(iv)Easy Installation and Maintenance: In RoF systems, complex and expensive equipment
is kept at the head end, thereby making the RAUs simpler. For instance, most RoF
techniques eliminate the need for a LO and related equipment at the RAU. In such
cases a photo detector, an RF amplifier, and an antenna make up the RAU.
Modulation and switching equipment is kept in the headend and is shared by several
RAUs. This arrangement leads to smaller and lighter RAUs, effectively reducing
system installation and maintenance costs.