Distributed antenna systems based on Radio over Fiber (RoF) has proofed to be the most efficient solution to achieve in-building coverage in 3G systems [1]. Today 3G uses an air interface based on WCDMA. However, Coded Orthogonal Frequency Division

Multiplexing (COFDM), has been selected in IEEE802.11a, WiMax and the long term evolution of 3G (LTE) due to its flexibility and robustness in fading environments [2].

The objectives of the present investigation are therefore to examine the OFDM reliability in the nonlinearities and multipath posed by the RoF link, and how its performance can be improved by using representative linear block codes.

As a measure of reliability, the Bit Error Rate (BER) of the uncoded and coded OFDMRoF system for Uplink (UL) and Downlink (DL) was simulated. The system modeling

considers multipath fading from radio transmission [3] and Amplitude-to-Amplitude (AM/AM) and Amplitude-to-Phase (AM/PM) distortions produced by the Electrical-to-

Optical (E/O) conversion and amplifying stages of the fiber link [4]. Several BCH and Reed-Solomon codes were studied with different code rates [5], complexity and interleaving depth. Their properties are related to system parameters such as Bit Energy

per Noise Density, Input Back-Off (IBO) and modulation order.

The Results show that using 4-QAM modulation with a moderate Input Back-Off (i.e. 4- 10dB), BCH and small Reed-Solomon codes can reduce BER by a factor even greater

than 10 depending on the IBO. However, using 16-QAM modulation BER reduction is poor even if Reed-Solomon is used with large number of bits per symbol.

Future work would consider using a more complex model for the E/O conversion and power amplifier, more sophisticated codes such as Turbo or LDPC, and the use of nonlinear channel

estimation to further enhance system performance.