%0 Journal Article
%T Polarization Division Multiplexing of OFDM Radio-over-Fiber Signals in Passive Optical Networks
%A Maria Morant
%A Joaquin P¨¦rez
%A Roberto Llorente
%J Advances in Optical Technologies
%D 2014
%I Hindawi Publishing Corporation
%R 10.1155/2014/269524
%X This paper describes the state-of-the-art of polarization multiplexing for optical networks transmission. The use of polarization division multiplexing (PDM) permits to multiply the user capacity and increase the spectral efficiency. Combining PDM and orthogonal frequency division multiplexed (OFDM) modulation allows maximizing the optical transmission capacity. The experimental demonstration of transmitting OFDM signals following ECMA-368 ultrawide band (UWB) standard in radio-over-fiber using PDM in passive optical networks is herein reported. The impact of cross-polarization and cochannel crosstalk is evaluated experimentally in a three-user OFDM-UWB subcarrier multiplexed (SCM) configuration per polarization. Each SCM uses up to three OFDM-UWB channels of 200£¿Mbit/s each, achieving an aggregated bitrate of 1.2£¿Gbit/s with 0.76£¿bit/s/Hz spectral efficiency when using PDM transmission. The experimental results for the polarization-multiplexed SCM indicate that a 4£¿dB additional polarization crosstalk interference can be expected compared to a nonpolarization-multiplexed transmission system which translates to 2.4£¿dB EVM penalty in the UWB signals. The successful PDM transmission of SCM multiuser OFDM-UWB over a passive optical network of 25£¿km standard-single mode fiber (SSMF) reach is demonstrated. 1. Introduction The ever-growing transmission capacity demand in optical transmission systems has brought out the necessity of increasing the spectral efficiency employing different transmission techniques. Several approaches have been proposed to date in order to increase the transmission capacity, that is, bitrate by number of users. In particular, the use of efficient modulation formats altogether with advanced multiplexing techniques has been indicated as an interesting approach. New modulation formats have been reported suitable for providing higher bitrate to the final customer. Especially, orthogonal frequency division multiplexing (OFDM) modulation has been adopted by several wireless standards such as 3GPP long-term evolution (LTE) or IEEE 802.16 worldwide interoperability for microwave access (WiMAX), between others. Also, new transmission technologies based on spreading techniques such as ultrawide band (UWB) use OFDM modulation. These signals can achieve high spectral efficiency when using several hundreds of OFDM subcarriers. Another advantage of the OFDM signals is the capability to correct multipath fading thanks to the cyclic prefix of the OFDM signal. For these reasons, OFDM suitability for optical communications has attracted a lot of
%U http://www.hindawi.com/journals/aot/2014/269524/