The effect of carrier phase jitter on the performance of orthogonal frequency-division multiple-access systems

We investigate the sensitivity to carrier phase jitter of an orthogonal frequency-division multiple access (OFDMA) system. When all OFDMA carriers have the same power level and the jitter spectrum, the degradation caused by the jitter is shown to be equal to the degradation of an OFDM system. Also, traditional FDMA is found to be slightly more robust than OFDMA. I. System description. Orthogonal frequency-division multiple access (OFDMA) is closely related to orthogonal frequency-division multiplexing (OFDM), which is well documented in the literature (e.g. [1-3]). In the case of OFDM, the received signal can be viewed as an OFDM signal, but with each carrier generated by a different user instead of all carriers generated by the same user. In [4], OFDMA has been proposed as access technique for the return channel in a CATV network, i.e. for the communication from the users to the head-end. In an OFDMA scenario, the receiving station (e.g. the head-end in a CATV network) transmits network synchronization signals to the different users, from which these derive the appropriate carrier frequency, symbol rate and time alignment, needed for the orthogonality of the modulated carriers. For instance, each user generates its sinusoidal carrier from the received synchronization signals by means of a phase-locked loop (PLL). However, each of these sinusoidal carriers is affected by phase jitter. The complex envelope r(t) of the received OFDMA signal is given by [4] : r t a E N e p t mN T N e n t m n s n j n N j t N