Channel Capacity of OFDM Systems with Timing Jitter

Timing jitter is emerging as an important factor in determining the performance of high-speed Orthogonal Frequency Division Multiplexing (OFDM) systems, particularly in optical OFDM systems where bit rates reach 100 Gbit/s and beyond. In OFDM timing jitter causes intercarrier interference (ICI). For a given subcarrier power, high frequency subcarriers in the sampled signal cause more ICI than lower frequency subcarriers, although the resulting ICI is equally distributed across all subcarriers. In this paper we show that by using this property and allocating more power to lower frequency subcarriers the overall capacity is greater than for a uniform power allocation. For systems where timing jitter is the main impairment, significant capacity increases can be achieved by applying this technique.