Performance bounds and cutoff rates of quantum limited OOK withoptical amplification

The bit error probability (BER) and the generalized cutoff rate (GCR) of optically amplified, direct-detection on-off keying (OOK) signaling are addressed utilizing the classical theory of Fredholm integral equations. The approach accounts for the impact of optical bandlimiting and upper bounds on the BER are found via Chernoff techniques, which address the resultant intersymbol interference (ISI) incurred by the linear pulse distortion. Simple rigorous upper bounds on the BER are derived in terms of basic system parameters relaxing the need for solving Fredholm related equations. Random coding is used to obtain the GCR of this channel. The theory is demonstrated for the Lorentzian and finite-duration bandpass optical filters and the optical bandwidth which optimally balances the ISI versus the amplified spontaneous emission noise is found     

Fast synchronization method for CDMA communication systems

The synchronization phase of a code division multiple access communication system might pose a limitation on the performance of the system, since unlike other communication systems it is required to obtain the state (i.e., sequence phase) of a linear feedback shift register (LFSR). Usually the state is obtained by using a brute force exhaustive search over all possibilities, which might be a computationally demanding task. In this paper, we suggest a new method for LFSR sequence phase acquisition. Our method is suitable for practical systems in which an unknown frequency drift may be present. Simulation results for the IS-95/CDMA-2000 standard show a dramatic reduction in the time required to acquire synchronization when using the new algorithm compared to the standard synchronization method