INTERNATIONAL JOURNAL OF ELECTRONICS & COMMUNICATION TECHNOLOGY (IJECT)
Vol 10 Issue 1 (Jan – March 2019)
International Journal of Electronics & Communication Technology Vol 10 Issue 1 (Jan – March 2019)
|Optical Signal Quality Optimization by Adopting Spectral Inversion at the Receiver of High-Speed Optical Communication System
In this paper a new approach of improving received optical signal quality utilizing Spectral Inversion (SI) technique outside the transmission link is investigated in long-haul intensity and phase modulated transmission systems using channel data rate up to 100 Gb/s. The approach is implemented using a module called Optical Signal Post-Optimization (OSPO) composed with an OPC-unit followed by Highly Nonlinear Fiber (HNLF) with high nonlinear coefficients. 100 Gb/s single channel was simulated with differential quadrature phase shift keying (DQPSK) where an increased in Q factor of the system with OSPO of 1.5 dB is observed at transmission lengths of 2000, 2500 and 3000 km. For 100 Gb/s 5 channels WDM the system Q factor improvement was about 1 dB at transmission lengths of 2000 and 2500 km. To ascertain the effectiveness of the method an experimental investigation was carried out using DPSK systems over 300 km transmission distance. Various results obtained showed an improvement of system Q factor of the order of 1 dB.
|Effect of Spreading Sequence, Modulation Schemes, Number of Users and Detection Technique on the Performance of MC-CDMA System
Shivani Sharma, Pratibha Nagaich
In this paper the BER performance of the Multi Carrier Code Division Multiple Access (MC-CDMA) is evaluated over Rayleigh fading channel. MC-CDMA is a promising technique to full fill the high speed data transmission requirements of today’s diversified wireless networks. MC-CDMA system incorporates the advantage of two schemes which are Orthogonal Frequency Division Multiplex (OFDM) and the code division multiple access (CDMA). In this paper we present MATLAB simulation results to show the effect of various parameters such as: Spreading sequence, Modulation schemes, Number of users and Detection technique on the performance of the MC-CDMA system. Bit Error Rate (BER) and Signal to Noise Ratio (SNR) are chosen as the performance metrics for comparison of the simulation results.