DIRECT-SEQUENCE CODE-DIVISION MULTIPLE-ACCESS WITH OPTICAL MULTICARRIERS AND PARALLEL FEC CODES

We propose Direct Sequence CDMA with Optical Multicarriers and Paralle l Forward Error Correcting (PFEC) coding technique. Proposed DE-CDMA w ith OPTICAL MULTICARRIERS, is new in lightwave systems and its allianc e with PARALLEL FEC codes, makes it further unique. Optical multicarri ers approach is effective to increase throughput by combating dispersi on and ISI (Intersymbol Interference), whereas FEC is effective to inc rease reliability by diluting interactions among optical multicarriers . Till now, both the techniques in lightwave systems have been discour aged. The former because of the wandering effect of optical multicarri ers owing to unstability of laser diodes and later because it involves insertion of parity bits that changes data rate and results in insert ion distortion that is not desirable in optical systems. To avoid chan ge due to spreading code we also propose to take spreading code equal to serial to parallel converted streams. It bounds initial data (befor e S/P conversion) to data per carrier (after S/P conversion and spread ing) on one hand and relaxes the requirement of high speed electronics on the other. The alliance of optical multicarriers with suitably app lied FEC that we refer as Parallel FEC (PFEC) is effective as the bene ficial aspects of each mitigate the shortcomings of the other and make the system practicable. Theoretical treatment confirms that the propo sed approach is fundamentally sound and holds the potential for promis ing network performance.