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Development of a new code family based on SAC-OCDMA system with large cardinality for OCDMA network

One spectral-amplitude-coding (SAC) scheme combined with wavelength-division-multiplexing (WDM) is proposed for optical code-division multiple-access systems. The supported code length is more flexible than the previous SAC codes and the corresponding encoder-decoder requires less fiber gratings, thus, the system becomes cheap and simple. As compared to the conventional SAC systems, this WDM/SAC system not only reserves the interference-cancellation property, but also has better performance against the effect of the phase-induced intensity noise arising in the photodetecting process. Thus, a larger number of active users can be supported under a given bit-error rate.

Hybrid wavelength-division-multiplexing/spectral-amplitude-coding optical CDMA system

Performance improvement of hybrid subcarrier multiplexing optical spectrum code division multiplexing system using spectral direct decoding detection technique

The major drawback of incoherent spectral-amplitude coding optical code-division multiple-access (SAC-OCDMA) systems is their inherent intensity noise originating due to the incoherency of the broadband light sources. In this paper, we propose a developed detection technique named the modified-AND subtraction detection for incoherent SAC-OCDMA systems. This detection technique is based upon decreasing the received signal strength during the decoding process by dividing the spectrum of the utilized code sequence. The proposed technique is capable of mitigating the intensity noise effect, as well as suppressing the multiple-access interference impact. Based on modified quadratic congruence (MQC) code, the analytical results reveal that the modified-AND detection offer best bit-error rate (BER) performance and enables MQC code to support higher transmission rate up to 1.25 Gb/s compared to conventional AND detection. Furthermore, we ascertained that the proposed technique enhances the system performance usin...

Improved BER based on intensity noise alleviation using developed detection technique for incoherent SAC-OCDMA systems

In this paper, a new code family named partitioned partial prime (PPP) code is proposed for high-rate spectral amplitude code (SAC) optical code-division multiple-access (OCDMA) passive optical networks (PONs) applications. They are derived from the well-known prime codes (PCs) and a manner of partitioning technique. To minimize in-phase cross-correlation (IPCC), we employ the partial and padding schemes. In addition, the influences of both phase-induced intensity noise (PIIN) and shot noise are further mitigated by the partition and two-code keying (TCK) schemes. The PPP code family has the property of good code balance, flexible code length, and excellent orthogonality. The numerical results show that the proposed system using PPP codes can substantially accommodate a lot of maximum and simultaneous users with high-rate transmission and low bit error rate (BER).

A new code family suitable for high-rate SAC OCDMA PONs applications

A compact optical code-division multiple-access (OCDMA) network coder-decoder (codec) of a spectral-amplitude-coding (SAC) scheme is presented. The scheme utilizes M-sequence-coded OCDMA codecs structured on arrayed-waveguide-grating (AWG) routers. By using the cyclic properties of AWG routers and M-sequence codes, the codecs pair can encode-decode multiple code words simultaneously, thus, each user can share the same hardware for coding process. The configuration not only preserves the ability of multiple-access interference cancellation in SAC-OCDMA system, but also results in a cheap system with reduced system complexity.

Shin-Pin Tseng

Papers

Optical CDMA network codecs structured with M-sequence codes over waveguide-grating routers

Complementary Walsh¿Hadamard coded optical CDMA coder/decoders structured over arrayed-waveguide grating routers