Design and analysis of a dynamic code division multiple access communication system based on tunable optical filter

A dynamic optical code division multiple access (DOCDMA) communication system is proposed for high-band-width communication systems. An implementation of the system is proposed based on a fast tunable optical filter (TOF) in each encoder and decoder. This technique actively modulates the central wavelength of a TOF according to a functional code at the transmitter during the bit period before the transmission of the data. The system is modeled and analyzed taking into account multiple access interference (MAI), thermal noise, and phase-induced intensity noise (PIIN). The performance of this system is compared to that of a spectral amplitude coding system that uses either a Hadamard code or a modified quadratic congruence (MQC) code. The results show that the proposed DOCDMA system reduces the PIIN effect on the performance of the system and improves the bit error rate (BER) performance at a large number of users. Furthermore, it is found that when the effective power is large enough, the MAI becomes the main factor that limits system performance, whereas when the effective power is relatively low, both thermal noise and PIIN become the main limiting factors with thermal noise having the main influence. © 2005 IEEE

Duty-cycle division multiplexing (DCDM): a novel and economical optical multiplexing and electrical demultiplexing technique for high speed fiber optics networks

A new multiplexing and demultiplexing technique based on duty cycle division is proposed, thus the name duty cycle division multiplexing (DCDM). DCDM can be applied in both electrical and optical domains. The new technique allows for more efficient use of time slots as well as the spectrum, taking advantage of both the conventional TDM and FDM. In this paper, three channels operating at the same speed of 10 Gbps are multiplexed in the optical domain and demultiplexed in the electrical domain. The performance comparison is made against 30 Gbps TDM, and the experimental simulation results show that the minimum sensitivity achieved is -26 dBm and -25.5 dBm for the two systems respectively, thus a 0.5 dB improvement

Configuration design and performance analysis of a fast frequency modulation optical CDMA communication system

A fast frequency modulation optical code division multiple access (CDMA) communication system is proposed. In this system, an electrically controlled tunable optical filter (TOF) is used to encode the modulated broadband light source. The code depends on the function set to the controller. Two-dimensional functional code is also proposed based of shifted sine function. The function defines the dynamic coding pattern of the central wavelength of the transmitted narrowband optical signal. The system allows for an easy reconfiguration of the transmitter without the need for sophisticated encoder. At the receiver, a synchronized TOF with the same function is used as a decoder. The performance of this system is shown to be better compared with a fast frequency hopping and a spectral amplitude coding systems

Development of modified double-weight code and its implementation in multi-rate transmissions

This paper presents a new code structure and its ability in supporting multiple transmission rates in point to point Spectral Amplitude Coding- Optical Code Division Multiple Access (SAC-OCDMA) links. The Double-Weight (DW) code family that has a basic fixed weight of 2 was proposed. Modified Double Weight (MDW) Code is a DW code family variation that has variable weight of greater than two. The ability of MDW codes to support simultaneous transmissions at different bit rates is shown through simulated results of the bit error rate (BER) and the eye patterns. Four MDW encoded channels were used at the bit rates of 2.5Gbps and 10Gbps. MDW code shown here significantly performs better than Hadamard and Modified Frequency Hopping (MFH) codes

Hybrid WDM/OCDMA system to support differentiated services in access network

This paper presents a new scheme of WDM/OCDMA system that capable of providing differentiated services in access network. We implement the proposed double-weight (DW) code in this system. The double-weight (DW) code has a fixed weight of 2 and exists for every natural number, n. In spectral-amplitude-coding optical code division multiple access (CDMA) systems, DW code has an ideal cross correlation to eliminate multiuser interference and suppress the noise. We analyze the performance of the system by evaluating the bit error rate (BER) of different services

Performance comparison of complementary and AND subtraction detection techniques for hybrid SCM SAC-OCDMA system

The subtraction detection techniques for a hybrid SCM spectral-amplitude-coding (SAC) OCDMA using double weight (DW) code family are investigated. The experimental simulation results show that the proposed new subtraction detection technique provides a better system performance

Optical domain service differentiation using spectral-amplitude-coding

We have implemented a new service differentiation technique in the optical domain using a spectral-amplitude-coding (SAC) variant of optical code division multiple access (OCDMA). The newly developed code, named KS (Khazani–Syed) is compared mathematically with other codes which use similar techniques. In our proposal, multiple weights are used to support ‘triple-play’ services (audio, video and data) with different quality-of-service (QoS) requirements. The results characterizing the bit-error-rate (BER) with respect to the total number of active users show that KS offers a significantly improved performance over the previous reported techniques by accommodating additional 30 users with shorter code length and smaller code weight at BER of 10−9. In variable weight system, we have shown that KS codes with larger weight always have the best performance when other users of different weights are present in the system

Optimization of EDF pump for efficient brillouin/ erbium fiber ring laser operation

We report here experimental results on the finding of an optimum Erbium pump power in obtaining a Brillouin-generated Stokes signal with the best quality. The quality of the Stokes signal is mainly characterized by its isolation from unwanted modes and noises. We also propose here a new parameter to characterize the signal further that is by using peak power-isolation product. With this particular system, we obtained an optimum Erbium pump power of 48.93 miliwatt producing a peak power 2.91 mW and isolation of 17.6 dB or a peak power-isolation product of 51.23 dB-dBm

Duty-cycle division multiplexing (DCDM): a novel and economical optical multiplexing and electrical demultiplexing technique for high speed fiber optics networks

A new multiplexing and demultiplexing technique based on duty cycle division is proposed, thus the name duty cycle division multiplexing (DCDM). DCDM can be applied in both electrical and optical domains. The new technique allows for more efficient use of time slots as well as the spectrum, taking advantage of both the conventional TDM and FDM. In this paper, three channels operating at the same speed of 10 Gbps are multiplexed in the optical domain and demultiplexed in the electrical domain. The performance comparison is made against 30 Gbps TDM, and the experimental simulation results show that the minimum sensitivity achieved is -26 dBm and -25.5 dBm for the two systems respectively, thus a 0.5 dB improvement