We measure the stimulated Raman scattering (SRS)-induced tilt in spectral-amplitude-coding optical code-division multiple-access (SAC–OCDMA) systems as a function of system main parameters (transmission distance, power per chip, and number of users) via computer simulations. The results show that SRS-induced tilt significantly increases as transmission distance, power per chip, or number of users grows.
KEYWORDS: Fiber to the x, Switching, Interfaces, Switches, Optical switching, Signal attenuation, Optical networks, Reliability, Network architectures, Signal detection
Massive deployment of FTTH fiber network causes protection to FTTH network a crucial need. Most FTTH
access networks are protected from failure by having redundant network equipments. These are not economical
approaches, as the redundant systems are not efficiently utilized by the network. In this paper, the authors propose a
protection method where redundant equipments are not required and protection is provided to end user through sharing
of bandwidth during the failure time. A protection control unit and an optical switch is employed connecting four Optical
Line Terminations (OLTs) with each one serving only 32 Optical Network Units (ONUs). Protection control unit collects
information of ONUs served by each OLT and when an OLT fails, it will instruct an active OLT to serve its original
ONUs together with the ONUs served by the failed OLT. It also provides information of ONUs served and inform the
involved 64 ONUs of their new timeslot allocation. Then, the signal is switched from failed OLT's line to the instructed
active OLT. The results show that through sharing of bandwidth, adequate protection is provided without redundant
equipment for more than one OLT failure.
An enhanced code structure for spectral amplitude coding in optical code division multiple access systems based on double weight (DW) code families is proposed. Enhanced double weight (EDW) codes possess ideal cross-correlation properties such as maximum cross correlation of 1 and a weight that can be any odd number greater than 1. It has been observed through theoretical analysis and experimental simulation that EDW codes perform significantly better than Hadamard and modified frequency-hopping (MFH) codes. In this study, point-to-point transmission with three EDW-encoded channels was tested at the bit rate of 10 Gbit/s per channel.
An optical dynamic spectral encoding 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 code, named functional code, is also proposed based on a shifted sine function. The function defines the dynamic coding pattern of the central wavelength of the transmitted narrowband optical signal. Thus, the system will allow for an easy reconfiguration of the transmitter without the need for a sophisticated encoder. At the receiver, a synchronized TOF with the same function is used as a decoder. The system is modeled and analyzed taking into account the multiple access interference, phase-induced intensity noise (PIIN), and thermal noise. The performance of this system is shown to be better compared with a fast frequency hopping (FFH) system and a spectral amplitude coding (SAC) system that uses either a Hadamard code, a modified quadratic congruence (MQC) code, or a modified frequency hopping (MFH) code.
A new code structure for spectral amplitude coding optical code division multiple access system based on Double Weight (DW) code families is proposed. The DW has a fixed weight of two. Enhancement Double Weight (EDW) possesses ideal cross-correlation properties and weight can be any odd number which is grater than one. It has been observed that theoretical analysis for EDW code is much better performance compared to Hadamard, and Modified Frequency Hopping (MFH) codes.
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