Paper Info
Title
Modified legendre sequences for optical CDMA-based passive optical networks
Abstract
One spectral-amplitude-coding optical code-division multiple access system is presented for passive optical networks. With the cyclic property of arrayed-waveguide grating (AWG) routers and the partially cyclic property of the proposed modified Legendre sequence, the central office needs two AWG routers and one fiber Bragg grating to generate each user's normal and complementary codewords. Thus complementary encoding is accomplished with a cheap and simple configuration, allowing for low-power asynchronous transmission. HE early incoherent optical code-division multiple ac- cess (OCDMA) systems were based on time spreading technique and multiple access interference (MAI) was always the main limiting factor for the system performance. Spectral- amplitude-coding (SAC) OCDMA systems (1) were proposed to use codes with fixed in-phase cross correlations for MAI elimination, and several codes with ideal in-phase cross corre- lations were proposed to suppress the phase-induced intensity noise in the photodiodes (PDs) of the decoders (2,3). However, these codes required higher source power to obtain a better performance. For application in passive optical networks, this poses a serious problem on the power consumption of the central office, especially when the number of encoders in need is large. Hadamard codes were used in the SAC OCDMA systems. Due to their strong ability in complementary coding, they can achieve a better performance than other codes at low signal-to-noise ratio. However, a large number of individual encoders were still needed in the central office and the cost was increased. In this paper new code families named modified Legendre sequences with complementary coding ability are proposed for SAC OCDMA systems. Due to their partially cyclic code patterns, the corresponding encoding devices are compact and more practical for realization. Thus this is a promising solution for OCDMA-based passive optical net- works. The performance of the proposed system is evaluated with respect to phase-induced intensity noise and thermal noise to demonstrate that the proposed system can operate normally in case of low signal power.
Year
DOI
Venue
2006
10.1109/LCOMM.2006.1633334
IEEE Communications Letters
Keywords
Field
DocType
Passive optical networks,Optical fiber networks,Multiple access interference,Central office,Optical noise,Phase noise,Multiaccess communication,Arrayed waveguide gratings,Encoding,Chaos
Asynchronous communication,Fiber Bragg grating,Telecommunications,Grating,Computer science,Optical communication,Passive optical network,Legendre polynomials,Real-time computing,Electronic engineering,Code division multiple access,Encoding (memory)
Journal
Volume
Issue
ISSN
10
5
1089-7798
Citations 
PageRank 
References 
6
2.14
0
Authors
1
Name
Order
Citations
PageRank
Chao-Chin Yang16414.24