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Hybrid fibre and optical wireless systems are a potential route to flexible access networks. When combined with code division multiple access (CDMA), there is the possibility of using a power combiner to extend the network to multiple users in a wider coverage area or different rooms and such a scheme is proposed and analyzed here. Moment generating function (MGF) techniques are used to account for...
When we use the free space optical(FSO) communication in the near-ground, it will be great influenced by the atmospheric turbulence. There are many studies on the effects of atmospheric turbulence in FSO. Recently gamma-gamma is a widely accepted model for the optical propagating through the atmosphere in normal and strong turbulence. In order to enhance bit error rate(BER) performance influenced...
This is a study on the effect of reflected light on optical code-division multiple-access (CDMA) system over indoor optical wireless communication (OWC). The indoor propagation channel model which takes multiple reflecting surfaces into account was addressed. Theoretical analysis of the pulse response of direct light and reflected light is given. Bit error rate (BER) of this system is analyzed considering...
In this paper, a theoretical analysis is presented to evaluate the influence of polarization mode dispersion (PMD) on the bit error rate (BER) performance of direct sequence optical code division multiple access system. In this analysis, intensity modulation direct detection technique is employed in single mode fiber operating at 1550nm, and optical orthogonal codes are used as address sequence. Optoelectronic...
Chipshape-dependent bit error rate (BER) performance of direct sequence optical code division multiple access is analytically studied in fiber optic communication with cascaded in-line optical amplifiers in presence of group velocity dispersion. In our analysis, supper-Gaussian, and Hyperbolic-Secant shaped optical orthogonal codes are employed as address sequence. Avalanche photodiode is used in...
In this paper, we propose a new scheme of time-diversity system using Optical Code Division Multiple Access (OCDMA) in free space optical (FSO) communication. Our design is a fully-optical communication system which facilitates synthesizing the time-diversity signals. We found that it can effectively minimize the influence of scintillation caused by atmospheric turbulence. We analyze the bit error...
In this paper a completely new analytical approach to the performance evaluation of turbulence induced fading on free space optical (FSO) CDMA communication system is presented. The current analysis develops an expression of average SINR of FSO CDMA system using switched inversed keyed(SIK) correlator transmitter in presence of turbulence induced fading and multiple access interference(MAI). Link...
Optical CDMA systems suffer from multiple access interferences (MAI) originating from other simultaneous users. As the number of simultaneous user increases, the bit error probability becomes higher. Several interference cancellation techniques have been proposed aiming at lowering MAI as Optical Parallel Interference Cancellation (OPIC), this system is complex, and the hardware is increased as the...
Optical CDMA systems have received much attention in fiber optic networks where the high-speed, the huge band width, the secure and immune communication, asynchronous and simultaneous access for multiple users on the same channel. Those features nominate strongly Optical CDMA for future optical multimedia networks. However, multiple access interference (MAI), which is originated from other simultaneous...
In indoor wireless optical systems the signal is received over different propagation paths. This multipath dispersion phenomenon decreases the system performances. The deconvolution operation is useful for many practical applications. In this paper, the possibility of using deconvolution for the optical code division multiple access (OCDMA) indoor wireless communication system is analyzed. An analysis...
In this paper, M-CSK with extended prime code sequence to enhance a data transmission rate of CSK is considered. Moreover, the bit error rate (BER) performance of M-CSK/CDMA is evaluated by taking into account scintillation, background-noise, avalanche photo-diode (APD) noise, thermal noise, and signal dependence noise through theoretical analysis. It is shown that the data transmission rate of the...
We propose a novel 10G-TDM-OCDMA-PON system using only a pair of en/decoder at a remote node. Full-duplex 4-TDM × 4-OCDMA transmission on a single wavelength over 65 km SMF using 200 Gchip/s optical code without dispersion compensation is successfully demonstrated.
In this paper, the performance of Optical Code Division Multiple Access (OCDMA) system is analyzed at different receivers by using Optical Orthogonal Codes (OOCs). Performance analysis is considered for the chip-level detector and optimum receiver. Our results demonstrate that optimum receiver require less BER i.e. 5.70e-008 than chip-level detector i.e. 2.54e-007 for fixed number of users i.e. for...
We propose 2-dimensional (2-D) free-space optical (FSO) CDMA system for broadband access networks. The performance of the proposed system is analyzed over strong atmospheric turbulence channels. To mitigate the impact of the strong atmospheric turbulence, channel coding schemes, including Reed-Solomon (R-S) and convolutional (CC) codes, are employed. In the analysis, we derive the upper bound of bit-error...
A new class code structure for Spectral Amplitude Coding Optical Code Division Multiple Access (OCDMA) with zero cross-correlation is been proposed in this paper. The proposed code called Modified Zero Cross Correlation Code (MZCC) which evaluation from the existing Zero Cross Correlation Code. MZCC code provides much easier code construction, minimum code length with K number of users given any weight...
A new modulation scheme for 2-D OCDMA systems named multi-code modulation (MCM) is proposed in this paper. The key advantage of MCM over the conventional ones is the ability of mitigating simultaneously both multiple access interference and dispersion. We also propose to combine MCM with heterodyne detection, a powerful technique to relax optical beating interference, to obtain better performance...
This paper investigates the performance of direct detection technique for zero cross correlation code in Optical Code Division Multiple Access (OCDMA) which is a better technique to reduce Multi Access Interference (MAI). MAI is the main reason for performance degradation in optical CDMA especially when large numbers of users are involved. The implementation of direct detection whereby only a pair...
In this paper, the effect of atmospheric turbulence on bit error probability in free-space multi-carrier optical CDMA (MC-OCDMA) scheme with Sequence Inverse Keyed(SIK) optical correlator receiver is analyzed. Here Intensity Modulation scheme is considered for transmission. The turbulence induced fading is described by the newly introduced gamma-gamma pdf[1] as a tractable mathematical model for atmospheric...
We propose a novel multiwavelength optical code-division multiple-access (OCDMA) system using multicode modulation (MCM) signaling. For the multicode demodulator, we employ a maximum-likelihood detection and optical hard limiters. The work in this paper theoretically analyzes the performance of the proposed system over linear dispersive channels, while taking into account the impacts of multiple-access...
In this study, a distributed power control algorithm is proposed for Dynamic Frequency Hopping Optical-CDMA (DFH-OCDMA) system. In general, the DFH-OCDMA can support higher number of simultaneous users compared to other OCDMA techniques. However, the performance of such system degrades significantly as the received power does lower than its minimum threshold. This may obviously occur in a DFH-OCDMA...
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