Multirate optical fast frequency hopping CDMA system using power control

Inaty, Elie; Rusch, Leslie A.; Fortier, Paul

doi:10.1109/glocom.2000.891331

Cited by 30 publications

(56 citation statements)

References 11 publications

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“…[1,2]. In recent years, research on OCDMA has attracted considerable attention [3][4][5][6][7][8]. It is expected that OCDMA will be used for such applications as bursty/low traffic [1], video transmissions [2,9], multimedia communications [5,7], and local-area network interconnections with different data rates [7], and so forth.…”

Section: Resultsmentioning

confidence: 99%

Proposed OCDMA encoders and decoders based on silica‐on‐silicon integrated optics

Zhang¹,

Yu-Mei²,

Li³

2003

Micro & Optical Tech Letters

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RESULTS Comparison with 2D ResultsTo test our code, we simulate the same problem as [8], used there to check focus properties of LHM. The problem consists of an infinitely long line source located 0 /2 above an LHM slab with thickness d ϭ 0 / 2, which is surrounded by free space. The LHM slab was located exactly in the middle of our domain, occupying x ϭ [0 120], y ϭ [40 80], and z ϭ [0 30] cells, including the PML region. The line source was located at (60, 100, [0 30]), 20 cells away from the slab and the resonant frequency used for expression (3) was set to be p ϭ 266.6 ϫ 10 11 rad/s, which gives r ϭ r Ӎ Ϫ1. The computational domain for this example is 120 ϫ 120 ϫ 30 grid points, in the x, y, and z directions, respectively. With the PML approach, we were able to reproduce the results in [8] in a much smaller domain. Figure 2 shows the E z -field distribution corresponding to the time t ϭ 1250⌬t. The field is shown down to 40 dB below its maximum. In order to compare our simulation to [8], we did not place a PML layer on the front and back faces, perpendicular to the z axis, in the 2D simulations. It should be noted that the field distribution is the same as in Fig. 7 in [8], even with a different precision due to larger time steps and larger cell sizes in our simulation. The same field distribution is also seen in [12].Another simulation was done in comparison with rad/s. The field is plotted down to 40 dB below its maximum and at a time t ϭ 1250⌬t. As shown in Figure 3, paraxial foci are located at the center of the slab and at the opposite side from the source. 3D Simulation of a /2 DipoleFinally, we apply our code to 3D problems. The problem is to simulate a 0 /2 dipole 0 /2 above an LHM slab with thickness d ϭ 0 / 2. We reproduced similar geometry to the 2D problems, but with a finite line source. The computational domain for all 3D examples has 120 ϫ 120 ϫ 120 grid points. Figure 4 illustrates the problem's geometry, with the xy-plane cutting at the middle of our domain and the yz-and zx-planes cutting along the dipole. All the fields are plotted down to 60 dB below their maxima.For the first example, the dipole was located at ( Figure 6.For all the examples presented here, the colored animation can be found at http://iris-lee3.ece.uiuc.edu/ ϳ jjin/jin_home.html, where the wave propagation and focus property are shown more clearly. CONCLUSIONA complete 3D formulation, adding the PML approach to the previous formulation of the Drude medium model, has been developed in this paper. The simulation results show good accuracy as compared to the previously published results. The phenomenon of backward-wave propagation can now be analyzed in any arbitrary direction inside an LHM and more complex and realistic structures can be simulated with our code.

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Section: Resultsmentioning

confidence: 99%

Proposed OCDMA encoders and decoders based on silica‐on‐silicon integrated optics

Zhang¹,

Yu-Mei²,

Li³

2003

Micro & Optical Tech Letters

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“…The first FFH-CDMA in optical domain is proposed by using an optical frequency synthesizer as the encoder [17], [18]. The tunable FBG arrays (FBGA) are used instead of the frequency synthesizer to reduce further the transmitter cost [19]- [22]. Since the OCDMA is proposed as an access scheme in a local area network (LAN), an OFFH-CDMA system using the FBGA [19] that maintains high performance and potentially low cost is one of the best choices.…”

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confidence: 99%

Improved fiber Bragg grating array OFFH-CDMA system using a novel frequency-overlapping multigroup method

Peng

Lin²,

Chi³

2006

J. Lightwave Technol.

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Abstract-The authors propose a novel frequency-overlapping multigroup scheme for a passive all-optical fast-frequency hopped code-division multiple-access (OFFH-CDMA) system based on fiber Bragg grating array (FBGA). In the conventional scheme, the users are assigned those codes constructed on the nonoverlapping frequency slots, and therefore the bandgaps between the adjacent gratings are wasted. To make a more efficient use of the optical spectrum, the proposed scheme divided the users into several groups, and assigned the codes, which interleaved to each other to the different groups. In addition to the higher utilization of the spectrum, the interleaved nature of the frequency allocations of different groups will make the groups less correlated and, hence, lower the multiple-access interference (MAI). The corresponding codeset and its constraints for this new scheme are also developed and analyzed. The performance of the system in terms of the correlation functions and bit error rate (BER) are given in both the conventional and the proposed schemes. The numerical results show that, with the multigroup scheme, performance is much improved compared to the conventional scheme.Index Terms-Fiber Bragg grating array (FBGA), multipleaccess interference (MAI), optical fast-frequency hopping codedivision multiple access (OFFH-CDMA).

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“…Optical hard limiters are not yet mature technology. Power control has been also considered in optical fast frequency hopping CDMA to provide quality of service compatibility by using variable attenuators [3]. However, the influence of network impairments, such as fiber length differences, were not considered.…”

Section: Introductionmentioning

confidence: 99%

Multi-Class Optical-Cdma Network Using Optical Power Control

Tarhuni¹,

Elmusrati

Korhonen

2006

PIER

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Abstract-In this paper we use optical power control to support multirate transmission over temporal optical CDMA networks. We apply the centralized power control algorithm to set the transmit power of the users' optical sources in order to satisfy a given target QoS. In addition, optical amplifiers are included to enhance the overall system performance while the Amplified Spontaneous Emission (ASE) is considered as the main noise source. The objective function defined as the sum of the transmitted optical power from all nodes is minimized subject to a signal-to-interference (SIR) constraint. Moreover, the network feasibility, defined as the ability to evaluate a power vector that satisfy the target SIR, is discussed in terms of the spectral radius of the network interference matrix. Next, the spectral radius of the network interference matrix is investigated and modeled as a truncated Gaussian distribution. Last, a rate reduction algorithm, categorized in terms of the number of nodes involved in the process of rate reduction, is proposed to increase the network feasibility. As more nodes are added to the rate reduction campaign, the network feasibility is significantly enhanced. For typical network parameters we find by simulating 10 4 random network realizations that a threenode rate reduction results in 99% network feasibility. 280Tarhuni, Elmusrati, and Korhonenn

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Multirate optical fast frequency hopping CDMA system using power control

Cited by 30 publications

References 11 publications

Proposed OCDMA encoders and decoders based on silica‐on‐silicon integrated optics

Proposed OCDMA encoders and decoders based on silica‐on‐silicon integrated optics

Improved fiber Bragg grating array OFFH-CDMA system using a novel frequency-overlapping multigroup method

Multi-Class Optical-Cdma Network Using Optical Power Control

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