Optical Local Area Research Articles

Performance Analysis of Wavelet Packet Transform Based De-Noising Receiver for Visible Light Communication by Using Single Source

In this paper, wavelet packet transform (WPT) based de-noising receiver for visible-light communication (VLC) using a white light-emitting diode (LED) is studied for indoor applications such as short distance wireless connectivity, optical wireless local area network, and optical wireless input / output control devise (remote control). Previously, reported discrete wavelet transform based de-noising for indoor optical wireless communication; here we considered wavelet packet transform based de-noising technique. The process starts with the evaluation of the performance of de-noising receiver by calculating the received optical power, signal noise ratio (SNR), path loss and bit error rate (BER). Throughout the simulation results, the SNR performance is inversely proportional to the distance. Analytical study of SNR for VLC system without de-noising for indoor applications has been studied. In this paper de-noising technique is considered for reduction of noise. The DWPT based de-noising receiver, with a single source improves the SNR performance approximately by 2% compared to the one without de-noising receiver.

Transmission scheduling in optical CDMA networks using hybridized overlap and threshold (HOT) scheduling algorithm

The bane of optical network is multiuser interference as a result of codewords overlap from different nodes simultaneously transmitting. Transmission scheduling is a good interference avoidance scheme which helps prevent throughput degradation at high offered load in an optical code division multiple access local area network. Interference avoidance consists of state estimation and transmission scheduling. This work examines different scheduling algorithms and parameter variations. This work investigated the performance of three scheduling algorithms (Pure Selfish Scheduling, Threshold Scheduling and Overlap Section Scheduling) against the ALOHA CDMA and our novel Hybrid--Hybridized Overlap and Threshold Scheduling--HOT algorithms using the modified padded prime codeset. The performance of the scheduling algorithms are measured in terms of its normalized network throughput, packet error rate and the average number of codewords allow into the line against the normalized offered load. The analysis shows that under this condition, the Hybridized Overlap--Threshold scheduling perform best and has throughputs as high as the 52 % with nearly zero packet error rate while the non-scheduled algorithm produce a throughput as low as 10 % and very high error rate at maximum offered load. Overall, the Threshold Scheduling and HOT algorithm are head to head and performed best in terms of normalized network throughput, however the HOT scheduling is best in terms of the packet error rate. Analysis also shows that the throughput is not affected by changes in codeset length and the mean packet size but it is affected by changes in the codeset weight. The study also analyzes the performance of the network under a bimodal packet distribution and with the Prime code codeset family. Optical Orthogonal Codeset and the Prime codeset family are used in the study under the assumption of perfect state estimation; that all nodes have the same view of the network and the transmission lines and the distance between the nodes and the central star coupler is assumed to be zero. A novel hybrid Scheduling Algorithm, the HOT Scheduling which proved better than traditional Scheduling Algorithms is peddled here.

Research on Characteristics of Plastic Materials and Plastic Optical Fiber

Plastic materials have many uses. The plastic optical fiber with a low-cost, light weight, good flexibility, big core diameter, easy coupling, anti-electromagnetic interference and electromagnetic radiation, is used for short range communication. This paper analyzed the characteristics of plastic materials and plastic optical fiber, and proposed a novel application technology for access network. In the access network, the plastic optical fiber is used as a transmission medium, from center router to the server, and the various floors of plastic optical fiber switch to the user using plastic optical fiber connections, constitute a plastic optical fiber local area network, to realize the true meaning fiber to the home.

Analysis of generalized optical orthogonal codes in optical wireless local area networks

In this paper we propose and analyze the application of generalized optical orthogonal codes (GOOC) in the optical wireless local area networks (OWLAN). A system deploying GOOC can support more users and achieve better BER performance. We evaluate the system performance of GOOC noting practical constraints of OWLAN applications. We consider average and peak power limitations of free space infrared sources, arising from eye safety and device non-linearity restriction. We include the impact of various noises including background-light induced noise in system evaluation. Proper system design requires appropriate selection of GOOC code parameters. We analyze the influence of code parameters on key system variables such as BER, required bandwidth and power consumption. Using the results, we provide guidelines for proper selection of key GOOC code parameters for OWLAN applications.

Optical Layer Local Area Network Emulation in a Multifunctional Repeater-Based Optical Access Network

A simple and bandwidth-efficient scheme for providing local area networking among customers in a multifunctional repeater-based optical access network is proposed and experimentally demonstrated. The local traffic from a customer premises is carried on a radio frequency carrier along with the upstream traffic, and this traffic is electrically separated and then combined with downstream traffic at the remote repeater for delivery to the customers.

Upstream access and local area networking in passive optical networks with a single reflective semiconductor optical amplifier

We propose and experimentally demonstrate three novel schemes for upstream access and local area network emulation among customers in a passive optical network using a single reflective semiconductor optical amplifier (RSOA) placed at the customer premises. The first scheme uses the broadband amplified spontaneous emission spectra of the RSOA for the transport of the local area network traffic among the customers, while the second scheme uses the optical carriers delivered to each optical network unit from the central office for the wavelength seeding of the RSOA to facilitate the transport of the local area network traffic. The third scheme describes the self-seeding process of the RSOA with the use of fiber Bragg gratings placed at the optical network unit to facilitate the upstream access and local area network traffic. These schemes for optical layer local area networking among the customers are experimentally demonstrated with more than 2Gbits/s downstream data, 1Gbit/s upstream access traffic, and 1Gbit/s local area network traffic. Moreover, the results of the experiments of all three schemes are compared further and discussed in terms of bandwidth of the local area network traffic, seeding optical power into the reflective semiconductor optical amplifier, and power budget.

A vision chip with column-level amplification of optical data signals for indoor optical wireless local area networks

We present a vision chip architecture with column-level photo-amplification of optical data signals for optical wireless local area networks (LANs) to reduce the pixel area. Based on the architecture, we have fabricated a prototype vision chip in a standard 0.8 μm bipolar complementary metal-oxide-semiconductor (BiCMOS) technology. The device offers position detection of other optical transceivers in the LAN and 4-ch concurrent high-speed optical data acquisition. A data rate of 400 Mbps was demonstrated. The pixel size was 125 μm square, which can be shrunk to smaller than around 60 μm square in 0.35 μm or more advanced BiCMOS or CMOS technologies.

Performance evaluation of a high-speed wavelength division multiplexing/asynchronous transfer mode optical fiber local area network

This work studies the performance of a proposed high-speed optical fiber local area network based on wavelength division multiplex- ing (WDM) and asynchronous transfer mode (ATM). The design opti- mizes the usage of resources by assigning different types of traffic to two overlapping sub-networks. The WDM segment is a circuit-oriented net- work for high-speed traffic. The ATM sub-network handles control, low speed traffic and overflows of the WDM network. Each network is sup- ported by one of two types of channels. The ATM channel employs con- ventional ATM cells for all stations using a 1300-nm wavelength carrier. The WDM channel which is assigned dynamically for very high-speed applications operates at 1500 nm band. The application of an ATM net- work to handle the overflow traffic reduces blocking in the system by approximately 13% for a 32 WDM system. However, depending on the load, it may increase the delay between 5% to 30%. In addition, employ- ing an adequate queuing policy, we may reduce the blocking by 30% while increasing the delay by 5%. We may conclude that the network is more efficient handling the traffic load compared to a simple circuit switched WDM network. © 1999 Society of Photo-Optical Instrumentation Engi- neers. (S0091-3286(99)02511-8)

1 Gbit/s CMOS photoreceiver with integrated detector operating at 850 nm

A fully integrated single-beam optical receiver is realised in a production 0.35 /spl mu/m CMOS process, which operates at 850 nm to 1 Gbit/s. The receiver integrates a photodiode, preamplifier, digital logic, and an off-chip driver. Pre-amplifier dissipation is <1.5 mW at 2.3 V, with an average optical power of -6.3 dBm required for 1 Gbit/s operation. Such a compact optical receiver may be of interest for short distance optical interconnects or local area networks.

ORMA: a high-performance MAC protocol for fiber-optic LANs/MANs

Emerging B-ISDN applications are accelerating the demand for high-speed and high-performance fiber optic local and metropolitan area networks (LANs and MANs). Most of the networks proposed for such an environment are based on either a folded bus or dual unidirectional bus technology, primarily due to the unidirectional nature of the fiber optic medium, their cost effectiveness, and their ability to carry asynchronous transfer mode (ATM) cells. Consequently, the design of the medium access control (MAC) protocols is the most crucial aspect for these networks since the decisions made at this level will determine the capabilities and the hardware cost of the network. The author proposes a novel MAC-layer protocol, called Optical Reservation Multiple Access (ORMA), which is suitable for data traffic on fiber optic folded bus MANs and LANs. Its main feature is an efficient optical reservation technique to allow stations to reserve transmission slots, which is attractive for use in fiber optic networks. Unlike conventional protocols. Where reservation is mostly done using software, ORMA performs its reservation using simple and effective optical circuits. Complete descriptions of the ORMA protocol and the associated nodes are given. Then the performance of ORMA is investigated as a function of the throughput, mean packet delay, and fairness among stations using analytical and simulation results. Our protocol is shown to achieve high throughput and small transmission delays while preserving the fairness of the whole network. Moreover, it compares favorably with related state-of-the-art networks. Thus, the ORMA protocol lends itself well to future-generation high-speed MANs and LANs.

Holograms for optical wireless LANs

The authors investigate the use of holographic transmitters in optical wireless local area networks. Holograms allow more optical power to be launched safely, leading to commensurate improvements in system range and performance. The authors assess the hologram performance, make comparison with theoretical predictions and quantify the improvement provided by holograms.

A load-controlled scheduling scheme for integrated voice-data communication on high-speed LANs/MANs

A new dynamic bandwidth-allocation (or rate-control) strategy that can be employed for integrating multimedia traffic on a class of high-speed fiber optic local and metropolitan area networks (LANs/MANs) is investigated. This new scheme is adapted from the original work by Limb on load-controlled-scheduling-of-traffic (LOCOST) mechanism, which employs channel feedback for proper distributed control operation. Although the mechanism is quite general for integrating diverse traffic types, the specific focus of this paper is on the integration of packet voice with data. The medium access control is simple, and is fully asynchronous and distributed which make it easy to implement. The necessary control functions are performed locally and independently at each data station based on a single parameter called its packet allowance, while each voice station can transmit a voice packet whenever it can. A gated global queue model is formulated to approximately analyze this system, and simulation results are also included to study the protocol's performance.

Performance analysis of slotted aloha protocol for optical fiber local area networks with star topology

In [1, 2] the present authors initiated the development of dynamic models for optical fiber local area networks. This is a major departure from the traditional approach of communication engineers who are used to steady state analysis based on queueing network theory. Here in this paper, theoretical analysis of the proposed model for a passive star coupler based on the Slotted ALOHA/ALOHA protocol for optical fiber local area networks is presented. The input, measured in terms of the number of user requests in each time slot, is modeled as a Poisson random process with time varying mean intensity thereby allowing time varying data traffic which closely models the real physical data flow. In contrast the traditional approach which uses a mean data traffic fails to capture the true dynamic nature of the system. Simulation and theoretical results are compared and they match well

Throughput analysis of a CDMA protocol with channel sensing and overload detection for fibre optic LANs

The throughput of a slotted DS/SSMA scheme for use in optical fibre local area networks is analysed. The scheme employs CDMA embedded in a one-persistent channel sensing protocol with overload detection. Numerical results are presented as a function of offered load with end-to-end transmission delay and channel load threshold as parameters.

Multichannel slot reservation protocol for use on WDM optical fibre LAN

A novel multichannel slot reservation protocol is introduced for application on an optical fibre local area network (LAN) employing wavelength division multiplexing (WDM). The multichannel protocol is shown to demonstrate considerable performance advantages, when compared to the single channel protocol, particularly under asymmetric traffic loading.

New signature code sequence design techniques for CDMA systems

New design techniques are presented for carefully selecting subsets of signature code sequences with small crosscorrelation magnitudes for applications in code inversion keying (CIK) direct-sequence spread-spectrum multiple-access systems. Also, a new class of code sequences, which has been called the class of “structured code” sequences, with small crosscorrelation magnitudes is presented. The performance measure considered is the average probability of data-bit error at the output of a correlator receiver. The results presented are applicable to various applications of code-division multiple-access (CDMA) systems including optical fibre local area networks and indoor radio communications.

FOLANs—An Overview and the Design of Two Optical Ethernets

An overview of the recent trends in research and development activities on fibre-optic local area computer networks is presented. Progress in the areas of devices and components, compatible network topologies, media access techniques, multiplexing and detection techniques for FOLAN applications has been outlined. The paper also describes the design and development of two Ethernet compatible optical fibre local area networks based on active and and passive star topologies.

A review of: “Optical technology and wideband local area networks”

A review of: “Optical technology and wideband local area networks”

Conformance verification of FDDI stations

Abstract The National Bureau of Standards has initiated a program to define test procedures to verify the conformance of stations to the FDDI fiber optic ring local area network standards. This paper summarizes the required conformance tests. A special purpose FDDI station tester is needed and the major characteristics of that tester are outlined.