This project progress report summarizes work on optimizing optical CDMA technology for fiber optic communication. The report discusses principles of OCDMA coding, major challenges like bit error rate and multi-access interference, and methods to overcome challenges such as using spectral amplitude coding and spectral phase coding. It also summarizes simulations conducted to measure bit error rate at different distances using an OCDMA system based on fiber Bragg grating encoders and decoders. Finally, the report outlines applications of OCDMA including use in passive optical networks and providing virtual private networks over metro optical networks.
This document provides an overview of Dense Wavelength Division Multiplexing (DWDM) technology. It discusses DWDM components like multiplexers, demultiplexers, transponders, and amplifiers. It also covers DWDM networks topologies like point-to-point, ring, and mesh. Finally, it discusses transmission quality parameters like optical signal-to-noise ratio that are important for DWDM systems. The presentation contains 29 slides and is intended to briefly explain DWDM for effective fiber-optic transmission.
This document discusses optical time division multiple access (OTDMA) and optical code division multiple access (OCDMA). OTDMA allows multiple optical signals to be combined into a single data stream by performing time division multiplexing. OCDMA transmits data using light pulses encoded with unique codes, allowing all users to transmit over the full bandwidth simultaneously. The document outlines the implementation of OTDMA and OCDMA, and compares their advantages and disadvantages. OTDMA provides higher bit rates but subjects signals to multipath distortion, while OCDMA does not require time or frequency management but has more expensive encoding/decoding hardware.
Dense wavelength division multiplexing (DWDM) is a fiber optic transmission technique that employs light wavelengths to transmit data parallel-by-bit or serial-by-character. It allows for increased fiber capacity and scalability. DWDM evolved from earlier WDM techniques and can transmit 64 or more channels through a single fiber using spacing between 25-50 GHz. Ongoing research focuses on reducing dispersion and developing tunable lasers. DWDM provides a robust, simple, and cost-effective solution for growing bandwidth demands.
This document provides an overview of optical DWDM fundamentals, including:
- Key terminology used in optical networks such as decibels, wavelength, frequency, and fiber impairments.
- Characteristics of optical fiber including different fiber types, fiber dimensions, and how light propagates through total internal reflection.
- Factors that reduce optical power over distance, specifically attenuation from absorption and scattering in the fiber material.
This document provides an overview of Dense Wavelength Division Multiplexing (DWDM) technology. It discusses key topics such as optical transmission, DWDM components like multiplexers/demultiplexers and amplifiers, DWDM networks and topologies, and transmission quality parameters. The presentation contains 32 slides and is intended to briefly explain DWDM as a means of achieving effective fiber-optic transmission and increasing bandwidth.
The document presents information on free space optics communication. It discusses how FSO works by transmitting data as invisible light pulses between a transmitter and receiver. FSO provides benefits like high bandwidth, bit rate, power efficiency, and data security at low cost. However, it faces challenges from environmental factors like absorption, scattering, fog, scintillation, solar interference, dispersion, and building motion that can attenuate the signal. The document lists manufacturers in the FSO field like LightPointe, AirFiber, and Terabeam and the funding they have received.
This document discusses next-generation reconfigurable optical add-drop multiplexers (NG ROADMs). It outlines the functionality requirements of NG ROADMs, including being colorless, directionless, contentionless, and gridless. It describes the technology building blocks that enable these features, such as wavelength selective switches (WSS). The document also discusses the benefits of NG ROADMs, such as increased flexibility, automatic restoration, and support for higher data rates. It concludes that NG ROADM technology prepares networks to meet current and future traffic needs.
This presentation provides an overview of free space optical communication (FSO). It discusses the history of FSO beginning with Alexander Graham Bell's photo-phone invention in 1880. FSO uses visible or infrared light to transmit data through free space. It has several advantages over traditional wired networks such as lower costs, high speeds, and unlimited spectrum. However, FSO also has disadvantages like vulnerability to weather conditions and need for line-of-sight access. The presentation describes the basic working of FSO systems and components. It outlines applications in areas like metro networks, enterprise connectivity, and space communications. In conclusion, FSO provides a cost-effective option for short-range, high-speed data transmission where physical connections are impractical
This document provides an overview of Dense Wavelength Division Multiplexing (DWDM) technology. It discusses DWDM components like multiplexers, demultiplexers, transponders, and amplifiers. It also covers DWDM networks topologies like point-to-point, ring, and mesh. Finally, it discusses transmission quality parameters like optical signal-to-noise ratio that are important for DWDM systems. The presentation contains 29 slides and is intended to briefly explain DWDM for effective fiber-optic transmission.
This document discusses optical time division multiple access (OTDMA) and optical code division multiple access (OCDMA). OTDMA allows multiple optical signals to be combined into a single data stream by performing time division multiplexing. OCDMA transmits data using light pulses encoded with unique codes, allowing all users to transmit over the full bandwidth simultaneously. The document outlines the implementation of OTDMA and OCDMA, and compares their advantages and disadvantages. OTDMA provides higher bit rates but subjects signals to multipath distortion, while OCDMA does not require time or frequency management but has more expensive encoding/decoding hardware.
Dense wavelength division multiplexing (DWDM) is a fiber optic transmission technique that employs light wavelengths to transmit data parallel-by-bit or serial-by-character. It allows for increased fiber capacity and scalability. DWDM evolved from earlier WDM techniques and can transmit 64 or more channels through a single fiber using spacing between 25-50 GHz. Ongoing research focuses on reducing dispersion and developing tunable lasers. DWDM provides a robust, simple, and cost-effective solution for growing bandwidth demands.
This document provides an overview of optical DWDM fundamentals, including:
- Key terminology used in optical networks such as decibels, wavelength, frequency, and fiber impairments.
- Characteristics of optical fiber including different fiber types, fiber dimensions, and how light propagates through total internal reflection.
- Factors that reduce optical power over distance, specifically attenuation from absorption and scattering in the fiber material.
This document provides an overview of Dense Wavelength Division Multiplexing (DWDM) technology. It discusses key topics such as optical transmission, DWDM components like multiplexers/demultiplexers and amplifiers, DWDM networks and topologies, and transmission quality parameters. The presentation contains 32 slides and is intended to briefly explain DWDM as a means of achieving effective fiber-optic transmission and increasing bandwidth.
The document presents information on free space optics communication. It discusses how FSO works by transmitting data as invisible light pulses between a transmitter and receiver. FSO provides benefits like high bandwidth, bit rate, power efficiency, and data security at low cost. However, it faces challenges from environmental factors like absorption, scattering, fog, scintillation, solar interference, dispersion, and building motion that can attenuate the signal. The document lists manufacturers in the FSO field like LightPointe, AirFiber, and Terabeam and the funding they have received.
This document discusses next-generation reconfigurable optical add-drop multiplexers (NG ROADMs). It outlines the functionality requirements of NG ROADMs, including being colorless, directionless, contentionless, and gridless. It describes the technology building blocks that enable these features, such as wavelength selective switches (WSS). The document also discusses the benefits of NG ROADMs, such as increased flexibility, automatic restoration, and support for higher data rates. It concludes that NG ROADM technology prepares networks to meet current and future traffic needs.
This presentation provides an overview of free space optical communication (FSO). It discusses the history of FSO beginning with Alexander Graham Bell's photo-phone invention in 1880. FSO uses visible or infrared light to transmit data through free space. It has several advantages over traditional wired networks such as lower costs, high speeds, and unlimited spectrum. However, FSO also has disadvantages like vulnerability to weather conditions and need for line-of-sight access. The presentation describes the basic working of FSO systems and components. It outlines applications in areas like metro networks, enterprise connectivity, and space communications. In conclusion, FSO provides a cost-effective option for short-range, high-speed data transmission where physical connections are impractical
The document compares and contrasts ASTN/ASON and GMPLS frameworks for automating provisioning of transport networks. It discusses their motivations, architectures, resource models, control planes, policy-based management, and provides two use cases to illustrate policy-based management in GMPLS networks.
Free space optics uses light propagating through free space to transmit data between two points. It provides line-of-sight connectivity at speeds up to 2.5 Gbps as an alternative to fiber cables when they are impractical. An FSO system consists of an optical transceiver with a laser transmitter and receiver to provide bidirectional communication over distances of several kilometers depending on the power of the transmitter. While offering rapid deployment over buildings on a campus, FSO is limited by fog, physical obstructions, and atmospheric effects like scattering that can reduce the intensity of the light beam.
Optical Wireless Communications - from the space to the chip.Joaquin Perez
A short introduction to the applications of the OWC in to the short-range to the deep-space applications. Form visible light communications to wearables, OWC is a way to reuse our natural space of communications the free space and the light.
Seminar presented at Universitat Politecnica de Valencia, Spain during the OQCG regular seminars' series, March 2014. by Dr Joaquin Perez
Optical wireless communication, also known as free space optics (FSO), uses lasers or LEDs to transmit data through the air. FSO can provide high-speed broadband connections for the "last mile" between buildings. However, FSO systems face challenges from atmospheric conditions like fog, rain, and smoke that can attenuate the optical signal. Proper choice of wavelength, transmitter power, receiver design, and link length can help overcome these challenges to provide reliable, high-bandwidth communication over short to medium distances.
This document summarizes a technical seminar on free space optics (FSO) presented by Kartik K Benageri at Jain Institute of Technology in Davangere, Karnataka, India. The seminar covered the introduction, key features, working principles, advantages, limitations, and conclusions of FSO technology. FSO uses lasers and photo detectors to transmit data, voice, or video at speeds up to 2.5 Gbps in a line-of-sight fashion without the need for fiber. While offering benefits like flexibility, low cost, and security compared to fiber or microwave, FSO performance can be impacted by environmental factors like fog, rain, scattering, and building sway. The seminar provided information
Free-space optical (FSO) communication uses visible light or infrared light beams to transmit data through the air. It works similarly to fiber optics but transmits the light beam through the air instead of glass fibers. FSO systems can transmit data at rates similar to fiber optics over distances up to a few kilometers. They provide a wireless complement to radio-based communication systems. The main requirements are having an unobstructed line-of-sight between the transmitter and receiver and clear atmospheric conditions.
The document summarizes free space optical communication (FSO). It discusses the operation of FSO links, their advantages over fiber and microwave links, and applications. The key points are:
1. An FSO link consists of a transmitter, receiver, and tracking system to direct light beams between nodes. It allows license-free, high-speed connections but is susceptible to weather.
2. Applications include point-to-point links between buildings and potential mesh networks or use on high altitude platforms. Mesh networks provide better coverage but at a higher cost than point-to-point links.
3. Compared to fiber and microwave links, FSO systems have lower costs and power needs but higher data rates and
Free space optical communication (FSO) uses lasers and photo detectors to transmit data through the air without fiber cables. It was initially developed by NASA and the military. FSO can transmit data, voice, or video at speeds up to 1.25 Gbps using invisible beams of light in a line-of-sight system. Signal propagation is impacted by weather like fog and rain, which can cause scattering and absorption leading to power losses and interruptions. While installation has low costs compared to fiber, FSO performance depends on clear line-of-sight conditions.
1. Optical fibers transmit data using pulses of light and are able to carry much higher bandwidths than metal wires.
2. Fibers use total internal reflection to guide light along their length with less loss than wires and are immune to electromagnetic interference.
3. Fibers have various applications including long distance communications, local networks, imaging bundles, and sensors.
Free-space optical communication is an optical communication technology that uses light propagating in free space to wirelessly transmit data for telecommunications or computer networking. It is a technology that can be installed license-free worldwide and can be installed in less than a day. A technology that offers a fast, high ROI. There is no Frequency License Required in it.
This presentation discusses freespace optical communication (FSO), which transmits modulated beams of light through the atmosphere for broadband communications. It provides a brief history of FSO, describes how FSO works by converting network traffic to light pulses, and lists its advantages like low cost, high security, and immunity to electromagnetic interference. The presentation also outlines FSO's applications like metro networks and last mile access, and discusses its disadvantages such as reliance on line of sight and susceptibility to atmospheric conditions.
Free Space Optics (FSO) communications, also called Free Space Photonics (FSP) or Optical Wireless, refers to the transmission of modulated visible or infrared (IR) beams through the atmosphere to obtain optical communications. Like fiber, Free Space Optics (FSO) uses lasers to transmit data, but instead of enclosing the data stream in a glass fiber, it is transmitted through the air. Free Space Optics (FSO) works on the same basic principle as Infrared television remote controls, wireless keyboards
Li-Fi is a new wireless technology which provides the connectivity within localized network environment. The main principle of this technology is we can transmit the data using light illumination by using light emitting diodes where radio frequency is media in Wi-Fi and LED bulb light intensity is faster than human eye can follow. One germen phycist-Prof Harald Haas an expert in optical wireless communications at the University of Edinburgh, he demonstrated how an LED bulb equipped with signal processing technology could stream a high-definition video to a computer. By using this technology a 1 watt LED light bulb would be enough to provide net connectivity to four computers. This technology termed as "light fidelity". This technology allows us to transfer data more securely with higher data rates. This technology is still under research and further exploitation could lead to wide applications.
This document discusses key characteristics of optical fibers that affect their performance as a transmission medium. It describes how wavelength, frequency, reflection, refraction, polarization, and attenuation properties influence fiber optic communication. Specific bands used in optical fibers, including O, C, E, S and L bands, are defined. The document also examines intrinsic and extrinsic factors contributing to fiber attenuation, as well as dispersion which limits bandwidth by spreading out light pulses over time as they travel through the fiber.
1) What is Fiber Optics?
2) Structure of Fiber Optics.
3) Modes of Fiber Optics.
4) How It Is made.
5) Communication System.
6) Evolution of Fiber Optics.
7) Advantages/ Disadvantages.
8) Applications of Fiber Optics.
9) Conclusion.
Optical networking uses fiber optic cables to transmit data via light pulses. Early networks like FDDI used two fiber rings operating at 100 Mbps. SONET/SDH later became the standard, using synchronous transmission and hierarchical multiplexing of lower speed streams. SONET/SDH supports various network configurations including point-to-point links, linear and ring topologies using add/drop multiplexers. Rings provide high availability through fast automatic protection switching.
This document discusses optical time division multiplexing (OTDM) systems. It outlines some of the key challenges with OTDM, including nonlinearity in fibers causing signal-to-noise ratio degradation as the number of channels increases. It also discusses the components needed for an OTDM system, including ultra-short optical pulse generation and modulation at the transmitter, and optical clock extraction and demultiplexing at the receiver. Several approaches for OTDM demultiplexing are described, such as using cascaded modulators, nonlinear optical loop mirrors, or four wave mixing in a nonlinear medium.
LTE carrier aggregation technology development and deployment worldwidecriterion123
Carrier aggregation (CA) allows the combination of multiple component carriers to increase bandwidth and throughput. CA can be intra-band, combining contiguous or non-contiguous carriers within a band, or inter-band, combining carriers across frequency bands. Inter-band CA provides more flexibility to utilize fragmented spectrum. The LTE standard defines a maximum of five component carriers for CA. CA improves downlink throughput by increasing bandwidth but may not always increase uplink throughput due to limitations of UE maximum power. Close frequency band CA and FDD-TDD CA require additional RF components to separate signal paths and prevent interference between bands.
This document discusses dispersion compensation techniques for optical code division multiple access (OCDMA) systems using dispersion compensation fiber (DCF) and fiber gratings. It compares the performance of an 8-user OCDMA system using DCF versus fiber gratings. The results show that DCF more effectively compensates for dispersion, as evidenced by a lower bit error rate and higher Q factor, making it a better dispersion compensation method for OCDMA systems compared to fiber gratings.
This document summarizes a seminar presentation on Optical Code Division Multiple Access (OCDMA). OCDMA allows multiple users to transmit simultaneously over the same bandwidth using unique optical codes. It provides advantages over TDMA and FDMA such as supporting more users and asynchronous transmission without packet collisions. The presentation describes OCDMA network implementation using optical orthogonal codes assigned to transmitters and receivers for communication. It also discusses enhanced security provided by OCDMA through increasing the signal-to-noise ratio required for eavesdropping.
The document compares and contrasts ASTN/ASON and GMPLS frameworks for automating provisioning of transport networks. It discusses their motivations, architectures, resource models, control planes, policy-based management, and provides two use cases to illustrate policy-based management in GMPLS networks.
Free space optics uses light propagating through free space to transmit data between two points. It provides line-of-sight connectivity at speeds up to 2.5 Gbps as an alternative to fiber cables when they are impractical. An FSO system consists of an optical transceiver with a laser transmitter and receiver to provide bidirectional communication over distances of several kilometers depending on the power of the transmitter. While offering rapid deployment over buildings on a campus, FSO is limited by fog, physical obstructions, and atmospheric effects like scattering that can reduce the intensity of the light beam.
Optical Wireless Communications - from the space to the chip.Joaquin Perez
A short introduction to the applications of the OWC in to the short-range to the deep-space applications. Form visible light communications to wearables, OWC is a way to reuse our natural space of communications the free space and the light.
Seminar presented at Universitat Politecnica de Valencia, Spain during the OQCG regular seminars' series, March 2014. by Dr Joaquin Perez
Optical wireless communication, also known as free space optics (FSO), uses lasers or LEDs to transmit data through the air. FSO can provide high-speed broadband connections for the "last mile" between buildings. However, FSO systems face challenges from atmospheric conditions like fog, rain, and smoke that can attenuate the optical signal. Proper choice of wavelength, transmitter power, receiver design, and link length can help overcome these challenges to provide reliable, high-bandwidth communication over short to medium distances.
This document summarizes a technical seminar on free space optics (FSO) presented by Kartik K Benageri at Jain Institute of Technology in Davangere, Karnataka, India. The seminar covered the introduction, key features, working principles, advantages, limitations, and conclusions of FSO technology. FSO uses lasers and photo detectors to transmit data, voice, or video at speeds up to 2.5 Gbps in a line-of-sight fashion without the need for fiber. While offering benefits like flexibility, low cost, and security compared to fiber or microwave, FSO performance can be impacted by environmental factors like fog, rain, scattering, and building sway. The seminar provided information
Free-space optical (FSO) communication uses visible light or infrared light beams to transmit data through the air. It works similarly to fiber optics but transmits the light beam through the air instead of glass fibers. FSO systems can transmit data at rates similar to fiber optics over distances up to a few kilometers. They provide a wireless complement to radio-based communication systems. The main requirements are having an unobstructed line-of-sight between the transmitter and receiver and clear atmospheric conditions.
The document summarizes free space optical communication (FSO). It discusses the operation of FSO links, their advantages over fiber and microwave links, and applications. The key points are:
1. An FSO link consists of a transmitter, receiver, and tracking system to direct light beams between nodes. It allows license-free, high-speed connections but is susceptible to weather.
2. Applications include point-to-point links between buildings and potential mesh networks or use on high altitude platforms. Mesh networks provide better coverage but at a higher cost than point-to-point links.
3. Compared to fiber and microwave links, FSO systems have lower costs and power needs but higher data rates and
Free space optical communication (FSO) uses lasers and photo detectors to transmit data through the air without fiber cables. It was initially developed by NASA and the military. FSO can transmit data, voice, or video at speeds up to 1.25 Gbps using invisible beams of light in a line-of-sight system. Signal propagation is impacted by weather like fog and rain, which can cause scattering and absorption leading to power losses and interruptions. While installation has low costs compared to fiber, FSO performance depends on clear line-of-sight conditions.
1. Optical fibers transmit data using pulses of light and are able to carry much higher bandwidths than metal wires.
2. Fibers use total internal reflection to guide light along their length with less loss than wires and are immune to electromagnetic interference.
3. Fibers have various applications including long distance communications, local networks, imaging bundles, and sensors.
Free-space optical communication is an optical communication technology that uses light propagating in free space to wirelessly transmit data for telecommunications or computer networking. It is a technology that can be installed license-free worldwide and can be installed in less than a day. A technology that offers a fast, high ROI. There is no Frequency License Required in it.
This presentation discusses freespace optical communication (FSO), which transmits modulated beams of light through the atmosphere for broadband communications. It provides a brief history of FSO, describes how FSO works by converting network traffic to light pulses, and lists its advantages like low cost, high security, and immunity to electromagnetic interference. The presentation also outlines FSO's applications like metro networks and last mile access, and discusses its disadvantages such as reliance on line of sight and susceptibility to atmospheric conditions.
Free Space Optics (FSO) communications, also called Free Space Photonics (FSP) or Optical Wireless, refers to the transmission of modulated visible or infrared (IR) beams through the atmosphere to obtain optical communications. Like fiber, Free Space Optics (FSO) uses lasers to transmit data, but instead of enclosing the data stream in a glass fiber, it is transmitted through the air. Free Space Optics (FSO) works on the same basic principle as Infrared television remote controls, wireless keyboards
Li-Fi is a new wireless technology which provides the connectivity within localized network environment. The main principle of this technology is we can transmit the data using light illumination by using light emitting diodes where radio frequency is media in Wi-Fi and LED bulb light intensity is faster than human eye can follow. One germen phycist-Prof Harald Haas an expert in optical wireless communications at the University of Edinburgh, he demonstrated how an LED bulb equipped with signal processing technology could stream a high-definition video to a computer. By using this technology a 1 watt LED light bulb would be enough to provide net connectivity to four computers. This technology termed as "light fidelity". This technology allows us to transfer data more securely with higher data rates. This technology is still under research and further exploitation could lead to wide applications.
This document discusses key characteristics of optical fibers that affect their performance as a transmission medium. It describes how wavelength, frequency, reflection, refraction, polarization, and attenuation properties influence fiber optic communication. Specific bands used in optical fibers, including O, C, E, S and L bands, are defined. The document also examines intrinsic and extrinsic factors contributing to fiber attenuation, as well as dispersion which limits bandwidth by spreading out light pulses over time as they travel through the fiber.
1) What is Fiber Optics?
2) Structure of Fiber Optics.
3) Modes of Fiber Optics.
4) How It Is made.
5) Communication System.
6) Evolution of Fiber Optics.
7) Advantages/ Disadvantages.
8) Applications of Fiber Optics.
9) Conclusion.
Optical networking uses fiber optic cables to transmit data via light pulses. Early networks like FDDI used two fiber rings operating at 100 Mbps. SONET/SDH later became the standard, using synchronous transmission and hierarchical multiplexing of lower speed streams. SONET/SDH supports various network configurations including point-to-point links, linear and ring topologies using add/drop multiplexers. Rings provide high availability through fast automatic protection switching.
This document discusses optical time division multiplexing (OTDM) systems. It outlines some of the key challenges with OTDM, including nonlinearity in fibers causing signal-to-noise ratio degradation as the number of channels increases. It also discusses the components needed for an OTDM system, including ultra-short optical pulse generation and modulation at the transmitter, and optical clock extraction and demultiplexing at the receiver. Several approaches for OTDM demultiplexing are described, such as using cascaded modulators, nonlinear optical loop mirrors, or four wave mixing in a nonlinear medium.
LTE carrier aggregation technology development and deployment worldwidecriterion123
Carrier aggregation (CA) allows the combination of multiple component carriers to increase bandwidth and throughput. CA can be intra-band, combining contiguous or non-contiguous carriers within a band, or inter-band, combining carriers across frequency bands. Inter-band CA provides more flexibility to utilize fragmented spectrum. The LTE standard defines a maximum of five component carriers for CA. CA improves downlink throughput by increasing bandwidth but may not always increase uplink throughput due to limitations of UE maximum power. Close frequency band CA and FDD-TDD CA require additional RF components to separate signal paths and prevent interference between bands.
This document discusses dispersion compensation techniques for optical code division multiple access (OCDMA) systems using dispersion compensation fiber (DCF) and fiber gratings. It compares the performance of an 8-user OCDMA system using DCF versus fiber gratings. The results show that DCF more effectively compensates for dispersion, as evidenced by a lower bit error rate and higher Q factor, making it a better dispersion compensation method for OCDMA systems compared to fiber gratings.
This document summarizes a seminar presentation on Optical Code Division Multiple Access (OCDMA). OCDMA allows multiple users to transmit simultaneously over the same bandwidth using unique optical codes. It provides advantages over TDMA and FDMA such as supporting more users and asynchronous transmission without packet collisions. The presentation describes OCDMA network implementation using optical orthogonal codes assigned to transmitters and receivers for communication. It also discusses enhanced security provided by OCDMA through increasing the signal-to-noise ratio required for eavesdropping.
With the concept of 3G & 4G services OCDMA is one of the important technologies, that provide a very high speed communication. In this technology multiple users can communicate simultaneously to transfer different kind of data. OCDMA enables the best use of available bandwidth and the spectrum to represent a cost efficient network. But in a network there is always the requirement to increase the security and the efficiency or the throughput of a multiuser communication in the OCDMA network. The proposed work is about to increase the efficiency in a Noisy channel. Here the work will be performed on impulse noised network. We are here proposing the orthogonal approach along with OCDMA to improve the throughput. We are trying to show the results in terms of noise ratio and the derived throughput. The proposed work is about to reduce this packet loss and to increase the throughput in the noisy network. To overcome this drawback and to increase the throughput we are using the concept of OFDM along with CDMA. This concept is represented as the Orthogonal CDMA.
Performance Analysis of Multi-QoS Model of OCDMA System by Adopting OPPM Sign...IJERA Editor
In this paper, optical CDMA which combines the large bandwidth of the fibre medium with the flexibility of the
CDMA technique to achieve high speed connectivity has been used. For achieving this purpose, OPPM
signalling and switching techniques have been employed. This helps in the achievement of high tolerance to
Multiple Access Interference, further resulting in improvement of both the Bit Error Rate and optical channel
capacity without the need to decrease the light pulse width. An OPPM scheme to support multimedia services
with different transmission rates and Quality of Service requirements is proposed. Packet Switching technique
has been employed to help in the transfer of data in the form of packets from the source to the destination via a
specified route. The results are calculated by using PPM signalling and switching technology.But switching
technology has been found to be far better than the OOK-OCDMA if the average power has been considered as
the restraining factor.
This document analyzes the performance of a four user optical code division multiple access (OCDMA) communication system under the effect of jitter. Simulations were conducted using Rsoft Optsim to evaluate the bit error rate (BER) and Q-factor of the system with jitter varying from 0 to 3 picoseconds. The results show that as jitter increases, BER increases and Q-factor decreases for different fiber lengths of 10km, 30km, 50km and 70km. Specifically, BER varies from 2.11E-02 to 1.71E-02 as jitter increases for a 10km fiber length. For a 30km length, BER increases from 2.11E-02 to 1.71
Dense wavelength division multiplexing....Arif Ahmed
The document discusses performance analysis of dense wavelength division multiplexing (DWDM) optical transmission systems. It begins with an introduction to DWDM, which allows transmission of up to 132 wavelengths over a single fiber. Section 2 provides an overview of optical fiber transmission and prior multiplexing techniques such as time division, frequency division, subcarrier, and coarse and dense wavelength division multiplexing. Section 3 indicates that the performance of DWDM will be analyzed using its application in NEMO, ANTARES, and KM3NeT underwater neutrino telescope experiments.
This document summarizes a research paper that analyzes the performance of various digital filters in an OCDMA (Optical Code Division Multiple Access) multi-user environment using 3D codes. The document describes a simulation of a 24-user OCDMA system using different parameters like BER (Bit Error Rate), Q-factor, and eye patterns with filters including Raised Cosine, Gaussian, Fabry Perot, Trapezoidal, and Lorentzian. The analysis found that the system using a Fabry Perot filter had the minimum distortion while maintaining a low BER of 6.81×e-20 for correctly decoded signals.
IOSR Journal of Electronics and Communication Engineering(IOSR-JECE) is an open access international journal that provides rapid publication (within a month) of articles in all areas of electronics and communication engineering and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in electronics and communication engineering. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
Design of high scalability multi-subcarrier RoF hybrid system based on optica...nooriasukmaningtyas
The technology of radio over fiber (RoF) regard a crucial point to solve
problems in wireless communication system. As well as, the growth of
internet applications also reveals a tremendous increase in bandwidth for
different applications. Therefore, the development of optical networks is very
important that have maximum bandwidth by using different multiple access
techniques. Optical code division multiple access (OCDMA) technique has
considered as a good solution for high bandwidth network. Hybrid optical
systems of OCDMA and time division multiplexing (OTDM) has been
proposed in this paper to increase the number of simultaneous users. The
results of hybrid OCDMA and OTDM system demonstrate that this system
can make a considerable increase in the network scalability while ensuring
sufficient data rate and an acceptable bit error rate. Where M-user OCDMA
signals can be transmitted in different channels of an OTDM system. Due to
its wide band facility compared with other access techniques, OCDMA used
here. In addition to its high scalability for our radio network, the OTDM and
SCM utilized. The combination of these efficient access technique and
powerful time-sharing media are lead to increase the framework system
scalability.
Optimal Channel and Relay Assignment in Ofdmbased Multi-Relay Multi-Pair Two-...ijcnes
Efficient utilization of radio resources in wireless networks is crucial and has been investigated extensively. This letter considers a wireless relay network where multiple user pairs conduct bidirectional communications via multiple relays based on orthogonal frequency-division multiplexing (OFDM) transmission. The joint optimization of channel and relay assignment, including subcarrier pairing, subcarrier allocation as well as relay selection, for total throughput maximization is formulated as a combinatorial optimization problem. Using a graph theoretical approach, we solve the problem optimally in polynomial time by transforming it into a maximum weighted bipartite matching (MWBM) problem. Simulation studies are carried out to evaluate the network total throughput versus transmit power per node and the number of relay nodes
This document summarizes research on improving the performance of WiMAX systems using FEC zigzag coding and MIMO techniques. It first provides background on WiMAX and discusses how OFDM, MIMO, and various channel coding schemes like zigzag codes work. It then evaluates the bit-error rate performance of WiMAX systems using zigzag-coded modulation with different code rates and lengths. The results show zigzag coding presents stronger error correction than Reed-Solomon with Convolutional coding. Encoding and decoding of zigzag codes is explained, along with how concatenated zigzag codes provide even stronger error correction through interleaving and turbo processing.
A simulation study of wi max based communication system using deliberately cl...eSAT Journals
This document summarizes a study on reducing peak-to-average power ratio (PAPR) in orthogonal frequency division multiplexing (OFDM) systems using deliberate clipping. It begins with an introduction to WiMAX technology and OFDM. It then discusses the PAPR problem in OFDM systems and different techniques to reduce PAPR, including signal scrambling and signal distortion methods. It focuses on deliberate clipping as a simple method to limit PAPR by distorting the signal before amplification. The document presents a simulation of an OFDM system using deliberate clipping at the Nyquist sampling rate to investigate its effect on bit error rate performance compared to an unclipped system.
A simulation study of wi max based communication system using deliberately cl...eSAT Publishing House
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
OPTICAL SWITCHING CONTROLLER USING FPGA AS A CONTROLLER FOR OCDMA ENCODER SYSTEMEditor IJCATR
This paper proposed a design of optical switching controller using FPGA for OCDMA encoder system. The encoder is one
of the new technologies that use to transmit the coded data in the optical communication system by using FPGA and optical switches.
It is providing a high security for data transmission due to all data will be transmitting in binary code form. The output signals from
FPGA are coded with a binary code that given to an optical switch before it signal modulate with the carrier and transmit to the
receiver. In this paper, AA and 55 data were used for source 1 and source 2. It is generated sample data and sent packet data to the
FPGA and stored it into RAM. The simulation results have done by using software Verilog Spartan 2 programming to simulate. After
that the output will produces at waveform to display the output. The main function of FPGA controlling unit is producing single pulse
and configuring optical switching system.
In recent past the influence of Radar has played a significant part in various fields. Radar sensing is one of
the prime application by which velocity and distance of a moving target can be found out. A joint RadCom
system to serve both radar sensing and wireless communication is proposed which ensures better
performance in terms of spectral efficiency, extended detection range and cost effectiveness. Such systems
demand for a common waveform which is designed in this work that perfectly matches to the system
requirements. OFDM multi carrier technique is chosen to generate a common waveform. Applicability of
multiple antenna technique for direction of arrival estimation is also considered. MIMO-OFDM technique
has gained much interest in the field of communication which improves the signal to noise ratio and lowers
the bit error rate. On the other hand the usage of MIMO reflects in the form of interference between
signals. In order to overcome this effect beamforming technique is used. In addition to theoretical
explanations we have also simulated and discussed the results for the proposed RadCom system using
MATLAB simulation tool.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
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Iaetsd ber performance of cdma, wcdma, ieee802.11g in awgnIaetsd Iaetsd
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Introduction- e - waste – definition - sources of e-waste– hazardous substances in e-waste - effects of e-waste on environment and human health- need for e-waste management– e-waste handling rules - waste minimization techniques for managing e-waste – recycling of e-waste - disposal treatment methods of e- waste – mechanism of extraction of precious metal from leaching solution-global Scenario of E-waste – E-waste in India- case studies.
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Time Division Multiplexing (TDM) is a method of transmitting multiple signals over a single communication channel by dividing the signal into many segments, each having a very short duration of time. These time slots are then allocated to different data streams, allowing multiple signals to share the same transmission medium efficiently. TDM is widely used in telecommunications and data communication systems.
### How TDM Works
1. **Time Slots Allocation**: The core principle of TDM is to assign distinct time slots to each signal. During each time slot, the respective signal is transmitted, and then the process repeats cyclically. For example, if there are four signals to be transmitted, the TDM cycle will divide time into four slots, each assigned to one signal.
2. **Synchronization**: Synchronization is crucial in TDM systems to ensure that the signals are correctly aligned with their respective time slots. Both the transmitter and receiver must be synchronized to avoid any overlap or loss of data. This synchronization is typically maintained by a clock signal that ensures time slots are accurately aligned.
3. **Frame Structure**: TDM data is organized into frames, where each frame consists of a set of time slots. Each frame is repeated at regular intervals, ensuring continuous transmission of data streams. The frame structure helps in managing the data streams and maintaining the synchronization between the transmitter and receiver.
4. **Multiplexer and Demultiplexer**: At the transmitting end, a multiplexer combines multiple input signals into a single composite signal by assigning each signal to a specific time slot. At the receiving end, a demultiplexer separates the composite signal back into individual signals based on their respective time slots.
### Types of TDM
1. **Synchronous TDM**: In synchronous TDM, time slots are pre-assigned to each signal, regardless of whether the signal has data to transmit or not. This can lead to inefficiencies if some time slots remain empty due to the absence of data.
2. **Asynchronous TDM (or Statistical TDM)**: Asynchronous TDM addresses the inefficiencies of synchronous TDM by allocating time slots dynamically based on the presence of data. Time slots are assigned only when there is data to transmit, which optimizes the use of the communication channel.
### Applications of TDM
- **Telecommunications**: TDM is extensively used in telecommunication systems, such as in T1 and E1 lines, where multiple telephone calls are transmitted over a single line by assigning each call to a specific time slot.
- **Digital Audio and Video Broadcasting**: TDM is used in broadcasting systems to transmit multiple audio or video streams over a single channel, ensuring efficient use of bandwidth.
- **Computer Networks**: TDM is used in network protocols and systems to manage the transmission of data from multiple sources over a single network medium.
### Advantages of TDM
- **Efficient Use of Bandwidth**: TDM all
1. A
PROJECTP ROGRESS REPORT
On
OPTICAL CDMA
SUBMITTED BY:
BRIJESH BHARTI
CIT-06/16
Under the Guidance of
Dr. GausiaQazi
Department of Electronics & Communication Engineering
National Institute of Technology, Srinagar
Jammu and Kashmir 190006
2. Table of Contents
1. Abstract
2. Project overview
2.1 Introduction
2.2Principles of coding in OCDMA
3. Find major Challenges
3.1 BER (major issue)
3.2 OCDMA, MAI (multi user interference)
3.3Component cost and complexity
3.4Signal Loss in Multimode and Single-Mode Fiber-Optic Cable
3.5 Attenuation and Dispersion in Fiber-Optic Cable
4. Methods to overcomethe challenges
4.1Using Spectral Amplitude Coding (SAC)
4.2Spectral Phase Coding (SPC)
4.3Based on fiber Bragg grating (FBG) encoder/decoder
5. Simulation of OCDMABased on (FBG) encoder/decoder
5.1measurement of BERfor 1km distance
5.2 measurementof BER for 100 km distance
6. Applicationof OCDMA
6.1From LAN to PON
6.2 OCDMA for access networks
6.3Metro-level optical VPN
6.4 Optical control signaling and OBS
6.5 All-optical switching and label routing
6.6 Network monitoring and OCOTDR
6.7 All-optical multicasting
7. References
3. Abbreviations
BER bit error rate
MAI multiple access interference
TDMA time division multiple access
CDMA code division multiple access
LAN local area network
PON passive optical network
VPN OpticalVirtual Private Network
OTDR optical time-domain reflectometry
OCLS label switch
4. 1. Abstract
In this project report we try to enhance the performance of optical fiber communication using
the optical CDMA technology, using different modulation techniques and coding and
decoding techniques. And main focus on reduce the BER and MAI in optical CDMA
system.Because of consumer bandwidth demands are rapidly growing at huge rate, and are
expected to keep growing for years to come. This growth applies not only to the internet
usage, but to a large range of individual institutions. Most ofthe downstream traffic is web
media which is mainly due to photo and video communication and real-time streaming.so we
to improve the performance of Optical CDMA .for high speed data communication
.nowadays Meany researcher are working on optical CDMA technology .in optical fiber
communication .
5. 2.1Introduction
Optical CDMA stands for Optical Code Division Multiple Access. OCDMA Technologyis
one of the promising technologies to implement alloptical networks, which has the potential
to exploit the unmannedbandwidth of optical fiber and take advantage of the predominance of
CDMA technology. OCDMA is a category of multiplexing and internetworking technologies
that encodes/decodes signals through employing simple and costeffective passive optical
components such that the signal multiplexing, routing and switchingcan be implemented
smoothly.Driven by the rapid increasing demands of communication bandwidth, multiplexing
is essential in bothwireless radio and fiberoptic networks. Codebased network access has the
tendency to simplify the network control and management with enhanced information
security. The efficient multipleaccessprotocol also allows many users to access the fiber
channel asynchronously and simultaneously without delay and scheduling. OCDMA is based
on the principle.that codesare mapped to the identities or addresses of users following a code-
user relation. Accordingly OCDMA was initially proposed to implementultrafast
asynchronous broadcast LAN.The OCDMA cam be implemented in various method .and
class show in fig (1.1)
6. Fig (1.1) optical CDMA classification
2.2Principles of coding in OCDMA
An encoding operation optically transforms each data bit before transmission. At the receiver,
the reverse decoding operationis required to recover the original data. The encoding and
decoding operations alone constitute optical coding. OCDMA is the use ofOCDM technology
to arbitrate channel access among multiple network nodes in a distributed fashion. Code
sequence either in the time domain, the wavelength domain, or a combination of both. The
latter method is called two-dimensional coding (2D-coding) illustrates the three coding
principles. In a time-encoded signal, the bit is split into smaller time components called chips.
Time-domain coding that manipulates the phase of the optical signal is usually bipolar and
requires phase-accurate coherent sources. Alternatively, positive encoding manipulates the
power of the optical signal but not its phase and typically uses incoherent sources. In
wavelength- domain coding, transmitted bits consist of a unique subset of wavelengths
forming the code. 2D-coding combines both wavelength selection and time spreading. A data
bit is encoded as consecutive chips of different wavelengths, the unique wavelength sequence
constituting the code. Decoding consists of applying the reverse time/wavelength operations.
Regardless of the coding domain, the coding operation broadens the spectrum of the data
signal, hence the designation of spread spectrum. Note that encoding can also be performed
in the space-domain, whereby the code determines the positions of chips within a dense fiber
array or a multicore fiber.
3. Find major Challenges [1]
3.1BER The bit error rate (BER) is the number of bit errors per unit time. The bit error ratio
(also BER) is the number of bit errors divided by the total number of transferred bits during a
studied time interval. Bit error ratio is a unit less performance measure, often expressed as a
percentage. The bit error probabilitype is the expectation value of the bit error ratio. The bit
error ratio can be considered as an approximate estimate of the bit error probability. This
estimate is accurate for a long time interval and a high number of bit errors. Bit error in
optical CDMA due to noise in optical fiber channel .bit error is major issue in
communication.
7. 3.2 OCDMA, MAIan OCDMA local area network (LAN) is based on a broadcast
medium. Signals from different encoders are coupled and each decoder receives the sum of
the encoded signals. If a given encoder transmits a signal, only the decoder with the same
code is capable of recovering it. Unwanted signals appear as noise to the decoder and are
called multiple-access interference (MAI). MAI is the principal source of noise in OCDMA
and is the limiting factor to system performance. In a well-designed OCDMA LAN where
MAI is overcome, users can successfully communicate asynchronously and regardless of
network traffic.
3.3Component cost and complexity Component cost and complexity are key
issues in OCDMA system design. For instance, the tenability of encoders and decoders
represents a significant challenge compared to tenability of WDMA transceivers. In addition,
currently available broadband light sources required for spectral or 2D-OCDMA operation
are eitherexpensive or do not offer enough intensity OCDMA is limited in network reach by
dispersion due to the high encoded signal bit rateand high power budget required
3.4Signal Loss in Multimode and Single-Mode Fiber-Optic Cable
Multimode fiber is large enough in diameter to allow rays of light to reflect internally
(bounce off the walls of the fiber). Interfaces with multimode optics typically use LEDs as
light sources. However, LEDs are not coherent sources. They spray varying wavelengths of
light into the multimode fiber, which reflects the light at different angles. Light rays travel in
jagged lines through a multimode fiber, causing signal dispersion. When light traveling in the
fiber core radiates into the fiber cladding, higher-order mode loss results. Together these
factors limit the transmission distance of multimode fiber compared with single-mode fiber.
Single-mode fiber is so small in diameter that rays of light can reflect internally through one
layer only. Interfaces with single-mode optics use lasers as light sources. Lasers generate a
single wavelength of light, which travels in a straight line through the single-mode fiber.
Compared with multimode fiber, single-mode fiber has higher bandwidth and can carry
signals for longer distances. Exceeding the maximum transmission distances can result in
significant signal loss, which causes unreliable transmission.
8. 3.5 Attenuation and Dispersionin Fiber-Optic Cable
Correct functioning of an optical data link depends on modulated light reaching the receiver
with enough power to be demodulated correctly. Attenuation is the reduction in power of the
light signal as it is transmitted. Attenuation is caused by passive media components, such as
cables, cable splices, and connectors. Although attenuation is significantly lower for optical
fiber than for other media, it still occurs in both multimode and single-mode transmission. An
efficient optical data link must have enough light available to overcome attenuation.
Dispersionis the spreading of the signal over time. The following two types of dispersion can
affect an optical data link:
Chromatic dispersion—spreading of the signal over time resulting from the different
speeds of light rays.
Modal dispersion—spreading of the signal over time resulting from the different
propagation modes in the fiber.
For multimode transmission, modal dispersion, rather than chromatic dispersion or
attenuation, usually limits the maximum bit rate and link length. For single-mode
transmission, modal dispersion is not a factor. However, at higher bit rates and over longer
distances, chromatic dispersion rather than modal dispersion limits maximum link length. An
efficient optical data link must have enough light to exceed the minimum power that the
receiver requires to operate within its specifications. In addition, the total dispersion must be
less than the limits specified for the type of link in Telcordia Technologies document GR-
253-CORE (Section 4.3) and International Telecommunications Union (ITU) document
G.957.When chromatic dispersion is at the maximum allowed, its effect can be considered as
a power penalty in the power budget. The optical power budget must allow for the sum of
component attenuation, power penalties (including those from dispersion), and a safety
margin for unexpected losses.
4. Methods to overcome the challenges
4.1Using SpectralAmplitude Coding (SAC) [2]
In this project workwe are not consider this (SAC) coding techniques because is a promising,
cost effective,so little bit explanation about SAC. Method to reduce the BER ,The optical
spectral amplitude coding help to overcome the noise(BER) issue in optical CDMA system,
the code structure for spectral amplitude coding optical codedivision multiple access
9. (CDMA) is proposed and analyzed. It is shown that such codes can effectively suppress the
intensity noise and in turn increase the number of active users and improve the bit error rate
performance.
4.2SpectralPhaseCoding (SPC)[3]
The spectral phase coding help to reduce the MAI in optical CDAM system
Spectral phase coded OCDMA system architecture is illustrated by Fig. (2.1). The SPC-
OCDMA system requires a broadband multi wavelength source, one of the most popular
sources is mode-locked laser (MLL).By this kind of spectral phase encoders the modulated
spectrum separated into spectral bins and applies a distinct phase shift to each bin. The phase
components could be simple binary codes (0 &1) or more advanced multilevel phase codes.
Spectral Phase Encoder/Decoder Technologies
The fundamental function of SPC - OCDMA technology is the ability to access and modify
uniformly the phase of spectrum components. The basic operation of such encoder/decoders
consists of three processes, DE multiplexing the optical pulse into addressable spectral
components, adding a prescribed phase change uniformly across the spectral components,
and multiplexing the phase encoded spectral components back into fiber. DE multiplexing
and multiplexing processes can be done in series or parallel depending on theapplied
technology. There are three technologies that have been applied in SP Encoder/Decoders,
diffraction gratings, virtually imaged phased array, and cascaded micro-ring resonators
10. Fig 3. Block diagram of SPC-OCDMAsystem.
4.3 Basedon fiber Bragg grating[4]
A fiber Bragg grating (FBG) is a type of distributed Bragg reflector constructed in a short
segment of optical fiber that reflects particular wavelengths of light and transmits all others.
This is achieved by creating a periodic variation in the refractive index of the fiber core,
which generates a wavelength-specific dielectric mirror. A fiber Bragg grating can therefore
be used as an inline optical filter to block certain wavelengths, or as a wavelength-specific
reflector.
11. The fundamental principle behind the operation of an FBG is reflection, where light traveling
between media of different refractive indices may both reflect and refract at the interface. The
refractive index will typically alternate over a defined length. The reflected wavelength (𝜆𝐵),
called the Bragg wavelength.
(FBG) encoder/decoder
The encoding/decoding scheme based on Fiber Bragg Grating (FBG) for Optical Code
Division Multiple Access (OCDMA) system is analyzed and the whole process from
transmitting end to receiving end is are simulated in this project work Having the properties
of large system capacity, great security, asynchronous connectivity, and high anti-jamming
ability, Optical Code Division Multiple Access (OCDMA) system, a very attractive multiple-
access technology, is receiving more and more attention and being researched well One of the
key technologies required on the practical application of OCDMA is the design of its core
parts, encoder/decoder. Fiber Bragg Grating (FBG) has been applied inmany fields of optical
communication and tailor technique for it has been improved largely in recent years.
Benefited from its unique filtering property, FBG is also becoming the major choice as the
material of optical encoder/decoder in OCDMA system. Uniform FBG is a kind of short-
period fiber grating, of which the reflection is utilized. The periodical variation of the
refraction index along the fiber axis makes FBG act as an optical band rejection filter, whose
center reflecting wavelength is AB, called the Braggwavelength. In non-coherent OCDMA
12. system, we employ the users' signature codes to control the center reflecting wavelength of
FBGs in order to reflect the broadband signal.
5. Simulation of OCDMABasedon (FBG)encoder/decoder
The spectral amplitude coded optical code division multiple access system for three users
where third user id off the detection technique we have chosen is single photo detection
(SPD) technique. The BER for user 1 and user 2 are 0.0092 and 0.00621 respectively. But
still we are searching how to improve theBER.
Simulation parameters in FGB based Optical CDMA
Optical channel
Distance 1KM
Attenuation 0.2 dB/Km
Reference wave length 1550 nm
Dispersion 16.75 ps/nm/km
Dispersion slop 0.075 ps/nm/km
Uniform FGB
Bit rate 10e+009 bps
Time window 0.1024e-006 s
Number per sample 64
Signal bit rate200mbps
Sequence length1024 bits
Samples rate 640e+009Hz
5.5 measurement of BER for 1km distance
For distance 1 km
Distance 1 Km
Attenuation 0.2 dB/Km
Reference wave length 1550 nm
Dispersion 16.75 ps/nm/km
Dispersion slop 0.075 ps/nm/km
15. 6 Application of OCDMA
6.1 From LAN to PON
LAN and PON contender techniques include TDMA, SCMA, and WDMA, denoting time-,
subcarrier-, and wavelength-division multiple access respectively. In TDMA, a time slot is
allocated to each user statically or dynamically. TDMA already is deployed in two forms:
asynchronous transfer mode PON (with various extensions) and Ethernet PON (EPON). In
WDMA, each user has a specific wavelength.Both TDMA and WDMA benefit from the
maturity of electrical multiplexing and optical transmission gained in backbone networks.
TDMA/WDM is proposed as a viable extension to TDMA that achieves dynamic bandwidth
allocation (DBA) on multiple wavelengths. In SCMA, microwave channels are multiplexed
electrically, and the composite signal modulates the optical carrier. SCMA is commonly used
in hybrid fiber-coax networks to carry broadcast community access television (CATV)
channels. SCMA/WDM has notable applications in radio-over-fiber networks
6.2 OCDMA for access networks
OCDMA is viewed as a candidate technology for future PON access networks. An OCDMA
PON uses a tree topology with passivepower splitters. Each optical network unit (ONU)
contains an encoder and decoder with unique fixed codes. The optical line terminal (OLT)
may contain all encoder-decoder pairs required for communication with each ONU or a
smaller number of tunable encoder decoders. In contrast to LAN, OCDMA PON is not fully
broadcast systems, because the signal transmitted by an ONU never reaches other ONU.
Hybrid OCDMA/WDM systems have been proposed. More ambitious contributions
introduce mapping universal IP addresses to OCDMA codes.
6.3 Metro-level optical VPN
Wavelength routing metropolitan optical network may provide light paths for VPN
connections. These links carry a multitude of OCDMA signals that are multiplexed and
demultiplexed at the end-points the primary goal of a VPN is to provide secure data links
over an insecure platform. The OCDMA signals provide enhanced security and can be
decoded only at the corresponding end point. The use of OCDMA for all-optical VPN
simplifies network design by replacing electronic multiplexing and grooming with optical
splitting and combining. Light-tree capabilities at the metropolitan network level can be used
to enable the establishment of multipoint VPN.
16. 6.4 Optical control signaling and OBS
Optical coding benefits from the fact that more information can be packed all-optically in a
coded pulse in a wavelength assignment. We use the term code wordto designate a pulse
encoded in a unique code and corresponding to a specific piece of information or set of
commands. Like an OC-label, a code word can carry photonic signaling information such as
the status of links and equipment for maintenance, the availability of communication
channels such as wavelength light paths, and control commands for dynamic switches. OC-
gate-like devices enable the photonic processing of code words at optical speeds. Condensing
relevant information in a code word inserted in a control packet is analternative to electronic
processing of an optical control packet. In addition to the elimination of electronic processing
time, code words reduce control packet overhead. The mapping of codes to relevant values
(quantities or commands) requires the provision of enough codes to span the entire set of
information values. Longer codes enable condensing more information in a single code word.
6.5 All-optical switching and label routing
OC label switching is among the most promising implementations of optical coding. In an
OC label-switched network, optically-encoded pulsesare added to fixed-length packets as
headers that specify the route or label-switched path (LSP). In an OC label switch (OCLS),
each output portis controlled by a header-sensitive switching device called an optical code
gate (OC-gate). OC-gates allow through only packets with a specificheader (OC-label).
6.6 Network monitoring and OCOTDR
The goal of optical time-domain reflectometry (OTDR) technology is to monitor fiber plant
quality and detect faults, particularly fiber cuts. It is based on the emission of out-of-band
optical pulses and the analysis of resulting reflections. Pulse reflection analysis reveals the
position of cuts, as well as any optical devices causing unusual reflection losses such as faulty
connectors. OTDR has found wide-scale applications in WDM backbone point-to-point links.
In reflections at any of the PON branches. The localization of an eventual faulty branch is
impossible, unless upstream OTDR is performed at each ONU.
6.7 All-optical multicasting
OC label switching may be extended to implement a multicast (MC) tree network where
optical codes denote MC groups as well as individual end-users. The network topology
considered is a tree where MC-enabled OC label switches reside at each node except the end
nodes. Packets are labeled with OC pulses corresponding to their MC group.
17. 7. References
[1]H. Fathallah, “Optical CDMA Communications and theUse of OFCs,” Optical Fiber
Components: Design andUse of OFCs,” Optical Fiber Components: Design andApplications,
H. Hamam, Ed., Research Signpost,Trivandrum, Kerala, India, Jan. 2006, pp. 201–43.
[1,2] HooshangGhafouri_Shiraz, M. MassoudKarbassian (auth.)-Optical CDMA Networks_
Principles, Analysis and Applications-Wiley-IEEE Press (2012)
[2] www.elsevier.de/ijleo/ Implementation of spectrally-coded FBG-based coder/decoder
optical CDMA network Accepted 6 September 2015