Broadband Access

Traffic engineering and an economical provisioning of bandwidth is crucial for network providers in times of high competition in broadband access networks. We investigate the efficiency of caching as an option to shorten end-to-end paths and delays while at the same time reducing traffic loads. The portion of HTTP based distribution of cacheable content on the Internet is increasing in recent time. In addition, the favourable effect of Zipf-like access pattern on caches is also confirmed for currently most popular web sites with user generated content. Content delivery (CDN) and peer-to-peer (P2P) networks are distributing a major portion of IP traffic with different impact on caching. P2P traffic is subject to long transport paths although appropriate for caching in principle. CDNs are based on server infrastructures allowing for shorter paths on a global scale on top of network provider platforms. We give a brief overview of the options for deploying caches by content and network providers at different points in the interconnection, backbone or aggregation. The main part of the work focuses on the analysis of replacement strategies with regard to Zipf-like and fixed or slowly varying access pattern. A comparative evaluation shows that least recently used (LRU) essentially differs from caching strategies based on access statistics in terms of the achievable hit rates.

Abstract—This paper describes a complete demo sce-nario where a Triple Play configuration (video, audio and data) with quality of service will be shown. This scenario could be considered as the aim of the Next Generation Networks (NGN) where a unified network is used to ...

This letter presents a low cost solution for wavelength division multiplexed orthogonal frequency division multiplexed passive optical network (WDM-OFDM-PON) with widely tunable optical filter and linear small form-factor pluggable (SFP) module. With 9-nm tunable range from 1551 to 1560 nm, the tunable filter can support up to 10-channel 100-GHz spacing WDM PON system. A linear avalanche photodiode (APD) based SFP+ module is designed for optical OFDM signal demodulation, which can provide better receiver performance compared with limiting APD module. Experimental results show that ∼34 dB power budget can be achieved in 4×5-Gbps WDM-OFDM-PON system, which can satisfy the transmission requirements of next generation PON system.

Efficient uplink scheduling in Ethernet passive optical networks is very important to maximizing the network capacity while maintaining the required quality of service (QoS). Several variants of dynamic bandwidth resource allocation have been proposed in recent research literature. However, the available techniques do not fully exploit the elastic properties of the user traffic. In this paper, we explore optimal predictive resource allocation strategies by exploiting the elasticity of QoS constrained traffic and using the knowledge of traffic patterns of different service classes. We propose a predictive dynamic uplink bandwidth allocation scheme that offers lesser access delay and packet loss rate, yet achieving a higher overall network throughput. We formulate a model for determining the traffic burstiness dependent optimum prediction order that would enhance the quality of prediction with a minimum possible prediction-related processing overhead. We then demonstrate that, in a multi-class access scheduling, with respect to the conventional dynamic allocation strategies, our priority scheduling with judicious prediction of individual traffic classes can enhance the system performance significantly. Our analytic observations are supported by extensive simulation results.

Efficient uplink scheduling in Ethernet passive optical networks is very important to maximizing the network capacity while maintaining the required quality of service (QoS). Several variants of dynamic bandwidth resource allocation have been proposed in recent research literature. However, the available techniques do not fully exploit the elastic properties of the user traffic. In this paper, we explore optimal predictive resource allocation strategies by exploiting the elasticity of QoS constrained traffic and using the knowledge of traffic patterns of different service classes. We propose a predictive dynamic uplink bandwidth allocation scheme that offers lesser access delay and packet loss rate, yet achieving a higher overall network throughput. We formulate a model for determining the traffic burstiness dependent optimum prediction order that would enhance the quality of prediction with a minimum possible prediction-related processing overhead. We then demonstrate that, in a multi-class access scheduling, with respect to the conventional dynamic allocation strategies, our priority scheduling with judicious prediction of individual traffic classes can enhance the system performance significantly. Our analytic observations are supported by extensive simulation results.

Most broadband access networks such as passive optical networks (PONs) adopt the point-to-multipoint (P2MP) topology. One critical issue in such networks is the upstream resource management and allocation mechanism. Nonlinear predictor-based dynamic resource allocation (NLPDRA) schemes for improving the P2MP network upstream transmission efficiency have been investigated in an ad hoc manner. In this paper, we establish a general state space model to analyze the controllability and stability of the NLPDRA schemes from the P2MP network system's point of view and propose controller design guidelines to maintain the system stability under different scenarios. Analytical results show that NLPDRA maintains the P2MP network system controllability even when the loaded network traffic changes drastically. We further prove that a P2MP network system with NLPDRA is stable by proper pole placements as the traffic changes. Finally, we provide guidelines to design a optimal compensator to achieve system accuracy.

The integration of wireless local area networks (WLANs) and the high speed wide area network (WAN) using 'always on' broadband access that could provide an efficient and cost effective inter-WLAN mobility management requires the current WLAN internetworking protocol enhanced. The Inter Access Point Protocol (IAPP) defines methods for access point coordination over a distribution system to support WLAN interworking without any central intelligence to support mobility. The implementation of mobility management with any external central control in a distribution system, including broadband such as DSL, is not specified in any WLAN, including 802.11. This paper, first, presents an implementation of a distribution system with broadband DSL accessed central network control for IEEE 802.11 inter-WLAN mobility. Then the modification to the IAPP protocol messaging required for the broadband supported mobility management for inter-WLAN is presented. Preliminary simulation results demonstrating the effectiveness of the proposed distribution and its signaling are also provided.

This paper reviews and outlines the key features of the emerging next-generation fixed passive optical network (NG-PON)-based and fourth-generation (4G) mobile broadband access technologies and how to leverage the advantages of both of these access technologies to build a next-generation hybrid fiber-wireless (FiWi) network. Specifically, this paper presents an overview of the most recent research activities on these hybrid FiWi architectures, aiming to clarify the basic differences and distinguish between two FiWi networking architectural models, namely, the overlay or independent model and the truly integrated model. We then explore and present a new direction to the design and implementation of a simple and cost-effective all-packet-based converged fixed-mobile access networking solution that enables the true integration of NG-PON and 4G mobile broadband access technologies into the envisioned fixed-mobile platform. We briefly outline the general and technical requirements to support a unified NG-PON longterm evolution ((LTE) radio access network (RAN) architecture that conforms to both the typically centralized fixed PON and the emerging distributed 4G mobile LTE access standards. The implementation methodology on how to efficiently and cost-effectively integrate these two access technologies along with the main advantages gained from such an integrated architecture are outlined and presented.

We propose a simple model that is capable of capturing the statistical characteristics of mobile video traces encoded using MPEG4-Part2, AVC and SVC-TS encoding standards. The model can be adjusted to adapt to diverse workload configurations, which gives fellow researchers a great flexibility to evaluate different network traffic scenarios. We also discuss the modelbased trace generator and the challenges of its implementation. Moreover, we present the simulation results validating the model using different encoding settings. In addition to that, we provide several insights about our video modeling approach. This will help in testing, simulating and validating mobile video transmission and resource scheduling strategies over broadband wireless networks such as WiMAX and LTE..

The IEEE 802.16 is a well known set of standards, which have been developed for global deployment of Metropolitan Area Networks (MANs) in order to provide broadband wireless accesses supporting the integrated transmission of multimedia applications with different Quality of Service (QoS) requirements. In order to achieve the QoS requirements of multimedia applications, the IEEE 802.16 standards offers different scheduling schemes. This paper is concerned with the analytical modelling of the MAC protocol and the analysis of average message delays for real and non-real time traffics in broadband access wireless networks operating under the IEEE 802.16 standard. The message delays results obtained are presented for two scenarios, as a function of the load generated for different types of traffic. In addition, the impact on the network performance caused by some of the parameters utilized as part of the random access mechanism is also investigated. The results obtained through the use of the analytical model proposed in this paper are compared with those obtained with the aid of a simulation tool. The agreement of comparisons involving analytical and simulation results in the examples studied show that the model proposed in this paper could be very useful when utilized to represent and study further behavior characteristics of the end-to-end message delays involved in IEEE 802.16 standard MAC protocol under consideration.

Wireless Fidelity for Rural Extension (WiFiRE) is a MAC layer protocol especially designed to provide internet broadband facility in rural area in India. It supports long ranged communication using inherited 802.16d MAC and 802.11b PHY layer. WiFiRE uses low cost chip sets with capability to communicate on unlicensed spectrum to transmit over 15-20km. The report covers the background knowledge of WiFiRe protocol with basic working of the protocol and its implementation in C. Problems associated with design and implementation and their plausible solutions are covered as a part of report. Additionally, it also comprises of sequence diagrams, flow diagrams, state diagrams etc. of working components of WiFiRE along with design model in C sockets and describes the issues and challenges involving implementation of the projects.

High-speed or "broadband" Internet access currently is provided, at the local level, chiefly by cable television and telephone companies, often in competition with each other. Wireless and satellite providers have a small but growing share of this business. An influential coalition of economic interests and academics have proposed that local broadband Internet access providers be prohibited from restricting access to their systems by upstream suppliers of Internet services. A recent term for this proposal is "net neutrality." We examine the potential costs and benefits of such a policy from an economic welfare perspective. Using a property rights approach, we ask whether transactions costs in the market for access rights are likely to be significant, and if so, whether owners of physical local broadband platforms are likely to be more or less efficient holders of access rights than Internet content providers. We conclude that transactions costs are likely to be lower if access rights are assigned initially to platform owners rather than content providers. In addition, platform hardware owners are likely to be more efficient holders of these rights because they can internalize demand-side interactions among content products. Further, failure to permit platform owners to control access threatens to result in inadequate incentives to invest in, to maintain, and to upgrade local broadband platforms. Inefficiently denying platform owners the ability to own access rights implies a need for price regulation; otherwise, there will be incentives to use pricing to circumvent the constraint on rights ownership. Price regulation is itself known to induce welfare losses through adaptive behavior of the constrained firm. The impact on welfare might produce a worse result than the initial problem, assuming one existed. Much of the academic interest in net neutrality arises from the belief that the open architecture of the Internet under current standards has been responsible for its remarkable success, and a wish to preserve this openness. We point out that the openness of the Internet was an unintended consequence of its military origins, and that other, less open, architectures might have been even more successful. A policy of denying platform owners the ability to own access rights could freeze the architecture of the Internet, preventing it from adapting to future technological and economic developments. Finally, we examine the net neutrality issue from the perspective of the "essential facility doctrine," a tool of the common law of antitrust. The doctrine establishes conditions under which federal courts will mandate access by competitors to the monopoly platform of a vertically-integrated firm. Because local broadband Internet access is not today a bottleneck monopoly (there are several competitors and the market is at an early stage of development), the essential facilities doctrine would not permit reassignment of access rights from platform owners to competitors. We conclude that "net neutrality" is a welfare-reducing policy proposal. Owen

Wireless communication technology has been evolving over the years. From the 2.5G era where the General Packet Radio Service (GPRS) offered very low data rates of 171.2 Kbps to the 3.5G era where the High-Speed Downlink Packet Access (HSDPA) offered data rates of 10.8 Mbps, the increased data rates can support the delivery of richer mobile multimedia contents to end-users. With the growing demand in data throughput, the IEEE 802.16e promises to deliver high data rates over large areas to a large number of users in the near future. This exciting technology can rapidly provide broadband access to locations in the world's rural areas where broadband is currently unavailable, as well as competing for urban market share. In this paper, we will investigate the research issues in devising rate adaptation algorithms at the WiMAX PHY and MAC layers. We will propose a framework in which the PHY layer metrics can be passed into the MAC layer under practical simulation environment. 1

Hybrid optical and wireless technology integrations have been considered as one of the most promising candidates for the next generation broadband access networks for quite some time. The integration scheme provides the bandwidth advantages of the optical networks and mobility features of the wireless networks for Subscriber Stations (SSs). It also brings economic efficiency to the network providers particularly in rural area where the existing wired telecommunication infrastructures such as Digital Subscriber Line (DSL), Cable Modem (CM), T-l/E-I networks or fibre deployments are either costly or unreachable. For successful integration of the optical and wireless technologies there are some technical issues which need to be addressed efficiently in order to provide End-to-End (ETE) and diverse Quality of Service (QoS) for various service classes. This paper investigates the possible challenging issues for the integrated structure of the Time Division Multiplexing and Wavelength Division Multiplexing Ethernet Passive Optical Networks (TDM EPON and WDM EPON) with the Worldwide Interoperability for Microwave Access and Wireless Fidelity (WiMAX and Wi-Fi) networks. To reduce the ETE delay and provide the QoS for diverse service classes, we have compared six existing upstream scheduling mechanisms in two levels which are distributed on Access Points (APs) from Wi-Fi domain and Base Stations (BSs) from WiMAX domain. Performance evaluations of the existing scheduling techniques for three popular service classes (Quad-play) have been studied which show the strong impact of using the efficient up-link scheduler in converged scenario. We have also proposed a dynamic scheduling algorithm for optical and wireless integration scheme, which is under the implementation and evaluation process.

The Ethernet Passive Optical Networks (EPONs) have been considered as a promising candidate for the next generation wired access networks for quite some time. In EPONs bandwidth requests and bandwidth allocations are critical issues which need to be addressed efficiently in order to guarantee the End-to-End (ETE) Quality of Service (QoS) for diverse classes of services. In this paper, we discuss the application of a statistical prediction technique based on the Bayesian Belief Networks (BBNs) which provides real-time decision support to the EPONs Dynamic Bandwidth Allocation (DBA) function. We show that in situations of burst traffic it helps the DBA to predict additional bandwidth requirements.

His research interests are communications in the infrastructure and communications policy with emphasis on pricing, costing, regulation, valuations, and real options methodology. He provides litigation support in these areas. Jonathan Liebenau-Reader in Technology Management at London School of Economics and Fellow at CITI. He heads the "Technology Innovation: Management, Economics & Policy" team of LSE-Enterprise where he has undertaken projects in conjunction with Microsoft, Tata Consultancy Services, McAfee, and various bodies of the UK government Paul Rappoport-Associate Professor of Economics at Temple University and Fellow at CITI. He has over 30 years of experience in data analysis, modeling and statistical assessment specializing in telecommunications demand analysis. His research interests include: inter alia; the construction of internet metrics; assessing the Digital Divide; modelling business broadband; and forecasting internet demand.

WiMax uses orthogonal frequency division multiple access technique in wireless communication. Orthogonal frequency division multiple access (OFDM) is what puts the max in WiMAX, OFDM delivers a wireless signal much farther with less interference. This technique uses Adaptive modulation coding (AMC) on physical layer of WiMAX. Adaptive modulation technique uses the concept of cyclic prefix that adds additional bits at the transmitter end. The receiver removes these additional bits. Cyclic Prefix is used to combat intersymbol interference (ISI) and intercarrier interference (ICI) introduced by the multipath fading channel. This paper investigates the performance of WiMAX network by varying physical layer parameter such as modulation and coding scheme and cyclic prefix. It also investigates the performance of WiMAX network by increasing traffic (number of downloading nodes) in network with different cyclic prefix.The performance of WiMAX network is measured in terms of throughput and goodput

Re: Call for Contributions: Initial PHY Proposals (IEEE 802.16.3-00/24) Abstract A PHY is proposed for 802.16.3 in which modulation format and coding rate can be adjusted on a block by block basis to provide optimum channel utilization for the widest range of channel conditions. Purpose This proposal is offered as a PHY layer for the 802.16.3 Task Group Notice This document has been prepared to assist IEEE 802.16. It is offered as a basis for discussion and is not binding on the contributing individual(s) or organization(s). The material in this document is subject to change in form and content after further study. The contributor(s) reserve(s) the right to add, amend or withdraw material contained herein. Release The contributor grants a free, irrevocable license to the IEEE to incorporate text contained in this contribution, and any modifications thereof, in the creation of an IEEE Standards publication; to copyright in the IEEE’s name any IEEE Standards publication even though it...

We will divide this project into 3 phases so we can build and model our system in the right way for easy debugging. However, our first goal is to accomplish the first stage, and as time permits we will continue the other phases. We intend to complete our model with a full ...

WiMax (Worldwide Interoperability for Microwave Access) is a promising wireless technology with the aim of providing the last mile wireless broadband access designed for both fixed and mobile consumers as an alternative solution to the wired DSL and cable access schemes. The purpose of this research project is to investigate efficient resource allocation algorithms for WiMax. To achieve this goal, we investigate efficient PHY layer Partial Usage of SubCarriers (PUSC) allocation as well as MAC layer piggyback bandwidth request mechanisms.

Abstract—This paper describes a complete demo sce-nario where a Triple Play configuration (video, audio and data) with quality of service will be shown. This scenario could be considered as the aim of the Next Generation Networks (NGN) where a unified network is used to ...

Efficient uplink scheduling in Ethernet passive optical networks is very important to maximizing the network capacity while maintaining the required quality of service (QoS). Several variants of dynamic bandwidth resource allocation have been proposed in recent research literature. However, the available techniques do not fully exploit the elastic properties of the user traffic. In this paper, we explore optimal predictive resource allocation strategies by exploiting the elasticity of QoS constrained traffic and using the knowledge of traffic patterns of different service classes. We propose a predictive dynamic uplink bandwidth allocation scheme that offers lesser access delay and packet loss rate, yet achieving a higher overall network throughput. We formulate a model for determining the traffic burstiness dependent optimum prediction order that would enhance the quality of prediction with a minimum possible prediction-related processing overhead. We then demonstrate that, in a multi-class access scheduling, with respect to the conventional dynamic allocation strategies, our priority scheduling with judicious prediction of individual traffic classes can enhance the system performance significantly. Our analytic observations are supported by extensive simulation results.

Wireless networks bring about essential changes to data networking. Wireless Fidelity (Wi-Fi) is a wireless technology which has a rich set of features. WiMAX is one of the hottest broadband wireless technologies around the world. It uses encryption and decryption methods to protect the user privacy from theft. This paper presents an event-driven simulation tool that has been proved useful in studying the performance of both wired and wireless network.

The hybrid fiber coax architecture deployed by the cable service providers has been successful in capturing a substantial piece of the residential broadband access market. In the United States over five million homes connect to the Internet using DOCSIS 1 cable modems. In this article we describe an evolution path to enhance the HFC plant to provide, initially, Gigabit Ethernet (and eventually multi-Gigabit Ethernet) on the trunk and feeder portions, and 100 Mb/s Ethernet on the subscriber drops. This next-generation HFC network will enable cable service providers to address the vast and underserved small and medium-sized business market, as well as offer emerging applications and services to the residential market.

A detailed understanding of the many facets of the Internet's topological structure is critical for evaluating the performance of networking protocols, for assessing the effectiveness of proposed techniques to protect the network from nefarious intrusions and attacks, or for developing improved designs for resource provisioning. In this way Available bandwidth estimation is a vital component of admission control for quality-of-service (QoS) on Internet in the world.In coming years, Optical networks are come to dominate the access network space. Ethernet passive optical networks, which influence the all of subscriber locations of Ethernet, seems bound for success in the optical access network. In this Review Paper we first prepare an introduction to Ethernet passive optical networks structure, then related to our totally categorize the bandwidth allocation methods to three groups as Static and Router-Based and Windows-Based, we will explain seven major weaknesses on static group and describe the improvements on them one by one. Finally in this survey, we found some roles and principles in static bandwidth allocation methods which explain them separately.We hope in the next article we will explain the Dynamic bandwidth allocation weaknesses and improvements then make a comparison between static and dynamic bandwidth allocations. Following that, at the end, we will propose an algorithm on dynamic bandwidth allocation and evaluate it.

Abstract. A detailed understanding of the many facets of the Internet's topological structure is critical for evaluating the performance of networking protocols, for assessing the effectiveness of proposed techniques to protect the network from nefarious intrusions and attacks, or for developing improved designs for resource provisioning. In this way Available bandwidth estimation is a vital component of admission control for quality-of-service (QoS) on Internet in the world. In coming years, Optical networks are come to dominate the ...

With growing demand for high-speed access to mobile handheld devices, there is a significant cost benefit in deploying fixed wireless-mesh networks for backhaul access. However, enabling reliable broadband access over high-frequency radios (such as millimeter-wave networks) posses a fundamental challenge due to weather disruptions in general and rain attenuation in particular. In this paper, we present an analysis of the impact of precipitation on millimeter-wave mesh networks based on radar measurements of real storms in the Midwest US. Furthermore, we compare two novel algorithms that use physical-layer information to optimize routing at the network layer: P-WARP (Predictive Weather-Assisted Routing Protocol) and XL-OSPF (Cross-Layered Open Shortest Path First). Finally, we present simulation studies to compare the performance of the proposed protocols and evaluate the dependability of the end-user service during weather disruptions.

WiMAX and WiFi have emerged as promising broadband access solutions for the latest generation of wireless MANs and LANs, respectively. Their complementary features enable the use of WiMAX as a backhaul service to connect multiple dispersed WiFi hotspots to the Internet. This study proposes an integrated architecture utilizing a novel WiMAX/WiFi Access Point (W 2-AP) device to effectively combine the WiMAX and WiFi technologies. In the proposed architecture, the protocol operation of the WiFi hotspots is the same as that of the WiMAX system. As a result, the WiFi network can support connection-oriented transmissions and QoS in a similar fashion to the WiMAX system, and thus a considerable improvement in the delay performance is obtained. The numerical results obtained using a Qualnet simulator confirm both the effectiveness and the efficiency of the proposed architecture.

Due to strong local competition in the broadband access market, strategic locational planning is very important for service providers. In this paper, we explore locational equilibria in a competitive broadband market under several situations: with and without customer loyalty and under different initial market conditions. To do this, we propose a competitive broadband location model based on probabilistic patronage behavior, explicitly considering the characteristics of the broadband market and competitive structures. Also, we suggest iterative algorithms to identify spatial equilibria. We show that competing location strategies may lead to a stable spatial configuration of market share. The authors are grateful for the valuable comments from two anonymous reviewers.

Esta pesquisa tem como objetivo o estudo de um ambiente de distribuição de vídeo sob demanda. À medida que o serviço implantado passa por diferentes condições durante seu funcionamento, este trabalho efetua a coleta de um conjunto de dados referente ao seu desempenho. Este conjunto de dados será adequado para investigações futuras de aprendizado de máquina. A metodologia se baseia na realização de experimentos controlados com a utilização de um serviço de transmissão de vídeos com adaptação dinâmica pelo método DASH, implantado em um ambiente conteinerizado, sendo acessado por um cliente de vídeo capaz de capturar métricas de qualidade de serviço. Ao mesmo tempo que o cliente está capturando as métricas, há um gerador de carga buscando afetar, de maneira controlada, o funcionamento da plataforma. Demonstramos que a plataforma foi capaz de realizar a transmissão apropriada dos vídeos conĄgurados para o padrão DASH, ao mesmo tempo que o gerador de carga fez capaz a alteração entre os níveis de qualidade dos vídeos ao longo do experimento, resultando na diversiĄcação dos valores contidos nos conjuntos de dados obtidos.

Recent growth in cellular networks has motivated research on broadband access technologies for the support of diverse services over wireless networks. Wireless Asynchronous Transfer Mode (WATM) has been proposed as a transport solution for next generation wireless and personal communication networks and ATM Adaptation Layer 2 (AAL2) has been identified suitable for the support of low data rate and delay sensitive voice traffic generated in cellular networks. In this paper, we study the performance of AAL2 over a burst error wireless channel. Analytical expressions for performance measures of interest are derived for the Gilbert-Elliott channel and numerical results are presented to demonstrate the effect of burst errors on the AAL2 frame structure and the AAL2 performance.

ccess networks are part of the telecommunications infrastructure that connect individual subscribers to the service provider's central office (CO) over public ground. They are cost prohibitive and have consistently been regarded as the bottleneck, primarily because the ever-growing demand for higher bandwidth is beyond the supported levels of the widely deployed access technologies. As illustrated in Table 1, the typical broadband access connections at home are composed of at least three phone lines, two high-definition television (HDTV) channels, and two PC connections for Internet access [1]. Neither digital subscriber line (DSL) nor cable modem can successfully meet the bandwidth requirements of this so-called "telhome" service. Therefore, upgrading access networks with a low-cost and high-capacity solution is necessary to provide broadband access. As an inexpensive, simple and scalable technology, passive optical networks (PONs) are considered a promising solution to provide various end users with broadband access [2]. As exemplified in Fig. 1, a PON system is composed of one optical line terminal (OLT) residing in the central office (CO), one passive optical splitter deployed in the remote node (RN), and multiple optical network units (ONUs) near subscribers' locations. Intermediate powering between the OLT and the ONUs is eliminated by the use of optical fibers and passive optical splitter. Great efforts to push the PON standardization progress have been made through both the International Telecommunication Union Telecommunication Standardization Sector (ITU-T) and the IEEE Ethernet in the First Mile Task Force (IEEE EFM TF). The ratified PON standard and recommendations are tabulated in Table 2. Significant differences among diverse PON "flavors" include the supported line rates and type of bearer units. The ITU-T G.983.x Recommendation series were ratified to specify broadband PON (BPON) [3], which employs asynchronous transfer mode (ATM) cells to encapsulate the data transmitted between the OLT and ONUs. IEEE 802.3ah [4] specifies the physical and medium access control (MAC) layer characteristics of Ethernet PON (EPON). EPON carries Ethernet frames with 1 Gb/s symmetric transmission speed. The recently approved IEEE P802.3av Task Force is working on an enhanced version of EPON, 10 Gb/s EPON (10GEPON). 10GEPON upgrades the existing EPON with two solutions, a symmetric solution of 10 Gb/s upstream and 10 Gb/s downstream transmission, and an asymmetric solution of 10 Gb/s downstream and 1Gb/s upstream transmission [5]. Gigabit PON (GPON) [6] is the continuation and evolution of BPON. Besides ATM cells, GPON supports Ethernet frames as well as time-division multiplexing (TDM) units by mapping them into GPON encapsulation method (GEM) frames. The maximum transmission speed over GPON reaches 2.448 Gb/s symmetrically. BPONs, EPONs, and GPONs are also called TDM-PONs for their data transmission is divided into time slots. As shown in Fig. 1a, in the downstream from the OLT to the associated ONUs, one wavelength is employed, and TDM enables data transmission to different ONUs. This is a point-to-multipoint architecture, and data are broadcast to each ONU through the shared downstream trunk.

The mobile WiMAX system is based on the IEEE 802.16m standard which is used to develop an advanced air interface (AAI) to meet the requirements for IMT-Advanced next generation networks , which are able to provide high speed access and are used to provide a rate of broadband data for low mobility scenarios up to 1 Gbit/sec. This paper investigates the application of link adaptation techniques (AM and AMC) to the downlink for the IEEE 802.16m-depending on the mobile WiMAX networks to achieve spectral efficiency gain. Also, by use of link adaptation it is possible to combine the MIMO technique with link adaptation in order to maximize the throughput. This paper considers six various MCS for link adaptation in order to find the largest throughput improvement. The working thresholds of the SNR for the various combinations of modulation, coding and MIMO will be determined through utilizing the ITU pedestrian channel model. Therefore, through employing a system level simulation, the performance evaluation results explain that the adaptive modulation and coding (AMC) system is noticeably superior compared to the systems that utilize fixed modulation (FM) or adaptive modulation (AM) schemes with regard to the spectral efficiency.

At the present time and as a result to the recent developed technology demand for higher data rate and capacity has been increased. For the wireless networks, the combination of radio over fiber (RoF) with (XGPON) Gigabit-capable PON techniques produce a high data rate at lower cost. Thus, this paper illustrates that the performance of RoF-XGPON optical link has been analyzed for multi-channel through combining two multiplexing techniques, such as; Subcarrier Multiplexing (SCM) and Wavelength Division Multiplexing (WDM). The proposed system utilizes WDM-xGPON and SCM-XGPON architecture combined with RoF technology with 10 Gpbs data rate and (2.4, 5.8, 10 and 15) GHz radio frequency (RF), when change the optical fiber length between (10 to 80) km. The network performance is compared with various digital quadrate amplitude modulation schemes, like ; 4-QAM, 16-QAM and 64-QAM for various input power (-2, 2, and 6) dB. The performance analysis is based on the optical spectrum of transmitted and received signals for 4-channel, constellation diagram, eye diagram, bit error rate (BER), power received, and quality factor. The result explain that the WDM-XGPON-Rof performs better than SCM-XGPON-Rof for different modulation schemes. The bit error rate for WDM-XGPON less than the SCM-XGPON while the power received recorded to the WDM-XGPON greater than SCM-XGPON and the quality factor for SCM-XGPON less than the WDM-XGPON. Therefore The simulation results show that the WDM-XGPON-RoF gives better performance from SCM-XGPON-RoF. The software optisystem version 15 has been used to simulate this system

In this paper, a new Quality of Service (QoS) provisioning scheme based on centralized scheduling is proposed for mesh mode operation. The scheme is developed from the QoS mechanism of Point to Multi-Point (PMP) mode specified in 802.16 standards. A scheduling algorithm with the concept of Urgency Index is proposed for efficient bandwidth resource usage. The proposed QoS framework is implemented into simulation model to assess the effectiveness. Simulation result shows excellent QoS performance. The delay and throughput statistics obtained through simulation shows the proposed scheduler is more responsive to traffic load changes and makes efficient use of bandwidth resources. The main contribution of this work is the QoS provisioning framework in mesh mode, which fully considers the network capacity in a mesh network scenario and employs the specially designed cross-service-class Urgency Index based scheduling algorithm.

͑Doc. ID 82597͒ We propose maximum likelihood sequence estimation (MLSE) for upstream signal detection in a high-speed centralized supercontinuum broadband-lightsource (SC-BLS) wavelength-division-multiplexing passive optical network (WDM-PON). Upstream pulse carriers are produced by a SC-BLS at the central office (CO), modulated by 10 Gbit/ s upstream data at optical network units (ONUs), and finally detected by MLSE at the CO. MLSE effectively compensates the impairments from (1) asynchronous modulation of upstream pulse carriers at ONUs; and (2) chromatic dispersion (CD) in the fibers. Compared to the conventional method using alignment monitors at ONUs for upstream modulation synchronization and all-optical components for CD compensation, the proposed method features significant cost saving, lower power requirement for upstream signals, and lower operation complexity for ONUs in the SC-BLS WDM-PON.

We propose and demonstrate a WDM access network with downstream OFSK data and upstream OOK data. A simple and low-cost optical network unit is realized by re-modulating the downstream optical signal power with the upstream data; and the transmission performance is experimentally characterized.

We propose and experimentally demonstrate a novel centrally controlled protection scheme for arrayed waveguide grating-based bidirectional wavelength-division-multiplexing passive optical networks which can provide automatic traffic restoration against fiber cut between remote node and optical network unit. Compared with the previous structures, its requirements on the network resources are greatly reduced with negligible protection performance degradation.

Employment of optical frequency shift keying (OFSK) as the downstream modulation format in a WDM passive optical network is proposed. The upstream OOK transmitter at the ONU can be realised by remodulating the constant-intensity downstream OFSK signal power with the upstream data. Transmission and remodulation of 2.5 Gbit=s downstream and upstream signals were successfully demonstrated.