Hybrid Fiber Coax Research Articles

Implementation of Both High-Speed Transmission and Quality of System for Internet Protocol Multicasting Services

The paper introduces both high-speed transmission and quality of system to offer the Internet services on a HFC (Hybrid Fiber Coaxial) network. This utilizes modulating the phase and the amplitude to the signal of the IPMS (Internet Protocol Multicasting Service). An IP-cable transmitter, IP-cable modem, and IP-cable management servers that support 30-Mbps IPMS on the HFC were developed. The system provides a 21Mbps HDTV transporting stream on a cable TV network. It can sustain a clear screen for a long time.

Datacab: a geographical‐information‐system‐based expert system for the design of cable networks

Abstract: Telecommunication networks have evolved over time as a result of technological advances, and network topologies and equipment have become increasingly complex. Expert systems are being successfully applied to the management of telecommunication networks. However, applying expert systems to network design is another especially beneficial yet still not very common approach. In this paper we propose a rule‐based expert system called Datacab. Datacab was developed at Enditel Endesa in collaboration with the Electronic Technology Department of the University of Seville, for the automatic design of hybrid fibre coax (HFC) cable networks. Using data from a geographical information system as input, it automatically generates viable HFC network designs.

BROADBAND ACCESS TECHNOLOGIES EVALUATION TOOL (BATET)

The goal of this paper is to identify all the essential costs of building broadband access networks, and then to comparise different technologies in various scenarios. Different market segments (Scenarios) have different geographical characteristics and will require different amounts of access bandwidth. These different market segments will be served by alternative access technologies that minimise overall costs. In order to do this, we have developed a model framework and an evaluation tool. To measure the attractiveness of several broadband access technologies, the proposed tool compares the costs, revenues, NPV, IRR, payback periods etc for 3 scenarios. The paper presents a techno‐economic analysis of 8 broadband technologies for access networks: digital subscriber line (DSL), hybrid fibre coax (HFC), power line communications (PLC), fibre to the home (FTTH), fibre to the curb (FTTC), fibre to the cabinet (FTTCab), and wireless alternatives such as WiMAX and satellite.

Piecewise Patching for Time-shifted TV Over HFC Networks

In video-on-demand (VOD) systems, a number of sophisticated architectures have been proposed to provide instantaneous services through the use of multicast technology. Most of the architectures focus on minimizing bandwidth requirements under the assumption that clients play from beginning to end, but this assumption is not suitable for time-shifted TV. Moreover, they have been proposed on an IP network, and failed to make full use of the broadcasting property of hybrid fiber coaxial (HFC) network. In this paper, we propose a novel delivery scheme, named as piecewise patching (PP), to tackle these problems. The piecewise patching scheme provides the video data for the users in a piecewise mode instead of a whole patching stream which includes all missing data. The former user can utilize the data from the later users' patching stream whose playback time is in advance of the former user's patching stream. In the proposed scheme, each client receives the data simultaneously from arbitrary channels which broadcast the same content. Simulation results show that the proposed scheme improves the performance of time-shift TV service significantly in terms of total server bandwidth requirement.

HFC Access Network Design for Switched Broadcast TV Services

The hybrid fiber coax (HFC) is a modern broadband access network, providing advanced interactive services such as Internet access, digital interactive television and cable telephony. The edge costs dominate the cost of launching new services, at the time of deployment (CapEx) as well as for maintenance (OpEx). Therefore next-generation edge devices aim at the convergence of these services and their platforms into a single multi-service infrastructure, thus sharing resources and bandwidth. The focus of this paper is on the HFC access network design for bandwidth-intensive TV services, bringing standard as well as switched broadcast technologies into play. Standard broadcast TV service deployments, offered through the digital video broadcast (DVB) platform, require low installation costs, but the bandwidth consumption increases linearly with the number of available TV channels, even for very unpopular channels. Switched broadcast TV channels, offered on the (Euro-) DOCSIS platform together with other interactive unicast services such as video on demand, are only streamed to a node on the HFC access network if they are requested locally, thus limiting bandwidth consumption for less popular channels. We present an access network design tool, based on an analytical TV traffic model, minimizing the installation cost on the edge devices and study the influence of the most important traffic and content parameters.

Adaptive collision-resolution algorithm and traffic-scheduling mechanism for DOCSIS-based HFC networks

A scheme is proposed that provides high QoS and collision-free data transmission in hybrid fiber-coax (HFC) networks. This scheme ensures effective medium access and creates an effective traffic-scheduling mechanism. To enhance the performance of the proposed scheme, a novel methodology has been adopted. Experiments have been performed to measure the effectiveness of the priority system that use the mean access delay, throughput, and channel utilization as figures of merit.

Design of Optical Access Systems using Computer Modeling

We present numerical techniques that allow efficient modeling of the transport of broadband services over fiber-optic links in access networks using various technologies. Application examples of Hybrid Fiber Coax (HFC), Radio-over-Fiber (RoF) systems and 10-Gb/s Ethernet transport over multimode fiber are provided to demonstrate the value of simulation during the R&D and deployment phases of product introduction.

HFC and PON-FTTH networks using higher SBS threshold singlemode optical fibre

Measurements showing improved RF video transmission are presented over a test-bed which replicates parts of a commercial hybrid fibre-coax (HFC) network using an optical fibre specifically engineered for fibre-to-the-home (FTTH) featuring +3 dB higher stimulated Brillouin scattering (SBS) threshold. Results validate improved system performance and increased reach for use in PON and FTTH architectures.

The behavior of TCP over DOCSIS-based CATV networks

This paper studies the impact of the data-over-cable service interface specification (DOCSIS) media-access control (MAC) protocol on the performance of the transmission control protocol (TCP) in hybrid fiber coax (HFC) broadband access networks. We find that the asymmetry ratio expressed in existing work cannot adequately explain the behavior of TCP in DOCSIS-based networks. To better capture the effect of DOCSIS on TCP, we express the asymmetry ratio (denoted by eta) in another way (denoted by k), considering the time-division multiple-access-like MAC layer operation of DOCSIS. When eta>1, TCP behaves as in a symmetric network, and when etales1, the system acts as in an asymmetric network, and the performance of TCP degrades. We find that the number of simultaneous TCP transfers significantly affects the asymmetry ratio. When the number of active transfers is below two times the maximum number of pending requests in a transmission period, the value of eta is larger than one, regardless of the value of k. However, when the number of active transfers becomes very large, the effect of DOCSIS on TCP becomes negligible, and the asymmetry ratio is determined by the bandwidth ratio of the channels times the length ratio of data and acknowledgement packets. Based on eta, we develop the round-trip delay of sending a data packet for both one-way and two-way transfers, and discuss the buffer requirement at the head end. The accuracy of the analytical model is validated by ns-2 simulations. The analytical result can provide useful guidelines in the design of slot allocation or scheduling mechanisms for any DOCSIS-based broadband access networks, including the emerging IEEE 802.16 WiMAX networks

Broadband Technologies in Australia 1993–98: Developing the Social Shaping of Technology Approach 1

Abstract The development and deployment of technologies for delivering broadband services to homes in Australia are investigated using the ‘social shaping of technology’ (SST) approach. The focus is on the period from 1993 to 1998 when there were five main technological options for delivering residential broadband services: ‘hybrid’ fibre coaxial (HFC) cable; direct broadcast satellite (DBS); multipoint microwave distribution systems (MDS); ‘Integrated Services Digital Network’ (ISDN); and ‘Asymmetric Digital Subscriber Line’ (ADSL). The main broadband services planned for delivery to homes over this period were pay television and fast Internet access. A sequence of snapshots of sociotechnical relationships at critical times during the study period, termed ‘sociotechnological configurations’, is used to track the evolutionary pathway of the broadband technologies. The mapping technique assists in identifying key features and explaining the driving factors of the pathway, including why HFC cable emerged as the predominant technology, and two competing HFC cable networks were rolled out in capital cities at an additional cost of over $2 billion when a single network would have had ample capacity.

Design of Optical Content Distribution Networks for Video on Demand Services

This paper presents the design of optical content distribution networks for video on demand (VoD) services. The proposed Ethernet-based WDM network architecture is decentralized and consists of independent regional ring networks with locally deployed video servers. Based on an Integer Linear Programming (ILP) model, a network design tool, minimizing the total installation cost for optical network equipment on the metro and the Hybrid Fiber Coax (HFC) access network, has been developed. Unicast as well as broadcast VoD services are taken into account. The influence of different parameters in our traffic and content models on the network design is studied.

DOCSIS Performance Analysis Under High Traffic Conditions in the HFC Networks

Hybrid Fiber Coaxial (HFC) networks provide a wide bandwidth and represent the solution of choice for many residential networks nowadays. The Data Over Cable Service Interface Specification (DOCSIS) protocol is an important standard for HFC networks and is supported by the majority of current vendors. This protocol uses the Truncated Binary Exponential Back-off (TBEB) algorithm to resolve collisions within the network by means of a back-off window. However, the performance of this algorithm tends to deteriorate when the network load is high. Consequently, the present study develops a novel mathematical model for the TBEB algorithm and then uses this model to identify the window size which yields the optimal system throughput and minimum delay time under high traffic conditions. The present numerical results confirm that the performance is improved when the window settings identified from the developed model are applied.

Resource planning and bandwidth allocation in hybrid fiber–coax residential networks

The introduction of new high bandwidth services such as video-on-demand by cable operators will put a strain on existing resources. It is important for cable operators to know how many resources to commit to the network to satisfy customer demands. In this paper, we develop models of voice and video traffic to determine the effect of demand growth on hybrid fiber–coax networks. We obtain a set of guidelines that network operators can use to build out their networks in response to increased demand. We begin with one type of traffic and generalize to an arbitrary number of high-bandwidth constant bit rate (CBR) like services to obtain service blocking probabilities. We consider the effect of supporting variable bit rate (VBR) packet-switched traffic in addition to CBR services. These computations help us to determine how cable networks would function under various conditions (i.e., low, medium, and heavy loads). We also consider how the growth rate of the popularity of such services would change over time, and how this impacts network planning. Our findings will help cable operators estimate how much bandwidth they need to provision for a given traffic growth model and connection blocking requirement.

VoIP services with embedded CAC over cable modem systems

VoIP (voice over Internet protocol) technology has rapidly been growing up recently, which transmits voice packets by using the user datagram protocol (UDP). VoIP quality is difficult to expect because it is hard to predict the influence of packet delay, packet lose, packet error, etc. This paper proposes an embedded call admission control (CAC) mechanism by applying real-time transfer protocol (RTP) and the real-time control protocol (RTCP) for VoIP services over hybrid fiber/coaxial (HFC) networks. The proposed CAC mechanism is evaluated by the impact of the various traffic load in cable modem termination system (CMTS), which estimates how VoIP quality satisfies the user's requirements under different constrains on cable networks. We discuss VoIP CAC mechanism for the upstream channel according to the data over cable service interface specifications (DOCSIS) version 1.1 and particularly consider G.723.1 voice packets at the transmission rate of 6.3 kbps. The performance measurement of the proposed embedded CAC mechanism is obtained by simulation experiments under various network constrains, which includes throughput, packet dropping ratio and call blocking ratio. Obviously this paper provides an efficiency and fast method for CMTS to decide how many calls can be accepted.

Scheduling Delay Minimization for Non-UGS Data in Multi-Channel HFC Network

SUMMARY The multi-channel Hybrid Fiber Coaxial (HFC) network is essentially a shared medium with multi-channels. Its operation requires the use of a scheduling algorithm to manage the data transmission within each channel. The Data-Over-Cable Service Interface Specification (DOCSIS) protocol is an important standard for HFC networks. Since this protocol does not explicitly specify the scheduling algorithm to be used, many alternative algorithms have been proposed. However, none of these algorithms are applicable to the scheduling of non-Unsolicited Grant Service (UGS) data in multi-channel HFC networks. Accordingly, the present study develops a multi-channel scheduling algorithm which optimizes the scheduling delay time of each transmitted non-UGS request. This algorithm manages the amount of data transmission in each upstream channel according to the overall network load and the bandwidth available in each channel. This study constructs a mathematical model of the algorithm and then uses this model as the basis for a series of simulations in which the performance of the scheduling algorithm is evaluated.

Call for Papers: Convergence

Call for Papers: Convergence Guest Editors: Thomas E. Darcie, University of Victoria Robert Doverspike, AT&T Martin Zirngibl, Lucent Technologies Coordinating Associate Editor: Steven K. Korotky, Lucent Technologies Submission Deadline: 1 January 2006 The Journal of Optical Networking (JON) invites submissions to a special issue on Convergence. Convergence has become a popular theme in telecommunications, one that has broad implications across all segments of the industry. Continual evolution of technology and applications continues to erase lines between traditionally separate lines of business, with dramatic consequences for vendors, service providers, and consumers. Spectacular advances in all layers of optical networking-leading to abundant, dynamic, cost-effective, and reliable wide-area and local-area connections-have been essential drivers of this evolution. As services and networks continue to evolve towards some notion of convergence, the continued role of optical networks must be explored. One vision of convergence renders all information in a common packet (especially IP) format. This vision is driven by the proliferation of data services. For example, time-division multiplexed (TDM) voice becomes VoIP. Analog cable-television signals become MPEG bits streamed to digital set-top boxes. T1 or OC-N private lines migrate to Ethernet virtual private networks (VPNs). All these packets coexist peacefully within a single packet-routing methodology built on an optical transport layer that combines the flexibility and cost of data networks with telecom-grade reliability. While this vision is appealing in its simplicity and shared widely, specifics of implementation raise many challenges and differences of opinion. For example, many seek to expand the role of Ethernet in these transport networks, while massive efforts are underway to make traditional TDM networks more data friendly within an evolved but backward-compatible SDH/SONET (synchronous digital hierarchy and synchronous optical network) multiplexing hierarchy. From this common underlying theme follow many specific instantiations. Examples include the convergence at the physical, logical, and operational levels of voice and data, video and data, private-line and virtual private-line, fixed and mobile, and local and long-haul services. These trends have many consequences for consumers, vendors, and carriers. Faced with large volumes of low-margin data traffic mixed with traditional voice services, the need for capital conservation and operational efficiency drives carriers away from today's separate overlay networks for each service and towards "converged" platforms. For example, cable operators require transport of multiple services over both hybrid fiber coax (HFC) and DWDM transport technologies. Local carriers seek an economical architecture to deliver integrated services on optically enabled broadband-access networks. Services over wireless-access networks must coexist with those from wired networks. In each case, convergence of networks and services inspires an important set of questions and challenges, driven by the need for low cost, operational efficiency, service performance requirements, and optical transport technology options. This Feature Issue explores the various interpretations and implications of network convergence pertinent to optical networking. How does convergence affect the evolution of optical transport-layer and control approaches? Are the implied directions consistent with research vision for optical networks? Substantial challenges remain. Papers are solicited across the broad spectrum of interests. These include, but are not limited to: Architecture, design and performance of optical wide-area-network (WAN), metro, and access networks Integration strategies for multiservice transport platforms Access methods that bridge traditional and emerging services Network signaling and control methodologies All-optical packet routing and switching techniques Manuscript Submission To submit to this special issue, follow the normal procedure for submission to JON, indicating "Convergence feature" in the "Comments" field of the online submission form. For all other questions relating to this feature issue, please send an e-mail to jon@osa.org, subject line "Convergence." Additional information can be found on the JON website: http://www.osa-jon.org/submission/. Submission Deadline: 1 January 2006

Network architecture and medium access control for deploying third generation (3G) wireless systems over CATV networks

We propose a novel and cost-effective approach for the deployment of third generation (3G) wireless systems over hybrid fiber coaxial (HFC) CATV networks. The main goal is to facilitate 3G deployment over the existing CATV plant and reduce the large cost required for building a dedicated last mile infrastructure for 3G access networks. Our proposal reduces the last mile cost by sharing the existing CATV network and using the standard equipment and protocols of data-over-cable systems interface specifications (DOCSIS). This allows rapid deployment of 3G wireless systems, facilitates convergence of wireless and wireline networks and paves the way towards all IP wireless networks. Enhancements to the DOCSIS medium access control (MAC) protocol must be implemented in order to support Quality of Service (QoS) guarantees for 3G data and signaling traffic. This paper presents the proposed 3G over CATV network architecture and DOCSIS medium access control (MAC) enhancements for enabling the support of QoS guarantees for 3G data and signaling traffic. The proposed MAC enhancements can reduce the access delay for delay-sensitive traffic by 30 to 40% over existing DOCSIS MAC without compromising QoS guarantees for other traffic classes, or the DOCSIS channel utilization. Copyright © 2004 John Wiley & Sons, Ltd.

Analysis and Modeling of Traffic on a Hybrid Fiber-Coax Network

This paper presents the study carried out on the data traffic collected on the network of a cable operator based on hybrid fiber-coax technology, and the subsequent simulation model developed to predict the bandwidth requirements of the network channels. The paper starts with the analysis of the traffic measurements, taken over two periods of time in one year, on all the network's channels. This analysis identifies the main characteristics of the traffic, as well as some relationships between network parameters and their persistence over time. The paper proceeds to present the development of a simulation model, which represents the cable network. This model is built from the results of the traffic analysis and network parameters. The major challenge of this model is to predict the traffic on each channel of the cable network, related to parameters of the network configuration, such as the number of assigned subscribers to the channel and the time of day. To reach this goal, the simulation model has been developed with a modular structure, which gives it flexibility to adapt to changes in the network. The process followed involves the establishment of a traffic model, a system model, and finally, the validation of the results.

Modeling and simulation of data transmission on a hybrid fiber coax cable network

This paper describes the steps followed in the development, simulation, and later validation of a model for a cable network based on hybrid fiber-coax (HFC) technology, used for data transmission. This work presents a representation of a communication system which has been growing dramatically over recent years and will continue to do so in the near future. The modeling process is based on the analysis of measurements of a cable operator, establishing a direct relationship between model parameters and network characteristics. The modeling technique produces a scalable model capable of simulating the evolution of the real cable network.

Adaptive Slot Allocation in DOCSIS-Based CATV Networks

This paper proposes an adaptive slot allocation mechanism to improve the performance of Transmission Control Protocol (TCP) in DOCSIS-based hybrid fiber coaxial (HFC) networks. The proposed mechanism is comprised of two parts: fast request transmission (FRT) and long packet deferment (LPD). FRT is designed to handle TCP transfers, while LDP targets transfers. Here one-way transfers means all active cable modems perform downloading; while two-way transfers indicates some perform downloading and some perform uploading. We analyze the proposed mechanism and conduct simulations using network simulator ns-2 to evaluate the performance of our mechanism. The results show that the proposed mechanism has better performance in terms of aggregate downstream throughput, access delay, and required buffer size, as compared to the original control mechanism of DOCSIS.