[Broadband Cable Access Networks Pdf Download
Betty Neyhart
In telecommunications, cable Internet access, shortened to cable Internet, is a form of broadband internet access which uses the same infrastructure as cable television. Like digital subscriber line and fiber to the premises services, cable Internet access provides network edge connectivity (last mile access) from the Internet service provider to an end user. It is integrated into the cable television infrastructure analogously to DSL which uses the existing telephone network. Cable TV networks and telecommunications networks are the two predominant forms of residential Internet access. Recently, both have seen increased competition from fiber deployments, wireless, mobile networks and satellite internet access.
Broadband cable Internet access requires a cable modem at the customer's premises and a cable modem termination system (CMTS) at a cable operator facility, typically a cable television headend. The two are connected via coaxial cable to a hybrid fibre-coaxial (HFC) network. While access networks are referred to as last-mile technologies, cable Internet systems can typically operate where the distance between the modem and the termination system is up to 160 kilometres (99 mi). If the HFC network is large, the cable modem termination system can be grouped into hubs for efficient management. Several standards have been used for cable internet, but the most common is DOCSIS.[1]
A cable modem at the customer is connected via coaxial cable to an optical node, and thus into an HFC network. An optical node serves many modems as the modems are connected with coaxial cable to a coaxial cable "trunk" via distribution "taps" on the trunk, which then connects to the node, possibly using amplifiers along the trunk. The optical node converts the Radiofrequency (RF) signal in the coaxial cable trunk into light pulses to be sent through optical fibers in the HFC network. At the other end of the network, an optics platform or headend platform converts the light pulses into RF signals in coaxial cables again using transmitter and receiver modules,[2][3] and the cable modem termination system (CMTS) connects to these coaxial cables. An example of an optics platform is the Arris CH3000. There are two coaxial cables at the CMTS for each node: one for the downstream (download speed signal), and the other for the upstream (upload speed signal).[3] The CMTS then connects to the ISP's IP (Internet Protocol) network.[4]
Downstream, the direction toward the user, bit rates can be as high as 1 Gbit/s.[5] Upstream traffic, originating at the user, ranges from 384 kbit/s to more than 50 Mbit/s, although maximum effective range seems to be unknown. One downstream channel can handle hundreds of cable modems. As the system grows, the CMTS can be upgraded with more downstream and upstream ports, and grouped into hub CMTSs for efficient management.
Most Data Over Cable Service Interface Specification (DOCSIS) cable modems restrict upload and download rates, with customizable limits. These limits are set in configuration files which are downloaded to the modem using the Trivial File Transfer Protocol, when the modem first establishes a connection to the provider's equipment.[6] Some users [specify] have attempted to override the bandwidth cap and gain access to the full bandwidth of the system by uploading their own configuration file to the cable modem - a process called uncapping.
In most residential broadband technologies, such as cable Internet, DSL, satellite internet, or wireless broadband, a population of users share the available bandwidth. Some technologies share only their core network, while some including cable internet and passive optical network (PON) also share the access network. This arrangement allows the network operator to take advantage of statistical multiplexing, a bandwidth sharing technique which is employed to distribute bandwidth fairly, in order to provide an adequate level of service at an acceptable price. However, the operator has to monitor usage patterns and scale the network appropriately, to ensure that customers receive adequate service even during peak-usage times. If the network operator does not provide enough bandwidth for a particular neighborhood, the connection would become saturated and speeds would drop if many people are using the service at the same time, or drop out completely. Operators have been known to use a bandwidth cap, or other bandwidth throttling technique; users' download speed is limited during peak times, if they have downloaded a large amount of data that day.[7]
Coaxial cable networks have been widely deployed to distribute television services using broadcasting technology. This infrastructure has been enhanced and developed into a Hybrid Fibre Coax (HFC) architecture along with the introduction of a return channel. The industry is now deploying digital television services, high-speed data services, Internet Protocol (IP) voice and other time-critical multimedia services across these broadband cable telecommunication network technologies.
These services are delivered using the DOCSIS and IPCablecom protocols. DOCSIS is a data communication protocol for the transparent transmission of IP traffic across the HFC infrastructure. IPCablecom has been developed to deliver telephony and other Quality of Service (QoS) enhanced, secure, IP multimedia, time critical communications services, using packetized data transmission technology on a HFC data network utilizing the DOCSIS protocol.
The ETSI specifications are consistent to the extent possible with the CableLabs set of specifications and with deliverables published by the Society of Cable Telecommunications Engineers (SCTE). In many of its activities TC CABLE leverages close relationships with SCTE, CENELEC and ITU-T.
ETSI is hosting standards for the core technology components and communication platforms deployed in HFC networks such as DOCSIS. Starting with the first generation [ES 201 488 series], DOCSIS provides an IP-based data communication interface that today is connecting millions of homes throughout the world. Further DOCSIS generations such as ES 202 488 and EN 302 878 series added advanced features including the ability to bond multiple channels together and support for IP version 6.
TC CABLE achieved another milestone on standards for broadband cable network technology with the publication of a multi-part specification [ES 203 811 series] for the fourth-generation transmission systems for interactive cable television services (IP cable modem). The latest version 4.0 of DOCSIS became an ETSI Standard (ES). The series of standards spans the DOCSIS 4.0 physical layer [ES 203 811-2]; MAC and upper layer protocols [ES 203 811-3]; cable modem operations support system interface [ES 203 811-4]; converged cable access platform operations support system interface [ES 203 811-5]; and security [ES 203 811-6] aspects.
An ongoing focus of TC CABLE is work on energy management for cable networks. A European Norm [EN 305 200-4-4] that specifies the requirements for a global KPIs for energy management (designated KPI) was published and a revision is planned.
Today, Cisco announced the availability of its Infinite Broadband solution, which uses Remote PHY technology to overcome the limitations of analog fiber and break through the HFC bottleneck. In its most basic form, Remote PHY unlocks major bandwidth increases in existing access networks, allowing cable operators to transform their infrastructures to simpler all digital networks, reduce space and power requirements in the hub, and enable higher bandwidth for each subscriber.
To help facilitate better interoperability among different vendors participating in the OpenRPD ecosystem, Cisco has launched a program to allow RPD vendors to test their interoperability with the Cisco cBR-8 Remote PHY core. This testing will be conducted at a third-party industry lab and will follow specific acceptance testing plans. Ultimately, this work will accelerate time-to-market of Remote PHY architectures. Among the companies that have committed to participate in the initial rounds of testing are VECTOR Technologies, BKtel networks, and Teleste.
Access networks are the communication networks that connect end-user devices, such as computers, smartphones and tablets, to a wide area network (WAN), such as the internet. Access networks provide the connection to business services, including cloud-based storage, video conferencing and software-as-a-service platforms. These services are only accessible through reliable and high-speed connections, making the access network an essential component of modern enterprise infrastructure. Similarly, consumers rely on access networks for broadband internet access, voice over IP (VoIP), cable television, video streaming and mobile device connectivity.
Access networks may be wired, wireless or a combination of both. Wired access networks use cables such as copper wires or fiber optics that run through the ground or along power lines, while wireless access networks use radio waves or microwaves. Hybrid access networks combine both wired and wireless technologies for increased reliability and speed.
Telecommunications companies and internet service providers (ISPs) usually own access networks and invest significant resources to deploy and maintain them. To meet the growing demand for online and cloud-based services, these companies must frequently upgrade and expand their infrastructure, both for access networks and the core network, which connects one provider to another.
In some cases, businesses or municipalities may choose to build their own access networks. This is often done in areas where existing telecommunications infrastructure is insufficient or unavailable, or when a business requires greater control over network performance and security or purpose-built infrastructure to meet specific needs. For municipalities, a private network can provide its own internet access to residents and can support smart city applications and services.
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