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Last mile

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Definitions Edit

The last mile

[r]efers generally to the transport and transmission of data communications from the demarcation point between the end user’s internal network and the carrier’s network at the customer premise to the first point of aggregation in the carrier’s network (such as a remote terminal, wireless tower location, or HFC node).[1]
refers to communications technology that bridge the transmission distance between the service provider and the customer.[2]
is the link between the middle mile and the last 100 feet to the end-user's terminal. The last mile is analogous to the local road between a larger, divided highway and a traveler’s driveway.[3]

Overview Edit

Usually referred to by the telecommunications and cable television industries, it is typically seen as an expensive challenge because "fanning out" wires and cables is a considerable physical undertaking. In countries employing the metric (as opposed to the imperial) measurement system, the phrase "last kilometre" is sometimes used.

While all components of the network play important roles in the delivery of advanced services, . . . deployment of last mile facilities . . . are often the missing link in communities that do not have access to advanced telecommunications capability. The last mile connection to the end-user can take the form of cable modem service, digital subscriber line service (DSL) or some other LEC-provided service, terrestrial wireless service, or satellite service. Some operators of last mile facilities, like cable providers, transport data entirely over facilities that they own. Others, including many terrestrial wireless providers, lease transport to regional and/or national connection points from local exchange carriers. Last mile facilities called very small aperture terminals (VSATs) may also use satellite links to transport traffic to middle mile facilities or directly to the national backbone networks.[4]

Last mile Internet service provider Edit

A last-mile Internet service provider[5] offers the network connections that link end users to the wider Internet.[6] By connecting its end-user customers to the many networks comprising the Internet backbone, an ISP provides its customers access to the end-user computers of any other ISP in the world connected to that backbone. Computer users in the United States have had nearly ubiquitous last-mile access to dial-up Internet connections of 56 to 280 Kbps since the late 1990s through telephone modems. In recent years, faster broadband connections have supplanted dial-up service for a rapidly growing number of computer users who demand faster access to the increasingly sophisticated and data-rich content and applications available on the Internet.

Broadband Edit

In broadband technology, the "last mile" refers to those components that provide broadband service to end-user devices through an intermediate point of aggregation. In most cases, the last mile connection goes from the end-user device through an intermediate point of aggregation (i.e., a remote terminal, fiber optic node, wireless tower, or other equivalent access point) to a primary IP routing entity in a centralized facility. Last mile also includes equivalent services that, solely because of close proximity between the customer and centralized facility, are routed directly to the centralized facility. The last mile will terminate at and include the initial customer-facing router or aggregation switch in the centralized facility that is utilized to deliver last mile broadband service.

A wireline broadband network provider can choose among various network architectures for its last mile grid. A telephone company can choose to deploy Optical fiber from its end office switch all the way to the home, or to the curb, or to a neighborhood node. If it brings the fiber to the curb or to a node, it can then complete the connection to the customer premise by attaching digital subscriber line (DSL) modems to the existing copper line running into the premise.

Cable companies most often use hybrid fiber-coaxial cable (HFC) technology, deploying optical fiber from the cable company’s head-end facility to a node and using coaxial cable from the node to the end user premise. The fiber to the home architecture is much more costly to deploy, but can provide substantially more bandwidth than can be provided over a fiber/DSL or HFC last mile[7] and can have its bandwidth expanded more cheaply and easily as demand grows.

According to the most recent data available from the FCC, most broadband consumers access the Internet today by cable modem or DSL. Of the 64.6 million high-speed lines in the United States as of June 30, 2006, 44.1% were cable modem, 36.4% DSL or other high-speed telephone line, 17.0% mobile wireless, 1.1% fiber-to-the-premise, 0.8% satellite, 0.5% fixed wireless, and 0.01% broadband over power line (and other lines).[8]

If a broadband network provider intends to offer multiple channel video service, it can choose between an architecture that “broadcasts” the signals of all the channels to the end-user premise (the cable company and Verizon approach) and an architecture that transmits to the end user only the particular video channel selected by the customer using her IP set-top box (the “call-up” approach used by AT&T). The “broadcast” approach requires more bandwidth.

Network providers have discretion over several other network parameters. For example, both the telephone and the cable companies have chosen to deploy asymmetric broadband networks that have far more bandwidth for the download of information to end-user customer premises than for the upload of information from end users. This architecture favors the development of applications that are one-to-many or client-server in design. Applications that would require end-user customers to deliver content as quickly as they receive it are limited by asymmetric bandwidth. Asymmetric network architecture supports the cable and telephone companies’ triple-play business plans, which focus on end users as receivers, rather than transmitters, of information. This is almost certainly consistent with current demands of most customers. If customer demand were to move toward applications and services requiring more symmetric downloading and uploading capability — perhaps as a result of heightened popularity for interactive games or peer-to-peer distribution of videos and other files — the current asymmetric architecture might constrain the growth of these applications, but it also might create market forces for entry of a third broadband provider with a more symmetric network or for the incumbents to modify their networks to meet the new demand.

A network provider can make other decisions about its last mile network that will affect the bandwidth available to end users. Whether its last mile architecture is all fiber, fiber and copper, or fiber and coaxial cable, it can choose to deploy electronics that determine the bandwidth capacity of the line into the end-user premise. In addition, it can partition the bandwidth capacity of the line into the end-user premise, reserving some portion or portions of the total bandwidth for specific applications. For example, a provider might reserve a portion of the bandwidth for its own applications or for those of an independent applications provider that pays for priority access to the end user.

Each network provider can make its own decisions about these technical parameters, subject to market constraints (though currently not subject to regulatory constraints). For example, Verizon’s fiber-to-the-home last mile architecture could potentially provide almost limitless bandwidth if all the fiber strands were “lit,” but demand cannot justify the deployment of the electronics needed for such unlimited capacity. As currently configured, Verizon’s Fios offering lights just three of the many fiber strands in the optical fiber that comes to the customer premise. These lit strands are called lasers. One of these lasers is reserved for the “broadcast” downloading of all the video channels offered in Verizon’s video service. The second laser brings 100 megabits per second (mbps) of bandwidth into the customer premise for downloading packets of all other “incoming” traffic — incoming web pages, e-mails, and other data received as part of internet access service, incoming voice packets, incoming video-on-demand programming, and incoming special services. The third laser is used for uploading packets of all outgoing traffic (associated with these internet access, voice, video-on-demand, and special virtual private network services).

Service Plans Edit

Basic residential service packages are typically available on a flat-rate basis to home computer users. ISPs may require that end users with more demanding needs, like a medium or large business, purchase a business-class or other type of premium service package.[9] In addition, end users can purchase for a premium fee access to a specialized virtual private network (“VPN”) offering a defined quality-of-service level over a reserved portion of an ISP’s network.[10]

Last-mile broadband wireline architecture can take various forms. A last-mile ISP can extend a fiber optic wireline from a backbone connection to either a neighborhood node, to the curb of a premise, or all the way to the end user’s premise. If the fiber runs only to the node or curb, the ISP can then use a cable or DSL connection for the remaining distance to the end user’s premise.[11] DSL wirelines provide a dedicated amount of bandwidth to each end user, but can transmit data up to only about three miles without the use of a repeater. Accordingly, transmission speeds can vary depending on an end user’s distance from a repeater.[12] Cable wirelines offer shared bandwidth among many customers. Thus, the transmission speed for an individual cable modem customer can vary with the number of customers who are using the network simultaneously.[13]

Last-mile wireless networks using wireless fidelity (“Wi-Fi”) or worldwide interoperability for microwave access (“Wi MAX”) technologies can be set up by deploying multiple antennas on street lights, traffic signals, and buildings, so that multiple wireless hotspots overlap each other to form a continuous “mesh” network of wireless signals. An initial connection to a backbone network also must be made in order to provide access to the wider Internet.[14] Several major telecommunications companies also offer mobile wireless Internet services over their wireless phone networks.[15] Three satellite providers offer broadband Internet service via satellite.[16] An end user must have a computer or other device that is configured for wireless Internet use to access these networks. In addition, there are now over forty deployments of broadband over power line technologies in the United States, most of which are in trial stages.[17]

Today’s last-mile networks generally are partitioned asymmetrically to provide more bandwidth for data traveling from an ISP’s facilities to the end user’s computer (“downstream”) than in the other direction (“upstream”). Typically, this is done because end users request much more data from other server computers than they, themselves, send out.[18] As a result, asymmetric architecture may constrain content and applications that require the end user simultaneously to send and receive content at the same speeds and volumes, such as two-way video transmissions.[19] Also, ISPs have the technical capability to reserve portions of last-mile bandwidth for specific applications.[20]

References Edit

  1. The Broadband Availability Gap, OBI Technical Paper No 1, Glossary, at 133 (full-text).
  2. Communications Networks: Outcome-Based Measures Would Assist DHS in Assessing Effectiveness of Cybersecurity Efforts, at 4 n.7.
  3. Deployment of Advanced Telecommunications Capability: Second Report, at 11.
  4. Id., at 19.
  5. Networks that connect end users to the broader Internet are generally referred to as “last-mile” ISPs. Networks that transmit data from a content or applications provider’s computer server(s) to the broader Internet are sometimes referred to as “first-mile” ISPs.
  6. Today, major last-mile wireline broadband ISPs include: AT&T, Comcast, Covad, Cox Communications, and Verizon. Major wireless broadband ISPs include: AT&T, Sprint Nextel, T-Mobile, and Verizon Wireless.
  7. The actual amount of bandwidth provided by fiber, fiber/copper, or HFC will depend on a number of factors, including how much of the optical fiber is “lit” by electronics and the type of modems used.
  8. FCC, High-speed Services for Internet Access: Status as of June 30, 2006, at 5, table 1 (2007).
  9. Last-mile access for large enterprise customers, particularly those with multiple locations, typically involves the use of dedicated, high-capacity facilities often referred to as special access or dedicated access services. See In re Special Access Rates for Price Cap Local Exch. Carriers, 20 FCC Rcd 1994, 1995-96 (2005) (order and notice of proposed rulemaking.
  10. See, e.g., Charles B. Goldfarb, Access to Broadband Networks: Congressional Research Services Report to Congress 10-11 (2006).
  11. Id. at 9-11.
  12. See generally FCC, FCC Consumer Facts: Broadband Access for Consumers.
  13. See generally id.
  14. Wireless broadband providers that do not have their own facilities connecting their transmitters (e.g., cell towers) to their switches typically purchase special access services from an incumbent local exchange carrier or other provider of such services. See Special Access NPRM, 20 FCC Rcd at 1995-96.
  15. Goldfarb, at 10.
  16. Id. at 10-11.
  17. Id. at 11-12.
  18. Id. at 4, 9.
  19. Id. at 9.
  20. For example, Verizon reserves one fiber of its downstream fiber-to-the-home service specifically for the company’s video service, while a separate fiber carries all other incoming traffic. Id. at 10. AT&T reserves 19 of 25 megabits of downstream end-user bandwidth specifically for the company’s video service. Id. at 11. AT&T customers can purchase between 1.5 and 6 Mbps of the remaining downstream bandwidth for Internet access and voice services. Id.

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