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Broadband Solutions for Residential Customers - HOME NETWORKING, BROADBAND APPLICATIONS, BROADBAND ACCESS SOLUTIONS, Digital Subscriber Line, Cable Access, Broadband Wireless Access, TRENDS

data services dsl networks

Mariana Hentea
Southwestern Oklahoma State University, USA

HOME NETWORKING

The term “home networking” implies that electronic network devices work together and communicate amongst themselves. These devices are classified in three categories: appliances, electronics and computers. Home networks include home theater, home office, small office home office (SOHO), intelligent appliances, smart objects, telecommunications products and services, home controls for security, heating/cooling, lighting and so forth. The suite of applications on each device, including the number of connected devices, is specific to each home. The home network configurations are challenges, besides the unpredictable problems that could be higher compared to a traditional business environment. These are important issues that have to be considered by developers supporting home networking infrastructure. In addition, home networks have to operate in an automatically configured plug-and-play mode. Home networks support a diverse suite of applications and services discussed next.

BROADBAND APPLICATIONS

Home networks carry phone conversations, TV programs and MP3 music programs, link computers and peripherals, electronic mail (e-mail), distribute data and entertainment programs, Internet access, remote interactive services and control of home appliances, lights, temperature and so forth. The most important remote interactive services include remote metering, home shopping, medical support, financial transactions, interactive TV, video telephony, online games, voice-over Internet Protocol (VoIP) and so forth. Home applications based on multimedia require Internet connections and higher data transfer rates. For example, video programs compressed to MPEG-2 standards require a 2-4 Mbps transfer rate; DVD video requires 3-8 Mbps; and high-definition TV requires 19 Mbps. Since the existing phone line connected to a modem does not support data rates higher than 56 Kbps, rather than installing a modem for each computer, the high-speed connection may be provided by a single access point called broadband access. Broadband access provides information and communication services to end users with high-bandwidth capabilities. The next section provides an overview of broadband access solutions.

BROADBAND ACCESS SOLUTIONS

The circuit between a business or home and the local telephone company’s end office is called a local loop. Originally, local-loop service carried only telephone service to subscribers. But today, several local-loop connection options are available from carriers. These include dial-up circuits, Integrated Services Digital Network (ISDN) and broadband. “Last mile” refers to the telecommunication technology that connects a subscriber’s home directly to the cable or telephone company. Broadband transmission is a form of data transmission in which a single medium can carry several channels at once. The carrying capacity medium is divided into a number of subchannels; each subchannel transports traffic such as video, low-speed data, high-speed data and voice (Stamper & Case, 2003). The broadband access options include Digital Subscriber Line (DSL), cable modems, broadband integrated services digital network (B-ISDN) line, broadband power line and broadband wireless, with a data rate varying from hundreds of Kbps to tens of Mbps.

Digital Subscriber Line

DSL is a technique for transferring data over regular phone lines by using a frequency different from traditional voice calls or analog modem traffic over the phone wires. DSL requires connection to a central telephone office, usually less than 20,000 feet. DSL lines carry voice, video and data, and DSL service provides transmission rates to maximum 55 Mbps, which is faster than analog modems and ISDN networks. In addition to high-speed Internet access, DSL provides other services, such as second telephone line on the same pair of wires, specific broadband services, video and audio on demand. The priority between these services depends on the users and geographical area. For example, Asian users demand video services, while North American telephone companies use it for Internet access service.

Globally, the DSL market reached 63.8 million subscribers by March 2003, and future growth is expected to reach 200 million subscribers—almost 20% of all phone lines—by the end of 2005 (DSL Forum Report, 2003). xDSL refers to all types of DSL technologies, classified into two main categories: symmetric (upstream and downstream data rates are equal) and asymmetric (upstream and downstream data rates are different). DSL services include asymmetric DSL (ADSL), rate-adaptive DSL (RADSL), high data-rate DSL (HDSL), symmetric DSL (SDSL), symmetric high data-rate DSL (SHDSL) and very high data-rate DSL (VDSL) with data rates scaling with the distance and specific to each technology. For example, ADSL technology supports downstream data rates from 1.5 Mbps to 9 Mbps and upstream data rates up to 1 Mbps. VDSL technology supports downstream rates up to 55 Mbps. Also, VDSL provides bandwidth performance equal to the optical fiber, but only over distances less than 1,500 meters. SDSL technology provides data rates up to 3 Mbps. SHDSL supports adaptive symmetrical data rates from 192 Kbps to 2.31 Mbps with increments of 8 Kbps on single pair of wire or 384 Kbps to 4.6 Mbps with increments of 16 Kbps on dual pair of wire. SDSL has been developed as a proprietary protocol in North America, but it is now moving to an international standard called G.SHDSL or G.991.2. This is the first technology developed as an international standard by the International Telecommunications Union (ITU). It incorporates features of other DSL technologies and transports T1, E1, ISDN, ATM and IP signals. ADSL service is more popular in North America, whereas SDSL service is being used as a generic term in Europe to describe the G.SHDSL standard of February 2001.

Cable Access

Cable access is a form of broadband access using a cable modem attached to a cable TV line to transfer data with maximum downstream rates of 40 Mbps and upstream rates of 320 Kbps to 10 Mbps. Cable services include Internet access, telephony, interactive media, video on demand and distance learning. Networks built using Hybrid Fiber-Coax (HFC) technologies can transmit analog and digital services simultaneously. The central office transmits signals to fiber nodes via fiber-optic cables and feeders. The fiber node distributes the signals over coaxial cable, amplifiers and taps out to business users and customer service areas that consist of 500 to 2,000 home networks with a data rate up to 40 Mbps. Cable companies gained lots of users in the United States (U.S.) and expect 24.3 million cable modems installed by the end of 2004, which represents an increase from 1.2 million cable modems installed in 1998. Cable services are limited by head-end and fiber-optic installation. HFC is one possible implementation of a passive optical network (PON). Fiber to the curb can provide higher bit rates; roughly 40 times the typical rates with a cable modem (Cherry, 2003).

Fiber-optic cable is used by telephone companies in place of long-distance wires and increasingly by private companies in implementing local data communication networks. Although the time for the massive introduction of fiber is quite uncertain, the perseverance of the idea of fiber in the loop (FITL) lies in the fact that the costs of optics are coming down, bandwidth demand is going up and optical networking spreads in metropolitan areas. Because the data over cable travels on a shared loop, customers see data transfer rates drop as more users gain service access.

Broadband Wireless Access

Wire line solutions did not secure telecommunication operators, because costs and returns on investments are not scalable with the number of attached users. Although various broadband access solutions (like DSL, cable, FITL) were implemented, the killer application video on demand disappeared for the benefit of less-demanding Web access. Unsatisfactory progress of wire line solutions pushed alternative solutions based on wireless technologies. Broadband wireless access (BWA) has emerged as a technology, which is profitable. Broadband wireless access is part of wireless local loop (WLL), radio local loop (RLL) and fixed wireless access (FWA).

WLL systems are based on a range of radio technologies such as satellite, cellular/cordless and many narrowband and broadband technologies. One WLL approach is placing an antenna on a utility pole (or another structure) in a neighborhood. Each antenna is capable of serving up to 2,000 homes. Subscribers must have an 18-inch antenna installed on their homes.

RLL systems connect mobile terminals at least in highly crowded areas to the point of presence of the operator’s cable-based Asynchronous Transfer Mode (ATM) backbone network.

FWA systems support wireless high-speed Internet access and voice services to fixed or mobile residential customers located within the reach of an access point or base transceiver station. FWA systems promise rapid development, high scalability and low maintenance.

TRENDS

The two emerging broadband access technologies include fiber access optimized for clusters of business customers and Wireless LAN (WLAN) to provide service to small business and home subscribers. Use of wireless, DSL and cable for broadband access has become increasingly prevalent in metropolitan areas.

Vast geographic regions exist where broadband services are either prohibitively expensive or simply unavailable at any price. Several alternatives are emerging for using 2.4 GHz band specified in IEEE 802.11b and IEEE 802.11g protocols. The use of 5 GHz band is specified in IEEE 802.11a protocol. IEEE 802.11a and IEEE 802.11b operate using radio frequency (RF) technology and together are called Wireless Fidelity (WiFi) technology. However, WiFi technology based on IEEE 202.11b is used more for home networks. WiFi opens new possibilities for broadband fixed wireless access. There are differences on capabilities supported by these specifications. Public use of WiFi is emerging in hot spots deployed in hotels, airports, coffee shops and other public places. Hot spots are expanded to hot zones that cover a block of streets. WiFi-based broadband Internet access is also financially viable in a rural area, because it can provide fixed broadband access for towns, smaller remote communities, clusters of subscribers separated by large intercluster distances, as well as widely scattered users (Zhang & Wolff, 2004). The companies typically utilize WiFi for last mile access and some form of radio link for backhaul, as well. The proliferation of WiFi technology resulted in significant reductions in equipment costs, with the majority of new laptops now being shipped with WiFi adapters built in. The network consists of wireless access points serving end users in a point-to-multipoint configuration, interconnected to switches or routers using point-to-point wireless backhaul.

Both broadband wireless access and mobile multimedia services are a challenge for the research in wireless communication systems, and a new framework, Multiple-Input Multiple-Output (MIMO), is proposed (Murch & Letaief, 2002; Gesbert, Haumonte, Bolcskei, Krishnamoorthy & Paulraj, 2002). MIMO is an antenna system processing at both the transmitter and receiver to provide better performance and capacity without requiring extra bandwidth and power.

Another trend is the next-generation network that will be a multi-service, multi-access network of networks, providing a number of advanced services anywhere, anytime. Networked virtual environments (NVEs) may be considered another advanced service in the merging of multimedia computing and communication technologies. A wide range of exciting NVE applications may be foreseen, ranging from virtual shopping and entertainment (especially games and virtual communities) to medicine, collaborative design, architecture and education/training. One of the most popular groups of NVEs is collaborative virtual environments (CVEs), which enable multiple users’ collaboration (Joslin, Di Giacomo & Magnenat-Thalman, 2004). Distributed Interactive Virtual Environments (DIVE) is one of the most prominent and mature NVEs developed within the academic world. It supports various multi-user CVE applications over the Internet. Key issues to be resolved include localization, scalability and persistence (Frecon, 2004).

Another important field of research is the use of the medium-voltage network for communication purposes, such as Internet access over the wall socket, voice-over IP (VoIP) and home entertainment (i.e., streaming audio and video at data rates in excess of 10 Mbps) (Gotz, 2004). The power line communications offer a permanent online connection that is not expensive, since it is based on an existing electrical infrastructure. The development of appropriate power line communication (PLC) systems turns out to be an interesting challenge for the communications engineer.

A major roadblock to the widespread adoption of VoIP applications is that 911 operators are unable to view the numbers of callers using IP phones. VoIP service providers have had a hard time replicating this service, limiting the technology’s usefulness in emergencies. Enhancements to VoIP services are being developed.

Next- or fourth-generation (NG/4G) wireless systems, currently in the design phase, are expected to support considerably higher data rates and will be based on IP technology, making them an integral part of the Internet infrastructure. Fourth-generation paradigm is combining heterogeneous networks, such as cellular wireless hot spots and sensor networks, together with Internet protocols. This heterogeneity imposes a significant challenge on the design of the network protocol stack. Different solutions include an adaptive protocol suite for next-generation wireless data networks (Akyildiz, Altunbasak, Fekri & Sivakumar, 2004) or evolution to cognitive networks (Mahonen, Rihujarvi, Petrova & Shelby, 2004), in which wireless terminals can automatically adapt to the environment, requirements and network.

One of the main goals for the future of telecommunication systems is service ubiquity (i.e., the ability for the user to transparently access any service, anywhere, anytime) based on a software reconfigurable terminal, which is part of ongoing European research activities in the context of reconfigurable software systems (Georganopoulos, Farnham, Burgess, Scholler, Sessler, Warr, Golubicic, Platbrood, Souville & Buljore, 2004). The use of mobile intelligent agents and policies is quite promising.

STANDARDS

All devices on a home network require a protocol and software to control the transmission of signals across the home network and Internet. A variety of standard protocols are installed in devices depending on the type of device. The TCP/IP suite of protocols is the standard protocol for linking computers on the Internet and is the fundamental building technology in home networks for entertainment services and Web applications. Currently, several companies and standardization groups are working on defining new protocols for the emerging technologies and interconnections with already defined protocols.

For example, the International Telecommunication Union and Institute of Electrical and Electronics Engineers (IEEE) is developing standards for passive optical networks (PON) capable of transporting Ethernet frames at gigabit-per-second speeds. The Ethernet Gigabit PON (GPON) system aligned with Full Services Access Network (FSAN)/ITU-T specification focuses on the efficient support of any level of Quality of Service (QoS). The Ethernet in the first mile (EFM) initiative of the IEEE and the GPON of FSAN/ITU-T solution represents a cost-effective solution for the last mile (Angelopoulos, Leligou, Argyriou, Zontos, Ringoot & Van Caenegem, 2004). Collaborative virtual environments (CVE) are being standardized by the Moving Picture Experts Group (MPEG). MPEG is one of the most popular standards for video and audio media today, while only a few years after its initial standardization. Recently, multi-user technology (MUTech) has been introduced to MPEG-4, Part 11, in order to provide some kind of collaborative experience using the MPEG specification. Although mobile voice services dominate the market, there is a need for more cellular bandwidth and new standards through General Packet Radio Service (GPRS) to third-generation wireless (3G) systems (Vriendt De, Laine, Lerouge & Xu, 2002). GPRS provides packet-switched services over the GSM radio and new services to subscribers. Creating ubiquitous computing requires seamlessly combining these wireless technologies (Chen, 2003). The Universal Mobile Telecommunication System (UMTS) is the chosen evolution of all GSM networks and Japanese Personal Digital Cellular network supporting IP-based multimedia.

More security specifications for wireless technologies (Farrow, 2003) are being developed. For example, Wired Equivalent Privacy (WEP) is improved with Wireless Protected Access (WPA). However, WPA is an interim standard that will be replaced with IEEE 802.11i standard upon its completion.

In addition to current developments, recent standards were specified or enhanced to be commercialized. IEEE ultrawideband (UWB) task group specified the UWB standard, which promises to revolutionize home media networking, with data rates between 100 and 500 Mbps. UWB could be embedded in almost every device that uses a microprocessor. For example, readings from electronic medical thermometers could automatically be input into the electronic chart that records vital statistics of a patient being examined. The UWB standard incorporates a variety of NG security mechanisms developed for IEEE 802.11 as well as plug-and-play features (Stroh, 2003). Another standard, IEEE 802.16 for wireless Metropolitan Access Networks (MANs), is commercialized by WiMax Forum, an industry consortium created to commercialize it, which allows users to make the connection between homes and the Internet backbone and to bypass their telephone companies (Testa, 2003). The IEEE 802.16a standard is a solution based on orthogonal frequency-division multiplexing, allowing for obstacle penetration and deployment of non line-of-sight (NLOS) scenarios (Koffman & Roman, 2002). Another example of enhancement is the DOCSIS 2.0 (Data Over Cable Service Interface Specifications) standard to provide the QoS capabilities needed for IP-specific types of broadband access, telephony and other multimedia applications provided by the cable industry.

CONCLUSION

Home networking presents novel challenges to systems designers (Teger, 2002). These include requirements such as various connection speeds, broadband access for the last mile (DSL, cable, fiber or wireless), current and future services, security, new applications oriented on home appliances, multiple home networks carrying multiple media (data, voice, audio, graphics, and video) interconnected by a backbone intranet, specific bandwidth requirements for different streams and so forth. Information Technology is moving toward digital electronics, and the major players in the industry will position for the future based on a functional specialization such as digitized content, multimedia devices and convergent networks. The information industry will realign to three main industries: Information Content, Information Appliances and Information Highways. These major paradigm shifts are coupled with changes from narrowband transmission to broadband communications and interactive broadband. The interactive broadband will have sociological implications on how people shop, socialize, entertain, conduct business and handle finances or health problems.

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