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Wireline Telephone When we think about Wireline, we think about good old copper. The transmission material of choice of the telephone system since the beginning. Despite the development of mediums and the resulting supportive technologies of fiber, satellite, and wireless, copper has continued to increase its bandwidth and versatility as it enters the digital age. Cable, T-1, ISDN, ADSL and other And how does Wireline compare to Wireless in this comparison? Wireline will continue to hold a Cost/Configuration advantage over Wireless in areas where there is already supporting Public Network (LEC, CLEC) infrastructure and penetration. On the internet front, DSL will be the medium of choice for business users, and Cable Modem will be the choice of home users.
Wireline Telephony-- Copper When we think of telephone lines we think of copper wire. Though the first telephone lines were steel wire similar to telegraph lines. The year after the telephone was invented by Alexander Graham Bell in 1876 a Connecticut brass mill man, Thomas Doolittle, developed the proper tempers so the copper wire could be strung between poles without breaking or sagging excessively. Within ten years lower Manhattan was strangled in phone lines. Mans romance with communicating over copper wire had begun. But this was not the beginning of man's relationship with copper. Copper usage goes back 10,000 years to its first known usage as a hammered pendant in about 8700BC in what is now Iraq. Copper owned 100% of the metals market for nearly 5000 years, when gold finally appeared on the scene. Other metals were mere infants in comparison. Despite the long history of copper's usage, first in early utensils, ornaments and weapons, through the Bronze Age where it was alloyed with arsenic and later other elements, down to the present day, its use did not develop in a major way until the late 1800's. Electricity replaced the steam engine and the energy power center of technologic development. Humankind's romance with copper is as old as the history of humans. Maybe this is why every time it appears that copper wire will be made obsolete by a new technology such as fiber optic or wireless, a new technology appears and revives the copper wire a few more years of useful life. The first copper wireline was strung on poles or buildings between two telephones, and only those two phones could communicate together. The first telephone line was set up in Boston in 1877. It connected the home of Charles Williams Jr. in Somerville MA with his Boston office. Early telephones were thought of as toys and preceded the development of electrical lights and electrical distribution systems. Telephone lines connected the homes of business owners with their homes. The first commercial use of the telephone was in the gold mining area of California. Mining inspectors from the state capitol in Sacramento enforced large-scale hydraulic mining made illegal in the 1870's. They would inspect the mines periodically. The mining company to advise its mine site at Malakoff Diggins to reduce the mining operations to legal level before the inspectors would arrive used the first commercial telephone. This early use of the telephone was part of the creation of the greatest man made hole on the earth and kept this record until large scale copper mines could dig a larger hole with huge earth moving equipment in the mid twentieth century. The first development in wireline telephony was the use of copper wire instead of steel wire. Though iron was OK for low frequency telegraph signals, copper's conductivity was needed to send weak, high-frequency voice signals more than 50 miles without losing the signal through attenuation, or signal weakening, halfway down the line. This is one of coppers major weakness in that the signal weakens as it passes through the wire. The electrical property of copper wire is the key factor that limits its transmission speeds. The signal needs to be boosted or amplified. The first major development in copper wireline technology was the metallic circuit or two-wire circuit developed by Bell in 1881. This eliminated a lot of the electrical disturbances and unwanted noise in the lines there was a gradual conversion from grounded to metallic circuit lines between 1890 and 1990. This was further developed into the twisted pair system. As the transmission moved through the two-wire circuit, the signal would leak in to the other line, called crosstalk, this noise would be boosted with the transmission as the signal was sent over long distances. One way copper wireline is protected from interference of nearby wires is by twisting each copper wire of the two-wire pair. Interference introduced in each wire of the twisted pair is canceled at the twist in the wire. Further factors in the development of copper wireline were the introduction of cabling in 1881. The invention of the switchboard where many phone lines could be linked together. The first electronic vacuum tubes in 1915. Though primitive multiplexing was developed before the vacuum tube, by phantoming a third telephone conversation on the two-pairs of wire. The electrical carrier system added four circuits to the copper wireline. Crossbar switching cane along in 1935 and greatly expanded the phone system. Electronic switching added in 1965 facilitated PBX systems that further expanded the telephone. And finally the development of fiber optics in the late seventies fed the need for more voice as well as the huge growth in data transmission over telephone systems. The various telephone companies around the world have been in operation for over 100 years. During this time, they have been able to run twisted-pair copper wire to over 90 percent of the residences they serve. Over a century ago, utility companies of the developed world started to bury copper wireline into the earth for the purpose of telephone connectivity. Perhaps no other investment in the history of modern business has been so nurtured, as this copper wireline now represents a collective asset estimated in the hundreds of billions of dollars. It is a copper wireline that today criss-crosses over virtually every mile in all developing countries. And while much is made of the advanced communications information superhighway, the truth of the matter is that most of that road is still paved with the workhorse copper wireline. With the development of fiber optic cabling in the seventies copper wireline was assumed to be phased out over time. FO superiority in speed and clarity of signal in data transmission over copper wireline appeared to mean the end of copper wireline. Of the three basic parts of the telephone system, the long distance network, the short haul trunk portion, which is basically lines between central offices nearby each other, and the subscriber local loop. The first two parts, Long distance and trunk lines between central offices, of the three-part telephone system have seen FO replace copper. But the last mile of telecommunications has seen copper wireline reprieved decade after decade. The huge increase in commercial telephone line caused by the fax machine and by Internet in more recent years has seen the quantity of telephone lines in the local loop increase immensely. Due to the high expense of bringing FO or wireless to end user, copper wireline has held its own. Plans by major telephone companies such as Pacific Bell in northern California to replace all copper with FO have slowed or stopped. It has been estimated that it would take up to twenty years to physically replace all the copper wireline with FO or wireless. The cost of this conversion is estimated in the billions of dollars. Who knows what technological advances will happen in that time line, so the pressure to utilize existing copper wireline in high. The development of T-1 copper wireline has confronted copper wirelines weakness in high-speed data transmission. In addition the he technological development of ISDN, Integrated Service Digital Network, is a set of standards for digital transmission over ordinary telephone copper wireline as well as over other medial. This is available in urban areas of the US, Japan and Europe. It has two flavors, Basic Rate Interface, BRI, intended for home and small business use and, Primary Rate Interface, PRI, for larger users. ISDN requires adapters at both ends of the transmission so your access also needs an ISDN adapter. BRI transmits at the rate of up to 128Kbps, while PRI can transmit at speeds up to ten times that. ISDN has not seen the growth due to its set up and adapter costs, and often problems interfacing your machine with the new ISDN equipment. It often takes about a month to get an ISDN system running smoothly. This is unattractive to the plug and play mentality of the home and small business computer user. The technology that appears to give copper wireline its new rebirth is Digital Subscriber Line, DSL. A generic name for a family of evolving digital services to be provided by local telephone companies to their local subscribers. These services are known by ADSL, Asymmetric Digital Subscriber Line and HDSL, High Bit Rate Digital Subscriber Line. Unlike ISDN and analog modem connections the DSL connection is up 24 hours per day. DSL has the large telephone company support as well as emerging providers. Also PC manufacturers are pre-installing DSL modems with their products. Both Dell and IBM offer machines with DSL modems already built-in. I think copper wireline will be a major part of our telecommunication systems for many years to come.
Wireline Telephony -- Cable A Cable Modem is a digital modem that uses a coaxial cable connection (Same line as Cable TV, except filtered) for the data. Cable Modems are typically used for high speed transport of Internet data due to it's relative low cost. Downstream speeds of 300K to 1 Meg are typical, but may be as high as 20 Meg. Cable modems usually incorporate a 10Base T-Ethernet card since cable modems operate on a Shared Services Platform much like a LAN Advantages of the Cable system
Disadvantages of the Cable System
Cable Modem Glossary: Carrier Sense Multiple Access with Collision Detection (CSMA/CD): The Ethernet media access method. All network devices contend equally for access to transmit. If a device detects another device’s signal while it is transmitting, it aborts transmission and retries after a brief pause. Coaxial Cable:Cable with a central copper strand for transmitting electrical signals, surrounded by a concentric air or insulation (nonconducting) core, and enclosed by an outer (electrically shielding) concentric metal fiber, either braided or solid. DOCSIS: Data Over Cable Service Interface Specifications Specification for transmission of data over a cable network that has been approved by the ITU as an international standard. DOCSIS was developed by MCNS, a consortium consisting of CableLabs and a consortium of North American multi-system operators. Ethernet:The most popular LAN technology in use today. The IEEE standard 802.3 defines the rules for configuring an Ethernet network. It is a 10 Mbps, CSMA/CD baseband network that runs over thin coax, thick coax, twisted pair or fiber optic cable. Head-End: The control center of a cable television system, where incoming signals are amplified, converted, processed and combined into a common cable along with any original cablecasting, for transmission to subscribers. The system usually includes antennas, preamplifiers, frequency converters, demodulators, modulators, processors and other related equipment. Line Speed: Expressed in bps, the maximum rate at which data can reliably be transmitted over a line using given hardware. MCNS: Multimedia Cable Network System - A consortium of CableLabs and North American multi-system operators that developed DOCSIS, a specification for the transmission of data over a cable network that has been approved by the ITU as an international standard. Modem: Also Modulator/Demodulator - A device that converts digital signals to analog or converts analog to digital, allowing computer data to be carried over normal telephone and cable lines. Network Termination: Part of the Access Network, (owned by the carrier or the subscriber) located on the side of the subscriber's home. The following are functions of the Network termination Coupling of home wiring to the carrier wiring
Service Consumer System (SCS): The DAVIC term for the in-home infrastructure for broadband networking. The SCS consists of the following:
Wide Area Network (WAN): A computer network which usually spans larger geographic area, such as cities, counties, states, nations and planets. WAN's usually employ telephone-type topologies, like T1, T2, T5, ATM, etc. The Internet is held together by lots of WAN's which hold together LAN's, which network computers. Wireless Cable: Uses microwaves frequencies to transmit programming to a small antenna at a subscribers home.
Conclusions on Wireless Vs. Wireline Cable Modem Application: Cable and Cable Modem seems to be the service of choice to bring high bandwidth Internet connections into the home due to low cost, ease of installation, and existing infrastructure in communities equipped with cable. Cable is not as competitive with xDSL (another wireline technology) for business applications due to the high upstream capabilities of xDSL and the lack of the Ethernet hub reductions and bottlenecks in bandwidth in high density areas where there are many users on a cable hub. Cable is not viable versus wireless cable, wireless LANs and WANs due to the extensive line and cable laying necessary to create an internetwork. It may even be more expensive than a wireless solution especially if there are numerous locations on the LAN/WAN. Cable is not a longhaul solution unless it is fiber. So given the narrowness of application, cable and cable modem technology is a leveraged technology, a way to bring cheap bandwidth to the public in areas where there is an existing cable network and a profitable buying public.
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