We will cover some familiar ground in this article as we move ahead. We have discussed analog modems and Integrated digital Network Services (ISDN) in previous articles, including the standards which govern each or these hardware systems. This article touch on the technologies and hardware which open that bandwidth even wider, ie., make data move faster. New techniques and hardware are on the horizon which will give individuals network level bandwidth. 

 Multimedia and graphic data demand greater bandwidth. Voice e-mail, alone, uses kilobyte size files to send and receive. Live action video segments as small as three seconds may use megabyte size files. These size files are not really receivable using a 14,400 bps analog modem. We all have a NEED FOR SPEED in our communication with others through our computers. 

Bandwidth Defined

 Our analog 14,400 bps modem from above would be equivalent to a large soda straw. An analog 28,800 bps modem would be a garden hose in our analogy. An ISDN terminal adapter would provide a two inch pipe flow of data. The ISP's T-1 line at 1.54 Mbps would be a six inch pipe data flow. The combined Internet backbone network would be a Mississippi River data flow. 

 There are, of course, intervening bumps which help to confuse us. A range of connectivity speeds have been established to meet our needs and fall into two broad categories. These are low speed and high connections. Dial-up analog modems are the most basic of these connections and provide speeds of up to 56 Kbps. At the high end, we find Synchronous Optical Network (SONET) which handles connections at multiples of 51.840 Mbps, ie.,., STS-1 at 51.840 Mbps and STS-12 at 622.08 Mbps. 

 The majority of personal and business connections fall into the low speed regime. These connections are the analog, ISDN, and T-1 capabilities. 

Some locations around the country have TV cable which allows two-way transmission of data in addition to the regular TV downloads. These connections provide speeds of around 1.5 Mbps. 

Bandwidth Technologies

Compression is required to reduce the transmission time. Several standards or protocols are available in analog modems to insure that each modem can understand what the other one is sending. These protocols equate to speed and compression and are embedded into the modem structure. Analog signals are transmitted over the standard Plain Old Telephone Service (POTS) twisted pair lines. Analog transmissions are affected by static in the phone line. The next level involves transmission of the digital data directly as digital information, with no conversion to a serial path. ISDN is the first technology and increases bandwidth greatly. ISDN provides connections at rates of 56 Kbps to 128 Kbps in its various basic combinations. It provides both switched digital and analog phone service. ISDN uses POTS twisted pair lines. ISDN and POTS voice service are interoperable. 

 The basic ISDN transmission channel is either 56 or 64 Kbps in the United States, depending upon the telephone company (telco) switch service. ISDN is allocated in channels. The basic channel for SouthWest Bell is 64 Kbps. It is known as a B-channel. The basic ISDN service is known as Basic Rate Interface (BRI) and consists of two 64 Kbps B-channels and one 16 Kbps signaling channel, adding up to 128 Kbps. 

ISDN service is available as a Primary Rate Interface (PRI) and consists of 23 switched 64 Kbps B-channels and one 64 Kbps D-channel. 

 One technology which is being used in some locations takes advantage of the TV cable. This is not a technology associated with any of the telco standards. Cable connections have been around for a long time. The main problem is that the cable companies have not had enough incentive to invest in their cable infrastructure to really provide the service. Cable connections really become useful when they are two-way. 

 Dedicated "private line" service is the next level of connection. This service consists of the FT-1, T-1, and T-3 capability. Fractional T-1 and T-1 service both provide 1.54 Mbps connections. Fractional T-1 service splits the full bandwidth into shares of use time. T-1 type service is used by large business for dedicated connections. 

 Another technology which offers much benefit, but is not being offered by the telcos is Asymmetric Digital Subscriber Line (ADSL) which offers connect speeds from 192 Kbps to 1.5 Mbps. This is a subset of the Digital Subscriber Line technology which takes advantage of the Switched Multimegbit Data Service (SMDS) connection service. ADSL modems will be installed and setup by the computer manufacturer to take advantage of this technology. 

 Satellite connections are becoming available. The satellite connections provide 400 Kbps for downloads. One-way connections are readily available through the 18 inch dishes and connecting hardware. The up-link requires a standard analog modem link. Two-way satellite connections will become more available in the future. 

 SONET is a digital hierarchy for high bandwidth, fiber-based signals. The SONET / cell relay service is mainly used by the telcos as their wide area network capability. The very large corporations sometimes use SONET leased lines to cover connectivity between two large facilities. SONET is charged by the mile and is distance sensitive. 

How Much Bandwidth

 Full motion video requires incredible amounts of transmission speed, RAM, and digital storage space to use in addition to high CPU performance. Anyone who needs to send or receive any multimedia or other graphics needs the highest bandwidth analog or digital connections they can afford. 

 The rest of us probably need the full benefit of the latest 56 Kbps analog connectivity. We need the reliability of the V.90 protocol to take full advantage of the 52 - 56 Kbps downloads offered by this technology. There is an evolving technology which combines two or three 56 Kbps modems into one connection. 

Multimedia communication would be an excellent way to use cable data connections. Paragon Cable has two-way fiber in most of the San Antonio neighborhoods. They have demonstrated cable modems at electronics shows. This type connection will provide multimedia level bandwidth. One article stated that a 13 MB video downloaded in one minute and 20 seconds. 

 The satellite down link would fulfil the download requirement for multimedia. The problem would be on the up-link. True two-way satellite links may have to wait for the addition of new, cheaper satellites from Bill Gates and others. 

How to Get Bandwidth

 There is a downside to combined analog modems. One's ISP must be able to handle the combined up-link and downlink. You may also have to have more than one account or a special higher rate account with the ISP. 

 ISDN TAs also are fairly easy to set up. This has not always been the case. The ISDN setup is complicated in any case. Most internal ISDN TAs use one B-channel for data and the other for POTS voice connections. The USR Sportster ISDN internal TA can be setup for combined B-channel operations at 128 Kbps. Most external ISDN TAs are used as combined units. ISDN TAs can also be incorporated with routers or as routers to meet small business connectivity needs. Again, some of these units allow more than one individual to share one IP account. ISDN TAs use existing telco twisted pair phone lines for data and voice. 

Cable modems are available only in selected parts of the country. The closest cable system providing this service in this area is Durant, OK at this time. There has been lots of promise, but little actual action by the cable companies. 

 ADSL is slowly taking place. It has two great things going for it. One, it is cheaper than T-1 for business. Two, it uses existing telco twisted pair phone lines for data. Some computer manufacturers are beginning to incorporate ASDL devices into their desktop computers. Compac and Dell are installing ADSL modems in some of their top of the line computers. Other manufacturers are building ADSL devices which will install into existing systems. One of the problems, again, is with the support infrastructure at the telco. Telco's are slow to install the proper equipment at the CO which will give broad support the technology. 

Bandwidth Cost and Conclusion

 Combined 56 Kbps analog modems are more expensive in all ways. The units usually must be external and range in price from $499.00 to $2,495.00. The multiple user communication software to go with them costs in the range of $100.00. Additional costs at the telco for extra POTS phone lines, and at the ISP for special or multiple accounts to support the combined modems are also factors to consider. 

 ISDN TA costs are dropping. Internal ISDN TAs range from $190.00 to $305.00 for 128 Kbps connections. External ISDN TAs range from $289.00 to 405.00. 

 The ISDN routers are more expensive at the $599.00 to $1200.00 range. Multiple user and firewall communication software is in addition to these costs at $100.00 to $500.00. 

 ISDN telco and ISP costs are more expensive as well. The telco must charge the tariff rate at $58.00 plus tax per month. The ISP will charge extra per month for the ISDN connection. 

 Internal ADSL modems installed in computers will add approximately $250.00 to the system. The connection cost ranges from $65.00 to $125.00 per month per connection at the telco. The ISP cost was not available. 

 Broad bandwidth is available for use by individuals now. It is really a matter of cost. For most individuals, the digital level bandwidth are to expensive to use outside of business needs. 

 JOHN WOODY IS A TELECOMMUNICATIONS CONSULTANT SPECIALIZING IN SMALL BUSINESS COMMUNICATIONS, NETWORKS, AND INTERNET BUSINESS TRAINING.