1. Dsl Vs Cable Internet

Do you have the right broadband internet connection for your business? And what does “broadband” mean anyway?

If you’re like us, you’ve asked yourself these questions, maybe because you just started up or bought a new business or decided your office needed a change. Broadband is an umbrella term that refers to just about any type of residential or business internet that is faster than dusty, old dial-up connections.

Broadband connections are typically “wireline,” which means you get connected to your high-speed Internet Service Provider (ISP) through a complex chain of cables. But there’s also wireless broadband, most notably in the form of satellite internet that is broadcast from stations orbiting the planet. But that doesn’t answer which internet service is best for your business. Unfortunately, the answer isn’t as simple as picking a winner—each type has its own benefits, flaws, and quirks.

On this page, we cover all the major types of internet connections and compare them in one-on-one matches so you can find the right connection to boost your business. DSL: Low-tech but high-speed internet Digital Subscriber Line (DSL) is a type of fixed wireline broadband internet that travels along existing copper telephone lines.

In the late 1990s, DSL became one of the first widely available broadband connections after the dial-up access age. Fast facts. Download speeds from 1 to 500 Mbps. Upload speeds from 384 Kbps to 8 Mbps. Prices from $20 to $300 per month Although DSL uses telephone lines like dial-up connections do, DSL’s “two-wire” technology allows you to get broadband internet without interfering with your phone services.

Your business gets connected via a DSL modem that in turn connects to your devices using local or wireless internet connections. There are a couple different types of DSL internet, the main two being ADSL and SDSL. The A and S stand for “asymmetric” and “symmetric,” respectively. ADSL connections tend to have faster download speeds than upload speeds, which is fine for businesses that don’t do a ton of upload-heavy file sharing. SDSL typically has matching upload and download speeds, which is great for video conferencing, but it’s not as widely available as ADSL. Two other DSL types—VDSL and HDSL—offer faster speeds than ADSL or SDSL.

DSL speeds often don’t reach what ISPs advertise. DSL is more reliable than dial-up access. But according to the FCC, DSL speeds often don’t reach what ISPs advertise.2 The availability of DSL broadband is high thanks to the widespread installation of required lines.

However, your ability to get DSL internet may depend on how close your office is to a phone-line facility. Your cable ISP will equip your office with a cable modem that attaches to a wall outlet. The cable modem then connects to your computer and devices via ethernet cables or through a Wi-Fi router’s network. You can also set up a local area network (LAN) or wide-area network (WAN) to keep your devices connected and in sync.

A downside of cable internet is that the copper coaxial cables are susceptible to electrical surges or heat damage. The fastest and most reliable cable connections use HFC cables—which aren’t as prone to electrical surges—and DOCSIS 3.0 cable modem technology. According to a 2016 FCC study, cable plans reached advertised speeds more reliably than DSL plans did. 3 Yet a potential risk stems from traditional cable internet sharing connections with other subscribers in the area.

That means that during peak times, you could experience lagging speeds as your neighbors drink from the same well of internet juice. Some ISPs offer dedicated cable internet access to avoid this problem. A dedicated line is what it sounds like: a connection dedicated to only transmit from the ISP to your business. Dedicated lines provide much faster and more reliable internet for cable subscribers but cost a premium. Fiber internet: Freaking fast Fiber-optic internet is the newest entrant in the broadband race. It’s a technology that can provide some seriously stunning speeds and solid reliability for small businesses.

Fast facts. Download speeds from 25 Mbps to 1 Gbps. Upload speeds from 5 to 880 Mbps. Prices from $50 to $650 per month Fiber internet connection gets its name from the glass or plastic fiber cables that substitute copper DSL or coaxial cables. Your fiber ISP will provide you with a modem or a gateway router to connect your office and devices. Tiny fibers the size of a width of hair transmit data with beams of light (that’s the “optic” part), which means the cables can carry higher bandwidth at higher speeds and with higher reliability than DSL or cable. And many fiber internet plans are “symmetrical,” which means your upload speeds match or nearly meet download speeds.

Fiber-optic internet isn’t as prone to problems from distance, frequency interference, and heat damage because glass and plastic don’t easily conduct electricity. But note that the actual speeds and reliability you get from your ISP can depend on things like the exact type of fiber network you’re connected to and the plan you purchase.

Satellite internet: Beamed to your business For businesses in rural or remote areas without access to landline internet like DSL, cable, or fiber, satellite technology is a lifesaver. Fast facts. Download speeds from 1 to 25 Mbps. Upload speeds from 1 to 4 Mbps. Prices from $60 to $420 per month If you’re a satellite internet subscriber, your office will be equipped with a receiver dish pointed to the southern skies. You’ll get your data from earth-orbiting stations operated by ISPs. The satellites transmit data to the dish using radio frequencies that are converted into internet signals by a modem inside your office.

Current satellite internet technology can’t deliver connection speeds as fast as DSL or cable, and it’s nowhere near as fast as fiber. The stations orbit Earth at distances reaching 23,000 miles away—nearly 10 times the width of the continental United States. Data taking such a massive trip simply can’t travel fast enough. These far-reaching distances also lead to reliability problems. Satellite internet suffers from high latency, resulting in delays between connection points.

What’s more, because satellite bandwidth is a precious resource, ISPs place limits on the amount of data you can use during certain periods of the day. You may have limited data during peak daytime use, for example, but more flexibility after hours. In case it wasn’t crystal clear, fiber is fast. If you’re looking for a connection that can move at lightning speeds, fiber is your best option. Although new technologies are pushing some DSL and cable speeds into the several-hundred-megabits-per-second range, nothing compares to the unadulterated pace of a pure-fiber connection.

With ISPs like Verizon and AT&T offering gigabit plans, you can connect your office to fiber for lightning-fast downloads and uploads. Internet speeds at this pace are great for complex cloud computing and near-seamless file sharing and backups—which can boost your small business into the future. The cheapest internet type: DSL or cable Are you more of a budget-conscious business decision maker?

Fortunately, both DSL and cable ISPs offer plans that give you decent internet speeds at sensible prices. DSL providers like offer introductory plans at around $20 per month for about 1 to 3 Mbps in downstream speeds. For higher-speed plans, we found cable ISPs to be more affordable than DSL.

For example, Spectrum offers an $89 cable plan for 100 Mbps while Centurylink’s $85 plan gives you only 40 Mbps. The best internet access for rural offices: Satellite Satellite internet is often the only option for businesses in sparsely populated areas, so if that’s you, then it’s the clear winner in a race of one. Yet some offices may have access to only dial-up connections or low-speed, copper-wire DSL internet—in which case, satellite is the best option. With download speeds up to 25 Mbps and close-to-perfect accessibility, satellite internet is your best bet if you can’t get DSL, cable, or fiber. One caveat: fixed wireless internet is another option for some businesses.

Fixed wireless providers use radio towers to transmit internet to a modem inside your office. This type of internet can be more reliable than satellite, but speeds tend to be lower, maxing out around 10 Mbps. Fixed wireless broadband is also much less available than satellite internet—another reason we can’t call it the winner. Round one: Speed Traditional DSL internet is much slower than plans offered by fiber ISPs. And even newer technology like VDSL can’t match the mind-blowing speeds of fiber gigabit connections. Round one goes to Fiber.

Round two: Affordability Although some fiber plans start around $20, their speeds aren’t worth the switch from DSL if it’s available. If you don’t need the super-fast speeds of fiber, DSL is the more affordable choice. Round two goes to DSL.

Round three: Reliability DSL is a more reliable option than dial-up internet. But because DSL providers give you access through your business’s phone line, you could lose your connection if the phone lines are damaged or interrupted. Fiber-optic is much more reliable, in part because it’s a passive system that doesn’t need electricity to power the network.

Round three goes to Fiber. Round four: Access DSL is widely available to businesses across the country. Fiber is only available to a fraction of customers—so far. But fiber internet access is growing. Round four goes to DSL.

And the winner is. Round one: Speed This one was easy. Fiber—the fastest option—totally wastes satellite—the slowest option—in the speed race.

Round one goes to fiber. Round two: Affordability Another easy win for fiber, which is more expensive than DSL or cable on average but still cheaper than satellite when matching speed for speed. Round two goes to fiber. Round three: Reliability Satellite internet is no match for the supremely reliable technology in fiber-optic connections. Round three goes to fiber. Round four: Access It’s not a total KO for satellite. Only some businesses can access fiber internet, while nearly any office can connect to a satellite ISP.

Round four goes to satellite. And the winner is. Round one: Speed With gigabit connections reaching toward 1,000 Mbps, fiber is the true winner over cable, which typically gets you only as far as 300 Mbps. Round one goes to fiber. Round two: Affordability Although fiber plans are often a better value for their speed than cable, if you’re looking for cheaper internet plans to run your business, cable prices usually start lower.

Round two goes to cable. Round three: Reliability Cable and fiber are generally reliable internet types. But fiber wins this round because the fiber-optic cables are safer from damage and outages than traditional coaxial cable internet. Round three goes to fiber. Round four: Access Cable is widely available thanks to Americans’ love for cable TV. If your business can receive cable television, it can most likely access cable internet. And although cable isn’t available in some rural locations, fiber connections are even less so.

Round four goes to cable. And the winner is.

Round one: Speed Satellite can’t beat DSL in download or upload speeds. The fastest satellite internet you can get maxes out at 25 Mbps, while DSL can get you into the hundreds of megabits per second.

Round one goes to DSL. Round two: Affordability Another loss for satellite. Satellite internet is almost always more expensive than DSL, with plans that range from about $50 to $200 per month—plus the costs of buying or leasing a satellite dish. DSL plans can run as cheap as $20 per month for low speeds, and even $50 for moderate speeds. Round two goes to DSL. Round three: Reliability Satellite loses the reliability round too because its signal can be blocked or interrupted by trees, mountains, structures, bad weather, and even sunspots. Round three goes to DSL.

Round four: Access DSL may be available to the majority of businesses, but satellite ISPs can provide access to almost any office in the world with a clear view of the sky. Round four goes to satellite. And the winner is. Round one: Speed Cable wins the speed round. Newer VDSL and HDSL technology can deliver speeds close to 100 Mbps, but many commercially available cable plans exceed 200 Mbps—some up to 300 Mbps.

Round one goes to cable. Round two: Affordability DSL plans tend to be cheaper than cable plans at lower speeds. Cable internet often costs more, but you do get the option of faster plans with cable. Round two goes to DSL. Round three: Reliability Cable and DSL both provide an “always-on” connection, which means that as long as your computer is on, it’s connected to the internet. You may lose your connection from damaged cable or telephone lines, but both internet types provide about the same reliability.

Round three is a tie. Round four: Access As long as your business can receive television cable service, you can likely get cable internet. A similar truth holds for DSL: most offices connected to telephone lines can access DSL internet services. Round four is a tie. And the winner is.

It’s another tie! Round one: Speed This round is pretty simple. Satellites can’t beam internet to your business nearly as fast as cable ISPs can. Round one goes to cable.

Round two: Affordability Comparing Mbps to Mbps, cable is the clear winner for price. Satellite is much more expensive, and most subscribers choose it because it’s the only option for them. Round two goes to cable. Round three: Reliability Satellite loses the reliability race thanks to it having to travel much farther into space to reach you. Round three goes to cable. Round four: Access Win one for satellite—it’s available almost everywhere.

Although most US companies can access cable internet, satellite is still more widely available. Round four goes to satellite. And the winner is.

5 crucial points to consider when choosing the best internet for your business If you read each of the internet showdowns above, you should have an understanding of how each type compares to the other. But choosing the right connection for your business depends on several factors. Cdc drivers download.

Here are five questions you should ask yourself when deciding the best connection for your office:. What’s available? Internet access for many businesses is limited to only one or two kinds of internet—which is unfortunate but makes the decision easier. Find out which internet plans are available in your area to begin your search. What’s my budget?

Don’t blow out your bottom line just to get the fastest speeds available. Determine what your business can afford per month, and then look for plans that meet your criteria. You can always switch later. How much speed do I need? If your business relies on constant, complex online computing, you’re going to need seriously fast speeds. But if you just need to do some day-to-day browsing and downloading, you can probably get away with lower speeds.

How important is reliability, customer service, security, and technology? Speed and price aren’t the only factors to consider.

Ask if your potential ISP has reliability or technical support guarantees. Look around for customer service ratings (although be warned: most ISPs don’t have the best reputations). And see if you can get free or discounted technology upgrades like cloud storage, VoIP services, and security software. Can I save by bundling internet with phone and/or TV?

Finally, business ISPs love to bundle. Although you may not need sophisticated TV or phone services, you may be able to save on the full package by combining offers. For even more details, read. How often should you reevaluate your high-speed internet service provider?

It’s a good idea to take a new look at your business internet options any time your business expands, your budget changes, or you’re nearing the end of a contract with a current ISP. You could benefit from changing to a new plan, but be careful—there are some potential downsides of switching providers.

The benefits of switching ISPs: You could potentially lower your costs, raise your speeds, access more functionality, and get better customer service and technical support. The disadvantages: You may have to pay early termination fees and new equipment or installation costs, and you could lose email or service accounts (security suites, cloud backups, etc.). Are there other types of internet connections?

We covered the major contenders in the internet wars, but there are a few others worth mentioning. Cellular: You can do business using your cellular provider’s data plan. Many smartphones let you set up “hotspots” to connect a computer to a wireless network. This is a good option for on-the-go business, but it’s too slow and expensive for long-term, data-heavy usage. Dial up: Many residents are still popping AOL discs into their computers and dialing into their telephone carriers to access the internet—and some businesses too!

It’s notoriously slow, but dial-up internet hasn’t yet disappeared entirely. Ethernet: This is not a primary internet connection.

Rather, Ethernet is a way to connect devices to each other in a local area network (LAN) or to your primary ISP router or modem. Fixed wireless: As an alternative to satellite internet for some rural offices, you may be able to get a fixed wireless broadband connection that uses radio frequencies sent from nearby towers. It’s more reliable—but not usually faster—than satellite internet. T1: T1 lines offer a dedicated and reliable way for businesses to get internet. The advantage of a T1 line is that the ISP usually guarantees your connection to be online at a certain percentage.

You also don’t share your T1 connection with any other subscribers, unlike most cable connections. On the other hand, the high cost for T1 lines tends to make it unattractive to small businesses. The takeaway There’s no single winner in our types of internet connections melee—the best type is the one that meets your business needs. If you need the fastest speeds, consider fiber. If your budget is tight, try a low-cost DSL plan.

Or if your office is remotely located, satellite’s probably your best option. In the end, the connection that balances your cost, speed, and service requirements will be your champion. Disclaimer At Business.org, our research is meant to offer general product and service recommendations. We don’t guarantee that our suggestions will work best for each individual or business, so consider your unique needs when choosing products and services. Wired Score, “” 2.

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Most people use cable TV or digital subscriber line (DSL) for high-speed Internet access at home. In fact, 50% of all broadband customers use cable, 42% use DSL, and 8% use fiber-optic cable, satellite, or a wireless system. However, DSL dominates in Europe and the rest of the world. Cable and DSL both have been around for years with steady upgrades and improvements, though their methods for delivering high-speed data are very different.

Cable TV Systems Cable TV systems were developed to provide reliable TV service to local communities. Along with the hundreds of TV channels available, cable companies offer services such as high-speed Internet access.

Some even offer voice over IP (VoIP) telephone service. Cable companies usually offer a “triple-play” package that bundles TV, phone, and Internet services. Systems have been upgraded from pure analog transmission to digital. Early systems were based on coax cable, but today the most common configuration is fiber-optic cable and coax. Hybrid fiber coax is one of the most common configurations (Fig.

The typical hybrid fiber coax (HFC) cable TV distribution system used throughout the U.S. Consists of fiber-optic cable to neighborhood nodes that then distribute the signals to homes with RG-6/U coax. All of the services originate from the cable company’s facilities, known as the headend, where the company collects the video from local TV stations and cable TV programming suppliers via satellite. The company then packages multiple channels into bundles for basic cable as well as two or three other options of premium movie and/or sports channels.

The headend also has an interconnection to the Internet, where it can supply Internet services or connect to a separate Internet service provider. The headend connects to the end user via a network of fiber-optic and coax cables. The TV channels and Internet channels are frequency multiplexed and modulated on to the main fiber-optic cable for transport out to distribution hubs that rejuvenate the signals over longer cable runs. From the one or more distribution hubs, the signal travels to multiple optical nodes located in various city or suburban neighborhoods. In a typical configuration, a single fiber is split to serve four fiber optical nodes.

Most fiber nodes serve up to 500 homes. With this arrangement, each fiber serves up to 2000 homes, although not all homes passed have a cable modem or service. The optical nodes convert the optical signals into electrical signals for the final distribution via coax cable. The most common cable is RG-6/U 75-ohm coax using F-type connectors. All of the homes receive the same signal, just like a bus network topology.

In some areas with longer distances, amplifiers are added along the way to mitigate the large cable losses that are common. All of the TV signals and Internet data are transmitted in a spectrum of 6-MHz wide channels. Since a coax cable has a bandwidth as wide as 850 MHz to 1 GHz, the system can accommodate from 140 to 170 downstream channels of 6 MHz each. The TV signals or Internet data are modulated on to carriers in each channel. There are also upstream channels that allow the consumer to transmit data back to the headend. This communication takes places in 6-MHz channels as well that occupy the cable spectrum from 5 MHz to 40 MHz or in some systems up to 65 MHz.

The composite video signal is developed in equipment called the cable modem termination system (CMTS). In older systems, the video information is modulated on to the 6-MHz channel carriers and then all channels are combined or linearly mixed to form the composited cable signal (Fig. However, today it’s possible to synthesize a full block of modulated channels digitally. The digitized video is sent to an ASIC or FPGA programmed to produce the desired quadrature amplitude modulation (QAM) for each channel (Fig.

The signals are then digitally upconverted to the final frequency and sent to a wideband digital-to-analog converter (DAC) that produces the composite multi-channel signal to be sent to the cable. In older cable TV systems, individual modulators add the video to the channel carriers that are linearly mixed to form the composite signal for transmission over the cable (a). Modern cable TV systems are beginning to use direct digital synthesis of the composite signal for transmission (b). The digital video signals are fed to an ASIC or FPGA, where an inverse FFT and other techniques implement the QAM modulation and upconversion.

A fast RF DAC develops the final composite analog signal for transmission on the cable. Maxim Integrated’s MAX5880 modulator/digital upconverter (DUC) can generate from eight to 128 QAM modulated channels. It is a 14-bit RF DAC with a 4.6-Gsample/s rate that produces the final signal. Figure 3 shows what the output signal looks like in the frequency domain. This illustration shows a spectrum analyzer output display of 128 QAM channels generated by the MAX5882 and MAX5880 combination.

The full bandwidth is 1 GHz with a center frequency of 525 MHz. The resolution bandwidth is 1 MHz. You can just make out the 6-MHz channels, 16 per 100-MHz segment. In older analog systems, each TV signal occupied one 6-MHz channel. Modern digital signals may have one TV signal per channel or more. Digital TV signals can be compressed using MPEG compression algorithms to reduce the amount of channel space required for transmission, allowing multiple signals per channel.

Downstream modulation is usually 64-state QAM (64QAM) or 256-state QAM (256QAM), meaning each channel can deliver a data rate up to 38 Mbits/s. Higher speeds can be achieved by using channel bonding, which transmits the data stream in two or more 6-MHz channels. Users do not usually get the full download speeds mentioned above.

Because the coax line is a bus shared by many homes, the data speed is divided up amongst those who are using the connection. A single user will get the full speed but with multiple users each will get a proportionally slower connection. Upstream modulation is quadrature phase-shift keying (QPSK) or one of several variations of 16/32/64/128QAM. Upstream rates are typically less than 27 Mbits/s. The downstream data is routed through the cable wiring in the home through splitters that divide the signal for multiple room connections.

Dsl Vs Cable Internet

One or two devices then recover the signals. A cable box or set-top box (STB) selects the desired television channel with a tuner and directs the signals to the TV set for presentation. In some cases, a cable-ready TV can recover the signals without the STB. Internet service and VoIP telephone service use a cable modem, which connects to the Ethernet port on a PC or laptop. In many homes today the cable modem connects to a wireless router that distributes the service by Wi-Fi to PCs, laptops, tablets, or cell phones. Most cable modems also have a telephone option where the digital VoIP is converted to be compatible with the standard telephone wiring in the home so standard phones can be used.

A standard RJ-11 connector connects the cable modem to the home wiring. Most cable systems are based on the Data Over Cable Service Interface Specification (DOCSIS).

Developed by CableLabs in cooperation with the industry, DOCSIS defines the operating system and the hardware specifications. Version 1.0 was introduced in 1997. DOCSIS 2.0 came along in 2001, and DOCSIS 3.0 was released in 2006. Most systems use the latest version, which is IPv6 capable.

DOCSIS also provides multiple security options including a Baseline Privacy Interface (BPI) or security (SEC) option. The 56-bit DES and AES 128 encryption methods are available, as is public key infrastructure (PKI) authentication. DSL DSL is one of the oldest forms of high-speed Internet access. It had its start in the 1990s and has since evolved into a very stable and capable platform. It uses existing telephone wiring, generally known as the plain old telephone system (POTS).

The in-place unshielded twisted pair (UTP) telephone lines form the backbone of the legacy wired telephone system. Thanks to technological developments, this wiring that was installed to handle voice telephone calls can now deliver high-speed digital data at 50-Mbit/s rates and beyond in some cases.

In a typical system, the telephone central office is connected to each subscriber by one or more #24 or #26 copper wire unshielded twisted pairs, with one for each telephone number. The lines are not shared. The cable runs vary from a few hundred feet to a maximum of 9000 to 18,000 feet (2.7 to 5.5 km). The system was designed to carry voice in the 0- to 4-kHz range.

Early in the Internet era, dialup modems were designed to carry digital data over these analog lines. Special QAM modulation and encoding schemes allowed data to be carried at rates to about 56 kbits/s maximum. Then the DSL system was developed to carry much higher speeds. The original DSL system was designed to produce data rates of 1.5 Mbits/s to 8 Mbits/s downstream from the telephone company to the subscriber and a lower rate upstream. Most Internet access involves more downloading and less uploading of data.

The resulting design is referred to as asymmetrical DSL or ADSL. Most DSL formats are asymmetrical, although there are DSL variations that deliver the same rates in both directions. The great attenuation, noise, and crosstalk problems of bundling multiple twisted-pair lines are the primary limitations of the POTS. These lines are effectively long low-pass filters with upper frequency limits that reduce the bandwidth of the line and limit the data rate that can be achieved. Line bandwidth is a function of the length of the UTP. Shorter cable runs have wider bandwidths, so they are clearly more capable of high data rates than longer runs.

But despite this limitation, developments in digital signal processing have made this once limited communications medium capable of high-speed data delivery. The telephone companies (telcos) have upgraded this basic system to include neighborhood terminals called digital subscriber line access multiplexers (DSLAMs). The DSLAM shortens the distance from the subscriber to the central office, so much higher speeds can be delivered. For shorter cable runs, the DSLAM may be in the central office. The DSLAM aggregates the data from multiple subscribers and connects them back to the central office by fiber-optic cables.

This arrangement is generally known as fiber to the node (FTTN). Older systems used T1 or T3 lines, but today most DSLAM connections are fiber. On the consumer end of the telephone line is a DSL modem generally called the customer premise equipment (CPE) that is used to demodulate the signals from the DSLAM and modulate any upstream transmissions. A low-pass filter separates the 0- to 4-kHz voice spectrum from the higher frequencies used for data transmission.

Most DSL systems use a modulation scheme similar to orthogonal frequency division multiplexing (OFDM) called discrete multitone (DMT). It divides the cable spectrum into subchannels or bins that are 4.3125 kHz wide (Fig. The original basic DSL uses 256 subchannels for a bandwidth of 1.1 MHz. The lower subchannels from approximately 26 kHz to 138 kHz are used for upstream transmissions from the subscriber to the central office.

Above 138 kHz to about 1.1 MHz are the subchannels used for downstream transmission. This is the spectrum of the unshielded twisted-pair cable showing the subcarriers and the upstream and downstream allocations for ADSL, ADSL2, VDSL, and VDSL2. As in OFDM, the high-speed serial data to be transmitted is divided into many slower parallel streams, each of which modulates a subcarrier in each subchannel. Modulation can be from QPSK to 64QAM. In DSL, the maximum bit rate per carrier is 60 kbits/s. The modulation is accomplished digitally in a digital signal processor (DSP) using the inverse fast Fourier transform (IFFT) for modulation and FFT for demodulation. The actual data rate depends not only on the modulation method used but also on the number of subchannels used—and, of course, the distance between the central office or DSLAM and the CPE.

Noise is another limiting factor. The DSLAM and DSL modem can adapt to noise conditions by examining the spectrum and blocking channels with excessive noise content. This reduces the speed but maintains the link with accurate data.

There are many different versions. ADSL is the most common, although some newer and more advanced versions are widely used. For example, ADSL2 extends the line bandwidth to 2.2 MHz and 512 subchannels, extending the maximum data rate to 12 Mbits/s.

Another variation, ADSL2+, further extends the maximum rate to 24 Mbits/s. Then there is video DSL (VDSL). Designed to carry compressed digital video for HDTV, it achieves even higher rates by using more of the cable bandwidth and further restricting its length. There are multiple versions including VDSL2 with a variety of specifications. One version uses the UTP cable bandwidth out to 8.832 MHz with 2048 subcarriers to achieve a maximum rate of 50 Mbits/s. Other versions use 12, 17, or 30 MHz of bandwidth.

With the 17-MHz bandwdith and 4096 subcarriers, the maximum possible data rate is 100 Mbits/s. Another version uses 30 MHz of bandwidth with 3479 subchannels that are 8.625 kHz wide instead of the usual 4.3125 kHz. Maximum data rate is 200 Mbits/s. The range is usually restricted to 1000 to 3000 feet. Unlike cable TV connections, DSL gives the full speed to each user. To make VDSL2 even faster, companies like Broadcom, Ikanos, and Lantiq are implementing VDSL2 chips with a feature called vectoring.

This digital signal processing technique cancels noise and far-end crosstalk (FEXT) between bundled twisted pairs, enabling high speeds. These new chips also implement channel bonding that permits two twisted pairs to be used simultaneously to further increase speed to 200 Mbits/s downstream and 100 Mbits/s upstream.

For example, the Ikanos’ Vx185-HP communications processor chipset implements VDSL2 as well as vectoring and channel bonding in a home gateway (Fig. The Ikanos Fusiv Vx185-HP home gateway chip implements ADSL2 and VDSL2. A MIPS 600-MHz processor is the host. Interfaces include two 1-Gbit/s Ethernet ports, PCI Express, USB 2.0, SATA, and the usual UART, SPI, I 2C, and GPIO ports.

VoIP processing is included. AT&T’s popular U-verse system uses VDSL2. It sends video signals by fiber to a neighborhood DSLAM and then distributes the signal to homes over the installed UTP wiring. The U-verse system provides cable TV-like service with IPTV as well as VoIP and Internet access.

The International Telecommunications Union-Telecommunications (ITU-T) standardizes DSL specifications. The ADSL standard is G.991 and G.992. The ADSL2 standard is G.993 and G.994. ADSL2+ is specified in G.995. The standards G.993.1 and G.992 define VDSL and VDSL2.

The vectoring standard is G.993-5, and the channel bonding standard is G.998.1. Alternate Systems Most consumers use cable TV or DSL for Internet service. However, there are instances where other methods are desirable or necessary. In many areas where new homes are being built, installing fiber-optic cable directly to the home (FTTH) is no more expensive.

For example, Verizon’s FIOS system isn’t widely available but does provide services with typical rates from 50 to 100 Mbits/s. Some rural systems use wireless methods.

Clearwire’s system uses the WiMAX standard (IEEE 802.16) to deliver data rates from 1 to 5 Mbits/s over several miles. For even more remote service, a few companies offer satellite downstream data at rates to several megabits per second. References Broadband Forum: CableLabs.