Q: What is bandwidth? And, by the way, what’s a gigabit?
A: In a network, bandwidth (what engineers call bitrate) is the ability to carry information. The more bandwidth a network has, the more bits of information it can carry in a given amount of time (Each “bit” is a 0 or a 1 – the smallest unit of information). Networks with high bandwidth tend to be more reliable because fewer bottlenecks disturb the flow of information and because the information flows through the network in less time, reducing the chance a disturbance will happen during the trip. These days, many fiber networks are being designed to provide a gigabit (one billion bits) per second to users who need it. In fact, some 2 gigabit per second (2 Gbps) and 10 Gbps systems are deploying now. In a 1 Gbps network, a two-hour video can be downloaded in as little as 16 seconds, and the images will be perfect.
Q: How much bandwidth – or information delivered by bandwidth – do we need?
A: The amount of bandwidth we need grows every year. Worldwide Internet traffic roughly doubles every two years and has increased even faster lately because of smartphone use. The biggest growth has been for video – traditional pay TV, over-the-top or Internet-based video, and video communications. By the end of 2013, network equipment vendor Cisco noted that traffic had reached levels not expected until 2020 – seven years ahead of schedule. Video requires not only extra bandwidth but also extra reliability. The smallest delay in data transmission can result in distorted views. More video is available than ever before, and people are watching video on more screens at once. In addition, video formats are becoming more bandwidth-intensive. HDTV can require 8 megabits per second (Mbps) or even more for fast action, such as in sporting events, with MPEG-4 compression technology. So-called 3D immersive HDTV – already used in some academic and industrial settings for telepresence – requires between 50 Mbps and 300 Mbps. 4K video, which has four times the pixels of today’s best quality HDTV broadcasts, requires 16 to 32 Mbps even with new HEVC compression technology, depending on how fast the screen action is and how much of the screen is taken up by fast-moving objects. Virtual-reality (VR) video is now becoming readily available, not just for movies but on Internet news sites. VR adds visual information to each frame, making possible multiple alternative views, and thus can vastly increase file sizes and bandwidth requirements.
Q: What about other kinds of data?
A: Bandwidth requirements for many kinds of data are exploding. For example, think about uploading photos to a cloud storage facility such as iCloud. Digital cameras can create larger and larger images; 30 megabytes is not uncommon. Amateur HD video cameras use about 10 gigabytes per hour of video – the equivalent of 300 of those 30 MB still images. Voice-activated searches on Siri, Google Search and Cortana take more bandwidth than text searches, and they require near-perfect transmission to be decoded by supercomputers at data centers (no, Siri doesn’t live on your phone). When voice search becomes the norm, as it soon will, upstream bandwidth will be saturated quickly. In health care, the medical images produced by equipment such as CT scanners are easily a hundred times larger than camera images. Business and science have both entered the era of big-data applications that collect and analyze data on massive scales. Today’s big-data applications range from consumer pricing models to DNA sequencing to particle physics to control of electrical grids. Big data doesn’t work without big bandwidth. A DNA sequencer produces enough data to monopolize a 3 Gbps connection.
Q: Can’t copper carry high bandwidth?
A: Copper’s capacity is far less than fiber’s. It can support high bandwidth for only a few hundred yards. The longer a signal travels on copper, the lower the bandwidth. That’s true for even the newest copper-based technologies such as G.fast and vectored/bonded VDSL. G.fast starts out with more bandwidth over very short distances, but older technologies such as DSL catch up within 1,000 feet. Optical fiber is unique in that it can carry high-bandwidth signals over enormous distances. Fiber uses laser light to carry signals. Under some circumstances, a signal can travel 60 kilometers (36 miles) without degrading enough to keep it from being received. The international minimum standard is 20 kilometers (12 miles). Fiber is also far better able to support upstream bandwidth – that is, from a user to the network.
Q: What’s the difference between upstream and downstream bandwidth, and why is it important?
A: In the debate about fiber-to-the-home versus copper-based broadband, people tend to argue in terms of downstream bandwidth because most users have needed more downstream bandwidth than upstream – especially for bringing video entertainment into their homes. But emerging consumer uses such as voice-activated search and dictation, home video uploads, cloud storage, distance learning, video communication and telemedicine may require as much upstream bandwidth as downstream. Small businesses, often home-based, may need upstream bandwidth as well – consider a wedding photographer sending proofs by email to clients. Businesses now often copy all their working data files to a remote computer center for safekeeping.
Q: What about wireless? I hear 4G wireless can provide 54 Mbps. In Singapore, there’s a wireless carrier boasting 300 Mbps!
A: That’s the potential bandwidth shared by all users connected to a cellular antenna. A wireless user might get high speeds for a moment or two if no one else is around, but average wireless speeds, even for 4G, are similar to those for DSL. Wireless broadband depends on fiber to move information to and from cell towers. Even so, each antenna can support only a finite number of cellular signals. Cellular data traffic grew 300-fold from 2006 to 2013 and will grow another sixfold by 2017. Providers severely limit wireless data, encouraging or forcing customers to use Wi-Fi connections instead of cellular networks for data. Those Wi-Fi connections, in turn, work best when they can quickly offload data to a fiber network. A typical cellular data plan allows 3 to 5 gigabytes per month. Use your phone to view video, and you quickly run over the limit. Over a gigabit fiber line, 5 gigabytes would take just 40 to 50 seconds to download! So a typical phone’s monthly data limit is 1 minute peak usage on an fiber-to-the-home connection. On the other hand, point-to-point wireless links, typically using so-called “millimeter wave” antennas, can be very useful to extend a fiber network to serve a specific neighborhood or building. That kind of wireless is not cellular. Each user gets much of the total bandwidth potential of the transmission link. Once bandwidth needs require an upgrade to fiber, the wireless link can often remain in place as a backup.
Q: What exactly makes fiber “future proof”?
A: The equipment used to send light signals over optical fiber keeps getting better. So equipping an existing fiber network with new software and electronics, and with lasers that pulse light faster, or lasers that use different wavelengths of light, can vastly increase available bandwidth without changing the fiber itself. New electronics are very cheap compared with the original cost of laying the fiber. At the customer end, the system can be designed so that customers themselves can simply pull an old unit out and plug a new one in. Therefore, once fiber has been deployed, network operators can keep increasing bandwidth as needed at very little cost. Q: How long has fiber optic technology been in use? A: Fiber optic cable is the foundation of the world’s telecommunications system. It has been used for more than 30 years to carry communications traffic from city to city and from country to country. Almost every country has some fiber optic cable, delivering services reliably and inexpensively. The first time fiber delivered a signal directly to a home (in Hunter’s Creek, Fla.) was nearly 30 years ago.
Q: All providers seem to claim they have fiber networks. What’s different about fiber to the home?
A: Don’t be fooled! It is true that most cable and FTTN (DSL) networks use fiber. In these networks, the fiber carries the signal close enough to homes so that copper can carry it the rest of the way. However, this approach requires expensive, difficult-to-maintain electronics at the point where fiber meets copper. These electronic devices use a great deal of power and are quite sensitive to lightning strikes. Even the cost of bringing electric power to them can be huge, depending on where they are located. The available bandwidth is far less than in an all-fiber network. And most of these halfway approaches do not allow symmetrical bandwidth – cable and DSL systems generally can’t upload information as fast as they can download it. Q: Isn’t a network with some fiber good enough? A: It may be fine to send emails, download songs or share family photos. If you want to log on to the corporate LAN from home and work effectively, or run a home-based business, you’ll need more. If multiple people in your household are using the Internet at the same time, you’ll need more. And what about uploading a high-def video of your child’s football game, or sitting down to dinner virtually with family members a thousand miles away?
Q: Why does it matter how close to the home fiber comes?
A: With copper cable, bandwidth drops precipitously with distance. Vectored DSL allows 50 Mbps downstream for as far as 1,800 feet under ideal conditions, though it won’t work on very old copper wiring, its upstream bandwidth is limited and it requires expensive electronics. However, it is touted as an interim solution for network builders that cannot afford fiber-to-the-home. A new technology, G.fast, under ideal conditions and with vectoring (crosstalk cancellation) and bonding (simultaneous use of more than one pair of copper wires), can provide 500 Mbps symmetrical bandwidth up to 300 feet from a fiber node. G.fast may prove to be an excellent solution for retrofitting apartment buildings with fiber to the basement (as long as those buildings already have good internal copper wiring), but it requires bringing fiber very close to customer premises and is still limited in comparison with true fiber to the home.
Q: With cable and DSL, there’s often a gap between advertised and actual bandwidth. Is that true for fiber?
A: No. Cable, DSL and even wireless networks are usually heavily oversubscribed – that is, providers promise users more than the total amount of available bandwidth because they know not all users are going full throttle most of the time. As a result, networks slow down during periods of heavy use, such as when teenagers come home from school. Copper networks are also more subject to speed degradation due to the condition of the wiring. Fiber has enough bandwidth and reliability that providers can guarantee high speeds with little or no over-subscription. If a fiber network is designed properly, users will always get the speeds that are advertised – or better. Data published by the FCC in June 2014 showed that, on average, fiber-to-the-home services delivered 113 percent of their advertised speeds.
Q: My cable company says it can deliver fiber all the way to my home. Is this possible?
A: Yes, using any of several methods, including a new technology called DOCSIS 3.1. That technology can indeed handle fiber-to-the-home, although FTTB systems are more common. In addition, cable companies have seen fiber’s light. They are installing new electronics to bring more bandwidth to existing DOCSIS nodes – the spots where the fiber signal is normally converted to travel over “coax,” short for copper (or aluminum) coaxial cable. In addition, the DOCSIS nodes can be split, so that each node handles as few as 20 or 30 homes, instead of the old industry standard of 500. Cable companies are beginning to offer reliable 2 Gbps download speeds in some locations. But customers have to know exactly what flavor of DOCSIS 3.1 they are getting, to be sure it is fiber-to-the-home.
Q: Is fiber-to-the-home technology expensive?
A: In new construction, fiber costs about the same as copper to build, and it costs much less to operate and maintain. Building fiber to the home is expensive only when compared with not building a new network – that is, with making minor tweaks to an existing copper network. The problem is that these less-expensive solutions don’t meet users’ needs. In the last few years, the flood of video content has outrun the ability of older copper technologies to handle bandwidth demands. In many parts of the world, providers shut off or slow down service or impose prohibitive fees for customers who exceed monthly data caps. Customers don’t like these restrictions, and they don’t appreciate being called “bandwidth hogs” for using services they have paid for. In addition, it’s not clear that providers save money by failing to meet users’ needs because limiting bandwidth means limiting revenue potential as well.
Q: Is lightning a problem with fiber?
A: No. Because fiber does not conduct electricity, lightning strikes do not directly affect fiber at all. Fiber does not have to be grounded.
Q: Is fiber-to-the-home a sustainable technology?
A: Glass is made from sand – an inexhaustible resource that uses far less energy and creates far less pollution to manufacture than does extraction of copper from its ore. fiber-to-the-home generally consumes less power than other broadband technologies. Passive optical networks (GPON and EPON) are especially energy-efficient because they require little or no active electronics in the field. fiber-to-the-home enables more sustainable lifestyles, too. A 2008 study by PricewaterhouseCoopers showed that the greenhouse gas emissions associated with deploying an fiber-to-the-home network are outweighed within five years by the savings from increased telecommuting. Other fiber-enabled applications, such as telehealth, telepresence, distance learning and cloud computing – and, of course, smart-grid applications and home energy management – reduce travel, minimize heating and cooling loads or help shift energy consumption to renewable sources.