Electronic Design

Communications: Introduction/Optical

Optical And Wireless Lead The Way
Communicate. That's what humans do. We still predominantly communicate face-to-face and in print, but electronics has made it possible to communicate faster, more conveniently, and certainly more broadly. The telephone. Cell phones. Radio. TV. Computers. Today everything is also networked, making it easier than ever to access and share information and other resources. We are without a doubt a communications-centric society.

Communications and networking drive the electronics industry today just as the computer industry drove it for the last two decades. Developments in communications never cease to amaze and benefit us all. The technology evolves as new and improved semiconductor techniques deliver better ICs and as society demands greater ease and convenience in communications.

There's a quest for speed. We will continue to focus on ways to make things faster, particularly faster computers and higher-speed data communications. An instant-gratification-seeking society, we more than appreciate speed. We demand it in everything we do. As an electrical engineer, what will you do if you can't pursue speed increases? In any case, the Pentiums and Athlons will get faster, Ethernet will move to 10 Gbits/s, Sonet will move to 40 Gbits/s, and dense wave-division multiplexing (DWDM) will make aggregated data rates in excess of terabits/s a reality.

In wireless applications, 3G cell phones will push toward 384 kbits/s and up to 2 Mbits/s. Wireless LANs will evolve to the newer 54-Mbit/s standards. We all continue to press for faster broadband Internet connections at home with cable and DSL connections.

Not surprisingly, wireless communications is pervasive. Wires and cables cost money, can fail, and are hard to hide. Wireless' greatness is offset by its complexity and cost. But as volume applications emerge, the price will come way down. We're on this path now, and that bandwagon continues. Look for more wireless Internet and e-mail in cell phones and PDAs, more wireless LANs for our PCs and laptops, and the growth of personal-area networks (PANs) with Bluetooth.

There will be a migration path to the Internet protocol (IP). The Internet made transmission control protocol (TCP)/IP the protocol of choice for data communications. Slowly but surely we're replacing older circuit-switched systems in telecommunications with packet-switched solutions. IP is simpler and more efficient. Use of the newer Internet addressing scheme, Ipv6, will increase as Ipv4 fades. Expect to see increased use of systems that combine the older legacy systems with the newer packet-based techniques. An example is packet-over-Sonet (POS), a method of putting asynchronous packet data on synchronous data networks with virtual concatenation. This will grow in the coming years.

Broadband developments will unlock the power of the Internet. The promise of faster, more efficient IP-based applications won't be realized until a fast broadband connection is available to the home. Today, only about 25% of homes have a fast connection. Cable modems currently dominate and will continue to command the lead thanks to the improved new DOCSIS 1.1 standard. DSL has grown, but it is flat to down right now. Progress depends on where you are and what carrier you have nearby. But DSL will continue to roll out, and the newer versions such as SHDSL and VDSL will make this broadband mode even more attractive.

Wireless broadband is such a tiny niche, it's hardly worth mentioning. But wireless systems like LMDS and MMDS still offer all of these benefits. As soon as carriers solve the line-of-sight (LOS) and self-installation problems and make the price competitive, it will flourish, especially in rural areas where no other broadband technology exists.

As for fiber to the home (FTTH), don't expect to see it in any pervasive way. While FTTH is the holy grail of home broadband, our systems, infrastructure, and its cost don't make it practical right now. The 53-kbit/s modems will continue as a factor in home access for some time. But cable and DSL will keep rolling out, and other broadband options will surely emerge. When they do, expect growth in new services like voice-over-broadband (VOB) telephone services, video on demand (VOD), interactive gaming, and who knows what else.

With all of this communication going on, and so much of it wireless, hackers and terrorists are a growing threat. Security can't remain a lower priority. The security field is a mosaic of solutions, mostly software, but new security chips are becoming available to make it easy to build in security wherever needed. Look for major advances in all areas, including firewalls, encryption, surveillance software, and biotechnology solutions.

See associated figure.

Greater use of dense wavelength-division multiplexing (DWDM) will increase bandwidth and capacity in existing optical networks. Decreased channel spacing to 25 GHz (even 12.5 and 6.25 GHz) and the development of splitters, filters, and other components will multiply capacity again and again.

Rollout of OC-192 (10 Gbit/s) Sonet equipment in WANs and MANs. There's still lots of activity for OC-12 (622-Mbit/s) and OC-48 (2.5-Gbit/s) systems and equipment, but 10 Gbits/s is slowly gaining ground. Sonet growth is expected through about 2003.

The emergence of the resilient packet ring (RPR), an optical ring standard (IEEE 802.17). Finalization of the standards will come by the end of 2002 and first deployment in late 2003 and beyond. It will primarily target MANs but also be useful in local-area networks (LANs) and WANs.

Movement toward more intelligent and flexible networks. Some examples are systems that permit assigning bandwidth on demand and those that offer faster and even automated provisioning.

Ethernet across the board—LANs, MANs, and WANs. 1 Gbit/s is being incorporated in MANs now, but 10-Gbit/s Ethernet is expected in late 2002 and beyond.

Continued movement toward and forthcoming deployment of commercial OC-768 (40-Gbit/s) systems with first production expected in the 2003/2004 time frame. Component developments will move toward a solution to the very challenging chromatic- and polarization-mode dispersion problems at 40 Gbits/s.

Increased integration of optical components into complete modules and equipment. Advances in planar lightwave circuits (PLCs) such as array waveguide gratings (AWGs) and optical add/drop multiplexers (OADMs). Forthcoming optical ICs that mix optical components with electronic circuits using InP and SiGe.

See associated timeline.

Optical Communications Move Steadily Ahead
THE PAST FIVE YEARS HAVE BEEN good to the fiber-optics industry. Internet expansion and increased construction of wide-area networks (WANs) and metropolitan-area networks (MANs) have kept the industry growing rapidly. Dozens of new companies have entered this arena, producing an amazing array of advanced components, modules, and systems to make optical networking faster, cheaper, and more accessible. While the economic downturn has halted this astonishing growth pattern, have no fear. It will return. New developments continue even in this quiet period.

In the coming years, you will see some significant advances. The terabit/s (Tbit/s) threshold has been easily passed, and we're now on the way to petabits/s (1015 bits/s) on a fiber. But can we really create, store, process, and consume that amount of data even though we can now transmit it? You bet.

Even during this economic downturn, the optical fiber industry is still growing, just at a decreased level. With telecom revenues flat to down, optical equipment sales have declined considerably. The building of new long-haul systems, backbones, and other WANs has slowed, but the market for MANs is hot. The trend toward increased data versus voice traffic continues with Internet Protocol (IP) traffic approximately doubling each year. Optical networks are slowly evolving from circuit-switched, legacy Sonet/synchronous digital hierarchy (SDH) systems to packet-based IP systems.

In the meantime, with significantly lower sales and unbelievably low stock prices, the industry is undergoing major consolidation and restructuring. Larger companies are downsizing and even doing spinoffs and divestitures. Smaller companies are refocusing, repositioning, and retrenching. Many have folded completely. With so many new small companies chasing so few big customers, the trend is to merge and/or acquire to reposition for the forthcoming turnaround. The industry's overall goal is still to bring additional bandwidth increases over longer distances at lower costs with new optical technology.

Improved lasers for 10 Gbits/s, 40 Gbits/s and DWDM. Advances in vertical-cavity surface-emitting lasers (VCSELs) for high-speed/short-range applications and tunable lasers to facilitate channel selection.

Significant growth in MANs. Sonet is being replaced with 1-Gbit/s Ethernet and ultimately 10-Gbit/s Ethernet or resilient packet rings (RPRs).

Progress toward the all-optical network (AON) and the passive optical network (PON). New switches, amplifiers, and other optical components promise lower cost, rapid provisioning, bandwidth management, and protocol transparency without the need for optical/electrical/optical (O/E/O) conversion. PONs will help promote and facilitate the potential of fiber to the home (FTTH) for the ultimate broadband connection.

See associated timeline.

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