Over the past century, we’ve wired and rewired the world countless times, evolving from copper cable to fiber optics and beyond. But this cycle will soon come to an end as rapid-fire wireless innovations consistently deliver faster, cheaper, and more reliable communication.
ONE TREND AT A TIME
The telephone business is still mostly wired, but the cell-phone phenomenon continues to chip it away. The balance may in fact shift drastically, now that cellular service has passed wired phone service in terms of number of subscribers. And let’s not forget the wired to cordless phone movement inside the home. I’ve never seen any figures, but I would guess that more than half of all home phones are cordless.
The next frontier in communications, computer networking movement, began in the 1970s with wired systems. Long-distance networking used domestic telephone lines with 300- and 1200-baud modems and special “fast” dedicated 56-kbit/s lines. Local-area networks (LANs) were invented later. Ethernet came along in 1973 using the large RG-8/U coax cable, which was followed by smaller cables like RG-58/U. Finally, unshielded twisted pair (UTP) first served as telephone wire before improved versions like CAT5 and CAT6 became the norm.
The LAN trend is now wireless. It started with the 802.11 standard in the 1990s, but didn’t take off until 802.11b arrived around 1997. Quickly after that, we got the faster 11a and 11g versions. Today, the super-fast 11n version dominates.
Wired Ethernet networks haven’t disappeared, they just got faster—first 100 Mbits/s, then 1 Gbit/s, and today reaching 10 Gbits/s. The faster versions consist of fiber, though wireless is still the trend. As enterprise networks expand, the extensions are wireless for greater flexibility and convenience. Work continues within the IEEE for even faster wireless LAN links.
Wireless reigns in home networks. Early home net adopters went for UTP Ethernet and other wired technologies like cable TV coax, powerline, and phone-line systems. Some of them are still around, but better than 80% of all home PC networks use Wi-Fi. While 11n can deliver up to about 300 Mbits/s over 100 m in a home or enterprise environment, a faster version beyond 1 Gbit/s is the goal.
Incidentally, Wi-Fi gave us something else: broadband wireless access through hotspots. When we’re in hotels, airports, cafes, convention centers, and other public places, we can easily connect to the Internet for e-mail and other applications with our laptops. You can even connect via a cell-phone plug-in card in your laptop. All laptops today come with Wi-Fi built in, and soon many will include WiMAX, making broadband wireless available in most major cities.
Wired remains solid in metropolitan-area networks (MANs) and wide-area networks (WANs), which are mostly fiber anyway (see “Wired Won’t Go Down Without A Fight” at www.electronicdesign.com, ED Online 19068). Fiber is super-fast, and lots of unlit fiber is still available. Fiber networks will continue to form the backbone of our connectivity, especially to the Internet.
But wireless trends are making their mark within MANs. Wireless links using microwave and free-space optical systems are already in use. Even faster links should emerge as equipment is developed for the millimeter bands.
And consider the most common wired MAN of all—the cable TV network. Its main distribution uses fiber and then drops to homes by coax. Most homes get their TV by cable, and most high-speed broadband Internet access in the U.S. hooks up via cable systems. Now we’re seeing WiMAX broadband wireless technology begin to attack this market.
WiMAX promises a high-speed wireless Internet connection to rival cable TV and DSL services as carriers like Clearwire, Sprint Nextel, and TowerStream roll out their new systems. WiMAX won’t kill the wired systems, but it brings needed competition, and rural areas with no broadband service can join the 21st century. We may even get Internet Protocol Television (IPTV) this way.
The cell-phone world was all voice until the late 1990s and early 2000s. That’s when data services and the so-called 2.5G period arrived. GPRS was added to GSM TDMA phones, and 1xRTT was added to cdma2000 phones. EDGE and EV-DO came later with higher speeds.
Since then, we’ve moved into the 3G era with WCDMA on GSM networks, which have been further updated with EDGE and HSDPA/HSUPA/ HSPA+. In the cdma2000 world (EV-DO), Rev. A has been added. Future 4G services will use Long Term Evolution (LTE) and, less likely, Ultra Mobile Broadband (Fig. 1). WiMAX will see a parallel path worldwide, though it isn’t expected to play a role in cell-phone service in the U.S.
Consider another cellular trend. Today, more than 200,000 of the cell-phone sites in the U.S. use a wired backhaul system to the main telephone system. That technology, the popular T1 digital line, carries 24 calls. Increasing subscriber capacity and expanding cell-phone data use requires more and faster backhaul.
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