Wireless Systems Design

What’s New With WI-FI? Better Still, What’s Next?

Wi-Fi is the familiar name for the world's most popular wireless local-area networking (WLAN) system, also known as the IEEE 802.11 standard. Wi-Fi has been around for about a decade, which is a long time (at least in electronics). Now, it has reached that stage where it is so successful, it’s utterly taken for granted.

Most laptops have Wi-Fi, and many home networking systems use it. Many people also have Wi-Fi access at the office. If you want to e-mail or search the Internet from your laptop, you can do it from an airport, convention center, coffee shop, or hotel, with over 100,000 hotspots worldwide. It’s also used in a handful of other applications, such as industrial monitoring and control. With such a successful technology, you have to wonder where it’s going.

11n Knocking On The Door

Perhaps the most agonizing process in Wi-Fi over the past few years has been the development of the 802.11n standard. This latest and greatest version of Wi-Fi uses multiple-input/multiple-output (MIMO) and some other exotic technology to achieve wireless data rates well over 100 Mbits/s. The fastest now is 11g and 11a with 54-Mbit/s maximum rates under optimum conditions. A more typical connect-rate is in the 20-Mbit/s range. Not bad for wireless.

The range is strictly a 100 m maximum and usually much less to get any real speed. For most applications, 20 to 54 Mbits/s is great. But the keepers of 802.11 have been pushing the technology so rates exceeding 100 Mbits/s are available, opening up new applications like video and new chip sales. 802.11n could find its way into home video distribution, a growing segment of the consumer market as high-definition television (HDTV) and digital video recorder (DVR) sales grow.

After years of struggling to reach an agreeable standard, manufacturers are shipping the first chip-sets, and end-products are now available. These conform to what is called the pre-n, draft 2.0 guidelines. This early version of the standard is supposedly 99% of the final 11n standard, which has yet to be fully ratified and blessed by IEEE. Look for that sometime in 2008. In the meantime, chip and modem manufacturers got antsy and launched chips and products to be first to market. Products are rolling out and available now.

The Wi-Fi Alliance, the industry organization that promotes and performs interoperability testing and certification, has agreed to certify pre-n, draft 2.0 products. Many chips and routers have now been certified. Most manufacturers seem to be pretty sure that the draft specs will be nearly identical to the final standard and that no interoperability problems will show up. In any case, the Wi-Fi community is pushing to get more sales sooner despite the excruciatingly painful and slow final approval process for the standard.

Dual-Mode Phones Pulling Up From The Rear

The other hot (if not hotter) new application is a carrier for digital wireless Voice over Internet Protocol (VoIP). The idea is to use standard VoIP but let Wi-Fi carry it. You could make phone calls from your laptop, but more likely you will make VoIP voice calls via a specially equipped cell phone known as a dual-mode phone.

Dual-mode phones have the usual cellular technology plus Wi-Fi and VoIP. Already, several hundred such cell phones are on the market, and the Wi-Fi Alliance has certified 120 of them. Other cell phones include Wi-Fi, but not for phone calls. It’s used for e-mail and Internet access. Apple's new iPhone is an example.

Cellular operators used to hate Wi-Fi and wouldn't have it in their phones because it just might compete with their own voice or data services. But now that they have figured out how to make extra revenue from having cellular plus Wi-Fi, many carriers are moving in that direction.

Both T-Mobile and Cincinnati Bell recently started services for VoIP phone calls. Sprint Nextel is also doing it to some extent, and both AT&T and Verizon are on the way to offering services. That means with a dual-mode phone, you can make your call from anywhere as long as one service or the other is available. Some phones will automatically hand off from one service to the other. Chances are your next cell phone will be a dual-mode phone.

Mesh Metro Networks

Another recent trend is the building of mesh networks with Wi-Fi to cover large metro areas. Hundreds of cities have built mesh networks that give citizens access to the Internet from any part of the city via their laptops or home PCs. Some cities charge for the service, while others do not. While that movement was booming for the past year or so, it has slowed as some cities have experienced less than satisfactory performance. Yet it is a great service and an extension of an already successful wireless technology.

What's Next?

What's beyond dual-mode phones and 11n? Who knows? It’s not likely that we will see 1-Gbit/s Wi-Fi, but you never know. Given the Wi-Fi industry's aggressive nature, it could be next on the list. A study group, if not already in action, is the next step to discovering a way to do 1 Gbit/s wirelessly. It is the way of Ethernet. The wired Ethernet side of the IEEE standards organization (802.3) is already working on a 100-Gbit/s standard over fiber optics.

Can 1-Gbit/s wireless be far behind? Certainly not in the current unlicensed 2.4- or 5.8-GHz bands. Maybe in the millimeter bands. For example, will the Wi-Fi Alliance acquire the recently formed WirelessHD group, which is working on a 60-GHz band wireless standard for the home? Whatever the solution, the bigger question is why we need it. What’s the killer app? As usual, those questions will be answered when the hardware becomes available.

Taken for granted or not, Wi-Fi is still viable and growing. Expectations on all fronts are high. You can bet we will see more in the future. While we may not get the 1-Gbit/s version in the near future (if ever), there will continue to be lots of modifications, enhancements, and extensions to the standard, making it better than ever.

One big event to watch, however, is the rollout of the WiMAX wireless broadband service, which is intended to be an alternative to cable TV and DSL Internet access for areas not served by those services and to provide competition especially in markets like IPTV. This IEEE standard (802.16) is fully ratified in both fixed and mobile versions. Like Wi-Fi, it uses orthogonal frequency-division multiplexing (OFDM) in the 2- to 11-GHz bands. The 2.3- to 2.5-GHz bands will be used in the U.S., while the 3.5-GHz band is more widely used in other parts of the world.

The standard can deliver data rates up to 10 to 15 Mbits/s over a range of several kilometers. It will use cell sites like the cellular-phone industry. Some experts even say the mobile version is a contender for the fourth-generation (4G) cell-phone system. It remains to be seen whether WiMAX will compete with or be a good complement to Wi-Fi. Laptops are expected to incorporate both in the near future. With both Clearwire and Sprint Nextel rolling out initial WiMAX services now and in early 2008, you should watch the action. Whatever the result, we will always be fully connected.

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