Electronic Design

Wireless Communications: The Lure Of Wireless Is Irresistible

Numerous wireless technologies abound to tackle virtually any chore.

Connectivity. Staying in touch. That's what it's all about, and it's addictive. Today, the cell-phone business is a giant, driven by the security-blanket need to always have a phone available, coupled with that instant gratification from contacting someone immediately. Wireless technology makes it possible to conduct business on the road or reach someone in an emergency.

But cell phones are only one piece of the wireless connection revolution. Today, it also covers e-mail and the Internet. Even though we still talk endlessly on the phone, we also e-mail our brains out. In only one decade, e-mail has gone from a tiny niche to the primary way that we communicate in business. E-mail is mostly a wired kind of connectivity, but thanks to wireless technology, you can now e-mail to your heart's content from your laptop, remote PDA, or cell phone. Are we a communicating society or what?

But there's more. Wireless is working its way into virtually every aspect of our business and home life. Wireless PC and peripheral connections, wireless headsets, and wireless local-area network (LAN) connections are the norm. Home networking is no longer just for the wealthy. It's becoming a necessity for us all as we share our PC resources, connect our entertainment equipment, and monitor and control our home functions—with no wires at all.

Wireless clearly dominates electronics today unlike any other killer app. More is going on in wireless than in any other electronic segment, and it's affecting virtually all markets, including enterprise, consumer, and industrial.

Cell Phones Rule Wireless: While cell-phone sales have been down during the past two years, the volume still hovers around 400 million handsets per year, and projections for the future are very positive (Fig. 1). Driving this recovery is the industry's goal of 3G systems that will bring high-speed data applications like e-mail, Internet access, and multimedia to our handsets. But high costs, lack of viable applications, technological issues, and lack of spectrum have slowed this development. Real 3G systems using ITU's IMT-2000 UMTS W-CDMA aren't expected in any volume until 2004, if then.

Meanwhile, the industry is focusing on interim 2.5G systems that add digital data capability to present-day TDMA/GSM and CDMA digital systems. Carriers like AT&T Wireless and Cingular are rolling out GSM systems that include the flexible data transmission capability called GPRS with data rates of up to about 56 kbits/s.

Sprint has announced its next-generation system using Qualcomm's cdma2000 technology. Sprint calls it 3G, thanks to the ITU's rather loose definition of 3G. The cdma2000 1XRTT version's speed potential is up to 144 kbits/s. GSM/GPRS systems are expected to achieve rates as high as 384 kbits/s by adopting EDGE via the GSM/GPRS framework with 8PSK modulation. Qualcomm's EV-DO technology gets you real 3G with cdma2000 up to 2.4 Gbits/s.

One expensive complication for 2.5G and 3G phones is the government-mandated E911 service that makes carriers responsible for installing systems that will accurately tell where every cell-phone user is located within 100 yards of accuracy. EOTD triangulation systems or GPS-based systems should solve the problem.

Finally, the growing complexity of the baseband chips in 2.5G and 3G phones has put more than average pressure on designers to reduce power consumption. Innovative power-management chips and battery technology like the new, small fuel cells are helping to achieve the long standby and talk times demanded by users.

When will we implement UMTS W-CDMA 3G? It's anyone's guess, as carriers try to find data applications and services to support such a massive build-out. With all the 3G delays and 2.5G successes, you must wonder if we shouldn't just skip 3G and go directly to the proposed OFDM-based 4G systems with full software-defined radios.

Wireless LANs... And PANs: Wireless local area networks (WLANs) are by far the fastest growing wireless segment. While the triple-digit percentage increases of the past two years have quickly gone away, WLANs have been a bright spot in this otherwise bleak downturn. Wireless' convenience and flexibility in a LAN is well known. But it took a widely accepted Ethernet standard (IEEE 802.11b) and a tough interoperability certification program (Wi-Fi) to make it successful. Now 802.11b WLAN connections, which are common in enterprise offices, dominate home networking and implement wireless Internet access points.

The 802.11b standard specifies DSSS in the 2.4-GHz ISM band to achieve a data rate of up to 11 Mbits/s at distances up to about 100 meters, indoors and out. The newer 802.11a radio modems giving up to 54 Mbits/s in the 5-GHz band use OFDM, so they are very robust in noisy and multipath environments. But the range is limited to about 100 feet.

Earlier this year, the IEEE standards committee approved the 802.11g standard, which provides a speed upgrade path to 54 Mbits/s for the 802.11b modems in the 2.4-GHz band. Numerous vendors have already announced multiband, multimode chips combining 802.11a/b and 802.11a/b/g.

Right now, the main issue in wireless Ethernet is security. The 802.11b standard provides security as an encryption algorithm called WEP, but many who use WLANs either don't know that it's available or fail to enable it. The IEEE standards groups and some vendors have been working on increased security measures for both wired and wireless Ethernet.

An unexpected application of 802.11b has been the establishment of wireless access points for e-mail and the Internet. These so-called "hot spots" are being installed in airports, hotels, restaurants, and other places where laptops are most likely to be deployed. Even cell-phone carriers are looking at 802.11b as an alternative or complement to 2.5G and 3G cell-phone data access.

In another unexpected effort, some enterprising companies are even building mesh networks of 802.11b transceivers as a way to supply high-speed broadband access to rural communities with no DSL or cable-TV modem service. Internet service is being provided to subscribers within a 12-mile radius.

Wireless Potpourri: Four other wireless technologies are making great progress: Bluetooth, ZigBee, UWB, and RFID. Even short-range infrared (IrDA) still exists. With a stable standard and 2G chip sets under $5, Bluetooth has finally arrived. The most popular applications are wireless cell-phone headsets; links between cell phones, PDAs, and laptops; and wireless PC peripheral connections. The rumored 3-Mbit/s Bluetooth is expected to even further broaden its reach.

ZigBee is a newer technology that like Bluetooth uses the 2.4-GHz ISM band. Designed for greater simplicity, lower power, and lower speed over longer distances than Bluetooth, ZigBee is finding its way into toys, home control, and industrial telemetry and control.

UWB is the esoteric wireless microwave technology that transmits data without a carrier in the form of very short pulses, which produce an extremely wideband signal. A spread-spectrum-like signal results, which is very secure and robust in multipath and noisy environments. Thanks to advances in semiconductor technology and the FCC's recent approval of low-power UWB in the 3.1- to 10.6-GHz band, considerable effort is under way to develop fast (over 100-Mbit/s) WLAN chips and high-resolution, short-range radar for collision avoidance.

An older wireless technology, RFID, is progressing far beyond its initial success in automatic toll collection applications. Advances in chip designs now make RFID a potential successor to bar coding. The cheap passive wireless tags are making it possible to identify, track, and locate shipments, inventory, and critical capital equipment items. It's revolutionizing warehouse, manufacturing, shipping, and supply-chain management systems.

Figure 2 positions all the wireless technologies relative to their range and data rate. Quite literally, there's something for everyone.

Looking Ahead: What's next in wireless connectivity? As always, higher speed is the ultimate goal. But new services are in the works too. Cell phones are going to see the location services activated to our benefit. E-mail and instant messaging will grow more popular with PDA/cell-phone combos. No doubt we will enjoy sending and receiving still digital photos, but not video.

At home, get ready for the wireless blitz. Soon we will have satellite as well as terrestrial digital radio broadcasts. HDTV is on the horizon. The problem of trying to connect multiple TV sets to a single set-top box and cable connection will be solved as UWB wireless links allow us to freely stream video. Wireless connections between DVDs, PVRs, MP3 players, and even speakers will become commonplace.

In WLANs, we will see more enterprise wireless at increasing speeds. Bluetooth connections, from laptops and PDA to PCs, will be standard as will wireless mice and keyboards.

There's no doubt about it. Once you experience the freedom of wireless, you can never go back.

See associated table.

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