Magazine Article | March 1, 2002

Getting Fixed

Source: Field Technologies Magazine

Fixed wireless solutions are becoming more popular for delivering broadband Internet connections. But, can it compete with its wired counterpart?

Integrated Solutions, March 2002

You've probably seen the Circuit City commercial where the husband excitedly explains to his wife and children his homemade plan for creating a broadband connection to their household. Although the commercial exemplifies a residential application of delivering high-speed Internet access, the husband's enthusiasm for this technology is also prevalent throughout the corporate enterprise. However, in the latter case, more and more companies are beginning to seek a wireless solution to this connectivity issue.

Of course, most companies are already familiar with wireless networking, having deployed wireless local area networks (WLANs). But WLANs have their limitations - namely, transmission distance. By their nature, WLANs are designed for indoor use, with access points (APs) acting as the main disseminators of network information. And indeed, the power or 'reach' of access points has improved over recent years, allowing some devices to operate at distances up to 1,000 feet away. But, what if a company wants to connect two separate buildings miles apart? Can a WLAN access point be super-powered enough to reach that distance? If so, what kind of speed will be achieved and will it rival that of a broadband connection?

The Fixed Wireless Alternative
Obviously, when talking about a wireless network spanning a distance measured in miles, the 'L' for local in WLAN begins to no longer apply. Instead, the project turns into a wireless wide area network, or WWAN. In recent years, a hybrid of a WWAN - termed fixed wireless - has captivated the interest of many Internet access providers. Fixed wireless, as compared to other WWAN technologies like CDPD (cellular digital packet data), has a limited geographical range. Radio signals are sent and received from a single base station with a predetermined reach (although multiple base stations can also be connected). Users within the range of the base station receive their high-speed Internet connection via wireless modems attached to a computer or a LAN. The technology is often referred to as point-to-point (PTP) or point-to-multipoint (PMP).

The interest in fixed wireless stems from the problems with deploying its wired counterpart. For instance, installing wired lines in metropolitan areas involves construction issues when spanning streets, railroad tracks, or other buildings. Furthermore, "These lines are often leased and much slower than internal LANs," explained Todd Thiemann, senior product marketing manager for fixed wireless provider Western Multiplex (Sunnyvale, CA). (Editor's note: In January 2002, Western Multiplex announced a merger with Proxim, a Sunnyvale, CA-based wireless networking company. The new company will go by the Proxim name) "Most customers are not aware there are higher-capacity options beyond WLAN networking. Customers desiring to connect buildings or campuses are accustomed to calling the local telephone company for another leased line. They don't realize wireless networking could solve the problem more quickly, more cost-effectively, and with equal capacity and security."

Thiemann explained that security, or backup, is another reason why many companies have already deployed fixed wireless links. But, this is no temporary growth spurt. A study by Insight Research predicts the interest in broadband wireless will continue, reaching $14 billion in revenue by 2006 in North America alone. Compare that number to the $963 million achieved in 2000 and the growth potential of this technology becomes obvious.

Understand Interference and Bandwidth
So, what should an end user look for when selecting a wireless networking vendor? Obviously, capacity is a big concern. Can these networks handle transmitting complex graphic or video files? According to Thiemann, "Wireless networking provides wire-line speeds up to 430 megabits per second (Mbps) full duplex. A typical T1 connection offers just 1.544 Mbps."

Another major consideration for end users contemplating fixed wireless is the choice of frequency. Both licensed and unlicensed frequencies exist and each has its pros and cons. For instance, licensed frequencies must be purchased, adding to the cost of the project. The two licensed bands are termed local multipoint distribution services (LMDS) and multichannel multipoint distribution services (MMDS). LMDS requires a line of sight between points on a network and operates in the 28 gigahertz (GHz) band. MMDS operates in the 2 GHz range, doesn't require a line of sight, and is less susceptible to interference.

On the other hand, the unlicensed frequencies are free and open to the public. The 2.4 GHz band is unlicensed and a common choice for fixed wireless broadband networking. However, this band is inundated with signals, causing significant interference problems that translate to decreased network performance. For example, previously, the topic of delivering high-speed Internet access via "super-powered" WLAN access points was mentioned. These APs operate in the unlicensed frequency bands using 802.11 specifications. Although some systems of this type exist using oversized antennas attached to APs, Dr. Sherin Kamal, VP of wireless networking vendor Solectek Corp. (San Diego) said this is a bad solution. "Users are being courted by cellular telephone companies offering in-building mobility and by indoor laptop IT companies claiming experience in outdoor fixed WANs," he said. "But, these types of networks cause interference in the radio environment and are an inefficient use of bandwidth."

Although, with a fixed wireless network that minimizes interference and maximizes bandwidth, Kamal is optimistic this technology can not only connect businesses, but residential customers as well. "Huge tracts of this country (let alone the world) have no chance of connecting to any net at speeds above a dial-up line. Wireless technology has a staggering potential to reach out where fiber and wire lines have no hope. By shaping air we are connecting people. So, what is the fixed wireless industry waiting for?"