Unfurling wireless mesh

New gear expands coverage of wireless networks, but proprietary products prevail

The port city of Corpus Christi, Texas, has attached 300 wireless access points to traffic signals, streetlights, water and radio towers, and buildings to provide a blanket of IP network access across 24 square miles. Within five years, city officials plan to expand that to 1,600 wireless access points spread across 147 square miles.

The Corpus Christi network uses wireless mesh technology, a newer and more versatile version of the popular Wi-Fi gear that creates wireless hot spots. It promises to help public works crews, police officers, and fire and rescue squads communicate and access information, such as real-time video, city maps and inventory. Schoolchildren will also be able to use the network to access the Internet and keep in touch with teachers, and Internet service providers will resell it as wireless broadband connectivity to businesses, residents and visitors.

Wireless mesh networks have become more popular lately because they solve problems that arise when applying conventional Wi-Fi gear to cover large areas.

With Wi-Fi, the access point uses radio frequency signals to provide laptop computers or other devices with a wireless connection to the Internet or private network. Because Wi-Fi radio signals typically only extend several hundred feet, multiple access points are necessary to cover large areas. The problem is that every access point must connect to a wired network — the backhaul — typically via an Ethernet cable. The backhaul wiring can be expensive and difficult to deploy. In comparison, not all wireless access points in a mesh network need a wired backhaul connection. At least one access point needs a wired connection, but that unit can then communicate with other access points via radio signals, forming a wireless backhaul that hops from one access point to another.

“We call it wireless wireless,” said Michael Disabato, a service director at the Burton Group, a research and advisory services firm. “Other than getting a power connector to an access point, you don’t have to worry about running cable.”

That means a wireless mesh network can span miles without any wires, thus reducing the costs and complexities associated with many wireless networks that cover large distances.

The technology’s potential has attracted numerous vendors to the market, although users must proceed carefully because the products employ some proprietary technology and industry standards are still at least two years away.

Wireless proliferation

Leonard Scott, Corpus Christi’s management information systems business unit manager, considers wireless mesh technology a revolutionary new infrastructure comparable to that of the telephone networks and other public utilities that modernized towns and cities decades ago.

“We look at wireless data and broadband access as the new infrastructure, and we feel that if we would say no to it, that’d be like a city in the 19th century deciding not to build a water system or a road system,” Scott said.

Other municipalities apparently agree. Philadelphia, among the most notable, is planning to build an estimated $20 million wireless mesh network. San Francisco; Mountain View, Calif.; Tucson, Ariz.; Providence, R.I.; and several other cities have similar projects under way.

Many public safety and other government agencies will use those wireless networks to improve communications and provide mobile access to information. Among other applications, Corpus Christi will use its wireless mesh network, built with Tropos Network’s gear, to automatically collect water and gas usage data from about 100,000 meters.

Other municipalities are building wireless mesh networks to boost economic development and provide more affordable Internet service to businesses and residents. That’s what the rural community of Marshalltown, Iowa, is doing. The city is known for its historic downtown, earning a place on the National Register of Historic Places. But city officials wanted to add technology to attract new investments and retain current businesses and residents.

“We wanted to prove that better-quality Internet access does lead to better jobs and better economic development,” said Mike Miller, chairman of the Marshalltown Economic Development Impact Committee, a volunteer organization charged with improving economic development in the region. Miller is also a vice president at Racom, the systems integrator Marshalltown chose to help install its wireless mesh network, built on equipment from Nortel Networks.

Marshalltown officials evaluated different options, including fiber-optic cable, to network its downtown area and determined that wireless mesh technology would provide the capabilities they wanted for less money.

“Fiber would have cost us anywhere from $1,500 to $2,200 dollars per business in the downtown area,” Miller said. “When you are talking about a 20-square-block area with several hundred businesses, you are talking quite a bit of money.”

The wireless mesh network cost the town about $35,000 for equipment, installation and advertising. Tax dollars covered half of the costs while private donations paid for the other half. Analysts agree that wireless mesh networks can be more cost-effective than wired networks. Because they require less backhaul cabling, they can also be less expensive to deploy than standard wireless networks, even though the mesh access points can cost hundreds if not thousands of dollars more than standard wireless equipment.

“The mesh access points are typically more expensive because they often have multiple radios and can work outside because they have to be more tolerant of hostile environments,” Disabato said. “But with a large installation, the costs may be lower because you get rid of the cable and you get rid of any labor costs to install it, which isn’t cheap.”

The Marshalltown network debuted in June 2005, and the city tested it for three months. It originally consisted of seven Nortel 7220 WLAN Access Points supported by a Nortel Wireless Gateway 7250, which serves as the base station for the wired connection to the Internet. The residents have been so happy with the network — Miller said at least three businesses lease space in the downtown area partly because of the free wireless Internet access — that officials plan to expand it across the entire city, which is approximately 18 square miles.

The network will eventually include about 20 access points covering 40 blocks, including at least four at Iowa Valley Community College. To pay for the expansion, which Miller said could cost as much as $1 million, Marshalltown has partnered with a local cable company, MediaCom USA, which will offer the wireless broadband Internet services to residents and businesses.

Market simmers

The wireless mesh network technology market has well-known vendors, such as Cisco Systems, Motorola and Nortel, and smaller companies, including BelAir Networks, Firetide, Strix Systems and Tropos, vying for attention. Cisco is the most recent entrant, launching its mesh offering in November 2005 after acquiring the technology from Airespace earlier that year.

Analysts expect the market for wireless mesh access points to grow from $33.5 million to $974.3 million between 2004 and 2009, according to the market research firm In-Stat.

Most of the vendors offer devices that support 802.11 Wi-Fi standards and operate in the unlicensed 2.4 GHz and 5 GHz frequency bands. But all the current offerings use some proprietary technology because 802.11 doesn’t natively support mesh topologies.

The Institute of Electrical and Electronics Engineers is working on 802.11s, a standard for linking mesh access points, but it’s unlikely to become a final specification before mid-2008. Two variations of the standard are currently under consideration.

Without a standard, different products won’t interoperate, and buyers will have to stick with vendor-specific implementations.

Many vendors say they plan to support the mesh standard when it’s ready. “It will be relatively simple for any of our solutions to support 802.11s,” said Ben Gibson, director of wireless and mobility marketing at Cisco. “We are highly engaged in the standards process, and we have a clear dedication to standards support.”

Another difference among the various vendors’ wireless mesh equipment is the number of radios in each access point. That number can affect bandwidth and price. For example, BelAir sells both single and multiradio systems, while Strix has a chassis-based system that can support as many as six radios in a single access point.

“You can slide the radios in and out, so when new technology comes along, you don’t need to do a forklift upgrade,” said Nan Chen, vice president of marketing at Strix.

For some, wireless mesh networks are already proving their worth. In Ripon, Calif., which spent about $550,000 to install Motorola’s Motomesh technology, the network of 50 access points, 25 IP wireless cameras and mobile cameras installed in police cars has already caught its first criminal. Last month, cameras on the mesh network recorded an adult male beating a child and stealing his skateboard. The victim called 911 and gave details of the assault and the suspect’s description. The dispatcher accessed the wireless cameras near the skate park to locate the suspect and track his moves. The dispatcher summoned the police, who made an arrest within minutes.

“It was one of those things where you see how the technology works, and that it really does make a difference,” said Richard Bull, Ripon’s police chief. “I’ve heard some people say this network is kind of a ‘Big Brother’ thing. But it isn’t. We are trying to protect our community in the best way we can.”

Bacheldor has nearly 20 years of journalism experience, much of that covering information technology.

New-age utility meets old

Corpus Christi, Texas, is becoming unwired. It’s already using a wireless mesh network that spans 24 square miles to support police officers and fire and rescue employees.

Public works officials can wirelessly tap into the city’s geographic information system to retrieve maps that pinpoint pipe infrastructure in the event of a water main break.

Building inspectors can also use the system to shorten the building permit process from a month or longer to one day, ultimately cutting as much as 25 percent of the time it takes to build a house.

“A lot of cities are looking at [wireless mesh networks] to solve one or two problems,” said Leonard Scott, Corpus Christi’s management information systems business unit manager. “We are going to use it for everything.”

That includes a $23 million, five-year project to build an automated meter reading system that will link to the city’s wireless mesh network and an existing fixed fiber-optic network. The city is equipping nearly 100,000 water and gas meters with radio frequency identification-based mobile equipment that will communicate with 200 collection points citywide.

“The meters wake up twice a day and squawk their readings randomly and are picked up by the collection points,” Scott said. The collection points then send the data to both the wireless and wired networks, which transfer the information to computers at City Hall.

Instead of monthly readings done manually, the automated meter reading system will let the city more closely monitor gas and water consumption by checking data daily or even more frequently.

Radio radio

The simplest, least expensive wireless mesh network comprises access points with only one radio each. In this scenario, the access point’s one radio performs double duty. On one side, it communicates with wireless clients such as laptop PCs, video cameras or other wireless-enabled devices, and on the other side, it talks to other access points, forming the wireless backhaul that eventually taps a wired connection to the Internet or private network.

Unfortunately, with this setup, the different communications share bandwidth, resulting in degraded performance at times. In addition, single-radio systems can only transmit or receive at any given time, which also affects throughput.

Adding a second radio in each access point allows users to deploy bigger mesh networks serving larger areas. In this scenario, one radio in an access point is for client access. The second radio transmits and receives data from the access points. This segmentation results in more efficient operations, thus allowing larger deployments.

A third option is a multiradio system, such as those offered by BelAir Networks and Strix Systems. Those access points can offer one or more radios for communications with clients, and two or more radios for communications among the access points (for communications between access points, one radio can transmit while the other receives). The added radios boost performance and are well-suited to networks spanning very large areas.

Analysts say single- or dual-radio systems can often provide the performance needed in many installations. Multiradio systems are more complex and expensive and therefore, “are still not

a silver bullet,” said Ellen Daley, vice president and research director at Forrester Research. “But these systems get you more bandwidth using a clever technique.”


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