Mixed bag of mesh helps scientists master the arts

Toronto’s plans for a business-grade wireless network include consistent quality of service that will support voice. As the project gets under way in the financial hub, engineers are discovering there’s more to the mesh than building it.

The masterminds behind Toronto’s city-wide wireless network are making up for lost time, plugging in stop-gaps and pulling off little tricks of ingenuity to move their ambitious plans off the drawing board and out into the field of deployment.

They say mesh wireless comes in various flavours, and they have a mixed bag to choose from. Technology upgrades won’t be giving them any headaches, and there’ll be no migraines or brain tumours caused by electromagnetic frequency emissions.

The network architects at Toronto Hydro Telecom Inc. (THT), the utility telco that’s taken on the task of building voice-quality Wi-Fi across the city in three years, say their heads are clear about complying with future wireless standards and equipment interoperability.

Instead, a collusion of red tape, ambient lighting, photo cells and kiddie pornographers has blurred the timelines for unwiring the city.

The aim was to have had the financial district – bounded by Front and Queen Streets between Spadina Avenue and Jarvis Street – covered by the end of this month. After a series of setbacks, building has begun in the area around City Hall and Sharyn Gravelle, THT’s vice-president of wireless, remains confident of an initial launch this summer.

Engineers are still looking for ways to work around two potential snags. There aren’t enough streetlights on the city’s main streets and the power isn’t always on along many of the side streets.

According to David Dobbin, THT’s president, the utelco has an agreement with Toronto Hydro Street Lighting Inc. to attach the wireless access points and antennae to the streetlight poles.

In some areas of the city, however, like Dundas Square and the Eaton Centre, there are no street lights because the density of retail stores and large advertising screens gives off more than enough ambient lighting.

“When you look at a map of Toronto, it seemed obvious to build the lines of coverage along the north-south grid, but some of those north-south streets just don’t have any lights,” says Dobbin. “So instead of a north-south configuration, we have to go east-west and use the corner points of side streets to provide access to streets like Yonge, University and Spadina.”

The access points will also rely on the streetlight grid for its power supply. The only problem is not all streetlights have 24×7 power supply.

Most streetlights have their own photo sensors, which are used to automatically turn the lights on and off by measuring the light of day, says Dobbin. “But large sections of Toronto are on controlled circuits, where one photo sensor controls all the lights on that street, and they’re only getting power half the time.”

Finding the right equipment vendor was the first major step, says Dobbin. After that, two contentious and politically-charged issues came up that stalled the network’s building and implementation.

“We felt it was very important to make sure we got the right equipment,” says Dobbin. “We made sure that we future-proofed ourselves and really built something for the future. We’re building this once and we have to build it right.”

Gravelle is impressed with the roadmap for the products offered by Siemens Canada and Ottawa-based BelAir Networks. “The equipment is fully compliant with all existing standards, and their product evolution allows them to do a number of different upgrades for the standards that will come into effect.”

The networking gear can be upgraded with either software or firmware cards and it’s all based on non-proprietary technology, says Gravelle. “We did all our research up front, and we really looked at what we want to offer. We’ve designed this network for voice capabilities.”

According to Dobbin, upgrading the units to provide PCS (personal communications service, a radio frequency for mobile phones) can be done with a card, and so can upgrading to WiMax or MIMO (multiple input, multiple output), an antenna technology that has the potential for gigabit throughput over Wi-Fi.

Siemens and BelAir sell a range of radio equipment that can be configured in various forms of mesh topologies, either point to multipoint, multipoint to multipoint or multiple point to point, she says.

“The term mesh is used quite liberally, but there are several different kinds, and one is not necessarily better or worse than the other,” says Gravelle. “They’re very specific to the application you’re trying to do, and what service you’re looking to offer.”

Different types of radio, dual-mode and multi-mode, offer design flexibility, says Gravelle, and there’s a choice of uni-directional and omni-directional antennae to provide coverage over different types of terrain.

“In a wide open area, you’d use a single, omni-directional antenna for a bubble of coverage,” says Dobbin, “but downtown, with all that high-rise concrete and glass, you need multiple antennae.”

Ian Collins, THT’s vice-president of operations, says coverage is an art, not a science.

“Things do change, so you need an arsenal of antennae and apparatus. If you have to use the same radio for everything, you can waste a lot of coverage, so it’s good that BelAir puts those options in your product bag,” says Collins, who deployed a type of mesh Wi-Fi in the Hamilton-Wentworth region last year.

Dobbin maintains the tricky part is not building the network, it’s putting in the back-end systems to run the network. “Authenticating it, billing it and serving it are much more complicated,” he says.

Two big stumbling blocks for THT were coming up with a stop-gap user authentication system and dealing with the city’s stringent health and safety standards for electromagnetic frequency emissions.

“Before we started deploying, we had to have authentication and tracking systems in place for the network,” he says. “This was a huge issue and it hit us like a brick wall.”

The network hardware and management software, from BelAir and Siemens, does provide user authentication and billing systems, but Dobbin says THT had to come up with an alternative while the service was free. THT is offering free access to the network until the end of this year while it builds out the rest of the downtown area, extending north to Bloor Street.

Dobbin says he became aware the network could be abused as a “city-wide playground for kiddie pornographers,” without the appropriate authentication system in place. “You have to be able to track them, know who they are and where they are, to be able to help the police.”

For privacy concerns, there’s a distinction between authentication and tracking, says Gravelle. “Authentication enables tracking if there is a belief of any illegal activity. We need to ensure that free access does not mean it’s not authenticated,” she says.

Until users can be authenticated through their credit card transactions, THT is using SMS text messaging technology from South African company Clickatell to identify users by their cell phone numbers.

Dealing with the city’s chief medical officer of health over acceptable levels of electromagnetic frequency emissions was another time-consuming exercise. According to Dobbin, the Toronto Board of Health has proposed stipulations that are 100 times less than those laid down by the federal government.

“There’s a very small group of people who believe they’re negatively affected by electromagnetic frequencies,” says Dobbin. “It’s a very contentious issue, though, because we’re talking about putting Wi-Fi on residential streets.”

THT had to conduct a number of radio frequency measurements and engineering studies, and Dobbin says the levels are now 3,000 times less than a cellular tower and well below the Toronto Board of Health requirements.

Collins says the electromagnetic field is highly localized, and drops off to negligible levels within three to five metres from the source.

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