Upstream Downstream

By Paula Bernier

While DSL and T1 appear to be the most prevalent backhaul methods for Wi-Fi to date, companies and organizations offering Wi-Fi can choose from a range of backhaul options - satellite, broadband wireless, IP VPNs and VDSL - that vary in price, performance and compatibility with the application.

“We’ve been working with several customers that are now rolling out Wi-Fi hotspots - enterprises, restaurants, etc.,” says Roark Pollock, senior product manager with MegaPath Networks Inc., which sells a variety of services including T1 and fractional T1, DSL, cable modem service, DS3 and satellite in North America. “We meet with them about what type of access needs they have and bandwidth requirements they have based on forecast usage. Will a simple DSL line be sufficient, or do they need fractional T1 that they can upgrade over time to a full T1 service? The biggest piece is figuring out what bandwidth they need. We help them with that based on users they expect to have simultaneously. Usually you plan on the peak. On average, if you can get a full DSL service - up to 1.5mbps of service - then you’re typically good for most applications.”

Symmetrical DSL offering 1.5mbps in each direction usually sells for about $300, while ADSL with 1.5mbps downstream and 384kbps upstream generally costs from $90 to $110 a month, Pollock says. “A huge portion of your traffic is download traffic, so sometimes ADSL is a viable option,” he says. “For restaurants it might be a good option because you might not expect more than a handful of people at any one time using the service.” In a hotel, traffic might be heavier, so a symmetrical DSL backhaul option might be the better choice, he says.

VDSL, very high bit rate DSL, even has been used for Wi-Fi backhaul. SBC Communications Inc. opted for VDSL backhaul when it set up 10 FreedomLink Wi-Fi hotspots and 29 SBC Yahoo!

DSL wired Internet connections at the EDS Byron Nelson Championship golf tournament this May in Irving, Texas. At the event, FreedomLink hotspots delivered high-speed Internet connectivity to corporate hospitality tents and surrounding areas on the golf course, enabling attendees to check tournament scores and other data on the Internet and to connect with their offices via Wi-Fi. The carrier used VDSL connections, powered by technology from Telco Systems, to link hotspots and the SBC communications operation center at the tournament.

Fiber is another option for Wi-Fi backhaul. In fact, BelAir Networks recently introduced the Wi- Fi industry’s first optical line interface module for infrastructure equipment, allowing for a direct connection between BelAir’s metro-scale Wi-Fi networks and existing fiber networks. The equipment provides up to 164mbps wireless backhaul and full 11mbps end-user access.

Of course, DSL and fiber aren’t always available where Wi-Fi access point hosts need it, or DSL might not be available at the required speed in a particular location, notes MegaPath’s Pollock. In that case, the Wi-Fi entity might go with a T1 or even a business-grade cable service, he says.

Fractional T1s usually sell for around $380 while a full T1 can typically be had for around $650, he says. “I haven’t seen many in Wi-Fi go with a cable service, mostly because of perception that cable is residential and not offering the performance of DSL,” Pollock adds. “Also, nine times out of 10 cable services just aren’t available in business areas.”

Wireless can be an effective option in places where other services aren’t available and there’s a need to get backhaul connections quickly - and sometimes temporarily. There are a wide variety of wireless options from which to choose, including satellite, 2.5/3G cellular, outdoor Wi-Fi and other versions of broadband wireless.

For example, wireless ISP TowerStream Corp., which offers a variety of access options ranging from T1 to 100mbps, operates a proprietary broadband wireless network based Aperto Networks Inc.’s proprietary point-to-multipoint equipment over a mix of licensed and unlicensed spectrum, mostly in the 5GHz band. The company plans to overlay its network with standards-based WiMAX technology when that equipment is available.

Among TowerStream’s services is “5 for 5,” which delivers 5mbps connectivity for $500 a month. “Customers are really amazed at that - that’s unheard of,” says Philip Urso, CEO of TowerStream. The first 1.5mbps is guaranteed QoS and the rest is best effort, he adds. Urso says TowerStream can offer that big bandwidth without relying on local incumbent service providers. “Since we’re not beholden to the telco in any way, we can deliver this very quickly - with 48-hour installation guaranteed,” he says.

Motorola Canopy Wireless Broadband Products is another of the many of proprietary broadband wireless equipment providers offering gear that can be used for Wi-Fi backhaul. The Canopy products are being used by the City of Cerritos, Calif., for Wi-Fi, says Juan Santiago, Motorola’s director of strategy. The meshbased solution delivers a 10mbps pipe that can be divided for upstream and downstream traffic (usually it’s a 25-75 split), says Santiago, adding that fast timeto- market and cost parity with DSL make Canopy an attractive option.

Even third-generation cellular can be used for Wi- Fi backhaul, adds Jeff Cortley, director of offer management for Lucent Technologies’ Mobility Solutions Group. The vendor provides an EV-DO or HSDPA interface from an 802.11 AP to enable mobile Wi-Fi applications like limousine- or train-based services, he says. The average, aggregate throughput of an EVDO connection is 400kbps to 700 kbps, but it can go up to 2.4mbps, says Cortley, while HSDPA delivers 1.4mbps to 3.6mbps, depending on the version of the standard used.

Meanwhile, some Wi-Fi providers with long-reach systems and nearby Internet PoPs use the Wi-Fi network itself for backhaul. DC Access, which offers Wi- Fi to apartments and other consumers in the Capitol Hill area in Washington, D.C., is among the WISPs going this route.

Yet another wireless option for Wi-Fi backhaul is satellite. SDN Global is a satellite-based service provider that provides LinkSpot Networks Inc., which offers Wi-Fi in RV parks at about 50 locations in 24 states. “In most cases we’re in rural areas, and DSL or cable is just not available,” says Mark Caplan, CTO for LinkSpot Networks Inc. “DSL is good for 12,000 feet beyond the CO and a lot of our sites are more than 30 miles from the CO and the loop charge for a T1 is pretty excessive. Two-way cable often is not available in RV parks. So it mostly comes down to a distance issue.” That led LinkSpot to look into various wireless options for backhaul; SDN is among the service providers it chose for that purpose.

For a promotional price of $395 per month, SDN provides LinkSpot with 1mbps downstream and 256kbps upstream satellite-based backhaul. Several wireless providers offer connectivity for up to 50 percent less, says Larry Jones, president and CEO of SDN Global, but they offer more consumer-grade service while SDN is “enterprise class.” “Jitter and delay on this is tightly controlled,” says Caplan. “In the past we’d used other satellite providers, but [their networks were] not built as IP networks; IP was built on top of it. So they didn’t have satellite loading parameters and the IP error correction … So, throughput wasn’t as good as we had hoped.” The SDN network is based on gear from iDirect Technologies Inc. and includes a 1.2-meter dish and ground unit/receiver/transmitter equipment. Caplan says SDN enables LinkSpot add bandwidth as needed, as well as jitter and delay control, which will come in especially handy when voice becomes a standard feature on Wi-Fi networks. “The product Mark uses” that we’ve installed - is capable as it’s installed of throttling up bandwidth without a visit to the site - up to 11.5mbps on the downlink and a return of up to 4.5mbps back to Internet - which is pretty much unheard of for VSAT,” Jones says. “That probably won’t be needed, but it’s a comfort, especially as VoIP is coming - we can offer a committed information rate.” Caplan says LinkSpot plans to offer a VoIP solution for campgrounds and RV owners in the next few months.

Companies that sell IP VPNs, for which Wi-Fi backhaul is just one application, also see these virtual wireline connections as a good match for those wanting to offer a mix of voice and data services. Global Crossing, which provides a wide variety of connectivity solutions including DSL, T1 and more, has found IP VPN ideal for Wi-Fi backhaul, says Mike Leary, director of wireless marketing at the carrier. “If our IP VPN is used, it’s IP, it’s ready to take that traffic directly,” he says. “Just the capacity and reach that we offer with our domestic network make it a good option for folks who are trying to knit together a Wi-Fi network.”

Of course, IP VPNs can run over DSL, he says. “We also can support frame relay and set up PVCs within a frame relay connection to support IP over frame relay in an instance like that,” he says.

Callipso Corp., which operates an IP network, also says Wi-Fi as a good match for its capabilities moving forward. “We believe there is a tremendous amount of growth in [Wi-Fi], and what’s really interesting about it is as you begin to take a look at how Wi-Fi is growing and how the bundling strategies that ISPs like Covad [Communications Group Inc.] and others are putting in place, there is tremendous opportunity for us to either peer Wi-Fi networks or to provide them connectivity much the same way we are doing with cellular, so we are taking a look at it,” says Randy Mueller, chief marketing officer with Callipso. “We have a number of discussions going on with carriers to do it.”

Callipso’s network enables it to provide carrier customers with quality of service and end-to-end visibility, says Mueller, “so they can take a look at a particular hotspot and that traffic as it’s routed all the way back to their switch and really have a continuous view to the QoS to that traffic, of being able to understand all the characteristics relative to their own SLAs with their customers. Those are the types of things they can find with a managed IP network that they can’t find anywhere else.”

Dan Moffat, president and CEO of New Edge Networks Inc., agrees that while most hotspot operators are content with 784kbps or higher, best-effort backhaul today, that’s likely to change with the advent of VoIP services. New Edge, which is co-marketing its backhaul through a deal with Wi-Fi back-office solutions provider Airpath Wireless Inc., sells a variety of access services including ATM, DSL, frame relay, dedicated Internet access, cable modem and satellite services.

“We have the largest access footprint in the country; it’s called our Big Foot strategy,” he adds. In selecting a backhaul provider and service, Moffat says the issue isn’t so much whether to go with a DSL or a T1 connection, because of a technical difference, but because of different response times from the telco. “The quality of service really has to do with the speed, the performance settings and the mean time to repair,” he says. “And speed and performance settings can be the same for DSL versus T1, but the mean time to repair is different.”