Wireless mesh deployment moves at rapid pace, despite architectural and topographical challenges
EarthLink overcomes challenges and rolls out citywide wireless for Philadelphia.
Crews were dispatched to accelerate the installation of access points on light poles. The Philadelphia streets department inspects light poles for the access points’ use and approves the selection of poles, and then EarthLink deploys the Tropos Networks units and goes through an optimization process, and the city does a final inspection for safety and mounting.
Within 15 days of getting the green light EarthLink had doubled network coverage to 30 square miles. Today, 80% of the city is covered, and EarthLink plans to have all 135 square miles blanketed with wireless signal by the end of September. Additional network optimization has to be completed, and EarthLink expects to get the city’s official acceptance by year-end.
EarthLink is building a layered network that starts with the mesh at the street level that the company says will deliver 1Mbps to 3Mbps data rates to customers. The Tropos / access points contain built-in routers and use point-to-multipoint radios. That creates the mesh, says Jeb Linton, director and chief architect for EarthLink. The Tropos units dynamically select the best wireless channel to avoid congestion and interference.
At the backhaul or capacity injection layer, data is fed into the mesh at rates of 20Mbps to 50Mbps by Motorola Canopy radios and Alvarion VL radios on the tops of buildings and towers. In some areas of this first layer of the backhaul system, EarthLink is running fiber.
The tower tops are connected by either fiber optics or line-of-sight microwave communication at 200Mbps-to-1Gbps data transfer rates.
EarthLink already has a major point of presence (POP) in Philadelphia, which connects to the ISP’s national backbone network. The local POP contains the service gateway, which manages every user session and all details of the user experience.
In addition, Philadelphia’s wireless network was required to adhere to an open-access design. EarthLink deployed a back-end authentication system that lets subscribers from other service providers be on the network and lets those service providers control or manage their subscribers. According to EarthLink, this is done via Radius Proxy Services.
EarthLink also will invest resources to keep the Philadelphia Wi-Fi mesh network running smoothly.
Tasks associated with support of the network include:
♦ Ongoing upgrades and new Wi-Fi releases: Because Wi-Fi is a relatively new and improving technology, the standards body comes out with new releases regularly. In addition, damaged nodes need to be replaced.
♦ Installation. EarthLink has contracts with installers and bucket truck operators that do the electrical and mechanical work at the sites.
♦ Capacity analysis. EarthLink has a staff on a national level that does ongoing capacity analysis. Links are monitored on every piece of equipment across the country and on all the Wi-Fi networks EarthLink runs. Alarms go off when capacity limits are reached. This lets the WAN planning team know when an upgrade to a circuit is needed or an additional circuit is needed to supplement the bandwidth.
♦ Network management. The Tropos Element Management System and EarthLink’s customized Central Network Management system are managed by teams in Atlanta and Pasadena, Calif. Call-center workers also have a view of the network through these systems.
♦ Support. Technical support, call centers and customer support are separate functions within EarthLink. There is an escalation path and different tiers of support. Problems affecting multiple customers in one zone or sector get escalated to the nearest technical-support team that can do radio readings and talk to the customers directly. Philadelphia does not have a call center.
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