• United States

How we did it

Feb 03, 20032 mins

How we tested the Vocera Communications System.

We tested the Vocera system as supplied by Vocera. The kit included four badges (with lanyards, headsets, belt clips and chargers), a Dell 4500 server (Windows 2000 Server) using a 2-GHz Intel processor, and a 40G-byte hard disk with internal IEEE 100Base-TX network card.

However, while the server software was installed with Vocera components, the server (running under Windows 2000 Advanced Server) arrived without any service packs or security updates.

After platform stabilization we added users, groups and access point location aliases, which became objects of identification that Vocera used to locate for conversations. Additional user setup can enable comparatively sophisticated “follow-me” call-forwarding features.

Two test beds were used: a pristine, isolated network and the lab network. The pristine network consisted of five 802.11b access points (one from Proxim/Orinoco, two from D-Link, one from Intel and one from Linksys) in a nonoverlapping configuration (to reduce the effects of co-channel interference). We then connected this network to the lab infrastructure and two phone trunk lines.

We walked along our property doing a Verizon-style test (“Can you hear me now?”) through an acre one-floor range. We noticed service outages (Vocera has a signal strength indicator that we verified with a notebook running an Proxim/Orinoco 802.11b card) that occurred where wireless LAN drop-off normally occurred.

We repeated the test while running batch FTP transfers designed to clog all the access points. On a few occasions we noticed conversational dropouts, but never increased time lag. When we used a Spirent traffic generator to clog the 100Base-TX segment connected to the Vocera server, we had uniform conversational drop-offs when at 94% utilization; badge units reconnected without user intervention.

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