Good wireless LAN (WLAN) performance depends first and foremost on WLAN design best practices, but when the physical characteristics of an environment change dramatically from day to day, designing a perfectly
The third-party warehousing company WOW Logistics has started deploying a Ruckus Wireless-based WLAN with Wi-Fi beamforming in order to address this challenge.
As a third-party logistics company, WOW maintains more than a dozen large warehouses in Wisconsin, Illinois and Idaho for a constantly evolving set of customers who move their products in and out of those warehouses on a daily basis. When network administrator Dave Christianson joined WOW Logistics two years ago, he inherited a wireless LAN that was plagued by poor performance.
"I noticed in talking to end users that we had disconnections and slow response times, so I went out to all our locations, did site surveys and generated heat maps. What I learned very quickly was that the site survey this month would be very different from the site survey the next month," said Christianson.
"In a refrigerated warehouse we have drive-in racking where customers store products four shelves deep and five shelves high. At the time I did the site survey, [these racks were] filled with 640-pound, [metal encased] blocks of cheese. Cheese is anywhere from 20 to 40% water. It's impossible [for Radio-Frequency (RF) signals] to penetrate water."
Customers would roll these immense blocks of cheese into a warehouse, and the wireless LAN would fail. If they pulled the cheese out a week later, the network would rebound. Since WOW's inventory control system depended on the wireless LAN, better performance was essential. Also, WOW planned to deploy more and more services over its wireless LAN, including a Wi-Fi-based push-to-talk voice system with Motorola's TEAM EWB00 badges that would replace a more costly walkie-talkie deployment. Christianson knew he had to come up with a WLAN design that could deal with his dynamic environment.
Wi-Fi beamforming eliminates need for line-of-sight WLAN design
WOW's 802.11a/b/g-based Motorola network was due for an upgrade, so Christianson asked Motorola and other vendors for solutions to his WLAN design problem. Many vendors told him that he had to establish a line-of-sight approach, placing access points where an RF signal could have an unimpeded path to clients. In an environment where mountains of cheese or crates of clothing rise and fall on a daily basis, this approach wasn't feasible.
"I understand [the need for line-of-sight], but we have thirteen warehouses, each with about 500,000 square feet," he said. "How realistic is it for me to move these access points that are 40 feet up in the air every time product moves around?"
Christianson did some online research and discovered Wi-Fi beamforming, a technology that analyzes signal-strength data from Wi-Fi clients and adjusts the output of the multiple antennas on an 802.11n wireless access point to form one optimal signal path to the client. Beamforming is different from MIMO (Multiple-Input Multiple-Output), which sends multiple independent signals to a client without any client input. He believed that Wi-Fi beamforming could help him build a wireless LAN that could adjust to his dynamic environment.
Christianson's research uncovered that two vendors offered forms of Wi-Fi beamforming at the time: Ruckus Wireless and Cisco Systems, but he sent out an RFP to a larger number of vendors (including Motorola and Aruba Networks). Ruckus' bid came in the cheapest and promised the highest performance, he said.
Phase one of WOW's upgrade started in January with one of its largest warehouses. Christianson began a one-for-one replacement of his legacy Motorola access points. Even though he had very few 802.11n-based Wi-Fi clients in the warehouse, users started seeing an immediate improvement.
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"On the first day, while I was in the middle of replacing the Motorola equipment, everyone was saying everything is so much faster," he said. "I could go into diagnostics on a [Motorola] MC9090 [handheld radio frequency identification (RFID) scanner] and it will tell you the average connection speed. When I had the 802.11a/b/g solution in place, not any of them were above 11 Mbps. As soon as I put the Ruckus network in, 98% of them were at 54 Mbps. The other two were at 48 Mbps."
Christianson installed Ruckus in two more warehouses in February and will continue rolling out the new wireless LAN throughout the year. With a more reliable WLAN powered by Wi-Fi beamforming, he is exploring ways to deploy more wireless applications and services over the network.
He is testing a new wireless temperature and humidity sensor system for WOW's refrigerated warehouses.
"We have to take temperature and humidity readings all the time," he said. "Currently, we have our managers walk around and read the temperature and humidity at specific intervals. I want to automate that. I want to put a [battery-powered, Wi-Fi] sensor in every cooler, so a manager can click a button and, boom, here you go. All of your readings are there and exported to XLS.”
Let us know what you think about the story; email: Shamus McGillicuddy, News Director