The art of wireless: Testing ensures WLAN quality of service
Testing ensures museum visitors enjoy a rich multimedia experience.
By Rick Nelson, Editor in Chief -- Test & Measurement World, 3/1/2009 2:00:00 AM
 Peter Bodell, CIO, oversaw prequalification testing before deploying a wireless LAN at the Los Angeles County Museum of Art. Photo by Steve Labadessa. See other articles from our March 2009 issue. |
LOS ANGELES, CA—A new wireless LAN system installed at the Los Angeles County Museum of Art (LACMA) enhances visitors’ experiences while supporting museum staff. Currently, the system delivers multimedia content to visitors equipped with museum-issued PDAs (personal digital assistants), it provides museum staff members with wireless connectivity to the museum’s wired network, and it serves as a WiFi hotspot to visitors who bring their own laptops to the museum campus.
Ultimately, the system may support wireless ticket and member-card scanners, enable VoIP communications among museum staff members equipped with mobile handsets, and provide RFID capability for controlling the museum collection, which numbers more than 100,000 objects.
The current and envisioned uses of the wireless-LAN capability entail various types of data traffic with widely varying quality-of-service requirements for factors such as allocated data rate, total bandwidth, jitter, and latency. And because the museum’s wireless LAN connects visitors and staff while providing connectivity to the museum’s wired network, security is a concern as well. Before choosing and installing its wireless LAN, LACMA performed extensive testing to ensure security while being able to provide the traffic-handling capability necessary to provide a positive user experience to museum visitors and staff members.
Why wireless?
The impetus to install a campus-wide wireless network occurred in 2003 when LACMA undertook to build the Broad Contemporary Art Museum within its campus. “We had been looking at wireless technology for several years, but it wasn’t really mature enough for us in this particular environment,” said Peter Bodell, LACMA’s CIO, during an interview at the museum campus in January. “We had implemented some wireless capability in some areas, but it wasn’t necessarily viewed as a campus-wide project. But when the museum said, 'yes, we are going ahead with the Broad building,’ it was the ideal opportunity to build out a campus-wide wireless system that would connect to our existing infrastructure.”
Bodell noted that, “Traditionally, museums have audio tours and paper-based content, so we stepped up and said, 'alright, we need to go to the next level—we need to get it to multimedia.’ So, we investigated a grant opportunity with the Irvine Foundation, which we were successful in securing. The grant provided funds for us to deploy PDAs within the museum and to develop content for them. In concert with that, we looked at wireless systems from a standpoint of, 'OK, what’s best for us at the moment, and what can we foresee in the future?’”
With an estimate of current and future needs, the museum developed an outline of expected deployed devices and traffic patterns (Table 1) and enlisted consultants to determine which of two competing vendors of wireless LAN implementations could best meet the museum’s requirements. Explained Bodell, “We started out with a floor plan for the various floors and galleries, and we estimated we could have a capacity of up to 300 visitors in a gallery. So, I looked at worst-case scenarios: If I have 300 people in this space, how do I need to lay out my access points to provide continuous coverage?”
LACMA’s unique approach
A unique approach taken by LACMA was that Bodell recognized that the expected mix and match of traffic would influence whether a particular wireless LAN vendor’s installation would meet expectations. “What we typically see is a lot of end users who say, 'Just make sure I can connect 10 clients and they can each do an FTP session,’ or something like that,” said Eran Karoly, VP of marketing at VeriWave, which provided the traffic-generation and -analysis equipment and software suite used to evaluate competing wireless LAN systems that the museum considered.
 Figure 1. The LACMA test bed consisted of a VeriWave WaveTest 90 traffic generator and analyzer, an authentication server, and a wireless LAN controller and six access points provided by participating vendors. |
“Many end users,” said Karoly, “don’t recognize that different uses require different quality of service. But LACMA recognized that in every hall or building there’s a variety of sessions that are going on, and there are a variety of users, with each having different requirements. The user who’s using a VoIP session requires very low delay, very low latency, and very low jitter, while somebody who is retrieving e-mail is not too sensitive to those things. What we got from LACMA was a blueprint that said, 'this is the amount of users of type a and type b and so forth, and all of them need to be served simultaneously.’ And we were told, 'OK, now create and analyze that mix of traffic.’”
To do that, VeriWave established a test bed (Figure 1) consisting of the following components:
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a wireless LAN controller (supplied by the participating vendors);
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six IEEE 802.11a/b/g APs (access points; supplied by the participating vendors);
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a VeriWave WaveTest 90 traffic generator/analyzer, equipped with six 802.11a/b/g test interfaces and one Gigabit Ethernet test interface;
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a Hewlett-Packard ProCurve 3500yl L2/L3 Gigabit Ethernet/PoE (power over Ethernet) switch;
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a Windows 2003 server; and
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assorted coaxial cables, SMA connectors, attenuators, and line splitters.
With its six APs, the tester modeled the hundreds of APs that would be mounted throughout the various art galleries, hallways, public areas, and office spaces. To ensure that the test measured traffic conditions only—and not RF variability or multipath effects—the APs were directly cabled to the VeriWave test interfaces.
The evaluation involved these tests:
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a load test, using VeriWave’s WiMix test suite, which blends planned data and voice applications originating from the independent clients communicating with each AP;
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a client capacity test, which uses the WiMix suite with various numbers of clients to determine the maximum number of concurrent clients each AP can support;
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a guest PDA goodput test, which creates high packet rates from independent PDA clients communicating with each AP; and
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an employee Web traffic goodput test, which models high bandwidth consumption from independent employee laptops and other clients communicating with each AP.
The controlled testing, said Karoly, enabled LACMA to move beyond vendors’ often oversimplified claims that a given facility will need x number of APs to cover y square feet. And in fact, the tests showed that although LACMA’s initial plan called for each AP to support up to 79 user devices, neither of the two systems under consideration could meet that goal. Given LACMA’s defined traffic, one vendor could support a maximum of 30 user devices per AP, while the other could support a maximum of 25 user devices per AP.
 Jane Burrell, VP for education and public programs, said LACMA’s wireless LAN and PDAs present a great opportunity for curators and educators: “With the ability to show images, we can tell a different kind of story—one that we couldn’t tell with a label.” Photo by Steve Labadessa. |
“LACMA came up with a traffic profile it expected every AP to handle, and one of the conclusions of the test was that the goal was overly optimistic, resulting in a more realistic and more dense AP deployment,” said Karoly. VeriWave has published a case study (Ref. 1) that provides a complete summary of the test results. Karoly noted that VeriWave, 80% of whose business is with equipment suppliers while 20% is with carriers, service providers, and IT departments like Bodell’s, doesn’t make vendor recommendations based on test results, leaving that task to independent consultants or the IT departments themselves.
Bodell did not disclose the name of the vendor ultimately chosen as a result of the test, and in fact, different traffic patterns at different installations may have resulted in a different choice. He did say that the testing was critical to making the right choice.
“The chaps at VeriWave came in and, in essence, set up their systems to emulate the traffic that we expected to see in the galleries,” said Bodell. “And that helped enormously in making a decision. VeriWave helped to recommend how to lay out the access points in the spaces so we could connect people to the system, track them, and provide them with continuous coverage. It was really a matter of saying, 'OK, what’s the ideal number of sessions you could have attached to any particular access point as users move from access point to access point within the space? How is the handoff going to take place? Will this type of access point work in this environment?’”
Bodell explained that the testing enabled LACMA to make the right decision before engaging in a substantial capital investment and complex installation process while controlling support costs. And in fact, he said, the technology can help reduce costs, because an effective entrance control system, perhaps based on RFID technology, could reduce the number of guards required.
That’s in keeping with a key museum goal. Said Bodell, “The museum has always been supportive of technologies that provide a way to leverage operational costs.” Moreover, he said, technology is increasingly important in the museum environment: “Over the past five to seven years, there really wasn’t a lot of interest in technology in the galleries. You think of a typical art museum with art on the walls and sculptures, but the concept of actually having technology in a gallery was somewhat new. It’s only recently where we started to see, because we have a lot of interest in contemporary art, that a lot of modern artists are starting to work with technology as a medium. So now all of a sudden, you’ve got technology pieces in a gallery, and you’ve got to be able to support that with power and network connectivity and access to the Internet.”
He said that going forward, PoE might complement wireless connectivity already installed to support technology works. “It’s very bleeding edge for a museum,” he said, “but at the same time, it’s an area that I’m watching.”
Town squares and virtual galleries
The wireless capabilities extend beyond the galleries, Bodell said, in support of the museum’s effort to create an environment that loosely mimics the feel of a town square, “where people can come mostly to enjoy the art but also to socialize and to sit down with a laptop and get a bite to eat. We want to create that environment where people can coexist and communicate, and the concept is one that we are very excited about.”
 During the LACMA wireless LAN prequalification testing, the VeriWave WaveTest 90 and WiMix test suite provided load and client capacity tests. Courtesy of VeriWave. |
But the wireless capabilities will be best taken advantage of not by the museum’s restaurant customers with laptops but by visitors who check out a PDA—a Nokia tablet PC that Bodell selected for its long battery life and large screen. As visitors stroll about the museum, they can key in three-digit codes discretely presented near each object that has associated multimedia content. Visitors can listen to audio content while examining similar works on the Nokia tablet’s screen, and they can drill down to learn more about the artist, the subject matter, the period when the work was created, and so on. As visitors tour the museum, they can select certain works as their “favorites.” By the time they get home, the museum has e-mailed them a link to their own personal “virtual galleries,” where they can review their favorites and do more research.
Bodell elaborated on how the system works: “When you check out a PDA, we ask you for an e-mail address and set up an account for you. As you walk around, the device is known to the system by its MAC address, which is in turn tied to your e-mail address, so that device and everything you do on that device is tied uniquely to you. You can save preferences as you walk around, and those preferences are transmitted over the wireless system to a back-end database that has relationships with the objects that you’ve selected. When you return the device, the system closes out your connection and automatically sends you a couple of e-mails that say thanks for coming to LACMA and this is what you need to do to access your virtual gallery. All the objects you saved as preferences are there displayed for you, and you can move them around and create your own galleries.
“The goal,” he continued, “is to give you access to more content that’s connected to LACMA’s collections management system, which has a lot more information about the objects. We plan to use that as a vehicle for CRM [customer relationship management] personalization, because we really feel that in the future—instead of having Websites that have a shotgun approach—we need to personalize the experiences for our visitors.”
Telling a different kind of story
Technical considerations make up only part of the challenges as the museum implements its wireless LAN system. Content creation is another challenge.
 Annie Carone, who works in LACMA’s public relations department, uses a wireless PDA to learn more about objects in the museum’s collection. By the time she gets home, the museum will have e-mailed her information about objects that she tagged as favorites. Photo by Steve Labadessa. |
Speaking of the wireless LAN system, Jane Burrell, VP for education and public programs, said, “It’s a great opportunity for us. One of the things we hear from our curators all the time is, 'We want to write more—there is so much more we want to say about our objects.’ But there is only so much that people can read in the galleries. We have strict guidelines for how much written text we can have in the galleries, and visitors can only absorb so much. But with the ability to show images, we can tell a different kind of story—one that we couldn’t tell with a label.”
Furthermore, she added, “With the back end that Peter implemented, visitors can go back home and revisit what they saw in a virtual gallery, and in fact, they can take advantage of the whole multimedia experience without ever coming here. It’s given us many more ways to connect with the visitors and give them a fuller picture of an object.”
As for user reaction, Bodell said it’s too early to tell, noting that the museum hadn’t aggressively publicized the system pending rollout of more multimedia content, which was just becoming available during my January visit. But Burrell said initial indications are that “People love the content—they’ve really been excited.” And Bodell added that people equipped with the PDAs spend exponentially longer times in the galleries. The museum is undertaking a formal evaluation of the system in pursuit of an additional grant that would provide funding to create more content.
As for how content gets created, Burrell said, “Curators will work with educators to pick objects and provide some idea of what direction they want the content to take. The educators decide what assets are available—what visuals could help tell the story, and what other stories could be told. Then, we prepare a very detailed outline and send it off to a freelance writer whom we also direct to different Websites for additional information. The writer prepares a rough draft of a script, and then the educators review that. The script gets refined through a back-and-forth process, until the curators and the educators are satisfied with the final script. As we are doing that, we simultaneously are clearing the rights for the assets that the educators or curators have identified. It’s a very collaborative process.”
Burrell used Kurt Schwitters’ “Construction for Noble Ladies” to provide an example of the types of information a multimedia treatment can provide: “The Schwitters is a painting where he used a lot of found objects to create what he wanted you to come away with. Most visitors look at that painting and don’t really see all the details that are in that work of art. But when you look at that painting on the PDA or computer screen, you can use what we call 'touch and listen’ to highlight the different found objects and bring up another screen that tells you what that object is and why he chose it.”
Content creation and rights management are proving to pose as difficult challenges as the wireless LAN installation. Burrell said that clearing the rights to use videos has been the most difficult. She explained, “We’ve had so many people turn us down for video—just small documentary filmmakers who thought, 'OK, this is my chance to get rich.’ We only have limited funding for the rights, so we’ve had to say, 'we just can’t afford it.’ You would think the exposure for some documentary with limited distribution would be great, but they really saw this as their opportunity to make money.”
Alternatively, she said, some institutions simply aren’t set up to address the rights issue. “They just ignore our requests; our phone calls don’t get returned.”
As content creation continues, Bodell is looking to the future of wireless technology. He said, “What the museum is planning to do in later phases of the transformation triggered by the Broad building construction is move more toward a very flexible work environment for the staff. What I’m really looking for is a solution that implements fixed-mobile convergence, so you could have a piece of technology on your desk that may look like a phone, but in essence, it’s a phone plus a data device. You can pick it up and walk around with it, and it’s your in-house phone, your cellphone, your PDA. The museum doesn’t want a fixed office environment for its staff. We want to leverage opportunities for telecommuting. The concept is to use a wired-wireless infrastructure to be able to support that.”
Ultimately, Bodell wants to enable visitors to access the museum’s multimedia content using their own mobile devices. “As part of the [Irvine Foundation] grant, we used an off-the-shelf piece of technology—the Nokia tablet. It’s a great wireless device—you connect it to the network, and it hangs onto the connection really well, but ultimately, the goal over the next year or two is to let you use your own piece of technology.”
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