More enterprises are moving towards deploying universal wireless coverage across their campuses. Software has matured, wireless networks have become easier to manage and more secure, and bandwidth is approaching that of wired connections. Today’s workforce has become more mobile, and the desktop of choice is usually a laptop. And as wireless becomes more ubiquitous, it enables an entire collection of new applications that can be used to communicate with employees when they are away from their offices, monitor sensors around a building, and even transmitting video streams, too.

Take for example 3G cellular broadband offerings. With the popularity of Apple’s iPhone and others, more IT workers want always-on Internet from their smartphones. In a survey conducted by Trellia Networks last fall, they found that there was widespread interest in 3G broadband adoption, with half of the respondents evaluating and another third in the middle of deploying this technology.

Many hotel owners have recognized they have to go after premium guests and offer corresponding premium services, and are doing so with various wireless technologies that will open guest doors, track the items in the mini-bar, and deliver Internet telephony to each room.

And hospitals are also coming on board with wireless too. “Five years ago, hospitals were afraid that wireless devices were going to interfere with their medical telemetry and they put these bans into effect. But few problems have materialized and for the most part interference isn’t an issue,” says Scott Sbihli, the global product manager of networking systems for GE Healthcare. As technologies have matured, many have realized that interference is more of an urban legend than reality, and with the proper arrangement of antennas and configuration, everyone’s radios can co-exist and not threaten patient monitoring or other critical functions.

But for these new applications to function properly, wireless truly has to be available everywhere, and this means that designing the right in-building coverage becomes critical and a lot more than just proper antenna placement and access point design to avoid radio dead spots. There are also lots of issues to resolve (see the related sidebar), particularly if a shop wants to support multiple wireless technologies beyond just Wifi and cellular voice connections. There are multiple standards to support, and mixing wired and wireless infrastructure can still be more of a black art than cut-and-dried engineering. Finally, deploying centrally-managed wireless solutions will take some careful planning and vendor evaluation to decide on the right approach.

The major vendors for managing mixed cellular/Wifi networks are ADC Telecommunications’ subsidiary LGC Wireless, PowerWave Technologies, InnerWireless and MobileAccess.

Just because an enterprise has wireless access deployed doesn’t mean that it is optimized. At the Baptist Healthcare East hospital in Louisville, Kentucky doctors were receiving their pages a few minutes late because poor in-building cellular coverage. “A lot of the doctors had Nextel push-to-talk phones, but they only worked in the surgical areas of the hospital,” says Jim Laval, manager of corporate IT at the medical center. “They wanted something that worked everywhere.” They ended up deploying ADC’s InterReach Fusion and now have universal coverage and high quality wireless signals, and are deploying new applications that depend on this wireless infrastructure.  “Having a solid wireless infrastructure gives us a lot of potential for new applications that enhance staff productivity and improve the quality of our care,” says Laval.

As the number of different radio frequencies increase within an enterprise, it is important that any deployment make use of filters to mitigate interference, as well as proper construction of antenna arrays that can operate at low power levels and focus coverage on particular areas inside the buildings. The goal is to keep coverage high without sacrificing signal quality and service. This is the solution adopted by MobileAccess, with their Universal Wireless Network products that combine multiple radio signals over a single antenna array. While this makes a lot of sense, it has to be done with care. This is because when two or more signals are transmitted together they can generate noise or interference. MobileAccess groups antennas together but does so by using lower power emitters and using filters to separate the signals and mitigate interference.

MobileAccess and InnerWireless both use a single antenna to support multiple wireless signals, but make use of coaxial cabling to connect this antenna to the wiring closet on each floor. In this solution, the WiFi access points are kept in the wiring closets, and connected via coaxial cables to antennas that are mounted closer to the users. This has the advantage of keeping IT infrastructure out of the ceilings and in more centralized areas that can be protected and more easily maintained. It also removes these devices from places out in public area where they may be tampered with. MobileAccess supports up to ten different wireless services, including cellular, WiFi, and the medical telemetry band on a single omni-directional antenna.

ADC and Powerwave use a different method. They have a separate antenna array for each wireless service, connecting each via standard category 5 twisted pair wiring to bring the radio signals back to the floor’s wiring closet. This has the advantage of using common wiring that is probably already installed and is well understood by most corporate infrastructure engineers.

ADC places more active elements closer to the users, which can be a more costly installation, depending on the configuration. The tradeoff is using cheaper passive antennas but having more expensive cabling compared to a single set of active antennas that are less expensive to cable but require separate antennas. Part of the biggest cost component of any antenna installation is the final few yards of cabling that will go closest to the ultimate end-users. “There is big labor cost to go up in the ceiling, and the less you can do there and the more you can do in the wiring closet when you want to add your second and third frequency band, the less costly your job will be,” says Sbihli. “You might also design a system for future expansion so you don’t have to pull more cabling two or three years from now.”

This was the motivation behind the design of the Comcast center, a new office tower in downtown Philadelphia that is also the home office of the cable company of the same name. “We wanted to have an in-building antenna system to future-proof the building,” says Fred Doughterty, the VP of portfolio technology for Liberty Property Trust and the developer of the 975-foot high skyscraper.  “Given the height of our building and the fact that we were using low-energy emissions glass cladding that would block a lot of cellular radio transmissions, we knew we had to doing something to support all four major cellular carriers and Wifi throughout the complex.” Liberty ended up choosing MobileAccess to deploy their wireless solution after a very painstaking evaluation of the various vendors. “Each tenant can connect their private network to the MobileAccess equipment and benefit from a fully engineered wireless network distribution system in their space. The reliability of the system is exceptional, and all of our property management and building staff have superior communications. Wireless coverage is exceptional and complete, without interference or any signal loss throughout the building.”

Supporting in-building wireless requires lots of planning and specifications development: the Comcast project started seven years ago as an example when the first requests for proposals for their IT infrastructure were created. The good news is that technology is improving and supporting multiple wireless frequencies is getting easier and better.

Sidebar: Issues to consider

• How far into your wired network do the wireless packets have to travel? You may have to rewire some of your network between floors or from wiring closets to accommodate.
• Is end-to-end network management important? Cisco doesn’t have this across both wired/wireless product lines, for example.
• Do you want to skip earlier 11x radio standards and move right to 11n? Then make sure your products are current with 11n support.
• Do you need a lot of capacity for wireless users in a small area? Look at products such as Xirrus that can support these higher density uses.
• Do you need to have both Wifi and cellular support, and if so, do you want to use the same antenna arrays and infrastructure?