OSU Medical Center
Wireless LAN Standards & Policy

The Ohio State University Medical Center (OSUMC) has adopted the Wireless LAN standard 802.11b. The devices supported conform to the IEEE standard whereby the following guidelines are met:

2.4 Frequency range
Direct Sequence Spread Spectrum (DSSS)

The OSUMC has a very large installation of Cisco/Aironet Wireless LAN equipment to currently facilitate Patient Order Entry. The impact of foreign devices and/or 3rd party vendor solutions in our environment can and will have detrimental effects on our patient care due to interference and unnecessary communications in the Radio Frequency (RF) environment. The same can be said if devices are deployed in buildings outside of our primary Medical Center complex, i.e. Rhodes, Doan, and the James. We have received and analyzed communications in our SICU and James O.R. areas from outside sources impacting normal data communications on our network.

Our environment is very sensitive to outside interference, as any Wireless LAN environment would be, and can be directly influenced by devices in adjacent buildings, i.e. Medical Research Facility, Wiseman Hall, Hamilton Hall, Heart Lung Institute, and Starling Loving, to name just a few. The transmit power of the Wireless LAN equipment or the type of antenna employed, are a few of the reasons for this interference. Many 3rd party devices, such as those from Dell, Compaq, 3COM, and Linksys, etc., may not have the ability to adjust this power, and their Network Management capabilities either are non-existent or greatly reduced. Likewise their prices reflect this as well.

When products are advertised as complying with standards, i.e. 802.11b, this does not apply to the methods utilized to roam and adjust data throughput due to high utilization in a multi-vendor environment. The current standard, 802.11b, does not govern roaming techniques and Network Management (to name a few). The market is being flooded with these products, and they are very easily obtained. However, they are not designed in large part for the Corporate Enterprise, but more geared for the small home office or private residence, for example. The need for Network Management is a critical requirement for OSUMC for the purpose of troubleshooting and maintaining a complex network infrastructure, which provides the highest level of patient care. The ability to document all network clients and devices is the cornerstone of our Network Management program.

Currently, we are strongly recommending any Wireless LAN purchases be limited to the Cisco/Aironet models 340 or 350. These models are in turn supported by the Microsoft Windows Operating System which is the standard adopted by OSUMC. These models include the Access Points (those devices wired to the network) and the PCMCIA Client Adapter cards that are necessary in the end devices. OSUMC's Information Systems Staff would be more than willing to provide any help in analyzing an area or department's request for Wireless LAN communications. In this way we can evaluate current product lines and determine the need for a site survey. In this way we can insure and maintain the highest performance possible on our data network, which in turn facilitates Patient Care in our facility. One factor that must be emphasized is the platform that Wireless LAN is based on, and that is a bridged or shared communications link. Unlike a switched environment where clients are dedicated to a 10 or 100 Mb link, for example, the Wireless LAN clients share the single uplink provided by the Access Point. Therefore the throughput of the Wireless clients will never be up to the level of the switched client on a wired topology.

We must insist that any plans for purchases of non-standard equipment for the purpose of Wireless LAN equipment be scrutinized and evaluated as to the effect on our Medical Center's Environment. This would also include those in surrounding buildings, as was mentioned earlier.

The placement of any Wireless LAN Access Points must be approved by OSUMC Information Systems. The placement or location is very important to the performance of these devices on OSUMC's data network infrastructure. The configuration is a vital part as well.

Wireless LAN communication is rapidly becoming available for the home market. The most popular product lines are being promoted and designed for the residential DSL or cable modem subscribers. Although these product purchases would naturally be out of the scope of the Medical Center's responsibility, we must insist on the Cisco 340 or 350 series Client Adapters, if the individual desires to use the end device, i.e. laptop, at the Medical Center as well as home. Again the ability to document the devices on our network is crucial to provide security in our environment, as was mentioned above.

Due to the standards illustrated above, Bluetooth is a technology not supported in our enterprise. This technology is designed for cableless communications (or cable replacement) supporting up to 8 devices in a PAN (Personal Area Network) or Piconet. It is based on Frequency Hopping Spread Spectrum (FHSS), whereas our Wireless Network is based on Direct Sequencing Spread Spectrum (DSSS). Bluetooth is gaining popularity, but is designed for a 10 meter range and only a Milliwatt of transmit power. As mentioned above the transmission technology (FHSS) allows for only 721kbps for data, has limited ability for handoffs (roaming), and has a fundamental weakness in security. Bluetooth's security standard authenticates only the device NOT the user. Within a DSSS cover cell Bluetooth enabled devices WILL CREATE a degradation in communications, almost any technical whitepaper written on the subject will verify this. Bluetooth in a scenario where a laptop, printer, PDA, and phone are all enabled makes perfect sense for wireless communication amongst the devices. However, that same scenario within one of our DSSS cells will cause interference and degradation of communications and must be avoided.

One final comment, the IEEE has adopted the 802.11a standard allowing up to 54 mbps throughput. It operates in the 5GHz frequency range. Currently no products are shipping, and the technology is very immature. The initial costs are very likely to be quite high. The OSUMC's stance on this technology is that it is currently not supported. The devices supporting these 2 standards will be able to be co-located, but at present time no devices will be deployed.