Designing and Fine-tuning WI-FI Networks

The benefits of a Wireless LAN have been touted enough to entice any IT manager to consider deploying it on his network. The chances are that many of you would have already done it in some or the other form. But are you happy with your existing WLAN setup? Are your users getting sufficient bandwidth for running their business applications over the WLAN? Can your mobile users get seamless roaming on your network? If the answer to any of these is negative, or if you're planning to use wireless technology for a particular application, then read on. 

Designing a wireless network is as easy or as difficult as designing an ordinary wired network. If you want to provide basic Internet connectivity to a few mobile users in your office, then you just have to set up a wireless router, and this doesn't require much planning. But if you intend to use your wireless network for a specific business application, then more careful planning is required. 

Take for instance one of the most talked about applications of WLAN-that of people working in a warehouse and recording inventory information using barcode scanners to a central database server over wireless. The big benefit of wireless here is that you don't need to deploy structured cabling, and workers can just move around carrying wireless equipment and recording inventory. The explanation usually stops here, so that the benefits of WLANs sink in. However, things aren't as hunky-dory as they sound. Just think what would happen if a worker lost the wireless signal in the middle of a database transaction? It could happen even if you've got wireless signals present throughout the warehouse. This break can be caused by obstructions, noise from sources such as cordless phones, etc. If this happens, then the worker would first have to move the barcode scanner around to catch the wireless signal, then he would have to re-login to the central database and only then perform the transaction. 

If this happens with all the workers in the warehouse, imagine the number of errors that would result in the central database. What should be done in this case? One solution is to ensure that your application is designed and developed to handle such incomplete transactions. Ensure that the transactions don't have to restart all over again, but resume from where they broke off. 

The bottom line here is that while designing a WLAN, you have to consider more than signal strength during the deployment. If mobile users need to access it from anywhere, then it needs to provide seamless roaming. If it's a business-critical application, then you have to factor in the QoS requirements, as well as provide fail-over and load-balancing, so that the access points themselves don't become a bottleneck. In this story, we try to address some of these issues while designing a

WLAN.

Anil Chopra, Anindya Roy, Ankit Kawatra, Anoop Mangla, Sujay V Sarma,

Sushil Oswal