This tip is reposted from SearchNetworking's Day-to-Day Networking feature, which includes a cartoon and daily networking tips for the month of October.
If you're planning to deploy a wireless LAN, or tweak a customer's existing deployment, then the conventional wisdom is that you need a "site survey." Most wireless vendors are now offering very sophisticated tools that practically do the survey for you, but if you're trying to manually locate the best places to put wireless access points (WAPs), the trick is to keep the following three key relationships in mind (most of which are fairly obvious, but this can serve as a checklist):
Relation to users:
- There are two ways to approach this, depending on your requirements: Design to give the best signal to the most users or coverage area, or pick a minimum and ensure that every user or area gets that or better.
- Obviously, distance is key since data rates go down as distance increases. Minimize distance based on the design objective above.
- Remember that signals are still shared, so the more users per WAP, the smaller each users' share of the bandwidth will be.
- For security, WAPs should be as out of reach as possible -- preferably on or above the ceiling (depending on construction).
Relation to the facilities:
- Obviously, keep away from metal pillars, filing cabinets, duct work or concrete walls, or other sources of interference (such as machinery), where possible.
- Use the appropriate antennae for the area.
- The device will have to have electric and/or Ethernet cabling, so placement should minimize cable distance and expense if possible.
Relation to other WAPs:
- Some vendors recommend a 20% overlap in coverage for seamless roaming of voice devices. This is a good rule of thumb, but consult your documentation.
- Think about channel usage when WAPs are within range of each other. This is particularly important in multi-tenant areas where you may not have administrative control of other radios.
- You can adjust the power to reduce or increase the signal to optimize the overlap instead of moving WAPs physically closer or farther apart.
About the author
Tom Lancaster, CCIE# 8829, CNX# 1105, is a consultant with 15 years of experience in the networking industry. He is co-author of several books on networking, most recently, CCSP: Secure PIX and Secure VPN Study Guide, published by Sybex.
This tip originally appeared on SearchNetworking.com.