Wireless Design Principles
- Wireless Signal Mesured in dBm ( Power referenced against one Milliwatt )
- Range is roughly -30dBm to -90dBm
- -30dBm = Max Achievable ( not desired ).
- -67dBm = Mininum for real-time Apps.
- -80dBm = Minimum for communication.
- Noise is always a challenge
- Signal to Noise Ratio ( SNR ) = ( Signal – Noise ) = Value
- Mininum SNR of 25 is needed for real-time apps.
Wireless Channel Selection: 2.4Ghz and 5Ghz
- 15% – 20% overlap required for seamless roaming.
- -67dBm at cell edges for real-time traffic.
- Multi-floor should be a 3D design.
- 2.4Ghz means fewer clean channels (1 – 11).
- 5Ghz means less range.
Site Survey tips:
- Identify the “Customer Style” you’re dealing with.
- Determine coverage area and key locations ( Good and bad ).
- Do a “floorplan-based WAP map”- Preliminary design.
- Install Waps.
- Do a “Boots on the ground” site survey, floorplan in-hand.
- Make adjustments ( Move WAPs, add Maps) to achieve data rates.
- Document everything you’ve done.