Insufficient Wireless Coverage Issues

if sufficient signal strength cannot be obtained and interference cannot be mitigated,
- must install additional AP

Antenna Placement

incorrect placement can cause:
- attenuation
- interference
leverage a site survey and heat map to choose a location
using wrong antenna type may worsen signal strength
- unidirectional antenna is only suitable for point to point connections
internal antennae built into APs may also be optimized to transmit and receive in some directions more than others
- e.g.,
  - AP designed for ceiling mounting may produce a stronger signal in a cone directed downward from its central axis
  - signal from a desktop AP is likely to radiate in a doughnut-like pattern

Effective Isotropic Radiated Power (EIRP) is the signal strength from a transmitter.

calculated as the sum of
- transmit power
- antenna cable/connector loss
- antenna gain
e.g., point to point link with directional antenna:
- EIRP =
EIRP for each radio is reported through the AP or controller management software
must not exceed regulatory limits
power limits are different for
- 2.4 GHz and 5 GHz bands
- point to multipoint and point to point operation modes
increasing transmit power is not an effective solution for improving wireless coverage
AP may have EIRP of 23 dBm
smartphones may have EIRP of 10-14 dBm
if client detects a strong signal
- sets a high data rate
- but client has lower EIRP, so fails to transmit strong signal back to AP
- results in excessive packet errors
AP power should be 2/3 of the weakest client power
- e.g., if weakest client has output of 14 dBm
  - AP should transmit at 9-10 dBm