Wi-Fi Analyzers

---

• To determine the best channel layout and troubleshoot wireless network performance measure the signal strength of the different networks using each channel
  • can be accomplished using a Wi-Fi analyzer
    • can be installed to a laptop or smartphone
    • will record statistics for the AP that the client is currently associated with and detect any other access points in the vicinity
• Wireless signal strength is measured in decibel (dB) units
  • represented as the ratio of a measurement to 1 milliwatt (mW), where 1 mW is equal to 0 dBm
  • because 0 dBm is 1 mW, a negative value for dBm represents a fraction of a milliwatt
    • E.g., -30 dBm is 0.001 mW, -60 dBm is 0.000001 mW
• Wi-Fi devices are all constrained by regulations governing spectrum use and output only small amounts of power
• When measuring signal strength, dBm values closer to zero represent better performance
  • value around -65 dBm represents a good signal
  • anything over -80 dBm is likely to suffer packet loss or be dropped

Info

The dB units express the ratio between two values using a logarithmic scale. A logarithmic scale is nonlinear, so a small change in value represents a large change in the performance measured. For example, +3 dB means doubling, while -3 dB means halving.

The comparative strength of the data signal to the background noise is called the signal-to-noise ratio (SNR).

• Noise is also measured in dBm
  • but values closer to zero are less welcome, as they represent higher noise levels
    • E.g.,
      • if signal is ‑65 dBm and noise is ‑90 dBm, the SNR is the difference between the two values, expressed in dB (25 dB)
      • If noise is -80 dBm, the SNR is 15 dB and the connection will be much, much worse