Registration Table and Signal Strength

What it is

The registration table lists every wireless peer that is connected to an interface, with live link statistics.

On an access point it shows each client. On a station it shows the access point. It is the first place to look when a user says the Wi-Fi is slow or keeps dropping.

The two most useful figures are the strength of the signal you receive and the strength of the signal the other side receives from you. Comparing them tells you where the problem is.

How it works

You read the table, compare the two signal values, and use the noise to judge the margin.

Reading the table

Print the table from the console:

/interface wireless registration-table print
/interface wireless registration-table print detail
/interface wireless registration-table print stats

The detail form shows every property of every peer. The stats form shows the figures that matter for troubleshooting, such as rates and signal, in a compact view.

These are the properties you meet most often:

Signal strength

Signal strength is measured in dBm, and it is a negative number. The closer to zero, the stronger it is, so -55 is stronger than -80. The scale is logarithmic, so a change of 3 dB is a doubling or halving of power.

RouterOS shows the signal it hears from the peer. This is the receive side from your point of view.

TX signal strength

The tx-signal-strength value tells you how well the peer hears you. It reports the signal that the other side receives from your transmissions. It is only available when the peer reports it, so it can be missing for some clients.

Comparing the two values is powerful. If both are strong and similar, the link is balanced. If they differ a lot, one side has a problem.

Signal to noise

A strong signal is not enough if the noise is high. Signal to noise is the gap between the signal and the noise floor. The larger the gap, the better the rates the link can hold.

A fair signal over a very low noise floor can beat a strong signal over a noisy one. When the signal looks fine but rates are low, look at the noise. The monitor command shows it:

/interface wireless monitor wlan1

A simple analysis routine

Follow these steps:

• Print the table and find the client that has the problem.
• Check uptime to see whether the client keeps reconnecting.
• Compare signal-strength with tx-signal-strength.
• Check signal-to-noise and the rates in both directions.
• Look at the CCQ values and the counters, which the next pages explain.
• Change one thing at a time, and look at the table again.

Why the table changes

Values move as people walk, doors close and neighbours start transmitting. A single reading is not a diagnosis. Look at the table several times and over a period.