log: no beacons received

RouterOS Wireless Networking
1

Hi,

I know this topic has already been mentioned meany times before, but it seems there was no solution found yet.

I have about 25 RB Metal 5SHPn wireless stations. These stations are located in a magazine hall and they are mounted on trolleys which move slowly along a looped route, slower than walking speed. The stations are running RouterOS v. 6.19 and this won’t be changed, at least not in the close future.

The stations are connected to one SSID on one access point working in 802.11a on a fixed frequency. The access point is made by a different vendor than Mikrotik, but it’s a high end product capable of handling 25 stations per radio. The AP broadcasts 3 SSIDs, data rates allowed are: 6, 12, 24 as basic and 18, 36 and 48 as supported. 54 Mbps is disabled on the access point. Signal levels received by the stations are ok - at least -70 dBm@48Mbps, noise and quality parameters are at least good. For 54 Mbps the signal level was low, it reached the sensitivity level of the station’s radio.
If it matters, the stations work in station-pseudobridge-clone mode.

Trouble is, I keep getting this in the log of the stations:

jan/25 04:19:56 wireless,info FC:xx:81:xxxxxx@wlan1-gateway established connection on 5220000, SSID xxxxxx 
jan/25 05:47:35 wireless,info FC:xx:81:xxxxxx@wlan1-gateway: lost connection, no beacons received 
jan/25 05:47:40 wireless,info FC:xx:81:xxxxxx@wlan1-gateway established connection on 5220000, SSID xxxxxx 
jan/25 06:46:24 wireless,info FC:xx:81:xxxxxx@wlan1-gateway: lost connection, no beacons received 
jan/25 06:46:29 wireless,info FC:xx:81:xxxxxx@wlan1-gateway established connection on 5220000, SSID xxxxxx 
jan/25 07:27:29 wireless,info FC:xx:81:xxxxxx@wlan1-gateway: lost connection, no beacons received 
jan/25 07:27:34 wireless,info FC:xx:81:xxxxxx@wlan1-gateway established connection on 5220000, SSID xxxxxx

Beacons are broadcasted on the lowest basic data rate, for this rate the signal level is more than satisfying. Why is this happening? What more can I check?

Looking forward to your responses,
Jacek

2

Have you tried distance = dynamic in stead of indoors?
Perhaps it’s a timeout issue and not a signal issue.
(not sure how far these carts are roaming from the AP)

Gotta admit this is one of the more interesting scenarios I’ve seen on here in a while.

3

No, I haven’t tried it. I will. Thanks for the hint.

The area is maybe 50 x 30 m ant the route looks like this:

/--------\
|         |
\---\     |
     |    |
   X |    |
     |    |
     |    |
     |    |
     \----/

X is the access point location, about 4 m above ground level, about 3 m above the station antennas.
The access point has a panel antenna of semi-omnidirectional characteristics, directed downwards.
The stations also have semi-omni antennas, directed upwards.

I made a script to measure the signal levels at different rates (logging :put [/interf wirel reg get 0 strength-at-rates]
second after second) and ran the trolley down the route. The outcome was poor for 54 Mbps, rx signal level got near to the receiver’s sensitivity (-77 dBm) in 3 locations. For 48 Mbps the signal level was at least 10 dB better and the sensivity is AFAIR -83 dBm.