Cisco Support Community
cancel
Showing results for 
Search instead for 
Did you mean: 
cancel
Community Member

Poor signal in Access Point 340 series

Why is it ocurrer? if there aren't interference of RF, the site survey has a poor quality of signal.

6 REPLIES
Community Member

Re: Poor signal in Access Point 340 series

For a deep-breath/start from scratch troubleshooting approach, I would:

- Upgrade the firmware

- Check the Transmit/Receive assignments of the antenna connectors

- Make sure you have good 2.4GHz antennas with a solid connection (if the unit has been dropped, you might even double-check the MMCX connectors on the card inside)

- Test the AP using the 'dB' (not %) mode in the newest version of ACU with a Cisco PCMCIA card in the client.

Matthew Wheeler

Chief Wireless Architect

www.BlueModal.com

Community Member

Re: Poor signal in Access Point 340 series

Make sure you are using antenna diversity (dual antennas on the AP, mobile client, or both). This will counteract a condition known as multipath (reflected signals reaching the AP or mobile client at the same time but out of phase). If you only have one antenna on the AP and on the mobile client, then this is most likely the cause for your poor signal quality.

Community Member

Re: Poor signal in Access Point 340 series

Instances of problems caused by multipath are rare. You almost never need both antennas attached.

Community Member

Re: Poor signal in Access Point 340 series

When you say the site survey has poor quality of signal, I'm assuming that you are referring to the signal quality reading in the site survey utility. With the Cisco utility, the signal quality meter is a depiction of the signal to noise ratio. If you are getting a low signal quality, it usually means that some type of interference exists.

You may need to have a spectrum analysis performed to see if there is some level of interference in the 2.4GHz band.

Multipath can be part of the problem. However, if you are seeing this low signal quality throughout the facility, it is unlikely that multipath is the cause. The effect of multipath is variable depending on the three dimensional positioning of the sending and receiving antenna. In this case, the AP antenna is likely stationery but the client device is not. Since the client device is moving, the multipath effect would not be consistent.

It is still not a bad idea to utilize antenna diversity, though. You will see some benefit even if you are not experiencing any adverse effects of multipath. The Cisco APs evaluate the quality of the signal for each client uniquely. Based on the quality, the AP chooses which antenna to use to transmit to each client. This is somewhat different from what some of the other vendors do with antenna diversity. Most others always transmit on the primary antenna, but will receive on both.

Hope this helps.

Kerry

Community Member

Re: Poor signal in Access Point 340 series

All of the suggestions by the responders are excellent please be sure to do them. If after all you still have problems then you should consider that at some point minor electrical damage may have happened to the RF Mod. in the AP that would affect the receiver sensitivity; in that case you would see poor signal quality with good signal strength...it does happen. But I would certainly try all of the other suggestions before determining this to be the problem.

Community Member

Re: Poor signal in Access Point 340 series

That's a good reminder for all of us who tend to look for too exotic an answer!

Matt

194
Views
0
Helpful
6
Replies
CreatePlease to create content