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New Member

Poor throughput ( retries on transmit )

I'm using a MC4800 workgroup bridge to connect to my ISP. The MC4800 is running at full power (100mw) and is attached via 25' of LMR400 to a 16.5dbi panel with clear LOS to their AP/Bridge.

The AP/Bridge is a BR-500 located about 1.5 miles away accross a valley. It is amplified and connected to an Omni on a tower.

When I run the multicast link tests, I get back "FAIR" results with 21% loss. The Unicast test also return "FAIR" with 20% retries. Overall, the radio statistics show a large number CRC errors on the recieve side and lots of retries (1000's) and excessive retries (100's) on the transmit side over a

24hr period.

My problem seems to be in our ability to upload data. If we try and dowload

data from the internet, we get good performance ( ~2Mbs ). If someone tries to download from us, they get poor performance ( 200kbs ) !

Is this simply an issue of the AP not being able to hear the MC ? Should I

increase the gain on our end ?


New Member

Re: Poor throughput ( retries on transmit )

1) There could be an asymmetric link in the path somewhere. This might account for a speed difference, but not the retries.

2) The other end might be hearing interference, or another of their customers. Since the ISP is using an omnidirectional antenna, they might be receiving signals that do not show up on your directional antenna.

New Member

Re: Poor throughput ( retries on transmit )

Because of the high CRCs, that would usually point to some type of interference or frequency issue. Check with the ISP about their recommended channel settings, making sure of what channels their other wireless clients may be using.

Also, the BR500 uses a 100mw radio and, depending on the omni antenna gain, adding amps to the system may be an FCC violation. Additionally, depending on the amp output, there is the potential of frequency saturation, or overpowering, which could cause the CRC errors as well.