AP-350 slight packet loss when streaming audio

rogerbutler · ‎02-13-2003

I have an AP-350 running as an infrastructure access point connecting 4 Compaq iPAQs to a server PC. The cable between the AP and the PC is a crossover cat5. The iPAQs are running DLink 660W compact-flash 802.11b cards. The problem is that I'm losing a packet every second or two in transmit from the PC to the iPAQs.

This matters because I'm trying to stream audio from the iPAQs to the PC and then back again. There is no packet loss on receive, only on transmit. The problem goes away when I used a wired ethernet compact-flash card in the iPAQs so it's definitely a wireless problem.

The problem isn't affected by the number of iPAQ clients connected. It occurs with 1 or all 4. The difference between receive and transmit is that the receive packet size is 566 bytes and the transmit is 1078. I've tried all the AP-350 options, like setting the number of retry packets, selecting other channels, etc, with no luck. The compact-flash DLink cards don't provide many parameters to play with.

Any suggestions?

derwin · ‎02-16-2003

Do you have any CRC errors or discards ???

I would guess you have some interference and the packets are being dropped as CRC errors

Try another Channel and a better placement of the AP

rogerbutler · ‎02-16-2003

I have a few CRC errors but none significant. I've tried both placement and other channels with no luck.

derwin · ‎02-16-2003

Have you tried this with a Cisco Client PCMCI card ? What about with a laptop instead of the IPAQ's

rogerbutler · ‎02-16-2003

No, I haven't tried with a Cisco PCMCI. Is there a compact flash version? I have tried with a D-Link 660W and a Netgear one.

I can't run the client software on a laptop (it requires WinCE) but I can run a packet sniffer while the client is running on an iPAQ. The sniffer gets slightly better results than the iPAQ software (losing 1 in 500 packets instead of 1 in 250). The laptop has a Compaq 110 PCMCIA card.

Placement of the antennae doesn't seem to be a problem because I'm operating the AP-350 and the client 2m from each other in free air.

derwin · ‎02-16-2003

I can't run the client software on a laptop (it requires WinCE) but I can run a packet sniffer while the client is running on an iPAQ. The sniffer gets slightly better results than the iPAQ software (losing 1 in 500 packets instead of 1 in 250). The laptop has a Compaq 110 PCMCIA card.

This would point to a problem with the IPAQ/CF adapter you are using.

Cisco does not make a compact flash adapter but you can get a PCMCI sleeve for the IPAQ you could try this with a Cisco client card to eliminate the current client cards you are using as the cause of the problem

I also strongly recommend that you load the latest ROM updates for you IPAQ

What is the model number and brand of the Compact Flash cards you are using ?

rogerbutler · ‎02-16-2003

It is possible that there's a client adapter problem but all four cards I've tried are getting bad results:

D-Link DCF-650W CF

D-Link DCF-660W CF

Netgear MA701 CF

Compaq WL110 PCMCIA

The iPAQs are running the latest ROM, v2.20 of Pocket PC 2002.

I'll see if I can get my hands on a Cisco client and sleeve. Thanks.

derwin · ‎02-16-2003

Not a single one of those cards you have listed are WiFi certified, or at least are not on the WiFi site as certified.

http://www.weca.net/OpenSection/Certified_Products.asp?TID=2

Inter vendor operation can not be gauranteed with non certifed devices and as such are not supported.

I would check with the vendors of these cards to see if they are WiFi certified, but typically the WiFi site is pretty much up to date.

I would try the Cisco card or see if you can get a WiFi certified CF adapter