Appendix A: Making Air Traces Of 802.11 Traffic - ASCOM i62 Troubleshooting Manual

Troubleshooting Guide
Ascom i62 VoWiFi Handset

Appendix A: Making Air Traces of 802.11 Traffic

Ascom recommends Omnipeek from Wildpackets as the airtrace tool for capturing data on a
designated channel. The tool can employ several WLAN adapters simultaneously in
promiscuous or monitor mode to capture the data.
Note: If other air trace tools than Omnipeek are used, the traces must be saved in Packet
Capture (PCAP) format. This is a TAC requirement.
Prerequisite
• The support engineer should have already investigated and ruled out relatively easy to
identify causes such as incorrectly configured parameters and incompatible software
versions.
• Layer 1 problems, that is, RF problems, should also have been investigated and
eliminated as a cause of a problem through a site survey and by doing a site survey and
spectrum analysis. Problems like co-channel interference, under or over coverage, rogue
WLAN transmitters and analog interference sources should also have been addressed.
Requirements
To perform an air trace, the support engineer should be equipped with the following:
• A portable PC
• The Omnipeek Airtrace tool. This is used to take wireless sniffer traces of:
- The AP that is transmitting
- The handset that is transmitting
- Other air traffic
• 3 WLAN adapters for the g-radio band (dual band is recommended) and 4WLAN
adapters for the a-radio band
Note: If there is only one specific problem that is easy to reproduce, one WLAN adapter is
sufficient.
Prerequisites
It is important to note the following before starting a trace:
• Captured traces might not be 100% true. The trace consists of data heard by the
adapters, which may miss data transmitted by handset or AP. It is therefore
recommended to take several captures to ensure that a complete data flow is logged.
• If more than one handset is used for the trace and the handsets are placed too close
together, RF disturbances between the handsets may occur.
To optimise the trace, ensure that:
• The distance between handset and adapter should be no less than 50cm and no more
than 100cm
• A clear line-of-sight exists between the handset and the adapter
• The adapter is placed between AP and handset
Note: If the handset is already experiencing WLAN communication problems, it is not
recommended to enable RPCAP tracing in the Admin menu because this will generate
additional WLAN traffic.
28 June 2012 / Ver. A
Appendix A: Making Air
TD 92685EN
62