User's Manual

CHAPTER FIVE - CONECTIVITY
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Hint: In case of troubles with WLAN connection establishment, you may
capture WLAN frames using WLAN protocol analyzer (of course,
assuming that you have an analyzer at your disposal). If it seems that your
PL3000 and your access point communicate with each other, and that the
analyzer can capture the wireless frames including the EAP request
(Header’s Code field: ‘1’; sent by the access point), in that case, check the
‘Type’ field in the EAP request message and see if the value matches the
value of the Auth Server setting (assuming that the ‘Type 1’ means the
value ‘1’ in the EAP ‘Type’ field.) If not, changing the value of the Auth
Server to correspond to the ‘Type’ value in the EAP request message may
help in getting rid of the problem. In addition, you may need to adjust an
‘Auth Timeout’.
• Auth Timeout: Like the Auth Server, this global setting has an effect on the
SDC Supplicant only. The Auth Timeout instructs the supplicant to wait for an
EAP request from an access point for a period of the Auth Timeout in seconds
before giving up waiting. The value of the Auth Timeout shall be set in the
range of 3 to 60 seconds. If it should happen that the timeout takes place, the
SDC Supplicant may prompt you to insert your EAP method-dependent
credentials although the EAP request is missing. However, if you specified the
credentials during the setting-up WLAN interface on your PL3000, as the
timeout takes place, a try at associating with the wireless LAN just ends
without notifying you of a missing EAP request.
• TX Diversity: Your PL3000 incorporates two WLAN antennas. By default the
PL3000 uses both the antennas for transmission. In other words, it utilizes
antenna diversity (aka space diversity). If you change a RX Diversity parameter
it may be reasonable to change the value of the Tx Diversity as well.
Otherwise, it is recommended that the radio uses Tx diversity, because it
typically guarantees best performance of the WLAN connectivity.
• RX Diversity: Radio signal’s quality at the receiver end is very vulnerable to
variations in the signal transmission path, especially when the antennas at the
receiver and transmitter ends move relative to each other. For that reason,
antenna diversity is used to get better probability to construct the most likely
transmitted signal at the receiver end. By default your PL3000 uses antenna
diversity for receiving transmitted messages, and more often than not, the
default value of the Rx diversity gives you the best performance of the WLAN
connectivity.
• Frag Thresh: The IEEE 802.11 wireless LAN uses a fragmentation threshold
in its medium access control (for short MAC). This parameter in the MAC can
be configured with the ‘Frag Thresh’ setting. Any frame longer than the value of
the fragmentation threshold, the MAC splits into smaller units for transmission.
The default value ‘2346’ is the maximum length of the MAC frame that can be
transmitted over the air. The minimum value that you can enter in the ‘Frag
Thresh’ field is 256. Be aware that setting this parameter is a trade-off between
a frame overhead and likelihood of getting a frame across to the access point
without errors. The shorter is the length of a frame the higher is the likelihood
of getting the frame through, but shorter frames generate more overhead for
transmission than longer ones.
• RTS Thresh: In the WLAN environment there is a common occurrence that
stations’ talks overlap, that is, more than one station transmits to an access
point at the same time. In general, this occurrence is referred to as hidden
node problem. Because of possible hidden nodes, WLAN stations use