This object represents the channel characteristics
of the PHY. The semantics are as follows.
legacyMode - The radio channel characteristics are the
same as that of 802.11a/802.11g radios.
htMode - The radio operates in either 40MHz
bandwidth with one to four spatial streams.
dupLegacyMode - The radio operates in a 40MHz
channel composed of 2 adjacent 20MHz channels.
The packets sent are in the legacy 802.11a format
in each of the 20MHz channels.
fortyMHzUpperMode - The radio tranmits a legacy or
HT packet in the upper 20MHz channel of a 40MHz
channel.
fortyMHzLowerMode - The radio transmits a legacy or
HT packet in the lower 20MHz channel of a 40MHz
channel.