I don't find you can define any time frame for this threshold monitoring. However, if you want to set time frame and do the threshold monitoring you can utilize SpectroWATCH. The following two OIDs are used to calculate Download/Upload volume of Mobile Stations within WLC.
1. bsnMobileStationBytesReceived OBJECT-TYPE
SYNTAX Counter64 (0 .. 9223372036854775807)
ACCESS read-only
STATUS current
DESCRIPTION
"Bytes received from Mobile Station"
::= { bsnMobileStationStatsEntry 2 }
-- 1.3.6.1.4.1.14179.2.1.6.1.2
2. bsnMobileStationBytesSent OBJECT-TYPE
SYNTAX Counter64 (0 .. 9223372036854775807)
ACCESS read-only
STATUS current
DESCRIPTION
"Bytes sent to Mobile Station"
::= { bsnMobileStationStatsEntry 3 }
-- 1.3.6.1.4.1.14179.2.1.6.1.3
Please also refer to https://www.ca.com/us/services-support/ca-support/ca-support-online/knowledge-base-articles.TEC1336663.html