There is provided a supplemental channel assigning apparatus and method in
a mobile communication system. In the supplemental channel assigning
method, a mobile station receives a plurality of supplemental channel
assignment messages successively from a base station on an existing
traffic channel, each of the channel assignment messages having the
fields of a start time, a duration, a sequence number for message
identification, and a channel identifier for channel identification, and
stores the received channel assignment messages in a memory according to
the durations and sequence numbers of the channel assignment messages.
The mobile station then conducts data communication on a channel
corresponding to the channel identifier of a first read channel
assignment message for a period between the start time and the end of the
duration set in the read channel assignment message and then on a channel
corresponding to the channel identifier of a next read channel assignment
message for a period between the start time and the end of the duration
set in the next channel assignment message, the start time of the next
channel assignment message being set to or after the end of the data
communication according to the first read channel assignment message.