Apparatus and method for transmitting a control message on a packet data control channel in a mobile communication system supporting a packet data service

An apparatus for transmitting Walsh information over a packet data control channel in a base station of a mobile communication system that transmits packet data and has the packet data control channel for transmitting control information related to transmission of packet data, the apparatus comprising:

• decoders for decoding reverse ACK channel (R-ACKCH) signals received from corresponding mobile stations;
• first counters being identical in number to the decoders, for counting NAKs if the NAKs are continuously output from corresponding decoders;
• a Walsh mask broadcasting controller for receiving the number of NAKs from the counters, and outputting a Walsh mask information broadcasting enable signal if the number of NAKs is larger than a predetermined threshold;
• and
• a transmitter for generating and broadcasting Walsh mask information of the base station upon receiving the Walsh mask information broadcasting enable signal.