Method and apparatus for distinguishing control channel from traffic channels

DETAILED DESCRIPTION It is accordingly an object of the present invention to speed up the process of discriminating between traffic and control channels in a received signal.
Another object of the invention is to confirm the accuracy of control-channel identification.
A further object is to reduce memory requirements for discrimination between traffic and control channels.
The invented apparatus and method discriminate between a traffic channel carrying coded traffic data and a coded control-channel locator value, and a control channel carrying convolutionally coded control data and a coded super-frame phase value.
The invented method comprises the steps of: checking a flag designating a received channel as a traffic channel, a control channel, or an unidentified channel; decoding the coded locator value, if the flag designates the channel as a traffic channel, to obtain information for locating the control channel; decoding and detecting errors in the coded control data and coded super-frame phase value, if the flag does not designate the channel as a traffic channel; incrementing a counter responsive to paucity or absence of these errors, if the flag indicates that the channel is still unidentified; and setting the flag to indicate that the channel is a control channel, when the counter reaches a threshold value.
The invented method preferably also comprises some or all of the following further steps: convolutionally re-encoding the decoded control data, and comparing the coded control data and re-encoded control data to determine whether the above-mentioned paucity of errors exists; incrementing the above counter when the coded super-frame phase value is decoded to an expected value; confirming the identification of the channel as a control channel, by checking whether the coded super-frame phase value is decoded to the expected value; decoding and detecting errors in the coded locator value, if the flag designates that the channel is still unidentified and the threshold value has not yet been reached; and setting the flag to designate the channel as a traffic channel, responsive to absence of errors in the coded locator value