Reference transport channel on/off status detection and reselection

A wireless transmit receive unit (WTRU) comprising:

• a transmitter configured to transmit a composite channel on which a plurality of channels are multiplexed;
• an error rate measurement circuit to perform measurements on received signals on a reference channel selected from the plurality of multiplexed channels for use in selectively controlling transmission of the composite channel;
• and composite channel received signal processing circuitry comprising:
• monitor circuitry configured to monitor the selected reference channel based on a quantitative data content criteria to determine an ON state when the quantitative data content criteria is met and an OFF state when the quantitative data content criteria is not met;
• and
• reference channel circuitry configured to be responsive to the monitoring circuitry such that when monitoring of the reference channel reflects an OFF state, the reference channel selection circuitry selects a different channel from the plurality of multiplexed channels as the reference channel for the error measurement circuitry and the monitoring circuitry, wherein:
• the channels are transport channels (TrCHs);
• the reference channel is a reference transport channel (RTrCH),
• each TrCH has a transport time interval (TTI) of a given size of which a largest TTI size is an integer multiple,
• the TrCHs are multiplexed on a coded composite transport channel (CCTrCH),
• the error rate measurement circuitry is configured to perform a block error rate measurement on the RTrCH;
• the monitoring circuitry is configured to monitor the RTrCH no less than during each time interval corresponding to the TTI size of the RTrCH;
• the TrCHs each have a block error rate (BLER) requirement;
• the reference channel circuitry is configured with a TrCH having a least restrictive BLER requirement as the default TrCH selection initially used as the RTrCH;
• there are N number of TrCHs multiplexed onto the CCTrCH;
• the reference channel selection circuitry is configured to assign a preference level for selection to the TrCHs, first through Nth, the first preference level being highest, based first on their BLER requirement and then on TTI size such that the first TrCH has a least restrictive BLER requirement and a smallest TTI size among TrCHs having the same BLER requirement;
• the Nth TrCH has a most restrictive BLER requirement and a largest TTI size among TrCHs having the same BLER requirement;
• and
• the first TrCH is selected as the RTrCH initially used for error rate measurement.