Mobile station having improved DCCH synchronization

A method for operating a mobile station, comprising the steps of:

• receiving a forward channel from a base station, the forward channel being transmitted to contain repeating frames each comprising N time slots, individual ones of the time slots including a synchronization word;
• correlating an i.sup.th one of the N time slots using a first correlation sequence and a second correlation sequence to obtain a first correlation result and a second correlation result, respectively;
• and
• declaring the forward channel to be one of a half-rate channel or a full-rate channel based on the first and second correlation results,
• wherein a first N/2 of the time slots are transmitted to have a same sequence of N/2 synchronization words whether the channel is a half-rate channel or a full-rate channel, and wherein i is equal to (N/2)+1.

A mobile station, comprising:

• a receiver and demodulator for receiving and demodulating a forward channel from a base station, the forward channel being transmitted to contain repeating frames each comprising N time slots, individual ones of the time slots including a synchronization word;
• a memory storing a plurality of predetermined synchronization sequences;
• a correlator for correlating a single i.sup.th one of the N time slots output from the demodulator using a first correlation sequence and a second correlation sequence stored in the memory to obtain a first correlation result and a second correlation result, respectively, the first correlation sequence being one that is known to be transmitted in the i.sup.th one of the time slots when operating as a half-rate channel, and the second correlation sequence being one that is known to be transmitted in the i.sup.th one of the time slots when operating as a full-rate channel;
• and
• a controller coupled to the correlator for declaring the forward channel to be one of a half-rate channel or a full-rate channel based on the first and second correlation results that are obtained from the single i.sup.th one of the N time slots.

A mobile station, comprising:

• a receiver and demodulator for receiving and demodulating a forward channel from a base station, the forward channel being transmitted to contain repeating frames each comprising N time slots, individual ones of the time slots including a synchronization word;
• a memory storing a plurality of predetermined synchronization sequences;
• a correlator for correlating an i.sup.th one of the N time slots output from the demodulator using a first correlation sequence and a second correlation sequence stored in the memory to obtain a first correlation result and a second correlation result, respectively;
• and
• a controller coupled to the correlator for declaring the forward channel to be one of a half-rate channel or a full-rate channel based on the first and second correlation results,
• wherein a first N/2 of the time slots are transmitted to have a same sequence of N/2 synchronization words whether the channel is a half-rate channel or a full-rate channel, and wherein i is equal to (N/2)+1.

A method for operating a mobile station, comprising the steps of:

• receiving a forward channel from a base station, the forward channel being a digital control channel (DCCH) that is transmitted to contain repeating frames each comprising N time slots, individual ones of the time slots including one of N predetermined synchronization words;
• correlating a single i.sup.th one of the N time slots using a first correlation sequence and a second correlation sequence to obtain a first correlation peak and a second correlation peak, respectively, the first correlation sequence being one that is known to be transmitted in the i.sup.th one of the time slots when operating as a half-rate DCCH, an d the second correlation sequence being one that is known to be transmitted in the i.sup.th one of the time slots when operating as a full-rate DCCH;
• comparing magnitudes of the first and second correlation peaks to at least one threshold value, the first and second correlation peaks being those that are obtained from the single i.sup.th one of the N time slots;
• and
• declaring the DCCH to be one of a half-rate DCCH or a full-rate DCCH based on the result of the step of comparing.

A method for operating a mobile station, comprising the steps of:

• receiving a forward channel from a base station, the forward channel being a digital control channel (DCCH) that is transmitted to contain repeating frames each comprising N time slots, individual ones of the time slots including one of N predetermined synchronization words;
• correlating an i.sup.th one of the N time slots using a first correlation sequence and a second correlation sequence to obtain a first correlation peak and a second correlation peak, respectively;
• comparing magnitudes of the first and second correlation peaks to at least one threshold value;
• and
• declaring the DCCH to be one of a half-rate DCCH or a full-rate DCCH based on the result of the step of comparing,
• wherein a first N/2 of the time slots are transmitted to have a same sequence of N/2 synchronization words whether the channel is a half-rate channel or a full-rate channel, and wherein i is equal to (N/2)+1.