Initial frequency synchronization mechanism

A cellular telephone base station comprising:

• an antenna;
• and
• a frequency synchronization device including at least:
• a frequency shift detector to detect a frequency difference between an internal frequency and a received frequency from a cellular telephone mobile station with respect to a reference frequency and to produce a frequency shift value;
• a non-linear controller to control an oscillator to generate said internal frequency in a range from a first frequency boundary to a second frequency boundary, and to provide said frequency shift value to said oscillator so that said oscillator adjusts said internal frequency according to said value;
• and
• a loop filter coupled to said frequency shift detector to filter said frequency shift value and to store information regarding previous frequency shifts and accordingly to determine a frequency shift direction.

A cellular telephone system comprising:

• a base station apparatus and a mobile station apparatus to communicate bidirectionally over a channel, and a neighboring transmitter apparatus to transmit on an adjacent channel,
• wherein said mobile station apparatus comprises:
• a transmitter to transmit radio frequency signals to said base station apparatus;
• a receiver to receive radio frequency signals from said base station apparatus;
• an intermediate frequency filter to substantially attenuate a carrier signal received from said neighboring transmitter apparatus relative to a carrier signal received from said base station apparatus;
• a frequency shift detector to detect a frequency difference between an internal frequency of said receiver and a received frequency from said base station apparatus with respect to a reference frequency and to produce a frequency shift value;
• a non-linear controller to control an oscillator to generate said internal frequency in a range from a first frequency boundary to a second frequency boundary, and to provide said frequency shift value to said oscillator so that said oscillator adjusts said internal frequency according to said value;
• and
• a loop filter coupled to said frequency shift detector to filter said frequency shift value and to store information regarding previous frequency shifts and accordingly to determine a frequency shift direction.

A cellular telephone system comprising:

• a base station apparatus and a mobile station apparatus to communicate bidirectionally over a channel, and a neighboring transmitter apparatus to transmit on an adjacent channel,
• wherein said base station apparatus comprises:
• a transmitter to transmit radio frequency signals to at least said mobile station apparatus;
• a receiver to receive radio frequency signals from at least said mobile station apparatus;
• an intermediate frequency filter to substantially attenuate a carrier signal received from said neighboring transmitter apparatus relative to a carrier signal received from said mobile station apparatus;
• a frequency shift detector to detect a frequency difference between an internal frequency of said receiver and a received frequency from said mobile station apparatus with respect to a reference frequency and to produce a frequency shift value;
• a non-linear controller to control an oscillator to generate said internal frequency in a range from a first frequency boundary to a second frequency boundary, and to provide said frequency shift value to said oscillator so that said oscillator adjusts said internal frequency according to said value;
• and
• a loop filter coupled to said frequency shift detector to filter said frequency shift value and to store information regarding previous frequency shifts and accordingly to determine a frequency shift direction.