Method and device for the synchronization between a base radio station and a mobile radio station in a digital radiomobile system

Claim 1

A method for the synchronization between a mobile radio station having a local oscillator, oscillating at a local oscillator frequency, and a base station in a digital radiomobile system, where the base station transmits a signal including modulated bits transmitted at a bit transmission frequency, in at least a first timeslot, a sinusoid having a frequency equal to 1/p, p being an integer, of the bit transmission frequency and in a second timeslot a preamble known by the mobile station, comprising the steps of: (a) demodulating said signal to produce a demodulated signal; (b) sampling the demodulated signal with a frequency equal to 1/p of the bit transmission frequency to produce samplings and measuring the phase increases between two samplings; (c) comparing said phase increases with a first threshold value, assigning a first binary value to each or said phase increases when an increase is larger than said first threshold value and assigning a second binary value when an increase is not larger than said first threshold value; (d) constructing a vector formed with a number n, n being an integer, of said binary values assigned to each of said phase increases; (e) calculating the sum of said number n of said binary values forming the vector and updating the vector and the sum at each new sampling; (f) identifying a minimum of a function of the sum with respect to time; (g) calculating a frequency offset of the local oscillator frequency as a function of the identified minimum.

Claim 2

A method for the synchronization between a mobile radio station having a local oscillator, oscillating at a local oscillator frequency, and a base station in a digital radiomobile system, where the base station transmits a signal including modulated bits transmitted at a bit transmission frequency, in at least a first timeslot, a sinusoid having a frequency equal to 1/p, p being an integer, of the bit transmission frequency and in a second timeslot a preamble known by the mobile station, comprising the steps of: (a) demodulating said signal to produce a demodulated signal; (b) sampling the demodulated signal with a frequency equal to 1/p of the bit transmission frequency to produce samplings and measuring the phase increases between two samplings; (c) comparing said phase increases with a first threshold value, assigning a first binary value to each or said phase increases when an increase is larger than said first threshold value and assigning a second binary value when an increase is not larger than said first threshold value; (d) constructing a vector formed with a number n, n being an integer, of said binary values assigned to each of said phase increases; (e) calculating the sum of said number n of said binary values forming the vector and updating the vector and the sum at each new sampling; (f) identifying a minimum of a function of the sum with respect to time; (g) calculating a frequency offset of the local oscillator frequency as a function of the identified minimum.

Claim 16

A device for the synchronization of a mobile radio station including a local oscillator oscillating at a local oscillator frequency and a base station in a digital radiomobile system where the base station transmits modulated bit values transmitted at a bit transmission frequency and at least in a first timeslot, a sinusoid having frequency equal to 1/4 of the bit transmission frequency and in a second timeslot a preamble known by the mobile station, the device comprising: a converter circuit including a conversion table outputting a phase value; a first shift register connected to the output of said converter circuit, the output of said register being connected to a circuit for the calculation of a correction voltage for the local oscillator of the mobile radio station; a subtractor circuit connected to the output of the converter circuit for subtracting a first phase value from a second phase value output from the converter circuit, whose output is connected to the input of a comparator whose other input is a reference voltage; a second shift register whose input is connected to the output of said comparator, including cells, each being connected to an input of a multi-input adder; means for the determination of the minimum value of the signal outgoing said adder over a period of time.

Claim 17

A device for the synchronization of a mobile radio station including a local oscillator oscillating at a local oscillator frequency and a base station in a digital radiomobile system where the base station transmits modulated bit values transmitted at a bit transmission frequency and at least in a first timeslot, a sinusoid having frequency equal to 1/4 of the bit transmission frequency and in a second timeslot a preamble known by the mobile station, the device comprising: a converter circuit including a conversion table outputting a phase value; a first shift register connected to the output of said converter circuit, the output of said register being connected to a circuit for the calculation of a correction voltage for the local oscillator of the mobile radio station; a subtractor circuit connected to the output of the converter circuit for subtracting a first phase value from a second phase value output from the converter circuit, whose output is connected to the input of a comparator whose other input is a reference voltage; a second shift register whose input is connected to the output of said comparator, including cells, each being connected to an input of a multi-input adder; means for the determination of the minimum value of the signal outgoing said adder over a period of time.

Claim 22

An apparatus for synchronizing a mobile radio station having a local oscillator, oscillating at a local oscillator frequency, and a base station in a digital radio system, where the base station transmits a signal including modulated bits transmitted at a bit transmission frequency, in at least a first timeslot, a sinusoid having a frequency equal to 1/p, p being an integer, of the bit transmission frequency and in a second timeslot a preamble known by the mobile station, the apparatus comprising: a demodulator, demodulating said signal to produce a demodulated signal; a sampler, sampling the demodulated signal with a frequency equal to 1/p of the bit transmission frequency to produce samplings; a measurer, measuring the phase increases between two samplings; a comparator, comparing the phase increases with a first threshold value and assigning a first binary value to each of the phase increases when an increase is larger than the first threshold value and assigning a second binary value when an increase is not larger than the first threshold value; a register, storing a vector formed with a number n of said binary values assigned to each of said phase increases, n being an integer; an adder, summing the n binary values stored in said register creating a sum, and updating the sum at each new sampling; means for identifying a minimum of a function of the sum with respect to time; means for calculating a frequency offset of the local oscillator frequency responsive to the identifying means.

Claim 23

An apparatus for synchronizing a mobile radio station having a local oscillator, oscillating at a local oscillator frequency, and a base station in a digital radio system, where the base station transmits a signal including modulated bits transmitted at a bit transmission frequency, in at least a first timeslot, a sinusoid having a frequency equal to 1/p, p being an integer, of the bit transmission frequency and in a second timeslot a preamble known by the mobile station, the apparatus comprising: a demodulator, demodulating said signal to produce a demodulated signal; a sampler, sampling the demodulated signal with a frequency equal to 1/p of the bit transmission frequency to produce samplings; a measurer, measuring the phase increases between two samplings; a comparator, comparing the phase increases with a first threshold value and assigning a first binary value to each of the phase increases when an increase is larger than the first threshold value and assigning a second binary value when an increase is not larger than the first threshold value; a register, storing a vector formed with a number n of said binary values assigned to each of said phase increases, n being an integer; an adder, summing the n binary values stored in said register creating a sum, and updating the sum at each new sampling; means for identifying a minimum of a function of the sum with respect to time; means for calculating a frequency offset of the local oscillator frequency responsive to the identifying means.