Synchronization method for a mobile radiotelephone
DC CAFCFirst Claim
1. A method of synchronizing a mobile radiotelephone in a cellular digital mobile radiotelephone network comprising a plurality of fixed radiotelephone stations and a plurality of mobile radio stations operating in accordance with a GSM standard or its equivalent, in which each communication frequency assignment is subdivided into interleaved time slots, a plurality of said time slots together comprising a frame, comprising the following steps which are carried out in the mobile radiotelephone:
- (1) conducting an initial synchronization by means of a frequency correction burst substantially fully occupying a time slot with an unmodulated wave corresponding to repetition of bits of the same binary logic value;
(2) maintaining normal synchronization during communication by means of interspersed normal synchronization bursts, each normal synchronization burst containing a training sequence occupying less than a third of a time slot, and(3) performing extended synchronization during communication as a background procedure by means of interspersed frequency synchronization bursts, each frequency synchronization burst containing an extended training sequence occupying less than an entire time slot and more than a third of a time slot, and wherein;
said step of conducting said initial synchronization comprises the substeps of;
(1.1) conducting a coarse frequency synchronization,(1.2) conducting a coarse frame synchronization over a plurality of said time slots which comprise a frame,(1.3) conducting a fine frequency synchronization, and(1.4) conducting a fine frame synchronization over said plurality of time slots which comprise a frame;
said step of maintaining said normal synchronization comprises the substeps of;
(2.1) conducting a frame synchronization with fine frequency synchronization, and(2.2) carrying out preliminary data signal processing; and
said step of performing said extended synchronization comprises the substeps of;
(3.1) conducting a coarse frame synchronization, and(3.2) conducting a fine frame synchronization with fine frequency synchronization.
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Abstract
The high requirements of digital mobile radiotelephone communication under the GSM Standard with respect to synchronization of a mobile radiotelephone to a fixed radiotelephone station is performed by frequently (four times per so-called baseband frequency cycle) sampling contemporary in-phase and quadrature phase components of received GMSK digital signals and utilization of time slots respectively containing a frequency correction burst, a normal burst and an extended synchronization burst, respectively for initial synchronization, normal maintenance of synchronization during communication and a background procedure during normal operation. The decoding of the GMSK signal provides one-bit of information from each pair of in-phase and quadrature components sampled. The sampling of in-phase and quadrature components greatly simplifies the synchronizing procedure. Initial synchronization includes coarse frequency synchronization, coarse frame synchronization, fine frequency synchronization and fine frame synchronization. Normal maintenance of synchronization consists fine frame synchronization with fine frequency synchronization and a data signal preliminary processing. Extended synchronization consists of coarse frame synchronization and a fine frame synchronization with fine frequency synchronization.
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Citations
13 Claims
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1. A method of synchronizing a mobile radiotelephone in a cellular digital mobile radiotelephone network comprising a plurality of fixed radiotelephone stations and a plurality of mobile radio stations operating in accordance with a GSM standard or its equivalent, in which each communication frequency assignment is subdivided into interleaved time slots, a plurality of said time slots together comprising a frame, comprising the following steps which are carried out in the mobile radiotelephone:
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(1) conducting an initial synchronization by means of a frequency correction burst substantially fully occupying a time slot with an unmodulated wave corresponding to repetition of bits of the same binary logic value; (2) maintaining normal synchronization during communication by means of interspersed normal synchronization bursts, each normal synchronization burst containing a training sequence occupying less than a third of a time slot, and (3) performing extended synchronization during communication as a background procedure by means of interspersed frequency synchronization bursts, each frequency synchronization burst containing an extended training sequence occupying less than an entire time slot and more than a third of a time slot, and wherein; said step of conducting said initial synchronization comprises the substeps of; (1.1) conducting a coarse frequency synchronization, (1.2) conducting a coarse frame synchronization over a plurality of said time slots which comprise a frame, (1.3) conducting a fine frequency synchronization, and (1.4) conducting a fine frame synchronization over said plurality of time slots which comprise a frame; said step of maintaining said normal synchronization comprises the substeps of; (2.1) conducting a frame synchronization with fine frequency synchronization, and (2.2) carrying out preliminary data signal processing; and said step of performing said extended synchronization comprises the substeps of; (3.1) conducting a coarse frame synchronization, and (3.2) conducting a fine frame synchronization with fine frequency synchronization. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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Specification