摘要:
A method enables the introduction of a 200 kHz GSM-type network into a TDMA system having a bandwidth that is substantially less than a 2.5 MHz bandwidth normally employed for GSM-type networks. The method provides a 52-multiframe containing 12 blocks of four consecutive frames, two idle frames, and two control channels, and rotates the control channels belonging to a serving time group over odd timeslot numbers as 7, 5, 3, 1, 7, 5, . . . , etc. Preferably the rotation occurs between frame numbers (FN) mod 52=3 and 4. Information specifying at least the rotation direction is signalled to the mobile station in a downlink synchronization channel.
摘要:
A method is disclosed to distinguish a first type of control channel from a second type of control channel. The method includes steps of (a) transmitting a carrier of the first type of control channel so as to include a first symbol sequence that results, when demodulated, in a sine wave having a frequency with a first offset from the carrier; (b) transmitting a carrier of the second type of control channel so as to include a second symbol sequence that results, when demodulated, in a sine wave having a frequency with a second offset from the carrier; and (c) demodulating a received carrier and detecting whether the carrier includes the first type of control channel of the second type of control channel. In the preferred embodiment of this invention the first symbol sequence is an all zeroes sequence, and the second type of symbol sequence is an alternating ones and zeroes sequence, which results in the first offset being a positive offset, and the second offset being a negative offset. In a most preferred embodiment the first offset is +67.7 kHz, and the second offset is −67.7 kHz. The step of demodulating includes a step of multiplying an I/Q representation of the received symbol sequence by 1−j, −1 j, 1−j, . . . , and by 1 j, −1−j, 1 j, . . .
摘要:
A method for frame quality detection and a receiver for implementing the method. For frame quality detection, results A and B are compared with each other and with a predetermined threshold. The result A is formed as a sum/product of soft bit decisions or as a bit error rate from bursts comprising bits from successive frames N and N+1. The result B is formed in the same way from frames N-1 and N. When comparing the result A and the result B with each other, the frame N is determined to be bad if one of the result A and the result B is essentially smaller than another of the result A and the result B. The frame N is also determined to be bad if the both result A and the result B are smaller than the predetermined threshold value. The method improves detection of a bad frame and accordingly reduces interference sound received by a receiver and caused by erroneously interpreted bad frames, especially during periods of silence.
摘要:
A radio frequency (RF) modem for a mobile communications device comprises a monitoring circuit; an RF circuit having a demodulator, the RF circuit being for receiving RF signals; a baseband processing unit, for processing baseband signals; and a controller. The RF modem can enter a sleep mode in which the monitoring circuit is operational and the RF circuit and the baseband processing unit are not operational. The controller is responsive to an indication from the monitoring circuit to control the RF modem to enter a monitoring mode in which the RF circuit is operational and the baseband processing unit is not operational. The RF circuit is configured for data reception in the monitoring mode. The controller then controls the RF modem to exit the monitoring mode and to enter a baseband processing mode in which the baseband processing unit is operational to process data signals provided by the RF circuit.
摘要:
A method of detecting a call set-up burst, and a receiver, in a digital radio system, the receiver comprising a converter (304) for sampling a signal received in a given time slot, means (400) for correlating digitalized samples with a known training sequence, and means (402) for computing the energy of the correlation results obtained, means (404) for looking for the maximum values of a string of samples of a given order from the computed energies, and means (408) for averaging the maximum values found per one sample. To improve reliability of detecting a call set-up burst, the receiver comprises means (410) for averaging the energy of the other samples of the time slot per one sample, and means (412) for comparing the averaged maximum energy values with the energy values of the other samples.
摘要:
A method and a system for expanding the capacity for transmission of information in a data frame which comprises at least an information element and a control element. After the data frame is subjected to channel coding, a portion of the control element is either removed or replaced by a divided portion of the information to be transmitted in the data frame.