JP2616112B2 - Mobile communication base station receiver - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention is applied to a base station receiver which receives digitally modulated radio waves from a plurality of mobile stations in a time-division manner. Especially,
The present invention relates to means for maintaining an optimal sampling timing during demodulation.

〔Overview〕

The present invention provides means for maintaining a sampling timing at the time of burst demodulation in a base station receiving apparatus for receiving bursts from a plurality of mobile stations in a time-sharing manner at an optimum value. By storing the sampling timing of this one and reusing it when receiving this burst from this one mobile station, stable synchronization can be achieved.

[Conventional technology]

In conventional mobile communication, frequency division multiplexing (FDM) is used, and a base station receiver continuously receives radio waves from one mobile station. After finding the sampling timing, it was better to follow the slow timing fluctuation while receiving data. In addition, digital PLLs have been frequently used for such initial timing acquisition and subsequent synchronization maintenance. An example is shown in FIG.

[Problems to be solved by the invention]

However, when the time division multiplexing method is introduced, the receiver of the base station receives radio waves from a plurality of mobile stations in order, so that the conventional means for searching for and following the optimum sampling timing cannot be used. There are two reasons. There is a high probability that the optimum sampling timing differs for each mobile station.
If you are looking for timing, you will always sample near the beginning of the burst at suboptimal timing,
Also, a gap is required between bursts of each mobile station,
During that time, the receiver receives only noise, so digital PL
L may cause out-of-sync due to the effect of this noise, and unless the line is used at full multiplicity, an empty slot is created and only noise is received during this time. become.

SUMMARY OF THE INVENTION An object of the present invention is to provide a mobile communication base station receiving apparatus capable of achieving stable synchronization for each mobile station transmitter.

[Means for solving the problem]

The present invention is provided in a mobile communication base station that communicates with a plurality of mobile station transmitters, a frame arriving from the mobile station transmitter is a digital modulation wave, and a timing at which a detection output of the digital modulation wave is sampled. In a mobile communication base station receiving apparatus comprising a phase locked loop circuit for generating a given clock pulse and a decoding circuit for decoding a sampled detection output, A first memory for temporarily storing the phase information of the phase locked loop circuit, a second memory provided for each of the frames, and a second memory provided for the one of the frames for storing the contents of the first memory. Control means for providing the data to the memory, and the contents stored in the second memory being updated at a second time near the start of reception of the next frame corresponding to the memory. Characterized by comprising a setting means for setting an initial phase of the phase locked loop circuit.

Here, it is preferable that a timing generating means is provided which determines each of the first time point and the second time point at a time point limited to a portion excluding a leading edge and a trailing edge of the frame related to the second memory.

Further, it is preferable that the apparatus further comprises a determination means for invalidating the control means when it is determined that the decoding result of the decoding circuit indicates a frame loss.

[Action]

Last sampling of previous burst from mobile station
The timing is stored, and when the current burst from the same mobile station starts to be received, the previously stored timing is reused. That is, the number of memories for storing the phase information of the digital PLL is set according to the number of TDM multiplexes, and the stored value is set in the digital PLL as an initial phase. In order to eliminate the influence on the phase shift during the unstable period at the end of the burst, the phase correction operation of the digital PLL is prohibited. In addition, a change in the state of the transmission line due to the movement of the mobile station or a lack of a burst that occurs when the mobile station temporarily omits transmission in order to reduce battery consumption (a time slot for receiving radio waves from the mobile station). Only noise
In order to prevent the synchronization from being lost due to receiving only a very distorted signal whose content is unknown), when the decoding result is bad, the refresh at the optimal timing is prohibited and the previously stored timing is retained.

〔Example〕

Hereinafter, the present invention will be described with reference to the drawings. First
FIG. 2 is a block diagram showing a configuration of a receiver embodying the present invention when the number of time division multiplexing is 3, and FIG. 2 is a timing chart showing an operation state of each unit.

As shown in FIG. 1, this embodiment is provided in a mobile communication base station that communicates with a plurality of mobile station transmitters, and a frame arriving from this mobile station transmitter includes the transmitted mobile station transmitter. A digital PLL6, which is a phase-locked loop circuit that generates a clock pulse that provides timing for sampling the detection output of a digital modulation wave obtained by time-division multiplexing of this frame and decodes the sampled detection output And a first memory for temporarily storing phase information of the phase locked loop circuit at a first time point near one end time point of one of the frames. A temporary storage memory 7, memories 9, 10 and 11, which are second memories provided for each of the frame numbers, A switch 16 which is a control means for giving to a second memory provided in correspondence with one, and stores the contents stored in the second memory in the vicinity of the start of reception of a subsequent frame having a frame number corresponding to this memory. Setting means switch 17 for setting as an initial phase of the phase locked loop circuit at a second time point, and further, each of the first time point and the second time point of a frame having a frame number related to the second memory. A timing generating means for determining a time point limited to a portion excluding a leading edge and a trailing edge; and disabling the control means when it is determined that the decoding result of the decoding circuit indicates a frame loss. A determination circuit 8 serving as a determination unit and a switch 15 are provided.

Next, the operation when the receiver receives a signal from the first mobile station will be described with time. The transmission from the third mobile station ends and the reception of the signal from the first mobile station starts, and the clock component extraction circuit 5 starts to stably output the clock component according to the signal from the first mobile station. Switch 13 is open and the digital
The PLL 6 enters a free-running state and does not perform a phase correction operation. During this period, the switch 17 is connected to the memory 9, and the phase value stored when the signal from the first mobile station was previously received is read out and loaded into the digital PLL 6. Thereafter, the switch 13 is closed, and the digital PLL 6 starts following operation. Since the following operation is performed while the transmission of the first mobile station continues, it is corrected if it deviates from the optimal sampling timing. When the first mobile station finishes transmitting, the radio wave gradually weakens and becomes only noise. Therefore, just before the timing when transmission should end, switch 13
Open to set the digital PLL6 to the free-running state and maintain the phase. Then, the switch 14 is closed and this phase is stored in the temporary storage memory 7. Subsequently, after the decoding of the decoding circuit 4 is completed, the judgment circuit 8 judges from the decoding result whether the phase value stored in the temporary storage memory 7 is worth the use as the next initial phase. This determination is to avoid that during the period when the radio wave from the first mobile station should be received, the mobile station has actually stopped transmitting and the partner whose phase was followed by the digital PLL 6 was noise, etc. Done in Therefore, a specific criterion is whether or not a fixed pattern (such as a synchronization signal) to be included in a signal can be detected with a certain number of errors or less. Or not. If the result of this determination is good, the switch 15 is closed and the phase value stored in the temporary storage memory 7 is transferred to the memory 9. (At this point, the switch 16 has been switched to the path to the memory 9.) However, if the determination result indicates a failure, the switch 15 is left open and the memory 9 is turned off.
Retains the previous value. At the timing when the first mobile station should transmit again through the above procedure, the same operation is repeated.

The case where the radio wave from the first mobile device is received has been described above.
The same circuit is used for the mobile device and the third mobile device in time division. At this time, the memory 10 and the memory 11 are used instead of the memory 9.

〔The invention's effect〕

As described above, according to the present invention, by storing the following phase values in the number of phase memories corresponding to the number of multiplexes, it is not necessary to re-establish synchronization every time, and the effect of achieving stable synchronization can be obtained. is there. Furthermore, by referring to the decoding result and storing the phase value stored before the abnormal phase value without storing the abnormal phase value, when there is a temporary deterioration of the quality of the transmission path or a temporary interruption of the mobile device, However, there is an effect that out of synchronization does not occur.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention. FIG. 2 is an explanatory diagram showing a state change of each unit of the receiver in FIG. 1 in a time series. FIG. 3 is a block diagram showing the configuration of a conventional example. DESCRIPTION OF SYMBOLS 1 ... High frequency circuit, 2 ... Detection circuit, 3 ... Sampling circuit, 4 ... Decoding circuit, 5 ... Clock component extraction circuit, 6 ... Digital PLL, 7 ... Temporary storage memory, 8 ...
... Judgment circuits, 9 to 11... Memories, 12... Timing generation circuits, 13 to 17.

Claims (3)

(57) [Claims] 1. A frame provided in a mobile communication base station communicating with a plurality of mobile station transmitters, a frame coming from the mobile station transmitter is a digital modulation wave, and a timing for sampling a detection output of the digital modulation wave. A phase locked loop circuit that generates a clock pulse that gives the following, and a decoding circuit that decodes the sampled detection output, the mobile communication base station receiver, at a first time near the end time of one of the frames A first memory for temporarily storing the phase information of the phase locked loop circuit, a second memory provided for each frame, and a second memory provided for the content stored in the first memory corresponding to one of the frames. Control means for providing the second memory with the contents stored in the second memory, a second time near the start of reception of the next frame corresponding to the memory; Setting means for setting as an initial phase of the phase locked loop circuit, and limiting each of the first time point and the second time point to a portion excluding a leading edge portion and a trailing edge portion of a frame related to the second memory. A mobile communication base station receiving apparatus comprising: timing generation means for determining a time point. 2. A mobile communication base station which communicates with a plurality of mobile station transmitters, wherein a frame arriving from the mobile station transmitter is a digital modulation wave, and a timing for sampling a detection output of the digital modulation wave. A phase locked loop circuit that generates a clock pulse that gives the following, and a decoding circuit that decodes the sampled detection output, the mobile communication base station receiver, at a first time near the end time of one of the frames A first memory for temporarily storing the phase information of the phase locked loop circuit, a second memory provided for each frame, and a second memory provided for the content stored in the first memory corresponding to one of the frames. Control means for providing the second memory with the contents stored in the second memory, a second time near the start of reception of the next frame corresponding to the memory; Setting means for setting an initial phase of the phase-locked loop circuit, and determining means for disabling the control means when determining that the decoding result of the decoding circuit indicates a frame loss. Mobile communication base station receiver. 3. The mobile communication base station receiving apparatus according to claim 1, further comprising: a judging means for invalidating said control means when judging that the decoding result of said decoding circuit indicates a frame loss.