JPH0463031A - Bit synchronizing system - Google Patents

Abstract

PURPOSE:To prevent an invalid burst from occurring by performing synchronized reception simultaneously with reception by a speech channel by utilizing bit synchronizing timing information recognized with a random access channel by sending to the speech channel via a host station. CONSTITUTION:A random access channel receiving part 10 checks the phase difference of a preamble pattern located at the forefront of a burst from a mobile station 2 during a period receiving the pattern with a bit synchronizing part 13 when a burst signal is received from the mobile station 2 suddenly, and performs the phase shift of the clock of a clock oscillation part 40, and sets it as a clock for the optimum sampling timing. Furthermore, phase difference information is informed to the host station 3 via a transfer circuit 15 with decode data. The host station 3 unifies the phase difference information and sends it to a speech channel receiving part 20. Thereby, the speech channel receiving part 20 can perform the reception with correct quantity of phase shift from the forefront of the first burst of a signal from the mobile station 2, which enables correct decoding to be performed.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a mobile telephone system employing a TDMA system, and particularly to a bit synchronization system at a base station [Prior Art] Conventionally, in this type of mobile telephone system, the base station When the receiving unit of the station receives a single burst transmission from a mobile station on the random access channel as a control channel, bit synchronization is performed using the fact that a preamble pattern for bit synchronization is prefixed to the beginning of the burst. is taking.

However, when bursts from the same mobile station are periodically received in succession, such as in a communication channel, it is wasteful to preamble a preamble pattern each time, so no preamble pattern is used. For this reason, the first few bursts before synchronization are used only to obtain bit synchronization from the data without decoding the contents, and these first few bursts are invalid bursts. .

Note that even though the mobile station transmits in synchronization with the downlink signal from the base station, the receiving section of the base station must obtain bit synchronization information from the received signal rather than from the transmission timing information. This is because the distance from the mobile station to the mobile station is not constant, and the propagation delay time due to this distance differs from mobile station to mobile station.

[Problems to be Solved by the Invention] In order for the base station to be able to receive the first few bursts in the communication channel without wasting them, the random access channel receiving section of the base station must The bit synchronization information obtained when the mobile station receives the calling signal may be stored, and when the communication channel is assigned to the mobile station, the stored bit synchronization information may be used.

However, there are the following problems in realizing this. First, call control is not originally a function of a transmitting/receiving circuit, but a function of a station higher than a base station, such as a switching equipment. For this reason, the base station stores the mobile station number,
Functions such as managing and identifying traffic channels assigned to the mobile station are entirely additional functions and add significantly to the complexity of the base station. Second, it is fine if the random access channel and the allocated speech channel are on different time slots of the same carrier, but if they are on different carriers, the random access channel receiving section and the speech channel receiving section are the same. Although it is within the base station, it is a separate channel, so a connection for bit synchronization information transfer between the receiving units is required.

SUMMARY OF THE INVENTION An object of the present invention is to provide a bit synchronization method that prevents the occurrence of invalid bursts in a communication channel receiving section.

[Means to solve the problem]

In the bit synchronization method of the present invention, the random access channel reception unit of the base station is equipped with a function to report the bit synchronization timing information used for decoding to the upper station along with the decoded data, and the upper station is notified of the bit synchronization timing information used for decoding. When the data is data requesting allocation of a communication channel, it specifies the communication channel number to the mobile station and sends a command signal to start communication and a bit synchronization timing information signal to the corresponding communication channel receiving section of the base station. The communication channel receiving section of the base station has a function of receiving a transmission burst from a mobile station using bit synchronization timing information sent from an upper station as an initial value.

For example, the random access channel reception section includes a bit synchronization section that shifts the phase of the clock generated from the clock oscillation section of the base station, and a transfer circuit that reports the clock from the bit synchronization section together with decoded data to the upper station. Equipped with
The communication channel receiving section includes a command receiving section that receives a reception start command signal and bit synchronization timing information from the upper station, and a bit synchronization section that pre-senses the bit synchronization timing information signal and outputs a clock for decoding. There is.

[Effect]

According to the present invention, since the bit synchronization timing information found on the random access channel is sent to the communication channel via the upper station and used, synchronized reception can be performed simultaneously with reception on the communication channel, and invalid burst prevent the occurrence of

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a bronc diagram showing an embodiment of the present invention, and 1
2 indicates a base station, 2 indicates a mobile station, and 3 indicates an upper station.

In the base station 1, descriptions of parts not related to the present invention, such as a transmitter, are omitted. This base station 1 has one carrier for a random access channel and two carriers for communication channels. Since it is a TDMA system, there are multiple time slots per carrier. For example, in the case of 3 multiplexing, each third time slot constitutes one communication path, that is, a channel, but it is easy to explain with the diagram. Therefore, the configuration is shown with one channel per carrier.

The random access channel receiving section 10 includes a demodulating section 1
1, and a sampling section 1 that samples demodulated data.
2, a bit synchronization section 13 that outputs a clock signal during this sampling, a decoding section 14 that decodes the sampled data, and a transfer circuit 15 that transfers the decoded signal to the upper station 3.

The communication channel receiving section 20 also includes a demodulating section 21, a sampling section 22, a bit synchronizing section 23, a decoding section 24, and a command receiving section 25 that receives commands from an upper station 25. .

The communication channel 30 is similarly configured.

Furthermore, the base station l is provided with a clock oscillation section 40.

In such a configuration, the random access channel receiving section 10 suddenly receives a burst signal from the mobile station 2. In this case, the signal is received at a roughly determined timing, but there is a timing shift within or outside of 1 bit due to the difference in propagation delay time. Therefore, the sampling timing for demodulating this signal matches the clock of the clock oscillation unit 40 in the base station 1 in frequency, but does not necessarily match in phase.

Therefore, the bit synchronizer 13 of the random access channel receiver 10 checks this phase difference while receiving the preamble pattern placed at the beginning of the burst from the mobile station 2, and checks the phase difference in the clock oscillator 40. The clock is phase-shifted to provide a clock with optimal sampling timing. Therefore, the portion after the preamble pattern that is originally intended to be transmitted as information can be sampled and decoded at the correct timing.

Furthermore, the random access channel receiving section 10
notifies the upper station 3 of the phase difference information of the bit synchronizer 13 through the transfer circuit 15 along with the decoded data.

The upper station 3 decodes the reported signal from the mobile station 2, and if the signal requires allocation of a communication channel, such as a calling signal, it selects one of the available communication channels and randomly Transmitter of access channel (not shown)
The mobile station 2 is notified of the channel number through the mobile station 2, and an operation start command is sent to the corresponding communication channel of the base station 1, for example, the command receiving unit 25 of the communication channel receiving unit 20.

At this time, the phase difference information in the bit synchronization circuit 13 when received by the random access channel receiving section 10 is also sent to the traffic channel receiving section 20 together. Therefore, the communication channel receiving section 20 starts the receiving operation when receiving an operation start command from the higher-level station 3, but at this time, since the bit synchronization section 23 can preset an initial value of the phase shift amount, the upper-level station After setting the bit synchronization information from the station 3 in the bit synchronization section 23, the receiving operation is started. Therefore, the communication channel receiving unit 20 can receive the signal from the mobile station 2 from the beginning of the first burst with the correct amount of phase shift, that is, with the optimal sampling timing, and correct decoding is possible.

The reason why the correct amount of phase shift in the random access channel is the same as the correct amount of phase shift in the communication channel is that the bit transmission timing within the mobile station is short because the signals are from the same mobile station. This is because it can be considered to be sufficiently stable in terms of time, and it can be assumed that the mobile station does not move so much that the propagation delay time changes significantly in a short period of time.

Here, the present invention can be similarly applied to the case of multilevel modulation of three or more levels.

〔Effect of the invention〕

As explained above, the present invention transmits information on the bit synchronization timing determined on the random access channel based on the transmission burst from the mobile station to the upper station, and the upper station receives this bit synchronization timing information. Since the data is sent to the communication channel, synchronized reception can be performed at the same time as reception on the receiving communication channel, which has the effect of avoiding missing the beginning of the transmission burst from the mobile station and preventing the occurrence of invalid bursts. .

[Brief explanation of the drawing]

FIG. 1 is a block configuration diagram employing the bit synchronization method of the present invention. 1...Base station, 2...Mobile station, 3...Upper station, 1
0...Random access channel receiving section, 20.
30... Call channel reception section, 40... Clock oscillation section, 11... Demodulation section, 12... Sampling section,
13...Bit synchronization unit, 14...Decoding unit, 15...
- Transfer circuit, 21... Demodulation section, 22... Sampling section, 23... Bit synchronization section, 24... Decoding section, 2
5... Command receiving section.

Claims (1)

[Claims] 1. A TDMA mobile telephone system having a random access channel and a communication channel, which
In a system that uses a signal format in which a preamble pattern for bit synchronization is prefixed to a mobile station's transmission burst on an access channel, but a preamble pattern for bit synchronization is not prefixed to a transmission burst on a communication channel, The random access channel receiving section of the station is equipped with a function to report the bit synchronization timing information used for decoding to the upper station along with the decoded data.
If the reported data is data requesting the allocation of a communication channel, the upper station sends a command signal that specifies the communication channel number to the mobile station and instructs the corresponding communication channel receiving section of the base station to start communication. It has a function to send a bit synchronization timing information signal, and the communication channel receiving section of the base station has a function to receive a transmission burst from a mobile station using the bit synchronization timing information sent from an upper station as an initial value. A bit synchronization method characterized by: 2. The random access channel reception section includes a bit synchronization section that shifts the phase of the clock generated from the clock oscillation section of the base station, and a transfer circuit that reports the clock from this bit synchronization section together with decoded data to the upper station. The communication channel receiving section includes a command receiving section that receives a reception start command signal and bit synchronization timing information from the upper station;
The bit synchronization system according to claim 1, further comprising a bit synchronization section that presets a bit synchronization timing information signal and outputs a clock for decoding.