JPH11275038A - Tdma mobile communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely attain time division multiple access(TDMA) communication by avoiding erroneous detection of a deviation in a frame timing and occurrence of a disabled timing correction. SOLUTION: Time alignment control is conducted at the setting UP of re- synchronization when making communication mobile terminals 1a, 1b under the control of a mobile communication control station 3 through a radio base station 2 by a TDMA system. The mobile terminals 1a, 1b and the mobile communication control station 3 through the radio base station 2 set up synchronization for setting a communication channel. When re-synchronization is set up as a state of out-of-synchronism is detected during communication through a set communication channel, the mobile communication control station 3 detects a time alignment control variable. The time alignment control variable having been stored after synchronization establishment is updated by replacing it with a time alignment control variable which is detected at the setup of re- synchronization.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a TDM system for performing digital communication by a time division multiple access (TDMA) method between a plurality of mobile stations and a mobile communication control station through a radio base station.
More particularly, the present invention relates to a TDMA mobile communication system such as a digital cellular mobile communication system or a digital cordless telephone that performs time alignment control when resynchronization is established during communication (call).

[0002]

2. Description of the Related Art Conventionally, in a digital cellular mobile telephone system or a digital cordless telephone in which a plurality of mobile terminals perform digital communication with a mobile communication control station through a radio base station by a time division multiple access (TDMA) system, a transmission delay in a radio section is known. It is necessary to prevent burst signal collision due to For this reason, in the synchronization establishing operation at the time of starting the communication channel, time alignment control for forcibly adjusting the transmission timing of the mobile terminal in units of symbols is performed.

[0003] In the synchronization establishing operation at the time of starting the communication channel, the mobile communication control station measures the delay amount of the uplink synchronization burst signal from the standard timing through the radio base station, and uses the phase difference obtained by this measurement for time alignment control. It is notified to the mobile terminal by the amount and the downlink burst signal, and is held by the mobile communication control station. The mobile terminal corrects the transmission timing based on the notified time alignment control amount.

[0004] Further, the mobile communication control station monitors the timing of an uplink signal from the radio base station during a call after the end of the synchronization establishing operation. When a phase difference is detected by this timing monitoring, the timing is corrected. This timing adjustment during a call is performed on a downlink signal from the wireless base station to the mobile terminal. In this case, the timing of the uplink signal obtained from the time alignment control amount held by the mobile communication control station and the standard timing is used as the reference timing, and the transmission timing is adjusted using the phase difference obtained by the frame monitoring process.

FIG. 4 is a diagram for explaining time alignment control. Such time alignment control is executed by, for example, a mobile communication control station accommodating a plurality of radio base stations in a digital cellular mobile telephone system performing digital communication. The mobile communication control station includes a control device 4 and a storage device 5 for performing time alignment control.

The control device 4 controls the frame timing monitoring (a) during communication, and as described above, the storage device 5
When a phase difference from the reference timing (e) held in the above occurs, the frame timing is corrected by the communication control (b). When an out-of-synchronization state is detected by the synchronization state monitoring (c) in the control device 4, synchronization establishment is started by the communication control (b), and transmission and reception of a synchronization burst are performed.
In this re-synchronization establishment, the time alignment (TA) control amount (f) in the storage device 5 is not held.

As described above, the mobile communication control station stores and holds the time alignment control amount at the time of establishing synchronization. However, when re-synchronization is subsequently performed, the stored and maintained time alignment control amount becomes The update for replacing with the time alignment control amount at the time of resynchronization establishment is not performed. Therefore, when the time alignment control amount at the time of the first synchronization establishment and the time alignment control amount at the time of the resynchronization establishment are not the same value, the reference timing (actual uplink signal timing) cannot be obtained after the resynchronization establishment. Therefore,
This means that frame timing monitoring and timing correction during a call cannot be performed accurately.

[0008] Japanese Patent Application Laid-Open No. 8-190 discloses this kind of prior art.
No. 38, "Inter-station Synchronization Method Between Radio Base Stations" and JP-A-8-19038, "Inter-station Synchronization Method" are examples. In the former conventional example, even when the distance between each radio base station and the mobile terminal in each service area is not equal, frame synchronization between the radio base stations is accurately established. In the latter conventional example, even when the radius of the service area is large and time alignment control is required, frame synchronization in a wireless section between the base station and the coordinating station can be established.

[0009]

As described above, in the above-described conventional TDMA mobile communication system, the time alignment control amount at the time of establishing resynchronization in the radio base station cannot be obtained, so that communication during the resynchronization is established. , It is easy to generate frame timing misalignment in the frame monitoring process, and the timing correction cannot be performed easily. Therefore, the frame timing monitoring and the timing correction during the call cannot be performed accurately and reliably. There were drawbacks.

The present invention has been made to solve the above-mentioned problems in the prior art. A mobile communication control station or the like accommodating a plurality of radio base stations of a digital cellular mobile telephone system of the TDMA system has been proposed. It is possible to obtain the time alignment control amount at the time of synchronization establishment, accurately grasp the reference timing, and erroneously detect the misalignment of the frame timing and prevent occurrence of the inability to execute the timing correction. An object of the present invention is to provide a TDMA mobile communication system capable of connecting a communication line in TDMA communication.

[0011]

In order to achieve the above object, a TDMA mobile communication system according to the present invention provides a resynchronization when a plurality of mobile stations and a radio control base station communicate with each other by a time division multiple access system. Performs time alignment control at the time of establishment.The mobile station and the radio control base station establish synchronization and set a communication channel.The radio control base station detects out-of-synchronism during communication through the set communication channel. In this case, re-synchronization is established, the time alignment control amount at the time of the re-synchronization establishment is detected, and the detected time alignment control amount at the time of the re-synchronization establishment is compared with the time alignment control amount held from the time of the synchronization establishment. It is configured to replace and update.

[0012] In the TDMA mobile communication system, the mobile station is a mobile terminal that performs a call or data communication, and
A digital cellular mobile telephone system in which the radio control base station is a plurality of radio base stations and a mobile communication control station. The mobile station is a slave unit for making a call, and the radio control base station is connected to a telephone network. It is a digital cordless telephone used as a base unit.

[0013] Further, as the radio base station, a transmission / reception unit for performing radio transmission / reception with a mobile terminal via a radio channel, and a modulation / demodulation for demodulating a reception signal from the transmission / reception unit or modulating transmission data and transmitting the data to the transmission / reception unit. And a multiplexing device for multiplexing communication data from the mobile communication control station and transmitting the multiplexed data to the modulation / demodulation device, and for converting multiplexed data from the modulation / demodulation device into non-multiplexed data and transmitting it to the mobile communication control station. There is a configuration.

Further, as the mobile communication control station, a multiplexer for extracting communication data from a plurality of radio base stations or transmitting communication data from a communication network in a time-division manner to a plurality of radio base stations. And a voice processing device that encodes communication data from the communication network and sends it to a plurality of radio base stations, and performs a codec process for decoding the encoded communication data from the multiplexing device. The mobile communication exchange that performs the processing and obtains the amount of time alignment control at the time of resynchronization establishment, grasps the reference timing, and performs control to prevent erroneous detection of frame timing deviation and occurrence of inability to execute timing correction. And a storage device for storing a reference timing and a time alignment control amount.

Further, the control device performs frame timing monitoring control during communication, and when a phase difference from a reference timing held in a storage device occurs, corrects the frame timing by communication control and performs synchronization. When the occurrence of the out-of-synchronization state is detected by the state monitoring, the time alignment control amount update processing is notified that the operation has shifted to the resynchronization establishment operation. Further, the storage device, by notification to the time alignment control amount update processing from the control device, replaces the held time alignment control amount with a time alignment control amount corresponding to the delay of the downlink communication channel and updates it, In addition, the standard timing is sent to the frame timing monitoring control of the control device.

In the TDMA mobile communication system of the present invention having such a configuration, a digital cellular mobile telephone system, a mobile terminal of a digital cordless telephone and a mobile communication control station through a radio base station are synchronized by the TDMA system. Set the communication channel. During communication via the set communication channel, the time alignment control amount obtained at the time of re-establishment of the synchronization loss is replaced with the time alignment control amount held from the time of the synchronization establishment at which the communication channel is set. Update.

As a result, erroneous detection of a frame timing shift during control by a mobile communication control station or the like accommodating a plurality of radio base stations of a TDMA digital cellular mobile telephone system, and occurrence of an inability to execute timing correction. Is prevented, and a reliable communication line connection in the TDMA communication becomes possible.

[0018]

Next, an embodiment of a TDMA mobile communication system according to the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a TDMA mobile communication system according to an embodiment of the present invention. This TDMA
The mobile communication system is, for example, a digital cellular mobile telephone system, which includes mobile terminals (MS) 1a and 1b such as a mobile radio telephone and a data terminal that perform communication by moving in adjacent service areas (cells), and own service areas. A radio base station (BS) 2 for performing communication by connecting radio terminals of mobile terminals 1a and 1b which have moved
For example, is accommodated through a digital transmission line having a transmission rate of 1.5 / 2.0 Mb / s, performs exchange control in mobile communication, and performs line connection with a wired communication network (PSTN, ISDN) or the like (not shown). And a station (MCC) 3.

The radio base station 2 includes a transmitting / receiving unit 21 for transmitting and receiving to and from the mobile terminals 1a and 1b via a radio channel via an antenna, and a 1 / π shift Q from the transmitting / receiving unit 21.
A modulation / demodulation device 22 for demodulating a received signal such as a PSK modulated wave, or generating transmission data as a 1 / π-shifted QPSK modulated wave and sending it to a transmitting / receiving section 21;
And a multiplexing device 23 for multiplexing communication data from the communication device and transmitting the multiplexed data to the modulation and demodulation device 22 and demultiplexing (decomposing) the multiplexed data from the modulation and demodulation device 22 and transmitting the multiplexed data to the mobile communication control station 3. I have.

The mobile communication control station 3 includes a number of radio base stations 2
A multiplexing device 31 that extracts communication data from a wireless communication network, or time-divides communication data from a wired communication network (PSTN, ISDN) and sends it to each of a large number of wireless base stations 2; And transmits the communication data from the multiplexing device 31 to the multiplexing device 31.
And a voice processing device 32 for performing a codec (CODEC) process for decoding communication data (encoded data).

Further, the mobile communication control station 3 obtains a time alignment control amount at the time of re-synchronization establishment such as during communication (communication) with a mobile communication exchange 33 for performing exchange processing with a wired communication network or the like. The control device 34 includes a control device 34 for grasping the timing and performing control for preventing erroneous detection of a frame timing shift and occurrence of inability to execute timing correction, and a storage device 35 for storing a reference timing and a time alignment control amount. doing.

The mobile terminals 1a and 1b have a general configuration. For example, an antenna transmission / reception duplexer, a transmission / reception unit,
1 / π shift QPSK modulator, high-speed switching synthesizer (DLPS), demodulator, control unit, TDMA circuit, codec (CODEC) circuit, microphone and speaker,
What is necessary is just to make it the structure provided with the display part, the operation part, etc.

Next, the operation of this embodiment will be described. In this TDMA mobile communication system, for example, a digital cellular mobile telephone system, mobile terminals 1a, 1b
Moves in the service area (cell) of the radio base station 2,
In addition, communication is performed by line connection. A large number of wireless base stations 2 have a mobile communication control station 3 having a transmission rate of 1.5 /
It controls line connection through a 2.0 Mb / s digital transmission path and uses a wired communication network (PSTN, IS
DN) and the like.

In the radio base station 2, the transmission / reception unit 21 performs transmission / reception with the mobile terminals 1a and 1b via a radio channel. In addition, the modem 22 receives the 1 / π-shifted QPS from the transmitting / receiving unit 21.
The received signal of the K modulation wave is demodulated or the transmission data is reduced by 1 /
A π-shift QPSK modulated wave signal is generated and transmitted to the transmission / reception unit 21. Further, the multiplexing device 23 multiplexes the communication data from the mobile communication control station 3 and sends the multiplexed data to the modulation / demodulation device 22, and demultiplexes (decomposes) the multiplexed data from the modulation / demodulation device 22 so as to multiplex the communication data. Send to

In the mobile communication control station 3, the multiplexing device 31 extracts each multiplexed data from a number of radio base stations 2 by non-multiplexing conversion, or time-divisions communication data from a wired communication network or the like. Then, the signal is transmitted to each of the large number of wireless base stations 2. Further, a codec (CODEC) that encodes communication data from a wired communication network or the like and sends it to the multiplexer 31 and decodes communication data (encoded data) of the multiplexer 31 by the audio processing device 32. Perform processing.

In the mobile communication control station 3, the mobile communication exchange 33 performs an exchange process with a wired communication network or the like. Furthermore,
The control device 34 stores the reference timing and the time alignment control amount in the storage device 35, obtains the time alignment control amount at the time of re-establishment of synchronization, grasps the reference timing, and erroneously detects the deviation of the frame timing, and Control is performed to prevent the correction from being disabled.

A control operation for obtaining a time alignment control amount at the time of establishing resynchronization, grasping a reference timing, and erroneously detecting a frame timing shift and preventing occurrence of inability to execute timing correction will be described. . FIG. 2 is a diagram for explaining a processing state in the control device 34 and the storage device 35, and FIG. 3 is a diagram for explaining a synchronization established state.

In FIG. 1, TDMA communication is performed between the mobile terminals 1a and 1b and the radio base station 2 and the mobile communication control station 3. That is, the radio base station 2 and the mobile communication control station 3
(Hereinafter, appropriately abbreviated as base station (2, 3)), time-divides carriers of frequency numbers 1, 2, 3,... N in the communication frequency band into slot numbers 1, 2, 3,. This one communication channel is allocated to the mobile terminals 1a and 1b, and the communication is performed.

At the start of communication, the base stations (2, 3) and the mobile terminals 1a, 1b transmit and receive a synchronous burst signal, and communicate with a communication channel (slot numbers 1, 2, 3,. The control operation for establishing synchronization for setting one of n / communication channels CH0, CH1, CH2, and CH3 in FIG. 3 is performed. The base stations (2, 3) transmit downlink synchronization burst signals to the mobile terminals 1a, 1b at standard timing. At the same time, the base stations (2, 3) measure the timing delay amount of the uplink synchronization burst signal from the mobile terminals 1a, 1b.

The phase difference as a result of this measurement is stored in the downlink synchronization burst signal and transmitted from the base station (2, 3) to the mobile terminal 1.
a, 1b. That is, the time alignment control amount TA1 corresponding to the delay between the uplink communication channels CH0 and CH1 for the downlink communication channels CH0, CH1, CH2, and CH3 shown in FIG. 3A is stored in the downlink synchronization burst signal and transmitted. .

The base station (2, 3) and the mobile terminals 1a, 1
After the synchronization with the base station (2, 3) is established, the base station (2, 3) notifies the base station (2, 3) of the uplink communication burst signal from the mobile terminals 1a, 1b to the base station (2, 3) as a reference timing.
The mobile terminals 1a and 1b store the time alignment control amount TA1 in (a). As shown in FIG. 3B, the stored time alignment control amount TA1 is used together with the standard timing of a state where no delay occurs in the uplink communication channels CH0 to H2 for achieving synchronization with the downlink communication channels CH0 to CH3. Is used to obtain the timing of the uplink communication burst.

That is, the control device 34 controls the frame timing monitoring (a) shown in FIG. 2 during communication, and when a phase difference from the reference timing (e) held in the storage device 35 occurs, the communication is performed. The frame timing is corrected by the control (b). When the occurrence of an out-of-synchronization state is detected by the synchronization state monitoring (c) shown in FIG. 2 in the control device 34, the synchronization state monitoring (c) of the control device 34 indicates that the transition to the resynchronization establishing operation has been completed. Alignment (T
A) Notify the control amount update (d) processing.

The time alignment (TA) control amount (f) of the storage device 35 in FIG. 2 is updated by the processing of the time alignment (TA) control amount update (d). That is, as shown in FIG. 3C, the time alignment (TA) control amount TA1 held from the time of synchronization establishment is the time alignment corresponding to the delay between the uplink communication channels CH0 and CH1 with respect to the downlink communication channels CH0 to CH3. It is updated by replacing with the control amount TA2. This storage device 35
From the latest time alignment control amount TA2 and the standard timing, the timing of the uplink signal frame transmitted by the mobile terminals 1a and 1b, that is, the reference timing can be identified.

In this way, the time alignment control amount at the time of re-synchronization establishment can be obtained, the reference timing can be grasped, and erroneous detection of a frame timing shift and occurrence of inability to execute timing correction can be prevented. Become.

In this embodiment, a digital cellular mobile station that performs time alignment control when resynchronization is established when performing communication under the control of the mobile communication control station 3 through the radio base station 2 with the mobile terminals 1a and 1b by the TDMA method. Although explained using the example of the telephone system, other communication systems,
For example, the present invention can be applied to a TDMA digital cordless telephone including a plurality of slave units and a master station.
In this case, the radio base station 2 and the mobile communication control station 3
Corresponds to the master station.

[0036]

As is apparent from the above description, according to the TDMA mobile communication system of the present invention, the mobile terminal and the mobile communication control station through the radio base station establish synchronization with each other and set a communication channel by the TDMA system. Then, during communication through the set communication channel, the time alignment control amount obtained at the time of re-establishment of the synchronization loss is replaced with the time alignment control amount retained from the time of the synchronization establishment and updated. I have.

As a result, in a mobile communication control station or the like accommodating a plurality of radio base stations in a digital cellular mobile telephone system of the TDMA system, erroneous detection of a frame timing shift during control and execution of timing correction are performed. The impossibility of occurrence is prevented, and a reliable communication line connection in TDMA communication can be performed.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a TDMA mobile communication system according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a processing state in a control device and a storage device in the embodiment.

FIG. 3 is a diagram illustrating a synchronization establishment state in the embodiment.

FIG. 4 is a diagram for explaining time alignment control in a conventional example.

[Explanation of symbols]

 1a, 1b Mobile terminal 2 Radio base station 3 Mobile communication control station 21 Transmitter / receiver 22 Modulator / demodulator 23, 31 Multiplexer 32 Audio processor 33 Mobile communication switch 34 Control device 35 Storage device

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI H04Q 7/24 7/26 7/30

Claims (7)

[Claims] 1. A TDMA mobile communication system for performing time alignment control when resynchronization is established when a plurality of mobile stations and a radio control base station communicate with each other by a time division multiple access method, wherein the mobile station and the radio control base station A station establishes synchronization and sets a communication channel, and when the radio control base station detects out-of-synchronism during communication through the set communication channel, re-establishes synchronization. A TDMA mobile communication system characterized by detecting an alignment control amount and replacing the detected time alignment control amount at the time of re-establishment of synchronization with a time alignment control amount held from the time of synchronization establishment. 2. The TDMA mobile communication system, wherein the mobile station is a mobile terminal that performs a call or data communication,
2. The TDMA mobile communication system according to claim 1, wherein the TDMA mobile communication system is a digital cellular mobile telephone system in which the radio control base station includes a plurality of radio base stations and a mobile communication control station. 3. The TDMA mobile communication system according to claim 1, wherein the mobile station is a slave unit for making a call, and is a digital cordless telephone having a radio control base station as a master unit connected to a telephone network. 2. The TDMA mobile communication system according to claim 1. 4. A transmission / reception unit for performing radio transmission / reception with a mobile terminal via a radio link as the radio base station, and demodulating a reception signal from the transmission / reception unit or modulating transmission data and transmitting the modulated data to the transmission / reception unit. Multiplexing communication data from a mobile communication control station and transmitting the multiplexed data to the modem, and multiplexing data from the modulation and demodulation device into non-multiplexed data and transmitting the multiplexed data to the mobile communication control station. The TDMA mobile communication system according to claim 2, comprising: a device. 5. The mobile communication control station according to claim 1, further comprising: fetching respective communication data from a plurality of radio base stations, or multiplexing the communication data from a communication network in a time-division manner and transmitting to said plurality of radio base stations. An audio processing device that encodes communication data from the communication network and sends the encoded data to the plurality of wireless base stations, and performs a codec process for decoding encoded communication data from the multiplexing device; A mobile communication exchange that performs exchange processing with the network, and obtains the time alignment control amount when resynchronization is established, grasps the reference timing, and detects erroneous detection of frame timing deviation and occurrence of inability to execute timing correction. 3. The TD according to claim 2, further comprising: a control device that performs control for preventing the signal; and a storage device that stores a reference timing and a time alignment control amount. MA mobile communication system. 6. The control device performs frame timing monitoring control during communication, and when a phase difference from a reference timing held in a storage device occurs, corrects the frame timing by communication control and performs synchronization. 6. The TDMA mobile communication system according to claim 5, wherein when the occurrence of an out-of-synchronization state is detected by the state monitoring, the time alignment control amount update processing is notified of a shift to a resynchronization establishing operation. 7. The storage device replaces the stored time alignment control amount with a time alignment control amount corresponding to a delay of a downlink communication channel by notifying a time alignment control amount update process from a control device. 6. The TDMA mobile communication system according to claim 5, wherein the standard timing is updated and sent to the frame timing monitoring control of the control device.