JPH08251653A - Digital mobile communication system - Google Patents

Abstract

PURPOSE: To improve frequency application efficiency by determining a communication slot after synchronizing with a slave equipment or a master equipment already in communicating at the time of starting inter-slave direct communication and eliminating a time not to be used for communication to execute time division multiplex. CONSTITUTION: A TDMA-TDD digital mobile communication is constituted of arranging a digital mobile communication terminal 2 as a slave equipment. When the terminal 2 tries to newly start inter-slave direct communication, a control part 28 in the terminal 2 enters a signal sent by a control slot or a communication slot from a slave equipment or a master equipment already in communicating to a TDMA part 24 through an antenna 21, an RF part 22 and a MODEM part 23 and detects a unique word in the signal by a UW detection part 242. Then the control part 28 controls a synchronizm generating part 241 based upon the detection result, and after synchronizing the part 24 with the slave equipment or the master equipment already in communication, determines the communication slot and starts newly inter-slave direction communication.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital mobile communication system comprising a plurality of base units and a plurality of handset units that wirelessly communicate with the base unit. The present invention relates to an improvement in communication slot setting control for preventing a decrease in frequency utilization efficiency when directly communicating without communication.

[0002]

2. Description of the Related Art In a digital mobile communication system consisting of a plurality of base units and a plurality of handset units that wirelessly communicate with the base unit, TD is used as a communication system in order to effectively use frequencies
There is known one that adopts the MA-TDD method.

FIG. 8 is a schematic block diagram of a digital mobile communication system of this type, and in particular, the above-mentioned base unit (BS) 1
And the slaves 2a to 2d (PS1 to 4) between the TDMA-T
It shows a state in which wireless communication is performed by the DD method.

Further, FIG. 9 shows an example of the configuration of a time slot relating to the above-mentioned master / slave communication in the system shown in FIG. That is, in this master / slave communication, the master BS, as shown in FIG. 4A, has 4 transmission slots (T1 to T4) and 4 reception slots (R1 to R4).
All of R4) are used to realize communication by 4 multiplexing.

On the other hand, regarding the slaves PS1 to PS4, first, PS1 receives the data using the transmission slot T1 of the master BS during communication with the master BS, as shown in FIG. , The transmission is performed using the reception slot R1 of the base unit BS.

Similarly, the slave units PS2, PS3, and PS4 communicate with the base unit BS, respectively, as shown in FIG.
As shown in (d) and (e), while using the transmission slots T2, T3, T4 of the base unit BS to receive, the base unit B
Transmission is performed using the reception slots R2, R3, and R4 of S.

On the other hand, FIG. 10 shows two sets of slave units PS1 and PS2 in the digital mobile communication system.
The figure shows a situation in which PS3 and PS4 each perform direct communication between slave units.

FIG. 11 shows a time slot structure in the above direct communication between the handset units when the set PS1 and PS2 enters the direct communication between the handset units earlier than the set PS3 and PS4.

That is, in this case, first, PS1 and PS2
In communication between the two, as shown in (a) and (b) of the figure, PS1 transmits using the transmission slot T2 and receives using the reception slot R2, and PS2
Then, it receives at the timing of the transmission slot T2 of PS1,
Transmission is performed at the timing of the reception slot R2 of PS1.

In the subsequent communication between PS3 and PS4,
As shown in (c) and (d) of the figure, PS3 transmits using the transmission slot T3, and at the same time, the reception slot R3.
The PS4 receives at the timing of the transmission slot T3 of PS3, and the PS4 receives the reception slot R3 of PS3.
Is transmitted at the timing of.

In the direct communication between the handset units under such an operating condition, in the conventional digital mobile communication system, PS1
PS3 that starts direct communication between handset units after pairing with PS2
And PS4 detect the reception level of the communication slot to be used, and based on this detected reception level, confirm that the communication slot is not used in the direct communication between PS1 and PS2 that has already started. Therefore, the communication slot is set and the direct communication between the child devices is started.

However, in such a conventional communication slot setting method, accurate transmission / reception timing is often unknown due to variations in the reception level due to fading or the like, and as shown in FIG. 11 (d), it is shorter than the communication slot. In some cases, the time Δt that cannot be used for communication is generated. As a result, conventionally, it becomes impossible to perform 4-multiplex communication, resulting in a decrease in frequency utilization efficiency.

[0013]

As described above, in the above-mentioned conventional digital mobile communication system, when the direct communication between the handset units is started, the reception level of the intended communication slot is measured and based on the reception level. Since it was determined whether or not the communication slot could be used, accurate transmission / reception timing was not known due to variations in the reception level due to fading, etc., and was used for communication such as Δt as shown in FIG. 11 (d). There is a problem that the 4-multiplexing becomes unexecutable due to the unavailability time, resulting in a decrease in frequency utilization efficiency. The present invention eliminates the above-mentioned problems, and when starting direct communication between handset units, the above communication slot can be set without being affected by fading, etc., and the time during which communication cannot be used is eliminated, improving frequency utilization efficiency. It is an object of the present invention to provide a digital mobile communication system capable of doing the above.

[0014]

SUMMARY OF THE INVENTION The present invention is a digital mobile communication system comprising a plurality of base units and a plurality of handset units communicating with the base unit, wherein the handset unit is another handset unit and a handset unit. When starting direct inter-communication, the pattern and signal level of the signal transmitted by the slave unit or master unit already in communication is detected to establish synchronization with the slave unit or master unit in communication, and the slave unit It is characterized in that a communication slot used for direct communication is determined.

[0015]

According to the present invention, when another slave unit newly starts direct communication between slave units from a state where communication is already being performed in the same communication area, the slave unit which is about to start communication is already in communication. After detecting the pattern and signal level of the signal transmitted by the slave unit or the master unit that is performing communication and establishing synchronization with the slave unit or the master unit already in communication, it is used for the new direct communication between the slave units. The communication slot is determined.

According to the present invention, the communication slot to be used for the direct communication between the slave units can be determined by establishing the synchronization with the slave unit or the master unit which is already in communication, without causing a time during which the communication cannot be used. , It becomes possible to perform multiplexing at the same frequency.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 is a functional block diagram showing an embodiment of a digital mobile communication terminal according to the present invention, which includes an antenna 21, an RF unit 22, a modem unit 23, and a TDMA unit 2.
4, a codec unit 25, a handset 26, an operation unit 27, and a control unit 28. Among them, the TDMA unit 24 includes a synchronization generation unit 241, a UW (unique word) detection unit 242, a transmission circuit unit 243, and a reception circuit unit 244.

The digital mobile communication terminal 2 is used as a slave unit (PS1 to PS4) of the digital mobile communication system as shown in FIG.
Various functional operations are implemented by controlling the above-mentioned respective circuit units in. The outline of the direct communication between the handset units, which is one of the functional operations, will be described below. In the digital mobile communication system of the present invention in which the digital mobile communication terminal 2 shown in FIG. 1 is arranged as slaves (PS1 to PS4), in order to start direct communication between these slaves, the operation mode is set to It is necessary to set the machine-to-machine direct communication mode in advance.

The setting of the direct communication mode between the slave units can be performed by operating a predetermined key from the operation unit 27 of each slave unit. When the inter-slave unit direct communication mode is set, each slave unit is maintained in a standby state for receiving only the signal assigned to the inter-slave unit direct communication. FIG. 2 is a table showing a relationship between channel frequencies and carrier numbers used in the digital mobile communication system according to the present invention. In the present embodiment, the carrier in the table is used as a signal assigned to the direct communication between the slave units. Ten waves of numbers 1 to 10 are assumed.

After the standby state is set, the direct communication between the handset units is started according to the control sequence as shown in FIG. That is, in the standby state, in the originating side handset (referred to as PS1 for convenience), after detecting an empty channel,
A burst signal is sent for 10 seconds at intervals of once every 5 ms as a calling signal to the receiving side handset (also called PS2).

At this time, the receiving side PS2 performs the intermittent reception of the above 10 waves by changing the frequency assigned to the direct communication between the slaves 10 times and performing the reception asynchronously in order. In response to a call from the caller PS1, the callee PS2 receives a call addressed to its own PS, and thereafter, in order to establish synchronization with the caller PS1, a control signal format is used with the caller PS1. Send and receive signals with no data.

In the operation during this period, the receiving side PS2, which receives the synchronization signal from the transmitting side PS1, generates a ringer sound and calls the operator. After that, when the operator performs an off-hook operation, the receiving side PS2 recognizes this operation as a response operation and transmits a response signal to the originating side PS1.

On the other hand, on the sending side PS1 which has received the response signal from the called side PS2, as a pre-process for utilizing the call channel, a signal "Tch idle" having no data in a signal format for a call is transmitted, and further, Receiving side PS2 that has received the signal transmits a similar "Tch idle" signal to originating side PS1. After sending and receiving this "Tch idle" signal, the originating side PS1 and the receiving side PS2
It becomes possible to communicate directly with. In the above-described direct communication between slave units, the same frequency and slot are used for the control channel (Cch) and the communication channel (Tch). That is, in the direct communication between the handset units, the sending side P
After the call from S1 to the called side PS2 and the transmission / reception of the synchronization signal between the calling side PS1 and the called side PS2 thereafter are performed using Cch, the frequency and the communication slot are not changed, and the Cch is simply changed to Tch. After changing
The "Tch idle" signal is communicated using the Tch.

By the way, in the conventional device of this kind, when the communication slot is decided at the time of starting the above-mentioned direct communication between the handset units, it is confirmed that this communication slot is not used in the direct communication between the handset units. This is realized by making a judgment based on the detection result of the reception level of the communication slot.

On the other hand, in the present invention, the slave unit which is going to start the direct communication between the slave units monitors the pattern and the signal level of the signal transmitted by the slave unit or the master unit already in communication,
It is characterized in that the communication slot is determined after establishing synchronization with the slave unit or the master unit that is already communicating based on the monitoring result.

Here, when a certain slave unit tries to start the direct communication between the slave units, as the mode of the communication already executed, the normal communication between the master unit and the slave unit or the direct communication between the slave units is performed. Conceivable.

FIG. 4 shows an example of the configuration of signals transmitted and received between the master unit and the slave units or between the slave units in the above communication. FIG. 4A shows the signal format of the control physical slot. , (B) shows the signal format of the call physical slot.

In the signal structure of each slot shown in FIGS. 7A and 7B, UW represents a unique word,
When the digital mobile communication terminal 2 according to the present invention starts direct communication between handset units, this unique word is assumed as a signal to be monitored for synchronization with the handset unit or base unit already in communication. .

That is, the terminal 2 having the configuration shown in FIG.
4A or ((a) in which the slave unit or the master unit already in communication sends out in the control slot or the communication slot when the terminal 2 tries to start the direct communication between the slave units. The signal of the format as shown in b) is received through the antenna 21 and the RF unit 22, further demodulated by the modem unit 23 and transferred to the TDMA unit 24, and then the receiving circuit unit 244 performs the receiving process.

At this time, the UW detector 242 detects the UW signal pattern and the signal level included in the demodulated signal. Next, the synchronization generation unit 241 refers to the detection result of the UW detection unit 242, and controls the establishment of synchronization with the slave unit or the master unit that is already in communication.

Here, when the synchronization can be established, in the terminal 2, the control unit 28 monitors the multiplexing or disassembling process of the TDMA unit 24 and has already established the synchronization and is in communication with the slave unit or the parent unit. A communication slot that does not interfere with the device is determined, and direct communication between the child devices is started using this communication slot.

On the other hand, when the synchronization with the slave unit or the master unit already in communication cannot be established, the control unit 28 of the terminal 2
The communication slot is determined at the timing owned by the terminal 2 itself, and direct communication between the child devices is started.

As described above, in the present invention, the slave unit which is going to start the direct communication between the slave units has two operation modes of the master mode and the slave mode, and the slave unit or the master unit already communicating at the same frequency is If it does not exist, the master mode is set, the communication slot is determined at the timing of the slave itself, and direct communication is performed between the slaves.On the other hand, if there is a slave or master that is already communicating, the slave mode Then, after detecting the signal pattern and signal level of the unique word transmitted by the slave unit in master mode or the slave unit or master unit of its communication partner, after establishing synchronization, the communication slot to be used is determined and the slave unit Direct communication is started.

Here, if the system configuration has only the slave mode, the unique word cannot be detected and the communication slot can be determined from the state in which communication is not already performed at the time of starting the direct communication between the handset units. However, by using the master mode together as described above, it becomes possible to autonomously shift to the direct communication between the handset units from the state in which there is no handset unit or base unit already in communication.

The details of the direct communication operation between the handset units of the digital mobile communication system according to the present invention will be described below.
The operation of S and the operation of the receiving side PS will be separately described with reference to the flowcharts shown in FIGS. Here, FIG. 5 shows the operation of the calling side PS, and FIG. 6 shows the operation of the called side PS.

First, in the calling side PS which is going to newly start direct communication between the handset units, in the standby state after the setting to the direct mode between handset units has been completed through the above-mentioned procedure, the call button is turned "ON". Is monitored (S501).

Here, when the call button is turned "ON" (S501Y), one channel is selected and set from arbitrary free channels (S502). Next, it is monitored whether or not there is another child device or parent device that is already using the set channel (S503).

If there is another child device or a parent device using the set channel (S503Y),
If the slave mode (S504) is entered and there is no other slave unit or master unit using the setting channel (S503N), the master mode (S520) is entered.

When the mode is changed to the slave mode, the originating PS then carries out a control operation for synchronizing the set channel with the operation timing of the slave unit or master unit already in use (S505). Then, after the synchronization is established with the slave or master that is already communicating, the originating PS determines whether there is a communication slot that can be used (S506), and if there is no available slot (S506N). ,
Returning to step S502, the operation of setting another channel is performed.

On the other hand, if there is a communication slot that can be used (S506Y), the originating PS sets the communication slot as a use slot (S507).
The communication procedure with the called PS (see the control sequence in FIG. 3) is executed.

First, the calling side PS sends a "call" (S508), and then the called side P responds to the "call".
When the "sync" sent from S is received (S50
9) Further, "synchronization" is transmitted to the called PS (S510).

After that, when the calling side PS receives a "response" from the called side PS in response to the "synchronization" sent in S510 (S511), it sends a "Tch idle" (S51).
2) Further, after receiving "Tch idle" from the PS on the receiving side (S513), the state shifts to the state of communicating with the PS on the receiving side (S514).

On the other hand, in S503, when there is no slave unit or master unit that is already using the previously set channel and the master mode is entered (S520), the originating PS
Sets the communication slot to be used at its own timing (S521). The operation after setting this communication slot is
Similar to the operation in the slave mode (S508 to S51
3), and direct communication between the handset units with the called PS (S51
Proceed to 4).

In response to the operation of the calling side PS, the receiving side P
At S, the control operation is performed according to the flowchart shown in FIG. First, in the receiving side PS, in the standby state, intermittent reception of all channels of the inter-slave communication is performed (S
601). Next, the terminating PS determines whether or not there is a call signal addressed to its own PS for the reception channel (S602). If there is no calling signal addressed to the own PS (S602N), the intermittent reception and the call determination for the own PS are continued.

On the other hand, if it is recognized that there is a calling signal addressed to the own PS for the above-mentioned intermittently received channel (S602Y), then the called side PS synchronizes with the timing of the calling side PS at this time. Control is performed (call reception) (S603).

After that, the called PS receives the "call" shown in FIG.
Preparations are made to proceed to direct communication between handset units with the originating PS via sequence control after reception. That is, after the callee PS has established synchronization with the caller PS by the process of S603, it transmits "synchronization" to the caller PS (S604). After that, when the "sync" sent from the calling PS is received in response to the "sync" from the called PS (S605), the operator is called by a ringer sound or the like, and after confirming the response operation to this calling, the call is sent. A "response" is transmitted to the side PS (S606). Further, the called PS receives "Tch idle" from the calling PS (S607), and then sends "Tc idle" to the calling PS.
After sending "h idle" (S608), a transition is made to a state during direct communication between the handset units with the calling PS (S60).
9).

As described above, according to the present invention, the slave unit which newly starts the direct communication between the slave units monitors the signal pattern and the signal level transmitted by the slave unit or the master unit already in communication at that time. Basically, the communication slot is determined after the synchronization is established with the child device or the parent device already in communication.

FIG. 7 shows the arrangement of the slave units PS1 to PS4 as shown in FIG.
In the digital mobile communication system as shown in FIG. 10 using the terminal 2 having the configuration shown in FIG.
3 is a time chart showing an example of a setting communication slot when PS3 and PS4 newly start direct communication between handset units from a state where direct communication between handset units is already performed.

According to the above operating conditions, before the PS3 and PS4 start the direct communication between the handset units, the communication between the PS1 and PS2 uses the control physical slot and the communication physical slot as shown in FIG. Is being performed, and at this time, FIG.
According to the timing shown in (a) and (b), PS1
In the PS2, transmission using the transmission slot T2 and reception using the reception slot R2 are performed.
Reception at the timing of the transmission slot T2 of S1 and PS1
Is being transmitted at the timing of the receiving slot R2.

From this state, for example, when a new direct communication between the handset units is started with the PS4 by a request from the PS3, first, the originating side PS3 first communicates with the PS1 and PS which are already in communication.
2 monitors the pattern and the reception level of the signal (UW in the control physical slot or the communication physical slot) sent by 2;
Based on the monitoring result, these slaves PS1 and P that are already in communication
After the synchronization with S2 is established, the communication slot having the timing as shown in FIGS. 7C and 7D is determined.

That is, in this example, transmission using transmission slot T3 and reception using reception slot R3 are performed in PS3, and transmission slot T3 of PS3 in PS4.
And the transmission at the timing of the reception slot R3 of PS3 are performed. Here, PS3 and PS
As described above, the communication slot between 4 is the P that is already communicating.
Since the selection is made after being synchronized with S1 and S2, the time Δt as shown in FIG. 11 can be eliminated, and multiplexing can be performed on the same frequency without causing a time unusable for communication.

[0052]

As described above, according to the present invention,
In a TDMA-TDD digital mobile communication system, a slave unit which is going to start direct communication between slave units detects a pattern and a signal level of a signal transmitted by a slave unit or a master unit that is already in communication and detects the slave unit. Or, since the communication slot is decided after establishing synchronization with the master unit, it is possible to eliminate the delay time until the communication slot is decided and cope with the multiplexing at the same frequency without causing a time unavailable for communication. It has an excellent advantage that it can contribute to the improvement of frequency utilization efficiency.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a digital mobile communication terminal according to the present invention.

FIG. 2 is a table showing a relationship between frequencies and carrier numbers used in a digital mobile communication system.

FIG. 3 is a diagram showing a control sequence of direct communication operation between handset units in the digital mobile communication system according to the present invention.

FIG. 4 is a configuration diagram of a control physical slot and a communication physical slot used in the digital mobile communication system according to the present invention.

FIG. 5 is a flowchart showing a control operation of a calling side handset in direct communication between handset units of the digital mobile communication system according to the present invention.

FIG. 6 is a flowchart showing a control operation of a receiving side handset in direct communication between handset units of the digital mobile communication system according to the present invention.

FIG. 7 is a configuration diagram of time slots in direct communication between handset units in the digital mobile communication system according to the present invention.

FIG. 8 is a schematic diagram showing a communication state between a master unit and a slave unit of a digital mobile communication system.

FIG. 9 is a configuration diagram of time slots during communication between a master unit and a slave unit of a digital mobile communication system.

FIG. 10 is a schematic diagram showing a direct communication state between slave units of a digital mobile communication system.

FIG. 11 is a configuration diagram of time slots during direct communication between handset units in a conventional digital mobile communication system.

[Explanation of symbols]

 1 Base unit (BS) 2, 2a, 2b, 2c, 2d Slave unit (PS1 to PS4) 21 Antenna 22 RF unit 23 Modem unit 24 TDMA unit 241 Sync generation unit 242 UW (unique word) detection unit 243 Transmission circuit unit 244 Reception circuit section 25 Codec section 26 Handset 27 Operation section 28 Control section

Claims (3)

[Claims] 1. A digital mobile communication system comprising a plurality of base units and a plurality of handset units communicating with the base unit, wherein the handset unit starts direct communication between the handset units and other handset units, Detects the pattern and signal level of the signal transmitted by the slave unit or master unit already in communication, establishes synchronization with the slave unit or master unit in communication, and establishes the communication slot used for direct communication between the slave units. A digital mobile communication system characterized by making a decision. 2. The slave unit has two modes, a master mode and a slave mode, relating to the procedure for starting direct communication between the slave units. In the master mode, the slave unit determines a communication slot at its own timing and determines the slave unit. Initiate direct inter-machine communication, and in slave mode, detect the pattern and signal level of the signal transmitted by the slave unit or master unit that is transmitting the channel to be used, and communicate with the slave unit or master unit in communication. 2. The digital mobile communication system according to claim 1, wherein synchronization is established, a communication slot to be used is determined based on the synchronization result, and direct communication between the handset units is started. 3. The digital mobile communication according to claim 1, wherein the signal to be detected is a unique word in a signal transmitted by the slave unit or the master unit already communicating with the control slot or the communication slot. system.