JPH05328428A - Mobile radio communication system - Google Patents

Abstract

PURPOSE:To provide economically uninterruptible hand-over with respect to the mobile radio communication system switching channels uninterruptibly when a mobile station moves between base station zones. CONSTITUTION:Each of plural mobile stations 1 and each of plural base stations 2 are provided with the optional number of exchange stations 3 and line control sections 4 and a mobile station 1 and a base station 2 implement radio communication by the time division multiple access system as the mobile radio communication system and the exchange 3 takes synchronization with the time division multiplex signal between base stations 2 to exchange a time slot corresponding to a radio channel. Furthermore, the exchange station 3 identifies busy state channel switching request information to inform it to the line control section 4 and implements the switching of radio channels between the mobile station 1 and the base station 2 and the switching of time slots in the exchange station 3 uninterruptibly during the busy state.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mobile radio communication system for switching channels without interruption when a mobile station such as an automobile telephone moves between base station zones. In a mobile radio communication system in which a mobile station such as a car phone or a mobile phone communicates via a base station, it is necessary for the mobile station to switch channels by moving between base station zones. There is a demand for a handover means for performing this channel switching without interruption.

[0002]

2. Description of the Related Art In a mobile radio communication system, each time a mobile station moves between zones during a call, a radio channel is switched and a wire line is switched at an exchange. Such channel switching during a call is called handover. In such a handover, the reception level from the mobile station is monitored at the base station, and it is determined that the mobile station has moved from its own base station zone to another zone due to the decrease in the reception level, and the line control unit etc. In addition, the mobile station determines that the mobile station has moved from another zone to its own base station zone due to an increase in the reception level, and notifies the line control unit, etc., and under the control of the line control unit, etc. The switching of the wired line between them and the switching of the wireless channel of the base station are performed. A method is also known in which the mobile station monitors the reception level from the base station and sends a channel switching request from the mobile station.

In such a handover, a momentary interruption occurs due to the time between the switching of the wireless channel and the switching of the wired line, and the transmission data is lost. In order to avoid such an interruption, the switching center is multi-connected to the base station in the current zone of the mobile station and the base station in the destination zone, and the mobile station connects via both base stations. A method is known in which switching is performed as a state in which communication can be continued.

As such a non-instantaneous interruption handover means, for example, a configuration shown in FIG. 13 is known. In the figure, BS1 and BS2 are zone-compatible base stations and MCCs.
Is a switching center, TRX is a radio transmitting / receiving unit, DLC is a delay control unit, BF is a buffer, BFC is a buffer control unit, SFA.
Is a super frame processing unit, SFG is a super frame clock generation unit, SW is a communication path switch unit, HDC is a handover control unit, BF1 and BF2 are buffers, BC
Is a buffer control unit, OR is an OR circuit, MC is a multi-connection unit, and SFCG is a superframe clock generation unit.

Base stations are respectively installed in a plurality of zones and are connected to the exchange MCC by a wired line. The base stations BS1 and BS1 located in the adjacent zones among them are connected.
S2 is illustrated. Each of the base stations BS1 and BS2 includes a radio transmission / reception unit TRX, a delay control unit DLC, a super frame clock generation unit SFG, etc., and the delay control unit DLC is
It includes a buffer BF, a control unit BFC thereof, and a superframe processing unit SFA. Also, the switching center MCC includes a speech path switch unit SW, a handover control unit HDC, a super frame clock generation unit SFCG, and the like, and the handover control unit HDC multi-buffers BF1 and BF2, its control unit BC, and an OR circuit OR. And a connecting portion MC.

When moving from the zone of the base station BS1 to the zone of the base station BS2, the speech path switch unit SW of the exchange MCC is controlled so that the path indicated by the dotted line is formed. Therefore, the data from the subscriber accommodated in the switching center MCC directly or via another switching center is transmitted to both base stations BS1 and BS2 by the multi-connection part MC, and the buffer of each base station BS1 and BS2 is transmitted. It is added to BF and written under the control of the buffer control unit BFC. Then, the buffer control unit BFC is synchronized with the super frame clock signal from the super frame clock generation unit SFG.
Is read out from the buffer BF and transmitted from the wireless transmission / reception unit TRX. In that case, in accordance with the transmission delay between the switching center MCC and the base stations BS1 and BS2, for example, a delay of Δt ₁ is given by the buffer BF at the base station BS1 and a Δt ₁ is given by the buffer BF at the base station BS2.
A delay of ₂ is given.

Data from a mobile station, not shown, is
It is received by the radio transmitting / receiving unit TRX of the base stations BS1 and BS2, and is exchanged via the superframe processing unit SFA.
It is transmitted to CC. In the handover controller HDC of the switching center MCC, the data from the base station BS1 and the data from the base station BS2 are written into the buffer BF1 and the buffer BF2, respectively, under the control of the buffer controller BC. The delay of Δt ₀ is given to the BF1 and the delay of Δt ₂ is given to the buffer BF2, which is read out and sent to the subscriber through the OR circuit OR.

Therefore, the data transmitted from the base stations BS1 and BS2 has delay times Δt ₁ and Δt due to the buffer BF.
The data that arrive at the mobile station at the same time under the control of t ₂ and are transmitted from the mobile station to the base stations BS1 and BS2 have the delay times Δt ₀ and Δt ₂ of the buffers BF1 and BF2 of the handover controller HDC. It is adjusted to the same time by the control, and at the same time, it is read from the buffers BF1 and BF2 and sent from the exchange MCC to the subscriber. At that time, by switching from the base station BS1 to the base station BS2,
A hitless handover can be achieved.

FIG. 14 is a diagram for explaining the operation of the conventional example, and shows the main points of the above-mentioned uninterrupted handover.
(F) is the switching center MC in the base stations BS1 and BS2.
The case where the data is received from C and transmitted to the mobile station is shown. (G) to (m) show switching of the reception data from the base stations BS1 and BS2 in the switching center MCC without any interruption and transmission. The case is shown. Further, (a) and (g) are superframe clock signals having a period Tf, (b) is a superframe timing signal received and extracted at the base station BS1,
(C) is the data input to the buffer BF of the base station BS1, (d) is the superframe timing signal received and extracted at the base station BS2, and (e) is the data input to the buffer BF of the base station BS2. Show.

Further, (h) is a buffer reference clock signal,
(I) is a superframe timing signal from the base station BS1, (j) is data input to the buffer BF1,
(K) is a superframe timing signal from the base station BS2, (l) is data input to the buffer BF2,
(M) shows the data output from the buffers BF1 and BF2.

The base station BS1 receives the superframe timing signal from the switching center MCC at the timing shown in (b) in response to the superframe clock signal shown in (a) from the superframe clock generator SFG, and outputs the data. Is written in the buffer BF as shown in (c), and similarly, in the base station BS2, the superframe timing signal from the exchange MCC is received at the timing shown in (d), and the data is written in the buffer BF in (e). Write as shown. Then, the base stations BS1 and BS2 read data from the buffer BF in synchronization with the superframe clock signal, and simultaneously transmit the same data from the base stations BS1 and BS2, as shown in (f).

The switching center MCC receives the superframe timing signal from the base station BS1 at the timing shown in (i), and receives the data in the buffer B as shown in (j).
The data is written in F1 or the superframe timing signal from the base station BS2 is received at the timing shown in (k), and the data is written in the buffer BF2 as shown in (l). Then, the data is read from the buffers BF1 and BF2 as shown in (m) according to the buffer reference clock signal shown in (h). In that case, the buffer BF1 causes Δt ₀ ,
Since the buffer BF2 gives a delay of Δt ₁ , they are read out at the same time, and are sent out via the OR circuit OR. In addition, the switching of radio channels in the base stations BS1 and BS2 is performed at the timing of tsw.

[0013]

In the above-mentioned conventional example, in order to cope with the channel switching to the base station having a large transmission delay, the buffers BF and BF1 are provided on the data receiving side from the start of communication. , BF2 further delays in addition to the transmission delay, and at the time of channel switching, the base stations BS1 and BS2 before and after switching and the switching center MCC are multi-connected, and at each of the base stations BS1 and BS2 and the switching center MCC. By aligning the delay amount from the data transmission time on the data transmission side to the buffer output time on the reception side,
The radio channel is switched and the time slot is switched in the switching center MCC, so that the channel can be switched without interruption.

However, the switching center MCC is provided with buffers BF1, BF2, etc. for adjusting the transmission delay from the base station before and after channel switching, and a multi-connecting unit MC, etc. for multi-connecting to each base station BS1, BS2. , It is necessary to provide the number of times of handovers that can occur simultaneously. In particular,
In a mobile radio communication system with a small zone,
Since the number of handovers increases, there is a drawback that the configuration of the switching center becomes complicated and expensive. The present invention is
The objective is to realize economical non-disruptive handover.

[0015]

A mobile radio communication system of the present invention will be described with reference to FIG.
And a plurality of base stations 2, a switching center 3 and a line controller 4,
Between the mobile station 1 and the base station 2 is a mobile radio communication system for performing radio communication by a time division multiple access system, and between the base station 2 and the exchange 3 is a radio transmission / reception at the base station 2. The exchange station 3 synchronizes the time-division multiplexed signals with the plurality of base stations 2 to exchange the time slot corresponding to the radio channel and adds the time-division multiplexed signals to the time-division multiplexed signals. The switched channel switching request information is identified and transferred to the line control unit 4, and in accordance with an instruction from the line control unit 4, in synchronization with the switching of the wireless channel, the switching center 3
It is equipped with a configuration that switches the time slot in the above and switches the channel during a call without interruption.

Further, between the base station 2 and the switching center 3, there is provided a multiplexing / separating means for multiplexing and demultiplexing the time division multiplexed signal. Alternatively, between the base station 2 and the exchange 3, the exchange 3
And a frame synchronization means for absorbing a difference in transmission delay between each base station 2 and each base station 2. Alternatively, frame conversion means for converting the frame format between the exchange 3 and another switching network is provided. Alternatively, codec conversion means for converting the code format between the exchange 3 and another exchange network is provided. The switching center 3 includes a switch unit 5 which is a combination of a time switch T and a space switch S, interface units 6 and 7, a call control unit 8 and the like, and the interface units 6 and 7 perform multiplexing / demultiplexing. Means, frame synchronization means, frame conversion means, codec conversion means, etc. can be adopted.

[0017]

Between the base station 2 and the exchange 3, the base station 2 transmits as a time division multiplexed signal which is wirelessly transmitted and received. Transmission and reception between the mobile station 1 and the base station 2 are performed by using different time slots of the same frequency, and the base station 2 may, for example, transmit and receive by one radio frequency. There are four slots each, and a total of eight time slots make up one frame.
It is possible to enable communication with 24 mobile stations 1 by using this radio frequency. In addition, the exchange 3 performs time slot exchange processing corresponding to the radio channel, and the mobile station 1
Alternatively, when the in-call channel switching request information from the base station 2 is identified, this channel switching request information is transferred to the line control unit 4. The line control unit 4 judges the channel switching destination,
Instruct to prepare for switching. The wireless channel is switched when the mobile station 1 and the base station 2 are ready for switching, and the time slot corresponding to the wireless channel of the switching center 3 is switched in synchronization therewith, so that the wired channel between the base station 2 and Switching can be performed and a non-interruptive handover can be performed.

The multiplexing / separating means provided between the base station 2 and the switching station 3 multiplexes time-division multiplexed signals for a plurality of radio frequencies between the base station 2 and the switching station 3. Then, the base station 2 separates them according to the radio frequency, and the mobile station 1
The mobile station 1 multiplexes the data corresponding to the radio frequency from the mobile station 1 and sends it to the exchange 3. Further, a frame synchronizing means is provided between the base station 2 and the exchange station 3 to absorb a delay difference due to a difference in the distance of a wired line between each base station 2 and the exchange station 3. When the exchange 3 and the other exchanges have different frame formats, frame conversion means is provided to convert the frame formats to each other. Further, when the exchange 3 and the other exchanges have different code formats, a codec converting means is provided to convert the code formats to each other.

[0019]

FIG. 2 is an explanatory view of an embodiment of the present invention.
1 is a mobile station (PS), 12-1 and 12-2 are base stations (B).
S), 13 is a switching center, 14 is a line control unit, 15 and 17 are space switch units, and 16 is a time switch unit (TSS). Although a large number of base stations are connected to the exchange 13, two base stations 12-1 and 12-2 are shown for convenience. Further, the exchange 13 shows the case of the configuration of the combination of S-T-S including the space switch S and the time switch T, but other S-T, T-S-T, S-T-S-T. It is also possible to use various combinations of configurations such as. The call control unit 8 in FIG. 1 is not shown.

FIG. 3 is an explanatory diagram of a frame structure, showing a case where a 4-channel ping-pong transmission system is used between the mobile station and the base station, and (a) is a radio frame, which goes from the mobile station to the base station. On the contrary, when the downlink is from the base station to the mobile station, the case is shown in which the uplink time slots T _{1 to} T ₄ and the downlink time slots R _{1 to} R ₄ are included. For example, the uplink time slot T ₁ has 6 frequencies. Minute upstream signals are multiplexed. This one radio frame has a 4-channel structure, and can be, for example, a 5 ms, 1920-bit structure. In this radio frame, four upstream time slots T _{1 to} T ₄ are followed by _four downstream time slots R ₁
Shows the configuration of arranging the to R ₄ but may be reversed, a configuration of arranging four downlink time slots R ₁ to R 4 Following the _four uplink time slots T ₁ through T _4. Alternatively, it is possible to adopt a configuration in which the upstream time slots and the downstream time slots are alternately arranged. The base station is generally configured to use a plurality of radio frequencies, and for example, if 6 frequencies are used, it has 24 radio channels.

Also, (b) is a superframe, and (c) is P.
CM frame, (d) is a multiplexed signal for 6 frequencies, (e)
Indicates a signal of one time slot. The signal of this one time slot has F bits and S before and after 6 bits D1 to D6.
Is obtained by the 8-bit structure by adding the bit, and 6 frequency component multiplexed to indicate this to (d), DF ₁ ~
A multiplexed signal composed of DF _{6 is} multiplexed as shown in (c) to form a 1PCM frame composed of PM ₁ to PM ₄ . A frame bit F can be added to the head of this 1PCM frame. This PCM frame is multiplexed 40 times as shown in (b) to form one super frame composed of SP _{1 to} SP ₄₀ . This superframe becomes 7680 bits with a period of 5 ms except for the frame bit F.
It is transmitted as a multiplexed signal of the primary group of 544 Mbps.

FIG. 4 is a diagram for explaining the operation of the embodiment of the present invention, in which (a) shows the control contents in the line control unit 14,
(B) and (c) are upstream and downstream signals between the exchange 13 and other exchanges or subscribers, and (d) and (e) are between the base station 12-1 and the exchange 13. Upstream and downstream signals,
(F) and (g) are upstream and downstream signals between the base station 12-2 and the switching center 13, and (h) and (i) are base stations 12-.
1, 12-2 wireless transmission / reception data, (j) is the mobile station 11
Wireless transmission / reception data, (k) and (l) indicate transmission / reception processing data of the mobile station 11, and (m) indicates wireless frequencies f1 and f2. Also, the uppercase letters of the alphabet indicate downlink signals and the lowercase letters indicate upstream signals.

The mobile station 11 communicating with the base station 12-1 in the fourth slot (fourth channel) of the frequency f1 moves to the zone of the base station 12-2, and the frequency f2 of the base station 12-2. The case of switching to the second slot (second channel) will be described with reference to steps (1) to (22). The mobile station 11 is a mobile station-initiated type that sends out channel switching request information for switching to another radio frequency when detecting deterioration of the communication quality such as the electric field strength or the bit error rate of the currently communicating radio channel. The case of the system is shown.

(1). As described above, the mobile station 11 moves from the zone of the base station 12-1 currently in communication to another base station 12-2.
By moving to the zone of
CCH) is used to send the channel switching request information. In that case, a unique word is inserted in an empty downlink slot (empty channel), and the mobile station 11 detects this, for example, to switch the channel to the second slot (second channel) of the radio frequency f2. The request information is transmitted by the upstream signal a.

(2). This upstream signal a is transmitted to the base station 12-1.
Is transmitted to the exchange 13. That is, (j) → (h) →
The upstream signal a is transmitted to the exchange 13 through the route (d).
The bold line indicates the attached control channel. (3). In the exchange station 13, the uplink signal of the fourth slot of the base station 12-1 is exchanged with the fourth slot of the uplink signal to another exchange station. (4). When the exchange 13 exchanges time slots,
When the content of the attached control channel is read and the channel switching request information from the mobile station 11 is identified, this is notified to the line control unit 14. That is, the channel switching request information is transferred as indicated by the dotted arrow from (d) to (a).

(5). The line control unit 14 gives an instruction for channel switching preparation according to the channel switching request information. That is, the switching center 13 is instructed to insert the channel switching preparation information including the information of the switching destination radio frequency f2 and the second slot into the downlink signal to the base station 12-1. (6). In this case, the exchange station 13 exchanges the fourth slot of the downlink signal from another exchange station with the fourth slot to the base station 12-1. (7). The switching center 13 inserts the channel switching preparation information into the attached control channel (ACCH) of the downlink signal D to the base station 12-1 according to the instruction from the line controller 14.
That is, the channel switching preparation information is inserted into the downlink signal D as shown by the dotted arrow from (a) to (e). (8). The downlink signal D is transmitted to the mobile station 11 as indicated by a solid arrow of (e) → (h) → (j).

(9). The mobile station 11, when the timing of the fourth slot of the radio frequency f1 being currently communicated elapses,
As shown in (m), while switching to the radio frequency f2 instructed by the channel switching preparation information, the instructed slot is received. (10). Since the unique word is inserted in the empty downlink slot as described above, the mobile station 11 receives the unique word and receives the designated radio frequency f2.
It is possible to judge whether or not the reception of the slot has been successful. In this case, nothing is done unless the reception is successful.

(11). The mobile station 11 immediately returns to the reception state of the slot of the radio frequency f1 being currently communicated when the designated timing of the slot of the radio frequency f2 has elapsed. (12). The mobile station 11 uses the radio frequency f1 currently in communication.
When the timing of the slot of 1 has passed, it is switched again to receive the slot of the instructed radio frequency f2. (13). When the mobile station 11 succeeds in receiving the designated slot of the radio frequency f2, the mobile station 11 sends a channel switching preparation completion notice using the attached control channel (ACCH) of the uplink slot of the radio frequency f2. At this time, the radio frequency f2 that has been successfully received is stored.

(14). The base station 12-2 is the mobile station 11
When the channel switching preparation completion notification from the slot of the radio frequency f2 is received from, the packet is transferred to the switching center 13 as indicated by the solid arrow of (j) → (i) → (f). (15). The switching center 13 has the base station 12 corresponding to the second slot of the radio frequency f2 of the channel switching destination of the mobile station 11.
-2, the attached control channel (ACCH) of the second slot is monitored, and when the transferred channel switching preparation completion notification is received and identified, the line control unit 14 is immediately notified to the line arrow from (f) to (a). Transfer as shown in. (16). The line control unit 14 instructs the exchange station 13 to insert a channel switching execution instruction for the mobile station 11 into the downlink slot to the base station 12-1, and to specify a destination of exchange of downlink signals from other exchange stations. , Second of base station 12-2
The exchange 13 is instructed to change to a slot.

(17). The switching center 13 inserts a channel switching execution instruction into the auxiliary control channel (ACCH) of the downlink signal H and controls to switch from the downlink signal I of the next frame to the second slot of the base station 12-2. (18). The downlink signal H in which the channel switching execution instruction is inserted is transmitted from the base station 12-1 to the mobile station 11. (19). The mobile station 11 sends a channel switching execution notification on the auxiliary control channel (ACCH) of the uplink signal h,
From the next frame, the communication is continued by switching to the second slot of the radio frequency f2.

(20). The upstream signal h in which the channel switching execution notification is inserted is transmitted to the exchange 1 via the base station 12-1.
3 is transmitted. (21). The switching center 13 transfers a channel switching execution notification by the upstream signal h to the line control unit 14. (22). The switching center 13 releases the path of the upstream signal from the base station 12-1 from the upstream signal i of the next frame,
The exchange between the second slot of the base station 12-2 and the fourth slot of the other exchange starts. Therefore, the base station 12-
Downstream signals from the mobile stations 11, 12 and 1, 12-2, A, B,
C, ... Are transmitted by the time slots shaded with (h), (i), and (j), and the uplink signals a, b, and b from the mobile station 11 to the base stations 12-1 and 12-2 are transmitted. c, d, ...
Is transmitted by the white time slot adjacent to the shaded time slot, and handover can be performed without interruption. Note that, in this case, the case is shown in which the uplink time slots and the downlink time slots are alternately arranged.

FIG. 5 is an explanatory view of another embodiment of the present invention, in which the same reference numerals as those in FIG. 2 designate the same parts, 20 is an antenna, 21 is a transmission / reception common part, and 22 is a plurality of band pass filters. Wave portion, 23 is a receiving portion, 24 is a multiplexing portion, 25
Is a transmitting unit, 26 is a multiplexing / separating means, 27 is a multiplexing unit, 2
8 is a separation unit, 31 is a switch unit, 32 and 34 are multiplexing units for performing multiplexing and separation, 33 is a frame conversion unit, 35 is a codec conversion unit, 36 and 37 are code conversion units, 40 is a processor (CPU), 41 is a read only memory (R
OM), 42 is a random access memory (RAM), 4
Reference numeral 3 is an interface unit (IF).

The signal received by the antenna 20 is input from the transmission / reception common unit 21 to the demultiplexing unit 22, demultiplexed into 6 frequencies, and input to the frequency-corresponding receiving unit 23 for reception demodulation. The demodulated baseband signal is multiplexed by the multiplexer 27 and sent to the exchange 13. Exchange station 1
The multiplexed signal from 3 is separated by the separation unit 28 in accordance with the frequency. The separated baseband signals are modulated into respective radio frequencies by the frequency-corresponding transmission unit 25, multiplexed by the multiplexing unit 24, and transmitted from the antenna 20 via the transmission / reception sharing unit 21. In the operation explanatory diagram of FIG. 4 described above, the multiplexing / separating means 26 is omitted, and the base station 1
The operation in the case where the receiving unit 23 and the transmitting unit 25 of No. 2 are connected to the exchange station 13 by a wired line will be described.

A plurality of base stations 12 are connected to the switch section 31 of the exchange station 13 via wired lines.
Further, the frame converting means 33 can convert the frame configurations between the other exchanges by disassembling and assembling the frames, when the frame configurations of the other exchanges differ.

The codec conversion means 35 is composed of code conversion units 36 and 37, and for example, an AD of 32 kbps.
Code conversion between a PCM code and a PCM code of 64 kbps is performed, and the code conversion units 36 and 37 each temporarily convert to natural binary data, transfer it from one to the other, and convert it to each code. Is output. If the exchange 13 and the other exchanges have the same code format, the codec converting means 35 can be omitted.

The line controller 14 includes a processor 40,
A read-only memory 41 that stores a control program, fixed parameters, and the like, a random access memory 42 that writes and reads various information, and an interface unit 43 that transmits and receives various information to and from the exchange station 13 are provided. .. Further, a plurality of exchanges may be connected via the interface unit 43. Processor 40
Is a mobile station which receives and identifies various information transferred from the exchange station 13 based on the program stored in the read-only memory 41, and which is written in the random access memory 42.
With reference to the status information of the base station and the exchange, various instructions are formed and sent to the exchange 13 via the interface unit 43.

FIG. 6 is an explanatory view of still another embodiment of the present invention, in which the frame synchronizing means 50 is connected to the base stations 12-1, 12
-2 and the switching center 13 are provided. The frame synchronization means 50 includes a clock circuit 54, a buffer 51 including a variable number of shift registers corresponding to a base station, a counter 52, and an arithmetic circuit 53. Reference numeral 11 is a mobile station, and 14 is a line controller.

The clock circuit 54 generates a clock signal CK synchronized with the clock signal CLK from the exchange station 13 and supplies it to each unit. Further, the super frame pulse SFP from the switching center 13 is sent from the frame synchronizing means 50 to each base station 1.
2-1 and 12-2, and the base stations 12-1 and 12-2
To the frame synchronization means 50. The counter 52 starts counting the clock signal CK from the transmission timing of the super frame pulse SFP, and the base station 1
The amount of delay between the switching center 13 and the base stations 12-1 and 12-2 is measured by stopping the counting of the clock signal CK by the superframe pulse SFP returned from 2-1 and 12-2.

The count content of the counter 52 is input to the arithmetic circuit 53, and the arithmetic circuit 53 causes the base stations 12-1 and 12 to operate.
-2, a value for correcting the delay difference between
By 1, the data is delayed by the delay time corresponding to the correction value and transferred to the exchange 13. When the count content of the counter 52 indicates the round-trip time of the super frame pulse SFP from a certain value, the arithmetic circuit 53 corrects the value obtained by subtracting 1/2 of the count content. This correction value represents a value obtained by subtracting the delay between the frame synchronization means 50 and the base station from a certain offset delay, and the time of the frame from each base station from the frame synchronization means 50 to the exchange. The positions can be aligned.

Further, the super frame pulse S of the switching center 13
The FP is sent to the base stations 12-1 and 12-2, and the base station 12
-1 and 12-2 fold back as shown by the dotted line, and the exchange 1
In 3 as well, by folding back as shown by the solid line, the amount of transmission delay between the base stations 12-1 and 12-2 and the switching center 13 is measured by the above-mentioned counter 52, etc. Frames transmitted from 12-1 and 12-2 are exchanges 13
It can also be synchronized at. The base stations 12-1 and 12-2 can be synchronized with each other by, for example, a local network synchronization method.

FIG. 7 is an explanatory diagram of an exchange station according to an embodiment of the present invention, in which 61 is a space switch section, 62 is a time switch section,
Reference numeral 63 denotes a space switch unit, which shows a case of the S-T-S configuration. Further, 64 is a call control unit, 65 is an auxiliary control channel extraction unit, 66 is an auxiliary control channel insertion unit, 67 is a clock distribution unit, 68 is a frame synchronization unit, and 69 is a frame conversion unit.

The call control unit 64 includes space switch units 61 and 6
3 and the time switch unit 62 are controlled to perform highway exchange and time slot exchange. Also, the channel switching request information, the channel switching preparation completion notification, the channel switching completion notification, etc. by the attached control channel (ACCH) are extracted by the extraction unit 65 and input to the call control unit 64. 14 is transferred. Further, the channel switching preparation instruction, the channel switching instruction, etc. transferred from the line control unit 14 are inserted into the time slot corresponding to the radio channel by the insertion unit 66 under the control of the call control unit 64.

The frame synchronization section 68 can use the frame synchronization means 50 shown in FIG.
Further, the frame conversion unit 69 converts the frame format when the frame format of the wireless part and the frame format of the wired part are different, and enables data transmission / reception with other exchanges.

FIG. 8 is an explanatory diagram of a base station according to an embodiment of the present invention, in which 20 is an antenna, 21 is a transmission / reception common unit, and 22-1 to 22-1.
22-6 is a band pass filter corresponding to the radio frequencies f1 to f6 forming the demultiplexing unit, 23-1 to 23-6 is a receiving unit corresponding to the radio frequencies f1 to f6, 24 is a multiplexing unit, and 25-1 to 25-1.
25-6 is a transmitter corresponding to radio frequencies f1 to f6, 27 is a multiplexer, 28 is a demultiplexer, 29 is a flip-flop, 30
Is a bit timing reproducing unit.

The bit timing reproduction unit 30 extracts the clock signal CK from the data from the exchange, supplies the clock signal CK to each unit, and, in addition to the clock terminal of the flip-flop 29, converts the data into one clock signal. Held for a while, the demultiplexing unit 28 separates the multiplexed signals corresponding to the radio frequencies f1 to f6, the transmitting units 25-1 to 25-6 modulate the multiplexed signals to the respective radio frequencies f1 to f6, and the combining unit 24 combines them. Waves are transmitted and transmitted from the antenna 20 via the transmission / reception sharing unit 21. That is, as shown in FIG.
As shown in downlink time slots R _{1 to} R ₄ , downlink signals of radio frequencies f 1 to f 6 are multiplexed in each time slot.

The upstream signals of the upstream time slots T _{1 to} T ₄ received from the mobile station are the bandpass filter 22-1.
22-6 are separated by radio frequencies f1 to f6 and are input to receiving sections 23-1 to 23-6, and the demodulated baseband signals are multiplexed by multiplexing section 27 and sent to the exchange. To be done.

FIG. 9 is an explanatory diagram of a mobile station according to an embodiment of the present invention, in which 71 is a microphone and 72 is an AD conversion unit (A /
D), 73 is a coding unit (COD), 74 is a speaker, 7
5 is a DA conversion unit (D / A), and 76 is a decoding unit (DE).
C), 77 is a time division processing unit, 78 is a control unit, 79 is a transmission unit, 80 is a reception unit, 81 is a variable frequency oscillation unit, 82 is a transmission / reception common unit, and 83 is an antenna.

The control unit 78 is composed of a microprocessor or the like, and the time division processing unit 77 controlled by the control unit 78 controls transmission / reception in transmission / reception time slots. For example, as shown in FIG. 4, transmission / reception is performed in the fourth slot of frequency f1. The variable frequency oscillator 81 is composed of a frequency synthesizer or the like, and switching of the radio frequencies f1 to f6 is executed at high speed under the control of the controller 78, and the transmitter based on the carrier wave from the variable frequency oscillator 81. The modulation is carried out at 79, and the demodulation is carried out at the receiving section 80.

FIG. 10 is an explanatory diagram of the multiplexing / separating means of the embodiment of the present invention. 90 is a multiplexing unit, 91 and 95 are counters, 92 is a serial / parallel conversion unit (S / P), and 93 and 94 are. Dual port memory, 96 is a parallel / serial converter (P /
S), 97 is a processor (CPU), 98 is an address bus, 99 is a data bus, 100 is a separation unit, 101, 10
5 is a counter, 102 is a parallel / serial converter (P / S), 1
03 and 104 are dual port memories, 106 is a serial / parallel converter (S / P), 107 is a processor (CP).
U) and 108 are address buses, and 109 is a data bus. This multiplexing / separating means is composed of a base station 12 and a switching center 13.
It is connected to and to transmit and receive multiplexed data.

The counters 91, 95, 101, 105 are
Counts clock signal CLK and frame pulse FP
The counters 91 and 101 are reset by the super frame pulse SFP, and the counters 95 and 105 are reset by the super frame pulse SFP, and the dual port memories 93, 94 and 1 are reset.
Addresses 03 and 104 are formed. For example, the write address of the dual port memory 93 becomes the content of the counter 91 synchronized with the frame pulse FP, and the serial / parallel conversion unit 92 converts the serial data DA into parallel,
It is written in the dual port memory 93.

The read address of the dual port memory 93 is applied from the processor 97 via the address bus 98, and the data sequentially read from each dual port memory 93 is output to the dual port memory 93 via the data bus 99. It is added to the port memory 94. The write address of the dual port memory 94 is applied from the processor 97 via the address bus 98, and the parallel data read from the dual port memory 93 on the input side is sequentially output to the dual port memory 94 on the output side. Written,
The parallel data is read from the dual port memory 94 by the read address from the counter 95 which counts the clock signal SCK and is reset by the super frame pulse SFP, converted into serial data MDA by the parallel / serial conversion unit 96, and transmitted. To be done. Therefore, the data DA written in the N input side dual port memories 93 is sent from the output side dual port memory 95 as N multiplexed data NDA.

The separating unit 100, contrary to the multiplexing unit 90,
The N-multiplexed data NDA is separated into the data DA, and the N-multiplexed data NDA is the serial-parallel conversion unit 106.
Is converted into parallel data by and input to the dual port memory 104, and counts the clock signal SCK,
The dual port memory 105 is written with the count content of the counter 105 reset by the superframe pulse SFP as a write address.

The read address of the dual port memory 105 is read from the processor 107 to the address bus 108.
Data applied to and read from the dual port memory 103 via the data bus 109 and a write address applied from the processor 107 via the address bus 108 to each dual port memory.
It is written so as to be distributed to the memory 103, counts the clock signal CLK, is read by the read address from the counter 101 which is reset by the frame pulse FP, and is converted into serial data DA by the parallel / serial conversion unit 102. The N multiplexed data NDA becomes the separated data DA.

FIG. 11 is an explanatory view of the frame synchronizing means of the embodiment of the present invention, in which 111 is a dual port memory,
Reference numeral 112 is a flip-flop, 113 is a clock reproducing unit (BTR), 114 is a frame timing reproducing unit (FT).
R), 115 are counters (CTR), 116 are counters (CTR), 117 are flip-flops, and 118 is a wired line to the base station. This frame synchronization means
It is provided on the side of the switching center 13 between the base station 12 and the switching center 13.

Input data from the base station via the wired line 118 is added to the flip-flop 112 and set by the clock signal reproduced by the clock reproducing unit 113, and the output of the flip-flop 112 is added to the dual port memory 111. Data is reset by a frame pulse from the frame timing reproducing unit 114, and the count content of the counter 115 that counts the clock signal from the clock reproducing unit 113 is used as a write address to write data to the dual port memory 111 via the flip-flop 112. Is written.

The contents of the counter 116, which is reset by the frame pulse FP from the exchange side and counts the clock signal CLK, is added to the dual port memory 111 as a read address, and the read data is passed through the flip-flop 117. Is output. Therefore, the data from each base station is synchronized with the frame pulse FP on the exchange side.

FIG. 12 is an explanatory diagram of the frame converting means of the embodiment of the present invention, in which 121 is a multiplexing unit, 122 is a radio frame assembling unit, 123 is a demultiplexing unit, and 124 is a radio frame decomposing unit. For example, band-compressed data for four channels of 32 kbps from another switching center and 192 k
When converting to a bps wireless frame, the wireless frame assembling section 122 assembles a 192 kbps downlink wireless frame by adding bits corresponding to a unique word, an auxiliary control channel, etc. to continuous data of 32 kbps × 4 channels. .. The multiplexing unit 121 multiplexes the 192 kbps data from the six radio frame assembling units 122, for example, and transmits the multiplexed data of 1.544 Mbps to the exchange.

The exchange exchanges the time-division exchange for the multiplexed data of 1.544 Mbps, and also the 1.54 from the exchange.
The 4 Mbps data is separated by the demultiplexing unit 123 into 192 kbps data corresponding to the six radio frame disassembling units 124, and each radio frame disassembling unit 124 decomposes the data into 32 kbps data, and the other switching center or the other exchange. It returns to the radio frame assembling section of the mobile station, and communication can be performed between mobile stations by this return path.

The above-mentioned frame synchronization means, frame conversion means, multiplexing / separation means and codec conversion means can be provided in the switching center 13. For example, as the interface units 6 and 7 in FIG. The function of means can be provided. It is also possible to provide the call control units 8 (see FIG. 1) and 64 (see FIG. 7) with the function of the line control unit 14 for controlling the non-instantaneous interruption handover.

[0060]

As described above, the present invention is a mobile radio communication system for performing radio communication between a mobile station 1 and a base station 2 by a time division multiple access system.
Performs time-division multiplexed signal synchronization with the base station 2 to exchange time slots corresponding to radio channels, and identifies channel switching request information during a call, thereby
The line control unit 4 switches the wireless channel and the time slot according to an instruction, and does not require a buffer for giving a large delay as in the conventional example, and a normal time division switch can be used. There is an advantage that it can be applied to realize a non-disruptive handover.

Further, when the multiplexing / separating means is provided, even if the number of wireless channels of the base station 2 is large, the switching center 3
Since data can be transmitted by a single wired line between and, economic efficiency can be achieved. Further, when the frame synchronization means is provided, even if there is a variation in the transmission delay time between the base station 2 and the switching center 3, the variation in the transmission delay time is corrected by the frame synchronization, so that the stable movement can be achieved. There is an advantage of enabling wireless communication.

Further, when the frame converting means is provided, when connected through the exchange network of various systems,
The frame format may differ depending on the system, but these frame formats can be converted to correspond to the system so that the communication between the subscriber and the mobile station accommodated in the system of the different frame format can be performed. Further, even when the codec converting means is provided, there is an advantage that communication between a subscriber accommodated in a switching network having a different code format and a mobile station can be made possible.

[Brief description of drawings]

FIG. 1 is a diagram illustrating the principle of the present invention.

FIG. 2 is an explanatory diagram of an embodiment of the present invention.

FIG. 3 is an explanatory diagram of a frame configuration.

FIG. 4 is an operation explanatory diagram of the embodiment of the present invention.

FIG. 5 is an explanatory diagram of another embodiment of the present invention.

FIG. 6 is an explanatory diagram of still another embodiment of the present invention.

FIG. 7 is an explanatory diagram of an exchange according to an embodiment of the present invention.

FIG. 8 is an explanatory diagram of a base station according to the embodiment of this invention.

FIG. 9 is an explanatory diagram of a mobile station according to the embodiment of this invention.

FIG. 10 is an explanatory diagram of a multiplexing / separating unit according to the exemplary embodiment of the present invention.

FIG. 11 is an explanatory diagram of a frame synchronization unit according to the embodiment of this invention.

FIG. 12 is an explanatory diagram of a frame conversion unit according to the embodiment of this invention.

FIG. 13 is an explanatory diagram of a conventional example.

FIG. 14 is an operation explanatory diagram of a conventional example.

[Explanation of symbols]

 1 mobile station 2 base station 3 switching station 4 line control unit 5 switch unit 6, 7 interface unit 8 call control unit

Claims (5)

[Claims] 1. A plurality of mobile stations (1), a plurality of base stations (2), a switching center (3) and a line control unit (4), the mobile stations (1) and the base stations (2). Between the base station (2) and the switching center (3) in the mobile radio communication system that performs radio communication by a time division multiple access system. The exchange station (3) exchanges time slots corresponding to radio channels by synchronizing the time division multiplex signals with a plurality of the base stations (2) by transmitting as time division multiplex signals for wireless transmission and reception. The channel switching request information during communication, which is performed and added to the time division multiplexed signal, is identified and transferred to the line control unit (4), and the wireless channel is switched according to an instruction from the line control unit (4). The time slot is switched in the exchange (3) in synchronization with The mobile radio communication system characterized by comprising a structure for switching the channel during a call without interruption. 2. A multiplexing / separating means for multiplexing and demultiplexing the time division multiplexed signal is provided between the base station (2) and the switching center (3). The mobile radio communication system according to claim 1. 3. A frame which absorbs a difference in transmission delay between the plurality of base stations (2) and the exchange (3) and between the exchange (3) and each base station (2). The mobile radio communication system according to claim 1, further comprising a synchronization means. 4. The mobile radio according to claim 1, wherein a frame converting means for converting a frame format between the exchange (3) and another exchange network is connected to the exchange (3). Communications system. 5. The mobile radio according to claim 1, wherein codec conversion means for converting a code format between the exchange (3) and another exchange network is connected to the exchange (3). Communications system.