JPH07177555A - Handover processing circuit - Google Patents

Abstract

PURPOSE:To reduce the hit time of voice in the handover processing in a digital mobile communication system adopting the narrow band TDMA system for a radio block. CONSTITUTION:A voice signal before handover is path-connected to input output terminals A, a, a voice signal after handover is path-connected to input output terminals B, b, and a voice signal of an opposite party of communication is path-connected to input output terminals C, c. A synchronization detection circuit 9 discriminates a coding type of the voice signal, and uses code conversion circuits 1, 3, 6 when the type is a code type 1 and uses code conversion circuits 2, 4, 7 when the type is a code type 2. The pre-stage conversion circuits 1, 3 or 2, 4 convert the signal into a linear code, an adder circuit 5 adds the voice signals before and after the handover to the converted signal, the post- stage code conversion circuit 6 or 7 restores the signal into the original code type and the resulting signal is fed to the output terminal C in any code type. The voice signal from the opposite party of communication is sent to the output terminals a, b via a timing adjustment circuit 15.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a handover processing circuit used in communication channel switching processing in a digital mobile communication system.

[0002]

2. Description of the Related Art Generally, a digital mobile communication system includes mobile stations 201, 202 and base stations 203, 2 as shown in FIG.
04, 205 and mobile communication switching center 206.
While the mobile station 201 and the mobile station 202 are in a call, the mobile communication switching center 206 connects the call paths 207 and 208. When the mobile station 201 moves from the service area of the base station 203 to the service area of the base station 204 during a call, the mobile communication switching center 206 receives the wireless call channel establishment report from the base station 204 with the mobile station 201. , Call path 2
07 is switched to the call path 208, and the handover process ends.

On the other hand, while the mobile station 201 is in a call with a general public subscriber, the mobile switching center 206 has a call path 2 as shown in FIG.
10 are connected. Similarly to the above, when the mobile station 201 moves, the mobile switching center 206 assigns the radio communication channel of the mobile station 201 and the base station 204, and at the same time,
Once, call paths 212 and 2 with the three-way call trunk 211
Switch to 13,214. After that, after receiving a report for establishing a wireless communication channel with the mobile station 201 from the base station 204, the communication path is switched to the communication path 215, and the handover processing ends.

In this case, even in the transient state until the mobile communication switching center receives the new radio communication channel establishment report,
The voice before and after the handover of the mobile station 201 reaches the mobile station 202 through the three-way call trunk 211, so that the interruption time is minimized.

[0005]

As described above, the conventional three-way call trunk can be used in the handover processing during a call between the mobile station and the general public subscribers by using the narrow band TDMA method in the wireless section. Even if the mobile station talks to a general public subscriber, the A-law or μ
This is because the serial transmission is performed at 64 [kbps] according to the PCM coding rule. However, in general, in a call between mobile stations, a conventional three-way call trunk is used because a base station stores fixed length data as shown in FIG. 5 to form a frame structure with a synchronization pattern and serially transmits in frame units. There was a problem that it could not be used.

[0006]

A handover processing circuit according to the present invention comprises a first code type to be coded according to the A law or the μ law, or a first code type for compressing information for lowering a transmission rate. From the first, second, and third input terminals for inputting a digital signal having the code type of 2, the first, second, and third output terminals for outputting the digital signal, and from the first input terminal The signal of
A first code conversion circuit that converts the code type of the first code into a linear code, and the second code conversion circuit that receives a signal from the first input terminal as an input
A second code conversion circuit for converting the code type of the above into a linear code, and a signal from the first input terminal as an input, and the signal of the second code type is put in fixed length data to form a frame together with a synchronization pattern. A sync detection circuit that forms a structure and detects a sync pattern at the time of serial serial transmission in frame units, and determines the code type of an input signal; and a signal from the second input terminal as an input. The first
A third code conversion circuit for converting the code type of the second code into a linear code, and the second code conversion circuit using the signal from the second input terminal as an input.
A fourth code conversion circuit for converting the code type of the above into a linear code, and the synchronization detection circuit according to a control signal from the outside,
A control circuit for instructing an operation of a delay circuit described later;
And a second selection circuit for inputting the output signals of the second code conversion circuit and selecting and outputting the input signal according to the sync pattern detection state of the sync detection circuit, and the third and fourth code conversion circuits. Second input circuit which receives the output signal of the first input signal and selects and outputs the input signal according to the synchronization pattern detection state of the synchronization detection circuit, and adds the linear codes output from the first and second selection circuits. An adder circuit for inputting a signal from the adder circuit, and a fifth code conversion circuit for converting a linear code to the first code type; and a signal from the adder circuit for inputting a linear code to the first code A sixth code conversion circuit for converting to a code type of 2, a delay circuit for delaying and outputting a signal from the control circuit for a fixed time, a signal from the first input terminal, the fifth and sixth signals. Input the output signal of the code conversion circuit A third selection circuit for selecting and outputting an input signal according to a sync pattern detection state of the sync detection circuit and an output signal of the delay circuit; and an output timing of the output signal of the third selection circuit to an external device. And a first timing adjusting circuit for adjusting the output of the signal from the third input terminal to the external device, and adjusting the output timing of the signal from the third input terminal to the external device. And a second timing adjustment circuit for outputting to.

[0007]

The present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of an embodiment of the handover processing circuit of the present invention. The code type of the digital signal input / output to / from the circuit of the present invention is the usual A law or μ
There are two types: a code type 1 according to the PCM code rule of the law, and a code type 2 for compressing and encoding information to reduce the transmission rate. The code type 1 is serially transmitted at a normal 64 kbps, and the code type 2 is put into fixed length data as shown in FIG. 5 to form a frame structure together with a synchronization pattern and serially transmitted in frame units. These signals are input / output via three sets of input / output terminals A and a, B and b, and C and c. The interface between these three sets of input / output terminals and the mobile switching center 20b is similar to that of a conventional three-way call trunk.

The code conversion circuit 1 converts the code type 1 into a linear code, the code conversion circuit 2 is connected to the input terminal A and converts the code type 2 into a linear code, and outputs the result to the selection circuit 10. . The code conversion circuit 3 is connected to the input terminal B and converts the code type 1 into a linear code, and the code conversion circuit 4 is connected to the input terminal B and converts the code type 2 into a linear code, and the result is sent to the selection circuit 11. Output. The control signal receiving circuit 8 receives, via the control input terminal D, an instruction as to whether the output of the circuit of the present invention is used externally. The synchronization detection circuit 9 is connected to the input terminal A, and the control signal reception circuit 8
While the output signal from the device indicates that the circuit is in use, the sync pattern of the code type 2 signal is detected to determine the code type of the input signal, and the result is selected by the selection circuits 10 and 1.
1 and 12 (described later) are output as selection signals. The selection circuits 10 and 11 select the output signals of the code conversion circuits 2 and 4 when the synchronization detection circuit 9 detects the synchronization pattern, and select the output signals of the code conversion circuits 1 and 3 when the synchronization pattern is not detected. And outputs to the adder circuit 5. The adder circuit 5 adds the two linear codes, and the result is the code conversion circuits 6 and 7
Output to. The code conversion circuit 6 converts the linear code into the code type 1, the code conversion circuit 7 converts the linear code into the code type 2, and outputs the result to the selection circuit 12. A signal from the input terminal A is also input to the selection circuit 12 as shown in the figure. The delay circuit 13 delays the output signal of the control signal receiving circuit 8 for a fixed time. This signal, together with the output signal of the synchronization detection circuit 9, is the selection signal of the selection circuit 12 as shown in the figure. This is the time set by the delay circuit 13 from the time when this circuit receives the instruction to use, 40 m in this embodiment.
Select the signal from input terminal A until [s]
When the sync pattern is not detected, the output of the code conversion circuit 6 is selected. The timing adjustment circuit 14 adjusts the output timing of the output signal of the selection circuit 12 to the external device and sends the signal to the output terminal C. The timing adjusting circuit 15 adjusts the output timing of the signal from the input terminal C to the external device and sends the signal to the output terminals a and b.

The operation when a handover process is performed using the circuit of the present invention during a call between mobile stations will be described below. FIG. 2 shows the path connection at the time of handover. While the mobile station 201 and the mobile station 202 are talking, the mobile station 20
1 moves from the service area of the base station 203 to the service area of the base station 204, the mobile switching center 206
Assigns the radio communication channel of the mobile station 201 and the base station 204, and at the same time, the handover processing circuit 1 of the present invention.
The call path is switched to 00. In this case, the control input terminal D is instructed to be in use, and at the same time, the base station 203 before the handover and the input / output terminals A and a are on the communication path 216, and the base station 204 of the handover destination is on the input / output terminals B and b. In path 217, the base station 205 used by the mobile station 202 in the call is connected to the input / output terminals C and c by the call path 218. As mentioned above, code type 2 is used when calling between mobile stations.
Signal is transmitted, but until the synchronization detection circuit 9 detects the synchronization pattern immediately after switching, that is, until the code type of the signal of the input terminal A can be reliably determined, the delay circuit 13
Causes the selection circuit 12 to select the signal from the input terminal A,
It is sent to the output terminal C.

When the synchronization detection circuit 9 detects the synchronization pattern, the selection circuit 10 selects the output signal of the code conversion circuit 2, and the selection circuit 11 selects the output signal of the code conversion circuit 4 and the selection circuit 12.
Selects the output signal of the code conversion circuit 7. At this time, the signal from the base station 203 is converted into a linear code by the code conversion circuit 2 and input to the addition circuit 5 via the selection circuit 10.
The signal from the base station 204 is converted into a linear code by the code conversion circuit 4 and input to the addition circuit 5 via the selection circuit 11. The signals added by the adder circuit 5 are converted into code type 2 by the code conversion circuit 7 and selected by the selection circuit 1 and the timing adjustment circuit 1.
4, the output terminal C, the call path 218, and the base station 205 to reach the mobile station 202. During the handover process, the idle signal corresponding to silence is output from the base station to which the mobile station has not established a wireless communication channel.
The voice of the base station 2
03, input to the input terminal A via the call path 216,
Immediately after switching, it is input to the input terminal B via the base station 204 and the communication path 217. Therefore, a momentary interruption occurs while the mobile station 201 switches channels.

On the other hand, the voice of the mobile station 202 is transmitted to the base station 20.
5, input to the input terminal C via the call path 218.
The signal input to the timing adjustment circuit 15 is output to the output terminals a and b, so that the mobile station 201 operates the base station 203,
The mobile station 201 is reached no matter which base station 204 has established a radio communication channel. After that, the mobile communication switching center 206, after receiving the wireless communication channel establishment report from the base station 204, switches to the communication paths 219 and 220,
The in-use instruction of the handover processing circuit is released, and the handover processing ends.

When the mobile station 201 moves as described above during a call with a general public subscriber, it is the general public subscriber that is connected to the input / output terminals C and c, and the base stations 203 and 2
Since the signal transmitted between 04 and mobile switching center 206 is code type 1, the only difference is that it operates so as to use the output signals of code conversion circuits 1, 3, and 6.

[0014]

As described above, in the handover processing circuit of the present invention, when a call is made between mobile stations, the signal of code type 2 transmitted to the mobile switching center is temporarily converted into a linear code for addition. Therefore, it is possible to realize the same function as that of the conventional three-way call trunk used in the handover processing between the mobile station and the general public subscriber, and it is possible to reduce the interruption time during the handover.

Further, the conventional handover process has to be executed in consideration of whether the other party talking to the mobile station to be handed over is a mobile station or a general public subscriber. By using the over-processing circuit, there is no need to be aware of it.

[0016]

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention.

FIG. 2 is a block diagram showing an embodiment of path connection at the time of handover.

FIG. 3 is a block diagram showing a first example of conventional path connection at the time of handover.

FIG. 4 is a block diagram showing a second example of conventional path connection at the time of handover.

FIG. 5 is a diagram showing a transmission form between a base station and a mobile switching center.

[Explanation of symbols]

 1-4 Code conversion circuit 5 Addition circuit 8 Control signal reception circuit 9 Synchronization detection circuit 10-12 Selection circuit 13 Delay circuit 14, 15 Timing adjustment circuit 100 Handover processing circuit 201, 202 Mobile station 203-205 Base station 206 Mobile communication Switching office 207-210, 212-220 Call path 211 Three-way call trunk

Claims (1)

[Claims] 1. A first signal for inputting a digital signal of a first code type for encoding or a second code type for compressing and encoding information in order to reduce a transmission rate according to the A-law or the μ-law. , Second and third input terminals, first, second and third output terminals that output the digital signal, and a signal from the first input terminal as an input, and the first code type is linear. A first code conversion circuit for converting to a code; a second code conversion circuit for inputting a signal from the first input terminal to convert the second code type into a linear code; and the first input terminal From the input, the signal of the second code type is put into fixed-length data to form a frame structure together with a synchronization pattern, and the synchronization pattern at the time of serial serial transmission in frame units is detected, Input signal mark A synchronization detection circuit for determining the signal type; a third code conversion circuit for converting the first code type into a linear code by inputting a signal from the second input terminal; A fourth code conversion circuit that receives a signal as an input and converts the second code type into a linear code; the synchronization detection circuit according to a control signal from the outside; and a control circuit that issues an operation instruction to a delay circuit described later, The output signals of the first and second code conversion circuits are input,
A first selection circuit that selects and outputs an input signal in accordance with the sync pattern detection state of the sync detection circuit; and inputs the output signals of the third and fourth code conversion circuits,
A second selection circuit that selects and outputs an input signal in accordance with a sync pattern detection state of the sync detection circuit; an adder circuit that adds linear codes output from the first and second selection circuits; A fifth code conversion circuit, which receives a signal from the circuit and converts a linear code into the first code type, and a signal from the adder circuit, which converts a linear code into the second code type A sixth code conversion circuit; a delay circuit for delaying the signal from the control circuit for a fixed time and outputting the signal; a signal from the first input terminal and an output signal from the fifth and sixth code conversion circuits. A third selection circuit which receives the input, selects an input signal according to the sync pattern detection state of the sync detection circuit and the output signal of the delay circuit, and outputs the output signal of the third selection circuit to an external device. Adjust output timing Then, the first timing adjusting circuit for outputting to the third output terminal and the output timing of the signal from the third input terminal to the external device are adjusted and output to the first and second output terminals. And a second timing adjustment circuit for performing the handover processing circuit.