JPH0391330A - Channel switching control method - Google Patents

Abstract

PURPOSE:To attain changeover without interrupting the communication by sending reception synchronization information of an original radio equipment in communication in a base station to a destination radio equipment of a new channel, and synchronizing in a timing represented in the synchronization information. CONSTITUTION:When it is judged that the changeover of a radio channel is required and a changeover destination radio channel is decided, a parameter of reception synchronization stored in a bit/frame synchronizing circuit of an original radio equipment 19 is outputted to a control section 21. Then the control section 21 informs the parameter to a bit/frame synchronizing circuit of a changeover destination radio equipment 20. The original changeover radio channel in communication at present designates the changeover destination radio channel to a mobile station 17 and the mobile station 17 uses an idle time slot to changeover the radio channel. The bit/frame synchronizing circuit of the radio equipment 20 applies decoding and starts the reception in a timing of a clock recovered from the parameter of the bit/frame synchronizing circuit of the radio equipment 19 via the control section 21. Finally the original changeover radio channel is released. The mobile station 17 makes communication with the radio equipment 20 without interrupting the communication with the radio equipment 19.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of switching base station radios without momentary interruption during communication in a digital mobile communication system.

[Conventional technology]

In mobile communication systems, intra-zone channel switching may be performed when a wireless channel during communication becomes unusable due to interference or the like.

Intra-zone channel switching refers to switching the radio channel within the base station of the radio zone, and is usually performed by switching the radio at the base station and by switching the channel at the mobile station.

In digital mobile communication systems, when switching radio channels, synchronization must be established between the switching source radio device and the mobile station in order for the mobile station to communicate on the switching destination radio channel.

Conventionally, mobile stations in digital mobile communication systems transmit signals in accordance with the 7-frame timing of signals from base stations, but at this time, due to signal delay in the radio section, mobile stations near the base station and mobile stations far away The frame timing of the mobile station transmission signal received by the base station is different for the mobile station located in the base station.

Therefore, when starting communication, the mobile station detects the frame timing of the base station with which it is trying to communicate, ■ the mobile station transmits a synchronization signal to the base station at the timing of the slot given to it, and ■ the base station It receives a synchronization signal from the mobile station and detects the 7-frame timing of the mobile station's transmission signal.

This control was carried out.

The base station can detect the frame timing of the mobile station transmission signal by performing the control described above, but in addition, during communication, it stores the frame timing of the corresponding slot of the previous TDMA frame and uses that timing. Another method is to receive the signal at

[Problem to be solved by the invention]

In the conventional system, a mobile station first receives a signal from a base station to establish downlink reception synchronization, and then transmits an uplink signal based on the timing.

The base station establishes uplink reception synchronization from the uplink signal of the mobile station, but in this case, synchronization pull-in starts from the initial phase of the free-running clock, so 10 bits or more are required to establish bit synchronization, so at least one slot is required. The disadvantage was that there was always a signal dropout.

FIGS. 9(a) and 9(b) are diagrams explaining such signal loss. In the figures, 5IS2, 83, etc. represent slots, and the alphabetic character A represents free time, and B represents a synchronization signal such as a preamble signal.

In addition, (a) and (b) both show the case of switching in the same slot (from Sl to 81), and the mobile station switches the wireless channel within the free time slot indicated by the letter A. Change.

In the case of Figure (a), after the mobile station switches channels, a synchronization signal such as a Brian 3-pull signal, indicated by the alphabet B, is inserted, so that among the signals received by the switching source radio, Information on the slot (slot indicated by the alphabet C) Sl is missing.

In the case of (b) in the same figure, in order to synchronize with the switching source radio device after switching,
The first 10 bits of information are required. Therefore,
Since the any word before the information signal for that slot is missing, the information for this slot becomes unusable.

In view of such conventional 8M points, the present invention has the so-called
It is an object of the present invention to provide a channel switching control method that can perform intra-zone channel switching without interrupting communication.

[Means to solve the problem]

According to the invention, the above objects are achieved by the means specified in the claims.

That is, the present invention is applicable to a small zone digital mobile communication system in which a switching center and a base station are connected via a communication line, and the switching center is connected to four mobile stations via the base station. Equipped with a function to set the reception synchronization timing from the outside of the radio and to notify the reception synchronization timing setting value of the base station i#lfi to the outside of the radio. This is a channel switching control method in which the reception synchronization timing setting value is set to the switching light/heat tag, and the switching source wireless device starts receiving at that timing.

[For production]

The present invention sends received synchronization information of a so-called switching source radio device communicating within a base station to a switching source radio device of a new channel, and makes it possible for the switching source radio device to synchronize at the timing instructed by the synchronization information. The main feature differs from the conventional technology in that it is possible to establish reception synchronization with the switching source wireless device without interrupting communication, and to switch without interruption.

[Example] FIG. 1 shows an example of a system configuration for implementing the present invention.

In FIG. 1, 1 represents a mobile station, 2 represents a base station, and fl and f2 represent radio frequencies.

The base station 2 has a function (switching function) of setting a communication path switch and switching the line between the base station base radio and the general switching network.

FIG. 2 is a diagram explaining the TDMA method,
The case of 3-channel TDMA is shown.

In the same figure, al-a3, bl-b3
, cl~c3. di to d3 each indicate the type of signal, and Sl, S2 . S3 each represents a time slot.

In addition, in the transmission signal of the base station in the same figure, each frame of the first to third signals is time-compressed, and a unique word (UWI is the identification information of the first slot) is added as slot identification information. It is multiplexed. Moreover, the received signal of the base station is the first to third mobile station transmitted signals arranged as they are on the time axis.

FIG. 3 is a diagram showing an example of the configuration of a base station radio device (transmission/reception unit) when a 3-channel TDMA system is used, in which 3 is a base station, 4-1 to 4-n are radio devices, and 5- 1 to 5-n are bit/frame synchronization circuits, 6-1 to 5-n are encoding circuits, and 7-1 to ? -n is a decoding circuit, 8-1 to 3-n are modulation circuits, 9-1 to 9-n are demodulation circuits, 10 is a reference clock generation section, and 11 is a control section.

As shown in the figure, the encoding circuit 6-1 or 6-n and the decoding circuits 7-1 and 7-n each have three communication paths between them and the communication path section. 3 channel T
It is shown that it is a DMA method.

The encoding circuits 6-1 to 6-n time-compress each of the three signals input from the communication path section and output them as ITDMA7 frames. In the decoding circuits 7-1-7-n, each slot in the ITDMA 78-frame is time-expanded, divided into three signals, and outputted to the communication path section.

The modulation circuits 8-1 to B-n convert signals input manually from the corresponding encoding circuits into signals suitable for transmitting digital signals, and transmit the converted signals to the mobile station as transmission signals.

Demodulation circuits 9-1 to 9-n demodulate the received signal from the mobile station and input it to the corresponding decoding circuit.

This signal is time-expanded and divided into individual signals as described above, and then sent to the communication path section.

The bit/frame synchronization circuits 5-1 to 5-n are configured so that the synchronization state can be set as a parameter and the parameter can be outputted.

For example, the phase difference between the reference clock and the received recovered clock can be output as a parameter. Furthermore, it is possible to externally provide a phase difference using this as a parameter and perform clock phase control using this as an initial state.

FIG. 4 is a diagram showing an example of the configuration of a bit/frame synchronization circuit, in which 12 is a bit/7 frame synchronization circuit, 13 is a phase shift circuit, 14 is a phase comparison circuit, 15 is a control circuit, and 16 is a diagram showing an example of the configuration of a bit/frame synchronization circuit.
represents an averaging circuit.

In the bit/frame synchronization circuit 12 shown in FIG.
The phase shift circuit 13 delays the reference clock by the phase difference parameter notified from the control circuit 15 and sends it to the decoding circuit as a recovered clock.

Further, the reproduced clock is sent to a phase comparison circuit, the phase is compared with the detected waveform of the a-key signal, and the comparison result (phase difference) is input to the averaging circuit in bit units. The averaging circuit averages the results (phase differences) over a predetermined number of bits.

Then, the average result (phase difference) is notified to the control circuit 15. In this way, the bit/frame synchronization circuit 12
are a control circuit 15, a phase shift circuit 13, a phase comparison circuit 14,
The averaging circuit 16 is in a constant loop state, and the parameters stored in the control circuit 15 are updated.

FIG. 5 shows signal waveforms for explaining the bit/frame synchronization circuit.

When the control circuit receives the phase difference parameter a from the control section, it sends the parameter to the phase shift circuit. Then, the phase shift circuit delays the reference clock shown in (,) by the parameter α and sends it to the decoding circuit as the recovered clock shown in (b), and the decoding circuit receives the demodulated signal at the timing of the recovered clock. and decrypt it.

That is, after the wireless channel is switched, the signal (detected waveform shown in (C)) received by the switching source radio device matches the timing of the recovered clock shown in (b).

This is because the mobile station is slave-synchronized with the clock and frame of the downlink signal from the base station as mentioned above, and the mobile station does not change the transmission clock timing during intra-zone switching, so the old transmitter's reception clock It is assumed that once the timing is set on the new transmitter, synchronization will be established from the beginning.

11- That is, the clocks are synchronized because the reference clocks are located within the same base station.

Switching source # is currently communicating! The reception synchronization of the machine is maintained in the control section. By informing the switching source radio device of the reception synchronization (phase difference parameter α), the switching source radio device receives at that timing (the timing of the recovered clock delayed by the phase difference parameter α).

Therefore, switching light and heat #I4$! Then, there is no need to resynchronize, so synchronization is established from the first slot and reception is possible.

Therefore, in the present invention, when performing channel switching, it is possible to directly specify the parameter values of the switching source wireless device to the switching source wireless device, so that synchronization can be established from the first slot after channel switching.

In this way, by enabling high-speed synchronization establishment, intra-zone channel switching can be performed without momentary interruption.

The procedure for intra-zone channel switching is shown below.

First, in the example of the system configuration shown in FIG.
Consider the case where the wireless channel is switched to 2.

When it is determined that wireless channel switching is necessary and the switching destination wireless channel is determined, the reception synchronization parameters stored in the bit/frame synchronization circuit of the switching source wireless device are output to the control unit, and the control unit outputs the reception synchronization parameters stored in the bit/frame synchronization circuit of the switching source wireless device. /Input (notify) to the frame synchronization circuit. In the switching source radio channel currently in communication, the switching destination radio channel is specified to the mobile station. Based on the designation, the mobile station switches the radio channel in an empty time slot (the empty ufMl slot will be described later). The bit/frame synchronization circuit of the switching source radio device decodes and starts reception at the timing of the clock reproduced from the parameters input from the bit/frame synchronization circuit of the switching source radio device via the control unit. Finally, the switching source wireless channel is released.

By performing the above-described control, the mobile station can establish synchronization and communicate with the switching source wireless device without interrupting communication with the switching source wireless device.

FIG. 6 is a diagram illustrating the free time slot.

In the figure, for example, the switching source channel (frequency f1
When switching from slot 1) to the switching destination channel (frequency f2, slot 2), the mobile station switches the channel in the dark of the vacant time slot of the mobile station transmission signal.

Note that when switching intra-zone channels, after determining the switching destination wireless channel, multi-connecting the communication path switch both upstream and downstream makes it easier to switch channels without momentary interruption.

The above multi-connection will be explained below.

FIG. 7 is a diagram showing an example of a line configuration for explaining multi-connection, in which 17 is a mobile station, 18 is a wireless base station, 19.20 is a wireless device (transmission/reception unit), and 21 is a control unit. , 22 represent a communication path switch. Radio 19
．． 20, for example, one is the switching source and the other is the switching destination.

Furthermore, FIG. 8 is a diagram showing an example of the configuration of the radio device, in which 23 is the radio device, 24 is a control section, 25 is a modulation circuit, and 2
6 is a demodulation circuit, 27 is a bit/frame synchronization circuit, 28
7 is a framing circuit, 29 is a deframing circuit, 30 is
31 is a reception state measuring circuit, 31 is a speed conversion circuit, 32 is a bit manipulation circuit, 33 is an encoding circuit, 34 is a speed conversion circuit,
35 represents a decoding circuit. When switching radio channels, the communication path switch 22 shown in FIG. 7 performs multiple connections for both uplink and downlink.

In a multi-connection, the information signal is sent to both the switching source radio and the switching source radio. Then, the switching source wireless device also transmits the signal received from the channel switch 22 to the mobile station (multi-transmission). That is, multi-transmission here means that the information signal from the general switching network is transmitted to both the switching source radio device and the switching source radio device in the communication path switch 22. Then, the switching source wireless device also transmits the signal received from the communication path switch to the mobile station.

In FIG. 8, a reception state measuring circuit 30 measures the state of the received signal from the mobile station according to a command from the control section 24 and reports it to the control section 24. If it is determined from the measured reception signal state that reception has not been received, the corresponding portion of the signal is replaced with 0 by a command from the control unit 24.

On the other hand, when an information signal is transmitted from one wireless channel by operating the bit manipulation circuit 32 and reception state measurement circuit 30 when switching channels, the information signal is always transmitted from the other wireless channel.
000” is sent, so switch the communication path switch 22.
An operation is performed to reproduce this signal by calculating the logical sum of both signals, and this is called multi-reception.

At the switch, the switch is switched at the time when the signal replaced with O by the switching source radio device is transmitted and at the same time a certain level of the signal transmitted from the switching source radio device is detected. By performing multi-reception, the channel switch does not need to switch at the same time as the mobile station switches channels.

Therefore, the configuration is such that there is no instantaneous interruption even when the mobile station switches channels.

As another embodiment, the control unit is provided with a memory function for storing reception synchronization parameters corresponding to all radio equipment in the base station, and when switching radio channels, the control unit sends the switching source radio equipment to the switching source radio equipment. There is also a method of specifying parameters for reception synchronization.

In addition, all wireless devices in a base station are connected like a mesh network, and when switching wireless channels, the bit/frame of the switching source wireless device is
There is also a method in which the synchronization circuit directly sets the stored reception synchronization parameters to the bit/frame synchronization circuit of the switching source radio device.

In the above description of the embodiment, an example in which channel switching is performed due to interference or the like has been described. However, the present invention is applicable to cases in which a mobile station moves between sectors and performs channel switching between sectors when a sector zone configuration is used. It can also be applied to

In other words, the sector zone configuration is such that wireless zones within the same base station are sectorized, and the switching source radio device and the switching source radio device are located within the same base station, and the reference clock is also located within the same base station. A switching control method can be applied.

Further, although the case where the communication path switch is installed in the base station has been described, the configuration may be such that the communication path switch is installed in the switching center.

〔Effect of the invention〕

As explained above, according to the method of the present invention, when performing intra-zone channel switching, it is possible to establish high-speed synchronization, and the communication with the switching source wireless device can be established without interrupting the communication currently in use. This has the advantage of being able to establish synchronization and switch wireless channels.

4,

[Brief explanation of drawings]

FIG. 1 is a diagram showing an example of a system configuration for implementing the present invention, FIG. 2 is a diagram explaining the TDMA method, and FIG.
The figure shows base station heat # when using 3-channel TDMA system.
[A diagram showing an example of the configuration of the machine, FIG. 4 is a diagram showing an example of the configuration of the bit/frame synchronization circuit, FIG. 5 is a diagram showing signal waveforms for explaining the bit/frame synchronization circuit, and FIG. 6 FIG. 7 is a diagram illustrating an example of a circuit configuration to explain multi-connection, FIG. 8 is a diagram illustrating an example of a radio device configuration, and FIG. 9 is a diagram illustrating a signal loss. FIG. 1.17 ...mobile station, 2,318
...Base station, 4-1 to 4-n19
．． 20 ... Radio equipment, 5-1 to 5-
n...Bit/7 frame same wi circuit, 6-
1 to 6-n... Encoding circuit, 7-
1 to 7-n...Decoding circuit, 8-1
~8-n25...Modulation circuit, 9
-1 to 9-n l 26 ... Demodulation circuit,
10...Reference clock generation section, 1
1...Control unit, 12, 27.
...Bit/frame synchronization circuit, 1
3... Phase shift circuit, 14...
Phase comparison circuit, 15...Control circuit,
16 ・・・・・・Averaging circuit, 21.24
...Control unit, 22 ...Call path switch, 28 ...7 framing circuit, 29 ...Deframing circuit, 30 ......・Reception status measurement circuit, 31... speed conversion circuit,
32...Bit manipulation circuit, 3
3...Encoding circuit, 34...Speed conversion circuit, 35...Decoding circuit

Claims (1)

[Claims] In a small zone digital mobile communication system in which a switching center and a base station are connected by a communication line and the switching center is connected to a mobile station via a base station, the reception synchronization timing is input to the base station radio from outside the radio. It also has a function to notify the reception synchronization timing setting value of the base station radio to the outside of the radio, and when switching radios within the same base station, the reception synchronization timing setting value of the switching source radio to the switching destination radio. A channel switching control method characterized in that the channel switching control method is characterized in that the switching destination radio equipment starts receiving at that timing.