JPH06164575A - Modification information transmitting system for information channel - Google Patents

Abstract

PURPOSE:To efficiently transfer the modification information of an information channel between a radio base station and a switch-board in an exchange system which stores a digital cordless terminal. CONSTITUTION:This modification information transmitting system is to hold the digital cordless terminal 1, and transmission between the switchboard 3 and the radio base station 2 is executed by a layer 1 frame decided to consist of two B-channels in which an information bit is inserted, one D-channel in which a control bit is inserted, and one K-channel in which a house keeping bit is inserted. Then, the data of the K-channel is made into a multi-frame in which one frame is constituted of plural layer 1 frames. The modification information of the information to be transferred between the switchboard 3 and the digital cordless terminal 1, e.g. error information or VOX information is transmitted by being inserted into a predetermined position of the multi-frame of the K-channel.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of transmitting information for modifying an information channel between a wireless base station and a base station interface circuit of a switch in a switching system accommodating a digital cordless terminal.

[0002]

2. Description of the Related Art In recent years, for example, in offices and the like, an increasing number of cases are being provided with extension terminals (for example, telephones) housed in a private branch exchange for each employee in order to improve work efficiency. As described above, a cordless terminal having excellent portability is also considered as a terminal provided to each employee. Here, it is considered to employ a digital transmission method, which has better confidentiality than the analog transmission method and enables the cordless terminal to be small and lightweight, so that the transmission between the digital cordless terminal and the wireless base station can be prevented. TDMA (Time Division Multiple Acc
ess) method and TDMA / TDD (Time Division Multip
le Access ・ Time Divison Duplex) method is proposed.

In a private branch exchange system adopting these methods, it is desired to synchronize radio base stations. This is because, when the cordless terminal moves across the service zones of the wireless base stations, communication may be interrupted if the TDMA frames are not synchronized between the wireless base stations before and after the movement.

In the document “Japanese Patent Application No. 3-97402, Specification and Drawings”, a TDMA frame synchronization signal is sent from a switch to a radio base station by a K channel separate from an information channel (for example, a voice signal) and a control channel for call control. It is disclosed that transmission is performed using a channel (housekeeping channel) to synchronize radio base stations and prevent instantaneous interruption.

As described above, in the exchange system accommodating the digital cordless terminal, between the exchange and the radio base station,
There is a need for transmission of information that was not present in conventional exchange systems that housed wired terminals.

[0006]

By the way, in the exchange system accommodating the digital cordless terminal, the TD
Higher quality and service performance can be realized by exchanging information other than the MA frame synchronization signal, which is not present in the conventional exchange system accommodating the wired terminal, between the wireless base station and the exchange.

[0007] Such information includes, for example, error information, so-called VOX information, and other information channel (traffic channel: voice signal) modification information. The modification information of these information channels will be described below.

In mobile communication, a high-efficiency voice coding system with a low bit rate, which is different from the conventional wire network, is used in order to improve the frequency utilization efficiency on the wireless line. If the low bit rate information is transmitted between the radio base station and the exchange, the information channel that can be carried per line can be increased.
In this case, low bit rate encoded data (voice data) and a standard encoding method in a wired network (for example, μ-law PC
The exchange is provided with a transcoder for converting between encoded data according to M).

In a switching system using the TDMA / TDD system in which the access method on the wireless line is 5 ms, an information channel is transmitted and received in bursts every 5 ms between the wireless base station and the cordless terminal, and the unit of error detection is also this. Every burst block. On the wireless line, the transcoder controls by whether it is the burst block in which the error occurred or whether it was received normally,
For example, by using the immediately preceding data in the case of an error, it is possible to reduce the voice quality deterioration due to the error on the wireless line.

Therefore, by transmitting the error information on the wireless line from the wireless base station to the exchange, high quality communication can be ensured.

Further, in mobile communication, battery saving of a cordless terminal is an important issue. As one of this battery saving technology, "VOX control"
There is a technique called "stopping the operation of a voice coder and a transmitter when detecting silence during a call." The VOX control side (cordless terminal or exchange side) transmits a burst containing background noise before stopping the voice coder or transmitter, and the receiving side performs background noise during VOX control (during silent periods). Avoiding the unnatural feeling by playing.

By doing so, the power consumption of the cordless terminal can be suppressed, the battery life of the cordless terminal can be extended, and the service can be improved.

In any case, error information and V
It becomes necessary to transmit information channel modification information, such as OX information, between the exchange equipped with the transcoder and the radio base station, for example, in a burst cycle. In the past, a method for efficiently transmitting this information has been proposed. There was nothing to disclose.

The present invention has been made in consideration of the above points, and in a switching system accommodating a digital cordless terminal, modification information of an information channel can be efficiently exchanged between a radio base station and a switching device. It is intended to provide an information channel modification information transmission method.

[0015]

In order to solve such a problem, in the modified information transmission system of the information channel according to the present invention, a digital cordless terminal is accommodated, and an information bit is provided between the exchange and the radio base station. 2 B channels into which a control bit is inserted and 1 D channel into which a control bit is inserted.
In a switching system in which a layer and a K channel in which housekeeping bits are inserted are defined to be transmitted in a layer 1 frame, data of the K channel is configured by a plurality of layer 1 frames into one frame. In addition to making it into a multi-frame, the modification information of the B channel is inserted at a predetermined position of the multi-frame of the K channel and transmitted.

Here, it is preferable to divide two predetermined B channels so that the number of divided B channels is equal to the number of information channels in one transmission frame on the wireless line.

Further, it is preferable that the modification information of the information channel inserted in the multi-frame of the K channel is error information indicating whether or not the information channel data is in error.

Further, it is preferable that the modification information of the information channel, which is inserted into the multi-frame of the K channel, is VOX information for instructing to replace the data of the information channel with the background noise data when there is no sound during a call.

Furthermore, it is preferable that the K-channel multi-frame indicates the division of the same information channel distributed to the B-channels of a plurality of layer 1 frames.

Further, it is preferable that the K-channel multi-frame synchronization information is also synchronization information for synchronizing the radio base stations.

[0021]

The present invention accommodates a digital cordless terminal, and two B channels in which information bits are inserted and one D channel in which control bits are inserted between the exchange and the radio base station. And a single K channel into which housekeeping bits are inserted, which is premised on a switching system for transmitting in a layer 1 frame.

In the exchange system accommodating such a digital code terminal, the modification information of the information channel is
By transmitting between the exchange and the radio base station, the service can be improved and the call quality can be improved. Here, since there are a plurality of cordless terminals accommodated by one radio base station, the amount of modification information also increases. In order to efficiently transmit such a large amount of modification information according to the above-described layer 1 frame format configuration, in the present invention,
The data of the K channel is converted into multi-frames that form one frame by a plurality of layer 1 frames, and
The modification information of the B channel is inserted and transmitted at a predetermined position of the multiframe of the K channel.

Here, the number of B channels in a predetermined layer 1 frame format, that is, 2
If the number of B channels is not equal to the number of information channels in one transmission frame on the wireless line, the conversion process between the layer 1 frame and the transmission frame on the wireless line becomes complicated. Therefore, in such a case, 2
It is preferable that the B channels are divided and the number of divided B channels is made equal to the number of information channels in the transmission frame on the wireless line.

If the modification information of the information channel inserted in the multi-frame of the K channel is error information indicating whether or not the information channel data is an error, a process corresponding to this can be executed to improve the communication quality. It can be increased, which is preferable.

Further, if the modification information of the information channel, which is inserted in the multi-frame of the K channel, is the VOX information for instructing to replace the data of the information channel with the background noise data when there is no sound during the call, the digital cordless terminal. This is preferable because it can realize a long battery life.

Furthermore, if the K-channel multi-frame indicates the division of the same information channel distributed to the B-channels of a plurality of layer 1 frames,
This is preferable because it facilitates the conversion process between the layer 1 frame and the transmission frame on the wireless line.

Further, if the K-channel multi-frame synchronization information is also synchronization information for synchronizing the radio base stations, it is not necessary to exchange dedicated information for synchronizing the radio base stations. preferable.

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 2 shows a schematic overall configuration of a switching system to which the information channel modification information transmission system of this embodiment is applied.

In FIG. 2, this switching system includes a digital cordless terminal 1, a radio base station 2 for communicating with the cordless terminal 1 according to, for example, the TDMA / TDD system, and a cordless terminal accommodating the radio base station 2. It is composed of an exchange 3 that performs exchange processing so that communication between the two can be performed. When viewed from the path of the information channel (traffic channel: voice signal, for example), the exchange 3 mainly includes a base station interface circuit (cordless subscriber circuit) 11 and a main switch (for example, a time division switch).
It is composed of twelve. Practically, cordless terminal 1
There is also a switch for movement tracking of the above, but since it is not directly related to the features of this embodiment, illustration and description thereof will be omitted. The base station interface circuit 11 includes a base station interface unit (layer 1 processing unit) 21 and a transcoder 22.

The radio base station 2 is a digital cordless terminal 1 located in a microzone assigned to itself.
Is a base station that exchanges information channels and control channels by multicarrier TDMA, and is accommodated in the base station interface circuit 11 of the exchange 3. That is,
The wireless base station 2 converts the transmission format (TDMA frame format) for the wireless channel and the transmission format (layer 1 frame format) for the base station interface circuit 11 as described later. The wireless base stations 2 are arranged at predetermined intervals so that communication can be performed even when the cordless terminal 1 moves between zones during communication.

The exchange 3 is an exchange that realizes digital mobile communication by multicarrier TDMA. The base station interface circuit 11 in the exchange 3 is an interface circuit that accommodates a plurality of radio base stations 2 and exchanges a layer 1 frame of 2B + D + K with the radio base station 2 as described later. In the case of this embodiment, a time division direction control transmission method (ping-pong transmission method) is applied as a transmission method between the base station interface circuit 11 and the radio base station 2. That is, the base station interface circuit 11 transmits a burst including a layer 1 frame to the radio base station 2, and when the radio base station 2 finishes receiving the burst, transmission / reception is switched and the radio base station 2 is transmitted to the base station interface circuit 11. Send a burst containing a Layer 1 frame.

The main switch 12 is a switch that forms a communication path between accommodated terminals. The main switch 12 is connected to a central processing module (not shown),
Switching processing is performed in a time division multiplex manner according to a connection control instruction from the central processing module.

The base station interface circuit 11 interfaces the radio base station 2 and the main switch 12. The transcoder 22 is a low bit rate voice coded data (ADPCM: 32 kb / s) peculiar to mobile communication.
Standard speech coded data in the switch (μ-law PCM: 6
4 kb / s) or vice versa, the standard voice coded data in the exchange is converted into low bit rate voice coded data peculiar to mobile communication. In the case of this embodiment, between the wireless base station 2 and the base station interface circuit 11, it is assumed that the data according to the voice coding method between the wireless base station 2 and the cordless terminal 1, for example, 32 kb / s ADPCM data is transmitted as it is. Therefore, the transcoder 22 is required. If the low bit rate voice encoding method is transmitted to the base station interface circuit 11 as described above, the number of communication channels that can be carried per line becomes larger than that in the case where the wireless base station 2 performs conversion. Base station interface unit 21
Is an interface that is connected to the wireless base station 2 by wire and transmits / receives a layer 1 frame to / from the wireless base station 2.

In the case of this embodiment, the TDMA frame period is 5 ms, the burst period is 125 μs, and ping-pong transmission with a period of 125 μs is performed between the base station interface circuit 11 and the radio base station 2.

FIG. 3 shows a layer 1 frame (layer) between the base station interface circuit 11 and the radio base station 2 developed to economically accommodate a terminal having a 2B + D interface structure (for example, ISDN basic rate). 1 shows the basic format configuration of one interface). The structure of the layer 1 frame includes two B channels (64 kb / s) into which user information (voice / data) is inserted and a D channel (16 kb / s) into which control information is inserted.
K channel (8 kb /
s), the frame synchronization and ping-pong monitoring bit F / P and the DC balanced bit DC are added to the information bits formed by these channels.

FIG. 4 shows an access method (TDMA frame structure) on the wireless line in the exchange system according to this embodiment.

In the case of this embodiment, one radio base station 2
Is capable of simultaneously accessing 4, 8, or 16 cordless terminals 1. For example, if the transmission rate with the cordless terminal 1 is 32 kb / s, a maximum of 4 cordless terminals 1 can be accommodated, and if the transmission rate is 16 kb / s, a maximum of 8 cordless terminals 1 can be accommodated. 8 kb / s
In that case, a maximum of 16 cordless terminals 1 can be accommodated.
In order to comply with any of these, the downlink direction from the wireless base station 2 to the cordless terminal 1 and the cordless terminal 1
1 for each uplink direction from the wireless base station 2 to the wireless base station 2.
Six slot numbers are defined. In any case, the wireless line between the wireless base station 2 and the cordless terminal 1 is defined to transmit a TDMA frame composed of four slots by ping-pong transmission. Here, 625 μs is allocated to one slot, and 160 bits can be inserted as an information channel (traffic channel) therein.

FIG. 5 shows a base station interface circuit 11-
3 shows a format configuration of a layer 1 frame (layer 1 interface) between the radio base stations 2 in this embodiment. The format configuration of this embodiment also respects the basic format configuration shown in FIG. But,
It has four B channels into which information bits are inserted.
That is, the B channel in the basic format has two 8-bit B channels, but in the case of this embodiment, it has four 4-bit B channels. These four B channels B1, B2, B3, B4
Correspond to the four slots (TDMA frame slot numbers in FIG. 4) in the wireless line access system in a one-to-one correspondence. That is, since the low bit rate voice coded data (ADPCM data) on the wireless line in the switching system of this embodiment is 32 kb / s, the B channel in the basic format is decomposed into 32 kb / s × 4 channels. ing.

By the way, in the conventional accommodation of wired terminals, the K channel bit of the layer 1 frame is used only for signal transmission for the purpose of maintenance of the interface requiring the loopback test in the upstream direction, and for the downlink. Regarding the direction, it was used only for transmitting the polling signal of the terminal. In this embodiment, this K
It was decided to use the channel bit for modifying the information channel. In this example, 160 layers 1
The K channel bits of the frame (see FIG. 5B) form a K channel multiframe.

FIG. 6, FIG. 1 and FIG. 7 are diagrams for explaining the multiframe structure of the K channel in the upstream direction.

In FIG. 6, four slots each containing an information channel of 160 bits each have a length of approximately 2.5 ms.
The upstream TDMA frame is transmitted to the wireless base station 2 every 5 ms period. The radio base station 2 uses this TD
The data of the information channel of each slot of the MA frame is
4 B channels of layer 1 frame B1, B2, B
3 and B4, but as shown in FIG.
It is assumed that the first slot data of the DMA frame is inserted into the B1 channel, the second slot data is inserted into the B2 channel, the third slot data is inserted into the B3 channel, and the fourth slot data is inserted into the B4 channel. Here, since the data of one slot is 160 bits and each B channel of one layer 1 frame is 4 bits, 4
16 in 1 slot with 0 layer 1 frames
0 bit data can be sent. Since one layer 1 frame is 125 μs, the time required to transmit 40 layer 1 frames is 5 ms.
Since it matches the frame cycle, as shown in FIG. 6, the slot data relating to the next TDMA frame can be immediately inserted into the layer 1 frame and transmitted. As shown in FIG. 4 and FIG. 6 described above, four TDMA frames make one cycle of the slot, so that the number of layer 1 frames is 160 in the end. Therefore, as described above, the K channel multiframe is configured by 160 K channel bits. As described above, since one bit of K channel data is transmitted for each layer 1 frame having a period of 125 μs, the K channel has a transmission capacity of 8 kb / s.

In the upstream direction, the bit number in the multiframe is defined for such 160 K channel bits as shown in FIG. That is,
The K channel bit in the layer 1 frame that first includes the information channel of the first slot of the first TDMA frame is set to bit number 5, and thereafter, it is incremented by 1 for each layer 1 frame.

FIG. 1 is an enlarged view of a part of the period shown in FIG. 6, and also shows the structure of a K channel multiframe. Here, 160 K channel bits forming one multi-frame are divided into five,
Four of the five K channel bits are allocated for modification of the information channel of a certain slot, and the remaining one bit is allocated for control of each radio base station. At present, since there is error information and VOX information as the modification information of the information channel, in this embodiment, 2 bits out of 4 bits are used and the remaining 2 bits are empty bits (reserved bits).
Further, among the bits allocated for control of each radio base station, every 20 bits constitute a multiframe synchronization pattern, and in the case of this embodiment, other bits are empty bits (reserved bits). .

When the slot relating to the VOX is inserted in the control information of the TDMA frame, the radio base station 2 receives the VOX control K corresponding to the slot.
Turn on the channel bit. In addition, the wireless base station 2
The error detection process of the information channel of the TDMA frame is executed, and when an error is detected, the K channel bit for error control corresponding to the slot is turned on.

FIG. 7 shows allocation of all 160 K channel bits constituting one multiframe. As shown in FIG. 7, in the case of this embodiment, the modification information of the information channel of the same slot is repeated twice with a 20-bit interval. here,
Bit numbers are 1, 21, 41, 61, 81, 101, 1
Since the multi-frame synchronization pattern consisting of 21 and 141 bits is "10100101", in the multi-frame configuration in which the modification information of the information channel of the same slot is repeated twice with 20 bits apart, it is not the position of the intended multi-frame synchronization pattern. The same pattern as this does not occur.

A base station interface circuit 1 to which multi-frame upstream K channel data composed of 160 layer 1 frames is sent.
The transcoder 22 in No. 1 monitors the multi-frame synchronization pattern by the built-in frame synchronization detection circuit to establish synchronization, determines the content of the K channel bit based on the bit number, and is inserted into the B channel. If the data is in error, it is muted or replaced with the immediately preceding data, for example. If no data is inserted in the B channel and the K channel bit indicates VOX, the background noise data already received. Or replace it with. Alternatively, the K channel bit may be monitored by the layer 1 processing unit 21 and the control processor (not shown) may be notified so that the control processor controls the operation of the transcoder 22.

FIG. 8 and FIG. 9 are diagrams for explaining the multi-frame structure of the downlink K channel.

The K-channel multiframe structure in the downlink direction is almost the same as the above-mentioned multiframe structure in the uplink direction, and the different points are as follows.

As shown in FIG. 8, the difference is that the exchange 3 side defines the number of the K channel bit in the multi-frame based on the system clock. This is, of course, a different point. In addition, as shown in FIG. 9, some of the K channel bits for controlling the radio base station 2 are
This is a point used for transmitting polling information of the wireless base station 2. Further, the exchange 3 sends a multi-frame synchronization pattern synchronized with each radio base station 2 based on the fact that the multi-frame synchronization pattern has a cycle of 20 ms, which is the same as one cycle of the TDMA frame. The point is that the synchronization pattern is transmitted to each radio base station 2 as a TDMA frame synchronization signal.

K in the downward direction of such a multi-frame
The radio base station 2 to which the channel data is sent monitors the multi-frame synchronization pattern by the built-in frame synchronization detection circuit and establishes synchronization. Then, the multi-frame synchronization pattern is recognized as a TDMA frame synchronization signal to form and transmit a TDMA frame. At this time, if the K channel bit indicates that the data inserted in the corresponding B channel is an error or is a VOX, the fact is directly inserted or processed in the control information in the TDMA frame. Do it or insert it.

According to the above-mentioned embodiment, the data of the K channel is converted into a multi-frame which is composed of a plurality of layer 1 frames, and the modification information of the information channel is set at a predetermined position of the multi frame of the K channel. Since the information channel modification information is inserted and transmitted, the information channel modification information can be efficiently transmitted. as a result,
Various services using this modification information can be provided, and the call quality can be improved.

For example, if the decoration information is error information,
Muting or replacing with the immediately preceding data can improve the call quality, and if the modification information is VOX information, the battery consumption of the cordless terminal can be suppressed and natural background noise can be provided.

Further, according to this embodiment, while respecting the basic format of the layer 1 frame (without changing the transmission rate), the number of B's corresponding to the number of information channels on the radio line is increased.
Since the layer 1 frame is configured to have the channel, the low bit rate encoded data on the wireless line can be efficiently transmitted between the wireless base station and the exchange together with the modification information described above.

Further, according to the above-mentioned embodiment, since the multi-frame of the K channel indicates the division of the same information channel distributed to the B channels of the plurality of layer 1 frames, the code conversion and the decomposition of the information channel data can be performed. Processing such as assembling of information channel data is easy.

Furthermore, according to the above embodiment, since the synchronization information of the multi-frame of the K channel is also the synchronization information of the TDMA frame for synchronizing the plurality of radio base stations 2, the synchronization information of the TDMA frame is collected. Is unnecessary, and the configuration can be simplified.

The present invention is not limited to the transmission of the information channel having the transmission rate in the above embodiment. Also, the digital code terminal is not limited to the telephone. Further, the present invention can be applied to both the private branch exchange system and the central office exchange system.

Further, in the future, the present invention can also cope with the case where new modification information needs to be transmitted in order to improve service and call quality.

[0059]

As described above, according to the present invention, a digital cordless terminal is accommodated, and two B channels into which information bits are inserted and control bits are provided between the exchange and the radio base station. In a switching system that transmits in a Layer 1 frame that is defined to include one D channel in which the K is inserted and one K channel in which the housekeeping bits are inserted, the K channel data is transmitted in a plurality of layers. One frame is made into multiple frames, and the modification information of the information channel exchanged between the exchange and the digital cordless terminal is inserted into a predetermined position of the K channel multiframe and transmitted. Therefore, information channel modification information can be efficiently exchanged between the wireless base station and the exchange.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing allocation of K channel bits in an upstream direction in association with a B channel according to an embodiment.

FIG. 2 is a block diagram showing a switching system to which an embodiment is applied.

FIG. 3 is an explanatory diagram showing a basic format of a layer 1 frame.

FIG. 4 is an explanatory diagram showing a format and an access method of a TDMA frame on a wireless line according to the embodiment.

FIG. 5 is an explanatory diagram showing a format of a layer 1 frame according to the embodiment.

FIG. 6 is an explanatory diagram showing the definition of bit numbers in an upstream K channel bit multiframe according to the embodiment.

FIG. 7 is an explanatory diagram showing allocation of upstream K channel bits in a multi-frame according to the embodiment.

FIG. 8 is an explanatory diagram showing definitions of bit numbers in a downlink K channel bit multi-frame according to the embodiment.

FIG. 9 is an explanatory diagram showing allocation of downlink K channel bits in a multiframe according to the embodiment.

[Explanation of symbols]

1 ... Digital cordless terminal, 2 ... Radio base station, 3 ... Switch, 11 ... Base station interface circuit (cordless subscriber circuit), 12 ... Main switch, 21 ... Layer 1 processing unit (base station interface unit), 22 ... Transformer Coder.

Claims (6)

[Claims] 1. A digital cordless terminal is accommodated, and two B channels into which information bits are inserted and a control bit is inserted between a switch and a radio base station.
Layer 1 defined as D channels and one K channel into which housekeeping bits are inserted
In a switching system that transmits in frames, K channel data is converted into multi-frames that form one frame by a plurality of layer 1 frames, and
A modification information transmission method of an information channel, characterized in that modification information of an information channel exchanged between a switchboard and a digital cordless terminal is inserted and transmitted at a predetermined position of a multi-frame of K channel. 2. The two B channels are divided, and the number of divided B channels is made equal to the number of information channels in one transmission frame on a wireless line. Qualified information transmission method of information channel. 3. The modification information transmission method of the information channel according to claim 1, wherein the modification information of the information channel is error information indicating whether or not the information channel data is in error. 4. The modification information of the information channel is VOX information for instructing to replace the data of the information channel with background noise data when there is no sound during a call. Modified information transmission method of the described information channel. 5. The K-channel multi-frame indicates a division of the same information channel distributed to a plurality of B-channels of a layer 1 frame, according to any one of claims 1 to 4. Modified information transmission method of the described information channel. 6. The information channel modification information according to claim 1, wherein the K-channel multi-frame synchronization information is also synchronization information for synchronizing a plurality of radio base stations. Transmission method.