JP3628524B2 - Communication channel multiplexer between satellite base station and portable satellite terminal station - Google Patents

Description

[0001]
[Technical field to which the invention belongs]
The present invention relates to a communication channel multiplexing apparatus for converting a communication channel between a satellite base station and a portable satellite terminal station into a plurality of subchannels via a communication satellite and increasing the multiplicity using a voice band compression apparatus.
[0002]
[Prior art]
Conventionally, portable satellite terminal stations have been developed for the purpose of bringing them to the disaster area in an emergency such as a disaster and securing at least one channel of communication path in the disaster area, so it is necessary to reduce the size of the device. For this reason, one having a channel for a communication path is generally used.
[0003]
[Problems to be solved by the invention]
However, in the conventional method as described above, since there is only one channel for the communication path, in reality, there are many cases of confusion due to insufficient channels.
[0004]
An object of the present invention is to increase the number of communication channels between a portable satellite terminal station and a satellite base station with a degree of freedom of connection even if the voice quality is somewhat deteriorated.
[0005]
[Means for Solving the Problems]
In order to solve the above problems, the invention according to claim 1 is directed to communication between a satellite base station and a portable satellite terminal station connected by a time-division digital channel, and the satellite base station and the portable satellite terminal station. a digital channel between further by temporally divided multiplexed channels constitute a plurality of subchannels, the portable satellite terminal station, bandwidth compression in response to a plurality of terminal devices or communication line writing a stretcher, transmit and receive buffers for temporarily storing compressed audio data, the time slot memory for storing time slot numbers of the previous SL sub-channel, as well as the time slot number of the subchannels in the time slot memory the control unit is arranged, the control section writes a time slot number of the subchannels in the time slot memory By Mukoto, said to have a plurality of terminal devices or division switching functions when applied to the connection between said plurality of sub-channels and communication lines, the control unit during the start of communication of the sub-channel in the time slot memory A time slot number is written, and the plurality of terminal apparatuses or communication lines and the plurality of subchannels are switched and connected .
[0006]
According to the present invention, the number of communication channels between the satellite base station and the portable satellite terminal station can be increased, and the satellite base station and the portable satellite terminal station can be provided with a time-division switching function. Is possible.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
A system configuration in the embodiment of the present invention is shown in FIG.
[0008]
In FIG. 1, 1 is a communication satellite, 2 is a portable satellite terminal station, and terminal devices such as a telephone set 4-1, a headset 4-2, and a cordless telephone 4-3 are connected to the portable satellite terminal station 2. Is done.
[0009]
Reference numeral 206 denotes a band compression / decompression unit of the portable satellite terminal device, and 207 denotes a multiplexing function unit.
[0010]
A satellite base station 3 is connected to a public communication network 5, a private branch exchange (PBX) 6 and the like in addition to the telephone 4-1.
[0011]
Reference numeral 301 denotes a bandwidth compression / decompression unit of the satellite base station, and 302 denotes a multiplexing function unit.
[0012]
In the embodiment shown in FIG. 1, there are two portable satellite terminal stations 2, but this number can be changed as required.
[0013]
The satellite base station 3, the communication satellite 1, and the portable satellite terminal station 2 are connected via the communication satellite 1 by time division multiple access.
[0014]
In the present embodiment, it is assumed that the portable satellite terminal station 2 and the satellite base station 3 are composed of one voice channel of 64 Kbps.
[0015]
Therefore, if audio can be compressed to 16 Kbps or less including control information, a 64 Kbps channel can be used as 4 subchannels of 16 Kbps.
[0016]
An outline of the operation will be described assuming that the portable satellite terminal station 2 on the upper side of the drawing is called from the public communication network 5.
[0017]
When there is an incoming call from the public communication network 5 to the satellite base station 3, it is connected to the band compression / decompression unit 301 through an interface circuit (not shown).
[0018]
There are several types of band compression methods used in the wireless system. Here, vector sum-excited linear predictive coding (hereinafter referred to as VSELP) is used.
[0019]
Although the compression rate of VSELP is variable, the description will be made here assuming that the compression rate is 9.6 Kbps and the control information is included in 16 kbps.
[0020]
The voice of the public communication network 5 of 64 kbps that has entered the band compression / decompression unit 301 is compressed to 16 Kbps VSELP voice for the uplink, and 16 Kbps VSELP voice for the downlink is 64 Kbps PCM voice or analog voice. Elongate.
[0021]
In this embodiment, the uplink and the downlink are paired, so that the uplink and the downlink are determined by selecting a subchannel.
[0022]
Since the audio signal that has passed through the band compression / decompression unit 301 is compressed to 16 Kbps, it can be placed on a 16 Kbps subchannel obtained by dividing a 64 Kbps channel into four.
[0023]
The multiplexing function unit 302 selects the free subchannel among the four subchannels going to the portable satellite terminal station 2 on the upper side of the drawing and places the compressed audio of 16 Kbps on this.
[0024]
As a result, the satellite base station 3 is connected to the portable satellite terminal station 2 on the upper side of the drawing.
[0025]
In the portable satellite terminal station 2, the connection to the terminal device changes depending on whether a dial number is sent from the base station 3, an additional number is sent, or nothing is sent.
[0026]
When a dial number or an additional number is sent, since the terminal device to be connected is designated, the multiplexing function unit 207 has a bandwidth compression / decompression unit corresponding to the designated terminal device, for example, the telephone 4-1. Connected to 206 compression / decompressor, the downlink converts 16 Kbps VSELP to 64 kbps PCM or analog voice, and the uplink converts 64 Kbps PCM or analog voice to 16 Kbps VSELP signal.
[0027]
As a result, the called terminal device 4-1 can make a call with the other party of the public communication network 5.
[0028]
If neither the dial nor the additional number can be received, the multiplexing function unit 207 selects and connects any one of the free terminal devices 4-1 to 4-3.
[0029]
Also in this case, if each terminal device is numbered, a call can be transferred between the terminal devices under the control of the multiplexing function unit 207 of the portable satellite terminal station 2 after connecting to a certain terminal device.
[0030]
FIG. 2 is a block diagram showing the internal configuration of the portable satellite terminal station 2.
[0031]
An external interface unit (hereinafter, referred to as an external I / F unit) 203 includes an interface 204 for the telephone set 4-1 and the cordless telephone 4-3 and an interface 205 for the headset.
[0032]
It is assumed that the interface with the cordless telephone 4-3 is a telephone interface, and the type between the telephone and the handset is cordless.
[0033]
A telephone interface (TELI / F) 204 and a headset interface (HDSI / F) 205 have a function of converting analog audio into 64 Kbps waveform encoded audio, and a band compression / expansion unit 206 that is a component of the baseband unit 201. Is delivered in the form of digital audio.
[0034]
The band compression / decompression unit 206 includes a plurality of compression / decompression units 218, and the compression / decompression unit 218 corresponds to the various interfaces 204 and 205 of the external I / F unit 203, respectively.
[0035]
The baseband unit 201 includes the band compression / decompression unit 206 and a multiplexing function unit 207. The multiplexing function unit 207 includes a reception buffer 208, a transmission buffer 209, and a time slot memory (hereinafter referred to as TS) corresponding to the compression / decompression unit 218. 210).
[0036]
The TS memory 210 here is not a time slot in a 64 Kbps frame configuration, but a TS memory that stores a time slot of a subchannel described later.
[0037]
A modulation unit 211 is provided for each of the four transmission buffers 209, and puts a 64 Kbps digital signal from the four transmission buffers on the modulated wave. The modulator 211 is provided corresponding to the number of 64 Kbps channels handled by the satellite terminal station 2.
A transmission frequency conversion unit 212 converts the modulated wave into a frequency to be sent to the communication satellite 1. One transmission frequency conversion unit 212 is also provided for the modulation unit 211.
[0038]
An antenna unit 213 transmits a radio wave having a transmission frequency converted by the transmission frequency conversion unit 212 toward the communication satellite 1. The antenna unit 213 is common to all the transmission frequency conversion units 212 and is also used for reception.
[0039]
Reference numeral 215 denotes a reception frequency conversion unit that converts a radio wave received from the communication satellite 1 into a modulated wave frequency, and is paired with the transmission frequency conversion unit 212.
[0040]
A demodulator 214 extracts a digital signal from the modulated wave. The demodulator 214 is paired with the modulator 211.
[0041]
A control unit 202 controls the entire terminal station 2 and sets the time slot of the subchannel in the TS memory 210 described above.
[0042]
An operation panel unit 216 instructs the control unit 202 to perform various settings such as multiplexing settings.
[0043]
Reference numeral 217 denotes a power supply unit that can handle any of an AC power supply, a DC power supply, and a battery.
[0044]
The configuration of the satellite base station 3 is basically the same as that of the portable satellite terminal station 2, and only the number of channels handled is increased.
[0045]
The operation of the portable satellite terminal station 2 when it is transmitted from the telephone 4-1 will be briefly described.
[0046]
When the handset is lifted by the telephone 4-1, the telephone interface (TELI / F) 204 is activated and a dial tone is returned. When the caller dials, the control unit 202 receives this and determines which subchannel should be selected.
[0047]
When the subchannel is determined, the time slot number of the selected subchannel is written in the TS memory 210 of the multiplexing function unit 207 corresponding to the telephone set 4-1.
[0048]
In the satellite base station 3, the same setting for the incoming call is performed according to the subchannel number and the dial number used from the control unit 202 of the portable satellite terminal station 2.
[0049]
As a result, the connection of the satellite part is completed, and the transmission from the telephone set 4-1 of the terminal station 2 is digitized by the telephone interface (TELI / F) 204 and compressed to, for example, 16 Kbps by the VSELP compression / decompression unit 218. Temporarily stored in the transmission buffer 209. When the time slot of the subchannel stored in the TS memory 210 arrives, the compressed audio data is transmitted from the transmission buffer 209 to the modulation unit 211, and is modulated as a digital bit string of 64 Kbps together with the audio data of other subchannels. .
[0050]
The modulated wave is raised to the frequency transmitted to the communication satellite 1 by the transmission frequency conversion unit 212 and transmitted from the antenna unit 213 toward the communication satellite 1.
[0051]
On the other hand, the radio wave received from the communication satellite 1, that is, the downlink radio wave is received by the antenna unit 213, lowered to the frequency of the modulation wave by the reception frequency conversion unit 215, demodulated by the demodulation unit 214, and returned to a 64 Kbps digital bit string. It is.
[0052]
Only the bits of the time slot of the subchannel stored in the TS memory are extracted from this bit string and temporarily stored in the reception buffer 208.
[0053]
The data stored in the reception buffer 208 is sent to the compression / decompression unit 218 at a rate of 16 Kbps, decompressed to 64 Kbps waveform encoded speech, and converted to analog speech by the telephone interface (TELI / F) 204 of the external I / F unit 203. And sent to the telephone 4-1.
[0054]
Since the same connection is made on the satellite base station 3 side, a call with the called party is possible.
[0055]
As described above, the correspondence between the terminal devices 4-1 to 4-3 and the subchannels is determined by the time slot numbers of the subchannels stored in the TS memory 210, so that the control unit 202 determines the contents of the TS memory. It can be changed freely by rewriting.
[0056]
In other words, the multiplexing function unit 207 has a time division exchange connection function and can freely connect between the subchannel and the terminal device.
[0057]
If the connection destination on the satellite base station 3 side is a digital line as in the public communication network 5, analog conversion is not performed in the external I / F unit 203 on the satellite base station 3 side, and the connection is made digitally.
[0058]
The above description is a case where the communication satellite 1 and the portable satellite terminal station 2 have 64 Kbps 1 channel and are connected in 4 sub-channels. However, there may be a plurality of 64 Kbps channels. Can be used as a 64 Kbps channel, and these can be set on the operation panel unit.
[0059]
An example of a method for converting a 64 Kbps channel into a plurality of subchannels will be described with reference to FIGS.
[0060]
FIG. 3 shows a frame and bit configuration in the case of digital multiplexing with a 64 Kbps channel, and is configured to have a length of 8000 frames / second, in other words, a length of one frame is 125 μs.
[0061]
Each frame is composed of n time slots (TS), and the same number of time slots (TS) constitute one channel.
[0062]
The lower diagram of FIG. 3 is a further development of frame 1 and time slot (TS) 1 in bit units, and is composed of 8 bits.
[0063]
Therefore, 8 bits × 8000 frames = 64000, and 64 Kbps channels are multiplexed by n channels.
[0064]
In FIG. 4A, 8 bits of one time slot (TS) in FIG. 3 are divided into four to form four subchannels (sch). Each subchannel (sch) has 2 bits per frame, so in frame 1, bits 1 and 2 of the subchannel (sch), and in frame 2, bits 3 and 4 of the subchannel (sch). (Not shown), the subchannel (sch) has bits 7 and 8 and one time slot (TS) is divided into four subchannels (sch).
[0065]
Therefore, if the TS memory 210 of FIG. 2 stores the time slot numbers of the subchannel (sch) (the time slot (TS) number in the 64 Kbps channel and the bit number in the time slot (TS)), four channels of 16 Kbps are stored. Can be identified.
[0066]
FIG. 4B is a bit configuration diagram when one time slot (TS) is divided into two, and a 64 Kbps channel can be divided into two 32 Kbps channels.
[0067]
Although not shown in the drawing, if the 8 bits of one time slot (TS) are divided into 8 subchannels (sch), it is possible to divide a 64 Kbps channel into 8 8 Kbps channels.
[0068]
Such division into subchannels (sch) is determined by the contents written in the TS memory 210 of FIG. 2, so that any of the n channels can be implemented, and the division into subchannels (sch) can be freely changed. .
[0069]
Therefore, setting of multiplexing can be easily performed by instructing the control unit 202 from the operation panel unit 216.
[0070]
In the satellite base station 3, the multiplicity can be freely changed by the satellite terminal station 2 of the communication partner, and different multiplicity can be obtained even in the same satellite terminal station 2.
[0071]
Since the multiplicity can be changed by rewriting the TS memory by the control unit 202, an instruction is sent from the operation panel unit of the satellite base station 3 to the control unit 202 of the portable satellite terminal station 2 via the control unit by remote operation. It is also possible to change the setting.
[0072]
FIG. 5 is a flowchart of multiplexing setting. First, in step S1, it is determined whether or not the setting is performed in the operation panel setting mode.
[0073]
If it is the operation panel setting mode, the operation panel unit 216 and the control unit 202 are set to the operation panel setting mode in step S2. Then, in step S4, it is determined whether or not it is a multiplexing mode. If it is a multiplexing mode, a device default mode is set according to the channel (step S8), and multiplexing is individually set (step S7). Is set (step S6).
[0074]
If it is not the multiplexing mode in step S4, multiplexing is not performed (step S9).
[0075]
If the operation panel setting mode is not set in step S1, the remote management mode from the satellite base station is set (step S3).
[0076]
Then, it is determined whether or not the mode is the multiplexing mode (step S5). If the mode is the multiplexing mode, steps S6 to S8 are set as in the case of the operation panel setting mode.
[0077]
If it is not the multiplexing mode in step S5, multiplexing is not performed (step S9).
[0078]
【The invention's effect】
According to the present invention, 64 Kbps voice is compressed to 32 Kbps, 16 Kbps, or 8 Kbps voice using the VSELP voice band compression technology and multiplexed onto a 64 Kbps digital channel, thereby enabling a small number of satellite base stations. It has the effect of being able to multiplex communication satellite channels between portable satellite terminal stations.
[Brief description of the drawings]
FIG. 1 is a system configuration diagram according to an embodiment of the present invention.
FIG. 2 is a block diagram of a portable satellite terminal station.
FIG. 3 is a frame configuration and bit configuration diagram of a digital channel of 64 Kbps.
FIG. 4 is a diagram showing a bit configuration in which 16 Kbps and 32 Kbps audio are placed on a 64 Kbps digital channel.
FIG. 5 is a flowchart for performing multiplexing setting of a portable satellite terminal station.
[Explanation of symbols]
1 Communication Satellite 2 Portable Satellite Terminal Station 201 Baseband Unit 202 Control Unit 203 External I / F Unit 206 Band Compression / Expansion Unit 207 Multiplexing Function Unit 208 Reception Buffer 209 Transmission Buffer 210 TS Memory 211 Modulation Unit 212 Transmission Frequency Conversion Unit 213 Antenna unit 214 Demodulation unit 215 Reception frequency conversion unit 218 Band compression / expansion unit 3 Satellite base stations 4-1 to 4-3 Terminal equipment 5 Public communication network 6 Private branch exchange (PBX)

Claims (1)

In communication between a satellite base station and a portable satellite terminal station connected by a time division digital channel,
By further dividing the digital channel between the satellite base station and the portable satellite terminal station in time, a plurality of subchannels are formed to multiplex the channels,
The said portable satellite terminal station, and bandwidth compression decompressor corresponding to the plurality of terminal devices or communication line, transmit and receive buffers for temporarily storing compressed audio data, the time slot number of the previous SL sub-channel A time slot memory for storing, and a control unit for writing the time slot number of the subchannel in the time slot memory ,
By the control unit writes the time slot number of the subchannels in the time slot memory, to have a division switching functions when applied to the connection between said plurality of sub-channels and the plurality of terminal devices or the communication line,
The satellite writes the time slot number of the subchannel in the time slot memory at the start of communication, and exchanges the plurality of terminal devices or communication lines and the plurality of subchannels. A communication channel multiplexer between a base station and a portable satellite terminal station.

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