JP2000307635A - Packet communication system, base station device and terminal device used in the packet communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently perform retransmission control over unreceived packets by reducing signal transfer between a terminal and a base station. SOLUTION: When the base station CS1 and mobile terminal devices PS1, PS2, and PS3 have a packet communication, data are sent from the base station CS1 by a specific number of packets and then the mobile terminal device PS1 when receiving an acknowledgement signal sends a transmission confirmation signal back to the base station CS1. At this time, reception history information indicating whether the packets are received or not is inserted into the transmission confirmation signal and sent back. Consequently, the base station CS1 is able to confirm which packet of the data received by itself is not received at a time according to the transmission confirmation signal and efficiently resends the unreceived packet.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a PHS (Pe
The present invention relates to a packet communication system in which packet communication is performed between a terminal device including a rsonal handy-phone system) and a base station device connected to a wired network. In particular, retransmission control when data is transmitted from the base station to the terminal device And a base station device and a terminal device used in the packet communication system.

[0002]

2. Description of the Related Art A packet communication system includes a plurality of mobile stations and a base station connected to a wired network.
In general, communication from the base station to the terminal is broadcast, and communication from the terminal to the base station is random access. In such a system, when data is transmitted from a base station to a terminal, retransmission control is performed as follows.

Now, it is assumed that the base station transmits data to terminal A as shown in FIG. It is assumed that data is transmitted from terminals A, B, and C to the base station at an arbitrary timing via a common communication channel.

As shown in a data transmission sequence example of FIG. 9, first, a base station transmits a predetermined number N of packets to terminal A, and then permits only terminal A to access the base station. Send the permission signal. In this case, since the permission signal is transmitted by broadcast, all terminals (terminals A, B, and C) under the control of the base station can receive the permission signal. The permission signal includes control information for causing a terminal specified by the base station to transmit a delivery confirmation signal, and for other terminals to temporarily stop transmitting data.

FIG. 10 shows a format of the permission signal.
The permission signal includes control information and data, and the control information includes a terminal ID and transmission suppression information. The terminal ID specified by the base station is written in the terminal ID of the control information, and the transmission suppression information of the control information is set to ON to temporarily stop data transmission of another base station. In the example of FIG. 9, the base station uses this permission signal to permit only the terminal A to transmit the acknowledgment signal, and the other terminals B and C need to temporarily stop transmitting data. ID = A and transmission suppression information = ON.

When this permission signal is transmitted to each of terminals A, B, and C, terminals other than terminal A designated by the base station by control information contained therein, that is, terminals B and C temporarily suspend data transmission. I do. On the other hand, terminal A transmits an acknowledgment signal by receiving the permission signal from the base station. This is because the acknowledgment signal transmitted from the terminal A is given priority over the data transmission of the other terminals B and C. In this way, it is possible to prioritize transmission of the acknowledgment signal from a specific terminal, so that retransmission control can be performed quickly.

When the base station transmits data of a predetermined number N of packets to the terminal A, some packets out of the number N of packets may be lost during the transmission. In particular, in packet communication using a wireless channel, a transmission error frequently occurs, and the tendency is remarkable.

FIG. 11 shows an example of a conventional data transmission sequence when a transmission error occurs. In the example of FIG. 11, the number of packets N is 5, and when the base station transmits data for 5 packets to the terminal A, the packet number 1 and the
3 and 4 show a state in which a transmission error has occurred.

Here, in the conventional system, the acknowledgment signal from the terminal to the base station contains only the oldest unconfirmed packet number. For this reason, when a large number of transmission errors occur, a notification of a permission signal from the base station to the terminal and a transmission of a delivery confirmation signal of the received packet from the terminal to the base station in response thereto are frequently exchanged.

More specifically, as shown in FIG. 11, when a transmission error occurs in packet numbers 1, 3, and 4, when terminal A receives a permission signal from the base station, the terminal A first receives the permission signal. An acknowledgment signal indicating that the oldest packet number 1 has not been received is returned to the base station. In response, the base station retransmits the data of packet number 1 to terminal A,
Notifies the permission signal. Next, upon receiving the permission signal, the terminal A returns an acknowledgment signal indicating that the packet number 3 has not been received to the base station. In response to this, the base station retransmits the data of the packet number 3 to the terminal A and notifies the permission signal again. The same applies to the data of packet number 4, and retransmission is performed by exchanging a permission signal from the base station to terminal A and a delivery acknowledgment signal from terminal A to the base station.

[0011]

As described above, conventionally, when there are a plurality of unreceived packets in the data receiving terminal, the permission signal from the base station and the number of unreceived packets from the terminal are equal to the number of unreceived packets. It was necessary to exchange a delivery confirmation signal. Therefore, the larger the number of unreceived packets,
There has been a problem that the effective transfer speed has been significantly reduced, and this tendency is particularly remarkable in an environment where burst errors are likely to occur, such as wireless packet communication.

Also, if a base station frequently transmits a permission signal to a specific terminal in response to the occurrence of an unreceived packet, communication between another terminal and the base station is stopped during that time. There has been a problem that the effective transfer speed of the entire system also decreases.

The present invention has been made in view of the above points, and a packet communication system capable of efficiently performing retransmission control of an unreceived packet by reducing the exchange of signals between a terminal and a base station. It is an object to provide a base station device and a terminal device used in the packet communication system.

[0014]

In order to solve the above problems, the present invention provides at least one base station device constituting a wireless area, and a plurality of terminal devices existing in the wireless area of the base station device. In a packet communication system in which packet communication is performed using a common communication channel among the above, in the base station apparatus, data of a predetermined number of packets for a predetermined terminal device among the terminal devices is transmitted in packet units. A packet transmission control means for transmitting, and after transmitting data by the packet transmission control means, a permission signal for permitting access to only the predetermined terminal device and prohibiting access of other terminal devices as access control information, An access control means for notifying the device, and a delivery confirmation returned from the predetermined terminal device after notifying the permission signal by the access control means. Retransmission control means for retransmitting unreceived packets to the terminal device by determining a packet that the terminal device was able to receive and a packet that was not received in the transmission data based on the signal, and the terminal device, When receiving the permission signal sent from the base station device,
Reception history creating means for creating reception history information indicating packets received up to that point and packets not received, and an acknowledgment signal containing the reception history information created by the reception history creation means, And an acknowledgment transmitting means for returning to the device.

According to such a configuration, when the base station apparatus transmits data of a predetermined number of packets to the terminal apparatus and broadcasts the permission signal, the terminal apparatus includes reception history information indicating the received packet and the unreceived packet. An acknowledgment signal is returned. Therefore, the base station apparatus can confirm which packet has not been received in the data transmitted by the base station apparatus at a time by receiving the acknowledgment signal, and can efficiently retransmit the unreceived packet. Can do well.

Further, in the base station apparatus, before reporting the permission signal, the number of data packets to be transmitted by the packet transmission control means is adjusted to the number of the terminal apparatuses, the number of unreceived packets, and the amount of transmission data. By making changes accordingly, efficient data communication can be performed, and data transmission time to the terminal can be reduced.

In the base station apparatus, the number of retransmissions of unreceived packets by the retransmission control means is changed in accordance with the number of unreceived packets that the terminal apparatus could not receive, so that the radio environment can be changed according to the state. Flexible retransmission control can be realized. As a result, the exchange of the reception history of the terminal in a bad environment can be reduced, and the data transmission time can be further reduced.

[0018]

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

Since the present invention can be suitably applied to a mobile packet communication system, the following description will be made assuming a mobile packet communication system using a PHS.

(First Embodiment) FIG. 1 is a schematic block diagram of a mobile packet communication system according to the present invention.
n indicates a PHS base station. These base stations CS
1 to CSn are geographically distributed in a service area covered by the system, and one or a plurality of them form a wireless area.

PS1 to PSm indicate mobile terminal devices using PHS. These mobile terminal devices PS1 to PS
m is connected to the nearest base station via a radio line in a cell formed by each of the base stations CS1 to CSn. As a wireless access method between the base station and the mobile terminal device, for example, TDMA-TDD (Time Division M
ultiple Access-Time Division Duplex) system is used. The mobile terminal devices PS1 to PSm include a mobile information terminal having a data communication function and a wireless access function, and a mobile terminal device having a personal computer PC connected to the mobile phone, in addition to a mobile phone having only a call function.

Each of the base stations CS1 to CSn is connected to an I 'interface network (hereinafter referred to as an I' network) IN2 via a subscriber line and to a dedicated line network PN via a dedicated line. Connected. I 'net IN2 is PH
It is for accommodating the S base stations CS1 to CSn and constitutes a public network composed of a circuit switching network together with the integrated services digital network (ISDN) IN1. Many wired terminal devices (not shown) are connected to the public network. The leased line network PN forms a packet network. The packet exchange is performed according to the protocol specified in 25.

A gateway GW as a data communication device is connected to the ISDN network IN1 and the private line network PN, and a server device AS is connected to the gateway GW via, for example, a LAN. The server device AS
It has a function as a mail server when e-mail is transmitted between the mobile terminal devices PS1 to PSm and the wired terminal device, and notifies the mobile terminal devices PS1 to PSm and the wired terminal device of Web information such as news and advertisements. It has a function as a content server to execute.

Note that the gateway GW is also connected to a computer network such as the Internet (not shown) via an access server of a service provider, for example. The Internet has many WWW (World-Wi
de Web) The server is connected. By using the TCP / IP protocol for these WWW servers, not only the subscriber wired terminal devices but also the above-mentioned mobile terminal devices PS1 to PS
Access is also possible from Sm.

Next, the base stations CS1 to CSn are configured as follows. FIG. 2 is a functional block diagram showing the configuration.

The base stations CS1 to CSn are connected to the antenna 111
, A modem unit 20, and a TDMA unit 3.
0, an interface unit 40, a control unit 50, an information storage unit 60, and a data communication unit 70.

That is, the radio carrier signals arriving from the mobile terminal devices PS1 to PSm are received by the antenna 111 and then input to the receiving unit 113 via the high frequency switch (SW) 112 of the radio unit 10. The receiving unit 113 converts the received wireless carrier signal into the synthesizer 11
4 and down-converted into a received intermediate frequency signal. The frequency of the local oscillation signal generated from the synthesizer 114 is instructed by the control unit 50 according to the radio channel frequency. The radio unit 10 includes a reception field strength detection unit (RS
SI) 116 is provided. The reception electric field strength detection section 116 detects the reception electric field strength of the radio carrier signal arriving from the mobile terminal apparatuses PS1 to PSm, and the detected value is used as a control section 50 for searching for an idle channel or controlling handover of the mobile terminal apparatus. Will be notified.

The received intermediate frequency signal output from the receiving section 113 is input to the demodulation section 221 of the modem section 20. The demodulation unit 221 performs digital demodulation of the received intermediate frequency signal, thereby reproducing a digital demodulated signal.

The TDMA decoding section 33 of the TDMA section 30
1 separates the digital demodulated signal for each reception time slot. If the data of the separated slot is audio data, the audio data is input to the interface unit 40. On the other hand, if the data of the separated slot is packet data or control data, these data are input to the data communication unit 70.

The interface unit 40 has an ADPCM (Ad
aptive Differential Pulse Code Modulation) transcoder 441, public line interface 442,
And a dedicated line interface 443.

The ADPCM transcoder 441 decodes the audio data output from the TDMA decoding section 331. The decoded digital audio signal is transmitted from the public line interface 442 to the I 'network IN2. The public line interface 442 performs a call connection process for the I 'network IN2 according to an instruction from the control unit 50. The leased line interface 443 performs processing for opening a connection for packet communication to the leased line network PN, etc., in accordance with an instruction from the control unit 50.

The data communication unit 70 is connected to the mobile terminal PS1.
If the data arriving from .about.PSm is control data addressed to the own station, the control data is input to the control unit 50. The control unit 50 performs processing for establishing a connection for packet communication, which will be described later, based on the control data. On the other hand, if the data arriving from the mobile terminal devices PS1 to PSm is packet data addressed to the outside, the data communication unit 70 sends the packet data to the leased line network PN via the leased line interface 443.

On the other hand, a digital communication signal arriving from the I 'network IN2 is received by the public line interface 442. If the digital communication signal is audio data, the digital communication signal is subjected to compression encoding processing by the ADPCM transcoder 441 and is input to the TDMA encoding unit 332. On the other hand, if the digital communication signal is control data, it is input to the data communication unit 70. Further, packet data arriving from the leased line network PN is input to the data communication unit 70 via the leased line interface 443.

If the destination of the input data is the mobile terminal device PS1 to PSm, the data communication unit 70 inputs the data to the TDMA encoding unit 332. On the other hand, if the input data is control data addressed to the own station,
The control data is input to the control unit 50. Control unit 50
Performs various controls by analyzing the input control data. Further, the control unit 50 includes the mobile terminal devices PS1 to PSm
The control data addressed to the TD via the data communication unit 70
Output to MA encoding section 332.

[0035] The TDMA encoding unit 332 converts the AD
The digital voice data of each channel output from the PCM transcoder 441 and the control data and packet data output from the data communication unit 70 are inserted into the transmission time slot designated by the control unit 50 and multiplexed. The modulation section 222 digitally modulates the transmission intermediate frequency signal with the multiplexed digital communication signal output from the TDMA encoding section 332, and inputs the modulated transmission intermediate frequency signal to the transmission section 115.

The transmitting section 115 mixes the modulated transmission intermediate frequency signal with the local oscillation signal generated from the synthesizer 114, upconverts the mixed signal into a radio carrier frequency, and further amplifies the signal to a predetermined transmission power level. The wireless carrier signal output from the transmitting unit 115 is transmitted from the antenna 111 to the mobile terminal devices PS1 to PSm via the high frequency switch 112.

The control unit 50 has a microcomputer as a main control unit, and includes a packet transmission control unit 551, an access control unit 552, and a retransmission control unit 553 as control functions according to the present invention.

The packet transmission control section 551 performs control for transmitting data of a predetermined number of packets in packet units to a designated terminal among the mobile terminal devices PS1 to PSm which are mobile stations. . Access control unit 55
2 after the data transmission by the packet transmission control unit 551, as access control information for controlling access to the mobile terminal devices PS1 to PSm, permit access only to the terminal of the data transmission destination, and permit access to other terminals. Control for notifying a permission signal for prohibition is performed. Retransmission control unit 55
3 determines, based on the acknowledgment signal returned from the data transmission destination terminal, a packet that the data transmission destination mobile terminal device has received and a packet that has not been received among the transmission data, Is determined as an unreceived packet to be retransmitted to the mobile terminal device, and retransmission control of the unreceived packet is performed.

The acknowledgment signal includes reception history information indicating a received packet / unreceived packet which is a feature of the present invention. This will be described later with reference to FIG.

The permission signal is the same as in the prior art, and includes control information and data as described in the format configuration of FIG. 10, and the control information includes a terminal ID and transmission suppression information. The terminal ID specified by the base station is written in the terminal ID of the control information, and the transmission suppression information of the control information is set to ON to temporarily stop data transmission of another base station. As a result, access (transmission of a signal) is permitted only to the designated terminal.

The mobile terminal devices PS1 to PSm are configured as follows. FIG. 3 is a functional block diagram showing the configuration.

Each of the mobile terminals PS1 to PSm includes a radio unit 1 having an antenna 11, a modem unit 2, and a TDMA unit 3.
, A communication unit 4, a control unit 5, an information storage unit 6, a data communication unit 7, a display unit 8, and a key input unit 9.

That is, the radio carrier signals arriving from the base stations CS1 to CSn are received by the antenna 11 and then input to the receiving unit 13 via the high frequency switch (SW) 12 of the radio unit 1. In the receiving unit 13, the received radio carrier signal is mixed with the local oscillation signal generated from the synthesizer 14 and down-converted into a received intermediate frequency signal. The local oscillation signal frequency generated from the synthesizer 14 is set to a value corresponding to the radio channel frequency according to an instruction from the control unit 5. Also, the radio unit 1 includes a reception field strength detection unit (RSSI) 16
Is provided. In this reception electric field strength detection unit 16,
The received electric field strengths of the radio carrier signals arriving from the base stations CS1 to CSn are detected, and the detected values are reported to the control unit 5 for, for example, determining and displaying the reception quality.

The received intermediate frequency signal output from the receiver 13 is input to the demodulator 21 of the modem 2. The demodulation section 21 digitally demodulates the received intermediate frequency signal, thereby reproducing the digital demodulated signal.

TDMA decoding section 31 of TDMA section 3
Separates the digital demodulated signal for each reception time slot. If the data of the separated slot is audio data, the audio data is transmitted to the interface unit 4.
To enter. On the other hand, if the data of the separated slot is packet data or control data, these data are input to the data communication unit 7.

The communication unit 4 has an ADPCM (Adaptive Diffe
rential Pulse Code Modulation) Transcoder 41
, A PCM codec 42, a speaker 43, and a microphone 44. The ADPCM transcoder 41 decodes the audio data output from the TDMA decoding unit 31. The PCM codec 42 uses the A
The digital audio signal output from the DPCM transcoder 41 is converted into an analog signal, and this audio signal is output from the speaker 43 as loudspeaker.

The data communication unit 7 receives the data supplied from the TDMA decoding unit 31 and supplies the data to the control unit 5. If the received data is control data, the control unit 5 analyzes the control data and performs necessary control.
On the other hand, if the received data is packet data arriving from a server or the like, the packet data is depacketized, stored in the information storage unit 6, and supplied to the display unit 8 including, for example, a liquid crystal display (LCD). Display.

On the other hand, the user's voice signal input to the microphone 44 is PCM-coded by the PCM codec 42 and then compression-coded by the ADPCM transcoder 41. Then, the encoded audio data is TDM
It is input to the A encoding unit 32. The control data and packet data output from the control unit 5 are input to the TDMA encoding unit 32 via the data communication unit 7.

[0049] The TDMA encoding unit 32
The digital audio data of each channel output from the CM transcoder 41 and the control data and packet data output from the data communication unit 7 are inserted into a transmission time slot designated by the control unit 5 and multiplexed. The modulation unit 22 digitally modulates the transmission intermediate frequency signal with the multiplexed digital communication signal output from the TDMA encoding unit 32, and inputs the modulated transmission intermediate frequency signal to the transmission unit 15.

The transmission section 15 mixes the modulated transmission intermediate frequency signal with the local oscillation signal generated from the synthesizer 14, upconverts the mixed signal into a radio carrier frequency, and further amplifies the signal to a predetermined transmission power level. The radio carrier signal output from the transmitting unit 15 is transmitted from the antenna 11 via the high frequency switch 12 to the base stations CS1 to CSn.
Sent to

The control unit 5 has a microcomputer as a main control unit, for example, and includes a reception history creating unit 51 and a delivery confirmation transmitting unit 52 as control functions according to the present invention.

When receiving the permission signal from the base station, the reception history creation section 51 creates reception history information indicating the packets that have been received and the packets that have not been received. The acknowledgment transmission unit 52 performs a process of returning an acknowledgment signal (FIG. 4) including the reception history information created by the reception history creation unit 51 to the base station.

FIG. 4 shows a format configuration of the acknowledgment signal of the present invention.

The acknowledgment signal is a signal for allowing the base station to confirm the reception status when the data transmitted from the base station is received. Normally, this delivery confirmation signal contains only the oldest unconfirmed packet number,
The present invention is characterized in that the above-described reception history information is included.

That is, the acknowledgment signal of the present invention comprises control information and data, and the control information includes
D and the like, and reception history information indicating a reception history are included. In the reception history information, the numbers of the received packet and the unreceived packet are described. For example, when the number N of packets of data transmitted from the base station is 5, and the data of the packet numbers 1, 3, and 4 is not received for some reason (that is, when the data is not transmitted from the base station) 4), as shown in FIG. 4, as reception history information, packet number 1 = unreceived, packet number 2 = received,
A description such as packet number 3 = unreceived, packet number 4 = unreceived, packet number 5 = received is made in the reception history information. Based on the reception history information, the base station can confirm at once the packets that the terminal could receive and the packets that it could not receive among the data transmitted by itself.

Next, the operation of the wireless packet communication system configured as described above will be described. Here, the communication procedure will be described on the assumption that packet communication is performed between the base station CS1 and a plurality of mobile terminal devices PS1, PS2, and PS3 under its control via a common communication channel.

FIG. 5 is a sequence diagram showing a packet communication procedure according to the first embodiment of the present invention.

It is assumed that the base station CS1 transmits data of a predetermined number N (5 in this example) of packets to the mobile terminal device PS1 in packet units. After sequentially transmitting five packets, the base station CS1 broadcasts a permission signal for permitting access to the base station only to the mobile terminal device PS1.

More specifically, the packet transmission control unit 551 of the control unit 50 shown in FIG. 2 determines the number N of packets for the mobile terminal device PS1. Then, after transmitting the data of the number N of packets (data provided from the server device AS or the like), the access control unit 552 generates a permission signal including the terminal ID of the mobile terminal device PS1 and the transmission suppression information. And broadcast as access control information. This permission signal is transmitted to each mobile terminal device PS1, P1 sharing the communication channel.
S2 and PS3 are notified, respectively. Of these, access is permitted only to the mobile terminal device PS1, and access to the other mobile terminal devices PS2 and PS3 is prohibited. Therefore, the mobile terminal device PS2,
When PS3 receives this permission signal, it suspends data transmission to base station CS1.

On the other hand, the mobile terminal device PS that has received the data
Receiving this permission signal, 1 transmits an acknowledgment signal including reception history information indicating reception / non-reception of the five packets transmitted by base station CS1 to base station CS1. More specifically, reception history creation section 51 shown in FIG. 3 creates reception history information describing the numbers of received packets and unreceived packets, and delivery confirmation transmission section 52 includes this reception history information in the delivery confirmation signal. Then, it transmits to base station CS1.
FIG. 4 shows a format example of the delivery confirmation signal at this time. This example indicates that the mobile terminal device PS1 could not receive the packets of the packet numbers 1, 3, and 4 due to a transmission error.

Upon receiving the acknowledgment signal, the base station CS1 checks the received packet and the unreceived packet, and if there is any unreceived packet, starts retransmission in order from the oldest unreceived packet. Specifically, the retransmission control unit 553 of the control unit 50 shown in FIG. 2 uses the mobile terminal device PS1 in the data transmitted by itself based on the acknowledgment signal.
Determine which packets have been received and which have not. If there are a plurality of unreceived packets, they are retransmitted in chronological order. In this example, since the packet numbers 1, 3, and 4 are unreceived packets, retransmission is performed to the mobile terminal device PS1 in the order of the packet numbers 1, 3, and 4.

As described above, when data of a predetermined number N of packets is transmitted from the base station CS1 to the mobile terminal device PS1,
Upon notification of the permission signal, the mobile terminal device PS1 returns an acknowledgment signal including reception history information indicating the received packet and the unreceived packet. Therefore, the base station CS1 receives the acknowledgment signal to confirm at a time which packet in the data transmitted by itself has not been received, and to efficiently retransmit the unreceived packet. Can do well.

It is to be noted that the mobile station device PS is transmitted from the base station CS1.
It is not necessary to predetermine the number N of packets of data to be transmitted between the base station CS1 and the mobile terminal device PS1 before transmitting data to 1. In this case, the mobile terminal device PS1 cannot know in advance how many packets are to be transmitted, but when the permission signal is transmitted from the base station CS1, the reception is performed immediately before the permission signal is transmitted. By returning the reception history up to the confirmed packet, the base station CS1 can determine which packet has not been received.

That is, in the example of FIG. 5, the number N of data packets transmitted from the base station CS1 to the mobile terminal device PS1 is 5
And the mobile terminal device PS1 ends with the packet number 5
5 shows the case where the data of the above is received. In such a case, the reception history information indicating that the packet numbers 2 and 5 can be received and the packet numbers 1, 3, and 5 have not been received according to the packet number 5 of the data last received on the mobile terminal device PS1 side. If the packet is returned to the base station CS1 in the acknowledgment signal, the base station CS1 determines that among the packet numbers 1 to 5 transmitted by itself, the packet numbers 1, 3, and 5 have not been received. And can resend those data.

In the example of FIG. 5, it is assumed that packet number 5 has not been received yet. In such a case, the packet number of the last received data is 2, and the number of packets N (=
It becomes smaller than 5). In such a case, packet number 2 can be received in accordance with packet number 2 of the data last received on the mobile terminal device PS1, and reception history information indicating that packet number 1 has not been received is included in the delivery confirmation signal. If the packet is returned to the base station CS1, the base station CS1 can determine that among the packet numbers 1 to 5 transmitted by itself, the packet numbers 1, 3, 4, and 5 have not been received. Can be resent.

By the way, the packet transmission control unit 551 shown in FIG. 2 may arbitrarily change the value of the number N of packets of data to be continuously transmitted until the base station CS1 broadcasts the permission signal as follows. You may do it.

As a first method, the value of the number of packets N is changed according to the number M of terminals controlled by the base station CS1. For example, when the number M of terminals is smaller than a preset value, the value of the number N of packets is increased according to the number M of terminals. As a result, when there are few terminals under
Data transmission time to the mobile terminal device PS1 can be reduced.

As a second method, the value of the number of packets N is changed according to the number of unreceived packets P in the acknowledgment signal transmitted from the mobile terminal device PS1 to the base station CS1.
Generally, the larger the number of unreceived packets, the worse the line condition is considered. Therefore, for example, when the number of unreceived packets P is smaller than a preset value, the number of packets N
Is increased according to the number P of unreceived packets. As a result, the time required to retransmit an unreceived packet can be reduced, and as a result, transfer efficiency can be increased.

As a third method, the value of the number of packets N is changed according to the transmission data amount Q to the mobile terminal device PS1 stored in the transmission buffer inside the base station CS1.
For example, when the transmission data amount Q is larger than a preset value, the value of the packet number N is increased according to the transmission data amount Q. Thereby, the exchange of the reception history in the transmission with a large data amount is reduced, and the mobile terminal device PS1
Data transmission time can be shortened.

The number N of packets to be continuously transmitted may be determined by combining the above three conditions.

(Second Embodiment) Next, a second embodiment of the present invention will be described.

In the first embodiment, the number of times when the base station retransmits an unreceived packet is set to one. In the second embodiment, the number of retransmissions is changed according to the number of unreceived packets. It is characterized by the following. In the following, a base station CS1 and a plurality of mobile terminals PS under its control
The communication procedure will be described on the assumption that packet communication is performed between the first, PS2 and PS3 via a common communication channel.

FIGS. 6 and 7 are sequence diagrams showing a packet communication procedure in the second embodiment. FIG. 6 shows an example in which the number of retransmissions is one, and FIG. 7 shows an example in which the number of retransmissions is two. Is shown.

As shown in FIG. 6, when the base station CS1 transmits data of a predetermined number of packets N (5 in this example) to the mobile terminal device PS1 in packet units, the base station CS1 transmits the packet number 1 Assume that an error has occurred. When receiving the permission signal transmitted from the base station CS1, the mobile terminal device PS1 transmits the base station CS1 to the base station CS1.
1 transmits an acknowledgment signal including reception history information indicating reception / non-reception of the five packets transmitted. More specifically, reception history creation section 51 shown in FIG. 3 creates reception history information describing the numbers of received packets and unreceived packets, and delivery confirmation transmission section 52 includes this reception history information in the delivery confirmation signal. Then, it transmits to base station CS1. In this example, reception history information indicating that packet number 1 has not been received and packet numbers 2 to 5 have been received is included in the acknowledgment signal and transmitted to base station CS1.

Here, the base station CS1 retransmits an unreceived packet by receiving the acknowledgment signal. At this time, in base station CS1, retransmission control section 553 shown in FIG. 2 determines the number of retransmissions of the unreceived packet according to the number of unreceived packets, and performs retransmission for the number of times.
In this case, it can be determined that the wireless environment is worse as the number of unreceived packets is larger. Therefore, it is preferable to increase the number of retransmissions. In the example of FIG. 6, since the number of unreceived packets is one, the number of retransmissions is set to one, and the data of the packet number 1 which is the unreceived packet is transmitted to the mobile terminal device P.
Retransmitted to S1.

On the other hand, as shown in FIG.
Assuming that a transmission error occurs in packet numbers 1, 3, and 4 when S1 transmits data of a predetermined packet number N (5 in this example) to the mobile terminal device PS1 in packet units, After receiving the permission signal, the mobile terminal device PS1 sends the packet numbers 1, 3, to the base station CS1.
The base station CS1 includes reception history information indicating that packet No. 4 has not been received and packet numbers 2 and 5 have been received in the delivery confirmation signal.
Will be sent to Upon receiving the acknowledgment signal, the base station CS1 determines the number of unreceived packets and performs retransmission according to the number of unreceived packets. In this case, since the number of unreceived packets is larger than that in FIG. 6, base station CS1 sets a larger number of retransmissions and retransmits the unreceived packets according to the set number. In the example of FIG. 7, since the number of unreceived packets is three, the number of retransmissions is set to two, and the data of the packet numbers 1, 3, and 4, which are unreceived packets, are repeated twice and the mobile terminal device P
Retransmitted to S1.

As described above, when the base station CS1 retransmits an unreceived packet, by changing the number of retransmissions according to the number of unreceived packets, it is possible to flexibly cope with the radio environment according to the state. it can. Thereby, the exchange of the reception history of the mobile terminal device PS1 in a bad environment can be reduced, and the data transmission time to the mobile terminal device PS1 can be shortened.

As a method of setting the number of retransmissions of unreceived packets, for example, the number is set stepwise according to the ratio of the number P of unreceived packets in the delivery confirmation signal to the number N of packets determined at the time of data transmission. And so on.

Further, the number of packets N itself may be arbitrarily changed under predetermined conditions by the method as in the first embodiment.

[0080]

As described above, according to the present invention, reception history information indicating reception / non-reception of a packet at that time is inserted into a delivery confirmation signal returned from a terminal to a base station during packet communication. By receiving the acknowledgment signal, the base station can confirm at a time which packet in the data transmitted by itself has not been received, and efficiently retransmit the unreceived packet. Can be. By this means, it is possible to reduce the communication of the notification of the permission signal from the base station to the terminal during the packet communication and the transmission of the transmission acknowledgment signal of the received packet from the terminal to the base station in response thereto, thereby improving the effective transfer rate. .

When data is transmitted from the base station to the terminal device in packet units, the number of data packets to be transmitted is changed according to the number of registered terminals, the number of unreceived packets, the amount of transmitted data, and the like. Thus, efficient data communication can be performed, and the time for transmitting data to the terminal can be reduced.

Also, when retransmitting an unreceived packet from the base station to the terminal device, by changing the number of retransmissions according to the number of unreceived packets, flexible retransmission control according to the state of the wireless environment can be realized. . As a result, the exchange of the reception history of the terminal in a bad environment can be reduced, and the data transmission time can be further reduced.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration of a mobile packet communication system according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a base station device in the mobile packet communication system of FIG. 1;

FIG. 3 is a block diagram showing a configuration of a mobile terminal device in the mobile packet communication system of FIG. 1;

FIG. 4 is a diagram showing a format configuration of an acknowledgment signal of the present invention.

FIG. 5 is a sequence diagram showing a packet communication procedure according to the first embodiment of the present invention.

FIG. 6 is a sequence diagram showing a packet communication procedure according to the second embodiment of the present invention, showing an example in which the number of retransmissions is set to one;

FIG. 7 is a sequence diagram showing a packet communication procedure according to the second embodiment of the present invention, showing an example in which the number of retransmissions is set to two;

FIG. 8 is a diagram for explaining data transmission from a base station to a terminal in a general mobile packet communication system.

FIG. 9 is a diagram showing a data transmission sequence between a base station and a terminal.

FIG. 10 shows a format of a permission signal.

FIG. 11 is a sequence diagram showing a conventional packet communication procedure.

[Explanation of symbols]

 CS1 to CSn base station PS1 to PSm mobile terminal device IN1 ISDN network IN2 I 'network PN dedicated line network AS server device GW gateway 1, 10 radio unit 2, 20 modem unit 3, 30 TDMA unit 4 Talk unit 5, 50 Control unit 6, 60 Information storage unit 7, 70 Data communication unit 8 Display unit 9 Input unit 11, 111 Antenna 12, 112 High frequency switch (SW) 13, 113 receiving unit 14, 114 synthesizer 15, 115 transmitting unit 16, 116 receiving electric field strength detecting unit (RSSI) 21, 221 demodulating unit 22, 222 modulating unit 31, 331 TDMA decoding unit 32, 332 TDMA encoding unit 40 interface units 41, 441 ADPCM transcoder 42 PCM codec 43 speaker 44 Microphone 442 ... public line interface 443 ... service line interface 51 ... reception history creating unit 52 ... acknowledgment transmitting unit 551 ... packet transmission control unit 552 ... Access control unit 553 ... retransmission control unit

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5K030 HA08 HC01 HC09 HD03 JL01 JT09 5K067 AA11 AA14 BB04 CC08 DD11 DD24 DD51 EE02 EE10 FF02 HH23 HH28 KK15 9A001 BB04 CC02 CC04 CC05 CC06 JJ12 JJ27 KK56

Claims (7)

[Claims] 1. Packet communication for performing packet communication between at least one base station device constituting a wireless area and a plurality of terminal devices existing in the wireless area of the base station device using a common communication channel. In the system, the base station apparatus includes: packet transmission control means for transmitting data of a predetermined number of packets to a predetermined terminal device among the terminal devices in packet units; After the transmission, access control means for permitting access only to the predetermined terminal device and notifying each terminal device of a permission signal for prohibiting access of other terminal devices as access control information; and a permission signal by the access control means. Of the terminal device in the transmission data based on an acknowledgment signal returned from the predetermined terminal device after the notification of Retransmission control means for recognizing a received packet and a packet that could not be received, and retransmitting an unreceived packet to the terminal device, wherein the terminal device receives a permission signal transmitted from the base station device. Receiving history creation means for creating reception history information indicating the packets received up to that point and the packets that could not be received, and a delivery acknowledgment signal including the reception history information created by the reception history creating means And a acknowledgment transmitting means for returning the packet to the base station apparatus. 2. The system according to claim 1, wherein the base station device changes the number of data packets to be transmitted by the packet transmission control means according to the number of the terminal devices before reporting the permission signal. 2. The packet communication system according to 1. 3. The system according to claim 2, wherein the base station apparatus changes the number of data packets to be transmitted by the packet transmission control means in accordance with the number of unreceived packets before reporting the permission signal. 2. The packet communication system according to 1. 4. The base station apparatus according to claim 1, wherein the number of data packets to be transmitted by the packet transmission control means is changed in accordance with the amount of the transmission data before reporting the permission signal. The packet communication system according to claim 1. 5. The base station device, when retransmitting an unreceived packet, changes the number of retransmissions of the unreceived packet by the retransmission control unit according to the number of unreceived packets that the terminal device has not received. The packet communication system according to claim 1, wherein: 6. A base station device for performing packet communication with a plurality of terminal devices sharing a communication channel, the data being a predetermined number of packets for a predetermined terminal device among the terminal devices. Packet transmission control means for transmitting the packet data in packet units. After the data transmission by the packet transmission means, a permission signal for permitting access only to the predetermined terminal device and prohibiting access to other terminal devices is used as access control information. Access control means for notifying each terminal device, and the terminal device was able to receive in the transmission data based on an acknowledgment signal returned from the predetermined terminal device after transmission of the permission signal by the access control device Retransmission control means for judging a packet and a packet that could not be received, and retransmitting an unreceived packet to the terminal device. Base station device. 7. A terminal device for performing packet communication with at least one base station device constituting a wireless area, wherein when a permission signal sent from the base station device is received, the terminal device performs a Receiving history creating means for creating receiving history information indicating a packet that was successfully received and a packet that could not be received, and returned an acknowledgment signal including the receiving history information created by the receiving history creating means to the base station apparatus. A terminal device comprising: