JP2583269B2 - Wireless packet communication method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for using a single wireless channel to communicate between a plurality of wireless terminals and a control station (therefore, a wireless terminal and a wireless terminal with a control station interposed). Between) wireless packet communication methods.

As such a wireless terminal, a small portable terminal having a simple data display function and a data input function can be considered. Considering, as an example, a wireless packet communication method capable of transmitting and receiving data between persons carrying such wireless terminals or between a person carrying the wireless terminals and a certain center via a control station, The use of communication methods seems to be very diverse. The present invention
The present invention relates to this type of wireless packet communication method.

[Conventional technology]

Conventionally, a data transmission method from a wireless terminal includes a contention method and a polling method. Examples of the contention method include the Aloha method and the ISMA method.

[Problems to be solved by the invention]

However, in the contention method, Aloha method, ISMA
In any of the methods, collisions are unavoidable because a plurality of wireless terminals transmit data competitively, and there is a problem particularly when the transmission data is long. On the other hand, in the polling method, no collision occurs because each wireless terminal is sequentially called and only that terminal is allowed to transmit data.However, since polling is performed for terminals having no transmission data, invalid calls are likely to occur when the number of wireless terminals increases. Therefore, there is a disadvantage that the use efficiency of the wireless channel is reduced.

When transmitting data to the wireless terminals, if the wireless terminals are divided into several groups, a method of transmitting data only within the own group is usually used. For this reason, when the data length is long, one data is not enough, and when the order of the own group passes through another group, the wireless terminal number of the transmission destination is written again in the column of the incoming call display signal. There is a drawback in that data must be transmitted and transmitted, and it takes time to transmit all data.

Further, in a method of simultaneously transmitting and receiving uplink data from the terminal to the control station and downlink data from the control station to the terminal,
When each uplink signal such as an uplink data signal polling request signal, no data signal, and a confirmation signal is generated irregularly, they collide with each other, and there is a problem that a time during which nothing can be transmitted occurs, resulting in poor efficiency.

The object of the present invention is to solve the disadvantages and problems of the prior art,
It is an object of the present invention to provide a wireless packet communication method in which data transmitted from a plurality of wireless terminals do not collide with each other and can increase the use efficiency of a wireless channel.

[Means for solving the problem]

To achieve the above object, according to the present invention, in a wireless packet communication method for performing communication between a control station and a plurality of wireless terminals via a time-division wireless line, a downlink signal transmitted from the control station to the wireless terminal is provided. The frame includes at least a first frame including an incoming call display signal, a polling control signal, and an idle / busy signal, and at least a second frame including data, a polling control signal, and an idle / busy signal. The upstream signal frame transmitted to the station is constituted by a frame including at least one of a confirmation signal, a no data signal, and a polling request signal, and a frame length between the upstream and downstream signal frames is substantially an integer. A double relationship has been added to prevent waste (empty period).

[Action]

The wireless terminal normally turns on its power and takes a standby state for reception only during a period during which the first frame from the control station can be received, but turns off its power during the other periods to disable reception. When transmitting data from the control station to the wireless terminal, first, the control station displays the terminal of the wireless terminal that is the data transmission destination in the field of the incoming call indication signal in the first frame. By writing the number and sending out the first frame, the terminal that has received it knows that there is an incoming call to its own terminal,
The control station shifts to a state of receiving a second frame including data, and then the control station writes required data in the second frame, transmits the data, and causes the wireless terminal to receive the data. When transmitting data, the wireless terminal confirms that the column of the idle / busy signal in the first or second frame received from the control station at the time of data transmission is empty, 1st or 2nd
When it is confirmed from the polling control signal column in the frame that no other wireless terminal has made a polling request, the wireless terminal creates an uplink frame including the polling request signal and sends it to the control station, Receives this, finds out the wireless terminal that has made the polling request, writes the terminal number of the wireless terminal in the polling control signal column in the first and second frames, and sends it out to poll the wireless terminal. Thus, only the terminal creates an uplink frame including data and sends it to the control station.

〔Example〕

 Next, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing a configuration example of a control station used in one embodiment of the present invention.

In the figure, 1 is a control station, 101 is a processor, 102 is a memory, 103 is an I / O port, 104 is a modem, 105 is a modulator,
106 is a demodulator, 107 is a transmitter, 108 is a receiver, and 109 is an antenna.

FIG. 2 is a block diagram showing a configuration example of a wireless terminal used in one embodiment of the present invention.

In the figure, 2 is a wireless terminal, 201 is a processor, 202
Is a keyboard, 203 is a display device, 204 is a speaker, 205 is I
/ O port, 206 is a modulator, 207 is a demodulator, 208 is a transmitter, 2
09 is a receiver, 210 is a memory, 211 is an antenna, and 212 is a timer.

FIG. 3 is an explanatory diagram showing a frame configuration of a signal transmitted and received between a control station and a wireless terminal and a mutual positional relationship between the respective frames. Here, the downlink signal is a signal transmitted from the control station to the radio terminal, the uplink signal is a signal transmitted from the radio terminal to the control station, and the transmitted signal examples are the downlink signal frame and the uplink signal frame. They are shown as (1) to (4).

FIG. 4 is an explanatory diagram showing an example of a downlink signal configuration when a plurality of wireless terminals are grouped. FIG. 5 is a flow chart showing an example of an idle / busy signal control flow in the control station, and FIG. 6 is a flow chart showing an example of a control flow when transmitting downlink data.

 The operation will be described below with reference to the drawings.

The processor 101 in the control station 1 shown in FIG. 1 passes through an I / O port 103, a modulator 105, a transmitter 107, and an antenna 109,
The downstream signal frame shown in FIG. 3 is transmitted.

In the downstream signal frame, SYN1 is a synchronization signal, CN and
PN is a polling control signal, CN is a control code, and PN is a terminal number. The CN has functions such as presence / absence of polling and reception confirmation of uplink data. SN1 to SNn are incoming call display signals, and up to n wireless terminal numbers can be written in this column and transmitted. BIS is an empty / busy signal and controls transmission of an upstream polling request signal. SYN2 is a synchronization signal different from SYN1, and DATA (1) and DATA (2) are downlink data.

The downstream signal is configured by repeating one CI frame (incoming display frame) starting with SYN1 and m DT frames (data frames) starting with SYN2. In general, m
Is preferably in relation to the number n of SNs in the incoming call indication signal, m ≧ n, and usually m = n.

The wireless terminal 2 shown in FIG. 2 normally receives only the CI frame from the downlink signal frames shown in FIG. That is, the wireless terminal 2 uses the processor 201 to first detect the CI frame synchronization signal SYN1 from the downlink signal received via the antenna 211, the receiver 209, the demodulator 207, and the I / O port 205. , And the subsequent SN1 to SNn are received, and it is detected whether or not their own terminal number is in it. If there is, it means that there is an incoming call to the own terminal, otherwise it means that there is no incoming call. Therefore, after that, only the timer 212 is operated and the power supplies of the remaining 201 to 210 are turned off thereafter.

The timer 212 counts the timing until the CI frame appears again in the downlink signal, and at that time, turns on the power of the wireless terminal 2 again to enable the reception of the CI frame. In this way, the life of the battery can be greatly extended.

Next, an operation example of transmitting data from a control station to a wireless terminal by a downlink signal will be described.

In FIG. 1, when data is received by the wireless terminal 2 from another device via the modem 104, the processor 101 temporarily stores the data in the memory 102, and first stores the data in one of SN1 to SNn of the CI frame. Write the terminal number and send. The wireless terminal number is written again to the SN of the next succeeding DT frame and transmitted, and the data is transferred to DATA (1) and DATA (2).
And send it. SN1 to S with n DT frames
If Nn is supported, the SN is unnecessary and can be identified in the order of the DT frame. If there is a large amount of data to be transmitted, data is transmitted in the same manner using the next DT frame.

As described above, the wireless terminal 2 always receives only the CI frame, but includes the call indication signals SN1 to S
When detecting the own terminal number somewhere in the column of Nn, it knows that there is an incoming call to the own terminal, so it is decided to continue receiving the signal, receive the data with the own terminal number in the SN in the DT frame, A frame including a confirmation signal is created and transmitted at the position (timing) shown in the example (1) of the upstream signal in FIG. 3 (a dotted line indicates a position where the confirmation signal can be transmitted).

The acknowledgment signal is transmitted via the I / O port 205, the modulator 206, the transmitter 208, and the antenna 211 in FIG. 2, and the antenna 109, the receiver 108, the demodulator 106, and the I / O in the control station 1 in FIG. / O
The data is received by the processor 101 via the port 103. If the acknowledgment signal does not come, the processor 101 writes the terminal number again in any of the columns of the call indication signals SN1 to SNn in the CI frame and sends it out, and retransmits the data in the DT frame.

In this retransmission procedure, if a frame number is added to retransmission data and the same number is added to the confirmation signal, a large number of DTs can be obtained.
When a frame is transmitted, there is an advantage that whether the DT frame is correctly transmitted and which data needs to be retransmitted is not ambiguous in the processor 101. Also, if the wireless terminal has the frame number, it is possible to save one when the same data is received twice. The wireless terminal that has received the data correctly sounds the speaker 204 to notify the terminal holder of the data reception, and displays the received data on the display device 203.

The above description has been made for the case of one type of CI frame. However, in order to further save the battery of the wireless terminal, a method of dividing the wireless terminal into a plurality of groups and providing a CI frame corresponding to each group is considered. Can be That is, the wireless terminals belonging to the first group always receive only the first CI frame, and the wireless terminals belonging to the second group always receive only the second CI frame. 3
FIG. 4 shows an example in the case of grouping.

The details of the CI frame and the DT frame are the same as those of the downlink signal example in FIG. 3, but it is desirable that the synchronization signal SYN1 be different so that each CI can be identified. Since the wireless terminal always receives only the CI frame of its own group, the three groups of FIG. 4 can save three times the battery as compared to the case where the wireless terminals are not grouped. In such a case, transmission of data to the wireless terminal is performed by grouping the wireless terminal with the processor 10.
1 identifies, writes the wireless terminal number in the CI frame of the group and transmits the data, and transmits the data in the DT frame of the group. If the transmission data is long, the DT frame of the group following the CI frame may be insufficient. In this case, if the terminal number is written in the own CI group and transmitted again, and the data is transmitted, it takes time until the transmission of the data is completed. In order to avoid this, there is a method of transmitting data by freely using the DATA frame of another group without writing the terminal number again in the CI frame and transmitting the subsequent data.

Next, transmission of data from the wireless terminal 2 to the control station 1 will be described.

When the wireless terminal 2 creates data using the keyboard 202 shown in FIG. 2 and presses a transmission key (not shown) on the keyboard, the processor 201 receives a downlink signal, and outputs a vacant / busy signal (BIS ) Column is empty or the polling control signal control code (CN) column detects no polling, the I / O port 205,
A frame including a polling request signal is created and transmitted via the modulator 206, the transmitter 208, and the antenna 211 as shown in an example (2) of an uplink signal in FIG. 3 (dotted lines indicate positions where the polling request signal can be transmitted). ).

When this polling request signal is transmitted from the antenna 211 and received by the processor 101 of the control station 1 via the antenna 109 of the control station 1 shown in FIG.
Writes a polling control signal in the CN and PN columns in the CI frame and the DT frame and sends it out. That is, the control code CN
Is polled, and the wireless terminal number is written in the PN and transmitted.

The wireless terminal that has received this signal creates and transmits a frame including data as shown in an example (3) of an uplink signal in FIG. If the control station 1 can receive this signal normally,
A confirmation code is written in the next column of control code CN and returned. If the wireless terminal 2 does not receive this confirmation code, the wireless terminal 2 retransmits data by polling the next terminal itself. If a large amount of transmission data cannot be transmitted, data is continuously transmitted by polling the next terminal. When polling from the control station 1 has been received, but there is no transmission data, a frame including a data absence signal is created and transmitted at the position (timing) shown in the uplink signal example (4) in FIG.

The upstream signals in this system are all in the example shown in FIG. Since these signals are transmitted from a large number of wireless terminals within the same wireless channel, it is desired to have a configuration that does not cause collision and that is not wasted in terms of time.

In this method, the position (timing) of the uplink signal is determined under the following conditions.

In order to guarantee the temporal independence of uplink data and downlink data, the position of the acknowledgment signal for downlink data is fixed, and other uplink signals are not used.

The same position is used for the polling request signal, data signal, and no data signal, but the polling request signal length is about 2
The double is defined as the upstream data signal length so that no invalid time occurs.

The length of the no-data signal is equal to or shorter than the length of the polling request signal, the control station confirms that the signal is a no-data signal, the empty / busy signal is emptied, the terminal identifies the signal, and the polling request signal can be transmitted. To do.

The sum of the uplink data signal length and the acknowledgment signal length is almost equal to the downlink CI frame and DT frame lengths, and there is no collision and the invalid time is reduced.

The uplink data signal and the no-data signal are transmitted only by the polled terminal, and therefore do not collide with other signals. However, since the polling request signal is transmitted independently from the wireless terminal, there is a possibility that the signal will collide with another signal. The idle / busy signal and the polling signal are used to control this. That is, if there is an upstream data signal, the column of the idle / busy signal is closed,
Transmission of the polling request signal is disabled. Also, even if polling is enabled in the CN code column of the polling signal, transmission of the polling request signal is disabled. Control station 1
FIG. 5 shows the control flow of the idle / busy signal in FIG.

It is considered that the communication between the wireless terminal and the control station often involves not only transmission of data from one side to the other side but also conversational communication. For example, such a case as a response to an inquiry. When the control station transmits downlink data in response to uplink data, there is a method of performing transmission in accordance with the above-described downlink data transmission method. That is, compatible with wireless terminals
This is a method in which an incoming call display signal is first written and transmitted in a CI frame, and then downlink data is transmitted in a DT frame.

However, in this method, it is necessary to wait until the transmission of the downlink data reaches the position of the CI frame, and when the terminals are grouped, there may be a considerable delay. The purpose of the incoming call indication signal using the CI frame is to notify a terminal that has been turned off except for a predetermined short period of time to receive a call to save battery power. However, since the terminal that has made the polling request and received the polling signal has turned on the power in advance, it is possible to receive data only with the DT frame without receiving the incoming call indication signal. However, for that purpose, a terminal number indicating which terminal is to be received is required in the DT frame, and the SN column can be used in this method.

In the control station, since the number of the wireless terminal requesting the polling is registered in the memory 102 of FIG. 1, the transmission of the incoming data to the terminal performing the polling registration is performed by the own station and the other groups.
Regardless of any of the DT frames,
Write the terminal number in the SN column and send it out.
This can be done with the TA signal. The control flow in the processor 101 is shown in FIG.

FIG. 6 shows that the long downlink data described above is used for the DT of another group.
It is a downlink data transmission control flow including the case of transmitting over a frame. To the terminal requesting polling, an incoming call is displayed in the CI frame of the terminal group, and data is transmitted in the DT frame of the group.If the DT frame is full of data to another terminal, the next group is transmitted. Of DT frames is also possible. When an incoming call is displayed in the CI frame and the data is transmitted, if the confirmation signal of the first transmitted data is not received, the incoming call display may not reach, so it is desirable to retransmit from the incoming call display.

〔The invention's effect〕

As described above, the transmission of the downlink data is performed by notifying the incoming call to the wireless terminal which is always in a receiving state only for a certain period of time to save the battery by the incoming call display signal at first,
After that, the method of sending data in DATA frame is adopted,
For data that cannot be sent out in one DATA frame or for terminals that have registered for polling, do not write the terminal number in the incoming call indication signal column and send it out again. Is also used, so that the time until all data is transmitted can be reduced.

In addition, since a wireless terminal requesting data transmission sends a polling request signal in advance and the control station polls only that wireless terminal, the probability of collision is extremely low compared to a general contention method, but invalid This is an extremely efficient method because there is little polling, and the relationship between the frame length of each signal and its transmission position (timing) is set so that no invalid time occurs in the wireless channel. Data entry, database access, transmission of messages between wireless terminals, etc., which use one wireless channel all in duplicate and transmit / receive data between many wireless terminals and control stations. It is valid.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration example of a radio terminal used in the present invention, FIG. 2 is a block diagram showing a configuration example of a control station used in the present invention, and FIG. 3 is a configuration example of a downlink signal frame and an uplink signal frame. FIG. 4 is an explanatory diagram showing a configuration example of a downlink signal frame when wireless terminals are grouped, and FIG. 5 is a flowchart showing an idle / busy signal control flow in a control station. FIG. 6 is a flow chart showing a transmission control flow of long downlink data. EXPLANATION OF SYMBOLS 101: Processor, 102: Memory, 103: I / O port, 104: Modem, 105: Modulator, 106: Demodulator, 1
07 ... Transmitter, 108 ... Receiver, 109 ... Antenna, 201
... Processor, 202 Keyboard, 203 Display device, 204 Speaker 205 I / O port 206 Modulator 207 Demodulator 208 Transmitter 209 Reception Machine, 2
10 …… Memory, 211 …… Antenna, 212 …… Timer

Continuing from the front page (72) Inventor Junki Shinagawa 1-6, Uchisaiwaicho, Chiyoda-ku, Tokyo Nippon Telegraph and Telephone Corporation Examiner Isao Tachikawa (56) References JP-A-60-27252 (JP, A) JP-A-50-87707 (JP, A) JP-A-61-281642 (JP, A) JP-A-57-81745 (JP, A)

Claims (1)

(57) [Claims] In a wireless packet communication method for performing communication between a control station and a plurality of wireless terminals via a time-division wireless line, at least a downlink signal frame transmitted from the control station to the wireless terminal is received. A first frame including a call indication signal, a polling control signal, and an idle / busy signal; a second frame including at least data, a polling control signal, and an idle / busy signal;
The uplink signal frame transmitted from the wireless terminal to the control station is configured by a frame including at least a confirmation signal, no data signal, any one of the polling request signal, between the uplink, downlink signal frame The frame lengths are set to be substantially integral multiples of each other, and the radio terminal normally turns on its power and sets the reception standby mode only during the period in which the first frame from the control station can be received. However, during the rest of the period, the power is turned off and the system is controlled to be in a state of being unable to receive. When transmitting data from the control station to the wireless terminal, first,
The control station writes the terminal number of the wireless terminal to which the data is to be transmitted in the column of the incoming call indication signal in the first frame, and transmits the first frame. Knowing that there is an incoming call, the mobile station shifts to a state of receiving a second frame including data, and then the control station writes and transmits necessary data to the second frame and sends it to the wireless terminal. When transmitting data to the control station from the wireless terminal, confirm that the empty / busy signal column in the first or second frame received from the control station by the wireless terminal at the time of data transmission is empty. After confirming that no other wireless terminal has made a polling request from the polling control signal column in the first or second frame received from the control station, An uplink frame including a request signal is created and transmitted to the control station. The control station receives the information and finds out the wireless terminal having the polling request, and displays the corresponding polling control signal field in the first and second frames. The wireless terminal is polled by writing and transmitting the terminal number of the wireless terminal, so that only the terminal creates an uplink frame including data and transmits it to the control station. Packet communication method.