JPH07118674B2 - Communication method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention is a broadcast in which a master station and a plurality of slave stations are connected via the same transmission medium, and communication from the master station to all slave stations is possible. The present invention relates to a multi-point type communication system configured using a multi-type channel and a multi-access type channel capable of communicating from all slave stations to a master station.

(Problems of Prior Art) In a multipoint type communication method, a polling method in which a master station sequentially sends a transmission command to a slave station and the slave station sends information according to the command is well known. However, in this method, the master station sends polling to the slave station, and other slave stations cannot be polled until a reply from the slave station that receives the polling arrives. When applied, there arises a problem that the use efficiency of the transmission line is significantly reduced.

On the other hand, by using the reservation information from the slave station to the master station, it is possible to send a transmission command from the master station to the slave station before receiving a response from the slave station, and improve the above problems, It is possible to realize a communication method with high usage efficiency of the transmission path. However, even in this method, polling is performed on the slave station that is registered for communication, so that a procedure for newly registering a station that is not registered in the polling group is required.

(Object of the Invention) An object of the present invention is to provide a communication system capable of efficiently entering a new unregistered station in the polling system for satellite lines.

(Structure of the Invention) The present invention relates to a broadcasting-type channel in which a master station and a plurality of slave stations are connected via the same transmission medium, and which enables communication from the master station to all slave stations, and from all slave stations. In a network configured using multiple access type channels capable of communicating with the master station, the master station recognizes the transmission request to each slave station that has already been registered with a preset access control channel, and the total communication capacity In a communication system that sends information to the broadcast type channel to instruct each slave station to transmit sequentially in conformity with the above, the master station uses new specific instruction information to register unregistered slave stations. The slave station, which has transmitted the information for instructing the entry of the participating station and has not yet registered and wishes to register, simultaneously transmits a new entry signal including the identification number of the own station in accordance with the specific instruction information, and the specific instruction information. The signal sent according to The communication system is characterized in that the station corresponding to the identification signal is registered when received, and the transmission instruction is sequentially received similarly to the already registered station.

(Embodiment) FIG. 4 is an example of a communication form of a communication system on which the present invention is based. In the figure, one master station and a plurality of slave stations can communicate with each other via one satellite. Usually, the master station uses a larger antenna than the slave station to transmit a high power signal and receive a low power signal so that the slave station can transmit and receive with a small antenna. Therefore, the slave stations cannot communicate with each other, and there are multiple access channels from the slave stations to the master station (hereinafter referred to as uplink) and broadcast channels from the master station to the slave stations (hereinafter referred to as downlink). . In this example, both lines have a line speed of 56 Kbps.

FIG. 5 is a diagram showing an uplink frame format in this embodiment. The frame includes a reserved frame and an information frame, each of which is a unit transmitted from one child station. In the figure, the guard time is a non-transmission time for adjusting the transmissions from the respective slave stations so that they do not overlap due to timing deviation and the like, and consists of 4 bits. The preamble is a section for transmitting a signal for synchronizing timing etc. on the receiving side and consists of 44 bits, the address is a section for transmitting the address of the own station and consists of 16 bits, and the control is reserved or not. , Is a section showing control information such as the reservation length and is made up of 16 bits, and FCS is a redundant bit string for error detection on the receiving side and made up of 16 bits. In addition, a variable-length information section consisting of an integral multiple of 96 bits is added to the information frame. Therefore, both frames are composed of an integral multiple of 96 bits.

FIG. 6 is a diagram showing how to use the downlink. In the downlink, the channel is divided into an access control channel and an information transmission channel by time division multiplexing. Specifically, as shown in the figure, a channel for access control is cut out at a rate of 1 bit per 8 bits. 49Kb for the remaining 7 bits
Used as a channel for sending ps information. On the other hand, the access channels are further grouped into 12-bit units to form one confirmation frame. The confirmation frame includes a 1-bit synchronization bit, an 8-bit address part, a 2-bit control part, and a 1-bit parity bit. The synchronization bit is used to extract 1 bit from 8 bits in TDM and to secure the frame synchronization of the access channel. This sync bit is added once every 12 bits in the access channel, so the original 56Kbps
In this line, the sync bit appears once every 96 bits. This is the same as the length of the reserved frame in the uplink, and the information frame is also an integral multiple of this. Therefore, if each slave station transmits a frame at an appropriate timing in synchronization with the downlink periodic bit, the frame can be transmitted without causing a collision. Further, the address part indicates a destination address, and when the destination is its own station, each slave station receives the frame and decodes the control part. The control section shows information indicating whether the frame to be transmitted next from the slave station is a reserved frame or an information frame.

FIG. 1 is a sequence diagram showing the transmission state of each frame. In the figure, the flow of time is shown on the right side. The arrows indicate the transmission status of each frame.
Ri (k) is a reservation frame issued from the i-th slave station for reserving k slots, and Di (k) is from the i-th slave station containing reservation information for reserving k slots. Ai (x) is an information frame to be output, Ai (x) is a confirmation frame to be output to the i-th slave station, and x is an identifier indicating whether or not it is a reserved frame. Here, the case where the number of slave stations is N stations is shown. In the initial state, no reservation is made. First, the master station sequentially transmits confirmation frames requesting transmission of reserved frames at 96-bit intervals. Each slave station fills in the length of the information frame to be transmitted next to the reservation frame based on the confirmation frame transmitted to itself and transmits it. In this example, the first station is 1 and the second station is 2.
The third station is making three requests. In the master station, if this reservation frame is received and the transmission of N confirmation frames has already been completed at that point, immediately before the completion, if it is before completion, the completion of the confirmation frame is awaited and a new confirmation frame is transmitted. In this case, since the first, second and third stations are all reserved, the identifier x is transmitted as 1. The transmission interval is set to twice the number of 96 bits between the first and the second and three times the number of 96 bits between the second and the third depending on the reserved amount. Each slave station sequentially transmits information frames by receiving the frame. If the length of the information frame is determined according to the previously reserved amount, the slave stations do not collide with each other. That is, the first station transmits a frame having a length twice as long as 96 bits, and at the end of the frame, the information frame due to the arrival of the confirmation frame is transmitted from the second station. In each information frame, the next reservation information is added at the same time as the information transmission, in the same manner as the reservation frame. The reception of these frames by the master station completes a round of communication of information from the slave station to the master station. Also,
The reservation information added to this frame is decoded by the master station and used again for transmitting the confirmation frame. Compared with the previous polling cycle, the polling cycle becomes longer as the information is added, and the delay until the transmission of the next confirmation frame increases. Considering that the transmission of the confirmation frame in the downlink frame corresponds to the transmission of each frame in the uplink, the longer polling period means that the proportion of information frames has increased, and the transmission efficiency in the downlink has increased. Means improvement. That is, in this communication method, the transmission efficiency can be improved as the amount of information increases. Also, k is 0 in each frame of the uplink.
Means that there is no information to be reserved, and in this case, k = 0 in the corresponding confirmation frame.

Next, the operation of the slave station and the master station in the present invention will be described. Second
The figure is an example of a slave station. In the figure, a downlink signal is input from terminal 1. The signal input from the terminal 1 is received by the receiver 5 to obtain a received signal. The received signal is input to the sync detection circuit 7 and the sync bit generated once every 96 bits is detected. A clock that is seven times that of the synchronization information is generated and supplied to the demultiplexing circuit 6. The demultiplexing circuit 6 separates the received signal into a 49 Kbps information sequence and a 7 Kbps confirmation frame sequence based on the synchronous clock, the information sequence is output from the terminal 2, and the confirmation frame is supplied to the address detection circuit 9. . The address detection circuit 9 detects the address portion based on the synchronization information supplied from the synchronization detection circuit 7 and judges whether or not the contents are addressed to the own station, and discards those other than those addressed to the own station. When the frame addressed to the own station is received, the control signal decoding circuit decodes the control unit. In the reservation information storage circuit 11, the amount of information input from the terminal 3 to the buffer circuit 12 is written. When the transmission of the signal reservation frame from the control signal decoding circuit 10 is instructed, the entire amount stored in the buffer is reserved, and when the transmission of the information frame is instructed, the remaining amount of the previously reserved amount is reserved. Make a reservation for the amount of. The frame creating circuit 13 creates a reserved frame or an information frame based on an instruction from the control signal decoding circuit 10. The reservation frame is created using the reservation information input from the reservation information storage circuit 11, and the information frame is created using the reservation information and the information stored in the buffer. The created frame is converted by the transmitter 14 into a transmission waveform and transmitted. The transmission timing at this time is determined as follows. Based on the synchronization signal output from the synchronization detection circuit 7, the delay circuit 8 outputs the transmission timing information after a predetermined delay if this is to be received by the slave station.
The frame is transmitted based on this timing information.

Next, the operation of the master station will be described with reference to FIG. The uplink signal is input from the terminal 101 and received by the receiver 105. The receiver 105 performs timing detection using the preamble, detection of the demodulation carrier phase, etc., and outputs the frame from which the preamble has been removed. The output frame is checked by the frame decoding circuit 106 for FCS, the transmission address detection reservation information is detected, and the original information is output through the terminal 102. The decoded transmission address and reservation information are input to the transmission timing detection circuit 107. The transmission timing detection circuit 107 calculates the timing of transmitting the confirmation frame based on the reservation information. The frame creation circuit 108 creates a confirmation frame using the reservation information and the address at the designated timing, and the multiplexing circuit 109 multiplexes the transmission information input from the terminal 103 with 1 bit per 8 bits. To be done. The multiplexed bit string is converted by the transmitter 110 into a transmission waveform, and the
It is transmitted to the downlink via 04.

The above is the communication procedure between the master station and the slave stations already registered in the master station. Next, a procedure will be described in which a slave station that is not yet registered in the master station and is not polled registers and enters polling synchronization.

The master station shown in the configuration of FIG. 3 sends designation instruction information for instructing the transmission of a new entry station (a station not polled but a polling desired station) in the frame generation circuit 108 in addition to the normal polling cycle. It is sent to a broadcast channel and transmitted to all slave stations. RI transmitted from the master station at the right end of Fig. 1
The A signal indicates this. At the first RIA signal, the XX station adds the identification number of its own station, and the new entry signal fortunately arrives at the master station without causing a collision with other unregistered stations, so that it will enter the polling cycle from the next time. . At this time, the master station confirms the delivery of the R _xx (1) signal by the method of returning an ACK signal to the signal R _xx (1) from the XX station and whether or not the slave station itself enters the polling cycle without doing anything. A method can be considered.
With respect to the specific instruction information RIA transmitted for the second time in FIG. 1, three stations xy, xz, zz simultaneously enter new entry signals R _xy (1), R
_{Since xz} (1) and R _zz (1) were sent, a collision occurred and the master station could not receive, and this new entry could not be admitted. When the subsequent specific instruction information RIA is transmitted from the master station, the new entry signal is transmitted again in a distributed manner.

(Effects of the Invention) As described above, according to the present invention, by adding reservation information to the polling method, it is possible to newly perform polling in a communication method capable of realizing communication with high transmission efficiency even in a form with a large transmission delay. This is a method for reasonably accommodating a desired unregistered slave station in the polling group. In other words, polling is not performed for slave stations that do not wish to poll at this time. The cycle becomes shorter accordingly.

[Brief description of drawings]

FIG. 1 is a sequence diagram showing a frame transmission state in the communication system of the present invention, FIG. 2 is a diagram showing an embodiment of a communication device of a slave station of the present invention, and FIG. 3 is a communication of a master station of the present invention. FIG. 4 is a diagram showing an embodiment of an apparatus, FIG. 4 is a diagram showing an example of a communication form to which the present invention is applied, FIG. 5 is a diagram showing a frame format of a multiple access channel, and FIG. 6 is a transmission form of a broadcast type channel. FIG. In the figure, 5 and 105 are receivers, 14 and 110 are transmitters, 6 is a demultiplexing circuit, 7 is a synchronization detection circuit, 8 is a delay circuit, 9 is an address detection circuit, and 10 is a control signal decoding circuit. 11 is a reservation information storage circuit, 12 is a buffer circuit, 13 and 108 are frame creating circuits, 106 is a frame decoding circuit, 107 is a frame detecting circuit, and 109 is a multiplexing circuit. .

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kojiro Watanabe 5-33-1 Shiba, Minato-ku, Tokyo Inside NEC Corporation (56) References JP-A-52-60516 (JP, A) JP-A-SHO 60-25347 (JP, A)

Claims (1)

[Claims] 1. A master station and a plurality of slave stations are connected via the same transmission medium, and a broadcast type channel capable of communicating from the master station to all slave stations and from all slave stations to the master station. In a network configured using multiple access type channels capable of communication, the master station confirms the transmission request of each slave station that has already been registered with the preset access control channel to match the total communication capacity. It is a communication method that sends information to each slave station instructed to sequentially transmit to the broadcast channel, and the master station newly enters to register unregistered slave stations using specific instruction information. The information for instructing the transmission of the station is transmitted, and in the slave station which is unregistered and desires to register, in accordance with the specific instruction information, a new entry signal including the identification number of the own station is simultaneously transmitted, and the specific instruction information is transmitted. The signal sent according to Communication system station, characterized in that it is received by the instruction similar to sequentially transmit the registered registered station corresponding to the identification number when.