JPH11205352A - Communication network system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To appropriately select a channel corresponding to a data transmission state and to provide an optimum data transmission environment by selecting one protocol to be utilized for transmission from plural protocols corresponding to the priority of a packet to be transmitted. SOLUTION: A multi-protocol control part 20 checks the header of a data packet from a high-order layer or a TDMA transmission/reception part 60 and judges whether transmission requested data are data of a strict delay request (real time data) or data of a non-strict delay request (non real time data). As a result, if it is a real time data, the data are sent to the TDMA transmission/reception part 60. If it is a non real time data, the data are sent to a carrier sense multiple access with collision detection (CSMA/CD) transmission part 40. In the case of being informed of a protocol change for a channel from a control station, a channel table 32 is updated. A channel selection part 31 determines a transmission channel in the transmission by a CSMA/CD system.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a data transmission system in a communication network system. More specifically, CSM in a plurality of channels forming a data transmission path
The present invention relates to a communication network system that realizes an optimal data transmission environment by appropriately changing channels of an A / CD system and a TDMA system according to a data transmission state.

[0002]

2. Description of the Related Art The amount of data transmitted through a local area network (LAN) has increased due to an increase in the number of personal computer users and the spread of real-time applications such as video and audio. For this reason, high-speed networks are required. Regarding transmission media,
Advances in fiber optic technology have made it possible to meet these demands.

[0003] However, currently, the most widely used transmission system in LAN is CSMA, which is not suitable for real-time transmission.
/ CD (Carrier Sense Multipl
eAccess with Collision De
protection method). In order to use a real-time application, the transmission delay must be constant. However, the CSMA / CD method is designed based on the idea that transmission is performed when transmission is possible, so that delay cannot be guaranteed. For this reason, non-real-time data transmission such as e-mail and file transfer has few problems, but is not suitable for transmission of real-time data such as moving images and audio.

[0004] Therefore, in order to guarantee transmission delay, a method of giving a transmission / reception terminal the right to occupy a transmission medium is used. For example, TDMA (Time Division Multip) that divides time and occupies a part of the time
le Access) scheme, or FDMA (Frequency Div) that divides the frequency and occupies a part of the frequency.
I.S. Multiple Access Method. However, in such a method, once the occupation starts, the occupation continues even if it is not actually used, so that the use efficiency of the channel is wasted and the communication opportunity of another terminal is robbed. On the other hand, the above-mentioned CSMA / CD system does not have such a problem.

For this reason, the CSMA / CD system and the TDMA
In order to take advantage of the features of the scheme, a scheme has been considered in which both schemes can be used with one transmission medium. For example, in Japanese Patent Application Laid-Open No. 2-98253, "Multimedia Optical Fiber Network" and Japanese Patent Application Laid-Open No. 3-270432, "Local Area Network", a transmission medium is divided into a plurality of channels to be multi-channel, and one channel is a CSMA / CD system. Are fixedly used as the TDMA system or the burst transmission channel system. In this system, real-time data is transmitted by TDMA or burst transmission, and non-real-time data is transmitted by CSMA / CD.

[0006]

However, even if almost no real-time data is transmitted, TDMA
Since the channel of the system cannot be used, the transmission of non-real-time data is performed on one channel for the CSMA / CD system, the data transmission waiting time increases, and the band of the channel cannot be used effectively. . In addition, although the control packet of the TDMA system is transmitted on the channel for the CSMA / CD system, only one channel can be used at that time.
Since the transmission of control packets is delayed, the number of real-time application users cannot be increased.

On the other hand, when the transmission medium is divided into a plurality of channels and the CSMA / CD system is used, both the throughput and the delay characteristics are improved, as described in "Nomura, Okada, Nakanishi," Multiple Channels in Bus-Type Local Area Networks. CSMA / CD system, "Journal of the Institute of Electronics, Information and Communication Engineers, vol. J67-D, no. 9, pp. 949-9.
59, September, 1984, but because the protocol was only the CSMA / CD system, it was not possible to guarantee the transmission delay.

[0008]

In order to solve the above-mentioned problems, a communication network system according to the present invention is a communication network system in which a plurality of terminals are connected by a network, and via a data transmission medium divided into a plurality of channels. In a communication network system in which a packet is transferred between a transmitting station and a receiving station constituting a terminal using a plurality of protocols, and a control station manages the network, the transmitting station stores a protocol used for each of a plurality of channels. A protocol storage unit that changes the content stored in the protocol storage unit in response to a protocol change notification from the control station, and selects one protocol to be used for transmission from a plurality of protocols in accordance with the priority of the transmission packet. Executes transmission using the protocol control means and the selected protocol. A transmitting means, and a channel selecting means for selecting any one of the plurality of channels at the time of transmission when the transmitted packet is a non-priority packet, wherein the receiving station stores a protocol used for each channel. Means, and changes the storage contents held in the protocol storage means in response to a protocol change notification from the control station, and selects one protocol to be used for transmission from a plurality of protocols according to the priority of a packet to be transmitted. Multi-protocol control means, and receiving means for receiving data in a plurality of protocols, the control station, a protocol storage means for storing a use protocol for each channel, and when the transmission packet is a non-priority packet, Channel selection means for selecting any one of a plurality of channels as a transmission channel when transmitting a packet; And changing means for changing the channel protocol according to the transmission amount of the priority packets by the transmitting station, characterized in that it has a notification means for notifying to the connecting result of changing by changing means to the network terminal.

Further, in the communication network system of the present invention, the priority in packet transmission is such that data transmission requiring a real-time transmission and having a strict transmission delay requirement is given a high priority, and transmission delay requirements not requiring a real-time transmission are strict. It is characterized by having a configuration in which no data transmission is set to a low priority, and a data transmission protocol is selected from a plurality of protocols according to the priority and data transmission is executed.

Further, the communication network system according to the present invention is characterized in that the communication network system has a configuration for notifying a terminal connected to the network of channel change information using one channel selected from a plurality of channels. I do.

Further, in the communication network system according to the present invention, it is characterized in that channel change information is notified to a terminal connected to the network using the protocol change channel.

Further, the communication network system according to the present invention has a configuration in which a control channel is provided in the data transmission medium, and information on a change in the protocol of the channel is notified to a terminal connected to the network via the control channel. It is characterized by.

Further, in the communication network system according to the present invention, the data transmission medium is constituted by a wired transmission medium. C for less demanding data transmission
The data transmission is performed by the SMA / CD method.

Further, in the communication network system according to the present invention, the data transmission medium is constituted by a wire transmission medium, and a token passing method is used for data transmission with a strict transmission delay requirement in data transmission via the wire transmission medium. It is characterized in that data transmission with less severe delay requirements is executed by the CSMA / CD method.

Further, in the communication network system according to the present invention, when there is no request for data transmission with a strict transmission delay during data transmission via the data transmission medium, all channels constituting the data transmission medium are set to CSMA / CD.
The control station configures the number of necessary channels in a plurality of channels constituting the data transmission medium in accordance with TDMA in response to a request for data transmission with a severe transmission delay request from the transmitting station.
It is characterized by having a configuration for changing to a system.

Further, in the communication network system according to the present invention, the number of slots required for data transmission with a strict transmission delay request from the transmitting station is detected, and the detected required number of slots is used as a channel constituting a data transmission medium. When the total number of slots of the channel set in the medium TDMA system is exceeded, the control station has a configuration to change the channel used in the CSMA / CD system to the TDMA system.

Further, in the communication network system according to the present invention, among the channels constituting the data transmission medium, 2
When the data transmission of the TDMA system is performed in the above-described plurality of channels, the control station performs the TDMA transmission when the data transmission of which the transmission delay request from the transmission station is severe decreases.
It is characterized in that it has a configuration in which a plurality of channels in which data transmission of the TDMA method is executed are integrated into a smaller number of channels to reduce the number of TDMA method channels.

Further, in the communication network system according to the present invention, at least one of a plurality of channels constituting a data transmission medium has a configuration which is always set as a channel for executing data transmission by the CSMA / CD system. Features.

Further, in the communication network system according to the present invention, the data transmission medium is constituted by a wireless transmission medium, and in the data transmission via the wireless transmission medium, the TDMA system and the transmission delay C for less demanding data transmission
The data transmission is performed by the SMA method.

Further, in the communication network system according to the present invention, the data transmission medium is constituted by a wireless transmission medium. A for less demanding data transmission
It is characterized by having a configuration for executing data transmission by the LOHA method.

[0021]

FIG. 1 shows a configuration example of a communication network according to the present invention. As shown in FIG. 1, the communication network includes a plurality of terminals that perform communication, a plurality of channels that perform data transfer between the terminals, and a control station that controls data transfer. Each terminal communicates with another terminal connected to the network by each data transmission method from each transmission means.

FIG. 2 shows the configuration of the terminal device connected to the network, and each component of the terminal device will be described. The terminal device is a multi-protocol control means 201, a multi-channel control means 202, a TDMA transmission / reception means 20.
3, CSMA / CD transmission means 204, and CSMA / CD
It has a CD receiving means 205.

The multi-protocol control means 201 looks at the header of the data packet sent from the upper layer and
A function of deciding whether to transmit by the / CD method or the TDMA method,
This means has the function of managing the protocol of the channel based on information from the control station.

The multi-channel control means 202 has a function of determining which channel to use when transmitting data transmitted from the transmission control means using the CSMA / CD system.

The TDMA transmitting / receiving means 203 has a function of transmitting data transmitted from the multiprotocol control means by the TDMA method and a function of transmitting data received by the TDMA method to the multiprotocol control means.

The CSMA / CD transmission means 204 converts the data sent from the multi-protocol control means 201 into CSMA / CD data.
This means has a function of transmitting data according to the / CD method.

The CSMA / CD receiving means 205
It has a function of transmitting data received by the / CD method to the multi-protocol control means 201.

The configuration of the control station on the communication network will be described with reference to FIG. The control station includes TDMA channel setting means 301, multi-protocol control means 302,
Multi-channel control means 303, TDMA control means 30
4, CSMA / CD transmission means 305 and CSMA / CD
It has a CD receiving means 306.

The TDMA channel setting means 301 performs the TDM
This is a means having a function of determining the increase or decrease of the channel using the A method. The TDMA control unit 304 is a unit having a function of performing TDMA channel control such as slot assignment. The other units are the same as the units constituting the terminal device described with reference to FIG.

[0030]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the communication network system according to the present invention will be described in detail.

Embodiment 1 Embodiment 1 of the present invention will be described with reference to the drawings. FIG. 1 shows a conceptual diagram of a terminal, a control station, and a communication network in the present embodiment. Each terminal communicates with the CSMA / CD system and the TDMA via a communication network.
It has the ability to send and receive data using the protocol of the system. In this embodiment, the transmission medium is divided into four channels, and the channels are numbered for distinction. (The channel of channel number 1 is CH1, and similarly, CH
2, CH3 and CH4).

Each terminal communicates with CH1, CH2, CH
3. Data can be transmitted and received using each channel of CH4. Each channel is either a channel that transmits and receives using the CSMA / CD method (hereinafter, referred to as a CSMA / CD channel) or a channel that transmits and receives using the TDMA method (hereinafter, referred to as a TDMA channel). Channel division is performed using wavelength division if the transmission medium is an optical fiber, frequency division or code division by spread spectrum if wireless. It is also possible to realize a plurality of twisted pair cables in parallel. Hereinafter, the transmission medium will be described as being wired.

In the TDMA system, time is divided and assigned to terminals, and the divided time is hereinafter referred to as a slot. The number of multiplexes in the TDMA system is determined by the number of slots per channel. Control of the TDMA system such as slot assignment is performed by a control station.

In the initial state, all channel protocols are CSMA / CD. Thereafter, when a terminal requests real-time data transmission, the control station changes one channel to the TDMA system, and then increases or decreases the real-time data transmission, so that the number of TDMA channels increases or decreases. T
No special control channel is provided for the DMA system.
At least one is CSM to use A / CD channel
It must be an A / CD channel.

Further, since there is at least one CSMA / CD channel, a terminal that can only use the CSMA / CD system can connect to the network. Furthermore, even if the control station fails and the TDMA method cannot be used, the CSMA
/ CD communication can be continued.

The manner in which the channel protocol changes in the communication network system of the present invention will be described with reference to FIGS.

In FIG. 4, CH1, CH2, CH3, C
All H4 channels use the CSMA / CD method.

FIG. 5 shows that only the channel CH4 is of the TDMA system. At least one real-time transmission is being performed using this channel CH4, and this state is maintained until the multiplex value of the TDMA system is reached.

FIG. 6 shows channels CH3 and CH4.
Is a TDMA system. This is because the real-time transmission between the terminals further increases from the state of FIG. 5 and it is no longer possible to cope with only one channel.
This is a state where transmission by the TDMA method is performed on two channels by increasing the number of channels.

In the data communication network system of the present invention, as shown in FIGS. 4, 5, and 6, the data transfer mode is switched from the CSMA / CD mode to the TDMA mode, and the channel is changed according to the data transfer state on the network. It is possible to apply an optimal communication method.

Referring to FIG. 7, the configuration of a terminal device for realizing the communication network system of the present invention will be described. FIG. 7 is a block diagram illustrating details of the terminal device.

The terminal device includes an upper layer 10, a multi-protocol control unit 20, a multi-channel control unit 30, a CSMA /
CD transmitter 40, CSMA / CD receiver 50, TDMA
Transmission / reception unit 60, physical interface unit 70, transmission medium 8
It is composed of 0.

The upper layer 10 is a software module corresponding to the OSI third layer (network layer). If there is data to be sent to another terminal, a request is sent to the multiprotocol control unit 20. The upper layer sends the data to the multiprotocol control unit 20 with a header attached. The header includes a bit or a bit string indicating the priority of transmission data.

The multi-protocol control unit 20 looks at the header of the data packet from the upper layer or the TDMA transmission / reception unit 60 and determines whether the data requested to be transmitted is data with a strict delay requirement (real-time data) or not strict. This is for determining whether the data is data (non-real-time data) and can be realized by an LSI or software. If the result of the determination is that the data is real-time data, the TDMA transmitting / receiving unit 6
Send data to 0. C for non real-time data
The data is transmitted to the SMA / CD transmission unit 40. Also, when the control station notifies the change of the channel protocol,
The channel table 32 is updated. The notification of the protocol change is made from the CSMA / CD system to the TDMA system by a CSMA / CD system broadcast packet. Conversely, a change from the TDMA scheme to the CSMA / CD scheme can be recognized by the absence of control packets transmitted at regular intervals on the TDMA scheme channel. When a slot assignment packet is received from the control station, the TDM
The channel number and the slot number of the A system are notified to the TDMA transmission / reception unit 60.

The multi-channel control unit 30 includes a channel selection unit 31 and a channel table 32, and can be realized by a one-chip IC module or the like.

The channel selection unit 31 has a function of determining a transmission channel when transmitting by the CSMA / CD system.
FIG. 9 shows a flowchart for determining a channel.

When there is a transmission request using the CSMA / CD channel (step 901), first, a channel which is a CSMA / CD channel at that time is extracted from the channel table 32 (step 902). Next, the extracted channels are simultaneously subjected to carrier detection (step 903).
If there is no free channel, the process waits for a random time and extracts a channel again (steps 904 and 90).
5). If there is an available channel, one is randomly selected from the available channels (step 906), and the CSMA / CD transmitting unit is notified (step 907).

The channel table 32 is, for example, a table as shown in FIG. 8, and records the correspondence between channel numbers and protocol identifiers. Here, identifier 0 is C
The SMA / CD system and the identifier 1 are the TDMA system. FIG. 10 shows a procedure for updating the contents. When the change of the protocol is recognized by the protocol change notification packet from the control station or the like, if communication is being performed on the channel whose protocol is to be changed, the communication is stopped and the channel table 32 is updated.

The CSMA / CD transmitting section 40 is a module having a function of controlling transmission of data packets by the CSMA / CD method in response to a request from the multiprotocol control section 20, and can be realized by an LSI. Here, the data packet is obtained by packetizing data transmitted from the multiprotocol control unit 20.

The CSMA / CD receiving unit 50 is a module having a function of performing a process related to a data packet received from another terminal by the CSMA / CD method.
Can be realized by

The TDMA transmission / reception section 60 responds to a request from the multiprotocol control section 20 to transmit the TD of the data packet.
Function to control transmission by MA method and TD from other terminals
A module having a function of performing processing related to a data packet received by the MA method, and can be realized by an LSI. When a data packet is received from the multiprotocol control unit 20, a slot request packet having a destination as a control station is sent to the multiprotocol control unit 20. The channel number and the time slot number to be used are notified from the multi-protocol control unit 20.

The physical layer interface unit 50 is connected to the transmission medium 6
0 and an interface portion of the terminal device. If the transmission medium is an optical fiber, it is a light emitting / receiving circuit. The transmission medium 60 is an optical fiber or a twisted pair cable.

FIG. 11 is a block diagram illustrating a detailed configuration of the control station. The control station includes a TDMA channel setting unit 11
0, multi-protocol control unit 120, multi-channel control unit 130, CSMA / CD transmission unit 140, CSMA /
It comprises a CD receiving section 150, a TDMA control section 160, a physical interface section 170, and a transmission medium 180.

The CSMA / CD channel is used for receiving a request for using a channel of the TDMA system and for notifying the processing result. The transmission algorithm at that time is the same as that of the terminal. Further, the TDMA channel setting unit 110 and the TDMA control unit 1
Operations other than 60 are the same as those of the terminal described above,
Description is omitted.

The TDMA channel setting section 110 performs TDMA
A decision is made as to whether to increase or decrease the channel, and to decide which channel to change to the TDMA channel when increasing, and to decide which channel to use as the CSMA / CD channel when decreasing, it can be realized by an LSI or the like.

FIG. 12 shows a flowchart of channel setting by TDMA channel setting section 110.

When a slot allocation request is received from a terminal (step 1201), it is determined whether the current number of TDMA channels can be used (step 1202).
If the slot of the channel which is the current TDMA channel is not used up, the current TDMA channel can be used. Therefore, the TDMA control unit 160 is instructed to allocate a slot, and then the slot number allocated by the TDMA control unit 160 And the channel number is notified to the requesting terminal using a slot allocation packet (step 1203).

If the slots of the channel which is currently the TDMA channel are used up and there is no room for further allocation, it is necessary to further increase the number of TDMA channels. At this time, if only one CSMA / CD channel remains (Yes in step 1204),
Since the channel cannot be a TDMA channel, the requesting terminal is notified that allocation is impossible (step 1205).

When two or more CSMA / CD channels remain, one of them is selected and TDMA
The channel is changed (step 1206), and the channel number to be changed and the identifier of the new protocol are notified to all terminals by a broadcast packet (step 1207). In addition, the TDMA control unit 160 instructs the TDMA control unit 160 to allocate a slot. After that, the TDMA control unit 160 notifies the requesting terminal of the allocated slot and its channel using a slot allocation packet (step 120).
8) Yes. CSMA / CD changing to TDMA channel
There are two ways to select a channel: random selection or a channel with low traffic.

Further, in a state where a plurality of TDMA channels are used, the number of terminals performing communication by the TDMA system is reduced, and the number of currently used slots is compared with the total number of slots in the current TDMA channel. If the slot can be accommodated with fewer channels than the number, the channels are integrated. Figure 1 shows the situation
3, shown in FIG. 14 and FIG. FIG. 16 is a flowchart of the procedure.

FIG. 13 shows channels CH3 and CH4.
Indicates a state used as a TDMA channel,
In this example, multiplexing on one channel is limited to five. Channel CH4 uses all slots and channel CH4
3 uses only slot 1 and slot 2. In this state, channel 4 has no more free slots,
Channel 3 indicates that data transfer is possible in an empty slot.

FIG. 14 shows a state in which a certain time has elapsed from the state of FIG. 13. Slots 2 and 4 of channel CH4 have become empty slots due to the end of communication. In this state, the slots used for CH3 are slots 1 and 2, and the slots used for CH4 are slots 1, 3 and 5. The total number of used slots is 5 slots. In this state, the entire channel is uselessly used.
As shown in 5, the slot is rearranged in the channel CH4.
At this time, a slot having a smaller slot number in CH3 is assigned to a slot having a smaller number among empty slots in CH4, so that there is no significant fluctuation in delay due to rearrangement.

In the TDMA system, a control packet is transmitted from a control station to a channel at regular intervals.
By not sending the packet to the channel that changes from the TDMA channel to the CSMA / CD channel, all terminals that have not received the control packet for one frame period recognize that the channel has changed from the TDMA channel to the CSMA / CD channel. it can. One frame time is T
This is a slot transmission cycle in the DMA system.

As a result of the rearrangement, the TDMA channel becomes C
A channel number to be changed to an SMA / CD channel;
The change can also be notified by notifying the SMA / CD identifier to all terminals with a broadcast packet using the CSMA / CD channel for the protocol change notification.

The TDMA control unit 160 controls the channel of the TDMA system, and can be realized by an LSI or the like. T
When the use of the DMA method starts, processing such as slot assignment and synchronization is performed.

The flow of FIG. 16 will be described. FIG.
Is an execution flow for switching between the TDMA channel and the CSMA / CD channel. When it is confirmed that the communication executed on the network is completed (step 160).
1, 1602) The slot used for the communication is released (step 1603). Next, step 1
At 604, another TDM is assigned to a channel on the communication network.
It is considered whether the A channel exists. If not (N
In o), in step 1605, it is determined whether or not there is an allocated slot in which communication is continued in the channel, that is, the channel in which data communication for which communication has been completed has been executed (step 1605). If there is an assigned slot (Yes), the process waits for a new communication end. If there is no assigned slot (No), the channel does not need to be a TDMA channel, so that the TDMA channel is changed to a CSMA / CD channel in step 1609.

If it is determined in step 1604 that another TDMA channel exists in the channel on the communication network (Yes), in step 1606, the number of slots of all TDMA channels in the network is calculated. Is compared with “(number of TDMA channels−1) × number of multiplexes”, and if “current number of slots” is smaller than “(number of TDMA channels−1) × number of multiplexes”, The slots are rearranged (Step 1608), and Step 16 is executed.
In 09, the TDMA channel that has become unnecessary due to the rearrangement is switched to the CSMA / CD channel, and transmission of the TDMA control packet on the channel that is no longer a TDMA channel due to the switching is stopped (step 16).
10). If it is determined in step 1607 that the “current number of slots” is not smaller than “(the number of TDMA channels−1) × the number of multiplexes”, step 160 is further performed.
Wait for the end of communication in step 1.

Next, simulation results showing a comparison between the performance of the system of this embodiment and the performance of the conventional system are shown in FIGS.
8 and FIG. The simulation conditions are
It is as shown in the table below.

[0069]

[Table 1] Number of terminals on network: 100 stations, 150 stations Number of channels in channel division: 4 Maximum distance between terminals: 200 m Packet length: 1536 bits Frame time in TDMA system: 5 ms Number of slots in TDMA system: 72 / frame Transmission capacity: 100 Mbps Priority: 2 types (high-priority real-time data and low-priority non-real-time data)

First, the behavior of the prior art and this embodiment will be described using the above simulation conditions. In the prior art,
Of the four channels, non-real-time data is transmitted using only one channel as a CSMA / CD channel, and real-time data is transmitted using the remaining three channels as a TDMA channel. Therefore, even if no real-time data is transmitted, one-time
Only channels can be used.

In this embodiment, one of the four channels is always used for the CSMA / CD system, and the remaining channels are used for the TDMA system or the CSMA / CD system. Therefore, if no real-time data is transmitted, four channels can be used for non-real-time data transmission. Also, when the number of terminals that send real-time data increases, up to three channels can be used for the TDMA system.

In this simulation, when the transmission amount of the non-real-time data is constant, the behavior when the transmission request of the real-time data of each terminal increases is shown for the average transmission waiting time. What is the average latency?
This is the average waiting time between the arrival of data at the transmission buffer and the start of a successful transmission. Also, the difference according to the number of terminals on the network is shown. Here, a network is assumed to be able to accommodate a maximum of 254 terminals, assuming one class C of IP addresses.

FIG. 17 shows the behavior of the average transmission waiting time (ms) of real-time data with respect to the arrival rate of real-time data (the number of data arrivals per second: pieces / second). The arrival rate of the real-time data corresponds to the number of packets transmitted from the upper layer per unit time.

The solid line is the result of the present embodiment, and the dotted line is the result of the prior art. From this figure, it can be seen that this method has a smaller average transmission waiting time. This is because, in the case of the prior art, there is always only one channel through which the control packet flows, and
This is because the packet transmission causes congestion in the CSMA / CD channel, and consequently the timing for starting real-time transmission is delayed. On the other hand, in this embodiment, if there is not enough real-time data, there is an opportunity to use two or more CSMA / CD channels, so that the probability of delaying the start of real-time transmission decreases.

FIG. 18 shows the behavior of the average non-real-time data transmission waiting time (ms) with respect to the arrival rate of real-time data (pieces / second). The average transmission waiting time on the vertical axis is based on the common logarithm. From this figure,
It is apparent that the performance of this embodiment is better. This also comes from the difference in the number of available CSMA / CD channels. Also, as the number of terminals increases, the difference becomes significant.

FIG. 19 shows the behavior of the average non-real-time data transmission waiting time (ms) when the real-time data arrival rate (pieces / second) is small. From this figure, it can be seen that the average transmission waiting time is much shorter in the present embodiment than in the prior art. This is the case in the prior art where 1
This is because all the channels can be used for the CSMA / CD system in the present embodiment, while these channels are used for the TDMA system.

From the above simulation results, it can be seen that the method of the present embodiment has better performance under a heavy load, has a high terminal capacity, and has a particularly small average transmission waiting time under a low load.

[Second Embodiment] Hereinafter, a second embodiment of the communication network system of the present invention will be described.

The configuration of the terminal device in this embodiment has the same configuration as the configuration described in the first embodiment.

In the first embodiment, in order to notify each terminal of the determined TDMA channel, the control station notifies the terminal using the CSMA / CD channel. The algorithm at that time, like the terminal, was to search for a channel with no carrier and send the packet.

In this embodiment, when notifying each terminal of the determined TDMA channel, the notification is made by using the CSMA / CD channel that is to be used as the TDMA system.

The packet used in the present embodiment encapsulates the packet transmitted in the first embodiment (FIG. 2).
2). As shown in FIG. 22, the header of the packet includes
A flag indicating that the packet is transmitted on the TDMA channel can be included. As shown in FIG. 22, setting the flag to 1 indicates that the packet is transmitted on the TDMA channel, and setting the flag to 0 indicates that the packet is CSMA.
/ CD channel.

To execute data transmission on the TDMA channel, the TDMA transmitting / receiving unit 60
And send it. When transmitting on the CSMA / CD channel, the CSMA / CD transmitting unit 40 transmits the packet with a header with this flag set to 0.

The terminal sets the CSMA / CD channel to T
CSMA / CD receiving unit 5 when changing to DMA channel
The operation of 0 will be described with reference to FIG. The control station is the CSM
When changing the A / CD channel to the TDMA channel, the packet with this flag attached to 1 is continuously sent to the CSMA / CD channel which is to be used as the TDMA system. If the terminal is transmitting data on that channel, the data being transmitted will collide, but eventually the CSM
A / CD receiving section 50 sets the channel to TDMA
The channel is recognized by the flag (step 2001). Then, the CSMA / CD receiving unit 50
Indicates that data transmission is being performed (Yes in the determination in step 2002), and the CSMA / CD transmission unit 4
0 (step 2003), and further notifies the multi-protocol control unit 20 that the channel is changed to a TDMA channel (step 2004). The multi-protocol control unit 20 updates the channel table 32 and notifies the TDMA transmission / reception unit 60 of the start of the TDMA control.

Conversely, by setting the flag to 1, CSMA
By indicating that the packet is transmitted to the / CD channel and setting it to 0, the channel may be a TDMA channel, and an arbitrary flag capable of identifying each transmission method can be used.

The terminal sets the CSMA / CD channel to T
The operation of the TDMA transmission / reception unit 60 when changing to the DMA channel will be described with reference to FIG. TDMA transceiver 60
Monitors the TDMA channel (step 210)
1) If no packet with a flag indicating that it is a TDMA channel is received for one frame time (steps 2102 and 2103), the TDMA channel is used.
The communication by the system ends, and the CSM
It determines that the channel has changed to the A / CD channel, and notifies the multi-protocol control unit 120 (step 2104). The multi-protocol control unit 20 updates the channel table 132 and notifies the TDMA transmission / reception unit 160 of the suspension of the TDMA control.

Further, as a method of identifying the method, in addition to the method using the above-mentioned flag, the entire header newly added is T
An embodiment representing either the DMA system or the CSMA / CD system is also conceivable (FIG. 23). If the frame is synchronized by using this header, it is a robust method because it is possible to recognize either method during synchronization.

In the above embodiment, the transmission according to the CSMA / CD method has been described as a protocol for transmitting non-real-time data.
The SMA / CD method cannot be used, but the CSMA method and ALO
Needless to say, the same effect can be obtained by the HA method. The same effect can be obtained even if the token passing method is adopted as a protocol for real-time data transmission.

In the above embodiment, the control channel of the TDMA system does not have a dedicated channel. However, by providing a dedicated channel, the opportunity of non-real-time data transmission can be increased.

[0090]

As described above, according to the communication network system of the present invention, the communication protocol can be flexibly changed according to the increase or decrease of the real-time traffic. Will be able to do.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a terminal, a control station, and a communication network in a first embodiment of a communication network system of the present invention.

FIG. 2 is a configuration diagram of a terminal in the communication network system of the present invention.

FIG. 3 is a configuration diagram of a control station in the communication network system of the present invention.

FIG. 4 is a diagram showing a state of a channel when there is no real-time traffic in the first embodiment of the present invention.

FIG. 5 is a diagram illustrating a state of a channel when there is real-time traffic in the first embodiment of the present invention.

FIG. 6 is a diagram illustrating a state of a channel when there is real-time traffic in the first embodiment of the present invention.

FIG. 7 is a block diagram showing a detailed configuration of a terminal device in the communication network system of the present invention.

FIG. 8 is a diagram showing a configuration example of a channel table in the communication network system of the present invention.

FIG. 9 is a flowchart illustrating an operation of a channel selection unit in the communication network system according to the present invention.

FIG. 10 is a flowchart showing an operation in which a terminal changes a protocol in a communication network system of the present invention.

FIG. 11 is a block diagram showing a detailed configuration of a control station in the communication network system of the present invention.

FIG. 12 is a flowchart showing an operation of a TDMA channel setting unit in the communication network system according to the present invention.

FIG. 13 is a diagram showing a situation in which there are two TDMA channels in the communication network system of the present invention.

FIG. 14 is a diagram showing a state where slots of a TDMA channel are reduced in the communication network system of the present invention.

FIG. 15 is a diagram showing a state where two TDMA channels are integrated into one TDMA channel in the communication network system of the present invention.

FIG. 16 is a flowchart showing the operation of the control station for reducing the TDMA channel in the communication network system of the present invention.

FIG. 17 is a simulation result of an average transmission waiting time of real-time data in the communication network system of the present invention.

FIG. 18 is a simulation result of an average transmission waiting time of non-real-time data in the communication network system of the present invention.

FIG. 19 is a simulation result of average transmission waiting time of non-real-time data when the arrival rate of real-time data is small in the communication network system of the present invention.

FIG. 20 shows a second example of the communication network system of the present invention.
5 is a flowchart illustrating an operation of a CSMA / CD receiving unit in the embodiment.

FIG. 21 shows a second example of the communication network system of the present invention.
5 is a flowchart illustrating an operation of a TDMA transmission / reception unit in the embodiment.

FIG. 22 shows a second example of the communication network system of the present invention.
6 is a packet format used in the embodiment.

FIG. 23 shows a second example of the communication network system of the present invention.
6 is a packet format used in the embodiment.

[Explanation of symbols]

 Reference Signs List 10 Upper layer 110 TDMA channel setting unit 20, 120 Multiprotocol control unit 30, 130 Multichannel control unit 31, 131 Channel selection unit 32, 132 Channel table 40, 140 CSMA / CD transmission unit 50, 150 CSMA / CD reception unit 60 , 160 TDMA control unit 70, 170 Physical layer interface unit 80, 180 Transmission medium

Claims (13)

[Claims] 1. A communication network system in which a plurality of terminals are connected by a network, wherein packet transmission is performed between a transmitting station and a receiving station constituting the terminals by using a plurality of protocols via a data transmission medium divided into a plurality of channels. In the communication network system in which the control station manages the network, the transmitting station, in response to a protocol change notification from the control station, a protocol storage unit that stores a use protocol of each of the plurality of channels. Multi-protocol control means for changing the storage content in the protocol storage means and selecting one protocol to be used for transmission from the plurality of protocols according to the priority of a transmission packet; and transmission using the selected protocol. And the transmission packet is a non-priority packet In this case, the transmission station has channel selection means for selecting any one of the plurality of channels at the time of transmission, the reception station, a protocol storage means for storing a use protocol for each channel, a protocol from the control station Multi-protocol control means for changing storage contents held in the protocol storage means according to the change notification, and selecting one of the plurality of protocols to be used for transmission according to the priority of a packet to be transmitted; and ,
Receiving means for receiving data in a plurality of protocols, the control station stores protocol used for each of the channels, and when the transmission packet is a non-priority packet, Channel selecting means for selecting any one of the channels as a transmission channel, changing means for changing a channel protocol according to the transmission amount of priority packets by the transmitting station, and changing the result by the changing means. A communication means for notifying a terminal connected to the network. 2. The priority in the packet transmission is set such that data transmission with a strict transmission delay request that requires real-time transmission has a high priority, and data transmission that does not require a real-time transmission and has a low transmission delay request has a low priority. 2. The communication network system according to claim 1, wherein a data transmission protocol is selected from the plurality of protocols according to the priority to execute data transmission. 3. The communication network system according to claim 1, wherein a change in channel protocol is notified to a terminal connected to the network using one channel selected from the plurality of channels. The communication network system according to claim 1. 4. The communication according to claim 1, wherein, in the communication network system, channel change information is notified to a terminal connected to the network using the protocol change channel. Network system. 5. The communication network system according to claim 1, wherein the communication network system has a control channel in the data transmission medium, and has a configuration for notifying a terminal connected to the network of the change information of the protocol of the channel via the control channel. The communication network system according to claim 1 or 2, wherein: 6. In the communication network system, the data transmission medium is a wired transmission medium, and a TDMA system and a transmission delay request are used for data transmission with a strict transmission delay requirement in data transmission via the wired transmission medium. CSMA for less severe data transmission
The communication network system according to any one of claims 1 to 5, wherein data transmission is performed by a / CD method. 7. The communication network system, wherein the data transmission medium is a wired transmission medium, and a token passing method and a transmission delay are used for data transmission with a strict transmission delay requirement in data transmission via the wired transmission medium. The communication network system according to any one of claims 1 to 5, wherein data transmission is performed according to the CSMA / CD method for data transmission that is not strictly required. 8. In the communication network system, during the data transmission via the data transmission medium, if there is no request for data transmission with strict transmission delay requirements, all channels constituting the data transmission medium are set to the CSMA / CD system. And wherein the control station changes the required number of channels among a plurality of channels constituting the data transmission medium to the TDMA system in response to a request for data transmission with a strict transmission delay request from the transmission station. The communication network system according to claim 6 or 7, wherein: 9. In the communication network system, a number of slots required for data transmission with a strict transmission delay requirement from the transmitting station is detected, and the detected required number of slots is a channel constituting the data transmission medium. The system according to claim 11, wherein the control station changes the channel used in the CSMA / CD system to the TDMA system when the total number of slots of the channel set in the medium TDMA system is exceeded. 9. The communication network system according to any one of 6 to 8. 10. In the communication network system, when data transmission of the TDMA system is performed in two or more channels among channels constituting the data transmission medium, the control station transmits the data from the transmission station. In the case where data transmission with strict delay requirements is reduced, a plurality of channels in which the TDMA data transmission is being performed are integrated into a smaller number of channels to reduce the number of TDMA channels. The communication network system according to any one of claims 6 to 9, wherein 11. In the communication network system, among a plurality of channels constituting the data transmission medium,
11. The communication network system according to claim 6, wherein at least one channel has a configuration that is always set as a channel for executing data transmission according to the CSMA / CD method. 12. In the communication network system, the data transmission medium is constituted by a wireless transmission medium, and a TDMA system and a transmission delay CSMA for less severe data transmission
The communication network system according to any one of claims 1 to 5, wherein data transmission is performed by a method. 13. In the communication network system, the data transmission medium is constituted by a wireless transmission medium, and the data transmission via the wireless transmission medium requires a TDMA method and a transmission delay ALOH for less demanding data transmission
The communication network system according to any one of claims 1 to 5, wherein the communication network system has a configuration for executing data transmission by the A method.