JP2000244969A - Communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the waste of the assets of a whole system without generating any exceptional processing not by transmitting the information of the temporary disconnection of a data link layer or below and the temporary connection of the re-connection of up to the data link layer to a network layer, and therefore, not by transmitting the information also to the upper layer of the network layer. SOLUTION: In a radio communication system, a ground telephone line between an improved MODEM 11 attached to a user station 2 and a demodulator(DEM) 4 of a center station 1, that is, the line of a data link layer or below repeats disconnection or connection according to the presence or absence of up transmission data. During that time, any layer beyond the network layer of an up line is not disconnected until the end of communication, that is, final line disconnection across the whole layers. In the same way, while at least a line beyond the network layer of the up line is maintained, any down line is not disconnected. Moreover, the factor of the generation of temporary disconnection/temporary connection can be any factor other than the presence or absence of data such as time-out.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a one-to-many communication system including a center station and a user station in the field of wired communication, wireless communication and / or satellite communication.

[0002]

2. Description of the Related Art As a prior art, a center station and one or more user stations that communicate with the center station are provided. The user station selects one channel from a plurality of channel groups and selects the center station. Means for setting and transmitting an uplink to the mobile station, and means for receiving transmission content from the center station via the downlink. The center station transmits transmission content from the user station input from different channels. Means for receiving via the uplink and means for transmitting to the user station via the downlink, and the center station has at least one channel-specific demodulator for each channel of the uplink. ,
At least the downlink is a wireless channel, and there is a communication system having a logical network configuration according to the OSI reference model. Such a system is described in, for example, Nakayama et al., "Multimedia Satellite Communication System (M. Nakayama, et.
al., “A Satellite Communication System for Intera
ctive Multimedia Networks, ”IEICE Trans. Commun.,
Vol.E80-B, No.1 1997.) ".

FIG. 9 is a configuration diagram of a conventional wireless communication system. This system has a center station 1 and a plurality of user stations 2, and between the center station 1 and the user station 2,
The downlink 9 is established via the communication satellite 3, and the uplinks 8 and 10 are established via the terrestrial telephone network 7. At this time, the center station 1 has a demodulator 104 for each uplink and the user station 2 has a commercially available modem 1
11 is provided. The demodulator 104 shown in the figure is a modulator / demodulator because it also has a modulation function. Also,
The center station 1 is connected to the Internet 5 via a gateway GW6. Further, the user station 2 is connected to a user terminal 12 which is a personal computer.

[0004] The wireless communication system shown in FIG. 9 is an up-down asymmetric communication system that uses a small-capacity terrestrial telephone line for the uplink and a large-capacity satellite communication for the downlink. Such an asymmetric communication system is very suitable for Internet access, especially as a multimedia satellite communication system.

Next, the operation of the system shown in FIG. 9 will be described. The user activates the modem 111 of the user station 2 from the user terminal 12 and connects to the demodulator 104 of the center station via the terrestrial telephone network 7. After completing a series of connection procedures including authentication, the user can access the Internet via the GW 6. Next, the user
In order to acquire data from a server on the Internet, a command is issued from an http browser or the like. As a result, downlink data for the command is transmitted from the center station to the user station 2 via the satellite line, and the data is notified to the user terminal 12.

In the present system, the down link is a one-way link in which information flows only in one direction and the reverse does not flow, but the up link carries information only in one direction, but the link itself has both sides. This is a two-way line that allows information to flow in the opposite direction. This is because two-way communication is required in the process of establishing the uplink using the terrestrial telephone line.

Although this system is not constructed and used only in the data communication field, it is assumed that voice communication as well as data communication will be digitized and processed with the progress of digitization in recent years. The number of cases where IP communication is performed is increasing. Therefore, hereinafter, a general data communication, specifically, a multimedia satellite communication system will be described as an example.

First, generally speaking, a data communication system often constructs a logical network according to the OSI reference model. In this model, the physical layer provides a physical line, and the data link layer above it exchanges electrical signals using the physical line to establish the line. Further, an upper network layer exchanges an information unit called a datagram using a line provided by the data link layer. As described above, the OSI reference model employs a hierarchical structure, clearly divides the role of each layer, and suppresses information exchange between layers to the minimum necessary types, amounts, and times.

[0009] Information generated when a physical line is connected or disconnected is usually handled as important information exchanged between layers.
This is because while the physical line is disconnected, the data link layer cannot establish a line and cannot function as its own layer. Therefore, the data link layer reports the line disconnection (state) to a higher network layer. In the OSI reference model,
The layer that has received the line disconnection instruction from the upper layer performs disconnection processing in its own layer, and relays it to the lower layer (physical layer only disconnects). Also, the layer, which has received a report from the lower layer that the line has not been established, instructs the lower layer to reestablish the line and starts executing various exceptional processes such as information retransmission. The execution of the exception processing is not particularly related to whether or not there is actually data to be transmitted and received.

Next, as a specific theory, in the multimedia satellite communication system, the data content of the uplink is based on the user information at the time of network connection and the h issued by the user.
tp browser request, Ack, Nak, and other commands. Therefore, traffic occurs in bursts every several seconds to several minutes, sometimes every tens of minutes, and the information amount of one burst is as small as several tens to several hundred bytes at most.

[0011] In addition, the user always occupies one telephone line and one center station demodulator during the connection time because the uplink line of the conventional system is a circuit-switched terrestrial telephone line. Furthermore, since the downlink is a time-division multiplexed satellite link, all the normally operating user stations continuously share and secure the connection over the entire layer of the OSI reference model during the connection time. .

[0012]

However, in the conventional system, since only traffic having a burst characteristic occurs on the uplink, no data is transferred for most of the time, and therefore, the demodulator of the center station is not transmitted. Is not working most of the time. Also, because the number of demodulators is limited,
An inactive demodulator is a significant waste of system assets. In order to avoid such inconvenience, it is also possible to connect the uplink physical layer line only when there is transmission data and disconnect it when there is no transmission data, according to the traffic characteristics. By doing so, a single center station demodulator can be virtually shared by a plurality of user stations within a range where the communication time zones of the user stations do not overlap, and only when there is transmission data, the ground telephone Since the line is not used, some resources of the system can be effectively used.

However, if disconnection / connection of the uplink physical layer line is performed during one unit of communication, the following problems occur.

First, as a general theory, when the physical layer line is disconnected, the upper layer instructs the line to be re-established and retransmits information regardless of whether there is data to be actually transmitted or received, as described above. Start executing various exception processing such as processing. Therefore, even at the time of connection of the physical layer line, the line establishment procedure up to the uppermost layer is performed endlessly. Also, exception processing is necessary when a physical layer line disconnection occurs when there is data to be transmitted / received. However, when exception processing is performed when there is no data to be transmitted / received, it is actually disconnected. However, the upper layer has to deal with disconnection / connection of the physical layer line without any trouble, which significantly hinders effective use of communication system assets.

Next, as a specific theory, it is pointless that if the upstream line, that is, the terrestrial telephone line connecting the center station (modulator) demodulator and a commercially available modem at the user station is cut off because the traffic has disappeared, the line will be meaningless. Trigger the establishment procedure. If the connection is re-established due to the occurrence of traffic and connection procedures such as line parameter negotiation are performed each time, information transmission in the data link layer and the upper layer will be delayed.

Another problem is that if a terrestrial telephone line is used as an uplink line, the installation location of the user station is limited to the location where the terrestrial telephone line exists, and the portability of the user station is greatly restricted. There is. If the downlink is a satellite link and is within the coverage of the communication beam of the communications satellite, there is virtually no restriction on the location of the user station, and this constraint is attributable only to the characteristics of the uplink.

Accordingly, an object of the present invention is to solve the above-mentioned problems of inefficient use of the demodulator of the center station in the uplink.
An object of the present invention is to provide a wireless communication system that solves the problem of portability of a user station.

[0018]

SUMMARY OF THE INVENTION Accordingly, the communication system of the present invention is characterized in that, after a user station has established an uplink for all layers on a certain channel for communication, the center station transmits an uplink from the user station. Means for disconnecting at least the physical layer line and releasing the demodulator of the center corresponding to the channel, or connecting at least the physical layer line and securing the demodulator corresponding to the channel in accordance with the line control information of The uplink of the network layer or higher is maintained from the establishment of the uplink for all layers until the disconnection of the uplink for all layers by an instruction from the network layer or higher. Is maintained at least from the time when the uplink is established for all layers until the time when the uplink is disconnected for all layers by instructions from layers above the network layer. It is intended to be.

Here, the term "temporary disconnection" means that when data to be transmitted is lost in the user station after the start of one unit of communication, at least physical disconnection is performed using a timeout of a user or a timer designated by the user station. It refers to the act of disconnecting the layer line and instructing the center station to release the demodulator at the center station of the channel. Also, the term "temporary connection" means that when data to be transmitted is generated in the user station while the user station is temporarily disconnected, the demodulator of the center station of a certain channel is used for uplink. This is the act of instructing the center station to secure and reconnect the physical layer line.

Here, the cause of the temporary connection and the temporary disconnection is the presence or absence of data. However, the cause may be the amount of data or the line control information from the center station. Further, for example, it may be possible to cope with a case where the priorities are assigned to the communications from the user stations, or a case where the center station needs to restrict the transmission of the user stations for some reason. Since the downlink is not disconnected during at least one unit of communication, communication from the center station to the user station can be performed at all times.

When the upstream line is a terrestrial telephone line, the disconnection of the physical layer line usually involves the disconnection of the data link layer line. Means reconnection. The most significant feature of the present invention is that the information of the temporary disconnection and the temporary connection is not transmitted to the network layer, and thus is not transmitted to the upper layer of the network layer. This is a difference from the related art in which all disconnection / connection information of the physical layer and the data link layer line is transmitted to an upper layer. In the present invention, since the upper layer is not notified of the temporary disconnection / temporary connection below the data link layer, the exception processing as described above does not occur, and there is an effect that waste of the entire system resources can be avoided. In addition, as the channel of the uplink at the time of temporary connection, a channel available at that time may be used (for example, in the case of IP communication, since the destination is specified for each IP packet, there is no channel dependency). However, it may be different from the channel at the time of temporary disconnection.
That is, the user may use a plurality of different uplink channels (center station demodulators) in a single unit of communication so that they do not overlap in time using temporary disconnection and temporary connection. Moreover, this operation need not be performed by the user. This makes it possible for a plurality of user stations to share one center station demodulator virtually within a range in which the communication time zones of a plurality of user stations do not overlap from the viewpoint of the center station, and to efficiently use demodulator assets. The effect of effective use is obtained.

The method of not transmitting the temporary disconnection and the temporary connection to the network layer depends on the frame structure of the physical layer and the data link layer and the protocol configuration. There are several specific methods. A method of setting a flag indicating a temporary disconnection and a temporary connection to a frame used in the physical layer to prevent reporting to the network layer by hardware,
Although the temporary disconnection and temporary connection are reported to the network layer, the report destination is actually a dummy configured in software, and a method of ignoring the dummy may be considered. The former can be processed only at the physical layer (it can also be processed at the data link layer), and the latter is processed with a virtual network layer (actually regarded as the data link layer) between the data link layer and the network layer It becomes a form to do.

According to another embodiment of the present invention, the center station reports the state of each user station and, for a user station using the uplink, the line characteristics of the uplink, the physical layer line disconnection and connection information. It has a database indicating the state of the uplink including, each user station, the information of the uplink including disconnection and connection information of the physical layer line of the uplink of the own user station, along with the identifier of the own user station, The center station has means for transmitting the data by adding it to the data when using the uplink, and when receiving the data from the uplink, the center station determines the state of the user station recorded in the database and the status of the uplink. Means for matching the line characteristics and information indicating the state of the uplink with the identifier of the user station added to the transmitted data and the information on the uplink of the user station; Shape And has a means to continue the reception process only when accepted without contradiction in. As a result, the line control, user management, and security management can be performed only by the user station notifying its own identifier and the current state of the uplink every transmission.

In the claims, "accepted without contradiction" means that commands, events, and the like issued due to state transitions of the user station and the center station are different, and the commands and events are recorded in the database of the center station. The inconsistency cannot be found when the station status, the uplink line characteristics, and the information indicating the uplink status are matched. In addition, the center station stores a database such as information indicating the state of the user station, the line characteristics of the uplink, and the state of the uplink, so that the user station can determine the destination of the uplink and the transmission content (the destination after the center station). It is also possible to obtain the effect that it is not necessary to consider the correspondence and even if there is a temporary disconnection / temporary connection, the identity of the user station can be proved without sending authentication-specific information. After the temporary disconnection of a certain user station, the center station does not know when and on which channel the temporary connection will occur, which is extremely effective in security management.

According to another embodiment of the present invention, the uplink is a frequency division multiple access wireless link. As a result, the user station only needs to be equipped with a radio transmitter, and the terrestrial telephone line and modem for the uplink are not required, so that the user station can be made smaller and its portability can be increased. In particular, unlike traditional land-line telephone lines,
The uplink may be a one-way line, and the target of temporary disconnection / temporary connection may be only the physical layer line. In this case, temporary disconnection means disconnection of the physical layer line, and temporary connection means reconnection of the physical layer line. However, of course, the data link layer may be targeted.

According to another embodiment of the present invention, the user station can use the channel used for the uplink based on the use status information of the channel for the uplink received from the center station via the downlink. Is determined. By this means, it is possible to know an empty channel at the time of securing the uplink, so that it is possible to improve the channel use efficiency at the time of connection and temporary connection, and to reduce the call loss due to collision. The line control information is a usage status of each channel of the uplink at that time, that is, a list of available free channels. In the conventional system, when the terrestrial telephone line is used for the uplink, the representative number is used, so that it is not necessary to notify such a use condition for each channel. That is, it is a means for contributing to the effective use of the uplink radio line according to the present invention.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, typical embodiments of the present invention will be described in detail.

FIG. 1 is a flowchart of line control in the present invention. FIG. 1 illustrates a control flow of an uplink in a center station after an uplink is established in all layers of a channel between a user station and a center station. As described above, the term "temporary disconnection" in FIG. 1 means that when there is no transmission data in the user station, the user station disconnects the physical layer line to the center station and releases the demodulator corresponding to the uplink line. Refers to the act of instructing Further, as described above, the term "temporary connection" refers to the case where data to be transmitted is generated in the user station when the user station is temporarily disconnected, as described above. To instruct the center station to reconnect the physical layer line again.

Here, the processing flow of FIG. 1 will be described. First, an uplink is established in all layers of the channel between the user station and the center station (C1). Next, when the center station receives the line control communication from the user station on the uplink (C2), it determines whether or not the communication content is a temporary disconnection request (C3). If the request is a temporary disconnection request, the center station executes a temporary disconnection (C4),
A report is sent to the line control function (C5). At this time, a standby state is maintained between the user station and the center station while the line at the network layer or higher is maintained. If the request is not a temporary disconnection request, a report to the line control function is made (C5), and it is determined whether the temporary disconnection is being performed and the request is a temporary connection request (C5).
6). If so, the center station performs a temporary connection (C
7) Waiting for line control communication reception. Otherwise,
It is determined whether or not the content of the communication is a request for disconnecting the uplink in all layers according to an instruction from a layer above the network layer (C8). If so, the center station disconnects the uplink in all layers of the user station (C9), reports to the line control function (C5), and completes one unit of communication (C1).
0). If not, a report to the line control function is made (C5), and a line control communication reception wait is waited.

FIG. 2 is a configuration diagram of the wireless communication system of the present invention. The configuration and operation of this system are the same as those of the conventional wireless communication system described above with reference to FIG. 9 except that the modem of the user station is modified to a special product. However, although a satellite line is used for the down line, a terrestrial wireless line may of course be used.

In the system according to the present invention, the terrestrial telephone line between the modem 11 attached to the user station 2 and the demodulator 4 of the center station 1, that is, the line below the data link layer is disconnected or disconnected depending on the presence or absence of uplink transmission data. Repeat to be connected. In the meantime, the layers above the network layer of the uplink are not disconnected until the end of communication, that is, the final disconnection of the line over all layers. Similarly, the downlink is not disconnected while at least the line above the network layer of the uplink is maintained. The cause of the temporary disconnection / temporary connection may be a factor other than the presence or absence of data such as a timeout.

FIG. 3 is a sequence diagram between devices in which the upstream line is a terrestrial line and the downstream line is a satellite line. Hereinafter, this sequence will be described.

First, the user establishes an uplink and starts Internet access. When the authentication is completed, the user is connected to the target Web site, and the first information request command is transmitted. Thereafter, here, the physical layer line is temporarily disconnected at the discretion of the user station due to the cause of the timeout of the user station. Regarding the disconnection, not only the user but also the communication program (the upper layer of the OSI reference model) on the Internet Web site is not known. However, the demodulator at the center station is open.

Next, the user inputs the ht displayed on the PC.
When a command is issued to the tp browser, the user station starts temporary connection of the physical layer line. When the physical layer line is established again, the previous command is transmitted via the uplink, and the requested information is transmitted using the downlink.
At this time, the uplink channel at the time of temporary connection may use an available channel available at the time of re-establishment, and may be different from the channel at the time of temporary disconnection. Also,
The user may use a plurality of different uplink channels in one unit of communication by using temporary disconnection and temporary connection so as not to overlap in time. Moreover, this operation need not be performed by the user. This means that, from the point of view of the center station, the communication time zones of multiple user stations do not overlap,
One center station demodulator can be virtually shared by a plurality of user stations, and the effect of efficient use of demodulator assets can be obtained. Thereafter, such a sequence is repeated.

Finally, the upper layer line of the OSI reference model is disconnected only when the user issues a final line end command.

FIG. 4 is a configuration diagram of a wireless communication system according to the present invention, in which the up line is also established via a satellite line. Compared with FIG. 2, the modem 11 of the user station 2 is not required because the terrestrial telephone lines (7, 8, 10) are not required.

Next, the center station includes in its database the state of each user station and, for a user station using an uplink, the line characteristics of the uplink, the disconnection and connection information of the physical layer line. Therefore, the information in the database is matched with the line control information from the user station, and it can be determined whether or not the line control information from the user station is consistent with the current state of the user station. .

FIG. 5 is a sequence diagram between apparatuses in which both the uplink and the downlink are satellite links. The disconnection and connection of the physical layer line are performed as compared with FIG.

FIG. 6 is a sequence diagram between the apparatuses in which the center station performs information matching each time the center station receives transmission contents from the user station in the sequence of FIG.
Thus, line control, user management, and security management can be performed only by the user station notifying its own identifier and the current state of the uplink for each transmission.

FIG. 7 is a sequence diagram between the apparatuses for notifying the user station of the uplink channel use information from the center station to the sequence of FIG. The line control information sent from the center station to the user station on the downlink includes the use status of each channel of the uplink at that time, that is, a list of available free channels, and the Since the available channel can be known and the channel to be used can be selected from the available channel, the use efficiency of the channel at the time of connection and temporary connection is greatly improved, and there is an effect of reducing the call loss due to collision.

FIG. 8 is a sequence diagram between the apparatuses that matches the information in the database with the transmitted information on the uplink of the user station in the sequence of FIG. Thus, line control, user management, and security management can be performed only by the user station notifying its own identifier and the current state of the uplink for each transmission.

Various changes, modifications and omissions within the scope of the technical idea and viewpoint of the present invention can be easily made by those skilled in the art. Therefore, the above-described embodiment is merely an example, and is not intended to limit the present invention. The invention is limited only as defined by the appended claims and equivalents thereof.

[0043]

As described in detail above, according to the present invention, since layers above the network layer do not know temporary disconnection / temporary connection below the data link layer, no exception processing occurs, and assets of the entire system do not occur. This has the effect of avoiding waste. Also, the channel of the uplink at the time of temporary connection may be different from the channel at the time of temporary disconnection, since the channel available at that time may be used. That is, the user may use a plurality of different uplink channels (center station demodulators) in a single unit of communication so that they do not overlap in time using temporary disconnection and temporary connection. Moreover, this operation need not be performed by the user. This makes it possible for a plurality of user stations to virtually share one center station demodulator within a range where the communication time zones of a plurality of user stations do not overlap from the viewpoint of the center station, and the efficiency of demodulator assets can be improved. The effect of effective use is obtained.

Also, if the user station has already started one unit of communication and has already secured a physical line, it will not make a request for uplink connection or a temporary connection again, or conversely, a user who has not communicated. When the station sends a request for temporary connection, the center station can immediately determine the inconsistency, so that there is obtained an effect useful for checking the line status, checking the charging information of the user station, reconfirming the identity, and the like. . This is because commands, events, and the like issued according to state transitions of the user station and the center station are different. In addition, the center station stores a database such as information indicating the state of the user station, the line characteristics of the uplink, and the state of the uplink, so that the user station can determine the destination of the uplink and the transmission content (the destination after the center station). It is also possible to obtain the effect that it is not necessary to consider the correspondence and even if there is a temporary disconnection / temporary connection, the identity of the user station can be proved without sending authentication-specific information. After a user station causes a temporary disconnection, the center station does not know when and on which channel the temporary connection will occur.
It is extremely effective in security management.

Furthermore, the user station only needs to be equipped with a radio transmitter, and the terrestrial telephone line and modem for the uplink are not required, so that the user station can be made smaller and its portability can be improved.

Further, since an available channel can be known at the time of securing the uplink, it is possible to improve the use efficiency of the channel at the time of connection and temporary connection, and to reduce the call loss due to collision.

In particular, the greatest effects of the present invention are that the resources of the entire system can be effectively used, specifically, the limited number of demodulators in the center station can be effectively used, and the user station is a mobile station. Sometimes it is possible to provide a product with excellent portability. In particular, what is excellent in portability is that power consumption can be suppressed low because a ground line is not required and operation is performed only when there is transmission data.

Further, a secondary effect can be obtained from the viewpoint of system construction. Although it seems very suitable to construct a system that applies the present invention to Internet access, in this case, the application used for communication, that is, the portion corresponding to the upper layer of the OSI reference model extends over many layers. Many types are already widely available to the public, meaning that they can be used as-is and used as-is. Otherwise, existing users cannot be captured and existing infrastructure cannot be used. The same result as that of the present invention can be obtained if certain types of exception processing are not activated in the upper layer of the OSI reference model, but it is practically impossible for the above-described reason. On the other hand, most systems have engineering or legal issues
Because of the physical layer (especially in the case of wireless), it is difficult to use the existing product as it is, and it is necessary to design a new system for each system, or at least modify the existing product and use it. Therefore, the present invention has an advantage that it can be easily introduced because it is applied to the “parts that must be modified” when the system is constructed.

[Brief description of the drawings]

FIG. 1 is a flowchart of a line control in a center of a wireless communication system according to the present invention, in particular, a part relating to (temporary) disconnection / connection.

FIG. 2 is a configuration diagram of a wireless communication system according to the present invention.

FIG. 3 is a sequence diagram between devices according to the present invention, wherein the uplink is a terrestrial link and the downlink is a satellite link.

FIG. 4 is a configuration diagram of a wireless communication system according to the present invention in which an uplink is also established via a satellite line.

FIG. 5: Both the uplink and the downlink are satellite links,
FIG. 5 is a sequence diagram between devices according to the present invention.

FIG. 6 is a sequence diagram between the devices according to the present invention, which matches the information of the database and the transmitted information of the uplink of the user station with respect to the sequence of FIG. 5;

FIG. 7 is a sequence diagram between devices according to the present invention for notifying a user station of uplink channel use status information from a center station to the sequence of FIG. 5;

8 is a sequence diagram between the devices according to the present invention for matching information of a database with transmitted uplink information of a user station in the sequence of FIG. 7;

FIG. 9 is a configuration diagram of a conventional wireless communication system.

[Explanation of symbols]

 Reference Signs List 1 center station 2 user station 3 satellite 4, 104 demodulator, DEM 5 internet 6 gateway, GW 7 terrestrial telephone network 8, 10 uplink 9 downlink 11, 111 modem 12 user terminal, personal computer

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hideki Fujibe 3-19-2 Nishi Shinjuku, Shinjuku-ku, Tokyo Japan Telegraph and Telephone Corporation (72) Inventor Yoshihisa Kato 3-19 Nishi Shinjuku, Shinjuku-ku, Tokyo No. 2 Nippon Telegraph and Telephone Corporation F-term (reference) 5K067 AA11 AA25 AA42 AA43 BB21 CC02 DD17 DD26 DD51 EE07 EE10 EE12 EE65 FF02 GG21 HH22 HH23 KK15 5K072 AA12 AA19 AA20 BB02 BB15 CC03 CC03 CC03 DD01

Claims (4)

[Claims] An information processing apparatus comprising: a center station; and one or more user stations communicating with the center station, wherein the user station selects one channel from a plurality of channel groups and transmits the selected channel to the center station. Means for setting and transmitting an uplink, and means for receiving transmission content from the center station via a downlink, wherein the center station transmits the transmission content from the user station input from different channels. Means for receiving via the uplink, means for transmitting to the user station via the downlink, and the center station performs at least one channel-specific demodulation for each channel of the uplink. A communication system having a logical network configuration according to the OSI reference model, wherein the user station is used for communication. After establishing the uplink for all layers in Yaneru, the center station, the uplink according to channel control information from the user station, and cutting at least a physical layer channel,
Releasing the demodulator of the center corresponding to the channel,
Or, at least a means for connecting a physical layer line and securing a demodulator corresponding to a certain channel, wherein the upstream layer of the network layer or higher is the network layer after the uplink is established for all layers. It is maintained until the uplink is disconnected for all layers by instructions from the above layers, and the downlink is transmitted from the network layer or higher layers after the uplink is established for all layers. A communication system characterized by being maintained at least until the uplink is disconnected for all layers by an instruction. 2. The center station displays a state of each user station and, for a user station using the uplink, a state of the uplink including line characteristics of the uplink, disconnection of a physical layer line, and connection information. Each of the user stations uses the uplink information including the disconnection and connection information of the physical layer line of the uplink of the own user station together with the identifier of the own user station. The center station, when receiving from the uplink, the state of the user station recorded in the database and the line of the uplink. Characteristics, information indicating the state of the uplink,
Means for matching the identifier of the user station added to the transmitted data and the information on the uplink of the user station; and receiving only when the information from the user station is accepted without any contradiction in the current state. The communication system according to claim 1, further comprising means for continuing processing. 3. The communication system according to claim 1, wherein the uplink is a frequency division multiple access wireless line. 4. The means for determining a channel to be used for the uplink based on usage information of the channel for the uplink received from the center station via the downlink. The communication system according to any one of claims 1 to 3, further comprising: