JP4449992B2 - Communication resource allocation method and apparatus for executing the method - Google Patents

Description

  The present invention relates to a communication resource allocation method and an apparatus for executing the method for the purpose of effectively using communication resources in communication in which periodic communication and on-demand communication are mixed.

  A conventional technique will be described regarding a method for assigning communication resources to a plurality of terminal stations sharing a communication path.

  FIG. 1 is a configuration example of a target multipoint communication system. The terminal station communicates with the base station, and the communication path is shared by all terminal stations. The communication path may be wired or wireless. Further, the terminal station and the base station may communicate with each other via a communication satellite. When a plurality of terminal stations perform communication using the same communication resource, the signals overlap each other and normal communication is not performed. On the other hand, if communication resources are fixedly allocated to terminal stations so that communication resources do not overlap, communication resources are also required for terminal stations that are not performing communication, resulting in waste. Therefore, in order to effectively use communication resources, a technique for dynamically allocating communication resources to terminal stations according to communication conditions is required.

  An outline of the prior art 1 is shown in FIG. A communication resource is allocated when a communication start request is issued by a terminal station, and a communication resource is released when a communication end request is issued. However, actual communication between the communication start request and the communication end request is performed discretely. That is, there are a time zone during which communication is performed and a time zone during which communication is not performed. At this time, since the communication resource is given also in the time zone when communication is not performed, the communication resource is wasted. Specific examples of the communication resource allocation method as in prior art 1 include the DAMA method (Demand Assignment Multiple Access) in Non-Patent Documents 1 and 2, and PPPoE (Point -to-Point Protocol over Ethernet (registered trademark)) corresponds to this. The prior art 1 is often used for a network whose communication status is not known in advance.

  In contrast to the prior art 1, the prior art 2 is used for a network in which predetermined communication or predictable communication is performed. A sensor network can be considered as an example of such a network. The sensor network is designed for a safe, secure, and comfortable life by transmitting sensor information to a base station and processing the collected sensor information mainly by innumerable wireless sensor terminals that require low power and do not require maintenance. Realize new service provision. In the sensor network, the base station schedules communication resources so as not to generate as much surplus as possible according to the communication contents. As a result, although communication is not performed, communication resources are not given, and communication resources can be used effectively. There exists patent document 1 as a concrete Example.

  However, as shown in FIG. 3, the related art 2 has a problem when new communication is added to the originally scheduled communication. In this case, as shown in FIG. 4, the communication resource is scheduled so as not to generate as much surplus as possible according to the originally scheduled communication content. In the figure, communication is performed by giving all time resources and frequency band resources during the communication period to the terminal station without gaps. However, if the amount of communication increases from the beginning, the portion of the communication with the scheduled communication resource cannot be communicated. Further, when the communication amount is reduced from the beginning, a surplus occurs in the scheduled communication resource. This is because all resources are given to the terminal station without any gaps at the scheduled stage. As a means corresponding to this, as shown in FIG. 5, a method of securing a surplus in the resource in advance can be considered. However, if surplus resources are not used, resources are wasted. In addition, a method for re-scheduling the communication resource for the changed communication volume and notifying it again can be considered. However, if the communication resource information to be notified becomes congested and a time delay occurs or is lost, terminal stations using communication resources of the old schedule and the new schedule are mixed. As a result, communication resources are duplicated or unused.

JP 2003-272079 A Satellite phone (DAMA) service, http://www.superbird.co.jp/services/dama.html Mobile communication Inmarsat and Iridium using satellite, http://www.sys.cs.meiji.ac.jp/~masao/Board/link/2-2/inmarsat-iridium.html A Method for Transmitting PPP Over Ethernet (PPPoE), http://www.ietf.org/rfc/rfc2516.txt

In the communication resource allocation method described above, a surplus or shortage of communication resources occurs for the following communication, and the communication resources cannot be effectively used.
1. 1. Communication in which communication volume is determined in advance and communication that fluctuates randomly. Communication in which the amount of communication is determined in a short time range, but the amount of communication changes in a longer time range. Therefore, the present invention assigns communication resources that can effectively use communication resources even in the above communication. It is an object to provide a method and an apparatus for performing the method.

  According to the communication resource allocation method according to the present invention, in the communication resource allocation method to a terminal station in a multipoint communication system, which includes a plurality of terminal stations and at least one base station, and the terminal stations share a communication path, The station schedules the communication resource in a predetermined time interval, and changes the schedule number monotonously in a predetermined order each time the schedule is performed, notifies the terminal station of the communication resource and the schedule number, At least one set of the notified communication resource and schedule number is held, the base station notifies the currently used schedule number M to all terminal stations, and the terminal station communicates using the communication resource of the schedule number that matches M. If the communication resource with the schedule number that matches M is not held, communication is stopped. The features. Therefore, each terminal station can communicate using the communication resource of the same schedule number scheduled by the base station. In other words, since communication resources with different schedule numbers are not used, resources can be used effectively.

  Further, according to another embodiment of the communication resource allocation method of the present invention, the base station may use a schedule number M that is currently used, a schedule number N that is used next, and a time T that starts using the communication resource of the schedule number N, and When the terminal station communicates using the communication resource of the schedule number that matches N for the time after T, and does not hold the communication resource of the schedule number that matches N It is also preferable to stop communication. In other words, in the notification of only the schedule number currently used, the minimum cycle for switching the schedule is the transmission cycle of the notification information. However, according to this method, the time for switching the schedule can be specified in a pinpoint. It can be carried out.

  Further, according to another embodiment of the communication resource allocation method of the present invention, it is preferable that the time timing at which the base station broadcasts the broadcast information to all terminal stations includes at least the time to start using the schedule number M. . According to this method, it is possible to effectively use resources in order to include the cycle for switching the schedule in the notification cycle of the currently used schedule number.

  Further, according to another embodiment of the communication resource allocation method of the present invention, the base station sets the time timing at which the broadcast information is broadcast to all the terminal stations as a constant interval D, and the terminal station receives the broadcast information every interval D. If not, the terminal station preferably stops communication. When a terminal station that has failed to receive broadcast information communicates, the communication resources of the new and old schedule numbers are used at the same time, resulting in communication collisions and unused communication resources. Since these can be avoided, resources can be used effectively.

  In addition, according to another embodiment of the communication resource allocation method of the present invention, a terminal station in a multipoint communication system that includes a plurality of terminal stations and at least one base station, and the terminal stations share a communication path. In the communication resource allocation method, the base station schedules communication resources in a predetermined time interval, and notifies the terminal station of the communication resource and the time T2 for starting use of the communication resource each time the schedule is performed. The terminal station holds at least one combination of the communication resource and time T2, and the terminal station communicates using the communication resource held in combination with T2 for the time after T2. As the amount of broadcast information increases, the number of communication resources that can be used for actual communication decreases. However, according to the present method, broadcast information is unnecessary, so resources can be effectively used.

  In the communication resource allocation method according to the present invention, the communication resource includes at least one of time, frequency, power, modulation / demodulation method, and error correction method.

  Further, according to the base station apparatus of the present invention, a base station apparatus in a multipoint communication system that includes a plurality of terminal stations and at least one base station, and in which the terminal stations share a communication path, transmits and receives with the terminal stations. , A terminal DB that stores communication contents for each terminal station, a communication resource schedule unit that schedules communication resources, and a notification information generation unit that generates communication resources to be notified to each terminal station from the schedule contents And.

  In addition, the base station apparatus according to the present invention preferably further includes a broadcast information generation unit that broadcasts the schedule number at a constant period.

  Further, according to the terminal station apparatus according to the present invention, the terminal station apparatus in the multipoint communication system, which is composed of a plurality of terminal stations and at least one base station, and the terminal stations share a communication path, transmits and receives with the base station. A modem that performs communication, a communication resource DB that stores a plurality of notified communication resources, and a communication resource switching unit that selects a communication resource.

  Moreover, it is also preferable that the communication resource switching unit of the terminal station apparatus according to the present invention selects the communication resource indicated by the latest switching time.

  According to the present invention, the terminal station selects the communication resource based on the information notified from the base station with respect to the communication resource scheduled based on the communication content of the terminal station, thereby efficiently reducing the communication resource. Can be used.

  The best mode for carrying out the present invention will be described in detail below with reference to the drawings. In addition, although this invention can be implemented in a multipoint communication system regardless of a cable and a radio | wireless, below, description is advanced on the assumption of a radio | wireless communication path.

  The communication resources for the terminal station to communicate with the base station may be time, frequency, power, modulation / demodulation method, error correction method, and the like. With regard to time and frequency, when a plurality of terminal stations communicate using the same terminal, the signals overlap each other and normal communication is not performed. On the other hand, if fixedly assigned to terminal stations so that communication resources do not overlap, communication resources are also required for terminal stations that are not performing communication, resulting in waste. Therefore, in order to effectively use communication resources, it is necessary to dynamically allocate communication resources to terminal stations.

  Regarding the power, when the terminal station is a mobile body, it is desirable that the power is as low as possible from the viewpoint of saving the drive battery. The modulation / demodulation method and error correction method must be assigned according to the characteristics of the modem. FIG. 6 shows a method for selecting a modulation / demodulation method and an error correction method. In the figure, BPSK, QPSK, 8PSK, and 16QAM are modulation / demodulation methods, and 1/2, 1/3, 3/4, and 7/8 are error correction methods. The modulation / demodulation method and error correction method are selected from the relationship between the received power / noise power of the terminal station and the transmission speed / frequency band. Since the noise power can be uniquely determined by the performance of the terminal station, a modulation / demodulation method and an error correction method are selected from the power, frequency, and transmission speed of the terminal station.

  By the way, the communication targeted by the present invention is a mixture of communication with clear communication contents before communication is performed and random communication that cannot be predicted before communication is performed. For example, a communication system is assumed in which on-demand emergency calls occur in the event of a disaster in addition to periodic data from multiple sensors distributed at multiple points. Specifically, as represented by a telemeter or the like in a sensor network, physical information obtained from the sensor is collected via a wired / wireless network and used for various analyzes and controls. For example, a factory production site is one of the places where sensors are most active. In such places, it is daily to control complex processes by cooperative operation of multiple sensors in the form of FA (factory automation). Has been done. In such daily communication, the amount of communication can be predicted in advance. In addition to daily communication, on-demand communication for notifying emergency content is added when an abnormality that causes an earthquake or other disaster is detected by a sensor.

An example of communication that occurs in the sensor network is shown in Table 1.

  The amount of communication and the communication interval differ for each type of sensor (terminal station). Since the sensing data is less urgent, transmission to the base station may be completed until the next sensing time (allowable delay). Using this property, communication resources can be used effectively. That is, as shown in FIG. 7, the time resource is scheduled to the terminal station in consideration of the communication amount of the terminal station and the allowable delay until the end of communication. Here, an example of only time is shown, but actually, a schedule is performed by combining frequency, power, modulation / demodulation method, and error correction method. The scheduled communication resource is notified to the terminal station, and the terminal station performs communication using the notified communication resource.

  In addition to the communication described above, let us consider a case where communication contents change due to addition or deletion of a terminal station, or a case where a sudden request call occurs. If you simply re-schedule and notify the communication resource again, there will be a problem that there will be a situation where a terminal station that has received a change in communication resource and a terminal station that has not received the change in communication resource for some reason may exist. To do. In particular, in the case of wireless communication, a terminal station that fails to notify communication resources occurs due to delay or deterioration of the communication path. Under such a situation, since communication using the same communication resource is performed at the same time, a communication collision occurs, and as a result, the communication resource is wasted. According to the present invention, this situation can be avoided and all terminals can communicate using communication resources belonging to the same schedule. This method will be described below.

  FIG. 8 illustrates a communication resource scheduling method according to the present invention. In the base station, a communication resource schedule table is created so that the communication resource can be most effectively used from the communication amount of the terminal station. In addition, when the originally scheduled communication changes, communication resources are rescheduled. At this time, the schedule table number is changed in a predetermined order each time a schedule is performed.

  FIG. 9 shows a method for assigning communication resources to each terminal. Create a table of communication resources and change the table number for each schedule. Next, communication resources allocated to each terminal station are extracted from the generated table. Then, the communication resource and the table number are notified to the terminal station. A series of processing from generation of a table at the base station to notification to the terminal station described here is performed each time a new table is generated. The base station reports (broadcasts) the current table number that is most effective at that time, the switching time to the next table, and the post-switching table number that is effective at the switching time to all terminal stations at regular intervals. On the other hand, the terminal station performs communication using a communication resource that matches the current table number to be notified. At the same time, after switching to the switching time, switching to the communication resource that matches the table number is continued. Basically, communication resources determined to be valid by the base station in the sequence described here can be allocated to the terminal station.

  Since communication resources are scheduled for each table number, when a terminal that fails to receive broadcast information performs communication, a communication resource with a schedule number different from that of other terminals is used. In order to avoid this, a terminal that fails to receive broadcast information immediately stops communication. As shown in FIG. 10, the broadcast information is transmitted from the base station at a predetermined period. Therefore, the terminal station that has not received the broadcast information at a predetermined period can determine that reception of the broadcast information has failed and stop communication.

  By the way, in the method described above, a separate communication resource is required to transmit broadcast information. As the broadcast information transmission interval becomes shorter, the communication resources for the broadcast information increase, and as a result, the communication resources that can be used in actual communication decrease. FIG. 11 shows a sequence that does not use broadcast information from the base station. Each time the base station schedules a communication resource, it notifies each terminal station of the communication resource and the switching time during which the communication resource can be most effectively used. On the other hand, the terminal station performs communication by switching communication resources according to the notified contents. It should be noted here that the schedule is performed at an arbitrary timing, so that the notified communication resource may be invalidated. Therefore, the terminal station selects the communication resource indicated by the latest switching time. That is, in FIG. 11, even if the resource 1A and the resource NA include resources after the time B, each terminal station selects the resource 1B and the resource NB indicated by the time B that is the latest switching time. . Further, when the notification information is not used, since it is necessary for each terminal to execute a switching process based on the time of a clock incorporated in each terminal, it is necessary to synchronize the clock of each terminal. As a clock synchronization method, there is a method of receiving radio waves such as a GPS or a radio clock.

  12 and 13 are block diagrams of base stations and terminal stations for carrying out the present invention. The base station communicates with the modem that performs transmission / reception with the terminal station, the terminal DB (database) that stores communication contents for each terminal, the on-demand communication IF that receives a request for on-demand communication from the terminal, and the communication contents A communication resource schedule unit that schedules communication resources so that resources can be used effectively, a notification information generation unit that generates communication resources and the like to be notified for each terminal from the schedule contents, and a schedule number and the like are reported at a fixed period It is comprised by the alerting | reporting information generation part. In addition, the terminal station includes a modem that performs transmission and reception with the base station, a communication resource DB that stores a plurality of notified communication resources, a communication resource switching unit that selects a communication resource, and an emergency call or the like within the local station. It consists of an on-demand communication IF that accepts the occurrence of on-demand communication. When the broadcast information is not used, the base station does not use the broadcast information generation unit in FIG. 12, and the terminal station selects the communication resource indicated by the latest switching time in the communication resource switching unit in FIG. To do.

  Moreover, all the embodiment described above shows the present invention exemplarily, and does not limit the present invention, and the present invention can be implemented in other various modifications and changes. Therefore, the scope of the present invention is defined only by the claims and their equivalents.

The structural example of a multipoint communication system is shown. The communication resource allocation in a prior art is shown. Shows the amount of communication for each terminal. The communication resource allocation 1 with respect to the traffic is shown. The communication resource allocation 2 with respect to the traffic is shown. Shows the modem characteristics. The scheduling for effective use of communication resources is shown. The allocation of the communication resource with respect to the traffic in this invention is shown. The communication resource allocation flowchart 1 in this invention is shown. The communication resource allocation flowchart 2 in this invention is shown. The communication resource allocation flowchart 3 in this invention is shown. The structure of the base station in this invention is shown. The structure of the terminal station in this invention is shown.

Claims (6)

In a method for allocating communication resources to a terminal station in a multipoint communication system, which is composed of a plurality of terminal stations and at least one base station, and the terminal stations share a communication path,
The base station performs scheduling of communication resources in a predetermined time interval, the scheduled number every time performing the schedule puff varying in a predetermined order, the communication resources and the schedule number to each of said terminal stations Notify
The terminal station holds at least one set of the notified communication resource and the schedule number,
The base station informs the all the previous SL end end station broadcast information including a time T to start using the communication resources currently used to schedule number M and the next schedule number using N and schedule number N,
The terminal station communicates using a communication resource with a schedule number that matches M, and stops communication if it does not hold a communication resource with a schedule number that matches M, and the time after T is N A communication resource allocating method , wherein communication is performed using a communication resource having a schedule number that matches N, and communication is stopped when a communication resource having a schedule number that matches N is not held . Said base station, said time timing for notifying to all the broadcast information before Symbol end end station, at least, a communication resource allocation according to claim 1, characterized in that it comprises the schedule number M of time to start using Method. Said base station, wherein the predetermined distance D time timing for notifying to all the broadcast information before Symbol edge end station, when the terminal station does not receive the notification information for each said interval D, the terminal station communication The communication resource allocation method according to claim 1 or 2 , wherein the communication resource is stopped. In a base station apparatus in a multipoint communication system, which is composed of a plurality of terminal stations and at least one base station, and the terminal stations share a communication path,
A modem for transmitting and receiving to and from the terminal station;
A terminal DB storing communication contents for each terminal station;
There line scheduling of communication resources in a predetermined time interval, the communication resource scheduling unit to change the schedule number every time performing the scheduling in a predetermined order,
A notification information generating unit that generates a communication resource and a schedule number to be notified for each terminal station from the schedule content;
Broadcast information that is broadcast to all of the terminal stations, and includes broadcast information including a schedule number M that is currently used, a schedule number N that is used next, and a time T at which the communication resource of the schedule number N starts to be used at regular intervals A notification information generation unit that
The terminal station communicates with each of the terminal stations using a communication resource having a schedule number that matches the M notified to each terminal station, and the time after the T is a schedule that matches the N notified to each terminal station. A base station apparatus that performs communication using a communication resource of a number . In a terminal station apparatus in a multipoint communication system, which is composed of a plurality of terminal stations and at least one base station, and the terminal stations share a communication path,
A modem for transmitting and receiving to and from the base station;
A communication resource DB for at least one set contains the set of notified communication resources and schedule number from said base station,
Based on broadcast information broadcast from the base station at a constant cycle, including the schedule number M that is currently used, the schedule number N that is used next, and the time T at which the communication resource of the schedule number N starts to be used, A communication resource switching unit for selecting the communication resource ,
Communication is performed using a communication resource with a schedule number that matches M, and communication is stopped when the communication resource with a schedule number that matches M is not held, and the time after T is a schedule number that matches N The terminal station apparatus is characterized in that the communication is stopped when the communication resource of the schedule number matching N is not held, and communication is stopped . 6. The terminal station apparatus according to claim 5 , wherein the communication resource switching unit selects a communication resource indicated by the latest switching time in time from among the communication resources stored in the communication resource DB. .

Images