Communication system, communication device, and communication method

Abstract

A communication system according to the present invention comprises a wireless terminal device that partitions one piece of data to be transmitted into a plurality of packets and wirelessly transmits the packets such that the difference in delay time between packets adjacent in the time direction is equal, a receiver that receives the packets, a transmission destination device that acquires packets, and a delay controller that buffers the packets received by the receiver and outputs the packets in order at a fixed time interval. The packets acquired by the transmission destination device are the packets outputted by the delay controller. When packets have been retransmitted, the delay controller outputs the packets buffered on the basis of a retransmission delay time preset in accordance with an identifier or the location of the wireless terminal device in order at a fixed time interval.

Description

Communication system, communication device, and communication method

[0001] The present invention relates to a communication system, a communication device, and a communication method.

[0002] In recent years, the demand for communication has been increasing.

[0003] “3GPP TS 38.300 V17.5.0”, 3GPP, 2023.”3GPP TS 38.212 V17.5.0”, 3GPP, 2023.”3GPP TS 38.322 V17.3.0”, 3GPP, 2023.

[0004] In communications, a single piece of data, such as a single piece of video data or a single piece of music data, is divided into multiple packets and transmitted from a transmitting side to a receiving side. When the packets are received by the receiving side, a predetermined application, which is a process that follows rules defined in the application layer of the OSI reference model, is executed on the packets.

[0005] Some applications perform processing on packet data at time intervals that correspond to the time intervals between packets arriving in the order they arrived, such as video distribution services that require real-time processing.

[0006] Meanwhile, the sender sends each packet. The sender sends each packet with the same packet interval. However, even if the sender sends each packet with the same packet interval, packet retransmissions can cause a discrepancy in the packet intervals before the packets reach the receiver. This discrepancy is known as jitter.

[0007] This difference has a greater impact on applications that process packet data at time intervals that correspond to the time intervals between packets arriving in the order in which they arrived than on applications that do not, because processing of packet data is performed at time intervals that correspond to the time intervals between packets arriving in the order in which they arrived. This is because if a packet contains jitter, the timing at which the application is executed for that packet will be shifted by the amount of the jitter.

[0008] As a result, if the data before being divided into packets is video data, for example, the video may be distorted when played back by an application. If the data before being divided into packets is music data, the music may be distorted when played back.

[0009] In view of the above circumstances, an object of the present invention is to provide a technique for reducing the effect of jitter on the execution results of an application.

[0010] One aspect of the present invention is a communication system comprising: a wireless terminal device that divides a single piece of data to be transmitted into multiple packets and transmits the packets wirelessly so that the difference in delay time between adjacent packets in the time direction is equal; a receiver that receives the packets; a destination device that acquires the packets; and a delay controller that buffers the packets received by the receiver and outputs each of the packets in sequence at a fixed time interval, wherein the packets acquired by the destination device are packets output by the delay controller, and when a packet is retransmitted, the delay controller outputs each of the buffered packets in sequence at a fixed time interval based on a retransmission delay time predetermined in accordance with the identifier or location of the wireless terminal device.

[0011] One aspect of the present invention is a communications device comprising: a wireless terminal device that divides a single piece of data to be transmitted into multiple packets and transmits the packets wirelessly so that the difference in delay time between adjacent packets in the time direction is equal; a receiver that receives the packets transmitted by the wireless terminal device; and a delay controller that buffers the received packets and outputs each of the packets in sequence at a fixed time interval; wherein, when a packet is retransmitted, the first control unit controls the operation of the delay controller and causes each of the packets buffered by the delay controller to be output in sequence at a fixed time interval based on a retransmission delay time predetermined according to the identifier or location of the wireless terminal device.

[0012] One aspect of the present invention is a communication method executed by a communication system comprising: a wireless terminal device that divides a single piece of data to be transmitted into multiple packets and transmits the packets wirelessly so that the difference in delay time between adjacent packets in the time direction is equal; a receiver that receives the packets; a destination device that acquires the packets; and a delay controller that buffers the packets received by the receiver and outputs each of the packets in sequence at a fixed time interval, wherein the packets acquired by the destination device are packets output by the delay controller, and when a packet is retransmitted, the delay controller outputs each of the buffered packets in sequence at a fixed time interval based on a retransmission delay time predetermined according to the identifier or position of the wireless terminal device, and the communication method includes an output step in which, when a packet is retransmitted, the delay controller outputs each of the buffered packets in sequence at a fixed time interval based on a retransmission delay time predetermined according to the identifier or position of the wireless terminal device.

[0013] The present invention makes it possible to reduce the effect of jitter on the execution results of an application.

[0014] 1 is an explanatory diagram illustrating a communication system according to an embodiment. An explanatory diagram illustrating an example of packet output processing by a delay controller according to an embodiment. An explanatory diagram illustrating a more specific example of implementation of a communication system according to an embodiment. A diagram illustrating an example of the hardware configuration of a base station according to an embodiment. A diagram illustrating an example of the hardware configuration of a transfer device controller according to an embodiment. A diagram illustrating an example of the hardware configuration of a transfer device according to an embodiment. A flowchart illustrating an example of the flow of processing performed by a communication system according to an embodiment. A diagram illustrating an example of the configuration of a communication system according to a modified example. A diagram illustrating an example of the configuration of a communication system including a wireless controller according to a modified example.

[0015] 1 is an explanatory diagram illustrating a communication system 100 according to an embodiment. The communication system 100 includes at least a wireless terminal device 10, a receiver 20, a first control unit 30, a delay controller 40, and a destination device 50.

[0016] The wireless terminal device 10 divides one piece of data to be transmitted into multiple packets and transmits the packets wirelessly so that the difference in delay time between adjacent packets in the time direction is equal. Therefore, the wireless terminal device 10 transmits multiple packets that make up the transmission target.

[0017] The wireless terminal device 10 retransmits packets according to a predetermined communication protocol when retransmission is necessary. This packet retransmission is an example of jitter generation. The predetermined communication protocol is, for example, TCP (Transmission Control Protocol) or HARQ (Hybrid Auto Repeat Request) in the MAC (Medium Access Control) layer of a mobile communication system (see, for example, Non-Patent Document 1).

[0018] The wireless terminal device 10 may be any device that divides data into packets and transmits them wirelessly. Therefore, the wireless terminal device 10 may be, for example, a mobile terminal such as a smartphone or a personal computer, or a robot such as an industrial robot or a drone that is equipped with sensors such as a camera sensor or a temperature sensor.

[0019] The receiver 20 receives the packets transmitted by the wireless terminal device 10. The receiver 20 is specifically an antenna.

[0020] The first control unit 30 includes a processor 91 such as a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), or an NPU (Neural Network Processing Unit), and a memory 92, which are connected by a bus. In the first control unit 30, the processor 91 reads out programs stored in a predetermined storage unit, such as a buffer time estimation process (to be described later), and stores the read programs in the memory 92. The processor 91 executes the programs stored in the memory 92, whereby the first control unit 30 performs various processes.

[0021] The processing executed by the first control unit 30 is, for example, a buffer time estimation processing, which is a processing for estimating a buffer time of a transmission target based on terminal information and retransmission performance information.

[0022] The terminal information is information indicating the identifier or location of the wireless terminal device 10 .

[0023] The retransmission performance information is predetermined information indicating a retransmission probability and a retransmission delay time according to the identifier or location of the wireless terminal device 10. The retransmission probability is the probability that a packet will be retransmitted. For example, if an average of one packet out of 1000 packets needs to be retransmitted, the retransmission probability is 0.1%.

[0024] The retransmission delay time indicates the delay time caused by retransmission. For example, suppose that after a first packet is transmitted at time t1, the next packet, a second packet, needs to be retransmitted, and the time at which the second packet is retransmitted is time t2. In this case, assuming that the time interval between packets in the absence of retransmission is t0, the retransmission delay time is td = (t2 - t1 - t0). Since the delay time caused by retransmission is predetermined, the retransmission delay time is a predetermined time.

[0025] The buffer time estimation process is a process of executing a mathematical model that has been trained in advance by machine learning, for example, and that estimates the buffer time of a transmission target based on terminal information and retransmission performance information. Such a trained mathematical model is obtained, for example, by learning using a set of terminal information, retransmission performance information, and information indicating the buffer time as training data. A more specific example of the learning is learning in which the mathematical model to be trained estimates the buffer time in response to input of the terminal information and retransmission performance information included in the training data, and the mathematical model to be trained is updated so as to reduce the difference between the estimated result and the buffer time indicated by the information indicating the buffer time included in the training data, until a predetermined condition for ending the learning is satisfied.

[0026] In addition, the process of estimating the buffer time of the transmission target based on the terminal information and retransmission performance information is not limited to the execution of the above mathematical model, but may be any process that estimates the buffer time of the transmission target based on, for example, the retransmission probability and retransmission delay time indicated by the retransmission performance information for the wireless terminal device 10 indicated by the terminal information.

[0027] The delay controller 40 buffers the packets received by the receiver 20 for the buffer time estimated by the buffer time estimation process. The delay controller 40 outputs the buffered packets in order at regular time intervals.

[0028] Here, the sequential output at a fixed time interval will be described with reference to Fig. 2. Fig. 2 is an explanatory diagram illustrating an example of processing for outputting packets by the delay controller 40 in the embodiment.

[0029] When no jitter occurs, packets are spaced equally apart, so the delay controller 40 simply outputs each packet in the order in which it arrived, at the time intervals at which the packets arrived. As a result, the buffered packets are output in order at predetermined time intervals. Note that the predetermined time intervals in this case are the time intervals between packets when the wireless terminal device 10 transmits the packets.

[0030] On the other hand, if jitter occurs due to packet retransmission, and the delay controller 40 simply outputs each packet in the order in which the packets arrived, at the time intervals at which the packets arrived, the time intervals will no longer be constant.

[0031] Image G1 in Figure 2 shows a situation in which jitter occurs in the transmission of packets to be transmitted. More specifically, image G1 shows that, among five packets, packets P1, P2, P3, P4, and P5, the time interval D1 between packets P3 and P4 is longer than the others. This is the result of packet P4 being retransmitted. Therefore, when expressed using the above-mentioned time t0 and retransmission delay time td, the time interval D1 is t0 + td.

[0032] The delay controller 40 changes this time interval D1 to t0 and outputs packets P1, P2, P3, P4, and P5. Image G2 in FIG. 2 shows an example of a sequence of packets in which the time intervals between packets have been adjusted to a constant time interval by the delay controller 40. In image G2 in FIG. 2, the time intervals between packets P1, P2, P3, P4, and P5 are constant, unlike in image G1. This is the result of the operation of the delay controller 40.

[0033] For example, when buffering packets P1, P2, P3, P4, and P5, the delay controller 40 records the time interval between each packet and the immediately preceding packet in a predetermined storage device. For packets that have been retransmitted, the delay controller 40 shortens the recorded time interval by the retransmission delay time and re-records the packets. The delay controller 40 then outputs each packet in order at the recorded time intervals.

[0034] In other words, when a packet is retransmitted, the delay controller 40 shortens the time interval between packets by the time indicated by the retransmission delay time, for example, for packets in which the time interval between packets has changed due to the retransmission, thereby aligning the time intervals of each buffered packet to a constant value and outputting the packets.

[0035] For example, by such processing, the delay controller 40 outputs the received packets at regular time intervals.

[0036] It should be noted that the delay controller 40 does not necessarily have to make the time intervals between packets constant by shortening them by the retransmission delay time. For example, the time intervals between packets that are not delayed may be made constant by extending the time intervals between packets by the retransmission delay time.

[0037] In this way, when a packet is retransmitted, the delay controller 40 outputs each buffered packet in sequence at a fixed time interval based on the retransmission delay time. Note that when there is no packet retransmission, the buffered packets can be output in the buffered order at the buffered time interval, so the packet output process by the delay controller 40 is not based on the retransmission delay time. This process reduces the impact of jitter on the execution results of the application.

[0038] The destination device 50 acquires the packets output by the delay controller 40. Because jitter has been eliminated by the delay controller 40, the time intervals between packets acquired by the destination device 50 are constant regardless of the packets. Therefore, when the destination device 50 executes an application that processes packet data at time intervals that correspond to the time intervals at which the packets arrived in the order in which they arrived, the impact of jitter on the execution result is small.

[0039] <More Specific Implementation Example of Communication System 100> A more specific implementation example of the communication system 100 will be described as a communication system 100a with reference to Fig. 3. Fig. 3 is an explanatory diagram illustrating a more specific implementation example of the communication system 100 according to the embodiment. That is, Fig. 3 is an explanatory diagram illustrating the communication system 100a according to the embodiment.

[0040] The communication system 100a includes a wireless terminal device 10, a base station 2, a transfer device controller 3, a transfer device 4, and a server 5. The base station 2 includes a receiver 20 and is a base station that transmits and receives wireless signals to and from the wireless terminal device 10. The transfer device controller 3 includes a first control unit 30 and controls the operation of the transfer device 4. The transfer device 4 includes a delay controller 40 and transfers data received from a transfer source to a transfer destination. The transfer source is, for example, the base station 2. The transfer destination is, for example, a server 5. The server 5 is a server and is an example of a destination device 50.

[0041] 4 is a diagram showing an example of the hardware configuration of the base station 2 in the embodiment. The base station 2 includes a second control unit 21 including a processor 93 and a memory 94 connected by a bus, and executes a program. By executing the program, the base station 2 functions as a device including a receiver 20, the second control unit 21, an interface unit 22, and a storage unit 23.

[0042] More specifically, the processor 93 reads the program stored in the storage unit 23 and stores the read program in the memory 94. The processor 93 executes the program stored in the memory 94, whereby the base station 2 functions as a device including the receiver 20, the second control unit 21, the interface unit 22, and the storage unit 23.

[0043] The second control unit 21 controls the operation of each functional unit included in the base station 2. The second control unit 21 controls, for example, the operation of the receiver 20. The second control unit 21 controls, for example, the operation of the interface unit 22. The second control unit 21 records information to the storage unit 23 and reads information from the storage unit 23, for example.

[0044] <Regarding Identification Process and Terminal Information> The second control unit 21 executes, for example, an identification process. The identification process is a process of identifying the wireless terminal device 10 in communication with the receiver 20, for example, based on radio waves received by the receiver 20. The identification process based on radio waves is a process of identifying the wireless terminal device 10 by, for example, acquiring a waveform of the radio waves that includes an identifier that identifies the wireless terminal device 10 and thereby identifying the wireless terminal device 10 in communication.

[0045] The identification may be performed using any known technology and does not necessarily have to be performed based on radio waves received by the receiver 20. The identification may also be performed based on the location or the identifier of the wireless terminal device 10. Therefore, the terminal information is acquired by the identification process.

[0046] The terminal information obtained as a result of the identification process is acquired by the first control unit 30 via, for example, the interface unit 22, for example, at a predetermined interval.

[0047] <Regarding Information Acquisition Processing> The second control unit 21 executes, for example, information acquisition processing. The information acquisition processing is processing for generating retransmission flag information, which is information indicating a packet for which retransmission has occurred when retransmission has occurred in communication between the receiver 20 and the wireless terminal device 10. Note that communication between the receiver 20 and the wireless terminal device 10 is performed in accordance with a predetermined communication protocol such as TCP. Therefore, the second control unit 21 generates retransmission flag information when a packet has been retransmitted in accordance with the predetermined communication protocol.

[0048] Here, the retransmission flag information is, for example, an information bit transmitted in DCI (Downlink Control Information) in the physical layer and MAC layer of a mobile communication system, and includes an NDI (New Data Indicator) indicating whether the data permitted to be transmitted by the DCI is new data or retransmission data (e.g., Non-Patent Document 2), Ack / Nack information for retransmission control in the MAC layer (Non-Patent Document 1), Ack / Nack information for retransmission control in the RLC (Radio Link Control) layer (e.g., Non-Patent Document 3), and Ack / Nack information in the TCP layer.

[0049] <How the retransmission flag information is used> The retransmission flag information obtained by the information acquisition process is acquired by the first control unit 30. Having acquired the retransmission flag information, the first control unit 30 executes a first packet management process. The first packet management process is a process that causes the delay controller 40 to make the time interval of packets indicated by the retransmission flag information as having undergone retransmission the same as the time interval of packets not having undergone retransmission.

[0050] When the first packet management process is executed, the delay controller 40 outputs packets whose time intervals have become constant as a result of the first packet management process. Therefore, the process of outputting packets whose time intervals have become constant as a result of the execution of the first packet management process is an example of the process of the delay controller 40 that sequentially outputs, at constant time intervals, packets buffered during the buffer time estimated by the buffer time estimation process described above.

[0051] The first packet management process is executed on packets buffered by the second packet management process, which will be described later. More specifically, the first packet management process is a process for making the time interval of packets buffered by the second packet management process, which are indicated as having undergone retransmission by the retransmission flag information, the same as the time interval of packets not having undergone retransmission.

[0052] The retransmission flag information is transmitted, for example, via a wired or wireless connection, to the device including the first control unit 30. Therefore, the retransmission flag information is transmitted, for example, from the interface unit 22 to the transfer device controller 3.

[0053] The interface unit 22 is configured to include a communication interface for connecting the base station 2 to an external device. The interface unit 22 communicates with the external device via a wired or wireless connection. The external device is, for example, the transfer device controller 3. The interface unit 22 transmits, for example, retransmission flag information to the transfer device controller 3 by communicating with the transfer device controller 3. The external device is, for example, the transfer device 4. The interface unit 22 transmits packets received by the receiver 20 to the transfer device 4 by communicating with the transfer device 4. The packets transmitted to the transfer device 4 are received by the delay controller 40.

[0054] The storage unit 23 is configured using a computer-readable storage medium device (non-transitory computer-readable recording medium) such as a magnetic hard disk device or a semiconductor storage device. The storage unit 23 stores various information related to the base station 2. The storage unit 23 stores various information generated by the operation of the second control unit 21, for example.

[0055] <Example of Hardware Configuration of Transfer Device Controller 3> Figure 5 is a diagram showing an example of the hardware configuration of the transfer device controller 3 in an embodiment. The transfer device controller 3 comprises a first control unit 30 comprising a processor 91 and memory 92 connected by a bus, and executes a program. By executing the program, the transfer device controller 3 functions as a device comprising the first control unit 30, an interface unit 32, and a storage unit 33.

[0056] More specifically, the processor 91 reads out a program stored in the storage unit 33 and stores the read out program in the memory 92. When the processor 91 executes the program stored in the memory 92, the transfer device controller 3 functions as a device including a first control unit 30, an interface unit 32, and a storage unit 33.

[0057] The first control unit 30 controls the operation of each functional unit included in the transfer device controller 3. The first control unit 30 controls, for example, the operation of the interface unit 32. The first control unit 30 records information in the memory unit 33 and reads information from the memory unit 23, for example.

[0058] <Regarding Control of Delay Controller 40 by First Control Unit 30> The first control unit 30 executes, for example, a buffer time estimation process. The first control unit 30 executes, for example, a second packet management process. The second packet management process is a process of controlling the operation of the delay controller 40 to cause the delay controller 40 to buffer packets for the buffer time estimated in the buffer time estimation process. The second packet management process is executed, for example, by notifying the delay controller 40 of the buffer time estimated in the buffer time estimation process.

[0059] The first control unit 30 acquires, for example, retransmission flag information. The first control unit 30 executes, for example, a first packet management process. Note that the first packet management process may be executed only when the retransmission flag information is obtained.

[0060] The interface unit 32 includes a communication interface for connecting the transfer device controller 3 to an external device. The interface unit 32 communicates with the external device via wired or wireless communication. The external device is, for example, the base station 2.

[0061] The interface unit 32 acquires, for example, retransmission flag information by communicating with the base station 2. The external device is, for example, the transfer device 4. The interface unit 32 controls the operation of the transfer device 4 by communicating with the transfer device 4. The control of the operation of the transfer device 4 is, for example, the control of the operation of the delay controller 40. The control of the operation of the delay controller 40 is, for example, the execution of a second packet management process. The control of the operation of the delay controller 40 is, for example, the execution of a first packet management process.

[0062] The storage unit 33 is configured using a computer-readable storage medium device such as a magnetic hard disk device or a semiconductor storage device. The storage unit 33 stores various information related to the transfer device controller 3. The storage unit 33 stores, for example, various information generated by the operation of the first control unit 30. The storage unit 33 stores, for example, retransmission performance information in advance. The storage unit 33 may also store, for example, terminal information obtained by an identification process.

[0063] 6 is a diagram illustrating an example of a hardware configuration of the transfer device 4 according to an embodiment. The transfer device 4 includes a delay controller 40. The delay controller 40 operates under the control of the first control unit 30.

[0064] The delay controller 40 includes a third control unit 41 having a processor 95 and a memory 96 connected by a bus, and executes a program. By executing the program, the delay controller 40 functions as a device including the third control unit 41, an interface unit 42, and a storage unit 43.

[0065] More specifically, the processor 95 reads the program stored in the storage unit 43 and stores the read program in the memory 96. When the processor 95 executes the program stored in the memory 96, the delay controller 40 functions as a device including a third control unit 41, an interface unit 42, and a storage unit 43.

[0066] The third control unit 41 operates, for example, under the control of the first control unit 30. When the second packet management process is executed, the third control unit 41 controls the operation of the storage unit 43 to buffer packets for the buffer time estimated in the buffer time estimation process.

[0067] Furthermore, when the first packet management process is executed, the third control unit 41 sets the time interval of packets indicated by the retransmission flag information as having undergone retransmission to be the same as the time interval of packets not having undergone retransmission.

[0068] The third control unit 41 outputs the buffered packets to a predetermined output destination via the interface unit 42 or the like.

[0069] The interface unit 42 includes a communication interface for connecting the delay controller 40 to an external device. The interface unit 42 communicates with the external device via wire or wirelessly. The external device is, for example, the base station 2.

[0070] The interface unit 42 receives, for example, packets received by the receiver 20 through communication with the base station 2. The packets received by the interface unit 42 are buffered.

[0071] The external device is, for example, the transfer device controller 3. The operation of the delay controller 40 is controlled by the first control unit 30 through communication with the transfer device controller 3 via the interface unit 42.

[0072] The external device is, for example, the server 5. The interface unit 42 transmits packets to the server 5 through communication with the server 5 when the first packet management process or the second packet management process is being executed.

[0073] The storage unit 43 is configured using a computer-readable storage medium device such as a magnetic hard disk drive or a semiconductor storage device. The storage unit 43 stores various information related to the delay controller 40. The storage unit 43 stores, for example, various information generated by the operation of the third control unit 41. The storage unit 43 stores, for example, packets together with information indicating the time interval between packets.

[0074] 6 is an example, the delay controller 40 may have any configuration as long as it can buffer the packets received by the receiver 20 for the buffer time estimated by the buffer time estimation process and then output the buffered packets in order at regular time intervals.

[0075] <Example of Processing Flow> Figure 7 is a flowchart showing an example of the processing flow executed by the communication system 100a in this embodiment. Here, an example will be described in which a retransmission occurs. If a retransmission does not occur, retransmission flag information is not generated, and the first packet management process is not executed. Note that the second packet management process is executed even if playback flag information is not generated. If retransmission flag information is not generated, the time interval between packets is constant even without the first packet management process being executed, and therefore the time interval between packets output by the delay controller 40 is constant.

[0076] The base station 2 acquires terminal information and retransmission flag information through communication between the wireless terminal device 10 and the receiver 20 (step S101). Next, the first control unit 30 executes a buffer time estimation process to estimate the buffer time based on the terminal information and retransmission performance information (step S102). That is, the first control unit 30 estimates the buffer time based on the retransmission probability and retransmission delay time indicated by the retransmission performance information for the wireless terminal device 10 indicated by the terminal information.

[0077] Next, the first control unit 30 executes a second packet management process (step S103). In step S103, the second packet management process is executed, and the delay controller 40 buffers the packet received by the receiver 20 for the buffer time estimated in step S102.

[0078] Next, the first control unit 30 executes a first packet management process (step S104). In step S104, the delay controller 40 sets the time interval of packets buffered by the process of step S103 and indicated by the retransmission flag information as having undergone retransmission to the same time interval as the time interval of packets not having undergone retransmission.

[0079] Next, the first control unit 30 outputs the packets whose time intervals have become the same in step S104 to the server 5 in sequence at regular time intervals (step S105). Therefore, the packets acquired by the server 5 are the packets output by the delay controller 40.

[0080] The communication system 100 or 100a configured in this manner includes the first control unit 30 and the delay controller 40, and maintains a constant time interval between packets. Therefore, the communication system 100 or 100a can reduce the effect of jitter on the execution results of applications.

[0081] Furthermore, a communication device equipped with the first control unit 30 configured in this manner controls the operation of the delay controller 40 to keep the time interval between packets constant. Therefore, a communication device equipped with the first control unit 30 can reduce the impact of jitter on the execution results of an application. An example of a communication device equipped with the first control unit 30 is the transfer device controller 3.

[0082] (Modification) The communication system 100a may include a remote station instead of the base station 2, and a central station instead of the server 5. In such a case, the configuration of the remote station may be the same as that of the base station 2, and the configuration of the central station may be the same as that of the server 5. Such a communication system 100a is designated as a communication system 100b, and an example of its configuration is shown in FIG.

[0083] 8 is a diagram showing an example of the configuration of a communication system 100b according to a modified example. The communication system 100b differs from the communication system 100a in that it includes a remote station 2b instead of the base station 2 and a central station 5b instead of the server 5. The remote station 2b is a remote station including a receiver 20. The central station 5b is a central station. For example, the central station 5b and the remote station 2b may be a CU (Central Unit) and a DU (Distributed Unit), respectively, in a mobile communication system, or a DU and a Radio Unit (RU). Note that the communication system 100b may also be a wireless communication system other than a mobile communication system.

[0084] The terminal information and retransmission flag information may reach the transfer device controller 3 from the remote station via the central station.

[0085] 3, the delay controller 40 is provided in the transfer device 4, but the delay controller 40 does not necessarily have to be provided in the transfer device 4. For example, the base station 2 may be provided with the delay controller 40 instead of the transfer device 4.

[0086] 3, the first control unit 30 is provided in the transfer device controller 3. However, the first control unit 30 does not necessarily have to be provided in the transfer device controller 3. For example, the base station 2 may be provided with the first control unit 30 instead of the transfer device controller 3. In such a case, the communication system 100a does not necessarily have to be provided with the transfer device controller 3. In such a case, the base station 2 is an example of a communication device that is provided with the first control unit 30.

[0087] Furthermore, the base station 2 may further include a delay controller 40 in addition to the first control unit 30 .

[0088] In addition, when the communication system 100a described above has a remote station 2b instead of the base station 2 and a central station 5b instead of the server 5 (hereinafter referred to as a "substitution example"), for example, the remote station 2b may have a delay controller 40 instead of the transfer device 4.

[0089] Furthermore, in the replacement example, the first control unit 30 does not necessarily have to be provided in the transfer device controller 3. For example, the distributed station 2b may be provided with the first control unit 30 instead of the transfer device controller 3. In such a case, the communication system 100a does not necessarily have to be provided with the transfer device controller 3. In such a case, the distributed station 2b is an example of a communication device that is provided with the first control unit 30.

[0090] Furthermore, the remote station 2 b may further include a delay controller 40 in addition to the first control unit 30 .

[0091] The terminal information and retransmission flag information may also arrive at the remote station 2b via the central station 5b.

[0092] 9 is a diagram showing an example of the configuration of a communication system 100c according to a modified example. The communication system 100c differs from the communication system 100a in that it further includes a wireless controller 6. The wireless controller 6 is a well-known wireless controller that controls the operation of the base station 2. In the communication system 100b, terminal information and retransmission flag information are transmitted from the base station 2 to the transfer device controller 3 via the wireless controller 6.

[0093] The first control unit 30 may be implemented using a plurality of information processing devices connected to each other via a network so as to be able to communicate with each other. In this case, the processes executed by the first control unit 30 may be distributed and executed by the plurality of information processing devices.

[0094] All or part of the functions of the communication systems 100, 100a, 100b, and 100c may be realized using hardware such as an ASIC (Application Specific Integrated Circuit), a PLD (Programmable Logic Device), or an FPGA (Field Programmable Gate Array). The program may be recorded on a computer-readable recording medium. Examples of computer-readable recording media include portable media such as flexible disks, optical magnetic disks, ROMs, and CD-ROMs, and storage devices such as hard disks built into computer systems. The program may be transmitted via a telecommunications line.

[0095] Although an embodiment of the present invention has been described in detail above with reference to the drawings, the specific configuration is not limited to this embodiment, and includes designs within the scope of the gist of the present invention.

[0096] 100, 100a, 100b, 100c...communication system, 10...wireless terminal device, 20...receiver, 30...first control unit, 40...delay controller, 50...destination device, 2...base station, 3...transfer device controller, 4...transfer device, 5...server, 20...receiver, 21...second control unit, 22...interface unit, 23...storage unit, 32...interface unit, 33...storage unit, 41...third control unit, 42...interface unit, 43...storage unit, 2b...remote station, 5b...central station, 6...wireless controller, 91...processor, 92...memory, 93...processor, 94...memory, 95...processor, 96...memory

Claims

1. A communications system comprising: a wireless terminal device that divides a single piece of data to be transmitted into multiple packets and transmits the packets wirelessly so that the difference in delay time between adjacent packets in the time direction is equal; a receiver that receives the packets; a destination device that acquires the packets; and a delay controller that buffers the packets received by the receiver and outputs each of the packets in sequence at regular time intervals, wherein the packets acquired by the destination device are packets output by the delay controller, and when a packet is retransmitted, the delay controller outputs each of the buffered packets in sequence at regular time intervals based on a retransmission delay time predetermined in accordance with the identifier or position of the wireless terminal device.

2. The communication system according to claim 1, wherein, when a packet is retransmitted, the delay controller shortens the time interval between packets for which the retransmission has caused a change in the time interval between the packets by the amount of time indicated by the retransmission delay time, thereby aligning the time intervals between each buffered packet to a constant value and outputting the packets.

3. The communication system according to claim 1 or 2, wherein the delay controller buffers the packet received by the receiver for a buffer time estimated in a buffer time estimation process that estimates a buffer time for the data based on terminal information indicating an identifier or location of the wireless terminal device and predetermined retransmission performance information indicating a retransmission probability and a retransmission delay time according to the identifier or location.

4. The communication system according to claim 1, wherein the delay controller is provided in a transfer device.

5. The communication system according to claim 1, wherein the delay controller is provided in a base station.

6. The communication system according to claim 1, wherein the delay controller is provided in a remote station.

7. A communications device comprising: a wireless terminal device that divides a single piece of data to be transmitted into multiple packets and transmits the packets wirelessly so that the difference in delay time between adjacent packets in the time direction is equal; a receiver that receives the packets transmitted by the wireless terminal device; and a delay controller that buffers the received packets and outputs each of the packets in sequence at a fixed time interval; wherein the first control unit controls the operation of the delay controller when a packet is retransmitted, and causes each of the packets buffered in the delay controller to be output in sequence at a fixed time interval based on a retransmission delay time predetermined according to the identifier or position of the wireless terminal device.

8. A communication method executed by a communication system comprising: a wireless terminal device that divides a single piece of data to be transmitted into multiple packets and transmits the packets wirelessly so that the difference in delay time between adjacent packets in the time direction is equal; a receiver that receives the packets; a destination device that acquires the packets; and a delay controller that buffers the packets received by the receiver and outputs each of the packets in sequence at a fixed time interval, wherein the packets acquired by the destination device are packets output by the delay controller, and when a packet is retransmitted, the delay controller outputs each of the buffered packets in sequence at a fixed time interval based on a retransmission delay time predetermined according to the identifier or position of the wireless terminal device, the communication method comprising: an output step in which, when a packet is retransmitted, the delay controller outputs each of the buffered packets in sequence at a fixed time interval based on a retransmission delay time predetermined according to the identifier or position of the wireless terminal device.

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