JP4583859B2 - Communication system, radio communication terminal and base station - Google Patents

Description

  The present invention relates to a communication system, a wireless communication terminal, and a base station.

  In the cellular communication system, one wireless base station performs wireless communication simultaneously with a plurality of wireless communication terminals, and with the recent increase in demand, it is required to increase transmission efficiency. A cdma2000 1xEV-DO method optimized for high-speed packet data is known as a high-speed wireless data communication method that improves the transmission efficiency of a downlink from a wireless base station to a wireless communication terminal.

  The above cdma2000 1xEV-DO system is a standardized version of the HDR (High Data Rate) system, which is an extension of cdma2000 1x by Qualcomm. Std.T-64 1S-2000 CS0024 “cdma2000 High Rate Standardized by the “Packet Data Air Interface Specification”, cdmaOne method currently being serviced by KDDI in Japan (ARIB T-53 in Japan, EIA / TIA / IS-95 etc. in North America, Korea, etc.) However, the cdma2000 1x system corresponding to the third generation system (3G) is a system aimed at further improving the communication speed by specializing in data communication. In cdma2000 lxEV-DO, EV means Evolution and DO means Data only.

  In the cdma2000 1xEV-DO method, when the reception state of the terminal is good by switching the modulation method of data transmitted from the wireless base station to the terminal based on the information notified of the reception state received from the mobile communication terminal Can use a high communication rate with low error tolerance but high speed, and a low speed but high error tolerance when reception is bad.

  In the cdma2000 1xEV-DO downlink direction (the direction from the radio base station to the mobile communication terminal), the time is divided in units of 1/600 second, and only one mobile communication terminal is communicated within that time. In addition, time division multiplex access (TDMA), which communicates with a plurality of mobile communication terminals by switching the communication partner mobile communication terminal according to time, is employed. As a result, the radio base station can always transmit data with the maximum power to each mobile communication terminal, and can perform data communication between mobile communication terminals at the fastest communication speed. (See, for example, Patent Document 1).

  In the cdma2000 1xEV-DO wireless communication system described above, a wireless communication terminal uses wireless packet communication to access a distribution server connected to an Internet (IP) network such as the Internet and receive streaming data such as moving image data. And playback is realized. In this streaming data distribution system, a distribution server packetizes streaming data in response to a distribution request from a wireless communication terminal and transmits the packet to the wireless communication terminal. The transmitted packet is transferred to the packet network (wireless packet network) by the wireless communication system via the IP network, and transferred to the wireless base station connected to the destination wireless communication terminal. The wireless base station wirelessly transmits the received packet to the destination wireless communication terminal according to the wireless communication protocol. The wireless communication terminal verifies the data of the wirelessly received packet, and if there is no problem, reproduces the streaming data.

  In the wireless section between the wireless base station and the wireless communication terminal, transmission data may be erroneous due to deterioration of the wireless environment such as the radio wave condition. The wireless communication terminal requests retransmission to the wireless base station when there is an error in the data of the received packet or for a packet that could not be received within a predetermined time. Upon receiving the retransmission request, the radio base station transmits the corresponding packet held for retransmission to the retransmission request source radio base station. As a result, the retransmission process is executed only in the wireless section, and the packet loss occurring in the wireless section is reduced.

  However, the above-described retransmission processing in the wireless section causes a large delay and jitter in reproducing streaming data. For this reason, conventionally, a time limit value for resending processing is set, and when the resending processing time exceeds the time limit value, the packet to be resent is discarded and resending is stopped and transmitted to the next packet of the data stream. A technique (prior art 1) for switching objects is known.

Also, the transmission speed on the IP network varies according to the amount of traffic that changes from moment to moment, but if the transmission speed on the IP network is slower than the transmission speed of the packet transmitted by the distribution server, Loss will occur. For this reason, a technique (prior art 2) is known in which the transmission speed of the distribution server is dynamically changed in accordance with the reception status such as the data loss rate and data delay time obtained at the receiving terminal.
JP 2002-300634 A

  However, in the above-described prior art 1, when the cause of the packet loss is congestion in the IP network, even if the packet retransmission processing in the wireless section is stopped, the packet loss eventually occurs on the IP network. The re-sending process of the radio section due to the loss is started. As a result, the packet retransmission process due to the packet loss on the IP network and the cancellation of the retransmission process are repeated, which causes a problem that the reproduction of streaming data is not normally performed.

  This problem also occurs when packet loss occurs due to congestion in the wireless packet network. As described above, in the downlink direction of the cdma2000 1xEV-DO method, one radio base station communicates wirelessly with a plurality of mobile communication terminals by time division multiple access, so communication per terminal according to the number of simultaneously connected terminals. The speed fluctuates. Thereby, when the communication speed of the mobile communication terminal becomes less than the transmission speed of the streaming data from the distribution server, packets that cannot be transmitted to the mobile communication terminal are accumulated in the buffer in the radio base station. When this amount of storage increases, the mobile communication terminal does not receive a packet within a predetermined time, so that it is detected as a packet loss and a retransmission is requested to the radio base station. Even in this case, even if the retransmission processing is canceled by the prior art 1 and the packet buffered in the radio base station is discarded, the packet that cannot be transmitted to the mobile communication terminal is not transmitted to the mobile communication terminal unless congestion in the radio packet network is resolved. Since buffering is performed in the station, packet retransmission processing and cancellation of the retransmission processing are repeated.

  Further, in the above-described conventional technique 2, control is performed to reduce the transmission speed of the distribution server even in the case of a reception error (such as packet loss due to a transmission error in the wireless section) unique to the wireless communication system described above. End up. As a result, the transmission speed of the distribution server is reduced during packet retransmission in the wireless section, but this does not contribute to eliminating the delay in reproduction of streaming data, and streaming that requires real-time performance. Not suitable for applications.

  The present invention has been made in consideration of such circumstances, and an object of the present invention is to provide a communication system, a wireless communication terminal, and a base station that can perform appropriate communication control in accordance with a deterioration factor of reception conditions. There is.

In order to solve the above problems, the present invention employs the following means.
The communication system according to the present invention includes a first monitoring unit that monitors a received data amount between a server and a base station, and a notification that notifies a wireless communication terminal of information related to the received data amount obtained by the first monitoring unit. Means, a receiving means for receiving information relating to the received data amount, a second monitoring means for monitoring the received data amount between the base station and the radio communication terminal, and the second monitoring means reception data amount based is rather smaller than the amount of received data of the received, and when said requesting retransmission between the base station and the wireless communication terminal, the retransmission between the base station and the radio communication terminal And a wireless communication terminal having control means for performing control for stopping the communication.

Further, the wireless communication terminal includes a detecting unit that detects a packet loss of data transmitted from the base station, and the control unit detects the second monitoring unit when the detecting unit detects a packet loss. reception data amount based on is less than the amount of received data of the received, and performs the control for stopping the retransmission between the base station and the radio communication terminal.

The base station according to the present invention comprises a monitoring means for monitoring the amount of received data between the server and the base station,
A notification means for notifying a wireless communication terminal of information relating to the amount of received data obtained by the monitoring means; and when the retransmission request is made between the base station and the wireless communication terminal, the wireless communication terminal and the base reception data amount between stations Metropolitan, because less than the amount of received data obtained by the notification, the termination of the retransmission between the from the wireless communication terminal wireless communication terminal and the base station is required, the retransmission Control means for performing stop control.

A wireless communication terminal according to the present invention includes a receiving unit that receives information on a received data amount between a server and a base station from a base station, and a monitor that monitors the received data amount between the base station and the wireless communication terminal. And when the amount of received data based on the monitoring means is less than the received amount of received data when a retransmission is requested between the base station and the wireless communication terminal. and control means for performing control to stop the retransmission between the communication terminal characterized in that it comprises a.

The communication system according to the present invention notifies the wireless communication terminal of the first monitoring means for monitoring the amount of received data between the server and the base station, and information related to the received data amount obtained by the first monitoring means. A base station having a notification means, a receiving means for receiving information relating to the received data amount, a second monitoring means for monitoring the received data amount between the base station and the radio communication terminal, and there is packet loss And a control means for requesting the server to reduce the transmission speed when the received data amount based on the second monitoring means is larger than the received received data amount. It is characterized by that.

The base station according to the present invention includes a monitoring unit that monitors the amount of received data between the server and the base station, a notification unit that notifies the wireless communication terminal of information related to the received data amount obtained by the monitoring unit, and a packet When there is a loss and the amount of received data between the wireless communication terminal and the base station is larger than the notified amount of received data, the wireless communication terminal requests to reduce the transmission speed of the server. And transmitting means for transmitting the request to the server.

A wireless communication terminal according to the present invention includes a receiving unit that receives information on a received data amount between a server and a base station from a base station, and a monitor that monitors the received data amount between the base station and the wireless communication terminal. And a control means for requesting the server to reduce the transmission speed when there is packet loss and the amount of received data based on the monitoring means is larger than the amount of received data received. To do.

  ADVANTAGE OF THE INVENTION According to this invention, appropriate communication control by discrimination | determination of the reception condition degradation factor based on each received data amount of the base station side and the radio | wireless communication terminal side can be performed. As a result, distribution control of streaming data according to the state of the IP network or the wireless packet network can be performed, and the reproduction quality of the streaming data can be improved.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing a configuration of a communication system according to an embodiment of the present invention. In FIG. 1, a wireless communication terminal 1 according to an embodiment of the present invention is a cdma2000 1xEV-DO wireless communication terminal, for example, a mobile phone. The wireless communication terminal according to the present invention is not limited to a portable type. The radio base station 2 is a cdma2000 1xEV-DO base station. The wireless communication terminal 1 is wirelessly connected to the wireless base station 2 and performs voice communication (for example, VoIP) or data communication.

  The wireless base station 2 transmits and receives packets to and from the IP network 3 such as the Internet via a wireless packet network (not shown). The wireless communication terminal 1 can be connected to the IP network 3 via the wireless base station 2.

  The distribution server 4 is connected to the IP network 3 and packetizes streaming data such as moving image data and distributes the packetized data to the distribution requesting terminal via the IP network 3.

  In FIG. 1, the wireless communication terminal 1 accesses the distribution server 4 connected to the IP network 3 by wireless packet communication and requests streaming data such as moving image data. The distribution server 4 packetizes the streaming data in response to a distribution request from the wireless communication terminal 1 and transmits it to the wireless communication terminal 1. The transmitted packet is transferred to the wireless base station 2 connected to the destination wireless communication terminal 1 via the IP network 3. The radio base station 2 transmits the received packet to the destination radio communication terminal 1 via a radio line according to the radio communication protocol. The wireless communication terminal 1 verifies the data of the packet received via the wireless line, and if there is no problem, reproduces the streaming data.

  FIG. 2 is a block diagram showing a configuration of the wireless communication terminal 1 shown in FIG. In FIG. 2, the control unit 11 includes a CPU, a memory, and the like, and controls each unit of the wireless communication terminal 1. The operation unit 12 includes a numeric keypad for inputting a telephone number and the like, various function keys, and the like, and outputs input data to the control unit 11. The display unit 13 includes a display panel such as a liquid crystal display panel and a display control circuit. The display unit 13 receives display data from the control unit 11 and controls display.

  The radio unit 14 transmits and receives radio signals to and from the radio base station 2 via an antenna, and performs voice communication or data communication. The voice control unit 15 processes voice transmitted / received via the wireless unit 14. The microphone 16 inputs sound to the sound control unit 15 under the control of the control unit 11. The speaker 17 outputs a call voice processed by the voice control unit 15 under the control of the control unit 11. The storage unit 18 stores various data used by the control unit 11. The streaming data distributed from the distribution server 4 is stored in the storage unit 24 and is read from the storage unit 24 during reproduction. The received data amount monitoring unit 19 monitors the received data amount based on the received packet received from the radio base station 2. The monitoring data is notified to the control unit 11.

  FIG. 3 is a block diagram showing a configuration of the radio base station 2 shown in FIG. In FIG. 3, the control unit 21 includes a CPU, a memory, and the like, and controls each unit of the radio base station 2. The wireless unit 22 transmits and receives wireless signals to and from the wireless communication terminal 1 via an antenna, and transmits and receives data related to voice communication or data communication by the wireless communication terminal 1. The communication unit 23 connects to the IP network 3 and transmits / receives packets. For example, a packet from the distribution server 4 in FIG. 1 is received, and a packet from the wireless communication terminal 1 is transmitted to the IP network 3.

  The storage unit 24 stores various data used by the control unit 21. The storage unit 24 is provided with a buffer for accumulating packets that cannot be transmitted to the wireless communication terminal 1. In addition, a buffer for holding a packet for retransmission is provided. The received data amount monitoring unit 25 monitors the received data amount for each wireless communication terminal 1 based on the received packet received from the distribution server 4 via the IP network 3. The monitoring data is notified to the control unit 21.

Next, in the communication system shown in FIG. 1, an operation when streaming data is packetized and distributed from the distribution server 4 to the wireless communication terminal 1 will be described.
FIG. 4 is a flowchart showing a flow of data communication control processing by the control unit 11 of the wireless communication terminal 1 shown in FIG.

  The wireless communication terminal 1 periodically receives the received data amount information of the base station from the connected wireless base station 2. This received data amount information indicates the amount of data received by the wireless base station 2 addressed to the wireless base station 2 based on the received packet received from the distribution server 4 via the IP network 3 within a predetermined period. Information. Based on the received data amount information received from the wireless base station 2, the control unit 11 of the wireless communication terminal 1 calculates transition data of the received data amount at the base station. For example, the data reception speed for a certain period is calculated. In addition, the control unit 11 of the wireless communication terminal 1 receives data in the wireless section of the terminal for a certain period based on the received data amount of the terminal transmitted from the wireless base station 2 obtained from the received data amount monitoring unit 19. The transition data of the data amount is calculated similarly.

  The control unit 11 of the wireless communication terminal 1 activates the process of FIG. 4 at a constant cycle. In FIG. 4, the control unit 11 detects the reception status at the terminal itself (step S1). This reception status includes the presence or absence of packet loss. Next, the control unit 11 determines whether or not there is a packet loss (step S2). If the result of this determination is that there is a packet loss (YES in step S2), the control unit 11 compares the received data amount at the base station described above for a predetermined period with the received data amount in the radio section of the terminal itself ( Note that transition data may be used) (step S3). As a result of this comparison, if the received data amount (or transition) is larger in the wireless section than in the section between the base station and the distribution server 4 (YES in step S4), the received packet is stagnated in the base station. Therefore, it can be determined that the received packet from the distribution server 4 is smoothly transferred to the wireless communication terminal 1. That is, it can be determined that the packet loss occurs in the middle of the route of the IP network 3. Accordingly, the control unit 11 requests the distribution server 4 to reduce the packet transmission rate (step S5). In response to this request, the distribution server 4 performs packet transmission at a reduced transmission speed. As a result, if the transmission speed from the distribution server 4 is kept below the transmission speed on the IP network 3, the packet arrives at the wireless communication terminal 1 without loss, and the streaming data is normally played back. It becomes like this.

  On the other hand, as a result of the comparison in step S3, if the received data amount (or transition) in the wireless section is less than the received data amount (or transition) in the section between the base station and the distribution server 4 (NO in step S4). It can be determined that the received packet is stagnated at the base station and the received packet from the distribution server 4 is not smoothly transferred to the wireless communication terminal 1. In this case, the control unit 11 determines whether or not there is a retransmission request in the wireless section in step S6 (step S6). If the result of this determination is that there is a retransmission request (YES in step S6), it can be determined that the received packet has stagnated in the base station as a result of retransmission in the radio section. Thereby, the control part 11 stops resending of a radio area (step S7). In response to this retransmission stop request, the radio base station 2 cancels the retransmission and discards the received packet held for retransmission.

  As a result of the determination in step S6, if there is no retransmission request (NO in step S6), it can be determined that the received packet has stagnated in the base station as a result of congestion in the wireless section. That is, since the number of terminals connected to the same base station is large and the communication speed per terminal is insufficient, the received packet from the distribution server is not smoothly transferred from the base station to the wireless communication terminal 1. I can judge. Accordingly, the control unit 11 requests the distribution server 4 to reduce the packet transmission rate (step S5). In response to this request, the distribution server 4 performs packet transmission at a lower transmission rate. As a result, if the transmission rate from the distribution server 4 is kept below the transmission rate of the wireless section, the packet is lost without stagnation in the base station. Thus, the mobile station arrives at the wireless communication terminal 1 and the streaming data is normally played back.

  If it is determined in step S2 that there is no packet loss (NO in step S2), the control unit 11 considers the reproduction status of the streaming data and transmits a packet to the distribution server 4 as necessary. A request is made to increase the speed (step S8). In response to this request, the distribution server 4 increases the transmission speed and performs packet transmission. Thereby, for example, the wireless communication terminal 1 can receive high-quality video streaming.

  As described above, according to the present embodiment, it is possible to perform appropriate communication control by determining the reception status deterioration factor based on the received data amounts on the radio base station side and the radio communication terminal side. As a result, distribution control of streaming data according to the state of the IP network or the wireless packet network can be performed, and the real-time property and reproduction quality of the streaming data can be improved.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and includes design changes and the like within a scope not departing from the gist of the present invention.

It is a block diagram which shows the structure of the communication system which concerns on one Embodiment of this invention. It is a block diagram which shows the structure of the radio | wireless communication terminal 1 shown in FIG. It is a block diagram which shows the structure of the wireless base station 2 shown in FIG. 3 is a flowchart showing a flow of data communication control processing by a control unit 11 of the wireless communication terminal 1 shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Wireless communication terminal, 2 ... Wireless base station, 3 ... IP network, 4 ... Distribution server, 11, 21 ... Control part, 12 ... Operation part, 13 ... Display part, 14, 22 ... Wireless part, 15 ... Voice control , 16 ... microphone, 17 ... speaker, 18, 24 ... storage unit, 19, 25 ... received data amount monitoring unit, 23 ... communication unit.

Claims (7)

A base station comprising: first monitoring means for monitoring the amount of received data between the server and the base station; and notification means for notifying the wireless communication terminal of information relating to the amount of received data obtained by the first monitoring means; ,
A receiving means for receiving information relating to the received data amount, a second monitoring means for monitoring the received data amount between the base station and the wireless communication terminal, and a received data amount based on the second monitoring means, rather smaller than the amount of received data, if you and requesting retransmission between said base station and the radio communication terminal, and a control means for performing control to stop the retransmission between the base station and the radio communication terminal A wireless communication terminal having
A communication system comprising: The wireless communication terminal has detection means for detecting a packet loss of data transmitted from the base station,
The control means, when the detection means detects a packet loss, if the amount of received data based on the second monitoring means is smaller than the received data amount received, between the base station and the wireless communication terminal The communication system according to claim 1, wherein control for stopping the retransmission is performed. Monitoring means for monitoring the amount of received data between the server and the base station;
Notification means for notifying the wireless communication terminal of information relating to the amount of received data obtained by the monitoring means;
When the retransmission is requested between the base station and the wireless communication terminal, the received data amount between the wireless communication terminal and the base station is smaller than the notified received data amount. When the said suspension retransmission is requested between the communication terminal and the wireless communication terminal and the base station, and a control means for performing stop control of the retransmission,
A base station comprising: Receiving means for receiving information on the amount of received data between the server and the base station from the base station;
Monitoring means for monitoring the amount of received data between the base station and the wireless communication terminal;
If the amount of received data based on the monitoring means is less than the received amount of received data when requesting retransmission between the base station and the wireless communication terminal, the base station and the wireless communication terminal and control means for performing control to stop the retransmission of between,
A wireless communication terminal comprising: A base station comprising: first monitoring means for monitoring the amount of received data between the server and the base station; and notification means for notifying the wireless communication terminal of information relating to the received data amount obtained by the first monitoring means When,
Receiving means for receiving information relating to the amount of received data; second monitoring means for monitoring the amount of received data between the base station and the wireless communication terminal ; and receiving based on the second monitoring means that has packet loss. A wireless communication terminal having control means for requesting the server to reduce the transmission rate when the amount of data is greater than the amount of received data received;
A communication system comprising: Monitoring means for monitoring the amount of received data between the server and the base station;
Notification means for notifying the wireless communication terminal of information relating to the amount of received data obtained by the monitoring means;
Since there is packet loss and the amount of received data between the wireless communication terminal and the base station is larger than the notified amount of received data, the wireless communication terminal requests to reduce the transmission rate of the server. Transmitting means for transmitting the request to the server;
A base station comprising: Receiving means for receiving information on the amount of received data between the server and the base station from the base station;
Monitoring means for monitoring the amount of received data between the base station and the wireless communication terminal;
Control means for requesting the server to reduce the transmission speed when there is packet loss and the amount of received data based on the monitoring means is greater than the amount of received data received;
A wireless communication terminal comprising:

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