JP4884922B2 - Communication apparatus and communication method - Google Patents

Description

  The present invention relates to a communication apparatus and a communication method for performing communication via a wireless communication path.

  In recent years, along with the low price, fixed amount ADSL service, and the reduction in the price of high-speed personal computers, any household can easily access the Internet. In addition, data handled by Internet access has changed from Web pages mainly consisting of text to Web pages mainly consisting of images, sounds, and videos, and the desire for wider bandwidth is increasing for comfortable Web access. A broadband of ADSL and broadband optical communication are becoming widespread.

  In addition, recently, along with the development of a stable and high-speed Internet access environment, free voice call software has been distributed, and it has become possible to use voice calls from home to home for a fixed amount. ing. In the future, with the spread of home networks and the use of HDD recorders as HDD servers, users can access home networks and watch videos stored on HDD servers using computers connected to the network at other locations. Doing so is considered to be widespread. As a result, for example, it is possible to watch Japanese television broadcasting via a home network server while staying abroad.

  In an environment where the home and the Internet network are connected by wire, such as ADSL or optical communication, voice communication and video transfer are performed according to the negotiation at the time of connection, depending on the communication bandwidth between the communicating computers and the processing capacity of the personal computer. By selecting the coding rate accordingly, it is possible to realize a comfortable voice call and video appreciation.

On the other hand, mobile communication terminals mainly for voice calls have recently been in the direction of wider bandwidth and higher functionality, and usage methods mainly for data communication such as access from mobile communication terminals to the Internet network have become mainstream. ing. In connection with this, also in a mobile communication terminal, it is in the direction which performs audio | voice communication and video communication using a data communication network (for example, refer patent document 1).
JP 2004-328593 A

  However, since the mobile communication terminal is a wireless connection, the propagation transmission path is unstable compared to a wired connection such as home ADSL or optical communication. For this reason, the mobile communication terminal selects a wireless communication modulation method according to the propagation path variation, and selects a modulation method that enables high-speed communication when the propagation environment is relatively good. When the propagation environment is poor, continuous communication is made possible by selecting a modulation method having high error tolerance (low-speed communication).

  However, even if the mobile communication terminal that is communicating is stationary, the propagation environment changes according to changes in the surrounding environment, and also changes depending on the characteristics of the frequency used for communication. . Furthermore, when the mobile communication terminal moves, the propagation environment may change suddenly from a stable state.

  For this reason, in the case of wireless communication, as in the case of wired communication, when communication is started with the encoding rate of audio and video set by negotiation at the time of connection, the audio and video are deteriorated as the propagation environment deteriorates. A phenomenon occurs in which data is lost in a wireless environment.

  In wireless communication, a buffer for storing data (packets) is provided in base stations and terminals of the wireless communication network in order to realize high-speed communication. In particular, when the number of users (terminals) wirelessly connected to one base station increases, in order to provide a comfortable communication service for each user, it is necessary to increase the transmission efficiency in each communication. . For this reason, it is necessary to use a modulation method with high transmission efficiency and insert and send a large amount of data in a short time without any gaps. A buffer having the required capacity is prepared.

  Therefore, in the base station, data (packets) corresponding to the encoding rate of audio and video received from the wired side (in the case of a terminal, from the application side) are sequentially stored in the buffer, and the stored data (packets) Are sequentially read and transmitted at a communication speed corresponding to the wireless propagation environment.

  For this reason, when the radio propagation environment deteriorates, the outflow rate of data (packets) from the buffer becomes lower than the inflow rate, the amount of data stored in the buffer increases, and this stored data is recovered in the propagation environment. As a result, a phenomenon occurs in which transmission is delayed.

  However, accumulation of data in the buffer (data retention) is a fatal wound in audio and video communications that require real-time performance, and most of the data is sent out from the buffer due to recovery of the propagation environment. Since the reproduction timing is missed, the data is discarded. In addition, during the period when reading from the buffer is slow, there is a shortage of data to be reproduced on the receiving side, and eventually there is no reproduction data, which may make it difficult to reproduce as audio or video.

  As a method of avoiding such a situation, for example, in an application, a jitter buffer that accumulates data for a time corresponding to fluctuations in the arrival time of data is arranged, and the received data is temporarily accumulated in the jitter buffer, It is known to absorb fluctuations in the arrival time of data by sequentially reading data stored in a jitter buffer in accordance with a reproduction speed in an application.

  However, in the communication path via the wireless communication network, the fluctuation of arrival time is larger than that of the wired network, so that a very large jitter buffer is required to absorb the fluctuation. Therefore, if such a large jitter buffer (a buffer capable of storing a data amount corresponding to a long time) is used, the voice is played back so that it arrives late, and the user feels uncomfortable. Become.

  In addition, as a method to realize audio and video communication with emphasis on real-time characteristics, adapting to wireless propagation environment (change of propagation environment accompanying change of wireless and wired communication path), variable encoding rate, When the propagation environment deteriorates, it is possible to switch to a low-rate encoding method, and when the propagation environment recovers, switch to a high-quality voice or image quality encoding method to maintain real-time characteristics. It is done.

  In this case, it is necessary to detect the propagation environment in the communication path. As one method, for example, when the storage capacity of the data in the jitter buffer is monitored and the storage capacity falls below a predetermined threshold, the propagation environment It is conceivable to detect that data has accumulated on the communication path due to deterioration.

  However, in this case, if the detection of the deterioration is delayed with respect to the sharp deterioration of the propagation environment (narrow band of allowable bandwidth), the data (packet) that stays (accumulates) in the buffer on the communication path for the delayed time The number will increase. For this reason, even if the encoding rate is lowered by detecting the deterioration of the propagation environment, the data is delayed until the stay is eliminated, and the real-time property is impaired.

  Further, as another method for detecting the narrowing of the allowable bandwidth in the wireless communication path, for example, when the number of received packets in the window Ts (predetermined period; for example, 500 ms) is monitored and the number of received packets is smaller than the expected number of packets In addition, a method of detecting that the allowable band is narrowed can be considered.

  However, in this case, the residence delay time varies depending on the timing of the window Ts that is the monitoring period. For example, as shown in FIG. 8, when the packet transmission interval of an application (for example, VoIP) is 20 ms, the allowable bandwidth is narrowed to 50% at time t1. In FIG. 8, the horizontal axis indicates time t, and the vertical axis indicates a packet sequence number (SN). Dp indicates a potential delay time (in this case, 80 ms) from the packet transmission timing to the ideal reception timing in the route, and Tb indicates a reproduction allowable time (in this case, 200 ms) from the packet transmission timing. Ds indicates the residence delay time.

  In FIG. 8, when the number of received packets in the window Ts up to time t1 is monitored, a decrease in the number of received packets is not observed, but when the number of received packets in the window Ts between (t2 and t1) is monitored at time t2, The number of received packets is halved to 12 packets with respect to the assumed number of received packets (500 ms / 20 ms = 25 packets). For this reason, it is necessary to reduce the encoding rate. In this case, since the packet (SN4) transmitted at time t2 is received at time t4, the ideal reception time t3 is obtained. A residence delay time Ds of 580 ms (= t4-t3) is generated.

  For this reason, assuming that a packet (a packet exceeding the reproduction allowable line) received exceeding the reproduction allowable time Tb of 200 ms from the transmission timing is discarded (excluded from reproduction), in this case, the window Ts in FIG. Of the 25 packets transmitted during this period, 23 painted-out packets are discarded without contributing to reproduction.

  As described above, when the number of received packets in the window Ts is monitored and the number of received packets is smaller than the expected number of packets, if it is detected that the allowable bandwidth of the route is narrowed, the timing of the window Ts that is the monitoring period Depending on this, the residence delay time varies. Therefore, depending on the timing of the window Ts, there is a concern that most of the packets transmitted during the window Ts are discarded without contributing to reproduction.

  As a method of reducing the number of discarded packets, it is conceivable to shorten the stay delay time Ds by setting the window Ts short in FIG. However, the number of received packets in the window Ts is inversely proportional to the packet transmission interval on the communication path, and the longer the transmission interval, the smaller the number of received packets.

  For this reason, when the window Ts is set to a short period, it becomes difficult to set a threshold value particularly when the transmission interval is long, and there is a concern that narrowing of the band cannot be accurately detected.

  Accordingly, an object of the present invention made in view of such circumstances is to quickly and accurately detect a change in propagation environment in a wireless communication path, and to minimize the number of packets discarded without being reproduced due to arrival time delay. It is an object of the present invention to provide a communication device and a communication method that can be used.

The invention according to claim 1 that achieves the above object is a communication method for transmitting and receiving a plurality of different data packets to one communication partner via a wireless communication path.
For each of the plurality of different types of data, the wireless communication path is based on packets received via the wireless communication path within a monitoring period corresponding to a transmission interval of packets transmitted to the wireless communication path. Monitor bandwidth status at
Based on the monitoring result, when the transmission band for any one type of data is narrowed, a transmission band control message for reducing the transmission rate of all types of data is transmitted to the communication partner. Is.

Furthermore, the invention according to claim 2 that achieves the above object is a communication method for transmitting and receiving a plurality of different data packets to one communication partner via a wireless communication path.
The wireless state in the wireless communication path is monitored, and each of the plurality of different data is received via the wireless communication path within a monitoring period corresponding to a transmission interval of packets transmitted to the wireless communication path. Based on the received packet, monitoring the bandwidth state in the wireless communication path,
Based on the monitoring result of the wireless state and the monitoring result of the bandwidth state, when the wireless state is good and the transmission bandwidth for any one data is narrowed as the bandwidth state, A transmission band control message for reducing a transmission rate or stopping transmission of data is transmitted to the communication partner;
When the wireless state deteriorates and the transmission band for any one data is narrowed as the band state, a transmission band control message for reducing the transmission rate of all data or stopping the transmission of data is sent to the communication It is characterized by transmitting to the other party.

  According to the present invention, the bandwidth state is monitored based on the packet received within the monitoring period corresponding to the transmission interval of the packet transmitted to the wireless communication path, and the transmission bandwidth control message based on the monitoring result is transmitted to the communication partner. Thus, it is possible to quickly and accurately detect a change in the propagation environment in the wireless communication path, and to appropriately control in real time on the transmission band according to the band state on the transmission side. Therefore, it is possible to minimize the number of packets discarded without being reproduced due to arrival time delay.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1 shows a schematic configuration of a communication system using the communication apparatus according to the first embodiment of the present invention. In FIG. 1, a mobile communication terminal 1 as a communication device can be connected to a wireless network 2 via a wireless communication path. The wireless network 2 is connected to a wired network 3, and a home video server 4 is connected to the network 3. In the present embodiment, the mobile communication terminal 1 is connected to the home video server 4 via a network including the wireless network 2 and the network 3 and receives video data distributed as packets from the home video server 4. Reproduce.

  FIG. 2 is a functional block diagram showing a schematic configuration of main parts of the mobile communication terminal 1 and the home video server 4 shown in FIG. The mobile communication terminal 1 includes a transmission / reception unit 11, an image / audio decoding unit 12, a display unit 13, an audio output unit 14, a received packet monitoring unit 15, and a control unit 16. The transmission / reception means 11 transmits and receives packets wirelessly, and the packet received from the home video server 4 received by the transmission / reception means 11 is supplied to the image / sound decoding means 12, where the image encoded data and the sound encoding are supplied. Each data is decoded, the decoded image signal is supplied to the display means 13 to display an image, and the decoded audio signal is supplied to the audio output means 14 to output sound.

  The (RTP) packet from the home video server 4 received by the transmission / reception unit 11 is supplied to the reception packet monitoring unit 15 where the bandwidth state of the wireless communication path in the wireless network 2 is monitored based on the received packet. The monitoring result is supplied to the control means 16. Therefore, in the present embodiment, the received packet monitoring unit 15 constitutes a bandwidth state monitoring unit. A method of monitoring the bandwidth state of the wireless communication path by the received packet monitoring unit 15 will be described later.

  The control unit 16 controls the overall operation of the mobile communication terminal 1 such as authentication with the home video server 4 via the transmission / reception unit 11. The control unit 16 generates a transmission band control message based on the monitoring result from the received packet monitoring unit 15, and controls the generated transmission band control message to the home video server 4 via the transmission / reception unit 11. Send as a packet. That is, when the reception packet monitoring means 15 obtains a monitoring result indicating that the allowable bandwidth is narrowed, a transmission bandwidth control message indicating that fact is generated and transmitted to the home video server 4 to reduce the bandwidth. In the case of recovery, similarly, a transmission band control message indicating that is generated and transmitted to the home video server 4. Therefore, in the present embodiment, the control means 16 and the transmission / reception means 11 constitute a transmission band control message transmission means.

  On the other hand, the home video server 4 includes a video storage unit 21, an image / audio decoding unit 22, an image / audio encoding unit 23, a transmission / reception unit 24, and a control unit 25. The video storage unit 21 stores video. The video stored in the video storage unit 21 is decoded into an image and a sound by the image / sound decoding unit 22, respectively. The encoded data and the encoded audio data are respectively encoded and transmitted from the transmission / reception means 24 to the network 3 as a packet. The transmission / reception means 24 may be connected to the network 3 by wire, or may be connected to the network 3 via a wireless network different from the wireless network 2.

  The control unit 25 controls the overall operation of the home video server 4 such as authentication with the mobile communication terminal 1 via the transmission / reception unit 24. Further, when receiving a transmission band control message indicating the narrowing of the allowable band from the mobile communication terminal 1, the control unit 25 reduces the encoding rate of the image data and the audio data in the image / audio encoding unit 23. After that, when a transmission band control message indicating recovery of the allowable band is received, control is performed to increase (enhance the quality) the coding rate. The encoding rate is controlled by a method such as changing the quantization table or the encoding method itself.

  Next, a method for monitoring the bandwidth state of the wireless communication path by the received packet monitoring unit 15 of the mobile communication terminal 1 will be described.

  In the present embodiment, a monitoring period corresponding to the packet transmission interval in the wireless communication path of the wireless network 2 is set, and the bandwidth state of the wireless communication path is determined based on the reception timing of sequential packets within the monitoring period. And a transmission bandwidth control message for controlling the transmission bandwidth based on the monitoring result is generated, and the transmission bandwidth control message is transmitted to the packet destination, whereby the transmission bandwidth of the packet in the wireless communication path To control.

  3 to 5 illustrate bandwidth state monitoring results according to the present embodiment. FIG. 3 illustrates the case where the application packet transmission interval is 80 ms. FIG. 4 illustrates the application packet transmission interval. The case of 40 ms is illustrated, and FIG. 5 illustrates the case where the packet transmission interval of the application is 20 ms. 3 to 5, the horizontal axis indicates time t, and the vertical axis indicates a packet sequence number (SN). Tm indicates a monitoring period based on (corresponding to) the packet transmission interval. Other symbols are the same as in FIG. 8, Dp indicates a potential delay time (in this case, 80 ms) from the packet transmission timing to the ideal reception timing in the route, and Tb is a reproduction from the packet transmission timing. The allowable time (here, 200 ms) is indicated, and Ds indicates the residence delay time.

  In the present embodiment, the monitoring period Tm corresponding to the transmission interval of packets transmitted from the home video server 4 is set as a transmission packet period for 5 packets, for example, and the IP packets received within this monitoring period Tm Based on the comparison between the displacement degree α of the reception timing and the calculated degree of displacement α and a threshold value αth corresponding to the packet transmission interval, the communication path is narrowed when α ≦ αth. It is determined that the bandwidth has been reached. In the following equation, s is a reception number assigned to a packet received within the monitoring period Tm, mean is an averaging process, SN is a sequence number of an IP packet, and trec is a reception time.

  In this way, Tm = 400 ms at the packet transmission interval of 80 ms in FIG. 3, Tm = 200 ms at the packet transmission interval of 40 ms in FIG. 4, and Tm = 100 ms at the packet transmission interval of 20 ms in FIG. That is, the shorter the packet transmission interval (the higher the transmission rate), the shorter Tm. Therefore, when the allowable bandwidth becomes narrow during packet transmission at a high transmission rate, it is possible to quickly detect the narrowing of the bandwidth and effectively reduce the number of packets remaining in the communication path. Even when the allowable bandwidth is narrowed during packet transmission at a low transmission rate, it is possible to accurately detect the narrowing of the bandwidth and effectively reduce the number of packets remaining in the communication path.

  For example, in FIGS. 3 to 5, it is assumed that the allowable bandwidth of the wireless communication path is narrowed to 50% from the time t1 when the packet SN1 is received. In this case, in the case of the packet transmission interval of 80 ms in FIG. 3, assuming that narrowing is detected in the monitoring period Tm (t2−t3) at time t3 when the next packet SN3 (indicated by a black circle) is received, The residence delay time Ds generated in the packets transmitted up to t3 is 240 ms. Therefore, in this case, the number of discarded packets exceeding the reproduction allowable line (circled in the figure) is only 2 packets.

  In the case of the packet transmission interval of 40 ms in FIG. 4, the monitoring period Tm (t2-t3) at time t3 when the second packet SN3 (shown by a black circle) is received after receiving the packet SN1 at time t1. If the narrowing of the band is detected, the residence delay time Ds generated in the packet transmitted up to time t3 is 240 ms. Accordingly, in this case, the number of discarded packets exceeding the reproduction allowable line (circled in the figure) is only 3 packets.

  Similarly, in the case of the packet transmission interval of 20 ms in FIG. 5, the monitoring period Tm (t2-t3) at the time t3 when the second packet SN3 (shown by a black circle) is received after the packet SN1 is received at the time t1. ), If the narrowing of the band is detected, the stay delay time Ds generated in the packet transmitted up to time t3 is 160 ms. Therefore, in this case, the number of discarded packets exceeding the reproduction allowable line (circled in the figure) is only 2 packets.

  In this way, the monitoring period Tm corresponding to the packet transmission interval is set, the displacement degree α of the reception timing of the packet received within the monitoring period Tm is calculated, and the calculated displacement degree α and the packet transmission interval are calculated. If the bandwidth state in the wireless communication path is monitored by comparing with the threshold value αth corresponding to, the fluctuation of the allowable bandwidth due to the change of the propagation environment such as fading is almost real-time, adapted to the communication method of the wireless communication path. Can be detected accurately. Therefore, if a narrow band is detected based on the monitoring result, a transmission band control message indicating that is generated, and the transmission band control message is transmitted to the home video server 4 which is a packet destination. In the home video server 4, if the encoding rate of image data and audio data to be transmitted is lowered, the number of packets discarded without being reproduced due to arrival time delay in a real-time application can be minimized. It becomes.

(Second Embodiment)
FIG. 6 shows a schematic configuration of a communication system using the communication apparatus according to the second embodiment of the present invention. In FIG. 6, a mobile communication terminal 51, which is a communication device, can be connected to the wireless network 2 via a wireless communication path. The wireless network 2 is connected to a wired network 3, and a communication terminal 71 such as a personal computer as a communication device is connected to the network 3. The mobile communication terminal 51 and the communication terminal 71 are equipped with communication software. In the present embodiment, the mobile communication terminal 51 and the communication terminal 71 are connected via a network including the wireless network 2 and the network 3, and image data and audio data are mutually transmitted and received in real time. Note that the communication terminal 71 may be connected to the network 3 by wire, or may be connected to the network 3 via a wireless network different from the wireless network 2.

  FIG. 7 is a functional block diagram showing a schematic configuration of main parts of the mobile communication terminal 51 and the communication terminal 71 shown in FIG. Since the mobile communication terminal 51 and the communication terminal 71 have substantially the same configuration, the configuration of the mobile communication terminal 51 will be described below, and the configuration of the communication terminal 71 is the same as that of the mobile communication terminal 51. Reference numerals are assigned and explanations are omitted.

  The portable communication terminal 51 includes an image input unit 52, an audio input unit 53, an image / audio encoding unit 54, a control unit 55, a transmission unit 56, and a storage unit 57, and an image acquired by the image input unit 52. The data or audio data acquired by the audio input means 53 is converted into image encoded data or audio encoded data by the image / audio encoding means 54 under the control of the control means 55, and the transmission means 56. Is sent as a packet to the communication partner.

  The storage unit 57 stores files such as images, sounds, and texts, and the files stored in the storage unit 57 are transmitted as packets from the transmission unit 56 to the communication partner in accordance with a transmission request from the control unit 55.

  The mobile communication terminal 51 includes a receiving unit 58, an image / audio decoding unit 59, a display unit 60, an audio output unit 61, a reproducing unit 62, and a received packet monitoring unit 63, and the communication received by the receiving unit 58. The encoded data (packet) from the other party is supplied to the image / sound decoding means 59, where each is decoded, the decoded image signal is supplied to the display means 60, the image is displayed, and the decoded sound signal is displayed. The sound is supplied to the sound output means 61 and the sound is output.

  Also, the file received by the receiving means 58 is reproduced by the reproducing means 62 by a reproduction method corresponding to the file, and when the reproduction signal is an image signal or the like, it is supplied to the display means 60 and displayed. In this case, it is supplied to the audio output means 61 and outputted.

  Further, the (RTP) packet from the communication partner received by the receiving means 58 is supplied to the received packet monitoring means 63, and here, in the same way as in the first embodiment, based on the received packet in the wireless network 2 The bandwidth state of the wireless communication path is monitored, and the monitoring result is supplied to the control means 55. Therefore, in the present embodiment, the received packet monitoring unit 63 constitutes a bandwidth state monitoring unit.

  As in the case of the first embodiment, the control means 55 generates a transmission band control message based on the monitoring result from the received packet monitoring means 63, and transmits the generated transmission band control message to the transmission means 56. To the other party via That is, when the received packet monitoring means 63 obtains a monitoring result indicating that the allowable bandwidth is narrowed, a transmission bandwidth control message indicating that is generated and transmitted to the communication partner, and the bandwidth narrowing is restored. In this case, similarly, a transmission band control message indicating that is generated and transmitted to the communication partner. Therefore, in the present embodiment, the control means 55 and the transmission means 56 constitute a transmission band control message transmission means.

  Further, in the present embodiment, the transmission band control message is transmitted to the communication partner, and at the same time, the transmission band of the packet transmitted from the own terminal to the communication partner is controlled based on the monitoring result from the received packet monitoring unit 63. That is, when the reception packet monitoring unit 63 obtains a monitoring result indicating narrowing of the allowable bandwidth during transmission of the image data acquired by the image input unit 52 or the audio data acquired by the audio input unit 53, It controls the image / sound encoding means 54 of its own terminal to reduce the encoding rate of data to be transmitted or to temporarily stop transmission. When a monitoring result indicating narrowing of the allowable bandwidth is obtained during transfer of the file stored in the storage means 57, control is performed so that the transfer of the file is interrupted. Note that the coding rate is controlled by a method such as changing the quantization table or the coding method itself, as in the case of the first embodiment.

  Thereafter, if the received packet monitoring means 63 obtains a monitoring result in which the allowable bandwidth has been recovered, a transmission bandwidth control message indicating that fact is transmitted to the communication partner, and at the same time, the image / sound encoding means 54 of its own terminal. On the other hand, control is performed such that the coding rate of data to be transmitted is increased (high quality) or transmission is started. In addition, when the transfer of the file stored in the storage unit 57 is interrupted due to the narrowing of the band, control is performed so that the transfer of the file is resumed.

  On the other hand, when the transmission band control message indicating the narrowing of the allowable band is received from the communication partner, the image / audio encoding unit 54 is similarly controlled to obtain the image data or the audio acquired by the image input unit 52. The reduction or temporary transmission of the audio data encoding rate acquired by the input means 53 is stopped. Further, when the file stored in the storage means 57 is being transferred, control is performed to interrupt the transfer of the file.

  Thereafter, when a transmission band control message indicating that the allowable band has been recovered is received, similarly, the encoding rate of data to be transmitted to the image / audio encoding unit 54 is increased (high quality) or transmitted. Control to start. In addition, when the transfer of the file stored in the storage unit 57 is interrupted due to the narrowing of the band, control is performed so that the transfer of the file is resumed. Therefore, in the present embodiment, the receiving means 58 constitutes a transmission band control message receiving means, and the control means 55 and the image / voice encoding means 54 constitute a transmission band control means.

  In this embodiment, when audio data and image data are transmitted in real time using different RTP packets, the bandwidth narrowing is monitored for each packet, and the bandwidth narrowing is detected in either one of them. In such a case, the encoding rate reduction processing is executed for both, or the encoding rate reduction processing or data reduction is performed for either or both depending on the radio condition (for example, RSSI). Control sending. For example, when a narrowing of the transmission band in one packet, for example, a voice packet, is detected even though the radio state is good, the rate of the detected voice packet of the communication partner is reduced, or data Stop sending. On the other hand, if a narrowing of the transmission band in the voice packet is detected in a state where the wireless state is deteriorated, rate reduction or data transmission is stopped for both the voice packet and the image packet. Further, when a group call can be made with a plurality of communication partners, the above-described control may be performed on each communication partner.

  Also in the present embodiment, similarly to the first embodiment, the monitoring period Tm corresponding to the packet transmission interval is set, and the displacement degree α of the reception timing of the packet received within the monitoring period Tm is calculated. Then, by comparing the calculated degree of displacement α and the threshold value αth corresponding to the packet transmission interval, the bandwidth state in the wireless communication path is monitored. The narrowing of the communication path can be accurately detected almost in real time. Therefore, by controlling the packet rate or data transmission from the communication partner and its own terminal based on the monitoring result, the number of packets discarded without being reproduced due to the arrival time delay in the real-time application It becomes possible to reduce to the minimum at both the other party and the own terminal.

  In addition, this invention is not limited only to the said embodiment, Many deformation | transformation or a change is possible. For example, in the above-described embodiment, the average value of the reception timing difference between sequential packets is calculated as the displacement degree α, but the displacement degree α in this case has a meaning as it is closer to the current time. The closer to the current time, the larger the weight coefficient can be calculated by averaging. Since one or two received packets may deviate greatly from the ideal reception timing, the threshold value αth can be changed according to the number of the received packets. That is, the threshold αth is increased as the number of received packets deviating from the ideal reception timing increases. In this way, erroneous detection can be prevented. In this case, for example, a statistical amount of reception time difference between sequential reception packets is calculated, and a threshold αth is set based on the lowest slope, a minimum value of reception time difference between sequential reception packets, It is also possible to set the threshold value αth based on the minimum value of the reception time difference between one skipped reception packet, the minimum value of the reception time difference between two skipped reception packets, or the like.

  If the degree of displacement α exceeds the threshold αth, the transmission band can be controlled to be wider (the transmission rate is higher) than the current time based on the difference. Furthermore, in the second embodiment, particularly when the frequency division duplex (FDD) method is adopted, the rate control of the transmission packet or the data transmission control in the own terminal based on the monitoring result of the band state in the own terminal is performed. It is possible to omit the transmission packet rate control or the data transmission control by a transmission band control message from the communication partner.

  Furthermore, in the present invention, since the monitoring period corresponds to the packet transmission interval, the number of received packets within the monitoring period is monitored without calculating the degree of displacement as in the above-described embodiment, and the received packet The bandwidth state can be monitored by comparing the number and the number of scheduled received packets (threshold value) corresponding to the packet transmission interval.

It is a figure which shows schematic structure of the communication system using the communication apparatus which concerns on 1st Embodiment of this invention. It is a functional block diagram which shows schematic structure of the principal part of the portable communication terminal and home video server which were shown in FIG. It is a figure which shows an example of the monitoring result of the band state by 1st Embodiment. It is a figure which shows the other example of the monitoring result of the band state by 1st Embodiment. It is a figure which shows the further another example of the monitoring result of the band state by 1st Embodiment. It is a figure which shows schematic structure of the communication system using the communication apparatus which concerns on 2nd Embodiment of this invention. It is a functional block diagram which shows schematic structure of the principal part of the portable communication terminal shown in FIG. 6, and a communication terminal. It is a figure for demonstrating the determination method of the transmission band which uses a monitoring period, and the malfunction in that case.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Mobile communication terminal 2 Wireless network 3 Network 4 Home video server 11 Transmission / reception means 12 Image | voice audio | voice decoding means 13 Display means 14 Audio | voice output means 15 Received packet monitoring means 16 Control means 21 Image | video storage means 22 Image | voice / audio decoding means 23 Audio encoding means 24 Transmission / reception means 25 Control means 51 Mobile communication terminal 52 Image input means 53 Audio input means 54 Image / audio encoding means 55 Control means 56 Transmission means 57 Storage means 58 Reception means 59 Image / audio decoding means 60 Display means 61 Voice output means 62 Playback means 63 Received packet monitoring means 71 Communication terminal

Claims (2)

In a communication method for transmitting / receiving a plurality of different data packets to one communication partner via a wireless communication path,
For each of the plurality of different types of data, the wireless communication path is based on packets received via the wireless communication path within a monitoring period corresponding to a transmission interval of packets transmitted to the wireless communication path. Monitor bandwidth status at
Based on the monitoring result, when the transmission band for any one type of data is narrowed, a transmission band control message for reducing the transmission rate of all types of data is transmitted to the communication partner. Communication method. In a communication method for transmitting / receiving a plurality of different data packets to one communication partner via a wireless communication path,
The wireless state in the wireless communication path is monitored, and each of the plurality of different data is received via the wireless communication path within a monitoring period corresponding to a transmission interval of packets transmitted to the wireless communication path. Based on the received packet, monitoring the bandwidth state in the wireless communication path,
Based on the monitoring result of the wireless state and the monitoring result of the bandwidth state, when the wireless state is good and the transmission bandwidth for any one data is narrowed as the bandwidth state, A transmission band control message for reducing a transmission rate or stopping transmission of data is transmitted to the communication partner;
When the wireless state deteriorates and the transmission band for any one data is narrowed as the band state, a transmission band control message for reducing the transmission rate of all data or stopping the transmission of data is sent to the communication A communication method characterized by transmitting to a partner.

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