JP2010283677A - Communication apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a communication apparatus for determining TS_STRIDE required for TS (Time Stamp) reproduction. <P>SOLUTION: This invention relates to a compression side communication apparatus 20, which compresses header information of a packet received from a packet transmitting terminal and transfers a packet, of which the header information has been compressed, to a decoding-side communication apparatus 30, including: a storage section 2 for storing the header information of the packet; and a control section 1 which performs control for transferring the packet received form the packet transmitting terminal to the decoding-side communication apparatus 30 and compresses the header information of the packet as needed. The control section 1 stores, in the storage section 2, the header information of the packet received from the packet transmitting terminal, determines TS_STRIDE to be used for reproducing the compressed header information based on header information of a latest packet received from the packet transmitting terminal and the header information of the last received packet stored in the storage section 2, and notifies the decoding-side communication apparatus 30 of the determined TS_STRIDE. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a communication apparatus that compresses and transmits header information in packet transmission.

  3GPP (3rd Generation Partnership Project), 3GPP LTE (Long Term Evolution), and other wireless access networks (BTS: Base Transceiver Station), radio network control equipment (RNC: Radio Network Control), mobile stations Communication devices such as (MS: Mobile Station) increase the transmission efficiency by compressing and transmitting the header part during packet transmission. For example, in RTP (Real-time Transport Protocol) that delivers a data stream such as a moving image in real time, a compression technique by ROHC (RObust Header Compression) is common.

  In a communication device (Compressor: compression side communication device) that compresses header information by ROHC and transmits a packet, before compressing the header information and starting packet transmission, TS (Time Stamp) that is time information, Communication device that receives packet and decodes header information with SN (Sequence Number) indicating transmission order and TS_STRIDE (RTP packet transmission cycle time / encoded sampling cycle time) that is the TS increase number according to the SN increase number (Decompressor: Decoding side communication device) After that, the compression side communication apparatus compresses and transmits the header information in the subsequent packets, and in the most efficient case, transmits only the SN as the compressed header information and does not transmit the other header information. The decoding-side communication apparatus that has received the packet in which the header information is compressed reproduces the TS using the SN and TS_STRIDE. Such a technique is disclosed in Non-Patent Document 1 below.

IETF RFC4815 RObust Header Compression (ROHC): Corrections and Clarifications to RFC 3095 4.2 (De) compression of TS without Transmitted TS Bits 2007

  However, according to the above-described conventional technology, a clear determination method and standard of TS_STRIDE are not defined. For this reason, if TS_STRIDE is not properly defined in the compression side communication device, there is a problem that even if the compression side communication device transmits only SN, the decoding side communication device may not be able to reproduce the TS.

  The present invention has been made in view of the above, and an object of the present invention is to obtain a communication apparatus that determines TS_STRIDE required for TS playback.

  In order to solve the above-described problems and achieve the object, the present invention is a communication device that compresses header information of a packet received from a packet transmission terminal and transfers the packet in which the header information is compressed to a reception device. Storage means for storing packet header information, and control for transferring a packet received from the packet transmission terminal to the receiving device. In the control, packet header information is stored as necessary. Compression means, and the control means stores the header information of the packet received from the packet transmission terminal in the storage means, the header information of the latest packet received from the packet transmission terminal, When reproducing the compressed header information based on the header information of the previously received packet stored in the storage means Determining a parameter for use, and notifies the parameters to the receiving device, characterized in that.

  According to the present invention, there is an effect that the TS can be reproduced in the decoding-side communication device.

FIG. 1 is a diagram illustrating a process of reproducing a TS. FIG. 2 is a diagram illustrating a configuration example of a wireless communication system. FIG. 3 is a diagram illustrating a method for determining TS_STRIDE. FIG. 4 is a diagram illustrating a configuration example of the parameter storage area on the memory. FIG. 5 is a diagram illustrating a method for determining TS_STRIDE. FIG. 6 is a flowchart showing TS_STRIDE determination processing. FIG. 7 is a diagram illustrating a configuration example of the parameter storage area on the memory. FIG. 8 is a diagram illustrating a method for determining TS_STRIDE. FIG. 9 is a diagram illustrating a configuration example of a reference table in which TS_STRIDE is registered.

  Embodiments of a communication apparatus according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment 1 FIG.
First, in a conventional RTP packet communication, a process until a decoding side communication apparatus that has received a packet with compressed header information reproduces a TS will be described. FIG. 1 is a diagram illustrating processing of the compression-side communication device and the decoding-side communication device until the TS is reproduced. For example, when the compression side communication device receives an RTP packet from an RTP transmission terminal at a certain point in time, an IR packet at the start of communication (a packet to be transmitted after receiving an RTP packet with SN = a and TS = TS0 from the RTP transmission terminal) Or TS_STRIDE together with the TS and SN information by an IR-DYN packet (packet transmitted after receiving an RTP packet with SN = a + 1 and TS = TS1 from the RTP transmitting terminal) for updating information on the decoding side communication device Is transmitted to the decoding-side communication device. Thereafter, the compression side communication device starts transmission of a packet in which the header portion is compressed. At this time, as the header information, only the variable SN (here, SN = a + 2) is transmitted for each packet.

  The decoding-side communication apparatus can reproduce the TS as “TS = TS1 + TS_STRIDE × (a + 2− (a + 1)) = TS2” by using the received SN (a + 2) and the previously received TS_STRIDE. However, if TS_STRIDE is not properly defined, the value of TS2 may not be correctly decoded even if TS_STRIDE is used. Therefore, a method for appropriately defining the value of TS_STRIDE will be described below. Note that description of packets (such as ACK packets) transmitted from the decoding-side communication device is omitted.

  FIG. 2 is a diagram illustrating a configuration example of a wireless communication system including a compression-side communication device. The wireless communication system includes an RTP transmission terminal 10, a compression side communication device 20, and a decoding side communication device 30. Here, the compression side communication device 20 receives the RTP packet transmitted from the RTP transmission terminal 10 and transmits the received RTP packet to the decoding side communication device 30. When transmitting to the decoding side communication device 30, the compression side communication device 20 compresses and transmits the packet header information as necessary.

  The compression-side communication device 20 includes a control unit 1 and a storage unit 2. The control unit 1 performs control for receiving a packet from the RTP transmission terminal 10 and transmitting the received packet to the decoding-side communication device 30. At this time, packet header information is compressed as necessary and transmitted. The storage unit 2 is a memory for storing the header information of the packet received from the RTP transmission terminal 10 and the calculated TS_STRIDE.

  FIG. 3 is a diagram illustrating a method for determining TS_STRIDE according to the present embodiment. In RTP communication in which the ROHC header compression protocol has not yet been activated, first, when the compression side communication device 20 receives the first RTP packet (1-1) of SN = a and TS = TS0 from the RTP transmission terminal 10, The control unit 1 records the SN and TS values on the memory of the storage unit 2. FIG. 4 is a diagram illustrating a configuration example of a parameter storage area on the memory of the storage unit 2. Values such as TS and SN can be stored for each ROHC section.

  Next, when the compression-side communication device 20 receives the RTP packet (1-2) with SN = a + 1 and TS = TS1 from the RTP transmission terminal 10, the control unit 1 determines that the SN, TS value, and storage unit 2 “TS_STRIDE = (TS1−TS0) / ((a + 1) −a) = TS1−TS0” is calculated using the TS and SN information (TS = TS0, SN = a) read out from the RTP, and the value is calculated as this RTP. It is determined as TS_STRIDE related to communication. That is, the control unit 1 calculates TS_STRIDE based on the RTP packet received from the RTP transmission terminal 10. The control unit 1 records the calculated value on the memory of the storage unit 2 as TS_STRIDE (see FIG. 4).

  Next, the control unit 1 of the compression-side communication device 20 transmits the packet (1-3) with the calculated TS_STRIDE attached to the header information to the decoding-side communication device 30. As a packet used for transmission, an IR packet can be used, but an IR-DYN packet can also be used as in the prior art. The decoding-side communication device 30 can reproduce the TS by using TS_STRIDE calculated based on the actually received packet. The TS playback method can be played back in the same manner as before (see FIG. 1).

  As described above, in the present embodiment, the control unit 1 of the compression-side communication device 20 calculates TS_STRIDE using the TS and SN values of the RTP packet received twice from the RTP transmission terminal 10. . Thereby, since the decoding side communication apparatus 30 can use TS_STRIDE based on the actual measurement value, it is possible to avoid a situation in which the TS cannot be reproduced.

Embodiment 2. FIG.
In the present embodiment, the compression-side communication apparatus determines the TS_STRIDE after calculating the temporary TS_STRIDE several times. Hereinafter, a different part from Embodiment 1 is demonstrated.

  In the present embodiment, the configurations of the wireless communication system and the compression side communication device are the same as those in FIG. 2, but the compression side communication device 20, the control unit 1, and the storage unit 2 are respectively connected to the compression side for convenience of explanation. The communication device 20a, the control unit 1a, and the storage unit 2a are assumed.

  FIG. 5 is a diagram illustrating a method for determining TS_STRIDE according to the present embodiment. Here, the process determined based on a flowchart is demonstrated. FIG. 6 is a flowchart showing TS_STRIDE determination processing.

  First, when the compression side communication device 20a receives the first RTP packet (2-1) with SN = a and TS = TS0 from the RTP transmission terminal 10 (step S1), the TS_STRIDE of the corresponding session has been determined here. However, since the TS and SN are not recorded on the memory of the storage unit 2a (step S3: No), the control unit 1a uses the TS and SN values in the memory of the storage unit 2a. Record above (step S4). FIG. 7 is a diagram illustrating a configuration example of the parameter storage area on the memory of the storage unit 2a. Values such as TS and SN can be stored for each ROHC section. Unlike the case of FIG. 4, there is a storage area for storing TMP_TS_STRIDE, which is a temporary TS_STRIDE.

  When the TS_STRIDE of the corresponding session has already been determined (step S2: Yes), the control unit 1a receives an RTP packet for determining TS_STRIDE in the next session (step S1).

  Next, when the compression side communication device 20a receives the RTP packet (2-2) with SN = a + 1 and TS = TS1 from the RTP transmission terminal 10 (step S1), the TS_STRIDE of the corresponding session is not determined (step S1). S2: No), since TS and SN are recorded in the memory of the storage unit 2a (step S3: Yes), the control unit 1a stores the SN = a + 1 and TS = TS1 of the RTP packet (2-2). "TS_STRIDE = (TS1-TS0) / ((a + 1) -a) = TS1-TS0" is calculated using the TS and SN information (TS = TS0, SN = a) read from the memory of the unit 2a ( In step S5), the value is recorded on the memory of the storage unit 2a as TMP_TS_STRIDE # 0 related to this RTP communication (step S6).

  The control unit 1a reads the number of measurements M_num on the memory of the storage unit 2a (step S7), and M_num = 2, but since the number of currently used TMP_TS_STRIDE on the memory is one (step S7: No), the calculation is performed. The TMP_TS_STRIDE # 0 is determined not to be determined as TS_STRIDE, and SN = a + 1 and TS = TS1 set in the RTP packet (2-2) are recorded in the memory of the storage unit 2a (step S4).

  Next, when the compression side communication apparatus 20a receives the RTP packet (2-3) of SN = a + 2 and TS = TS2 from the RTP transmission terminal 10 (step S1), the TS_STRIDE of the corresponding session is not determined (step S1). (S2: No), since TS and SN are recorded in the memory of the storage unit 2a (step S3: Yes), the control unit 1a stores the SN = a + 2 and TS = TS2 of the RTP packet (2-3). “TS_STRIDE = (TS2−TS1) / ((a + 2) − (a + 1)) = TS2−TS1” is calculated using the TS and SN information (TS = TS1, SN = a + 1) read from the memory of the unit 2a. (Step S5), and the value is recorded on the memory of the storage unit 2a as TMP_TS_STRIDE # 1 related to the RTP communication (Step S5). 6).

  The control unit 1a reads the number of measurements M_num on the memory of the storage unit 2a (step S7), M_num = 2, and the number of currently used TMP_TS_STRIDE on the memory is two, TMP_TS_STRIDE # 0 and TMP_TS_STRIDE # 1. Therefore, the value of TMP_TS_STRIDE # 0, which is the currently used TMP_TS_STRIDE, is compared with the value of TMP_TS_STRIDE # 1 (step S8). When the two values are the same (step S8: Yes), the control unit 1a determines this value as TS_STRIDE (step S9) and records it in the memory of the storage unit 2a. When the two values are not the same (step S8: No), the control unit 1a deletes all TMP_TS_STRIDE recorded in the memory of the storage unit 2a (step S10).

  Note that the packet (2-4) for transmitting the calculated TS_STRIDE to the decoding side communication device 30 by the control unit 1a of the compression side communication device 20a is an IR packet or an IR-DYN packet as in the first embodiment. be able to.

  As described above, in the present embodiment, the control unit 1a of the compression-side communication device 20a determines the value after calculating the temporary TS_STRIDE value a plurality of times. Thereby, since TS_STRIDE in a stable communication state can be calculated, it is possible to avoid a situation where reproduction cannot be further performed when the decoding-side communication device 30 reproduces a TS, as compared with the first embodiment.

  In addition, although the case where the frequency | count of measurement was 2 was demonstrated, it is not limited to this, It is applicable also to the case where it is 3 times or more.

Embodiment 3 FIG.
In this embodiment, TS_STRIDE is determined based on the payload type value set in the header information of the RTP packet. Hereinafter, a different part from Embodiment 1, 2 is demonstrated.

  In the present embodiment, the configurations of the wireless communication system and the compression side communication device are the same as those in FIG. 2, but the compression side communication device 20, the control unit 1, and the storage unit 2 are respectively connected to the compression side for convenience of explanation. Assume that the communication device 20b, the control unit 1b, and the storage unit 2b. The storage unit 2b is a memory for storing TS_STRIDE corresponding to the payload type value.

  FIG. 8 is a diagram illustrating a method for determining TS_STRIDE according to the present embodiment. First, when the compression side communication device 20b receives the RTP packet (3-1) from the RTP transmission terminal 10, the control unit 1b sets a payload type value (here, a value of X) set as header information of the RTP packet. ). Next, the control unit 1b refers to the reference table on the memory of the storage unit 2b, reads TS_STRIDE corresponding to the extracted payload type X, and determines the value as TS_STRIDE.

  FIG. 9 is a diagram illustrating a configuration example of a reference table in which TS_STRIDE corresponding to the payload type value on the memory of the storage unit 2b is registered. For example, a G.P. In the case of 721, since the RTP transmission cycle is 20 msec and the signal sampling frequency is 8 kHz, the value “0.02 / (1/8000) = 160” can be registered in advance.

  Note that the packet (3-2) for transmitting the read TS_STRIDE to the decoding-side communication device 30 by the control unit 1b of the compression-side communication device 20b is an IR packet or an IR-DYN packet as in the first and second embodiments. Can be done.

  As described above, in the present embodiment, TS_STRIDE corresponding to the payload type value is prepared in advance in the memory of the storage unit 2b based on the transmission cycle and signal sampling frequency specified by the payload type, and compression side communication is performed. The control unit 1b of the device 20b determines the value read from the memory as TS_STRIDE based on the payload type of the received packet. As a result, it is possible to reduce the TS_STRIDE determination time in the compression-side communication device 20b, and avoid the situation where the decoding-side communication device 30 cannot reproduce the TS.

  As described above, the communication device according to the present invention is useful for packet communication, and is particularly suitable as a device for compressing and transmitting header information.

DESCRIPTION OF SYMBOLS 1 Control part 2 Memory | storage part 10 RTP transmission terminal 20 Compression side communication apparatus 30 Decoding side communication apparatus

Claims (7)

A communication device that compresses header information of a packet received from a packet transmission terminal, and forwards the packet in which the header information is compressed to the receiving device,
Storage means for storing packet header information;
Control for transferring the packet received from the packet transmission terminal to the receiving device, and in the control, a control means for compressing the header information of the packet as necessary,
With
The control means is
The header information of the packet received from the packet transmission terminal is stored in the storage means,
Based on the header information of the latest packet received from the packet transmitting terminal and the header information of the previously received packet stored in the storage means, a parameter used when reproducing the compressed header information is determined. , Notifying the reception device of the parameter,
A communication device. A communication device that compresses header information of a packet received from a packet transmission terminal and forwards the packet in which the header information is compressed to a receiving device,
Storage means for storing packet header information and parameter provisionally calculated values;
Control for transferring the packet received from the packet transmission terminal to the receiving device, and in the control, a control means for compressing the header information of the packet as necessary,
With
The control means is
The header information of the packet received from the packet transmission terminal is stored in the storage means,
Further, parameters used when reproducing the compressed header information based on the header information of the latest packet received from the packet transmitting terminal and the header information of the previously received packet stored in the storage means Temporarily calculate and store the temporary calculated value in the storage means;
When the provisional calculation value stored in the storage means reaches a predetermined number, the parameter is determined based on the predetermined number of provisional calculation values, and the parameter is notified to the receiving device;
A communication device. The control means determines the temporary calculated value as the parameter when a predetermined number of temporary calculated values are all the same.
The communication device according to claim 2. A communication device that compresses header information of a packet received from a packet transmission terminal and forwards the packet in which the header information is compressed to a receiving device,
A storage means for storing a correspondence relationship between a payload type value given to the header information of the packet and a parameter used when reproducing the compressed header information;
Control for transferring the packet received from the packet transmission terminal to the receiving device, and in the control, a control means for compressing the header information of the packet as necessary,
With
The control means is
Extract the payload type value attached to the header information of the packet received from the packet transmission terminal,
A parameter corresponding to the extracted payload type value is read from the storage means, and the parameter is notified to the receiving device;
A communication device. The control means notifies the parameter to the receiving device by an IR packet.
The communication device according to any one of claims 1 to 4, wherein The control means notifies the parameter to the receiving device by an IR-DYN packet.
The communication device according to any one of claims 1 to 4, wherein The header information is a time stamp indicating time information and a sequence number indicating a data transmission order,
The parameter is a time stamp stride (TS_STRIDE), which is the number of time stamps that increase each time the packet transmitting terminal transmits a packet.
The communication apparatus according to claim 1, wherein

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