Data transmission method and apparatus

• US 20020004838A1
• Filed: 03/02/2001
• Published: 01/10/2002
• Est. Priority Date: 03/02/2000
• Status: Active Grant

• Current Assignee: Sovereign Peak Ventures, LLC (Dominion Harbor Enterprises, LLC)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Hakenberg, Rolf, Burmeister, Carsten, Wiebke, Thomas
• Granted Patent: US 6,792,470 B2
• Time in Patent Office: Days
• US Class Current: 709/231
• CPC Class Codes: H04L 1/1678 where the control information is for timing, e.g. time stamps
• CPC Class Codes: H04L 1/1809 Selective-repeat protocols
• CPC Class Codes: H04L 1/1854 Scheduling and prioritising arrangements
• CPC Class Codes: H04L 1/1887 Scheduling and prioritising arrangements
• CPC Class Codes: H04L 65/1101 Session protocols
• CPC Class Codes: H04L 65/612 for unicast
• CPC Class Codes: H04L 65/70 Media network packetisation
• CPC Class Codes: H04L 65/80 Responding to QoS
• CPC Class Codes: H04L 9/40 Network security protocols
• CPC Class Codes: H04N 19/89 involving methods or arrangements for detection of transmission errors at the decoder
• CPC Class Codes: H04N 21/2402 Monitoring of the downstream path of the transmission network, e.g. bandwidth available traffic monitoring in data switching networks H04L43/00; monitoring data switching networks utilization H04L43/0876
• CPC Class Codes: H04N 21/2404 Monitoring of server processing errors or hardware failure error or fault detection G06F11/07; monitoring in general G06F11/30
• CPC Class Codes: H04N 21/2408 Monitoring of the upstream path of the transmission network, e.g. client requests monitoring data switching networks utilization H04L43/0876; scheduling or organising the servicing of application requests H04L67/60
• CPC Class Codes: H04N 21/26216 involving the channel capacity, e.g. network bandwidth admission control, resource allocation in open networks H04L12/5692; flow control in packet networks H04L47/10; establishing a schedule or organising the servicing of application requests taking into account QoS H04L67/61
• CPC Class Codes: H04N 21/44209 Monitoring of downstream path of the transmission network originating from a server, e.g. bandwidth variations of a wireless network arrangements for maintenance or administration in data switching networks involving bandwidth and capacity management H04L41/0896
• CPC Class Codes: H04N 21/6375 for requesting retransmission , e.g. of data packets lost or corrupted during transmission from serverARQ protocols H04L1/18; implementation or adaptation of Internet protocol [IP], of transmission control protocol [TCP] or of user datagram protocol [UDP] H04L69/16
• CPC Class Codes: H04N 21/6377 directed to server one-way streaming services wherein the source is controlled by the destination H04L65/613
• CPC Class Codes: H04N 21/643 Communication protocols network streaming protocols, e.g. real-time transport protocol [RTP] or real-time control protocol [RTCP], H04L65/65
• CPC Class Codes: H04N 21/658 Transmission by the client directed to the server

Abstract

The invention relates to a method and apparatus for transmitting and receiving video data arranged in data frames forming a data stream. Each frame has assigned a priority level. Once a data frame has been transmitted through an unreliable channel and has not been received at the receiver, the priority level of the missing data frame is compared with a priority threshold value, and is then retransmitted if its priority level is greater than the priority threshold value. The retransmission decision is performed either at the transmitting or at the receiving side. According to a preferred embodiment, the priority level of any data frame to be transmitted is compared with the threshold value. The priority decision may involve the calculation of the priority threshold value based on a measurement of the available channel bandwidths and eventually on the bit rate of previously sent frames. The retransmission decision further may include an estimation of the arrival time of the data frame to be retransmitted.

Claims

1. Method for transmitting video data from a server to a client, said data being arranged in data frames forming a data stream, each frame having assigned a priority level, the method comprising the steps of:

receiving (S420) at the server a client'"'"'s retransmission request for a data frame;

a comparing (S630, S730, S830) the priority level of the requested data frame with a priority threshold value (P_th); and

retransmitting (S450) the requested data frame if the priority level is greater than said priority threshold value.

2. The method according to claim 1, further comprising the step of comparing the priority level of any data frame to be transmitted with said priority threshold value.

3. The method according to claim 1 or 2, wherein the retransmission request includes the reception times and frame lengths of at least two preceding data frames.

5. The method according to one of claims 1 to 4, wherein the frames having assigned a priority level include P-frames.

6. The method according to one of claims 1 to 5, wherein the assignment of priority levels to frames is performed according to the logical depth of the multidependency of the respective frame.

7. The method according to one of claims 1 to 6, wherein the step of comparing includes the steps of measuring (S710) the available channel bandwidth (B_ch) and calculating (S720, S820) said priority threshold value based on the measured bandwidth.

8. The method according to claim 7, wherein the step of comparing further includes the step of measuring (S810) the bit rate (B_s) of previously sent frames, wherein said priority threshold value is calculated based on the measured bandwidth and the measured bit rate.

9. The method according to one of claims 1 to 8, further comprising the step of estimating the data frame arrival time and comparing the estimated arrival time with the desired arrival time for suppressing transmission if the estimated arrival time is not before the desired arrival time.

12. The apparatus according to claim 10 or 11, arranged for performing the method according to one of claims 1 to 9.

4. Method for receiving video data from a server, said data being arranged in data frames forming a data stream, each frame having assigned a priority level, the method comprising the steps of:

detecting (S920) that a data frame is missing;

comparing (S630, S730, S830) the priority level of the missing data frame with a priority threshold value (P_th); and

sending (S940) a retransmission request for the missing data frame to the server.

10. Apparatus for transmitting video data to a client, said data being arranged in data frames forming a data stream, each frame having assigned a priority level, the apparatus comprising:

receiver means (230) for receiving a retransmission request from the client for a data frame;

a controller (210) for comparing the priority level of the requested data frame with a priority threshold value; and

transmitter means (130, 220) for retransmitting the requested data frame if the priority level is greater than said priority threshold value.

11. Apparatus for receiving video data from a server, said data being arranged in data frames forming a data stream, each frame having assigned a priority level, the apparatus comprising:

detection means (240) for detecting that a data frame is missing;

a controller for comparing the priority level of the missing data frame with a priority threshold value; and

transmitter means (250) for sending a retransmission request for the missing data frame to the server.