Data transmission method and apparatus
First Claim
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;
comparing (S630, S730, S830) the priority level of the requested data frame with a priority threshold value (Pth); and
retransmitting (S450) the requested data frame if the priority level is greater than said priority threshold value.
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Accused Products
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.
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Citations
12 Claims
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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:
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receiving (S420) at the server a client'"'"'s retransmission request for a data frame;
comparing (S630, S730, S830) the priority level of the requested data frame with a priority threshold value (Pth); and
retransmitting (S450) the requested data frame if the priority level is greater than said priority threshold value. - View Dependent Claims (2, 3, 5, 6, 7, 8, 9, 12)
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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:
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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 (Pth); and
sending (S940) a retransmission request for the missing data frame to the server.
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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:
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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.
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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:
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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.
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Specification