Hybrid corrective scheme for dropped packets
AssigneeCisco Technology, Inc.
InventorsDavid Oran, William VerSteeg
Life of this patent
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Abstract
In one embodiment, a hybrid packet repair scheme adaptively switches among unicast retransmission, multicast retransmission, and Forward Error Correction (FEC) depending on the receiver population and the nature of the error prompting the repair operation. The NACK patterns are used to heuristically determine the degree of correlation among packet losses. In an additional embodiment, wasting bandwidth and processing on retransmissions of FEC that will fail to correct the errors is avoided by evaluating the nature of the error and the bandwidth needed to optimally repair it. Unicast retransmission, multicast retransmission, or FEC repair is then dynamically performed according to the loss patterns derived from the NACK arrivals and other network conditions.
Claims19
An apparatus, comprising:
- one or more processors;
- and
- a memory coupled to the one or more processors comprising instructions executable by the processors, at least one of the processors operable, when executing the instructions, to:
- store packets from a media stream;
- monitor lost packet notices identifying lost packets from the media stream;
- increment a lost packet counter entry in a table each time a lost packet notice is received, wherein the table identifies the lost packets and the lost packet counter counts a number of receivers that have lost the packets;
- determine a number and pattern of the identified lost packets based on entries in the table;
- select one or more different schemes for repairing or retransmitting the identified lost packets to one or more receivers in a network according to the number and pattern of the identified lost packets;
- and
- retransmit one or more of the identified lost packets to one or more receivers according to the selected one or more different schemes for repair or retransmission of the identified lost packets from the media stream.
A computer-readable medium having instructions stored thereon, wherein when the instructions are executed by at least one device, the instructions configure the at least one device to:
- receive Negative ACKnowledgment (NACK) messages identifying packets lost from a media stream;
- analyze a distribution of the identified lost packets;
- identify a population of receivers actively receiving the media stream;
- compare the identified receiver population with an amount of network bandwidth available for packet repair and determine a notification density indicating a probability that lost packet messages will be successfully received;
- and
- select between different forward error correction (FEC), unicast or multicast retransmission schemes, or combinations thereof for retransmitting or repairing the identified lost packets according to the notification density.
An apparatus, comprising:
- one or more processors configured to;
- receive a media stream and send back Negative ACKnowledgments (NACKs) for any identified lost media packets from the media stream, the one or more processors then receiving back different types of packet repair schemes for repairing or replacing the lost media packets according to a receiver population and a correlation status with other receivers losing media packets;
- and
- send periodic Real Time Control Protocol (RTCP) receiver reports;
- wherein the receiver population is indicated by RTCP receiver reports;
- and
- wherein the correlation status indicates how different packet losses identified by a portion of the receiver population are related to each other.
An apparatus, comprising:
- one or more processors configured to receive a media stream and send back Negative ACKnowledgments (NACKs) for any identified lost media packets from the media stream, the one or more processors then receiving back different types of packet repair schemes for repairing or replacing the lost media packets according to a receiver population and a correlation status with other receivers losing media packets;
- wherein the one or more processors receive either a unicast retransmission scheme, a multicast retransmission scheme, or a Forward Error Correction (FEC) scheme for repairing the lost media packets;
- the media stream has a primary Multicast Real Time Protocol (RTP) session along with a corresponding Real Time Control Protocol (RTCP) control channel and a unicast repair RTP/RTCP session;
- the unicast repair RTP/RTCP session is used for sending unicast repair packets when the unicast retransmission scheme is selected for repairing the lost packets;
- and
- a second SSM RTP/RTCP multicast session is used for sending multicast repair packets when the multicast retransmission scheme is selected for repairing the lost packets.
Dependencies are inferred from the claim text.