Method and system for improving performance of broadcast/multicast transmissions
View Patent ↗Methods and systems for performing hybrid automatic repeat request (ARQ) in conjunction with broadcast/multicast channels are presented. In particular, an access node may transmit a series of hybrid ARQ subpackets to one or more client nodes using a broadcast/multicast channel. Each of the subpackets may be derived from the same full packet. Upon receiving a subpacket, a client node may attempt to decode the full packet from the subpacket(s) derived from the full packet. If the client node fails to do so, the client node may transmit a negative acknowledgement to the access node. If the access node receives more than a threshold extent of negative acknowledgements, the access node may transmit a subsequent subpacket in the series on the broadcast/multicast channel.
1. A method comprising:
transmitting, by an access node, a subpacket in a series of subpackets to a plurality of client nodes, wherein the subpacket is broadcast or multicast to the client nodes on a channel;
receiving feedback signals from more than a threshold number of the plurality of client nodes, wherein the feedback signals negatively acknowledge the subpacket; and
in response to receiving the feedback signals from more than the threshold number of the plurality of client nodes, transmitting a subsequent subpacket in the series of subpackets, wherein the subsequent subpacket is broadcast or multicast on the channel.
2. The method of claim 1 , wherein the feedback signals are received from a feedback channel, wherein the feedback channel comprises a plurality of sub-channels, and wherein each of the feedback signals is received on a different one of the plurality of sub-channels.
3. The method of claim 1 , wherein there are M client nodes in the plurality of client nodes, and wherein the threshold number is between 2 and M−1, inclusive.
4. The method of claim 1 , wherein the threshold number is based on a percentage of the client nodes in the plurality of client nodes.
5. The method of claim 1 , wherein the feedback channel operates according to code division multiple access (CDMA), and wherein each sub-channel is associated with a unique CDMA code.
6. The method of claim 1 , wherein the feedback channel operates according to time division multiple access (TDMA), and wherein each sub-channel is a timeslot within the feedback channel.
7. The method of claim 1 , wherein the subpacket and subsequent subpacket are both derived from a full packet.
8. A method comprising:
receiving, by a client node, a subpacket in a series of subpackets, wherein the subpacket is broadcast or multicast to the client node on a channel by an access node, wherein the subpacket was derived from a full packet;
determining that the full packet cannot be decoded from the subpacket;
transmitting, to the access node, a first negative acknowledgement on a first sub-channel of a plurality of sub-channels of a feedback channel;
after transmitting the first negative acknowledgement, determining that the client node has not received a subsequent subpacket in the series of subpackets;
transmitting, to the access node, a second negative acknowledgement on a second sub-channel of the plurality of sub-channels of the feedback channel.
9. The method of claim 8 , wherein the feedback channel operates according to code division multiple access (CDMA), and wherein each sub-channel is associated with a unique CDMA code.
10. The method of claim 8 , wherein the feedback channel operates according to time division multiple access (TDMA), and wherein each sub-channel is a timeslot within the feedback channel.
11. The method of claim 8 , wherein transmitting the first negative acknowledgement comprises choosing the first sub-channel randomly, and wherein transmitting the second negative acknowledgement comprises choosing the second sub-channel randomly.
12. The method of claim 11 , wherein the bearer channel is associated with a group of sub-channels of the feedback channel, and wherein choosing the first sub-channel comprises choosing the first sub-channel from the group of sub-channels.
13. The method of claim 8 , further comprising:
after determining that the client node has not received the subsequent subpacket in the series of subpackets, waiting a random period of time before transmitting the second negative acknowledgement.
14. An access node comprising:
a processor;
data storage;
program instructions, stored in the data storage, that when executed by the processor cause the access node to perform operations comprising:
transmitting a subpacket in a series of subpackets to a plurality of client nodes, wherein the subpacket is broadcast or multicast to the client nodes on a bearer channel;
receiving feedback signals from more than a threshold number of the plurality of client nodes, wherein the feedback signals negatively acknowledge the subpacket; and
in response to receiving the feedback signals from more than the threshold number of the plurality of client nodes, transmitting a subsequent subpacket in the series of subpackets, wherein the subsequent subpacket is broadcast or multicast on the bearer channel.
15. The access node of claim 14 , wherein the feedback signals are received from a feedback channel, wherein the feedback channel comprises a plurality of sub-channels, and wherein each of the feedback signals is received on a different one of the plurality of sub-channels.
16. The access node of claim 14 , wherein there are M client nodes in the plurality of client nodes, and wherein the threshold number is between 2 and M−1, inclusive.
17. The access node of claim 14 , wherein the threshold number is based on a percentage of the client nodes in the plurality of client nodes.
18. The access node of claim 14 , wherein the feedback channel operates according to code division multiple access (CDMA), and wherein each sub-channel is associated with a unique CDMA code.
19. The access node of claim 14 , wherein the feedback channel operates according to time division multiple access (TDMA), and wherein each sub-channel is a timeslot within the feedback channel.
20. The access node of claim 14 , wherein the subpacket and subsequent subpacket are both derived from a full packet.