Method and apparatus for communicating delivery of data packets to a user equipment in a wireless communication system
In a communication system ( 100 ) where a wireless relay node (RN) ( 114 ) relays data packets between a Node B ( 112 ) and a user equipment (UE) ( 102 ), the RN receives ( 608 ) a data packet from the Node B via a first wireless link ( 115 ), conveys ( 614 ) the received data packet to the UE via a second wireless link ( 120 ), determines ( 616 ) whether the UE is likely to handoff, and in response to determining that the UE is likely to handoff, delays conveying ( 620, 622 ) an acknowledgment of the data packet to the Node B until an acknowledgment has been received from the UE. In another embodiment, the RN may use a status report ( 720 ) to inform the Node B of data packets that have not been transmitted to the UE or that have been transmitted to the UE but for which an acknowledgement has not been received from the UE.
1. A method for determining at a Node B whether or not a packet has been delivered to a user equipment, the method comprising:
transmitting the packet from the Node B to a relay node;
when the relay node determines that the user equipment is not likely to handoff, receiving at the Node B from the relay node a first acknowledgement, wherein the first acknowledgement indicates that the relay node received the packet from the Node B, before the relay node receives a second acknowledgement, wherein the second acknowledgement indicates that the user equipment received the received packet from the relay node; and
when the relay node determines that the user equipment is likely to handoff and has received the second acknowledgement from the user equipment, receiving at the Node B from the relay node the first acknowledgment.
2. The method of claim 1 , wherein the acknowledgment received at the Node B is a Radio Link Control acknowledgment.
3. The method of claim 1 , further comprising:
storing the packet in a packet buffer at the Node B; and
in response to receiving the acknowledgment at the Node B, deleting the packet from the packet buffer.
4. A Node B, comprising:
a radio frequency transmitter;
a radio frequency receiver; and
a processor that is configured to
control transmission of a packet from the Node B to a relay node, and
control reception at the Node B of a first acknowledgement sent from the relay node, indicating that the relay node received the packet from the Node B, when (1) the relay node determines that the user equipment is not likely to handoff, before the relay node receives a second acknowledgement, wherein the second acknowledgement indicates that the user equipment received the received packet from the relay node, and (2) when the relay node determines that the user equipment is likely to handoff and has received the second acknowledgement from the user equipment.
5. The Node B of claim 4 , wherein the acknowledgment received at the Node B is a Radio Link Control acknowledgment.
6. The Node B of claim 4 , further comprising a packet buffer, and wherein the packet is stored in the packet buffer at the Node B, and in response to receiving the acknowledgment of the packet at the Node B, the packet is deleted from the packet buffer.