Enhanced uplink operation in soft handover
A method and system for an enhanced uplink (EU) operation in a wireless communication system during soft handover. The system comprises a wireless transmit/receive unit (WTRU), at least two Node-Bs, and a radio network controller (RNC). One Node-B may be designated as a primary Node-B, and the primary Node-B may control EU operation during soft handover including uplink scheduling and hybrid automatic repeat request (H-ARQ). Soft buffer corruption is avoided during soft handover by controlling H-ARQ by the primary Node-B. Alternatively, an RNC may control EU operation during soft handover including H-ARQ. In this case, an RNC generates final acknowledge/non-acknowledge (ACK/NACK) decision based on the error check results of the Node-Bs.
1. A method comprising:
transmitting a data packet to a Node-B via a primary cell and at least one non-primary cell, the primary cell and the at least one non-primary cell being controlled by the Node-B, wherein the data packet is sent via the primary cell and the at least one non-primary cell over an enhanced uplink (EU) channel;
receiving an acknowledgement (ACK) from the Node-B on a condition that the transmitted data packet is successfully decoded; and
receiving a negative acknowledgement (NACK) from the Node-B on a condition that the transmitted data packet is not successfully decoded;
wherein the NACK is received only via the primary cell.
2. The method of claim 1 , wherein the ACK or NACK is received via the primary cell over one or more downlink channels shared by a plurality of wireless transmit/receive units.
3. The method of claim 2 , further comprising:
receiving a shared channel indicator from the primary cell;
wherein the shared channel indicator indicates over which of the one or more downlink channels, downlink messages are allowed to be received.
4. The method of claim 1 , further comprising:
receiving downlink messages via the primary cell during handover.
5. The method of claim 1 , wherein the ACK is received via the primary cell and the at least one non-primary cell.
6. An apparatus comprising:
a transmitter, wherein the transmitter transmits a data packet to a Node-B via a primary cell and at least one non-primary cell, the primary cell and the at least one non-primary cell being controlled by the Node-B, wherein the data packet is sent via the primary cell and the at least one non-primary cell over an enhanced uplink (EU) channel; and
a receiver, wherein the receiver:
receives an acknowledgement (ACK) from the Node-B on a condition that the transmitted data packet is successfully decoded; and
receives a negative acknowledgement (NACK) from the Node-B on a condition that the transmitted data packet is not successfully decoded;
wherein the NACK is received only via the primary cell.
7. The apparatus of claim 6 , wherein the ACK or NACK is received via the primary cell over one or more downlink channels shared by a plurality of wireless transmit/receive units.
8. The apparatus of claim 7 , wherein the receiver further:
receives a shared channel indicator via the primary cell;
wherein the shared channel indicator indicates over which of the downlink channels the receiver is allowed to receive messages.
9. The apparatus of claim 6 , wherein the ACK is received via both the primary cell and the at least one non-primary cell.
10. The apparatus of claim 6 , wherein the receiver further:
receives downlink messages via the primary cell during handover.
11. The apparatus of claim 6 , wherein the apparatus is a wireless transmit/receive unit.
12. A method for operating a Node-B, the method comprising:
receiving a data packet from a wireless transmit/receive unit (WTRU) via a primary cell and at least one non-primary cell controlled by the Node-B, wherein the data packet is received from the WTRU over an enhanced uplink (EU) channel;
combining the data packet received via the primary cell and the data packet received via the at least one non-primary cell into a combined data packet;
transmitting an acknowledgement (ACK) to the WTRU on a condition that the combined data packet is successfully decoded; and
transmitting a negative acknowledgement (NACK) to the WTRU on a condition that the combined data packet is not successfully decoded;
wherein the NACK is transmitted only via the primary cell.
13. The method of claim 12 , wherein the ACK or NACK is transmitted over one or more downlink channels shared by a plurality of WTRUs.
14. The method of claim 13 , further comprising:
transmitting a shared channel indicator via the primary cell;
wherein the shared channel indicator indicates over which of the downlink channels the WTRU is allowed to receive messages.
15. The method of claim 12 , wherein the ACK is transmitted via the primary cell and the at least one non-primary cell.
16. The method of claim 12 , wherein the data packet received via the primary cell and the data packet received via the at least one non-primary cell is combined using maximum ratio combining.
17. The method of claim 12 , further comprising:
transmitting downlink messages to the WTRU via the primary cell during handover.
18. The method of claim 12 , further comprising:
sending an ACK to a radio network controller (RNC) on the condition that the combined data packet is successfully decoded;
wherein the RNC controls the Node-B.
19. A Node-B comprising:
a receiver and a transmitter;
wherein the receiver:
receives a data packet from a wireless transmit/receive unit (WTRU) via a primary cell and at least one non-primary cell controlled by the Node-B, wherein the data packet is received over an enhanced uplink (EU) channel;
combines the data packet received via the primary cell and the data packet received via the at least one non-primary cell into a combined data packet; and
decodes the combined data packet,
and wherein the transmitter:
transmits an acknowledgement (ACK) to the WTRU on a condition that the combined data packet is successfully decoded; and
transmits, via only the primary cell, a negative acknowledgement (NACK) to the WTRU on a condition that the combined data packet is not successfully decoded.
20. The Node-B of claim 19 , wherein the ACK or NACK is transmitted via the primary cell over one or more downlink channels shared by a plurality of WTRUs.
21. The Node-B of claim 20 , wherein the transmitter further:
transmits a shared channel indicator via the primary cell, wherein the shared channel indicator indicates over which of the downlink channels of at least one non-primary cell the WTRU is allowed to receive messages.
22. The Node-B of claim 19 , wherein the ACK is transmitted via both the primary cell and the at least one non-primary cell.
23. The Node-B of claim 19 , wherein the data packet received via the primary cell and the data packet received via the at least one non-primary cell is combined using maximum ratio combining.
24. The Node-B of claim 19 , wherein the transmitter further:
transmits downlink messages to the WTRU via the primary cell during handover.
25. The Node-B of claim 19 wherein the transmitter further:
sends an ACK to a radio network controller (RNC) on the condition that the combined data packet is successfully decoded;
wherein the RNC controls the Node-B.