Wireless communication method and apparatus for coordinating Node-B's and supporting enhanced uplink transmissions during handover
A wireless communication method and apparatus for coordinating Node-Bs during handover for enhanced uplink (EU) transmission. In one embodiment, a radio network controller (RNC) initiates an inter-Node-B soft handover. A wireless transmit/receive unit (WTRU) establishes communication connections with a plurality of Node-Bs. A particular one of the Node-Bs is designated as being a primary Node-B, and each of other Node-Bs are designated as being a non-primary Node-B. The RNC informs all of the Node-Bs that the particular Node-B is a primary Node-B. The primary Node-B schedules EU transmission and performs ACK/NACK during soft handover. In another embodiment, the RNC initiates a hard handover for a WTRU connected to a source Node-B. The RNC sends an activation timer to the source Node-B to set the time for handover. As many previously negatively acknowledged (NACKed) data packets as possible are prioritized for retransmission in the source Node-B before the activation timer expires.
1. In a wireless multi-cell communication system including a radio network controller (RNC), a plurality of Node-Bs, and at least one wireless transmit/receive unit (WTRU), a method of coordinating Node-Bs during handover, the method comprising:
(a) the RNC initiating an inter-Node-B soft handover;
(b) the WTRU establishing communication connections with at least two of the Node-Bs;
(c) designating particular one of the Node-Bs as a primary Node-B, wherein the primary Node-B is configured to store negative acknowledgement (NACK) data packets and use soft combining to process transmissions, and the primary Node-B is also configured to transmit at least one of a positive acknowledgement (ACK) and a NACK to the WTRU, and transmit a correctly decoded data packet to the RNC;
(d) designating the other one(s) of the Node-Bs as a non-primary Node-B, wherein the non-primary Node-B does not store NACK data packets and does not use soft combining to process transmissions, and the non-primary Node-B is not configured to transmit at least one of an ACK and a NACK to the WTRU; and
(e) the RNC informing the Node-Bs that the particular Node-B is a primary Node-B.
2. The method of claim 1 further comprising:
(f) the primary Node-B controlling an uplink (UL) transmission originating from the WTRU during soft handover.
3. The method of claim 2 wherein the primary Node-B schedules the UL transmission.
4. The method of claim 3 wherein the primary Node-B receives physical measurement information regarding the non-primary Node-B(s), and considers the information when scheduling the UL transmission.
5. The method of claim 4 wherein the primary Node-B transmits scheduling information to the WTRU and the non-primary Node-B(s).
6. The method of claim 1 further comprising:
(f) the primary Node-B controlling transmissions during soft handover by performing enhanced uplink (EU) scheduling and hybrid automatic repeat request (H-ARQ) operations.
7. The method of claim 6 wherein a positive acknowledgement (ACK) or negative acknowledgement (NACK) is transmitted either synchronously or non-synchronously from the primary Node-B to the WTRU.
8. The method of claim 6 wherein the non-primary Node-B transmits correctly decoded data blocks to the RNC.
9. The method of claim 1 wherein the primary Node-B is selected by the WTRU based on a downlink quality received from the Node-Bs.
10. The method of claim 9 wherein the downlink quality is downlink pilot power.
11. The method of claim 1 wherein the primary Node-B is selected by the RNC based on uplink performance statistics at each Node-B.
12. The method of claim 11 wherein the RNC selects the primary Node-B further based on a report generated by the WTRU regarding a downlink quality from the Node-Bs.
13. The method of claim 11 wherein the RNC selects the primary Node-B further based on a report generated by the WTRU regarding a combination of uplink and downlink quality.
14. A wireless communication system for coordinating Node-Bs during handover for enhanced uplink communication, the system comprising:
(a) a wireless transmit/receive unit (WTRU); and
(b) a plurality of Node-Bs, each Node-B comprising an entity for enhanced uplink (EU) functionalities and processing a transmission from the WTRU independently, wherein a particular one of the Node-Bs is designated as being a primary Node-B which is configured to store negative acknowledgement (NACK) data packets and use soft combining to process transmissions, and the primary Node-B is also configured to transmit at least one of a positive acknowledgement (ACK) and a NACK to the WTRU, and transmit a correctly decoded data packet to the RNC, the other Node-B(s) being designated as a non-primary Node-B which does not store NACK data packets and does not use soft combining to process transmissions, and the non-primary Node-B is not configured to transmit at least one of an ACK and a NACK to the WTRU, and the primary Node-B controlling EU transmissions from the WTRU during handover.
15. The system of claim 14 wherein the primary Node-B control an uplink (UL) transmission originating from the WTRU during soft handover.
16. The system of claim 15 wherein the primary Node-B schedules the UL transmission.
17. The system of claim 16 wherein the primary Node-B receives physical measurement information regarding the non-primary Node-B(s), and considers the physical measurement information when scheduling the UL transmission.
18. The system of claim 16 wherein the primary Node-B transmits scheduling information to the WTRU and the non-primary Node-B(s).
19. The system of claim 14 wherein a positive acknowledgement (ACK) or negative acknowledgement (NACK) is transmitted either synchronously or non-synchronously from the primary Node-B to the WTRU.
20. In a wireless multi-cell communication system including a radio network controller (RNC), a plurality of Node-Bs, and at least one wireless transmit/receive unit (WTRU), an integrated circuit (IC) used to coordinate Node-Bs during handover, the IC comprising:
(a) means for designating a particular one of the Node-Bs as a primary Node-B, wherein the primary Node-B is configured to store negative acknowledgement (NACK) data packets and use soft combining to process transmissions, and the primary Node-B is also configured to transmit at least one of a positive acknowledgement (ACK) and a NACK to the WTRU, and transmit a correctly decoded data packet to the RNC;
(b) means for designating one or more other ones of the Node-Bs as a non-primary Node-B, wherein the non-primary Node-B does not store NACK data packets and does not use soft combining to process transmissions, and the non-primary Node-B is not configured to transmit at least one of an ACK and a NACK to the WTRU; and
(c) means for informing the Node-Bs that the particular Node-B has been designated as a primary Node-B.
21. The IC of claim 20 wherein the IC is integrated with the RNC.
22. In a wireless multi-cell communication system including a plurality of Node-Bs, a radio network controller (RNC) comprising:
(a) means for controlling the plurality of Node-Bs;
(b) means for initiating an inter-node-B soft handover;
(c) means for designating a particular one of the Node-Bs as a primary Node-B, wherein the primary Node-B is configured to store negative acknowledgement (NACK) data packets and use soft combining to process transmissions, and the primary Node-B is also configured to transmit at least one of a positive acknowledgement (ACK) and a NACK to the WTRU, and transmit a correctly decoded data packet to the RNC;
(d) means for designating one or more other ones of the Node-Bs as a non-primary Node-B, wherein the non-primary Node-B does not store NACK data packets and does not use soft combining to process transmissions, and the non-primary Node-B is not configured to transmit at least one of an ACK and a NACK to the WTRU; and
(e) means for informing the Node-Bs that the particular Node-B has been designated as a primary Node-B.
23. In a wireless multi-cell communication system including a plurality of Node-Bs, an integrated circuit (IC) comprising:
(a) means for controlling the plurality of Node-Bs;
(b) means for initiating an inter-Node-B soft handover;
(c) means for designating a particular one of the Node-Bs as a primary Node-B, wherein the primary Node-B is configured to store negative acknowledgement (NACK) data packets and use soft combining to process transmissions, and the primary Node-B is also configured to transmit at least one of a positive acknowledgement (ACK) and a NACK to the WTRU, and transmit a correctly decoded data packet to the RNC;
(d) means for designating one or more other ones of the Node-Bs as a non-primary Node-B, wherein the non-primary Node-B does not store NACK data packets and does not use soft combining to process transmissions, and the non-primary Node-B is not configured to transmit at least one of an ACK and a NACK to the WTRU; and
(e) means for informing the Node-Bs that the particular Node-B has been designated as a primary Node-B.
24. The IC of claim 23 wherein the IC is integrated with a radio network controller (RNC) that controls the plurality of Node-Bs.