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 for operating hybrid automatic repeat request (H-ARQ) in a wireless communications network, the method comprising:
receiving a data packet from a wireless transmit/receive unit (WTRU) via an enhanced uplink (EU) channel;
decoding the data packet;
sending an acknowledgement (ACK) to a radio network controller (RNC) on a condition that the data packet is successfully decoded;
receiving an ACK/non-acknowledgement (NACK) decision from the RNC, an ACK decision being made on a condition that there is at least one ACK from Node-Bs and a NACK decision being made on a condition that there is no ACK from the Node-Bs; and
forwarding the ACK/NACK decision to the WTRU.
2. The method of claim 1 further comprising:
flushing a soft buffer on a condition that an ACK decision is received from the RNC.
3. The method of claim 1 wherein one of the Node-Bs is designated as a primary Node-B and only the primary Node-B performs soft combining.
4. The method of claim 3 wherein non-primary Node-Bs perform only automatic repeat request (ARQ).
5. The method of claim 3 wherein non-primary Node-Bs transmit only correctly decoded data packets to the RNC.
6. The method of claim 1 wherein one of the Node-Bs is designated as a primary Node-B and both the primary Node-B and non-primary Node-Bs perform soft combining and each Node-B transmits a data packet along with identification of transmission and H-ARQ process and WTRU identity.
7. A method for operating hybrid automatic repeat request (H-ARQ) in a wireless communications network, the method comprising:
receiving a data packet from a wireless transmit/receive unit (WTRU) via an enhanced uplink (EU) channel;
decoding the data packet;
sending an acknowledgement (ACK) both to the WTRU and a radio network controller (RNC) on a condition that the data packet is successfully decoded; and
receiving an ACK/non-acknowledgement (NACK) decision from the RNC, an ACK decision being made on a condition that there is at least one ACK from Node-Bs and a NACK decision being made on a condition that there is no ACK from the Node-Bs.
8. The method of claim 7 further comprising:
flushing a soft buffer when an ACK decision is received from the RNC.
9. A Node-B for operating hybrid automatic repeat request (H-ARQ) in a wireless communications network, the Node-B comprising:
a receiver configured to receive a data packet from a wireless transmit/receive unit (WTRU) via an enhanced uplink (EU) channel;
a decoder configured to decode the data packet; and
an H-ARQ entity configured to send a positive acknowledgement (ACK) to a radio network controller (RNC) on a condition that the data packet is successfully decoded and receive an ACK/negative acknowledgement (NACK) decision from the RNC and forward the ACK/NACK decision to the WTRU, wherein an ACK decision being made on a condition that there is at least one ACK from Node-Bs and a NACK decision being made on a condition that there is no ACK from the Node-Bs.
10. The Node-B of claim 9 further comprising:
a soft buffer configured to store the data packet, the soft buffer being flushed on a condition that an ACK decision is received from the RNC.
11. The Node-B of claim 9 wherein one of the Node-Bs is designated as a primary Node-B and only the primary Node-B performs soft combining.
12. The Node-B of claim 11 wherein the non-primary Node-Bs perform only automatic repeat request (ARQ).
13. The Node-B of claim 12 wherein the non-primary Node-Bs transmit only correctly decoded data packets to the RNC.
14. A Node-B for operating hybrid automatic repeat request (H-ARQ) in a wireless communications network, the Node-B comprising:
a receiver configured to receive a data packet from a wireless transmit/receive unit (WTRU) via an enhanced uplink (EU) channel;
a decoder configured to decode the data packet; and
an H-ARQ entity configured to send an acknowledgement (ACK) both to the WTRU and a radio network controller (RNC) on a condition that the data packet is successfully decoded and receive an ACK/negative acknowledgement (NACK) decision from the RNC, an ACK decision being made on a condition that there is at least one ACK from Node-Bs and a NACK decision being made on a condition that there is no ACK from the Node-Bs.
15. The Node-B of claim 14 wherein one of the Node-Bs is designated as a primary Node-B and both the primary Node-B and the non-primary Node-Bs perform soft combining and each Node-B transmits a data packet along with identification of transmission and H-ARQ process and WTRU identity.
16. A Node-B for operating hybrid automatic repeat request (H-ARQ) in a wireless communications network, the Node-B comprising:
a receiver configured to receive a data packet from a wireless transmit/receive unit (WTRU) via an enhanced uplink (EU) channel;
a decoder configured to decode the data packet; and
an H-ARQ entity configured to send an acknowledgement (ACK) to a Node-B coordinator on a condition that the data packet is successfully decoded, receive an ACK/negative acknowledgement (NACK) decision from the Node-B coordinator, and forward the ACK/NACK decision to the WTRU, wherein an ACK decision is made on a condition that there is at least one ACK from Node-Bs and a NACK decision is made on a condition that there is no ACK from the Node-Bs.
17. A method for operating hybrid automatic repeat request (H-ARQ), implemented in a Node-B, in a wireless communications network, the method comprising:
receiving a data packet via each of at least two cells controlled by the Node B, wherein each cell received its respective data packet from a wireless transmit/receive unit (WTRU) via an enhanced uplink (EU) channel;
combining the each received data packet into a combined data packet;
decoding the combined data packet;
sending an acknowledgement (ACK) to the WTRU on a condition that the combined data packet is successfully decoded and a non-acknowledgement (NACK) on a condition that the combined data packet is not successfully decoded, wherein one cell is designated as a primary cell, and other cells are designated as a non-primary cell; and
transmitting downlink messages to the WTRU using the primary cell during softer handover.
18. The method of claim 17 wherein the ACK/NACK is signaled via a downlink channel shared by a plurality of WTRUs.
19. The method of claim 18 further comprising receiving a shared channel indicator indicating channels in which the WTRU is allowed to receive messages from the non-primary cells.
20. A Node-B for operating hybrid automatic repeat request (H-ARQ), in a wireless communications network, the Node-B comprising:
a H-ARQ process configured to perform H-ARQ operation for a wireless transmit/receive unit (WTRU);
a receiver configured to receive a data packet via each of at least two cells controlled by the Node-B wherein each cell received its respective data packet from the WTRU via an enhanced uplink (EU) channel;
a decoder configured to combine the each data packet into a combined data packet and decode the combined data packet,
wherein the H-ARQ process sends an acknowledgement (ACK) to the WTRU on a condition that the combined data packet is successfully decoded and sends a non-acknowledgement (NACK) to the WTRU on a condition that the combined data packet is not successfully decoded, wherein one cell is designated as a primary cell and other cells are designated as a non-primary cell; and
a transmitter configured to transmit downlink messages to the WTRU using the primary cell during softer handover.
21. The Node-B of claim 20 wherein the ACK/NACK is signaled via a downlink channel shared by a plurality of WTRUs.
22. The Node-B of claim 21 wherein a shared channel indicator is sent via the primary cell indicating channels in which the WTRU is allowed to receive messages from the non-primary cells.