System and method for multi-point HSDPA communication utilizing a multi-link PDCP sublayer

Patent metadata

Field	Value
Publication number	US-8989004-B2
Application number	US-201113291037-A
Country	US
Kind code	B2
Filing date	Nov 7, 2011
Priority date	Nov 8, 2010
Publication date	Mar 24, 2015
Grant date	Mar 24, 2015

Abstract

A method and apparatus for wireless communication may provide a multi-link PDCP sublayer in a radio network controller capable of allocating PDCP PDUs among a plurality of RLC entities for use in a multi-point HSDPA network. Some aspects of the disclosure address issues relating to out-of-order delivery of the PDCP PDUs to a UE, such as unnecessary retransmissions. That is, the disclosed multi-link PDCP may be capable of distinguishing between sequence number gaps that are caused by physical layer transmission failures and those caused merely by skew.

First claim

The invention claimed is:

1. A method of wireless communication operable at a user equipment, comprising:
receiving at least a portion of a multi-link packet data convergence protocol (PDCP) flow from each of a plurality of base stations;
reordering PDCP protocol data units (PDUs) corresponding to the multi-link PDCP flow according to a PDCP sequence number in each of the PDCP PDUs to form a queue of received PDCP PDUs;
determining that a gap in the PDCP sequence numbers exists in the queue of received PDCP PDUs;
starting a skew timer based on determining that the gap exists;
passing, to one or more upper layers from the queue of received PDCP PDUs, PDCP PDUs having contiguous PDCP sequence numbers lower than a PDCP sequence number corresponding to the gap, when the skew timer corresponding to the gap expires; and
flushing, from the queue of received PDCP PDUs, PDCP PDUs having PDCP sequence numbers higher than the PDCP sequence number corresponding to the gap, without passing the PDCP PDUS having the PDCP sequence numbers higher than the PDCP sequence number corresponding to the gap to the one or more upper layers.

2. The method of claim 1 , further comprising:
receiving at least one PDCP PDU having a sequence number corresponding to the gap, to fill the gap; and
passing PDCP PDUs having contiguous PDCP sequence numbers up to and including the gap in the PDCP sequence numbers when the gap is filled.

3. The method of claim 1 , wherein the receiving of the at least a portion of the multi-link PDCP flow from each of the plurality of base stations comprises:
receiving a first downlink stream from a first base station; and
receiving a second downlink stream from a second base station, in substantially the same carrier frequency as the first downlink stream.

4. The method of claim 3 , further comprising:
determining that a measurement of the second downlink stream has fallen below a threshold;
transmitting a request corresponding to the measurement; and
switching off a multi-point high speed downlink packet access (HSDPA) mode such that the second downlink stream is not received from the second base station.

5. The method of claim 4 , wherein the request corresponding to the measurement comprises an indication that a cell corresponding to the second base station is suitable for removal from an active set.

6. The method of claim 4 , further comprising:
determining that a gap in radio link control (RLC) sequence numbers corresponding to the second downlink stream exists;
requesting a retransmission of at least one packet corresponding to the gap in the RLC sequence numbers; and
receiving a retransmission of the at least one packet corresponding to the gap over the first downlink stream from the first base station.

7. The method of claim 3 , wherein the first downlink stream corresponds to a first logical channel between the user equipment and a radio network controller, and wherein the second downlink stream corresponds to a second logical channel between the user equipment and the radio network controller.

8. The method of claim 3 , wherein the first base station is configured to provide a primary serving cell associated with the user equipment and the second base station is configured to provide a secondary serving cell associated with the user equipment.

9. The method of claim 8 , wherein the primary serving cell facilitates a first logical channel between the user equipment and a radio network controller, and wherein the secondary serving cell facilitates a second logical channel between the user equipment and a radio network controller.

10. A user equipment configured for wireless communication, comprising:
means for receiving at least a portion of a multi-link packet data convergence protocol (PDCP) flow from each of a plurality of base stations;
means for reordering PDCP protocol data units (PDUs) corresponding to the multi-link PDCP flow according to a PDCP sequence number in each of the PDCP PDUs to form a queue of received PDCP PDUs;
means for determining that a gap in the PDCP sequence numbers exists in the queue of received PDCP PDUs;
means for starting a skew timer based on determining that the gap exists;
means for passing, to one or more upper layers from the queue of received PDCP PDUs, PDCP PDUs having contiguous PDCP sequence numbers lower than a PDCP sequence number corresponding to the gap, when the skew timer corresponding to the gap expires; and
means for flushing, from the queue of received PDCP PDUs, PDCP PDUs having PDCP sequence numbers higher than the PDCP sequence number corresponding to the gap, without passing the PDCP PDUS having the PDCP sequence numbers higher than the PDCP sequence number corresponding to the gap to the one or more upper layers.

11. A non-transitory computer-readable medium storing computer-executable code, comprising:
code for causing a computer to receive at least a portion of a multi-link packet data convergence protocol (PDCP) flow from each of a plurality of base stations;
code for causing the computer to reorder PDCP protocol data units (PDUs) corresponding to the multi-link PDCP flow according to a PDCP sequence number in each of the PDCP PDUs to form a queue of received PDCP PDUs;
code for causing the computer to determine that a gap in the PDCP sequence numbers exists in the queue of received PDCP PDUs;
code for causing the computer to start a skew timer based on determining that the gap exists; and
code for causing the computer to pass, to one or more upper layers from the queue of received PDCP PDUs, PDCP PDUs having contiguous PDCP sequence numbers lower than a PDCP sequence number corresponding to the gap, when the skew timer corresponding to the gap expires; and
code for causing the computer to flush, from the queue of received PDCP PDUs, PDCP PDUs having PDCP sequence numbers hi her than the PDCP sequence number corresponding to the gap, without passing the PDCP PDUS having the PDCP sequence numbers higher than the PDCP sequence number corresponding to the gap to the one or more upper layers.

12. A user equipment configured for wireless communication, comprising:
a receiver for receiving downlink transmissions from at least one base station;
a transmitter for transmitting uplink transmissions to the at least one base station;
at least one processor for controlling the receiver and the transmitter; and
a memory coupled to the at least one processor,
wherein the at least one processor is configured to:
receive at least a portion of a multi-link packet data convergence protocol (PDCP) flow from each of a plurality of base stations;
reorder PDCP protocol data units (PDUs) corresponding to the multi-link PDCP flow according to a PDCP sequence number in each of the PDCP PDUs to form a queue of received PDCP PDUs;
determine that a gap in the PDCP sequence numbers exists in the queue of received PDCP PDUs;
start a skew timer based on determining that the gap exists;
pass, to one or more upper layers from the queue of received PDCP PDUs, PDCP PDUs having contiguous PDCP sequence numbers lower than a PDCP sequence number corresponding to the gap, when the skew timer corresponding to the gap expires; and
flush, from the queue of received PDCP PDUs, PDCP PDUs having PDCP sequence numbers higher than the PDCP sequence number corresponding to the gap, without passing the PDCP PDUS having the PDCP sequence numbers higher than the PDCP sequence number corresponding to the gap to the one or more upper layers.

13. The user equipment of claim 12 , wherein the at least one processor is further configured to:
receive at least one PDCP PDU having a sequence number cor

Assignees

• Zhang Danlu
• Kapoor Rohit
• Mohanty Bibhu Prasad
• Ge Weiyan
• Hou Jilei
• Qualcomm Inc

Inventors

• Zhang Danlu
• Kapoor Rohit
• Mohanty Bibhu Prasad
• Ge Weiyan
• Hou Jilei

Classifications

• H04L1/1867

  Arrangements specially adapted for the transmitter end · CPC title

• H04W28/10 Primary

  Flow control {between communication endpoints} · CPC title

• H04W88/06

  adapted for operation in multiple networks {or having at least two operational modes}, e.g. multi-mode terminals · CPC title

• H04L2001/0092

  Error control systems characterised by the topology of the transmission link · CPC title

• H04W24/10

  Scheduling measurement reports {; Arrangements for measurement reports} · CPC title