Hyper frame number (HFN) resynchronization of packet data convergence protocol (PDCP) protocol data units

Patent metadata

Field	Value
Publication number	US-12413344-B2
Application number	US-202218710586-A
Country	US
Kind code	B2
Filing date	Jan 20, 2022
Priority date	Jan 20, 2022
Publication date	Sep 9, 2025
Grant date	Sep 9, 2025

Abstract

Aspects of the present disclosure provide mechanisms for fast hyper frame number (HFN) resynchronization of Packet Data Convergence Protocol (PDCP) Protocol Data Units (PDUs). A wireless communication device (e.g., a PDCP entity at a wireless communication device) can calculate a current PDCP count of a current PDCP PDU of a plurality of PDCP PDUs received from a radio link control (RLC) sublayer based on a PDCP sequence number (SN) of the current PDCP PDU and an HFN of a first missing PDCP PDU after a successfully received PDCP PDU. The PDCP count may be calculated using the HFN of the first missing PDCP PDU in response to a gap between the PDCP count of the first missing PDCP PDU and the actual PDCP count of the current PDCP PDU being greater than a PDCP window size.

First claim

What is claimed is:

1. A wireless communication device configured for wireless communication, comprising:
a memory; and
a processor coupled to the memory, the processor and the memory configured to:
receive a plurality of packet data convergence protocol (PDCP) protocol data units (PDUs) from a radio link control (RLC) sublayer, each of the plurality of PDCP PDUs comprising a respective PDCP sequence number (SN); and
calculate a current PDCP count of a current PDCP PDU of the plurality of PDCP PDUs based on the respective PDCP SN of the current PDCP PDU and a hyper frame number (HFN) of a first missing PDCP PDU after a successfully received PDCP PDU of the plurality of PDCP PDUs in response to a gap between a missing PDCP count of the first missing PDCP PDU and an actual PDCP count of the current PDCP PDU being greater than a PDCP window size.

2. The wireless communication device of claim 1 , wherein each of the plurality of PDCP PDUs is further associated with a respective RLC sequence number (SN) and wherein the processor and the memory are further configured to:
determine an RLC SN gap between the respective RLC SN of the successfully received PDCP PDU and the current PDCP PDU.

3. The wireless communication device of claim 2 , wherein the processor and the memory are further configured to:
calculate the current PDCP count of the current PDCP PDU based on the HFN of the first missing PDCP PDU and a quotient of the RLC SN gap and the PDCP window size.

4. The wireless communication device of claim 3 , wherein the processor and the memory are further configured to:
perform a deciphering operation on the current PDCP PDU based on the current PDCP count in response to the current PDCP count being greater than or equal to the missing PDCP count of the first missing PDCP PDU.

5. The wireless communication device of claim 3 , wherein the processor and the memory are further configured to:
calculate a new PDCP count of the current PDCP PDU in response to the current PDCP count being less than the missing PDCP count of the first missing PDCP PDU;
perform a deciphering operation on the current PDCP PDU based on the new PDCP count in response to the new PDCP count being greater than or equal to the missing PDCP count of the first missing PDCP PDU; and
discard the current PDCP PDU in response to the new PDCP count being less than the missing PDCP count of the first missing PDCP PDU.

6. The wireless communication device of claim 1 , wherein the plurality of PDCP PDUs comprises a first subset of PDCP PDUs associated with a first radio access technology (RAT) and a second subset of PDCP PDUs associated with a second RAT, and the current PDCP PDU is within the first subset of PDCP PDUs, and wherein the processor and the memory are further configured to:
maintain a first HFN associated with the first subset of PDCP PDUs; and
maintain a second HFN associated with the second subset of PDCP PDUs.

7. The wireless communication device of claim 6 , wherein the processor and the memory are further configured to:
update a current HFN of the current PDCP PDU to the first HFN; and
calculate the current PDCP count of the current PDCP PDU based on the first HFN and the respective PDCP SN of the current PDCP PDU.

8. The wireless communication device of claim 7 , wherein the processor and the memory are further configured to:
perform a deciphering operation on the current PDCP PDU based on the current PDCP count in response to the current PDCP count being greater than or equal to the missing PDCP count of the first missing PDCP PDU.

9. The wireless communication device of claim 7 , wherein the processor and the memory are further configured to:
update the current HFN of the current PDCP PDU to the second HFN in response to the current PDCP count being less than the missing PDCP count of the first missing PDCP PDU; and
calculate a new PDCP count of the current PDCP PDU based on the second HFN and the respective PDCP SN of the current PDCP PDU.

10. The wireless communication device of claim 9 , wherein the processor and the memory are further configured to:
perform a deciphering operation on the current PDCP PDU based on the new PDCP count in response to the current PDCP count being greater than or equal to the missing PDCP count of the first missing PDCP PDU; and
discard the current PDCP PDU in response to the new PDCP count being less than the missing PDCP count of the first missing PDCP PDU.

11. The wireless communication device of claim 10 , wherein the processor and the memory are further configured to:
update the first HFN with the current HFN of the current PDCP PDU in response to the current PDCP PDU not being discarded.

12. The wireless communication device of claim 6 , wherein the processor and the memory are further configured to:
calculate an initial PDCP count of the current PDCP PDU;
perform a deciphering operation on the current PDCP PDU based on the initial PDCP count in response to the initial PDCP count being greater than or equal to the missing PDCP count of the first missing PDCP PDU;
discard the current PDCP PDU in response to failure of the deciphering operation; and
calculate the current PDCP count of the current PDCP PDU in response to the initial PDCP count of the current PDCP PDU being less than the missing PDCP count of the first missing PDCP PDU.

13. A method for wireless communication at a wireless communication device, the method comprising:
receiving a plurality of packet data convergence protocol (PDCP) protocol data units (PDUs) from a radio link control (RLC) sublayer, each of the plurality of PDCP PDUs comprising a respective PDCP sequence number (SN); and
calculating a current PDCP count of a current PDCP PDU of the plurality of PDCP PDUs based on the respective PDCP SN of the current PDCP PDU and a hyper frame number (HFN) of a first missing PDCP PDU after a successfully received PDCP PDU of the plurality of PDCP PDUs in response to a gap between a missing PDCP count of the first missing PDCP PDU and an actual PDCP count of the current PDCP PDU being greater than a PDCP window size.

14. The method of claim 13 , wherein each of the plurality of PDCP PDUs is further associated with a respective RLC sequence number (SN) and further comprising:
determining an RLC SN gap between the respective RLC SN of the successfully received PDCP PDU and the current PDCP PDU.

15. The method of claim 14 , wherein the calculating the current PDCP count of the current PDCP PDU further comprises:
calculating the current PDCP count of the current PDCP PDU based on the HEN of the first missing PDCP PDU and a quotient of the RLC SN gap and the PDCP window size.

16. The method of claim 15 , further comprising:
performing a deciphering operation on the current PDCP PDU based on the current PDCP count in response to the current PDCP count being greater than or equal to the missing PDCP count of the first missing PDCP PDU.

17. The method of claim 15 , further comprising:
calculating a new PDCP count of the current PDCP PDU in response to the current PDCP count being less than the missing PDCP count of the first missing PDCP PDU;
performing a deciphering operation on the current PDCP PDU based on the new PDCP count in response to the new PDCP count being greater than or equal to the missing PDCP count of the first missing PDCP PDU; and
discarding the current PDCP PDU in response to the new PDCP count being less than the missing PDCP count of the first missing PDCP PDU.

18. The method of claim 13 , wherein the plurality of PDCP PD

Assignees

• Qualcomm Inc

Inventors

• Sun Lei
• Wu Peng
• Balasubramanian Arun Prasanth
• Tan Jason
• Li Yuyi
• Rao Vaishakh
• Palakodety Sivaram Srivenkata
• Dalmiya Vishal
• Iberico Torres Mariano
• Maheshwari Shailesh
• Chin Tom

Classifications

• H04L47/34 Primary

  ensuring sequence integrity, e.g. using sequence numbers · CPC title

• H04L47/32

  by discarding or delaying data units, e.g. packets or frames · CPC title

• H04L1/1854 Primary

  Scheduling and prioritising arrangements · CPC title

• H04L1/1841

  Resequencing · CPC title

• H04L69/324

  in the data link layer [OSI layer 2], e.g. HDLC · CPC title