# US 11,452,016 B2 · Dual-protocol for mobility enhancement > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,452,016 B2 - Document ID: US11452016B2 - Status: Granted - Kind: B2 - Application number: 16/989,992 - Filed: 2020-08-11 - Published: 2020-11-26 - Granted: 2022-09-20 - Earliest claimed: 2019-06-26 - Assignees: MediaTek Singapore Pte. Ltd. - Applicants: MediaTek Singapore Pte. Ltd. - Inventors: Yuanyuan Zhang; Chun-Fan Tsai - Web page: https://patentgrep.com/patent/US11452016B2 ## CPC - H04W 76/34: Selective release of ongoing connections - H04L 41/0816: the condition being an adaptation, e.g. in response to network events - H04L 69/18: Multiprotocol handlers, e.g. single devices capable of handling multiple protocols - H04W 12/0433: Key management protocols - H04W 28/0252: {per individual bearer or channel (dynamic wireless traffic scheduling H04W72/12)} - H04W 36/026: {Multicasting of data during hand-off} - H04W 36/305: {Handover due to radio link failure (control signalling for hand-off failure H04W36/0079)} - H04W 74/0833: Random access procedures, e.g. with 4-step access - H04W 76/10: Connection setup - H04W 36/0069: {in case of dual connectivity, e.g. decoupled uplink/downlink} - H04W 36/324: {by mobility data, e.g. speed data} - H04W 80/02: Data link layer protocols - H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72) - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) ## Abstract Apparatus and methods are provided to reduce mobility interruption time through dual-protocol stacks for mobility enhancement. In novel aspect, the UE configures a target protocol stack for a target gNB upon receiving a reconfiguration message from a source gNB, performs random access procedure and establishes RRC connection with the target gNB through the target protocol stack while simultaneously maintaining data transmission and reception with the source gNB, and releases the source RRC connection with the source gNB and performs data transmission and reception with the target gNB upon detecting one or more predefined release triggering event. In one embodiment, the target protocol stack includes a PHY layer, a MAC layer, and RLC layer, a PDCP and optionally a SDAP. In one embodiment, the UE enables a PDCP reordering, wherein the PDCP reordering is performed on PDCP packet data units received from the source and the target protocol stacks. ## Claims ### Claim 1 A method comprising: receiving a reconfiguration message from a source gNB by a user equipment (UE) in a wireless network, wherein the UE performs data transmission and reception with the source gNB through a source protocol stack; configuring a new target protocol stack for a target gNB based on the received reconfiguration message, wherein the new target protocol is concurrent with the source protocol stack, and wherein the target protocol stack is configured with an existing source data radio bearer (DRB) configuration for the target gNB; performing random access (RA) procedure and establishing radio resource control (RRC) connection with the target gNB through the target protocol stack while simultaneously maintaining data transmission and reception with the source gNB through the source protocol stack; reordering PDCP packet data units (PDUs) received from the source protocol stack and the target protocol stack by a UE PDCP entity; and releasing an RRC connection with the source gNB and performing data transmission and reception with the target gNB upon detecting one or more predefined release triggering event. ### Claim 2 (depends on 1) The method of claim 1, wherein the target protocol stack includes a PHY layer, a MAC layer, a radio link control (RLC) layer. ### Claim 3 (depends on 1) The method of claim 1, wherein the target protocol stack further includes at least one upper layer comprising: a Packet Data Convergence Protocol (PDCP) layer and a Service Data Adaptation Protocol (SDAP) layer. ### Claim 4 (depends on 1) The method of claim 1, wherein the reconfiguration message indicates to maintain the RRC connection with the source gNB and the source protocol stack. ### Claim 5 (depends on 1) The method of claim 1, further comprising: sending a reconfiguration response message to the target gNB upon establishing the RRC connection with the target gNB; and performing data transmission and reception simultaneously with the source gNB and the target gNB. ### Claim 6 (depends on 1) The method of claim 1, further comprising: applying a first security key for the source protocol stack and applying a second security key for the target protocol stack. ### Claim 7 (depends on 1) The method of claim 1, wherein the one or more predefined release triggering events comprising: receiving a RRC connection release message from the source gNB, receiving a RRC connection release message from the target gNB, receiving a RRC connection release message in response to a RRC Connection Release Request sent by the UE upon detecting a radio link failure (RLF) of the source gNB, and receiving a RRC connection release message in response to a RRC Connection Release Request sent by the UE indicating a RLF to the target gNB. ### Claim 8 (depends on 1) The method of claim 1, further comprising: triggering a Packet Data Convergence Protocol (PDCP) status report upon releasing the source RRC connection. ### Claim 9 A user equipment (UE) comprising: a radio frequency (RF) transceiver that transmits and receives radio signals in a wireless network; a source protocol stack and a target protocol stack that communicate with the RF transceiver; a memory; and a processor coupled to the memory, the source protocol stack and the source protocol stack, the processor configured to receive a reconfiguration message from a source gNB, wherein the UE performs data transmission and reception with the source gNB through the source protocol stack, configure a new target protocol stack for a target gNB based on the received reconfiguration message, wherein the new target protocol is concurrent with the source protocol stack, and wherein the target protocol stack is configured with an existing source data radio bearer (DRB) configuration for the target gNB, perform random access (RA) procedure and establishes radio resource control (RRC) connection with the target gNB through the target protocol stack while simultaneously maintaining data transmission and reception with the source gNB through the source protocol stack, reorder PDCP packet data units (PDUs) received from the source protocol stack and the target protocol stack by a UE PDCP entity, and release an RRC connection with the source gNB and performing data transmission and reception with the target gNB upon detecting one or more predefined release triggering event. ### Claim 10 (depends on 9) The UE of claim 9, wherein the target protocol stack includes a PHY layer, a MAC layer, a radio link control (RLC) layer. ### Claim 11 (depends on 9) The UE of claim 9, wherein the target protocol stack further includes at least one upper layer comprising: a Packet Data Convergence Protocol (PDCP) layer and a Service Data Adaptation Protocol (SDAP) layer. ### Claim 12 (depends on 9) The UE of claim 9, wherein the reconfiguration message indicates to maintain the RRC connection with the source gNB and the source protocol stack. ### Claim 13 (depends on 9) The UE of claim 9, wherein the processor is further configured to send a reconfiguration response message to the target gNB upon establishing the RRC connection with the target gNB, and perform data transmission and reception simultaneously with the source gNB and the target gNB. ### Claim 14 (depends on 9) The UE of claim 9, wherein the processor is further configured to apply a first security key for the source protocol stack and applying a second security key for the target protocol stack. ### Claim 15 (depends on 9) The UE of claim 9, wherein the one or more predefined release triggering events comprising: receiving a RRC connection release message from the source gNB, receiving a RRC connection release message from the target gNB, receiving a RRC connection release message in response to a RRC Connection Release Request sent by the UE upon detecting a radio link failure (RLF) of the source gNB, and receiving a RRC connection release message in response to a RRC Connection Release Request sent by the UE indicating a RLF to the target gNB. ### Claim 16 (depends on 9) The UE of claim 9, wherein the processor is further configured to trigger a Packet Data Convergence Protocol (PDCP) status report upon releasing the source RRC connection.