# US 2020/0288357 A1 · Method and system for supporting fast recovery of user equipment > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2020/0288357 A1 - Document ID: US20200288357A1 - Status: Published application - Kind: A1 - Application number: 16/882,306 - Filed: 2020-05-22 - Published: 2020-09-10 - Earliest claimed: 2012-12-24 - Assignees: Samsung Electronics Co., Ltd. - Applicants: Samsung Electronics Co., Ltd. - Inventors: Lixiang XU; Hong Wang; Huarui Liang - Web page: https://patentgrep.com/patent/US20200288357A1 ## CPC - H04W 36/0033: {with transfer of context information} - H04W 36/0079: {in case of hand-off failure or rejection} - H04W 36/08: Reselecting an access point - H04W 76/19: Connection re-establishment - H04W 84/045: {using private Base Stations, e.g. femto Base Stations, home Node B} - H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72) ## Abstract A method for supporting fast recovery of a User Equipment (UE) includes performing, by a serving base station, UE context synchronization for one or more other base stations in a related small cell cluster when a UE accesses the serving base station, performing, by a base station that the UE performs a radio resource control (RRC) connection re-establishment, the RRC connection re-establishment for the UE according to UE context saved in a synchronization process. The present also discloses another method and system for supporting UE fast recovery. By applying the technical solution disclosed by the present disclosure, when the UE moves in a small cell scenario, the UE can be recovered quickly in the case of a failure, so as to avoid the UE returns to an idle mode, avoid data loss, guarantee business continuity, and improve UE experience. ## Claims ### Claim 1 A method performed by a base station in a wireless communication system, the method comprising: receiving a first radio resource control (RRC) message from a user equipment (UE); transmitting a UE context request message associated with the UE to a last serving base station; receiving a UE context response message associated with the UE from the last serving base station; transmitting a path switch request message to a mobility management node associated with the UE based on the UE context response message; receiving a path switch response message from the mobility management node associated with the UE; and transmitting information associated with releasing a context of the UE to the last serving base station based on the path switch response message, wherein the UE context request message includes a base station UE application protocol (AP) identifier allocated by the base station and an identifier of the UE allocated by the last serving base station for identifying a context of the UE, and wherein the UE context response message includes the base station UE AP identifier allocated by the base station and a base station UE AP identifier allocated by the last serving base station. ### Claim 2 (depends on 1) The method of claim 1, wherein the UE context request message includes at least one of a cell identifier of the base station, or a short Media Access Control (MAC) identifier (shortMACI). ### Claim 3 (depends on 2) The method of claim 2, wherein a security check is performed by the last serving base station based on the shortMACI included in the UE context request message, and wherein a resource allocated for the UE and the context of the UE is released based on the information associated with releasing the context of the UE. ### Claim 4 (depends on 1) The method of claim 1, wherein the UE context response message includes at least one of information associated with the mobility management node, security information of the UE, capability information of the UE, or a mobility restriction list. ### Claim 5 A base station in a wireless communication system, the base station comprising: a transceiver; and a controller configured to: receive, via the transceiver from a user equipment (UE), a first radio resource control (RRC) message, transmit, to a last serving base station via the transceiver, a UE context request message associated with the UE, receive, from the last serving base station via the transceiver, a UE context response message associated with the UE, transmit, to a mobility management node associated with the UE via the transceiver, a path switch request message based on the UE context response message, receive, from the mobility management node associated with the UE via the transceiver, a path switch response message, and transmit, to the last serving base station via the transceiver, information associated with releasing a context of the UE based on the path switch response message, wherein the UE context request message includes a base station UE application protocol (AP) identifier allocated by the base station and an identifier of the UE allocated by the last serving base station for identifying a context of the UE, and wherein the UE context response message includes the base station UE AP identifier allocated by the base station and a base station UE AP identifier allocated by the last serving base station. ### Claim 6 (depends on 5) The base station of claim 5, wherein the UE context request message includes at least one of a cell identifier of the base station, or a short Media Access Control (MAC) identifier (shortMACI). ### Claim 7 (depends on 6) The base station of claim 6, wherein a security check is performed by the last serving base station based on the shortMACI included in the UE context request message, and wherein a resource allocated for the UE and the context of the UE is released based on the information associated with releasing the context of the UE. ### Claim 8 (depends on 5) The base station of claim 5, wherein the UE context response message includes at least one of information associated with the mobility management node, security information of the UE, capability information of the UE, or a mobility restriction list. ### Claim 9 A method performed by a last serving base station in a wireless communication system, the method comprising: receiving a user equipment (UE) context request message associated with a UE from a base station, wherein the UE context request message includes a base station UE application protocol (AP) identifier allocated by the base station and an identifier of the UE allocated by the last serving base station for identifying a context of the UE; identifying the context of the UE based on the identifier of the UE; performing a security check based on the UE context request message associated with the UE; transmitting a UE context response message associated with the UE to the base station based on a success of the security check; and receiving information associated with releasing a context of the UE from the base station, wherein the UE context response message includes the base station UE AP identifier allocated by the base station and a base station UE AP identifier allocated by the last serving base station. ### Claim 10 (depends on 9) The method of claim 9, wherein the UE context request message includes at least one of a cell identifier of the base station, or a short Media Access Control (MAC) identifier (shortMACI). ### Claim 11 (depends on 10) The method of claim 10, wherein a path switch request message is transmitted from the base station to a mobility management node associated with the UE based on the UE context response message, wherein a path switch response message is received at the base station from the mobility management node associated with the UE, wherein the information associated with releasing the context of the UE is transmitted from the base station based on the path switch response message, wherein the security check is performed by the last serving base station based on the shortMACI included in the UE context request message, and wherein a resource allocated for the UE and the context of the UE is released based on the information associated with releasing context of the UE. ### Claim 12 (depends on 9) The method of claim 9, wherein the UE context response message includes at least one of information associated with a mobility management node, security information of the UE, capability information of the UE, or a mobility restriction list. ### Claim 13 A last serving base station in a wireless communication system, the last serving base station comprising: a transceiver; and a controller configured to: receive, from a base station via the transceiver, a user equipment (UE) context request message associated with a UE, wherein the UE context request message includes a base station UE application protocol (AP) identifier allocated by the base station and an identifier of the UE allocated by the last serving base station for identifying a context of the UE, identify the context of the UE based on the identifier of the UE, perform a security check based on the UE context request message associated with the UE, transmit, to the base station via the transceiver, a UE context response message associated with the UE based on a success of the security check, and receive, from the base station via the transceiver, information associated with releasing a context of the UE, wherein the UE context response message includes the base station UE AP identifier allocated by the base station and a base station UE AP identifier allocated by the last serving base station. ### Claim 14 (depends on 13) The last serving base station of claim 13, wherein the UE context request message includes at least one of a cell identifier of the base station, or a short Media Access Control (MAC) identifier (shortMACI). ### Claim 15 (depends on 14) The last serving base station of claim 14, wherein a path switch request message is transmitted from the base station to a mobility management node associated with the UE based on the UE context response message, wherein a path switch response message is received at the base station from the mobility management node associated with the UE, wherein the information associated with releasing the context of the UE is transmitted from the base station based on the path switch response message, wherein the security check is performed by the last serving base station based on the shortMACI included in the UE context request message, and wherein a resource allocated for the UE and the context of the UE is released based on the information associated with releasing context of the UE. ### Claim 16 (depends on 13) The last serving base station of claim 13, wherein the UE context response message includes at least one of information associated with a mobility management node, security information of the UE, capability information of the UE, or a mobility restriction list. ### Claim 17 A method performed by a user equipment (UE) in a wireless communication system, the method comprising: transmitting a first radio resource control (RRC) message to a base station; and receiving a last serving RRC message associated with an RRC connection from the base station, wherein a UE context request message associated with the UE is transmitted from the base station to a last serving base station based on reception of the first RRC message, wherein the last serving RRC message associated with the RRC connection is transmitted from the base station, based on reception of a UE context response message associated with the UE at the base station, wherein the UE context request message includes a base station UE application protocol (AP) identifier allocated by the base station and an identifier of the UE allocated by the last serving base station for identifying a context of the UE, and wherein the UE context response message includes the base station UE AP identifier allocated by the base station and a base station UE AP identifier allocated by the last serving base station. ### Claim 18 (depends on 17) The method of claim 17, wherein the UE context request message includes at least one of a cell identifier of the base station, or a short Media Access Control (MAC) identifier (shortMACI). ### Claim 19 (depends on 17) The method of claim 17, wherein the UE context response message includes at least one of information associated with a mobility management node, security information of the UE, capability information of the UE, or a mobility restriction list. ### Claim 20 A user equipment (UE) in a wireless communication system, the UE comprising: a transceiver; and a controller configured to: transmit, to a base station via the transceiver, a first radio resource control (RRC) message, and receive, from the base station via the transceiver, a last serving RRC message associated with an RRC connection, wherein a UE context request message associated with the UE is transmitted from the base station to a last serving base station based on reception of the first RRC message, wherein the last serving RRC message associated with the RRC connection is transmitted from the base station, based on reception of a UE context response message associated with the UE at the base station, wherein the UE context request message includes a base station UE application protocol (AP) identifier allocated by the base station and an identifier of the UE allocated by the last serving base station for identifying a context of the UE, and wherein the UE context response message includes the base station UE AP identifier allocated by the base station and a base station UE AP identifier allocated by the last serving base station. ### Claim 21 (depends on 20) The UE of claim 20, wherein the UE context request message includes at least one of a cell identifier of the base station, or a short Media Access Control (MAC) identifier (shortMACI). ### Claim 22 (depends on 20) The UE of claim 20, wherein the UE context response message includes at least one of information associated with a mobility management node, security information of the UE, capability information of the UE, or a mobility restriction list.