# US 2008/0186920 A1 · Seamless context switching for radio link protocol > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2008/0186920 A1 - Document ID: US20080186920A1 - Status: Published application - Kind: A1 - Application number: 12/012,786 - Filed: 2008-02-04 - Published: 2008-08-07 - Earliest claimed: 2007-02-02 - Assignees: QUALCOMM Incorporated - Inventors: Ramin Rezaiifar; Peter Black - Web page: https://patentgrep.com/patent/US20080186920A1 ## CPC - H04W 36/02: Buffering or recovering information during reselection {; Modification of the traffic flow during hand-off} - H04W 36/14: Reselecting a network or an air interface - H04W 76/20: Manipulation of established connections - H04W 80/06: Transport layer protocols, e.g. TCP [Transport Control Protocol] over wireless {(transmission control protocol/Internet protocol [TCP/IP] or user datagram protocol [UDP] H04L69/16)} - H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72) ## Abstract Techniques to support handover of a terminal from a source base station to a target base station are described. In one design, a determination is made whether a change in personality is requested by the terminal. If the answer is ‘Yes’, then the personality of the terminal may be switched by sending one or more appropriate messages. The connection and RLP for the terminal may be reset due to the change in personality. A buffer of data reported by the source base station as being served to the terminal (e.g., no NAK was sent) may be saved by a BSC/PCF. The buffer of data may be sent to the target base station when handover occurs. New data may thereafter be sent to the target base station. This buffer of duplicate data may avoid both loss of data and retransmission timeout by TCP during the handover. ## Claims ### Claim 1 An apparatus for wireless communication, comprising: at least one processor configured to reset a connection for a terminal in response to handover from a source base station to a target base station, to store data reported as having been served to the terminal by the source base station, to send the stored data to the target base station after the handover, and to send new data for the terminal to the target base station after sending the stored data; and a memory coupled to the at least one processor. ### Claim 2 (depends on 1) The apparatus of claim 1, wherein the at least one processor is configured to determine if a personality change for the terminal is requested, and to switch the personality of the terminal if requested. ### Claim 3 (depends on 2) The apparatus of claim 2, wherein the at least one processor is configured to switch the personality of the terminal in response to the handover from the source base station to the target base station. ### Claim 4 (depends on 2) The apparatus of claim 2, wherein the at least one processor is configured to reset Radio Link Protocol (RLP) for the terminal in response to the switch in the personality of the terminal. ### Claim 5 (depends on 1) The apparatus of claim 1, wherein the source base station supports a first revision of an air interface and the second base station supports a second revision of the air interface. ### Claim 6 (depends on 1) The apparatus of claim 1, wherein the at least one processor is configured to send the data reported as having been served to the terminal to the source base station prior to the handover. ### Claim 7 (depends on 1) The apparatus of claim 1, wherein the at least one processor is configured to store a predetermined amount of data most recently served to the terminal by the serving base station. ### Claim 8 (depends on 7) The apparatus of claim 7, wherein the at least one processor is configured to determine the data most recently served to the terminal by the serving base station based on a flow control message received from the source base station. ### Claim 9 (depends on 1) The apparatus of claim 1, wherein the at least one processor is configured to store an amount of data corresponding to a maximum packet size. ### Claim 10 (depends on 1) The apparatus of claim 1, wherein the at least one processor is configured to send the stored data to the target base station after the handover to avoid retransmission timeout (RTO) of Transmission Control Protocol (TCP). ### Claim 11 A method for wireless communication, comprising: resetting a connection for a terminal in response to handover from a source base station to a target base station; storing data reported as having been served to the terminal by the source base station; sending the stored data to the target base station after the handover; and sending new data for the terminal to the target base station after sending the stored data. ### Claim 12 (depends on 11) The method of claim 11, further comprising: determining if a personality change for the terminal is requested; and switching the personality of the terminal if requested. ### Claim 13 (depends on 11) The method of claim 11, further comprising: resetting Radio Link Protocol (RLP) for the terminal in response to the switch in the personality of the terminal. ### Claim 14 (depends on 11) The method of claim 11, wherein the storing data comprises storing a predetermined amount of data most recently served to the terminal by the serving base station. ### Claim 15 (depends on 11) The method of claim 11, wherein the sending the stored data comprises sending the stored data to the target base station after the handover to avoid retransmission timeout (RTO) of Transmission Control Protocol (TCP). ### Claim 16 An apparatus for wireless communication, comprising: means for resetting a connection for a terminal in response to handover from a source base station to a target base station; means for storing data reported as having been served to the terminal by the source base station; means for sending the stored data to the target base station after the handover; and means for sending new data for the terminal to the target base station after sending the stored data. ### Claim 17 (depends on 16) The apparatus of claim 16, further comprising: means for determining if a personality change for the terminal is requested; and means for switching the personality of the terminal if requested. ### Claim 18 (depends on 16) The apparatus of claim 16, further comprising: means for resetting Radio Link Protocol (RLP) for the terminal in response to the switch in the personality of the terminal. ### Claim 19 (depends on 16) The apparatus of claim 16, wherein the means for storing data comprises means for storing a predetermined amount of data most recently served to the terminal by the serving base station. ### Claim 20 (depends on 16) The apparatus of claim 16, wherein the means for sending the stored data comprises means for sending the stored data to the target base station after the handover to avoid retransmission timeout (RTO) of Transmission Control Protocol (TCP). ### Claim 21 A computer program product, comprising: a computer-readable medium comprising: code for causing at least one computer to reset a connection for a terminal in response to handover from a source base station to a target base station; code for causing the at least one computer to store data reported as having been served to the terminal by the source base station; code for causing the at least one computer to store send the stored data to the target base station after the handover; and code for causing the at least one computer to send new data for the terminal to the target base station after sending the stored data. ### Claim 22 An apparatus for wireless communication, comprising: at least one processor configured to reset a connection for a terminal in response to handover from a source base station to a target base station, to receive data from the source base station prior to the handover, to receive duplicate data from the target base station after the handover, the duplicate data being received previously from the source base station prior to the handover, and to receive new data from the target base station after receiving the duplicate data; and a memory coupled to the at least one processor. ### Claim 23 (depends on 22) The apparatus of claim 22, wherein the at least one processor is configured to switch personality of the terminal in response to the handover. ### Claim 24 (depends on 22) The apparatus of claim 22, wherein the at least one processor is configured to discard the duplicate data received from the target base station, and to reassemble packets based on the new data received from the target base station and prior data received from the source base station. ### Claim 25 A method for wireless communication, comprising: resetting a connection for a terminal in response to handover from a source base station to a target base station; receiving data from the source base station prior to the handover; receiving duplicate data from the target base station after the handover, the duplicate data being received previously from the source base station prior to the handover; and receiving new data from the target base station after receiving the duplicate data. ### Claim 26 (depends on 25) The method of claim 25, further comprising: switching personality of the terminal in response to the handover. ### Claim 27 (depends on 25) The method of claim 25, further comprising: discarding the duplicate data received from the target base station; and reassembling packets based on the new data received from the target base station and prior data received from the source base station. ### Claim 28 An apparatus for wireless communication, comprising: means for resetting a connection for a terminal in response to handover from a source base station to a target base station; means for receiving data from the source base station prior to the handover; means for receiving duplicate data from the target base station after the handover, the duplicate data being received previously from the source base station prior to the handover; and means for receiving new data from the target base station after receiving the duplicate data. ### Claim 29 (depends on 28) The apparatus of claim 28, further comprising: means for switching personality of the terminal in response to the handover. ### Claim 30 (depends on 28) The apparatus of claim 28, further comprising: means for discarding the duplicate data received from the target base station; and means for reassembling packets based on the new data received from the target base station and prior data received from the source base station. ### Claim 31 A computer program product, comprising: a computer-readable medium comprising: code for causing at least one computer to reset a connection for a terminal in response to handover from a source base station to a target base station; code for causing the at least one computer to receive data from the source base station prior to the handover; code for causing the at least one computer to receive duplicate data from the target base station after the handover, the duplicate data being received previously from the source base station prior to the handover; and code for causing the at least one computer to receive new data from the target base station after receiving the duplicate data.