# US 9,521,600 B2 · Handover mechanism in cellular networks > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,521,600 B2 - Document ID: US9521600B2 - Status: Granted - Kind: B2 - Application number: 13/752,316 - Filed: 2013-01-28 - Published: 2014-07-31 - Granted: 2016-12-13 - Earliest claimed: 2013-01-28 - Assignees: BlackBerry Limited - Applicants: BlackBerry Limited - Inventors: Chandra Sekhar Bontu; Yi Song; Zhijun Cai; Shalini Suresh Periyalwar - Web page: https://patentgrep.com/patent/US9521600B2 ## CPC - H04W 36/04: Reselecting a cell layer in multi-layered cells - H04W 36/026: {Multicasting of data during hand-off} - H04W 36/00835: {Determination of neighbour cell lists} - 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 Systems, apparatuses, and methods for a handover procedure in heterogeneous networks are provided. In particular, an intermediate handover (IHO) is introduced. Certain aspects of the disclosure involve, a method, performed at a first base station of a wireless communications network. An indication that a user equipment (UE) is receiving coverage signal from a second base station can be received. A data packet destined for the UE can be transmitted to the second base station. A communications link with the UE can be maintained after transmitting the data packet to the second base station. ## Claims ### Claim 1 A method performed at a first base station of a wireless communications network, the method comprising: receiving an indication that a user equipment (UE) is receiving coverage signal from a second base station; forwarding data packets destined for the UE to the second base station; maintaining a RRC_connected state with the UE after forwarding the data packets destined for the UE to the second base station, wherein maintaining the RRC_connected state with the UE comprises: sending, from the first base station to the UE, a first Radio Resource Control (RRC) message after forwarding the data packets; and in response to the first RRC message, receiving, at the first base station, a second RRC message from the UE; receiving a data packet destined for an Evolved Packet Core (EPC) from the second base station; decrypting the data packet destined for the EPC to form Packet Data Convergence Protocol (PDCP) Service Data Unit (SDU); forwarding the data packet destined for the EPC to the EPC; and maintaining a communications link with the UE after forwarding the data packet destined for the EPC from the second base station. ### Claim 2 (depends on 1) The method of claim 1, wherein the indication is a quality of service indicator. ### Claim 3 (depends on 1) The method of claim 1, wherein the coverage signal includes one or more of: a reference signal, a system information broadcast signal, or a data transmission signal transmitted by a base station. ### Claim 4 (depends on 1) The method of claim 1, wherein forwarding the data packets destined for the UE further comprises: receiving a data packet destined for the UE from an Evolved Packet Core (EPC); encrypting the data packet destined for the UE to form PDCP PDU; and forwarding the encrypted data packet destined for the UE to the second base station. ### Claim 5 (depends on 1) The method of claim 1, wherein forwarding the data packets destined for the UE to the second base station is performed across one or more of an X2 interface or an S1 interface. ### Claim 6 (depends on 1) The method of claim 1, wherein maintaining the RRC_connected state with the UE includes reserving a C-RNTI assigned to the UE for the first base station. ### Claim 7 (depends on 1) The method of claim 1, further comprising: receiving an indication that the coverage signal from the second base station is stronger than a coverage signal from the first base station; handing over control of communications for the UE to the second base station; and terminating the communications link with the UE. ### Claim 8 (depends on 7) The method of claim 7, wherein the indication is a quality of service indicator. ### Claim 9 A base station in a wireless communications network, the base station configured to: receive an indication that a user equipment (UE) is receiving coverage signal from a second base station; forward data packets destined for the UE to the second base station; maintaining a RRC_connected state with the UE after forwarding the data packets destined for the UE to the second base station, wherein maintaining the RRC_connected state with the UE comprises: sending, from the base station to the UE, a first Radio Resource Control (RRC) message after forwarding the data packets; and in response to the first RRC message, receiving, at the base station, a second RRC message from the UE; receiving a data packet destined for an Evolved Packet Core (EPC) from the second base station; decrypting the data packet destined for the EPC to form Packet Data Convergence Protocol (PDCP) Service Data Unit (SDU); forwarding the data packet destined for the EPC to the EPC; and maintaining a communications link with the UE after forwarding the data packet destined for the EPC from the second base station. ### Claim 10 (depends on 9) The base station of claim 9, wherein the indication is a quality of service indicator. ### Claim 11 (depends on 9) The base station of claim 9, wherein the coverage signal includes one or more of: a reference signal, a system information broadcast signal, or a data transmission signal transmitted by a base station. ### Claim 12 (depends on 9) The base station of claim 9, wherein forwarding the data packets destined for the UE further comprises: receiving a data packet destined for the UE from an EPC; encrypting the data packet destined for the UE to form PDCP PDU; and forwarding the encrypted data packet destined for the UE to the second base station. ### Claim 13 (depends on 9) The base station of claim 9, wherein forwarding the data packets destined for the UE to the second base station is performed across one or more of an X2 interface or an S1 interface. ### Claim 14 (depends on 9) The base station of claim 9, wherein maintaining the RRC_connected state with the UE includes reserving a C-RNTI assigned to the UE for the first base station. ### Claim 15 (depends on 9) The base station of claim 9, further configured to: receive an indication that the coverage signal from the second base station is stronger than a coverage signal from the base station; hand over control of communications for the UE to the second base station; and terminate the communications link with the UE. ### Claim 16 (depends on 15) The base station of claim 15, wherein the indication is a quality of service indicator.