# US 2014/0194130 A1 · Methods and apparatus for efficient co-existence of macro and small cells > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0194130 A1 - Document ID: US20140194130A1 - Status: Published application - Kind: A1 - Application number: 13/738,936 - Filed: 2013-01-10 - Published: 2014-07-10 - Earliest claimed: 2013-01-10 - Assignees: QUALCOMM Incorporated - Applicants: Qualcomm Incorporated - Inventors: Nilesh Khude; Saurabha Rangrao Tavildar; Junyi Li; Vincent Douglas Park - Web page: https://patentgrep.com/patent/US20140194130A1 ## CPC - H04W 56/001: {Synchronization between nodes} - H04W 56/0045: {compensating for timing error by altering transmission time} - H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72) ## Abstract A femto base station (BS) maintains two different timings: a femto BS downlink timing and a femto BS uplink timing. A femto base station's uplink reference timing is based on the macro uplink timing being used by one or more UE devices in the local vicinity of the femto BS. In some embodiments, the femto BS synchronizes its femto uplink timing to the macro uplink timing being used by the closest UE device transmitting uplink signals to the macro BS. In other embodiments, the femto BS determines its femto base station uplink timing based on one or more uplink signals from UE devices in its vicinity transmitting to the macro BS. In various embodiments, femto cell uplink signals and macro cell uplink signals are received at a femto cell BS in synchronization. This approach facilitates frequency division multiplexing (FDM) in the uplink between a macro cell and a femto cell. ## Claims ### Claim 1 A method of operating a femto base station within a coverage area of a macro base station, the method comprising: determining the arrival time, at said femto base station, of a first signal transmitted by a first user equipment (UE) device to said macro base station; generating a femto base station uplink reference time based on said determined arrival time of the first signal; and controlling uplink transmission timing of devices communicating with said femto base station to synchronize arrival times at said femto base station of signals, transmitted by said devices communicating with said femto base station to said femto base station uplink reference time. ### Claim 2 (depends on 1) The method of claim 1, wherein said synchronization of the arrival time at said femto base station is to within the duration of a cyclic prefix used by user equipment devices transmitting to said macro base station. ### Claim 3 (depends on 2) The method of claim 2, further comprising: measuring, at said femto base station, the received signal power of signals transmitted by UE devices communicating with said macro base station; and wherein said first UE device is a UE device from which said femto base station received a highest power signal to said macro base station. ### Claim 4 (depends on 1) The method of claim 1, wherein generating a femto base station uplink reference time is further based on the arrival times of additional signals transmitted by UE devices to said macro base station. ### Claim 5 (depends on 4) The method of claim 4, further comprising: selecting said additional signals based on the measured received power of said signals transmitted to said macro base station. ### Claim 6 (depends on 5) The method of claim 5, wherein generating a femto base station uplink reference time includes: generating a weighted average arrival time based on the arrival time of said first signal and the arrival times of said selected additional signals. ### Claim 7 (depends on 1) The method of claim 1, further comprising; determining a femto base station downlink reference time from the arrival time at said femto base station of a signal transmitted by said macro base station. ### Claim 8 A femto base station within a coverage area of a macro base station, the femto base station comprising: means for determining the arrival time, at said femto base station, of a first signal transmitted by a first user equipment (UE) device to said macro base station; means for generating a femto base station uplink reference time based on said determined arrival time of the first signal; and means for controlling uplink transmission timing of devices communicating with said femto base station to synchronize arrival times at said femto base station of signals transmitted by said devices communicating with said femto base station to said femto base station uplink reference time. ### Claim 9 (depends on 8) The femto base station of claim 8, wherein said synchronization of the arrival time at said femto base station is to within the duration of a cyclic prefix used by user equipment devices transmitting to said macro base station. ### Claim 10 (depends on 9) The femto base station of claim 9, further comprising: means for measuring, at said femto base station, the received signal power of signals transmitted by UE devices communicating with said macro base station; and wherein said first UE device is a UE device from which said femto base station received a highest power signal to said macro base station. ### Claim 11 (depends on 8) The femto base station of claim 8, wherein said means for generating a femto base station uplink reference time includes means for generating a femto base station uplink reference time based on the arrival times of additional signals transmitted by UE devices to said macro base station. ### Claim 12 (depends on 11) The femto base station of claim 11, further comprising: means for selecting said additional signals based on the measured received power of said signals transmitted to said macro base station. ### Claim 13 (depends on 12) The femto base station of claim 12, wherein said means for generating a femto base station uplink reference time includes: means for generating a weighted average arrival time based on the arrival time of said first signal and the arrival times of said selected additional signals. ### Claim 14 (depends on 8) The femto base station of claim 8, further comprising: means for determining a femto base station downlink reference time from the arrival time at said femto base station of a signal transmitted by said macro base station. ### Claim 15 A computer program product for use in a femto base station within the coverage area of a macro base station, the computer program product comprising: a non-transitory computer readable medium comprising: code for causing at least one computer to determine the arrival time, at said femto base station, of a first signal transmitted by a first user equipment (UE) device to said macro base station; code for causing said at least one computer to generate a femto base station uplink reference time based on said determined arrival time of the first signal; and code for causing said at least one computer to control uplink transmission timing of devices communicating with said femto base station, to synchronize arrival times at said femto base station of signals transmitted by said devices communicating with said femto base station to said femto base station uplink reference time. ### Claim 16 A femto base station within the coverage area of a macro base station, the femto base station comprising: at least one processor configured to: determine the arrival time, at said femto base station, of a first signal transmitted by a first user equipment (UE) device to said macro base station; generate a femto base station uplink reference time based on said determined arrival time of the first signal; and control uplink transmission timing of devices communicating with said femto base station to synchronize arrival times at said femto base station of signals transmitted by said devices communicating with said femto base station to said femto base station uplink reference time; and memory coupled to said at least one processor. ### Claim 17 (depends on 16) The femto base station of claim 16, wherein said synchronization of the arrival time at said femto base station is to within the duration of a cyclic prefix used by user equipment devices transmitting to said macro base station. ### Claim 18 (depends on 17) The femto base station of claim 17, wherein said at least one processor is further configured to: measure, at said femto base station, the received signal power of signals transmitted by UE devices communicating with said macro base station; and wherein said first UE device is a UE device from which said femto base station received a highest power signal to said macro base station. ### Claim 19 (depends on 16) The femto base station of claim 16, wherein said at least one processor is configured to generate the femto base station uplink reference time based on the arrival times of additional signals transmitted by UE devices to said macro base station, as part of being configured to generate a femto base station uplink reference time. ### Claim 20 (depends on 19) The femto base station of claim 19, wherein said at least one processor is further configured to select said additional signals based on the measured received power of said signals transmitted to said macro base station.