User equipment and methods for cell reselection using scaled time-to-trigger and A3 offset values

• US 9,674,757 B2
• Filed: 09/03/2015
• Issued: 06/06/2017
• Est. Priority Date: 04/04/2013
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Intel IP Corporation (Intel Corporation)
• Inventors: Zhang, Yujian, Yiu, Candy
• Primary Examiner(s): Eisner, Ronald
• Application Number:
  US14/845,019
• Publication Number:
  US 20160066243A1
• Time in Patent Office: 642 Days
• Field of Search: 455436-444, 370321-334, 370328-330
• CPC Class Codes: H04B 1/38 Transceivers, i.e. devices in which transmitter and receiver form a structural unit and in which at least one part is used for functions of transmitting and receiving
• CPC Class Codes: H04B 7/024 Co-operative use of antennas of several sites, e.g. in co-ordinated multipoint or co-operative multiple-input multiple-output [MIMO] systems
• CPC Class Codes: H04B 7/0456 Selection of precoding matrices or codebooks, e.g. using matrices antenna weighting
• CPC Class Codes: H04B 7/0639 Using selective indices, e.g. of a codebook, e.g. pre-distortion matrix index [PMI] or for beam selection
• CPC Class Codes: H04L 1/1854 Scheduling and prioritising arrangements
• CPC Class Codes: H04L 12/18 for broadcast or conference , e.g. multicast
• CPC Class Codes: H04L 43/0823 Errors, e.g. transmission errors
• CPC Class Codes: H04L 5/0007 the frequencies being orthogonal, e.g. OFDM(A), DMT
• CPC Class Codes: H04L 5/0053 Allocation of signaling, i.e. of overhead other than pilot signals
• CPC Class Codes: H04L 5/0055 Physical resource allocation for ACK/NACK for physical mapping arrangements in ARQ protocols H04L1/1861
• CPC Class Codes: H04L 5/0094 Indication of how sub-channels of the path are allocated
• CPC Class Codes: H04L 5/14 Two-way operation using the same type of signal, i.e. duplex
• CPC Class Codes: H04L 65/1016 IP multimedia subsystem [IMS]
• CPC Class Codes: H04L 65/1045 Proxies, e.g. for session initiation protocol [SIP]
• CPC Class Codes: H04L 65/1104 Session initiation protocol [SIP]
• CPC Class Codes: H04L 65/611 for multicast or broadcast systems for broadcast or conference H04L12/18; arrangements for broadcast or distribution combined with broadcast H04H20/00; arrangements for broadcast applications with a direct linkage to broadcast information or to broadcast space-time H04H60/00; selective distribution of broadcast services, e.g. multimedia broadcast multicast service [MBMS], H04W4/06
• CPC Class Codes: H04L 65/613 for the control of the source by the destination control signals issued by the client directed to the server or network components specially adapted for selective content distribution H04N21/637
• CPC Class Codes: H04L 67/02 based on web technology, e.g. hypertext transfer protocol [HTTP]
• CPC Class Codes: H04L 67/1076 Resource dissemination mechanisms or network resource keeping policies for optimal resource availability in the overlay network
• CPC Class Codes: H04W 24/02 Arrangements for optimising operational condition
• CPC Class Codes: H04W 24/08 : Testing, supervising or monitoring using real traffic
• CPC Class Codes: H04W 36/0088 : Scheduling hand-off measurements
• CPC Class Codes: H04W 36/0094 : Definition of hand-off measurement parameters
• CPC Class Codes: H04W 36/14 : Reselecting a network or an air interface
• CPC Class Codes: H04W 36/30 : by measured or perceived connection quality data
• CPC Class Codes: H04W 36/36 : by user or terminal equipment
• CPC Class Codes: H04W 36/38 : by fixed network equipment
• CPC Class Codes: H04W 4/70 : Services for machine-to-machine communication [M2M] or machine type communication [MTC]
• CPC Class Codes: H04W 56/001 : Synchronization between nodes
• CPC Class Codes: H04W 68/02 : Arrangements for increasing efficiency of notification or paging channel
• CPC Class Codes: H04W 72/0446 : Resources in time domain, e.g. slots or frames
• CPC Class Codes: H04W 72/1215 : for collaboration of different radio technologies
• CPC Class Codes: H04W 72/1263 : Mapping of traffic onto schedule, e.g. scheduled allocation or multiplexing of flows
• CPC Class Codes: H04W 72/21 : in the uplink direction of a wireless link, i.e. towards the network
• CPC Class Codes: H04W 72/23 : in the downlink direction of a wireless link, i.e. towards a terminal
• CPC Class Codes: H04W 72/51 : based on terminal or device properties
• CPC Class Codes: H04W 72/52 : based on load
• CPC Class Codes: H04W 74/0808 : using carrier sensing, e.g. carrier sense multiple access [CSMA]
• CPC Class Codes: H04W 76/00 : Connection management
• CPC Class Codes: H04W 76/10 : Connection setup
• CPC Class Codes: H04W 76/11 : Allocation or use of connection identifiers
• CPC Class Codes: H04W 76/12 : Setup of transport tunnels
• CPC Class Codes: H04W 76/15 : Setup of multiple wireless link connections
• CPC Class Codes: H04W 76/20 : Manipulation of established connections
• CPC Class Codes: H04W 76/22 : Manipulation of transport tunnels
• CPC Class Codes: H04W 76/27 : Transitions between radio resource control [RRC] states
• CPC Class Codes: H04W 76/28 : Discontinuous transmission [DTX]; Discontinuous reception [DRX]
• CPC Class Codes: H04W 76/30 : Connection release
• CPC Class Codes: H04W 76/38 : triggered by timers
• CPC Class Codes: H04W 8/005 : Discovery of network devices, e.g. terminals
• CPC Class Codes: H04W 84/045 : using private Base Stations, e.g. femto Base Stations, home Node B
• CPC Class Codes: H04W 84/12 : WLAN [Wireless Local Area Networks]
• CPC Class Codes: H04W 88/02 : Terminal devices
• CPC Class Codes: H04W 88/06 : adapted for operation in multiple networks or having at least two operational modes, e.g. multi-mode terminals
• CPC Class Codes: H04W 88/08 : Access point devices
• CPC Class Codes: H04W 92/20 : between access points
• CPC Class Codes: Y02D 30/70 : in wireless communication networks

Abstract

Embodiments of user equipment (UE) and method for handover enhancement using a scaled time-to-trigger (TTT) and a time-of-stay are generally described herein. In some embodiments, the TTT is scaled based on at least one of a measured reference signal received quality (RSRQ) value of a serving cell and a time-of-stay in the serving cell.

Claims

1. An apparatus of user equipment (UE) comprising transceiver circuitry and processing circuitry configured to:

detect a mobility state of the UE, the mobility state being one of a plurality of different potential mobility states that comprise a high mobility state and a medium mobility state;

scale at least one of an A3 offset value or a time-to-trigger (TTT) value based on the detected mobility state, wherein at least one of the TTT value is increased or the A3 offset value is decreased when the high mobility state is detected and the at least one of the TTT value or the A3 offset value is scaled for fast handover based on a predetermined condition unrelated to the mobility state, the high mobility state and fast handover defined by a Third Generation Partnership Project (3GPP) information element;

compare a reference signal received power (RSRP) level of a serving cell with a RSRP level of a target cell, the predetermined condition related to a type of the serving cell and a type of the target cell, the type of the serving cell and the type of the target cell dependent on cell size, handover being initiated faster for smaller serving or target cells than for larger serving or target cells; and

transmit a measurement report to an enhanced node B (eNB) of the serving cell when the RSRP level of the target cell exceeds the RSRP level of the serving cell by the A3 offset value for the TTT value.

2. The apparatus of claim 1 wherein the mobility state of the UE is detected based on a number of handovers.

3. The apparatus of claim 1 wherein the mobility state of the UE is detected based on a number of cell reselections.

4. The apparatus of claim 1 wherein the mobility state of the UE is detected based on a velocity of the UE.

5. The apparatus of claim 1 wherein the measurement report is a measurement report for cell reselection.

6. The apparatus of claim 1 wherein when the A3 offset value is scaled based on the mobility state, the measurement report is generated when the reference signal level of the target cell exceeds the reference signal level of the serving cell by the scaled A3 offset value for a time equal to or exceeding the TTT value.

7. The apparatus of claim 1 wherein when the TTT value is scaled based on the mobility state, the measurement report is generated when the reference signal level of the target cell exceeds the reference signal level of the serving cell by the A3 offset value for a time equal to or exceeding the scaled TTT value.

8. The apparatus of claim 1 wherein when both the A3 offset value and the TTT value are scaled based on the mobility state, the measurement report is generated when the reference signal level of the target cell exceeds the reference signal level of the serving cell by the scaled A3 offset value for a time equal to or exceeding the scaled TTT value.

9. The apparatus of claim 1 further comprising two or more antennas coupled to the transceiver circuitry configured to receive reference signals associated with the reference signal levels, and wherein the processing circuitry is further configured to refrain from scaling at least one of the A3 offset value or the TTT value when neither the high mobility state or the medium mobility state is detected.

16. The apparatus of claim 1 wherein the at least one of the A3 offset value or TTT value are scaled based on the RSRQ such that the UE recovers connectivity, using the target cell, prior to expiry of a T310 timer.

17. The apparatus of claim 1 wherein the processing circuitry is further configured to measure a time of stay of the serving cell and if the time of stay is greater than a predetermined value, scale the at least one of the TTT value or the A3 offset value for fast handover.

18. The apparatus of claim 17 wherein the TTT value scales inversely with the time of stay.

19. The apparatus of claim 1 wherein the transceiver circuitry and processing circuitry are further configured to receive a ReportConfigEUTRA information element configured with a plurality of parameters to scale the at least one of the TTT value or the A3 offset value using the serving cell RSRQ, the parameters comprising a RSRQ radio link failure threshold, a RSRQ fast handover threshold and A3offset, TTT and short time-of-stay threshold pairs.

20. The apparatus of claim 1 wherein:

the processing circuitry is further configured to measure a reference signal received quality (RSRQ) of a serving cell, and the at least one of the A3 offset value or the TTT value is based on the RSRQ, and the predetermined condition comprises the RSRQ being below a predetermined value.

21. The apparatus of claim 1 wherein:

the at least one of the A3 offset value or the TTT value is based on at least one of a type of handover or the type of the serving or target cell.

22. The apparatus of claim 21 wherein the processing circuitry is further configured to:

determine the at least one of type of the serving or target cell from an indicator of signal strength received from the eNB.

23. The apparatus of claim 1 wherein:

the at least one of the A3 offset value or the TTT value is free from being based on the RSRP level.

10. A non-transitory computer-readable storage medium that stores instructions for execution by one or more processors of user equipment (UE) to configure the UE to perform operations to:

measure a reference signal received quality (RSRQ) of a serving cell;

detect a mobility state of the UE, the mobility state being one of a plurality of different potential mobility states that comprise a high mobility state and a medium mobility state;

scale at least one of an A3 offset value or a time-to-trigger (TTT) value based on the detected mobility state and the RSRQ, wherein at least one of the TTT value is increased or the A3 offset value is decreased when the high mobility state is detected and the at least one of the TTT value or the A3 offset value is scaled for fast handover based on the RSRQ being below a predetermined value, the high mobility state and fast handover defined by a Third Generation Partnership Project (3GPP) information element, handover being initiated faster for smaller serving or target cells than for larger serving or target cells;

compare a reference signal level received power (RSRP) of the serving cell with a RSRP of a target cell; and

transmit a measurement report to an enhanced node B (eNB) of the serving cell when the RSRP level of the target cell exceeds the RSRP level of the serving cell by the A3 offset value for the TTT value.

11. The apparatus of claim 10 wherein the mobility state of the UE is detected based on a number of handovers or on a number of cell reselections.

12. The apparatus of claim 10 wherein:

when the A3 offset value is scaled based on the mobility state, the measurement report is generated when the reference signal level of the target cell exceeds the reference signal level of the serving cell by the scaled A3 offset value for a time equal to or exceeding the TTT value, and when the TTT value is scaled based on the mobility state, the measurement report is generated when the reference signal level of the target cell exceeds the reference signal level of the serving cell by the A3 offset value for a time equal to or exceeding the scaled TTT value.

13. An apparatus of user equipment (UE) comprising transceiver circuitry and processing circuitry configured to:

measure a reference signal received quality (RSRQ) of a serving cell;

detect a mobility state of the UE based on a number of handovers, the mobility state being one of a plurality of different potential mobility states that comprise a high mobility state and a medium mobility state;

scale at least one of an A3 offset value or a time-to-trigger (TTT) value based on the detected mobility state and the RSRQ, wherein at least one of the TTT value is increased or the A3 offset value is decreased when the high mobility state is detected and the at least one of the TTT value or the A3 offset value is scaled for fast handover based on the RSRQ being below a predetermined value, the high mobility state and fast handover defined by a Third Generation Partnership Project (3GPP) information element, handover being initiated faster for smaller serving or target cells than for larger serving or target cells;

receive a reference signal received power (RSRP) associated with a serving cell and a RSRP associated with a target cell;

compare a RSRP level associated with the serving cell with a RSRP level associated with a target cell; and

transmit a measurement report for cell reselection to an enhanced node B (eNB) of the serving cell when the RSRP level of the target cell exceeds the RSRP level of the serving cell by the A3 offset value for the TTT value.

14. The apparatus of claim 13 wherein the signal level of the reference signals is a reference signal received power (RSRP) level for intra-RAN handovers.

15. The apparatus of claim 14 wherein the A3 offset value and the TTT value are selected for use in a heterogeneous network.