WO2018224545A1

WO2018224545A1 - Use of handover measurements for wireless networks based on signal blocking condition

Info

Publication number: WO2018224545A1
Application number: PCT/EP2018/064890
Authority: WO
Inventors: Jari Petteri Lunden; Elena Virtej; Niko KOLEHMAINEN; Frank Frederiksen
Original assignee: Nokia Technologies Oy
Priority date: 2017-06-09
Filing date: 2018-06-06
Publication date: 2018-12-13

Abstract

A technique includes determining, by a user device, that a signal blocking condition is present with respect to a serving cell; determining, by the user device, that a signal blocking condition is not present with respect to a neighbor cell; determining that a signal parameter for the neighbor cell is greater than an absolute threshold; and performing, by the user device, an action in response to determining that both the signal blocking condition is present with respect to the serving cell and the signal blocking condition is not present with respect to the neighbor cell and the signal parameter for the neighbor cell is greater than an absolute threshold, the action including at least one of the following: sending a measurement report to the serving cell; and sending a message to the neighbor cell to trigger a handover of the user device to the neighbor cell.

Description

USE OF HANDOVER MEASUREMENTS FOR WIRELESS NETWORKS BASED ON SIGNAL BLOCKING CONDITION

TECHNICAL FIELD

[0001 ] This description relates to communications.

BACKGROUND

[0002] A communication system may be a facility that enables communication between two or more nodes or devices, such as fixed or mobile communication devices. Signals can be carried on wired or wireless carriers.

[0003] An example of a cellular communication system is an architecture that is being standardized by the 3^rd Generation Partnership Project (3GPP). A recent development in this field is often referred to as the Long Term Evolution (LTE) of the Universal Mobile Telecommunications System (UMTS) radio-access technology. E- UTRA (evolved UMTS Terrestrial Radio Access) is the air interface of 3GPP's Long Term Evolution (LTE) upgrade path for mobile networks. In LTE, base stations or access points (APs), which are referred to as enhanced Node AP (eNBs), provide wireless access within a coverage area or cell. In LTE, mobile devices, or mobile stations are referred to as user equipments (UE). LTE has included a number of improvements or developments.

[0004] Moreover, there are some types of wireless networks or wireless spectrum, e.g., such as unlicensed wireless spectrum, in which multiple devices may share or compete for transmission on a wireless channel or portion of wireless spectrum. For example, in some cases, wireless devices may implement a listen before talk (LBT) to determine that a wireless channel is idle, before transmitting.

SUMMARY

[0005] According to an example implementation, a method includes determining, by a user device in a wireless network, that a signal blocking condition is present with respect to a serving cell; determining, by the user device, that a signal blocking condition is not present with respect to a neighbor cell; determining that a signal parameter for the neighbor cell is greater than an absolute threshold; and performing, by the user device, an action in response to determining that both the signal blocking condition is present with respect to the serving cell and the signal blocking condition is not present with respect to the neighbor cell and the signal parameter for the neighbor cell is greater than an absolute threshold, the action including at least one of the following: sending a measurement report to the serving cell; and sending a message to the neighbor cell to trigger a handover of the user device to the neighbor cell.

[0006] According to an example implementation, an apparatus includes at least one processor and at least one memory including computer instructions, when executed by the at least one processor, cause the apparatus to: determine, by a user device in a wireless network, that a signal blocking condition is present with respect to a serving cell; determine, by the user device, that a signal blocking condition is not present with respect to a neighbor cell; determine that a signal parameter for the neighbor cell is greater than an absolute threshold; and perform, by the user device, an action in response to determining that both the signal blocking condition is present with respect to the serving cell and the signal blocking condition is not present with respect to the neighbor cell and the signal parameter for the neighbor cell is greater than an absolute threshold, the action including at least one of the following: send a measurement report to the serving cell; and send a message to the neighbor cell to trigger a handover of the user device to the neighbor cell.

According to an example implementation, an apparatus includes means for determining, by a user device in a wireless network, that a signal blocking condition is present with respect to a serving cell; means for determining, by the user device, that a signal blocking condition is not present with respect to a neighbor cell; means for determining that a signal parameter for the neighbor cell is greater than an absolute threshold; and means for performing, by the user device, an action in response to determining that both the signal blocking condition is present with respect to the serving cell and the signal blocking condition is not present with respect to the neighbor cell and the signal parameter for the neighbor cell is greater than an absolute threshold, the action including at least one of the following: sending a measurement report to the serving cell; and sending a message to the neighbor cell to trigger a handover of the user device to the neighbor cell.

[0007] According to an example implementation, a computer program product includes a computer-readable storage medium and storing executable code that, when executed by at least one data processing apparatus, is configured to cause the at least one data processing apparatus to perform a method including: determining, by a user device in a wireless network, that a signal blocking condition is present with respect to a serving cell; determining, by the user device, that a signal blocking condition is not present with respect to a neighbor cell; determining that a signal parameter for the neighbor cell is greater than an absolute threshold; and performing, by the user device, an action in response to determining that both the signal blocking condition is present with respect to the serving cell and the signal blocking condition is not present with respect to the neighbor cell and the signal parameter for the neighbor cell is greater than an absolute threshold, the action including at least one of the following: sending a measurement report to the serving cell; and sending a message to the neighbor cell to trigger a handover of the user device to the neighbor cell.

[0008] According to an example implementation, a method includes determining, by a user device in a wireless network, whether or not a signal blocking condition is present with respect to a serving cell; determining, by the user device, whether or not a signal blocking condition is present with respect to a neighbor cell; sending, by the user device, a measurement report to the serving cell if both the signal blocking condition is present with respect to the serving cell and the signal blocking condition is not present with respect to the neighbor cell, and if a signal parameter for the neighbor cell is greater than an absolute threshold; and sending, by the user device, a measurement report to the serving cell if the signal blocking condition is not present with respect to the serving cell and if a signal parameter for the neighbor cell is greater than a signal parameter for the serving cell.

[0009] According to an example implementation, an apparatus includes at least one processor and at least one memory including computer instructions, when executed by the at least one processor, cause the apparatus to: determine, by a user device in a wireless network, whether or not a signal blocking condition is present with respect to a serving cell; determine, by the user device, whether or not a signal blocking condition is present with respect to a neighbor cell; send, by the user device, a measurement report to the serving cell if both the signal blocking condition is present with respect to the serving cell and the signal blocking condition is not present with respect to the neighbor cell, and if a signal parameter for the neighbor cell is greater than an absolute threshold; and send, by the user device, a measurement report to the serving cell if the signal blocking condition is not present with respect to the serving cell and if a signal parameter for the neighbor cell is greater than a signal parameter for the serving cell.

[0010] According to an example implementation, an apparatus includes means for determining, by a user device in a wireless network, whether or not a signal blocking condition is present with respect to a serving cell; means for determining, by the user device, whether or not a signal blocking condition is present with respect to a neighbor cell; means for sending, by the user device, a measurement report to the serving cell if both the signal blocking condition is present with respect to the serving cell and the signal blocking condition is not present with respect to the neighbor cell, and if a signal parameter for the neighbor cell is greater than an absolute threshold; and means for sending, by the user device, a measurement report to the serving cell if the signal blocking condition is not present with respect to the serving cell and if a signal parameter for the neighbor cell is greater than a signal parameter for the serving cell.

[0011 ] According to an example implementation, a computer program product includes a computer-readable storage medium and storing executable code that, when executed by at least one data processing apparatus, is configured to cause the at least one data processing apparatus to perform a method including: determining, by a user device in a wireless network, whether or not a signal blocking condition is present with respect to a serving cell; determining, by the user device, whether or not a signal blocking condition is present with respect to a neighbor cell; sending, by the user device, a measurement report to the serving cell if both the signal blocking condition is present with respect to the serving cell and the signal blocking condition is not present with respect to the neighbor cell, and if a signal parameter for the neighbor cell is greater than an absolute threshold; and sending, by the user device, a measurement report to the serving cell if the signal blocking condition is not present with respect to the serving cell and if a signal parameter for the neighbor cell is greater than a signal parameter for the serving cell.

[0012] The details of one or more examples of implementations are set forth in the accompanying drawings and the description below. Other features will be apparent from the description and drawings, and from the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] FIG. 1 is a block diagram of a wireless network according to an example implementation.

[0014] FIG. 2 is a flow chart illustrating operation of a user device according to an example implementation.

[0015] FIG. 3 is a flow chart illustrating operation of a user device according to an example implementation.

[0016] FIG. 4 is a flow chart illustrating operation of a user device according to another example implementation.

[0017] FIG. 5 is a block diagram of a node or wireless station (e.g., base station/access point or mobile station/user device) according to an example

implementation.

DETAILED DESCRIPTION

[0018] FIG. 1 is a block diagram of a wireless network 130 according to an example implementation. In the wireless network 130 of FIG. 1, user devices 131, 132, 133 and 135, which may also be referred to as mobile stations (MSs) or user equipment (UEs), may be connected (and in communication) with a base station (BS) 134, which may also be referred to as an access point (AP), an enhanced Node B (eNB), a gNB, or a network node. At least part of the functionalities of an access point (AP), base station (BS) or (e)Node B (eNB) may be also be carried out by any node, server or host which may be operably coupled to a transceiver, such as a remote radio head. BS (or AP) 134 provides wireless coverage within a cell 136, including to user devices 131, 132, 133 and 135. Although only four user devices are shown as being connected or attached to BS 134, any number of user devices may be provided. BS 134 is also connected to a core network 150 via a SI interface 151. This is merely one simple example of a wireless network, and others may be used.

[0019] A user device (user terminal, user equipment (UE) or mobile station) may refer to a portable computing device that includes wireless mobile communication devices operating with or without a subscriber identification module (SIM), including, but not limited to, the following types of devices: a mobile station (MS), a mobile phone, a cell phone, a smartphone, a personal digital assistant (PDA), a handset, a device using a wireless modem (alarm or measurement device, etc.), a laptop and/or touch screen computer, a tablet, a phablet, a game console, a notebook, and a multimedia device, as examples. It should be appreciated that a user device may also be a nearly exclusive uplink only device, of which an example is a camera or video camera loading images or video clips to a network.

[0020] In LTE (as an example), core network 150 may be referred to as Evolved Packet Core (EPC), which may include a mobility management entity (MME) which may handle or assist with mobility/handover of user devices between BSs, one or more gateways that may forward data and control signals between the BSs and packet data networks or the Internet, and other control functions or blocks.

[0021 ] In addition, by way of illustrative example, the various example implementations or techniques described herein may be applied to various types of user devices or data service types, or may apply to user devices that may have multiple applications running thereon that may be of different data service types.

[0022] The various example implementations may be applied to a wide variety of wireless technologies, wireless devices, wireless networks and/or different radio access technologies (RATs). For example, the various example implementations may be applied to a wide variety of wireless devices, such as wireless devices (e.g., user devices or UEs and/or BSs or APs) for LTE, LTE-A, New Radio (5G), cmWave, and/or mmWave band networks, IoT (Internet of Things), MTC (Machine to Machine communications), eMTC, eMBB (enhanced mobile broadband), URLLC (ultra-reliable and low-latency

communications), V2X (vehicle-to-vehicle, or vehicle-to-infrastructure), Wireless Local Area Network (WLAN), etc., or any other wireless network or wireless technology. These example networks, technologies or data service types are provided only as illustrative examples.

[0023] In an illustrative example implementation, multiple wireless devices may make use of bandwidth or wireless spectrum that is currently unused or otherwise available, but which may be unlicensed (e.g., not licensed for use by 3GPP devices). In some cases, in order to access unlicensed bandwidth or unlicensed wireless spectrum, some wireless devices may (or may be required to) implement a mechanism to do clear channel assessment or Listen-Before-Talk (LBT) before transmitting on a wireless channel, e.g., to avoid collisions of transmissions from different wireless devices over the same channel or portion of wireless spectrum. For example, under LBT, a device (e.g., eNB, BS, AP, user device or UE) attempting to use a portion of unlicensed spectrum (for example) may first sense or "listen" to a wireless channel or a portion of the spectrum to confirm that the wireless channel or portion of wireless spectrum is not in use (e.g., to confirm that no other wireless devices are currently transmitting on that portion of spectrum or wireless channel). If the sensing or listening has confirmed that the wireless channel of interest is idle or not in use, then the listening wireless device may then transmit or "talk" on the unused wireless channel or portion of wireless spectrum.

[0024] In addition, base stations (BSs), which may also be referred to as eNBs or APs, may transmit discovery reference signals (DRSs), which may include, for example, primary synchronization signals (PSS), secondary synchronization signals (SSS), cell- specific reference signals (CRS), enhanced system information block (eSIB) (SIB 1 and SIB2), master information block (MIB), enhanced primary synchronization signals (ePSS), enhanced secondary synchronization signal (eSSS), eSIB on physical downlink shared channel (PDSCH) (and associated with physical downlink control channel (PDCCH)) and/or channel state information reference signals (CSI-RS), if configured. [0025] On unlicensed spectrum, the need to perform LBT as regulated poses problems to mobility robustness. Transmission of various handover messages could be delayed, because another device is occupying the medium. Also, triggering of measurement events may be delayed because the UE is unable to obtain signal measurement samples when the LBT blocks transmission of DRS by the serving cell or neighbor cells.

[0026] For example, in a present MulteFire specification, the radio link monitoring (RLM) handles missing measurements (no DRS within DMTC window) so that low value sample is inserted in the evaluation filter. The purpose is to trigger RLF (radio link failure) if no measurement samples are received from the serving cell for a longer period of times.

[0027] The problem with this is that HO (handover) measurements (RRM/radio resource measurements) are not impacted same way by missing samples. Thus, according to an example implementation, if the UE is unable to obtain measurements of the serving cell, its RSRP/RSRQ value in the measurement event evaluation may, for example, essentially remain the same until new samples are obtained. This can make HOs based on A3 event delayed substantially, as even if a good RSRP is measured from neighbor cells, since the quality of serving cell remains at its earlier level. In the worst case, this delays HO so much that the radio link fails before HO is successfully started.

[0028] Thus, a problem may arise where a HO (handover) is delayed because a serving cell cannot send DRS (due to LBT). Therefore, a measurement event A3 is not triggered, at least in some cases, even though neighbor cell is actually stronger, because the serving cell RSRP is not updated due to lack of new measurement samples.

[0029] According to an example implementation, a measurement process may be performed by a user device, e.g., at a radio resource control (RRC) layer of the user device. For example, a serving cell (serving BS) may configure a user device to perform DRS (or reference signal) measurements, and may specify one or more parameters, such as an absolute threshold, an offset, and/or may indicate one or more events that may trigger a measurement report to be sent by the user device to the BS. Or, one or more of these parameters of the measurement process may be known in advance by a user device (e.g., user device may be configured with one or more parameters of the measurement process).

[0030] According to an example implementation, in order for a network to perform a handover of the user device between cells (e.g., perform a handover of the user device from a serving cell to a neighbor/target cell), the user device may (e.g., continuously or periodically) receive and measure a signal parameter of DRS (or reference) signals received from the serving cell and from one or more neighbor cells. For example, based on a measured signal parameter(s) for DRS signals received from the serving cell and/or neighbor cell(s), a user device may send a measurement report when a measurement event occurs. For example, an A3 event occurs when a signal parameter (e.g., reference signal received power/RSRP or reference signal received quality/RSRQ) measured for a neighbor cell becomes or is better than the signal parameter measured for the serving cell. Alternatively, an offset may be used for an A3 event to provide hysteresis, e.g., where an A3 event occurs when a signal parameter for a neighbor cell becomes an offset better than the signal parameter for the serving cell. Also, for example, as another example measurement event, an A4 event may occur when a signal parameter for a neighbor cell is or becomes better than an absolute threshold, where the absolute threshold may be a specific value, and is not dependent upon a signal parameter of the serving cell. Also, according to an example implementation, a recently (e.g., most recently) received signal parameter sample (e.g., a measured RSRP or measured RSRQ) may be used, or an average signal parameter (e.g., an average of the last N RSRP or RSRQ received samples) may be used to determine whether an A3 event or an A4 event has occurred. Signal samples (e.g., DRS signal samples) may include a sampled or measured value of a signal parameter (e.g., RSRP or RSRQ) as measured or determined by the user device (e.g., or one or more layers, such as a RRC layer, of a user device) based on received signals. Thus, for example, a DRS signal sample may include a sampled or measured value of signal power (e.g., RSRP) or signal quality (e.g., RSRQ) for received DRS signal(s).

[0031 ] According to an example implementation, in some cases, a user device may send a measurement report to the serving cell/serving BS when one of the measurement events (e.g., A3, A4, ..., or some other measurement event related to signal strength or quality of a cell) has been detected by the user device. The measurement report may, for example, indicate signal parameter values (e.g., RSRP and/or RSRQ) for the serving cell and/or one or more neighbor cells, and may also, for example, indicate which neighbor cell meets the A3 event or A4 event that caused the measurement report to be sent by the user device to the serving cell, for example. This is merely one example type of measurement report, and other types of measurement reports may be

sent/transmitted by the user device. Also, other measurement events may be used as well to trigger a transmission of a measurement report to the serving cell.

[0032] However, a problem may arise in this measurement process, at least in some cases, due to the use of LBT. According to an example implementation, before transmitting DRS signals, a BS or cell may be required to first sense the wireless spectrum or wireless channel. In the event that the wireless channel or portion of wireless spectrum is busy or in use by another wireless device, then the transmission of DRS signals from the cell/BS will be delayed. The BS may later sense or listen to the portion of wireless spectrum or wireless channel to determine if it is in use, or if it is idle. Eventually, the cell/BS may sense an idle wireless channel, and then will transmit the DRS signals. Thus, in some cases, a BS or cell may be delayed in transmitting DRS signals, e.g., due to LBT.

[0033] According to an example implementation, a problem may arise where, for example, a transmission of DRS signals is delayed, which may cause a handover error for a user device. Such a handover error may include, e.g., either a delayed handover or an early handover. In some cases, either of these handover errors may cause a radio link failure or interruption in wireless services for the user device. For example, at least in some cases, a delay in a transmission of DRS signals from a cell may cause the

(previously received) DRS signals from such cell to be outdated (and thus, unreliable or inaccurate). Thus, for example, such a delay in transmission of DRS signals may cause errors when a user device may determine whether an A3 event has occurred (e.g., determining whether a signal parameter for a neighbor cell becomes an offset better than the signal parameter for the serving cell). The error may result from the user device not having an accurate or updated DRS signal sample for a cell. Thus, in the case of DRS signal transmission delays (e.g., due to LBT), this may cause a user device to incorrectly determine that an A3 event has occurred, or to incorrectly determine that an A3 event has not occurred, since the user device may be missing an updated DRS signal sample(s) from a cell.

[0034] For example, handover errors that may result from delayed transmission of DRS signals may include a late or delayed handover from a serving cell to a neighbor cell or an early or erroneous handover. As an example of a late handover, a signal parameter (e.g., RSRP) from a serving cell may decrease, but such a recent decrease in RSRP from the serving cell DRS signals may be unknown to the user device due to a delay at the serving cell in transmitting DRS signals due to LBT, for example. Thus, in such a case, because a current DRS signal is not transmitted by the serving cell, no current DRS sample is received by the RRC layer of the user device. Thus, for example, in such a case of a delayed DRS signal, the user device may use a previous DRS signal sample when determining whether or not the A3 event has occurred with respect to this neighbor cell. Thus, in this example, the user device may not detect an A3 event with respect to the neighbor cell due to a failure to receive a current DRS signal sample from the serving cell. For example, the previous DRS signal sample from the serving cell may be better than the serving cell DRS signal sample (thus, not triggering A3 event measurement report transmission), whereas a current DRS signal sample from the serving cell (if it had been transmitted) would have been significantly less and thus would have caused a triggering of the A3 event measurement report from the user device. Thus, in such a situation, a delayed serving cell DRS signal sample may cause a delayed transmission of measurement report and handover of the user device to such neighbor cell (e.g., because the user device has not received the current DRS signal sample from the serving cell due to LBT delay at the serving cell). If a delay in transmitting such A3 event triggered measurement report and handover is significant, this may, at least in some cases, result in a radio link failure at the user device before a handover is performed.

[0035] Similarly, an example of an early (or erroneous) handover may occur due to LBT delays. For example, if a neighbor cell (previously providing a DRS signal sample that may meet the A3 event criteria as compared to DRS signal from serving cell), now is unable to transmit its lower signal power DRS signal sample, the user device may use a previous DRS signal sample from the neighbor cell and thus, may erroneously trigger a transmission of an A3 event measurement report to the serving cell, which may cause an early/erroneous handover of the user device to the neighbor cell. For example, if the current DRS signal sample had been sent (e.g., with significantly lower RSRP than previous DRS signal sample), this may have prevented the (early/erroneous) A3 event measurement report from being transmitted, for example. Thus, in such a case of a delayed DRS signal sample from the neighbor cell, an early or erroneous handover may be performed, at least in some cases. It may be desirable to at least decrease the handover errors that may result from LBT delays, for example.

[0036] Delayed DRS signal transmission may typically cause unreliability of the (previously received) DRS signal samples, e.g., which are now outdated. Signal samples may include, for example, a value of a signal parameter (e.g., RSRP or RSRQ) as measured or determined by the user device (e.g., RRC layer) based on received DRS signals.

[0037] Therefore, according to an example implementation, a measurement event is provided that may be triggered (e.g., causing the user device send a measurement report and/or cause or trigger a user device-initiated handover) when all of the following conditions 1) - 3) are present, by way of illustrative example:

1) the user device determines that a signal blocking condition is present with respect to a serving cell (e.g., where such signal blocking condition may prevent or delay transmission of DRS signals from the serving cell);

2) the user device determines that a signal blocking condition is not present with respect to a neighbor cell; and

3) the user device determines that a signal parameter (e.g., RSRP or RSRQ) of the neighbor cell is greater than an absolute threshold.

[0038] Thus, for example, conditions 1) - 3) above may describe a new

conditional A4 (or similar to an A4 event) type of event in which a measurement event is used that compares a signal parameter of DRS signals from a neighbor cell to an absolute threshold if both 1) a signal blocking condition is present with respect to serving cell, and 2) a signal blocking condition is not present with respect to a neighbor cell. Therefore, for example, instead of using an A3 event to trigger transmission of a measurement report (which may be unreliable due to signal blocking condition with respect to serving cell), a conditional A4 type of event may be used in the case where a signal blocking condition is present with respect to the serving cell and a signal blocking condition is not present with respect to the neighbor cell. Thus, for example, when both of these conditions 1) and 2) are present, the user device may not use an A3 event (e.g., because of the unreliability or inaccuracy of the previous DRS signal samples from the serving cell and due to delay in receiving updated DRS signal samples for serving cell), but instead may use an A4 event, which only compares the DRS signal sample parameter of the neighbor cell to an absolute value (and is not compared to the signal parameter of the serving cell, which may be considered inaccurate or unreliable due to LBT delays in this example).

[0039] Thus, in this illustrative example, the user device may measure or determine a signal parameter or DRS signal sample (e.g., determine whether a DRS signal sample or an average of DRS signal samples) for a neighbor cell is greater than an absolute threshold. In an example implementation, when the conditions 1) and 2) are present, the user device may perform an action if the signal parameter (e.g., DRS signal sample) for the neighbor cell is greater than the absolute threshold.

[0040] The evaluation of DRS blocking or DRS non-blocking condition by the user device may consider only those DRS samples obtained (or not obtained) during a configured DMTC (DRS measurement timing configuration) window. In another example the evaluation considers also the opportunistic DRS transmissions outside the DMTC window. This may lead the user device, for example, not consider the DRS blocking condition to hold if there have been successful opportunistic DRS transmissions even though there have not been any recent successful DRS transmissions within the DMTC window(s). Same rule may be used for both serving cell and neighbor cells, or in some cases different rule may be applied; for example, the serving cell DRS blocking condition evaluation may consider also opportunistic DRS transmissions whereas neighbor cell DRS blocking condition is considering only DRS transmissions within DTMC window.

[0041 ] The action that may be performed by the user device if conditions 1) - 3) are present may include, for example: 1) sending a measurement report to the serving cell (e.g., an A4 event triggered measurement report transmitted to the serving cell that indicates/suggests a handover of the user device to the neighbor cell); and/or 2) performing a user device-initiated handover to the neighbor cell or sending a message to the neighbor cell to request a user device-initiated handover to the neighbor cell.

[0042] Therefore, in the case where both 1) a signal blocking condition is present for the serving cell and a where a signal blocking condition is not present with respect to the neighbor cell, an A4 event may be used/analyzed by the user device to determine whether to perform an action (e.g., send measurement report and/or perform handover). Thus, in this manner, the user device may avoid using the relative signal parameter (e.g., RSRP or RSRQ) of the serving cell for an A3 event (which may be deemed unreliable in the case where a DRS signal blocking condition from serving cell is detected).

Therefore, an A4 event may be used, which may only compare the DRS signal parameter of the neighbor cell to an absolute threshold, e.g., in the case where a signal blocking condition is detected with respect to the serving cell (e.g., serving cell signal is now unreliable due to blocking condition) and there is no signal blocking condition detected with respect to the neighbor cell (e.g., the neighbor cell signal is reliable and may be used for triggering transmission of measurement report or initiating a handover).

[0043] As noted, the action performed by a user device in this example case (e.g., in which conditions 1) - 3) are present) may include: 1) sending a measurement report to the serving cell, and/or 2) sending a message from the user device to the neighbor cell to initiate an autonomous handover , which may be a user device-initiated handover to the neighbor cell (e.g., without waiting for a handover command from the serving cell, and/or without waiting for expiration of a handover timer). In an example implementation, the signal blocking condition with respect to the serving cell may mean, at least in some cases, that a measurement report (e.g., indicating HO to neighbor cell) that is triggered for transmission from user device to serving cell may be delayed in transmission or not transmitted and/or any subsequent handover command from the serving cell may be delayed. Such delay in sending the measurement report to the serving cell and/or any delay in receiving a handover command from the serving cell may cause a delay in the user device receiving a handover command from the serving cell, thus delaying any handover of the user device to the neighbor cell This delay may, at least in some cases, cause a radio link failure or interruption in wireless services for the user device. Thus, according to an example implementation, rather than waiting for a handover command from the network device (based on network- initiated handover in response to the measurement report sent to serving cell), the user device may initiate a user device- initiated handover by sending a message (e.g., handover request or connection (re- )establishment request) to the neighbor cell. In this manner, in the case of a signal blocking condition with respect to the serving cell (and where no such signal blocking condition is present with respect to the neighbor cell), a more reliable measurement event may be used by the user device (e.g., using the A4 type event with respect to an absolute threshold) and/or a more reliable handover may be performed by the user device (e.g., by using or triggering an autonomous handover or user device-initiated handover to the neighbor cell, e.g., without relying on or waiting on a handover command from the serving cell, which is blocked or delayed).

[0044] Thus, one or more example implementations described herein may, at least in some cases, provide a number of example advantages, such as, e.g.: 1) supporting improved mobility robustness, 2) reducing handover errors and/or reducing interruption of wireless services, e.g., due to LBT delays, and/or 3) allowing improved transmission of measurement reports and/or provide a faster and/or more reliable handover of a user device in the event of a signal blocking condition with respect to the serving cell and/or neighbor cell (e.g., which may be due to LBT delays).

[0045] Various conditions or criteria may be used to determine whether a signal blocking condition (e.g., LBT causes transmission of DRS signals to be blocked or delayed) is present with respect to a cell. According to an example implementation, by way of illustrative example, determining by the user device that a signal blocking condition is present with respect to a serving cell may include, for example, the user device determining at least one of the following: 1) the user device has not obtained a discovery reference signal sample from the serving cell during a first threshold period of time (e.g., more than X ms since the last received DRS signal sample); 2) the user device has missed or not obtained at least a second threshold number of consecutive discovery reference signal samples from the serving cell (e.g., the user device has missed (not received) the last 4 consecutive DRS signal samples; and 3) the user device has missed or not obtained at least a third threshold number of discovery reference signal samples from the serving cell within a period of time (e.g., user device has missed (or not received) 5 DRS signal samples within a window of the last 120 ms). These are merely some examples and other examples may be used.

[0046] Similarly, various conditions or criteria may be used to determine whether a signal blocking condition is not present with respect to a cell. According to an example implementation, by way of illustrative example, determining by the user device that a signal blocking condition is not present with respect to a neighbor cell may include the user device determining at least one of the following: 1) the user device has obtained a discovery reference signal sample from the serving cell during a first threshold period of time (e.g., at least one DRS signal sample received within the last 50 ms); 2) the user device has not missed at least a second threshold number of consecutive discovery reference signal samples from the serving cell (e.g.,. user device has not missed at least 4 consecutive DRS signal samples); and 3) the user device has not missed at least a third threshold number of discovery reference signal samples from the serving cell within a period of time (e.g., user device has not missed at least 5 DRS signal samples within a window of the last 120 ms). These are merely some illustrative examples and other examples may be used.

[0047] A same set of criteria may be used for determining both 1) presence of a blocking condition for a serving cell and 2) a blocking condition is not present with respect to a neighbor cell. Alternatively, one or more different criteria may be used, e.g., 1) a first set of criteria (or conditions) may be used for the user device to determine a presence (or non-presence) of a blocking condition for a serving cell and 2) a second set of conditions or criteria may be used to determine that a blocking condition is present or not present with respect to a neighbor cell. [0048] According to an example implementation, multiple measurement events may be used, and a user device may use a presence or absence of a signal blocking condition with respect to the serving cell and/or a neighbor cell to determine which measurement event will be used to trigger an action by the user device (such as sending a measurement report and/or sending a message to perform user device-initiated handover). According to an example implementation, a first measurement event (e.g., an A4 event, in which the user device compares the DRS signal parameter of the neighbor cell to an absolute threshold) may be used by the user device if a signal blocking condition is present with respect to the serving cell, and a second measurement event (e.g., an A3 event, in which the user device compares the DRS signal parameter of the neighbor cell to a DRS signal parameter of the serving cell) may be used by the user device if a signal blocking condition is not present with respect to the serving cell.

[0049] FIG. 2 is a flow chart illustrating operation of a user device according to an example implementation. The flow chart begins at 210. At 212, the user device may wait until a next measurement event evaluation. At 214, the user device may determine whether or not the serving cell is blocked (e.g., determine whether or not a signal blocking condition is present with respect to the serving cell). If the serving cell is blocked, the flow proceeds to operation 216. At 216, the user device determines whether or not a neighbor cell is blocked (e.g., determines whether or not a signal blocking condition is present with respect to the neighbor cell). If the neighbor cell is not blocked, then at 218, an A4 type measurement event is applied, where the user device determines whether a neighbor cell signal (e.g., RSRP or RSRQ) is better than an absolute threshold. If the neighbor cell signal is better than the absolute threshold, then, at 222, the user device may transmit a measurement report to the serving cell. Also, if the neighbor cell signal is better than the absolute threshold, then, at 220, the user device may initiate an autonomous handover to the neighbor cell or perform a user device-initiated handover to the neighbor cell.

[0050] At 214, if the serving cell is not blocked, then flow will proceed to 230. Although not shown, an optional operation may be provided between operations 214 and 230 in which the user device may confirm that the neighbor cell is not blocked (e.g., user device may confirm that a signal blocking condition is not present with respect to the neighbor cell), before proceeding to operation 230. At operation 230, an A3 type measurement event is applied in which the user device determines if the neighbor cell DRS signal is an offset better than the serving cell signal measurement. If the neighbor cell signal is better than the absolute threshold, then, at 232, the user device transmits a measurement report to the serving cell.

[0051 ] Example 1. FIG. 3 is a flow chart illustrating operation of a user device according to an example implementation. Operation 310 includes determining, by a user device in a wireless network, that a signal blocking condition is present with respect to a serving cell. Operation 320 includes determining, by the user device, that a signal blocking condition is not present with respect to a neighbor cell. Operation 330 includes determining that a signal parameter for the neighbor cell is greater than an absolute threshold. Operation 340 includes performing, by the user device, an action in response to determining that both the signal blocking condition is present with respect to the serving cell and the signal blocking condition is not present with respect to the neighbor cell and the signal parameter for the neighbor cell is greater than an absolute threshold, the action including at least one of the following: sending a measurement report to the serving cell; and sending a message to the neighbor cell to trigger a handover of the user device to the neighbor cell.

[0052] Example 2. According to an example implementation of the method of example 1, wherein the determining, by the user device that the signal blocking condition is present with respect to a serving cell comprises the user device determining at least one of the following: the user device has not obtained a discovery reference signal sample from the serving cell during a first threshold period of time; the user device has missed or not obtained at least a second threshold number of consecutive discovery reference signal samples from the serving cell; and the user device has missed or not obtained at least a third threshold number of discovery reference signal samples from the serving cell within a period of time.

[0053] Example 3. According to an example implementation of the method of any of examples 1-2, wherein the determining, by the user device, that the signal blocking condition is not present with respect to the neighbor cell comprises the user device determining at least one of the following: the user device has obtained a discovery reference signal sample from the serving cell during a first threshold period of time; the user device has not missed at least a second threshold number of consecutive discovery reference signal samples from the serving cell; and the user device has not missed at least a third threshold number of discovery reference signal samples from the serving cell within a period of time.

[0054] Example 4. According to an example implementation of the method of any of examples 1-3, wherein the sending a message to the neighbor cell to trigger a handover of the user device to the neighbor cell comprises: sending a message to the neighbor cell to trigger a user device-initiated handover of the user device to the neighbor cell, before receiving a handover command from the serving cell, if a signal power or signal quality for the neighbor cell is greater than an absolute threshold.

[0055] Example 5. According to an example implementation, an apparatus includes means for performing the method of any of examples 1-4.

[0056] Example 6. According to an example implementation, an apparatus includes at least one processor and at least one memory including computer instructions, when executed by the at least one processor, cause the apparatus to perform the method of any of examples 1-4.

[0057] Example 7. According to an example implementation, an apparatus comprises at least one processor and at least one memory including computer

instructions, when executed by the at least one processor, cause the apparatus to:

determine, by a user device in a wireless network, that a signal blocking condition is present with respect to a serving cell; determine, by the user device, that a signal blocking condition is not present with respect to a neighbor cell; determine that a signal parameter for the neighbor cell is greater than an absolute threshold; perform, by the user device, an action in response to determining that both the signal blocking condition is present with respect to the serving cell and the signal blocking condition is not present with respect to the neighbor cell and the signal parameter for the neighbor cell is greater than an absolute threshold, the action including at least one of the following: send a measurement report to the serving cell; and send a message to the neighbor cell to trigger a handover of the user device to the neighbor cell.

[0058] Example 8. FIG. 4 is a flow chart illustrating operation of a user device according to an example implementation. Operation 410 includes determining, by a user device in a wireless network, whether or not a signal blocking condition is present with respect to a serving cell. Operation 420 includes determining, by the user device, whether or not a signal blocking condition is present with respect to a neighbor cell. Operation 430 includes sending, by the user device, a measurement report to the serving cell if both the signal blocking condition is present with respect to the serving cell and the signal blocking condition is not present with respect to the neighbor cell, and if a signal parameter for the neighbor cell is greater than an absolute threshold. And, operation 440 includes sending, by the user device, a measurement report to the serving cell if the signal blocking condition is not present with respect to the serving cell and if a signal parameter for the neighbor cell is greater than a signal parameter for the serving cell.

[0059] Example 9. According to an example implementation of the method of example 8, wherein the signal parameter comprises at least one of: a signal power or reference signal received power (RSRP); and a signal quality or a reference signal received quality (RSRQ).

[0060] Example 10. According to an example implementation of the method of any of examples 8-9, wherein the determining, by the user device whether or not a signal blocking condition is present with respect to a serving cell comprises the user device determining that a signal blocking condition is present with respect to the serving cell based on at least one of the following: the user device has not obtained a discovery reference signal sample from the serving cell during a first threshold period of time; the user device has missed or not obtained at least a second threshold number of consecutive discovery reference signal samples from the serving cell; and the user device has missed or not obtained at least a third threshold number of discovery reference signal samples from the serving cell within a period of time.

[0061 ] Example 11. According to an example implementation of the method of any of examples 8-10, wherein the determining, by the user device, whether or not the signal blocking condition is present with respect to the neighbor cell comprises the user device determining that a signal blocking condition is not present with respect to the neighbor cell based on at least one of the following: the user device has obtained a discovery reference signal sample from the serving cell during a first threshold period of time; the user device has not missed at least a second threshold number of consecutive discovery reference signal samples from the serving cell; and the user device has not missed at least a third threshold number of discovery reference signal samples from the serving cell within a period of time.

[0062] Example 12. According to an example implementation of the method of any of examples 8-11, and further comprising: sending a message, by the user device to the neighbor cell, to trigger a user device-initiated handover to the neighbor cell, if both the signal blocking condition is present with respect to the serving cell and the signal blocking condition is not present with respect to the neighbor cell, and if the signal parameter for the neighbor cell is greater than the absolute threshold.

[0063] Example 13. According to an example implementation of the method of any of examples 8-12, wherein the sending, by the user device, a measurement report to the serving cell if the signal blocking condition is not present with respect to the serving cell comprises: sending, by the user device, a measurement report to the serving cell if both a signal blocking condition is not present with respect to the serving cell and a signal blocking condition is not present with respect to the neighbor cell, and if a signal parameter for the neighbor cell is an offset greater than a signal parameter for the serving cell.

[0064] Example 14. According to an example implementation, an apparatus includes means for performing the method any of examples 8-13.

[0065] Example 15. According to an example implementation, an apparatus includes at least one processor and at least one memory including computer instructions, when executed by the at least one processor, cause the apparatus to perform the method of any of examples 8-13.

[0066] Example 16. According to an example implementation, an apparatus includes at least one processor and at least one memory including computer instructions, when executed by the at least one processor, cause the apparatus to: determine, by a user device in a wireless network, whether or not a signal blocking condition is present with respect to a serving cell; determine, by the user device, whether or not a signal blocking condition is present with respect to a neighbor cell; send, by the user device, a

measurement report to the serving cell if both the signal blocking condition is present with respect to the serving cell and the signal blocking condition is not present with respect to the neighbor cell, and if a signal parameter for the neighbor cell is greater than an absolute threshold; and send, by the user device, a measurement report to the serving cell if the signal blocking condition is not present with respect to the serving cell and if a signal parameter for the neighbor cell is greater than a signal parameter for the serving cell.

[0067] FIG. 5 is a block diagram of a wireless station (e.g., AP, BS, eNB, UE or user device, or other network device or wireless device) 1000 according to an example implementation. The wireless station 1000 may include, for example, one or two RF (radio frequency) or wireless transceivers 1002A, 1002B, where each wireless transceiver includes a transmitter to transmit signals and a receiver to receive signals. The wireless station also includes a processor or control unit/entity (controller) 1004 to execute instructions or software and control transmission and receptions of signals, and a memory 1006 to store data and/or instructions.

[0068] Processor 1004 may also make decisions or determinations, generate frames, packets or messages for transmission, decode received frames or messages for further processing, and other tasks or functions described herein. Processor 1004, which may be a baseband processor, for example, may generate messages, packets, frames or other signals for transmission via wireless transceiver 1002 (1002A or 1002B). Processor 1004 may control transmission of signals or messages over a wireless network, and may control the reception of signals or messages, etc., via a wireless network (e.g., after being down-converted by wireless transceiver 1002, for example). Processor 1004 may be programmable and capable of executing software or other instructions stored in memory or on other computer media to perform the various tasks and functions described above, such as one or more of the tasks or methods described above. Processor 1004 may be (or may include), for example, hardware, programmable logic, a programmable processor that executes software or firmware, and/or any combination of these. Using other terminology, processor 1004 and transceiver 1002 together may be considered as a wireless transmitter/receiver system, for example.

[0069] In addition, referring to FIG. 5, a controller (or processor) 1008 may execute software and instructions, and may provide overall control for the station 1000, and may provide control for other systems not shown in FIG. 5, such as controlling input/output devices (e.g., display, keypad), and/or may execute software for one or more applications that may be provided on wireless station 1000, such as, for example, an email program, audio/video applications, a word processor, a Voice over IP application, or other application or software.

[0070] In addition, a storage medium may be provided that includes stored instructions, which when executed by a controller or processor may result in the processor 1004, or other controller or processor, performing one or more of the functions or tasks described above.

[0071 ] According to another example implementation, RF or wireless transceiver(s) 1002A/1002B may receive signals or data and/or transmit or send signals or data. Processor 1004 (and possibly transceivers 1002A/1002B) may control the RF or wireless transceiver 1002A or 1002B to receive, send, broadcast or transmit signals or data.

[0072] The embodiments are not, however, restricted to the system that is given as an example, but a person skilled in the art may apply the solution to other

communication systems. Another example of a suitable communications system is the 5G concept. It is assumed that network architecture in 5G will be quite similar to that of the LTE-advanced. 5G is likely to use multiple input - multiple output (MIMO) antennas, many more base stations or nodes than the LTE (a so-called small cell concept), including macro sites operating in co-operation with smaller stations and perhaps also employing a variety of radio technologies for better coverage and enhanced data rates.

[0073] It should be appreciated that future networks will most probably utilise network functions virtualization (NFV) which is a network architecture concept that proposes virtualizing network node functions into "building blocks" or entities that may be operationally connected or linked together to provide services. A virtualized network function (VNF) may comprise one or more virtual machines running computer program codes using standard or general type servers instead of customized hardware. Cloud computing or data storage may also be utilized. In radio communications this may mean node operations may be carried out, at least partly, in a server, host or node operationally coupled to a remote radio head. It is also possible that node operations will be distributed among a plurality of servers, nodes or hosts. It should also be understood that the distribution of labour between core network operations and base station operations may differ from that of the LTE or even be non-existent.

[0074] Implementations of the various techniques described herein may be implemented in digital electronic circuitry, or in computer hardware, firmware, software, or in combinations of them. Implementations may implemented as a computer program product, i.e., a computer program tangibly embodied in an information carrier, e.g., in a machine-readable storage device or in a propagated signal, for execution by, or to control the operation of, a data processing apparatus, e.g., a programmable processor, a computer, or multiple computers. Implementations may also be provided on a computer readable medium or computer readable storage medium, which may be a non-transitory medium. Implementations of the various techniques may also include implementations provided via transitory signals or media, and/or programs and/or software

implementations that are downloadable via the Internet or other network(s), either wired networks and/or wireless networks. In addition, implementations may be provided via machine type communications (MTC), and also via an Internet of Things (IOT).

[0075] The computer program may be in source code form, object code form, or in some intermediate form, and it may be stored in some sort of carrier, distribution medium, or computer readable medium, which may be any entity or device capable of carrying the program. Such carriers include a record medium, computer memory, readonly memory, photoelectrical and/or electrical carrier signal, telecommunications signal, and software distribution package, for example. Depending on the processing power needed, the computer program may be executed in a single electronic digital computer or it may be distributed amongst a number of computers.

[0076] Furthermore, implementations of the various techniques described herein may use a cyber-physical system (CPS) (a system of collaborating computational elements controlling physical entities). CPS may enable the implementation and exploitation of massive amounts of interconnected ICT devices (sensors, actuators, processors microcontrollers,...) embedded in physical objects at different locations. Mobile cyber physical systems, in which the physical system in question has inherent mobility, are a subcategory of cyber-physical systems. Examples of mobile physical systems include mobile robotics and electronics transported by humans or animals. The rise in popularity of smartphones has increased interest in the area of mobile cyber- physical systems. Therefore, various implementations of techniques described herein may be provided via one or more of these technologies.

[0077] A computer program, such as the computer program(s) described above, can be written in any form of programming language, including compiled or interpreted languages, and can be deployed in any form, including as a stand-alone program or as a module, component, subroutine, or other unit or part of it suitable for use in a computing environment. A computer program can be deployed to be executed on one computer or on multiple computers at one site or distributed across multiple sites and interconnected by a communication network.

[0078] Method steps may be performed by one or more programmable processors executing a computer program or computer program portions to perform functions by operating on input data and generating output. Method steps also may be performed by, and an apparatus may be implemented as, special purpose logic circuitry, e.g., an FPGA (field programmable gate array) or an ASIC (application-specific integrated circuit).

[0079] Processors suitable for the execution of a computer program include, by way of example, both general and special purpose microprocessors, and any one or more processors of any kind of digital computer, chip or chipset. Generally, a processor will receive instructions and data from a read-only memory or a random access memory or both. Elements of a computer may include at least one processor for executing instructions and one or more memory devices for storing instructions and data. Generally, a computer also may include, or be operatively coupled to receive data from or transfer data to, or both, one or more mass storage devices for storing data, e.g., magnetic, magneto-optical disks, or optical disks. Information carriers suitable for embodying computer program instructions and data include all forms of non- volatile memory, including by way of example semiconductor memory devices, e.g., EPROM, EEPROM, and flash memory devices; magnetic disks, e.g., internal hard disks or removable disks; magneto-optical disks; and CD-ROM and DVD-ROM disks. The processor and the memory may be supplemented by, or incorporated in, special purpose logic circuitry.

[0080] To provide for interaction with a user, implementations may be implemented on a computer having a display device, e.g., a cathode ray tube (CRT) or liquid crystal display (LCD) monitor, for displaying information to the user and a user interface, such as a keyboard and a pointing device, e.g., a mouse or a trackball, by which the user can provide input to the computer. Other kinds of devices can be used to provide for interaction with a user as well; for example, feedback provided to the user can be any form of sensory feedback, e.g., visual feedback, auditory feedback, or tactile feedback; and input from the user can be received in any form, including acoustic, speech, or tactile input.

[0081 ] Implementations may be implemented in a computing system that includes a back-end component, e.g., as a data server, or that includes a middleware component, e.g., an application server, or that includes a front-end component, e.g., a client computer having a graphical user interface or a Web browser through which a user can interact with an implementation, or any combination of such back-end, middleware, or front-end components. Components may be interconnected by any form or medium of digital data communication, e.g., a communication network. Examples of communication networks include a local area network (LAN) and a wide area network (WAN), e.g., the Internet.

[0082] While certain features of the described implementations have been illustrated as described herein, many modifications, substitutions, changes and

equivalents will now occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the various embodiments.

Claims

WHAT IS CLAIMED IS:

1. A method comprising:

determining, by a user device in a wireless network, that a signal blocking condition is present with respect to a serving cell;

determining, by the user device, that a signal blocking condition is not present with respect to a neighbor cell;

determining that a signal parameter for the neighbor cell is greater than an absolute threshold; and

performing, by the user device, an action in response to determining that both the signal blocking condition is present with respect to the serving cell and the signal blocking condition is not present with respect to the neighbor cell and the signal parameter for the neighbor cell is greater than an absolute threshold, the action including at least one of the following:

sending a measurement report to the serving cell; and

sending a message to the neighbor cell to trigger a handover of the user device to the neighbor cell.

2. The method of claim 1 wherein the determining, by the user device that the signal blocking condition is present with respect to a serving cell comprises the user device determining at least one of the following:

the user device has not obtained a discovery reference signal sample from the serving cell during a first threshold period of time;

the user device has missed or not obtained at least a second threshold number of consecutive discovery reference signal samples from the serving cell; and

the user device has missed or not obtained at least a third threshold number of discovery reference signal samples from the serving cell within a period of time.

3. The method of any of claims 1-2 wherein the determining, by the user device, that the signal blocking condition is not present with respect to the neighbor cell comprises the user device determining at least one of the following: the user device has obtained a discovery reference signal sample from the serving cell during a first threshold period of time;

the user device has not missed at least a second threshold number of consecutive discovery reference signal samples from the serving cell; and

the user device has not missed at least a third threshold number of discovery reference signal samples from the serving cell within a period of time.

4. The method of any of claims 1-3 wherein the sending a message to the neighbor cell to trigger a handover of the user device to the neighbor cell comprises:

sending a message to the neighbor cell to trigger a user device-initiated handover of the user device to the neighbor cell, before receiving a handover command from the serving cell, if a signal power or signal quality for the neighbor cell is greater than an absolute threshold.

5. An apparatus comprising means for performing the method any of claims 1-4.

6. An apparatus comprising at least one processor and at least one memory including computer instructions, when executed by the at least one processor, cause the apparatus to perform the method of any of claims 1-4.

7. An apparatus comprises at least one processor and at least one memory including computer instructions, when executed by the at least one processor, cause the apparatus to:

determine, by a user device in a wireless network, that a signal blocking condition is present with respect to a serving cell;

determine, by the user device, that a signal blocking condition is not present with respect to a neighbor cell;

determine that a signal parameter for the neighbor cell is greater than an absolute threshold;

perform, by the user device, an action in response to determining that both the signal blocking condition is present with respect to the serving cell and the signal blocking condition is not present with respect to the neighbor cell and the signal parameter for the neighbor cell is greater than an absolute threshold, the action including at least one of the following:

send a measurement report to the serving cell; and

send a message to the neighbor cell to trigger a handover of the user device to the neighbor cell.

8. A method comprising:

determining, by a user device in a wireless network, whether or not a signal blocking condition is present with respect to a serving cell;

determining, by the user device, whether or not a signal blocking condition is present with respect to a neighbor cell;

sending, by the user device, a measurement report to the serving cell if both the signal blocking condition is present with respect to the serving cell and the signal blocking condition is not present with respect to the neighbor cell, and if a signal parameter for the neighbor cell is greater than an absolute threshold; and

sending, by the user device, a measurement report to the serving cell if the signal blocking condition is not present with respect to the serving cell and if a signal parameter for the neighbor cell is greater than a signal parameter for the serving cell.

9. The method of claim 8 wherein the signal parameter comprises at least one of:

a signal power or reference signal received power (RSRP); and

a signal quality or a reference signal received quality (RSRQ).

10. The method of any of claims 8-9 wherein the determining, by the user device whether or not a signal blocking condition is present with respect to a serving cell comprises the user device determining that a signal blocking condition is present with respect to the serving cell based on at least one of the following:

11. The method of any of claims 8-10 wherein the determining, by the user device, whether or not the signal blocking condition is present with respect to the neighbor cell comprises the user device determining that a signal blocking condition is not present with respect to the neighbor cell based on at least one of the following:

the user device has obtained a discovery reference signal sample from the serving cell during a first threshold period of time;

12. The method of any of claims 8-11 and further comprising:

sending a message, by the user device to the neighbor cell, to trigger a user device-initiated handover to the neighbor cell, if both the signal blocking condition is present with respect to the serving cell and the signal blocking condition is not present with respect to the neighbor cell, and if the signal parameter for the neighbor cell is greater than the absolute threshold.

13. The method of any of claims 8-12 wherein the sending, by the user device, a measurement report to the serving cell if the signal blocking condition is not present with respect to the serving cell comprises:

sending, by the user device, a measurement report to the serving cell if both a signal blocking condition is not present with respect to the serving cell and a signal blocking condition is not present with respect to the neighbor cell, and if a signal parameter for the neighbor cell is an offset greater than a signal parameter for the serving cell. An apparatus comprising means for performing the method any of claims

15. An apparatus comprising at least one processor and at least one memory including computer instructions, when executed by the at least one processor, cause the apparatus to perform the method of any of claims 8-13.

16. An apparatus comprises at least one processor and at least one memory including computer instructions, when executed by the at least one processor, cause the apparatus to:

determine, by a user device in a wireless network, whether or not a signal blocking condition is present with respect to a serving cell;

determine, by the user device, whether or not a signal blocking condition is present with respect to a neighbor cell;

send, by the user device, a measurement report to the serving cell if both the signal blocking condition is present with respect to the serving cell and the signal blocking condition is not present with respect to the neighbor cell, and if a signal parameter for the neighbor cell is greater than an absolute threshold; and

send, by the user device, a measurement report to the serving cell if the signal blocking condition is not present with respect to the serving cell and if a signal parameter for the neighbor cell is greater than a signal parameter for the serving cell.