Patent Description:
Procedures for handover of a user equipment (UE) from a first base station to a second base station are known. The Third Generation Partnership Program (3GPP) has proposed coverage enhancement (CE) for Machine Type Communications (MTC) in LTE. 3GPP standards include CE levels and CE level criteria.

<CIT> describes a technique comprising a user equipment selecting a PRACH preamble based on a determined coverage enhancement category for the user equipment. <CIT> describes a technique comprising executing a random access to a target cell using random access information relating to the coverage level of the target cell. <CIT> describes a technique for enhancing coverage of machine type communication devices. <CIT> describes a technique for providing mobility support for enhanced coverage of wireless devices.

There is hereby provided a user equipment according to claim <NUM>, a method according to claim <NUM>, a non-transitory program storage device according to claim <NUM>, a target base station according to claim <NUM>, a method according to claim <NUM>, and a non-transitory program storage device according to claim <NUM>.

<FIG> shows an example of overall architecture of an E-UTRAN system. The E-UTRAN system includes eNBs, providing an E-UTRAN user plane (PDCP/RLC/MAC/PHY) and control plane (RRC) protocol terminations towards the UE (not shown in <FIG>). The eNBs are interconnected with each other by means of an X2 interface. The eNBs are also connected by means of a S1 interface to an EPC (Enhanced Packet Core), more specifically to a MME (Mobility Management Entity) by means of a S1 MME interface and to a Serving Gateway (S-GW) by means of a S1 interface. The S1 interface supports a many-to-many relationship between MMEs/S-GW and eNBs. One or more of the eNB may form an access point (AP) or base station.

Referring also to <FIG>, a user equipment (UE) <NUM> is shown. In this example the UE <NUM> is a smartphone. However, in alternate examples the UE may be, for example, a tablet computer, a PDA, a smart watch, or any other suitable device configured for wireless communications including, for example, in a vehicle such as a car. The UE <NUM> is configured to be able to communicate with the base stations (BS) <NUM>, <NUM>, <NUM>.

The wireless system <NUM> comprise a wireless network <NUM> adapted for communication over a wireless link <NUM> with an apparatus, such as the mobile communication device which may be referred to as a UE <NUM>, via the eNB <NUM>. The network <NUM> may include a network control element (NCE) <NUM> that may include MME/S-GW functionality, and which provides connectivity with a network, such as a telephone network and/or a data communications network (e.g., the internet <NUM>).

The UE <NUM> includes a controller, such as a computer or a data processor (DP) <NUM>, a computer-readable memory medium embodied as a memory (MEM) <NUM> that stores a program of computer instructions (PROG) <NUM>, and a suitable wireless interface, such as radio frequency (RF) transceiver <NUM>, for bidirectional wireless communications with the eNB <NUM> via one or more antennas.

The eNB <NUM> also includes a controller, such as a computer or a data processor (DP) <NUM>, a computer-readable memory medium embodied as a memory (MEM) <NUM> that stores a program of computer instructions (PROG) <NUM>, and a suitable wireless interface, such as RF transceiver <NUM>, for communication with the UE <NUM> via one or more antennas. The eNB <NUM> is coupled via a data/control path <NUM> to the NCE <NUM>. The path <NUM> may be implemented as an interface. The eNB <NUM> may also be coupled to other eNB(s) via data/control path <NUM> also known as the X2 interface.

The NCE <NUM> includes a controller, such as a computer or a data processor (DP) <NUM>, a computer-readable memory medium embodied as a memory (MEM) <NUM> that stores a program of computer instructions (PROG) <NUM>.

At least one of the PROGs <NUM>, <NUM> and <NUM> is assumed to include program instructions that, when executed by the associated DP, enable the device to operate in accordance with exemplary embodiments of this invention, as will be discussed below in greater detail. That is, various exemplary embodiments of this invention may be implemented at least in part by computer software executable by the DP <NUM> of the UE <NUM>; by the DP <NUM> of the eNB <NUM>; and/or by the DP <NUM> of the NCE <NUM>, or by hardware, or by a combination of software and hardware (and firmware).

For the purposes of describing various exemplary embodiments in accordance with this invention the UE <NUM> and the eNB <NUM> may also include dedicated processors, for example RRC module <NUM> and a corresponding RRC module <NUM>. RRC module <NUM> and RRC module <NUM> may be constructed so as to operate in accordance with various exemplary embodiments in accordance with this invention.

The computer readable MEMs <NUM>, <NUM> and <NUM> may be of any type suitable to the local technical environment and may be implemented using any suitable data storage technology, such as semiconductor based memory devices, flash memory, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory. The DPs <NUM>, <NUM> and <NUM> may be of any type suitable to the local technical environment, and may include one or more of general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs) and processors based on a multicore processor architecture, as non-limiting examples. The wireless interfaces (e.g., RF transceivers <NUM> and <NUM>) may be of any type suitable to the local technical environment and may be implemented using any suitable communication technology such as individual transmitters, receivers, transceivers or a combination of such components.

Extending LTE coverage from a normal coverage mode (i.e., a non-CE mode) to a coverage enhancement (CE) mode allows LTE to be used for services such as smart metering, where the meters may be installed in basements or shielded locations, and thus may be subject to substantial penetration loss. MTC devices are sometimes referred to as low-cost or low-complexity devices because they do not require all the hardware and programming a non-MTC device may have. A low cost MTC device may suffer from coverage degradation due to some restrictions, e.g. the reduced bandwidth and the single RX, etc. However, devices which use a coverage enhancement (CE) mode rather than a normal coverage mode of communication are envisioned which may be mobile and, therefore, will need a handover capability. Thus, mobility support for "Low Complexity/Enhanced Coverage" (LC/EC) UEs will be needed.

Low power consumption and low cost are important aspects for large-scale deployment of CE capable devices. To provide sufficient coverage of MTC devices, or MTC user equipments (UEs), special coverage enhancement (CE) considerations may be needed. These coverage enhancements may include a desired coverage enhancement level for various physical channels of communication. For example, in some instances physical uplink channels and physical downlink channels such as, for example, physical downlink control channel (PDCCH), physical uplink shared channel (PUSCH), etc. may be configured to achieve a desired coverage enhancement level, or decibel (dB) gain in signal power. A required CE level can be different for different eNBs, for example depending on an eNB transmission power or an associated cell size, as well as for different UEs, for example depending on a location of a UE or on a number of UE receiver antennas.

Features as described herein provide an improvement to exchange of information over an X2 interface for supporting a reliable handover procedure for a 3GPP low-cost (low complexity) UE and a UE in a coverage enhancement mode, such as for 3GPP Rel-<NUM> for example.

During a X2 interface setup procedure (or during a X2 interface update procedure), a source eNB and a target eNB may exchange information about their capabilities, such as, for example:.

Such information may be used by the source eNB to decide potential coverage status in a target eNB, configure CE-specific measurement configurations and decide the CE level in the target eNB based on a measurement result from the UE. This also helps the source eNB to make handover decisions when preparing a handover towards multiple target cells with different CE conditions.

During the Handover procedure an additional flag indicating whether the UE will work in a CE mode or/and the CE level of the UE may be added in a Handover Request message by the source eNB. The configuration of Random Access (RA) procedure (including CE related Physical Random Access Channel (PRACH) resources) towards the target eNB may be added by the target eNB in a Handover Request Acknowledge as part of a RRC container. PRACH resource information may include, for example, time, frequency and preamble related information. As different sets of PRACH resources (e.g. time, frequency and preamble) are associated with each EC level, and also the PRACH resource for EC UEs is separated from the normal coverage UEs, that information could enable the target eNB to allocate the RA resource reflecting the practical UE coverage situation in the target eNB correctly; to ensure a successful RA procedure towards the target eNB during the handover procedure. Please note that any combination of above may be considered. Alternatively, instead of signaling the CE level criteria (i.e. the threshold(s) to decide the CE level based on the measurement result), the measurement results from the UE can be included in the Handover Request message; allowing the target eNB to decide the CE level of the UE. PRACH resources may be assigned per CE level and/or PRACH resources may be assigned per "UE type" (such as low-cost UE versus non-low-cost UE for example).

Referring also to <FIG>, an example will be described. At Step <NUM>, during the X2 setup or update procedure, the source eNB <NUM> and the target eNB <NUM> exchange at least one of:.

At Step <NUM> the UE triggers a measurement report sent to the source eNB <NUM>. At Step <NUM> the source eNB <NUM> makes a decision based upon the received MEASUREMENT REPORT and the CE configuration of the cells of the neighbouring base stations <NUM>, <NUM> exchanged during the X2 setup/update procedure. The source eNB <NUM> detects the UE's CE level for the neighboring cells according to the cell specific CE level criteria. The source eNB <NUM> may select the suitable target eNB based on the CE level, such as:.

At Step <NUM> when the source eNB <NUM> determines that the CE level for the UE in the target eNB would be better than that in the source cell, the source eNB <NUM> decides to prepare handover. A one bit EC indicator or the EC level indicator may be added in the Handover Request. The source eNB <NUM> may provide the measurement result to the target eNB <NUM>. The target eNB <NUM> may then use that measurement result to decide the UE's CE level.

At Step <NUM> the target eNB may add the CE related physical random access channel (PRACH) resources in the Handover Request Acknowledge as part of the RRC container. This may include the PRACH resource allocated for UE operating in normal coverage, and the PRACH resource associated with the UE specific EC level in the target cell. The PRACH resource may include the time/frequency allocation and dedicated preambles. Either all PRACH resource associated with all possible CE levels may be added or only the PRACH resource corresponding to the estimated CE of the incoming UE might be added.

At Steps <NUM>-<NUM> the handover procedure in the air interface is performed. The UE accesses the target cell with the RA procedure using the assigned PRACH resources associated with its CE level in the target cell; contained in the RRC Connection Reconfiguration message. The PRACH resource may include the time/frequency allocation and dedicated preambles. According to the PRACH resource, the target eNB is aware of the UE in the EC mode, and the CE level which could be applied for resource scheduling.

In <FIG>, step <NUM> (which corresponds to the target eNB <NUM> being aware of the UE's CE level) is shown occurring after step <NUM> (after the UE <NUM> transmitting the PRACH preamble associated with the CE level to the Target eNB <NUM>). However, ifstep <NUM> contains the measurement report, the block <NUM> "Decide the CE level if measurement is provided by source eNB" implies that the target eNB <NUM> will be aware of the UE's CE level. So, with this alternative, the occurrence of the target eNB <NUM> being aware of the UE's CE level may occur between steps <NUM>-<NUM> rather than between steps <NUM>-<NUM>. Thus, the target eNB <NUM> being aware of the UE's CE level may occur either after step <NUM> or after step <NUM>; depending on the information carried in the Handover request from source eNB to target eNB.

In the X2 setup/update procedure, additional parameters may be exchanged between eNBs, such as:.

A one bit EC indicator or the EC level indicator may be added in the Handover Request, or the measurement result may be added in the Handover Request.

Additional PRACH resources may be added in the Handover Request Acknowledge as part of the RRC container. The PRACH resource may be allocated for UE operating in a normal coverage mode. The PRACH resource may be allocated for a LC UE. The PRACH resource may be associated with the UE specific EC level in the target cell. The PRACH resource may be associated with the LC UE. In addition, any combination(s) of above may be considered.

With features as described herein, the proposed solution helps to ensure a reliable handover procedure for a 3GPP Rel-<NUM> low complexity UE and a UE in coverage enhancement mode for the selection of a suitable target cell when source eNB makes the handover decision, and the correct PRACH resource utilization when the UE performs the RA towards the target eNB.

During a traditional handover procedure, the source eNB makes a decision and selects a suitable target eNB based on the MEASUREMENT REPORT and the Radio Resource Management (RRM) information to handoff the UE. During the handoff procedure, the source eNB issues a HANDOVER REQUEST message to the target eNB passing necessary information to prepare the handover at the target side. After performing the Admission Control, the target eNB sends the HANDOVER REQUEST ACKNOWLEDGE to the source eNB which includes a transparent container to be sent to the UE as an RRC message to perform the handover. After receiving the RRCConnectionReconfiguration message, the UE performs synchronization to target eNB and accesses the target cell via RACH. However, the conventional handover procedure does not take into consideration the new type of low-complexity UE and UE capable of EC operation in LTE; to support coverage enhancement (CE) for both Rel-<NUM> low-complexity UE and UE operating in CE compared to existing LTE networks.

Baseline connected mode mobility mechanisms may be supported for LC UEs in normal coverage and LC UEs in "shallow" enhanced coverage. Ideally, the source eNB should prioritize the cells in which the UE is able to operate in normal coverage over cells in which the UE has to use enhanced coverage or to select the cells that UE works in low CE level when making the handover decision. A threshold for deciding the CE level is cell specific. With existing specification handover procedures, the source eNB has no knowledge of whether the neighboring eNB could support the coverage enhancement and the related coverage enhancement configuration, e.g. the cell specific CE level criteria, etc. Without such information, the source eNB could not select the suitable target eNB. As a consequence, it may make a wrong decision and request a handover to a CE incapable eNB or an eNB which the UE may work in a worst coverage situation. This may cause extra signaling overhead due to the increased number of transmission repetitions and even an unsuccessful handover procedure in a worst case scenario. Furthermore, after receiving the RRCConnectionReconfiguration message, the UE performs synchronization to the target eNB and accesses the target cell via RACH. With one-to-one mapping between PRACH repetition level and PRACH resource set, the UE needs to know the correct PRACH resource associated with its CE level in the target cell to ensure a successful RA and subsequent procedures with the target eNB.

With features as described herein, the problems noted above are overcome. Information exchanged at the X2 interface setup or X2 interface update between the base stations may be used to select a proper target base station with the best CE capabilities and proper CE level for the particular "type" of UE being handed over. For example, the handover procedure may involve distinguishing handover of a low-cost UE versus a non-low-cost UE or handover of UE working in enhanced coverage versus working in normal coverage.

<FIG> shows the operations of:, during an interface setup or an interface update between the first, source base station and the second, target base station, receiving by the first base station information regarding coverage enhancement (CE) supported by the second base station as indicated by block <NUM>; and based at least partially upon the information received by the first base station from the second base station, the first base station transmitting a handover request to the second base station for the user equipment as indicated by block <NUM>. The information may comprise at least one of:.

<FIG> shows the operations of: during an interface setup or an interface update between the first, source base station and the second, target base station, transmitting by the second base station to the first base station information regarding coverage enhancement (CE) supported by the second base station as indicated by block <NUM>; and based upon receipt of a handover request by the second base station from the first base station, the second base station transmitting a handover request acknowledgement comprising information regarding coverage enhancement (CE) related physical random access channel (PRACH) resources as indicated by block <NUM>. The information regarding coverage enhancement (CE) supported by the second base station may comprise at least one of:.

<FIG> shows the operations of:operationsreceiving by the user equipment (UE) from the first, target base station a handover command comprising information regarding coverage enhancement (CE) related physical random access channel (PRACH) resources, where the information has been received by the first base station from a second base station as indicated by block <NUM>; and transmitting, as indicated by block <NUM>, a signal by the user equipment (UE) to the second base station, where the signal comprises a physical random access channel (PRACH) preamble, where the physical random access channel (PRACH) preamble is based, at least partially, upon the information regarding the coverage enhancement (CE) related physical random access channel (PRACH) resources received by the user equipment (UE).

The first, source base station may transmit signals to the second, target base station in the network; and during an interface setup or an interface update between the first base station and the second base station, receive information regarding at least one of: whether coverage enhancement (CE) is supported by the second base station, a maximum coverage enhancement (CE) level supported by the second base station, whether low-cost coverage enhancement (CE) is supported by the second base station, and coverage enhancement (CE) level criteria at the second base station.

The first, source base station may, at least partially based upon the information received from the second, target base station, transmit a handover request to the second base station. The transmitting of the handover request to the second base station may be based, at least partially, upon a measurement report received by the first base station from a user equipment (UE). The first base station may determine, based at least partially the information received by the first base station from the second base station, whether or not to transmit the handover request to the second base station. The first base station, based at least partially upon the information received by the first base station from the second base station, may perform at least one of: configures a CE-specific measurement configuration; determines CE level criteria; and decides a CE level for the UE to use in the second base station. The first base station, based at least partially upon the information received by the first base station from the second base station, where the second base station is a neighboring base station, may compare the second base station to at least one other neighboring base station, and the first base station selects: the neighboring base station having a cell in which the UE is able to work in a normal coverage mode; or if UE has to work in a CE mode rather than in the normal coverage mode, the neighboring base station having a cell in which UE works with low CE level. Transmitting a handover request to the second base station may comprise at least one of a single bit Enhanced Coverage (EC) indicator and a Enhanced Coverage (EC) level indicator. Transmitting a handover request to the second base station may comprise transmitting a measurement report from the first base station to the second base station. The first base station may receive from the second base station a handover request acknowledgement, where the handover request acknowledgement comprises information regarding coverage enhancement (CE) related physical random access channel (PRACH) resources. The first base station may transmit to a user equipment (UE) a radio resource control (RRC) connection reconfiguration message, where the RRC connection reconfiguration message comprises information regarding coverage enhancement (CE) related physical random access channel (PRACH) resources for the second base station.

The first, source base station may an comprising at least one processor; and at least one non-transitory memory including computer program code, the at least one memory and the computer program code configured to, with the at least one processor, cause the first base station to: transmit signals to the second, target base station in the network; and during an interface setup or an interface update between the first base station and the second base station, receive information regarding at least one of: whether coverage enhancement (CE) is supported by the second base station, a maximum coverage enhancement (CE) level supported by the second base station, whether low-cost coverage enhancement (CE) is supported by the second base station, and coverage enhancement (CE) level criteria at the second base station.

The at least one memory and the computer program code may be configured to, with the at least one processor, cause the the first, source base station to: transmit a handover request to the second, target base station based, at least partially, upon the information received from the second base station. The transmitting of the handover request to the second base station may be based, at least partially, upon a measurement report received from the user equipment (UE). The at least one memory and the computer program code may be configured to, with the at least one processor, cause the first base station to: determine, based at least partially the information received from the second base station, whether or not to transmit the handover request to the second base station. The at least one memory and the computer program code may be configured to, with the at least one processor, cause the first base station to: perform, based at least partially upon the information received by the first base station from the second base station, at least one of: configure a CE-specific measurement configuration; determine CE level criteria; and decide a CE level for the UE to use in the second base station. The at least one memory and the computer program code may be configured to, with the at least one processor, cause the first base station to: based at least partially upon the information received from the second base station, where the second base station is a neighboring base station, compare the second base station to at least one other neighboring base station, and select: the neighboring base station having a cell in which the UE is able to work in a normal coverage mode; or if the UE has to work in a CE mode rather than in the normal coverage mode, the neighboring base station having a cell in which the UE works with low CE level. The at least one memory and the computer program code may be configured to, with the at least one processor, cause the first base station to: transmit a handover request to the second base station comprising at least one of: a single bit Enhanced Coverage (EC) indicator and a Enhanced Coverage (EC) level indicator. The at least one memory and the computer program code may be configured to, with the at least one processor, cause the first base station to: transmit a handover request to the second base station comprising transmitting a UE measurement report to the second base station. The at least one memory and the computer program code may be configured to, with the at least one processor, cause the first base station to: receive from the second base station a handover request acknowledgement, where the handover request acknowledgement comprises information regarding coverage enhancement (CE) related physical random access channel (PRACH) resources. The at least one memory and the computer program code may be configured to, with the at least one processor, cause the first base station to: transmit to the user equipment (UE) a radio resource control (RRC) connection reconfiguration message, where the RRC connection reconfiguration message comprises information regarding coverage enhancement (CE) related physical random access channel (PRACH) resources for the second base station.

The following operations of the first, source base station may be performed according to an executable program of instructions tangibly embodied in a non-transitory program storage device readable by a machine: transmitting signals from the first base station to the second base station in the network; and during an interface setup or an interface update between the first base station and the second base station, receiving information regarding at least one of: whether coverage enhancement (CE) is supported by the second base station, a maximum coverage enhancement (CE) level supported by the second base station, whether low-cost coverage enhancement (CE) is supported by the second base station, and coverage enhancement (CE) level criteria at the second base station.

The executable program of instructions may also be for the operations of: : based at least partially upon the information received by the first, source base station from the second base station, transmitting the handover request to the second base station; transmitting the handover request to the second base station based, at least partially, upon a measurement report received by the first base station from the user equipment (UE); determining, based at least partially on the information received by the first base station from the second base station, whether or not to transmit the handover request to the second base station; based at least partially upon the information received by the first base station from the second base station, performing at least one of: configures a CE-specific measurement configuration; determines CE level criteria; and decides a CE level for the UE to use in the second base station;, based at least partially upon the information received by the first base station from the second base station, comparing the second base station to at least one other neighboring base station, and selecting the neighboring base station having a cell in which the UE is able to work in a normal coverage mode; or if UE has to work in a CE mode rather than in the normal coverage mode, the neighboring base station having a cell in which UE works with low CE level; transmitting to the second base station a handover request comprising at least one of a single bit Enhanced Coverage (EC) indicator and a Enhanced Coverage (EC) level indicator; transmitting to the second base station a handover request comprising a measurement report; receiving from the second base station a handover request acknowledgement, where the handover request acknowledgement comprises information regarding coverage enhancement (CE) related physical random access channel (PRACH) resources; transmitting by the first base station to the user equipment (UE) a radio resource control (RRC) connection reconfiguration message, where the RRC connection reconfiguration message comprises information regarding coverage enhancement (CE) related physical random access channel (PRACH) resources for the second base station.

The second, target base station may transmit signals to the first base station in the network; and during an interface setup or an interface update between the first base station and the second base station, transmit to the first base station information regarding at least one of: whether coverage enhancement (CE) is supported by the second base station, a maximum coverage enhancement (CE) level supported by the second base station, whether low-cost coverage enhancement (CE) is supported by the second base station, and coverage enhancement (CE) level criteria at the second base station.

The second, target base station may, based upon receipt of a handover request by the second base station from the first base station, transmit a handover request acknowledgement comprising information regarding coverage enhancement (CE) related physical random access channel (PRACH) resources. The handover request may comprise at least one of a single bit EC indicator and a EC level indicator, and the information transmitted in the handover request acknowledgement may be based, at least partially, on the indicator received by the second base station. The handover request may comprise information from a measurement report received by the first base station from the user equipment (UE). The second base station may determine a CE level for the UE based upon the measurement report.

The second, target base station may comprise at least one processor; and at least one non-transitory memory including computer program code, the at least one memory and the computer program code configured to, with the at least one processor, cause the second base station to: transmit signals to the first base station in the network; and during an interface setup or an interface update between the first base station and the second base station, transmit to the first base station information regarding at least one of: whether coverage enhancement (CE) is supported by the second base station, a maximum coverage enhancement (CE) level supported by the second base station, whether low-cost coverage enhancement (CE) is supported by the second base station, and coverage enhancement (CE) level criteria at the second base station.

The at least one memory and the computer program code may be configured to, with the at least one processor, cause the second base station to: based upon receipt of a handover request by the second base station from the first base station, transmit a handover request acknowledgement comprising information regarding coverage enhancement (CE) related physical random access channel (PRACH) resources. The handover request may comprise at least one of a single bit EC indicator and a EC level indicator, and the information transmitted in the handover request acknowledgement may be based, at least partially, on the indicator received by the second base station. The handover request may comprise information from a measurement report received by the first base station from the user equipment (UE). The second base station may determine a CE level for the UE based upon the measurement report.

The following operations of the second, target base station may be performed according to an executable program of instructions tangibly embodied in a non-transitory program storage device readable by a machine: transmitting signals from the second base station to the first base station in the network; and during an interface setup or an interface update between the first base station and the second base station, transmitting to the first base station information regarding at least one of: whether coverage enhancement (CE) is supported by the second base station, a maximum coverage enhancement (CE) level supported by the second base station, whether low-cost coverage enhancement (CE) is supported by the second base station, and coverage enhancement (CE) level criteria at the second base station.

The executable program of instructions may also be for the operations of: based upon receipt of a handover request by the second base station from the first base station, transmitting a handover request acknowledgement comprising information regarding coverage enhancement (CE) related physical random access channel (PRACH) resources. The handover request may comprise at least one of a single bit EC indicator and a EC level indicator, and the information transmitted in the handover request acknowledgement may be based, at least partially, on the indicator received by the second base station. The handover request may comprise information from a measurement report received by the first base station from the user equipment (UE). The second base station may determine a CE level for the UE based upon the measurement report.

The user equipment (UE) may receive from the first base station a handover command comprising information regarding coverage enhancement (CE) related physical random access channel (PRACH) resources; and transmit a signal by the user equipment (UE) to the second base station, where the signal comprises a physical random access channel (PRACH) preamble, where the physical random access channel (PRACH) preamble is based, at least partially, upon the information regarding the coverage enhancement (CE) related physical random access channel (PRACH) resources received by the user equipment (UE).

The information regarding coverage enhancement (CE) related physical random access channel (PRACH) resources may comprise information regarding at least one of: whether coverage enhancement (CE) is supported by the second base station, a maximum coverage enhancement (CE) level supported by the second base station, whether low-cost coverage enhancement (CE) is supported by the second base station, and coverage enhancement (CE) level criteria at the second base station. Transmitting the physical random access channel (PRACH) preamble may comprise transmitting the physical random access channel (PRACH) preamble associated with a CE level supported by the second base station. The information regarding coverage enhancement (CE) physical random access channel (PRACH) resources received by the user equipment may include a resource allocation and dedicated preambles.

The user equipment may comprise at least one processor; and at least one non-transitory memory including computer program code, the at least one memory and the computer program code configured to, with the at least one processor, cause the user equipment to: receive from the first base station a handover command comprising information regarding coverage enhancement (CE) related physical random access channel (PRACH) resources; and transmit a signal to the second base station, where the signal comprises a physical random access channel (PRACH) preamble, where the physical random access channel (PRACH) preamble is based, at least partially, upon the information regarding the coverage enhancement (CE) related physical random access channel (PRACH) resources received by the user equipment (UE).

Transmitting the physical random access channel (PRACH) preamble may comprise transmitting the physical random access channel (PRACH) preamble associated with a CE level supported by the second base station. The information regarding coverage enhancement (CE) physical random access channel (PRACH) resources received by the user equipment may include a resource allocation and dedicated preambles.

The following operations of the user equipment may be performed according to an executable program of instructions tangibly embodied in a non-transitory program storage device readable by a machine: receiving from the first, source base station a handover command comprising information regarding coverage enhancement (CE) related physical random access channel (PRACH) resources; and transmitting a signal by the user equipment (UE) to the second, target base station, where the signal comprises a physical random access channel (PRACH) preamble, where the physical random access channel (PRACH) preamble is based, at least partially, upon the information regarding the coverage enhancement (CE) related physical random access channel (PRACH) resources received by the user equipment (UE).

The first, source base station may comprise means for transmitting signals from the first base station to thesecond base station in the network; and means for receiving by the first base station, during an interface setup or an interface update between the first base station and the second base station, information regarding at least one of: whether coverage enhancement (CE) is supported by the second base station, a maximum coverage enhancement (CE) level supported by the second base station, whether low-cost coverage enhancement (CE) is supported by the second base station, and coverage enhancement (CE) level criteria at the second base station.

The second, target base station may comprise means for transmitting signals from the second base station to the first base station in the network; and means for transmitting by the second base station to the first base station, during an interface setup or an interface update between the first base station and the second base station, information regarding at least one of: whether coverage enhancement (CE) is supported by the second base station, a maximum coverage enhancement (CE) level supported by the second base station, whether low-cost coverage enhancement (CE) is supported by the second base station, and coverage enhancement (CE) level criteria at the second base station.

The user equipment may comprise means for receiving by the user equipment (UE) from the first base station a handover command comprising information regarding coverage enhancement (CE) related physical random access channel (PRACH) resources; and means for transmitting a signal by the user equipment (UE) to the second base station, where the signal comprises a physical random access channel (PRACH) preamble, where the physical random access channel (PRACH) preamble is based, at least partially, upon the information regarding the coverage enhancement (CE) related physical random access channel (PRACH) resources received by the user equipment (UE).

Claim 1:
A user equipment comprising:
means for receiving a handover command from a source base station (<NUM>), wherein the handover command includes a radio resource control container from a target base station, wherein the radio resource control container comprises information regarding a coverage enhancement level dependent set of physical random access channel resources for a coverage enhancement level decided for the user equipment; and
means for transmitting a physical random access channel preamble to the target base station (<NUM>) based, at least partially, upon said information,