WO2018085049A1

WO2018085049A1 - Systems, methods, and devices for make-before-break handover and secondary cell group reconfiguration

Info

Publication number: WO2018085049A1
Application number: PCT/US2017/057325
Authority: WO
Inventors: Jie Cui; Candy YIU
Original assignee: Intel IP Corporation
Priority date: 2016-11-04
Filing date: 2017-10-19
Publication date: 2018-05-11
Also published as: DE112017004789T5

Abstract

A make-before-break handover procedure may reduce the interruption time of an intra-frequency handover. A user equipment may continue uplink (UL) transmission and downlink (DL) reception with the source cell until an initiation of radio frequency (RF) re-tuning of the UE for connection to the target cell. The UE can autonomously select a time to stop the UL transmission and the DL reception of the UE with the source cell to initiate the RF re-tuning. After the UL transmission and the DL reception of the UE with the source cell stops, the UE may perform a second portion of the handover procedure to connect to the target cell.

Description

SYSTEMS, METHODS, AND DEVICES FOR MAKE-BEFORE-BREAK HANDOVER AND SECONDARY CELL GROUP RECONFIGURATION

Related Applications

[0001] This application claims the benefit of United States provisional patent Application No. 62/417,701 , filed November 4, 2016, which is hereby incorporated by reference herein in its entirety.

Technical Field

[0002] This disclosure relates to wireless communication networks. Specifically, this disclosure relates to make-before-break handover and make-before-break second cell group reconfiguration in wireless communications systems.

Background

[0003] Wireless mobile communication technology uses various standards and protocols to transmit data between a base station and a wireless mobile device. Wireless communication system standards and protocols can include the 3rd

Generation Partnership Project (3GPP) long term evolution (LTE); the Institute of Electrical and Electronics Engineers (IEEE) 802.16 standard, which is commonly known to industry groups as worldwide interoperability for microwave access

(WiMAX); and the IEEE 802.1 1 standard for wireless local area networks (WLAN), which is commonly known to industry groups as Wi-Fi. In 3GPP radio access networks (RANs) in LTE systems, the base station can include a RAN Node such as an Evolved Universal Terrestrial Radio Access Network (E-UTRAN) Node B (also commonly denoted as evolved Node B, enhanced Node B, eNodeB, or eNB) and/or Radio Network Controller (RNC) in an E-UTRAN, which communicate with a wireless communication device, known as user equipment (UE). In fifth generation (5G) wireless RANs, RAN Nodes can include a 5G Node (gNB or new radio node B (NR NB)).

[0004] RANs use a radio access technology (RAT) to communicate between the RAN Node and UE. RANs can include global system for mobile communications (GSM), enhanced data rates for GSM evolution (EDGE) RAN (GERAN), Universal Terrestrial Radio Access Network (UTRAN), and/or E-UTRAN, which provide access to communication services through a core network. Each of the RANs operates according to a specific 3GPP RAT. For example, the GERAN implements GSM and/or EDGE RAT, the UTRAN implements universal mobile telecommunication system (UMTS) RAT or other 3GPP RAT, and the E-UTRAN implements LTE RAT.

[0005] A core network can be connected to the UE through the RAN Node. The core network can include a serving gateway (SGW), a packet data network (PDN) gateway (PGW), an access network detection and selection function (ANDSF) server, an enhanced packet data gateway (ePDG) and/or a mobility management entity (MME).

Brief Description of the Drawings

[0006] FIG. 1 illustrates a flow chart of a method, according to certain

embodiments, for a UE to perform a make-before break handover when UE radio frequency (RF) re-tuning occurs.

[0007] FIG. 2 illustrates a flow chart of a method, according to certain

embodiments, for an eNB to perform a make-before-break handover where a UE RF re-tuning may occur.

[0008] FIG. 3 illustrates a flow diagram of a method, according to certain embodiments, of a message flow associated with a handover of a UE from a source cell to a target cell in LTE.

[0009] FIG. 4 illustrates a flow diagram of a method, according to certain embodiments, of an intra-MME/serving gateway handover.

[0010] FIG. 5 illustrates an architecture of a system of a network in accordance with some embodiments.

[0011] FIG. 6 illustrates example components of a device in accordance with some embodiments.

[0012] FIG. 7 illustrates example interfaces of baseband circuitry in accordance with some embodiments.

[0013] FIG. 8 is a block diagram illustrating components, according to some example embodiments, able to read instructions from a machine-readable or computer-readable medium and perform any one or more of the methodologies discussed herein.

Detailed Description

[0014] An objective for cellular technology is to improve mobility and reduce or minimize the length of data service disruption during handover to meet ever- increasing expectations with respect to end users' experience. Make-before-break handover and RACH-less handover (HO) are intended to assist with these

objectives. RACH-less HO assumes a random access (RA) procedure at the target cell/eNB can be omitted, which may lead to minimization of the data interruption time. Another possibility is to continue the transmission to and reception from the source cell as long as a new radio link is not established at the target cell. Such an approach is often labelled as "make-before-break" handover.

[0015] Some disruption may occur during handover even with efforts to reduce or minimize disruption. For example, a handover may introduce handover delay and interruption time. A handover delay includes a radio resource control (RRC) procedure delay and a handover processing time. An interruption time may occur, for example, when a user equipment (UE) receives a handover command from a source cell that requires re-tuning. The re-tuning may interrupt data transmission or receiving.

[0016] To minimize the effects of the disruption, intra-frequency handovers for make-before-break solutions may include requirements for a handover delay and an interruption time. In some implementations, a handover delay requirement may indicate that when the UE receives an RRC message implying handover, the UE is ready to start the transmission of the new uplink physical random access channel (PRACH) channel within D-handover seconds from the end of the last transmission time interval (TTI) including the RRC command. In some embodiments, D-handover equals the maximum RRC procedure delay plus the handover processing time (e.g., T-interrupt as in certain handover procedures). An interruption time requirement may take into consideration handover cases with bandwidth change and without bandwidth change. In some embodiments, the requirements for interruption time could be general for the handover cases with or without bandwidth change.

[0017] Certain embodiments discussed herein relate to make-before-break operation when the source and target evolved node B (eNB) bandwidth is different. These embodiments may reduce or minimize the interruption time, the handover delay, and/or the effects of these disruptions.

[0018] Certain embodiments discussed herein are applicable for intra-frequency handover and secondary cell group (SCG) change. Thus, when an embodiment discusses intra-frequency handovers, it may be understood that the same principles may apply to an SCG change and vice versa. A secondary cell group is the subset of serving cells not part of the master cell group (MCG). A primary secondary cell is an SCG cell in which the UE is instructed to perform random access or initial PUSCH transmission if a random access procedure is skipped when performing an SCG change procedure.

[0019] In one make-before-break embodiment, a UE continues downlink and uplink with the source cell until the UE performs RF tuning to a target cell. In such an embodiment, the UE stops communicating with the source cell when the UE performs radio (RF) adjustments for the target cell. In case of the same bandwidth used for both the source and target cells, the UE will stop communicating with the source cell when it is ready for a first PUSCH or PRACH transmission.

[0020] In another make-before-break embodiment, it is up to UE implementation to decide when to stop communicating with the source cell when the bandwidths of the source and target cells are different.

[0021] Additional details and examples are provided with reference to the figures below. The embodiments of the disclosure can be understood by reference to the drawings, wherein like parts are designated by like numerals throughout. The components of the disclosed embodiments, as generally described and illustrated in the figures herein, could be arranged and designed in a wide variety of different configurations. Thus, the following detailed description of the embodiments of the systems and methods of the disclosure is not intended to limit the scope of the disclosure, as claimed, but is merely representative of possible embodiments.

[0022] FIG. 1 illustrates a flow chart of a method 100, according to certain embodiments, for a UE to perform a make-before break handover when UE RF re- tuning occurs. The illustrated method 100 provides, for example, UE procedures for make-before-break handovers when the UE is to camp to a target cell in scenarios where the bandwidth of the target cell is not the same as a source cell.

[0023] A UE may include a memory interface to store or retrieve 102, from a memory device, an RRC connection reconfiguration message from a source cell in a wireless network. The RRC connection reconfiguration message is the command to modify an RRC connection. It may convey information for measurement

configuration, mobility control, and radio resource configuration (including radio bearers (RBs), medium access control (MAC) main configuration and physical channel configuration), including any associated dedicated non-access stratum (NAS) information and security configuration. [0024] In certain embodiments, a baseband processor of the UE decodes 104 the RRC connection reconfiguration message to obtain mobility control information elements. The mobility control elements may include parameters for network controlled mobility of the UE to or within the wireless network. In some embodiments, the mobility control elements may include indications of make-before break configuration, RACH configuration, and/or bandwidth changes between cells.

[0025] In response to the mobility control information element, the baseband processor initiates 106 a handover procedure from the source cell to a target cell. A first portion of the handover procedure includes a determination 108 of whether make-before-break handover is configured. If make-before-break is configured, the UE may start synchronizing to the downlink of a target cell. In the make-before-break handover solution, when the UE does not perform RF-retuning, the UE continues downlink and uplink with the source cell until the UE performs the first transmission through a physical uplink shared channel (PUSCH) or PRACH to the target eNB.

[0026] When the UE performs RF-retuning to camp on the target cell, the handover procedure may be done partially before and after the UE stops the uplink transmission/downlink reception with the source cell(s). The handover may include a MAC reset after the UE stops the uplink transmission/downlink reception with the source cell(s).

[0027] If it is determined 108 that make-before-break is not configured, the UE may perform 124 a second portion of the handover procedure to connect to the target cell based on the configured handover method. If it is determined 108 that make-before-break is configured, the baseband processor may control 1 10 the UE to continue uplink (UL) transmission and downlink (DL) reception with the source cell until an initiation of RF re-tuning of the UE for connection to the target cell.

[0028] In some embodiments, the mobility control information element further comprises a random access channel (RACH) skip parameter to indicate whether a random access procedure for a target primary cell (PCell) is skipped. Thus, the baseband processor may also determine 1 12 whether the RACH skip parameter is configured. The RACH skip parameter indicates whether the UE continues uplink transmission/downlink reception with the source cell(s) before performing the first transmission through PRACH to the target PCell, or through PUSCH to the target PCell. The RACH-less solution and maintaining a connection to the source eNB (e.g., make-before-break) can be considered two independent mechanisms, activation of which is up to the network's decision. The two solutions can be activated simultaneously.

[0029] Based on the RACH determination, the baseband processor continues the UL transmission and the DL reception with the source cell before a transmission through different channels. For example, if the RACH skip parameter is not configured, the baseband processor may continue 1 14 the UL transmission and the DL reception with the source cell before a transmission through a PRACH to the target Pcell. If the RACH skip parameter is configured, the baseband processor may continue 1 16 the UL transmission and the DL reception with the source cell before a transmission through a PUSCH to the target Pcell.

[0030] The baseband processor may further determine 1 18 whether the source cell and the target cell comprise different bandwidths. If the source cell and the target cell do not comprise different bandwidths, the baseband processor may perform 124 a second portion of the handover procedure to connect to the target cell as a typical make-before-break process.

[0031] However, if it is determined 1 18 that the source cell and the target cell comprise different bandwidths, a typical make-before-break handover process would fail. For example, a typical make-before-break handover process may wait to break the UL transmission and the DL reception with the source cell until a connection is made with the target cell and the source cell instructs the UE to disconnect.

However, during re-tuning the UE may be unable to communicate with the source cell. Thus, the source cell may not be able to instruct the UE when to stop the UL transmission and the DL reception.

[0032] To address this, if it is determined 1 18 that the source cell and the target cell comprise different bandwidths, the baseband processor autonomously selects 120 a time to stop the UL transmission and the DL reception of the UE with the source cell. In some embodiments, the baseband processor is configured to select the time to stop the UL transmission and the DL reception of the UE with the source cell based on the determination that the source cell and the target cell comprise different bandwidths. In other words, it is up to the UE's implementation when to stop the uplink transmission/downlink reception with the source cell(s) to initiate re-tuning for connection to the target cell.

[0033] After the UL transmission and the DL reception is stopped, the UE initiates 122 re-tuning to cause the UE to cover the bandwidth of the target cell. The timing to stop the transmission and the reception of the UE with the source cell to initiate the RF re-tuning may be selected to reduce service interruption. For example, in some embodiments, the UE continues downlink and uplink with the source cell until a known or selected set of data has been communicated. In some embodiments it is up to the UE's implementation when to stop the data from source cell when the bandwidth of the source cell and target cell is different.

[0034] The bandwidth of the target cell may either be determined by the UE or be received from the source cell. For example, the source cell may transmit the bandwidth of the target cell in the mobility control information element. In some embodiments, the UE will scan the bandwidth to determine the bandwidth of the target cell.

[0035] After the UL transmission and the DL reception of the UE with the source cell stops, the baseband processor performs 124 a second portion of the handover procedure to connect to the target cell. The second portion of the handover procedure may include a medium access control (MAC) reset after the UE stops the UL transmission and DL reception with the source cell.

[0036] In some embodiments, the UE is configured for dual connectivity. In dual connectivity embodiments, the baseband processor may determine that the RRC connection reconfiguration message includes a secondary cell group (SCG) reconfiguration parameter. In response to the SCG reconfiguration parameter, the baseband processor starts synchronizing to a DL of a target primary secondary cell (PSCell) in the first portion of the handover procedure. If a make-before-break SCG parameter is configured, the baseband processor performs at least a portion of an SCG reconfiguration procedure after the UL transmission and the DL reception of the UE with the source cell stops.

[0037] Additionally, the control information element may further comprise a random access channel (RACH) skip SCG parameter to indicate whether a random access procedure for the target PSCell is skipped. In some embodiments, the baseband processor is further configured to, in response to the determination that the make-before-break SCG parameter is configured, control the UE to continue the UL transmission and the DL reception with the source cell before a transmission through a PRACH to the target PSCell if the RACH skip SCG parameter is not configured, or through a PUSCH to the target PSCell if the RACH skip SCG parameter is configured. [0038] FIG. 2 illustrates a flow chart of a method 200, according to certain embodiments, for an eNB to perform a make-before-break handover where a UE RF re-tuning may occur. This method 200 may be used whether RF re-tuning is needed or not.

[0039] An eNB receives 202 measurement reports from a UE. The eNB

determines 204, based at least in part on a measurement report from a UE, to hand off the UE to a target eNB. For example, the UE measurement reports may indicate that a target cell has a stronger signal at the location of the UE than a source cell, and the target cell determines to hand off the UE to the cell with the stronger signal.

[0040] The eNB generates 206 a handover request message for the target eNB. The handover request message passes information to the target eNB to prepare the handover at the target side. For example, the handover request message may include UE X2 signaling context reference at source eNB, UE S1 EPC signaling context reference, target cell ID, an eNB handover transition key (KeNB^*), RRC context including the C-RNTI of the UE in the source eNB, AS-configuration, E-RAB context and physical layer ID of the source cell + short MAC-I for possible radio link failure (RLF) recovery. UE X2 or UE S1 signaling references enable the target eNB to address the source eNB and the EPC. The E-RAB context includes radio network layer (RNL) and transport network layer (TNL) addressing information, and QoS profiles of the E-RABs.

[0041] The eNB processes 208, in response to the handover request message, a handover request acknowledge message from the target eNB. The handover request may comprise information to forward to the UE in a radio resource control (RRC) message. In some embodiments, the handover request acknowledge message includes a transparent container to be sent to the UE as an RRC message to perform the handover. The container may include a new C-RNTI, target eNB security algorithm identifiers for the selected security algorithms, a dedicated RACH preamble, and possibly some other parameters, i.e., access parameters, SIBs, etc. If RACH-less handover is configured, the container may include timing adjustment indication and optionally a preallocated uplink grant. The handover request acknowledge message may also include RNL/TNL information for the forwarding tunnels, if necessary.

[0042] The eNB generates 210 the RRC message to configure the UE for make- before-break handover. The eNB maintains 212 a connection with the UE to allow, without expectation, uplink (UL) and downlink (DL) communication with the UE during make-before-break handover to the target eNB. For example, if RF tuning is performed by the UE, the eNB would continue to allow UL and DL communication even though the UE may have already stopped communicating to tune. As another example, before a handover command, the eNB may configure certain reference signal monitoring for the UE (e.g., sounding reference signals or other reference signals). However, after configuring a make-before-break handover, the eNB may or may not receive the sounding or other feedback from the UE because the UE autonomously decides when to stop communication with the eNB to perform RF re- tuning. Thus, the eNB may not wait for a response or feedback that might otherwise be expected.

[0043] The eNB processes 214 a UE context release message from the target eNB to indicate success of the make-before-break handover and to release resources associated to the UE. In this way the communication resources may not be released before the handover is complete. By sending the UE context release message, the target eNB confirms success of handover to the source eNB and triggers the release of resources by the source eNB. In some embodiments, the target eNB sends this message after a PATH SWITCH REQUEST ACKNOWLEDGE message is received from the MME. Upon reception of the UE context release message, the source eNB can release radio and C-plane related resources associated to the UE context. Any ongoing data forwarding may continue.

[0044] FIG. 3 illustrates a flow chart of a method 300, according to certain embodiments, of a message flow associated with a handover of a UE 302 from a source cell 304 to a target cell 306. In LTE systems, handover is a network- controlled, UE-assisted procedure wherein the UE's role is typically limited to performing measurements on neighboring E-UTRAN cells or frequencies. However, in embodiments disclosed herein, the UE may additionally autonomously select a time to stop the UL transmission and the DL reception of the UE with the source cell to initiate RF re-tuning when a source eNB has a different bandwidth than a target eNB.

[0045] As shown in FIG. 3, the UE 302 may communicate packet data 307 with the source cell 304. Upon the reception of a measurement report 308 from the UE 302, the source cell 304 or a source eNB triggers a handover preparation phase. For instance the source cell 304 may communicate over X2 interface with the target cell 306 (or more accurately: eNB, in case of inter-eNB handover). The target cell 306 receives a handover request 310 and reacts positively (in case where it is feasible to accommodate the additional user) by sending a handover request acknowledgement 312 to the source cell 304. This in turn evokes a handover command 314, sent from the source cell 304 to the UE 302. This point in time may mark the beginning of the handover execution phase.

[0046] In some handovers, the reception of the handover command 314 (i.e., RRC Connection Reconfiguration including mobilityControllnfo information element) explicitly indicates the beginning of a data service interruption period. Namely, the UE 302 discards protocol stack associated with the source cell 304 and starts actions towards synchronizing with the target cell 306 while the source cell 304 initiates data forwarding 320 (e.g., for one or more data radio bearers) to the target cell 306. Data service interruption lasts as long as the RRC Connection

Reconfiguration Complete message 322 is not correctly received by the target cell 306. After receiving the handover message, the UE 302 may attempt to access the target cell 30 at the first available RACH occasion according to random access resource selection (e.g., by sending a random access preamble 324 and receiving a random access response 326), or at the first available PUSCH occasion if rach-Skip is configured. Upon successful completion of the handover, the UE 302 sends a handover complete (HO complete) message (e.g., the RRC Connection

Reconfiguration Complete message 322) to the target cell 306. The target cell 306 informs the source cell 304 of the successful handover with a UE context release message 328.

[0047] However, in a make-before-break handover process according to certain embodiments disclosed herein, the UE 302 continues downlink and uplink of packet data 318 with the source cell 304 until the UE 302 performs a first transmission through PUSCH or PRACH to the target eNB. When RF re-tuning is necessary, the UE 302 autonomously selects a time to stop the UL transmission and the DL reception of the UE 302 with the source cell 304 to initiate RF re-tuning.

[0048] In one embodiment, a UE configured for dual connectivity can initiate a secondary cell group (SCG) reconfiguration procedure, and determine that the UE is configured for make-before-break SCG reconfiguration. In response to the

determination, the UE can start synchronization to a DL of a PSCell. The UE may perform at least a portion of the SCG reconfiguration procedure after the UE stops UL transmission and DL reception with one or more source cells. For example, the UE can perform an SCG MAC reset after the UE stops the UL transmission and DL reception with the one or more source cells.

[0049] In some embodiments, the UE autonomously selects a time to stop the UL transmission and the DL reception of the UE with the source cell to initiate RF re- tuning for connection to a target cell. The selected time to stop the UL transmission and the DL reception of the UE with the one or more source cells may be based on reducing service interruption upon a determination that the source cell and the target PSCell communicate with the UE using different bandwidths.

[0050] The UE may decode an RRC connection reconfiguration message from a master evolved node B (MeNB) to obtain an SCG mobility control information parameter, and in response to the SCG mobility control information parameter and the SCG make-before-break parameter, initiate the SCG reconfiguration procedure. In some embodiments the UE also obtains, from the RRC connection reconfiguration message, an SCG make-before-break parameter set to indicate that the UE is configured for the make-before-break SCG reconfiguration.

[0051] In some embodiments, the UE obtains, from the RRC connection reconfiguration message, a random access channel (RACH) skip SCG parameter to indicate whether a random access procedure for the target PSCell is skipped. In response to a determination that the make-before-break SCG parameter is configured, the UE can continue the UL transmission and the DL reception with the one or more source cells before a transmission. For example, if the RACH skip SCG parameter is not configured, the UE continues the UL transmission and the DL reception with a PRACH to the target PSCell; and if the RACH skip SCG parameter is configured, the UE continues the UL transmission and the DL reception with a PUSCH to the target PSCell.

[0052] The following description provides non-limiting examples of handover embodiments. In RRC_CONNECTED, the network controls UE mobility; i.e., the network decides when the UE connects to which E-UTRA cell(s), or inter-RAT cell. For network controlled mobility in RRC_CONNECTED, the PCell can be changed using an RRCConnectionReconfiguration message including the mobilityControllnfo (handover), whereas the SCell(s) can be changed using the

RRCConnectionReconfiguration message either with or without the

mobilityControllnfo. [0053] An SCG can be established, reconfigured or released by using an

RRCConnectionReconfiguration message with or without the mobilityControllnfo. In case Random Access to the PSCell or initial PUSCH to the PSCell, if RACH- SkipSCG is configured, is required upon SCG reconfiguration, E-UTRAN employs the SCG change procedure (i.e., an RRCConnectionReconfiguration message including the mobilityControllnfoSCG). The PSCell can only be changed, in certain embodiments, using the SCG change procedure and by release and addition of the PSCell.

[0054] The network triggers the handover procedure, e.g., based on radio conditions, load. To facilitate this, the network may configure the UE to perform measurement reporting (possibly including the configuration of measurement gaps). The network may also initiate handover blindly, i.e., without having received measurement reports from the UE.

[0055] Before sending the handover message to the UE, the source eNB prepares one or more target cells. The source eNB selects the target PCell. The source eNB may also provide the target eNB with a list of best cells on each frequency for which measurement information is available, in order of decreasing reference signal received power (RSRP). The source eNB may also include available measurement information for the cells provided in the list. The target eNB decides which SCells are configured for use after handover, which may include cells other than the ones indicated by the source eNB. If an SCG is configured, handover involves either SCG release or SCG change. In case the UE was configured with DC, the target eNB indicates in the handover message whether the UE may release the entire SCG configuration. Upon connection re-establishment, the UE releases the entire SCG configuration except for the data radio bearer (DRB) configuration, while E-UTRAN in the first reconfiguration message following the re-establishment either releases the DRB(s) or reconfigures the DRB(s) to MCG DRB(s).

[0056] The target eNB generates the message used to perform the handover, i.e., the message including the AS-configuration to be used in the target cell(s). The source eNB transparently (i.e., without altering values/content) forwards the handover message/information received from the target to the UE. When

appropriate, the source eNB may initiate data forwarding for (a subset of) the DRBs.

[0057] After receiving the handover message, the UE attempts to access the target PCell at the first available RACH occasion according to Random Access resource selection defined in TS 36.321 ; i.e., the handover is asynchronous, or at the first available PUSCH occasion if RACH-Skip is configured. Consequently, when allocating a dedicated preamble for the random access in the target PCell, E-UTRA is configured to make it available from the first RACH occasion the UE may use. Upon successful completion of the handover, the UE sends a message used to confirm the handover.

[0058] If the target eNB does not support the release of RRC protocol which the source eNB used to configure the UE, the target eNB may be unable to comprehend the UE configuration provided by the source eNB. In this case, the target eNB should use the full configuration option to reconfigure the UE for Handover and Re- establishment. The full configuration option includes an initialization of the radio configuration, which makes the procedure independent of the configuration used in the source cell(s) with the exception that the security algorithms are continued for the RRC re-establishment.

[0059] After the successful completion of handover, PDCP SDUs may be retransmitted in the target cell(s). In certain embodiments, this only applies for DRBs using RLC-AM mode and for handovers not involving the full configuration option. After the successful completion of handover not involving the full configuration option, the SN and the hyper frame number (HFN) are reset except for the DRBs using RLC-AM mode (for which both SN and HFN continue). For reconfigurations involving the full configuration option, the PDCP entities are newly established (SN and HFN do not continue) for the DRBs irrespective of the RLC mode. The further details are specified in TS 36.323.

[0060] FIG. 4 illustrates an example flow chart of a method 400, according to certain embodiments, of an intra-MME/serving gateway handover. The figure is provided by way of example only and depicts the basic handover scenario where neither MME 408 nor Serving Gateway 410 changes.

[0061] In the illustrated embodiment, the preparation and execution phase of the handover procedure is performed without evolved packet core (EPC) involvement; i.e., preparation messages are directly exchanged between the eNBs 404, 406. The release of the resources at the source side during the handover completion phase is triggered by the source eNB 404. In case a relay node (RN) is involved, its donor eNB (DeNB) relays the appropriate S1 messages between the RN and the MME 408 (S1 -based handover) and X2 messages between the RN and target eNB 406 (X2- based handover); the DeNB is explicitly aware of a UE attached to the RN due to the S1 proxy and X2 proxy functionality.

[0062] The UE context 412 within the source eNB 404 contains information regarding roaming and access restrictions which were provided either at connection establishment or at the last timing advance (TA) update. The source eNB 404 configures the UE measurement procedures according to the roaming and access restriction information and, e.g., the available multiple frequency band information. Measurements 414 provided by the source eNB 404 may assist the function controlling the UE's 402 connection mobility. A measurement report 416 is triggered and sent to the source eNB 404.

[0063] The source eNB 404 makes a handover decision 418 based on the measurement report 416 and radio resource management (RRM) information to hand off the UE 402. The source eNB 404 issues a handover request message 420 to the target eNB 406 passing information to prepare the handover at the target eNB 406 (e.g., UE X2 signaling context reference at source eNB, UE S1 EPC signalling context reference, target cell ID, KeNB^* RRC context including the C-RNTI of the UE in the source eNB, AS-configuration, E-RAB context and physical layer ID of the source cell + short MAC-I for possible RLF recovery). UE X2 / UE S1 signaling references enable the target eNB 406 to address the source eNB 404 and the EPC. The E-RAB context includes RNL and TNL addressing information, and QoS profiles of the E-RABs.

[0064] Admission control 422 may be performed by the target eNB 406, dependent on the received E-RAB QoS information to increase the likelihood of a successful handover, if the resources can be granted by target eNB 406. The target eNB 406 configures the resources according to the received E-RAB QoS information and reserves a C-RNTI and optionally a RACH preamble. The AS-configuration to be used in the target cell can either be specified independently (i.e., an "establishment") or as a delta compared to the AS-configuration used in the source cell (i.e. a

"reconfiguration").

[0065] The target eNB 406 prepares handover with L1/L2 and sends the

HANDOVER REQUEST ACKNOWLEDGE message 424 to the source eNB 404. The HANDOVER REQUEST ACKNOWLEDGE message 424 includes a transparent container to be sent to the UE 402 as an RRC message to perform the handover. The container includes a new C-RNTI and target eNB 406 security algorithm identifiers for the selected security algorithms, and may include a dedicated RACH preamble and possibly some other parameters, i.e., access parameters, SIBs, etc. If RACH-less handover is configured, the container includes a timing adjustment indication and optionally a preallocated uplink grant. The HANDOVER REQUEST ACKNOWLEDGE message 424 may also include RNL/TNL information for the forwarding tunnels, if necessary. As soon as the source eNB 404 receives the HANDOVER REQUEST ACKNOWLEDGE message 424, or as soon as the transmission of the handover command is initiated in the downlink, data forwarding may be initiated.

[0066] The following description provides means to avoid data loss during handover. The target eNB 406 generates the RRC message 426 to perform the handover, i.e. RRCConnectionReconfiguration message including the

mobilityControllnfo, to be sent by the source eNB 404 towards the UE 402. The source eNB 404 performs the integrity protection and ciphering of the message. The UE 402 receives the RRCConnectionReconfiguration message 426 with parameters (e.g., new C-RNTI, target eNB security algorithm identifiers, and optionally dedicated RACH preamble, target eNB SIBs, etc.) and is commanded by the source eNB 404 to perform the HO. If RACH-less HO is configured, the

RRCConnectionReconfiguration message 426 includes timing adjustment indication and optionally preallocated uplink grant for accessing the target eNB 406. If preallocated uplink grant is not included, the UE 402 may monitor the Physical Downlink Control Channel (PDCCH) of the target eNB 406 to receive an uplink grant. In certain embodiments, the UE 402 does not delay the handover execution for delivering the HARQ/ARQ responses to the source eNB 404.

[0067] If Make-Before-Break handover is configured, the connection to the source cell is maintained after the reception of RRCConnectionReconfiguration message 426 with mobilityControllnfo before the UE 402 executes initial uplink transmission to the target cell. If Make-Before-Break handover is configured, the source eNB 404 or the UE 402 decides when to stop transmitting to the UE 402. The UE 402 can be configured with Make-Before-Break handover and RACH-less handover

simultaneously.

[0068] When make-before-break handover is configured, in order to change bandwidth for the target cell, the RF chain might be adjusted to cover different bandwidth. In addition to RF chain adjustment, or in other embodiments, automatic gain control (AGC) adjusting may be needed if the bandwidth is changed. Taking into account for these factors for bandwidth change, the interruption time is estimated up to 5ms for certain embodiments. Thus, the UE 402 may not be able to receive data from the source cell for up to 5ms during this time. This problem may happen where the source cell bandwidth and target cell bandwidth are different. Therefore, embodiments disclosed herein provide procedures for make-before-break solutions that reduce handover delay.

[0069] In one make-before-break handover embodiment, the UE 402 continues downlink and uplink with the source eNB 404 until the UE 402 performs RF tuning to target eNB 406. In this embodiment, the UE 402 stops communicating with the source eNB 404 when the UE 402 performs RF adjustments for the target eNB 406. In case of same bandwidth, the UE 402 may stop communicating with the source eNB 404 when it is ready for first PUSCH or PRACH transmission.

[0070] In another make-before-break handover embodiment, it is up to UE 402 implementation when to stop communication with the source eNB 404 when the bandwidth of source and target is different such that the UE 402 performs RF re- tuning. In some embodiments, the current technical specifications may be updated to indicate that UE implementation may determine when to stop the data from the source cell when the bandwidth of source and target is different.

[0071] Continuing with the method 400 shown in FIG. 4, the source eNB 404 sends the SN STATUS TRANSFER message 428 to the target eNB 406 to convey the uplink PDCP SN receiver status and the downlink PDCP SN transmitter status of E-RABs for which PDCP status preservation applies (i.e., for RLC AM). The uplink PDCP SN receiver status includes at least the Packet Data Convergence Protocol sequence number (PDCP SN) of the first missing UL service data unit (SDU) and may include a bit map of the receive status of the out-of-sequence UL SDUs for the UE 402 to retransmit in the target cell, if there are any such SDUs. The downlink PDCP SN transmitter status indicates the next PDCP SN that the target eNB 406 assigns to new SDUs, not having a PDCP SN yet. The source eNB 404 may omit sending this message if none of the E-RABs of the UE 402 are treated with PDCP status preservation.

[0072] If RACH-less handover is not configured, after receiving the

RRCConnectionReconfiguration message 426 including the

mobilityControllnformation, UE 402 performs synchronization 430 to target eNB 406band accesses the target cell via RACH, following a contention-free procedure if a dedicated RACH preamble was indicated in the mobilityControllnformation, or following a contention-based procedure if no dedicated preamble was indicated. UE 402 derives target eNB 406 specific keys and configures the selected security algorithms to be used in the target cell. If RACH-less HO is configured, UE 402 performs synchronization to target eNB 406. UE 402 derives target eNB 406 specific keys and configures the selected security algorithms to be used in the target cell.

[0073] If RACH-less HO is not configured, the target eNB 406 responds with UL allocation and timing advance 432. If RACH-less HO is configured and the UE 402 did not get the periodic pre-allocated uplink 434 grant in the

RRCConnectionReconfiguration message 426 including the mobilityControllnfo, the UE 402 receives uplink grant via the PDCCH of the target cell. The UE 402 uses the first available uplink grant after synchronization to the target cell.

[0074] When the UE 402 has successfully accessed the target eNB 406 or received uplink grant when RACH-less HO is configured, the UE sends the

RRCConnectionReconfigurationComplete message 436 (C-RNTI) to confirm the handover, along with an uplink Buffer Status Report, whenever possible, to the target eNB 406 to indicate that the handover procedure is completed for the UE 402. The target eNB 406 verifies the C-RNTI sent in the

RRCConnectionReconfigurationComplete message 436. The target eNB 406 can now begin sending data to the UE 402.

[0075] The target eNB 406 sends a PATH SWITCH REQUEST message 438 to MME 408 to inform it that the UE 402 has changed cell. The MME 408 sends a MODIFY BEARER REQUEST message 440 to the Serving Gateway 410. The Serving Gateway 410 switches the downlink data path 442 to the target side. The Serving Gateway 410 sends one or more "end marker" packets on the old path to the source eNB 404 and then can release any U-plane/TNL resources towards the source eNB 404. The Serving Gateway 410 sends a MODIFY BEARER RESPONSE message 444 to MME 408.

[0076] The MME 408 confirms the PATH SWITCH REQUEST message 438 with the PATH SWITCH REQUEST ACKNOWLEDGE message 446. By sending the UE CONTEXT RELEASE message 448, the target eNB 406 informs success of handover to source eNB 404 and triggers the release of resources by the source eNB 404. The target eNB 406 sends this message after the PATH SWITCH

REQUEST ACKNOWLEDGE message 446 is received from the MME 408.

[0077] Upon reception of the UE CONTEXT RELEASE message 448, the source eNB 404 can release radio and C-plane related resources 450 associated to the UE context. Any ongoing data forwarding may continue. When an X2 handover is used involving HeNBs and when the source HeNB is connected to a HeNB GW, a UE

CONTEXT RELEASE REQUEST message including an explicit GW Context

Release Indication is sent by the source HeNB, in order to indicate that the HeNB

GW may release the resources related to the UE context.

[0078] The following are examples according to certain embodiments.

[0079] Example A may include a UE adapted to continue downlink and uplink with a source cell until the UE performs RF tuning to target cell.

[0080] Example B may include the UE of example A and/or some other examples herein, wherein a UE implementation indicates when to stop the data from source cell when the bandwidth of source cell and target cell is different.

[0081] Example C may include the UE of examples A-B and/or some other examples herein, wherein make-before-break is configured and the target cell bandwidth is different from source cell bandwidth.

[0082] Example D may include an apparatus comprising means to perform one or more elements of a method described in or related to any of examples A-C, or any other method or process described herein.

[0083] Example E may include one or more non-transitory computer-readable media comprising instructions to cause an electronic device, upon execution of the instructions by one or more processors of the electronic device, to perform one or more elements of a method described in or related to any of examples A-C, or any other method or process described herein.

[0084] Example F may include an apparatus comprising logic, modules, and/or circuitry to perform one or more elements of a method described in or related to any of examples A-C, or any other method or process described herein.

[0085] Example G may include a method, technique, or process as described in or related to any of examples A-C, or portions or parts thereof.

[0086] Example H may include an apparatus comprising: one or more processors and one or more computer readable media comprising instructions that, when executed by the one or more processors, cause the one or more processors to perform the method, techniques, or process as described in or related to any of examples A-C, or portions thereof.

[0087] Example I may include a method of communicating in a wireless network as shown and described herein.

[0088] Example J may include a system for providing wireless communication as shown and described herein.

[0089] Example K may include a device for providing wireless communication as shown and described herein.

[0090] For an example handover procedure, reception of an

RRCConnectionReconfiguration including the mobilityControllnfo by the UE may function according to the example pseudocode demonstrated below. Additional security and sidelink functionality may be included in some embodiments. If the RRCConnectionReconfiguration message includes the mobilityControllnfo and the UE is able to comply with the configuration included in this message, the UE shall:

1 >stop timer T310, if running;

1 >stop timer T312, if running;

1 >start timer T304 with the timer value set to t304, as included in the

mobilityControllnfo;

1 >stop timer T370, if running;

1 >if the carrierFreq is included:

2>consider the target PCell to be one on the frequency indicated by the

carrierFreq with a physical cell identity indicated by the targetPhysCellld;

1 >else:

2>consider the target PCell to be one on the frequency of the source PCell with a physical cell identity indicated by the targetPhysCellld;

1 >start synchronising to the DL of the target PCell;

NOTE 1 : The UE should perform the handover as soon as possible following the reception of the RRC message triggering the handover, which could be before confirming successful reception (HARQ and ARQ) of this message. 1 >if BL UE or UE in CE:

2>acquire the MasterlnformationBlock in the target PCell;

1 >if makeBeforeBreak is configured:

2> start synchronising to the DL of the target PSCell, if

mobilityControllnfoSCG is included;

2>perform the remainder of this procedure including and following resetting MAC after the UE stops the uplink transmission/downlink reception with the source cell(s);

NOTE 1 a: It is up to UE implementation when to stop the uplink transmission/ downlink reception with the source cell(s) to initiate re-tuning for connection to the target cell, if makeBeforeBreak is configured.

1 >reset MCG MAC and SCG MAC, if configured;

1 > re-establish PDCP for all RBs that are established;

NOTE 2: The handling of the radio bearers after the successful completion of the PDCP re-establishment, e.g. the re-transmission of unacknowledged PDCP SDUs (as well as the associated status reporting).

1 >re-establish MCG RLC and SCG RLC, if configured, for all RBs that are established;

1 >configure lower layers to consider the SCell(s) other than the PSCell, if

configured, to be in deactivated state;

1 >apply the value of the newUE-ldentity as the C-RNTI;

1 >if the RRCConnectionReconfiguration message includes the fullConfig:

2>perform the radio configuration procedure;

1 >configure lower layers in accordance with the received

radioResourceConfigCommon;

1 >if the received RRCConnectionReconfiguration message includes the rach- Skip: 2>apply the N_TA value for the target MCG PTAG, as indicated by targetTA in rach-Skip;

1 >configure lower layers in accordance with any additional fields, not covered in the previous, if included in the received mobilityControllnfo;

1 >if the received RRCConnectionReconfiguration includes the

sCellToReleaseList:

2>perform SCell release;

1 >if the received RRCConnectionReconfiguration includes the scg-Configuration; or

1 >if the current UE configuration includes one or more split DRBs and the

received RRCConnectionReconfiguration includes

radioResourceConfigDedicated including drb-ToAddModList:

2>perform SCG reconfiguration;

1 >if the RRCConnectionReconfiguration message includes the

radioResourceConfigDedicated:

2>perform the radio resource configuration procedure;

2>the procedure ends.

[0091] In some embodiments, an example SCG reconfiguration procedure may function according to the following pseudocode. The UE shall:

1 >if makeBeforeBreakSCG is configured:

2>stop timer T313, if running;

2>start timer T307 with the timer value set to t307, as included in the

mobilityControllnfoSCG;

2>start synchronising to the DL of the target PSCell, if needed; 2>perform the remainder of this procedure including and following resetting MAC after the UE stops the uplink transmission/downlink reception with the source cell(s);

NOTE 0a: It is up to UE implementation when to stop the uplink transmission/ downlink reception with the source cell(s) to initiate re-tuning for the connection to the target cell, if makeBeforeBreakSCG is configured.

1 >if rach-SkipSCG is configured:

2>apply the N_TA value for the target SCG PTAG, as indicated by targetTA in rach-SkipSCG;

1 >if the received scg-Configuration is set to release or includes the

mobilityControllnfoSCG (i.e. SCG release/ change):

2>if mobilityControllnfo is not received (i.e. SCG release/ change without HO): 3> reset SCG MAC, if configured;

3>for each drb-ldentity value that is part of the current UE configuration: 4>if the DRB indicated by drb-ldentity is an SCG DRB:

5>re-establish the PDCP entity and the SCG RLC entity or entities; 4>if the DRB indicated by drb-ldentity is a split DRB:

5>perform PDCP data recovery and re-establish the SCG RLC entity;

4>if the DRB indicated by drb-ldentity is an MCG DRB; and

4>drb-ToAddModl_istSCG is received and includes the drb-ldentity value, while for this entry drb-Type is included and set to scg (i.e. MCG to SCG):

5>re-establish the PDCP entity and the MCG RLC entity or entities;

3>configure lower layers to consider the SCG SCell(s), except for the

PSCell, to be in deactivated state... .

[0092] FIG. 5 illustrates an architecture of a system 500 of a network in accordance with some embodiments. The system 500 is shown to include a user equipment (UE) 501 and a UE 502. The UEs 501 and 502 are illustrated as smartphones (e.g., handheld touchscreen mobile computing devices connectable to one or more cellular networks), but may also comprise any mobile or non-mobile computing device, such as Personal Data Assistants (PDAs), pagers, laptop computers, desktop computers, wireless handsets, or any computing device including a wireless communications interface.

[0093] In some embodiments, any of the UEs 501 and 502 can comprise an Internet of Things (loT) UE, which can comprise a network access layer designed for low-power loT applications utilizing short-lived UE connections. An loT UE can utilize technologies such as machine-to-machine (M2M) or machine-type

communications (MTC) for exchanging data with an MTC server or device via a public land mobile network (PLMN), Proximity-Based Service (ProSe) or device-to- device (D2D) communication, sensor networks, or loT networks. The M2M or MTC exchange of data may be a machine-initiated exchange of data. An loT network describes interconnecting loT UEs, which may include uniquely identifiable embedded computing devices (within the Internet infrastructure), with short-lived connections. The loT UEs may execute background applications (e.g., keep-alive messages, status updates, etc.) to facilitate the connections of the loT network.

[0094] The UEs 501 and 502 may be configured to connect, e.g.,

communicatively couple, with a radio access network (RAN) 510. The RAN 510 may be, for example, an Evolved Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access Network (E-UTRAN), a NextGen RAN (NG RAN), or some other type of RAN. The UEs 501 and 502 utilize connections 503 and 504, respectively, each of which comprises a physical communications interface or layer (discussed in further detail below); in this example, the connections 503 and 504 are illustrated as an air interface to enable communicative coupling, and can be consistent with cellular communications protocols, such as a Global System for Mobile Communications (GSM) protocol, a code-division multiple access (CDMA) network protocol, a Push-to-Talk (PTT) protocol, a PTT over Cellular (POC) protocol, a Universal Mobile Telecommunications System (UMTS) protocol, a 3GPP Long Term Evolution (LTE) protocol, a fifth generation (5G) protocol, a New Radio (NR) protocol, and the like.

[0095] In this embodiment, the UEs 501 and 502 may further directly exchange communication data via a ProSe interface 505. The ProSe interface 505 may alternatively be referred to as a sidelink interface comprising one or more logical channels, including but not limited to a Physical Sidelink Control Channel (PSCCH), a Physical Sidelink Shared Channel (PSSCH), a Physical Sidelink Discovery

Channel (PSDCH), and a Physical Sidelink Broadcast Channel (PSBCH).

[0096] The UE 502 is shown to be configured to access an access point (AP) 506 via connection 507. The connection 507 can comprise a local wireless connection, such as a connection consistent with any IEEE 802.1 1 protocol, wherein the AP 506 would comprise a wireless fidelity (WiFi®) router. In this example, the AP 506 is shown to be connected to the Internet without connecting to the core network of the wireless system (described in further detail below).

[0097] The RAN 510 can include one or more access nodes that enable the connections 503 and 504. These access nodes (ANs) can be referred to as base stations (BSs), NodeBs, evolved NodeBs (eNBs), next Generation NodeBs (gNB), RAN nodes, and so forth, and can comprise ground stations (e.g., terrestrial access points) or satellite stations providing coverage within a geographic area (e.g., a cell). The RAN 510 may include one or more RAN nodes for providing macrocells, e.g., macro RAN node 51 1 , and one or more RAN nodes for providing femtocells or picocells (e.g., cells having smaller coverage areas, smaller user capacity, or higher bandwidth compared to macrocells), e.g., low power (LP) RAN node 512.

[0098] Any of the RAN nodes 51 1 and 512 can terminate the air interface protocol and can be the first point of contact for the UEs 501 and 502. In some

embodiments, any of the RAN nodes 51 1 and 512 can fulfill various logical functions for the RAN 510 including, but not limited to, radio network controller (RNC) functions such as radio bearer management, uplink and downlink dynamic radio resource management and data packet scheduling, and mobility management.

[0099] In accordance with some embodiments, the UEs 501 and 502 can be configured to communicate using Orthogonal Frequency-Division Multiplexing

(OFDM) communication signals with each other or with any of the RAN nodes 51 1 and 512 over a multicarrier communication channel in accordance various

communication techniques, such as, but not limited to, an Orthogonal Frequency- Division Multiple Access (OFDMA) communication technique (e.g., for downlink communications) or a Single Carrier Frequency Division Multiple Access (SC-FDMA) communication technique (e.g., for uplink and ProSe or sidelink communications), although the scope of the embodiments is not limited in this respect. The OFDM signals can comprise a plurality of orthogonal subcarriers.

[0100] In some embodiments, a downlink resource grid can be used for downlink transmissions from any of the RAN nodes 51 1 and 512 to the UEs 501 and 502, while uplink transmissions can utilize similar techniques. The grid can be a time- frequency grid, called a resource grid or time-frequency resource grid, which is the physical resource in the downlink in each slot. Such a time-frequency plane representation is a common practice for OFDM systems, which makes it intuitive for radio resource allocation. Each column and each row of the resource grid

corresponds to one OFDM symbol and one OFDM subcarrier, respectively. The duration of the resource grid in the time domain corresponds to one slot in a radio frame. The smallest time-frequency unit in a resource grid is denoted as a resource element. Each resource grid comprises a number of resource blocks, which describe the mapping of certain physical channels to resource elements. Each resource block comprises a collection of resource elements; in the frequency domain, this may represent the smallest quantity of resources that currently can be allocated. There are several different physical downlink channels that are conveyed using such resource blocks.

[0101] The physical downlink shared channel (PDSCH) may carry user data and higher-layer signaling to the UEs 501 and 502. The physical downlink control channel (PDCCH) may carry information about the transport format and resource allocations related to the PDSCH channel, among other things. It may also inform the UEs 501 and 502 about the transport format, resource allocation, and H-ARQ (Hybrid Automatic Repeat Request) information related to the uplink shared channel. Typically, downlink scheduling (assigning control and shared channel resource blocks to the UE 502 within a cell) may be performed at any of the RAN nodes 51 1 and 512 based on channel quality information fed back from any of the UEs 501 and 502. The downlink resource assignment information may be sent on the PDCCH used for (e.g., assigned to) each of the UEs 501 and 502.

[0102] The PDCCH may use control channel elements (CCEs) to convey the control information. Before being mapped to resource elements, the PDCCH complex-valued symbols may first be organized into quadruplets, which may then be permuted using a sub-block interleaver for rate matching. Each PDCCH may be transmitted using one or more of these CCEs, where each CCE may correspond to nine sets of four physical resource elements known as resource element groups (REGs). Four Quadrature Phase Shift Keying (QPSK) symbols may be mapped to each REG. The PDCCH can be transmitted using one or more CCEs, depending on the size of the downlink control information (DCI) and the channel condition. There can be four or more different PDCCH formats defined in LTE with different numbers of CCEs (e.g., aggregation level, L=1 , 2, 4, or 8).

[0103] Some embodiments may use concepts for resource allocation for control channel information that are an extension of the above-described concepts. For example, some embodiments may utilize an enhanced physical downlink control channel (EPDCCH) that uses PDSCH resources for control information transmission. The EPDCCH may be transmitted using one or more enhanced control channel elements (ECCEs). Similar to above, each ECCE may correspond to nine sets of four physical resource elements known as enhanced resource element groups (EREGs). An ECCE may have other numbers of EREGs in some situations.

[0104] The RAN 510 is shown to be communicatively coupled to a core network (CN) 520— via an S1 interface 513. In embodiments, the CN 520 may be an evolved packet core (EPC) network, a NextGen Packet Core (NPC) network, or some other type of CN. In this embodiment the S1 interface 513 is split into two parts: the S1 -U interface 514, which carries traffic data between the RAN nodes 51 1 and 512 and a serving gateway (S-GW) 522, and an S1 -mobility management entity (MME) interface 515, which is a signaling interface between the RAN nodes 51 1 and 512 and MMEs 521.

[0105] In this embodiment, the CN 520 comprises the MMEs 521 , the S-GW 522, a Packet Data Network (PDN) Gateway (P-GW) 523, and a home subscriber server (HSS) 524. The MMEs 521 may be similar in function to the control plane of legacy Serving General Packet Radio Service (GPRS) Support Nodes (SGSN). The MMEs 521 may manage mobility aspects in access such as gateway selection and tracking area list management. The HSS 524 may comprise a database for network users, including subscription-related information to support the network entities' handling of communication sessions. The CN 520 may comprise one or several HSSs 524, depending on the number of mobile subscribers, on the capacity of the equipment, on the organization of the network, etc. For example, the HSS 524 can provide support for routing/roaming, authentication, authorization, naming/addressing resolution, location dependencies, etc. [0106] The S-GW 522 may terminate the S1 interface 513 towards the RAN 510, and routes data packets between the RAN 510 and the CN 520. In addition, the S- GW 522 may be a local mobility anchor point for inter-RAN node handovers and also may provide an anchor for inter-3GPP mobility. Other responsibilities may include lawful intercept, charging, and some policy enforcement.

[0107] The P-GW 523 may terminate an SGi interface toward a PDN. The P-GW 523 may route data packets between the CN 520 (e.g., an EPC network) and external networks such as a network including the application server 530

(alternatively referred to as application function (AF)) via an Internet Protocol (IP) interface 525. Generally, an application server 530 may be an element offering applications that use IP bearer resources with the core network (e.g., UMTS Packet Services (PS) domain, LTE PS data services, etc.). In this embodiment, the P-GW 523 is shown to be communicatively coupled to an application server 530 via an IP communications interface 525. The application server 530 can also be configured to support one or more communication services (e.g., Voice-over-Internet Protocol (VoIP) sessions, PTT sessions, group communication sessions, social networking services, etc.) for the UEs 501 and 502 via the CN 520.

[0108] The P-GW 523 may further be a node for policy enforcement and charging data collection. A Policy and Charging Enforcement Function (PCRF) 526 is the policy and charging control element of the CN 520. In a non-roaming scenario, there may be a single PCRF in the Home Public Land Mobile Network (HPLMN) associated with a UE's Internet Protocol Connectivity Access Network (IP-CAN) session. In a roaming scenario with local breakout of traffic, there may be two PCRFs associated with a UE's IP-CAN session: a Home PCRF (H-PCRF) within a HPLMN and a Visited PCRF (V-PCRF) within a Visited Public Land Mobile Network (VPLMN). The PCRF 526 may be communicatively coupled to the application server 530 via the P-GW 523. The application server 530 may signal the PCRF 526 to indicate a new service flow and select the appropriate Quality of Service (QoS) and charging parameters. The PCRF 526 may provision this rule into a Policy and Charging Enforcement Function (PCEF) (not shown) with the appropriate traffic flow template (TFT) and QoS class of identifier (QCI), which commences the QoS and charging as specified by the application server 530.

[0109] FIG. 6 illustrates example components of a device 600 in accordance with some embodiments. In some embodiments, the device 600 may include application circuitry 602, baseband circuitry 604, Radio Frequency (RF) circuitry 606, front-end module (FEM) circuitry 608, one or more antennas 610, and power management circuitry (PMC) 612 coupled together at least as shown. The components of the illustrated device 600 may be included in a UE or a RAN node. In some

embodiments, the device 600 may include fewer elements (e.g., a RAN node may not utilize application circuitry 602, and instead include a processor/controller to process IP data received from an EPC). In some embodiments, the device 600 may include additional elements such as, for example, memory/storage, display, camera, sensor, or input/output (I/O) interface. In other embodiments, the

components described below may be included in more than one device (e.g., said circuitries may be separately included in more than one device for Cloud-RAN (C- RAN) implementations).

[0110] The application circuitry 602 may include one or more application processors. For example, the application circuitry 602 may include circuitry such as, but not limited to, one or more single-core or multi-core processors. The

processor(s) may include any combination of general-purpose processors

and dedicated processors (e.g., graphics processors, application processors, etc.). The processors may be coupled with or may include memory/storage and may be configured to execute instructions stored in the memory/storage to enable various applications or operating systems to run on the device 600. In some embodiments, processors of application circuitry 602 may process IP data packets received from an EPC.

[0111] The baseband circuitry 604 may include circuitry such as, but not limited to, one or more single-core or multi-core processors. The baseband circuitry 604 may include one or more baseband processors or control logic to process baseband signals received from a receive signal path of the RF circuitry 606 and to generate baseband signals for a transmit signal path of the RF circuitry 606. Baseband processing circuity 604 may interface with the application circuitry 602 for generation and processing of the baseband signals and for controlling operations of the RF circuitry 606. For example, in some embodiments, the baseband circuitry 604 may include a third generation (3G) baseband processor 604A, a fourth generation (4G) baseband processor 604B, a fifth generation (5G) baseband processor 604C, or other baseband processor(s) 604D for other existing generations, generations in development or to be developed in the future (e.g., second generation (2G), sixth generation (6G), etc.).

[0112] The baseband circuitry 604 (e.g., one or more of baseband processors 604A-D) may handle various radio control functions that enable communication with one or more radio networks via the RF circuitry 606. In other embodiments, some or all of the functionality of baseband processors 604A-D may be included in modules stored in the memory 604G and executed via a Central Processing Unit (CPU) 604E. The radio control functions may include, but are not limited to, signal modulation/demodulation, encoding/decoding, radio frequency shifting, etc. In some embodiments, modulation/demodulation circuitry of the baseband circuitry 604 may include Fast-Fourier Transform (FFT), precoding, or constellation

mapping/demapping functionality. In some embodiments, encoding/decoding circuitry of the baseband circuitry 604 may include convolution, tail-biting

convolution, turbo, Viterbi, or Low Density Parity Check (LDPC) encoder/decoder functionality. Embodiments of modulation/demodulation and encoder/decoder functionality are not limited to these examples and may include other suitable functionality in other embodiments.

[0113] In some embodiments, the baseband circuitry 604 may include one or more audio digital signal processor(s) (DSP) 604F. The audio DSP(s) 604F may be include elements for compression/decompression and echo cancellation and may include other suitable processing elements in other embodiments. Components of the baseband circuitry may be suitably combined in a single chip, a single chipset, or disposed on a same circuit board in some embodiments. In some embodiments, some or all of the constituent components of the baseband circuitry 604 and the application circuitry 602 may be implemented together such as, for example, on a system on a chip (SOC).

[0114] In some embodiments, the baseband circuitry 604 may provide for communication compatible with one or more radio technologies. For example, in some embodiments, the baseband circuitry 604 may support communication with an evolved universal terrestrial radio access network (EUTRAN) or other wireless metropolitan area networks (WMAN), a wireless local area network (WLAN), or a wireless personal area network (WPAN). Embodiments in which the baseband circuitry 604 is configured to support radio communications of more than one wireless protocol may be referred to as multi-mode baseband circuitry. [0115] RF circuitry 606 may enable communication with wireless networks using modulated electromagnetic radiation through a non-solid medium. In various embodiments, the RF circuitry 606 may include switches, filters, amplifiers, etc. to facilitate the communication with the wireless network. The RF circuitry 606 may include a receive signal path which may include circuitry to down-convert RF signals received from the FEM circuitry 608 and provide baseband signals to the baseband circuitry 604. RF circuitry 606 may also include a transmit signal path which may include circuitry to up-convert baseband signals provided by the baseband circuitry 604 and provide RF output signals to the FEM circuitry 608 for transmission.

[0116] In some embodiments, the receive signal path of the RF circuitry 606 may include mixer circuitry 606A, amplifier circuitry 606B and filter circuitry 606C. In some embodiments, the transmit signal path of the RF circuitry 606 may include filter circuitry 606C and mixer circuitry 606A. RF circuitry 606 may also include

synthesizer circuitry 606D for synthesizing a frequency for use by the mixer circuitry 606A of the receive signal path and the transmit signal path. In some embodiments, the mixer circuitry 606A of the receive signal path may be configured to down- convert RF signals received from the FEM circuitry 608 based on the synthesized frequency provided by synthesizer circuitry 606D. The amplifier circuitry 606B may be configured to amplify the down-converted signals and the filter circuitry 606C may be a low-pass filter (LPF) or band-pass filter (BPF) configured to remove unwanted signals from the down-converted signals to generate output baseband signals.

Output baseband signals may be provided to the baseband circuitry 604 for further processing. In some embodiments, the output baseband signals may be zero- frequency baseband signals, although this is not a requirement. In some

embodiments, the mixer circuitry 606A of the receive signal path may comprise passive mixers, although the scope of the embodiments is not limited in this respect.

[0117] In some embodiments, the mixer circuitry 606A of the transmit signal path may be configured to up-convert input baseband signals based on the synthesized frequency provided by the synthesizer circuitry 606D to generate RF output signals for the FEM circuitry 608. The baseband signals may be provided by the baseband circuitry 604 and may be filtered by the filter circuitry 606C.

[0118] In some embodiments, the mixer circuitry 606A of the receive signal path and the mixer circuitry 606A of the transmit signal path may include two or more mixers and may be arranged for quadrature downconversion and upconversion, respectively. In some embodiments, the mixer circuitry 606A of the receive signal path and the mixer circuitry 606A of the transmit signal path may include two or more mixers and may be arranged for image rejection (e.g., Hartley image rejection). In some embodiments, the mixer circuitry 606A of the receive signal path and the mixer circuitry 606A may be arranged for direct downconversion and direct upconversion, respectively. In some embodiments, the mixer circuitry 606A of the receive signal path and the mixer circuitry 606A of the transmit signal path may be configured for super-heterodyne operation.

[0119] In some embodiments, the output baseband signals and the input baseband signals may be analog baseband signals, although the scope of the embodiments is not limited in this respect. In some alternate embodiments, the output baseband signals and the input baseband signals may be digital baseband signals. In these alternate embodiments, the RF circuitry 606 may include analog-to- digital converter (ADC) and digital-to-analog converter (DAC) circuitry and the baseband circuitry 604 may include a digital baseband interface to communicate with the RF circuitry 606.

[0120] In some dual-mode embodiments, a separate radio integrated circuit (IC) circuitry may be provided for processing signals for each spectrum, although the scope of the embodiments is not limited in this respect.

[0121] In some embodiments, the synthesizer circuitry 606D may be a fractional- N synthesizer or a fractional N/N+1 synthesizer, although the scope of the

embodiments is not limited in this respect as other types of frequency synthesizers may be suitable. For example, synthesizer circuitry 606D may be a delta-sigma synthesizer, a frequency multiplier, or a synthesizer comprising a phase-locked loop with a frequency divider.

[0122] The synthesizer circuitry 606D may be configured to synthesize an output frequency for use by the mixer circuitry 606A of the RF circuitry 606 based on a frequency input and a divider control input. In some embodiments, the synthesizer circuitry 606D may be a fractional N/N+1 synthesizer.

[0123] In some embodiments, frequency input may be provided by a voltage controlled oscillator (VCO), although that is not a requirement. Divider control input may be provided by either the baseband circuitry 604 or the application circuitry 602 (such as an applications processor) depending on the desired output frequency. In some embodiments, a divider control input (e.g., N) may be determined from a lookup table based on a channel indicated by the application circuitry 602.

[0124] Synthesizer circuitry 606D of the RF circuitry 606 may include a divider, a delay-locked loop (DLL), a multiplexer and a phase accumulator. In some

embodiments, the divider may be a dual modulus divider (DMD) and the phase accumulator may be a digital phase accumulator (DPA). In some embodiments, the DMD may be configured to divide the input signal by either N or N+1 (e.g., based on a carry out) to provide a fractional division ratio. In some example embodiments, the DLL may include a set of cascaded, tunable, delay elements, a phase detector, a charge pump and a D-type flip-flop. In these embodiments, the delay elements may be configured to break a VCO period up into Nd equal packets of phase, where Nd is the number of delay elements in the delay line. In this way, the DLL provides negative feedback to help ensure that the total delay through the delay line is one VCO cycle.

[0125] In some embodiments, the synthesizer circuitry 606D may be configured to generate a carrier frequency as the output frequency, while in other embodiments, the output frequency may be a multiple of the carrier frequency (e.g., twice the carrier frequency, four times the carrier frequency) and used in conjunction with quadrature generator and divider circuitry to generate multiple signals at the carrier frequency with multiple different phases with respect to each other. In some embodiments, the output frequency may be a local oscillator (LO) frequency (fLO). In some embodiments, the RF circuitry 606 may include an IQ/polar converter.

[0126] FEM circuitry 608 may include a receive signal path which may include circuitry configured to operate on RF signals received from one or more antennas 610, amplify the received signals and provide the amplified versions of the received signals to the RF circuitry 606 for further processing. The FEM circuitry 608 may also include a transmit signal path which may include circuitry configured to amplify signals for transmission provided by the RF circuitry 606 for transmission by one or more of the one or more antennas 610. In various embodiments, the amplification through the transmit or receive signal paths may be done solely in the RF circuitry 606, solely in the FEM circuitry 608, or in both the RF circuitry 606 and the FEM circuitry 608.

[0127] In some embodiments, the FEM circuitry 608 may include a TX/RX switch to switch between transmit mode and receive mode operation. The FEM circuitry 608 may include a receive signal path and a transmit signal path. The receive signal path of the FEM circuitry 608 may include a low noise amplifier (LNA) to amplify received RF signals and provide the amplified received RF signals as an output (e.g., to the RF circuitry 606). The transmit signal path of the FEM circuitry 608 may include a power amplifier (PA) to amplify input RF signals (e.g., provided by the RF circuitry 606), and one or more filters to generate RF signals for subsequent transmission (e.g., by one or more of the one or more antennas 610).

[0128] In some embodiments, the PMC 612 may manage power provided to the baseband circuitry 604. In particular, the PMC 612 may control power-source selection, voltage scaling, battery charging, or DC-to-DC conversion. The PMC 612 may often be included when the device 600 is capable of being powered by a battery, for example, when the device 600 is included in a UE. The PMC 612 may increase the power conversion efficiency while providing desirable implementation size and heat dissipation characteristics.

[0129] FIG. 6 shows the PMC 612 coupled only with the baseband circuitry 604. However, in other embodiments, the PMC 612 may be additionally or alternatively coupled with, and perform similar power management operations for, other components such as, but not limited to, the application circuitry 602, the RF circuitry 606, or the FEM circuitry 608.

[0130] In some embodiments, the PMC 612 may control, or otherwise be part of, various power saving mechanisms of the device 600. For example, if the device 600 is in an RRC_Connected state, where it is still connected to the RAN node as it expects to receive traffic shortly, then it may enter a state known as Discontinuous Reception Mode (DRX) after a period of inactivity. During this state, the device 600 may power down for brief intervals of time and thus save power.

[0131] If there is no data traffic activity for an extended period of time, then the device 600 may transition off to an RRCJdle state, where it disconnects from the network and does not perform operations such as channel quality feedback, handover, etc. The device 600 goes into a very low power state and it performs paging where again it periodically wakes up to listen to the network and then powers down again. The device 600 may not receive data in this state, and in order to receive data, it transitions back to an RRC_Connected state.

[0132] An additional power saving mode may allow a device to be unavailable to the network for periods longer than a paging interval (ranging from seconds to a few hours). During this time, the device is totally unreachable to the network and may power down completely. Any data sent during this time incurs a large delay and it is assumed the delay is acceptable.

[0133] Processors of the application circuitry 602 and processors of the baseband circuitry 604 may be used to execute elements of one or more instances of a protocol stack. For example, processors of the baseband circuitry 604, alone or in combination, may be used to execute Layer 3, Layer 2, or Layer 1 functionality, while processors of the application circuitry 602 may utilize data (e.g., packet data) received from these layers and further execute Layer 4 functionality (e.g.,

transmission communication protocol (TCP) and user datagram protocol (UDP) layers). As referred to herein, Layer 3 may comprise a radio resource control (RRC) layer, described in further detail below. As referred to herein, Layer 2 may comprise a medium access control (MAC) layer, a radio link control (RLC) layer, and a packet data convergence protocol (PDCP) layer, described in further detail below. As referred to herein, Layer 1 may comprise a physical (PHY) layer of a UE/RAN node, described in further detail below.

[0134] FIG. 7 illustrates example interfaces of baseband circuitry in accordance with some embodiments. As discussed above, the baseband circuitry 604 of FIG. 6 may comprise processors 604A-604E and a memory 604G utilized by said processors. Each of the processors 604A-604E may include a memory interface, 704A-704E, respectively, to send/receive data to/from the memory 604G.

[0135] The baseband circuitry 604 may further include one or more interfaces to communicatively couple to other circuitries/devices, such as a memory interface 712 (e.g., an interface to send/receive data to/from memory external to the baseband circuitry 604), an application circuitry interface 714 (e.g., an interface to send/receive data to/from the application circuitry 602 of FIG. 6), an RF circuitry interface 716 (e.g., an interface to send/receive data to/from RF circuitry 606 of FIG. 6), a wireless hardware connectivity interface 718 (e.g., an interface to send/receive data to/from Near Field Communication (NFC) components, Bluetooth® components (e.g., Bluetooth® Low Energy), Wi-Fi® components, and other communication

components), and a power management interface 720 (e.g., an interface to send/receive power or control signals to/from the PMC 612.

[0136] FIG. 8 is a block diagram illustrating components, according to some example embodiments, able to read instructions from a machine-readable or computer-readable medium (e.g., a non-transitory machine-readable storage medium) and perform any one or more of the methodologies discussed herein.

Specifically, FIG. 8 shows a diagrammatic representation of hardware resources 800 including one or more processors (or processor cores) 810, one or more

memory/storage devices 820, and one or more communication resources 830, each of which may be communicatively coupled via a bus 840. For embodiments where node virtualization (e.g., NFV) is utilized, a hypervisor 802 may be executed to provide an execution environment for one or more network slices/sub-slices to utilize the hardware resources 800.

[0137] The processors 810 (e.g., a central processing unit (CPU), a reduced instruction set computing (RISC) processor, a complex instruction set computing (CISC) processor, a graphics processing unit (GPU), a digital signal processor (DSP) such as a baseband processor, an application specific integrated circuit (ASIC), a radio-frequency integrated circuit (RFIC), another processor, or any suitable combination thereof) may include, for example, a processor 812 and a processor 814.

[0138] The memory/storage devices 820 may include main memory, disk storage, or any suitable combination thereof. The memory/storage devices 820 may include, but are not limited to any type of volatile or non-volatile memory such as dynamic random access memory (DRAM), static random-access memory (SRAM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), Flash memory, solid-state storage, etc.

[0139] The communication resources 830 may include interconnection or network interface components or other suitable devices to communicate with one or more peripheral devices 804 or one or more databases 806 via a network 808. For example, the communication resources 830 may include wired communication components (e.g., for coupling via a Universal Serial Bus (USB)), cellular

communication components, NFC components, Bluetooth® components (e.g., Bluetooth® Low Energy), Wi-Fi® components, and other communication

components.

[0140] Instructions 850 may comprise software, a program, an application, an applet, an app, or other executable code for causing at least any of the processors 810 to perform any one or more of the methodologies discussed herein. The instructions 850 may reside, completely or partially, within at least one of the processors 810 (e.g., within the processor's cache memory), the memory/storage devices 820, or any suitable combination thereof. Furthermore, any portion of the instructions 850 may be transferred to the hardware resources 800 from any combination of the peripheral devices 804 or the databases 806. Accordingly, the memory of processors 810, the memory/storage devices 820, the peripheral devices 804, and the databases 806 are examples of computer-readable and machine- readable media.

[0141] The following are examples of further embodiments.

[0142] Example 1 is an apparatus for a user equipment (UE), comprising a memory interface and a baseband processor. The memory interface to send or receive, to or from a memory device, a radio resource control (RRC) connection reconfiguration message from a source cell in a wireless network. The baseband processor to: decode the RRC connection reconfiguration message to obtain a mobility control information element comprising parameters for network controlled mobility of the UE to or within the wireless network; in response to the mobility control information element, initiate a handover procedure from the source cell to a target cell, a first portion of the handover procedure including a determination that make-before-break handover is configured; and in response to the determination that make-before-break handover is configured: cause the UE to continue uplink (UL) transmission and downlink (DL) reception with the source cell until an initiation of radio frequency (RF) re-tuning of the UE for connection to the target cell; select a time to stop the UL transmission and the DL reception of the UE with the source cell to initiate the RF re-tuning; and after the UL transmission and the DL reception of the UE with the source cell stops, perform a second portion of the handover procedure to connect to the target cell.

[0143] Example 2 is the apparatus of Example 1 , wherein the second portion of the handover procedure includes a medium access control (MAC) reset after the UE stops the UL transmission and DL reception with the source cell.

[0144] Example 3 is the apparatus of any of Examples 1 -2, wherein the baseband processor is configured to select the time to stop the UL transmission and the DL reception of the UE with the source cell based on a determination that the source cell and the target cell comprise different bandwidths. [0145] Example 4 is the apparatus of any of Examples 1 -2, wherein the baseband processor is configured to select the time to stop the UL transmission and the DL reception of the UE with the source cell to reduce service interruption.

[0146] Example 5 is the apparatus of any of Examples 1 -4, wherein the mobility control information element further comprises a random access channel (RACH) skip parameter to indicate whether a random access procedure for a target primary cell (PCell) is skipped; and wherein the baseband processor is further configured to, in response to the determination that the make-before-break handover is configured, control the UE to continue the UL transmission and the downlink reception with the source cell before a transmission through: if the RACH skip parameter is not configured, a physical random access channel (PRACH) to the target PCell; and if the RACH skip parameter is configured, a physical uplink shared channel (PUSCH) to the target PCell.

[0147] Example 6 is the apparatus of any of Examples 1 -5, wherein the mobility control information element comprises a make-before-break parameter used in the determination that the make-before-break handover is configured.

[0148] Example 7 is the apparatus of any of Examples 1 -6, wherein the UE is configured for dual connectivity, and wherein the baseband processor is further configured to: determine that the RRC connection reconfiguration message includes a secondary cell group (SCG) reconfiguration parameter; and in response to the SCG reconfiguration parameter, start synchronizing to a DL of a target primary secondary cell (PSCell) in the first portion of the handover procedure.

[0149] Example 8 is the apparatus of Example 7, wherein the baseband processor is further configured to: determine that the mobility control information element indicates that a make-before-break SCG parameter is configured; and in response to the determination that the make-before-break SCG parameter is configured, perform at least a portion of an SCG reconfiguration procedure after the UL transmission and the DL reception of the UE with the source cell stops.

[0150] Example 9 is the apparatus of Example 8, wherein the mobility control information element further comprises a random access channel (RACH) skip SCG parameter to indicate whether a random access procedure for the target PSCell is skipped; and wherein the baseband processor is further configured to, in response to the determination that the make-before-break SCG parameter is configured, control the UE to continue the UL transmission and the downlink reception with the source cell before a transmission through: if the RACH skip SCG parameter is not configured, a physical random access channel (PRACH) to the target PSCell; and if the RACH skip SCG parameter is configured, a physical uplink shared channel (PUSCH) to the target PSCell.

[0151] Example 10 is a machine readable storage medium including machine- readable instructions, when executed by one or more processors of an evolved node B (eNB), to: determine, based at least in part on a measurement report from a user equipment (UE), to hand off the UE to a target eNB; generate a handover request message for the target eNB; process, in response to the handover request message, a handover request acknowledge message from the target eNB comprising information to forward to the UE in a radio resource control (RRC) message;

generate the RRC message to configure the UE for make-before-break handover, wherein the eNB maintains a connection with the UE to allow, without expectation, uplink (UL) and downlink (DL) communication with the UE during make-before-break handover to the target eNB; and process a UE context release message from the target eNB to indicate success of the make-before-break handover and to release resources associated to the UE.

[0152] Example 1 1 is the machine readable storage medium of Example 10, wherein the machine-readable instructions are further to determine a time, during the make-before-break handover, to stop the DL communication to the UE.

[0153] Example 12 is the machine readable storage medium of any of Examples 10-1 1 , wherein to configure the UE for the make-before-break handover, the machine-readable instructions are further to: encode the RRC message as an RRC connection reconfiguration message including a mobility control information element comprising parameters for network controlled mobility of the UE to the target eNB; and set a make-before-break parameter in the mobility control information element to indicate to the UE that the make-before-break handover is configured.

[0154] Example 13 is the machine readable storage medium of Example 12, wherein the machine-readable instructions are further to set a random access channel (RACH) skip parameter in the mobility control information element to indicate to the UE whether a random access procedure for a target primary cell (PCell) is to be skipped.

[0155] Example 14 is a machine readable storage medium including machine- readable instructions, when executed by one or more processors of a user equipment (UE) configured for dual connectivity, to: initiate a secondary cell group (SCG) reconfiguration procedure; determine that the UE is configured for make- before-break SCG reconfiguration; and in response to the determination: start synchronization to a downlink (DL) of a target primary secondary cell (PSCell); and perform at least a portion of the SCG reconfiguration procedure after the UE stops uplink (UL) transmission and DL reception with one or more source cells.

[0156] Example 15 is the machine readable storage medium of Example 14, wherein the machine-readable instructions are further to autonomously select a time to stop the UL transmission and the DL reception of the UE with the source cell to initiate radio frequency (RF) re-tuning for connection to a target cell.

[0157] Example 16 is the machine readable storage medium of any of Examples 14-15, wherein to initiate the SCG reconfiguration procedure, the machine-readable instructions are further to: decode a radio resource control (RRC) connection reconfiguration message from a master evolved node B (MeNB) to obtain an SCG mobility control information parameter; and in response to the SCG mobility control information parameter and the SCG make-before-break parameter, initiate the SCG reconfiguration procedure.

[0158] Example 17 is the machine readable storage medium of Example 16, wherein the machine-readable instructions are further to obtain, from the RRC connection reconfiguration message, an SCG make-before-break parameter set to indicate that the UE is configured for the make-before-break SCG reconfiguration.

[0159] Example 18 is the machine readable storage medium of Example 16, wherein the machine-readable instructions are further to: obtain, from the RRC connection reconfiguration message, a random access channel (RACH) skip SCG parameter to indicate whether a random access procedure for the target PSCell is skipped; and in response to the determination that the make-before-break SCG parameter is configured, control the UE to continue the UL transmission and the downlink reception with the one or more source cells before a transmission through: if the RACH skip SCG parameter is not configured, a physical random access channel (PRACH) to the target PSCell; and if the RACH skip SCG parameter is configured, a physical uplink shared channel (PUSCH) to the target PSCell.

[0160] Example 19 is the machine readable storage medium of any of Examples 14-18, wherein to perform at least the portion of the SCG reconfiguration procedure after the UE stops, the machine-readable instructions are further to perform an SCG medium access control (MAC) reset after the UE stops the UL transmission and DL reception with the one or more source cells.

[0161] Example 20 is the machine readable storage medium of any of Examples 14-19, wherein the machine-readable instructions are further to select a time to stop the UL transmission and the DL reception of the UE with the one or more source cells based on a determination that the source cell and the target PSCell

communicate with the UE using different bandwidths.

[0162] Example 21 is a method for a user equipment (UE), comprising:

processing a radio resource control (RRC) message, received from a source cell in a wireless network, implying handover of the UE from the source cell to a target cell; in response to the RRC message, initiating a make-before-break handover procedure from the source cell to the target cell; causing the UE to continue uplink (UL) transmission and downlink (DL) reception with the source cell until an initiation of radio frequency (RF) re-tuning of the UE for connection to the target cell; and selecting a time to stop the UL transmission and the DL reception of the UE with the source cell to initiate the RF re-tuning.

[0163] Example 22 is the method of Example 21 , further comprising selecting the time to stop the UL transmission and the DL reception of the UE with the source cell based on a determination that the source cell and the target cell comprise different bandwidths.

[0164] Example 23 is the method of Example 21 , further comprising selecting the time to stop the UL transmission and the DL reception of the UE with the source cell to reduce service interruption.

[0165] Example 24 is the method of any of Examples 21 -23, wherein selecting the time to stop the UL transmission and the DL reception comprises selecting the time during a secondary cell group (SCG) change.

[0166] Example 25 is the method of any of Examples 21 -24, further comprising performing a random access channel (RACH)-less connection to the target cell.

[0167] Example 26 is a method for a user equipment (UE), comprising: decoding the radio resource control (RRC) connection reconfiguration message to obtain a mobility control information element comprising parameters for network controlled mobility of the UE to or within a wireless network; in response to the mobility control information element, initiating a handover procedure from a source cell to a target cell, a first portion of the handover procedure including a determination that make- before-break handover is configured; and in response to the determination that make-before-break handover is configured: causing the UE to continue uplink (UL) transmission and downlink (DL) reception with the source cell until an initiation of radio frequency (RF) re-tuning of the UE for connection to the target cell; selecting a time to stop the UL transmission and the DL reception of the UE with the source cell to initiate the RF re-tuning; and after the UL transmission and the DL reception of the UE with the source cell stops, performing a second portion of the handover procedure to connect to the target cell.

[0168] Example 27 is the method of Example 26, wherein the second portion of the handover procedure includes a medium access control (MAC) reset after the UE stops the UL transmission and DL reception with the source cell.

[0169] Example 28 is the method of any of Examples 26-27, further comprising selecting the time to stop the UL transmission and the DL reception of the UE with the source cell based on a determination that the source cell and the target cell comprise different bandwidths.

[0170] Example 29 is the method of any of Examples 26-27, further comprising selecting the time to stop the UL transmission and the DL reception of the UE with the source cell to reduce service interruption.

[0171] Example 30 is the method of any of Examples 26-29, wherein the mobility control information element further comprises a random access channel (RACH) skip parameter to indicate whether a random access procedure for a target primary cell (PCell) is skipped; and wherein the method further comprises, in response to the determination that the make-before-break handover is configured, controlling the UE to continue the UL transmission and the downlink reception with the source cell before a transmission through: if the RACH skip parameter is not configured, a physical random access channel (PRACH) to the target PCell; and if the RACH skip parameter is configured, a physical uplink shared channel (PUSCH) to the target PCell.

[0172] Example 31 is the method of any of Examples 26-30, wherein the mobility control information element comprises a make-before-break parameter used in the determination that the make-before-break handover is configured.

[0173] Example 32 is the method of any of Examples 26-31 , wherein the UE is configured for dual connectivity, and wherein the method further comprises:

determining that the RRC connection reconfiguration message includes a secondary cell group (SCG) reconfiguration parameter; and in response to the SCG reconfiguration parameter, starting synchronization to a DL of a target primary secondary cell (PSCell) in the first portion of the handover procedure.

[0174] Example 33 is the method of Example 32, further comprising: determining that the mobility control information element indicates that a make-before-break SCG parameter is configured; and in response to the determination that the make-before- break SCG parameter is configured, performing at least a portion of an SCG reconfiguration procedure after the UL transmission and the DL reception of the UE with the source cell stops.

[0175] Example 34 is the method of Example 33, wherein the mobility control information element further comprises a random access channel (RACH) skip SCG parameter to indicate whether a random access procedure for the target PSCell is skipped; and wherein the method further comprises, in response to the determination that the make-before-break SCG parameter is configured, controlling the UE to continue the UL transmission and the downlink reception with the source cell before a transmission through: if the RACH skip SCG parameter is not configured, a physical random access channel (PRACH) to the target PSCell; and if the RACH skip SCG parameter is configured, a physical uplink shared channel (PUSCH) to the target PSCell.

[0176] Example 35 is a method for an evolved node B (eNB), comprising:

determining, based at least in part on a measurement report from a user equipment (UE), to hand off the UE to a target eNB; generating a handover request message for the target eNB; processing, in response to the handover request message, a handover request acknowledge message from the target eNB comprising information to forward to the UE in a radio resource control (RRC) message; generating the RRC message to configure the UE for make-before-break handover, wherein the eNB maintains a connection with the UE to allow, without expectation, uplink (UL) and downlink (DL) communication with the UE during make-before-break handover to the target eNB; and processing a UE context release message from the target eNB to indicate success of the make-before-break handover and to release resources associated to the UE.

[0177] Example 36 is the method of Example 35, further comprising determining a time, during the make-before-break handover, to stop the DL communication to the UE. [0178] Example 37 is the method of any of Examples 35-36, wherein to configure the UE for the make-before-break handover, the method further comprises: encoding the RRC message as an RRC connection reconfiguration message including a mobility control information element comprising parameters for network controlled mobility of the UE to the target eNB; and setting a make-before-break parameter in the mobility control information element to indicate to the UE that the make-before- break handover is configured.

[0179] Example 38 is the method of Example 37, further comprising setting a random access channel (RACH) skip parameter in the mobility control information element to indicate to the UE whether a random access procedure for a target primary cell (PCell) is to be skipped.

[0180] Example 39 is a method for a user equipment (UE) configured for dual connectivity, comprising: initiating a secondary cell group (SCG) reconfiguration procedure; determining that the UE is configured for make-before-break SCG reconfiguration; and in response to the determination: starting synchronization to a downlink (DL) of a target primary secondary cell (PSCell); and performing at least a portion of the SCG reconfiguration procedure after the UE stops uplink (UL) transmission and DL reception with one or more source cells.

[0181] Example 40 is the method of Example 39, further comprising

autonomously selecting a time to stop the UL transmission and the DL reception of the UE with the source cell to initiate radio frequency (RF) re-tuning for connection to a target cell.

[0182] Example 41 is the method of any of Examples 39-40-, wherein to initiate the SCG reconfiguration procedure, the method further comprises: decoding a radio resource control (RRC) connection reconfiguration message from a master evolved node B (MeNB) to obtain an SCG mobility control information parameter; and in response to the SCG mobility control information parameter and the SCG make- before-break parameter, initiating the SCG reconfiguration procedure.

[0183] Example 42 is the method of Example 41 , wherein the method further comprises obtaining, from the RRC connection reconfiguration message, an SCG make-before-break parameter set to indicate that the UE is configured for the make- before-break SCG reconfiguration.

[0184] Example 43 is the method of Example 41 , further comprising: obtaining, from the RRC connection reconfiguration message, a random access channel (RACH) skip SCG parameter to indicate whether a random access procedure for the target PSCell is skipped; and in response to the determination that the make-before- break SCG parameter is configured, controlling the UE to continue the UL

transmission and the downlink reception with the one or more source cells before a transmission through: if the RACH skip SCG parameter is not configured, a physical random access channel (PRACH) to the target PSCell; and if the RACH skip SCG parameter is configured, a physical uplink shared channel (PUSCH) to the target PSCell.

[0185] Example 44 is the method of any of Examples 39-43, wherein to perform at least the portion of the SCG reconfiguration procedure after the UE stops, the method further comprises performing an SCG medium access control (MAC) reset after the UE stops the UL transmission and DL reception with the one or more source cells.

[0186] Example 45 is the method of any of Examples 39-44, further comprising selecting a time to stop the UL transmission and the DL reception of the UE with the one or more source cells based on a determination that the source cell and the target PSCell communicate with the UE using different bandwidths.

[0187] Example 46 is an apparatus comprising a means to perform a method as exemplified in any of Examples 21 -45.

[0188] Example 47 is a machine-readable medium including code, when executed, to cause a machine to perform the method of any one of Examples 21 -45.

[0189] Example 48 is an apparatus for an evolved node B (eNB), comprising: a memory device to store a measurement report from a user equipment (UE); and one or more baseband processors to: determine, based at least in part on a

measurement report from a user equipment (UE), to hand off the UE to a target eNB; generate a handover request message for the target eNB; process, in response to the handover request message, a handover request acknowledge message from the target eNB comprising information to forward to the UE in a radio resource control (RRC) message; generate the RRC message to configure the UE for make-before- break handover, wherein the eNB maintains a connection with the UE to allow uplink (UL) and downlink (DL) communication with the UE during make-before-break handover to the target eNB, wherein the eNB does not wait for a response or feedback from the UE during the make-before-break handover; and process a UE context release message from the target eNB to indicate success of the make- before-break handover and to release resources associated to the UE.

[0190] Example 49 is the apparatus of Example 48, wherein the one or more baseband processors are further to determine a time, during the make-before-break handover, to stop the DL communication to the UE.

[0191] Example 50 is the apparatus of any of Examples 48-49, wherein to configure the UE for the make-before-break handover, the one or more baseband processors are further to: encode the RRC message as an RRC connection reconfiguration message including a mobility control information element comprising parameters for network controlled mobility of the UE to the target eNB; and set a make-before-break parameter in the mobility control information element to indicate to the UE that the make-before-break handover is configured.

[0192] Example 51 is the apparatus of Example 50, wherein the one or more baseband processors are further to set a random access channel (RACH) skip parameter in the mobility control information element to indicate to the UE whether a random access procedure for a target primary cell (PCell) is to be skipped.

[0193] Example 52 is an apparatus for a user equipment (UE) configured for dual connectivity, comprising: a memory to store a secondary cell group (SCG) identifier; and one or more baseband processors to: initiate an SCG reconfiguration procedure; determine that the UE is configured for make-before-break secondary cell group (SCG) reconfiguration; and in response to the determination: start synchronization to a downlink (DL) of a target primary secondary cell (PSCell) corresponding to the SCG identifier; and perform at least a portion of the SCG reconfiguration procedure after the UE stops uplink (UL) transmission and DL reception with one or more source cells.

[0194] Example 53 is the apparatus of Example 52, wherein the one or more baseband processors are further to autonomously select a time to stop the UL transmission and the DL reception of the UE with the source cell to initiate radio frequency (RF) re-tuning for connection to a target cell.

[0195] Example 54 is the apparatus of any of Examples 52-53, wherein to initiate the SCG reconfiguration procedure, the one or more baseband processors are further to: decode a radio resource control (RRC) connection reconfiguration message from a master evolved node B (MeNB) to obtain an SCG mobility control information parameter; and in response to the SCG mobility control information parameter and the SCG make-before-break parameter, initiate the SCG reconfiguration procedure.

[0196] Example 55 is the apparatus of Example 54, wherein the one or more baseband processors are further to obtain, from the RRC connection reconfiguration message, an SCG make-before-break parameter set to indicate that the UE is configured for the make-before-break SCG reconfiguration.

[0197] Example 56 is the apparatus of Example 54, wherein the one or more baseband processors are further to: obtain, from the RRC connection

reconfiguration message, a random access channel (RACH) skip SCG parameter to indicate whether a random access procedure for the target PSCell is skipped; and in response to the determination that the make-before-break SCG parameter is configured, control the UE to continue the UL transmission and the downlink reception with the one or more source cells before a transmission through: if the RACH skip SCG parameter is not configured, a physical random access channel (PRACH) to the target PSCell; and if the RACH skip SCG parameter is configured, a physical uplink shared channel (PUSCH) to the target PSCell.

[0198] Example 57 is the apparatus of any of Examples 52-56, wherein to perform at least the portion of the SCG reconfiguration procedure after the UE stops, the one or more baseband processors are further to perform an SCG medium access control (MAC) reset after the UE stops the UL transmission and DL reception with the one or more source cells.

[0199] Example 58 is the apparatus of any of Examples 52-57, wherein the one or more baseband processors are further to select a time to stop the UL transmission and the DL reception of the UE with the one or more source cells based on a determination that the source cell and the target PSCell communicate with the UE using different bandwidths.

[0200] It will be understood by those having skill in the art that many changes may be made to the details of the above-described embodiments without departing from the underlying principles of the disclosure. The scope of the present disclosure, therefore, be determined only by the following claims.

Claims

1 . An apparatus for a user equipment (UE), comprising:

a memory interface to send or receive, to or from a memory device, a radio resource control (RRC) connection reconfiguration message from a source cell in a wireless network; and

a baseband processor to:

decode the RRC connection reconfiguration message to obtain a mobility control information element comprising parameters for network controlled mobility of the UE to or within the wireless network;

in response to the mobility control information element, initiate a handover procedure from the source cell to a target cell, a first portion of the handover procedure including a determination that make-before-break handover is configured; and

in response to the determination that make-before-break handover is configured:

cause the UE to continue uplink (UL) transmission and downlink (DL) reception with the source cell until an initiation of radio frequency (RF) re-tuning of the UE for connection to the target cell;

select a time to stop the UL transmission and the DL reception of the UE with the source cell to initiate the RF re-tuning; and

after the UL transmission and the DL reception of the UE with the source cell stops, perform a second portion of the handover procedure to connect to the target cell.

2. The apparatus of claim 1 , wherein the second portion of the handover procedure includes a medium access control (MAC) reset after the UE stops the UL transmission and DL reception with the source cell.

3. The apparatus of claim 1 , wherein the baseband processor is configured to select the time to stop the UL transmission and the DL reception of the UE with the source cell based on a determination that the source cell and the target cell comprise different bandwidths.

4. The apparatus of claim 1 , wherein the baseband processor is configured to select the time to stop the UL transmission and the DL reception of the UE with the source cell to reduce service interruption.

5. The apparatus of any of claims 1 -4, wherein the mobility control information element further comprises a random access channel (RACH) skip parameter to indicate whether a random access procedure for a target primary cell (PCell) is skipped; and

wherein the baseband processor is further configured to, in response to the determination that the make-before-break handover is configured, control the UE to continue the UL transmission and the downlink reception with the source cell before a transmission through:

if the RACH skip parameter is not configured, a physical random access channel (PRACH) to the target PCell; and

if the RACH skip parameter is configured, a physical uplink shared channel (PUSCH) to the target PCell.

6. The apparatus of any of claims 1 -4, wherein the mobility control information element comprises a make-before-break parameter used in the determination that the make-before-break handover is configured.

7. The apparatus of any of claims 1 -4, wherein the UE is configured for dual connectivity, and wherein the baseband processor is further configured to:

determine that the RRC connection reconfiguration message includes a secondary cell group (SCG) reconfiguration parameter; and

in response to the SCG reconfiguration parameter, start synchronizing to a DL of a target primary secondary cell (PSCell) in the first portion of the handover procedure.

8. The apparatus of claim 7, wherein the baseband processor is further configured to:

determine that the mobility control information element indicates that a make- before-break SCG parameter is configured; and

in response to the determination that the make-before-break SCG parameter is configured, perform at least a portion of an SCG reconfiguration procedure after the UL transmission and the DL reception of the UE with the source cell stops.

9. The apparatus of claim 8, wherein the mobility control information element further comprises a random access channel (RACH) skip SCG parameter to indicate whether a random access procedure for the target PSCell is skipped; and

wherein the baseband processor is further configured to, in response to the determination that the make-before-break SCG parameter is configured, control the UE to continue the UL transmission and the downlink reception with the source cell before a transmission through:

if the RACH skip SCG parameter is not configured, a physical random access channel (PRACH) to the target PSCell; and

if the RACH skip SCG parameter is configured, a physical uplink shared channel (PUSCH) to the target PSCell.

10. A machine readable storage medium including machine-readable instructions, when executed by one or more processors of an evolved node B (eNB), to:

determine, based at least in part on a measurement report from a user equipment (UE), to hand off the UE to a target eNB;

generate a handover request message for the target eNB;

process, in response to the handover request message, a handover request acknowledge message from the target eNB comprising information to forward to the UE in a radio resource control (RRC) message;

generate the RRC message to configure the UE for make-before-break handover, wherein the eNB maintains a connection with the UE to allow, without expectation, uplink (UL) and downlink (DL) communication with the UE during make- before-break handover to the target eNB; and

process a UE context release message from the target eNB to indicate success of the make-before-break handover and to release resources associated to the UE.

1 1 . The machine readable storage medium of claim 10, wherein the machine- readable instructions are further to determine a time, during the make-before-break handover, to stop the DL communication to the UE.

12. The machine readable storage medium of any of claims 10-1 1 , wherein to configure the UE for the make-before-break handover, the machine-readable instructions are further to:

encode the RRC message as an RRC connection reconfiguration message including a mobility control information element comprising parameters for network controlled mobility of the UE to the target eNB; and

set a make-before-break parameter in the mobility control information element to indicate to the UE that the make-before-break handover is configured.

13. The machine readable storage medium of claim 12, wherein the machine- readable instructions are further to set a random access channel (RACH) skip parameter in the mobility control information element to indicate to the UE whether a random access procedure for a target primary cell (PCell) is to be skipped.

14. A machine readable storage medium including machine-readable instructions, when executed by one or more processors of a user equipment (UE) configured for dual connectivity, to:

initiate a secondary cell group (SCG) reconfiguration procedure;

determine that the UE is configured for make-before-break SCG

reconfiguration; and

in response to the determination:

start synchronization to a downlink (DL) of a target primary secondary cell (PSCell); and

perform at least a portion of the SCG reconfiguration procedure after the UE stops uplink (UL) transmission and DL reception with one or more source cells.

15. The machine readable storage medium of claim 14, wherein the machine- readable instructions are further to autonomously select a time to stop the UL transmission and the DL reception of the UE with the source cell to initiate radio frequency (RF) re-tuning for connection to a target cell.

16. The machine readable storage medium of any of claims 14-15, wherein to initiate the SCG reconfiguration procedure, the machine-readable instructions are further to:

decode a radio resource control (RRC) connection reconfiguration message from a master evolved node B (MeNB) to obtain an SCG mobility control information parameter; and

in response to the SCG mobility control information parameter and the SCG make-before-break parameter, initiate the SCG reconfiguration procedure.

17. The machine readable storage medium of claim 16, wherein the machine- readable instructions are further to obtain, from the RRC connection reconfiguration message, an SCG make-before-break parameter set to indicate that the UE is configured for the make-before-break SCG reconfiguration.

18. The machine readable storage medium of claim 16, wherein the machine- readable instructions are further to: obtain, from the RRC connection reconfiguration message, a random access channel (RACH) skip SCG parameter to indicate whether a random access procedure for the target PSCell is skipped; and

in response to the determination that the make-before-break SCG parameter is configured, control the UE to continue the UL transmission and the downlink reception with the one or more source cells before a transmission through:

19. The machine readable storage medium of any of claims 14-15, wherein to perform at least the portion of the SCG reconfiguration procedure after the UE stops, the machine-readable instructions are further to perform an SCG medium access control (MAC) reset after the UE stops the UL transmission and DL reception with the one or more source cells.

20. The machine readable storage medium of any of claims 14-15, wherein the machine-readable instructions are further to select a time to stop the UL transmission and the DL reception of the UE with the one or more source cells based on a determination that the source cell and the target PSCell communicate with the UE using different bandwidths.

21 . A method for a user equipment (UE), comprising:

processing a radio resource control (RRC) message, received from a source cell in a wireless network, implying handover of the UE from the source cell to a target cell;

in response to the RRC message, initiating a make-before-break handover procedure from the source cell to the target cell;

causing the UE to continue uplink (UL) transmission and downlink (DL) reception with the source cell until an initiation of radio frequency (RF) re-tuning of the UE for connection to the target cell; and

selecting a time to stop the UL transmission and the DL reception of the UE with the source cell to initiate the RF re-tuning.

22. The method of claim 21 , further comprising selecting the time to stop the UL transmission and the DL reception of the UE with the source cell based on a determination that the source cell and the target cell comprise different bandwidths.

23. The method of claim 21 , further comprising selecting the time to stop the UL transmission and the DL reception of the UE with the source cell to reduce service interruption.

24. The method of claim 21 , wherein selecting the time to stop the UL transmission and the DL reception comprises selecting the time during a secondary cell group (SCG) change.

25. The method of claim 21 , further comprising performing a random access channel (RACH)-less connection to the target cell.

26. An apparatus comprising a means to perform a method as claimed in any of claims 21 -25.

27. A machine-readable medium including code, when executed, to cause a machine to perform the method of any one of claims 21 -25.