DURING HANDOVER

BACKGROUND

[0001] Wireless mobile communication technology uses various standards and protocols to transmit data between a node (e.g., a transmission station) and a wireless device (e.g., a mobile device). Some wireless devices communicate using orthogonal frequency-division multiple access (OFDMA) in a downlink (DL) transmission and single carrier frequency division multiple access (SC-FDMA) in uplink (UL). Standards and protocols that use orthogonal frequency-division multiplexing (OFDM) for signal transmission include the third generation partnership project (3 GPP) long term evolution (LTE) Release 8, 9, 10, 11, 12 and 13, the Institute of Electrical and Electronics Engineers (IEEE) 802.16 standard (e.g., 802.16e, 802.16m), which is commonly known to industry groups as WiMAX (Worldwide interoperability for Microwave Access), and the IEEE 802.11 standard, which is commonly known to industry groups as WiFi.

[0002] In 3GPP radio access network (RAN) LTE systems (e.g., Release 13 and earlier), the node can be a combination of Evolved Universal Terrestrial Radio Access Network (E-UTRAN) Node Bs (also commonly denoted as evolved Node Bs, enhanced Node Bs, eNodeBs, or eNBs) and Radio Network Controllers (RNCs), which communicates with the wireless device, known as a user equipment (UE). The downlink (DL) transmission can be a communication from the node (e.g., eNodeB) to the wireless device (e.g., UE), and the uplink (UL) transmission can be a communication from the wireless device to the node.

BRIEF DESCRIPTION OF THE DRAWINGS

[0003] Features and advantages of the disclosure will be apparent from the detailed description which follows, taken in conjunction with the accompanying drawings, which together illustrate, by way of example, features of the disclosure; and, wherein:

[0004] FIG. 1 A illustrates a handover scenario in a wireless communication network in accordance with an example; [0005] FIG. IB illustrates another handover scenario in a wireless communication network in accordance with an example;

[0006] FIG. 2 illustrates a user equipment (UE) beam structure for an antenna array in accordance with an example;

[0007] FIG. 3 illustrates signaling to maintain a source eNodeB connection between a user equipment (UE) and a source eNodeB during a handover of the UE to a target eNodeB in accordance with an example;

[0008] FIG. 4 depicts functionality of a user equipment (UE) configured to operate in a massive multiple-input multiple-output (MIMO) system in accordance with an example;

[0009] FIG. 5 depicts additional functionality of a user equipment (UE) configured to operate in a massive multiple-input multiple-output (MIMO) system in accordance with an example;

[0010] FIG. 6 depicts a flowchart of a machine readable storage medium having instructions embodied thereon for maintaining a source eNodeB connection with a source eNodeB at a user equipment (UE) during a handover of the UE in a massive multiple- input multiple-output (MIMO) system in accordance with an example;

[0011] FIG. 7 illustrates an architecture of a wireless network in accordance with an example;

[0012] FIG. 8 illustrates a diagram of a wireless device (e.g., UE) in accordance with an example;

[0013] FIG. 9 illustrates interfaces of baseband circuitry in accordance with an example; and

[0014] FIG. 10 illustrates a diagram of a wireless device (e.g., UE) in accordance with an example.

[0015] Reference will now be made to the exemplary embodiments illustrated, and specific language will be used herein to describe the same. It will nevertheless be understood that no limitation of the scope of the technology is thereby intended. DETAILED DESCRIPTION

[0016] Before the present technology is disclosed and described, it is to be understood that this technology is not limited to the particular structures, process actions, or materials disclosed herein, but is extended to equivalents thereof as would be recognized by those ordinarily skilled in the relevant arts. It should also be understood that terminology employed herein is used for the purpose of describing particular examples only and is not intended to be limiting. The same reference numerals in different drawings represent the same element. Numbers provided in flow charts and processes are provided for clarity in illustrating actions and operations and do not necessarily indicate a particular order or sequence.

EXAMPLE EMBODIMENTS

[0017] An initial overview of technology embodiments is provided below and then specific technology embodiments are described in further detail later. This initial summary is intended to aid readers in understanding the technology more quickly but is not intended to identify key features or essential features of the technology nor is it intended to limit the scope of the claimed subject matter.

[0018] In Long Term Evolution (LTE) wireless communication systems, maintaining a source eNodeB connection between a UE and a source eNodeB during handover of the UE to a target eNodeB can provide various benefits during the handover, such as latency reduction. A data interruption during the handover can be reduced by not releasing the source eNodeB connection to the source eNodeB until the handover is completed at the target eNodeB. In addition, maintaining the source eNodeB connection during the handover can enable the UE to return back to the source eNodeB if the handover to the target eNodeB fails. In LTE wireless communication systems, an increased number of radio frequency (RF) chains can be used to support simultaneous reception from the source eNodeB and the target eNodeB on a same frequency resource. A time division multiplexing (TDM) mechanism can be used by the UE to transmit in an uplink to the source eNodeB and the target eNodeB.

[0019] Multiple-input multiple-output (MIMO) antenna technology has been incorporated into wireless broadband standards, such as 3GPP LTE and Wi-Fi. When a transmitter/receiver is equipped with an increased number of antennas, there can be more possible signal paths and improved performance in terms of data rate and link reliability. Massive MIMO (also known as large-scale antenna systems, very large MIMO, hyper MIMO or full-dimension MIMO) utilizes a very large number of service antennas (e.g., hundreds or thousands) that operate fully coherently and adaptively. The increased number of antennas can focus the transmission and reception of signal energy into smaller regions of space, which can provide improvements in throughput and energy efficiency. Massive MIMO can be used with time division duplex (TDD) operation or frequency division duplex (FDD) operation.

[0020] In Fifth Generation (5G) wireless communication systems that support massive MIMO, both an eNodeB and the UE can maintain a plurality of beams. While the term eNodeB is used here, it is not intended to be limiting. The eNodeB can be configured for 5G, in which the node is commonly referred to as a Next Generation Node B (gNB), as previously discussed. A suitable network beam can be selected at the UE by measuring beam reference signals (BRS), in which different network beams can be applied by the eNodeB. In other words, based on a multiple beams approach, the eNodeB can transmit reference signals with different beams (or BRS), which can be measured by the UE. The UE can select the network beam to correspond with a beam with a highest receiving power observed by the UE. The UE can select a suitable UE beam to track the network beam. Therefore, after an initial access, a network-UE beam pair can be selected by the UE to enable communication between the UE and the eNodeB. An indication of the network-UE beam pair can be provided from the UE to the eNodeB.

[0021] FIG. 1 A illustrates an example of a first handover scenario in a wireless communication network. In the first handover scenario, a user equipment (UE) 102 can be handed over from a source eNodeB 104 to a target eNodeB 106. Initially, the UE 102 can establish a source eNodeB connection with the source eNodeB 104. The source eNodeB connection with the source eNodeB 104 can be established using a network (NW)-UE beam pair, which can include a suitable network beam from the source eNodeB 104 and a suitable UE beam for transmissions (Tx) and receptions (Rx) with the source eNodeB 104. After the handover is initiated, the UE 102 can establish a target eNodeB connection with the target eNodeB 106. The target eNodeB connection with the target eNodeB 106 can be established using a network-UE beam pair, which can include a suitable network beam from the target eNodeB 106 and a suitable UE beam for transmissions (Tx) and receptions (Rx) with the target eNodeB 106. In the first handover scenario, the UE beams used to receive and transmit signals to different eNodeBs (e.g., the source eNodeB 104 and the target eNodeB 106) can come from different antenna arrays. As a result, the UE 102 can maintain a link between each eNodeB independently. For example, each antenna array can have independent radio frequency (RF) chains, such that maintaining the source eNodeB connection during the handover can be supported, irrespective of whether the wireless communication network is synchronized or unsynchronized. A synchronized wireless communication network can have an alignment of timing between the source eNodeB 104 and the target eNodeB 106, whereas an unsynchronized wireless communication network can have a misalignment of timing between the source eNodeB 104 and the target eNodeB 106.

[0022] FIG. IB illustrates an example of a second handover scenario in a wireless communication network. In the second handover scenario, a user equipment (UE) 112 can be handed over from a source eNodeB 114 to a target eNodeB 116. Initially, the UE 112 can establish a source eNodeB connection with the source eNodeB 114. The source eNodeB connection with the source eNodeB 114 can be established using a network (NW)-UE beam pair, which can include a suitable network beam from the source eNodeB 114 and a suitable UE beam for transmissions (Tx) and receptions (Rx) with the source eNodeB 114. After the handover is initiated, the UE 112 can establish a target eNodeB connection with the target eNodeB 116. The target eNodeB connection with the target eNodeB 116 can be established using a network-UE beam pair, which can include a suitable network beam from the target eNodeB 116 and a suitable UE beam for transmissions (Tx) and receptions (Rx) with the target eNodeB 116. In the second handover scenario, the UE beams used to receive and transmit signals to different eNodeBs (e.g., the source eNodeB 114 and the target eNodeB 116) can come from a same antenna array. Alternatively, two selected UE beams can come from different antenna arrays, but the UE 112 may only have two RF chains and enable one antenna array at a time. As a result, in this example, signal transmission and reception from the source eNodeB 114 and the target eNodeB 116 cannot be independent, which increases the UE's difficulty in being able to support maintaining both the source eNodeB connection and the target eNodeB connection during the handover.

[0023] As explained in further detail below, a UE behavior can be defined to enable the UE to maintain both the source eNodeB connection and the target eNodeB connection during the handover. For example, a measurement enhancement and a physical layer signal enhancement for the UE can enable the UE to maintain both the source eNodeB connection and the target eNodeB connection during the handover.

[0024] In one configuration, UE behavior can vary depending on whether the first handover scenario (i.e., the UE is connected to different eNodeBs using UE beams derived from different antenna arrays) or the second handover scenario (i.e., the UE is connected to different eNodeBs using UE beams derived from a same antenna array) is employed in a wireless communication system. For example, in the first handover scenario, as the UE beams are derived from different antenna arrays, the UE can transmit and receive signals to/from the source eNodeB and the target eNodeB independently with the corresponding UE beam. In the second handover scenario, the UE can use only one antenna array to maintain a source eNodeB connection with the source eNodeB and perform a random access channel (RACH) procedure with the target eNodeB over a target eNodeB connection.

[0025] In one example, the UE can send a beam reference signal receiving power (BRS- RP) report to an eNodeB (e.g., the source eNodeB and/or the target eNodeB). When sending the BRS-RP report, the UE can indicate whether the corresponding BRS-RP is measured from an antenna array used to maintain the source eNodeB connection with the source eNodeB. Thus, an indicator can be included to a BRS-RP report context or a neighbor cell BRS-RP report context, and a first value in the indicator can denote that the BRS-RP is measured at the UE from an antenna array used to maintain the source eNodeB connection with the source eNodeB, and a second value in the indicator can denote that the BRS-RP is measured at the UE from another antenna array (e.g., a separate antenna array used to establish the target eNodeB connection with the target eNodeB).

[0026] In one configuration, in a synchronized wireless communication network that employs the second handover scenario (as discussed above), the UE can use antenna port(s) from one polarization to maintain the source eNodeB connection to the source eNodeB with a UE beam to the source eNodeB, and the UE can use antenna port(s) from the other polarization to establish the target eNodeB connection to the target eNodeB with a UE beam to the target eNodeB.

[0027] FIG. 2 illustrates an exemplary user equipment (UE) beam structure for an antenna array. The antenna array can be used by the UE to maintain a source eNodeB connection with a source eNodeB in a wireless communication network. The same antenna array can also be used by the UE to establish a target eNodeB connection with a target eNodeB in the wireless communication network (in accordance with the second handover scenario, as described above). As shown, the UE can use antenna port(s) from one polarization to maintain the source eNodeB connection to the source eNodeB with a UE beam to the source eNodeB, and the UE can use antenna port(s) from the other polarization to establish the target eNodeB connection to the target eNodeB with a UE beam to the target eNodeB. For example, the UE can use the antenna port(s) from the other polarization to accomplish the RACH procedure with the target eNodeB. In other words, antenna port(s) from a first polarization can be used to apply a UE beam to the source eNodeB, and antenna port(s) from a second polarization can be used to apply a UE beam to the target eNodeB.

[0028] In one configuration, in the synchronized wireless communication network, the UE can receive and decode a radio resource control (RRC) message from the source eNodeB, and the RRC message can include an information element (IE) for mobility control information, which can be used to trigger a handover procedure for the UE (e.g., a procedure to hand the UE from the source eNodeB to the target eNodeB). A successful decoding of the RRC message with the mobility control information at the UE can cause both the UE and the source eNodeB to determine a start of the handover procedure. In the second handover scenario (as discussed above), the UE can only report rank 1 channel state information (CSI) when reporting the CSI to the source eNodeB (or the target eNodeB), which indicates that a rank indicator (RI) can be always zero. Alternatively, the RI may not be reported and a channel quality indicator (CQI) and a precoding matrix indicator (PMI) can be measured based on an assumption that the RI is equal to zero when the handover procedure starts.

[0029] In one configuration, in the synchronized wireless communication network, the BRS can be transmitted from the source eNodeB or the target eNodeB from two polarizations, such that the UE can measure a BRS-RP by using one polarization. A number of antenna ports for a BRS sequence in which one network beam is applied can be equal to two, and the two antenna ports can be mapped to antenna elements in different polarizations. In addition, during the handover of the UE from the source eNodeB to the target eNodeB, the UE can transmit uplink data and control signaling to the source eNodeB and the target eNodeB simultaneously by using different polarizations (e.g., different UE transmitting beams can be applied to different polarizations).

[0030] In one configuration, in the synchronized wireless communication network, the UE can transmit in an uplink a demodulation reference signal (DMRS) associated with a Fifth Generation (5G) physical uplink shared channel (xPUSCH) (also referred to as an enhanced physical uplink shared channel (xPUSCH)). The UE can transmit in the uplink the DMRS to the source eNodeB and/or the target eNodeB. In this example, the DMRS can be generated independently for the source eNodeB and the target eNodeB. For example, a DMRS associated with an xPUSCH that is transmitted to the source eNodeB can be configured by the source eNodeB based on a source eNodeB cell identity (ID) or a virtual cell ID, and the DMRS can be transmitted from the UE in the uplink in one antenna port mapped to antenna elements in one polarization. In addition, a DMRS associated with an xPUSCH that is transmitted to the target eNodeB can be configured by the target eNodeB based on a target eNodeB cell identity (ID) or a virtual cell ID (which can be indicated in the RRC message that includes the mobility control information IE), and the DMRS can be transmitted from the UE in the uplink in the other antenna port mapped to antenna elements in the other polarization. In addition, when the xPUSCH is transmitted to the source eNodeB and the target eNodeB on a same resource

simultaneously, an interference cancellation based receiver or a joint receiver can be applied at the source eNodeB or the target eNodeB.

[0031] In one configuration, in the synchronized wireless communication network, a time division multiplexing (TDM) operation can be applied to a UE beam for the second handover scenario (as described above). In the TDM operation, the UE can apply a same UE beam for both polarizations. For example, in a first subset of subframes (e.g., odd subframes), the UE beam can be directed to the source eNodeB, and in a second subset of subframes (e.g., even subframes) (or a remaining subset of subframes), the UE beam can be directed to the target eNodeB. In another example, a source eNodeB gap can be configured for the UE via higher layer signaling, in which the UE can use the UE beam directed to the source eNodeB to communicate with the source eNodeB, and the UE can assume that there is no downlink data or control information to be received from the target eNodeB during the source eNodeB gap.

[0032] In one configuration, in the synchronized wireless communication network, a BRS-RP threshold A _dB can be configured for the UE via higher layer signaling from the source eNodeB. For the target eNodeB, when the BRS-RP of a candidate antenna array is A _dB lower than that of a current antenna array (i.e., an antenna array used to maintain the source eNodeB connection with the source eNodeB), then the UE can switch from the first handover scenario (i. e., using different antenna arrays) to the second handover scenario (i.e., using the same antenna array). In addition, an indicator can be reported by the UE through higher layer signaling to inform the source eNodeB and/or the target eNodeB of the switch from the first handover scenario to the second handover scenario, and then related mobility control information can be subsequently configured for the UE.

[0033] In one configuration, in an unsynchronized network, it can be difficult to transmit or receive signals to/from the source eNodeB and/or the target eNodeB simultaneously due to the misalignment of timing between the source eNodeB and the target eNodeB. In the first handover scenario (as described above), the UE can independently maintain a connection to the source eNodeB and the target eNodeB using separate antenna arrays. Thus, even though the network can be unsynchronized, the UE can transmit/receive signals with different eNodeBs with different timings at the corresponding antenna arrays. In other words, the UE can support different antenna arrays with different timings, which can enable the UE to independently maintain a source eNodeB and connection and a target eNodeB connection with the source eNodeB and the target eNodeB, respectively. In addition, the UE can report a UE capability indicating whether the UE supports having different antenna arrays with different timings. When such a capability is supported at the UE, the UE can maintain the source eNodeB connection during the handover of the UE to the target eNodeB by using one antenna array to connect to the source eNodeB and another antenna array to connect to the target eNodeB (e.g., the other antenna array can be used by the UE to perform a RACH procedure with the target eNodeB).

[0034] In one configuration, in the unsynchronized network, in order to resolve a UE being able to maintain connections to different eNodeBs independently when the connections are formed using one antenna array (in accordance with the second handover scenario, as described above), the UE can employ a TDM mechanism for signal transmissions/receptions. Based on the TDM mechanism, the UE can communicate with both the source eNodeB and the target eNodeB using the single antenna array, and transmissions/receptions with the source eNodeB may not conflict with

transmissions/receptions with the target eNodeB.

[0035] In one example, in the unsynchronized network, a source eNodeB connection gap configuration can be included in a mobility control information IE included in an RRC message transmitted to the UE from the source eNodeB. The source eNodeB connection gap configuration can indicate a time window (or connection gap) when the UE can connect to the source eNodeB. During the time window (or connection gap), the UE can apply a UE beam for the source eNodeB to transmit or receive signals to/from the source eNodeB. During a period of time outside the time window (or connection gap), the UE can apply a UE beam for the target eNodeB to transmit or receive signals to/from the target eNodeB. For example, during the period of time outside the time window (or connection gap), the UE can apply the UE beam for the target eNodeB to perform a RACH procedure with the target eNodeB.

[0036] FIG. 3 illustrates exemplary signaling to maintain a source eNodeB connection between a user equipment (UE) 310 and a source eNodeB 320 during a handover of the UE 310 to a target eNodeB 330. The UE 310, the source eNodeB 320 and the target eNodeB 330 can operate in a wireless communication system that supports massive multiple-input multiple-output (MIMO). In addition, the UE 310, the source eNodeB 320 and the target eNodeB 330 can operate in a synchronized network or an unsynchronized network.

[0037] In one example, the UE 310 can establish a source eNodeB connection with the source eNodeB 320. A source UE beam used by the UE 310 to communicate with the source eNodeB 320 can be derived from a first antenna array of the UE 310. The UE 310 can establish a target eNodeB connection with the target eNodeB 330 during the handover of the UE 310 from the source eNodeB 320 to the target eNodeB 330. A target UE beam used by the UE 310 to communicate with the target eNodeB 330 can be derived from the first antenna array of the UE 310 or a second antenna array of the UE 310. In addition, the UE 310 can maintain the source eNodeB connection with the source eNodeB 320 during the handover of the UE 310 from the source eNodeB 320 to the target eNodeB 330. The UE can transmit/receive, via a transceiver, signals to the source eNodeB and/or the target eNodeB using the source eNodeB connection and/or the target eNodeB connection, respectively. For example, since the source eNodeB connection is maintained after the handover to the target eNodeB 330 has been completed, the UE can transmit/receive signals to/from the source eNodeB 320 and/or the target eNodeB 330.

[0038] In one example, the UE 310 can transmit a beam reference signal receiving power (BRS-RP) report to the source eNodeB 320 and/or the target eNodeB 330. The BRS-RP report can include an indicator to identify when a BRS-RP is measured at the UE 310 from the first antenna array of the UE 310 used to maintain the source eNodeB connection with the source eNodeB 320 or from the second antenna array of the UE 310.

[0039] In one example, the UE 310 can utilize one or more antenna ports from a first polarization to maintain the source eNodeB connection with the source eNodeB 320, and the UE 310 can utilize one or more antenna ports from a second polarization to perform a random access channel (RACH) procedure with the target eNodeB 330. In another example, the UE 310 can transmit a channel state information (CSI) report to the source eNodeB 320 and/or the target eNodeB 330 using a rank 1 precoder.

[0040] In one example, the UE 310 can transmit uplink data and control signaling to the source eNodeB 320 and the target eNodeB 330 using different polarizations of antenna ports at the UE 310, wherein the UE 310 can be configured to apply different UE beams to the different polarizations of antenna ports. In another example, the UE 310 can transmit a first demodulation reference signal (DMRS) associated with an enhanced physical uplink shared channel (xPUSCH) to the source eNodeB 320 using a first antenna port mapped to antenna elements in a first polarization, and the UE 310 can transmit a second DMRS associated with the xPUSCH to the target eNodeB 330 using a second antenna port mapped to antenna elements in a second polarization. [0041] In one example, the UE 310 can utilize a same UE beam to communicate with the source eNodeB 320 in a first subset of subframes or to communicate with the target eNodeB 330 in a second subset of subframes that do not conflict with the first subset of subframes, and the UE 310 can be configured to utilize the same UE beam to communicate with the source eNodeB 320 and the target eNodeB 330 in a time division duplexing (TDM) manner. In another example, the UE 310 can transmit a capability message to the source eNodeB 320 and/or the target eNodeB 330, and the capability message can indicate when the UE 310 is capable of using different antenna arrays to transmit or receive information at different timings.

[0042] In one example, the UE 310 can receive a source eNodeB connection gap configuration from the source eNodeB 320. The source eNodeB connection gap configuration can enable the UE 310 to communicate with the source eNodeB 320 during a period of time as defined by the source eNodeB connection gap configuration. The UE 310 can be configured to communicate with the target eNodeB 330 outside the period of time defined in the source eNodeB connection gap configuration.

[0043] In one configuration, a source eNodeB connection can be maintained between a UE and a source eNodeB during a handover of the UE to a target eNodeB, and when beamforming is applied at the UE and the source/target eNodeBs. In one example, the UE can report a flag associated with each beam reference signal receiving power (BRS-RP) report, and the flag can be used to indicate whether the BRS-RP is received from another antenna array. In another example, the UE can report a capability as to whether different antenna arrays can transmit or receive at different times. In yet another example, the UE can use one antenna port from one polarization to connect to the source eNodeB, and the UE can use another antenna port from another polarization to connect to the target eNodeB.

[0044] In one example, the UE can report a channel state information (CSI) with a rank 1 precoder. In another example, the UE can apply one beam in two beam reference signal (BRS) antenna ports. In yet another example, the source eNodeB can configure a connection gap using radio resource control (RRC) signaling to the UE, during which the target eNodeB may not transmit or receive data to the UE and the UE can transmit and receive data to the source eNodeB. [0045] Another example provides functionality 400 of a user equipment (UE) configured to operate in a massive multiple-input multiple-output (MIMO) system, as shown in FIG.

4. The UE can comprise one or more processors configured to establish, at the UE, a source eNodeB connection with a source eNodeB in the massive MMO system, wherein a source UE beam used to communicate with the source eNodeB is derived from a first antenna array of the UE, as in block 410. The UE can comprise one or more processors configured to establish, at the UE, a target eNodeB connection with a target eNodeB in the massive MIMO system during a handover of the UE from the source eNodeB to the target eNodeB, wherein a target UE beam used to communicate with the target eNodeB is derived from the first antenna array of the UE or a second antenna array of the UE, as in block 420. The UE can comprise one or more processors configured to maintain, at the UE, the source eNodeB connection with the source eNodeB during the handover of the UE from the source eNodeB to the target eNodeB, as in block 430. In addition, the UE can comprise a memory interface configured to send to a memory an indication of the source UE beam and the target UE beam used by the UE to communicate with the source eNodeB and the target eNodeB, respectively.

[0046] Another example provides functionality 500 of a user equipment (UE) configured to operate in a massive multiple-input multiple-output (MIMO) system, as shown in FIG.

5. The UE can comprise one or more processors configured to establish, at the UE, a first connection with a first base station in the massive MMO system, wherein a first UE beam used to communicate with the first base station is derived from a first antenna array of the UE, as in block 510. The UE can comprise one or more processors configured to establish, at the UE, a second connection with a second base station in the massive MMO system during a handover of the UE from the first base station to the second base station, wherein the first connection with the first base station and the second connection with the second base station are simultaneously maintained by the UE, wherein a second UE beam used to communicate with the second base station is derived from the first antenna array of the UE or a second antenna array of the UE, as in block 520. In addition, the UE can comprise a memory interface configured to send to a memory an indication of the first beam and the second beam used by the UE to communicate with the first base station and the second base station, respectively.

[0047] Another example provides at least one machine readable storage medium having instructions 600 embodied thereon for maintaining a source eNodeB connection with a source eNodeB at a user equipment (UE) during a handover of the UE in a massive multiple-input multiple-output (MIMO) system, as shown in FIG. 6. The instructions can be executed on a machine, where the instructions are included on at least one computer readable medium or one non-transitory machine readable storage medium. The instructions when executed by one or more processors of the UE perform: establishing, at the UE, a source eNodeB connection with a source eNodeB in the massive MMO system, wherein a source UE beam used to communicate with the source eNodeB is derived from a first antenna array of the UE, as in block 610. The instructions when executed by one or more processors of the UE perform: establishing, at the UE, a target eNodeB connection with a target eNodeB in the massive MMO system during a handover of the UE from the source eNodeB to the target eNodeB, wherein a target UE beam used to communicate with the target eNodeB is derived from the first antenna array of the UE or a second antenna array of the UE, as in block 620. The instructions when executed by one or more processors of the UE perform: maintaining, at the UE, the source eNodeB connection with the source eNodeB during the handover of the UE from the source eNodeB to the target eNodeB, as in block 630.

[0048] FIG. 7 illustrates an architecture of a system 700 of a network in accordance with some embodiments. The system 700 is shown to include a user equipment (UE) 701 and a UE 702. The UEs 701 and 702 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.

[0049] In some embodiments, any of the UEs 701 and 702 can comprise an Internet of Things (IoT) UE, which can comprise a network access layer designed for low-power IoT applications utilizing short-lived UE connections. An IoT 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 IoT networks. The M2M or MTC exchange of data may be a machine-initiated exchange of data. An IoT network describes interconnecting IoT UEs, which may include uniquely identifiable embedded computing devices (within the Internet infrastructure), with short-lived connections. The IoT UEs may execute background applications (e.g., keep-alive messages, status updates, etc.) to facilitate the connections of the IoT network.

[0050] The UEs 701 and 702 may be configured to connect, e.g., communicatively couple, with a radio access network (RAN) 710— the RAN 710 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 701 and 702 utilize connections 703 and 704, respectively, each of which comprises a physical communications interface or layer (discussed in further detail below); in this example, the connections 703 and 704 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.

[0051] In this embodiment, the UEs 701 and 702 may further directly exchange communication data via a ProSe interface 705. The ProSe interface 705 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).

[0052] The UE 702 is shown to be configured to access an access point (AP) 706 via connection 707. The connection 707 can comprise a local wireless connection, such as a connection consistent with any IEEE 802.15 protocol, wherein the AP 706 would comprise a wireless fidelity (WiFi®) router. In this example, the AP 706 is shown to be connected to the Internet without connecting to the core network of the wireless system (described in further detail below).

[0053] The RAN 710 can include one or more access nodes that enable the connections 703 and 704. 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 710 may include one or more RAN nodes for providing macrocells, e.g., macro RAN node 711, 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 712.

[0054] Any of the RAN nodes 711 and 712 can terminate the air interface protocol and can be the first point of contact for the UEs 701 and 702. In some embodiments, any of the RAN nodes 711 and 712 can fulfill various logical functions for the RAN 710 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.

[0055] In accordance with some embodiments, the UEs 701 and 702 can be configured to communicate using Orthogonal Frequency-Division Multiplexing (OFDM)

communication signals with each other or with any of the RAN nodes 711 and 712 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.

[0056] In some embodiments, a downlink resource grid can be used for downlink transmissions from any of the RAN nodes 711 and 712 to the UEs 701 and 702, 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.

[0057] The physical downlink shared channel (PDSCH) may carry user data and higher- layer signaling to the UEs 701 and 702. 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 701 and 702 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 702 within a cell) may be performed at any of the RAN nodes 711 and 712 based on channel quality information fed back from any of the UEs 701 and 702. The downlink resource assignment information may be sent on the PDCCH used for (e.g., assigned to) each of the UEs 701 and 702.

[0058] 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=l, 2, 4, or 8).

[0059] 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 the control channel elements (ECCEs). Similar to above, each ECCE may correspond to nine sets of four physical resource elements known as an enhanced resource element groups (EREGs). An ECCE may have other numbers of EREGs in some situations.

[0060] The RAN 710 is shown to be communicatively coupled to a core network (CN) 720— via an SI interface 713. In embodiments, the CN 720 may be an evolved packet core (EPC) network, a NextGen Packet Core (NPC) network, or some other type of CN. In this embodiment the SI interface 713 is split into two parts: the SI -U interface 714, which carries traffic data between the RAN nodes 711 and 712 and the serving gateway (S-GW) 722, and the S I -mobility management entity (MME) interface 715, which is a signaling interface between the RAN nodes 711 and 712 and MMEs 721.

[0061] In this embodiment, the CN 720 comprises the MMEs 721, the S-GW 722, the Packet Data Network (PDN) Gateway (P-GW) 723, and a home subscriber server (HSS) 724. The MMEs 721 may be similar in function to the control plane of legacy Serving General Packet Radio Service (GPRS) Support Nodes (SGSN). The MMEs 721 may manage mobility aspects in access such as gateway selection and tracking area list management. The HSS 724 may comprise a database for network users, including subscription-related information to support the network entities' handling of

communication sessions. The CN 720 may comprise one or several HSSs 724, depending on the number of mobile subscribers, on the capacity of the equipment, on the organization of the network, etc. For example, the HSS 724 can provide support for routing/roaming, authentication, authorization, naming/addressing resolution, location dependencies, etc.

[0062] The S-GW 722 may terminate the SI interface 713 towards the RAN 710, and routes data packets between the RAN 710 and the CN 720. In addition, the S-GW 722 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.

[0063] The P-GW 723 may terminate an SGi interface toward a PDN. The P-GW 723 may route data packets between the EPC network 723 and external networks such as a network including the application server 730 (alternatively referred to as application function (AF)) via an Internet Protocol (IP) interface 725. Generally, the application server 730 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 723 is shown to be communicatively coupled to an application server 730 via an IP communications interface 725. The application server 730 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 701 and 702 via the CN 720.

[0064] The P-GW 723 may further be a node for policy enforcement and charging data collection. Policy and Charging Enforcement Function (PCRF) 726 is the policy and charging control element of the CN 720. 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 726 may be communicatively coupled to the application server 730 via the P-GW 723. The application server 730 may signal the PCRF 726 to indicate a new service flow and select the appropriate Quality of Service (QoS) and charging parameters. The PCRF 726 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 730.

[0065] FIG. 8 illustrates example components of a device 800 in accordance with some embodiments. In some embodiments, the device 800 may include application circuitry 802, baseband circuitry 804, Radio Frequency (RF) circuitry 806, front-end module (FEM) circuitry 808, one or more antennas 810, and power management circuitry (PMC) 812 coupled together at least as shown. The components of the illustrated device 800 may be included in a UE or a RAN node. In some embodiments, the device 800 may include less elements (e.g., a RAN node may not utilize application circuitry 802, and instead include a processor/controller to process IP data received from an EPC). In some embodiments, the device 800 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).

[0066] The application circuitry 802 may include one or more application processors. For example, the application circuitry 802 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 800. In some embodiments, processors of application circuitry 802 may process IP data packets received from an EPC.

[0067] The baseband circuitry 804 may include circuitry such as, but not limited to, one or more single-core or multi-core processors. The baseband circuitry 804 may include one or more baseband processors or control logic to process baseband signals received from a receive signal path of the RF circuitry 806 and to generate baseband signals for a transmit signal path of the RF circuitry 806. Baseband processing circuity 804 may interface with the application circuitry 802 for generation and processing of the baseband signals and for controlling operations of the RF circuitry 806. For example, in some embodiments, the baseband circuitry 804 may include a third generation (3G) baseband processor 804a, a fourth generation (4G) baseband processor 804b, a fifth generation (5G) baseband processor 804c, or other baseband processor(s) 804d for other existing generations, generations in development or to be developed in the future (e.g., second generation (2G), sixth generation (6G), etc.). The baseband circuitry 804 (e.g., one or more of baseband processors 804a-d) may handle various radio control functions that enable communication with one or more radio networks via the RF circuitry 806. In other embodiments, some or all of the functionality of baseband processors 804a-d may be included in modules stored in the memory 804g and executed via a Central Processing Unit (CPU) 804e. 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 804 may include Fast-Fourier Transform (FFT), precoding, or constellation mapping/demapping functionality. In some embodiments, encoding/decoding circuitry of the baseband circuitry 804 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.

[0068] In some embodiments, the baseband circuitry 804 may include one or more audio digital signal processor(s) (DSP) 804f. The audio DSP(s) 804f 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 804 and the application circuitry 802 may be implemented together such as, for example, on a system on a chip (SOC).

[0069] In some embodiments, the baseband circuitry 804 may provide for

communication compatible with one or more radio technologies. For example, in some embodiments, the baseband circuitry 804 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), a wireless personal area network (WPAN). Embodiments in which the baseband circuitry 804 is configured to support radio communications of more than one wireless protocol may be referred to as multi-mode baseband circuitry.

[0070] RF circuitry 806 may enable communication with wireless networks

using modulated electromagnetic radiation through a non-solid medium. In various embodiments, the RF circuitry 806 may include switches, filters, amplifiers, etc. to facilitate the communication with the wireless network. RF circuitry 806 may include a receive signal path which may include circuitry to down-convert RF signals received from the FEM circuitry 808 and provide baseband signals to the baseband circuitry 804. RF circuitry 806 may also include a transmit signal path which may include circuitry to up-convert baseband signals provided by the baseband circuitry 804 and provide RF output signals to the FEM circuitry 808 for transmission.

[0071] In some embodiments, the receive signal path of the RF circuitry 806 may include mixer circuitry 806a, amplifier circuitry 806b and filter circuitry 806c. In some embodiments, the transmit signal path of the RF circuitry 806 may include filter circuitry 806c and mixer circuitry 806a. RF circuitry 806 may also include synthesizer circuitry 806d for synthesizing a frequency for use by the mixer circuitry 806a of the receive signal path and the transmit signal path. In some embodiments, the mixer circuitry 806a of the receive signal path may be configured to down-convert RF signals received from the FEM circuitry 808 based on the synthesized frequency provided by synthesizer circuitry 806d. The amplifier circuitry 806b may be configured to amplify the down-converted signals and the filter circuitry 806c 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 804 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, mixer circuitry 806a of the receive signal path may comprise passive mixers, although the scope of the embodiments is not limited in this respect.

[0072] In some embodiments, the mixer circuitry 806a of the transmit signal path may be configured to up-convert input baseband signals based on the synthesized frequency provided by the synthesizer circuitry 806d to generate RF output signals for the FEM circuitry 808. The baseband signals may be provided by the baseband circuitry 804 and may be filtered by filter circuitry 806c.

[0073] In some embodiments, the mixer circuitry 806a of the receive signal path and the mixer circuitry 806a 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 806a of the receive signal path and the mixer circuitry 806a 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 806a of the receive signal path and the mixer circuitry 806a may be arranged for direct downconversion and direct upconversion, respectively. In some embodiments, the mixer circuitry 806a of the receive signal path and the mixer circuitry 806a of the transmit signal path may be configured for super-heterodyne operation.

[0074] 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 806 may include analog-to-digital converter (ADC) and digital-to-analog converter (DAC) circuitry and the baseband circuitry 804 may include a digital baseband interface to communicate with the RF circuitry 806.

[0075] In some dual-mode embodiments, a separate radio IC circuitry may be provided for processing signals for each spectrum, although the scope of the embodiments is not limited in this respect.

[0076] In some embodiments, the synthesizer circuitry 806d may be a fractional-N synthesizer or a fractional N/N+l 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 806d may be a delta-sigma synthesizer, a frequency multiplier, or a synthesizer comprising a phase-locked loop with a frequency divider.

[0077] The synthesizer circuitry 806d may be configured to synthesize an output frequency for use by the mixer circuitry 806a of the RF circuitry 806 based on a frequency input and a divider control input. In some embodiments, the synthesizer circuitry 806d may be a fractional N/N+l synthesizer.

[0078] 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 804 or the applications processor 802 depending on the desired output frequency. In some embodiments, a divider control input (e.g., N) may be determined from a look-up table based on a channel indicated by the applications processor 802.

[0079] Synthesizer circuitry 806d of the RF circuitry 806 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+l (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.

[0080] In some embodiments, synthesizer circuitry 806d 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 LO frequency (fLO). In some embodiments, the RF circuitry 806 may include an IQ/polar converter.

[0081] FEM circuitry 808 may include a receive signal path which may include circuitry configured to operate on RF signals received from one or more antennas 810, amplify the received signals and provide the amplified versions of the received signals to the RF circuitry 806 for further processing. FEM circuitry 808 may also include a transmit signal path which may include circuitry configured to amplify signals for transmission provided by the RF circuitry 806 for transmission by one or more of the one or more antennas 810. In various embodiments, the amplification through the transmit or receive signal paths may be done solely in the RF circuitry 806, solely in the FEM 808, or in both the RF circuitry 806 and the FEM 808.

[0082] In some embodiments, the FEM circuitry 808 may include a TX/RX switch to switch between transmit mode and receive mode operation. The FEM circuitry may include a receive signal path and a transmit signal path. The receive signal path of the FEM circuitry may include an LNA to amplify received RF signals and provide the amplified received RF signals as an output (e.g., to the RF circuitry 806). The transmit signal path of the FEM circuitry 808 may include a power amplifier (PA) to amplify input RF signals (e.g., provided by RF circuitry 806), and one or more filters to generate RF signals for subsequent transmission (e.g., by one or more of the one or more antennas 810).

[0083] In some embodiments, the PMC 812 may manage power provided to the baseband circuitry 804. In particular, the PMC 812 may control power-source selection, voltage scaling, battery charging, or DC-to-DC conversion. The PMC 812 may often be included when the device 800 is capable of being powered by a battery, for example, when the device is included in a UE. The PMC 812 may increase the power conversion efficiency while providing desirable implementation size and heat dissipation characteristics.

[0084] While FIG. 8 shows the PMC 812 coupled only with the baseband circuitry 804. However, in other embodiments, the PMC 8 12 may be additionally or alternatively coupled with, and perform similar power management operations for, other components such as, but not limited to, application circuitry 802, RF circuitry 806, or FEM 808.

[0085] In some embodiments, the PMC 812 may control, or otherwise be part of, various power saving mechanisms of the device 800. For example, if the device 800 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 800 may power down for brief intervals of time and thus save power.

[0086] If there is no data traffic activity for an extended period of time, then the device 800 may transition off to an RRC Idle state, where it disconnects from the network and does not perform operations such as channel quality feedback, handover, etc. The device 800 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 800 may not receive data in this state, in order to receive data, it must transition back to

RRC Connected state.

[0087] 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. [0088] Processors of the application circuitry 802 and processors of the baseband circuitry 804 may be used to execute elements of one or more instances of a protocol stack. For example, processors of the baseband circuitry 804, alone or in combination, may be used execute Layer 3, Layer 2, or Layer 1 functionality, while processors of the application circuitry 804 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.

[0089] FIG. 9 illustrates example interfaces of baseband circuitry in accordance with some embodiments. As discussed above, the baseband circuitry 804 of FIG. 8 may comprise processors 804a-804e and a memory 804g utilized by said processors. Each of the processors 804a-804e may include a memory interface, 904a-904e, respectively, to send/receive data to/from the memory 804g.

[0090] The baseband circuitry 804 may further include one or more interfaces to communicatively couple to other circuitries/devices, such as a memory interface 912 (e.g., an interface to send/receive data to/from memory external to the baseband circuitry 804), an application circuitry interface 914 (e.g., an interface to send/receive data to/from the application circuitry 802 of FIG. 8), an RF circuitry interface 916 (e.g., an interface to send/receive data to/from RF circuitry 806 of FIG. 8), a wireless hardware connectivity interface 918 (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 920 (e.g., an interface to send/receive power or control signals to/from the PMC 812.

[0091] FIG. 10 provides an example illustration of the wireless device, such as a user equipment (UE), a mobile station (MS), a mobile wireless device, a mobile

communication device, a tablet, a handset, or other type of wireless device. The wireless device can include one or more antennas configured to communicate with a node, macro node, low power node (LPN), or, transmission station, such as a base station (BS), an evolved Node B (eNB), a baseband processing unit (BBU), a remote radio head (RRH), a remote radio equipment (R E), a relay station (RS), a radio equipment (RE), or other type of wireless wide area network (WWAN) access point. The wireless device can be configured to communicate using at least one wireless communication standard such as, but not limited to, 3 GPP LTE, WiMAX, High Speed Packet Access (HSPA), Bluetooth, and WiFi. The wireless device can communicate using separate antennas for each wireless communication standard or shared antennas for multiple wireless communication standards. The wireless device can communicate in a wireless local area network

(WLAN), a wireless personal area network (WPAN), and/or a WWAN. The wireless device can also comprise a wireless modem. The wireless modem can comprise, for example, a wireless radio transceiver and baseband circuitry (e.g., a baseband processor). The wireless modem can, in one example, modulate signals that the wireless device transmits via the one or more antennas and demodulate signals that the wireless device receives via the one or more antennas.

[0092] FIG. 10 also provides an illustration of a microphone and one or more speakers that can be used for audio input and output from the wireless device. The display screen can be a liquid crystal display (LCD) screen, or other type of display screen such as an organic light emitting diode (OLED) display. The display screen can be configured as a touch screen. The touch screen can use capacitive, resistive, or another type of touch screen technology. An application processor and a graphics processor can be coupled to internal memory to provide processing and display capabilities. A non-volatile memory port can also be used to provide data input/output options to a user. The non-volatile memory port can also be used to expand the memory capabilities of the wireless device. A keyboard can be integrated with the wireless device or wirelessly connected to the wireless device to provide additional user input. A virtual keyboard can also be provided using the touch screen.

Examples

[0093] The following examples pertain to specific technology embodiments and point out specific features, elements, or actions that can be used or otherwise combined in achieving such embodiments. [0094] Example 1 includes an apparatus of a user equipment (UE) configured to operate in a massive multiple-input multiple-output (MIMO) system, the apparatus comprising: one or more processors configured to: establish, at the UE, a source eNodeB connection with a source eNodeB in the massive MMO system, wherein a source UE beam used to communicate with the source eNodeB is derived from a first antenna array of the UE; establish, at the UE, a target eNodeB connection with a target eNodeB in the massive MIMO system during a handover of the UE from the source eNodeB to the target eNodeB, wherein a target UE beam used to communicate with the target eNodeB is derived from the first antenna array of the UE or a second antenna array of the UE; and maintain, at the UE, the source eNodeB connection with the source eNodeB during the handover of the UE from the source eNodeB to the target eNodeB; and a memory interface configured to send to a memory an indication of the source UE beam and the target UE beam used by the UE to communicate with the source eNodeB and the target eNodeB, respectively.

[0095] Example 2 includes the apparatus of Example 1, further comprising a transceiver configured to: transmit, from the UE, signals to one or more of the source eNodeB or the target eNodeB; and receive, at the UE, signals from one or more of the source eNodeB or the target eNodeB.

[0096] Example 3 includes the apparatus of any of Examples 1 to 2, wherein the one or more processors are further configured to encode a beam reference signal receiving power (BRS-RP) report for transmission to one of the source eNodeB or the target eNodeB, wherein the BRS-RP report includes an indicator to identify when a BRS-RP is measured at the UE from the first antenna array of the UE used to maintain the source eNodeB connection with the source eNodeB or from the second antenna array of the UE.

[0097] Example 4 includes the apparatus of any of Examples 1 to 3, wherein the one or more processors are further configured to: utilize one or more antenna ports from a first polarization to maintain the source eNodeB connection with the source eNodeB; and utilize one or more antenna ports from a second polarization to perform a random access channel (RACH) procedure with the target eNodeB.

[0098] Example 5 includes the apparatus of any of Examples 1 to 4, wherein the one or more processors are further configured to encode a channel state information (CSI) report for transmission to one or more of the source eNodeB or the target eNodeB using a rank 1 precoder.

[0099] Example 6 includes the apparatus of any of Examples 1 to 5, wherein the one or more processors are further configured to encode uplink data and control signaling for transmission to the source eNodeB and the target eNodeB using different polarizations of antenna ports at the UE, wherein the UE is configured to apply different UE beams to the different polarizations of antenna ports.

[00100] Example 7 includes the apparatus of any of Examples 1 to 6, wherein the one or more processors are further configured to: encode a first demodulation reference signal (DMRS) associated with an enhanced physical uplink shared channel (xPUSCH) for transmission to the source eNodeB using a first antenna port mapped to antenna elements in a first polarization; and encode a second DMRS associated with the xPUSCH for transmission to the target eNodeB using a second antenna port mapped to antenna elements in a second polarization.

[00101] Example 8 includes the apparatus of any of Examples 1 to 7, wherein the one or more processors are further configured to utilize a same UE beam to communicate with the source eNodeB in a first subset of subframes or to communicate with the target eNodeB in a second subset of subframes that do not conflict with the first subset of subframes, wherein the UE is configured to utilize the same UE beam to communicate with the source eNodeB and the target eNodeB in a time division duplexing (TDM) manner.

[00102] Example 9 includes the apparatus of any of Examples 1 to 8, wherein the one or more processors are further configured encode a capability message for transmission to one of the source eNodeB or the target eNodeB, wherein the capability message indicates when the UE is capable of using different antenna arrays to transmit or receive information at different timings.

[00103] Example 10 includes the apparatus of any of Examples 1 to 9, wherein the one or more processors are further configured decode a source eNodeB connection gap configuration received from the target eNodeB or the source eNodeB, wherein the source eNodeB connection gap configuration enables the UE to communicate with the source eNodeB during a period of time as defined in the source eNodeB connection gap configuration, wherein the UE is configured to communicate with the target eNodeB outside the period of time defined in the source eNodeB connection gap configuration.

[00104] Example 11 includes the apparatus of any of Examples 1 to 10, wherein the UE, the source eNodeB and the target eNodeB operate in a synchronized network.

[00105] Example 12 includes the apparatus of any of Examples 1 to 11, wherein the UE, the source eNodeB and the target eNodeB operate in an unsynchronized network.

[00106] Example 13 includes an apparatus of a user equipment (UE) configured to operate in a massive multiple-input multiple-output (MIMO) system, the apparatus comprising: one or more processors configured to: establish, at the UE, a first connection with a first base station in the massive MMO system, wherein a first UE beam used to communicate with the first base station is derived from a first antenna array of the UE; and establish, at the UE, a second connection with a second base station in the massive MMO system during a handover of the UE from the first base station to the second base station, wherein the first connection with the first base station and the second connection with the second base station are simultaneously maintained by the UE, wherein a second UE beam used to communicate with the second base station is derived from the first antenna array of the UE or a second antenna array of the UE; and a memory interface configured to send to a memory an indication of the first beam and the second beam used by the UE to communicate with the first base station and the second base station, respectively.

[00107] Example 14 includes the apparatus of Example 13, wherein the one or more processors are further configured to encode a beam reference signal receiving power (BRS-RP) report for transmission to one of the first base station or the second base station, wherein the BRS-RP report indicates that a BRS-RP is measured at the UE from the first antenna array of the UE used to maintain the first connection with the first base station or from the second antenna array of the UE.

[00108] Example 15 includes the apparatus of any of Examples 13 to 14, wherein the one or more processors are further configured to utilize a same UE beam to communicate with the first base station in a first subset of subframes or to communicate with the second base station in a second subset of subframes that do not conflict with the first subset of subframes, wherein the UE is configured to utilize the same UE beam to communicate with the first base station and the second base station in a time division duplexing (TDM) manner.

[00109] Example 16 includes the apparatus of any of Examples 13 to 15, wherein the first subset of subframes include odd subframes and the second subset of subframes include even subframes, or the first subset of subframes include even subframes and the second subset of subframes include odd subframes.

[00110] Example 17 includes the apparatus of any of Examples 13 to 16, wherein the one or more processors are further configured encode a capability message for transmission to one of the first base station or the second base station, wherein the capability message indicates that the UE is capable of using different antenna arrays to transmit or receive information at different timings.

[00111] Example 18 includes the apparatus of any of Examples 13 to 17, wherein the UE, the first base station and the second base station operate in a synchronized network or an unsynchronized network.

[00112] Example 19 includes at least one machine readable storage medium having instructions embodied thereon for maintaining a source eNodeB connection with a source eNodeB at a user equipment (UE) during a handover of the UE in a massive multiple- input multiple-output (MIMO) system, the instructions when executed by one or more processors of the UE perform the following: establishing, at the UE, a source eNodeB connection with a source eNodeB in the massive MMO system, wherein a source UE beam used to communicate with the source eNodeB is derived from a first antenna array of the UE; establishing, at the UE, a target eNodeB connection with a target eNodeB in the massive MMO system during a handover of the UE from the source eNodeB to the target eNodeB, wherein a target UE beam used to communicate with the target eNodeB is derived from the first antenna array of the UE or a second antenna array of the UE; and maintaining, at the UE, the source eNodeB connection with the source eNodeB during the handover of the UE from the source eNodeB to the target eNodeB.

[00113] Example 20 includes the at least one machine readable storage medium of Example 19, further comprising instructions when executed perform the following: utilizing one or more antenna ports from a first polarization to maintain the source eNodeB connection with the source eNodeB; and utilizing one or more antenna ports from a second polarization to perform a random access channel (RACH) procedure with the target eNodeB.

[00114] Example 21 includes the at least one machine readable storage medium of any of Examples 19 to 20, further comprising instructions when executed perform the following: encoding a channel state information (CSI) report for transmission to one or more of the source eNodeB or the target eNodeB using a rank 1 precoder.

[00115] Example 22 includes the at least one machine readable storage medium of any of Examples 19 to 21, further comprising instructions when executed perform the following: encoding uplink data and control signaling for transmission to the source eNodeB and the target eNodeB using different polarizations of antenna ports at the UE, wherein the UE is configured to apply different UE beams to the different polarizations of antenna ports.

[00116] Example 23 includes the at least one machine readable storage medium of any of Examples 19 to 22, further comprising instructions when executed perform the following: encoding a first demodulation reference signal (DMRS) associated with an enhanced physical uplink shared channel (xPUSCH) for transmission to the source eNodeB using a first antenna port mapped to antenna elements in a first polarization; and encoding a second DMRS associated with the xPUSCH for transmission to the target eNodeB using a second antenna port mapped to antenna elements in a second polarization.

[00117] Example 24 includes the at least one machine readable storage medium of any of Examples 19 to 20, further comprising instructions when executed perform the following: decoding a source eNodeB connection gap configuration received from the target eNodeB or the source eNodeB, wherein the source eNodeB connection gap configuration enables the UE to communicate with the source eNodeB during a period of time as defined in the source eNodeB connection gap configuration, wherein the UE is configured to communicate with the target eNodeB outside the period of time defined in the source eNodeB connection gap configuration.

[00118] Example 25 includes a user equipment (UE) operable to maintain a source eNodeB connection with a source eNodeB during a handover of the UE in a massive multiple-input multiple-output (MIMO) system, the UE comprising: means for establishing, at the UE, a source eNodeB connection with a source eNodeB in the massive MMO system, wherein a source UE beam used to communicate with the source eNodeB is derived from a first antenna array of the UE; means for establishing, at the UE, a target eNodeB connection with a target eNodeB in the massive MMO system during a handover of the UE from the source eNodeB to the target eNodeB, wherein a target UE beam used to communicate with the target eNodeB is derived from the first antenna array of the UE or a second antenna array of the UE; and means for maintaining, at the UE, the source eNodeB connection with the source eNodeB during the handover of the UE from the source eNodeB to the target eNodeB.

[00119] Example 26 includes the UE of Example 25, further comprising: means for utilizing one or more antenna ports from a first polarization to maintain the source eNodeB connection with the source eNodeB; and utilizing one or more antenna ports from a second polarization to perform a random access channel (RACH) procedure with the target eNodeB.

[00120] Example 27 includes the UE of any of Examples 25 to 26, further comprising: means for encoding a channel state information (CSI) report for transmission to one or more of the source eNodeB or the target eNodeB using a rank 1 precoder.

[00121] Example 28 includes the UE of any of Examples 25 to 27, further comprising: means for encoding uplink data and control signaling for transmission to the source eNodeB and the target eNodeB using different polarizations of antenna ports at the UE, wherein the UE is configured to apply different UE beams to the different polarizations of antenna ports.

[00122] Example 29 includes the UE of any of Examples 25 to 28, further comprising: means for encoding a first demodulation reference signal (DMRS) associated with an enhanced physical uplink shared channel (xPUSCH) for transmission to the source eNodeB using a first antenna port mapped to antenna elements in a first polarization; and means for encoding a second DMRS associated with the xPUSCH for transmission to the target eNodeB using a second antenna port mapped to antenna elements in a second polarization.

[00123] Example 30 includes the UE of any of Examples 25 to 29, further comprising: means for decoding a source eNodeB connection gap configuration received from the target eNodeB or the source eNodeB, wherein the source eNodeB connection gap configuration enables the UE to communicate with the source eNodeB during a period of time as defined in the source eNodeB connection gap configuration, wherein the UE is configured to communicate with the target eNodeB outside the period of time defined in the source eNodeB connection gap configuration.

[00124] Various techniques, or certain aspects or portions thereof, may take the form of program code (i.e., instructions) embodied in tangible media, such as floppy diskettes, compact disc-read-only memory (CD-ROMs), hard drives, non-transitory computer readable storage medium, or any other machine-readable storage medium wherein, when the program code is loaded into and executed by a machine, such as a computer, the machine becomes an apparatus for practicing the various techniques. In the case of program code execution on programmable computers, the computing device may include a processor, a storage medium readable by the processor (including volatile and nonvolatile memory and/or storage elements), at least one input device, and at least one output device. The volatile and non-volatile memory and/or storage elements may be a random-access memory (RAM), erasable programmable read only memory (EPROM), flash drive, optical drive, magnetic hard drive, solid state drive, or other medium for storing electronic data. The node and wireless device may also include a transceiver module (i.e., transceiver), a counter module (i.e., counter), a processing module (i.e., processor), and/or a clock module (i.e., clock) or timer module (i.e., timer). In one example, selected components of the transceiver module can be located in a cloud radio access network (C-RAN). One or more programs that may implement or utilize the various techniques described herein may use an application programming interface (API), reusable controls, and the like. Such programs may be implemented in a high level procedural or object oriented programming language to communicate with a computer system. However, the program(s) may be implemented in assembly or machine language, if desired. In any case, the language may be a compiled or interpreted language, and combined with hardware implementations.

[00125] As used herein, the term "circuitry" may refer to, be part of, or include an Application Specific Integrated Circuit (ASIC), an electronic circuit, a processor (shared, dedicated, or group), and/or memory (shared, dedicated, or group) that execute one or more software or firmware programs, a combinational logic circuit, and/or other suitable hardware components that provide the described functionality. In some embodiments, the circuitry may be implemented in, or functions associated with the circuitry may be implemented by, one or more software or firmware modules. In some embodiments, circuitry may include logic, at least partially operable in hardware.

[00126] It should be understood that many of the functional units described in this specification have been labeled as modules, in order to more particularly emphasize their implementation independence. For example, a module may be implemented as a hardware circuit comprising custom very-large-scale integration (VLSI) circuits or gate arrays, off-the-shelf semiconductors such as logic chips, transistors, or other discrete components. A module may also be implemented in programmable hardware devices such as field programmable gate arrays, programmable array logic, programmable logic devices or the like.

[00127] Modules may also be implemented in software for execution by various types of processors. An identified module of executable code may, for instance, comprise one or more physical or logical blocks of computer instructions, which may, for instance, be organized as an object, procedure, or function. Nevertheless, the executables of an identified module may not be physically located together, but may comprise disparate instructions stored in different locations which, when joined logically together, comprise the module and achieve the stated purpose for the module.

[00128] Indeed, a module of executable code may be a single instruction, or many instructions, and may even be distributed over several different code segments, among different programs, and across several memory devices. Similarly, operational data may be identified and illustrated herein within modules, and may be embodied in any suitable form and organized within any suitable type of data structure. The operational data may be collected as a single data set, or may be distributed over different locations including over different storage devices, and may exist, at least partially, merely as electronic signals on a system or network. The modules may be passive or active, including agents operable to perform desired functions.

[00129] Reference throughout this specification to "an example" or "exemplary" means that a particular feature, structure, or characteristic described in connection with the example is included in at least one embodiment of the present technology. Thus, appearances of the phrases "in an example" or the word "exemplary" in various places throughout this specification are not necessarily all referring to the same embodiment.

[00130] As used herein, a plurality of items, structural elements, compositional elements, and/or materials may be presented in a common list for convenience. However, these lists should be construed as though each member of the list is individually identified as a separate and unique member. Thus, no individual member of such list should be construed as a de facto equivalent of any other member of the same list solely based on their presentation in a common group without indications to the contrary. In addition, various embodiments and example of the present technology may be referred to herein along with alternatives for the various components thereof. It is understood that such embodiments, examples, and alternatives are not to be construed as defacto equivalents of one another, but are to be considered as separate and autonomous representations of the present technology.

[00131] Furthermore, the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided, such as examples of layouts, distances, network examples, etc., to provide a thorough understanding of embodiments of the technology. One skilled in the relevant art will recognize, however, that the technology can be practiced without one or more of the specific details, or with other methods, components, layouts, etc. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of the technology.

[00132] While the forgoing examples are illustrative of the principles of the present technology in one or more particular applications, it will be apparent to those of ordinary skill in the art that numerous modifications in form, usage and details of implementation can be made without the exercise of inventive faculty, and without departing from the principles and concepts of the technology. Accordingly, it is not intended that the technology be limited, except as by the claims set forth below.