WO2018063443A1

WO2018063443A1 - Timer handling for rachless handover

Info

Publication number: WO2018063443A1
Application number: PCT/US2017/030051
Authority: WO
Inventors: Candy YIU; Yujian Zhang; Youn Hyoung Heo
Original assignee: Intel IP Corp
Current assignee: Intel IP Corp
Priority date: 2016-09-30
Filing date: 2017-04-28
Publication date: 2018-04-05
Anticipated expiration: 2019-03-30

Abstract

Embodiments of the present disclosure may identify a user equipment (UE) for handling timers in RACH-less handovers. The UE may comprise transceiver circuitry to send, as part of a random access channel (RACH)-less handover, a transmission to a target cell in a cellular communications network, and receive a responsive message from a base station of the target cell. The UE may also comprise timer control circuitry coupled to the transceiver circuitry to stop a UE reception of connection reconfiguration message timer if the responsive message is received. Other embodiments may be described and/or claimed.

Description

TIMER HANDLING FOR RACHLESS HANDOVER

Related Application

This application claims benefit of U.S. Provisional Patent Application No.

62/402,050, filed September 30, 2016, which is hereby incorporated by reference herein in its entirety.

Field

Various embodiments generally may relate to the field of wireless communications.

Background

An example of a cellular communication system is an architecture as standardized by the 3rd Generation Partnership Project (3GPP). A recent development in this field is often referred to as the long-term evolution (LTE) of the Universal Mobile

Telecommunications System (UMTS) radio-access technology. E-UTRA (evolved UMTS Terrestrial Radio Access) is the air interface of 3GPP's Long Term Evolution (LTE) upgrade path for mobile networks. In LTE, base stations, which are referred to as evolved Node Bs (eNBs), provide wireless access within a coverage area or cell. In LTE, mobile devices, or mobile stations, are referred to as user equipment (UE). A mobile station or UE may perform a handover from a source base station (BS) to a target BS. A handover may use a random access procedure to allow the mobile station to obtain a time advance value with respect to the target BS. Also, a handover often causes an interruption in data services for a mobile station.

A random-access channel (RACH) is a communication mechanism used by mobile phones and other wireless devices on a TDMA-based network. A RACH is used to get the attention of a base station in order to initially synchronize a device's transmission with the base station. It is a shared channel that is used by wireless access terminals to access the access network (e.g., Time Division Multiple Access (TDMA), Frequency Division

Multiple Access (FDMA), and Code Divison Multiple Access (CDMA) based networks) especially for initial access and bursty data transmission. More precisely, RACH is a transport-layer channel, and the corresponding physical -layer channel is PRACH.

Conventional LTE handovers of a user device from one base station to another involve RACH procedures. Such a handover is known as a RACH handover (HO). In a RACH handover, the user equipment (UE) sends a measurement report to a source eNB once an event is triggered and a time-to-trigger (TTT) timer is expired. Then the source eNB will send a handover request. Once the source eNB receives the handover acknowledgement from a target eNB, it sends an RRCConnectionReconfiguration message to the UE including the mobility control information (containing RACH preamble information generated by the target eNB). The UE then performs a RACH procedure towards the target eNB. When the UE receives a random access response (RAR) from the target eNB, it sends an RRCConnectionReconfigurationComplete message, indicating that the handover is completed.

While useful, RACH handovers require longer interruption delays. Because of this, RACH-less handovers are desirable, but require modification to certain RACH signaling procedures.

Brief Description of the Drawings

Embodiments will be readily understood by the following detailed description in conjunction with the accompanying drawings. To facilitate this description, like reference numerals designate like structural elements. Embodiments are illustrated by way of example and not by way of limitation in the figures of the accompanying drawings.

Figure 1 illustrates an example network that includes a user equipment (UE) and an evolved NodeB (eNB), in accordance with various embodiments.

Figure 2 illustrates an example network that includes a plurality of eNBs, in accordance with various embodiments.

Figure 3 illustrates an overview of the operational flow of a process for termination of a T304 timer in a RACH-less handover, in accordance with various embodiments.

Figure 4 illustrates an overview of the operational flow of a process for termination of a T307 timer in a RACH-less handover, in accordance with various embodiments.

Figure 5 illustrates an electronic device, in accordance with various embodiments.

Figure 6 illustrates a computer system, in accordance with various embodiments.

Detailed Description

The following detailed description refers to the accompanying drawings. The same reference numbers may be used in different drawings to identify the same or similar elements. In the following description, for purposes of explanation and not limitation, specific details are set forth such as particular structures, architectures, interfaces, techniques, etc. in order to provide a thorough understanding of the various aspects of various embodiments. However, it will be apparent to those skilled in the art having the benefit of the present disclosure that the various aspects of the various embodiments may be practiced in other examples that depart from these specific details. In certain instances, descriptions of well-known devices, circuits, and methods are omitted so as not to obscure the description of the various embodiments with unnecessary detail.

Various operations may be described as multiple discrete actions or operations in turn, in a manner that is most helpful in understanding the claimed subject matter. However, the order of description should not be construed as to imply that these operations are necessarily order dependent. In particular, these operations may not be performed in the order of presentation. Operations described may be performed in a different order than the described embodiment. Various additional operations may be performed or described operations may be omitted in additional embodiments.

For the purposes of the present disclosure, the phrases "A or B," "A and/or B," and

"A/B" mean (A), (B), or (A and B).

The description may use the phrases "in an embodiment," or "in embodiments," which may each refer to one or more of the same or different embodiments. Furthermore, the terms "comprising," "including," "having," and the like, as used with respect to embodiments of the present disclosure, are synonymous.

As used herein, including in the claims, 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.

Figure 1 illustrates an example network 100 that includes user equipment (UE) 105 and an evolved NodeB (e B) 110, in accordance with various embodiments. In

embodiments, the network 100 may be a third generation partnership project (3GPP) Long Term Evolution (LTE), LTE Advanced (LTE-A) LTE-Unlicensed (LTE-U), fifth generation (5G) network, and/or a new radio (NR) network. In other embodiments, the network 100 may be some other type of wireless communication network.

As shown in Figure 1, the UE 105 may include transceiver circuitry 120, which may also be referred to as a multi-mode transceiver chip. The transceiver circuitry 120 may be configured to transmit and receive signals using one or more protocols such as LTE, LTE- A, LTE-U, 5G, and/or NR protocols. Specifically, the transceiver circuitry 120 may be coupled with one or more of a plurality of antennas 160 of the UE 105 for communicating wirelessly with other components of the network 100, e.g., eNB 110 over radio link 115. The antennas 160 may be powered by the transceiver circuitry 120, for example, by a power amplifier which may be a component of the transceiver circuitry 120 as shown in Figure 1, or separate from but coupled with the transceiver circuitry 120. In one embodiment, the power amplifier may provide the power for all transmissions on the antennas 160. In other embodiments, there may be multiple power amplifiers on the UE 105. The use of multiple antennas 160 may allow for the UE 105 to use transmit diversity techniques such as spatial orthogonal resource transmit diversity (SORTD), multiple-input multiple-output (MTMO), or full-dimension MTMO (FD-MFMO).

In certain embodiments the transceiver circuitry 120 may include transmit circuitry

125 configured to cause the antennas 160 to transmit one or more signals from the UE 105, and receive circuitry 130 configured to process signals received by the antennas 160. In some embodiments, the transmit circuitry 125 and the receive circuitry 130 may be implemented as a single communication circuitry. In other embodiments, the transmit circuitry 125 and the receive circuitry 130 may be implemented in separate chips or modules, for example, one chip including the receive circuitry 130 and another chip including the transmit circuitry 125. In some embodiments, the transmitted or received signals may be cellular signals transmitted to or received from eNB 110. In some embodiments, the transceiver circuitry 120 may include or be coupled with messaging and timer control circuitry 135 to generate and process messages from eNBs and network 100, including Physical Downlink Control Channel (PDCCH) messages, Physical Downlink Shared Channel (PDSCH) messages, (Physical Uplink Shared Channel Messages (PUSCH), or the like, as described in further detail below, and to control, start, reset or stop timers on UE 105, such as reception of connection reconfiguration message timers, including T304 and T307. In some embodiments, the transceiver circuitry 120 and the timer control circuitry 135 may be provided in a single chip or apparatus within UE 105.

Similar to the UE 105, the eNB 110 may include transceiver circuitry 140. The transceiver circuitry 140 may be further coupled with one or more of a plurality of antennas 165 of the eNB 110 for communicating wirelessly with other components of the network 100, e.g., UE 105 over radio link 115. The antennas 165 may be powered by a power amplifier, or may be a separate component of the eNB 110. In one embodiment, the power amplifier may provide the power for all transmissions on the antennas 165. In other embodiments, there may be multiple power amplifiers on the eNB 110. The use of multiple antennas 165 may allow for the eNB 110 to use transmit diversity techniques such as SORTD, MEVIO, or FD-MEVIO. In certain embodiments the transceiver circuitry 140 may contain both transmit circuitry 145 configured to cause the antennas 165 to transmit one or more signals from the eNB 110, and receive circuitry 150 to process signals received by the antennas 165. In other embodiments, the transceiver circuitry 140 may be replaced by transmit circuitry 145 and receive circuitry 150 which are separate from one another (not shown). In some embodiments, the eNB 110 may include messaging circuitry 155, to generate and process messages to and from other eNBs, network 100 and UEs 105.

Figure 2 illustrates an example network 200 that includes a plurality of eNBs, in accordance with various embodiments. For example, the network 200 may include a plurality of eNBs such as eNBs 210a, 210b, 210c, and 210d. In embodiments, respective eNBs 210a-d may be similar to eNB 110. The network 200 may also include a UE 205, which may be similar to UE 105. In embodiments, the UE 105 may be able to communicate with the eNBs 210a-d over radio links 215a, 215b, 215c, 215d, which may be similar to radio link 115. It will be understood that although network 200 is shown to have four eNBs, in embodiments network 200 may have greater or fewer eNBs.

As noted above, RACH-less handovers are desirable so as to obviate the longer interruption delays that RACH procedures generate. A RACH attempt procedure during handovers typically takes—10—12 ms. An average handover procedure takes -40-50 ms to complete. Thus, eliminating -10-12 ms of RACH delay during a handover procedure can significantly reduce the data interruption during handovers and improve the user experience.

Generally, a RACH-less handover for small cell and intra-eNB cases may include one or more of: excluding the asynchronous RACH-less solution, or only considering a RACH-less solution where the timing advance (TA) value of the source cell is reused for the targeted cell, or where TA=0. It is noted that where a handover is to a small cell, having a small radius (less than 240 meters), the UE may use TA=0 for the target eNB.

An issue in performing RACH-less handovers is the handling by the UE of timers T304 and T307. In legacy LTE handover procedure, timers T304 and T307 are stopped when the Medium Access Control (MAC) successfully completes a random access procedure. In LTE, T304 is generally used as a safe-guard for the handover execution phase, when the UE has deemed the handover message valid and starts the handover execution. Table 1 below provides start, stop and expiry related actions in T304 and T307 handling. As can be seen in Table 1, each of T304 and T307 start upon receipt by the UE of a connection reconfiguration message, such as an RRCConnectionReconfiguration message: Timer Start Stop At Expiry

T304 Reception of Criterion for successful In case of cell change

RRCConnectionReconfiguration completion of handover order from E-UTRA message including the within Evolved or intra E-UTRA MobilityControl Info Universal Terrestrial handover, initiate the or Radio Access (E- Radio Resource reception of UTRA), Control (RRC)

MobilityFromEUTRA Command handover to E-UTRA connection re- message including or cell change order is establishment CellChangeOrder met (the criterion is procedure; In case of specified in the target handover to E- Radio Access UTRA, perform the Technology (RAT) in actions defined in the case of inter-RAT) specifications

applicable for the source RAT.

T307 Reception of Successful Inform E-UTRAN

RRCConnectionReconfiguration completion of random about the SCG message including the access on the Primary change failure by MobilityControlInfoSCG Secondary Cell initiating the SCG

(PSCell), upon failure information initiating re- procedure as establishment and upon specified in 5.6.13. Secondary Cell Group

(SCG) release

Table 1 - Start, Stop and Expiry For T304 and T307 Handling

As provided in 3 GPP Technical Specification (TS) 36.331, 13.2.0 (2016-07-11), the T304 stop condition (meaning a successful handover has occurred) is when the MAC successfully completes, as follows:

1> if MAC successfully completes the random access procedure:

2> stop timer T304.

The implication is that the UE starts a RACH procedure by sending the preamble to a target cell, and that the target cell then sends back a random access response (RAR) indicating that the RACH is successful. This also means that the target cell receives the RACH successfully from the UE and therefore the handover is successfully completed.

Embodiments herein may relate to how to handle T304 and T307 timers when a RACH-less handover (HO) is configured, and thus where no RAR is sent by the target cell. In embodiments, various options may be implemented to handle timers T304 and T307 for a RACH-less handover. In particular, options are presented for stopping these timers in absence of the legacy RAR message being received by the UE. Such options may include new features to be added to RACH-less handovers to obviate Timer 304 or 307 from attempting to re-establish upon their respective expirations. In embodiments, these timers may be stopped by circuitry provided in the UE, such as messaging and timer control circuitry 135, shown in Figure 1, and discussed above.

In a first embodiment, T304 or T307 may be stopped if the UE initiates the first transmission of Physical Uplink Shared Channel (PUSCH) message to the target Primary Cell (PCell). It is here noted, however, that when the UE initiates the first transmission of PUSCH to the target PCell, that does not mean that the transmission will be successful. This is in contrast to the standard RACH case, where a Random Access Response (RAR) is sent back to the UE to indicate the success of handover. Thus, in a RACH-less handover according to the first embodiment, where no response is actually sent back to the UE, and the sending by the UE of the initial PUSCH is assumed to result in a successful handover, it is still possible that the power default value is not accurate and that this causes the PCell not be able to receive the UE transmission. In this case, the UE will have Radio Link Failure (RLF), but the network will not be able to distinguish between RLF and hand-off failure (HOF).

In a second embodiment, T304 may be stopped when the UE receives a unicast

Physical Downlink Shared Channel (PDSCH) message or a unicast Physical Downlink Control Channel (PDCCH) message from a target e B after sending the first transmission of PUSCH to the target PCell.

Similarly, in this second embodiment, T307 may be stopped when the UE receives a unicast Physical Downlink Shared Channel (PDSCH) message or a unicast Physical

Downlink Control Channel PDCCH message from the target eNB after sending the first transmission of PUSCH to the target Primary Secondary Cell (PSCell). In this scenario the downlink unicast PDSCH may be an implicit indication to the UE that the network has received the first transmission of PUSCH to the target PCell and hence the handover is successful. However, if the network does not transmit the PDCCH/PDSCH for a long time, T304/T307 may expire, and the UE may then re-establish unnecessarily.

In this second embodiment, T304 may be stopped when the UE receives a Physical Downlink Control Channel (PDCCH) transmission addressed to its Cell Radio Network Temporary Identifier (C-RNTI) with a downlink assignment. In embodiments, the PDCCH transmission may contain contention resolution identity. In such embodiments, the Medium Access Control (MAC) may send an indication to Radio Resource Control when the UE receives the PDCCH to stop T304.

In a third embodiment, T304/T307 may be stopped by Radio Resource Control (RRC) signaling from the target to the UE indicating the successful reception of the

RRCConnectionReconfiguration message. This embodiment uses RRC to signal the UE as to the completion of handoff It is noted that this may introduce additional delay in the handoff procedure, but at the same time can guarantee the correct operation of the handover procedure.

In a fourth embodiment, T304/T307 may simply not be used for RACH-less handovers. However, it is noted that in this fourth embodiment, in the case of a handoff failure (HOF), because T310 would already be stopped when HO CMD is received, the UE would need to start from the beginning of the Radio Link Failure (RLF) procedure (i.e., perform Radio Link Monitoring (RLM), triggering an out-of-sync indication, start timer T310, and wait for T310 to expire). This may increase the delay of the re-establishment procedure. In this embodiment, it is noted, if T304/ T307 is not used, long re-establishment delay in case of HOF may be expected.

In a fifth embodiment, the second and third embodiments may be combined as follows: if the UE receives a PDCCH/PDSCH from a target e B, the target does not send a RRC signal, as described in the third embodiment. However, if there is no PDCCH/PDSCH received by the UE, then the target sends a RRC message to the UE. In this embodiment there may not be additional signaling required if a PDCCH/PDSCH is received from the target cell to the UE.

The following illustrates an example of a modified RRC signaling Information Element (IE) that may be used according to the third embodiment (added content in bold and slightly enlarged text):

RRCConnectionReconfiguration-vl310- : := SEQUENCE {

sCellToReleaseListExt-rI3 Need ON sCellToAddModListExt-rI3 Need ON lwa-Configuration-r13 Need ON lwip-Configuration-r13 Need ON rclwi-Configuration-r13 Need ON nonCriticalExtension

OPTIONAL

RRCConnectionReconfiguration-vxy-IEs : : = SEQUENCE {

handoverSuccess-rl3 ENUMERATED {true} OPTIONAL, — Need OR nonCriticalExtension SEQUENCE { } OPTIONAL

}

Referring now to Figures 3 and 4, overviews of operational flow for processes for termination of LTE timers T304 and T307 (described above), respectively, in RACH-less handovers, according to the second embodiment described above, are illustrated.

Referring to Fig. 3, process 300 may include operations performed at blocks 310- 330. The operations may be performed e.g., by the various elements of UE 105 earlier described with reference to Figure 1. In embodiments, process 300 looks for a PDSCH transmission from a target eNB in a RACH-less handover, and terminates timer T304 when it is received.

Process 300 may begin at block 310. At block 310, a UE sends a PUSCH

transmission to a target PCell. From block 310 process 300 may proceed to block 320, where it is determined whether the UE has received a responsive PDCCH/PDSCH

transmission from the target eNB servicing the cell. If Yes, process 300 may proceed to block 330, where a running T304 timer may be stopped, inasmuch as the target cell has responded. If, on the other hand, the result of the query at block 320 is No, then process 300 may remain at block 320, waiting for the PDCCH/ PDSCH transmission to be received. If the PDCCH/PDSCH transmission is not received, then timer T304 may expire on its own, triggering the actions to be taken at expiry, as provided above in Table 1.

Referring to Fig. 4, process 400 may include operations performed at blocks 410-

430. The operations may be performed e.g., by the various elements of UE 105 earlier described with reference to Figure 1. In embodiments, process 400 looks for a PDSCH transmission from a target eNB in a RACH-less handover, and terminates timer T307 when it is received.

Process 400 may begin at block 410. At block 410, a UE sends a PUSCH

transmission to a target PSCell. From block 410 process 400 may proceed to block 420, where it is determined whether the UE has received a responsive PDSCH transmission from the target eNB servicing the targeted secondary cell. If Yes, process 400 may proceed to block 430, where a running T307 timer may be stopped, inasmuch as the target cell has responded. If, on the other hand, the result of the query at block 420 is No, then process 400 may remain at block 420, waiting for the PDSCH transmission to be received from the target eNB. If the PDSCH transmission is not received, then timer T307 may expire on its own, triggering the actions to be taken at expiry, as provided above in Table 1, including initiating the Secondary Cell Group (SCG) failure information procedure.

Embodiments described herein may be implemented into a system using any suitably configured hardware and/or software. Figure 5 illustrates, for one embodiment, example components of an electronic device 500. In embodiments, the electronic device 500 may be, implement, be incorporated into, or otherwise be a part of a user equipment (UE), an evolved NodeB (eNB), and/or some other electronic device. In some

embodiments, the electronic device 500 may include application circuitry 502, baseband circuitry 504, Radio Frequency (RF) circuitry 506, front-end module (FEM) circuitry 508 and one or more antennas 510, coupled together at least as shown. In embodiments where the electronic device 500 is implemented in or by an eNB 210, the electronic device 500 may also include network interface circuitry (not shown) for communicating over a wired interface (for example, an X2 interface, an SI interface, and the like).

The application circuitry 502 may include one or more application processors. For example, the application circuitry 502 may include circuitry such as, but not limited to, one or more single-core or multi-core processors 502a. The processor(s) 502a may include any combination of general-purpose processors and dedicated processors (e.g., graphics processors, application processors, etc.). The processors 502a may be coupled with and/or may include computer-readable media 502b (also referred to as "CRM 502b", "memory 502b", "storage 502b", or "memory/storage 502b") and may be configured to execute instructions stored in the CRM 502b to enable various applications and/or operating systems to run on the system.

The baseband circuitry 504 may include circuitry such as, but not limited to, one or more single-core or multi-core processors. The baseband circuitry 504 may include one or more baseband processors and/or control logic to process baseband signals received from a receive signal path of the RF circuitry 506 and to generate baseband signals for a transmit signal path of the RF circuitry 506. Baseband circuity 504 may interface with the application circuitry 502 for generation and processing of the baseband signals and for controlling operations of the RF circuitry 506. For example, in some embodiments, the baseband circuitry 504 may include a second generation (2G) baseband processor 504a, third generation (3G) baseband processor 504b, fourth generation (4G) baseband processor 504c, and/or other baseband processor(s) 504d for other existing generations, generations in development or to be developed in the future (e.g., fifth generation (5G), 6G, etc.). The baseband circuitry 504 (e.g., one or more of baseband processors 504a-d) may handle various radio control functions that enable communication with one or more radio networks via the RF circuitry 506. The radio control functions may include, but are not limited to, signal modulation/demodulation, encoding/decoding, radio frequency shifting, and the like. In some embodiments, modulation/demodulation circuitry of the baseband circuitry 504 may include Fast-Fourier Transform (FFT), precoding, and/or constellation

mapping/demapping functionality. In some embodiments, encoding/decoding circuitry of the baseband circuitry 504 may include convolution, tail-biting convolution, turbo, Viterbi, and/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.

In some embodiments, the baseband circuitry 504 may include elements of a protocol stack such as, for example, elements of an evolved universal terrestrial radio access network (E-UTRAN) protocol including, for example, physical (PHY), media access control (MAC), radio link control (RLC), packet data convergence protocol (PDCP), and/or radio resource control (RRC) elements. A central processing unit (CPU) 504e of the baseband circuitry 504 may be configured to run elements of the protocol stack for signaling of the PHY, MAC, RLC, PDCP and/or RRC layers. In some embodiments, the baseband circuitry may include one or more audio digital signal processor(s) (DSP) 504f. The audio DSP(s) 504f may include elements for compression/decompression and echo cancellation and may include other suitable processing elements in other embodiments. The baseband circuitry 504 may further include computer-readable media 504b (also referred to as "CRM 504b", "memory 504b", "storage 504b", or "CRM 5042b"). The CRM 504g may be used to load and store data and/or instructions for operations performed by the processors of the baseband circuitry 504. CRM 504g for one embodiment may include any

combination of suitable volatile memory and/or non-volatile memory. The CRM 504g may include any combination of various levels of memory/storage including, but not limited to, read-only memory (ROM) having embedded software instructions (e.g., firmware), random access memory (e.g., dynamic random access memory (DRAM)), cache, buffers, etc.). The CRM 504g may be shared among the various processors or dedicated to particular processors. Components of the baseband circuitry 504 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 504 and the application circuitry 502 may be implemented together, such as, for example, on a system on a chip (SOC).

In some embodiments, the baseband circuitry 504 may provide for communication compatible with one or more radio technologies. For example, in some embodiments, the baseband circuitry 504 may support communication with an E-UTRAN and/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 504 is configured to support radio communications of more than one wireless protocol may be referred to as multi-mode baseband circuitry.

RF circuitry 506 may enable communication with wireless networks using modulated electromagnetic radiation through a non-solid medium. In various embodiments, the RF circuitry 506 may include switches, filters, amplifiers, etc., to facilitate the communication with the wireless network. RF circuitry 506 may include a receive signal path that may include circuitry to down-convert RF signals received from the FEM circuitry 508 and provide baseband signals to the baseband circuitry 504. RF circuitry 506 may also include a transmit signal path that may include circuitry to up-convert baseband signals provided by the baseband circuitry 504 and provide RF output signals to the FEM circuitry 508 for transmission.

In some embodiments, the RF circuitry 506 may include a receive signal path and a transmit signal path. The receive signal path of the RF circuitry 506 may include mixer circuitry 506a, amplifier circuitry 506b and filter circuitry 506c. The transmit signal path of the RF circuitry 506 may include filter circuitry 506c and mixer circuitry 506a. RF circuitry 506 may also include synthesizer circuitry 506d for synthesizing a frequency for use by the mixer circuitry 506a of the receive signal path and the transmit signal path. In some embodiments, the mixer circuitry 506a of the receive signal path may be configured to down-convert RF signals received from the FEM circuitry 508 based on the synthesized frequency provided by synthesizer circuitry 506d. The amplifier circuitry 506b may be configured to amplify the down-converted signals and the filter circuitry 506c 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 504 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 506a of the receive signal path may comprise passive mixers, although the scope of the embodiments is not limited in this respect.

In some embodiments, the mixer circuitry 506a of the transmit signal path may be configured to up-convert input baseband signals based on the synthesized frequency provided by the synthesizer circuitry 506d to generate RF output signals for the FEM circuitry 508. The baseband signals may be provided by the baseband circuitry 504 and may be filtered by filter circuitry 506c. The filter circuitry 506c may include a low-pass filter (LPF), although the scope of the embodiments is not limited in this respect.

In some embodiments, the mixer circuitry 506a of the receive signal path and the mixer circuitry 506a of the transmit signal path may include two or more mixers and may be arranged for quadrature downconversion and/or upconversion, respectively. In some embodiments, the mixer circuitry 506a of the receive signal path and the mixer circuitry 506a 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 506a of the receive signal path and the mixer circuitry 506a of the transmit signal path may be arranged for direct downconversion and/or direct upconversion, respectively. In some embodiments, the mixer circuitry 506a of the receive signal path and the mixer circuitry 506a of the transmit signal path may be configured for super-heterodyne operation.

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 506 may include analog-to-digital converter (ADC) and digital-to-analog converter (DAC) circuitry and the baseband circuitry 504 may include a digital baseband interface to communicate with the RF circuitry 506.

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.

In some embodiments, the synthesizer circuitry 506d 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 506d may be a delta-sigma synthesizer, a frequency multiplier, or a synthesizer comprising a phase-locked loop with a frequency divider. The synthesizer circuitry 506d may be configured to synthesize an output frequency for use by the mixer circuitry 506a of the RF circuitry 506 based on a frequency input and a divider control input. In some embodiments, the synthesizer circuitry 506d may be a fractional N/N+l synthesizer.

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 504 or the application circuitry 502 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 application circuitry 502.

Synthesizer circuitry 506d of the RF circuitry 506 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 (DP A). 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.

In some embodiments, synthesizer circuitry 506d 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 506 may include an IQ/polar converter.

FEM circuitry 508 may include a receive signal path that may include circuitry configured to operate on RF signals received from one or more antennas 510, amplify the received signals and provide the amplified versions of the received signals to the RF circuitry 506 for further processing. FEM circuitry 508 may also include a transmit signal path that may include circuitry configured to amplify signals for transmission provided by the RF circuitry 506 for transmission by one or more of the one or more antennas 510. In some embodiments, the FEM circuitry 508 may include a TX/RX switch to switch between transmit mode and receive mode operation. The FEM circuitry 508 may include a receive signal path and a transmit signal path. The receive signal path of the FEM circuitry 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 506). The transmit signal path of the FEM circuitry 508 may include a power amplifier (PA) to amplify input RF signals (e.g., provided by RF circuitry 506), and one or more filters to generate RF signals for subsequent transmission (e.g., by one or more of the one or more antennas 510).

In some embodiments, the electronic device 500 may include additional elements such as, for example, a display, a camera, one or more sensors, and/or interface circuitry (for example, input/output (I/O) interfaces or buses) (not shown). In embodiments where the electronic device is implemented in or by an e B, the electronic device 500 may include network interface circuitry. The network interface circuitry may be one or more computer hardware components that connect electronic device 500 to one or more network elements, such as one or more servers within a core network or one or more other e Bs via a wired connection. To this end, the network interface circuitry may include one or more dedicated processors and/or field programmable gate arrays (FPGAs) to communicate using one or more network communications protocols such as X2 application protocol (AP), SI AP, Stream Control Transmission Protocol (SCTP), Ethernet, Point-to-Point (PPP), Fiber Distributed Data Interface (FDDI), and/or any other suitable network communications protocols.

In some embodiments, the electronic device of Figure 5 may be configured to perform one or more processes, techniques, and/or methods as described herein, or portions thereof.

Figure 6 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 machine-readable storage medium) and perform any one or more of the methodologies discussed herein. Specifically, Figure 6 shows a diagrammatic

representation of computer system 600 including one or more processors (or processor cores) 610, one or more computer-readable media 620, and one or more communication resources 630, each of which are communicatively coupled via one or more interconnects 630. The processors 610 may include one or more central processing unit ("CPUs"), reduced instruction set computing ("RISC") processors, complex instruction set computing ("CISC") processors, graphics processing units ("GPUs"), digital signal processors ("DSPs") implemented as a baseband processor, for example, application specific integrated circuits ("ASICs"), radio-frequency integrated circuits (RFICs), etc. As shown, the processors 610 may include, a processor 612 and a processor 614.

The computer-readable media 620 may be suitable for use to store instructions 650 that cause the computer system 600, in response to execution of the instructions 650 by one or more of the processors 610, to practice selected aspects of the present disclosure described with respect to the UE, an eNB, and/or a location server. In some embodiments, the computer-readable media 620 may be non-transitory. As shown, computer-readable storage medium 620 may include instructions 650. The instructions 650 may be

programming instructions or computer program code configured to enable the computer system 600, which may be implemented as the UE 105 or 205, in response to execution of the instructions 650, to implement (aspects of) any of the methods or elements described throughout this disclosure related to RSTD reporting. In some embodiments, programming instructions 650 may be disposed on computer-readable media 650 that is transitory in nature, such as signals.

Any combination of one or more computer-usable or computer-readable media may be utilized as the computer-readable media 620. The computer-readable media 620 may be, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, device, or propagation medium. More specific examples (a non-exhaustive list) of the computer-readable media would include the following: an electrical connection having one or more wires, a portable computer diskette, a hard disk, RAM, ROM, an erasable programmable read-only memory (for example,

EPROM, EEPROM, or Flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a transmission media such as those supporting the Internet or an intranet, or a magnetic storage device. Note that the computer- usable or computer-readable media could even be paper or another suitable medium upon which the program is printed, as the program can be electronically captured, via, for instance, optical scanning of the paper or other medium, then compiled, interpreted, or otherwise processed in a suitable manner, if necessary, and then stored in a computer memory. In the context of this document, a computer-usable or computer-readable media may be any medium that can contain, store, communicate, propagate, or transport the program for use by or in connection with the instruction execution system, apparatus, or device. The computer-usable media may include a propagated data signal with the computer-usable program code embodied therewith, either in baseband or as part of a carrier wave. The computer-usable program code may be transmitted using any appropriate medium, including but not limited to wireless, wireline, optical fiber cable, radio frequency, etc.

Computer program code for carrying out operations of the present disclosure may be written in any combination of one or more programming languages, including an object oriented programming language such as Java, Smalltalk, C++ or the like and conventional procedural programming languages, such as the "C" programming language or similar programming languages. The program code may execute entirely on the user's computer, partly on the user's computer, as a stand-alone software package, partly on the user's computer and partly on a remote computer or entirely on the remote computer or server. In the latter scenario, the remote computer may be connected to the user's computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or the connection may be made to an external computer (for example, through the Internet using an Internet Service Provider).

As shown in Figure 6, instructions 650 may reside, completely or partially, within at least one of the processors 610 (e.g., within the processor's cache memory), the computer- readable media 620, or any suitable combination thereof. Furthermore, any portion of the instructions 650 may be transferred to the computer system 600 from any combination of the peripheral devices 604 and/or the databases 606. Accordingly, the memory of processors 610, the peripheral devices 606, and the databases 606 are additional examples of computer-readable media.

The communication resources 630 may include interconnection and/or network interface components or other suitable devices to communicate with one or more peripheral devices 604 and/or one or more databases 606 via a network 608. For example, the communication resources 630 may include wired communication components (e.g., for coupling via a Universal Serial Bus (USB)), cellular communication components, Near Field Communication (NFC) components, Bluetooth® components (e.g., Bluetooth® Low Energy), Wi-Fi® components, and other communication components. In some

embodiments, the communication resources 630 may include a cellular modem to communicate over a cellular network, an Ethernet controller to communicate over an Ethernet network, etc. In some embodiments, one or more components of computer system 600 may be included as a part of a UE (for example, UE 105 or 205 of Figures 1 and 2) or an e B (for example, eNB 110, 210a, 210b, 210c, and/or 210d). For example, messaging and timer control circuitry 135, messaging circuitry 155, or baseband circuitry 604 may include processors 610, computer-readable media 620, or communication resources 630 to facilitate operations described above with respect to the UE, eNB, or some other element such as the location server.

The present disclosure is described with reference to flowchart illustrations or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the disclosure. It will be understood that each block of the flowchart illustrations or block diagrams, and combinations of blocks in the flowchart illustrations or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create a means for implementing the

functions/acts specified in the flowchart or block diagram block or blocks.

These computer program instructions may also be stored in a computer-readable medium that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable medium produce an article of manufacture including instruction means that implement the function/act specified in the flowchart or block diagram block or blocks.

The computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions that execute on the computer or other programmable apparatus provide processes for implementing the functions/acts specified in the flowchart or block diagram block or blocks.

Some non-limiting examples are provided below.

Example 1 may include an apparatus of a user equipment (UE) for handling timers, comprising transceiver circuitry to send, as part of a random access channel (RACH)-less handover, a transmission to a target cell in a cellular communications network and receive a responsive message from a base station of the target cell, and timer control circuitry coupled to the transceiver circuitry to stop a reception of connection reconfiguration message timer if the responsive message is received.

Example 2 may include the apparatus of a UE of example 1 or some other example herein wherein the target cell is a target primary cell (PCell).

Example 3 may include the apparatus of a UE of example 2 or some other example herein, wherein the first transmission to the target PCell is a physical uplink shared channel (PUSCH) transmission.

Example 4 may include the apparatus of a UE of any of examples 1-3 or some other example herein, wherein the base station of the target cell is an evolved node B (eNB).

Example 5 may include the apparatus of a UE of example 4 or some other example herein, wherein the responsive message is either a physical downlink shared channel (PDSCH) transmission or a physical downlink control channel (PDCCH) transmission.

Example 6 may include the apparatus of a UE of example 4 or some other example herein, wherein the reception of connection reconfiguration message timer is a T304 timer.

Example 7 may include the apparatus of a UE of any one of examples 1-3 or some other example herein, wherein the target cell is a target primary secondary cell (PSCell) and the base station of the target cell is an eNB.

Example 8 may include the apparatus of a UE of example 7 or some other example herein, wherein the reception of connection reconfiguration message timer is a T307 timer.

Example 9 may include the apparatus of a UE of example 1 or some other example herein, wherein the transceiver circuitry is further to receive a connection reconfiguration message from the base station of the target cell.

Example 10 may include the apparatus of a UE of example 9 or some other example herein, wherein if no responsive message is received from the base station of the target cell, but the UE receives a signal from the target cell indicating successful reception of an

RRCConnectionReconfiguration message, the timer control circuitry stops the reception of connection reconfiguration message timer.

Example 11 may include one or more computer-readable media comprising instructions to cause a user equipment (UE), upon execution of the instructions by one or more processors of the UE, to send, as part of a random access channel-less handover, a first transmission to a target cell in a cellular communications network, receive a responsive message from an eNB of the target cell, and stop a reception of connection reconfiguration message timer if the responsive message is received. Example 12 may include the one or more computer-readable media of example 11 or some other example herein, wherein the first transmission is a PUSCH.

Example 13 may include the one or more computer-readable media of example 11 or some other example herein, wherein the responsive message is a unicast PDCCH or PDSCH.

Example 14 may include any one of the one or more computer-readable media of examples 11-13 or some other example herein, wherein the target cell is a PCell and the reception of connection reconfiguration message timer is a T304 timer.

Example 15 may include any one of the one or more computer-readable media of examples 11-13 or some other example herein, wherein the target cell is a PSCell and the reception of connection reconfiguration message timer is a T307 timer.

Example 16 may include the one or more computer-readable media of example 14 or some other example herein, wherein, upon execution, the instructions further cause the UE to receive connection reconfiguration messages from the e B of the target cell.

Example 17 may include the one or more computer-readable media of example 16 or some other example herein, wherein, upon execution, the instructions further cause the UE, if no responsive message is received from the eNB of the target cell, but the UE receives a signal from the target cell indicating successful reception of an

RRCConnectionReconfiguration message, to stop the T304 timer.

Example 18 may include the one or more computer-readable media of example 11 or some other example herein, wherein the responsive message is a Physical Downlink Control Channel (PDCCH) transmission addressed to a Cell Radio Network Temporary Identifier (C-RNTI) of the UE with a downlink assignment.

Example 19 may include a method for handling timers in random access channel (RACH)-less handovers, comprising sending, by a user equipment (UE) as part of a random access channel-less handover, a first transmission to a target cell in a cellular

communications network, receiving, by the UE, a responsive message from a base station of the target cell, and stopping, by the UE, a reception of connection reconfiguration message timer following receipt of the responsive message.

Example 20 may include the method of example 19 or some other example herein, wherein the target cell is a target PCell, and the first transmission is a PUSCH transmission.

Example 21 may include the method of example 19 or some other example herein, wherein the target cell is a target PSCell and the reception of connection reconfiguration message timer is a T307 timer. Example 22 may include the method of example 21 or some other example herein, wherein the responsive message is one of a PDCCH or a PDSCH transmission.

Example 23 may include the method of example 21 or some other example herein, wherein the base station of the target cell is an e B, and the reception of connection reconfiguration message timer is a T304 timer.

Example 24 may include the method of example 21 or some other example herein, wherein the responsive message is a Physical Downlink Control Channel (PDCCH) transmission addressed to a Cell Radio Network Temporary Identifier (C-RNTI) of the UE with a downlink assignment.

Example 25 may include the method of example 20 or some other example herein, wherein if no responsive message is received from the base station of the target cell, but the UE receives a signal from the target cell indicating successful reception of an

RCConnectionReconfiguration message, stopping, by the UE, the reception of connection reconfiguration message timer.

Example 26 may include apparatus, comprising control logic, transmit logic and/or receive logic to perform one or more elements of the methods of any one of claims 19-25.

Example 27 may include a user equipment (UE) for handling timers in random access channel (RACH)-less handovers, comprising transceiver circuitry to send, as part of a RACH-less handover, a transmission to a target cell in a cellular communications network, and timer control circuitry coupled to the transceiver circuitry to stop a reception of connection reconfiguration message timer when the transmission is sent.

Example 28 may include the UE of example 27 or some other example herein, wherein the target cell is a target primary cell (PCell).

Example 28 may include the UE of examples 27 or 28 or some other example herein, wherein the first transmission to the target PCell is a physical uplink shared channel (PUSCH) transmission.

Example 30 may include the UE of example 29 or some other example herein, wherein the reception of connection reconfiguration message timer is a T304 timer.

Example 31 may include the UE of example 27 or some other example herein, wherein the target cell is a target primary secondary cell (PSCell).

Example 32 may include the UE of example 31 or some other example herein, wherein the reception of connection reconfiguration message timer is a T307 timer.

Example 33 may include one or more computer-readable media comprising instructions to cause a user equipment (UE), upon execution of the instructions by one or more processors of the UE, to send, as part of a random access channel-less handover, a transmission to a target cell in a cellular communications network, and stop a reception of connection reconfiguration message timer when the transmission is sent.

Example 34 may include the one or more computer-readable media of example 33 or some other example herein, wherein the first transmission is a PUSCH.

Example 35 may include the one or more computer-readable media of either examples 33 or 34 or some other example herein, wherein the target cell is a target primary cell (PCell).

Example 36 may include the one or more computer-readable media of example 33 or some other example herein, wherein the target cell is a target primary secondary cell (PSCell).

Example 37 may include the one or more computer-readable media of either examples 33 or 34 or some other example herein, wherein the reception of connection reconfiguration message timer is a T307 timer.

Example 38 may include a user equipment (UE) for handling timers in random access channel (RACH)-less handovers, comprising transceiver circuitry to send, as part of a RACH-less handover, a transmission to a target cell in a cellular communications network, and timer control circuitry coupled to the transceiver circuitry to stop a reception of connection reconfiguration message timer if a message is received from the target indicating the target's successful reception of a connection reconfiguration message.

Example 39 may include the UE of example 38 or other example herein, wherein the message received from the target includes an indication of completion of handoff from another base station.

Example 40 may include the UE of either of examples 38 or 39 or other example herein, wherein the message is received via Radio Resource Control (RRC) signaling from the target to the UE.

Example 41 may include the UE of any one of examples 38-40 or other example herein, wherein the message indicates that the target has received an

RRCConnectionReconfiguration message augmented with a handover success field.

Example 42 may include the UE of example 38 or other example herein, wherein the transceiver circuitry is further to receive a responsive message from a base station of the target cell, and wherein if no message is received from the target indicating the target's successful reception of a connection reconfiguration message, but the UE receives a responsive message from the base station of the target cell, the timer control circuitry stops the reception of connection reconfiguration message timer.

Example 43 may include the UE of example 42 or any other example herein, wherein the responsive message is either a physical downlink shared channel (PDSCH) transmission or a physical downlink control channel (PDCCH) transmission.

Example 44 may include apparatus for handling timers in random access channel (RACH)-less handovers, comprising means to send, as part of a RACH-less handover, a transmission to a target cell in a cellular communications network, means to receive a responsive message from a base station of the target cell, and means coupled to the means to receive to stop a reception of connection reconfiguration message timer if the responsive message is received.

Example 45 may include the apparatus of example 44 or any other example herein, wherein the target cell is a target primary cell (PCell).

Example 46 may include the apparatus of example 45 or any other example herein, wherein the transmission to the target PCell is a physical uplink shared channel (PUSCH) transmission.

Example 47 may include the apparatus of any one of examples 44-46 or any other example herein, wherein the base station of the target cell is an evolved node B (eNB).

Example 48 may include the apparatus of example 47 or any other example herein, wherein the responsive message is either a physical downlink shared channel (PDSCH) transmission or a physical downlink control channel (PDCCH) transmission.

Example 49 may include the apparatus of example 47 or any other example herein, wherein the reception of connection reconfiguration message timer is a T304 timer.

Example 50 may include the apparatus of any one of examples 44-47 or any other example herein, wherein the target cell is a target primary secondary cell (PSCell) and the base station of the target cell is an eNB.

Example 51 may include the apparatus of example 50 or any other example herein, wherein the reception of connection reconfiguration message timer is a T307 timer.

Example 52 may include the apparatus of example 50 or any other example herein, wherein the means to receive is further to receive a connection reconfiguration message from the base station of the target cell.

Example 53 may include the apparatus of example 52 or any other example herein, wherein if no responsive message is received from the base station of the target cell, but the apparatus receives a signal from the target indicating successful reception of an RCConnectionReconfiguration message, the means to stop stops the reception of connection reconfiguration message timer.

Example 54 may include apparatus for handling timers in random access channel (RACH)-less handovers, comprising means to send, as part of a RACH-less handover, a transmission to a target cell in a cellular communications network, means to receive messages from the target cell, and means coupled to the means to receive to stop a reception of connection reconfiguration message timer if a message is received from the target indicating the target's successful reception of a connection reconfiguration message.

Example 55 may include the apparatus of example 54 or any other example herein, wherein the message received form the target includes an indication of completion of handoff from another base station.

Example 56 may include the apparatus of either of examples 54 or 55, wherein the message is received via Radio Resource Control (RRC) signaling from the target to the apparatus.

Example 57 may include the apparatus of any one of examples 54-56, wherein the message indicates that the target has received an RRCConnectionReconfiguration message augmented with a handover success field.

Example 58 may include a user equipment (UE) for handling timers in random access channel (RACH)-less handovers, comprising transceiver circuitry to send, as part of a RACH-less handover, a transmission to a target cell in a cellular communications network and receive a responsive message from a base station of the target cell, and timer control circuitry coupled to the transceiver circuitry to stop a reception of connection

reconfiguration message timer if the responsive message is received.

Example 59 may include the UE of example 58 or some other example herein wherein the target cell is a target primary cell (PCell).

Example 60 may include the UE of example 59 or some other example herein, wherein the first transmission to the target PCell is a physical uplink shared channel (PUSCH) transmission.

Example 61 may include the UE of any of examples 58-60 or some other example herein, wherein the base station of the target cell is an evolved node B (eNB).

Example 62 may include the UE of example 61 or some other example herein, wherein the responsive message is either a physical downlink shared channel (PDSCH) transmission or a physical downlink control channel (PDCCH) transmission. Example 63 may include the UE of example 61 or some other example herein, wherein the reception of connection reconfiguration message timer is a T304 timer.

Example 64 may include the UE of any one of examples 58-60 or some other example herein, wherein the target cell is a target primary secondary cell (PSCell) and the base station of the target cell is an e B.

Example 65 may include the UE of example 64 or some other example herein, wherein the reception of connection reconfiguration message timer is a T307 timer.

Example 66 may include the UE of example 58 or some other example herein, wherein the transceiver circuitry is further to receive a connection reconfiguration message from the base station of the target cell.

Example 67 may include the UE of example 66 or some other example herein, wherein if no responsive message is received from the base station of the target cell, but the UE receives a signal from the target cell indicating successful reception of an

The foregoing description of one or more implementations provides illustration and description, but is not intended to be exhaustive or to limit the scope of embodiments to the precise form disclosed. Modifications and variations are possible in light of the above teachings or may be acquired from practice of various embodiments.

Claims

1. A user equipment (UE) for handling timers, comprising:

transceiver circuitry to:

send, as part of a random access channel (RACH)-less handover, a transmission to a target cell in a cellular communications network; and

receive a responsive message from a base station of the target cell;

and

timer control circuitry coupled to the transceiver circuitry to:

stop a reception of connection reconfiguration message timer if the responsive message is received.

2. The UE of claim 1, wherein the target cell is a target primary cell (PCell).

3. The UE of claim 2, wherein the transmission to the target PCell is a physical uplink shared channel (PUSCH) transmission.

4. The UE of any one of claims 1-3, wherein the base station of the target cell is an evolved node B (eNB).

5. The UE of claim 4, wherein the responsive message is either a physical downlink shared channel (PDSCH) transmission or a physical downlink control channel (PDCCH) transmission.

6. The UE of claim 4, wherein the connection reconfiguration receipt timer is a T304 timer.

7. The UE of any one of claims 1-3, wherein the target cell is a target primary secondary cell (PSCell) and the base station of the target cell is an eNB.

8. The UE of claim 7, wherein the connection reconfiguration receipt timer is a T307 timer.

9. The UE of claim 1, wherein the transceiver circuitry is further to receive a connection reconfiguration message from the base station of the target cell.

10. The UE of claim 9, wherein if no responsive message is received from the base station of the target cell, but the UE receives a signal from the target indicating successful reception of an RRCConnectionReconfiguration message, the timer control circuitry stops the connection reconfiguration receipt timer.

11. One or more computer-readable media comprising instructions to cause a user equipment (UE), upon execution of the instructions by one or more processors of the UE, to: send, as part of a random access channel-less handover, a first transmission to a target cell in a cellular communications network;

receive a responsive message from an eNB of the target cell; and

12. The one or more computer-readable media of claim 11, wherein the first transmission is a PUSCH.

13. The one or more computer-readable media of claim 11, wherein the responsive message is a unicast PDCCH or PDSCH.

14. The one or more computer-readable media of any one of claims 11-13, wherein the target cell is a PCell and the reception of connection reconfiguration message timer is a T304 timer.

15. The one or more computer-readable media of any one of claims 11-13, wherein the target cell is a PSCell and the reception of connection reconfiguration message timer is a T307 timer.

16. The one or more computer-readable media of claim 14, wherein, upon execution, the instructions further cause the UE to receive connection reconfiguration messages from the eNB of the target cell.

17. The one or more computer-readable media of claim 16, wherein, upon execution, the instructions further cause the UE, if no responsive message is received from the eNB of the target cell, but the UE receives a signal from the target indicating successful reception of an RRCConnectionReconfiguration message, to stop the T304 timer.

18. The one or more computer-readable media of claim 11, wherein the responsive message is a Physical Downlink Control Channel (PDCCH) transmission addressed to a Cell Radio Network Temporary Identifier (C-RNTI) of the UE with a downlink assignment.

19. A method for handling timers in random access channel (RACH)-less handovers, comprising:

sending, by a user equipment (UE) as part of a random access channel-less handover, a transmission to a target cell in a cellular communications network;

receiving, by the UE, a responsive message from a base station of the target cell; and stopping, by the UE, a reception of connection reconfiguration message timer following receipt of the responsive message.

20. The method of claim 19, wherein the target cell is a target PCell, and the transmission is a PUSCH transmission.

21. The method of claim 19, wherein the target cell is a target PSCell and the reception of connection reconfiguration message timer is a T307 timer.

22. The method of claim 20, wherein the base station of the target cell is an eNB, and the reception of connection reconfiguration message timer is a T304 timer.

23. The method of claim 22, wherein the responsive message is a Physical

Downlink Control Channel (PDCCH) transmission addressed to a Cell Radio Network Temporary Identifier (C-RNTI) of the UE with a downlink assignment.

24. The method of claim 19, wherein if no responsive message is received from the base station of the target cell, but the UE receives a signal from the target indicating successful reception of an RRCConnectionReconfiguration message, stopping, by the UE, the connection reconfiguration receipt timer.

25. Apparatus, comprising control logic, transmit logic and/or receive logic to perform one or more elements of the methods of any one of claims 19-24.