Communication device, infrastructure equipment and method

Abstract

A communication device is provided. The communication device includes transceiver circuitry and controller circuitry. The transceiver circuitry is configured to transmit signals to and / or receive signals from a first cell of a wireless communication network. The controller circuitry is configured, in combination with the transceiver circuitry, to: determine that the communication device will perform a handover process from the first cell to a second cell of the wireless communication network; measure the difference between the start of a first radio frame received from the first cell and the start of a second radio frame received from the second cell; and during the handover process, determine at least one of a propagation delay value of the second cell and a timing advance value of the second cell based on the measured difference. The propagation delay of the second cell defines the time required for a signal to propagate unidirectionally between the communication device and the second cell, and the timing advance of the second cell defines the time required for a signal to propagate round-trip between the communication device and the second cell.

Description

Technical Field

[0001] This disclosure relates to communication apparatus configured to transmit data to and receive data from a wireless communication network, as well as infrastructure equipment forming part of the wireless communication network.

[0002] This application claims priority under the Paris Convention for European Patent Application No. EP20169971.7, the contents of which are incorporated herein by reference. Background Technology

[0003] The “background” description provided herein is intended to provide a general context for this disclosure. To the extent described in this background section, the work of the currently named inventors and aspects of the description that may not be considered prior art at the time of filing are neither explicitly nor implicitly considered to be prior art to this invention.

[0004] Third and fourth generation mobile telecommunications systems (e.g., mobile telecommunications systems based on the UMTS and LTE architectures defined by 3GPP) are capable of supporting more complex services than the simple voice and messaging services offered by previous generations of mobile telecommunications systems. For example, through the improved radio interface and enhanced data rates provided by LTE systems, users can enjoy high-data-rate applications, such as mobile video streaming and mobile video conferencing, which were previously only available via fixed-line data connections. Therefore, the demand for deploying such networks is significant, and the coverage areas of these networks (i.e., geographical locations where network access is available) are likely to increase more rapidly.

[0005] Future wireless communication networks are expected to routinely and efficiently support communication with a wider range of devices than currently optimized for, and these devices will be associated with a broader range of data traffic profiles and types. For example, future wireless communication networks are expected to efficiently support communication with devices including reduced-complexity devices, machine-type communication (MTC) devices, high-resolution video displays, virtual reality headsets, and so on. Some of these different types of devices can be deployed in large numbers, for example, low-complexity devices to support the “Internet of Things”, and can typically be associated with the transmission of smaller amounts of data with higher latency tolerance.

[0006] In light of this, it is expected that future wireless communication networks, such as those that may be referred to as 5G or New Radio (NR) systems / New Radio Access Technology (RAT) systems, as well as future iterations / versions of existing systems, will support connectivity for a wide range of devices that are effectively associated with different applications and data service profiles with different characteristics.

[0007] The increasing use of different types of network infrastructure equipment and terminal devices associated with different service profiles poses new challenges to the effective processing of communications in wireless telecommunications systems. Summary of the Invention

[0008] This disclosure can help resolve or mitigate at least some of the problems discussed above.

[0009] A first embodiment of this technology may provide a communication device. The communication device includes transceiver circuitry and controller circuitry. The transceiver circuitry is configured to transmit signals to and / or receive signals from a first cell of a wireless communication network. The controller circuitry is configured to combine with the transceiver circuitry to: determine that the communication device will perform a handover process from the first cell to a second cell of the wireless communication network; measure the difference between the start of a first radio frame received from the first cell and the start of a second radio frame received from the second cell; and during the handover process, determine at least one of a propagation delay value of the second cell and a timing advance value of the second cell based on the measured difference. The propagation delay of the second cell defines the time required for a signal to propagate unidirectionally between the communication device and the second cell, and the timing advance of the second cell defines the time required for a signal to propagate round-trip between the communication device and the second cell.

[0010] A second embodiment of this technology provides a communication device. The communication device includes transceiver circuitry and controller circuitry. The transceiver circuitry is configured to transmit signals to and / or receive signals from a first cell of a wireless communication network. The controller circuitry is configured, in combination with the transceiver circuitry, to: determine that the communication device will perform a handover process from the first cell to a second cell of the wireless communication network; transmit an uplink reference signal to the second cell in communication resources pre-allocated to the communication device and in which the communication device can transmit signals; and, in response to the transmitted uplink reference signal, receive from the first cell at least one of a propagation delay value and a timing advance value of the second cell from one or more messages of the handover process, the propagation delay of the second cell defining the time taken for a signal to propagate unidirectionally between the communication device and the second cell, and the timing advance of the second cell defining the time taken for a signal to propagate round-trip between the communication device and the second cell.

[0011] In addition to communication devices, embodiments of this technology also relate to infrastructure equipment, methods for operating communication devices and infrastructure equipment, and circuitry for communication devices and infrastructure equipment, providing solutions that allow for the execution of random access-free (RACH) handover procedures, regardless of the importance of propagation delay.

[0012] The various aspects and features of this disclosure are defined in the appended claims.

[0013] It should be understood that the foregoing general description and the following detailed description are exemplary of the technology and not limiting. The described embodiments and further advantages will be best understood by referring to the following detailed description taken in conjunction with the accompanying drawings. Attached Figure Description

[0014] A more complete understanding of this disclosure and its many accompanying advantages will readily be obtained when considered in conjunction with the accompanying drawings and by referring to the following detailed description, wherein, in several views, the same reference numerals denote the same or corresponding parts, and wherein:

[0015] Figure 1 These illustrations represent aspects of an LTE-type wireless telecommunications system that can be configured to operate according to certain embodiments of this disclosure.

[0016] Figure 2 This schematically illustrates some aspects of a novel Radio Access Technology (RAT) wireless communication system that can be configured to operate according to certain embodiments of this disclosure;

[0017] Figure 3 It is shown in more detail in Figure 2 A schematic block diagram of some components of a wireless communication system is provided to illustrate exemplary embodiments of the present technology.

[0018] Figure 4 This is a schematic representation of the steps in the four-step random access (RACH) process in a wireless telecommunications network;

[0019] Figure 5 This is a schematic representation of an example of uplink data transmission from a communication device in RRC_INACTIVE mode with a downlink response from the network;

[0020] Figure 6 This is a schematic representation of an example four-step RACH process that can be applied to a small amount of data transmission;

[0021] Figure 7 This is a schematic representation of an example two-step RACH process that can be applied to a small amount of data transmission;

[0022] Figure 8 This is a schematic representation of the steps in a two-step RACH process in a wireless telecommunications network;

[0023] Figure 9 It is a signaling ladder diagram that schematically represents various aspects of a known switching process;

[0024] Figure 10 This is a partial schematic representation and partial message flow diagram of communication between a communication device and a wireless communication network according to embodiments of the present technology.

[0025] Figure 11 The propagation delay difference between the serving and target cells at a user equipment (UE) according to an embodiment of the present technology is shown; and

[0026] Figure 12 A flowchart illustrating a method of operating a communication device according to an embodiment of the present technology is shown. Detailed Implementation

[0027] Long Term Evolution (LTE) Advanced Wireless Access Technology (4G)

[0028] Figure 1 A schematic diagram is provided illustrating some basic functions of a mobile telecommunications network / system 100, which typically operates based on LTE principles but may also support other radio access technologies and may be adapted to implement embodiments of the present disclosure described herein. Figure 1 Certain aspects of the various components and their corresponding operating modes are well known and defined in relevant standards managed by the 3GPP (RTM) organization, and described in many books on the subject, such as Holma H. ​​and Toskala A[1]. It should be understood that the operational aspects of telecommunications networks not specifically described herein (e.g., regarding specific communication protocols and physical channels used for communication between different components) can be implemented according to any known technology, such as modifications and additions to relevant standards and known proposals for relevant standards.

[0029] Network 6 includes multiple base stations 1 connected to core network 2. Each base station provides coverage area 3 (i.e., cell), within which data can communicate with communication device 4.

[0030] Although each base station 1 is Figure 1 While shown as a single entity, those skilled in the art will understand that some functions of a base station can be performed by different, interconnected components, such as antennas (or antenna heads), remote radio heads, amplifiers, etc. In general, one or more base stations can form a radio access network.

[0031] Data is transmitted from base station 1 to communication device 4 within its corresponding coverage area 3 via a radio downlink. Data is transmitted from communication device 4 to base station 1 via a radio uplink. Core network 2 routes data to and from communication device 4 via the corresponding base station 1, and provides functions such as authentication, mobility management, and billing. Terminal devices may also be referred to as mobile stations, user equipment (UE), user terminals, mobile radios, communication devices, etc.

[0032] The services provided by core network 2 may include connections to the Internet or external telephone services. Core network 2 may further track the location of communication device 4 so that it can effectively contact (i.e., page) communication device 4 to send downlink data to communication device 4.

[0033] A base station is an example of network infrastructure equipment and may also be referred to as a transceiver station, nodeB, e-nodeB, eNB, g-nodeB, gNB, etc. In this regard, different terms are generally associated with different generations of wireless telecommunication systems to provide elements with broadly comparable functionality. However, certain embodiments of this disclosure can be implemented equivalently in different generations of wireless telecommunication systems, and for simplicity, specific terms may be used regardless of the underlying network architecture. That is, the use of specific terms associated with particular example implementations is not intended to imply that these implementations are limited to the specific generation of networks most relevant to that specific term.

[0034] New wireless access technology (5G) wireless communication system

[0035] 3GPP has completed the basic version of 5G in Rel-15, which is called the New Radio Access Technology (NR). In addition, it has been improved in Rel-16, adding new features such as the two-step RACH process[2], Industrial Internet of Things (IIoT)[3] and NR-based unlicensed spectrum access (NR-U)[4].

[0036] Further improvements have been agreed upon for Rel-17, such as small data transmissions when the UE is in the RRC_INACTIVE state. Referring to [5], some specific examples of small data transmissions and infrequent data traffic might include the following use cases:

[0037] • Smartphone applications:

[0038] Traffic to instant messaging services;

[0039] Traffic from IM / email clients and other applications' heartbeat / keep-alive activity; and

[0040] Push notifications from various applications;

[0041] Non-smartphone applications:

[0042] Traffic from wearable devices (e.g., periodic location information);

[0043] ο Sensors (e.g., industrial wireless sensor networks that periodically or in an event-triggered manner transmit temperature or pressure readings); and

[0044] Smart meters and smart meter networks periodically send meter readings.

[0045] Furthermore, based on the above-mentioned [5], for RACH-based schemes (i.e., 2-step and 4-step RACH, which will be discussed in more detail below), uplink small data transmission has been enabled for UEs in the RRC inactive state. This includes the general procedure for enabling user plane data transmission of small data packets in the inactive state (using MsgA of the 2-step RACH procedure or Msg3 of the 4-step RACH procedure), and enabling a flexible payload size larger than the Rel-16 Common Control Channel (CCCH) message size, currently likely used for UEs in the RRC_INACTIVE state, to transmit small data in MsgA or Msg3 to support user plane data transmission in the uplink.

[0046] NR radio access systems employ Orthogonal Frequency Division Multiple Access (OFDMA), where different users are simultaneously scheduled across different subsets of subcarriers. However, OFDMA requires tight synchronization in uplink transmissions to achieve orthogonality of transmissions from different users. Essentially, uplink transmissions from all users must arrive at the gNB receiver simultaneously (i.e., they must be synchronized). Therefore, due to different RF propagation delays, UEs farther from the gNB must transmit earlier than those closer to the gNB. In NR, timing advance commands are applied to control the uplink transmission timing of individual UEs, primarily for Physical Uplink Shared Channels (PUSCHs), Physical Uplink Control Channels (PUCCHs), and Sound Reference Signals (SRS). Timing advance typically includes twice the one-way propagation delay between the UE and the gNB, thus representing both downlink and uplink delays.

[0047] Figure 2 The image shows an exemplary configuration of a wireless communication network that uses some of the terminology proposed and used for NR and 5G. Figure 2In this configuration, multiple Transmit and Receive Points (TRPs) 10 are connected to Distribution Control Units (DUs) 41, 42 via connection interfaces represented by lines 16. Each of the TRPs 10 is arranged to transmit and receive signals via a wireless access interface within the available radio frequency bandwidth of the wireless communication network. Thus, within the range for performing radio communication via the wireless access interface, each of the TRPs 10 forms a wireless communication network unit represented by circles 12. In this way, a wireless communication device 14 within the radio communication range provided by unit 12 can transmit signals to and receive signals from the TRPs 10 via the wireless access interface. Each of the distribution units 41, 42 is connected to a central unit (CU) 40 (which may be referred to as a control node) via interface 46. The central unit 40 is then connected to a core network 20, which may contain all other functions required for transmitting data for communicating with wireless communication devices, and the core network 20 may be connected to other networks 30.

[0048] Figure 2 The components of the wireless access network shown can be configured with respect to... Figure 1 The example describes a corresponding element in an LTE network that operates in a similar manner. It will be understood that... Figure 2 The operational aspects of the telecommunications network represented, as well as other operational aspects of networks discussed herein according to embodiments of this disclosure, are not specifically described (e.g., regarding specific communication protocols and physical channels for communication between different elements) and can be implemented according to any known technology, such as currently used methods for implementing such operational aspects of wireless telecommunications systems, for example, according to relevant standards.

[0049] Figure 2 The TRP 10 may partially have functions corresponding to a base station or eNodeB in an LTE network. Similarly, the communication device 14 may have functions corresponding to a UE device 4 known for operation in an LTE network. Therefore, it will be understood that the operational aspects of the new RAT network (e.g., regarding the specific communication protocols and physical channels used for communication between different components) may differ from those known from LTE or other known mobile telecommunications standards. However, it will also be understood that each of the core network components, base stations, and communication devices of the new RAT network will be functionally similar to the core network components, base stations, and communication devices of an LTE wireless communication network, respectively.

[0050] In terms of broad top-level functions, Figure 2 The core network 20 shown, connected to the new RAT telecommunications system, can be broadly considered to correspond to... Figure 1 The core network 2 shown, and the central unit and its associated distributed units / TRP 10 can be broadly considered to provide corresponding... Figure 1The function of base station 1. The term network infrastructure equipment / access node can be used for these elements that comprise wireless telecommunications systems and more conventional base station type elements. Depending on the application at hand, the responsibility for scheduling transmissions on the radio interface between the corresponding distributed unit and communication device may lie with the control node / central unit and / or distributed unit / TRP. Figure 2 In this context, the communication device 14 is represented within the coverage area of ​​the first communication unit 12. The communication device 14 can therefore exchange signaling with the first central unit 40 in the first communication unit via a distributed unit 10 associated with the first communication unit 12.

[0051] It should also be understood that Figure 2 This is merely one example of a proposed architecture for a new RAT-based telecommunications system, in which methods based on the principles described herein can be employed, and the functionality disclosed herein can also be applied to wireless telecommunications systems with different architectures.

[0052] Therefore, certain embodiments of this disclosure discussed herein can be adapted to various different architectures (e.g., Figure 1 and Figure 2 The example architecture shown is implemented in a wireless telecommunications system / network. Therefore, it should be understood that a particular wireless telecommunications architecture in any given implementation is not of primary significance to the principles described herein. In this regard, certain embodiments of this disclosure can be generally described in the context of communication between network infrastructure devices / access nodes and communication devices, wherein the specific properties of the network infrastructure devices / access nodes and communication devices will depend on the network infrastructure to be implemented. For example, in some cases, the network infrastructure devices / access nodes may include base stations, such as… Figure 1 The illustrated LTE-type base station 1 is suitable for providing functionality according to the principles described herein, and in other examples, network infrastructure equipment may include... Figure 2 The control unit / control node 40 and / or TRP 10 of the type shown are adapted to provide functionality in accordance with the principles described herein.

[0053] Figure 3 Provided Figure 2 A more detailed diagram of some of the network components is shown below. Figure 3 In, such as Figure 2 The TRP 10 shown includes, in simplified representation, a wireless transmitter 30, a wireless receiver 32, and a controller or control processor 34, which is operable to control the transmitter 30 and the wireless receiver 32 to transmit and receive radio signals to or from one or more UEs 14 within the unit 12 formed by the TRP 10. Figure 3As shown, example UE 14 is shown as including a respective transmitter 49, receiver 48 and controller 44, controller 44 being configured to control transmitter 49 and receiver 48 to transmit signals representing uplink data to the wireless communication network via the radio access interface formed by TRP 10, and to receive downlink data as signals transmitted by transmitter 30 and received by receiver 48 in accordance with normal operation.

[0054] Transmitters 30, 49 and receivers 32, 48 (and other transmitters, receivers, and transceivers described in the examples and embodiments of this disclosure) may include radio frequency filters and amplifiers, as well as signal processing components and means for transmitting and receiving radio signals according to, for example, 5G / NR standards. Controllers 34, 44, 48 (and other controllers described in the examples and embodiments of this disclosure) may be, for example, microprocessors, CPUs, or dedicated chipsets, configured to execute instructions stored on a computer-readable medium (e.g., non-volatile memory). The processing steps described herein may be executed by, for example, a microprocessor in conjunction with random access memory, operating according to instructions stored on a computer-readable medium.

[0055] like Figure 3 As shown, TRP 10 also includes a network interface 50 connected to DU 42 via physical interface 16. Therefore, network interface 50 provides a communication link for data and signaling services from TRP 10 to core network 20 via DU 42 and CU 40.

[0056] The interface 46 between DU 42 and CU 40 is referred to as the F1 interface, which can be a physical interface or a logical interface. The F1 interface 46 between the CU and DU operates according to specifications 3GPP TS 38.470 and 3GPP TS 38.473 and can be formed by fiber optic or other wired high-bandwidth connections. In one example, the connection 16 from TRP 10 to DU 42 is via fiber optic cable. The connection between TRP 10 and the core network 20 can generally be referred to as the backhaul, which includes the interface 16 from the network interface 50 of TRP 10 to DU 42 and the F1 interface 46 from DU 42 to CU 40.

[0057] RACH process in LTE and NR

[0058] In wireless telecommunication networks such as LTE and NR, different Radio Resource Control (RRC) modes exist for terminal devices. For example, RRC Idle Mode (RRC IDFE) and RRC Connected Mode (RRCCONNECTED) are typically supported. A terminal device in Idle Mode can transition to Connected Mode by performing a random access procedure, for example, because it needs to transmit uplink data or respond to a paging request. The random access procedure involves the terminal device transmitting a preamble on the Physical Random Access Channel; therefore, this procedure is often referred to as the RACH or PRACH procedure / process.

[0059] In addition to the terminal device deciding to initiate a random access procedure to connect to the network, the network, such as a base station, can also instruct the terminal device in connected mode to initiate a random access procedure by transmitting an instruction to the terminal device to do so. Such an instruction is sometimes called a PDCCH command (Physical Downlink Control Channel Command); see, for example, section 5.3.3.1.3 in ETSI TS36.213 v13.0.0(2016-01) / 3 GPP TS 36.212 version 13.0.0 Release 13[6].

[0060] There are various scenarios in which the network may trigger the RACH procedure (PDCCH command).

[0061] For example:

[0062] • The terminal device can receive PDCCH commands for transmission on PRACH as part of the handover process;

[0063] • A terminal device that is connected to the base station via RRC but has not exchanged data with the base station for a relatively long time can receive a PDCCH command to enable the terminal device to transmit a PRACH preamble, thereby enabling it to resynchronize with the network and allowing the base station to correct the timing of the terminal device.

[0064] • The terminal device can receive PDCCH commands so that it can establish different RRC configurations in the subsequent RACH process. For example, this can be applied to a narrowband IoT terminal device that is prevented from RRC reconfiguration in connected mode. Sending the terminal device to idle mode via PDCCH commands allows the terminal device to be configured in the subsequent PRACH process, for example, configuring the terminal device to a different coverage enhancement level (e.g., more or less repetition).

[0065] For convenience, this document uses the term PDCCH command to refer to signaling transmitted by the base station to instruct a terminal device to initiate a PRACH procedure, regardless of the reason. However, it should be understood that in some cases, such instructions may be transmitted on other channels / at higher layers. For example, regarding intra-system handover procedures, the PDCCH command referred to herein may be an RRC connection reconfiguration instruction transmitted on the downlink shared channel / PDSCH.

[0066] When a PDCCH command is transmitted to a terminal device, the terminal device is assigned a PRACH preamble signature sequence for use in subsequent PRACH procedures. This differs from a PRACH procedure triggered by the terminal device itself, where the terminal device selects a preamble from a predefined set, potentially leading to accidental selection of the same preamble as another terminal device simultaneously performing a PRACH procedure, thus causing potential contention. Therefore, for a PRACH procedure initiated by a PDCCH command, there is no contention with other terminal devices simultaneously performing a PRACH procedure, because the PRACH preamble used by the terminal device executing the PDCCH command is scheduled by the network / base station.

[0067] Figure 4 A typical RACH procedure used in an LTE system is shown, for example, via a reference. Figure 1 As described, it can also be applied to NR wireless communication systems, for example, through reference Figure 2As described. UE101, which may be in an inactive or idle mode, may have some data that it needs to transmit to the network. For this purpose, it sends a random access preamble 120 to gNodeB 102. This random access preamble 120 indicates the identifier of UE101 to gNodeB 102, allowing gNodeB 102 to address UE101 in the later stages of the RACH procedure. Assuming that gNodeB 102 successfully receives the random access preamble 120 (and if not, UE101 will simply retransmit it at higher power), gNodeB 102 will transmit a random access response 122 message to UE101 based on the identifier indicated in the received random access preamble 120. The random access response 122 message carries another identifier assigned by gNodeB 102 to identify UE101, a timing advance value (allowing UE101 to change its timing to compensate for round-trip delay caused by its distance from gNodeB 102), and authorizes uplink resources for UE101 to transmit data. Upon receiving the random access response message 122, UE 101 uses the identifier assigned to it in the random access response message 122 to transmit a scheduled transmission of data 124 to gNodeB 102. Assuming there are no conflicts with other UEs (a conflict might occur if another UE and UE 101 simultaneously send the same random access preamble 120 to gNodeB 102 using the same frequency resources), gNodeB 102 successfully receives the scheduled transmission of data 124. gNodeB 102 will respond to the scheduled transmission 124 with a contention resolution message 126.

[0068] Recent discussions have covered how UE states (e.g., RRC idle, RRC connected, etc.) should transition to the NR system. For example, it has been agreed that a new "inactive" state should be introduced, in which the UE should be able to initiate data transmission with low latency (as required by RAN requirements). The possibility of the UE transmitting data in an inactive state without transitioning to a connected state has also been agreed upon. In addition to shifting the baseline to a connected state before data transmission, the following two methods have been identified:

[0069] • Data can be transmitted along with the initial RRC message requesting a transition to the connected state, or

[0070] Data can be transmitted in a new state.

[0071] Discussions concerning uplink data transmission in inactive states have sought solutions for transmitting uplink data in inactive states without using RRC signaling and without the UE initiating a transition to the connected state. [7] A first potential solution is discussed. This solution is in Figure 5As shown, it is reproduced together with the accompanying text from [7]. Figure 5 As shown, UE 101 can transmit uplink data 132 to network 104, which is in an RRC inactive state. Here, network 104 knows at least which cell received the transmission 132, and potentially even which TRP it is transmitted through. For a certain period of time after receiving the uplink data packet, network 104 can assume that UE 101 is still in the same location so that, for example, in the next paging response 134, any RLC acknowledgment or application response can be scheduled to be transmitted to UE 101 in the same area where UE 101 is located. Alternatively, UE 101 can be paged in a wider area. After receiving the downlink response 134, UE 101 can transmit an acknowledgment 136 to network 104 to indicate that it was successfully received.

[0072] A second potential solution was discussed in [8]. This solution is... Figure 6 As shown in the figure, it is reproduced together with the accompanying text from [8]. Figure 6 The mechanism described is used for small data transmission and is based on LTE's suspend-resume mechanism. The main difference lies in the fact that user plane data and message 3 ( Figure 6 The RRC connection restoration request (144) and the optional RRC suspension signal issued in message 4 are transmitted simultaneously. Figure 6 As shown, under the initial assumption of the random access scheme in LTE, when UE 101 receives uplink data to be transmitted to gNodeB 102 of the mobile communication network, UE 101 first transmits a random access (RA) preamble 140. Here, a special preamble set (preamble partition) can be used, as in LTE, to indicate small data transmission (meaning that UE 101 desires a larger grant and may wish to remain inactive).

[0073] The network (via gNodeB 102) responds with a Random Access Response (RAR) message 142 containing a timed advance and authorization. The authorization in message 3 should be large enough to accommodate the RRC request and a small amount of data. The allowed data size can be specified and linked to a preamble, for example, preamble X requests authorization to allow Y bytes of data. Depending on available resources, gNodeB 102 can provide authorization for message 3 that only contains a recovery request; in this case, additional authorization can be provided after message 3 is received.

[0074] At this point, UE 101 will prepare RRC connection restoration request 144 and perform the following actions:

[0075] • Re-establish the Packet Data Convergence Protocol (PDCP) for SRBs and all established DRBs;

[0076] • Re-establish RLC for Radio Signaling Bearers (SRBs) and all established Data Radio Bearers (DRBs). During this step, PDCP should reset the Sequence Number (SN) and Superframe Number (HFN).

[0077] • Restore SRB and all pending DRBs;

[0078] • Based on the next-hop link counter (NCC) provided before UE 101 is sent to the “inactive” state, derive possible new security keys (e.g., eNB key or KeNB);

[0079] • Generate encryption and integrity protection keys, and configure the PDCP layer using the previously configured security algorithm;

[0080] @Generate RRC connection recovery request message 144;

[0081] • Add indications of potential remaining data, such as buffer status reports (BSRs);

[0082] • Add an indication that UE 101 wants to remain inactive (if this is not indicated by a preamble);

[0083] • Apply the default physical channel and media access control (MAC) configuration; and

[0084] • Submit RRC connection recovery request 144 and data 146 to the lower layer for transmission.

[0085] Following these steps, message 3 is transmitted at the lower layer. This may also contain user plane data 146 multiplexed by the MAC layer, as is the case with existing LTE specifications, since a security context has been activated to encrypt the user plane. Signaling (using SRB) and data (using DRB) will be multiplexed by the MAC layer (meaning data is not sent over the SRB).

[0086] The network (via gNodeB 102) receives message 3 and uses the context identifier to retrieve the RRC context of UE 101, and re-establishes PDCP and RLC for SRB and DRB. The RRC context contains the encryption key, and the user plane data is decrypted (and will be mapped to the re-established DRB or the always-available contention-based channel).

[0087] Upon successful reception of message 3 and user plane data, the network (via gNodeB 102) responds with a new RRC response message 148, which can be "RRC suspended," "RRC resumed," or "RRC rejected." This transmission resolves contention and serves as an acknowledgment of message 3. In addition to RRC signaling, the network can acknowledge any user data in the same transmission (RLC acknowledgment). The multiplexing of RRC signaling and user plane acknowledgment is handled by the MAC layer. If UE 101 loses contention, a new attempt is required.

[0088] • If the network decides to restore UE 101, the message will be similar to RRC restoration and may include additional RRC parameters.

[0089] If the network decides to suspend UE 101 immediately, this message will be similar to an RRC suspension. The message may be delayed to allow downlink acknowledgments to be transmitted.

[0090] • In the event that the network transmission refuses to resume, UE 101 will initiate a new scheduling request (SR) after some potential backoff time, just like in LTE.

[0091] Strictly speaking, this process will transmit user plane data without UE 101 fully entering an RRC connection, which previously occurred when UE 101 received an RRC response indicating resumption (message 4). On the other hand, it uses the RRC context to enable encryption, etc., even if the network's decision is to keep UE 101 in RRC inactive by immediately suspending UE 101 again.

[0092] Figure 7 and Figure 8 Examples of simplified two-step RACH procedures are shown, where a small amount of data can be transmitted from UE101 to gNodeB or eNodeB 102. In the two-step RACH process, data is transmitted simultaneously with the RACH preamble. Figure 8 Message 1 (in the context of Message 162) allows UE 101 to transmit its data without waiting for a response from the network that granted it uplink authorization. However, a drawback is that the amount of data that can be transmitted in Message 1 is limited. After receiving Message 1 at eNodeB 102, eNodeB 101 transmits a random access response (in the context of Message 162) to UE 101. Figure 8 Message 162 in the message includes an acknowledgment of the data received in message 1. Figure 7 The message is illustrated in more detail, where message 1 (also referred to herein as msgA) transmits a random access preamble 150, an RRC connection restoration request 152, and / or a small amount of data 154 within the same Transmission Time Interval (TTI). Message msgA is essentially a combination of messages 1 and 3 in a 4-step RACH process, such as... Figure 6 As shown. Similarly, for message 2 (also referred to here as msgB), during the same TTI, eNodeB 102 transmits a random access response 156 and an RRC response 158 (including an acknowledgment and an RRC hang-up command) with a time advance to UE 101. This message msgB is essentially a combination of messages 2 and 4 in the 4-step RACH process, for example as... Figure 6 As shown. Further details about the two-step and four-step RACH process can be found in 3GPP Technical Report 38.889[9].

[0093] Handover process in LTE

[0094] Figure 9 This is a ladder diagram illustrating the signaling exchange between an RRC-connected mode terminal device (“UE”), a source network access node (“source eNB”), a target network access node (“target eNB”), a mobility management entity (“MME”), and a serving gateway (“serving gateway”) for a traditional MME / serving gateway LTE handover process in a traditional LTE-based wireless telecommunications network. This process is well established and understood by those skilled in the art and is described in relevant standards; therefore, for the sake of brevity, it will not be described in detail here. Although described for LTE... Figure 9 The process shown is analogous to the basic handover process for NR, but those skilled in the art will understand that it is different. Figure 9 The two are very similar, with the main difference being the entities involved.

[0095] In references such as the above Figure 1 In the known LTE-based wireless telecommunications systems described, terminal devices in RRC connection mode / state are typically configured with event-based reporting triggering criteria. Therefore, the terminal device is configured by the network access node it is currently connected to (the source network access node) to measure the radio channel conditions associated with the radio path between the terminal device, the source network access node, and adjacent access nodes (potential target network access nodes for handover). This configuration process... Figure 9 The step is schematically represented by the label "1. Measurement Control". In LTE, radio channel condition measurements are based on cell-specific reference signals transmitted by network access nodes. CRS transmissions from a given network access node provide an indication of the network access node's identity (based on a mapping between resources used for CRS transmission and the network access node's Physical Cell Identifier (PCI)). The terminal device is configured to measure characteristics of the CRS received from different network access nodes, such as Reference Signal Received Power (RSRP) or Reference Signal Received Quality (RSRQ), to establish a characteristic indication of channel quality for different network access nodes. Handover decisions are made based on these channel quality measurements.

[0096] In summary, the terminal device is configured to continuously determine whether the radio channel conditions associated with any neighboring network access node (i.e., a network access node to which the terminal device is not currently connected) meet predefined criteria for triggering a measurement report. If the criteria are met for a given neighboring network access node, it may be appropriate for the terminal device to notify its connected network access node (source network access node) of a handover by sending a measurement report indicating that the predefined criteria have been met for the relevant network access node. The step of transmitting the measurement report is described in... Figure 9 The step is illustrated by the label "2. Measurement Report". Based on the measurement report, the source network access node makes a decision on whether to switch the terminal device to the relevant neighboring network access node (in... Figure 9 (This is illustrated by the step marker "3.HO Decision"). If the source network access node does determine that the terminal device should be handed over, processing will continue, as follows: Figure 9 As shown in the image.

[0097] Pre-adjustment of timing during initial access

[0098] During the initial access transition from RRC idle / RRC inactivity to RRC connection, the UE follows an initial access procedure using either a 4-step or 2-step RACH, as referenced above. Figures 4 to 8 As described above. During initial access, the UE can perform timing advance (TA) adjustments.

[0099] As described above, for a 4-step RACH procedure, the gNB estimates the propagation delay from the random access preamble sent by the UE in message 1 and converts this propagation delay into a TA value command, which is included in the RAR sent to the UE in message 2. The UE's future uplink transmissions (including uplink transmissions in message 3) will be adjusted based on the TA value command. Similarly, for a 2-step RACH procedure, the gNB will receive data from the UE in the random access preamble and PUSCH in msgA, and will estimate the propagation delay from the received random access preamble before converting it into a TA value command. Then, in msgB, the gNB will include the TA value command for the UE, which the UE will use to adjust its future uplink transmissions.

[0100] Therefore, as described above, for the 4-step and 2-step initial access procedures, the downlink response contains a TA value in the range of 0, 1, 2, 3, ..., 3846. Then, upon receiving this value, the UE converts it into an absolute time value in seconds, as follows:

[0101] T TA =T A ·16·64·T c / 2μ

[0102] Where μ is the subcarrier spacing index as shown in Table 1 below, and Tc is the basic timing unit defined in

[10] .

[0103] Table 1: Subcarrier Spacing Index μ

[0104]

[0105]

[0106] After a UE has established a connection with the cell, timing advance is maintained when propagation delay changes due to UE mobility within the same cell. For example, the gNB periodically measures the propagation delay from the UE based on received UL SRS, PUSCH, and PUCCH, and then includes a TA update (called the timing advance MAC control element) for the UE's downlink PDSCH transmission. Assuming the UE is in RRC connected mode but not performing UL synchronization, the gNB can also command the UE (called the PDCCH command) to send a preamble for UL synchronization purposes. In response, the gNB sends an update to the TA value based on the UL preamble measurement. Finally, the UE adjusts its future uplink transmissions based on the new TA value.

[0107] If the UE is moving to another cell (i.e., the target cell) while still on an RRC connection, then based on the above regarding... Figure 9 The described handover process will instruct the UE to send a preamble to the target cell (see...). Figure 9 Step “9. Synchronization” enables the target cell to estimate the propagation delay. After the target cell has received the preamble and determined the TA value, the target cell sends a TA value command, and then the UE adjusts its future uplink transmission based on the new cell's TA value.

[0108] To maintain timing advance in RRC connection mode, the UE receives a relative TA value, which may have one of 64 values ​​ranging from 0 to 63. The UE then converts the relative TA into an absolute time value in seconds, as follows:

[0109] T TA_DCW =T TA_old +(T A -31)·16·64·T c / 2 μ

[0110] During handover, for UL synchronization as described above, the UE transmits a PRACH according to the 4-step or 2-step RACH procedure as described above, and the gNB sends a response to the PRACH in the downlink. However, using this RACH procedure solely for the purpose of achieving synchronization during handover introduces delays and / or wastes some resources within the target cell when the UE transmits actual data to the new cell. Embodiments of this disclosure attempt to provide a solution to this problem.

[0111] RACH-free handover without considering propagation delay

[0112] Figure 10 A partial schematic representation and partial message flow diagram of communication between a communication device or UE 1001 and a wireless communication network according to embodiments of the present technology are provided. The wireless communication network may include multiple infrastructure devices 1002, 1004, each infrastructure device providing a cell with a coverage area. The communication device 1001 may be located within one of these coverage areas and may move between coverage areas. The communication device 1001 includes a transceiver (or transceiver circuitry) 1001.t configured to transmit signals to or receive signals from the wireless communication network (e.g., via a wireless access interface provided by the wireless communication network to at least one infrastructure device 1002); and a controller (or controller circuitry) 1001.t configured to control the transceiver circuitry 1001.t to transmit or receive signals. Figure 10 As can be seen, infrastructure devices 1002 and 1004 may further include transceivers (or transceiver circuits) 1002.t and 1004.t, which can be configured to transmit signals to or receive signals from communication device 1001 via a wireless access interface, and controllers (or controller circuits) 1002.c and 1004.c, which can be configured to control the transmission or reception of signals by transceiver circuits 1002.t and 1004.t. For example, each of controllers 1001.c and 1002.c may be a microprocessor, CPU, or dedicated chipset, etc.

[0113] The controller circuit 1001.c of the communication device 1001 is configured to combine with the transceiver circuit 1001.t of the communication device 1001 to: determine whether the communication device 1001 will execute a command from the first cell of the wireless communication network (in... Figure 10 In the example, the second cell of the wireless communication network (controlled by infrastructure device 1002) connects to the wireless communication network. Figure 10In the example, the handover process 1012 (controlled by infrastructure device 1004) includes: measuring the difference between the start of the first radio frame 1016 received from the first cell and the start of the second radio frame 1018 received from the second cell; and during the handover process 1012, determining, based on the measured difference 1014, at least one of the propagation delay value of the second cell and the timing advance value of the second cell, wherein the propagation delay of the second cell defines the time taken for a signal to propagate unidirectionally between the communication device 1001 and the second cell, and the timing advance of the second cell defines the time taken for a signal to propagate round trip between the communication device 1001 and the second cell.

[0114] Essentially, embodiments of this technology propose that the UE or serving cell apply the difference between the downlink radio frames received from the serving cell and the target cell, along with the current timing advance value of the serving cell (i.e., derived from the bidirectional propagation delay value), to estimate the UL propagation delay (or timing advance) of the target cell. Therefore, by applying embodiments of this technology, no PRACH transmission is required in the uplink or DL ​​transmission response for UL synchronization purposes. That is, embodiments of this technology achieve RACH-free handover. In known systems and technologies, RACH-free handover can only be used in small cells where propagation delay is insignificant, and where the UE is known to be substantially synchronized with the target cell and the serving cell. However, embodiments of this technology can achieve RACH-free handover even in scenarios with significant propagation delay.

[0115] As described above, embodiments of this technology can provide a method for a UE or serving gNB to determine the UL propagation delay or timing advance of a target cell.

[0116] In the arrangement of embodiments of this technology, where the UE determines the UL propagation delay or timing advance of the target cell, the UE first measures the frame timing difference between the NR serving cell and the NR target cell. Section 5.1.14 of

[11] specifies this as follows:

[0117] Frame boundary offset = [(T FrameBoundaryPCell -T FrameBoundryTRGCell ) / 5], where T FrameBoundaryPCell It is the time when the UE starts receiving radio frames from the PCell, and T FrameBoundryTRGCel l is the start time of the radio frame received by the UE from the target cell that is closest in time to the radio frame received from the PCell. (T) FrameBoundaryPCell -T FrameBoundryTRGCell The unit for () is TS.

[0118] Figure 11The text above, reproduced from

[11] , is shown in the image, depicting UE 1001 undergoing a handover between serving cell gNB A 1002 and target cell gNB B 1004. Similarly, with... Figure 10 Similarly, in the example, UE 1001 measures the timing difference between the start of radio frame 1016 received from gNB A 1002 (denoted as T0) and the start of radio frame 1018 received from gNB B 1004 (denoted as T1), and this is denoted as ΔT, which is expressed in seconds, and can be calculated as follows:

[0119] Δt=(T1-T0)·64·T c

[0120] Where Tc is derived from Ts / Tc = 64, as shown in

[10] . ΔT can be a positive or negative value. It should be noted that, according to embodiments of this technology, the scaling factor 5 in the above text copied from

[10] is not considered. In addition, the UE may be required to read the MIB (Master Information Block) of the target cell during the measurement frame timing difference in order to determine, for example, the radio frame boundary of the target cell.

[0121] After the UE has detected the frame timing difference between the NR serving cells, the UE can then calculate the absolute timing advance or propagation delay value of the target cell, as described below. This can be aided by the UE receiving the TA value of the first cell from the serving cell. In other words, the communication device can be configured to receive an indication of the timing advance value of the first cell, which defines the time taken for the signal to travel round trip between the communication device and the first cell.

[0122] If the frame timing between adjacent cells is synchronized at the transmission point (i.e., at the GNB), then in some arrangements of embodiments of this technology, the UE can calculate the absolute timing advance value (T) of the target cell as follows: TA_target cell ) or one-way propagation delay (T PD_target cell ):

[0123] T TA_target cell =T TA_serving cell -(2*Δt), or

[0124] T PD_target cell =(T TA_serving cell / 2)-Δt

[0125] In other words, the communication device is configured to determine the propagation delay value of the second cell by subtracting the measured difference from a value equal to half the timing advance value of the first cell, and / or by subtracting a value equal to twice the measured difference from the timing advance value of the first cell.

[0126] If the frame timing between adjacent cells is out of sync at the transmission point (i.e., at the GNB), the earlier UE measurement of ΔT already includes a fixed misalignment value between the two cells. If the serving gNB already knows its misalignment value (ΔK) with the target cell, the serving gNB can send the misalignment value (ΔK) to the UE. Based on this, in some arrangements of embodiments of this technology, the UE can then calculate the absolute timing advance value or one-way propagation delay of the target cell as follows:

[0127] T TA_target cell =T TA_serving cell -[2*(Δt-Δk)], or

[0128] T PD_target cell =(T TA_serving cell / 2)-(Δt-Δk)

[0129] In other words, the communication device is configured to receive an indication of an inaccuracy value from a first cell, which defines the amount of time the first cell is out of sync with a second cell, and to determine the propagation delay value of the second cell by subtracting the inaccuracy value from the difference in measurements, and then by subtracting the result of subtracting the inaccuracy value from the difference in measurements from a value equal to half the timing advance value of the first cell, and / or by subtracting the inaccuracy value from the difference in measurements, and then by subtracting twice the result of subtracting the inaccuracy value from the timing advance value of the first cell.

[0130] In the arrangement of embodiments of this technology, where the serving gNB determines the UL propagation delay or timing advance of the target cell, the UE again first measures the frame timing difference between the NR serving cell and the NR target cell. However, instead of subsequently calculating the UL propagation delay itself, the UE sends a measurement report (ΔT) to the serving cell to calculate the UL timing advance (or one-way propagation delay), as follows:

[0131] T TA_target cell =T TA_serving cell -(2*Δt), or

[0132] T PD target cell =(T TA serving cell / 2)-Δt

[0133] After performing the above calculations, the serving cell can then send the target cell's UL timing advance value to the UE during handover.

[0134] In other words, the communication device is configured to send an indication of a measured difference to a first cell; and in response to the sent indication of the measured difference, to determine at least one of the propagation delay value and the timing advance value of the second cell by receiving at least one of the propagation delay value and the timing advance value of the second cell from one or more messages of the handover process. Here, the infrastructure equipment (i.e., controlling the first cell) is configured to determine that the communication device will perform a handover process from the first cell to the second cell of the wireless communication network; to receive from the communication device an indication of a measured difference between the start of a first radio frame received by the communication device from the first cell and the start of a second radio frame received by the communication device from the second cell; during the handover process, to determine at least one of the propagation delay value and the timing advance value of the second cell based on the measured difference, wherein the propagation delay of the second cell defines the time taken for a signal to propagate unidirectionally between the communication device and the second cell, and the timing advance of the second cell defines the time taken for a signal to propagate round trip between the communication device and the second cell; and to send an indication of at least one of the propagation delay value and the timing advance value of the second cell to the communication device in one or more messages of the handover process.

[0135] Similar to the arrangement of embodiments of the present technology described above, wherein the UE determines the UL propagation delay of the target cell, and when the serving gNB performs the calculation and makes this determination, the serving gNB may do so solely based on the difference between the received measurement and the UE, or additionally based on the misalignment value between the serving cell and the target cell. In other words, the infrastructure equipment (i.e., controlling the first cell) is configured to determine a timing advance value for the first cell, which defines the time taken for a signal to propagate round trip between the communication device and the first cell; and to determine the propagation delay value of the second cell by subtracting the measured difference from a value equal to half the timing advance value of the first cell, and / or by subtracting a value equal to twice the measured difference from the timing advance value of the second cell. The infrastructure equipment can then be configured to determine an aberration value between the first cell and the second cell, the aberration value defining the amount of time the first cell and the second cell are out of sync, and to determine the propagation delay value of the second cell by subtracting the aberration value from the measured difference, and then by subtracting the result from the difference in measurements from the aberration value from half the timing advance value of the first cell, and / or by subtracting the aberration value from the measured difference, and then by subtracting twice the result from the timing advance value of the first cell from the result of the difference in measurements from the aberration value.

[0136] One problem with the above-described arrangement of the serving cell determining the target cell's TA in this technical embodiment is that the TA may be outdated when the UE is about to request a UL transmission. To mitigate this situation, or if the UE performs the determination of the target cell's TA, in some arrangements of this technical embodiment, assuming that the TA value used by the UE may be less accurate (i.e., 'a' is a rough estimate or outdated), the target gNB sends an update of the TA in the DL transmission to the UE after receiving the handover completion message (in the PUSCH). In other words, the infrastructure equipment is configured to receive an update of at least one of the propagation delay value of the second cell and the timing advance value of the second cell after the handover process has been completed.

[0137] In another arrangement of embodiments of this technology, the UE may report its timing advance value for the transmission (e.g., within a "handover completion message") to the target cell so that the target cell can record and store the value, and provide an updated value to the UE if the UE's value is incorrect or differs from the actual value by more than a threshold amount. In other words, the communication device is configured to send an indication to the second cell of at least one of the propagation delay value of the second cell and the timing advance value of the second cell.

[0138] In other arrangements of embodiments of this technology, the UE can be configured to send a UL reference signal (RS) to the target cell before completing the handover using pre-allocated resources, and the target cell can then notify the serving cell of the UE's propagation delay (or TA). The serving cell can then include the TA in the handover message so that the UE can apply the TA used for UL transmission to the target cell. In other words, the communication device is configured to determine that it will perform a handover process from a first cell to a second cell in a wireless communication network; transmit an uplink reference signal to the second cell in communication resources pre-allocated to the communication device in which it may transmit signals (e.g., the UE may optionally transmit uplink data in these pre-allocated uplink resources, or the UE may be allocated pre-allocated uplink resources by the source cell based on RS signaling configuration between the source cell and the target cell – in which RS is transmitted); and in response to the transmitted uplink reference signal, receive from the first cell at least one of a propagation delay value and a timing advance value of the second cell from one or more messages of the handover process, the propagation delay of the second cell defining the time taken for a signal to propagate unidirectionally between the communication device and the second cell, and the timing advance of the second cell defining the time taken for a signal to propagate round-trip between the communication device and the second cell.

[0139] Therefore, according to the above arrangement of embodiments of the present technology, during the handover of the UE from the source gNB to the target gNB, the UE or the source gNB can determine the timing advance or propagation delay of the target gNB. Here, propagation delay is defined as the time it takes for a signal to propagate from the UE to the gNB, and timing advance is defined as the round-trip time of the signal between the UE and the gNB. However, those skilled in the art will understand that any other definition of "propagation delay" or "timing advance," or any other type of timing information consistent between the target and source gNBs, is within the scope of this disclosure and consistent with the inventive contribution of embodiments of the present technology, provided that the timing values ​​of the source and target gNBs are calculated in the same manner as described herein (i.e., subtracting the difference and / or inaccuracy value of the measurements as described above).

[0140] Flowchart representation

[0141] Figure 12 A flowchart illustrating a method for operating a communication device in a wireless communication network is shown. The method begins at step S1201. The method includes, in step S1202, transmitting a signal to and / or receiving a signal from a first cell of the wireless communication network. In step S1203, the process includes determining that the communication device will perform a handover process from the first cell to a second cell of the wireless communication network, and subsequently, in step S1204, measuring the difference between the start of a first radio frame received from the first cell and the start of a second radio frame received from the second cell. In step S1205, the method includes, during the handover process, determining at least one of a propagation delay value and a timing advance value of the second cell based on the measured difference, whereby the propagation delay of the second cell defines the time taken for a signal to propagate unidirectionally between the communication device and the second cell, and the timing advance of the second cell defines the time taken for a signal to propagate round-trip between the communication device and the second cell. The process ends at step S1206.

[0142] Those skilled in the art will understand that Figure 12 The example methods shown and Figure 10 The example system shown can be adapted to embodiments of the present technology. For example, the method or system may include additional intermediate steps, or these steps may be performed in any logical order. Although Figure 12 The example method illustrates the UE determining the uplink propagation delay of the second cell in step S1205, but those skilled in the art will understand that the UE can also or alternatively determine the timing advance of the second cell, wherein, as described above, the timing advance is substantially twice the uplink propagation delay.

[0143] Those skilled in the art will further understand that such infrastructure equipment and / or communication devices as defined herein can be further defined according to the various setups and embodiments discussed in the preceding paragraphs. Those skilled in the art will further understand that such infrastructure equipment and communication devices as defined and described herein can form part of communication systems other than those defined in this disclosure.

[0144] The following numbered paragraphs provide further illustrative aspects and features of this technology:

[0145] Paragraph 1. A communication device, comprising

[0146] The transceiver circuitry is configured to transmit signals to and / or receive signals from a first cell of a wireless communication network, and

[0147] The controller circuit is configured to be combined with the transceiver circuit to...

[0148] It is determined that the communication device will perform a handover process from the first cell of the wireless communication network to the second cell of the wireless communication network.

[0149] The difference between the start of a first radio frame received from the first cell and the start of a second radio frame received from the second cell is measured, and

[0150] During the handover process, at least one of the propagation delay value and the timing advance value of the second cell is determined based on the measured difference. The propagation delay of the second cell defines the time taken for a signal to propagate unidirectionally between the communication device and the second cell, and the timing advance of the second cell defines the time taken for a signal to propagate round trip between the communication device and the second cell.

[0151] Paragraph 2. The communication apparatus according to paragraph 1, wherein the controller circuit is configured to be combined with the transceiver circuit to...

[0152] The device receives an indication of the timing advance value of the first cell, which defines the time required for a signal to travel back and forth between the communication device and the first cell.

[0153] Paragraph 3. The communication apparatus according to paragraph 2, wherein the controller circuit is configured to be combined with the transceiver circuit to...

[0154] The propagation delay value of the second cell is determined by subtracting the measured difference from a value equal to half the timing advance value of the first cell, and / or by subtracting a value equal to twice the measured difference from the timing advance value of the first cell.

[0155] Paragraph 4. The communication device according to paragraph 2 or paragraph 3, wherein the controller circuit is configured to be combined with the transceiver circuit to...

[0156] Receive an indication of an asynchrony value from the first cell, the asynchrony value defining the amount of time the first cell and the second cell are out of sync, and

[0157] The propagation delay value of the second cell is determined by subtracting the misalignment value from the measured difference, and then by subtracting the result of subtracting the misalignment value from the measured difference from a value equal to half the timing advance value of the first cell, and / or by subtracting the misalignment value from the measured difference, and then by subtracting twice the result of subtracting the misalignment value from the measured difference from the timing advance value of the first cell.

[0158] Paragraph 5. The communication apparatus according to any one of paragraphs 1-4, wherein the controller circuit is configured to be combined with the transceiver circuit to...

[0159] Send an indication of the measured difference to the first cell, and

[0160] In response to an indication of the measured difference being transmitted, at least one of the propagation delay value and the timing advance value of the second cell is determined by receiving at least one of the propagation delay value and the timing advance value of the second cell from the first cell in one or more messages of the handover process.

[0161] Paragraph 6. A communication device according to any one of paragraphs 1-5, wherein the controller circuit is configured to be combined with the transceiver circuit to...

[0162] After the handover process is completed, an update value of at least one of the propagation delay value and the timing advance value of the second cell is received from the second cell.

[0163] Paragraph 7. The communication apparatus according to any one of paragraphs 1-6, wherein the controller circuit is configured to be combined with the transceiver circuit to...

[0164] Send an indication to the second cell of at least one of the propagation delay value and the timing advance value of the second cell.

[0165] Paragraph 8. A method of operating a communication device, the method comprising:

[0166] Sending signals to and / or receiving signals from the first cell of the wireless communication network.

[0167] It is determined that the communication device will perform a handover process from the first cell of the wireless communication network to the second cell of the wireless communication network.

[0168] The difference between the start of a first radio frame received from the first cell and the start of a second radio frame received from the second cell is measured, and

[0169] During the handover process, at least one of the propagation delay value and the timing advance value of the second cell is determined based on the measured difference. The propagation delay of the second cell defines the time taken for a signal to propagate unidirectionally between the communication device and the second cell, and the timing advance of the second cell defines the time taken for a signal to propagate round trip between the communication device and the second cell.

[0170] Paragraph 9. A circuit for a communication device, said circuit comprising

[0171] The transceiver circuitry is configured to transmit signals to and / or receive signals from a first cell of a wireless communication network, and

[0172] The controller circuit is configured to be combined with the transceiver circuit to...

[0173] It is determined that the circuit will perform a handover process from the first cell of the wireless communication network to the second cell of the wireless communication network.

[0174] The difference between the start of a first radio frame received from the first cell and the start of a second radio frame received from the second cell is measured, and

[0175] During the handover process, at least one of the propagation delay value and the timing advance value of the second cell is determined based on the measured difference. The propagation delay of the second cell defines the time taken for a signal to propagate unidirectionally between the communication device and the second cell, and the timing advance of the second cell defines the time taken for a signal to propagate round trip between the communication device and the second cell.

[0176] Paragraph 10. An infrastructure device for controlling a first cell of a wireless communication network, the infrastructure device comprising...

[0177] A transceiver circuit is configured to transmit signals to and / or receive signals from a communication device, and

[0178] The controller circuit is configured to be combined with the transceiver circuit to...

[0179] It is determined that the communication device will perform a handover process from the first cell of the wireless communication network to the second cell of the wireless communication network.

[0180] The communication device receives an indication of the measured difference between the start of a first radio frame received by the communication device from the first cell and the start of a second radio frame received by the communication device from the second cell.

[0181] During the handover process, at least one of the propagation delay value and the timing advance value of the second cell is determined based on the measured difference. The propagation delay of the second cell defines the time required for a signal to propagate unidirectionally between the communication device and the second cell, and the timing advance of the second cell defines the time required for a signal to propagate round-trip between the communication device and the second cell.

[0182] In one or more messages of the handover process, an indication is sent to the communication device of at least one of the propagation delay value and the timing advance value of the second cell.

[0183] Paragraph 11. The infrastructure equipment according to paragraph 10, wherein the controller circuitry is configured to combine with the transceiver circuitry to...

[0184] The timing advance value of the first cell is determined, whereby the timing advance of the first cell defines the time required for a signal to travel round trip between the communication device and the first cell.

[0185] The propagation delay value of the second cell is determined by subtracting the measured difference from a value equal to half the timing advance value of the first cell, and / or by subtracting a value equal to twice the measured difference from the timing advance value of the second cell.

[0186] Paragraph 12. The infrastructure equipment according to paragraph 10 or paragraph 11, wherein the controller circuitry is configured to combine with the transceiver circuitry to...

[0187] The timing advance value of the first cell is determined, which defines the time required for the signal to travel round trip between the communication device and the first cell.

[0188] Determine the misalignment value between the first cell and the second cell, whereby the misalignment value defines the amount of time the first cell and the second cell are out of sync.

[0189] The propagation delay value of the second cell is determined by subtracting the misalignment value from the measured difference, and then by subtracting the result of subtracting the misalignment value from the measured difference from a value equal to half the timing advance value of the first cell, and / or by subtracting the misalignment value from the measured difference, and then by subtracting twice the result of subtracting the misalignment value from the measured difference from the timing advance value of the first cell.

[0190] Paragraph 13. A method for operating and controlling the infrastructure equipment of a first cell of a wireless communication network, the method comprising:

[0191] Sending signals to and / or receiving signals from the communication device.

[0192] It is determined that the communication device will perform a handover process from the first cell of the wireless communication network to the second cell of the wireless communication network.

[0193] The communication device receives an indication of the measured difference between the start of a first radio frame received by the communication device from the first cell and the start of a second radio frame received by the communication device from the second cell.

[0194] During the handover process, at least one of the propagation delay value and the timing advance value of the second cell is determined based on the measured difference. The propagation delay of the second cell defines the time required for a signal to propagate unidirectionally between the communication device and the second cell, and the timing advance of the second cell defines the time required for a signal to propagate round-trip between the communication device and the second cell.

[0195] In one or more messages of the handover process, an indication is sent to the communication device of at least one of the propagation delay value and the timing advance value of the second cell.

[0196] Paragraph 14. A circuit for controlling infrastructure equipment of a first cell of a wireless communication network, the circuit comprising...

[0197] A transceiver circuit is configured to transmit signals to and / or receive signals from a communication device, and

[0198] The controller circuit is configured to be combined with the transceiver circuit to...

[0199] It is determined that the communication device will perform a handover process from the first cell of the wireless communication network to the second cell of the wireless communication network.

[0200] The communication device receives an indication of the measured difference between the start of a first radio frame received by the communication device from the first cell and the start of a second radio frame received by the communication device from the second cell.

[0201] During the handover process, at least one of the propagation delay value and the timing advance value of the second cell is determined based on the measured difference. The propagation delay of the second cell defines the time required for a signal to propagate unidirectionally between the communication device and the second cell, and the timing advance of the second cell defines the time required for a signal to propagate round-trip between the communication device and the second cell.

[0202] In one or more messages of the handover process, an indication is sent to the communication device of at least one of the propagation delay value and the timing advance value of the second cell.

[0203] Paragraph 15. A communication device, comprising

[0204] A transceiver circuit is configured to transmit signals to and receive signals from a first cell of a wireless communication network.

[0205] The controller circuit is configured to be combined with the transceiver circuit to...

[0206] It is determined that the communication device will perform a handover process from the first cell of the wireless communication network to the second cell of the wireless communication network.

[0207] In the communication resources pre-allocated to the communication device and capable of transmitting signals, an uplink reference signal is transmitted to the second cell, and

[0208] In response to a transmitted uplink reference signal, at least one of a propagation delay value and a timing advance value of the second cell is received from the first cell in one or more messages of the handover process. The propagation delay of the second cell defines the time taken for a signal to propagate unidirectionally between the communication device and the second cell, and the timing advance of the second cell defines the time taken for a signal to propagate round trip between the communication device and the second cell.

[0209] Paragraph 16. A method of operating a communication device, the method comprising:

[0210] Sending signals to and receiving signals from the first cell of the wireless communication network.

[0211] The circuitry determines that it will perform the handover process from the first cell of the wireless communication network to the second cell of the wireless communication network.

[0212] In the communication resources pre-allocated to the communication device and capable of transmitting signals, an uplink reference signal is transmitted to the second cell, and

[0213] In response to a transmitted uplink reference signal, at least one of a propagation delay value and a timing advance value of the second cell is received from the first cell in one or more messages of the handover process. The propagation delay of the second cell defines the time taken for a signal to propagate unidirectionally between the communication device and the second cell, and the timing advance of the second cell defines the time taken for a signal to propagate round trip between the communication device and the second cell.

[0214] Paragraph 17. A circuit for a communication device, said circuit comprising

[0215] A transceiver circuit is configured to transmit signals to and receive signals from a first cell of a wireless communication network.

[0216] The controller circuit is configured to be combined with the transceiver circuit to...

[0217] It is determined that the circuit will perform a handover process from the first cell of the wireless communication network to the second cell of the wireless communication network.

[0218] In the communication resources pre-allocated to the communication device and capable of transmitting signals by the circuit, an uplink reference signal is transmitted to the second cell, and

[0219] In response to a transmitted uplink reference signal, at least one of a propagation delay value and a timing advance value of the second cell is received from the first cell in one or more messages of the handover process. The propagation delay of the second cell defines the time taken for a signal to propagate unidirectionally between the circuit and the second cell, and the timing advance of the second cell defines the time taken for a signal to propagate round trip between the communication device and the second cell.

[0220] Paragraph 18. An infrastructure device for controlling a first cell of a wireless communication network, the infrastructure device comprising...

[0221] A transceiver circuit is configured to transmit signals to and / or receive signals from a communication device, and

[0222] The controller circuit is configured to be combined with the transceiver circuit to...

[0223] It is determined that the communication device will perform a handover process from the first cell of the wireless communication network to the second cell of the wireless communication network.

[0224] The system receives at least one of the propagation delay value and the timing advance value of the second cell from the second cell. The propagation delay of the second cell defines the time required for a signal to propagate unidirectionally between the circuit and the second cell, and is calculated by the second cell using an uplink reference signal transmitted to the second cell by the communication device. The timing advance of the second cell defines the time required for a signal to propagate round-trip between the communication device and the second cell, and is calculated by the second cell using the uplink reference signal.

[0225] In one or more messages of the handover process, at least one of the propagation delay value of the second cell and the timing advance value of the second cell is sent to the communication device.

[0226] Paragraph 19. A method for operating and controlling the infrastructure equipment of a first cell of a wireless communication network, the method comprising...

[0227] Sending signals to and / or receiving signals from the communication device.

[0228] It is determined that the communication device will perform a handover process from the first cell of the wireless communication network to the second cell of the wireless communication network.

[0229] The system receives at least one of the propagation delay value and the timing advance value of the second cell from the second cell. The propagation delay of the second cell defines the time required for a signal to propagate unidirectionally between the circuit and the second cell, and is calculated by the second cell using an uplink reference signal transmitted to the second cell by the communication device. The timing advance of the second cell defines the time required for a signal to propagate round-trip between the communication device and the second cell, and is calculated by the second cell using the uplink reference signal.

[0230] In one or more messages of the handover process, at least one of the propagation delay value of the second cell and the timing advance value of the second cell is sent to the communication device.

[0231] Paragraph 20. A circuit for controlling infrastructure equipment of a first cell of a wireless communication network, the circuit comprising...

[0232] A transceiver circuit is configured to transmit signals to and / or receive signals from a communication device, and

[0233] The controller circuit is configured to be combined with the transceiver circuit to...

[0234] It is determined that the communication device will perform a handover process from the first cell of the wireless communication network to the second cell of the wireless communication network.

[0235] The system receives at least one of the propagation delay value and the timing advance value of the second cell from the second cell. The propagation delay of the second cell defines the time required for a signal to propagate unidirectionally between the circuit and the second cell, and is calculated by the second cell using an uplink reference signal transmitted to the second cell by the communication device. The timing advance of the second cell defines the time required for a signal to propagate round-trip between the communication device and the second cell, and is calculated by the second cell using the uplink reference signal.

[0236] In one or more messages of the handover process, at least one of the propagation delay value of the second cell and the timing advance value of the second cell is sent to the communication device.

[0237] Since embodiments of this disclosure have been described as being implemented at least in part by a data processing device controlled by software, it should be understood that non-transitory machine-readable media (e.g., optical discs, magnetic disks, semiconductor memories, etc.) carrying such software are also considered to represent embodiments of this disclosure.

[0238] It should be understood that, for clarity, the above description has referenced various functional units, circuits, and / or processors in the embodiments. However, it will be apparent that any suitable functional distribution among the various functional units, circuits, and / or processors may be used without departing from the embodiments.

[0239] The described embodiments can be implemented in any suitable form, including hardware, software, firmware, or any combination thereof. The described embodiments can optionally be implemented, at least in part, as computer software running on one or more data processors and / or digital signal processors. Elements and components of any embodiment can be implemented physically, functionally, and logically in any suitable manner. In practice, the function can be implemented in a single unit, multiple units, or as part of other functional units. Thus, the disclosed embodiments can be implemented in a single unit or can be physically and functionally distributed among different units, circuits, and / or processors.

[0240] Although this disclosure has been described in conjunction with some embodiments, it is not intended to be limited to the specific forms set forth herein. Furthermore, while a feature may appear to be described in conjunction with a particular embodiment, those skilled in the art will recognize that the various features of the described embodiments can be combined in any manner suitable for implementing the technology.

[0241] References

[0242] [1]Holma H.and Toskala A,“LTE for UMTS OFDMA and SC-FDMA based radioaccess”,John Wiley and Sons,2009.

[0243] [2]RP-192330,“New work item:2-step RACH for NR,”ZTE Corporation,3GPPTSG RAN Meeting#85.

[0244] [3]RP-192324,“Revised WID:Support of NR Industrial Internet of Things(IoT),”Nokia,Nokia Shanghai Bell,3GPP TSG RAN Meeting#85.

[0245] [4]RP-191575,“NR-based Access to Unlicensed Spectrum,”Qualcomm,Inc.,3GPP TSG RAN Meeting#84.

[0246] [5]RP-193252,“New Work Item on NR small data transmission in INACTIVEstate,”ZTE

[0247] Corporation,3GPP TSG RAN Meeting#86.

[0248] [6]ETSI TS 136213V13.0.0(2016-01) / 3GPP TS 36.212version 13.0.0Release13.

[0249] [7]R2-168544,“UL data transmission in RRC INACTIVE,”Huawei,HiSilicon,RAN#96.

[0250] [8]R2-168713,“Baseline solution for small data transmission in RRCINACTIVE,”Ericsson,Ran#96.

[0251] [9]TR 38.889,V16.0.0,“3rd Generation Partnership Project;TechnicalSpecification Group Radio Access Network;Study on NR-based Access toUnlicensed Spectrum;(Release 16),”3GPP,December 2018.

[0252]

[10] TS 38.211,V16.1.0,“3rd Generation Partnership Project;TechnicalSpecification Group Radio Access Network;NR;Physical channels and modulation;(Release 16),”3GPP,March 2020.

[0253]

[11] TS 38.215,V16.1.0,“3rd Generation Partnership Project;TechnicalSpecification Group Radio Access Network;NR;Physical layer measurements;(Release 16),”3GPP,March 2020.

Claims

1. A communication device, comprising The transceiver circuitry is configured to transmit signals to and / or receive signals from a first cell of a wireless communication network, and The controller circuit is configured to be combined with the transceiver circuit to... It is determined that the communication device will perform a handover process from the first cell of the wireless communication network to the second cell of the wireless communication network. The difference between the start of a first radio frame received from the first cell and the start of a second radio frame received from the second cell is measured. During the handover process, at least one of the propagation delay value and the timing advance value of the second cell is determined based on the measured difference. The propagation delay of the second cell defines the time required for a signal to propagate unidirectionally between the communication device and the second cell, and the timing advance of the second cell defines the time required for a signal to propagate round-trip between the communication device and the second cell. Send an indication of the measured difference to the first cell, and In response to an indication of the measured difference being transmitted, at least one of the propagation delay value and the timing advance value of the second cell is determined by receiving at least one of the propagation delay value and the timing advance value of the second cell from the first cell in one or more messages of the handover process.

2. The communication device according to claim 1, wherein, The controller circuit is configured to be combined with the transceiver circuit to... The device receives an indication of the timing advance value of the first cell, which defines the time required for a signal to travel back and forth between the communication device and the first cell.

3. The communication device according to claim 2, wherein, The controller circuit is configured to be combined with the transceiver circuit to... The propagation delay value of the second cell is determined by subtracting the measured difference from a value equal to half the timing advance value of the first cell, and / or by subtracting a value equal to twice the measured difference from the timing advance value of the first cell.

4. The communication device according to claim 2, wherein, The controller circuit is configured to be combined with the transceiver circuit to... Receive an indication of an asynchrony value from the first cell, the asynchrony value defining the amount of time the first cell and the second cell are out of sync, and The propagation delay value of the second cell is determined by subtracting the misalignment value from the measured difference, and then by subtracting the result of subtracting the misalignment value from the measured difference from a value equal to half the timing advance value of the first cell, and / or by subtracting the misalignment value from the measured difference, and then by subtracting twice the result of subtracting the misalignment value from the measured difference from the timing advance value of the first cell.

5. The communication device according to claim 1, wherein, The controller circuit is configured to be combined with the transceiver circuit to... After the handover process is completed, an update value of at least one of the propagation delay value and the timing advance value of the second cell is received from the second cell.

6. The communication device according to claim 1, wherein, The controller circuit is configured to be combined with the transceiver circuit to... Send an indication to the second cell of at least one of the propagation delay value and the timing advance value of the second cell.

7. A method of operating a communication device, the method comprising: Sending signals to and / or receiving signals from the first cell of the wireless communication network. It is determined that the communication device will perform a handover process from the first cell of the wireless communication network to the second cell of the wireless communication network. The difference between the start of a first radio frame received from the first cell and the start of a second radio frame received from the second cell is measured. During the handover process, at least one of the propagation delay value and the timing advance value of the second cell is determined based on the measured difference. The propagation delay of the second cell defines the time required for a signal to propagate unidirectionally between the communication device and the second cell, and the timing advance of the second cell defines the time required for a signal to propagate round-trip between the communication device and the second cell. Send an indication of the measured difference to the first cell, and In response to an indication of the measured difference being transmitted, at least one of the propagation delay value and the timing advance value of the second cell is determined by receiving at least one of the propagation delay value and the timing advance value of the second cell from the first cell in one or more messages of the handover process.

8. A circuit for a communication device, the circuit comprising: The transceiver circuitry is configured to transmit signals to and / or receive signals from a first cell of a wireless communication network, and The controller circuit is configured to be combined with the transceiver circuit to... It is determined that the circuit will perform a handover process from the first cell of the wireless communication network to the second cell of the wireless communication network. The difference between the start of a first radio frame received from the first cell and the start of a second radio frame received from the second cell is measured. During the handover process, at least one of the propagation delay value and the timing advance value of the second cell is determined based on the measured difference. The propagation delay of the second cell defines the time required for a signal to propagate unidirectionally between the communication device and the second cell, and the timing advance of the second cell defines the time required for a signal to propagate round-trip between the communication device and the second cell. Send an indication of the measured difference to the first cell, and In response to an indication of the measured difference being transmitted, at least one of the propagation delay value and the timing advance value of the second cell is determined by receiving at least one of the propagation delay value and the timing advance value of the second cell from the first cell in one or more messages of the handover process.

9. An infrastructure device for controlling a first cell of a wireless communication network, the infrastructure device comprising: A transceiver circuit is configured to transmit signals to and / or receive signals from a communication device, and The controller circuit is configured to be combined with the transceiver circuit to... It is determined that the communication device will perform a handover process from the first cell of the wireless communication network to the second cell of the wireless communication network. The communication device receives an indication of the measured difference between the start of a first radio frame received by the communication device from the first cell and the start of a second radio frame received by the communication device from the second cell. During the handover process, at least one of the propagation delay value and the timing advance value of the second cell is determined based on the measured difference. The propagation delay of the second cell defines the time required for a signal to propagate unidirectionally between the communication device and the second cell, and the timing advance of the second cell defines the time required for a signal to propagate round-trip between the communication device and the second cell. Send an indication of the measured difference to the first cell. In response to an indication of the measured difference transmitted, at least one of the propagation delay value and the timing advance value of the second cell is determined by receiving at least one of the propagation delay value and the timing advance value of the second cell from the first cell in one or more messages of the handover procedure. In one or more messages of the handover process, an indication is sent to the communication device of at least one of the propagation delay value and the timing advance value of the second cell.

10. The infrastructure equipment according to claim 9, wherein, The controller circuit is configured to be combined with the transceiver circuit to... The timing advance value of the first cell is determined, whereby the timing advance of the first cell defines the time required for a signal to travel round trip between the communication device and the first cell. The propagation delay value of the second cell is determined by subtracting the measured difference from a value equal to half the timing advance value of the first cell, and / or by subtracting a value equal to twice the measured difference from the timing advance value of the second cell.

11. The infrastructure equipment according to claim 9, wherein, The controller circuit is configured to be combined with the transceiver circuit to... The timing advance value of the first cell is determined, which defines the time required for the signal to travel round trip between the communication device and the first cell. Determine the misalignment value between the first cell and the second cell, whereby the misalignment value defines the amount of time the first cell and the second cell are out of sync. The propagation delay value of the second cell is determined by subtracting the misalignment value from the measured difference, and then by subtracting the result of subtracting the misalignment value from the measured difference from a value equal to half the timing advance value of the first cell, and / or by subtracting the misalignment value from the measured difference, and then by subtracting twice the result of subtracting the misalignment value from the measured difference from the timing advance value of the first cell.

12. A method for operating and controlling the infrastructure equipment of a first cell of a wireless communication network, the method comprising: Sending signals to and / or receiving signals from the communication device. It is determined that the communication device will perform a handover process from the first cell of the wireless communication network to the second cell of the wireless communication network. The communication device receives an indication of the measured difference between the start of a first radio frame received by the communication device from the first cell and the start of a second radio frame received by the communication device from the second cell. During the handover process, at least one of the propagation delay value and the timing advance value of the second cell is determined based on the measured difference. The propagation delay of the second cell defines the time required for a signal to propagate unidirectionally between the communication device and the second cell, and the timing advance of the second cell defines the time required for a signal to propagate round-trip between the communication device and the second cell. Send an indication of the measured difference to the first cell. In response to an indication of the measured difference being transmitted, at least one of the propagation delay value and the timing advance value of the second cell is determined by receiving at least one of the propagation delay value and the timing advance value of the second cell from the first cell in one or more messages of the handover procedure. In one or more messages of the handover process, an indication is sent to the communication device of at least one of the propagation delay value and the timing advance value of the second cell.

13. A circuit for controlling infrastructure equipment of a first cell of a wireless communication network, the circuit comprising: A transceiver circuit is configured to transmit signals to and / or receive signals from a communication device, and The controller circuit is configured to be combined with the transceiver circuit to... It is determined that the communication device will perform a handover process from the first cell of the wireless communication network to the second cell of the wireless communication network. The communication device receives an indication of the measured difference between the start of a first radio frame received by the communication device from the first cell and the start of a second radio frame received by the communication device from the second cell. During the handover process, at least one of the propagation delay value and the timing advance value of the second cell is determined based on the measured difference. The propagation delay of the second cell defines the time required for a signal to propagate unidirectionally between the communication device and the second cell, and the timing advance of the second cell defines the time required for a signal to propagate round-trip between the communication device and the second cell. Send an indication of the measured difference to the first cell. In response to an indication of the measured difference transmitted, at least one of the propagation delay value and the timing advance value of the second cell is determined by receiving at least one of the propagation delay value and the timing advance value of the second cell from the first cell in one or more messages of the handover procedure. In one or more messages of the handover process, an indication is sent to the communication device of at least one of the propagation delay value and the timing advance value of the second cell.

14. A communication device, comprising A transceiver circuit is configured to transmit signals to and receive signals from a first cell of a wireless communication network. The controller circuit is configured to be combined with the transceiver circuit to... It is determined that the communication device will perform a handover process from the first cell of the wireless communication network to the second cell of the wireless communication network. The difference between the start of a first radio frame received from the first cell and the start of a second radio frame received from the second cell is measured, and an indication of the measured difference is sent to the first cell so that the first cell can determine at least one of the propagation delay value and the timing advance value of the second cell based on the measured difference. In communication resources pre-allocated to the communication device and capable of transmitting signals, an uplink reference signal is sent to the second cell. In response to a transmitted uplink reference signal, in one or more messages of the handover process, at least one of a propagation delay value and a timing advance value of the second cell, determined based on a measured difference, is received from the first cell. The propagation delay of the second cell defines the time required for a signal to propagate unidirectionally between the communication device and the second cell, and the timing advance of the second cell defines the time required for a signal to propagate round-trip between the communication device and the second cell. The communication device is able to report the timing advance value for the transmission of the uplink reference signal to the second cell, the timing advance value being included in the handover completion message, so that the second cell records and stores the timing advance value; and when the second cell determines that the timing advance value is incorrect or the difference between the timing advance value and the actual value exceeds a threshold, it receives an updated value of the timing advance value from the second cell.

15. A method of operating a communication device, the method comprising: Sending signals to and receiving signals from the first cell of the wireless communication network. The circuitry determines that it will perform the handover process from the first cell of the wireless communication network to the second cell of the wireless communication network. The method measures the difference between the start of a first radio frame received from the first cell and the start of a second radio frame received from the second cell, sends an indication of the measured difference to the first cell, enabling the first cell to determine at least one of the propagation delay value and the timing advance value of the second cell based on the measured difference, and sends an uplink reference signal to the second cell in communication resources pre-allocated to the communication device and capable of transmitting signals. In response to a transmitted uplink reference signal, in one or more messages of the handover process, at least one of a propagation delay value and a timing advance value of the second cell, determined based on a measured difference, is received from the first cell. The propagation delay of the second cell defines the time required for a signal to propagate unidirectionally between the communication device and the second cell, and the timing advance of the second cell defines the time required for a signal to propagate round-trip between the communication device and the second cell. The communication device is able to report the timing advance value for the transmission of the uplink reference signal to the second cell, the timing advance value being included in the handover completion message, so that the second cell records and stores the timing advance value; and when the second cell determines that the timing advance value is incorrect or the difference between the timing advance value and the actual value exceeds a threshold, it receives an updated value of the timing advance value from the second cell.

16. A circuit for a communication device, the circuit comprising: A transceiver circuit is configured to transmit signals to and receive signals from a first cell of a wireless communication network. The controller circuit is configured to be combined with the transceiver circuit to... It is determined that the circuit will perform a handover process from the first cell of the wireless communication network to the second cell of the wireless communication network. The difference between the start of a first radio frame received from the first cell and the start of a second radio frame received from the second cell is measured. An indication of the measured difference is sent to the first cell so that the first cell can determine at least one of the propagation delay value and the timing advance value of the second cell based on the measured difference. An uplink reference signal is then sent to the second cell from communication resources pre-allocated to the communication device and capable of transmitting signals. In response to a transmitted uplink reference signal, in one or more messages of the handover process, at least one of a propagation delay value and a timing advance value of the second cell, determined based on a measured difference, is received from the first cell. The propagation delay of the second cell defines the time required for a signal to propagate unidirectionally between the circuit and the second cell, and the timing advance of the second cell defines the time required for a signal to propagate round-trip between the communication device and the second cell. The communication device is able to report the timing advance value for the transmission of the uplink reference signal to the second cell, the timing advance value being included in the handover completion message, so that the second cell records and stores the timing advance value; and when the second cell determines that the timing advance value is incorrect or the difference between the timing advance value and the actual value exceeds a threshold, it receives an updated value of the timing advance value from the second cell.

17. An infrastructure device for controlling a first cell of a wireless communication network, the infrastructure device comprising: A transceiver circuit is configured to transmit signals to and / or receive signals from a communication device, and The controller circuit is configured to be combined with the transceiver circuit to... It is determined that the communication device will perform a handover process from the first cell of the wireless communication network to the second cell of the wireless communication network. The communication device receives an indication of the difference between the start of a first radio frame received from the first cell and the start of a second radio frame received from the second cell, as measured by the communication device, so that the second cell can determine at least one of a propagation delay value and a timing advance value of the second cell based on the measured difference. The system receives at least one of the propagation delay value and the timing advance value of the second cell, determined based on the measured difference, from the second cell. The propagation delay of the second cell defines the time required for a signal to propagate unidirectionally between the circuit and the second cell, and is calculated by the second cell using an uplink reference signal transmitted to the second cell by the communication device. The timing advance of the second cell defines the time required for a signal to propagate round-trip between the communication device and the second cell, and is calculated by the second cell using the uplink reference signal. The communication device is capable of reporting the timing advance value for the transmission of the uplink reference signal to the second cell, the timing advance value report being included in the handover completion message, causing the second cell to record and store the timing advance value; and receiving an updated timing advance value from the second cell when the second cell determines that the timing advance value is incorrect or the difference between the timing advance value and the actual value exceeds a threshold amount, and In one or more messages of the handover process, at least one of the propagation delay value of the second cell determined based on the measured difference and the timing advance value of the second cell is sent to the communication device.

18. A method for operating and controlling the infrastructure equipment of a first cell of a wireless communication network, the method comprising: Sending signals to and / or receiving signals from the communication device. It is determined that the communication device will perform a handover process from the first cell of the wireless communication network to the second cell of the wireless communication network. The communication device receives an indication of the difference between the start of a first radio frame received from the first cell and the start of a second radio frame received from the second cell, as measured by the communication device, so that the second cell can determine at least one of a propagation delay value and a timing advance value of the second cell based on the measured difference. The system receives at least one of the propagation delay value and the timing advance value of the second cell, determined based on the measured difference, from the second cell. The propagation delay of the second cell defines the time required for a signal to propagate unidirectionally between the circuit and the second cell, and is calculated by the second cell using an uplink reference signal transmitted to the second cell by the communication device. The timing advance of the second cell defines the time required for a signal to propagate round-trip between the communication device and the second cell, and is calculated by the second cell using the uplink reference signal. The communication device is capable of reporting the timing advance value for the transmission of the uplink reference signal to the second cell, the timing advance value report being included in the handover completion message, causing the second cell to record and store the timing advance value; and receiving an updated timing advance value from the second cell when the second cell determines that the timing advance value is incorrect or the difference between the timing advance value and the actual value exceeds a threshold amount, and In one or more messages of the handover process, at least one of the propagation delay value of the second cell and the timing advance value of the second cell, determined based on the measured difference, is sent to the communication device.

19. A circuit for controlling infrastructure equipment of a first cell of a wireless communication network, the circuit comprising: A transceiver circuit is configured to transmit signals to and / or receive signals from a communication device, and The controller circuit is configured to be combined with the transceiver circuit to... It is determined that the communication device will perform a handover process from the first cell of the wireless communication network to the second cell of the wireless communication network. The communication device receives an indication of the difference between the start of a first radio frame received from the first cell and the start of a second radio frame received from the second cell, as measured by the communication device, so that the second cell can determine at least one of a propagation delay value and a timing advance value of the second cell based on the measured difference. The system receives at least one of the propagation delay value and the timing advance value of the second cell, determined based on the measured difference, from the second cell. The propagation delay of the second cell defines the time required for a signal to propagate unidirectionally between the circuit and the second cell, and is calculated by the second cell using an uplink reference signal transmitted to the second cell by the communication device. The timing advance of the second cell defines the time required for a signal to propagate round-trip between the communication device and the second cell, and is calculated by the second cell using the uplink reference signal. The communication device is capable of reporting the timing advance value for the transmission of the uplink reference signal to the second cell, the timing advance value report being included in the handover completion message, causing the second cell to record and store the timing advance value; and receiving an updated timing advance value from the second cell when the second cell determines that the timing advance value is incorrect or the difference between the timing advance value and the actual value exceeds a threshold amount, and In one or more messages of the handover process, at least one of the propagation delay value of the second cell and the timing advance value of the second cell, determined based on the measured difference, is sent to the communication device.

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