User equipment, target base station and method for performing a handover procedure

Abstract

The present disclosure relates to a user equipment comprising: a transceiver unit configured to receive a handover command message from a source base station, the handover command message comprising information about at least a first bandwidth part and a different second bandwidth part in a downlink and the first bandwidth part and the different second bandwidth part in an uplink; and a processor configured to, upon receiving the handover command message, activate in the transceiver unit at least a preselected one of the non-user equipment selected first or second bandwidth part in the uplink and the downlink, respectively, out of the configured at least first or second bandwidth parts, and control the transceiver unit to perform uplink and downlink communication with a target base station on the at least one activated in the uplink and the downlink, respectively, out of the configured at least first or second bandwidth parts, as part of a handover procedure.

Description

[0001] This application is a divisional application of the invention patent application filed on January 14, 2019, with application number 201980013576.2 and entitled "Mobile Terminal, Target Base Station and Method for Performing Handover Process". Technical Field

[0002] This disclosure relates to a mobile terminal that performs a handover process from a source base station to a target base station in a wireless communication system. Background Technology

[0003] Currently, the 3rd Generation Partnership Project (3GPP) is focused on the next version (Release 15) of the technical specifications for next-generation cellular technology, also known as fifth generation (5G).

[0004] At the 3GPP Technical Specification Group (TSG) Radio Access Network (RAN) meeting #71 (March 2016, Gothenburg), the first 5G research project, “Study on New Radio Access Technology,” covering RAN1, RAN2, RAN3, and RAN4, was approved. This study laid the foundation for Work Item 15 (W1), which will define the first 5G standard.

[0005] 5G New Radio (NR) provides a single technology framework that addresses all use cases, requirements, and deployment scenarios defined in 3GPP TSG RAN TR 38.913 v14.1.0 “Study on Scenarios and Requirements for Next Generation Access Technologies” (December 2016, available at www.3gpp.org), including at least Enhanced Mobile Broadband (eMBB), Ultra Reliable Low Latency Communication (URLLC), and Massive Machine Type Communication (mMTC).

[0006] For example, eMBB deployment scenarios may include indoor hotspots, dense urban areas, rural areas, urban macros, and highways; URLLC deployment scenarios may include industrial control systems, mobile healthcare (remote monitoring, diagnosis, and treatment), real-time vehicle control, and wide-area monitoring and control systems for smart grids; mMTC may include scenarios with a large number of devices that transmit non-time-critical data, such as smart wearable devices and sensor networks.

[0007] 5G also provides forward compatibility, anticipating future use cases / deployment scenarios. No backward compatibility with Long Term Evolution (LTE) is required, which facilitates entirely new system designs and / or the introduction of novel features. As summarized in one of the technical reports from the NR research project (3GPP TSG TR 38.801 v2.0.0, “Study on New Radio Access Technology; Radio Access Architecture and Interfaces”, March 2017), the basic physical layer signal waveforms will be based on Orthogonal Frequency Division Multiplexing (OFDM). Waveforms based on OFDM with a cyclic prefix (CP-OFDM) are supported for both downlink and uplink. Waveforms based on Discrete Fourier Transform (DFT) Extended OFDM (DFT-S-OFDM) are also supported, complementing the CP-OFDM waveform at least up to 40 GHz in the eMBB uplink.

[0008] One of the design goals in NR is to enhance user mobility by minimizing interruptions to ongoing traffic (if any), without increasing user equipment power consumption. At RAN# 78, RAN2's task is to investigate how to address the IMT-2020 requirement regarding 0ms handover interruption time for both LTE and NR within the Rel-15 timeframe. As a first step, the handover process in LTE has been discussed as a baseline design for NR. Discussions are underway within the 3GPP working group regarding what functionalities need to be added or modified for NR mobility enhancements.

[0009] The term "downlink" refers to communication from a higher node to a lower node (e.g., communication from a base station to a relay node or to a UE, or from a relay node to a UE, etc.). The term "uplink" refers to communication from a lower node to a higher node (e.g., communication from a UE to a relay node or to a base station, or from a relay node to a base station, etc.). The term "sidelink" refers to communication between nodes at the same level (e.g., between two UEs, or between two relay nodes, or between two base stations). Summary of the Invention

[0010] One non-limiting and exemplary embodiment enables a mobile terminal to perform a faster handover from a source base station to a target base station. When the target base station has already configured multiple bandwidth portions for the mobile terminal and signals the same configuration to the mobile terminal during the handover, the mobile terminal can immediately (again) resume communication with the target base station during the handover by configuring the appropriate bandwidth portion. After the handover, other reconfiguration attempts can be avoided.

[0011] In an embodiment, the technology disclosed herein is characterized by a mobile terminal for performing a handover process from a source base station to a target base station in a mobile communication system. A target base station is configured for the mobile terminal, which has at least a first bandwidth portion and different second bandwidth portions within its cell bandwidth. The mobile terminal includes: a transceiver unit that receives a handover command message from the source base station, the handover command message including information about the configured at least first bandwidth portion and second bandwidth portion; and processing circuitry, such as a processor, which, upon receiving the handover command message, activates at least one pre-selected of the configured at least first bandwidth portion or second bandwidth portion in the transceiver unit, and controls the transceiver unit to perform communication with the target base station on at least one of the activated at least configured first bandwidth portion or second bandwidth portion as part of the handover process.

[0012] In another general aspect, the technology disclosed herein is characterized by a mobile terminal for performing a handover process from a source base station to a target base station in a mobile communication system. A target base station is configured for the mobile terminal having at least a first bandwidth portion and different second bandwidth portions within its cell bandwidth. The mobile terminal includes: a transceiver unit that receives a handover command message from the source base station, the handover command message including information about the configured at least first bandwidth portion and second bandwidth portion; and a processor that, upon receiving the handover command message, selects and activates at least one of the configured at least first bandwidth portion or second bandwidth portion in the transceiver unit, and controls the transceiver unit to perform communication with the target base station on the selected and activated at least one of the configured at least first bandwidth portion or second bandwidth portion as part of the handover process.

[0013] In a further general aspect, the technology disclosed herein is characterized by a target base station for performing a handover process of a mobile terminal from a source base station in a mobile communication system. The target base station is capable of communicating with the mobile terminal on at least a first bandwidth portion and each of different second bandwidth portions within its cell bandwidth. The target base station includes: a transceiver unit that receives a handover request message from the source base station, the handover request message including information about the mobile terminal's ability to communicate on at least the first bandwidth portion and the second bandwidth portion; and a processor that, upon receiving the handover request message, controls the transceiver unit to configure at least the first bandwidth portion and the second bandwidth portion for the mobile terminal, and controls the transceiver unit to send a handover request confirmation message to the source base station, wherein the handover request confirmation message includes information about the configured at least the first bandwidth portion and the second bandwidth portion.

[0014] In another general aspect, the technology disclosed herein is characterized by a method for performing a handover process from a source base station to a target base station for a mobile terminal in a mobile communication system. A target base station is configured for a mobile terminal having at least a first bandwidth portion and different second bandwidth portions within its cell bandwidth. The method includes the steps of: receiving a handover command message from a source base station, the handover command message including information about the configured at least first bandwidth portion and second bandwidth portion; and, upon receiving the handover command message, activating at least one pre-selected of the configured at least first bandwidth portion or second bandwidth portion, and communicating with the target base station on at least one activated of the configured at least first bandwidth portion or second bandwidth portion as part of the handover process.

[0015] In another general aspect, the technology disclosed herein is characterized by a method for performing a handover process from a source base station to a target base station for a mobile terminal in a mobile communication system. A target base station is configured for a mobile terminal having at least a first bandwidth portion and different second bandwidth portions within its cell bandwidth. The method includes the steps of: receiving a handover command message from a source base station, the handover command message including information about the configured at least first bandwidth portion and second bandwidth portion; and, upon receiving the handover command message, selecting and activating at least one of the configured at least first bandwidth portion or second bandwidth portion, and communicating with the target base station on the selected and activated at least one of the configured at least first bandwidth portion or second bandwidth portion as part of the handover process.

[0016] In yet another general aspect, the technology disclosed herein is characterized by another method for a target base station to perform a handover process for a mobile terminal in a mobile communication system from a source base station. The target base station is capable of communicating with the mobile terminal on at least a first bandwidth portion and each of different second bandwidth portions within its cell bandwidth. The method includes the steps of: receiving a handover request message from the source base station, the handover request message including information about the mobile terminal's ability to communicate on at least the first bandwidth portion and the second bandwidth portion; and upon receiving the handover request message, configuring at least the first bandwidth portion and the second bandwidth portion for the mobile terminal, and sending a handover request confirmation message to the source base station, wherein the handover request confirmation message includes information about the configured at least the first bandwidth portion and the second bandwidth portion.

[0017] In yet another general aspect, the technology disclosed herein is characterized by a user equipment comprising: a transceiver unit that receives a handover command message from a source base station, the handover command message including information relating to at least a first bandwidth portion and a different second bandwidth portion in a downlink and a first bandwidth portion and a different second bandwidth portion in an uplink; and a processor that, upon receiving the handover command message, activates, in the transceiver unit, at least one of the configured at least first bandwidth portion or second bandwidth portion in the uplink and downlink respectively, which is not selected by the user equipment, and controls the transceiver unit to perform uplink and downlink communication with a target base station on at least one of the configured at least first bandwidth portion or second bandwidth portion activated in the uplink and downlink respectively as part of the handover process.

[0018] In yet another general aspect, the technology disclosed herein is characterized by a target base station comprising: a transceiver unit that receives a handover request message from a source base station, the handover request message including information relating to the ability of a user equipment to communicate on at least a first bandwidth portion and a different second bandwidth portion in a downlink and on a first bandwidth portion and a different second bandwidth portion in an uplink; and a processor that, upon receiving the handover request message, controls the transceiver unit to configure at least a first bandwidth portion and a second bandwidth portion for the user equipment in the uplink and downlink respectively, and controls the transceiver unit to send a handover request confirmation message to the source base station, wherein the handover request confirmation message includes information relating to at least a first bandwidth portion and a second bandwidth portion configured in the uplink and downlink respectively.

[0019] In yet another general aspect, the technology disclosed herein is characterized by a method for performing a handover process for a user equipment, comprising the steps of: receiving a handover command message from a source base station, the handover command message including information relating to at least a first bandwidth portion and a different second bandwidth portion in the downlink and a first bandwidth portion and a different second bandwidth portion in the uplink; and upon receiving the handover command message, activating at least one of the configured at least first bandwidth portion or second bandwidth portion not selected by the user equipment, respectively, in the uplink and downlink, and communicating with the target base station in the uplink and downlink in at least one of the configured at least first bandwidth portion or second bandwidth portion activated in the uplink and downlink as part of the handover process.

[0020] In yet another general aspect, the technology disclosed herein is characterized by a method for a target base station to perform a handover process, comprising the steps of: receiving a handover request message from a source base station, the handover request message including information relating to the ability of a user equipment to communicate on at least a first bandwidth portion and a different second bandwidth portion in a downlink and on a first bandwidth portion and a different second bandwidth portion in an uplink; and upon receiving the handover request message, configuring at least a first bandwidth portion and a second bandwidth portion for the user equipment in the uplink and downlink respectively, and sending a handover request confirmation message to the source base station, wherein the handover request confirmation message includes information relating to at least a first bandwidth portion and a second bandwidth portion configured in the uplink and downlink respectively.

[0021] In yet another general aspect, the technology disclosed herein is characterized by an integrated circuit for processing a handover procedure for a user equipment, the process comprising: receiving a handover command message from a source base station, the handover command message including information relating to at least a first bandwidth portion and a different second bandwidth portion in the downlink and a first bandwidth portion and a different second bandwidth portion in the uplink; and, upon receiving the handover command message, activating at least one of the configured at least first bandwidth portion or second bandwidth portion, not selected by the user equipment, in the uplink and downlink respectively, and engaging in uplink and downlink communication with the target base station as part of the handover procedure on at least one of the configured at least first bandwidth portion or second bandwidth portion activated in the uplink and downlink respectively.

[0022] In yet another general aspect, the technology disclosed herein is characterized by an integrated circuit for controlling a target base station to perform a handover process, the process comprising: receiving a handover request message from a source base station, the handover request message including information relating to the ability of a user equipment to communicate on at least a first bandwidth portion and a different second bandwidth portion in a downlink and on a first bandwidth portion and a different second bandwidth portion in an uplink; and upon receiving the handover request message, configuring at least a first bandwidth portion and a second bandwidth portion for the user equipment in the uplink and downlink respectively, and sending a handover request confirmation message to the source base station, wherein the handover request confirmation message includes information relating to the at least first bandwidth portion and the second bandwidth portion configured in the uplink and downlink respectively.

[0023] It should be noted that general or specific embodiments may be implemented as systems, methods, integrated circuits, computer programs, storage media, or any alternative combination thereof.

[0024] Further benefits and advantages of the disclosed embodiments will become apparent from the specification and accompanying drawings. Benefits and / or advantages may be individually obtained from the various embodiments and features described and included in the specification and drawings, and it is not necessary to provide all of them to obtain one or more such benefits and / or advantages. Attached Figure Description

[0025] Figure 1A and 1B A sequence diagram of an exemplary switching process is shown, along with a scenario illustrating bandwidth adaptation over time.

[0026] Figure 2A and Figure 2B An exemplary scenario is shown with bandwidth portion configuration in the source and target cells before and after handover;

[0027] Figure 3 It is a block diagram showing the structure of the mobile terminal, source base station, and target base station;

[0028] Figure 4 A sequence diagram depicts a handover process implemented according to an exemplary embodiment in a 3GPP NR deployment scenario;

[0029] Figure 5 A sequence diagram is shown illustrating the handover process according to different exemplary implementations of the first embodiment in a 3GPP NR deployment scenario;

[0030] Figure 6 A sequence diagram depicts an exemplary implementation of a handover process according to a second embodiment in a 3GPP NR deployment scenario;

[0031] Figure 7 It shows the method for using according to Figure 6 The association table for the switching process;

[0032] Figure 8 The diagram shows a sequence of handover procedures according to different exemplary implementations of the second embodiment in a 3GPP NR deployment scenario; and

[0033] Figure 9 It shows the method for using according to Figure 8 Another related table for the switching process. Detailed Implementation

[0034] In 3GPP NR, bandwidth part (BWP) operation is introduced as a new feature. A BWP is a set of contiguous physical resource blocks (PRBs). It is defined as the UE's operating bandwidth within the cell's operating bandwidth. Furthermore, the BWP bandwidth is equal to or less than the maximum bandwidth capability supported by the UE.

[0035] For each UE-specific serving cell, one or more downlink BWPs and one or more uplink BWPs can be configured via dedicated radio resource control (RRC) signaling for the UE. BWP configuration can include the following attributes: parameter set (numerology), frequency location (e.g., center frequency), and bandwidth (e.g., number of PRBs), where the parameter set refers to the subcarrier spacing and cyclic prefix.

[0036] However, in version 15, for a UE, there is at most one active downlink BWP and at most one active uplink BWP for the serving cell at a given time. The UE only expects to make communications to / from the gNB via the active BWP, which means that the UE can monitor only the active downlink BWP for PDCCH and possibly PDSCH, and can send PUSCH / PUCCH only in the active uplink BWP.

[0037] NR supports the following scenario: A single scheduling DCI (Downlink Control Information) can switch the UE's active BWP from one to another within the BWPs already configured for the UE. This is called (dynamic) BWP adaptation.

[0038] The bandwidth adaptation is described in the 3GPP technical specifications for New Radio (NR) and Next Generation Radio Access Network (NG-RAN) (3GPP TSG TS 38.300V.2.0.0, “NR; NR and NG-RAN Overall Description”, December 2017):

[0039] Using Bandwidth Adaptation (BA), the UE's receive and transmit bandwidth does not need to be as large as the cell's bandwidth and can be adjusted: the bandwidth can be commanded to change (e.g., shrinking during periods of low activity to save power); the location can be moved in the frequency domain (e.g., to improve scheduling flexibility); and the subcarrier spacing can be commanded to change (e.g., to allow different services). A subset of the cell's total cell bandwidth is called the Bandwidth Part (BWP), and BA is implemented by configuring the UE with the BWP and telling the UE which of the configured BWPs is currently active.

[0040] Imagine a scenario where, for example... Figure 1B The configuration shown consists of three different BWPs, each with the same or different center frequencies, different (band) widths, and / or different subcarrier spacings:

[0041] BWP1, with a bandwidth of 40MHz and a subcarrier spacing of 15kHz;

[0042] BWP2, with a bandwidth of 10MHz and a subcarrier spacing of 15kHz; and

[0043] BWP3 has a bandwidth of 20MHz and a subcarrier spacing of 60kHz.

[0044] The 3GPP technical specifications for New Radio (NR) and Next Generation NG-RAN (3GPP TSG TS38.300 V.2.0.0, “NR; NR and NG-RAN Overall Description”, December 2017, provide a general description of network-controlled mobility. Network-controlled mobility applies to UEs in RRC_CONNECTED and is divided into two types: cell-level mobility and beam-level mobility.

[0045] Cell-level mobility requires explicit RRC signaling to be triggered, for example, during handover. For handovers between gNBs, the signaling procedure must include at least the information in 3GPP TSG TS 38.300V.2.0.0. Figure 9 The following basic components shown in .2.3.1-1 are copied here for consistency reasons. Figure 1A In contrast, beam-level mobility does not require explicit RRC signaling to be triggered—it is processed at a lower layer—and does not require the RRC to know which beam is being used at a given point in time.

[0046] like Figure 1A As shown, RRC-driven mobility is responsible for cell-level mobility, such as handover. The handover signaling procedure follows the same principles as Rel-13 LTE. For handover between gNBs, the signaling procedure includes at least the following basic components.

[0047] 1. The source gNB initiates the handover and sends a handover request through the Xn interface.

[0048] 2. The target gNB performs admission control and provides RRC configuration as part of the handover confirmation.

[0049] 3. The source gNB provides RRC configuration to the UE in the handover command. The handover command message includes at least the cell ID and information required to access the target cell, enabling the UE to access the target cell without reading system information. In some cases, information required for contention-based and non-contention-based random access may be included in the handover command message. Access information for the target cell may include beam-specific information (if any).

[0050] 4. The UE moves the RRC connection to the target gNB and replies that the handover is complete.

[0051] The handover mechanism triggered by RRC requires the UE to at least reset the MAC entity and re-establish RLC. Both RRC-managed handovers with and without PDCP entity re-establishment are supported. For DRBs using RLC AM mode, PDCP can be re-established along with a security key change, or the data recovery process can be initiated without changing the key. For DRBs and SRBs using RLCUM mode, PDCP can be re-established along with a security key change, or it can be retained as is without changing the key.

[0052] When the target gNB uses the same DRB configuration and QoS flow-to-DRB mapping as the source gNB, it can facilitate data forwarding, sequential delivery, and copy avoidance during handover. NR supports timer-based handover failure procedures. The RRC connection re-establishment procedure is used to recover from handover failures.

[0053] It should be pointed out that, Figure 1A The basic components shown not only represent handover between gNBs, but also are part of handover within the NR RAN. For simplicity, please refer to 3GPP TSG TS 38.300V.2.0.0. Figure 9 Section 2.3.2.1-1 discloses specific aspects of handover within the AMF / UPF. In this diagram, the handover request is located in message 3, the handover (request) confirmation is located in message 5, the handover command is part of communication 6, and the handover completion is part of communication 8.

[0054] Importantly, the basic components of current handover do not support the concept of bandwidth adaptation. Recognizing these shortcomings, this disclosure aims to improve the handover process.

[0055] Non-limiting and exemplary embodiments help mobile terminals perform handovers from source base stations to target base stations more quickly, minimize interruptions to ongoing data transmission (if any), and avoid increasing the power consumption of mobile terminals.

[0056] When the target base station has already configured multiple bandwidth portions for the mobile terminal during handover and signals the same configuration to the mobile terminal, the mobile terminal can immediately communicate with the target base station again during handover using the appropriate bandwidth portion configuration. After handover, no further reconfiguration or bandwidth portion adaptation attempts may be required.

[0057] It should be noted that the Xn interface for message exchange between gNBs was chosen for illustrative purposes. This should not be considered a limitation of the present disclosure and can be applied directly to AMF / UPF handover scenarios, in which information relating to bandwidth usage mentioned in this disclosure will be exchanged via the interface between the gNB and the core network.

[0058] To discuss the advantages provided in this disclosure more comprehensively, two different scenarios will be described in further detail. It will become apparent from this description that further synergistic effects can be achieved when bandwidth adaptation during handover is taken into account.

[0059] refer to Figure 2A An exemplary scenario is illustrated, in which a mobile terminal is configured to have multiple bandwidth portions in the source and target cells, for example, before or after a handover.

[0060] This exemplary scenario depicts a mobile terminal performing a handover from a source base station (more specifically, from a source cell served by the source base station) to a target base station (more specifically, in a target cell served by the target base station). In both the source and target cells, the mobile terminal is configured with multiple bandwidth portions, for example, first and second bandwidth portions with corresponding indices #0 and #1.

[0061] Specifically, in the source and target cells, the configuration (e.g., location and bandwidth) of the synchronization signal SS block in the carrier bandwidth, for example in the frequency domain, is shown for a first bandwidth portion (referred to as the BWP with index #0) and a second bandwidth portion (referred to as the BWP with index #1). Since the indicated first and second bandwidth portions are included in the same carrier bandwidth occupied by the SS block, they both correspond to the downlink bandwidth portion for the mobile terminal. However, further descriptions also apply to the uplink bandwidth portion, thus specific distinctions are omitted for simplicity.

[0062] In the source cell, both the first and second bandwidth portions are configured to be center-aligned (in the frequency domain) with one (e.g., a lower) SS block, and in the target cell, both the first and second bandwidth portions are configured to be center-aligned (in the frequency domain) with another (e.g., an upper) SS block. In other words, in this exemplary scenario, multiple bandwidth portions are located in different parts of the carrier frequency.

[0063] Therefore, when a mobile terminal is triggered to perform a handover from the source cell to the target cell, it receives radio resources from different portions of the carrier bandwidth. This is beneficial for load balancing within the target cell.

[0064] However, adaptation of the receiving operation in the mobile terminal includes: (re)tuning to the different center frequencies of the various bandwidth portions, and adjusting the filter bandwidth to the corresponding (bandwidth) of the bandwidth portion.

[0065] refer to Figure 2BThis illustrates another exemplary scenario in which the mobile terminal is configured with multiple bandwidth portions in the source and target cells, for example, before or after handover.

[0066] Now, in both the source and target cells, the first and second bandwidth portions are no longer centered (in the frequency domain) with one or another SS block, but are more flexibly distributed across the carrier bandwidth. Importantly, the mobile terminal is configured with the first bandwidth portion in both the source and target cells, which is located in the same location and has the same (band) width (e.g., in terms of the number of Physical Resource Blocks (PRBs)).

[0067] Therefore, when a mobile terminal is triggered to perform a handover from the first bandwidth portion (BWP#0) in the source cell to the first bandwidth portion (BWP#0) in the target cell, it does not need to receive radio resources from different portions of the carrier bandwidth. Instead, the reception operation in the mobile terminal can remain the same.

[0068] This other exemplary scenario does not require (re)tuning and filter adaptation, thus avoiding interruptions to ongoing traffic due to frequency retuning during handover.

[0069] However, it goes without saying that in this other exemplary scenario, the mobile terminal is configured with a second bandwidth portion (BWP#1) in both the source and target cells, which is not centered (in the frequency domain) on the respective first bandwidth portions (BWP#0). When changing between different bandwidth portions, the mobile terminal receives radio resources from different portions of the carrier bandwidth.

[0070] In other words, making a change between the first and second bandwidth portions within each of the source and target cells would require (re)tuning and filtering to adapt to both, thus delaying the change (increasing latency). However, this can be compensated for by the increased bandwidth that the mobile terminal can utilize in the second bandwidth portion (BWP#1) of both the source and target cells.

[0071] In summary, two different exemplary scenarios were discussed, in which the latter (e.g.) Figure 2B (As shown) has the following advantages: it allows for seamless handover between at least the first bandwidth portion of the source and target cells, and the former can achieve load balancing (such as... Figure 2A (As shown).

[0072] These considerations apply not only to the downlink bandwidth portion but also to the uplink bandwidth portion in the source or target cell. Similarly, for the uplink bandwidth portion, location and width are also crucial for transmission operations in the mobile terminal. The mobile terminal may need to perform uplink transmissions on different frequency resources, which typically requires (re)tuning and filter adaptation.

[0073] Therefore, the advantages / disadvantages mentioned above also apply to the downlink bandwidth portion and the uplink bandwidth portion.

[0074] Figure 3 A block diagram of a mobile communication system is shown, comprising a mobile terminal 100 (also referred to as a user equipment UE), a source base station 200-a (also referred to as a source g-node B, gNB), and a target base station 200-b (also referred to as a target g-node B, gNB). This block diagram illustrates a mobile terminal performing a handover from source base station 200-a to target base station 200-b.

[0075] Typically, multiple events can cause source base station 200-a to trigger handover of mobile terminal 100. For example, source base station 200-a may trigger handover due to poor coverage conditions of mobile terminal 100. Coverage is measured by mobile terminal 100 and subsequently reported to source base station 200-a. Alternatively, source base station 200-a may also trigger handover of mobile terminal 100 due to load balancing issues within source base station 200-a.

[0076] Regardless of the reason, the processor 230-a of the source base station 200-a sends a handover request message through its transceiver unit 220-a (see...). Figure 1A The message 1) is sent to the target base station 220-b to trigger a handover to the target base station 200-b.

[0077] This message, along with other messages, can be sent via the wireless or wired interfaces that connect base stations to each other. For example, a handover request message can be sent via the next-generation NG interface, or via the Xn interface, which is defined as part of the next-generation NG radio access network (RAN), through an entity that provides access and mobility management functions (AMF) and / or user plane functions (UPF). If the handover involves different 5G core networks, it may even be necessary to forward the same message between different AMF / PDF entities.

[0078] The transceiver unit 220-b of the target base station 200-b receives a handover request message from the source base station 200-a. Specifically, this message includes (among other things) information about the mobile terminal 100's ability to communicate on at least two different bandwidth portions (e.g., a first bandwidth portion BWP#0 and a second bandwidth portion BWP#1 in the uplink and downlink). This information helps the target base station 200-b determine how many bandwidth portions it wishes to configure for the mobile terminal 100.

[0079] For illustrative purposes, assuming that mobile terminal 100 can only communicate on a single rather than multiple bandwidth portions, target base station 200-b will avoid configuring more than one bandwidth portion for mobile terminal 100. Despite this possibility, this disclosure focuses on mobile terminal 100 capable of communicating on multiple bandwidth portions, thereby facilitating target base station 200-b to configure all multiple bandwidth portions for the mobile terminal.

[0080] The aforementioned limitations on bandwidth capacity can be understood as being equally applied to the uplink and downlink in Frequency Division Duplex (FDD) operation mode, and to the uplink and downlink in Time Division Duplex (TDD) operation mode.

[0081] In other words, if a mobile terminal is able to communicate in FDD operating mode using a single bandwidth portion, this can be understood as implying a configuration with a maximum of a single bandwidth portion in the downlink and a separate single bandwidth portion in the uplink. If a mobile terminal is able to communicate in TDD operating mode using a single bandwidth portion, this can be understood as implying a combined configuration with a maximum of a single bandwidth portion in the downlink and a single bandwidth portion in the uplink (as a pair).

[0082] For this reason, this disclosure is configured to refer to the term "bandwidth portion," which can be understood to refer equivalently to the terms "uplink and downlink bandwidth portions" or even "uplink and downlink bandwidth portion pair." Both cases only emphasize, for example, the need to configure separate bandwidth portions in the uplink and downlink. Therefore, for both FDD and TDD operations, it is essential to configure a first or second uplink and downlink bandwidth portion simultaneously.

[0083] When the target base station 200-b has received a handover request message instructing the mobile terminal 100 to communicate through at least two (e.g., first and second) bandwidth portions of the uplink and downlink, the processor 230-b then controls the transceiver unit 220-b to configure at least both the first and second bandwidth portions for the mobile terminal.

[0084] The processor 230-b in the target base station 200-b also controls the transceiver unit 220-b to send a handover (request) confirmation message to the source base station 200-a (see...). Figure 1A Message 2 in the message includes information about at least the first and second bandwidth portions configured in the uplink and downlink.

[0085] For example, this information includes location (e.g., center frequency), bandwidth (e.g., number of physical resource blocks, PRBs), a set of parameters indicating subcarrier spacing and cyclic prefixes, and an index associated with this bandwidth for each bandwidth portion in the uplink and downlink.

[0086] As an alternative to location, the information may also include an offset, which indirectly identifies the location of the uplink bandwidth portion by specifying an offset from the (given) location of the downlink bandwidth portion or an offset from a known reference location (e.g., the first PRB of the DL carrier bandwidth). Note that some parameters used for bandwidth portion configuration (e.g., location and bandwidth) may be encoded together as a single parameter in the configuration.

[0087] Similarly, the handover request confirmation message can be sent via the Xn interface that directly connects base stations to each other or the NG interface that connects base stations to the core network.

[0088] Then, the source base station 200-a forwards the information from the handover (request) confirmation message to the mobile terminal 100. This information is transmitted in the form of a handover command message (see...). Figure 1A (Message 3 in the text). In other words, the information configured in the target base station 200-b regarding at least the first bandwidth portion and the second bandwidth portion is also included in the handover command message to the mobile terminal 100.

[0089] The transceiver unit 120 of the mobile terminal 100 receives a handover command message from the source base station 200-a. This message includes information such as (as described above) regarding the configured bandwidth portion. When the handover command message is received, the processor 130 can process the information included in this disclosure using two different mechanisms, which will be discussed below as a first embodiment and a second embodiment.

[0090] Separating from the details, it is important to understand that in both embodiments, the processor 130 of mobile terminal 100 successfully activates one of the bandwidth portions already configured (specifically) for mobile terminal 100, and a handover can be performed using this configured bandwidth portion. Therefore, the mobile communication system is not limited to performing handover using a common configuration of the bandwidth portion, which is broadcast to all mobile terminals, for example, via a system information message. Using the disclosed method, congestion in the commonly configured bandwidth portion can be avoided.

[0091] In the first embodiment, the mobile terminal 100 processes the information in the handover command in such a manner that the processor 130 activates at least one preselected portion of at least the first and second bandwidth portions configured in the uplink and downlink in the transceiver unit 120. For example, the mobile terminal 100 activates (precisely) one preselected bandwidth portion in the uplink and one preselected bandwidth portion in the downlink. However, this should not be construed as a limitation in any way. Rather, the mobile terminal 100 may also activate more than one preselected bandwidth portion in the uplink and downlink. In the future, to support simultaneous multi-parameter set processing, it may be beneficial for the mobile terminal to simultaneously activate two bandwidth portions with different parameter sets in the uplink and downlink carrier bandwidths. Therefore, it can be said that the mobile terminal 100 activates at least one preselected portion of the configured bandwidth.

[0092] In the context of this disclosure, the term "preselection" should be understood to emphasize that the selection is not performed by the mobile terminal itself. This selection may be defined by the specification as a bandwidth portion with a specific index (e.g., index #0), or a special bandwidth portion such as an initial bandwidth portion or a default bandwidth portion, which is performed by the target base station and then instructed to the mobile terminal.

[0093] At least one pre-selected bandwidth portion has been activated, and the processor 130 of the mobile terminal 100 controls the transceiver unit 120 to perform communication with the target base station 200-b on the activated at least one pre-selected bandwidth portion as part of the handover.

[0094] Since the target base station 200-b also knows which of the at least two configured bandwidth portions is the pre-selected portion that the mobile terminal will activate, it can also continue to activate at least one of the same pre-selected bandwidth portions that the mobile terminal expects to activate after sending a handover (request) confirmation message.

[0095] In the first embodiment, information about at least two configured bandwidth portions is provided to the mobile terminal 100. This information is still signaled to the mobile terminal 100 even if only one of the at least two bandwidth portions has been pre-selected. Although this information adds to the payload of the handover command, it advantageously increases the flexibility during handover, allowing handover between the at least two configured bandwidth portions at handover time.

[0096] Conversely, in the second embodiment, the mobile terminal 100 processes the information in the handover command in such a way that the processor 130 first (actively) selects and then activates at least one of at least two configured bandwidth portions in the uplink and downlink in the transceiver unit 130. For example, here also, the mobile terminal 100 selects and activates (precisely) one of the at least two bandwidth portions.

[0097] Similarly, this should not be construed as a limitation in any way. On the contrary, the mobile terminal 100 can also select and activate more than one of at least two configured bandwidth portions in the uplink and downlink. For example, when two non-contiguous bandwidth portions with different parameter sets are selected and activated simultaneously, this can be used for the purpose of simultaneously processing multiple parameter sets or alleviating congestion between available radio resources.

[0098] After selecting and activating at least one of the two configured bandwidth portions in the uplink and downlink, the processor 130 of the mobile terminal 100 controls the transceiver unit 120 to communicate with the base station 200-b on the selected and activated bandwidth portion as part of the handover.

[0099] Here, the target base station 200-b does not know (exactly) which of the at least two configured bandwidth portions the mobile terminal 100 is selecting and activating. However, since both of the at least two bandwidth portions are (specifically) configured for mobile terminal selection and activation, all at least two configured bandwidth portions can be activated, thus resolving this uncertainty in the initial stage to communicate with the mobile terminal.

[0100] Then, in a later stage, as will be described in detail below, the mobile terminal may notify the target base station of the selection of the first active bandwidth through a method that distinguishes between RACH resources and PUSCH resources.

[0101] As a result, the target base station 200-b can detect from further communication with the mobile terminal 100 which of the configured bandwidth portions is actually used for communication. Thus, information about which of the configured bandwidth portions the mobile terminal has selected and activated can be obtained (retrospectively).

[0102] It is equally important here to recognize that, in the second embodiment, information about at least two bandwidth portions of the configuration is provided to the mobile terminal 100. This information (along with other information described in detail later) is signaled to the mobile terminal 100 to enable the mobile terminal to make a selection, which is then indicated to the target base station.

[0103] Although this information still advantageously increases the flexibility during handover for the payload of the handover command (additional), it (already) allows handover between at least two configured bandwidth portions.

[0104] Figure 4 A sequence diagram depicts an exemplary implementation of a handover process according to a first embodiment in a 3GPP NR deployment scenario. Specifically, a user equipment (UE) is shown when performing a handover from a source g-node B (gNB) to a target gNB.

[0105] When preparing for handover, the source gNB sends a handover request message to the target gNB (see [link]). Figure 4 Message 1 in the context of UE handover requests is typically sent on the Xn interface, which establishes communication between gNBs in the Next Generation Nang (NG) radio access network (RAN). This handover request message provides the target gNB with sufficient details to prepare for the UE handover, such as performing admission control.

[0106] Through this handover request message, the target gNB receives information about the UE's ability to communicate on at least two bandwidth portions in the uplink and downlink. This allows the target gNB to configure an appropriate number of bandwidth portions for the UE, for example, to meet the UE's capabilities. For instance, if the UE can communicate through both narrow and wide bandwidth portions, the target gNB can effectively configure both bandwidth portions for the UE.

[0107] An appropriate amount of bandwidth has already been configured in both the uplink and downlink, and the target gNB confirms this in the handover (request) message (see...). Figure 4 Message 2) includes the information contained therein. This message is sent from the target gNB to the source gNB. If the Xn interface between gNBs is available, a handover (request) confirmation message is typically also sent via the Xn interface.

[0108] Subsequently, the source gNB will switch command messages (see...) Figure 4 The information in message 3) is relayed to the UE. Therefore, the UE receives information relating to the appropriate amount of configured bandwidth. As discussed regarding 3GPP NR, the handover command message includes numerous details for the UE to perform a handover to the target gNB.

[0109] Importantly, by utilizing information about (an appropriate amount) of configured bandwidth portions, the UE is in a position where it can perform a handover to the target gNB using bandwidth portions that have been configured for the UE in a UE-specific manner. In other words, the UE is not limited to performing a handover on a single (common) initial bandwidth portion shared among multiple UEs.

[0110] Therefore, information about the configured bandwidth mitigates the impact of congestion during handover, while simultaneously eliminating the need to configure the bandwidth at a later point in time. These advantages can be achieved regardless of how a fixed handover sequence exchanges a limited number of messages.

[0111] Advantageously, UEs with a target gNB can already perform random access message transmission during handovers based on the random access channel RACH in the bandwidth portion specifically configured for the UE, without having to rely solely on the (common) initial bandwidth portion.

[0112] Specifically, by utilizing the bandwidth portion configured for the UE, RACH message 1 experiences less congestion, and RACH message 2 can be scheduled more flexibly.

[0113] The UE completes the handover by sending a handover completion message to the target gNB (see [link]). Figure 4 Message 4) to end the switch.

[0114] The different configurations of the bandwidth portions for the UE have been detailed, and so far there has been no discussion about which of the multiple bandwidth portions should be activated. This is important because the UE and the target gNB (most likely) will not activate all configured bandwidth portions in the uplink and one in the downlink, as activating more bandwidth would increase power consumption and processing complexity. This is the reason for which, in Release 15, it was agreed that NR mobile terminals should activate a single downlink bandwidth portion and a single uplink bandwidth portion at any given time.

[0115] Therefore, during handover, the UE and the target gNB will only activate one of the bandwidth portions configured in the uplink and one of the bandwidth portions activated in the downlink. Thus, it is necessary to establish a consensus between the target gNB and the UE regarding which of the two configured bandwidth portions (uplink and downlink) should be activated.

[0116] In this exemplary implementation, it is assumed that in the information about the configured bandwidth portion, there is (always) an active preselected bandwidth portion in both the uplink and downlink.

[0117] For example, assuming that the information about the configured bandwidth portions has a specific sequence, the UE and the target gNB can (always) activate the first or last bandwidth portion in the specific sequence. If there are more than two configured bandwidth portions in the sequence, the UE and the target gNB can also (always) activate another portion in the specific sequence, such as the second, third, ...

[0118] As another example, the pre-selected bandwidth portion can be some special bandwidth portion, such as the initial BWP or the default BWP. Load balancing in the target cell can also be adapted by providing a new configuration in the target gNB of such a special BWP.

[0119] In summary, the fact that information about the configured bandwidth portion is provided only in a specific sequence is sufficient to establish a consensus between the UE and the target gNB on which part of that sequence should be activated.

[0120] However, for this to be possible, the sequence of information regarding the configured bandwidth portion must be identical in both the handover (request) confirmation message and the handover command. In other words, when a handover command is generated from the handover (request) confirmation message, the source gNB relaying this information retains the sequence of information.

[0121] In this exemplary extension, the handover (request) confirmation message and the handover command also include random access transport parameters, such as a preamble sequence or time and frequency resources to be used during RACH-based handover.

[0122] Importantly, the included random access transmission parameters need to be associated with at least one of the pre-selected bandwidth portions in the configuration. Therefore, the UE uses the random access transmission parameters associated (specifically) with the pre-selected bandwidth portion to be activated to perform random access message transmission (e.g., RACH message 1).

[0123] Because the degrees of freedom for defining random access transmission parameters associated only with a pre-selected portion of the configured bandwidth, RACH resource utilization can be improved. In this case, the target gNB does not need to reserve RACH resources corresponding to other configured bandwidth portions besides the pre-selected bandwidth portion for the UE performing the handover. As a result, more idle RACH resources become available to other UEs in the target cell.

[0124] In another exemplary extension of this implementation, the handover request message also includes information relating to the status of the active bandwidth portion in the source gNB. Alternatively or additionally, the handover request message includes information relating to data traffic volume predicted by the source gNB, such as the expected data traffic volume after the handover.

[0125] For example, the status of the active bandwidth portion may include, for example, a descriptor for narrowband or wideband, or a reference to the (band)width (e.g., according to physical resource blocks) of the bandwidth portion active in the source gNB before the handover. As another example, traffic volume information predicted by the source gNB may include an index of buffer size levels used to index the buffer status in the downlink, or may include information from buffer status reports from the UE in the uplink before the handover.

[0126] In both cases, when the source gNB forwards this information from the switch request message to the target gNB, the target gNB can (actively) select which configured bandwidth portion is most suitable to be one of the pre-selected configured bandwidth portions.

[0127] For example, if UE traffic demand is low or nonexistent, it is best to activate a narrower bandwidth portion during and after handover to ensure that UE power is not wasted. On the other hand, if UE traffic demand is high, it is a wise decision to activate a wider bandwidth portion in the configured section, even during handover.

[0128] Then, after the handover, UE data can be served immediately with a wider bandwidth portion (with full capacity) without the need for additional bandwidth portion switching (and thus avoid the latency introduced by bandwidth portion switching).

[0129] An argument might arise that during handover, only a small amount of traffic communicates between the UE and the target base station, such as for performing random access. Therefore, the UE can operate within a narrower bandwidth during handover. Then, after random access is complete, the target gNB can, if necessary, instruct the UE to switch to a wider BWP via DCI. However, the following drawbacks are observed:

[0130] - Although the BWP handover transition time is still under discussion, it will likely require at least one time slot (15kHz SCS). Therefore, if a BWP handover DCI is transmitted in time slot n, and the UE performs a BWP handover in time slot n+1 (since BWP handover DCI with empty data scheduling is not supported, the UE still needs to receive PDSCH in the narrow BWP in time slot n), the first opportunity to schedule UE data in the wide BWP is time slot n+2. If the UE's traffic demand is high, the data transmission latency will be affected.

[0131] Furthermore, Channel State Information (CSI) is also delayed. Since CSI is measured within the active BWP, it is unavailable until the wide BWP is activated. Therefore, in the example above, where the wide BWP is activated in slot n+2, the gNB must use a conservative scheduling decision for at least slot n+2 (and possibly slot n+3 if the UE cannot provide CSI feedback in the same slot), resulting in further waiting time.

[0132] - There is a risk that the UE may lose the DCI used for BWP handover. Although this is related to general DCI error conditions, it is more reasonable to avoid unnecessary BWP handovers by consistently setting the BWP during and after handover.

[0133] To communicate this selection of the pre-selected bandwidth portion to the UE, the target gNB then rearranges the information about the configured bandwidth portions in a specific sequence. For example, the target gNB may rearrange the most suitable one of the configured bandwidth portions as the first or last configured bandwidth portion included in the specific sequence in the handover (request) confirmation message. Then, when the UE is expected to activate the first or last of the specific sequence of bandwidth portions as the pre-selected bandwidth portion, it will (automatically) activate the most suitable bandwidth portion.

[0134] Figure 5 A sequence diagram illustrating the handover process according to different exemplary implementations of a first embodiment in a 3GPP NR deployment scenario is shown. Because these different exemplary implementations are... Figure 4 The exemplary implementations shown in the previous description are closely related, so the following discussion will focus only on the differences.

[0135] Similar to before, here, information about the (appropriate amount) configured bandwidth portion also puts the UE in a position where it can utilize the bandwidth portion already configured for the UE to perform a handover to the target gNB. Therefore, the same or similar advantages are achieved.

[0136] Unlike the above, there is a handover (request) confirmation message from the target gNB to the source gNB (see message 2-). Figure 5 The message also includes handover command messages from the source gNB to the UE (see message 3-). Figure 5 The index (or bandwidth portion index) is also included in the ) . This index indicates which bandwidth portion of the configuration should be activated in the uplink and downlink.

[0137] For example, both messages can include an index, such as BWP#1, for both uplink and downlink, to explicitly indicate which of the information related to the configured bandwidth portion should be activated. Therefore, using the index, the target gNB can also pre-select the corresponding bandwidth portion to be activated.

[0138] Considering that both messages include information about the first and second configured bandwidth portions, an index indicating which first or second configured bandwidth portion to send enables the UE to activate the corresponding pre-selected one of the two bandwidth portions.

[0139] Therefore, it is no longer necessary to provide information about the configured bandwidth portions in a specific sequence, but rather to arrange the information in an ascending order, such as resulting in the (narrowest) bandwidth portion first, followed by the (wider) bandwidth portion.

[0140] Similar to further exemplary extensions, the request message may also include information about the status of the active bandwidth portion in the source gNB, or information about the data traffic volume predicted by the source gNB, such as the expected data traffic volume after the handover.

[0141] In both cases, when the source gNB forwards this information from the handover request message to the target gNB, the target gNB can also (actively) select here which of the configured bandwidth portions is most suitable to be one of the pre-selected bandwidth portions. In order to convey this selection of the pre-selected bandwidth portion to the UE, the target gNB then incorporates the corresponding index of the information related to the configured bandwidth portion into the message, as described above.

[0142] Figure 6 A sequence diagram depicts a handover process according to an exemplary implementation of a second embodiment in a 3GPP NR deployment scenario. Specifically, a user equipment (UE) is shown when performing a handover from a source gNB to a target gNB.

[0143] When preparing for the switchover, the source gNB will send a switchover request message (see...). Figure 6 Message 1) is sent to the target gNB. Typically, the handover request message will be resent via the Xn interface to establish communication between gNBs in the next-generation NG radio access network (RAN) (if such a link is available; otherwise, the message will be sent via the core network). This handover request message provides the target gNB with sufficient details to prepare for the UE handover, such as performing admission control.

[0144] Through this handover request message, the target gNB receives information about the UE's ability to communicate on at least two bandwidth portions in the uplink and downlink. This allows the target gNB to configure an appropriate number of bandwidth portions for the UE, for example, that match the UE's capabilities. For instance, if the UE can communicate through both narrow and wide bandwidth portions, the target gNB can effectively configure both bandwidth portions for the UE.

[0145] An appropriate amount of bandwidth has already been configured in both the uplink and downlink, and the target gNB includes information about it in its handover (request) confirmation message (see...). Figure 6 Message 2 in the context of the target gNB is sent from the target gNB to the source gNB. If possible, a handover (request) confirmation message is also typically sent via the Xn interface.

[0146] Unlike the above, the target gNB also includes an association table in the handover (request) confirmation message, which associates each of the two configured bandwidth portions with different random access transmission parameters.

[0147] An example of this type of related table is... Figure 7 The example is shown below. This example assumes that at least two bandwidth portions are configured in the uplink and downlink, identifying UL BWP#0 and UL BWP#1 or DL ​​BWP#0 and DL BWP#1, respectively. The additional column with three points suggests the possibility of including further configured bandwidth portions.

[0148] As can be seen from the table, the bandwidth portion of each configuration in the uplink and downlink is associated with different transmission parameters.

[0149] For example, a configured UL BWP#0 is associated with certain random access transmission parameters (i.e., RACH#0 or RACH#2), and a further configured UL BWP#1 is associated with different random access transmission parameters (i.e., RACH#1 or RACH#3). Similarly, configured DL BWP#0 and BWP#1 are also associated with different random access transmission parameters.

[0150] Undoubtedly, the bandwidth portion of each configuration in the uplink and downlink is individually (as previously stated) associated with different random access parameters, but also with different combinations of random access parameters.

[0151] In other words, the combination of bandwidth portions configured in each uplink and downlink is also associated with different random access transmission parameters. For example, the combination of DL BWP#0 and UL BWP#0 is associated with parameter RACH#0, while different combinations of DL BWP#0 and UL BWP#1 are associated with parameter RACH#1.

[0152] Although beneficial, it is not necessary for achieving the desired effect, as will be evident from the following text.

[0153] Subsequently, the source gNB will switch command messages (see...). Figure 6 The information in message 3) is relayed to the UE. Therefore, the UE receives information relating to an appropriate amount of the configured bandwidth. Figure 4 Similar to the situation described in the text, information about the configured bandwidth portion mitigates the congestion impact on the (common) initial bandwidth portion during handover, while eliminating the need to configure the bandwidth portion at a later point in time.

[0154] The source gNB also relays the association table from the relay command message to the UE. This association table enables the UE to perform a random access channel (RACH) based handover to the target gNB. Depending on whether the RACH resource is contention-based or non-contention-based, it can be either contention-based or non-contention-based random access, depending on the target gNB's decision to place it in the association table.

[0155] UEs with a target gNB can perform random access message transmission on the configured bandwidth portion during RACH-based handover, instead of relying solely on the (common) initial bandwidth portion.

[0156] Specifically, by utilizing the configured bandwidth, there is less congestion for RACH message 1 in the uplink, and RACH message 2 can be scheduled more flexibly in the downlink.

[0157] The UE sends a handover completion message to the target gNB (see message 6-). Figure 6 Use ) to end the switch.

[0158] The different configurations of the bandwidth portion for the UE have been detailed. It is also necessary to establish a common understanding between the target gNB and the UE regarding which of the two bandwidth portions of the uplink and downlink configurations will be activated.

[0159] In this exemplary implementation, it is assumed that the UE (actively) selects the bandwidth portion of the configuration to be activated. In other words, the UE is in a state where it is not subject to any pre-selection constraints imposed by the target gNB, but can (freely) choose the bandwidth portion of any configuration regarding what information to relay from the target gNB.

[0160] Advantageously, the UE is typically the most knowledgeable and able to predict its own uplink traffic. While it's true that the UE signals buffer status reports to the source gNB, this isn't necessarily resolved at the target gNB during handover. Furthermore, due to the time interval between reporting the buffer status and the UE receiving the handover command, it may be outdated. Therefore, by having the UE (actively) select the bandwidth portion of the configuration to activate, it can be ensured that, at least in the uplink, this activation is best suited to the UE's needs during and after handover.

[0161] Having selected one of the configured bandwidth portions, the UE performs RACH-based handover by first activating the selected bandwidth portion and then using parameters associated with the selected and activated bandwidth portion to perform random access message transmission.

[0162] Random access message transmission not only uses associated parameters but also operates on the selected and activated bandwidth portion. Therefore, there is a clear correlation between the transmission parameters and the bandwidth portion used to perform the transmission. This provides the following advantages.

[0163] For example, assuming the UE selects and activates UL BWP#1, then Figure 7The association table in the UE requires the use of either parameter RACH#1 or RACH#3. Regardless of the method, when the UE performs random access message transmission using parameter RACH#1 or RACH#3, the target gNB can automatically reconfirm that random access transmission has been performed via (correct) UL BWP#1.

[0164] This level of guarantee is beneficial. Random access transmissions do not occupy the full uplink bandwidth portion, therefore, it is difficult for the target gNB to distinguish between different uplink bandwidth portions, especially when, for example, two configured uplink bandwidth portions are centered on each other or have significant overlap in configuration.

[0165] Therefore, the association table prevents the target gNB from receiving random access message transmissions but not being able to determine which uplink bandwidth portion is being used and thus has been selected and activated by the UE.

[0166] In addition, from Figure 7 The parameters in the association table also convey information about the selected and activated downlink segments. For example, when the UE performs random access message transmission using parameter RACH#1, the target gNB knows not only that ULBWP#1 has been selected, but also that DL BWP#0 has been selected.

[0167] Therefore, the association table can help the UE and gNB reach a consensus on which portion of the configured bandwidth in the uplink and downlink the UE has selected and activated for communication as part of the (already) handover process.

[0168] Now refer to RACH-based handover in more detail. Based on the information in the handover command, the UE selects and activates one of the configured bandwidth portions in the uplink and downlink. These bandwidth portions are used in subsequent handover processes.

[0169] The UE uses the preamble sequence and / or time and frequency resources corresponding to the association table of the selected and activated bandwidth to send a random access preamble message to the target gNB (see message 4-). Figure 6 ).

[0170] This random access preamble message is received at the target gNB and responded to with a random access response message (see message 5-). Figure 6 The message is sent from the target gNB to the UE. The target gNB allocates the corresponding bandwidth in the downlink for the transmission of this message.

[0171] When the example of returning random access transmission parameters RACH#1 is shown, the target gNB allocates the downlink bandwidth portion DLBWP#0 for the transmission of the random access response message. Again, this can be understood as a consensus between the UE and the target gNB regarding which portion of the configured bandwidth will be used during and after handover.

[0172] However, in some cases, this degree of autonomy for the UE is undesirable, or even detrimental.

[0173] Therefore, in this exemplary extension of the implementation, the handover (response) confirmation includes a bandwidth portion index, which is forwarded to the UE in the handover command, thus limiting the UE's freedom to select a bandwidth portion. Therefore, the UE receives information about the configured bandwidth portion; however, the UE can only select information corresponding to the index. This restriction can also be imposed by the source gNB in ​​the handover command. In this case, the bandwidth portion index is determined by the source gNB.

[0174] This is particularly advantageous when the index is used to select a specific downlink bandwidth portion to be used, while retaining the UE's (active) freedom to select its uplink bandwidth portion for handover. Then, the index is used to select a subset of the bandwidth portion combinations, specifically the uplink bandwidth portion corresponding to that particular downlink bandwidth portion indexed.

[0175] Using this definition of bandwidth portion indexing, the UE is restricted to selecting and activating the bandwidth portion for which this information is included in the handover command from a subset of all configured bandwidth portions. This subset includes all configured uplink bandwidth portions but excludes configured downlink bandwidth portions, as these are pre-selected by the index.

[0176] The beneficial effect stems from the observation that the UE is typically the most knowledgeable and predictive of its own uplink traffic, while the source or target gNB can best predict downlink traffic. In other words, the index is moderated between two extremes: one where the target gNB pre-selects one extreme of all bandwidth portions, and the other where the UE selects the other extreme of all bandwidth portions.

[0177] When combined with the following modifications, this exemplary extension with an index leads to further advantages.

[0178] In another exemplary extension of this implementation, the handover request message also includes information about the status of the active bandwidth portion in the source gNB. Alternatively or additionally, the handover request message includes information related to data traffic volume predicted by the source gNB, such as the expected data traffic volume after the handover.

[0179] In both cases, when this information in the handover request message is forwarded to the target gNB, the UE can (actively) choose which configured bandwidth portion is most suitable to be the pre-selected downlink bandwidth portion, without limiting the UE's (active) freedom to select the uplink bandwidth portion from the configured bandwidth portions.

[0180] In order to convey this selection of the pre-selected downlink bandwidth portion to the UE, the target gNB includes the corresponding index (bandwidth portion index) in the handover (request) confirmation message, which is relayed to the UE by the source gNB in ​​the form of a handover command.

[0181] Then, when the UE is expected to select and activate a configured bandwidth portion, the selection is restricted to a subset of all configured bandwidth portions included in the handover command regarding this information. Thus, the UE not only cannot (actively) select the optimal uplink bandwidth portion, but is also guided in selecting the optimal downlink bandwidth portion.

[0182] Needless to say, the association table allows the target gNB to obtain the re-guarantee level of which uplink bandwidth portion of the configuration has been selected and activated by the UE.

[0183] In various exemplary extensions of this implementation, the bandwidth portion index in the handover (request) confirmation message and the handover command index a single bandwidth portion in both the uplink and downlink. Thus, the UE is deprived of the freedom to select any of the configured bandwidth portions, whether in the downlink or uplink.

[0184] Returning to the more general discussion of the exemplary implementation, it must be mentioned that the target gNB is unaware in advance that the UE has selected one of the configured bandwidth portions before the UE makes its initial contact with the target gNB by sending RACH message 1. In other words, this truly gives the UE the freedom to select and (simultaneously) activate one of the (most suitable) configured bandwidth portions (at least for the uplink).

[0185] Since a random access transmission message has already been sent on the uplink bandwidth portion selected by the UE (see message 4-), Figure 6 Therefore, the target gNB must make arrangements to receive the message, regardless of the choice made. This uncertainty leaves the target gNB in ​​a situation where it cannot predict the portion of uplink bandwidth it will use.

[0186] For this reason, the target gNB activates not just one, but all configured uplink bandwidth segments; for example, all uplink bandwidth segments for which information is included in the handover (request) confirmation and handover command messages. In other words, unlike previous implementations, the target gNB must monitor not just one, but all configured uplink bandwidth segments.

[0187] However, once the association table indicates which of the configured bandwidth sections has been selected, the uncertainty is removed from the target gNB, and the deactivation of all unselected bandwidth sections can proceed.

[0188] Returning to the example, where the UE has selected RACH#1 to use with the random access preamble transmission (Message 4- Figure 6 Due to uncertainty, the target gNB must activate UL BWP#0 and UL BWP#1, which have already been configured and indicated to the UE as additional information. Only in this way can the target gNB ensure that it receives the message regardless of which option is selected.

[0189] Upon receiving the random access preamble transmission with RACH#1, the target gNB is provided with knowledge about the UE's selection result, such as knowing that the UE has selected... Figure 7 The DL BWP #0 and UL BWP #1 are shown. The target gNB can then immediately proceed to activate the remaining configured but unselected parts.

[0190] Figure 8 A sequence diagram illustrating the handover process according to different exemplary implementations of a second embodiment in a 3GPP NR deployment scenario is shown. Because these different exemplary implementations are... Figure 6 The exemplary implementations shown in the previous description are closely related, so the following discussion will focus only on the differences.

[0191] Starting from this point, this implementation is based on the understanding that handover does not necessarily require RACH transmission (referred to as RACH-based handover), but can also be performed in a RACH-free manner (referred to as: RACH-free handover).

[0192] For example, consider a RACH-free handover in a mobile communication system where time synchronization exists between multiple gNBs, or where the UE performing the handover already knows about time advances related to neighboring cells (e.g., when a secondary cell (SCell) changes to a primary cell (PCell)). In such cases, when performing a handover from the source to the target cell, the UE does not need to perform a random access procedure for re-establishing time synchronization.

[0193] For example, when communicating with either the source or target gNB, a UE with this RACH-free handover will reuse the same timing advance command. When there is no timing uncertainty in the target gNB, there is absolutely no need to perform random access transmissions, such as random access preamble transmissions.

[0194] Based on this understanding, it is immediately apparent that an association table that links the configured bandwidth portion to different random access transmission parameters is useless. Instead, in this exemplary implementation, there exists an association table that associates the configured bandwidth portion with different uplink shared channel transmission parameters, as shown in Figure 9.

[0195] For example, different uplink shared channel transmission parameters may include the time and frequency of radio channel resources, which can be used by the UE when sending a handover completion message (see message 4-). Figure 8 In other words, uplink shared channel transmission parameters can be considered as uplink licensing of different radio resources in the physical uplink shared channel of the target base station.

[0196] Apart from this fundamental difference, the handover process only involves the handover (request) confirmation message sent from the target gNB to the UE via the source gNB (see message 2-). Figure 8 ) and switching command messages (see message 3- Figure 8 The information included in the document differs from that in the document.

[0197] These messages do not include an association table that associates the configured bandwidth portion with different random access transmission parameters, but instead include an association table that associates the configured bandwidth portion with different uplink shared channel transmission parameters.

[0198] By utilizing different uplink shared channel transmission parameters, the target gNB also gains a beneficial level of reassurance. Since the handover completion transmission does not occupy a full portion of the uplink bandwidth, the target gNB will have difficulty distinguishing between different uplink bandwidth portions, especially when, for example, two configured uplink bandwidth portions are centered on each other or have significant overlap.

[0199] Therefore, the association table also advantageously prevents situations where the target gNB receives uplink shared channel transmissions but cannot determine which uplink bandwidth portion is being used, and thus has already been selected and activated by the UE. For further details, refer to [reference needed]. Figure 6 The above description can be understood as a similar description of the process and its advantages.

[0200] It should be mentioned that, in the case of carrier aggregation with multiple component carriers configured for the UE, the bandwidth portion configuration and activation method in this disclosure is for each component carrier. In other words, each component carrier has an independent bandwidth portion configuration. During handover, the UE's PCell will be changed. However, depending on the handover confirmation received by the UE, the UE's SCell configuration may be released or retained. Similarly, a new bandwidth portion configuration may be provided accordingly.

[0201] Referring now to the most general description, it can be summarized that this disclosure provides a mechanism that allows for coordinated configuration of bandwidth during handover, thereby minimizing downtime and reducing power consumption during handover. Figuratively speaking, if the utilization level of the target base station allows, the bandwidth portion can be configured to be the same in both the source and target cells, as shown in reference [reference needed]. Figure 2B The subject of discussion.

[0202] If switching request message (see message 1-) Figure 4 , 5 (6 and 8) In particular, this includes information about at least a third and different fourth bandwidth portions configured in the source base station and / or information about the activation of one of the at least third and fourth bandwidth portions configured in the source base station.

[0203] Then, the target base station can configure the first bandwidth portion and the second bandwidth portion in the transceiver unit for the mobile terminal based on the third bandwidth portion and the fourth bandwidth portion, respectively. More specifically, the target base station can configure the first bandwidth portion, which is the same as (or similar to) the third bandwidth portion, and the second bandwidth portion, which is the same as (or similar to) the fourth bandwidth portion.

[0204] Therefore, coordinated configuration of the bandwidth portion is achieved during switching, thereby realizing the many advantages discussed above.

[0205] Finally, when information about the most recently activated bandwidth portion in the source base station is readily available in the target base station, the target base station can not only coordinate the configuration of the bandwidth portion for the mobile terminal, but also send a handover request confirmation message including a bandwidth portion index, wherein the bandwidth portion index is an index of the same bandwidth portion that was previously activated in the bandwidth portion configured in the source base station.

[0206] This disclosure can be implemented by software, hardware, or software cooperating with hardware. Each functional block used in the description of each of the above embodiments can be partially or wholly implemented by an LSI such as an integrated circuit, and each process described in each embodiment can be partially or wholly controlled by the same LSI or a combination of LSIs. An LSI can be formed as a chip on its own, or it can be formed as a chip to include some or all of the functional blocks. An LSI can include data inputs and outputs coupled thereto. Depending on the level of integration, the LSI herein can be referred to as an IC, a system LSI, a super LSI, or an ultra-super LSI.

[0207] However, the technology for implementing integrated circuits is not limited to LSIs and can be implemented using dedicated circuits, general-purpose processors, or special-purpose processors. Alternatively, FPGAs (Field-Programmable Gate Arrays) that can be programmed after the LSI is manufactured, or reconfigurable processors in which the connections and settings of circuit cells arranged within the LSI can be reconfigured, can be used. This disclosure can be implemented as digital or analog processing. If future integrated circuit technologies replace LSIs due to advancements in semiconductor technology or other derivative technologies, then future integrated circuit technologies can be used to integrate functional blocks. Biotechnology can also be applied.

[0208] According to a first aspect, a mobile terminal is proposed for performing a handover process from a source base station to a target base station in a mobile communication system. The target base station is configured for the mobile terminal having at least a first bandwidth portion and different second bandwidth portions within its cell bandwidth. The mobile terminal includes: a transceiver unit that receives a handover command message from the source base station, the handover command message including information about the configured at least first bandwidth portion and second bandwidth portion; and a processor that, upon receiving the handover command message, activates at least one pre-selected of the configured at least first bandwidth portion or second bandwidth portion in the transceiver unit, and controls the transceiver unit to perform communication with the target base station on at least one activated of the configured at least first bandwidth portion or second bandwidth portion as part of the handover process.

[0209] According to the second aspect, which can be combined with the first aspect, the information regarding the configuration of at least the first bandwidth portion and the second bandwidth portion has a specific sequence, and if more than the first bandwidth portion and the second bandwidth portion are configured, the processor activates the first or last or a specific other in the specific sequence as a pre-selected one of the bandwidth portions.

[0210] According to a third aspect that can be combined with the first aspect, the received switching command message also includes a bandwidth portion index, and the processor activates a pre-selected bandwidth portion corresponding to the bandwidth portion index in at least the first or second bandwidth portion of the configuration.

[0211] According to a fourth aspect that can be combined with the first to third aspects, as part of the handover process, the processor controls the transceiver unit to perform at least the transmission of random access messages to the target base station.

[0212] According to a fifth aspect that can be combined with the first to fourth aspects, if the received handover command message further includes a plurality of different random access transmission parameters associated with at least one of the configured first bandwidth portion and second bandwidth portion, the processor controls the transceiver unit to perform at least random access message transmission to the target base station using the random access transmission parameters associated with the active preselected one of the configured at least first bandwidth portion or second bandwidth portion.

[0213] According to a sixth aspect, a mobile terminal is proposed for performing a handover process from a source base station to a target base station in a mobile communication system. The target base station is configured for the mobile terminal having at least a first bandwidth portion and different second bandwidth portions within its cell bandwidth. The mobile terminal includes: a transceiver unit that receives a handover command message from the source base station, the handover command message including information about the configured at least first bandwidth portion and second bandwidth portion; and a processor that, upon receiving the handover command message, selects and activates at least one of the configured at least first bandwidth portion or second bandwidth portion in the transceiver unit, and controls the transceiver unit to perform communication with the target base station on the selected and activated at least one of the configured at least first bandwidth portion or second bandwidth portion as part of the handover process.

[0214] According to the seventh aspect, which can be combined with the sixth aspect, the received switching command message also includes a bandwidth portion index, and the processor selects and activates one of the configured subsets of at least the first bandwidth portion or the second bandwidth portion corresponding to the bandwidth portion index in the transceiver unit.

[0215] According to the eighth aspect, which can be combined with the sixth aspect, the bandwidth portion index is a subset of the uplink bandwidth portion of a specific downlink bandwidth portion index, and the processor selects and activates at least a subset of the first or second bandwidth portion corresponding to the bandwidth portion index in the transceiver unit.

[0216] According to the ninth aspect, which can be combined with the sixth to eighth aspects, the received handover command message further includes: a plurality of different random access transmission parameters associated with each or a subset of the configured at least first bandwidth portion and second bandwidth portion; and a processor that controls the transceiver unit to perform at least random access message transmission using the random access transmission parameters associated with the selection and activation of at least the configured first bandwidth portion or second bandwidth portion.

[0217] According to the tenth aspect, which may be combined with the ninth aspect, the plurality of random access transmission parameters include at least one or more of the following: - a random access preamble sequence sent together with the random access message, and - the time and frequency of the radio channel resources that the mobile terminal will use when sending the random access message to the target base station.

[0218] According to the eleventh aspect, a target base station is proposed for performing a handover process of a mobile terminal from a source base station in a mobile communication system. The target base station is capable of communicating with the mobile terminal on at least a first bandwidth portion and each of different second bandwidth portions within its cell bandwidth. The target base station includes: a transceiver unit that receives a handover request message from the source base station, the handover request message including information about the mobile terminal's ability to communicate on at least the first bandwidth portion and the second bandwidth portion; and a processor that, upon receiving the handover request message, controls the transceiver unit to configure at least the first bandwidth portion and the second bandwidth portion for the mobile terminal, and controls the transceiver unit to send a handover request confirmation message to the source base station, wherein the handover request confirmation message includes information about the configured at least the first bandwidth portion and the second bandwidth portion.

[0219] According to the twelfth aspect, which can be combined with the eleventh aspect, after the processor controls the sending unit to send a handover request confirmation message, it activates in the sending unit one of the same pre-selected mobile terminals that are expected to be activated in at least the first bandwidth portion or the second bandwidth portion of the configuration.

[0220] According to the thirteenth aspect, which can be combined with the twelfth aspect, the information regarding the configuration of at least the first bandwidth portion and the second bandwidth portion has a specific sequence, and if more than the first bandwidth portion and the second bandwidth portion are configured, the processor activates the first or last of the specific sequence or a specific other as one of the preselected bandwidth portions.

[0221] According to the fourteenth aspect, which can be combined with the twelfth aspect, the switching request confirmation message also includes a bandwidth portion index, and the processor activates at least one of the preselected bandwidth portions of the configuration corresponding to the bandwidth portion index.

[0222] According to the fifteenth aspect, which can be combined with aspects eleven to fourteen, the handover request message also includes information about the status of the activated bandwidth portion or predicted traffic volume information; and when the processor receives the handover request message, it controls the transceiver unit to select and activate at least one of the first and second bandwidth portions that the mobile terminal expects to activate as a pre-selected bandwidth portion, as part of the handover process.

[0223] According to the sixteenth aspect, which can be combined with the eleventh aspect, after the processor controls the transmitting unit to send a switching request confirmation message, it activates at least the first bandwidth portion or the second bandwidth portion of all configurations in the transceiver unit.

[0224] According to the seventeenth aspect, which can be combined with the eleventh aspect, the handover request confirmation message further includes: - a plurality of different uplink shared channel transmission parameters, each parameter being associated with a different portion of at least a first bandwidth portion and a second bandwidth portion configured; and a processor that controls the transceiver unit to schedule candidates for handover completion message transmission using all of the plurality of uplink shared channel transmission parameters associated with at least the first bandwidth portion or the second bandwidth portion configured.

[0225] According to the eighteenth aspect, which can be combined with the seventeenth aspect, the multiple uplink shared channel transmission parameters include: - the time and frequency of the radio channel resources to be used by the mobile terminal when sending a handover completion message to the target base station.

[0226] According to the nineteenth aspect, which can be combined with the seventeenth or eighteenth aspect, if the handover request confirmation message also includes multiple uplink shared channel transmission parameters, each uplink shared channel transmission parameter is associated with a different one of the configured first bandwidth portion and second bandwidth portion; the transceiver unit also uses one of the multiple uplink shared channel transmission parameters to receive a handover completion message transmission from the mobile terminal, the parameter being associated with the configured first bandwidth portion or second bandwidth portion selected and activated by the mobile terminal; and the processor deactivates the remaining portions of the configured first bandwidth portion and second bandwidth portion that the mobile terminal has not yet selected and activated.

[0227] According to the twentieth aspect, which can be combined with the eleventh aspect, the handover request confirmation message further includes: - a plurality of different random access transmission parameters, each parameter being associated with a different one of at least a first bandwidth portion and a second bandwidth portion configured; and a processor that controls the transceiver unit to reserve random access message transmission using all of the plurality of random access transmission parameters associated with at least the first bandwidth portion or the second bandwidth portion configured.

[0228] According to the twenty-first aspect, which may be combined with the twentieth aspect, the plurality of random access transmission parameters include at least one or more of the following: - a random access preamble sequence transmitted together with the random access message; - the time and frequency of the radio channel resources that the mobile terminal will use when transmitting the random access message to the target base station.

[0229] According to the twenty-second aspect, which can be combined with the twenty-first aspect, if the handover request confirmation message further includes multiple different random access transmission parameters, each parameter is associated with a different one of the configured first bandwidth portion and second bandwidth portion; the transceiver unit also uses one of the multiple random access transmission parameters to receive random access message transmission from the mobile terminal, the random access transmission parameter being associated with the mobile terminal selected and activated in the configured first bandwidth portion or second bandwidth portion; and the processor deactivates the remaining portions of the configured first bandwidth portion and second bandwidth portion that the mobile terminal has not yet selected and activated.

[0230] According to the 23rd aspect, which can be combined with the eleventh aspect, the handover request message also includes: - information about at least a third bandwidth portion and a different fourth bandwidth portion configured for the mobile terminal in the source base station.

[0231] According to the twenty-fourth aspect, which can be combined with the twenty-third aspect, the handover request message also includes: - information about the activation of at least one of the third and fourth bandwidth portions configured in the source base station.

[0232] According to the twenty-fifth aspect, which can be combined with the twenty-fourth aspect, the processor configures the first bandwidth portion and the second bandwidth portion respectively in the transceiver unit for the mobile terminal based on the third bandwidth portion and the fourth bandwidth portion.

[0233] According to the twenty-sixth aspect, which can be combined with the twenty-fifth aspect, the processor controls the transceiver unit to send a handover request confirmation message including a bandwidth portion index, and the bandwidth portion index indicates the same bandwidth portion as one of the previously activated bandwidth portions of at least the third and fourth bandwidth portions configured in the source base station.

[0234] According to aspect twenty-seven, a method is proposed for performing a handover process of a mobile terminal in a mobile communication system from a source base station to a target base station. The target base station is configured for a mobile terminal having at least a first bandwidth portion and different second bandwidth portions within its cell bandwidth. The method includes the steps of: receiving a handover command message from a source base station, the handover command message including information about the configured at least first bandwidth portion and second bandwidth portion; and, upon receiving the handover command message, activating at least one pre-selected of the configured at least first bandwidth portion or second bandwidth portion, and communicating with the target base station on at least one activated of the configured at least first bandwidth portion or second bandwidth portion as part of the handover process.

[0235] According to aspect twenty-eight, a method is proposed for performing a handover process of a mobile terminal in a mobile communication system from a source base station to a target base station. The target base station is configured for a mobile terminal having at least a first bandwidth portion and a different second bandwidth portion within its cell bandwidth. The method includes the steps of: receiving a handover command message from a source base station, the handover command message including information about the configured at least first bandwidth portion and second bandwidth portion; and, upon receiving the handover command message, selecting and activating at least one of the configured at least first bandwidth portion or the second bandwidth portion, and communicating with the target base station on the selected and activated at least one of the configured at least first bandwidth portion or the second bandwidth portion as part of the handover process.

[0236] According to aspect twenty-nine, a method is proposed for a target base station to perform a handover process for a mobile terminal from a source base station in a mobile communication system. The target base station is capable of communicating with the mobile terminal on at least a first bandwidth portion and each of different second bandwidth portions within its cell bandwidth. The method includes the steps of: receiving a handover request message from the source base station, the handover request message including information about the mobile terminal's ability to communicate on at least the first bandwidth portion and the second bandwidth portion; and upon receiving the handover request message, configuring at least the first bandwidth portion and the second bandwidth portion for the mobile terminal, and sending a handover request confirmation message to the source base station, wherein the handover request confirmation message includes information about configuring at least the first bandwidth portion and the second bandwidth portion.

Claims

1. A user equipment, comprising: transceiver unit The storage medium for storing instructions, and The processor executes the instructions to cause the transceiver unit to: Receive a handover command message from the source base station, the handover command message including information relating to at least a first bandwidth portion and a different second bandwidth portion in the downlink and a first bandwidth portion and a different second bandwidth portion in the uplink; in When the processor receives a handover command message, it activates at least one of the configured first bandwidth portion or second bandwidth portion, which is not selected by the user equipment, in the transceiver unit in the uplink and downlink respectively, and controls the transceiver unit to perform uplink and downlink communication with the target base station on at least one of the configured first bandwidth portion or second bandwidth portion activated in the uplink and downlink respectively as part of the handover process.

2. The user equipment according to claim 1, wherein Information relating to at least a first bandwidth portion and a second bandwidth portion configured in the uplink and downlink respectively has a specific sequence, and if more than at least a first bandwidth portion and a second bandwidth portion are configured in the uplink and downlink respectively, the processor activates the first or last or other specific one in the specific sequence as a preselected bandwidth portion. Or, among them The received switching command message also includes a bandwidth portion index, and the processor activates a pre-selected one of the configured first or second bandwidth portions corresponding to the bandwidth portion index in the uplink and downlink, respectively.

3. The user equipment according to claim 1, wherein, The processor controls the transceiver unit to perform at least the transmission of random access messages to the target base station as part of the handover process; and / or In the case where the received handover command message also includes multiple different random access transmission parameters associated with at least one of a first bandwidth portion and a second bandwidth portion configured in the uplink and downlink respectively; The processor controls the transceiver unit to perform at least random access message transmission to the target base station using a pre-selected random access transmission parameter associated with an activation in at least a first bandwidth portion or a second bandwidth portion configured in the uplink and downlink, respectively.

4. A target base station, comprising: transceiver unit The storage medium for storing instructions, and The processor executes the instructions to cause the transceiver unit to: The user equipment receives a handover request message from the source base station, the handover request message including information relating to the user equipment’s ability to communicate on at least a first bandwidth portion and a different second bandwidth portion in the downlink and on a first bandwidth portion and a different second bandwidth portion in the uplink; in When the processor receives a handover request message, it controls the transceiver unit to configure at least a first bandwidth portion and a second bandwidth portion for the user equipment in the uplink and downlink respectively, and controls the transceiver unit to send a handover request confirmation message to the source base station, wherein the handover request confirmation message includes information related to the at least first bandwidth portion and second bandwidth portion configured in the uplink and downlink respectively.

5. The target base station according to claim 4, wherein After controlling the transceiver unit to send a handover request confirmation message, the processor activates in the transceiver unit one of the same pre-selected ones that the user equipment is expected to activate, which is configured in at least a first bandwidth portion or a second bandwidth portion in the uplink and downlink respectively. And, among them Information relating to at least a first bandwidth portion and a second bandwidth portion configured in the uplink and downlink, respectively, has a specific sequence, and If more than at least a first bandwidth portion and a second bandwidth portion are configured in the uplink and downlink respectively, the processor will activate the first or last or other specific one in the particular sequence as a preselected bandwidth portion; Or, among them The switching request confirmation message also includes a bandwidth portion index, and the processor activates a pre-selected one of the configured first or second bandwidth portions corresponding to the bandwidth portion index in the uplink and downlink, respectively.

6. The target base station according to claim 4 or 5, wherein: The switching request message also includes information related to the status of the activated bandwidth portion or predicted traffic volume. as well as When the processor receives a handover request message, it controls the transceiver unit to select and activate at least one of the first and second bandwidth portions configured in the uplink and downlink, respectively, which is the portion that the user equipment is expected to activate as a pre-selected bandwidth portion as part of the handover process.

7. The target base station according to claim 4, wherein, After the processor controls the transceiver unit to send the handover request confirmation message, it activates all at least the first bandwidth portion or the second bandwidth portion configured in the uplink and downlink respectively in the transceiver unit.

8. The target base station according to claim 4, wherein, The handover request confirmation message also includes: Multiple different uplink shared channel transmission parameters, each uplink shared channel transmission parameter being associated with at least one of a first bandwidth portion and a second bandwidth portion configured in the uplink and downlink, respectively; and The processor controls the transceiver unit to schedule and switch candidates that have completed message transmission using all of the multiple uplink shared channel transmission parameters associated with at least a first bandwidth portion or a second bandwidth portion configured in the uplink and downlink, respectively.

9. The target base station according to claim 8, wherein, The transmission parameters of the multiple uplink shared channel include: The time and frequency of the radio channel resources to be used by the user equipment when sending a handover completion message to the target base station; And, among them When the handover request confirmation message also includes multiple uplink shared channel transmission parameters, each uplink shared channel transmission parameter is associated with a different one of at least a first bandwidth portion and a second bandwidth portion configured in the uplink and downlink, respectively. The transceiver unit also uses one uplink shared channel transmission parameter, which is associated with a bandwidth portion selected and activated by the user equipment from at least a first bandwidth portion or a second bandwidth portion configured in the uplink and downlink respectively, among multiple uplink shared channel transmission parameters, to receive a handover completion message transmission from the user equipment; and The processor deactivates the remaining bandwidth portions that the user equipment has not yet selected and activated, in at least the first and second bandwidth portions configured in the uplink and downlink, respectively.

10. The target base station according to claim 4, wherein, The handover request confirmation message also includes: Multiple different random access transmission parameters, each associated with a different one of at least a first bandwidth portion and a second bandwidth portion configured in the uplink and downlink, respectively; and The processor controls the transceiver unit to reserve random access message transmission using all of the plurality of random access transmission parameters associated with at least a first bandwidth portion or a second bandwidth portion configured in the uplink and downlink, respectively. as well as, The plurality of random access transmission parameters include at least one or more of the following: The random access preamble sequence is sent along with the random access message. The time and frequency of the radio channel resources to be used by the user equipment when sending random access messages to the target base station; as well as, In cases where the handover request confirmation message also includes multiple different random access transmission parameters, each random access transmission parameter is associated with at least one of a first bandwidth portion and a second bandwidth portion configured in the uplink and downlink, respectively. The transceiver unit also uses one of the plurality of random access transmission parameters, associated with a bandwidth portion selected and activated by the user equipment in at least a first bandwidth portion or a second bandwidth portion configured in the uplink and downlink respectively, to receive random access message transmissions from the user equipment; and The processor deactivates the remaining bandwidth portions of at least the first and second bandwidth portions configured in the uplink and downlink, respectively, that the user equipment has not yet selected and activated.

11. The target base station according to claim 4, wherein the handover request message further includes: Information relating to at least a third bandwidth portion and different fourth bandwidth portions configured for user equipment in the uplink and downlink respectively in the source base station; Furthermore, the switching request message also includes: Information relating to the activation of at least one of the third bandwidth portion and the fourth bandwidth portion configured in the uplink and downlink respectively in the source base station; as well as, The processor configures a first bandwidth portion and a second bandwidth portion in the transceiver unit for the user equipment in the uplink and downlink, respectively, based on the third bandwidth portion and the fourth bandwidth portion in the uplink and downlink. and, The processor controls the transceiver unit to send a switching request confirmation message including a bandwidth portion index, and The bandwidth portion index indicates the same bandwidth portion as one of the previously activated third and fourth bandwidth portions configured in the uplink and downlink of the source base station, respectively.

12. An integrated circuit for controlling a user equipment switching process, the process comprising: Receive a handover command message from the source base station, the handover command message including information relating to at least a first bandwidth portion and a different second bandwidth portion in the downlink and a first bandwidth portion and a different second bandwidth portion in the uplink; as well as Upon receiving the handover command message, at least one of the configured first bandwidth portion or second bandwidth portion, which is not selected by the user equipment but is pre-selected, is activated in the uplink and downlink respectively, and communication in the uplink and downlink with the target base station is performed as part of the handover process on at least one of the configured first bandwidth portion or second bandwidth portion activated in the uplink and downlink respectively.

13. An integrated circuit for controlling a target base station to perform a handover process, the process comprising: The user equipment receives a handover request message from the source base station, the handover request message including information relating to the user equipment’s ability to communicate on at least a first bandwidth portion and a different second bandwidth portion in the downlink and on a first bandwidth portion and a different second bandwidth portion in the uplink; as well as Upon receiving the handover request message, at least a first bandwidth portion and a second bandwidth portion are configured for the user equipment in the uplink and downlink respectively, and a handover request confirmation message is sent to the source base station, wherein the handover request confirmation message includes information related to the at least first bandwidth portion and second bandwidth portion configured in the uplink and downlink respectively.

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