Devices, methods, apparatuses and media for switching of carriers under FDD-SDL carrier aggregation

Abstract

Embodiments of the present disclosure relate to terminal devices, network devices, methods, apparatuses and medium for switching of carriers under frequency division duplex-supplementary downlink (FDD-SDL) carrier aggregation (CA). In an aspect, a terminal device obtains first information for switching of carriers in frequency division duplex-supplementary downlink (FDD-SDL) carrier aggregation (CA), the carriers at least comprise an FDD carrier and an SDL carrier. By implementing the embodiments of the present disclosure, the terminal device could obtain the information for switching of carriers in the FDD-SDL CA, which contains information of certain aspects of switched operation for the FDD-SDL band combination, thereby proposing enhancements to standards that are needed to declare and support for the FDD-SDL band combination.

Description

DEVICES, METHODS, APPARATUSES AND MEDIA FOR SWITCHING OF CARRIERS UNDER FDD-SDL CARRIER AGGREGATIONCROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims priority from, and the benefit of US Provisional Application No. 63 / 755299, filed February 7, 2025, the contents of which are hereby incorporated by reference in their entirety.FIELD

[0002] Various example embodiments generally relate to the field of communication, and in particular, to terminal devices, network devices, methods, apparatuses and computer readable storage media related to switching of carriers under frequency division duplex-supplementary downlink (FDD-SDL) carrier aggregation (CA).BACKGROUND

[0003] A communication network can be seen as a facility that enables communications between two or more communication devices, or provides communication devices access to a data network. A mobile or wireless communication network is one example of a communication network.

[0004] Such communication networks operate in accordance with standards, such as those promulgated by 3GPP (Third Generation Partnership Project) or ETSI (European Telecommunications Standards Institute). Examples of such standards include the so-called 5G (5th Generation) standard or other standards promulgated by 3GPP.SUMMARY

[0005] In general, example embodiments of the present disclosure provide terminal devices, network devices, methods, apparatuses and computer readable storage media for communication, for example, for operations under FDD-SDL CA, especially for switching of carriers under FDD-SDL CA.

[0006] In a first aspect, there is provided a terminal device. The terminal device may comprise at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the terminal device at least to: obtain first information for switching of carriers in frequency division duplex-supplementary downlink (FDD-SDL) carrier aggregation (CA), the carriers at least comprise an FDD carrier and an SDL carrier.

[0007] In a second aspect, there is provided a network device. The network device may comprise at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the network device at least to: obtain first information for switching of carriers in frequency division duplex-supplementary downlink (FDD-SDL) carrier aggregation (CA), the carriers at least comprise an FDD carrier and an SDL carrier.

[0008] In a third aspect, there is provided a method for a terminal device. The method may comprise: obtaining first information for switching of carriers in frequency division duplex-supplementary downlink (FDD-SDL) carrier aggregation (CA), the carriers at least comprise an FDD carrier and an SDL carrier.

[0009] In a fourth aspect, there is provided a method for a network device. The method may comprise: obtaining first information for switching of carriers in frequency division duplex-supplementary downlink (FDD-SDL) carrier aggregation (CA), the carriers at least comprise an FDD carrier and an SDL carrier.

[0010] In a fifth aspect, there is provided an apparatus for a terminal device. The apparatus may comprise: means for obtaining first information for switching of carriers in frequency division duplex-supplementary downlink (FDD-SDL) carrier aggregation (CA), the carriers at least comprise an FDD carrier and an SDL carrier.

[0011] In a sixth aspect, there is provided an apparatus for a network device. The apparatus may comprise: means for obtaining first information for switching of carriers in frequency division duplex-supplementary downlink (FDD-SDL) carrier aggregation (CA), the carriers at least comprise an FDD carrier and an SDL carrier.

[0012] In a seventh aspect, there is provided a non-transitory computer readable medium comprising program instructions for causing an apparatus to perform at least the method according to the third or fourth aspect.

[0013] In an eighth aspect, there is provided a computer program comprising instructions, which, when executed by a terminal device, cause the terminal device at least to: obtain first information for switching of carriers in frequency division duplex-supplementary downlink (FDD-SDL) carrier aggregation (CA), the carriers at least comprise an FDD carrier and an SDL carrier.

[0014] In a ninth aspect, there is provided a computer program comprising instructions, which, when executed by a network device, cause the network device at least to: obtain first information for switching of carriers in frequency division duplex-supplementary downlink (FDD-SDL) carrier aggregation (CA), the carriers at least comprise an FDD carrier and an SDL carrier.

[0015] In a tenth aspect, there is provided a terminal device. The terminal device may comprise: an obtaining circuitry configured to obtain first information for switching of carriers in frequency division duplex-supplementary downlink (FDD-SDL) carrier aggregation (CA), the carriers at least comprise an FDD carrier and an SDL carrier.

[0016] In an eleventh aspect, there is provided a network device. The network device may comprise: an obtaining circuitry configured to obtain first information for switching of carriers in frequency division duplex-supplementary downlink (FDD-SDL) carrier aggregation (CA), the carriers at least comprise an FDD carrier and an SDL carrier.

[0017] It is to be understood that the summary section is not intended to identify key or essential features of embodiments of the present disclosure, nor is it intended to be used to limit the scope of the presentdisclosure. Other features of the present disclosure will become easily comprehensible through the following description.BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Some example embodiments will now be described with reference to the accompanying drawings, in which:

[0019] FIG. 1 illustrates an example of an application scenario in which some example embodiments of the present disclosure may be implemented;

[0020] FIG. 2 illustrates an example signaling process for obtaining information for switching of carriers by a terminal device and a network device to adapt for operations under FDD-SDL CA according to some embodiments of the present disclosure;

[0021] FIG. 3A illustrates an example diagram for switching between Case 1 in which there is uplink transmission and downlink reception on n12 band but no downlink reception on n29 band and Case 2 in which there is downlink reception on n29 band but no uplink transmission and downlink reception on n12 band according to some embodiments of the present disclosure;

[0022] FIG. 3B illustrates an example diagram for switching between Case 1 in which there is uplink transmission and downlink reception on n12 band but no downlink reception on n29 band and Case A in which there are downlink receptions on n12 band and n29 band but no uplink transmission on n12 band according to some embodiments of the present disclosure;

[0023] FIG. 4 illustrates an example signaling process for obtaining information for switching of carriers by a UE and a gNB to adapt for operations under FDD-SDL CA according to some embodiments of the present disclosure;

[0024] FIG. 5A illustrates an example diagram for switching between Case 1 in which there is uplink transmission and downlink reception on n12 band but no downlink reception on n29 band and Case 2 in which there is downlink reception on n29 band but no uplink transmission and downlink reception on n12 band using three local oscillators, and LOs are kept at fixed frequency locations according to some embodiments of the present disclosure;

[0025] FIG. 5B illustrates an example diagram for switching between Case 1 in which there is uplink transmission and downlink reception on n12 band but no downlink reception on n29 band and Case 2 in which there is downlink reception on n29 band but no uplink transmission and downlink reception on n12 band using two local oscillators, and switching the location of the Rx LO according to some embodiments of the present disclosure;

[0026] FIG. 5C illustrates an example diagram for switching between Case 1 in which there is uplink transmission and downlink reception on n12 band but no downlink reception on n29 band and Case A in which there are downlink receptions on n12 band and n29 band but no uplink transmission on n12 bandusing three local oscillators, and LOs are kept at fixed frequency locations according to some embodiments of the present disclosure;

[0027] FIG. 6 illustrates an example block diagram of a configuration state of a fully separated radio frequency (RF) architecture of a terminal device used under FDD-SDL CA according to some embodiments of the present disclosure;

[0028] FIG. 7 illustrates an example block diagram of a configuration state of a partially shared RF architecture of a terminal device used under FDD-SDL CA according to some embodiments of the present disclosure;

[0029] FIG. 8 illustrates an example block diagram of a configuration state of a fully separated radio frequency (RF) architecture of a terminal device used under FDD-SDL CA according to some other embodiments of the present disclosure;

[0030] FIG. 9 illustrates an example diagram of interferences when the terminal device uses one receiving chain for downlink receptions on n12 band and n29 band according to some embodiments of the present disclosure;

[0031] FIG. 10 illustrates an example diagram for switching between Case 1 in which there is uplink transmission and downlink reception on n12 band but no downlink reception on n29 band and Case C in which there are downlink receptions on n12 band and n29 band but no uplink transmission on n12 band using three local oscillators, and LOs are kept at fixed frequency locations according to some embodiments of the present disclosure;

[0032] FIG. 11 illustrates an example block diagram of a configuration state of a fully shared RF architecture of a terminal device used under FDD-SDL CA according to some other embodiments of the present disclosure;

[0033] FIG. 12 illustrates an example diagram for switching between Case 1 in which there is uplink transmission and downlink reception on n12 band but no downlink reception on n29 band and Case B in which there are downlink receptions on n12 band and n29 band but no uplink transmission on n12 band using two local oscillators, and switching the location of the Tx LO according to some embodiments of the present disclosure;

[0034] FIG. 13 illustrates an example diagram for switching between Case 1 in which there is uplink transmission and downlink reception on n12 band but no downlink reception on n29 band and Case C in which there are downlink receptions on n12 band and n29 band but no uplink transmission on n12 band using two local oscillators, and switching the location of the Rx LO according to some embodiments of the present disclosure;

[0035] FIG. 14 illustrates an example diagram for switching between Case D in which there is uplink transmission and downlink reception on n12 band and inactive downlink reception on n29 band and Case C in which there are downlink receptions on n12 band and n29 band but no uplink transmission on n12 bandusing two local oscillators, and LOs are kept at fixed frequency locations according to some embodiments of the present disclosure;

[0036] FIG. 15 illustrates a flowchart of an example method implemented at a terminal device in accordance with some embodiments of the present disclosure;

[0037] FIG. 16 illustrates a flowchart of an example method implemented at a network device in accordance with some embodiments of the present disclosure;

[0038] FIG. 17 illustrates an example simplified block diagram of a device that is suitable for implementing embodiments of the present disclosure; and

[0039] FIG. 18 illustrates an example block diagram of an example computer readable medium in accordance with some example embodiments of the present disclosure.

[0040] Throughout the drawings, the same or similar reference numerals represent the same or similar element.DETAILED DESCRIPTION

[0041] Principles of the present disclosure will now be described with reference to some example embodiments. It is to be understood that these embodiments are described only for the purpose of illustration and help those skilled in the art to understand and implement the present disclosure, without suggesting any limitation as to the scope of the disclosure. The disclosure described herein may be implemented in various manners other than the ones described below.

[0042] In the following description and claims, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skills in the art to which the present disclosure belongs.

[0043] References in the present disclosure to “one embodiment,” “an embodiment,” “an example embodiment,” and the like indicate that the embodiment described may include a particular feature, structure, or characteristic, but it is not necessary that every embodiment includes the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.

[0044] It may be understood that although the terms “first”, “second”, “third” etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and similarly, a second element could be termed a first element, without departing from the scope of example embodiments. As used herein, the term “and / or” includes any and all combinations of one or more of the listed terms.

[0045] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises”, “comprising”, “has”, “having”, “includes” and / or “including”, when used herein, specify the presence of stated features, elements, and / or components etc., but do not preclude the presence or addition of one or more other features, elements, components and / or combinations thereof. As used herein, “at least one of the following: ” and “at least one of ” and similar wording, where the list of two or more elements are joined by “and” or “or”, mean at least any one of the elements, or at least any two or more of the elements, or at least all the elements.

[0046] As used in this application, the term “circuitry” may refer to one or more or all of the following:(a) hardware-only circuit implementations (such as implementations in only analog and / or digital circuitry) and(b) combinations of hardware circuits and software, such as (as applicable):(i) a combination of analog and / or digital hardware circuit(s) with software / firmware and (ii) any portions of hardware processor(s) with software (including digital signal processor(s)), software, and memory(ies) that work together to cause an apparatus, such as a mobile phone or server, to perform various functions) and(c) hardware circuit(s) and or processor(s), such as a microprocessor(s) or a portion of a microprocessor(s) that requires software (e.g., firmware) for operation, but the software may not be present when it is not needed for operation.

[0047] This definition of circuitry applies to all uses of this term in this application, including in any claims. As a further example, as used in this application, the term circuitry also covers an implementation of merely a hardware circuit or processor (or multiple processors) or portion of a hardware circuit or processor and its (or their) accompanying software and / or firmware. The term circuitry also covers, for example and if applicable to the particular claim element, a baseband integrated circuit or processor integrated circuit for a mobile device or a similar integrated circuit in server, a cellular network device, or other computing or network device.

[0048] As used herein, the term “communication network” refers to a network following any suitable communication standards, such as new radio (NR), long term evolution (LTE), LTE-advanced (LTE-A), wideband code division multiple access (WCDMA), high-speed packet access (HSPA), narrow band Internet of Things (NB-IoT) and so on. Furthermore, the communications between a terminal device and a network device in the communication network may be performed according to any suitable generation communication protocols, including, but not limited to, the third generation (3G), the fourth generation (4G), 4.5G, the fifth generation (5G) communication protocols, the sixth generation (6G) communication protocols, and / or beyond. Embodiments of the present disclosure may be applied in various communication systems. Given the rapiddevelopment in communications, there will of course also be future type communication technologies and systems with which the present disclosure may be embodied. It should not be seen as limiting the scope of the present disclosure to only the aforementioned system.

[0049] As used herein, the term “network device” refers to a node in a communication network via which a terminal device accesses the network and receives services therefrom. The network device may refer to a base station (BS) or an access point (AP), for example, a node B (NodeB or NB), an evolved NodeB (eNodeB or eNB), a NR NB (also referred to as a gNB), a transmit-receive point (TRP), a remote radio unit (RRU), a radio header (RH), a remote radio head (RRH), a relay, a low power node such as a femto, a pico, an Integrated Access and Backhaul (IAB) node, a non-terrestrial network (NTN) or non-ground network device such as a satellite network device, a low earth orbit (LEO) satellite and a geosynchronous earth orbit (GEO) satellite, an aircraft network device, and so forth, depending on the applied terminology and technology. In some example embodiments, radio access network (RAN) split architecture comprises a Centralized Unit (CU) and a Distributed Unit (DU) at an IAB donor node. An IAB node comprises a Mobile Terminal (IAB-MT) part that behaves like a UE toward the parent node, and a DU part of an IAB node behaves like a base station toward the next-hop IAB node.

[0050] The term “terminal device” refers to any end device that may be capable of wireless communication. By way of example rather than limitation, a terminal device may also be referred to as a communication device, user equipment (UE), a subscriber station (SS), a portable subscriber station, a mobile station (MS), or an access terminal (AT). The terminal device may include, but not limited to, a mobile phone, a cellular phone, a smart phone, voice over IP (VoIP) phones, wireless local loop phones, a tablet, a wearable terminal device, a personal digital assistant (PDA), portable computers, desktop computer, image capture terminal devices such as digital cameras, gaming terminal devices, music storage and playback appliances, vehiclemounted wireless terminal devices, wireless endpoints, mobile stations, laptop-embedded equipment (LEE), laptop-mounted equipment (LME), USB dongles, smart devices, wireless customer-premises equipment (CPE), an Internet of Things (IoT) device, a watch or other wearable, a head-mounted display (HMD), a vehicle, a drone, a medical device and applications (e.g., remote surgery), an industrial device and applications (e.g., a robot and / or other wireless devices operating in an industrial and / or an automated processing chain contexts), a consumer electronics device, a device operating on commercial, a relay node, an integrated access and backhaul (IAB) node, and / or industrial wireless networks, and the like. In the following description, the terms “terminal device”, “communication device”, “terminal”, “user equipment” and “UE” may be used interchangeably.

[0051] As used herein, the term “resource”, “transmission resource”, “resource block”, “physical resource block” (PRB), “uplink (UL) resource” or “downlink (DL) resource” may refer to any resource for performing a communication, for example, a communication between a terminal device and a network device, such as a resource in time domain, a resource in frequency domain, a resource in space domain, a resource in codedomain, a resource in a combination of more than one domain or any other resource enabling a communication, and the like. In the following, a resource in time domain (such as, a subframe) will be used as an example of a transmission resource for describing some example embodiments of the present disclosure. It is noted that example embodiments of the present disclosure are equally applicable to other resources in other domains.

[0052] In a communication technology, the third generation partnership project (3GPP) agreed that a terminal device needs to support inter-carrier scheduling. The UE may monitor a PCell on an FDD carrier for physical downlink control channel (PDCCH) and downlink control information (DCI), which comprises scheduling information for both FDD and SDL bands. The carrier aggregation (CA) of the FDD and SDL bands may also be called as low-low band CA. Current standardized procedures for switched operations are defined for time division duplexing (TDD) band combinations or TDD-FDD band combinations. However, standardized procedures for switched operations for FDD-SDL band combinations have not been defined yet. How to specify that an FDD-SDL band combination supports certain aspects of switched operation needs to be discussed.

[0053] Therefore, some example embodiments of the present disclosure provide a solution for switching of carriers under FDD-SDL CA. According to these embodiments of the present disclosure, a terminal device (e.g., a UE) obtains first information for switching of carriers in frequency division duplex-supplementary downlink (FDD-SDL) carrier aggregation (CA), the carriers at least comprise an FDD carrier and an SDL carrier. A network device (e.g., a gNB or a TRP) also obtains the first information for switching of carriers in FDD-SDL CA.

[0054] It is understood that the above procedure steps may work together, in a flow of operations as described below, partly together or independently of each other. By implementing these embodiments of the present disclosure, the terminal device (e.g., a UE) and the network device (e.g., a gNB or a TRP) could obtain the information for switching of carriers in the FDD-SDL CA, which contains information of certain aspects of switched operation for the FDD-SDL band combination, thereby proposing enhancements to standards that are needed to declare and support for the FDD-SDL band combination.

[0055] For illustrative purposes, principles and example embodiments of the present disclosure for switching of carriers under FDD-SDL CA will be described below with reference to FIG. 1 through FIG. 18. However, it is to be noted that these embodiments are given to enable the skilled in the art to understand inventive concepts of the present disclosure and implement the solution as proposed herein, and not intended to limit scope of the present application in any way.

[0056] FIG. 1 illustrates an example of an application scenario 100 in which some example embodiments of the present disclosure may be implemented. The communication system 100, which may be a part of a communication network, includes a terminal device 102 and a network device 104.

[0057] As illustrated in FIG. 1, the terminal device 102 may also be referred to as a user equipment 102or a UE 102. The network device 104 may also be referred to as a gNB 104. The network device 104 can provide services to the terminal device 102, and the network device 104 and the terminal device 102 may communicate data and control information with each other. In some embodiments, the network device 104 and the terminal device 102 may communicate with direct links / channels.

[0058] In the communication system 100, a link from the network device 104 to the terminal device 102 is referred to as a downlink (DL), while a link from the terminal device 102 to the network device 104 is referred to as an uplink (UL). In downlink, the network device 104 is a transmitting (TX) device (or a transmitter) and the terminal device 102 is a receiving (RX) device (or a receiver). In uplink, the terminal device 102 is a transmitting (TX) device (or a transmitter) and the network device 104 is a RX device (or a receiver).

[0059] The communications in the communication system 100 may conform to any suitable standards including, but not limited to, Long Term Evolution (LTE), LTE-Evolution, LTE-Advanced (LTE-A), Wideband Code Division Multiple Access (WCDMA), Code Division Multiple Access (CDMA) and Global System for Mobile Communications (GSM), Wireless Fidelity (Wi-Fi) and the like. Furthermore, the communications may be performed according to any generation communication protocols either currently known or to be developed in the future. Examples of the communication protocols include, but not limited to, the first generation (1G), the second generation (2G), 2.5G, 2.75G, the third generation (3G), the fourth generation (4G), 4.5G, the fifth generation (5G), 5.5G, 5G-Advanced networks, the sixth generation (6G), or IEEE 802.11 communication protocols.

[0060] The terminal device 102 and the network device 104 may operate under the FDD-SDL CA scenario, in which at least an FDD carrier and an SDL carrier are aggregated as shown in FIG. 1. The FDD carrier may be a frequency duplex carrier which can be used as both an uplink and a downlink. The SDL carrier may be a one-way carrier which can only be used as a downlink. For example, the FDD carrier may be of 5G band n5, n12, n13, n14, n20, n28 or n71, and the SDL carrier may be of 5G band n29 or n67. The terminal device 102 could transmit its capability information to the network device 104. The FDD carrier and the SDL carrier may be activated concurrently or non-concurrently.

[0061] It is to be understood that the number of devices and their connection relationships and types shown in FIG. 1 are for illustrative purposes only without suggesting any limitation. The communication system 100 may comprise any suitable number of devices adapted for implementing embodiments of the present disclosure.

[0062] FIG. 2 illustrates an example signaling process 200 for obtaining information for switching of carriers by a terminal device 202 and a network device 204 to adapt for operations under FDD-SDL CA according to some embodiments of the present disclosure. The terminal device 202 may refer to the terminal device 102 in FIG. 1, and the network device 204 may refer to the network device 104 in FIG. 1.

[0063] At 210a, the terminal device 202 may obtain first information for switching of carriers in frequency division duplex-supplementary downlink (FDD-SDL) carrier aggregation (CA). The carriers at least comprisean FDD carrier and an SDL carrier. At another side, at 210b, the network device 204 may also obtain the first information for switching of carriers in FDD-SDL CA. In some example embodiments, the FDD carrier and the SDL carrier may be adjacent or overlapping to each other in the frequency domain. The FDD carrier may be of 5G band n5, n12, n13, n14, n20, n28 or n71, and the SDL carrier may be of 5G band n29 or n67. Correspondingly, the low-low band combination (i.e., FDD-SDL band combinations) may be CA_n5-n29, CA_n12-n29, CA_n13-n29, CA_n14-n29, CA_n20-n67, CA_n28-n67 or CA_n29-n71.

[0064] In some example embodiments, the first information may indicate the SDL carrier cannot be switched on concurrently with downlink operations on the FDD carrier. Alternatively or additionally, the FDD carrier may be regarded as a half-duplex FDD (HD-FDD) carrier, and the first information may indicate uplink operations on the FDD carrier and downlink operations on the SDL carrier cannot occur concurrently. Under these embodiments, the terminal device 202 may periodically switch off uplink transmission on the FDD carrier to adapt for activation of downlink reception on the SDL carrier. At another side, the network device 204 may periodically switch off uplink reception on the FDD carrier to adapt for activation of downlink transmission on the SDL carrier. That is to say, the FDD carrier may be half-duplex in operation. In other words, when there are uplink operations on the FDD carrier, there may be no downlink operation on the FDD carrier. In this way, the non-concurrent CA capability applies for the inter-band FDD-SDL carrier aggregation, thus operations are restricted to non-concurrent activity, which may follow transmission time interval (TTI) level switching for allowing Tx operations to be periodically switched off to adapt for Scell activation. An example of these embodiments will be described with reference to FIG. 3A.

[0065] FIG. 3A illustrates an example diagram 300Afor switching between Case 1 in which there is uplink transmission and downlink reception on n12 band but no downlink reception on n29 band and Case 2 in which there is downlink reception on n29 band but no uplink transmission and downlink reception on n12 band according to some embodiments of the present disclosure. As shown in FIG. 3A, the FDD carrier 1 refers to n12 band and the SDL carrier 2 refers to n29 band. The terminal device 202 may have two or three LOs forTx / Rx on the n12 and n29 bands. In Case 1, there is uplink transmission and downlink reception on the n12 band but no downlink reception on the n29 band, the n12 band is switched on but the n29 band is switched off, and in Case 2, there is downlink reception on the n29 band but no uplink transmission or downlink reception on the n12 band, the n29 band is switched on but the n12 band is switched off. As can be seen, the n29 band is not switched on concurrently with n12 Rx on the FDD carrier, and n12 Tx on the n12 band and n29 Rx on the n29 band do not occur concurrently. The terminal device 202 may switch from Case 1 to Case 2 or vice versa. The support and requirements of switching of carriers and operations between Case 1 and Case 2 for the band combination of n12 and n29 bands may be specified in standard specifications, which may be shown as italic in the text box below.5.2A.2 Inter-band CANR inter-band carrier aggregation is designed to operate in the operating bands defined in Table 5.2A.2.1-1, Table 5.2A.2.2-1, Table 5.2A.2.3-1, Table 5.2A.2.4-1 and Table 5.2A.2.5-1, where all operating bands are within FR1.If the mandatory simultaneous Rx / Tx capability applies for a lower order band combination, when the applicable lower order band combination is a band pair in a higher order band combination, the mandatory simultaneous Rx / Tx capability also applies for the band pair in the higher order band combination.If the non-concurrent CA capability applies for the inter-band carrier aggregation, the operation may be restricted to non-concurrent activity, which must follow TTI level switching for allowing the Tx operation to be periodically switched off to adapt Scell activation.5.2A.2.1 Inter-band CA (two bands)Table 5.2A.2.1-1: Inter-band CA operating bands involving FR1 (two bands)NR CA Band NR Band (Table 5.2-1) DL interruption allowed (Note8)CA_n1-n3 n1, n3***************TQ|^|00ntn0S loft Qut************CA n12-n2921 22n12, n29***************"1" g | Q Isft out************CA_n78-n104 n78, n104CA_n78-n105 n78, n105NOTE 21: The combination is only applicable for FDD-SDL with the SDL band supported through non-concurrent CA operation. The CA operation follows the TTI level switching in accordance with 38.133 section 8.x.x.x

[0013] NOTE 22: FDD band operates as HD-FDD. When FDD is transmitting SDL band is not receiving.

[0066] Alternatively, the “DL Interruption allowed (Note 8)” column in the above text box may be renamed to simply state “Interruption allowed” and be used to state NOTE 21 and NOTE 22, which may be shown as italic in the text box below. It is noted that the names and numbers of NOTE 21, NOTE 22 and “Interruption allowed” are for illustrative purposes only without suggesting any limitation.5.2A.2 Inter-band CANR inter-band carrier aggregation is designed to operate in the operating bands defined in Table 5.2A.2.1-1, Table 5.2A.2.2-1, Table 5.2A.2.3-1, Table 5.2A.2.4-1 and Table 5.2A.2.5-1, where all operating bands are within FR1.If the mandatory simultaneous Rx / Tx capability applies for a lower order band combination, when the applicable lower order band combination is a band pair in a higher order band combination, the mandatory simultaneous Rx / Tx capability also applies for the band pair in the higher order band combination.If the non-concurrent CA capability applies for the inter-band carrier aggregation, the operation may be restricted to non-concurrent activity, which must follow TTI level switching for allowing the Tx operation to be periodically switched off to adapt Scell activation.5.2A.2.1 Inter-band CA (two bands)Table 5.2A.2.1-1: Inter-band CA operating bands involving FR1 (two bands)NR CA Band NR Band (Table 5.2-1) Interruption allowed CA_n1-n3 n1, n3***************TQ|^|00ntn0S loft Qut************CA_n12-n29 n12, n29 NOTE 21, 22***************"1" g | Q l^ft out************CA_n78-n104 n78, n104CA_n78-n105 n78, n105NOTE 21: The combination is only applicable for FDD-SDL with the SDL band supported through non-concurrent CA operation. The CA operation follows the TTI level switching in accordance with 38.133 section 8.x.x.x

[0013] NOTE 22: FDD band operates as HD-FDD. When FDD is transmitting SDL band is not receiving.

[0067] Alternatively or additionally, the first information may indicate the SDL carrier can be switched on concurrently with downlink operations on the FDD carrier. Under these embodiments, the terminal device 202 may periodically switch off uplink transmission on the FDD carrier to adapt for activation of downlink reception on both the FDD carrier and the SDL carrier. At another side, the network device 204 may periodically switch off uplink reception on the FDD carrier to adapt for activation of downlink transmission on both the FDD carrier and the SDL carrier. In this way, the concurrent CA capability applies for the inter-bandFDD-SDL carrier aggregation, thus operations are restricted to concurrent activity in the DL CA combination only, which may follow TTI level switching for allowing Tx operations to be periodically switched off to adapt for both DL cells activation. An example of these embodiments will be described with reference to FIG. 3B.

[0068] FIG. 3B illustrates an example diagram 300B for switching between Case 1 in which there is uplink transmission and downlink reception on n12 band but no downlink reception on n29 band and Case A in which there are downlink receptions on n12 band and n29 band but no uplink transmission on n12 band according to some embodiments of the present disclosure. As shown in FIG. 3B, the FDD carrier 1 refers to n12 band and the SDL carrier 2 refers to n29 band. The terminal device 202 may have two or three LOs for Tx / Rx on the n12 and n29 bands. In Case 1, there is uplink transmission and downlink reception on the n12 band but no downlink reception on the n29 band, the n12 band is switched on but the n29 band is switched off, and in Case A, there are downlink receptions on the n12 band and the n29 band but no uplink transmission on the n12 band, both the n12 band and the n29 band are switched on. As can be seen, the n29 band is switched on concurrently with n12 Rx on the FDD carrier. The terminal device 202 may switch from Case 1 to Case A or vice versa. The support and requirements of switching of carriers and operations between Case 1 and Case A for the band combination of n12 and n29 bands may be specified in standard specifications, which may be shown as italic in the text box below.5.2A.2 Inter-band CANR inter-band carrier aggregation is designed to operate in the operating bands defined in Table 5.2A.2.1-1, Table 5.2A.2.2-1, Table 5.2A.2.3-1, Table 5.2A.2.4-1 and Table 5.2A.2.5-1, where all operating bands are within FR1.If the mandatory simultaneous Rx / Tx capability applies for a lower order band combination, when the applicable lower order band combination is a band pair in a higher order band combination, the mandatory simultaneous Rx / Tx capability also applies for the band pair in the higher order band combination.If the non-concurrent CA capability applies for the inter-band carrier aggregation, the operation may be restricted to non-concurrent activity, which must follow TTI level switching for allowing the Tx operation to be periodically switched off to adapt Scell activation.If the concurrent CA capability applies for the inter-band carrier aggregation, the operation may be restricted to concurrent activity in the DL CA combination only, which must follow TTI level switching for allowing the Tx operation to be periodically switched off to adapt both DL cells activation.5.2A.2.1 Inter-band CA (two bands)Table 5.2A.2.1-1: Inter-band CA operating bands involving FR1 (two bands)NR CA Band NR Band (Table 5.2-1) DL interruption allowed(Note 8)CA_n1-n3 n1, n3*************** Q|^| 0ntn0S loft Qu ************CA_n12-n2921 22n12, n29 CA_n12-n2923n12, n29***************TQ|^|00pt|’j0S loft Q[jt************ CA_n78-n104 n78, n104CA_n78-n105 n78, n105NOTE 23: The combination is only applicable for FDD-SDL with the SDL band supported through concurrent CA DL operation. The uplink operation follows the TTI level switching in accordance with 38.133 section 8.x.x.x

[0013]

[0069] Alternatively, the “DL Interruption allowed (Note 8)” column in the above text box may be renamed to simply state “Interruption allowed” and be used to state NOTE 23, which may be shown as italic in the text box below. It is noted that the names and numbers of NOTE 23 and “Interruption allowed” are for illustrative purposes only without suggesting any limitation.5.2A.2 Inter-band CANR inter-band carrier aggregation is designed to operate in the operating bands defined in Table 5.2A.2.1-1, Table 5.2A.2.2-1, Table 5.2A.2.3-1, Table 5.2A.2.4-1 and Table 5.2A.2.5-1, where all operating bands are within FR1.If the mandatory simultaneous Rx / Tx capability applies for a lower order band combination, when the applicable lower order band combination is a band pair in a higher order band combination, the mandatory simultaneous Rx / Tx capability also applies for the band pair in the higher order band combination.If the non-concurrent CA capability applies for the inter-band carrier aggregation, the operation may be restricted to non-concurrent activity, which must follow TTI level switching for allowing the Tx operation to be periodically switched off to adapt Scell activation.If the concurrent CA capability applies for the inter-band carrier aggregation, the operation may be restricted to concurrent activity in the DL CA combination only, which must follow TTI level switching for allowing the Tx operation to be periodically switched off to adapt both DL cellsactivation.5.2A.2.1 Inter-band CA (two bands)Table 5.2A.2.1-1: Inter-band CA operating bands involving FR1 (two bands)NR CA Band NR Band (Table 5.2-1) interruption allowed CA_n1-n3 n1, n3*************** Q|^| 0ntn0S loft Qu ************CA_n12-n29 n12, n29 NOTE 21, 22CA_n12-n29 n12, n29 NOTE 23***************TQ|^|00pt|’j0S loft Q[jt************CA_n78-n104 n78, n104CA_n78-n105 n78, n105NOTE 23: The combination is only applicable for FDD-SDL with the SDL band supported through concurrent CA DL operation. The uplink operation follows the TTI level switching in accordance with 38.133 section 8.x.x.x

[0013]

[0070] Referring back to FIG. 2, at 220, the terminal device 202 may transmit, to the network device 204 capability information of the terminal device 202. At the same time, in a reverse direction, the network device 204 may receive, from a terminal device 202, capability information of the terminal device 202. The capability information may comprise information of one or more interruption time lengths supported by the terminal device 202 for switching between two modes under FDD-SDL CA. The two modes may comprise a first mode and a second mode. The first mode may refer to a mode in which there is no downlink reception on the SDL carrier, and the second mode may refer to a mode in which there is downlink reception on the SDL carrier. Further, the first mode may refer to a mode in which there is uplink transmission and downlink reception on the FDD carrier and no downlink reception on the SDL carrier (also called as an FDD(ULZDL) mode), and the second mode may refer to a mode in which there are downlink receptions on the FDD carrier and the SDL carrier (also called as an FDD(DL)-SDL mode). In this way, the configurations of designs of the terminal device 202 could be synchronized between the terminal device 202 and the network device 204, the network device 204 could know the implementations of the terminal device 202 based on the received capability information of the terminal device 202, and simultaneous downlink receptions on both the FDD carrier and the SDL carrier under FDD-SDL CAcan be achieved.

[0071] In some example embodiments, the information of one or more interruption time lengths may comprise one or more time values. Alternatively or additionally, the information of one or more interruptiontime lengths may comprise an indication of one or more table entries, the one or more table entries are from one or more interruption time length tables, the one or more interruption time lengths may be associated with at least one of the following: one or more architectures of the terminal device 202; one or more numbers of local oscillators used by the terminal device 202; or one or more filter settings used by the terminal device 202. Different interruption time lengths may implicitly reflect different UE implementations, such as different RF architectures, different numbers of LOs, and / or different bandpass filter settings. For example, different interruption time lengths may correspond to different numbers of LOs, such as two or three LOs, etc. The one or more table entries or interruption time length tables may be defined in the standards, such as Tables 1 and 2 as below. In this way, the interruption time lengths could be represented by specific values or table entries.Table 1NR Slot length Interruption length X (slots)A(ms) Sync Async0 1 1 21 0.5 1 22 0.25 33 0.125 5Table 2NR Slot length Uplink Tx switching period (symbols)A(ms) 35us 140us0 1 2 31 0.5 3 62 0.25 4 10

[0072] In some example embodiments, the capability information may further comprise an indication indicating whether the terminal device 202 supports switching between different interruption time lengths based on scheduling of the SDL carrier. Alternatively or additionally, the capability information may further comprise an indication indicating whether the terminal device 202 supports switching between different interruption time lengths based on a fixed scheme. The fixed scheme may comprise a semi-static switching pattern configured by a radio resource control (RRC) signaling from the network device 204. Alternatively or additionally, the capability information may further comprise an indication indicating whether the terminal device 202 supports switching between different interruption time lengths based on a timer. In this way, the capability of the terminal device 202 for switching between different interruption time lengths dynamically or in a fixed way could be notified to the network device 204.

[0073] Still referring to FIG. 2, at 230, the terminal device 202 may receive, from the network device 204, configuration information. At the same time, in a reverse direction, the network device 204 may transmit, to the terminal device 202, the configuration information. The configuration information may be carried by a RRC Reconfiguration message from the network device 204. The configuration information may comprise information for configuring the FDD carrier and the SDL carrier, such that the FDD-SDL CA connections would be established.

[0074] In some example embodiments, the configuration information may further comprise information of one or more interruption time lengths to be used by the terminal device 202. For one example, the configuration information may comprise information of an interruption time length corresponding to two LOs, then the terminal device 202 would know two LOs are to be used. For another example, the configuration information may comprise information of an interruption time length corresponding to three LOs, then the terminal device 202 would know three LOs are to be used. Alternatively or additionally, the configuration information may further comprise an indication indicating the terminal device 202 to switch between different interruption time lengths based on one of the following: scheduling of the SDL carrier, a fixed scheme, or a timer. In this way, the terminal device 202 could be indicated to switch between different configurations. For example, the configuration information may comprise an indication indicating the terminal device 202 to switch between two interruption time lengths, which correspond to two or three LOs, based on scheduling of the SDL carrier. Then, if there is no scheduling of the SDL carrier, the terminal device 202 would switch to use two LOs, otherwise, the terminal device 202 would switch to use three LOs. In this way, more LOs could be used when there is scheduling of the SDL carrier so as to save the time for settling the LO, and less LOs could be used when there is no scheduling of the SDL carrier so as to save power cost.

[0075] In some example embodiments, the terminal device 202 may receive, via a downlink control information (DCI) or medium access control (MAC) message from the network device 204, an indication indicating the terminal device 202 to switch between different interruption time lengths based on scheduling of the SDL carrier. At the same time, in a reverse direction, the network device 204 may transmit, via a downlink control information (DCI) or medium access control (MAC) message to the terminal device 202, an indication indicating the terminal device 202 to switch between different interruption time lengths based on scheduling of the SDL carrier. In this way, the switch indication could be transmitted via the explicit low layer signaling.

[0076] In some example embodiments, the one or more interruption time lengths may comprise a first interruption time length corresponding to the terminal device 202 using two local oscillators, and a second interruption time length corresponding to the terminal device 202 using three local oscillators. The terminal device 202 may determine to use two or three local oscillators based on scheduling of the SDL carrier. For example, the terminal device 202 may determine to use two local oscillators when scheduling of the SDL carrier is not detected for a predetermined period (e.g., predetermined times of monitoring occasions).Alternatively or additionally, the terminal device 202 may determine to use three local oscillators when scheduling of the SDL carrier is detected.

[0077] FIG. 4 illustrates an example signaling process for obtaining information for switching of carriers by a UE (for example, a UE 402) and a gNB (for example, a TRP 404 or a gNB 404) to adapt for operations under FDD-SDL CA according to some embodiments of the present disclosure. The UE 402 may refer to the terminal device 102 in FIG. 1 or the terminal device 202 in FIG. 2, and the gNB 404 may refer to the network device 104 in FIG. 1 or the network device 204 in FIG. 2.

[0078] At 410a, the UE 402 may obtain first information for switching of carriers in FDD-SDL CA. At another side, at 410b, the network device 404 may also obtain the first information for switching of carriers in FDD-SDL CA. The FDD carrier and the SDL carrier may be adjacent or overlapping to each other in the frequency domain. The first information may indicate the SDL carrier can be or cannot be switched on concurrently with downlink operations on the FDD carrier. In some example embodiments, the FDD carrier may be a halfduplex FDD (HD-FDD) carrier, and the first information may indicate uplink operations on the FDD carrier and downlink operations on the SDL carrier cannot occur concurrently.

[0079] At 420, the UE 402 transmits, to the gNB 404, UE capability information related to the FDD-SDL CA. In other words, the UE 402 shares its capabilities related to low-low band CAwith the gNB 404. The UE capability information may comprise: which of table entries are to be used as interruption time lengths supported by the UE 402; and / or whether the UE 402 supports automatic switching between different interruption time lengths based on dynamic scheduling of the SDL carrier, a fixed scheme or a timer. Different UE architectures, numbers of LOs, filter settings and so on may affect interruption time, so there may be a plurality of different interruption time lengths based on exactly which UE implementation is used. The fixed scheme may be a semi-static switching pattern configured by a radio resource control (RRC) signaling from the gNB 404. For example, the fixed scheme may be a scheme in which x slots correspond to one interruption time length and y slots correspond to another interruption time length, repeated during a whole low-low band CA connection time.

[0080] At 430, the UE 402 receives, from the gNB 404, RRCReconfiguration message. The RRCReconfiguration message may comprise information for configuring the FDD carrier and the SDL carrier for the low-low band CA. It is noted that there may be more carriers configured and used except the low-low band CA carrier pair. The RRCReconfiguration message may further comprise which of the table entries are to be used by the UE 402; and / or whether the UE 402 is allowed to automatically switch between different interruption time lengths and how to switch. For example, the RRCReconfiguration message may comprise an indication indicating the UE 402 to switch between different interruption time lengths based on dynamic scheduling of the SDL carrier, a fixed scheme or a timer.

[0081] At 440, the UE 402 transmits, to the gNB 404, a RRCReconfigurationComplete message, which confirms that the low-low band CA connection is established.

[0082] In some example embodiments, the dynamic switching between interruption time lengths may be configured via explicit signaling (e.g., the DCI or MAC message, etc.), which can directly configure the UE 402 to switch based on dynamic scheduling of the SDL carrier.

[0083] By implementing these embodiments described with reference to FIG. 4, the UE 402 and the gNB 404 could obtain the information for switching of carriers in the FDD-SDL CA, which contains information of certain aspects of switched operation for the FDD-SDL band combination, thereby proposing enhancements to standards that are needed to declare and support for the FDD-SDL band combination. In addition, the UE 402 and the gNB 404 are fully synchronized on which switch scheme is to be used and when the interruption time length is to be switched, as well as which interruption time length is to be used every time an interruption occurs.

[0084] In the following, principles and example embodiments of different operation modes / cases and configuration state of the terminal device will be described with reference to FIG. 5A through FIG. 14. However, it is to be noted that these embodiments are given to enable the skilled in the art to understand inventive concepts of the present disclosure and implement the solution as proposed herein, and not intended to limit scope of the present application in any way. It should be noted that those embodiments described with reference to FIG. 5A through FIG. 14 also apply for or could be combined with the embodiments described with reference to FIG. 1 through FIG. 4 in a replaced or mixed manner, explanations of terms with reference to FIG. 1 through FIG. 4 also apply for FIG. 5A through FIG. 14. For ease of understanding, FIG. 5A through FIG. 14 will be described from the perspective of the terminal device 202 and network device 204 with reference to FIG. 2. It is noted that the same contents apply for FIG. 5A through FIG. 14 are not repeated here for brevity.

[0085] FIG. 5A illustrates an example diagram 500Afor switching between Case 1 in which there is uplink transmission and downlink reception on n12 band but no downlink reception on n29 band and Case 2 in which there is downlink reception on n29 band but no uplink transmission and downlink reception on n12 band using three local oscillators, and LOs are kept at fixed frequency locations according to some embodiments of the present disclosure. FIG. 5A is an embodiment of the non-concurrent FDD-SDL CA operations. As shown in FIG. 5A, the FDD carrier 1 refers to n12 band and the SDL carrier 2 refers to n29 band. The terminal device 202 may have three LOs, including one Tx LO for n12 Tx, one Rx LOi for n29 Rx and one Rx LO2 for n12 Rx. In Case 1, the three LOs are all activated, and there is uplink transmission and downlink reception on the n12 band but no downlink reception on the n29 band. In Case 2, the three LOs are all activated, and there is downlink reception on the n29 band but no uplink transmission or downlink reception on the n12 band. The terminal device 202 may switch from Case 1 to Case 2 or vice versa. In this embodiment, the time for setting LO contributing to the interruption duration is reduced due to the three LOs are always activated at fixed frequencies for the associated carrier locations.

[0086] FIG. 5B illustrates an example diagram 500B for switching between Case 1 in which there is uplink transmission and downlink reception on n12 band but no downlink reception on n29 band and Case 2 in which there is downlink reception on n29 band but no uplink transmission and downlink reception on n12 band using two local oscillators, and switching the location of the Rx LO according to some embodiments of the present disclosure. FIG. 5B is another embodiment of the non-concurrent FDD-SDL CA operations. Different from FIG. 5A, the terminal device 202 may have two LOs, including one Tx LO for n12 Tx, and one Rx LO for both n29 Rx and n12 Rx. In Case 1, the two LOs are all activated, and there is uplink transmission and downlink reception on the n12 band but no downlink reception on the n29 band. In Case 2, only the Rx LO is activated, and there is only downlink reception on the n29 band. The terminal device 202 may switch from Case 1 to Case 2 or vice versa. During the switch, the Rx LO needs to be set from accommodating the n12 Rx to the n29 Rx, or vice versa. In this embodiment, the power cost consumed by LOs could be reduced since less LOs are used. It should be appreciated that it may be implementation specific if it is the Rx LO or the Tx LO that is switched for the SDL band operation. Benefits of LO settling time or power consumption may affect the decision of which LO to be switched.

[0087] FIG. 5C illustrates an example diagram 500C for switching between Case 1 in which there is uplink transmission and downlink reception on n12 band but no downlink reception on n29 band and Case A in which there are downlink receptions on n12 band and n29 band but no uplink transmission on n12 band using three local oscillators, and LOs are kept at fixed frequency locations according to some embodiments of the present disclosure. FIG. 5C is an embodiment of the concurrent FDD-SDL CA operations. Different from FIG. 5A, in Case 2, the three LOs are all activated at fixed frequencies for the associated carrier locations, and there are downlink receptions on both the n29 band and the n12 band. The terminal device 202 may switch from Case 1 to Case A or vice versa. In this embodiment, the time for setting LO contributing to the interruption duration is reduced due to the three LOs are always activated, and simultaneous downlink receptions on both the n29 band and the n12 band can be achieved.

[0088] FIG. 6 illustrates an example block diagram of a configuration state 600 of a fully separated radio frequency (RF) architecture of a terminal device 202 used under FDD-SDL CA according to some embodiments of the present disclosure. FIG. 6 shows an example implementation of the terminal device 202 used in Case A of FIG. 5C. In FIG. 6, each carrier has its own Rx RF chain through separate paths in the RF front ends, thereby using dedicated bandpass filters. Therefore, the terminal device 202 in FIG. 6 has a fully separated RF architecture. Under Case A, there are two Rx paths for n12 band and two Rx paths for n29 band, which are shown as bold paths in FIG. 6. Correspondingly, there is a n12 duplex filter and a n12 Rx bandpass filter used for the two Rx paths for n12 band, and two n29 Rx bandpass filter used for the two Rx paths for n29 band. In FIG. 6, the transmission paths of the RF transceiver are crossed out, meaning that the transmission paths are disabled in the carrier state shown at the gNB.

[0089] FIG. 7 illustrates an example block diagram of a configuration state 700 of a partially shared RF architecture of a terminal device 202 used under FDD-SDL CA according to some embodiments of the present disclosure. FIG. 7 shows another example implementation of the terminal device 202 used in Case A of FIG. 5C. In FIG. 7, the terminal device 202 uses a same wider bandpass filter in the front-end module through the n28 TX duplex path for n12+n29 Rx, while it uses a dedicated n12- 29 filter on the diversity side for n12+n29 Rx, and finally uses a split internal to the transceiver chip to separate the n12 and n29 carriers. In other words, the n12 and n29 carriers share the same Rx bandpass filter, but have separate Rx RF chains. Therefore, the terminal device 202 in FIG. 7 has a partially shared RF architecture. The implementation of FIG. 7 can save current using just one low noise amplifier (LNA) in the front-end plus diversity (FE+Div) modules, and does not need a dedicated n29 filter, thereby achieving cost optimization.

[0090] With the two different implementations of the terminal device 202 as shown in FIG. 6 and FIG. 7, the terminal device 202 is able to inform the network device 204 that it has implementations that serve for faster switching between the FDD(ULZDL) and the FDD(DL)-SDL modes.

[0091] FIG. 8 illustrates an example block diagram of a configuration state 800 of a fully separated radio frequency (RF) architecture of a terminal device 202 used under FDD-SDL CA according to some other embodiments of the present disclosure. FIG. 8 shows another example implementation of the terminal device 202 used in Case A of FIG. 5C. In FIG. 8, the n12 and n29 bands share the same Rx bandpass filter, and use the same Rx RF chain at each antenna. Therefore, the terminal device 202 in FIG. 8 has a fully shared RF architecture. The terminal device 202 with a switch for an uplink duplex side of the n28 Tx bandpass filter could switch from uplink operations on n28 band (UL n28: 703MHz - 748MHz) into downlink operations on n12 and n29 bands (DL n12: 729MHz - 746MHz, DL n29: 717MHz - 728MHz). The implementation of FIG.8 can further save current using just the same Rx RF chain for two bands, and does not need dedicated Rx RF chains, thereby further achieving cost optimization.

[0092] However, when the terminal device uses just one receive chain for Rx operations on n12 and n29 bands, interferences may occur between n29 Rx and n12 Rx. FIG. 9 illustrates an example diagram 900 of interferences when the terminal device 202 uses one receiving chain for downlink receptions on n12 band and n29 band according to some embodiments of the present disclosure. As can be seen, the n28 Tx duplex filter may not be able to separately filter n29 Rx and n12 Rx perfectly.

[0093] Corresponding to FIG. 8 and FIG. 9, FIG. 10 illustrates an example diagram 1000 for switching between Case 1 in which there is uplink transmission and downlink reception on n12 band but no downlink reception on n29 band and Case C in which there are downlink receptions on n12 band and n29 band but no uplink transmission on n12 band using three local oscillators, and LOs are kept at fixed frequency locations according to some embodiments of the present disclosure. FIG. 10 is another embodiment of the concurrent FDD-SDL CA operations. As shown in FIG. 10, the FDD carrier 1 refers to n12 band and the SDL carrier 2 refers to n29 band. The terminal device 202 may have three LOs, including one Tx LO for n12 Tx, one RxLOi for n12 Rx and one Rx LO2 for both n12 Rx and n29 Rx. In Case 1, the Tx LO and the Rx LO1 are activated, and there is uplink transmission and downlink reception on the n12 band but no downlink reception on the n29 band. In Case C, the Tx LO and the Rx LO2 are activated, and there are downlink receptions on the n29 band and n12 band but no uplink transmission on the n12 band. The terminal device 202 may switch from Case 1 to Case C or vice versa. In this embodiment, the Rx RF chains can be freed up so as to achieve cost optimization. However, the implementation of FIG. 10 may require interference management.

[0094] FIG. 11 illustrates an example block diagram of a configuration state 1100 of a fully shared RF architecture of a terminal device 202 used under FDD-SDL CA according to some other embodiments of the present disclosure. FIG. 11 may be an example implementation corresponding to the FDD(UL / DL) mode and Case 1 in FIG. 10. In FIG. 11, the transmission paths with the Tx LO and the reception paths with the Rx LO1 are enabled, but the reception paths with the Rx LO2 are disabled. Therefore, there is uplink transmission and downlink reception on the n12 band but no downlink reception on the n29 band. In this way, it provides an implementation for the terminal device 202 which the terminal device 202 is capable to configure to use.

[0095] FIG. 12 illustrates an example diagram 1200 for switching between Case 1 in which there is uplink transmission and downlink reception on n12 band but no downlink reception on n29 band and Case B in which there are downlink receptions on n12 band and n29 band but no uplink transmission on n12 band using two local oscillators, and switching the location of the Tx LO according to some embodiments of the present disclosure. FIG. 12 is still another embodiment of the concurrent FDD-SDL CA operations. As shown in FIG. 12, the terminal device 202 may have two LOs, including one Tx LO for both n12 Tx and n 29 Rx, and one Rx LO for n12 Rx. In Case 1, the two LOs are activated, and there is uplink transmission and downlink reception on the n12 band but no downlink reception on the n29 band. In Case B, the two LOs are all activated, and there are downlink receptions on the n29 band and n12 band but no uplink transmission on the n12 band. The terminal device 202 may switch from Case 1 to Case B or vice versa. When switching from Case 1 to Case B, the Tx LO needs to be switched from n12 Tx band to n29 Rx band. Thus, an interruption time length is needed for retuning the Tx LO of the terminal device 202 to settle in the Rx n29 band. Similarly, when switching from Case B to Case 1, an interruption time length is also needed for retuning the Tx LO of the terminal device 202 to settle in the Tx n12 band. It is noted that no interruption is needed on for Rx LO used for Rx n12 band.

[0096] FIG. 13 illustrates an example diagram 1300 for switching between Case 1 in which there is uplink transmission and downlink reception on n12 band but no downlink reception on n29 band and Case C in which there are downlink receptions on n12 band and n29 band but no uplink transmission on n12 band using two local oscillators, and switching the location of the Rx LO according to some embodiments of the present disclosure. FIG. 13 is still another embodiment of the concurrent FDD-SDL CA operations. In FIG.13, the n12 and n29 bands share the same Rx bandpass filter, and use the same Rx RF chain at each antenna similar to FIG. 8 and FIG. 10. The main difference between FIG. 13 and FIG. 10 is that the terminaldevice 202 uses two local oscillators when switching modes in FIG. 13. The terminal device 202 may have two LOs, including one Tx LO for n12 Tx, and one Rx LO for both n12 Rx and n29 Rx. In Case 1, the Tx LO and the Rx LO are activated, and there is uplink transmission and downlink reception on the n12 band but no downlink reception on the n29 band. In Case C, only the Rx LO is shifted in frequency, and there are downlink receptions on the n29 band and n12 band but no uplink transmission on the n12 band. The terminal device 202 may switch from Case 1 to Case C or vice versa. In Case C, the n12 Rx and n29 Rx may be switched to pass through the n28 Tx duplex filter. As an interruption requirement for this configuration, the terminal device 202 needs time to shift the frequency of the Rx LO, which may correspond to a specific interruption time length.

[0097] If the terminal device 202 uses a different implementation of Rx LO management, it may keep the placement of the Rx LO during both switched cases as shown in FIG. 14. FIG. 14 illustrates an example diagram 1400 for switching between Case D in which there is uplink transmission and downlink reception on n12 band and inactive downlink reception on n29 band and Case C in which there are downlink receptions on n12 band and n29 band but no uplink transmission on n12 band using two local oscillators, and LOs are kept at fixed frequency locations according to some embodiments of the present disclosure. FIG. 14 is still another embodiment of the concurrent FDD-SDL CA operations. As shown in FIG. 14, even though the terminal device 202 still has two LOs similar as FIG.13, the time for shifting the frequency of the Rx LO would not be present. This embodiment provides an interruption-less implementation for simultaneous downlink receptions of the FDD-SDL combination and the Rx RF chains can be freed up so as to achieve cost optimization, but may require interference management.

[0098] By implementing these embodiments described with reference to FIG. 5A through FIG. 14, a plurality of UE implementations considering the RF architecture, the number of LOs and bandpass filter implementation for simultaneous downlink receptions on both the FDD carrier and the SDL carrier are provided. These embodiments support all kinds of receiver architectures, including the fully separated RF architecture, the partially shared RF architecture and fully shared RF architecture. These embodiments also support using different numbers of LOs, such as two or three LOs. These embodiments also support different bandpass filter implementation, including separated bandpass filters for the FDD and SDL carrier, and combined bandpass filters for the FDD and SDL carrier. Consequently, different UE implementations correspond to different interruption time, thus the interruption time length can reflect various UE implementations.

[0099] FIG. 15 illustrates a flowchart of an example method 1500 implemented at a terminal device (for example, a terminal device 102 or 202, or a UE 402) in accordance with some embodiments of the present disclosure. For ease of understanding, the method 1500 will be described from the perspective of the terminal device 202 with reference to FIG. 2.

[0100] At block 1510, the terminal device 202 obtains first information for switching of carriers in frequency division duplex-supplementary downlink (FDD-SDL) carrier aggregation (CA), the carriers at least comprise an FDD carrier and an SDL carrier.

[0101] In some example embodiments, the first information indicates the SDL carrier cannot be switched on concurrently with downlink operations on the FDD carrier.

[0102] In some example embodiments, the FDD carrier is a half-duplex FDD (HD-FDD) carrier, and the first information indicates uplink operations on the FDD carrier and downlink operations on the SDL carrier cannot occur concurrently.

[0103] In some example embodiments, the terminal device 202 is further caused to: periodically switch off uplink transmission on the FDD carrier to adapt for activation of downlink reception on the SDL carrier.

[0104] In some example embodiments, the first information indicates the SDL carrier can be switched on concurrently with downlink operations on the FDD carrier.

[0105] In some example embodiments, the terminal device 202 is further caused to: periodically switch off uplink transmission on the FDD carrier to adapt for activation of downlink reception on both the FDD carrier and the SDL carrier.

[0106] In some example embodiments, the FDD carrier and the SDL carrier are adjacent or overlapping to each other in the frequency domain.

[0107] In some example embodiments, the terminal device 202 is further caused to: transmit, to a network device 204, capability information of the terminal device 202, the capability information comprises information of one or more interruption time lengths supported by the terminal device 202 for switching between two modes under the FDD-SDL CA, wherein the two modes comprise a first mode in which there is no downlink reception on the SDL carrier, and a second mode in which there is downlink reception on the SDL carrier.

[0108] In some example embodiments, the information of one or more interruption time lengths comprises one of the following: one or more time values; or an indication of one or more table entries, the one or more table entries are from one or more interruption time length tables.

[0109] In some example embodiments, the capability information further comprises an indication indicating whether the terminal device 202 supports switching between different interruption time lengths based on at least one of the following: scheduling of the SDL carrier; a fixed scheme; or a timer.

[0110] In some example embodiments, the fixed scheme comprises a semi-static switching pattern configured by a radio resource control (RRC) signaling from the network device 204.

[0111] In some example embodiments, the one or more interruption time lengths are associated with at least one of the following: one or more architectures of the terminal device 202; one or more numbers of local oscillators used by the terminal device 202; or one or more filter settings used by the terminal device 202.

[0112] In some example embodiments, the terminal device 202 is further caused to: receive, from the network device 204, configuration information comprising information for configuring the FDD carrier and the SDL carrier.

[0113] In some example embodiments, the configuration information further comprises at least one of the following: information of one or more interruption time lengths to be used by the terminal device 202; or an indication indicating the terminal device 202 to switch between different interruption time lengths based on one of the following: scheduling of the SDL carrier, a fixed scheme, or a timer.

[0114] In some example embodiments, the terminal device 202 is further caused to: receive, via a downlink control information (DCI) or medium access control (MAC) message from the network device 204, an indication indicating the terminal device 202 to switch between different interruption time lengths based on scheduling of the SDL carrier.

[0115] In some example embodiments, the one or more interruption time lengths comprise a first interruption time length corresponding to the terminal device 202 using two local oscillators and a second interruption time length corresponding to the terminal device 202 using three local oscillators, the terminal device 202 is further caused to: determine to use two or three local oscillators based on scheduling of the SDL carrier.

[0116] In some example embodiments, the terminal device 202 is caused to determine to use two or three local oscillators based on scheduling of the SDL carrier by: determining to use two local oscillators when scheduling of the SDL carrier is not detected for a predetermined period; or determining to use three local oscillators when scheduling of the SDL carrier is detected.

[0117] FIG. 16 illustrates a flowchart of an example method 1600 implemented at a network device (for example, a network device 104 or 204, or a gNB 404) in accordance with some embodiments of the present disclosure. For ease of understanding, the method 1600 will be described from the perspective of the network device 204 with reference to FIG. 2.

[0118] At block 1610, the network device 204 obtains first information for switching of carriers in frequency division duplex-supplementary downlink (FDD-SDL) carrier aggregation (CA), the carriers at least comprise an FDD carrier and an SDL carrier.

[0119] In some example embodiments, the first information indicates the SDL carrier cannot be switched on concurrently with downlink operations on the FDD carrier.

[0120] In some example embodiments, the FDD carrier is a half-duplex FDD (HD-FDD) carrier, and the first information indicates uplink operations on the FDD carrier and downlink operations on the SDL carrier cannot occur concurrently.

[0121] In some example embodiments, the network device 204 is further caused to: periodically switch off uplink reception on the FDD carrier to adapt for activation of downlink transmission on the SDL carrier.

[0122] In some example embodiments, the first information indicates the SDL carrier can be switched onconcurrently with downlink operations on the FDD carrier.

[0123] In some example embodiments, the network device 204 is further caused to: periodically switch off uplink reception on the FDD carrier to adapt for activation of downlink transmission on both the FDD carrier and the SDL carrier.

[0124] In some example embodiments, the FDD carrier and the SDL carrier are adjacent or overlapping to each other in the frequency domain.

[0125] In some example embodiments, the network device 204 is further caused to: receive, from a terminal device 202, capability information of the terminal device 202, the capability information comprises information of one or more interruption time lengths supported by the terminal device 202 for switching between two modes under the FDD-SDL CA, wherein the two modes comprise a first mode in which there is no downlink reception on the SDL carrier, and a second mode in which there is downlink reception on the SDL carrier.

[0126] In some example embodiments, the information of one or more interruption time lengths comprises one of the following: one or more time values; or an indication of one or more table entries, the one or more table entries are from one or more interruption time length tables.

[0127] In some example embodiments, the capability information further comprises an indication indicating whether the terminal device 202 supports switching between different interruption time lengths based on at least one of the following: scheduling of the SDL carrier; a fixed scheme; or a timer.

[0128] In some example embodiments, the fixed scheme comprises a semi-static switching pattern configured by a radio resource control (RRC) signaling from the network device 204.

[0129] In some example embodiments, the one or more interruption time lengths are associated with at least one of the following: one or more architectures of the terminal device 202; one or more numbers of local oscillators used by the terminal device 202; or one or more filter settings used by the terminal device 202.

[0130] In some example embodiments, the network device 204 is further caused to: transmit, to the terminal device 202, configuration information comprising information for configuring the FDD carrier and the SDL carrier.

[0131] In some example embodiments, the configuration information further comprises at least one of the following: information of one or more interruption time lengths to be used by the terminal device 202; or an indication indicating the terminal device 202 to switch between different interruption time lengths based on one of the following: scheduling of the SDL carrier, a fixed scheme, or a timer.

[0132] In some example embodiments, the network device 204 is further caused to: transmit, via a downlink control information (DCI) or medium access control (MAC) message to the terminal device 202, an indication indicating the terminal device 202 to switch between different interruption time lengths based on scheduling of the SDL carrier.

[0133] In some example embodiments, the one or more interruption time lengths comprise a first interruption time length corresponding to the terminal device 202 using two local oscillators and a second interruption time length corresponding to the terminal device 202 using three local oscillators, the network device 204 is further caused to: determine that the terminal device 202 is to use two or three local oscillators based on scheduling of the SDL carrier.

[0134] In some example embodiments, the network device 204 is caused to determine that the terminal device 202 is to use two or three local oscillators based on scheduling of the SDL carrier by: determining that the terminal device 202 is to use two local oscillators when scheduling of the SDL carrier is not detected for a predetermined period; or determining that the terminal device 202 is to use three local oscillators when scheduling of the SDL carrier is detected.

[0135] In some example embodiments, an apparatus (for example, the terminal device 202) capable of performing the method 1500 may comprise means for performing the respective steps of the method 1500. The means may be implemented in any suitable form. For example, the means may be implemented in a circuitry or software module.

[0136] In some example embodiments, the apparatus may comprise: means for obtaining first information for switching of carriers in frequency division duplex-supplementary downlink (FDD-SDL) carrier aggregation (CA), the carriers at least comprise an FDD carrier and an SDL carrier.

[0137] In some embodiments, the apparatus further comprises means for performing other steps in some embodiments of the method 1500. In some embodiments, the means comprises at least one processor; and at least one memory including computer program code, the at least one memory and computer program code configured to, with the at least one processor, cause the performance of the apparatus.

[0138] In some example embodiments, an apparatus (for example, the network device 204) capable of performing the method 1600 may comprise means for performing the respective steps of the method 1600. The means may be implemented in any suitable form. For example, the means may be implemented in a circuitry or software module.

[0139] In some example embodiments, the apparatus may comprise: means for obtaining first information for switching of carriers in frequency division duplex-supplementary downlink (FDD-SDL) carrier aggregation (CA), the carriers at least comprise an FDD carrier and an SDL carrier.

[0140] In some embodiments, the apparatus further comprises means for performing other steps in some embodiments of the method 1600. In some embodiments, the means comprises at least one processor; and at least one memory including computer program code, the at least one memory and computer program code configured to, with the at least one processor, cause the performance of the apparatus.

[0141] FIG. 17 illustrates an example simplified block diagram of a device 1700 that is suitable for implementing embodiments of the present disclosure. The device 1700 may be provided to implement a communication device or a network element, for example, the terminal device 102 and the network device104 as shown in FIG. 1. As shown, the device 1700 includes one or more processors 1710, one or more memories 1720 may couple to the processor 1710, and one or more communication modules 1740 may couple to the processor 1710.

[0142] The communication module 1740 is for bidirectional communications. The communication module 1740 has at least one antenna to facilitate communication. The communication interface may represent any interface that is necessary for communication with other network elements, for example the communication interface may be wireless or wireline to other network elements, or software based interface for communication.

[0143] The processor 1710 may be of any type suitable to the local technical network and may include one or more of the following: general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs) and processors based on multicore processor architecture, as non-limiting examples. The device 1700 may have multiple processors, such as an application specific integrated circuit chip that is slaved in time to a clock which synchronizes the main processor.

[0144] The memory 1720 may include one or more non-volatile memories and one or more volatile memories. Examples of the non-volatile memories include, but are not limited to, a read only memory (ROM) 1724, an electrically programmable read only memory (EPROM), a flash memory, a hard disk, a compact disc (CD), a digital video disk (DVD), and other magnetic storage and / or optical storage. Examples of the volatile memories include, but are not limited to, a random access memory (RAM) 1722 and other volatile memories that will not last in the power-down duration.

[0145] A computer program 1730 includes computer executable instructions that are executed by the associated processor 1710. The program 1730 may be stored in the ROM 1724. The processor 1710 may perform any suitable actions and processing by loading the program 1730 into the RAM 1722.

[0146] The embodiments of the present disclosure may be implemented by means of the program so that the device 1700 may perform any process of the disclosure as discussed with reference to FIG. 1 or FIG. 16. The embodiments of the present disclosure may also be implemented by hardware or by a combination of software and hardware.

[0147] In some example embodiments, the program 1730 may be tangibly contained in a computer readable medium which may be included in the device 1700 (such as in the memory 1720) or other storage devices that are accessible by the device 1700. The device 1700 may load the program 1730 from the computer readable medium to the RAM 1722 for execution. The computer readable medium may include any types of tangible non-volatile storage, such as ROM, EPROM, a flash memory, a hard disk, CD, DVD, and the like. FIG. 18 shows an example of the computer readable medium 1800 in form of CD or DVD. The computer readable medium has the program 1730 stored thereon.

[0148] Generally, various embodiments of the present disclosure may be implemented in hardware or special purpose circuits, software, logic or any combination thereof. Some aspects may be implemented inhardware, while other aspects may be implemented in firmware or software which may be executed by a controller, microprocessor or other computing device. While various aspects of embodiments of the present disclosure are illustrated and described as block diagrams, flowcharts, or using some other pictorial representations, it is to be understood that the block, apparatus, system, technique or method described herein may be implemented in, as non-limiting examples, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof.

[0149] The present disclosure also provides at least one computer program product tangibly stored on a non-transitory computer readable storage medium. The computer program product includes computerexecutable instructions, such as those included in program modules, being executed in a device on a target real or virtual processor, to carry out the methods 200, 400, 1500 and 1600 as described above with reference to FIG. 2, FIG. 4, FIG. 15 and FIG. 16. Generally, program modules include routines, programs, libraries, objects, classes, components, data structures, or the like that perform particular tasks or implement particular abstract data types. The functionality of the program modules may be combined or split between program modules as desired in various embodiments. Machine-executable instructions for program modules may be executed within a local or distributed device. In a distributed device, program modules may be located in both local and remote storage media.

[0150] Program code for carrying out methods of the present disclosure may be written in any combination of one or more programming languages. These program codes may be provided to a processor or controller of a general purpose computer, special purpose computer, or other programmable data processing apparatus, such that the program codes, when executed by the processor or controller, cause the functions / operations specified in the flowcharts and / or block diagrams to be implemented. The program code may execute entirely on a machine, partly on the machine, as a stand-alone software package, partly on the machine and partly on a remote machine or entirely on the remote machine or server.

[0151] In the context of the present disclosure, the computer program codes or related data may be carried by any suitable carrier to enable the device, apparatus or processor to perform various processes and operations as described above. Examples of the carrier include a signal, computer readable medium, and the like.

[0152] The computer readable medium may be a computer readable signal medium or a computer readable storage medium. A computer readable medium may include but not limited to an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples of the computer readable storage medium would include an electrical connection having one or more wires, a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an opticalstorage device, a magnetic storage device, or any suitable combination of the foregoing. The term “non-transitory,” as used herein, is a limitation of the medium itself (i.e., tangible, not a signal) as opposed to a limitation on data storage persistency (e.g., RAM vs. ROM).

[0153] Further, while operations are depicted in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. In certain circumstances, multitasking and parallel processing may be advantageous. Likewise, while several specific implementation details are contained in the above discussions, these should not be construed as limitations on the scope of the present disclosure, but rather as descriptions of features that may be specific to particular embodiments. Certain features that are described in the context of separate embodiments may also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment may also be implemented in multiple embodiments separately or in any suitable sub-combination.

[0154] Although the present disclosure has been described in languages specific to structural features and / or methodological acts, it is to be understood that the present disclosure defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.

Claims

WHAT IS CLAIMED IS:

1. A terminal device comprising:at least one processor; andat least one memory storing instructions that, when executed by the at least one processor, cause the terminal device at least to:obtain first information for switching of carriers in frequency division duplex-supplementary downlink (FDD-SDL) carrier aggregation (CA), the carriers at least comprise an FDD carrier and an SDL carrier.

2. The terminal device of claim 1, wherein the first information indicates the SDL carrier cannot be switched on concurrently with downlink operations on the FDD carrier.

3. The terminal device of claim 1, wherein the FDD carrier is a half-duplex FDD (HD-FDD) carrier, and the first information indicates uplink operations on the FDD carrier and downlink operations on the SDL carrier cannot occur concurrently.

4. The terminal device of claim 2 or 3, wherein the terminal device is further caused to: periodically switch off uplink transmission on the FDD carrier to adapt for activation of downlink reception on the SDL carrier.

5. The terminal device of claim 1, wherein the first information indicates the SDL carrier can be switched on concurrently with downlink operations on the FDD carrier.

6. The terminal device of claim 5, wherein the terminal device is further caused to: periodically switch off uplink transmission on the FDD carrier to adapt for activation of downlink reception on both the FDD carrier and the SDL carrier.

7. The terminal device of any of claims 1 to 6, wherein the FDD carrier and the SDL carrier are adjacent or overlapping to each other in the frequency domain.

8. The terminal device of any of claims 1 to 7, the terminal device is further caused to: transmit, to a network device, capability information of the terminal device, the capability information comprises information of one or more interruption time lengths supported by the terminal device for switching between two modes under the FDD-SDL CA,wherein the two modes comprise a first mode in which there is no downlink reception on the SDL carrier, and a second mode in which there is downlink reception on the SDL carrier.

9. The terminal device of claim 8, wherein the information of one or more interruption time lengths comprises one of the following:one or more time values; oran indication of one or more table entries, the one or more table entries are from one or more interruption time length tables.

10. The terminal device of claim 8 or 9, wherein the capability information further comprises an indication indicating whether the terminal device supports switching between different interruption time lengths based on at least one of the following:scheduling of the SDL carrier;a fixed scheme; ora timer.

11. The terminal device of claim 10, wherein the fixed scheme comprises a semi-static switching pattern configured by a radio resource control (RRC) signaling from the network device.

12. The terminal device of any of claims 8 to 11, wherein the one or more interruption time lengths are associated with at least one of the following:one or more architectures of the terminal device;one or more numbers of local oscillators used by the terminal device; orone or more filter settings used by the terminal device.

13. The terminal device of any of claims 1 to 12, wherein the terminal device is further caused to: receive, from the network device, configuration information comprising information for configuring the FDD carrier and the SDL carrier.

14. The terminal device of claim 13, wherein the configuration information further comprises at least one of the following:information of one or more interruption time lengths to be used by the terminal device; or an indication indicating the terminal device to switch between different interruption time lengths based on one of the following: scheduling of the SDL carrier, a fixed scheme, or a timer.

15. The terminal device of any of claims 8 to 13, wherein the terminal device is further caused to: receive, via a downlink control information (DCI) or medium access control (MAC) message from the network device, an indication indicating the terminal device to switch between different interruption time lengths based on scheduling of the SDL carrier.

16. The terminal device of any of claims 8 to 15, wherein the one or more interruption time lengths comprise a first interruption time length corresponding to the terminal device using two local oscillators and a second interruption time length corresponding to the terminal device using three local oscillators, the terminal device is further caused to:determine to use two or three local oscillators based on scheduling of the SDL carrier.

17. The terminal device of claim 16, wherein the terminal device is caused to determine to use two or three local oscillators based on scheduling of the SDL carrier by:determining to use two local oscillators when scheduling of the SDL carrier is not detected for a predetermined period; ordetermining to use three local oscillators when scheduling of the SDL carrier is detected.

18. A network device comprising:at least one processor; andat least one memory storing instructions that, when executed by the at least one processor, cause the network device at least to:obtain first information for switching of carriers in frequency division duplex-supplementary downlink (FDD-SDL) carrier aggregation (CA), the carriers at least comprise an FDD carrier and an SDL carrier.

19. The network device of claim 18, wherein the first information indicates the SDL carrier cannot be switched on concurrently with downlink operations on the FDD carrier.

20. The network device of claim 18, wherein the FDD carrier is a half-duplex FDD (HD-FDD) carrier, and the first information indicates uplink operations on the FDD carrier and downlink operations on the SDL carrier cannot occur concurrently.

21. The network device of claim 19 or 20, wherein the network device is further caused to: periodically switch off uplink reception on the FDD carrier to adapt for activation of downlink transmission on the SDL carrier.

22. The network device of claim 18, wherein the first information indicates the SDL carrier can be switched on concurrently with downlink operations on the FDD carrier.

23. The network device of claim 22, wherein the network device is further caused to: periodically switch off uplink reception on the FDD carrier to adapt for activation of downlink transmission on both the FDD carrier and the SDL carrier.

24. The network device of any of claims 18 to 23, wherein the FDD carrier and the SDL carrier are adjacent or overlapping to each other in the frequency domain.

25. The network device of any of claims 18 to 24, the network device is further caused to: receive, from a terminal device, capability information of the terminal device, the capability information comprises information of one or more interruption time lengths supported by the terminal device for switching between two modes under the FDD-SDL CA,wherein the two modes comprise a first mode in which there is no downlink reception on the SDL carrier, and a second mode in which there is downlink reception on the SDL carrier.

26. The network device of claim 25, wherein the information of one or more interruption time lengths comprises one of the following:one or more time values; oran indication of one or more table entries, the one or more table entries are from one or more interruption time length tables.

27. The network device of claim 25 or 26, wherein the capability information further comprises an indication indicating whether the terminal device supports switching between different interruption time lengths based on at least one of the following:scheduling of the SDL carrier;a fixed scheme; ora timer.

28. The network device of claim 27, wherein the fixed scheme comprises a semi-static switching pattern configured by a radio resource control (RRC) signaling from the network device.

29. The network device of any of claims 25 to 28, wherein the one or more interruption time lengths are associated with at least one of the following:one or more architectures of the terminal device;one or more numbers of local oscillators used by the terminal device; orone or more filter settings used by the terminal device.

30. The network device of any of claims 18 to 29, wherein the network device is further caused to: transmit, to the terminal device, configuration information comprising information for configuring the FDD carrier and the SDL carrier.

31. The network device of claim 30, wherein the configuration information further comprises at least one of the following:information of one or more interruption time lengths to be used by the terminal device; or an indication indicating the terminal device to switch between different interruption time lengths based on one of the following: scheduling of the SDL carrier, a fixed scheme, or a timer.

32. The network device of any of claims 25 to 30, wherein the network device is further caused to: transmit, via a downlink control information (DCI) or medium access control (MAC) message to the terminal device, an indication indicating the terminal device to switch between different interruption time lengths based on scheduling of the SDL carrier.

33. The network device of any of claims 25 to 32, wherein the one or more interruption time lengths comprise a first interruption time length corresponding to the terminal device using two local oscillators and a second interruption time length corresponding to the terminal device using three local oscillators, the network device is further caused to:determine that the terminal device is to use two or three local oscillators based on scheduling of the SDL carrier.

34. The network device of claim 33, wherein the network device is caused to determine that the terminal device is to use two or three local oscillators based on scheduling of the SDL carrier by:determining that the terminal device is to use two local oscillators when scheduling of the SDL carrier is not detected for a predetermined period; ordetermining that the terminal device is to use three local oscillators when scheduling of the SDL carrier is detected.

35. A method for a terminal device comprising:obtaining first information for switching of carriers in frequency division duplex-supplementary downlink (FDD-SDL) carrier aggregation (CA), the carriers at least comprise an FDD carrier and an SDL carrier.

36. A method for a network device comprising:obtaining first information for switching of carriers in frequency division duplex-supplementary downlink (FDD-SDL) carrier aggregation (CA), the carriers at least comprise an FDD carrier and an SDL carrier.

37. An apparatus for a terminal device comprising:means for obtaining first information for switching of carriers in frequency division duplex-supplementary downlink (FDD-SDL) carrier aggregation (CA), the carriers at least comprise an FDD carrier and an SDL carrier.

38. An apparatus for a network device comprising:means for obtaining first information for switching of carriers in frequency division duplex-supplementary downlink (FDD-SDL) carrier aggregation (CA), the carriers at least comprise an FDD carrier and an SDL carrier.

39. A non-transitory computer readable medium comprising program instructions stored thereon for performing the method of claim 35 or 36.

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