JP7540824B2 - User Equipment and Base Station - Google Patents

Description

Non-limiting and exemplary embodiments of the present disclosure relate generally to wireless communications, and more particularly to methods and apparatus for performing transmissions according to a frame structure in unlicensed spectrum in a wireless network that supports communications over both licensed and unlicensed spectrum.

This section introduces aspects that may facilitate a better understanding of the present disclosure. Accordingly, the statements in this section are to be read in this light and are not to be understood as admissions about what is in the prior art or what is not in the prior art.

The rapid adoption of the Third Generation Partnership Project (3GPP)-Long Term Evolution (LTE) in various regions of the world indicates an increasing demand for wireless broadband data. To meet the data traffic demand from an ever-increasing number of users, more mobile broadband bandwidth will be required, especially in concentrated high-traffic buildings or hotspots. Given the large amount of spectrum available in unlicensed bands around the world, unlicensed spectrum is viewed by cellular operators as a complementary means to increase service offerings. Although unlicensed spectrum may not match the quality of the licensed regime, solutions that allow efficient utilization of unlicensed spectrum as a complement to licensed deployments could bring significant value to mobile operators and ultimately the entire mobile industry. This type of solution allows operators and vendors to leverage existing or planned investments in LTE/Evolved Package Core (EPC) hardware in radio and core networks.

3GPP RP-141664 agreed to study Licensed-Assisted Access (LAA) technology. This LAA framework builds on carrier aggregation solutions introduced in LTE Release-10 to access additional bandwidth in unlicensed spectrum, thus supporting the coexistence of different wireless technologies such as LTE and Wi-Fi. Figure 1 shows an example network in which user equipment (UE) is configured to aggregate a secondary cell (SCell) using an unlicensed carrier in the unlicensed spectrum. The primary cell (PCell) can maintain the exchange of essential control messages and provide real-time and high-value traffic over the licensed spectrum. Through a robust licensed spectrum, the PCell can also provide mobility handling and management for the UE. The aggregated SCell in the unlicensed spectrum can be utilized as a bandwidth booster to accommodate best effort traffic when available. The LAA SCell may be operated in the downlink (DL) or uplink (UL) or both.

However, due to the lack of certainty of available resources in unlicensed carriers, directly applying the existing frame structure in the LTE system to the LAA system may cause some problems, such as unexpected resource waste and transmission delays. Although some solutions have been proposed for a frame structure applicable to the LAA system, there is no way to indicate the frame structure between communicating parties, e.g., from a base station to a terminal device or vice versa (terminal device to base station), so that DL and/or UL transmissions can be performed between the base station and the terminal device on the unlicensed spectrum according to the frame structure.

The various embodiments of the present disclosure have a primary objective to provide a solution for indicating a frame structure applicable to a wireless network supporting communication over licensed and unlicensed spectrum such that transmissions can be performed between a base station and a terminal device over an unlicensed spectrum according to the frame structure. Other features and advantages of the embodiments of the present disclosure will be understood from the following description of specific embodiments, taken in conjunction with the accompanying drawings illustrating the principles of the embodiments of the present disclosure.

A first aspect of the present disclosure provides a method for performing transmission between a base station and a terminal device according to a frame structure in an unlicensed spectrum in a wireless network supporting communication over both licensed and unlicensed spectrums. The method includes signaling information indicating a frame structure, and performing transmission between the base station and the terminal device on an unlicensed carrier in the unlicensed spectrum according to the frame structure. The method may be performed in the base station or the terminal device.

In a second aspect of the present disclosure, there is provided an apparatus for performing transmission between a base station and a terminal device according to a frame structure in an unlicensed spectrum in a wireless network supporting communication over both licensed and unlicensed spectrums. The apparatus includes a signaling unit for signaling information indicating the frame structure, and a transmission performing unit for performing transmission between the base station and the terminal device on an unlicensed carrier in the unlicensed spectrum according to the frame structure. The apparatus may be embodied in a base station or as at least a part of a base station. The apparatus may alternatively be embodied in a terminal device or as at least a part of a terminal device.

In a third aspect of the present disclosure, there is provided an apparatus for performing transmissions between a base station and a terminal device in accordance with a frame structure in the unlicensed spectrum in a wireless network supporting communication in both licensed and unlicensed spectrum. The apparatus comprises a processor and a memory, the memory including instructions executable by the processor, and the apparatus is operative to perform a method according to the first aspect of the present disclosure. The apparatus may be embodied in a base station or as at least part of a base station. The apparatus may alternatively be embodied in a terminal device or as part of a terminal device.

The above and other aspects, features, and advantages of various embodiments of the present disclosure will become more fully apparent from the following detailed description, taken in conjunction with the accompanying drawings.

FIG. 1 illustrates an example network in which a UE is configured to integrate a secondary cell that uses an unlicensed carrier in an unlicensed spectrum.

FIG. 2 shows three conceptual frame structures corresponding to three transmission cases.

FIG. 3 shows three specific examples corresponding respectively to the three frame structures in FIG.

FIG. 4 illustrates a flowchart of a method for performing transmission according to a frame structure in an unlicensed spectrum according to an embodiment of the present disclosure.

FIG. 5 is a diagram illustrating an example of how to reduce the number of bits to indicate information about the start of an initial signal according to an embodiment of the present disclosure.

FIG. 6 illustrates a schematic block diagram of an apparatus for performing transmissions according to a frame structure in an unlicensed spectrum in accordance with an embodiment of the present disclosure.

FIG. 7 illustrates a schematic block diagram of another apparatus for performing transmissions according to a frame structure in an unlicensed spectrum in accordance with an embodiment of the present disclosure.

Like reference numbers and designations in the various drawings indicate like elements.

The principles and spirit of the present disclosure will now be described with reference to exemplary embodiments. It should be understood that all of these embodiments are provided merely to enable those skilled in the art to better understand and further practice the present disclosure, but are not intended to limit the scope of the present disclosure. For example, features illustrated or described as part of one embodiment may be used with other embodiments to yield yet further embodiments. For purposes of clarity, not all features of an actual implementation are described in this specification.

References in the specification to "an embodiment," "another embodiment," "a further embodiment," etc., indicate that the described embodiment may include a particular feature, structure, or characteristic, but not all embodiments necessarily include the particular feature, structure, or characteristic. Moreover, such phrases do not necessarily refer to the same embodiment. Moreover, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is within the knowledge of one of ordinary skill in the art to affect such feature, structure, or characteristic, whether or not expressly described.

Although terms such as "first" and "second" are used herein to describe various elements, it is understood that these elements should not be limited by these terms. These terms are used only to distinguish one element from another. For example, a first element can be referred to as a second element, and similarly, a second element can be referred to as a first element, without departing from the scope of the exemplary embodiments. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed terms.

The terms used herein are for the purpose of describing particular embodiments and are not intended to limit the embodiments. As used herein, the singular forms are intended to include the plural, unless the context clearly indicates otherwise. The terms "comprises," "comprising," "including," and/or "comprising," as used herein, are understood to specify the presence of the referenced features, elements, and/or components, etc., but do not exclude the presence or addition of one or more other features, elements, components, and/or combinations thereof.

In the following description and claims, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this disclosure belongs. For example, the term "base station (BS)" used herein may be referred to as, for example, eNB, eNodeB, NodeB, or base transceiver station (BTS), access node (AN), or access point (AP), depending on the technology and terminology used. Similarly, the term "terminal device" or UE used herein may be referred to as any terminal having mobile wireless communication capabilities. For example, it includes, but is not limited to, a mobile phone, a cellular phone, a smartphone, or a personal digital assistant (PDA), a portable computer, an image capture device such as a digital camera, a game device, a music storage device and a music playback device, and any portable unit or terminal having wireless communication capabilities, or an Internet device that allows Internet access and browsing. In this document, "terminal device" and "UE" are used interchangeably.

Embodiments of the present disclosure are applicable to any wireless network that supports communication over both licensed and unlicensed spectrum, including, but not limited to, an LAA network. To simplify the following description, an LAA network is used as an illustrative example of a wireless network that supports communication over both licensed and unlicensed spectrum, but is not a limitation of the present disclosure.

In general, the transmissions performed on the unlicensed spectrum according to a frame structure applicable to the LAA network may include at least one of DL transmissions and UL transmissions. In other words, the frame structures applicable to the LAA network may be classified into three classes: 1) DL-only: a frame structure supporting only DL transmissions, 2) DL+UL: a frame structure supporting both DL and UL transmissions, and 3) UL-only: a frame structure supporting only UL transmissions. The DL transmissions may include transmissions of DL control information (referred to herein as DL control transmissions), such as, for example, a Physical Downlink Control Channel (PDCCH), and DL data transmissions, such as, for example, a Physical Downlink Shared Channel (PDSCH). Similarly, an UL transmission may include a transmission of UL control information (referred to herein as UL control transmission), e.g., a Physical Uplink Control Channel (PUCCH), and/or an UL data transmission, e.g., a Physical Uplink Shared Channel (PUSCH). It will be understood that the use of the term "only" in this specification does not mean that there are no other transmissions in the DL or UL. For example, there may be an initial signal transmission (described below) in the DL or UL. However, such signal transmissions in the DL or UL are not considered to belong to the DL or UL transmissions in this document.

Because unlicensed spectrum is a shared property, the same transmission resources may be used simultaneously by multiple stations, including base stations and terminal devices, which may result in collisions. To avoid such collisions, existing wireless networks operating in unlicensed spectrum, such as Wireless Local Area Networks (WLANs) using Wi-Fi technology, use the Carrier Sense Multiple Access (CSMA) method, also called "listen before talk (LBT)", to regulate access to transmission resources. All stations, including base stations and terminal devices, are allowed to access the resources, but before transmitting, they must verify that the resources are not being used by other stations.

Similarly, in an LAA network, before transmitting, a base station or a terminal device must ensure that the resources accessed on the unlicensed carrier in the unlicensed spectrum are not being used by other base stations or terminal devices. For example, when a base station or a terminal device has a packet to transmit on an unlicensed carrier, it may perform a clear channel assessment (CCA) check by performing an LBT to obtain exclusive occupancy on the unlicensed carrier. Since either DL or UL transmission needs to start at a specific location, for example, at a certain symbol boundary or subframe boundary, there is usually a time period after the successful LBT until the DL or UL transmission is actually performed. During this period, a signal may be transmitted on the unlicensed carrier. The main purpose of transmitting this signal is to ensure that the resources on the unlicensed carrier are not used by other users during this period. Furthermore, the transmitted signal may contain some information on the unlicensed carrier to assist or facilitate transmission or for other purposes. In this document, this signal is called the initial signal, and this period is called the reservation period. However, it should be understood that other terms may be used to name the signals and the periods, and any particular term for naming the signals and periods does not constitute a limitation of the signals and periods themselves. Additionally, resources in unlicensed carriers may be reserved through other techniques, but are not limited to the transmission of initial signals.

To better understand the present disclosure, three schematic frame structures corresponding to each of the three classes of frame structures described above are shown in FIG.

Figure 2(A) corresponds to the DL-only class. As shown, the frame structure of Figure 2(A) includes a first group of time resources corresponding to a reservation period and a second group of time resources for DL transmission within a maximum allowed transmission time period, which can be referred to as a transmission opportunity (TXOP). The maximum allowed transmission time period refers to a period during which CCA does not need to be performed. Those skilled in the art will understand that the specific term TXOP for expressing the maximum allowed transmission time period does not constitute a limitation on the meaning of the maximum allowed transmission time period.

Figure 2(B) corresponds to the DL+UL class. The frame structure of Figure 2(B) includes within the TXOP a first group of time resources corresponding to the reservation period, a second group of time resources used for DL transmissions, and a third group of time resources for UL transmissions.

Figure 2(C) corresponds to the UL-only class. The frame structure of Figure 2(C) includes within the TXOP a first group of time resources corresponding to the reservation period and a second group of time resources for UL transmissions.

It should be understood that these three frame structures are shown herein only to illustrate some general features of subframe structures to facilitate the following description of the present disclosure. Thus, any particular features shown in this figure, such as the particular order in which the various time resources are shown and the illustrated durations of the various time resources, are not intended to limit the present disclosure. Also, the dotted lines used in this figure mean that other time resources may or may not be present, and are not particularly limited. Those skilled in the art will appreciate that the first, second, or third time resources may correspond to one or more subframes or symbols or other resource units, but the one or more subframes or symbols or other resource units corresponding to the individual time resources do not constitute a limitation of the present disclosure. Thus, the details of the subframes and symbols are not shown in this figure.

Figure 3 shows specific examples corresponding to each of the three frame structures in Figure 2.

In particular, FIG. 3A shows an example of the frame structure of FIG. 2A. In this example, the frame structure includes a first set of time resources and four DL subframes in which DL transmissions are performed. The subset of the first set of time resources, indicated by the horizontally shaded block, corresponds to the first group of time resources in FIG. 2A, while the four DL subframes correspond to the second group of time resources in FIG. 2A. According to this frame structure, the availability of the unlicensed carriers is first determined within the portion indicated by the dotted block in the first set of time resources by using the LBT scheme. Then, the subset of the first set of time resources is reserved until the end of the first set of time resources. Once the duration of the reserved subset of time resources is over, DL transmissions, including DL control transmissions and DL data transmissions, are performed in four consecutive DL subframes.

3B shows an example of the frame structure of FIG. 2B. In this example, the frame structure includes a first set of time resources, one DL subframe in which DL transmissions are performed, a subframe including a guard period (GP), one UL subframe in which UL transmissions are performed, and a second set of time resources. The subset of the first set of time resources indicated by the horizontally shaded block corresponds to the first group of time resources of FIG. 2B. The sum of the partial resources after the subset in the first set of time resources, the DL subframe, and the partial resources before the GP in the subframe including the GP corresponds to the second group of time resources of FIG. 2B. The sum of the partial resources after the GP in the subframe including the GP, the UL subframe, and the first half of the second set of time resources corresponds to the third group of time resources of FIG. 2B. According to this frame structure, the availability of the unlicensed carrier (with respect to whether the unlicensed carrier is available) is first performed within the portion indicated by the dotted block in the first set of time resources. Then, as shown by the horizontally shaded blocks, a subset of the first set of time resources is reserved until the start of a particular symbol in the first set of time resources. Once the duration of the reserved subset of time resources has expired, DL transmissions, including DL control transmissions and DL data transmissions, occur until a GP is encountered. Then, once the duration of the GP has expired, UL transmissions occur until the end of the TXOP.

3C shows an example of the frame structure of FIG. 2C. In this example, the frame structure includes a first set of time resources, three UL subframes in which UL transmissions are performed, and a second set of time resources. The subset of the first set of time resources, indicated by the horizontally shaded block, corresponds to the first group of time resources of FIG. 2C. The sum of the partial resources after the subset in the first set of time resources, the UL subframe, the partial resources before the GP in the subframe containing the GP, and the first half of the second set of time resources corresponds to the second group of time resources of FIG. 2C. According to this frame structure, the availability of the unlicensed carrier is first determined within the portion indicated by the dotted block in the first set of time resources by using the LBT scheme. Then, as indicated by the horizontally shaded block, a subset of the first set of time resources is reserved until the start of a particular symbol in the first set of time resources. Once the duration of the reserved subset of time resources has expired, UL transmissions, including UL control transmissions and/or UL data transmissions, are performed until the end of the TXOP.

It is understood that in FIG. 3, the number of DL or UL subframes and subframes containing GP are illustrated for illustrative purposes only, rather than for limiting purposes. Those skilled in the art can understand that these numbers may be changed according to the requirements of the actual application.

Various embodiments of the present disclosure will now be described with reference to Figures 4 to 7.

FIG. 4 illustrates a flow chart of a method 400 for performing transmission between a base station and a terminal device according to a frame structure in an unlicensed spectrum in a wireless network according to an embodiment of the present disclosure. The wireless network supports communication over both licensed and unlicensed spectrum, meaning that the base station and the terminal device can operate in both licensed and unlicensed spectrum. The transmission may include DL transmission and/or UL transmission. The method 400 may be performed in the base station or the terminal device.

In FIG. 4, the operations in the solid blocks are required, while the operations in the dashed blocks are optional and may be selected according to various implementations of the present disclosure. The description begins with the required operations in block 410.

Specifically, the method 400 starts at step 410, where information indicative of a frame structure is signaled. Then, transmission is performed between the base station and the terminal device on an unlicensed carrier of the unlicensed spectrum according to the frame structure. In an embodiment, the information indicative of the frame structure (hereinafter referred to as "indicating information") may be signaled on a licensed carrier of the licensed spectrum. In another embodiment, the indicating information may be signaled on an unlicensed carrier.

It is clear that the ultimate goal of indicating the frame structure to be used on the unlicensed spectrum is to enable transmission to be performed on the unlicensed carrier in the unlicensed spectrum according to the frame structure. Therefore, the information on the frame structure necessary to enable transmission on the unlicensed carrier should be known to both communication partners, i.e., the base station and the terminal device. The necessary information may be obtained directly or indirectly derived from other information. In this way, the necessary information itself and any information that allows to derive the necessary information may be signaled as indication information. The signaling of the information is detailed below for three cases: 1) DL-only case, where only DL transmissions are included; 2) DL+UL case, where both DL and UL transmissions are included; and 3) UL-only case, where only UL transmissions are included.

DL-only Case

To achieve the ultimate goal of enabling transmission, i.e., for DL transmission to be performed on an unlicensed carrier, any one or more pieces of information that can be used alone or in combination to derive the information necessary to enable DL transmission on an unlicensed carrier may be indicated to the terminal device as instruction information.

In an embodiment, the instruction information may include any or any combination of information in the following groups:
Information regarding the start of DL transmission,
Information regarding the end of DL transmission;
Information regarding the duration of the TXOP;
Information regarding the duration of DL transmission, and Information regarding unlicensed carriers.

In a further embodiment in which the frame structure in FIG. 2(A) is employed and the initial signal is transmitted in a first group of time resources, said group may further include information about the start of the first group of time resources or about the start of the initial signal.

Since DL transmission is specific to the unlicensed carrier, the unlicensed carrier on which the DL transmission is performed should be known to the terminal device. Therefore, the unlicensed carrier may be indicated to the terminal device. In one example, the unlicensed carrier may be explicitly indicated by including information about the unlicensed carrier in the indication information, particularly when the unlicensed carrier on which the indication information is received is different from the unlicensed carrier on which the DL transmission is performed. In another example, the unlicensed carrier may be implicitly indicated, particularly when the unlicensed carrier on which the indication information is received is the same as the unlicensed carrier on which the DL transmission is performed. In this case, the unlicensed carrier on which the DL transmission is performed may be implicitly determined as the unlicensed carrier on which the indication information is received.

In one example, if the initial signal and DL data or DL control information can be correctly detected, only the duration of the DL transmission or the duration of the TXOP needs to be indicated, such that the receiving terminal device can derive the necessary information to enable the DL transmission, such as, for example, the start and end of the DL transmission, and the end of the DL transmission may be rounded down to the nearest symbol or subframe. Thus, in this example, the indication information may include information regarding the duration of the DL transmission, or information regarding the duration of the TXOP.

In another example, if the start of DL transmission is predetermined, the start of the initial signal and the duration of DL transmission or the duration of the TXOP may be indicated, from which the receiving terminal device can derive the necessary information for DL transmission, such as, for example, the start and end of DL transmission. Thus, in this example, the indication information may include information regarding the start of the initial signal and information regarding the duration of DL transmission or information regarding the duration of the TXOP.

In yet another example, the start of the initial signal, the start of the DL transmission, and the duration of the DL transmission or the duration of the TXOP may be indicated, from which the receiving terminal device can derive the necessary information to enable the DL transmission, such as, for example, the start and end of the DL transmission. Thus, in this example, the indication information may include information regarding the start of the initial signal, information regarding the start of the DL transmission, and information regarding the duration of the DL transmission or the duration of the TXOP.

In yet another example, the start of DL transmission and the end of DL transmission may be directly indicated. Thus, in this example, the indication information may include information regarding the start of DL transmission and information regarding the duration of DL transmission.

Alternatively, some information that changes slowly or can be predefined, such as, for example, TXOP, may be notified to the terminal device via higher layer signaling instead of being included in the indication information.

Furthermore, the indication information may be signaled in multiple bits, for example by reusing existing Downlink Control Information (DCI) format 1C, as defined in section 5.3.3 of 3GPP Technical Specification 36.212 version 12.4.0. In this case, a new radio network temporary identifier (RNTI) may be required to distinguish the reused DCI format 1C from existing uses of DCI format 1C.

Alternatively, the indication information may be signaled in a new DCI format that includes a field that may contain the indication information.

To efficiently utilize limited bandwidth resources, the number of bits used to indicate the frame structure may be reduced as small as possible. Figure 5 shows an example of how to reduce the number of bits indicating information about the start of an initial signal according to an embodiment of the present disclosure.

In this example, it is predefined that DL transmission starts at symbol 11 in a subframe consisting of 14 symbols. It is understood that DL transmission may start at a different specific symbol and that a subframe may contain fewer or more symbols. If the initial signal starts at symbol 8, there are two ways to indicate the start of the initial signal: 1) use the absolute start position of the initial signal, i.e., use the 9th symbol of this subframe, which requires 4 bits to indicate; 2) use the relative start position of the initial signal with respect to the DL transmission, which is the difference between the start position of the initial signal and the start position of the DL transmission, i.e., use 3 symbols, which requires 2 bits to indicate. Obviously, using the relative start position of the initial signal can reduce the number of bits to indicate.

ＤＬ＋ＵＬケース As an example, Table 1 lists several bits that may be used, alone or in combination, to indicate frame structure in a reused DCI format 1C, which may provide 15 bits for 20 MHz.

DL+UL case

As in the DL-only case, any one or more pieces of information that can derive, alone or in combination, the information required to enable DL and UL transmissions on the unlicensed carrier to achieve the ultimate goal of enabling transmissions, i.e., to have DL and UL transmissions performed on the unlicensed carrier, may be indicated to the terminal device as indication information.

In an embodiment, the instruction information may include any information or any combination of information in the following groups:
Information regarding the start of DL transmission,
Information regarding the end of DL transmission;
Information regarding the start of UL transmission;
Information regarding the end of UL transmission;
Information regarding the duration of the TXOP;
Information regarding the duration of DL transmission;
information regarding the duration of a UL transmission; and information regarding the sum of the duration of a DL transmission and the duration of a UL transmission.
Information about unlicensed carriers.

In a further embodiment in which the frame structure in FIG. 2(B) is employed and the initial signal is transmitted in a first group of time resources, said group may further include information about the start of the first group of time resources or about the start of the initial signal.

Since DL and UL transmissions are specific to the unlicensed carrier, the unlicensed carrier on which the DL and UL transmissions are performed must be known to the terminal device. Therefore, the unlicensed carrier may need to be indicated to the terminal device. As described above for the DL-only case, for example, the unlicensed carrier may be explicitly indicated by including information about the unlicensed carrier in the indication information, or may be indicated implicitly.

In alternative embodiments, some information that may vary slowly or be predefined, such as the TXOP, may be signaled to the terminal device via higher layer signaling. Thus, such information may not be included in the indication information.

In other embodiments, where a UL grant for UL scheduling can be successfully received at the terminal device, the UL grant may be used to determine the start of the UL transmission. For example, the UL transmission may start at the boundary of the subframe following the subframe in which the uplink grant is received at the terminal device. In particular, if a UL grant is successfully received in subframe 1, the UL transmission scheduled by this UL grant may start at the boundary of subframe 2, subframe 3, etc. In this case, information regarding the start of the UL transmission may not be included in the indication information.

Again, the indication information may be signaled in multiple bits, for example by reusing existing DCI format 1C as specified in section 5.3.3 of 3GPP Technical Specification 36.212 version 12.4.0. In this case, a new RNTI may be required to distinguish the reused DCI format 1C from existing uses of DCI format 1C.

Alternatively, the indication information may be signaled in a new DCI format that includes a field that may contain the indication information.

As in the DL-only case, the relative start position of the initial signal may be used to reduce the number of bits indicating the frame structure.

As an example, Table 2 lists some bits that may be used, alone or in combination, to indicate the frame structure in reuse DCI format 1C, which may provide 15 bits for 20 MHz. In this example, it is assumed that UL transmissions start on a subframe boundary.

ＵＬ－オンリーケース（UL-only Case） As another example, Table 3 lists several bits that may be used, alone or in combination, to indicate the frame structure in reuse DCI format 1C, which may provide 15 bits for 20 MHz. In this example, it is assumed that UL transmissions start on a symbol boundary.

UL-only Case

Similar to the DL-only or DL+UL cases, any one or more pieces of information that can be used alone or in combination to derive the information required to enable UL transmission on the unlicensed carrier to achieve the ultimate goal of enabling transmission, i.e., to have UL transmission performed on the unlicensed carrier, may be indicated as instruction information to the base station.

In an embodiment, the instructional information may include any or any combination of information in the following groups:
Information regarding the start of an uplink transmission,
Information regarding the end of an uplink transmission;
Information regarding the duration of the TXOP, and Information regarding the duration of the UL transmission.

In a further embodiment in which the frame structure in FIG. 2(C) is employed and the initial signal is transmitted in a first group of time resources, said group may further include information about the start of the first group of time resources or about the start of the initial signal.

In other embodiments, where the UL grant for UL scheduling can be successfully received by the terminal device, the UL grant may be used to determine the start of UL transmission. Thus, information regarding the start of UL transmission may not be included in the indication information.

The indication information may be signaled periodically or non-periodically, for example in multiple bits on the PUCCH.

Similar to the DL-only or DL+UL cases, the relative starting position of the initial signal may be used to reduce the number of bits to indicate the frame structure.

By way of example, Table 4 lists several bits that may be used, either alone or in combination, to indicate the frame structure.

Now referring back to FIG. 4, the method 400 may optionally include determining in step 401 the availability of an unlicensed carrier in the unlicensed spectrum (whether the unlicensed carrier is available) and reserving a period on the unlicensed carrier if it is determined in step 402 that the unlicensed carrier is available. The reservation period may be the same as the reservation period described above.

In accordance with various embodiments described above, a viable method 400 is provided for indicating a frame structure applicable to transmissions in an unlicensed spectrum between communicating parties such that the transmissions may be performed in the unlicensed spectrum in accordance with the frame structure applicable to transmissions in the unlicensed spectrum.

FIG. 6 shows a schematic block diagram of an apparatus 600 for performing transmission between a base station and a terminal device according to a frame structure in an unlicensed spectrum in a wireless network according to an embodiment of the present disclosure. The wireless network supports communication over both licensed and unlicensed spectrum, meaning that the base station and the terminal device are capable of operating in both licensed and unlicensed spectrum. The apparatus 600 may be embodied in or as at least a part of a base station or a terminal device.

In particular, the device 600 includes a notification unit 610 and a transmission execution unit 620.

The notification unit 610 notifies information indicating the frame structure. The transmission execution unit 620 executes transmission between the base station and the terminal device on the unlicensed carrier in the unlicensed spectrum according to the frame structure.

In an embodiment, the notification unit 610 may be configured to notify information indicating a frame structure in a licensed carrier in a licensed spectrum.

In an alternative embodiment, the notification unit 610 may be configured to notify information indicating a frame structure in an unlicensed carrier.

In other embodiments, the information indicative of the frame structure may include any or any combination of the following group of information:
Information regarding the start of a downlink transmission;
Information regarding the end of a downlink transmission;
Information regarding the duration of the maximum permitted transmission period;
Information about the duration of the downlink transmission, and Information about unlicensed carriers.

In further embodiments, the group may include any or any combination of the following:
Information regarding the start of an uplink transmission,
Information regarding the end of an uplink transmission;
Information regarding the duration of an uplink transmission, and Information regarding the sum of the duration of a downlink transmission and the duration of an uplink transmission.

In yet another embodiment, the UL transmission may start at the boundary of a subframe following the subframe in which the uplink grant was received at the terminal device. Thus, information regarding the start of the UL transmission may not be included in the information indicating the frame structure.

In yet another embodiment, the notification unit 610 may be configured to notify information indicating the frame structure by reusing DCI format 1C.

In yet another embodiment, the notification unit 610 may be configured to notify information indicating the frame structure by using a new DCI format that includes a field containing information indicating the frame structure.

In alternative embodiments, the information indicating the frame structure may include any or any combination of the following group:
Information regarding the start of an uplink transmission,
Information regarding the end of an uplink transmission;
Information about the duration of an uplink transmission, and Information about the duration of the maximum transmission period allowed.

In another embodiment, the method may further include a determining unit 630 configured to determine the availability of an unlicensed carrier in the unlicensed spectrum, and a reserving unit 640 configured to reserve a period in the unlicensed carrier if the unlicensed carrier is determined to be available. In this embodiment, the group described in the above embodiment may further include information regarding the start of the reserved period and/or information regarding the end of the reserved period.

The above units 610-640 may be configured to implement corresponding operations or steps as described with reference to Figures 4-6. All features relating to the frame structure indication described above in relation to the method 400 are equally applicable to the apparatus 600 and therefore will not be detailed herein for the sake of brevity.

FIG. 7 is a schematic block diagram of an apparatus 700 for performing transmission between a base station and a terminal device according to a frame structure in an unlicensed spectrum in a wireless network according to an embodiment of the present disclosure. The wireless network supports communication over both licensed and unlicensed spectrum, meaning that the base station and the terminal device are capable of operating in both licensed and unlicensed spectrum. The apparatus 700 may be embodied in or as at least a part of a base station or a terminal device.

In FIG. 7, the units in the solid line blocks are required, while the units in the dashed line blocks are selectable (optional) depending on various embodiments of the present disclosure.

The device 700 comprises at least one processor 710, such as a data processor (DP) and at least one memory (MEM) coupled to the processor 710. The device 700 may further comprise a transmitter TX and a receiver RX 730 coupled to the processor 710 for establishing wireless communication with other devices. The MEM 720 stores a program (PROG) 740. The combination of the at least one processor 710 and the at least one MEM 720 may form a processing means 750 suitable for implementing some embodiments of the present disclosure.

PROG 740 may include instructions that, when executed on an associated processor 710, enable device 700 to operate in accordance with an embodiment of the present disclosure, for example to perform method 400, as described with reference to FIG. 4. Alternatively, processing means 750 may be adapted to implement some embodiments of the present disclosure, as described with reference to FIG. 4.

MEM 720 may be of any type suitable for the local technical environment and may be implemented using any suitable data storage technology, including, but not limited to, semiconductor-based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed and removable memory.

Processor 710 may be of any type suitable for the local technical environment, including, but not limited to, one or more general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs), and processors based on multi-core processor architectures.

The present disclosure may further provide a carrier comprising a computer program as described above, the carrier being one of an electrical signal, an optical signal, a radio signal, or a computer readable medium. The computer readable medium may be, for example, an optical compact disc, or an electronic memory device such as a random access memory (RAM) or a read only memory (ROM), flash memory, magnetic tape, a CD-ROM, a DVD, a Blu-ray disc, etc.

The techniques described herein may be implemented by a variety of means, such that an apparatus implementing one or more functions of a corresponding apparatus described with embodiments may include means for implementing one or more functions of a corresponding apparatus described with embodiments as well as prior art means, and may include separate means for each separate function, or means configured to perform two or more functions. For example, these techniques may be implemented in hardware (one or more devices), firmware (one or more devices), software (one or more modules), or a combination thereof. For firmware or software, the implementation may be via modules (e.g., procedures, functions, etc.) that perform the functions described herein.

The exemplary embodiments of the present specification have been described above with reference to block diagrams and flowcharts of methods and apparatus. It will be understood that each block of the block diagrams and flowchart diagrams, and combinations of blocks in the block diagrams and flowchart diagrams, respectively, can be implemented by various means, including computer program instructions. These computer program instructions may be loaded onto a general purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine such that the instructions, which execute on a computer or other programmable data processing apparatus, generate means for implementing the functions identified in the blocks or blocks of the flowcharts.

Although the specification contains many specific implementation details, these should not be construed as a limitation on the scope of the implementation or what may be claimed, but rather as a description of features specific to a particular embodiment of a particular implementation. Some features described in the context of separate embodiments may also be implemented in combination in a single embodiment. Conversely, various features described in the context of a single embodiment may also be implemented in multiple embodiments separately or in any suitable sub-combination. Furthermore, although features may be described above as operating in some combinations, in some cases one or more features may be carved out of the claimed combination, even if originally claimed as such, and the claimed combination may be directed to a sub-combination or sub-combination variation.

It will be obvious to those skilled in the art that as technology advances, the concept of the present invention can be implemented in various ways. The above-mentioned embodiments are given to illustrate, not to limit the disclosure, and it is understood that modifications and variations are possible without departing from the concept (spirit) and scope of the present disclosure, as those skilled in the art will easily understand. Such modifications and variations are considered to be within the scope of the present disclosure and the appended claims. The scope of protection of the present disclosure is defined by the appended claims.

Claims (8)

A user equipment (UE),
means for receiving the first information and the second information from a base station;
The first information indicates a start position of a first transmission , and the first transmission has a PUCCH (Physical Uplink Control Channel);
a relative starting position of the second transmission with respect to the first transmission based on the second information;
the relative starting position begins after a first channel is sensed as idle;
Also, the relative start position precedes the start position of the first transmission ,
A UE having means for performing the first transmission and the second transmission on the first channel. The UE of claim 1 , wherein the starting position of the first transmission is indicated by the first information in symbols in the time domain. means for receiving third information indicating that the first n subframes in the subframe are occupied by downlink transmission;
other symbols in the subframe are unoccupied.
The UE of claim 1. The UE of claim 3, wherein the third information is received by Downlink Control Information (DCI). A base station,
Means for transmitting the first information and the second information to a user equipment (UE);
The first information indicates a start position of a first transmission , and the first transmission has a PUCCH (Physical Uplink Control Channel);
a relative starting position of the second transmission with respect to the first transmission based on the second information;
the relative starting position begins after a first channel is sensed as idle;
Also, the relative start position precedes the start position of the first transmission ,
A base station having means for receiving the first transmission and the second transmission on the first channel. the starting position of the first transmission is indicated by the first information in symbols in the time domain.
The base station according to claim 5. means for transmitting third information indicating that the first n subframes in the subframe are occupied by downlink transmission;
other symbols in the subframe are unoccupied.
The base station according to claim 5. The third information is transmitted by Downlink Control Information (DCI);
The base station according to claim 7.

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