Wireless data transmission

Abstract

The present invention relates to wireless data transmission. A device determines the availability of a scheduled serving cell before data communication and notifies the device of the determined availability of the scheduled serving cell. Depending on the determined availability, the device is controlled to perform data communication on the scheduled serving cell or another available serving cell. In this way, an unfinished data communication (e.g., retransmission of a data block in an uplink or downlink HARQ process) can continue on an available serving cell, thereby avoiding large transmission delays and throughput losses in a wireless communication system.

Description

[0001] This divisional patent application is a divisional application of the invention patent application with international application number PCT / US2016 / 013983, international filing date January 20, 2016, and China national stage application number 201680008129.4, titled "Wireless Data Transmission". Technical Field

[0002] The non-limiting and exemplary embodiments of the present disclosure generally relate to wireless communication, and more particularly to methods and apparatuses for data transmission in wireless communication. Background Art

[0003] In wireless communication, the demand for high data rates is constantly increasing, and Long Term Evolution (LTE) developed by the 3rd Generation Partnership Project (3GPP) has proven to be an extremely successful platform to meet such demands. LTE systems are designed to operate in dedicated and licensed frequency bands to avoid interfering with other systems and to ensure meeting communication performance. However, due to the increasing demand for high data rates and the decreasing availability of licensed frequency resources, more and more cellular network operators are considering using unlicensed spectrum as a supplementary tool to increase their service offerings.

[0004] One way to use unlicensed frequency bands is called "Licensed Assisted Access (LAA)", where the utilization of unlicensed frequency bands is controlled by licensed frequency bands. LTE LAA is a topic to be studied in 3GPP Advanced LTE Release 13 and above. The goal of LTE LAA is to consider uplink and downlink or pure downlink transmissions in unlicensed spectrum, investigate the basic aspects of operator-controlled non-standalone deployment of LTE in unlicensed spectrum, to further improve network throughput and provide offloading capabilities to meet the demand for increasing communication traffic.

[0005] In particular, LTE LAA can use Carrier Aggregation (CA) to aggregate carriers in unlicensed spectrum (e.g., using unlicensed carriers as supplementary downlinks or component carriers). In this case, the primary cell (also known as PCell, primary carrier, or primary component carrier) for an LTE Frequency Division Duplexing (FDD) or Time Division Duplexing (TDD) system can always operate in the licensed frequency band to carry control signaling, mobility management, and data, while one or more secondary cells (also referred to herein as SCell, secondary carrier, or secondary component carrier) in the unlicensed frequency band can provide downlink (DL) and / or uplink (UL) data transmission for opportunistic capacity improvement. Summary of the Invention

[0006] Unlicensed bands are shared by various wireless devices and networks rather than dedicated to a specific use. Therefore, for systems operating in unlicensed bands, co-channel interference from other wireless systems must be addressed. To mitigate the interference problem, the listen-before-talk (LBT) feature has been introduced in systems operating in unlicensed bands and has been made mandatory in some countries / regions. For LTE LAA, this feature has also been agreed upon in the 3GPP RAN1#78bis meeting, and the physical layer design of LTE LAA should take the LBT feature into account. In particular, the LTE evolved Node B (eNB) or user equipment (UE) should measure the unlicensed spectrum before transmitting in the unlicensed spectrum.

[0007] The introduction of the LBT mechanism may have an impact on data transmission, especially on the hybrid automatic repeat request (HARQ) performance of LAA, because the availability of transmission opportunities on the unlicensed band cannot be guaranteed. Ongoing data transmissions such as HARQ processes may be interrupted due to the need for an idle period or the unavailability of the operating channel after a clear channel assessment (CCA) check. When the unlicensed channel is heavily loaded, data transmission interruptions may occur frequently, and the retransmission of data blocks in the HARQ process may be delayed for a long time.

[0008] According to various embodiments of the subject matter described herein, this problem can be alleviated by allowing a device to determine the availability of a scheduled serving cell before data communication and notifying other devices of the determined availability of the scheduled serving cell. Depending on the determined availability, the device is controlled to perform data communication on the scheduled serving cell or an available serving cell. In one embodiment of the subject matter described herein, a first serving cell may operate in a licensed band, while a second serving cell may operate in an unlicensed band.

[0009] In this way, even if the scheduled serving cell operates in the unlicensed band and data transmission is interrupted due to the unavailability of transmission opportunities on the unlicensed band (e.g., an incomplete uplink or downlink data transmission), the retransmission of data blocks in the uplink or downlink HARQ process can continue on another available serving cell. Thus, large transmission delays and throughput losses in the wireless communication system can be avoided.

[0010] This summary is provided to introduce some concepts in a simplified form. These concepts will be further described in the following detailed description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] By way of example and not limitation, some embodiments of the subject matter described herein are illustrated in the accompanying drawings, in which like reference numerals indicate like elements, and in which:

[0012] Figure 1 A block diagram of an apparatus according to one embodiment of the subject matter described herein is illustrated;

[0013] Figure 2a A block diagram of an environment in which embodiments of the subject matter described herein may be implemented is illustrated;

[0014] Figure 2b A schematic diagram showing discontinuous transmission on an unlicensed frequency band is illustrated;

[0015] Figure 3 A flowchart of a method for wireless communication according to one embodiment of the subject matter described herein is illustrated;

[0016] Figure 4a A schematic diagram showing continuing an unfinished data transmission in a serving cell that schedules data transmission is illustrated;

[0017] Figure 4b A schematic diagram showing continuing an unfinished data transmission in another available serving cell is illustrated;

[0018] Figure 5 A flowchart of a method for wireless communication according to another embodiment of the subject matter described herein is illustrated;

[0019] Figure 6 A block diagram of an apparatus for wireless communication according to one embodiment of the subject matter described herein is illustrated; and

[0020] Figure 7 A block diagram of an apparatus for wireless communication according to another embodiment of the subject matter described herein is illustrated. DETAILED DESCRIPTION

[0021] The subject matter described herein will now be discussed with reference to several example embodiments. It should be understood that these embodiments are discussed only for the purpose of enabling those skilled in the art to better understand and thereby implement the subject matter described herein, and do not impose any limitation on the scope of the subject matter.

[0022] As used herein, the term "base station" (BS) may represent a Node B (Node B or NB), evolved Node B (eNodeB or eNB), remote radio unit (RRU), radio head (RH), remote radio head (RRH), relay, low power node (such as femto, pico), etc.

[0023] As used herein, the term "user equipment" (UE) refers to any device capable of communicating with a BS. By way of example, a UE may include a terminal, a mobile terminal (MT), a subscriber station (SS), a portable subscriber station (PSS), a mobile station (MS), or an access terminal (AT). Specifically, some examples of a UE include devices that can operate in an unlicensed frequency band.

[0024] As used herein, the term "comprising" and variations thereof are to be taken as an open term, meaning "including but not limited to". The term "based on" is to be taken as "at least partially based on". The terms "one embodiment" and "an embodiment" are to be taken as "at least one embodiment". The term "another embodiment" is to be taken as "at least one other embodiment". Other explicit or implicit definitions may be included hereinafter.

[0025] Figure 1 A block diagram of a device 100 in accordance with one embodiment of the subject matter described herein is illustrated. In one embodiment, the device 100 can be a UE, which can be any device having wireless communication capabilities, such as a mobile phone, a portable digital assistant (PDA), a pager, a mobile computer, a mobile television, a gaming device, a laptop computer, a tablet computer, a camera, a video camera, a GPS device, and other types of voice and text communication systems. Fixed devices can similarly readily use the embodiments of the subject matter described herein.

[0026] As shown, the device 100 includes one or more antennas 112 operable to communicate with a transmitter 114 and a receiver 116. Using these antennas, the device 100 can perform cellular communication with one or more devices such as a BS or other UEs. Specifically, the device 100 can be configured to operate in a licensed frequency band or an unlicensed frequency band, and can be configured to perform LBT (e.g., for contention-based access) when operating in an unlicensed frequency band.

[0027] The device 100 further includes at least one controller 120. It should be understood that the controller 120 includes the circuitry or logic required to implement the functions of the device 100. For example, the controller 120 may include a digital signal processor, a microprocessor, an A / D converter, a D / A converter, and / or any other suitable circuitry. The control and signal processing functions of the device 100 are allocated according to the respective capabilities of these devices.

[0028] Optionally, the device 100 may further include a user interface, which may include, for example, a ringer 122, a speaker 124, a microphone 126, a display 128, and an input interface 130, and all of the above devices are coupled to the controller 120. The device 100 may further include a camera module 136 for capturing static and / or dynamic images.

[0029] Device 100 may further include a battery 134 such as a vibrating battery pack for powering the various circuits required to operate device 100 and for alternatively providing mechanical vibrations as a detectable output. In one embodiment, device 100 may further include a user identity module (UIM) 138. The UIM 138 is generally a memory device with a built-in processor. The UIM 138 may include a subscriber identity module (SIM), a universal integrated circuit card (UICC), a universal subscriber identity module (USIM), or a removable user identity module (R-UIM), etc. The UIM 138 may include card connection detection means according to various embodiments of the subject matter described herein.

[0030] Device 100 further includes a memory. For example, device 100 may include volatile memory 140, such as volatile random access memory (RAM) included in a cache region for temporarily storing data. Device 100 may further include other non-volatile memories 142 that may be embedded and / or removable. Alternatively or additionally, the non-volatile memory 142 may include EEPROM and flash memory. The memory 140 may store multiple pieces of information and any item of data used by device 100 to implement the functions of device 100. For example, the memory may contain machine-executable instructions that, when executed, cause the controller 120 to implement the methods described below.

[0031] It should be understood that Figure 1 the block diagrams shown herein are for illustrative purposes only and do not impose any limitation on the scope of the subject matter described herein. In some cases, some devices may be added or removed as needed.

[0032] Figure 2a illustrates an environment of a wireless communication system in which some embodiments of the subject matter described herein may be implemented. As Figure 2a shown, one or more UEs may communicate with a BS 200 such as an evolved Node B (eNodeB). In this example, three UEs 210, 220, and 230 are shown, but this is for illustrative purposes only and does not limit the number of UEs. Any suitable number of UEs may communicate with the BS 200. In one embodiment, one or more of the UEs 210, 220, and 230 may be implemented as, for example, Figure 1 the device 100 shown herein. Additionally, UEs may communicate directly with another UE, for example, via device-to-device (D2D) communication. In this example, the D2D paired devices are illustrated by UEs 220 and 230.

[0033] The communication between UEs 210, 220, and 230 and BS 200, and between UE 211 and BS 201, can be performed according to any suitable communication protocol, including but not limited to first-generation (1G), second-generation (2G), 2.5G, 2.75G, third-generation (3G), fourth-generation (4G) communication protocols, and / or any other protocol currently known or to be developed in the future. Although for illustrative purposes, in some embodiments of the present disclosure, UEs 210, 220, and 230 and BS 200 may communicate using 3GPP LTE technology, the embodiments of the present disclosure are not limited to such network scenarios.

[0034] Figure 2a The wireless communication system shown in can be deployed in both licensed and unlicensed frequency bands. The unlicensed frequency band can be shared with various other wireless systems (such as Wi-Fi systems) in a contention-based manner. As Figure 2a shown, in the case of carrier aggregation (CA), for example, UE 210 is configured with more than one serving cell (i.e., one pCell and several SCell). Some serving cells can be operated within the licensed frequency band, while other serving cells can be operated within the unlicensed frequency band.

[0035] As described above, the introduction of the LBT mechanism may have an impact on data communication, especially on the uplink and downlink hybrid automatic repeat request (HARQ) performance of LAA. In downlink transmission, for example, before the downlink transmission or burst transmission of the operating carrier of the serving cell, BS 200 must perform a CCA check through energy detection. If the energy level in the carrier channel exceeds a predefined threshold, the serving cell is considered unavailable because the corresponding carrier channel is occupied; otherwise, it can transmit data immediately or in a subsequent frame period. After each data transmission, BS200 always needs to perform CCA at the end of the idle period. Therefore, discontinuous transmission of LAA is a basic feature because the availability of transmission opportunities on the unlicensed frequency band cannot be guaranteed. This results in ongoing data transmissions (especially for HARQ processes) being interrupted due to the requirements of the idle period or the unavailability of the scheduled serving cell after the CCA check. This problem will be described in detail with reference to Figure 2b the example of.

[0036] Figure 2b illustrates a schematic diagram showing discontinuous transmission on the unlicensed frequency band in a HARQ process. As Figure 2bAs shown, the first and second serving cells are configured by BS 200 for UE 210, where the first serving cell can be a PCell or SCell operating in a licensed band, and the second cell can be an SCell operating in an unlicensed band. The second serving cell (corresponding to an SCell, secondary component carrier, or secondary cell) is scheduled by the first serving cell (corresponding to a PCell, primary component carrier, or primary cell) via a Physical Downlink Control Channel (PDCCH). The initial transmission of a data block is scheduled to be performed in the second serving cell during a time period such as a subframe (1 ms). Before retransmitting a data block that was not successfully received on the receiver side, BS 200 detects the availability of the second serving cell by performing a CCA check on the component carrier of the second serving cell. Due to the unavailability of the unlicensed band in the next time period (e.g., the unlicensed band may be occupied by a Wi-Fi system), the retransmission of the data block cannot be sent until the second serving cell is available again. The data transmission of UE 210 may suffer from large transmission delays, and the system performance may severely degrade due to throughput loss.

[0037] Embodiments of the subject matter described herein are directed to providing a solution that at least partially addresses the above problems.

[0038] Reference Figures 3 - 7 , various embodiments of the subject matter described herein are elaborated.

[0039] Figure 3 FIG. illustrates a flowchart of an exemplary method 300 for data transmission in wireless communication according to one embodiment of the subject matter described herein.

[0040] It should be understood that method 300 can be implemented by a network node or a device for transferring data blocks with another device in a wireless communication system (e.g., BS 200 shown in FIG. 2). In the embodiment illustrated as Figure 3 , the data transmission is scheduled by the first serving cell and transmitted by the second serving cell.

[0041] As Figure 3As shown, in step S310, method 300 is entered, where the BS 200 determines the availability of the second serving cell before data transmission. In step S320, the BS 200 notifies a device such as the UE 210 of the determined availability of the second serving cell. Based on the determined availability of the second serving cell, in step S330, the BS 200 performs data communication on one of the second serving cell and the third serving cell. Specifically, if the scheduled second serving cell is available, the BS 200 performs data communication in the second serving cell; otherwise, the BS 200 schedules data communication to be performed in the third serving cell. Since the other party of the data communication such as the UE 210 is aware of the availability of the scheduled second serving cell, this other party can know whether the corresponding data communication should be performed in the second serving cell or in the third serving cell.

[0042] According to an embodiment of the subject matter disclosed herein, the first serving cell may operate in a licensed band, while the second cell may operate in an unlicensed band. The second serving cell, which may be an SCell (also referred to as a secondary component carrier, or secondary cell), is scheduled by the first serving cell, which may be a PCell (also referred to as a primary component carrier, or primary cell) or a licensed SCell via PDCCH.

[0043] To illustrate the inventive concept of the subject matter disclosed herein, various embodiments will be described with reference to the case of the downlink HARQ process of LTE LAA. However, those skilled in the art can understand that such a case of the downlink HARQ process is only a non-limiting example for illustrative purposes and should not be construed as any limitation on the claimed scope. For example, some embodiments of the subject matter disclosed herein may be applicable to uplink data transmission (e.g., uplink HARQ process) between the BS and the UE or even D2D transmission between UEs (with appropriate modifications in signaling communication).

[0044] Figure 4a Schematic diagram 400 is illustrated showing the continuation of an unfinished data transmission in the serving cell scheduling the data transmission.

[0045] As Figure 4a shown, for example, the data communication of an unfinished HARQ process on the scheduled second serving cell can only be continued in the corresponding scheduling party, the first serving cell. In other words, as Figure 3The described third serving cell may be preconfigured as a first serving cell that schedules data communication of a second serving cell. When the BS 200 determines that the second serving cell is not available for subsequent data communication, the BS 200 may continue the unfinished data communication (e.g., unfinished UL or DL HARQ process) in the first serving cell.

[0046] Solution 1

[0047] According to an embodiment of the subject matter disclosed herein, Figure 3 step S320 in may be implemented by indicating the availability of the determined second serving cell in downlink control signaling sent from the first serving cell to the device.

[0048] In an exemplary implementation, a 1-bit Channel Availability Indicator (CAI) may be introduced in the DL control signaling to indicate whether the second serving cell is available in the current time period (e.g., current subframe). For example, the DL control signaling may be a DL grant signaling for a downlink HARQ process or a UL grant signaling for an uplink HARQ process.

[0049] In a downlink HARQ process, for example, if the second serving cell is available, the CAI may be set to, for example, 1, and the DL grant including the CAI may be used for cross-carrier scheduling of Physical Downlink Shared Channel (PDSCH) transmission on the second serving cell. If the second serving cell is not available, the CAI may be set to, for example, 0, and the DL grant including the CAI may be used for scheduling the PDSCH on the same carrier as the DL grant (i.e., the first serving cell) to perform those subsequent HARQ processes that were unfinished in the second serving cell. The scheduled second serving cell is indicated by the Carrier Indicator Field (CIF) in the DL grant transmitted from the scheduling serving cell. Advantageously, in some examples, when these subsequent HARQ processes are continued in the first serving cell, the HARQ process numbers of these HARQ processes may remain unchanged.

[0050] In this implementation, the BS 200 may determine the availability of each unlicensed cell through a CCA check and use the CAI in the DL grant signaling to indicate it. If the second serving cell is available, the BS 200 may set the CAI to, for example, 1 and transmit the PDSCH on the second serving cell; otherwise, the BS 200 may set the CAI to, for example, 0 and transmit the PDSCH on the scheduling serving cell. In this way, the DL retransmission that was unfinished in the second serving cell is continued in the PDSCH of the first scheduling serving cell.

[0051] A receiving device such as UE 210 does not need to perform a CCA check for each unlicensed cellular cell. After detecting a DL grant on the first serving cellular cell, UE 210 obtains the availability of the second serving cellular cell via the CAI. If the CAI is set to, for example, 1, UE 210 may attempt to receive PDSCH transmissions on the second serving cellular cell; otherwise, if the CAI is set to, for example, 0, UE 210 may attempt to receive PDSCH transmissions on the first serving cellular cell. Since the HARQ process number remains unchanged, when continuing an unfinished HARQ process of the second serving cellular cell in the first serving cellular cell, UE 210 can identify the corresponding HARQ process of the PDSCH retransmitted on the first serving cellular cell and attempt to combine the received soft bits with the same HARQ process number.

[0052] Those skilled in the art can understand that, in addition to using UL grants to indicate the CAI, the operations of BS200 and UE 210 in the uplink HARQ process are similar to those in the downlink HARQ process described above. Therefore, for the sake of brevity, the detailed description of the operations in the uplink HARQ process is omitted.

[0053] Solution 2

[0054] According to an embodiment of the subject matter disclosed herein, Figure 3 step S320 in may be implemented by indicating the availability of the determined second serving cellular cell via physical layer signaling. The physical layer signaling may include at least a bitmap corresponding to the availability of all serving cellular cells operating on the unlicensed frequency band.

[0055] In an exemplary implementation, layer 1 (physical layer) signaling referred to as Channel Availability Signaling (CAS) may be introduced to carry a bitmap corresponding to the availability of all serving cells operating on an unlicensed frequency band. The bitmap may also correspond to each SCell, regardless of whether the SCell operates on a licensed frequency band or an unlicensed frequency band. CAS may have the same length as Downlink Control Information (DCI) format 1C with a new Radio Network Temporary Identity (RNTI), which is common to all UEs served by BS 200 and configured / indicated in Radio Resource Control (RRC) signaling. The CAS signal may be sent in the PCell common search space in a fixed subframe or in a specified subframe configured by RRC signaling within each frame period or RRC signaling configuration period. In an advantageous implementation, the period during which CAS is updated from BS 200 to a UE (such as UE 210) may be aligned with the requirements of LBT. Once BS 200 obtains the availability of the serving cells operating in the unlicensed frequency band, BS 200 notifies such availability information in CAS via physical layer signaling. The UE (e.g., UE 210) is aware of the period during which CAS is notified, and the UE is able to detect the CAS content. Based on the CAS, UE 210 may obtain the availability of a second serving cell, and then UE 210 may determine based on the availability of the second serving cell whether subsequent data transmissions will continue in one of the first serving cell and the second serving cell.

[0056] In this implementation, BS 200 may determine the availability of each unlicensed cell through CCA checking and indicate it via CAS signaling. In the downlink HARQ process, for example, if a second serving cell is available, the corresponding bit value in the CAS may be set to, for example, 1, and BS 200 will transmit the PDSCH on the second serving cell based on the determined availability; otherwise, the corresponding bit value in the CAS is set to, for example, 0, and BS 200 will transmit the PDSCH on the first serving cell. In this way, DL retransmissions that were not completed in the second serving cell continue in the PDSCH of the first serving cell. Advantageously, in some examples, when these subsequent HARQ processes are continued in the first serving cell, the HARQ process numbers of these HARQ processes may remain unchanged.

[0057] The receiving device (e.g., UE 210) does not need to perform a CCA check for each unlicensed cell. After detecting the CAS signaling in the PCell common search space, UE 210 obtains the availability of each serving cell. If a serving cell (e.g., the second serving cell) is cross-carrier scheduled by the first serving cell and the bit value in the CAS signaling corresponding to this serving cell is set to 1, then UE 210 may attempt to receive a PDSCH transmission on the second serving cell; otherwise, UE 210 may attempt to receive a PDSCH transmission on the first serving cell. Since the HARQ process number remains unchanged, when continuing an unfinished HARQ process of the second cell in the first serving cell, UE 210 may determine the corresponding HARQ process of the PDSCH retransmitted in the first serving cell and then attempt to combine the received soft bits with the same HARQ process number.

[0058] Those skilled in the art can understand that the operations of BS 200 and UE 210 in the uplink HARQ process are similar to those in the downlink HARQ process described above. Therefore, for the sake of brevity, the detailed description of the operations in the uplink HARQ process is omitted.

[0059] Figure 4b Fig. 410 illustrates a schematic diagram showing the continuation of an unfinished data transmission in another available serving cell.

[0060] As Figure 4b shown, data communication (e.g., an unfinished HARQ process on the unlicensed scheduled second serving cell) may be continued in another available serving cell (i.e., the third serving cell described as such Figure 3 may be designated as an available serving cell). The designated available serving cell may be the first serving cell or another serving cell that is different from or fixed to the PCell from the first serving cell, but Figure 4b for the sake of simplicity, the third serving cell is shown as a cell different from the first serving cell. When BS 200 determines that the second serving cell is not available for subsequent data communication, BS 200 may continue the unfinished data communication (e.g., an unfinished UL or DL HARQ process) in the designated third serving cell.

[0061] Solution 3

[0062] According to an embodiment of the subject matter disclosed herein, Figure 3Step S320 in [the above] can be implemented by indicating the availability of the determined second serving cell in the downlink control signaling sent from the first serving cell to the device. If the second serving cell is unavailable, the downlink control signaling includes a carrier index for indicating the specified third serving cell.

[0063] In one exemplary implementation, a new field called the Available Carrier Index (ACI) can be introduced in the DL control signaling. For example, the DL control signaling can be the DL grant signaling for the downlink HARQ process or the UL grant signaling for the uplink HARQ process. The ACI field can have the same bit length as the bit length of the CIF of the DL control signaling. In the downlink HARQ process, for example, if the scheduled second serving cell indexed by the CIF is available, the ACI can be set to a default value (such as the same value as the CIF or a zero value). Thus, this DL grant is used for cross-carrier scheduling of PDSCH transmission on the second serving cell indexed by the CIF. If the scheduled second serving cell indexed by the CIF is unavailable and another serving cell is available, the ACI can be set to the index specifying this available serving cell (i.e., the third serving cell), and this DL grant is used to cross-carrier schedule PDSCH transmission on the serving cell specified by the ACI to continue those uncompleted HARQ processes of the second serving cell indexed by the CIF. Advantageously, in some examples, when these subsequent HARQ processes are continued in the first serving cell, the HARQ process numbers of these HARQ processes can remain unchanged.

[0064] According to this exemplary implementation, in the downlink HARQ process, for example, the BS 200 can determine the availability of each unlicensed cell through CCA checking. If the scheduled second serving cell indexed by the CIF is available, the BS 200 can set the ACI in the DL grant signaling to a default value (e.g., the same value as the CIF or a zero value), and transmit the PDSCH on the scheduled second serving cell indexed by the CIF. If the scheduled second serving cell indexed by the CIF is unavailable and another serving cell is available, the BS 200 can use the ACI in the DL grant to indicate the index of the specified available serving cell (i.e., the third serving cell), and transmit the PDSCH on the specified available serving cell.

[0065] The receiving device (e.g., UE 210) does not need to perform a CCA check for each unlicensed cell. After detecting a DL grant in the first serving cell, UE 210 may first check the CIF and ACI. If the ACI is the default value (e.g., the same value as the CIF or a zero value), the UE may attempt to receive a PDSCH transmission on the scheduled second serving cell indexed by the CIF. If the ACI specifies the carrier index of a third serving cell, the UE may attempt to receive a PDSCH transmission on the third serving cell indexed by the ACI. Since the HARQ process number remains unchanged, when continuing an unfinished HARQ process of the scheduled cell in the available third serving cell, the UE can identify the corresponding HARQ process of the retransmitted PDSCH and attempt to combine the received soft bits with the same HARQ process number.

[0066] Those skilled in the art can understand that, except for using UL grants to indicate the ACI, the operations of BS200 and UE 210 in the uplink HARQ process are similar to those in the downlink HARQ process described above. Therefore, for the sake of brevity, the detailed description of the operations in the uplink HARQ process is omitted.

[0067] Solution 4

[0068] According to an embodiment of the subject matter disclosed herein, method 300 may further include another step (not shown in Figure 3 ), in the scheduling process from the first serving cell to the second serving cell, where BS 200 may indicate the carrier index of the third serving cell to the device via higher layer signaling from the first serving cell. Figure 3 The step S320 in

[0069] In an exemplary implementation, layer 1 (physical layer) signaling called Channel Availability Signaling (CAS) may be introduced to carry a bitmap corresponding to the availability of all serving cells operating on an unlicensed frequency band. Alternatively, the bitmap may also correspond to each SCell (regardless of the corresponding licensed or unlicensed frequency band). CAS may have the same length as Downlink Control Information (DCI) format 1C with a Cyclic Redundancy Check (CRC) scrambled by a new Radio Network Temporary Identifier (RNTI), which is common to all UEs served by BS 200 and configured / indicated in Radio Resource Control (RRC) signaling. The CAS signal may be sent in the PCell common search space in a fixed subframe or in a specified subframe configured by RRC signaling within each frame period or RRC signaling configuration period. In an advantageous implementation, the period during which CAS is updated from BS 200 to a UE (such as UE 210) may be aligned with the requirements of LBT.

[0070] In this implementation, during the cross-carrier scheduling process from a first serving cell to a second serving cell, a new field called Backup Carrier Index (BCI) is introduced in the RRC signaling. During the cross-carrier scheduling configuration for the scheduled second serving cell, the carrier index of the backup serving cell may be notified to a device such as UE 210. In some examples, for reliability purposes, the BCI may be the carrier index corresponding to a licensed carrier. When the second serving cell is configured by RRC signaling for cross-carrier scheduling, the BCI field may be added to the corresponding RRC signaling to indicate the index of its backup carrier. The BCI may be retained even if the serving cell on the licensed frequency band is configured for cross-carrier scheduling. In some examples, the PCell may always be designated as the backup serving cell. In this way, the BCI field in the RRC signaling for cross-carrier scheduling may be retained or not needed.

[0071] According to this implementation, BS 200 may determine the availability of each unlicensed cell through CCA check and indicate it through CAS in the physical layer signaling. In the downlink HARQ process, for example, if the second serving cell is available, the corresponding bit value in the CAS may be set to, for example, 1, and BS 200 may transmit PDSCH on this scheduled second serving cell; otherwise, the corresponding bit value in the CAS may be set to, for example, 0, and BS 200 may transmit PDSCH on the backup carrier indexed by BCI to complete the outstanding HARQ process.

[0072] The receiving device (e.g., UE 210) does not need to perform a CCA check for each unlicensed cell. After detecting the CAS signaling in the PCell common search space, UE 210 can know the availability of each serving cell. In the case where a SCell (e.g., the second serving cell) is cross-carrier scheduled by another serving cell (e.g., the first serving cell and the bit value in the CAS signaling corresponding to the second serving cell is set to, for example, 1), UE 210 can attempt to receive PDSCH transmission on this scheduled second serving cell; otherwise, UE 210 can attempt to receive PDSCH transmission on its corresponding alternative carrier indexed by the BCI. Since the HARQ process number remains unchanged, UE 210 can determine the corresponding HARQ process of the PDSCH retransmitted on the alternative carrier and attempt to combine the received soft bits with the same HARQ process number.

[0073] Those skilled in the art can understand that the operations of BS 200 and UE 210 in the uplink HARQ process are similar to those in the downlink HARQ process, and therefore, for the sake of brevity, the detailed description thereof is omitted here.

[0074] Figure 5 A flowchart of a method 500 for wireless communication according to another embodiment of the subject matter described herein is illustrated.

[0075] It should be understood that method 500 can be implemented by a UE or a device for transmitting each data block to another device (e.g., UE 210 shown in FIG. 2) in a wireless communication system. In Figure 5 the illustrated embodiment, data communication is scheduled from the first serving cell.

[0076] As Figure 5 shown, method 500 is entered at step S510, where UE 210 obtains the availability of the second serving cell. At step S520, UE 210 performs data communication on one of the second serving cell and the third serving cell based on the obtained availability of the second serving cell. According to one embodiment of the subject matter disclosed herein, the first serving cell can operate in a licensed band, while the second serving cell can operate in an unlicensed band.

[0077] According to an embodiment of the subject matter disclosed herein, the third serving cell may be the first serving cell. In one exemplary implementation, the UE 210 may obtain the availability of the second serving cell by receiving downlink control signaling from the first serving cell that includes an indicator of the availability of the second serving cell. In another exemplary implementation, the UE 210 may obtain the availability of the second serving cell by receiving physical layer signaling that includes a bitmap corresponding to at least the availability of all serving cells operating on the unlicensed band.

[0078] According to an embodiment of the subject matter disclosed herein, the third serving cell is a designated available serving cell. In one exemplary implementation, the UE 210 may obtain the availability of the second serving cell by receiving downlink control signaling from the first serving cell that indicates the availability of the second serving cell. In the case where the second serving cell is unavailable, the downlink control signaling may include the carrier index of the third serving cell. In another exemplary implementation, the UE 210 may receive higher layer signaling that includes the carrier index of the third serving cell, and the UE 210 may obtain the availability of the second serving cell by receiving physical layer signaling that includes a bitmap corresponding to at least the availability of all serving cells operating on the unlicensed band.

[0079] Figure 6 FIG. shows a block diagram of an apparatus 600 for wireless communication according to an embodiment of the subject matter described herein. The apparatus 600 may be implemented as the BS 200 shown in FIG. 2 or at least a portion thereof. Alternatively or additionally, the apparatus 600 may be implemented as any other suitable entity in a wireless communication system. The apparatus 600 may be operable to perform the example method 300 described with reference to Figure 3 and any other possible processes or methods. It should also be understood that the method 300 described with reference to Figure 3 is not necessarily performed only by the apparatus 600. At least some steps of the method 300 may be performed by one or more other entities, such as a specific functional entity in a wireless communication system.

[0080] As Figure 6 shown, the apparatus 600 includes a determination unit 610, a first transmission unit 620, and a data transceiver unit 630. The transmission unit 610 and the data transceiver unit 620 are functional modules for performing the functions of the apparatus 600 related to the embodiments of the subject matter disclosed herein, rather than specific physical transmitters or transceivers. The first transmission unit 620 and the data transceiver unit 630 may be implemented by a radio transceiver, an antenna array, and associated processing and memory circuitry to perform control signaling and data transmission.

[0081] The determination unit 610 is configured to determine the availability of a second serving cell, which is scheduled from a first serving cell, for example, during a HARQ process, to perform data communication. The first serving cell can be operated in a licensed band, and the scheduled second serving cell can be operated in an unlicensed band. The first transmission unit 620 is configured to notify the UE of the determined availability of the second serving cell. And the data transceiver unit 630 is configured to perform data communication on one of the second serving cell and a third serving cell based on the availability of the second serving cell determined by the determination unit 610.

[0082] According to one embodiment of the subject matter disclosed herein, the third serving cell can be the first serving cell that schedules the second serving cell. In an exemplary implementation, the first transmission unit 620 can be configured to transmit downlink control signaling including an indicator indicating the availability of the second serving cell to the UE via the first serving cell. In another exemplary implementation, the first transmission unit 620 can be configured to transmit a physical layer signaling including a bitmap corresponding at least to the availability of all serving cells operating on the unlicensed band to the UE.

[0083] According to one embodiment of the subject matter disclosed herein, the third serving cell is a designated available serving cell. In an exemplary implementation, the first transmission unit 620 is configured to transmit downlink control signaling including an available carrier index to the UE via the first serving cell, thereby designating the available serving cell for performing subsequent data transmission. In the case where the second serving cell is unavailable, the available carrier index indicates the carrier index of the third serving cell. In another exemplary implementation, the apparatus 600 can include a second transmission unit (not shown in Figure 6 configured to transmit a high layer signaling including the carrier index of the third serving cell to the UE via the first serving cell. In this implementation, the first transmission unit 620 can be configured to transmit a physical layer signaling including a bitmap corresponding at least to the availability of all serving cells operating on the unlicensed band.

[0084] As described above, the apparatus 600 can be used to improve measurements in both licensed and unlicensed bands.

[0085] Figure 7 A block diagram of an apparatus 700 for wireless communication according to another embodiment of the subject matter described herein is illustrated. The apparatus 700 can be implemented as the UE 210 shown in FIG. 2 or at least a part thereof. Alternatively or additionally, the apparatus 700 can be implemented as any other suitable entity in a wireless communication system. The apparatus 700 can operate to perform reference Figure 5The described exemplary method 500 and any other possible processes or methods. It should also be understood that the method 500 described with reference to Figure 5 is not necessarily performed only by the apparatus 700. At least some steps of the method 500 may be performed by one or more other entities, such as specific functional entities in a wireless communication system.

[0086] As Figure 7 shown, the apparatus 700 includes an obtaining unit 710 and a data transceiver unit 720.

[0087] The obtaining unit 710 is configured to obtain the availability of a second serving cell. The data transceiver unit 720 is configured to perform data communication on one of the second serving cell and a third serving cell based on the availability of the second serving cell obtained by the obtaining unit 710. According to one embodiment of the subject matter disclosed herein, the first serving cell may operate in a licensed band, while the second serving cell may operate in an unlicensed band.

[0088] According to one embodiment of the subject matter disclosed herein, the third serving cell may be the first serving cell. In an exemplary implementation, the obtaining unit 710 may be configured to obtain the availability of the second serving cell by receiving downlink control signaling including an indicator indicating the availability of the second serving cell from the first serving cell. In another exemplary implementation, the obtaining unit 710 may be configured to obtain the availability of the second serving cell by receiving physical layer signaling including a bitmap corresponding at least to the availability of all serving cells operating on the unlicensed band.

[0089] According to one embodiment of the subject matter disclosed herein, the third serving cell is a designated available serving cell. In an exemplary implementation, the obtaining unit 710 may be configured to obtain the availability of the second serving cell by receiving downlink control signaling indicating the availability of the second serving cell from the first serving cell. In the case where the second serving cell is unavailable, the downlink control signaling may include the carrier index of the third serving cell. In another exemplary implementation, the UE 210 may include a receiving unit (not shown in Figure 7 configured to receive high layer signaling including the carrier index of the third serving cell. In this implementation, the obtaining unit 710 may be configured to obtain the availability of the second serving cell by receiving physical layer signaling including a bitmap corresponding at least to the availability of all serving cells operating on the unlicensed band.

[0090] It should be understood that although in some embodiments of the subject matter described herein, the methods and apparatuses are described in the context of a cellular system (particularly an LTE LAA system), the embodiments of the subject matter described herein are not limited thereto.

[0091] The modules / units included in apparatuses 600 and / or 700 can be implemented in various ways, including software, hardware, firmware, or any combination thereof. In one embodiment, software and / or firmware can be used to implement one or more units, such as machine-executable instructions stored on a storage medium. As a supplement or replacement to the machine-executable instructions, some or all of the units in apparatuses 600 and / or 700 can be implemented at least partially by one or more hardware logic components. By way of example and not limitation, illustrative types of hardware logic components that can be used include field-programmable gate arrays (FPGAs), application-specific integrated circuits (ASICs), application-specific standard products (ASSPs), systems-on-a-chip (SOCs), complex programmable logic devices (CPLDs), and the like.

[0092] In addition, some units or modules in apparatus 600 or 700 can be combined in some implementations. For example, in one embodiment, a single transceiver may be used to act as the transmitter unit 620 and the data transceiver unit 630 in apparatus 600 as discussed above. Similarly, a single transceiver can act as the acquisition unit 710 and the data transceiver unit 720 in apparatus 700 as discussed above.

[0093] In general, the various embodiments of the subject matter described herein can be implemented in hardware or special-purpose circuits, software, logic, or any combination thereof. Some aspects can be implemented in hardware, while other aspects can be implemented in firmware or software executable by a controller, microprocessor, or other computing device. Although the various aspects of the embodiments of the subject matter described herein are illustrated and described as block diagrams, flowcharts, or using some other graphical representation, it will be understood that the blocks, apparatuses, systems, techniques, or methods described herein can be implemented, by way of non-limiting example, in hardware, software, firmware, special-purpose circuits or logic, general-purpose hardware or controllers or other computing devices, or some combination thereof.

[0094] As an example, embodiments of the present subject matter may be described in the general context of machine-executable instructions, such as those included in program modules that are executed in a device on a target real or virtual processor. Generally, program modules include routines, programs, libraries, objects, classes, components, data structures, etc. that perform particular tasks or implement particular abstract data types. As described in the embodiments, the functionality of these program modules may be combined or split between these program modules. The machine-executable instructions for the various program modules may be executed locally or in a distributed device. In a distributed device, the program modules may be located in both local and remote storage media.

[0095] The program code for performing the methods of the subject matter described herein 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, when the processor or controller executes the program code, the functions / operations specified in the flowchart and / or block diagram are implemented. The program code may execute entirely on the machine, partially on the machine, as a stand-alone software package, partially on the machine and partially on a remote machine, or entirely on a remote machine or server.

[0096] In the context of the present disclosure, a machine-readable medium may be any tangible medium that can contain or store a program for use by or in connection with an instruction execution system, apparatus, or device. A machine-readable medium may be a machine-readable signal medium or a machine-readable storage medium. A machine-readable medium may include, but is 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 a machine-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 optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

[0097] Moreover, although the operations are depicted in a particular order, this should not be construed as requiring that the operations be performed in the particular order shown or in sequential order, or that all of the illustrated operations be performed to achieve the desired result. In some cases, multitasking and parallel processing may be advantageous. Similarly, although several specific implementation details are included in the foregoing discussion, these should not be construed as limitations on the scope of the subject matter described herein, but rather as descriptions of specific features of particular embodiments. Certain features that are described in the context of separate embodiments may also be implemented in combination in a single embodiment. Conversely, the various features that are described in the context of a single embodiment may also be implemented separately in multiple embodiments or in any suitable subcombination.

[0098] Although the subject matter of this invention has been described in terms of structural features and / or methodological acts, it is to be understood that the subject matter 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

1. A method for wireless communication, comprising: Determining the availability of a second serving cell before data communication, wherein the second serving cell is scheduled by a first serving cell to perform the data communication; Notifying a device of the determined availability of the second serving cell via downlink control signaling; And Performing the data communication on one of the second serving cell or a third serving cell after determining the availability of the second serving cell, wherein in response to the second serving cell being available, performing the data communication on the second serving cell, and in response to the second serving cell being unavailable, performing communication on the third serving cell, wherein the third serving cell is configured as the first serving cell, and the third serving cell schedules the data communication of the second serving cell.

2. The method according to claim 1, wherein The first serving cell operates in a licensed band, while the second serving cell operates in an unlicensed band.

3. The method according to claim 1, wherein Further comprising instructing the first serving cell to schedule the second serving cell to perform the data communication via a Physical Downlink Control Channel (PDCCH).

4. The method according to claim 1, characterized in that Notifying the determined availability of the second serving cell includes indicating the availability of the second serving cell in downlink control signaling sent from the first serving cell to the device.

5. The method according to claim 4, wherein Due to the unavailability of the second serving cell, the downlink control signaling includes a carrier index of the third serving cell.

6. The method according to claim 1, wherein The data communication is transmitted using an uplink or downlink Hybrid Automatic Repeat reQuest (HARQ) process.

7. The method according to claim 1, wherein The availability of the second serving cell is indicated in a 1-bit Channel Availability Indicator (CAI).

8. A method for wireless communication, comprising: Determining the availability of a second serving cell before data communication, wherein the second serving cell is scheduled by a first serving cell to perform the data communication; Notifying a device of the determined availability of the second serving cell via Channel Availability Signaling (CAS), wherein the Channel Availability Signaling includes at least a bitmap corresponding to the availability of a plurality of serving cells operating in an unlicensed band; And Performing the data communication on one of the second serving cell or a third serving cell after determining the availability of the second serving cell, wherein in response to the second serving cell being available, performing the data communication on the second serving cell, and in response to the second serving cell being unavailable, performing communication on the third serving cell, wherein the third serving cell is configured as the first serving cell, and the third serving cell schedules the data communication of the second serving cell.

9. A method for performing data transmission of wireless communication from a user equipment, comprising: Determine the availability of a second serving cell before data communication, where the second serving cell is scheduled by a first serving cell to perform the data communication, and the availability of the second serving cell is indicated in a 1-bit Channel Availability Indicator (CAI) in downlink control signaling; Obtain the availability of a second serving cell before data communication; And Based on the obtained availability of the second serving cell, perform data communication on one of the second serving cell and a third serving cell, where in response to determining that the second serving cell is available, schedule a Physical Downlink Shared Channel (PDSCH) across carriers on the second serving cell, and in response to determining that the second serving cell is unavailable, schedule a Physical Downlink Shared Channel (PDSCH) across carriers on the third serving cell.

10. The method according to claim 9, characterized in that, The downlink control signaling includes downlink control signaling for one or more uplink or downlink Hybrid Automatic Repeat reQuest (HARQ) processes.

11. An apparatus for wireless communication, comprising: A determination unit configured to determine the availability of a second serving cell operating in an unlicensed band before data communication, where the second serving cell is scheduled by a first serving cell operating in a licensed band to perform the data communication; A first transmission unit configured to notify a User Equipment (UE) of the determined availability of the second serving cell through downlink control signaling; And A data transceiver unit configured to perform the data communication on one of the second serving cell or a third serving cell based on the obtained availability of the second serving cell, where in response to the second serving cell being available, perform the data communication on the second serving cell, and in response to the second serving cell being unavailable, perform communication on the third serving cell, where the third serving cell is a designated available serving cell, where the first transmission unit is configured to transmit downlink control signaling including an available carrier index via the first serving cell, and in the case where the second serving cell is unavailable, the available carrier index indicates the carrier index of the third serving cell.

12. The device according to claim 11, characterized in that, The availability of the second serving cell is indicated in a 1-bit Channel Availability Indicator (CAI).

13. The device according to claim 11, wherein The data communication is partly transmitted using the second serving cell and partly transmitted using the third serving cell.

14. The device according to claim 11, characterized in that, The downlink control signaling includes downlink control signaling for one or more uplink or downlink Hybrid Automatic Repeat reQuest (HARQ) processes.

15. The device according to claim 11, characterized in that, The third serving cell is configured as the first serving cell, and the third serving cell schedules the data communication of the second serving cell.

16. The device according to claim 11, characterized in that, The third serving cell is a designated available serving cell, wherein the second transmission unit is configured to transmit high layer signaling including a carrier index of the third serving cell via the first serving cell.

17. An apparatus for wireless communication, comprising: a determination unit configured to determine the availability of a second serving cell operating in an unlicensed band before data communication, wherein the second serving cell is scheduled by a first serving cell operating in a licensed band to perform the data communication; a first transmission unit configured to notify a user equipment (UE) of the determined availability of the second serving cell via channel availability signaling (CAS); and a data transceiver unit configured to perform the data communication on one of the second serving cell or a third serving cell based on the obtained availability of the second serving cell, wherein in response to the second serving cell being available, the data communication is performed on the second serving cell, and in response to the second serving cell being unavailable, the communication is performed on the third serving cell, wherein the third serving cell is a designated available serving cell, wherein the first transmission unit is configured to transmit downlink control signaling including an available carrier index via the first serving cell, and in the case where the second serving cell is unavailable, the available carrier index indicates a carrier index of the third serving cell.

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