阅读说明：本技术 用于在未授权频谱上的基于子带的信道接入的方法及设备 (Method and apparatus for sub-band based channel access on unlicensed spectrum ) 是由 雷海鹏 颜智 吴联海 刘兵朝 于 2018-09-28 设计创作，主要内容包括：本申请案涉及用于在未授权频谱上的基于子带的信道接入的方法及设备。本发明的一个实施例提供一种方法,其包括：接收用于调度在载波的一组带宽部分上的数据传输的下行链路控制信息DCI,其中所述载波包括多个带宽部分；对所述一组带宽部分执行先听后说LBT测试；及基于所述LBT测试的结果在所述一组带宽部分的一或多个带宽部分上发射所述数据。(The present application relates to methods and apparatus for subband-based channel access over unlicensed spectrum. One embodiment of the present invention provides a method, comprising: receiving downlink control information, DCI, for scheduling data transmission on a set of bandwidth parts of a carrier, wherein the carrier comprises a plurality of bandwidth parts; performing a listen before talk, LBT, test on the set of bandwidth parts; and transmitting the data on one or more bandwidth portions of the set of bandwidth portions based on results of the LBT test.)

1. A method, comprising:

receiving downlink control information, DCI, for scheduling data transmission on a set of bandwidth parts of a carrier, wherein the carrier comprises a plurality of bandwidth parts;

performing a listen before talk, LBT, test on the set of bandwidth parts; and

transmitting the data on one or more bandwidth portions of the set of bandwidth portions based on results of the LBT test.

2. The method of claim 1, wherein each bandwidth portion has the same bandwidth in frequency.

3. The method of claim 2, wherein each bandwidth portion has a 20MHz bandwidth in frequency.

4. The method of claim 1, wherein the DCI comprises a bitmap, wherein each bit of the bitmap indicates whether a corresponding bandwidth portion is assigned for the data transmission.

5. The method of claim 4, wherein a number of bits of the bitmap is equal to a number of bandwidth portions of the carrier.

6. The method of claim 1, wherein the DCI comprises a bit field indicating a starting bandwidth portion index and a number of contiguous bandwidth portions on the carrier.

7. The method of claim 1, wherein the data comprises a plurality of Transport Block (TB) s, and each of the plurality of TB s is to be transmitted on a corresponding bandwidth portion of the set of bandwidth portions.

8. The method of claim 1, wherein the DCI comprises a bitmap, wherein each bit of the bitmap indicates whether the data transmitted over a bandwidth portion of the set of bandwidth portions is to be retransmitted.

9. The method of claim 4, further comprising determining whether a bandwidth portion of the set of bandwidth portions is scheduled for transmission of a new Transport Block (TB) or a previous TB based on the bitmap and a New Data Indicator (NDI) included in the DCI.

10. The method of claim 1, wherein the data comprises a plurality of Code Block Groups (CBGs), and each bandwidth portion of the set of bandwidth portions includes an integer number of CBGs.

11. The method of claim 1, further comprising transmitting Uplink Control Information (UCI) with the data, wherein the UCI is carried on each of the set of bandwidth parts.

12. The method of claim 1, further comprising transmitting Uplink Control Information (UCI) with the data, wherein the UCI is carried on a particular bandwidth portion of the set of bandwidth portions having a lowest or minimum or highest or maximum bandwidth portion index; and wherein the LBT test includes a plurality of LBT operations corresponding to the set of bandwidth portions, and one of the plurality of LBT operations corresponding to the particular bandwidth portion is completed before the remaining operations of the plurality of LBT operations.

13. The method of claim 1, further comprising transmitting Uplink Control Information (UCI) on at least one bandwidth part of the set of bandwidth parts, and the UCI is mapped to at least one symbol at or near an end of the at least one bandwidth part.

14. The method of claim 1, further comprising performing a first LBT operation of the LBT test on one of the set of bandwidth parts and performing a second LBT of the LBT test on a remaining bandwidth part of the set of bandwidth parts, wherein the first LBT operation is different than the second LBT operation.

15. The method of claim 1, further comprising performing a first LBT operation of the LBT test on each of the set of bandwidth parts.

16. The method of claim 1, wherein the data transmission on each of the set of bandwidth parts begins with a demodulation reference signal (DMRS) symbol.

17. A method, comprising:

transmitting downlink control information, DCI, for scheduling data transmission on a set of bandwidth parts of a carrier, wherein the carrier comprises a plurality of bandwidth parts;

performing a listen before talk, LBT, test on the set of bandwidth parts; and

receiving the data on one or more bandwidth portions of the set of bandwidth portions based on results of the LBT test.

18. The method of claim 17, wherein each bandwidth portion has the same bandwidth in frequency.

19. The method of claim 18, wherein each bandwidth portion has a 20MHz bandwidth in frequency.

20. The method of claim 17, wherein the DCI comprises a bitmap, wherein each bit of the bitmap indicates whether a corresponding bandwidth portion is assigned for the data transmission.

21. The method of claim 20, wherein a number of bits of the bitmap is equal to a number of bandwidth portions of the carrier.

22. The method of claim 17, wherein the DCI comprises a bit field indicating a starting bandwidth portion index and a number of contiguous bandwidth portions on the carrier.

23. The method of claim 17, wherein the data comprises a plurality of Transport Block (TB) s, and each of the plurality of TB s is to be transmitted on a corresponding bandwidth portion of the set of bandwidth portions.

24. The method of claim 17, wherein the DCI comprises a bitmap, wherein each bit of the bitmap indicates that the data transmitted over a bandwidth portion of the set of bandwidth portions is to be retransmitted.

25. The method of claim 20, wherein the DCI further comprises a New Data Indicator (NDI).

26. The method of claim 17, wherein the data comprises a plurality of Code Block Groups (CBGs), and each bandwidth portion of the set of bandwidth portions includes an integer number of CBGs.

27. The method of claim 17, further comprising receiving Uplink Control Information (UCI) with the data, and the UCI is carried on each of the set of bandwidth parts.

28. The method of claim 17, further comprising receiving Uplink Control Information (UCI) on at least one bandwidth part of the set of bandwidth parts, wherein the UCI is mapped to at least one symbol at or near an end of the at least one bandwidth part.

29. The method of claim 17, wherein the data transmission on each of the set of bandwidth parts begins with a demodulation reference signal (DMRS) symbol.

30. An apparatus, comprising:

at least one non-transitory computer-readable medium having computer-executable instructions stored therein;

at least one receiver;

at least one transmitter; and

at least one processor coupled to the at least one non-transitory computer-readable medium, the at least one receiver, and the at least one transmitter;

wherein the computer-executable instructions are programmed to implement the method of any one of claims 1-16 with the at least one receiver, the at least one transmitter, and the at least one processor.

31. An apparatus, comprising:

at least one non-transitory computer-readable medium having computer-executable instructions stored therein;

at least one receiver;

at least one transmitter; and

at least one processor coupled to the at least one non-transitory computer-readable medium, the at least one receiver, and the at least one transmitter;

wherein the computer-executable instructions are programmed to implement the method of any one of claims 17-29 with the at least one receiver, the at least one transmitter, and the at least one processor.

Technical Field

The present disclosure relates generally to methods and apparatus for communication, and more particularly, to methods and apparatus for communication with a 3GPP 5G New Radio (NR) access over unlicensed spectrum (NR-U).

Background

Listen-before-talk, or sometimes referred to as listen-before-transmit (LBT), is a technique for transmitting on an unlicensed spectrum. To achieve fair coexistence with other wireless systems, LBT is required before a transmitter can start transmitting on the unlicensed spectrum. LBT is performed by performing energy detection on a specific channel. LBT succeeds if the detected power of the channel is below a predefined threshold, indicating that the channel is considered empty and available for transmission. Only when LBT is successful, the transmitter can start transmitting on the channel and occupy the channel up to a Maximum Channel Occupancy Time (MCOT); otherwise, the transmitter cannot start communication and will continue to perform LBT until a successful LBT is obtained.

In 5G NR, very wide bandwidths are supported, for example up to 100MHz bandwidth for frequency range 1(FR1, 450MHz to 6000MHz) and up to 400MHz bandwidth for frequency range 2(FR2, 24250MHz to 52600 MHz). Since the unlicensed spectrum at 5.7GHz has a wide bandwidth of up to several hundred MHz, NR-U also supports wide bandwidths.

To achieve fair coexistence with Wi-Fi, the agreed NR-U operating bandwidth is an integer multiple of 20MHz, and LBT is performed in each portion of the operating bandwidth having a 20MHz bandwidth.

When a Transport Block (TB) is scheduled for transmission on an unlicensed wide frequency, not all portions having a 20MHz bandwidth are available for the TB. Therefore, how to transmit data in case several parts of the operating bandwidth are not available is a problem to be solved by the present invention.

Disclosure of Invention

One embodiment of the present invention provides a method, comprising: receiving Downlink Control Information (DCI) for scheduling data transmission on a set of bandwidth parts of a carrier, wherein the carrier comprises a plurality of bandwidth parts; performing a Listen Before Talk (LBT) test on the set of bandwidth parts; and transmitting the data on one or more bandwidth portions of the set of bandwidth portions based on results of the LBT test.

Another embodiment of the invention provides a method comprising: transmitting Downlink Control Information (DCI) for scheduling data transmission on a set of bandwidth parts of a carrier, wherein the carrier comprises a plurality of bandwidth parts; performing a Listen Before Talk (LBT) test on the set of bandwidth parts; and receiving the data on one or more bandwidth portions of the set of bandwidth portions based on results of the LBT test.

Yet another embodiment of the present invention provides an apparatus, comprising: at least one non-transitory computer-readable medium having computer-executable instructions stored therein; at least one receiver; at least one transmitter; and at least one processor coupled to the at least one non-transitory computer-readable medium, the at least one receiver, and the at least one transmitter; wherein the computer-executable instructions are programmed to implement a method comprising: receiving Downlink Control Information (DCI) for scheduling data transmission over a set of bandwidth parts of a carrier, wherein the carrier comprises a plurality of bandwidth parts; performing a Listen Before Talk (LBT) test on the set of bandwidth parts; and transmitting the data on one or more bandwidth portions of the set of bandwidth portions based on results of the LBT test.

Yet another embodiment of the present invention provides an apparatus, comprising: at least one non-transitory computer-readable medium having computer-executable instructions stored therein; at least one receiver; at least one transmitter; and at least one processor coupled to the at least one non-transitory computer-readable medium, the at least one receiver, and the at least one transmitter; wherein the computer-executable instructions are programmed to implement a method: transmitting Downlink Control Information (DCI) for scheduling data transmission on a set of bandwidth parts of a carrier, wherein the carrier comprises a plurality of bandwidth parts; performing a Listen Before Talk (LBT) test on the set of bandwidth parts; and receiving the data on one or more bandwidth portions of the set of bandwidth portions based on results of the LBT test.

Drawings

Fig. 1 illustrates a wireless communication system 100 according to an embodiment of the present invention.

Fig. 2 illustrates a wideband carrier divided into four subbands.

Fig. 3(a) and 3(b) illustrate subband-based partitioning and bandwidth part (BWP) partitioning, respectively, on a wideband carrier.

Fig. 4 illustrates UCI multiplexing on each assigned subband.

Fig. 5 illustrates an exemplary block diagram of a User Equipment (UE) according to an embodiment of the present invention.

Fig. 6 illustrates an exemplary block diagram of a Base Station (BS) according to an embodiment of the present invention.

Detailed Description

The detailed description of the drawings is intended as a description of the presently preferred embodiments of the invention and is not intended to represent the only forms in which the present invention may be practiced. It is to be understood that the same or equivalent functions may be accomplished by different embodiments that are intended to be encompassed within the spirit and scope of the invention.

Embodiments provide methods and apparatus for subband-based channel access over an unlicensed spectrum. To facilitate understanding, embodiments are provided under specific network architectures and new service scenarios, such as 3GPP 5G, 3GPP Long Term Evolution (LTE) release 8, and so on. It is clear to those skilled in the art that the embodiments of the present invention can also be applied to similar technical problems as the network architecture and new service scenarios develop.

Fig. 1 depicts a wireless communication system 100 according to an embodiment of the present invention.

As shown in fig. 1, a wireless communication system 100 includes a UE 101 and a BS 102. In particular, for illustrative purposes, the wireless communication system 100 includes three UEs 101 and three BSs 102. Although a particular number of UEs 101 and BSs 102 are depicted in FIG. 1, one skilled in the art will recognize that any number of UEs 101 and BSs 102 may be included in the wireless communication system 100.

The UE 101 may include a computing device, such as a desktop computer, laptop computer, Personal Digital Assistant (PDA), tablet computer, smart television (e.g., a television connected to the Internet), set-top box, gaming console, security system (including security camera), on-board computer, network device (e.g., router, switch, and modem), or the like. According to embodiments of the invention, the UE 101 may comprise a portable wireless communication device, a smart phone, a cellular phone, a clamshell phone, a device with a user identity module, a personal computer, a selective call receiver, or any other device capable of sending and receiving communication signals over a wireless network. In some embodiments, the UE 101 includes a wearable device, such as a smart watch, a fitness bracelet, an optical head-mounted display, or the like. Moreover, the UE 101 may be referred to as a subscriber unit, a mobile phone, a mobile station, a user, a terminal, a mobile terminal, a wireless terminal, a fixed terminal, a subscriber station, a user terminal, or a device, or described using other terminology used in the art. UE 101 may communicate directly with BS 102 via an Uplink (UL) communication signal.

BSs 102 may be distributed throughout a geographic area. In certain embodiments, each of BSs 102 may also be referred to as an access point, an access terminal, a base station, a macro cell, a node-B, an enhanced node B (enb), a home node-B, a relay node, or a device, or described using other terminology used in the art. BS 102 is typically a component of a radio access network that may include one or more controllers communicatively coupled to one or more corresponding BSs 102.

The wireless communication system 100 is compatible with any type of network capable of sending and receiving wireless communication signals. For example, the wireless communication system 100 is compatible with wireless communication networks, cellular telephone networks, Time Division Multiple Access (TDMA) -based networks, Code Division Multiple Access (CDMA) -based networks, Orthogonal Frequency Division Multiple Access (OFDMA) -based networks, LTE networks, 3 rd generation partnership project (3GPP) -based networks, 3GPP 5G networks, satellite communication networks, high altitude platform networks, and/or other communication networks.

In one embodiment, the wireless communication system 100 is compatible with the 5G New Radio (NR) of the 3GPP protocol, where the BS 102 transmits data using an Orthogonal Frequency Division Multiplexing (OFDM) modulation scheme on the DL and the UE 101 transmits data using a single carrier frequency division multiple access (SC-FDMA) or OFDM scheme on the UL. More generally, however, the wireless communication system 100 may implement some other open or proprietary communication protocols, such as WiMAX, among others.

In other embodiments, BS 102 may communicate using other communication protocols, such as the IEEE 802.11 family of wireless communication protocols. Furthermore, in some embodiments, BS 102 may communicate via licensed spectrum, while in other embodiments BS 102 may communicate via unlicensed spectrum. The present invention is not intended to be limited to implementation by any particular wireless communication system architecture or protocol. In another embodiment, the BS 102 may communicate with the UE 101 using 3GPP 5G protocols.

Wireless communication transmissions over unlicensed spectrum should meet regulatory requirements subject to the management of the country or region in which they are located. Therefore, the uplink data design of NR-U, e.g., Physical Uplink Shared Channel (PUSCH) or Physical Uplink Control Channel (PUCCH), should meet regulatory requirements for unlicensed spectrum.

The requirements include:

occupied Channel Bandwidth (OCB): the bandwidth containing 99% of the power of the signal should be between 80% and 100% of the nominal channel bandwidth stated;

maximum Power Spectral Density (PSD) with a resolving bandwidth of 1MHz, e.g. 10 dBm/MHz.

These two requirements indicate that signals occupying a small portion of the channel bandwidth cannot be transmitted at the UE with the maximum available power due to PSD and OCB constraints.

In an embodiment of the invention, a wideband carrier is divided into a set of bandwidth parts. For example, for illustrative purposes only, fig. 2 illustrates a wideband carrier divided into four subbands, named subband 1, subband 2, subband 3, and subband 4, respectively. However, the present invention does not intend to limit the designation of a set of bandwidth parts to a subband or several bandwidth parts. For example, FIG. 3(a) depicts that a set of bandwidth portions may be named subbands and numbered from 0 to N-1, where N is an integer greater than 0. FIG. 3(b) depicts that a set of bandwidth parts may be named as Bandwidth parts (BWPs) and numbered from 0 to N-1. In the present invention, the bandwidth part is named a sub-band. In a preferred embodiment, each sub-band has the same bandwidth in frequency. In another preferred embodiment, each sub-band has a 20MHz bandwidth.

For a wideband carrier having an integer multiple of the same sub-band bandwidth (e.g., 20MHz), a channel access method comprises:

-Carrier Aggregation (CA); and

-subband manipulation.

In the CA method, similar to LTE's licensed-assisted access (LAA) or enhanced LAA (eLAA), a UE or BS performs LBT testing on each carrier based on multi-carrier LBT operations specified in LTE LAA or eLAA, and then transmits data on each available carrier.

Alternatively, in the subband operation method, the UE or the BS performs LBT test on each subband and aggregates available subbands of a single PUSCH or PDSCH. For example, when some results of the LBT test with respect to some subbands indicate success and some results of the LBT test with respect to other subbands indicate failure, then the UE may transmit data on the subbands with successful results of the LBT test and not transmit data on the subbands with failed results of the LBT test. As shown in fig. 2, when the results of the LBT test for subbands 1 and 4 are successful, simultaneous utilization of subbands 1 and 4 for data transmission is allowed.

For the CA approach (i.e., CA-based LBT), less standard impact is introduced when using LTE-based LAA as baseline and it also requires less stringent processing requirements since each TB is processed independently of each Component Carrier (CC). However, an additional guard band is required between consecutive carriers for the CA method.

On the other hand, the subband manipulation method (i.e., subband-based LBT) has two features: (1) no guard bands need to be placed between consecutive sub-bands, so the spectral efficiency is improved over the CA-based LBT approach; and (2) dynamic spectrum usage is achieved at a finer granularity of LBT bandwidth.

Nevertheless, during data communication, scheduling decisions are made before performing LBT tests. When it is determined that the TB is to be transmitted over a wide frequency band (e.g., the wideband carrier of fig. 2), not all of the sub-bands may be simultaneously used for TB transmission, subject to LBT test results. The method for overcoming the situation may include: (1) performing rate matching on the available subbands; or (2) puncturing data to be transmitted on the unavailable subbands.

In the case of using a rate matching method, a high coding rate may be incurred so that scheduled TBs are transmitted only in the available subbands and the coding rate may vary depending on the number of available subbands. Furthermore, the UE may not have enough processing time to perform rate matching because there is little extra time from the moment the LBT result is considered successful to the moment the UE starts UL transmission.

In case of using the puncturing method, a portion of the TB mapped to a subband corresponding to a failed LBT result is punctured. Although it is simpler than the rate matching method, it may cause TB decoding failure at the gbb side when too many parts of the TB are punctured.

Some embodiments of the present invention provide a method that solves the aforementioned problems of the subband operating method and thus improves the channel utilization efficiency.

During data communication, the UE receives Downlink Control Information (DCI) from the BS, which allocates frequency domain resources to the UE. In one embodiment, the DCI schedules data transmission on a set of subbands of a wideband carrier. The subband carrier includes a plurality of subbands, and a set of subbands may be a portion or all of the plurality of subbands. Then, the UE performs LBT testing on a set of subbands for uplink transmission or the BS performs LBT testing on a set of subbands for downlink transmission. According to the results of the LBT test, some subbands may be used for transmission, which means that the results of the LBT test for the available subbands are successful and the UE or BS may transmit data on these subbands. Correspondingly, the BS or UE will receive data transmitted on the corresponding subband from the UE or BS.

In a preferred embodiment, the sub-bands have the same bandwidth in frequency. In another preferred embodiment, the frequencies of the bandwidths of the sub-bands are all 20 MHz. In some embodiments, the partitioning is based on an interleaved structure every 20MHz sub-band. In detail, the carrier bandwidth is divided into a plurality of interlaces, and each interlace includes a set of PRBs that are evenly spaced in the frequency domain. In this way, each interlace may span more than 80% of the carrier bandwidth in order to meet the requirements for occupied bandwidth. Meanwhile, the minimum distance between two adjacent PRBs within each interlace is greater than 1 MHz. Each PRB within one interlace may be transmitted at 10dBm power. For example, for a 15kHz subcarrier spacing, the total number of Physical Resource Blocks (PRBs) of the NR 20MHz bandwidth is 106, then ten interlaces are formed, where one interlace includes 16 PRBs and each of the other nine interlaces includes 10 PRBs or each of the ten interlaces includes 10 PRBs and the remaining 6 PRBs are unused; or 11 interlaces are formed, where one interlace includes 6 PRBs and each of the other ten interlaces includes 10 PRBs.

There are two levels of frequency domain resource allocation: the first level is a subband-based indication and the second level is a PRB-based indication within the assigned subband.

For subband-based indication, in a preferred embodiment, the DCI includes a bitmap indicating the subbands allocated for data transmission. Each bit of the bitmap indicates whether a corresponding subband is assigned for data transmission. The assigned subbands may be distributed across the subband carriers. For example, with respect to a wideband having a bandwidth of 80MHz, it is divided into 4 sub-bands, each having a bandwidth of 20 MHz. Then, a 4-bit bitmap is sufficient to indicate whether any of the four subbands has been allocated. For another example, subband 0, subband 2, and subband N-1 in FIG. 3(a) may be allocated for data transmission. In this way, the frequency diversity gain can be further improved.

According to DCI, there are two types of subbands in a wideband: a subband in the wideband allocated for data transmission, and a subband not allocated for data transmission. In one embodiment, the size of the bitmap is equal to the bandwidth of the wideband divided by the bandwidth of the sub-bands.

In another embodiment, the size of the bitmap is equal to the effective bandwidth portion in the wideband divided by the bandwidth of the sub-band.

In some embodiments, the DCI may further include bit fields indicating a starting bandwidth portion index and a number of contiguous bandwidth portions on a wideband carrier. Using FIG. 2 as an example, the bit field may specify that the allocated sub-band starts from sub-band 2 and that the number of consecutive sub-bands is 3. The UE will then know that the allocated subbands are subband 2, subband 3, and subband 4. In this embodiment, continuous transmission in the frequency domain is achieved in order to reduce channel blockage due to power leakage on adjacent sub-bands.

With respect to the PRB based indication within the assigned subbands, the current frequency domain resource assignment field is reused as an interlace based assignment within each subband. To reduce overhead, the same frequency domain resources are applied for each of the assigned subbands.

As described above, if the results of LBT testing for a particular sub-band are unsuccessful, then data transmitted on the particular sub-band is punctured. With respect to punctured data, subband-based retransmission in accordance with embodiments of the present invention is presented in order to recover the punctured data.

In one embodiment, one TB is carried on one of the assigned subbands. When the results of the LBT test indicate success on the associated sub-band, the TB is transmitted from the BS to the UE. When the results of the LBT test indicate a failure on the associated sub-band, the TB is not transmitted from the BS to the UE on the associated sub-band. In some embodiments, the TBs are scheduled for retransmission on the same subband or on a different subband in the next transmission opportunity. To achieve the above result, the DCI may further include a subband-based transmission indication (STI) for scheduling retransmission of data. In a preferred embodiment, the DCI contains a bitmap, where each bit of the bitmap indicates whether data transmitted on a subband is to be retransmitted.

In some embodiments, the DCI further includes a New Data Indicator (NDI) having a size of one bit. Based on the NDI in the DCI and the subband-based bitmap, the UE may determine which subband to use to transmit the new TB and which subband to use to transmit the previous TB.

In some embodiments, with respect to the acknowledgement (HARQ-ACK) feedback mechanism in hybrid automatic repeat request-new NR, Code Block Group (CBG) based retransmissions are supported in addition to TB based retransmissions. One HARQ-ACK feedback bit corresponds to one TB for TB-based retransmission. As long as one Code Block (CB) of a given TB is not decoded correctly on the receiver side, the entire TB is reported to "not acknowledged" (NACK). The transmitter must retransmit all CBs of the TB. In the case where one HARQ-ACK feedback bit corresponds to one CB, the transmitter knows the decoding status of each transmitted CB and transmits only the failed CBs. In this way, retransmission efficiency is high. However, the HARQ-ACK feedback overhead can be significant.

To balance the number of required HARQ-ACK feedback bits and retransmission efficiency, CBG is introduced into the radio access network (RAN 1). Fundamentally, a CBG wants to group several code blocks into one code block group and generate the resulting HARQ-ACK feedback per CBG. Setting the HARQ-ACK of a CBG to "ACK" only if all code blocks within one CBG are decoded correctly; otherwise, it is set to "NACK". Upon receiving the HARQ-ACK feedback, the CBG with only "NACK" is retransmitted by the transmitter.

For CBG-based retransmissions, Radio Resource Control (RRC) signaling is used to configure the maximum number of CBGs per TB. The maximum number of CBGs per TB may be 2, 4, 6 and 8. The number of HARQ-ACK bits for one TB is equal to the maximum number of CBGs configured per TB, regardless of the variable TBs for a given TB, for both the semi-static HARQ-ACK codebook and the dynamic HARQ-ACK codebook.

CBG-based retransmissions are also suitable for unlicensed spectrum. Especially when an incomplete PDSCH or PUSCH is transmitted in the initial partial time slot after LBT success, CBG-based retransmissions may be used to retransmit those CBGs punctured by the transmitter.

In a preferred embodiment, the TB is divided into a plurality of CBGs, and each sub-band carries an integer number of CBGs. Preferably, the number of CBGs carried on each sub-band is the same. Rate matching is employed to align the CBG mapping in each subband. In this way, CBG transmission information (CBGTI) in the DCI is used to retransmit those CBGs that are carried on the associated subbands and punctured due to unsuccessful results of the LBT test.

Upon receiving the DCI, the UE prepares data, which may be the PUSCH, according to the assigned subbands in the scheduled slot. The corresponding TB indicated by the DCI is divided into a plurality of CBGs, and the maximum number of CBGs per TB is configured by RRC signaling.

The UE will calculate the number of CBGs within each sub-band and each sub-band carries the same number of CBGs.

In another preferred embodiment, Uplink Control Information (UCI), such as ACK/NACK for DL TBs, Channel State Information (CSI), etc., is transmitted with the data in each subband. Due to the unpredictability of the results of the LBT test, the UE and BS cannot know which sub-band is available before the LBT test, and therefore, transmitting UCI in each sub-band will simplify the implementation complexity of the UE and BS. Preferably, the UCI is mapped as close to the end of the transmission as possible. For example, fig. 4 illustrates UCI mapped to each subband.

In one embodiment, the last few symbols carried on each subband are used for PUCCH transmission. More specifically, the number of PUCCH symbols is determined by the corresponding PUCCH format and resource.

Alternatively, UCI may be transmitted on only one subband. For example, the index for a subband may be lowest or minimum, or the index may be highest or maximum, and the LBT test for the lowest or minimum subband, or for the highest or maximum index, is the first completed LBT test. However, the BS needs to blindly detect potential opportunities for UCI transmission.

In a preferred embodiment, the LBT test on the sub-bands involves different types of operations. For example, one type of operation is a full LBT cat.4 operation (also referred to as a type 1UL channel access procedure in TS 36.213) with a random backoff counter selected from a variable contention window, and another type of operation is a single step LBT operation (also referred to as a type 2UL channel access procedure in TS 36.213) over at least a 25us sensing interval. In one embodiment, the UE selects a random subband from the allocated subbands and performs a full LBT cat.4 operation for this subband. Before the LBT cat.4 operation is completed, the UE performs a single step LBT operation on every other subband of the allocated subbands.

In another embodiment, the BS dynamically indicates one sub-band in the DCI to direct the UE to perform LBT cat.4 operations on the sub-band and perform single-step LBT operations on the other assigned sub-bands before LBT cat.4 on the indicated sub-band is completed.

In another embodiment, if the UE determines that the subbands assigned for data transmission (e.g., PUSCH transmission) are interleaved and discontinuous, the UE will perform independent LBT cat.4 operations on each assigned subband. In this way, the UE may transmit data in a subband without deferral periods for other subbands as soon as the LBT operation for the subband is complete.

If the UE determines that consecutive subbands are assigned for PUSCH transmission, the UE should perform LBT cat.4 operation on one subband and single step LBT operation on the other assigned subband. In this case, a deferral period is required.

In another preferred embodiment, the data transmission on each of the set of bandwidth parts starts with a demodulation reference signal (DMRS) symbol.

Over the unlicensed spectrum, for a wideband carrier having an integer multiple of 20MHz bandwidth, the wideband carrier is divided into a plurality of BWPs, where each BWP occupies the 20MHz bandwidth. The partitioning is based on an interleaved structure per BWP. Since multiple BWPs may be used for data transmission as long as they have successful LBTs, the specification should grant entry into one slot when more than one BWP is activated. A BWP-based bitmap is included in the UL grant to indicate BWP assigned for PUSCH transmissions.

According to the above disclosure, the spectrum utilization efficiency can be further improved.

Fig. 5 depicts a block diagram of a UE according to an embodiment of the invention. The UE 101 may include a receiver, a processor, and a transmitter. In a particular embodiment, the UE 101 may further include an input device, a display, a memory, and/or other elements. In one embodiment, the UE may include: at least one non-transitory computer-readable medium having computer-executable instructions stored therein; at least one receiver; at least one transmitter; and at least one processor coupled to the at least one non-transitory computer-readable medium, the at least one receiver, and the at least one transmitter. The computer-executable instructions may be programmed to implement a method with the at least one receiver, the at least one transmitter, and the at least one processor. A method according to an embodiment of the invention is for example the method shown in fig. 4.

Fig. 6 depicts a block diagram of a BS according to an embodiment of the present invention. BS 102 may include a receiver, a processor, and a transmitter. In one embodiment, the BS may comprise: at least one non-transitory computer-readable medium having computer-executable instructions stored therein; at least one receiver; at least one transmitter; and at least one processor coupled to the at least one non-transitory computer-readable medium, the at least one receiver, and the at least one transmitter. The computer-executable instructions may be programmed to implement a method with the at least one receiver, the at least one transmitter, and the at least one processor. A method according to an embodiment of the invention is for example the method shown in fig. 4.

The method of the present invention may be implemented on a programmed processor. However, the controllers, flow charts and modules may also be implemented on a general purpose or special purpose computer, a programmed microprocessor or microcontroller and peripheral integrated circuit elements, integrated circuits, hardware electronic or logic circuits (e.g., discrete element circuits), programmable logic devices or the like. In general, any device having a finite state machine capable of implementing the flowcharts shown in the figures may be used to implement the processing functions of this disclosure.

While the present invention has been described with reference to specific embodiments thereof, it is evident that many alternatives, modifications, and variations will be apparent to those skilled in the art. For example, various components of the embodiments may be interchanged, added, or substituted in the other embodiments. Also, not all of the elements shown in each figure are necessary for operation of the disclosed embodiments. For example, those skilled in the art of the disclosed embodiments will be able to make and use the teachings of the present disclosure by simply employing the elements of the independent claims. Accordingly, the embodiments of the invention set forth herein are intended to be illustrative, not limiting. Various changes may be made without departing from the spirit and scope of the invention.

In this document, relational terms such as "first," "second," and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. The terms "comprises/comprising" or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. An element(s) that begins with an "a/an" or the like, without further constraint, does not exclude the presence of additional identical elements from the process, method, article, or apparatus that comprises the element. Also, the term "another" is defined as at least a second or more. The terms "comprising," "having," and the like, as used herein, are defined as comprising.