WO2023065332A1

WO2023065332A1 - Methods, devices, and medium for communication

Info

Publication number: WO2023065332A1
Application number: PCT/CN2021/125829
Authority: WO
Inventors: Gang Wang
Original assignee: Nec Corporation
Priority date: 2021-10-22
Filing date: 2021-10-22
Publication date: 2023-04-27

Abstract

Example embodiments of the present disclosure relate to methods, devices, and medium for communication. The method comprises determining a gap between an ending point of a first channel access procedure and a starting point of a symbol after the first channel access procedure, the first channel access procedure being associated with a channel occupancy initiated by the first device for a channel between the first device and at least one second device; performing a second channel access procedure within the gap, the second channel access procedure having a first pre-determined duration; and in accordance with a determination that the second channel access procedure is successful, performing communication with the at least one second device on the channel at the starting point of the symbol. In this way, the alignment between the transmission and symbol boundary can be guaranteed for operation on shared spectrum in mmWave band.

Description

METHODS, DEVICES, AND MEDIUM FOR COMMUNICATION

FIELD

Example embodiments of the present disclosure generally relate to the field of communication techniques and in particular, to methods, devices, and medium for channel access in millimeter wave bands.

BACKGROUND

Mobile communication involves the transmissions between a terminal device and a network device. Before performing transmission (s) , the terminal device or the network device may evaluate the availability of a channel for performing transmissions with channel access procedures, such as a Listen-before-Talk (LBT) mechanism or a clear channel assessment (CCA) , to improve the transmission performance. Work is ongoing to introduce enhancements to achieve more effective channel access procedures.

SUMMARY

In general, example embodiments of the present disclosure provide methods, devices and computer storage medium for channel access in millimeter wave bands. Embodiments that do not fall under the scope of the claims, if any, are to be interpreted as examples useful for understanding various embodiments of the disclosure.

In a first aspect, there is provided a method implemented at a first device. The method comprises: determining a gap between an ending point of a first channel access procedure and a starting point of a symbol after the first channel access procedure, the first channel access procedure being associated with a channel occupancy initiated by the first device for a channel between the first device and at least one second device; performing a second channel access procedure within the gap, the second channel access procedure having a first pre-determined duration; and in accordance with a determination that the second channel access procedure is successful, performing communication with the at least one second device on the channel at the starting point of the symbol.

In a second aspect, there is provided a method implemented at a first device. The method comprises: transmitting, to at least one second device, information comprising a cyclic prefix extension signal or a short control signalling at an ending point of a first channel access procedure, the first channel access procedure being associated with a channel occupancy initiated by the first device for a channel between the first device and the at least one second device; and performing communication with the at least one second device on the channel at a starting point of a symbol after the first channel access procedure.

In a third aspect, there is provided a first device. The communication device comprises a processor and a memory. The memory is coupled to the processor and stores instructions thereon. The instructions, when executed by the processor, cause the first device to perform the method according to the first aspect or the second aspect above.

In a fifth aspect, there is provided a computer readable medium having instructions stored thereon, the instructions, when executed on at least one processor, causing the at least one processor to carry out the method according to the first aspect or the second aspect above.

It is to be understood that the summary section is not intended to identify key or essential features of embodiments of the present disclosure, nor is it intended to be used to limit the scope of the present disclosure. Other features of the present disclosure will become easily comprehensible through the following description.

BRIEF DESCRIPTION OF THE DRAWINGS

Through the more detailed description of some example embodiments of the present disclosure in the accompanying drawings, the above and other objects, features and advantages of the present disclosure will become more apparent, wherein:

Fig. 1 illustrates an example communication network in which embodiments of the present disclosure can be implemented;

FIGs. 2A-2C illustrate time diagrams for the channel access according to some example embodiments of the present disclosure;

FIGs. 3A-3D illustrate time diagrams for the channel access according to some example embodiments of the present disclosure;

FIG. 4 illustrates a time diagram for the channel access according to some example embodiments of the present disclosure;

FIGs. 5A-5C illustrate time diagrams for the channel access according to some example embodiments of the present disclosure;

FIG. 6 illustrates a flowchart of an example method in accordance with some embodiments of the present disclosure;

FIG. 7 illustrates a flowchart of an example method in accordance with some embodiments of the present disclosure;

FIG. 8 illustrates a simplified block diagram of a device that is suitable for implementing embodiments of the present disclosure.

Throughout the drawings, the same or similar reference numerals represent the same or similar element.

DETAILED DESCRIPTION

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

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

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

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

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

In some examples, values, procedures, or apparatus are referred to as “best, ” “lowest, ” “highest, ” “minimum, ” “maximum, ” or the like. It will be appreciated that such descriptions are intended to indicate that a selection among many used functional alternatives can be made, and such selections need not be better, smaller, higher, or otherwise preferable to other selections.

As used herein, the term “communication network” refers to a network following any suitable communication standards, such as New Radio (NR) , Long Term Evolution (LTE) , LTE-Advanced (LTE-A) , Wideband Code Division Multiple Access (WCDMA) , High-Speed Packet Access (HSPA) , Narrow Band Internet of Things (NB-IoT) and so on. Furthermore, the communications between a terminal device and a network device in the communication network may be performed according to any suitable generation communication protocols, including, but not limited to, the first generation (1G) , the second generation (2G) , 2.5G, 2.75G, the third generation (3G) , the fourth generation (4G) , 4.5G, the fifth generation (5G) , 5.5G, 5G-Advanced networks, or the sixth generation (6G) communication protocols, and/or any other protocols either currently known or to be developed in the future. Embodiments of the present disclosure may be applied in various communication systems. Given the rapid development in communications, there will of course also be future type communication technologies and systems with which the present disclosure may be embodied. It should not be seen as limiting the scope of the present disclosure to only the aforementioned system.

As used herein, the term “terminal device” refers to any device having wireless or wired communication capabilities. Examples of the terminal device include, but not limited to, user equipment (UE) , personal computers, desktops, mobile phones, cellular phones, smart phones, personal digital assistants (PDAs) , portable computers, tablets, wearable devices, internet of things (IoT) devices, Ultra-reliable and Low Latency Communications (URLLC) devices, Internet of Everything (IoE) devices, machine type communication (MTC) devices, device on vehicle for V2X communication where X means pedestrian, vehicle, or infrastructure/network, devices for Integrated Access and Backhaul (IAB) , Space borne vehicles or Air borne vehicles in Non-terrestrial networks (NTN) including Satellites and High Altitude Platforms (HAPs) encompassing Unmanned Aircraft Systems (UAS) , eXtended Reality (XR) devices including different types of realities such as Augmented Reality (AR) , Mixed Reality (MR) and Virtual Reality (VR) , the unmanned aerial vehicle (UAV) commonly known as a drone which is an aircraft without any human pilot, devices on high speed train (HST) , or image capture devices such as digital cameras, sensors, gaming devices, music storage and playback appliances, or Internet appliances enabling wireless or wired Internet access and browsing and the like. The ‘terminal device’ can further has ‘multicast/broadcast’ feature, to support public safety and mission critical, V2X applications, transparent IPv4/IPv6 multicast delivery, IPTV, smart TV, radio services, software delivery over wireless, group communications and IoT applications. It may also be incorporated one or multiple Subscriber Identity Module (SIM) as known as Multi-SIM. The term “terminal device” can be used interchangeably with a UE, a mobile station, a subscriber station, a mobile terminal, a user terminal or a wireless device.

As used herein, the term “network device” refers to a device which is capable of providing or hosting a cell or coverage where terminal devices can communicate. Examples of a network device include, but not limited to, a satellite, a unmanned aerial systems (UAS) platform, a Node B (NodeB or NB) , an evolved NodeB (eNodeB or eNB) , a next generation NodeB (gNB) , a transmission reception point (TRP) , a remote radio unit (RRU) , a radio head (RH) , a remote radio head (RRH) , an IAB node, a low power node such as a femto node, a pico node, a reconfigurable intelligent surface (RIS) , and the like.

The terminal device or the network device may have Artificial intelligence (AI) or machine learning capability. It generally includes a model which has been trained from numerous collected data for a specific function, and can be used to predict some information.

The terminal device or the network device may work on several frequency ranges, e.g. FR1 (410 MHz –7125 MHz) , FR2 (24.25GHz to 71GHz) , millimeter waveform (mmWave) frequency band (24GHz to 300GHz) , frequency band larger than 100GHz as well as Tera Hertz (THz) . It can further work on licensed/unlicensed/shared spectrum. The terminal device may have more than one connection with the network device under Multi-Radio Dual Connectivity (MR-DC) application scenario. The terminal device or the network device can work on full duplex, flexible duplex and cross division duplex modes.

The embodiments of the present disclosure may be performed in test equipment, e.g., signal generator, signal analyzer, spectrum analyzer, network analyzer, test terminal device, test network device, or channel emulator.

The embodiments of the present disclosure may be performed according to any generation communication protocols either currently known or to be developed in the future. Examples of the communication protocols include, but not limited to, the first generation (1G) , the second generation (2G) , 2.5G, 2.75G, the third generation (3G) , the fourth generation (4G) , 4.5G, the fifth generation (5G) communication protocols, 5.5G, 5G-Advanced networks, or the sixth generation (6G) networks.

The term “circuitry” used herein may refer to hardware circuits and/or combinations of hardware circuits and software. For example, the circuitry may be a combination of analog and/or digital hardware circuits with software/firmware. As a further example, the circuitry may be any portions of hardware processors with software including digital signal processor (s) , software, and memory (ies) that work together to cause an apparatus, such as a terminal device or a network device, to perform various functions. In a still further example, the circuitry may be hardware circuits and or processors, such as a microprocessor or a portion of a microprocessor, that requires software/firmware for operation, but the software may not be present when it is not needed for operation. As used herein, the term circuitry also covers an implementation of merely a hardware circuit or processor (s) or a portion of a hardware circuit or processor (s) and its (or their) accompanying software and/or firmware.

FIG. 1 shows an example communication network 100 in which embodiments of the present disclosure can be implemented. The network 100 includes a network device 120 and terminal devices 110-1, 110-2…, 110-N served by the network device 120. The serving area of the network device 120 is called as a cell 102. The terminal devices 110-1, 110-2…, 110-N may be collectively referred to as “terminal device 110” .

In the communication network 100, the network device 120 can communicate/transmit data and control information to the terminal device 110 and the terminal device 110 can also communicate/transmit data and control information to the network device 120. A link from the network device 120 to the terminal device 110 is referred to as a downlink (DL) , while a link from the terminal device 110 to the network device 120 is referred to as an uplink (UL) . DL may comprise one or more logical channels, including but not limited to a Physical Downlink Control Channel (PDCCH) and a Physical Downlink Shared Channel (PDSCH) . UL may comprise one or more logical channels, including but not limited to a Physical Uplink Control Channel (PUCCH) and a Physical Uplink Shared Channel (PUSCH) .

Depending on the communication technologies, the network 100 may be a Code Division Multiple Access (CDMA) network, a Time Division Multiple Address (TDMA) network, a Frequency Division Multiple Access (FDMA) network, an Orthogonal Frequency-Division Multiple Access (OFDMA) network, a Single Carrier-Frequency Division Multiple Access (SC-FDMA) network or any others. Communications discussed in the network 100 may use conform to any suitable standards including, but not limited to, NR, Long Term Evolution (LTE) , LTE-Evolution, LTE-Advanced (LTE-A) , Wideband Code Division Multiple Access (WCDMA) , Code Division Multiple Access (CDMA) , CDMA2000, and Global System for Mobile Communications (GSM) and the like. Furthermore, the communications may be performed according to any generation communication protocols either currently known or to be developed in the future. Examples of the communication protocols include, but not limited to, the first generation (1G) , the second generation (2G) , 2.5G, 2.75G, the third generation (3G) , the fourth generation (4G) , 4.5G, the fifth generation (5G) , 5.5G, 5G-Advanced networks, or the sixth generation (6G) communication protocols. The techniques described herein may be used for the wireless networks and radio technologies mentioned above as well as other wireless networks and radio technologies. For clarity, certain aspects of the techniques are described below for LTE, and LTE terminology is used in much of the description below.

It is to be understood that the numbers of devices (i.e., the terminal devices 110 and the network device 120) and their connection relationships and types shown in Fig. 1 are only for the purpose of illustration without suggesting any limitation. The communication network 100 may include any suitable numbers of devices adapted for implementing embodiments of the present disclosure.

As used herein, the term “channel” may refer to a carrier or a part of a carrier consisting of a contiguous set of resource blocks (RBs) on which a channel access procedure is performed in shared spectrum.

As used herein, the term “channel access procedure” may refer to a procedure based on sensing that evaluates the availability of a channel for performing transmissions. The basic unit for sensing may be a sensing slot with a sensing slot duration T _sl. For example, the sensing slot duration T _sl may be considered to be idle if an eNB/gNB or a UE senses the channel during the sensing slot duration, and determines that the detected power for at least certain duration within the sensing slot duration (such as 4μs or 5μs) is less than energy detection threshold X _thresh. Otherwise, the sensing slot duration T _sl may be considered to be busy.

As used herein, the term “LBT” , “Category 4 (Cat4) LBT” , “Category 2 (Cat2) LBT” , “clear channel assessment (CCA) ” or “enhanced clear channel assessment (eCCA) ” may refer to the channel access procedure described above. For example, the Cat 4 LBT procedure may be similar to the Type 1 UL/DL channel access procedure or clear channel access. As a further example, the Cat 2 LBT procedure may be similar to the Type 2/2A/2B/2C UL/DL channel access procedures.

As used herein, the term “channel occupancy” may refer to transmission (s) on channel (s) by eNB/gNB/UE (s) after performing the corresponding channel access procedures.

As used herein, the term “Channel Occupancy Time (COT) ” may refer to the total time for which eNB/gNB/UE and any eNB/gNB/UE (s) sharing the channel occupancy perform transmission (s) on a channel after an eNB/gNB/UE performs the corresponding channel access procedures described above. For example, for determining a Channel Occupancy Time, if a transmission gap is less than or equal to certain duration (such as 25μs) , the gap duration is counted in the channel occupancy time. A channel occupancy time may be shared for transmission between an eNB/gNB and the corresponding UE (s) . In some cases, the Channel Occupancy Time shall be less than 5ms. A consecutive sequence of transmissions by the device, without a new CCA Check, shall not exceed the 5 ms Channel Occupancy Time, i.e., the Maximum Channel Occupancy Time (MCOT) is 5 ms.

The equipment (eNB/gNB/UE) that initiates transmission shall perform the CCA check using “energy detect” . The Operating Channel shall be considered occupied for a slot time of 5 μs if the energy level in the channel exceeds the threshold corresponding to the given power level. It shall observe the Operating Channel (s) for the duration of the CCA observation time measured by multiple slot times.

A CCA check is initiated at the end of an operating channel occupied slot time. Upon observing that Operating Channel was not occupied for a minimum of 8 μs, transmission deferring shall occur. The transmission deferring shall last for a minimum of random (0 to Max number) number of empty slots periods; where Max number shall not be lower than 3. The expected/ideal total sensing duration is calculated based on:

Ideal total sensing duration = 8+5*rand [0, Max number] μs.

Since the channel sensing result (the channel is occupied or not) for the minimum of 8 μs before transmission deferring occurrence is uncertain, and the channel sensing result for each slot within transmission deferring is also uncertain, therefore the actual total sensing duration for a CCA check is uncertain due to the channel characteristics on shared spectrum.

For the operation in regions where LBT is mandated on mmWave band shared spectrum, considering maximum re-use of the existing channel access mechanism and design principle in NR-Unlicensed spectrum (NR-U) to simplify the gNB/UE’s transmission alignment with symbol boundary for initiating the channel occupancy, discusses the impact on specification and proposes corresponding methods to resolve the misalignment issue due to uncertain sensing duration in LBT procedure.

In the solution of the present disclosure, if the gNB/UE has not performed a transmission after a channel access procedure, the gNB/UE may perform an additional channel access procedure immediately before the intended transmission, or the gNB/UE may transmit occupancy information before the intended transmission.

In this way, considering maximum re-use of the channel access mechanism in NR-U, a channel occupancy mechanism is proposed to resolve misalignment between starting point of UL/DL initial transmission and symbol boundary due to uncertain sensing duration in LBT procedure. In this regard, the UL/DL transmission can be aligned with the symbol boundary in a slot for NR supporting high frequency as a synchronous system.

Principle and implementations of the present disclosure will be described in detail below with reference to FIG. 2A to FIG. 5C, which show time diagrams for the channel access in different scenarios according to the embodiments of the present disclosure. Hereinafter the process of the channel access may involve the terminal device 110 and the network device 120 as shown in FIG. 1. As an example embodiment, a UE 110 will be the terminal device 100 and a gNB 120 will be the network device 120 in the following embodiments, for simplifying the description.

Due to uncertain actual sensing duration in LBT procedure, an ending point of a channel access procedure may locate within a symbol and does not align with symbol boundary. Thus, there may be a gap between the ending point of the channel access procedure and a starting point of a symbol after the channel access procedure.

In some embodiments of the present disclosure, a cyclic prefix extension signal may be considered for operation in mmWave band and the cyclic prefix extension signal may be designed to adapt to the sensing duration for related channel access procedure.

Specifically, a time length of the cyclic prefix extension signal is equal to the time length of the gap, so that the channel may be occupied before the intended transmission. And the actual transmission can be started at the starting point of the symbol after the channel access procedure.

Taking the uplink transmission for example, the time-continuous signal

for the interval

preceding the first OFDM symbol l for PUSCH, SRS, or PUCCH is given by

where t=0 at the start of the sub-frame and t<0 refers to the previous sub-frame, T _ext refers to the time length of the cyclic prefix extension signal, p refers to antenna port, and μ refers to subcarrier spacing configuration. And the time length of the cyclic prefix extension signal of the first OFDM symbol l allocated for PUSCH, SRS or PUCCH transmission can be represented as:

where “mod” refers to a modulus operator, Δ _i is given by Table 1 with an index i, and the index i may be indicated or configured by the gNB 120. “floor (x) ” in Table 1 refers to a function to obtain the largest integer not exceeding x. In some examples, the index i can be one integer value within a range of 0 to 4.

It should be noted that, the first PUSCH/SRS transmission performed by the UE 110 may be scheduled or configured by the gNB 120, the first PUCCH transmission performed by the UE 110 may be scheduled or configured by the gNB 120, or the first transmission performed by the UE 110 may be related to a random access procedure.

The UE 110 may initiate the first transmission related to a random access procedure by itself, or the UE 110 may initiate the first PUSCH/SRS/PUCCH transmission using configured grant scheduled by the gNB 120.

Table 1: The variable Δ _i for cyclic prefix extension signal

Taking the downlink transmission for example, the time-continuous signal

for the interval

preceding the first OFDM symbol l for PDSCH, or PDCCH is given by

where t=0 at the start of the sub-frame and t<0 refers to the previous sub-frame, T _ext refers to the time length of the cyclic prefix extension signal, p refers to antenna port, and μ refers to subcarrier spacing configuration. And the time length of the cyclic prefix extension signal of the first OFDM symbol l allocated for PDSCH or PDCCH transmission can be represented as:

where “mod” refers to a modulus operator, Δ _i is given by Table 1 with an index i, and the index i may be determined by the gNB 120. In some examples, the index i can be one integer value within a range of 0 to 4.

It should be noted that, the first transmission performed by the gNB 120 may include PDSCH/PDCCH, or the first transmission performed by the gNB 120 may be with only discovery burst or with discovery burst multiplexed with non-unicast information.

In other words, the gNB 120 may initiate the first transmission on PDSCH/PDCCH, or the gNB 120 may initiate the first transmission with discovery burst.

Now the reference is made to FIGs. 2A-2C, which show time diagrams for the channel access. In some embodiments, the UE 110 may initiate the first transmission related to a random access procedure by itself, or the UE 110 may initiate the first PUSCH/SRS/PUCCH transmission using configured grant scheduled by the gNB 120. In some embodiments, the gNB 120 may initiate the first PDSCH/PDCCH transmission, or the gNB 120 may initiate the first transmission with discovery burst. The UE 110 or the gNB 120 may perform a channel access procedure for initiating a channel occupancy for transmission between the UE 110 and the gNB 120.

As shown in FIGs. 2A-2C, an ideal channel access procedure should be ended at a boundary of a symbol (for example, a time point 210) , however, the actual channel access procedure may be ended within a symbol, that is, the ending point of the channel access procedure is not aligned with symbol boundary. For example, the channel access procedure ends at

time point

222, 224, 226 with an extended LBT after the starting point of symbol n, as shown in FIGs. 2A-2C respectively.

In this regard, a cyclic prefix extension signal may be transmitted before the intended transmission. In other words, the cyclic prefix extension signal may be transmitted within a gap between the ending point of the channel access procedure and the starting point of the symbol (for example, symbol n+1 in FIG. 2A, symbol n+1 in FIG. 2B, and symbol n+2 in FIG. 2C) after the channel access procedure.

In some embodiments, as shown in FIG. 2A, the channel access procedure 212 is performed and the time duration of the extended LBT 232 is Td, which represents a defer duration. The gNB 120 may determine the index i as i=0. Thus, the time length of the cyclic prefix extension signal 242 can be determined by:

In this way, the transmission 262 can be performed by the UE 110 or the gNB 120 at the starting point 252 of symbol n+1, after the transmission of the cyclic prefix extension signal 242.

In some embodiments, as shown in FIG. 2B, the channel access procedure 214 is performed and the time duration of the extended LBT 234 is 1*Tsl. The gNB 120 may determine the index i as i=1. The value of m is calculated by Table 1 and m=0, and thus the variable Δ _i for cyclic prefix extension signal is 1·T _sl. Accordingly, the time length of the cyclic prefix extension signal 244 can be determined by:

In this way, the transmission 264 can be performed by the UE 110 or the gNB 120 at the starting point 254 of symbol n+1, after the transmission of the cyclic prefix extension signal 244.

In some embodiments, as shown in FIG. 2C, the channel access procedure 216 is performed and the time duration of the extended LBT 236 is 2*Tsl. The gNB 120 may determine the index i as i=2. The value of m is calculated by Table 1 and m=1, and thus the variable Δ _i for cyclic prefix extension signal is

Accordingly, the time length of the cyclic prefix extension signal 246 can be determined by:

In this way, the transmission 266 can be performed by the UE 110 or the gNB 120 at the starting point 256 of symbol n+2, after the transmission of the cyclic prefix extension signal 246.

With reference to FIGs. 2A-2C, some embodiments with the index i=0, 1, 2 are described. It should be understood that the embodiments with the index i=3 is similar with the embodiments with the index i=2 shown in FIG. 2C, therefore will not be described redundantly.

With regard to the index i=4, the time length of the cyclic prefix extension signal can be as 0 according to Table 1. That is to say, there is no need to transmit the cyclic prefix extension signal before the intended transmission and the ending point of the channel access procedure is aligned with the starting point of the symbol for transmission.

It should be understood that, the index can be indicated or configured by the gNB 120 in case the first transmission is initiated by the UE 110, the index can be determined and used by the gNB 120 in case the first transmission is initiated by the gNB 120.

Based on the embodiments with reference to FIGs. 2A-2C, if the ending point of the channel access procedure for initiating the channel occupancy for communication between the UE 110 and the gNB 120 is not aligned with the boundary of the symbol after the channel access procedure, the cyclic prefix extension signal of the first symbol (i.e., symbol 1) of the intended transmission may be transmitted within the gap between the ending point of the channel access procedure and the starting point of the symbol, in this regard, the intended transmission may be started at the starting point of the symbol and the gNB/UE’s transmission is aligned with symbol boundary.

In some embodiments of the present disclosure, when the gNB 120 or the UE 110 has not transmitted a transmission after a successful channel access procedure, an additional channel access procedure can be performed immediately before the intended transmission.

Specifically, when an intended transmission has not transmitted after a successful channel access procedure due to misalignment between the ending point of the channel access procedure for initiating a channel occupancy and symbol boundary or due to a transmitter (of the gNB 120 or the UE 110) being unready for transmission, a gNB/UE behavior can be specified for pending transmission based on an additional channel access procedure.

The additional channel access procedure has a defer sensing duration, which can be represented as Tx. Tx can be predefined as a fixed value, or can be configured with a value within a specific range, for example, [1, 2, 3, 4, 5] μs.

In some example embodiments, if the UE 110 or the gNB 120 has not transmitted a transmission after the successful channel access procedure, the UE 110 or the gNB 120 may perform a transmission on the channel if the channel has been sensed to be idle during a defer sensing duration Tx immediately before this transmission. Specifically, If the UE 110 has not transmitted a UL transmission on a channel on which UL transmission (s) are performed after the channel access procedure, the UE 110 may transmit a transmission on the channel if the channel has been sensed to be idle during a defer sensing duration Tx immediately before this transmission. If the gNB 120 has not transmitted a transmission after the channel access procedure, the gNB 120 may transmit a transmission on the channel if the channel has been sensed to be idle during a defer sensing duration Tx immediately before this transmission.

Alternatively, the channel may be sensed to be not idle during the defer sensing duration Tx immediately before the intended transmission, in this regard, the transmission cannot be transmitted due to the failed additional channel access procedure. In some embodiments, the channel access procedure for initiating a channel occupancy for communication between the UE 110 and the gNB 120 may be re-performed immediately after the failed additional channel access procedure. In some embodiments, the additional channel access procedure may be re-performed until it is successful and the channel access procedure for initiating a channel occupancy for communication between the UE 110 and the gNB 120 may be re-performed immediately after the successful additional channel access procedure. In some embodiments, a transmission on the channel can be performed until the channel has been sensed to be idle after sensing the channel to be idle during another defer sensing duration Ty immediately before this transmission.

It should be understood that the another defer sensing duration Ty can be predefined as a fixed value, or can be configured with a value within a specific range, for example, [1, 2, 3, 4, 5] μs. Ty may be equal to or different from Tx, and the scope of the present disclosure is not limited in this regard.

Now the reference is made to FIGs. 3A-3D, which show time diagrams for the channel access. In some embodiments, the UE 110 may initiate the first transmission related to a random access procedure by itself, or the UE 110 may initiate the first PUSCH/SRS/PUCCH transmission using configured grant scheduled by the gNB 120. In some embodiments, the gNB 120 may initiate the first PDSCH/PDCCH transmission, or the gNB 120 may initiate the first transmission with discovery burst. The UE 110 or the gNB 120 may perform a channel access procedure for initiating a channel occupancy for transmission between the UE 110 and the gNB 120.

As shown in FIGs. 3A-3D, an ideal channel access procedure should be ended at a boundary of a symbol (for example, a time point 310) , however, the actual channel access procedure 312 may be ended within a symbol, for example, the channel access procedure ends at time point 320 as shown in FIGs. 3A-3D.

In this regard, an additional channel access procedure having a predefined duration Tx can be performed immediately before the intended transmission.

In some embodiments, as shown in FIG. 3A, an additional channel access procedure 322 with a duration 332 performed before the intended transmission 352 is successful, and the transmission 352 can be started at the starting point 330 of the symbol (symbol n+1 as shown in FIG. 3A) following the additional channel access procedure 322. It can be seen that the ending point of the additional channel access procedure 322 is aligned with the starting point 330 of the symbol and the UE 110 or the gNB 120 may transmit a transmission 352 if the channel is sensed to be idle during the defer sensing duration Tx 332 of the additional channel access procedure 322 immediately before the transmission 352.

In some embodiments, as shown in FIG. 3B, an additional channel access procedure 324 with a duration 334 is failed, and the channel access procedure 314 may be re-performed for using the channel following the failed additional channel access procedure 324. The re-performed channel access procedure 314 can be started immediately after the failed additional channel access procedure 324, that is, at the starting point 330 of the symbol (symbol n+1 as shown in FIG. 3B) after the additional channel access procedure 324. In other words, if the channel has been sensed to be not idle during the defer sensing duration Tx 334 immediately before the intended transmission, the UE 110 or the gNB 120 proceeds back to the channel access procedure 314 for initiating a channel occupancy for communication between the UE 110 and the gNB 120.

In some embodiments, as shown in FIG. 3C, an additional channel access procedure 324 with a duration 334 is failed, and the additional channel access procedure 326 with a duration 336 may be re-performed following the failed additional channel access procedure 324 until the additional channel access procedure is successful. Additionally, a channel access procedure 316 can be re-performed immediately after the successful additional channel access procedure 326. Since the additional channel access procedure 326 can be regarded as a re-performed one of the additional channel access procedure 324, the duration 336 equals to the duration 334, both are represented as Tx. In other words, if the channel has been sensed to be not idle during the defer sensing duration Tx 334 immediately before the intended transmission, the UE 110 or the gNB 120 proceeds back to the channel access procedure 316 after sensing the channel to be idle during the defer sensing duration Tx 336.

In some embodiments, as shown in FIG. 3D, an additional channel access procedure 324 with a duration 334 is failed, and another additional channel access procedure 328 with a duration 338 may be performed immediately before the starting point 340 of the next following symbol (symbol n+1 as shown in FIG. 3D) . Additionally, a transmission 354 can be performed immediately after the successful another additional channel access procedure 328. In other words, if the channel has been sensed to be not idle during the defer sensing duration Tx 334 immediately before the intended transmission, the UE 110 or the gNB 120 may transmit a transmission 354 on the channel until the channel has been sensed to be idle after sensing the channel to be idle during a defer sensing duration Ty 338 immediately before this transmission 354. It should be understood that the duration 338 (Ty) can be equal to or can be different from the duration 334 (Tx) , and the scope of the present disclosure is not limited in this regard.

Based on the embodiments with reference to FIGs. 3A-3D, if the ending point of the channel access procedure for initiating a channel occupancy for communication between the UE 110 and the gNB 120 is not aligned with the boundary of the symbol after the channel access procedure, an addition channel access procedure with a predefined duration Tx can be performed immediately before the intended transmission. In this regard, the transmission on the channel can be performed only when the channel is sensed to be idle during the predefined duration Tx, and the intended transmission may be started at the starting point of the symbol and the gNB/UE’s transmission is aligned with symbol boundary.

In some embodiments of the present disclosure, when the gNB 120 or the UE 110 has not transmitted a transmission after a successful channel access procedure, an additional channel access procedure can be performed after the channel access procedure and before the starting point of the symbol after the channel access procedure, additionally, a cyclic prefix extension signal can be transmitted immediately after the successful additional channel access procedure.

Now the reference is made to FIG. 4, which shows a time diagram for the channel access. As shown in FIG. 4, an ideal channel access procedure should be ended at a boundary of a symbol (for example, a time point 410) , however, the actual channel access procedure 412 may be ended within a symbol, for example, the channel access procedure ends at time point 420 as shown in FIG. 4.

An additional channel access procedure 422 with a duration 432 is performed after the channel access procedure, and an ending point 440 of the additional channel access procedure 422 is not aligned with a starting point 430 of the symbol after the channel access procedure 412, for example symbol n+1 as shown in FIG. 4. In this regard, a cyclic prefix extension signal 424 can be transmitted within a gap between the ending point 440 of the additional channel access procedure 422 and the starting point 430 of the symbol. In this way, the transmission 452 can be performed by the UE 110 or the gNB 120 at the starting point 430 of symbol n+1, after the transmission of the cyclic prefix extension signal 424.

The duration 432 of the additional channel access procedure 422 can be referred as a defer sensing duration, and it can be represented as Tz. Tz can be predefined as a fixed value, or can be configured with a value within a specific range, for example, [1, 2, 3, 4, 5] μs. As an example, Tz can equal to Tx or Ty described above, or Tz can be different from Tx or Ty.

A time length 434 of the cyclic prefix extension signal 424 of the first symbol of the intended transmission 452 is equal to a length of the gap between the ending point 440 of the additional channel access procedure 422 and the starting point 430 of the symbol (symbol n+1 as shown in FIG. 4) . The similar description about the time length of the cyclic prefix extension signal may refer to FIGs. 2A-2C and will not be redundantly herein.

In some embodiments of the present disclosure, in case there is a gap between an ending point of the channel access procedure and a starting point of a symbol after the channel access procedure, a short control signalling can be introduced and transmitted within the gap, accordingly, the intended transmission can be performed at the starting point of the symbol after the channel access procedure.

The short control signalling may refer to a directional channel reservation signal, and the short control signalling transmission may refer to transmitting management and control signal without performing the channel access procedure before transmission for sensing the presence of other signals. The use of Short Control Signalling Transmissions shall be constrained as follows: the total duration of the device’s Short Control Signalling Transmissions shall be less than 10 ms within an observation period of 100ms. In other words, a duty ratio for transmitting the short control signalling shall less than 1/10.

Alternatively, a total duration for transmitting the short control signalling is less than a threshold within an observation period. As an example, the threshold can be represented as T1 and the observation period can be represented as T0, where T1<T0. For example, T0=100 ms and T1=10 ms, but those skilled in the art should understand that T0 and T1 may be other values, and the scope of the present disclosure is not limited in this regard.

In some example embodiments, information contained in the short control signalling can be predefined, such as synchronization information, sounding reference signal (SRS) , a DCI signalling scrambled with a specific RNTI, or a specific preamble and so on, where the information may or may not be specific/unique to the device transmitting the short control signalling.

It should be understood that the short control signalling can include other information and will not be listed in detail, the short control signalling can also be called as other signal (such as channel reservation signal) or information, and the scope of the present disclosure is not limited in this regard. It should be noted that the short control signalling is transmitted in the direction of intended traffic transmission and the duty ratio should be less than 1/10.

In this way, by the aid of introducing a new defined short control signalling, the gap between the ending point of the channel access procedure and symbol boundary can be filled or marked to align with the symbol boundary.

Now the reference is made to FIGs. 5A-5C, which show time diagrams for the channel access. As shown in FIGs. 5A-5C, an ideal channel access procedure should be ended at a boundary of a symbol (for example, a time point 510) , however, the actual channel access procedure 512 may be ended within a symbol, for example, the channel access procedure ends at time point 520.

In this regard, a short control signalling can be transmitted immediately after the channel access procedure.

In some embodiments, as shown in FIG. 5A, a short control signalling 522 with a predefined time length 532 can be transmitted immediately after the channel access procedure 512. Further, the transmission 552 can be started at the starting point 530 of the symbol (symbol n+1) after the channel access procedure 512.

In some embodiments, as shown in FIG. 5B, a short control signalling 524 with a predefined time length 534 can be transmitted immediately after the channel access procedure 512, and an additional channel access procedure 526 can be performed immediately before the transmission 554. As an example, the additional channel access procedure 526 can be a Category 2 channel access procedure. The additional channel access procedure 526 has a sensing duration 536, which can be a predefined fixed value, or it can be preconfigured.

It should be understood that the time length 532 in FIG. 5A or the time length 534 in FIG. 5B can be a predefined fixed value. Alternatively, the time length 532 in FIG. 5A can be determined based on the number of bits comprised by the short control signalling 522, similarly the time length 534 in FIG. 5B can be determined based on the number of bits comprised by the short control signalling 524. The time length 532 may be equal to or may be different from the time length 534, and the scope of the present disclosure is not limited in this regard.

In some embodiments, as shown in FIG. 5C, a short control signalling 528 can be transmitted immediately after the channel access procedure 512 and preceding the transmission 556. In other words, the short control signalling transmission fills the gap between the ending point 520 of the channel access procedure 512 and the starting point 530 of the symbol (symbol n+1 as shown in FIG. 5C) after the channel access procedure 512.

Based on the embodiments with reference to FIGs. 5A-5C, if the ending point of the channel access procedure for initiating a channel occupancy for communication between the UE 110 and the gNB 120 is not aligned with the boundary of a symbol (for example, symbol n as shown in FIGs. 5A-5C) , a short control signalling can be transmitted immediately following the channel access procedure. In this regard, the channel can be marked to be occupied, and the intended traffic transmission may be performed at the starting point of the next symbol (for example, symbol n+1 as shown in FIGs. 5A-5C) , namely the starting point of gNB/UE’s transmission is aligned with symbol boundary.

In this way, the alignment between the transmission and symbol boundary can be guaranteed for operation in mmWave band.

FIG. 6 illustrates a flowchart of an example method 600 in accordance with some embodiments of the present disclosure. The method 600 can be implemented at a first device, and the first device can be a terminal device 110 or a network device 120 as shown in FIG. 1. It is to be understood that the method 600 may include additional blocks not shown and/or may omit some blocks as shown, and the scope of the present disclosure is not limited in this regard.

At block 610, the first device determines a gap between an ending point of a first channel access procedure and a starting point of a symbol after the first channel access procedure, and the first channel access procedure is associated with a channel occupancy initiated by the first device for a channel between the first device and at least one second device.

At block 620, the first device performs a second channel access procedure within the gap, and the second channel access procedure has a first pre-determined duration.

At block 630, if the first device determines that the second channel access procedure is successful, the first device performs a communication with the at least one second device on the channel at the starting point of the symbol.

The sensing duration of the first channel access procedure is associated with a sensing interval (such as 8μs) , a sensing slot duration (such as 5μs) and a random value within a predefined range (such as 0 to Max with Max is not lower than 3) .

In some embodiments, an ending point of the second channel access procedure may be aligned with the starting point of the symbol. That is, the second channel access procedure is performed by the first device immediately before the intended communication.

The first pre-determined duration of the second channel access procedure can be Tx, which is preconfigured by the network device 120, in case the first device is the terminal device 110.

In case the second channel access procedure is successful, i.e., the channel is sensed to be idle during the first pre-determined duration, the communication can be performed by the first device immediately after the successful second channel access procedure. FIG. 3A may be referred as an example embodiment.

In case the second channel access procedure is failed, i.e., the channel is sensed to be not idle during the first pre-determined duration, at least one further channel access procedure is required.

In some embodiments, if the first device determines that the second channel access procedure is failed, the first device may perform a third channel access procedure immediately after the second channel access procedure, and the third channel access procedure has the first pre-determined duration. Further, in case that the third channel access procedure is failed, the first device may re-perform the third channel access procedure immediately after the previous failed third channel access procedure until the third channel access procedure is successful, and re-perform the first channel access procedure immediately after the successful third channel access procedure. It should be understood that the first device can perform the third channel access procedure at least once, and the first channel access procedure is re-performed thereafter in case the third channel access procedure is successful the first time, FIG. 3C may be referred as an example embodiment. If the third channel access procedure is performed multiple times, it is understood that only the third channel access procedure the last time is successful.

In some embodiments, if the first device determines that the second channel access procedure is failed, the first device may re-perform the first channel access procedure immediately after the second channel access procedure. FIG. 3B may be referred as an example embodiment.

In some embodiments, if the first device determines that the second channel access procedure is failed, the first device may perform a fourth channel access procedure having a second pre-determined duration, and an ending point of the fourth channel access procedure is aligned with a starting point of a symbol after the fourth channel access procedure. Further, if the first device determines that the fourth channel access procedure is successful, the first device may perform the communication with the at least one second device immediately after the fourth channel access procedure. FIG. 3D may be referred as an example embodiment.

The second pre-determined duration of the fourth channel access procedure can be Ty, which is preconfigured by the network device 120, in case the first device is the terminal device 110.

In some embodiments, the first device may further transmit a short control signalling immediately after the first channel access procedure. A time length of the short control signalling or the number of bits included in the short control signalling may be predefined or preconfigured. FIG. 5B may be referred as an example embodiment.

In some embodiments, although the second channel access procedure performed by the first device at block 620 is successful, an ending point of the second channel access procedure may be not aligned with the starting point of the symbol. That is, there is another gap between the ending point of the second channel access procedure and the starting point of the symbol after the first channel access procedure. In some example embodiments, if the first devise determines that the ending point of the second channel access procedure is not aligned with the starting point of the symbol, the first device may transmit a cyclic prefix extension signal of the communication immediately after the second channel access procedure. In some examples, a time length of the cyclic prefix extension signal may be determined based on a difference between a length of a symbol and a parameter, that is, the length of a symbol minus the parameter, and the parameter may be associated with at least one of: a sensing interval, an index and the first pre-determined duration. FIG. 4 may be referred as an example embodiment.

In some embodiments, if the second channel access procedure performed by the first device at block 620 is failed, the first device may perform at least one further channel access procedure. As one example, the first device may re-perform the first channel access procedure immediately after the failed second channel access procedure. As another example, the first device may perform a third channel access procedure immediately after the failed second channel access procedure until the third channel access procedure is successful, and the first device may re-perform the first channel access procedure immediately after the successful third channel access procedure. As another example, the first device may perform a fourth channel access procedure immediately before a starting point of the next symbol, and the first device may perform a communication with the at least one second device immediately after the successful fourth channel access procedure.

In some embodiments, the first device comprises a terminal device 110 and the at least one second device comprises a network device 120. The communication in block 630 may be an uplink transmission from the terminal device 110 to the network device 120.

In some embodiments, the first device comprises a network device 120 and the at least one second device comprises at least one terminal device 110. The communication in block 630 may be a downlink transmission from the network device 120 to one terminal device 110 (unicast for example) or a plurality of terminal devices 110 (broadcast for example) .

FIG. 7 illustrates a flowchart of an example method 700 in accordance with some embodiments of the present disclosure. The method 700 can be implemented at a first device, and the first device can be a terminal device 110 or a network device 120 as shown in FIG. 1. It is to be understood that the method 700 may include additional blocks not shown and/or may omit some blocks as shown, and the scope of the present disclosure is not limited in this regard.

At block 710, the first device transmits information comprising a cyclic prefix extension signal or a short control signalling to at least one second device at an ending point of a first channel access procedure, and the first channel access procedure is associated with a channel occupancy initiated by the first device for a channel between the first device and the at least one second device.

At block 720, the first device performs a communication with the at least one second device on the channel at a starting point of a symbol after the first channel access procedure.

The sensing duration of the first channel access procedure is associated with a sensing interval (such as 8μs) , a sensing slot duration (such as 5μs) and a random value within a predefined range (such as 0 to Max with Max is not lower than 3) . In some embodiments, the first device may determines that there is a gap between the ending point of the first channel access procedure and the starting point of the symbol after the first channel access procedure.

In some embodiments, the information transmitted by the first device at block 710 may comprise a cyclic prefix extension signal. A time length for transmitting the cyclic prefix extension signal may be determined based on a difference between a length of a symbol and a parameter, that is, the length of a symbol minus the parameter, and the parameter may be associated with at least one of: a sensing interval, an index and the sensing slot duration of the first channel access procedure. FIGs. 2A-2C may be referred as some example embodiments.

In some embodiments, the information transmitted by the first device at block 710 may comprise a short control signalling and a duty ratio for transmitting the short control signalling may be less than 1/10. As an example, a time length of the short control signalling or the number of bits included in the short control signalling may be predefined or preconfigured, FIG. 5A may be referred as an example embodiment. As another example, the first device may transmit the short control signalling immediately after the first channel access procedure and preceding the communication, that is, the short control signalling transmission fills the gap, FIG. 5C may be referred as an example embodiment.

In some embodiments, the information transmitted by the first device at block 710 may comprise a short control signalling, and the first device may further perform a second channel access procedure immediately before the communication and after transmitting the short control signalling. The second channel access procedure may have a sensing duration Tz. FIG. 5B may be referred as an example embodiment.

Details for channel access in millimeter wave bands according to the present disclosure have been described with reference to FIGs. 1-7. Now an example implementation of the first device will be discussed below.

In some example embodiments, the first device comprises circuitry configured to: determine a gap between an ending point of a first channel access procedure and a starting point of a symbol after the first channel access procedure, where the first channel access procedure is associated with a channel occupancy initiated by the first device for a channel between the first device and at least one second device; perform a second channel access procedure within the gap, where the second channel access procedure has a first pre-determined duration; and in accordance with a determination that the second channel access procedure is successful, perform a communication with the at least one second device on the channel at the starting point of the symbol.

In some embodiments, an ending point of the second channel access procedure is aligned with the starting point of the symbol.

In some embodiments, the first device comprises circuitry configured to transmit a short control signalling immediately after the first channel access procedure.

In some embodiments, the first device comprises circuitry configured to: in accordance with a determination that the second channel access procedure is failed, perform a third channel access procedure immediately after the second channel access procedure, where the third channel access procedure has the first pre-determined duration; in case that the third channel access procedure is failed, re-perform the third channel access procedure immediately after the previous failed third channel access procedure until the third channel access procedure is successful; and re-perform the first channel access procedure immediately after the successful third channel access procedure.

In some embodiments, the first device comprises circuitry configured to: in accordance with a determination that the second channel access procedure is failed, re-perform the first channel access procedure immediately after the failed second channel access procedure.

In some embodiments, the first device comprises circuitry configured to: in accordance with a determination that the second channel access procedure is failed, perform a fourth channel access procedure having a second pre-determined duration, where an ending point of the fourth channel access procedure is aligned with a starting point of a symbol after the fourth channel access procedure; and in accordance with a determination that the fourth channel access procedure is successful, perform communication with the at least one second device immediately after the fourth channel access procedure.

In some embodiments, the first device comprises circuitry configured to in accordance with a determination that an ending point of the second channel access procedure is not aligned with the starting point of the symbol, transmit a cyclic prefix extension signal of the communication immediately after the second channel access procedure.

In some example embodiments, a time length for transmitting the cyclic prefix extension signal is determined based on a difference between a length of a symbol and a parameter, the parameter is associated with at least one of: a sensing interval, an index, or the first pre-determined duration.

In some embodiments, the first device comprises a terminal device 110 and the at least one second device comprises a network device 120, and the first device comprises circuitry configured to receive configuration information indicating the first pre-determined duration.

In some embodiments, the first device comprises a network device 120 and the at least one second device comprises at least one terminal device 110.

In some example embodiments, the first device comprises circuitry configured to: transmit, to at least one second device, information comprising a cyclic prefix extension signal or a short control signalling at an ending point of a first channel access procedure, where the first channel access procedure is associated with a channel occupancy initiated by the first device for a channel between the first device and the at least one second device; and perform communication with the at least one second device on the channel at a starting point of a symbol after the first channel access procedure.

In some embodiments, the information comprises the cyclic prefix extension signal, and a time length for transmitting the cyclic prefix extension signal is determined based on a difference between a length of a symbol and a parameter, where the parameter is associated with at least one of: a sensing interval, an index, or a sensing slot duration of the first channel access procedure.

In some embodiments, the information is the short control signalling, and a duty ratio for transmitting the information is less than 1/10.

In some embodiments, the first device comprises circuitry configured to perform a second channel access procedure immediately before the communication and after transmitting the short control signalling.

In some embodiments, the first device comprises a terminal device 110 and the at least one second device comprises a network device 120. In some embodiments, the first device comprises a network device 120 and the at least one second device comprises at least one terminal device 110.

FIG. 8 illustrates a simplified block diagram of a device 800 that is suitable for implementing embodiments of the present disclosure. The device 800 can be considered as a further example implementation of the terminal device 110 and/or the network device 120 as shown in FIG. 1. Accordingly, the device 800 can be implemented at or as at least a part of the terminal device 110, or the network device 120.

As shown, the device 800 includes a processor 810, a memory 820 coupled to the processor 810, a suitable transmitter (TX) and receiver (RX) 840 coupled to the processor 810, and a communication interface coupled to the TX/RX 840. The memory 810 stores at least a part of a program 830. The TX/RX 840 is for bidirectional communications. The TX/RX 840 has at least one antenna to facilitate communication, though in practice an Access Node mentioned in this disclosure may have several ones. The communication interface may represent any interface that is necessary for communication with other network elements, such as X2 interface for bidirectional communications between eNBs, S1 interface for communication between a Mobility Management Entity (MME) /Serving Gateway (S-GW) and the eNB, Un interface for communication between the eNB and a relay node (RN) , or Uu interface for communication between the eNB and a terminal device.

The program 830 is assumed to include program instructions that, when executed by the associated processor 810, enable the device 800 to operate in accordance with the embodiments of the present disclosure, as discussed herein with reference to Figs. 2-10. The embodiments herein may be implemented by computer software executable by the processor 810 of the device 800, or by hardware, or by a combination of software and hardware. The processor 810 may be configured to implement various embodiments of the present disclosure. Furthermore, a combination of the processor 810 and memory 820 may form processing means 850 adapted to implement various embodiments of the present disclosure.

The memory 820 may be of any type suitable to the local technical network and may be implemented using any suitable data storage technology, such as a non-transitory computer readable storage medium, semiconductor-based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory, as non-limiting examples. While only one memory 820 is shown in the device 800, there may be several physically distinct memory modules in the device 800. The processor 810 may be of any type suitable to the local technical network, and may include one or more of general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs) and processors based on multicore processor architecture, as non-limiting examples. The device 800 may have multiple processors, such as an application specific integrated circuit chip that is slaved in time to a clock which synchronizes the main processor.

Generally, various embodiments of the present disclosure may be implemented in hardware or special purpose circuits, software, logic or any combination thereof. Some aspects may be implemented in hardware, while other aspects may be implemented in firmware or software which may be executed by a controller, microprocessor or other computing device. While various aspects of embodiments of the present disclosure are illustrated and described as block diagrams, flowcharts, or using some other pictorial representation, it will be appreciated that the blocks, apparatus, systems, techniques or methods described herein may be implemented in, as non-limiting examples, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof.

The present disclosure also provides at least one computer program product tangibly stored on a non-transitory computer readable storage medium. The computer program product includes computer-executable instructions, such as those included in program modules, being executed in a device on a target real or virtual processor, to carry out the process or method as described above with reference to Figs. 11-22. Generally, program modules include routines, programs, libraries, objects, classes, components, data structures, or the like that perform particular tasks or implement particular abstract data types. The functionality of the program modules may be combined or split between program modules as desired in various embodiments. Machine-executable instructions for program modules may be executed within a local or distributed device. In a distributed device, program modules may be located in both local and remote storage media.

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

The above program code may be embodied on a machine readable medium, which may be any tangible medium that may contain, or store a program for use by or in connection with an instruction execution system, apparatus, or device. The machine readable medium may be a machine readable signal medium or a machine readable storage medium. A machine readable medium may include but not limited to an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples of the 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.

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

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

Claims

A method implemented at a first device, comprising:

determining a gap between an ending point of a first channel access procedure and a starting point of a symbol after the first channel access procedure, the first channel access procedure being associated with a channel occupancy initiated by the first device for a channel between the first device and at least one second device;

performing a second channel access procedure within the gap, the second channel access procedure having a first pre-determined duration; and

in accordance with a determination that the second channel access procedure is successful, performing communication with the at least one second device on the channel at the starting point of the symbol.
The method of claim 1, wherein an ending point of the second channel access procedure is aligned with the starting point of the symbol.
The method of claim 2, further comprising:

transmitting a short control signalling immediately after the first channel access procedure.
The method of claim 1, further comprising:

in accordance with a determination that the second channel access procedure is failed, performing a third channel access procedure immediately after the second channel access procedure, the third channel access procedure having the first pre-determined duration;

in case that the third channel access procedure is failed, re-performing the third channel access procedure immediately after the previous failed third channel access procedure until the third channel access procedure is successful; and

re-performing the first channel access procedure immediately after the successful third channel access procedure.
The method of claim 1, further comprising:

in accordance with a determination that the second channel access procedure is failed, re-performing the first channel access procedure immediately after the second channel access procedure.
The method of claim 1, further comprising:

in accordance with a determination that the second channel access procedure is failed, performing a fourth channel access procedure having a second pre-determined duration, an ending point of the fourth channel access procedure being aligned with a starting point of a symbol after the fourth channel access procedure; and

in accordance with a determination that the fourth channel access procedure is successful, performing communication with the at least one second device immediately after the fourth channel access procedure.
The method of claim 1, further comprising:

in accordance with a determination that an ending point of the second channel access procedure is not aligned with the starting point of the symbol, transmitting a cyclic prefix extension signal of the communication immediately after the second channel access procedure.
The method of claim 7, wherein a time length for transmitting the cyclic prefix extension signal is determined based on a difference between a length of a symbol and a parameter, the parameter is associated with at least one of: a sensing interval, an index, or the first pre-determined duration.
The method of claim 1, wherein the first device comprises a terminal device and the at least one second device comprises a network device, the method further comprising receiving configuration information indicating the first pre-determined duration.
The method of claim 1, wherein the first device comprises a network device and the at least one second device comprises at least one terminal device.
A method implemented at a first device, comprising:

transmitting, to at least one second device, information comprising a cyclic prefix extension signal or a short control signalling at an ending point of a first channel access procedure, the first channel access procedure being associated with a channel occupancy initiated by the first device for a channel between the first device and the at least one second device; and

performing communication with the at least one second device on the channel at a starting point of a symbol after the first channel access procedure.
The method of claim 11, wherein the information comprises the cyclic prefix extension signal, and wherein a time length for transmitting the cyclic prefix extension signal is determined based on a difference between a length of a symbol and a parameter, the parameter is associated with at least one of: a sensing interval, an index, or a sensing slot duration.
The method of claim 11, wherein the information is the short control signalling, and wherein a total duration for transmitting the short control signalling is less than a threshold within an observation period.
The method of claim 13, wherein a transmission of the short control signalling fills a gap between the ending point of a first channel access procedure and the starting point of the symbol.
The method of claim 13, further comprising:

performing a second channel access procedure immediately before the communication after transmitting the short control signalling.
The method of claim 11, wherein the first device comprises a terminal device, and wherein the at least one second device comprises a network device.
The method of claim 11, wherein the first device comprises a network device, and wherein the at least one second device comprises at least one terminal device.
A first device comprising:

a processor; and

a memory coupled to the processor and storing instructions thereon, the instructions, when executed by the processor, causing the first device to perform the method according to any of claims 1-10 or claims 11-17.
A computer readable medium having instructions stored thereon, the instructions, when executed on at least one processor, causing the at least one processor to perform the method according to any of claims 1-10 or claims 11-17.