Packet transmission

Abstract

The present disclosure provides a method (700) performed by a user equipment (UE) for transmitting a packet. The packet is transmitted (706) at a point in time. The point in time is determined based on a time offset. The time offset is determined based on a characteristic associated with the transmission of the packet.

Description

PACKET TRANSMISSIONTECHNICAL FIELD

[0001] Disclosed are embodiments related to a method for transmitting a packet, and a user equipment (UE) configured to operate in accordance with that method.BACKGROUND

[0002] Transmissions may take place in one or multiple channels. A typical way to perform a transmission is to use a channel access procedure (e.g., listen before talk (LBT)) to determine whether a channel is busy or idle (which potentially introduces some waiting time) and, once the channel access procedure is complete and the channel is idle, transmit on the corresponding channel(s).

[0003] Channel access procedures regulate the channel access of multiple users. As mentioned above, a typical requisite is to sense the channel as idle during a certain duration prior to transmission. Ideally, two users that aim for transmitting at the same time (in different frequencies) would see the channel as idle and start transmitting at the same time. That is, none of them would receive the transmission from the other user before they start their own transmission.

[0004] In practice, the synchronization between different users is not perfect. Consequently, a first user starting a transmission a few microseconds before a second user would block the channel for the second user (i.e., the second user would see the channel as busy). This would likely prevent the second user from transmitting in the channel, even if they intended to transmit on orthogonal frequencies.SUMMARY

[0005] Certain challenges presently exist. For instance, one user may block another user from accessing a channel (e.g. due to sub-symbol effects).

[0006] It is an object of the disclosure to obviate or eliminate at least some of the abovedescribed challenges associated with existing techniques.

[0007] Accordingly, in one aspect, there is provided a method performed by a user equipment (UE) for transmitting a packet. The method comprises transmitting the packet at a point in time. The point in time is determined based on a time offset. The time offset is determined based on a characteristic associated with the transmission of the packet.

[0008] In another aspect, there is provided a computer program comprising instructions which, when executed by processing circuitry of a UE, causes the UE to operate in accordance with the methods disclosed herein. In one embodiment, there is provided a carrier containing the computer program wherein the carrier is one of an electronic signal, an optical signal, a radio signal, and a computer readable storage medium.

[0009] In another aspect, there is provided a computer program product, embodied on a non-transitory machine-readable medium, comprising instructions which are executable by processing circuitry of a UE to cause the UE to operate in accordance with the methods disclosed herein.

[0010] In another aspect, there is provided a UE that is configured to operate in accordance with the methods disclosed herein. In some embodiments, the UE may comprise processing circuitry. The UE may comprise memory. The processing circuitry may be coupled to the memory.

[0011] An advantage of the embodiments disclosed herein is that they avoid (e.g. LBT) blocking between users and thereby increase the chance that a user will be able to access a channel.BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The accompanying drawings, which are incorporated herein and form part of the specification, illustrate various embodiments.

[0013] FIG. 1 illustrates an example resource pool.

[0014] FIG. 2 illustrates a slot that comprises multiple OFDM symbols.

[0015] FIG. 3 illustrates an example of resource reservation.

[0016] FIG. 4 illustrates two transmissions synchronized in time.

[0017] FIG. 5 illustrates two transmissions that are not synchronized in time.

[0018] FIG. 6 illustrates a system according to an embodiment.

[0019] FIG. 7 is a block diagram illustrating a process according to an embodiment.

[0020] FIG. 8 is a flowchart illustrating a process according to an embodiment.

[0021] FIG. 9 is a block diagram of a UE according to an embodiment.DETAILED DESCRIPTION

[0022] Generally, all terms used herein are to be interpreted according to their ordinary meaning in the relevant technical field, unless a different meaning is clearly given and / or isimplied from the context in which it is used. All references to a / an / the element, apparatus, component, means, step, etc. are to be interpreted openly as referring to at least one instance of the element, apparatus, component, means, step, etc., unless explicitly stated otherwise. The steps of any methods disclosed herein do not have to be performed in the exact order disclosed, unless a step is explicitly described as following or preceding another step and / or where it is implicit that a step must follow or precede another step. Any feature of any of the embodiments disclosed herein may be applied to any other embodiment, wherever appropriate. Likewise, any advantage of any of the embodiments may apply to any other embodiments, and vice versa. Other objectives, features and advantages of the enclosed embodiments will be apparent from the following description.

[0023] Some of the embodiments contemplated herein will now be described more fully with reference to the accompanying drawings. Other embodiments, however, are contained within the scope of the subject-matter disclosed herein, the disclosed subject-matter should not be construed as limited to only the embodiments set forth herein; rather, these embodiments are provided by way of example to convey the scope of the subject-matter to those skilled in the art.

[0024] As mentioned earlier, the present disclosure relates to a method for transmitting a packet, and a user equipment (UE) configured to operate in accordance with that method.

[0025] Sidelink communications are referred to herein. Sidelink (SL) is the name in the Third Generation Partnership Project (3 GPP) specifications of the interface used for direct communication between UEs, also referred to as device-to-device (D2D) communications. This is in comparison to typical cellular communications in which two LEs communicate via a base station by means of uplink (LIL) and downlink (DL) transmissions. The sidelink interface is sometimes referred to as the PC5 interface. The UL / DL interface is sometimes referred to as the Liu interface. As used herein a LIE is any device (e.g., mobile phone, smart sensor, computer, appliance, gateway, etc.) capable of wireless communication with another device.

[0026] 3 GPP specified the sidelink (SL) as part of Release 12 (Rel-12). The target use case (UC) was the Proximity Services (communication and discovery). Support was enhanced during Release 13 (Rel-13). In Release 14 (Rel-14), Long Term Evolution (LTE) sidelink was extensively redesigned to support vehicular communications (commonly referred to as vehicle-to-everything (V2X) or vehicle-to-vehicle (V2V)). Support was again enhanced during Release 15 (Rel-15). From the point of view of the lowest radio layers, theLTE SL uses broadcast communication. That is, transmission from a UE targets any receiver that is in range.

[0027] In Release 16 (Rel-16), 3 GPP introduced the sidelink for the Fifth Generation (5G) New Radio (NR). The driving UC were vehicular communications with more stringent requirements than those typically served using the LTE SL. To meet these requirements, the NR SL is capable of broadcast, groupcast, and unicast communications. In groupcast communication, the intended receivers of a message are typically a subset of vehicles near the transmitter, whereas in unicast communication, there is a single intended receiver.

[0028] Both the LTE SL and the NR SL can operate with and without network coverage and with varying degrees of interaction between the UEs and the network (NW) (e.g., base stations), including support for standalone, network-less operation.

[0029] Physical (PHY) sidelink channels are referred to herein. In sidelink, the following physical structures are defined:• Physical sidelink control channel (PSCCH). This channel carries sidelink control information (SCI) (sometimes referred to as a first stage SCI) that is useful for two purposes: o Scheduling of a corresponding physical sidelink shared channel (PSSCH) transmission. That is, the PSSCH contains information that is necessary for decoding the corresponding PSSCH (e.g., the time-frequency allocation, etc.). o Informing other uses about future utilization of the resources (i.e., reservation of resources for intended future transmissions).• Physical sidelink shared channel (PSSCH). This channel carries: o Additional SCI (a second stage SCI) that schedules the corresponding PSSCH transmission (e.g., modulation and coding scheme) and information related to hybrid automatic repeat request (HARQ). o Payload from a higher layer, including data payload and / or control payload.• Physical sidelink feedback channel (PSFCH). This channel carries one of: o HARQ feedback related to a PSSCH transmission (e.g., an acknowledgement (ACK) or negative ACK (NACK)) o An inter-UE coordination message with information about expected conflicts in future transmissions (e.g., collisions).• A sidelink synchronization signals block (S-SSB). This block carries:o A physical sidelink broadcast channel (PSBCH) carrying basic system information. o Synchronization signals.

[0030] An SL resource pool is referred to herein. Radio resources for SL communication are organized into an SL resource pool. An NR SL resource pool consists of radio resources spanning both a time and frequency domain. In the time domain, the SL resource pool consists of NR slots indexed in an ascending order, starting from index 0 up to a maximum index value. Once this maximum index is reached, the slot indexing is started again from index 0, and so on.

[0031] The resource pool is divided in frequency in sub-channels. A sub-channel is a collection of resource blocks (RBs) that are contiguous in the frequency domain. The subchannel is the minimum scheduling unit for transmission of data payload in the corresponding resource pool. That is, a data transmission (carrying a PSCCH and a PSSCH) must be allocated an integer number of sub-channels for transmission (see FIG. 1). FIG. 1 illustrates a resource pool for sidelink transmission with 3 sub-channels, each consisting of 4 RBs in frequency and a (periodically repeating) number of slots in time.

[0032] A sidelink transmission lasts one single sidelink slot, which consists of a configurable integer number of orthogonal frequency-division multiplexing (OFDM) symbols (up to 14 OFDM symbols, including an automatic gain control (AGC) symbol and guard period). A transmission starts at the beginning of the first OFDM symbol in a sidelink slot and ends at the end of the last symbol. This is illustrated in FIG. 2, which shows a sidelink slot with 14 OFDM symbols. The last symbol is used as a guard period (GP) (i.e., there is no transmission in the last symbol).

[0033] The starting and ending times of the OFDM symbols, slots, and transmissions are clearly defined. A UE is expected to respect them, up to its synchronization accuracy (which is tightly regulated by the 3GPP specifications).

[0034] Resource allocation for sidelink transmissions is referred to herein. The 3GPP specification defines two resource allocation modes for NR sidelink: (1) Network-based resource allocation and (2) Autonomous resource allocation.

[0035] Network-based resource allocation is a resource allocation mode in which the network selects the resources and other transmit parameters used by sidelink UEs. In some cases, the network may control every single transmission parameter. In other cases, thenetwork may select the resources used for transmission but may give the transmitter the freedom to select some of the transmission parameters, possibly with some restrictions. In the context of NR SL, 3GPP refers to this resource allocation mode as “Mode 1”.

[0036] Autonomous resource allocation is a resource allocation mode in which the UEs autonomously select the resources and other transmit parameters. In this mode, there may be no intervention by the network (e.g., out of coverage, unlicensed carriers without a network deployment, etc.) or very minimal intervention by the network (e.g., configuration of pools of resources, etc.). In the context of NR SL, 3GPP refers to this resource allocation mode as “Mode 2”.

[0037] Mode 1 and Mode 2 only describe the behavior of a UE when acting as a transmitter. From a receiver point of view, there is only one behavior. Moreover, the signals used by Mode 1 transmitters and by Mode 2 transmitters are identical. From a receiver point of view, there is no difference in how to treat them. In fact, the receiver is typically unaware of whether the transmitter is in Mode 1 or Mode 2.

[0038] SL transmissions and resource reservation is referred to herein. One type of SL transmission is a Physical Sidelink Control Channel (PSCCH) transmission that carries control information (e.g., control information indicating one or more reservations of sidelink resources that may be used by the transmitting (TX) UE in the future for additional SL transmissions). Another type of SL transmission is a Physical Sidelink Shared Channel (PSSCH) transmission that carries data payload (e.g. user plane data) as well as some additional control information.

[0039] Every PSSCH transmission can reserve up to two retransmissions for the same transport block (TB). In addition, the same 1st stage SCI can reserve the same (1, 2, or 3) radio resources (i.e., RBs) for transmission of a (single) different TB. This is illustrated in FIG. 3, which shows resource reservation for non-periodic transmissions.

[0040] Sidelink in an unlicensed spectrum is referred to herein. In Release 18 (Rel-18), 3GPP is working on developing mechanisms that enable the operation of SL communications in an unlicensed spectrum, sometimes referred to as “SL-Unlicensed” or “SL-U” for short. It is expected that SL-U design will take NR SL and NR unlicensed (NR-U) designs as a baseline. NR-U is the set of features in the cellular 5G NR system that are used for performing uplink / downlink transmissions in unlicensed spectrum.

[0041] A spectrum for unlicensed NR transmissions is referred to herein. The spectrum for unlicensed transmission is typically organized by regulatory bodies in a band that containsmultiple channels. Transmissions may take place in one or multiple channels. A typical way to perform a transmission is the following: (1) use a channel access procedure (e.g., listen before talk (LBT)) to determine whether the channel is busy or idle, potentially introducing some waiting time and (2) Once the channel access procedure is complete and the channel is idle, transmit on the corresponding channel(s).

[0042] Determining that a channel is busy or idle typically involves performing detection of signals or transmitted energy in the channel. For example, the channel may be declared as idle if the energy sensed in the channel is below a certain threshold.

[0043] Sub-symbol effects are referred to herein. In an unlicensed spectrum, the channel access procedures regulate the channel access of multiple users. As stated above, a typical requisite is to sense the channel as idle during a certain duration prior to transmission. Ideally, two users that aim for transmitting at the same time (in different frequencies), would see the channel as idle and start transmitting at the same time. That is, none of them would receive the transmission from the other user before they start their own transmission. This is illustrated in FIG. 4, which shows a transmission from user 1 and user 2 being perfectly synchronized in time (i.e., the respective transmissions start at the same time). They both see the channel as idle until they start their own transmission.

[0044] In practice, the synchronization between the different users is not perfect. That means that the transmissions of two users for the same slot or symbol may be offset by a small gap (e.g., a few microseconds (us)). Consequently, a first user starting a transmission a few microseconds before a second user would block the channel for the second user (i.e., the second user would see the channel as busy). This would likely prevent the second user from transmitting in the channel, even if they intended to transmit on orthogonal frequencies. This is shown in FIG. 5, which shows that a difference in synchronization for user 1 and user 2 result in their transmissions being slightly misaligned in time. Since the transmission from user 2 is starting slightly earlier than the transmission from user 1, user 1 may detect the channel as busy and defer its own transmission.

[0045] Sidelink transmission on multiple channels is referred to herein. In Rel-18 and coming releases, 3GPP is going to develop mechanisms for transmission on multiple channels including: (1) aggregation of multiple carriers (licensed or unlicensed) (from a lower layer perspective, this consists of individual transmissions on separate carriers); and (2) Wideband transmission spanning multiple channels (for unlicensed spectrum) (from a lower layer perspective, this corresponds to a single transmission spanning a large bandwidth).

[0046] Configuration and pre-configuration are referred to herein. In cellular systems, the network typically configures some parameters used by the UEs. This configuration is typically signaled by a NW node (e.g., a 5G base station (gNodeB (gNB)) to the UE (e.g., using Radio Resource Control (RRC) signaling, broadcast signaling such as Master Information Block (MIB) or System Information Block (SIB), or some other type of signaling). This is applicable to UEs performing sidelink transmissions if they are in coverage of a network. UEs that are out of network coverage but participate in sidelink communications, may be provided the corresponding parameters by means of a preconfiguration (e.g., stored in the UE’s Subscriber Identity Module (SIM)). Unless explicitly stated, the terms configuration, pre-configuration, or (pre-)configuration will be used to denote both ways of providing the corresponding configuration / parameters to a UE.

[0047] FIG. 6 illustrates a system 600 according to an embodiment. The system 600 includes a first UE 601 communicating with a second UE 602 (e.g. using an unlicensed channel) and a third UE 603 communicating with a fourth UE 604 (e.g. using the unlicensed channel). As noted above, a problem may occur in that if the third UE 603 begins transmitting shortly before the first UE 601, then the first UE 601 may not sense that the channel is idle and, therefore, may delay its transmission. This disclosure describes a way to overcome this problem.

[0048] FIG. 7 illustrates a method 700 according to an aspect of the disclosure. The method is performed by a user equipment (UE) and is for transmitting a packet. As illustrated by block 706 of FIG. 7, the method comprises transmitting the packet at a point in time. The point in time is determined based on a time offset. The time offset is determined based on a characteristic associated with the transmission of the packet. For example, the characteristic can be a characteristic of the packet that is to be transmitted and / or a characteristic of the transmission itself.

[0049] In some embodiments, the time offset may be different from a time offset used to determine another point in time for transmission of another packet. In some embodiments, the method may comprise one or both of determining the characteristic associated with the transmission of the packet, and determining the time offset based on the characteristic.

[0050] In some embodiments, the point in time may be determined as a start time of a time slot for performing the transmission of the packet plus the determined time offset, or a start time of a time slot for performing the transmission of the packet minus the determined time offset. In some embodiments, the method may comprise determining the time slot forperforming the transmission of the packet. In some embodiments, the method may comprise, prior to determining the time slot, determining that a channel for transmitting the packet is idle.

[0051] In some embodiments, the characteristic may be determined based on one or both of information about the packet and information contained within the packet. In some embodiments, the characteristic may comprise one or more of a size of the packet, a priority with which the packet is to be transmitted (e.g. relative to other packets), a mode of the transmission, information about a latency tolerated by the packet, information about a time remaining until the packet exceeds a maximum latency, information about a bandwidth allocated for the transmission, information about one or more channels allocated for the transmission, and whether the packet is to be transmitted on reserved resources or unreserved resources.

[0052] Examples of a characteristic of the packet include, but are not limited to, the size of the packet, the priority with which the packet is to be transmitted, the information about the latency tolerated by the packet, the information about the time remaining until the packet exceeds the maximum latency, and whether the packet is to be transmitted on reserved resources or unreserved resources. Examples of a characteristic of the transmission itself include, but are not limited to, the mode of the transmission, the information about the bandwidth allocated for the transmission, and the information about one or more channels allocated for the transmission.

[0053] In some embodiments, the information about the bandwidth allocated for the transmission may be indicative of one or both of whether a full or partial bandwidth is allocated for the transmission, and whether the bandwidth allocated for the transmission is greater than, less than, or equal to a first threshold. In some embodiments, the bandwidth may be a channel bandwidth.

[0054] In some embodiments, the information about one or more channels allocated for the transmission may be indicative of one or more of a number of channels allocated for the transmission, whether all channels are allocated for the transmission, and whether the number of channels allocated for the transmission is greater than, less than, or equal to a second threshold.

[0055] In some embodiments, the mode of the transmission is a first mode of the transmission in which the transmission is on resources scheduled by a network node, or a second mode of the transmission in which the transmission is on resources selected by theuser equipment. In some embodiments, the time offset determined if the mode of transmission is the first mode and the time offset determined if the mode of transmission is the second mode may be different.

[0056] In some embodiments, the time offset determined if the packet is to be transmitted on reserved resources and the time offset determined if the packet is to be transmitted on unreserved resources may be different. In some embodiments, the reserved resources can be resources reserved for a previous transmission.

[0057] In some embodiments, the information about the latency tolerated by the packet may be indicative of whether the latency tolerated by the packet is greater than, less than, or equal to a third threshold. In some embodiments, the time offset determined if the latency tolerated by the packet may be greater than the third threshold and the time offset determined if the latency tolerated by the packet is less than or equal to the third threshold may be different.

[0058] In some embodiments, the information about the time remaining may be indicative of whether the time remaining is greater than, less than, or equal to a fourth threshold. In some embodiments, the time offset determined if the time remaining is greater than the fourth threshold and the time offset determined if the time remaining is less than or equal to the fourth threshold may be different.

[0059] In some embodiments, transmitting the packet may comprise transmitting the packet over an unlicensed channel.

[0060] The method described herein can be useful in a variety of use cases. For example, the method can be for transmitting a packet to a sidelink wireless device. Therefore, the method for transmitting the packet can be used for sidelink transmission.

[0061] In one aspect, a transmitting UE (e.g. the first UE 601 and / or the third UE 603 in FIG. 6) may determine a time offset to be applied for transmitting a packet (e.g. on an unlicensed spectrum) based on a characteristic of the transmission.

[0062] In one aspect, there is provided a method for selecting a transmission time for a transmission of a packet (e.g. in an unlicensed channel) based on some characteristics of the transmission. The method may include the following steps:

[0063] (1) determine a slot for performing the transmission of the packet;

[0064] (2) determine a characteristic of the transmission (e.g., a characteristic of the packet to be transmitted);

[0065] (3) determine a time offset based on the determined characteristic; and

[0066] (4) transmit the packet in the determined slot using a time offset (e.g., the transmission starting earlier than the slot boundary or later than the slot boundary) that depends on the characteristic of the transmission. Herein, the characteristic of the transmission may also be referred to as the transmission characteristic.

[0067] Some example ways in which to determine the transmission characteristic will now be described.

[0068] The packet to be transmitted may contain, for example: data provided by layers above the PHY layer (e.g., RRC messages, application data, Media Access Control (MAC) Control Elements (CEs), etc.), control signaling from the PHY layer or any other layer; or a mixture of any of them.

[0069] In one embodiment, determining the transmission characteristic may comprise determining the transmission characteristic based on information about or contained within the packet to be transmitted. For example, some value provided as part of control signaling (e.g., a priority value, a retransmission number, a source / destination identifier (ID)). In one embodiment, the transmission characteristic may be the size of the packet.

[0070] In one embodiment, the transmission characteristic can depend on a sidelink resource allocation mode or characteristic of the resource allocation procedure. For example: (i) a transmission scheduled by a NW node (e.g., a gNB) (Mode 1); (ii) transmissions scheduled autonomously by the transmitter UE (Mode 2); (iii) transmissions on resources selected by means of a procedure using sensing / full sensing / partial sensing / random resource allocation; (iv) transmissions on resource selected using a coordination procedure (e.g., between UEs); (v) initial selection of a resource or reselection of a resource, etc.

[0071] In one embodiment, the transmission characteristic may be a bandwidth allocation. For example, whether the full channel bandwidth is used or not or whether the utilization of a channel bandwidth is above / below a certain absolute or relative threshold (e.g., at least N RBs or sub-channels or sub-carriers; at least P% of the RBs / sub- channels / sub-carriers in the channel are used).

[0072] In one embodiment, the transmission characteristic may be a number of channels used for transmitting the packet. For example, whether all the channels in a band are used or not; whether the number of utilized channels in a band is above / below a certain absolute or relative threshold (e.g., at least N channels in the band; at least P% of the channels in the band).

[0073] In one embodiment, the transmission characteristic can be a maximum latency that the packet may tolerate (e.g., a packet delay budget (PDB)) or the amount of time left until a packet exceeds such latency (e.g., a remaining PDB).

[0074] Some example ways in which to determine the time offset will now be described.

[0075] In one embodiment, the determination of the time offset may be fixed (i.e., deterministic) given the characteristic. For example, if the characteristic corresponds to a first characteristic, then a first offset can be determined, and if the characteristic corresponds to a second characteristic, then a second offset can be determined.

[0076] In another embodiment, the determination of the time offset given the characteristic can involve some randomness. For example, if the characteristic corresponds to a first characteristic, then a first offset can be determined with probability X (with 0<X<l) and a second offset can be determined with probability 1-X, and if the characteristic corresponds to a second characteristic, then a third offset can be determined with probability Y (with 0<Y<l) and a fourth offset can be determined with probability 1-Y.

[0077] The applicability of the methods disclosed herein may depend on some system (pre-)configuration. For example, the possibilities of multiplexing different users in frequency may restrict the offsets that can be selected. For example, if the system does not allow for multiplexing different users in frequency, then a number Ni of offsets may be configured or possible to select among. As another example, if two users may be multiplexed in frequency, then a number of offsets N2 may be configured or possible to select among.

[0078] Whether multiplexing in frequency is allowed or not, and the number of users that can be multiplexed in frequency in a channel, may be explicitly (pre-)configured or determined from some (pre-)configured parameter. For example, if a single sub-channel is configured for a channel, then it may be implicitly determined that frequency multiplexing is not allowed. In another example, if N sub-channels are configured, then it may be implicitly determined that up to N users may be multiplexed in frequency.

[0079] Different examples are described below. The different examples can be combined in many ways. For example, many examples use deterministic offsets, but the application of random offsets to these examples is a possible modification.

[0080] An example involving Mode 1 vs Mode 2 will first be described.

[0081] In this example, the offset can depend on the transmission mode. For example, for any transmissions on resources scheduled by a NW node, e.g. gNB (such as Mode 1 transmissions), an offset of -Ti may be applied (a negative offset can represent anadvancement with respect to the nominal time of the transmission), whereas for transmissions on resources (e.g. autonomously) selected by a UE (such as Mode 2 transmissions), an offset +T2 may be applied (a positive offset can represent an delay with respect to the nominal time of the transmission).

[0082] Thus, a transmission with nominal transmission time t = TTX may start:

[0083] (1) at time t = TTX + (-TI) (if all other requirements are met, in particular, if the channel access procedure allows for it) for a transmission scheduled by a NW node (e.g., a Mode 1 transmission, a transmission on a resource provided by a gNB in a dynamic or configured grant, etc.), or

[0084] (2) at time at time t = TTX + T2 (if all other requirements are met, in particular, if the channel access procedure allows for it) for a transmission scheduled by the UE itself (e.g., a Mode 2 transmission, a transmission on a resource selected by the UE, etc.).

[0085] In this way, transmissions on resources scheduled by a NW node (e.g. gNB) have a chance of starting earlier than transmissions on resources (e.g. autonomously) selected by a UE. Thus, the former can have a better chance of accessing the channel against the latter. The opposite effect is achieved by swapping the offsets. Ti and T2 may be pre-defined fixed values or they may be pseudo-random values.

[0086] An example involving transmission on (un)reserved resources will now be described.

[0087] In this example, the offset can be determined by the presence or absence of a reservation for the resources.

[0088] For example, for transmissions on resources that have been reserved by a previous transmission (e.g., by the SCI of an earlier transmission) an offset of -Ti may be applied (i.e., t = TTX-TI), but for transmissions on resources that have not been reserved by a previous transmission, an offset of +T2 may be applied (i.e., t = TTX+T2). TI and T2 may be pre-defined fixed values or they may be pseudo-random values.

[0089] An example involving priority will now be described.

[0090] In this example, the priority of the transmission can determine the offset. For example, for transmissions associated with a priority value Pl (e.g., signaled in an SCI, corresponding to a logical channel (of part) of the information transmitted, etc.), an offset of -Ti may be applied (i.e., t = TTX-TI), but for transmissions associated with a priority value P2, an offset of +T2 may be applied (i.e., t = TTX+T2). TI and T2 may be pre-defined fixed values or they may be pseudo-random values.

[0091] An example involving latency will now be described.

[0092] In this example, the PDB or remaining PDB can determine the offset. For example, for a packet with large PDB or large remaining PDB the probability of selecting an offset with (large) positive value (+V2) is higher than that of selecting an offset with (large) negative value (-V1). For example:Ti = -VI is selected with probability 10% 0 is selected with probability 20% Ti = +V2 is selected with probability 70%.

[0093] For packets with small PDB or remaining PDB the probability of selecting an offset with (large) positive value (+V2) is smaller than that of selecting an offset with (large) negative value (-V1). For example:Ti = -VI is selected with probability 70% 0 is selected with probability 20% Ti = +V2 is selected with probability 10%.

[0094] In this way, UEs with transmissions with a small PDB or remaining PDB are given a better chance of accessing the channel compared to UEs with transmissions with a larger PBD or remaining PBD.

[0095] FIG. 8 is a flow chart illustrating a method 701 performed by a UE in accordance with some embodiments. The method is for transmitting a packet. As illustrated by block 702 of FIG. 8, in some embodiments, the method may comprise determining a characteristic associated with the transmission of the packet. Thus, in some embodiments, the UE may determine the characteristic in the manner described herein.

[0096] As illustrated by block 704 of FIG. 8, in some embodiments, the method may comprise determining a time offset based on the determined characteristic. Thus, in some embodiments, the UE may determine the time offset in the manner described herein.

[0097] As illustrated by block 706 of FIG. 8, the method comprises transmitting the packet at a point in time. The point in time is determined based on the determined time offset.

[0098] FIG. 9 is a block diagram of a representative UE 800, according to some embodiments. The UE can be configured to operate in accordance with the methods described herein.

[0099] As shown in FIG. 9, the UE 800 may comprise processing circuitry (PC) 802. The PC 802 may include one or more processors (P) 855 (e.g., one or more general purpose microprocessors and / or one or more other processors, such as an application specific integrated circuit (ASIC), field-programmable gate arrays (FPGAs), and the like). The PC 802 can be configured to operate in accordance with the methods described herein.

[0100] The UE 800 may comprise communication circuitry 848. The communication circuitry 848 may be coupled to an antenna arrangement 849 comprising one or more antennas. The communication circuitry 848 may comprise a transmitter (Tx) 845 and a receiver (Rx) 847 for enabling the UE 800 to transmit data and receive data (e.g., wirelessly transmit / receive data).

[0101] The UE 800 may comprise a storage unit (or “data storage system”) 808. The storage unit 808 may include one or more non-volatile storage devices and / or one or more volatile storage devices. In embodiments where PC 802 includes a programmable processor, a computer readable storage medium (CRSM) 842 may be provided. CRSM 842 may store a computer program (CP) 843 comprising computer readable instructions (CRI) 844. CRSM 842 may be a non-transitory computer readable medium, such as, magnetic media (e.g., a hard disk), optical media, memory devices (e.g., random access memory, flash memory), and the like. In some embodiments, the CRI 844 of computer program 843 may be configured such that, when executed by PC 802, the CRI 844 causes the UE 800 to perform any of the steps described herein (e.g., steps described herein with reference to the flow charts and / or block diagrams). In other embodiments, the UE 800 may be configured to perform steps described herein without the need for code. That is, for example, PC 802 may consist merely of one or more application-specific integrated circuits (ASICs). Hence, the features of the embodiments described herein may be implemented in hardware and / or software.

[0102] There is thus also provided a computer program 843 comprising instructions 844 which, when executed by processing circuitry 802 of a UE 800, causes the UE 800 to operate in accordance with the method described herein.

[0103] There is also provided a computer program product, embodied on a non-transitory machine-readable medium 842 , comprising instructions 844 which are executable by processing circuitry 802 of a UE 800 to cause the UE 800 to operate in accordance with the method described herein.

[0104] Other embodiments of the present disclosure are defined in the following numbered statements:Statement 1. A method 701 (see FIG. 8) performed by a user equipment 800 for transmitting a packet (e.g., transmitting the packet over an unlicensed channel), the method comprising: determining (step 702) a characteristic associated with the transmission of the packet; determining (step 704) a time offset based on the determined characteristic; and transmitting (step 706a) the packet at a point in time determined based on the determined time offset.Statement 2. The method of Statement 1, further comprising: determining a slot for performing the transmission of the packet; and determining said point in time, t, wherein determining t comprises calculating: t = T_tx + T off, whereT_tx is the start time of the slot, andT off is the determined time offset.Statement 3. The method of Statement 1 or 2, wherein determining the characteristic comprises: determining a priority of packet; determining a mode of the transmission; determining a packet delay budget (PDB) for the packet; determining a remaining PDB for the packet; determining the characteristic based on information about or contained within the packet; and / or determining whether resources have been reserved for the transmission.Statement 4. The method of Statement 2, further comprising: prior to determining the slot, determining that a channel is idle.Statement 5. A computer program (843) comprising instructions (844) which when executed by processing circuitry (802) of a UE (800) causes the UE to perform the method of any one of Statements 1 to 4.Statement 6. A carrier containing the computer program of Statement 5, wherein the carrier is one of an electronic signal, an optical signal, a radio signal, and a computer readable storage medium (842).Statement 7. A user equipment, UE (800), the UE being configured to perform the methods disclosed herein.

[0105] While various embodiments are described herein, it should be understood that they have been presented by way of example only, and not limitation. Thus, the breadth and scope of this disclosure should not be limited by any of the above-described exemplary embodiments. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the disclosure unless otherwise indicated herein or otherwise clearly contradicted by context.

[0106] Additionally, while the processes described above and illustrated in the drawings are shown as a sequence of steps, this was done solely for the sake of illustration.Accordingly, it is contemplated that some steps may be added, some steps may be omitted, the order of the steps may be re-arranged, and some steps may be performed in parallel.

[0107] It should be noted that the above-mentioned embodiments illustrate rather than limit the idea, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims. The word “comprising” does not exclude the presence of elements or steps other than those listed in a claim, “a” or “an” does not exclude a plurality, and a single processor or other unit may fulfil the functions of several units recited in the claims. Any reference signs in the claims shall not be construed so as to limit their scope.

Claims

CLAIMS1. A method (700) performed by a user equipment for transmitting a packet, the method comprising: transmitting (706) the packet at a point in time, wherein the point in time is determined based on a time offset, and wherein the time offset is determined based on a characteristic associated with the transmission of the packet.

2. The method as claimed in claim 1, wherein: the time offset is different from a time offset used to determine another point in time for transmission of another packet.

3. The method as claimed in claim 1 or 2, comprising one or both of: determining (702) the characteristic associated with the transmission of the packet; and determining (704) the time offset based on the characteristic.

4. The method as claimed in any of the preceding claims, wherein: the point in time is determined as: a start time of a time slot for performing the transmission of the packet plus the determined time offset; or a start time of a time slot for performing the transmission of the packet minus the determined time offset.

5. The method as claimed in claim 4, comprising: determining the time slot for performing the transmission of the packet.

6. The method as claimed in claim 5, comprising: prior to determining the time slot, determining that a channel for transmitting the packet is idle.

7. The method as claimed in any of the preceding claims, wherein:the characteristic is determined based on one or both of information about the packet and information contained within the packet.

8. The method as claimed in any of the preceding claims, wherein the characteristic comprises one or more of: a size of the packet; a priority with which the packet is to be transmitted; a mode of the transmission; information about a latency tolerated by the packet; information about a time remaining until the packet exceeds a maximum latency; information about a bandwidth allocated for the transmission; information about one or more channels allocated for the transmission; and whether the packet is to be transmitted on reserved resources or unreserved resources.

9. The method as claimed in claim 8, wherein: the information about the bandwidth allocated for the transmission is indicative of one or both of: whether a full or partial bandwidth is allocated for the transmission; and whether the bandwidth allocated for the transmission is greater than, less than, or equal to a first threshold.

10. The method as claimed in claim 9, wherein: the bandwidth is a channel bandwidth.

11. The method as claimed in any of claims 8 to 10, wherein: the information about one or more channels allocated for the transmission is indicative of one or more of: a number of channels allocated for the transmission; whether all channels are allocated for the transmission; and whether the number of channels allocated for the transmission is greater than, less than, or equal to a second threshold.

12. The method as claimed in any of claims 8 to 11, wherein:the mode of the transmission is: a first mode of the transmission in which the transmission is on resources scheduled by a network node; or a second mode of the transmission in which the transmission is on resources selected by the user equipment.

13. The method as claimed in claim 12, wherein: the time offset determined if the mode of transmission is the first mode and the time offset determined if the mode of transmission is the second mode are different.

14. The method as claimed in any of claims 8 to 13, wherein: the time offset determined if the packet is to be transmitted on reserved resources and the time offset determined if the packet is to be transmitted on unreserved resources are different.

15. The method as claimed in claim 13 or 14, wherein: the reserved resources are resources reserved for a previous transmission.

16. The method as claimed in any of claims 8 to 15, wherein: the information about the latency tolerated by the packet is indicative of whether the latency tolerated by the packet is greater than, less than, or equal to a third threshold.

17. The method as claimed in claim 16, wherein: the time offset determined if the latency tolerated by the packet is greater than the third threshold and the time offset determined if the latency tolerated by the packet is less than or equal to the third threshold are different.

18. The method as claimed in any of claims 8 to 17, wherein: the information about the time remaining is indicative of whether the time remaining is greater than, less than, or equal to a fourth threshold.

19. The method as claimed in claim 18, wherein:the time offset determined if the time remaining is greater than the fourth threshold and the time offset determined if the time remaining is less than or equal to the fourth threshold are different.

20. The method as claimed in any of the preceding claims, wherein: transmitting the packet comprises transmitting the packet over an unlicensed channel.

21. A user equipment (800) configured to operate in accordance with the method as claimed in any of the preceding claims.

22. A computer program (843) comprising instructions (844) which, when executed by processing circuitry (802) of a user equipment (800), causes the user equipment (800) to operate in accordance with the method as claimed in any one of claims 1 to 20.

23. A computer program product, embodied on a non-transitory machine-readable medium(842), comprising instructions (844) which are executable by processing circuitry (802) of a user equipment (800) to cause the user equipment (800) to operate in accordance with the method as claimed in any one of claims 1 to 20.

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