Resource allocation in sidelink transmission systems

Abstract

A cellular system can enable user equipments to communicate directly with each other by using sidelink communication instead of through a base station. The user equipments can be allowed to select transmission resources according to an indication from the base station, or to select transmission resources autonomously. The invention provides a method that allows autonomous selection of transmission resources even if the user equipments are within the coverage of a base station.

Description

TECHNICAL FIELD

[0001] The following disclosure relates to resource allocation in sidelink transmission systems, and in particular to simultaneous operation of mode 1 and mode 2 procedures. BACKGROUND

[0002] Wireless communication systems such as the third generation (3G) mobile telephone standard and technology are well known. Such 3G standards and technology have been developed by the Third Generation Partnership Project (3GPP). Third generation wireless communication has generally been developed to support macrocellular mobile telephone communication. The communication systems and networks have evolved towards broadband and mobile systems.

[0003] In a cellular wireless communication system, user equipment (UE) is connected to a radio access network (RAN) over a wireless link. The radio access network comprises a set of base stations providing wireless links to user equipment located in cells covered by the base stations and an interface to a core network (CN) providing overall network control. It will be appreciated that the radio access network and the core network each perform respective functions relating to the overall network. For convenience, the term cellular network refers to the combined radio access network and core network and it will be appreciated that the term refers to the corresponding system for performing the disclosed functionality.

[0004] The Third Generation Partnership Project has developed a so-called Long Term Evolution (LTE) system, namely the Evolved Universal Mobile Telecommunications System Terrestrial Radio Access Network (E-UTRAN), for mobile access networks in which one or more macro cells are supported by base stations of eNodeB or eNB (Evolved NodeB). Currently, LTE systems are further evolving towards so-called 5G or NR (New Radio) systems in which one or more cells are supported by base stations of gNB. NR is proposed to use an Orthogonal Frequency Division Multiplexing (OFDM) physical transmission format.

[0005] New Radio adds many functions and features to the wireless strategy far beyond LTE operating on licensed spectrum. In addition, the New Radio protocol is intended to provide an option for operation on unlicensed radio bands, referred to as NR-U. When operating on unlicensed radio bands, gNBs and UEs must contend for physical medium / resource access with other devices. For example, Wi-Fi, NR-U, and LAA (Licensed Assisted Access) can use the same physical resources.

[0006] A trend in wireless communications is to provide services with lower latency and higher reliability. For example, NR aims to support ultra-reliable and low latency communications (URLLC), while massive machine type communications (mMTC) aims to provide low latency and high reliability for small data packet sizes, typically 32 bytes. A user plane latency of 1 ms has been proposed, with a reliability of 99.99999%, and a packet loss rate of 10 -5 or 10 -6 at the physical layer has been proposed.

[0007] Massive machine type communications services aim to support a large number of devices over a long life cycle through a highly energy efficient communication channel, with occasional and infrequent data transfer with each device. For example, a cell can be expected to support thousands of devices.

[0008] The following disclosure relates to various improvements to cellular wireless communication systems. SUMMARY

[0009] The invention provides a method of scheduling sidelink communications in a cellular communications network, comprising the step of sending an indication from a base station to at least one mobile station that the mobile station can select transmission resources using an in-coverage transmission resource selection procedure or using an autonomous transmission resource selection procedure, even if the mobile station is in-coverage.

[0010] The indication can be sent as an RRC message.

[0011] The autonomous transmission resource selection procedure can utilize a listen-before-transmit procedure at the mobile station to determine available transmission resources.

[0012] The in-coverage transmission resource selection procedure can comprise the base station receiving a resource request from the mobile station, and the base station sending an indication of transmission resources for the mobile station to use.

[0013] The indication of the selection procedure can only apply to a subset of a pool of resources available to the mobile station for transmission.

[0014] The indication of the selection procedure can allow the mobile station to use the autonomous transmission resource selection procedure for retransmission, even if the initial transmission or at least one earlier retransmission was made using the in-coverage transmission resource selection procedure.

[0015] The indication of the selection procedure can relate to a pool of resources that the mobile station can utilize autonomous selection, even if the mobile station is in-coverage of the base station.

[0016] The base station can use a sensing procedure before scheduling transmissions in the pool of resources that allow the autonomous transmission resource selection procedure.

[0017] The base station can allow autonomous selection of transmission resources according to a measure of channel utilisation.

[0018] The method can further comprise receiving an indication from the mobile station at the base station that the mobile station made an autonomous transmission resource selection of the selected resource.

[0019] The indication of the selected resource can comprise a sub-channel selected by the mobile station.

[0020] The indication of the selected resource can be received before or after the transmission.

[0021] The indication of the selected resource can be received on an uplink control channel.

[0022] The indication of the selected resource can be received on an uplink data channel.

[0023] The indication of the selected resource can be received within a time defined by the base station.

[0024] The indication of the selected resource can be received periodically.

[0025] The method can further comprise the step of cancelling a transmission by the base station, the resource of the transmission conflicting with the indicated resource selected by the user equipment for transmission.

[0026] The method can further comprise the step of scheduling a further transmission resource for the mobile station based on the indicated selected transmission resource.

[0027] The further transmission resource can be scheduled for a retransmission.

[0028] The base station can send a cancellation message to the mobile station in response to the indicated transmission resource selected by the mobile station for transmission.

[0029] The method can further comprise the step of sending an indication of a sidelink resource reserved by the base station to the mobile station.

[0030] The indication of the sidelink resource reserved by the base station can be sent only in relation to a pool of resources the mobile station is allowed to use autonomously when in coverage.

[0031] The indication can be sent periodically.

[0032] The indication can be sent in a set of common downlink control information.

[0033] The indication can comprise a reservation of transmission resources for a predetermined period of time.

[0034] The indication comprises a bitmap, the size of the bitmap being equal to the product of the number of sub-channels in the relevant resource pool and the number of time slots in the period for which the indication is applicable.

[0035] Each bit of the bitmap can be applicable to a respective subchannel and time slot, or a predefined set of subchannels and time slots.

[0036] The indication can comprise an indication of a change in resource reservation since a previous indication.

[0037] The application also provides a base station configured to perform the method described herein.

[0038] The application also provides a method of scheduling sidelink communications in a cellular communications network, comprising the step of receiving at a mobile station an indication from a base station that the mobile station can use an in-coverage transmission resource selection procedure or use an autonomous transmission resource selection procedure to select transmission resources, even when the mobile station is in-coverage.

[0039] The indication can be received as an RRC message.

[0040] The autonomous transmission resource selection procedure can utilise a listen-before-talk procedure at the mobile station to determine available transmission resources.

[0041] The in-coverage transmission resource selection procedure can comprise sending a request for transmission resources to the base station and receiving an indication of available transmission resources from the base station.

[0042] The indication of the selection procedure can only apply to a subset of a pool of resources available to the mobile station for transmission.

[0043] The indication of the selection procedure can allow the mobile station to use an autonomous transmission resource selection procedure for retransmission, even if the initial transmission or at least one earlier retransmission was made using an in-coverage transmission resource selection procedure.

[0044] The indication of the selection procedure can relate to a pool of resources that the mobile station can utilise autonomous selection, even when the mobile station is in-coverage of the base station.

[0045] The method can further comprise sending an indication to the base station of the resources selected by the mobile station using the autonomous selection procedure.

[0046] The indication of the selected resources can comprise subchannels selected by the mobile station.

[0047] The indication of the selected resources can be sent before or after the transmission.

[0048] The indication of the selected resources can be sent on an uplink control channel.

[0049] The indication of the selected resources can be sent on an uplink data channel.

[0050] The indication of the selected resources can be sent within a time defined by the base station.

[0051] The indication of the selected resources can be transmitted periodically.

[0052] The method can further comprise the step of receiving, from the base station, an indication of a further transmission resource scheduled for the mobile station based on the indicated selected transmission resources.

[0053] The further transmission resource can be scheduled for a retransmission.

[0054] The method can further comprise receiving, from the base station, a cancellation message related to the indicated selected transmission resources.

[0055] The method can further comprise the step of receiving, from the base station, an indication of sidelink resources reserved by the base station.

[0056] The indication of sidelink resources reserved by the base station can be received only in relation to a resource pool for which the mobile station is allowed to use autonomous selection when in-coverage.

[0057] The indication can be received periodically.

[0058] The indication can be received in a set of common downlink control information.

[0059] The indication can comprise a reservation of transmission resources for a predetermined time period.

[0060] The indication comprises a bitmap, the size of the bitmap being equal to the product of the number of sub-channels in the relevant resource pool and the number of time slots in the period for which the indication is applicable.

[0061] Each bit of the bitmap can be applicable to a respective sub-channel and time slot, or a predefined set of sub-channels and time slots.

[0062] The indication can comprise an indication of a change in the reservation of resources since a previous indication.

[0063] The invention also provides a mobile station configured to perform the methods described herein. BRIEF DESCRIPTION OF DRAWINGS

[0064] Further details, aspects and embodiments of the invention are described by way of example with reference to the accompanying drawings. The elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. Identical reference numerals have been used, where possible, to denote identical elements throughout the figures. In order to facilitate understanding, like reference numerals have been used in the various drawings.

[0065] Figure 1 selected elements of a cellular wireless communication network are shown; and

[0066] Figure 2 selected elements of a radio area network of a cellular wireless communication network of Figure 1 are shown. DETAILED DESCRIPTION

[0067] Those skilled in the art will recognize and appreciate that the details of the described examples are merely illustrative of some embodiments and that the teachings provided herein are applicable to a variety of alternatives.

[0068] Figure 1 A schematic diagram showing three base stations 102 (e.g., eNBs or gNBs, depending on the particular cellular standard and terminology) forming a cellular network is shown. Typically, each base station 102 will be deployed by a cellular network operator to provide geographic coverage to user equipment in the area. The base stations form a Radio Area Network (RAN). Each base station 102 provides wireless coverage to user equipment in its area or cell. The base stations 102 are interconnected by means of an X2 interface and connected to a core network 104 by means of an SI interface. It should be understood that only basic details are shown in order to illustrate key features of a cellular network. The relevant interface and component names are used as examples only, different systems operating on the same principles can use different nomenclature. Figure 1

[0069] Each base station 102 comprises hardware and software to implement the functionality of the RAN. This functionality includes communication with the core network and other base stations, transmission of control signals and data signals between the core network and user equipment, and maintaining wireless communication with user equipment associated with each base station. The core network 104 comprises hardware and software to implement network functionality, such as management and control of the overall network, and call routing and data routing.

[0070] In vehicle-to-vehicle (V2V) applications, UEs can be incorporated into vehicles, such as cars, trucks, and buses, among others. These vehicular UEs are able to communicate with each other both within the coverage of base stations managing and allocating resources and outside the coverage without any base station managing and allocating resources. In vehicle-to-anything (V2X) applications, vehicles can communicate not only with other vehicles, but also with infrastructure, pedestrians, cellular networks, and potentially other surrounding devices. Use cases for V2X include:

[0071] 1) Vehicle platooning - this enables vehicles to dynamically form a platoon to travel together. All vehicles in the platoon take information from the leading vehicle to perform platooning operations. This information allows the vehicles to travel closer together and in the same direction in a coordinated manner compared to when they are driving normally.

[0072] ​2) Extended sensors - This enables raw or processed data collected by local sensors or real-time video images to be exchanged between vehicles, road-side units, pedestrian devices, and V2X application servers. These vehicles can enhance their perception of the environment beyond what their own sensors can detect and have a broader and more comprehensive view of the local situation. High data rates are one of the key characteristics.

[0073] 3) Advanced driving - This enables semi- or fully-automated driving. Each vehicle and / or road-side unit (RSU) shares its perception data obtained from local sensors with nearby vehicles and allows vehicles to synchronize and coordinate their motion trajectories or operations. Each vehicle also shares its driving intentions with nearby vehicles.

[0074] 4) Remote driving - This enables remote drivers or V2X applications to operate remote vehicles for passengers who cannot drive themselves or are located in dangerous environments. For situations with limited variations and predictable routes, such as public transportation, cloud computing-based driving can be used. High reliability and low latency are the main requirements.

[0075] Figure 2 A base station 102 forming a RAN, and a sidelink transmitter (SL Tx UE) UE 150 and a sidelink receiver (SL Rx UE) UE 152 in the RAN are shown. The UEs 150 and 152 are described as transmitters and receivers only to explain during a particular communication, and their roles can equally be interchanged. The base station 102 is configured to wirelessly communicate with each of the SL Tx UE 150 and the SL Rx UE 152 over respective connections 154. The SL Tx UE 150 and the SL Rx UE 152 are configured to wirelessly communicate with each other over a sidelink 156.

[0076] Sidelink transmissions use TDD (half duplex) on a dedicated carrier, or on a shared carrier with traditional Uu transmissions between base stations and UEs. Resource pools of transmission resources are used to manage resources and allocations, and to manage interference between potentially concurrent transmissions. A resource pool is a set of time-frequency resources from which resources for transmissions can be selected. A UE can be configured with multiple transmit resource pools and receive resource pools.

[0077] There are two modes of operation for resource allocation for sidelink communications, depending on whether the UE is within the coverage of a cellular network. In Mode 1, V2X communications operate within the coverage of a base station (e.g., multiple eNBs or multiple gNBs). All scheduling and resource allocation can be done by the base station.

[0078] Mode 2 is applicable for cases where the V2X service operates outside the coverage of a cellular base station. Here, the UE needs to schedule itself. For fair utilization, the UE typically employs a sensing-based resource allocation. In Mode 2, the UE reserves resources for a transmission by sending a Sidelink Control Information (SCI) message indicating the resources to be used. The SCI informs the receiver (possibly a single UE in unicast, a group of UEs in groupcast, or all reachable UEs in broadcast) of the transmission details it can expect.

[0079] In certain cases, it can be beneficial for a UE to support both Mode 1 and Mode 2 operation when it is in the coverage of a base station. This allows the UE to choose the most suitable mode for each case. For example, the UE can have a traffic flow with very strict latency requirements that does not allow time for the traditional Mode 1 scheduling operation ((i) sending a scheduling request (SR) to the base station, (ii) the base station performing scheduling, (iii) the base station sending a scheduling command in downlink (DL) downlink control information (DCI), (iv) the UE sending a sidelink (SL) transmission on its scheduled resources). These steps add latency before the UE can transmit. The looser latency requirements can also be difficult to meet due to failed scheduled sidelink transmissions. The sidelink TX UE can have an un-delivered packet with a packet delay budget (PDB) close to expiration that does not have enough time to go through the traditional Mode 1 scheduling procedure. For safety-related applications where reliable delivery is critical, such as a fire alarm, the UE can be allowed to transmit without requesting resources from the base station. The signaling phase of the Mode 1 scheduling procedure can also be power-hungry due to the number of transmissions.

[0080] Accordingly, various methods and techniques are disclosed below to enable a UE to use both Mode 1 and Mode 2 for sidelink transmission resource scheduling when in the coverage of a base station. The coexistence of Mode 1 and Mode 2 can cause interference to Mode 2 scheduled transmissions in the coverage. Accordingly, the UE can communicate its behavior to the relevant base station so that it can properly configure its behavior. The methods and techniques listed below aim to address one or more of the following issues: improving QoS (latency, reliability) for strict latency requirements, the ability to transmit packets that are discarded due to the Mode 1 procedure exceeding the packet delay budget, and increasing efficiency due to improved flexibility of resource allocation.

[0081] As an initial configuration step, the base station can indicate to the user that it is allowed to use mode 2 resource allocation, even when the UE is in the coverage of the base station. This indication can be provided using any appropriate mechanism, for example using radio resource control (RRC) signalling, which is a high layer signalling. The configuration of the UE to perform autonomous resource allocation (i.e. mode 2) can be selected by the base station according to the general network status (e.g. as indicated in the buffer status report - configuration (BSR-Config) table, QoS / properties of the traffic flow (e.g. logical channel ID used in the buffer status report)) or also in response to a UE request to use this mode. For example, the UE can have traffic with QoS requirements that cannot be fulfilled when operating in mode 1. Also, the UE can have transmitted a transport block (TB) after a mode 1 resource allocation, requiring retransmission due to a failure, but it cannot be completed in the remaining packet delay budget (PDB).

[0082] To address the latter problem, the UE can be allowed to use mode 2 resource allocation for retransmission of a TB even if the first transmission (or early retransmission) was performed using mode 1.

[0083] The configuration of the UE to use mode 2 can apply to all sidelink transmissions of this UE or only to specific traffic flows. The UE will then use both mode 1 and mode 2 based allocation simultaneously. The configuration can be applied per UE or be set as part of the resource configuration, in which case it can be set as part of the resource pool configuration procedure.

[0084] In this disclosure, reference is made to mode 2 resource allocation as a general reference to the principle of the UE autonomously selecting the transmission resources, without base station control. This can include all steps of the mode 2 procedure defined in the standard or other methods of autonomous selection can be used. Therefore, all references to mode 2 resource allocation should be understood to include any appropriate method of resource allocation performed without base station control, that is, any method of autonomous resource allocation, as the context allows.

[0085] One particular feature of mode 2 operation is the use of a sensing based approach for resource allocation. Each UE listens to the resource reservations of other UEs and selects resources that do not collide with existing reservations. Additional refinements can also be provided to allow pre-emption of early reservations in certain cases. This sensing arrangement helps to avoid collisions with other autonomously selected UE transmissions, but can not avoid collisions with base station controlled transmissions.

[0086] Conflicts with base station controlled transmissions can be mitigated in the coverage of the base station by a control resource pool over which UEs are allowed to perform autonomous resource allocation. Each sidelink UE is configured with a set of resource pools for reception and a set of resource pools for transmission. When a UE is allowed to perform autonomous resource allocation, the UE only performs its autonomous resource selection over the resource pool(s) that have been indicated for autonomous selection in the coverage. In one example, the indication can be in the form of a subset of the transmission resource pools indicated for autonomous resource selection. In different designs, the resource pool for autonomous resource selection is configured to the user separately.

[0087] The base station can change the configuration of the resource pool (e.g., allow or prohibit autonomous resource allocation) according to the general network status and requirements. The resource pool configuration can indicate whether it can be used for both mode 1 (base station allocates sidelink resources) and mode 2 (autonomous resource selection) operation, or only for mode 2 operation, or only for mode 1 operation. It can be beneficial to configure a resource pool for only mode 2 operation, as then the base station will not schedule any transmissions over the resource pool, avoiding conflicts.

[0088] The configuration of a set of resource pools that operate in only one mode can be efficient in avoiding conflicts, but this relies on allocating appropriate resource sizes. An insufficient allocation of mode 2 resources can result in a large number of conflicts, degrading performance and to some extent defeating the benefit of allowing mode 2 allocation. An over-allocation of mode 2 resources will result in few conflicts and thus improve QoS, but also result in inefficient utilization of resources. Traffic flows can be difficult to predict, thus posing a challenge to accurately partitioning resources between the two modes.

[0089] Allowing both mode 1 and mode 2 operation in a resource pool can solve the difficulty of partitioning resources. The base station can prioritize resource pools that operate in only mode 1, but can use resource pools that are dual-mode when necessary to gain capacity, at the risk of increased conflicts. To reduce the probability of conflicts, the base station can also use a sensing operation over the mixed-mode resource pools to gain information of the resources selected by UEs operating in mode 2, and thus can schedule its transmissions over said resources, or can allocate resources in a mode 1 fashion to avoid conflicts with the above. This does not guarantee conflict-free scheduling by the base station, but at least adds a safeguard similar to mode 2 scheduling, by the base station avoiding scheduling UEs over resources where it is able to decode sidelink control information with sufficient power.

[0090] The base station can also perform sensing to evaluate various aspects of the network configuration. For example, sensing can provide information about channel busy ratio (CBR) and other usage details to select an appropriate resource pool configuration. For example, the base station can detect that resources allocated to mode 2 operation are insufficient and increase the allocation (either change the resource pool to mode 2 only or allow mode 2 operation on a previously mode 1 only resource pool), or vice versa.

[0091] By having the UEs indicate their mode 2 selected resources to the base station, collisions on the dual mode resource pool can be effectively reduced. The UEs can also provide additional information to the base station by sending their resource selection to the base station, providing additional data that can be configured. Additionally, the UEs can send their sensing results (instead of resource selection), which can be used by the base station. Thus, the base station can use all available information to configure the resource pool and perform resource scheduling on the resource pool, or in a mode 1 fashion to avoid collisions. The transmission of scheduling indication by in-coverage mode 2 UEs is helpful for resource pools that allow both mode 1 and mode 2. This is independent of the status of a given UE, whether it is running mode 2 only or mode 1-mode 2 simultaneously.

[0092] The options for transmitting relevant information from a UE performing autonomous selection to the base station are listed below. The data provided can range from a basic indication from the UE of the resources it will transmit on, to detailed information about scheduling and resource utilization. The indication can also include the user selected set of sub-channels. The time slot and sub-channel information, in combination, give the base station full knowledge of the time-frequency resources the user will transmit on. The UE can report the information of its resource selection either before transmission on the selected resources, or after transmission on the selected resources. The UE can be triggered to send the information after the autonomous allocated resources. The indication can be transmitted on the UE’s physical uplink control channel (PUCCH) resources using an appropriate format. The availability of PUCCH resources can not coincide with the selected resources, so the time of transmission of the information to the base station can be adjusted to coincide with the availability of PUCCH. Thus, in some cases, the UE can be forced to transmit the information to the base station either before or after transmission, depending on the time of the PUCCH resources. If the information becomes too large to transmit on the PUCCH, the uplink shared channel can be used (or a small size if needed).

[0093] The UE can be configured to send a report about its own mode 2 transmissions during a configured time interval. This information can include one or more of the number of mode 2 transmissions, the number of sub-channels used, or a full resource description. Such a report can be aperiodic and triggered by the base station, or sent periodically without specific requirements. In another option, the UE can be configured to report their sensing of a particular resource pool for a time interval. For example, the UE can report a cumulative snapshot of time-frequency resources (slots and sub-channels) providing the activity status on the particular resource pool that the UE sees. This is similar to a sensing window snapshot that the UE prepares for performing resource allocation in mode 2. These reports can be sent to the base station on the shared uplink channel or other appropriate channel.

[0094] The base station can utilize the mode 2 resource allocation information shared by the UE to the base station to reduce interference and collisions. If the base station receives an indication about the UE’s mode 2 allocation before it makes a transmission, it can take this into account in its own scheduling. If the base station has already scheduled its own transmission on the resource, or a mode 1 sidelink transmission, it can cancel the transmission, or if no transmission is planned, it can avoid scheduling a transmission on the indicated resource. If the indication received by the base station is too late to avoid a collision, then the mode 2 allocation can also include future resources for retransmission, or transmission of another TB. The base station can thus avoid those future resources (not schedule its own transmission, and avoid scheduling a mode 1 resource allocation), and improve the performance of the mode 2 transmission.

[0095] The base station can use the reported mode 2 resource allocation to schedule a mode 1 transmission for the UE in order to retransmit a TB that was originally scheduled using mode 2 allocation. This can be particularly suitable in cases where the base station cannot avoid a collision with the original mode 2 transmission. The trigger for the base station to schedule a mode 1 transmission can be the reception of an indication from the UE, which can include an additional indication that more resources are needed in addition to the currently autonomously selected resources. The request for more resources can be for retransmission of the current TB, or transmission of another TB. Responding to an explicit request ensures that the base station only makes an allocation when needed, thus avoiding a waste of resources.

[0096] The base station can also decide to allocate mode 1 resources based on other parameters, such as identified collisions. If the base station deems it appropriate based on the priority and / or QoS requirements of the mode 2 transmissions, it can schedule mode 1 transmissions for the affected UEs that select mode 2 resources in an autonomous manner and send a sidelink grant to the UE to improve the reliability and latency of the relevant data packets. Thus, with the additional transmission opportunity on the mode 1 scheduled resources, the UEs that transmit data packets through mode 2 resource selection increase their chances of successful transmission. The base station can also schedule one or more additional transmissions for the colliding mode 1 transmissions, as once a collision occurs, the interfering transmissions mean a degradation in the QoS of both mode 1 and mode 2 transmissions.

[0097] As mentioned above, the base station can also decide to cancel previously scheduled transmissions that overlap with mode 2 transmissions to avoid collisions. The base station can send a cancellation indication for the mode 1 transmissions, and the UEs cancel their scheduled transmissions, thus avoiding interference with the mode 2 transmissions.

[0098] In a different variant, the base station can send a cancellation indication to the mode 2 UEs themselves upon receiving a mode 2 scheduling indication. The cancellation indication can indicate to the mode 2 UEs to stop transmitting on the resources. This can happen, for example, if the base station has scheduled a high-priority mode 1 transmission on the resources. After the cancellation indication, the base station can send a mode 1 sidelink grant to the UEs for their transmission.

[0099] For a base station that has enabled UEs to operate in mode 2 in-coverage, the base station can send a resource indication of the scheduled mode 1 transmissions to UEs that can or are operating in mode 2. The UEs that receive the indication can use the information to schedule their mode 2 transmissions to avoid mode 1 transmissions, thus preventing collisions between base station scheduled and autonomously scheduled transmissions. The base station can send the information to all UEs in-coverage or to the UEs in the resource pools that are configured to allow operation in mode 2 in-coverage.

[0100] The base station can send the scheduling information periodically or dynamically. The information can be transmitted in a group common DCI, where UEs operating in mode 2 are configured to listen to the relevant group common DCI. The DCI can include scheduling information for a predetermined time period, which can be either statically pre-configured or variable. The information can include a bitmap whose size is equal to the product of the number of sub-channels in the resource pool and the number of slots in the indicated period. Each bit in the bitmap then represents the scheduling status of a given sub-channel in a given slot. To reduce the signaling overhead, a suitable granularity can be used. For example, multiple sub-signals can be represented with one bit (i.e. a bit). The bit then represents the scheduling status of the group of sub-channels, which can indicate that the sub-channels in the group are occupied if any of them are scheduled. In the most extreme case, the size of the bitmap can be equal to the number of slots in the specified period, with each bit representing whether any sub-channel in that slot is scheduled for mode 1 transmission.

[0101] In another example, the base station can send a compact periodic indication (delta indication) of a resource allocation change for a resource pool configured for simultaneous allocation of mode 1 and mode 2. The change can be indicated relative to the allocation in the previous indication interval. The absolute allocation of the resource pool is sent periodically with a longer period than the delta indication period. This reduces the signaling overhead between the base station and the UEs, while providing the UEs with an indication of the relevance of the results of their past SL resource sensing for upcoming mode 2 transmissions.

[0102] In summary, various methods and techniques are disclosed to allow simultaneous operation of mode 1 and mode 2 resource allocation (or more generally base station allocation and autonomous UE allocation) for sidelink communication by in-coverage UEs. The resource pool can be configured to allow only mode 1, only mode 2 or mixed operation.

[0103] A UE operating in mode 2 in-coverage can send scheduling information to the relevant base station to assist in avoiding collisions. The base station can use this information to guide its scheduling and / or schedule additional mode 1 resources for UEs transmitting in mode 2. The base station can also send its own scheduling information to the in-coverage UEs so that these UEs can use this information in their mode 2 scheduling decisions.

[0104] As will be appreciated, the techniques described herein are applicable to all types of sidelink transmissions, in particular to unicast, groupcast and broadcast transmissions.

[0105] While not shown in detail, any device or apparatus forming part of a network can comprise at least one processor, at least one storage unit, and at least one communication interface, wherein the processor, storage unit, and communication interface are configured to perform the method of any aspect of the application. Further options and choices are described below.

[0106] The signal processing functionality of embodiments of the application, particularly the gNB and the UE, can be implemented using a computer system or architecture known to those having ordinary skill in the art. The computer system used can be, for example, a desktop, laptop or notebook computer, handheld computing device (PDA, cell phone, palmtop, etc.), mainframe, server, client, or any other type of special or general purpose computing device that is desirable or suitable for given applications or environments. The computer system can include one or more processors that can be implemented using a general or special purpose processing engine such as a microprocessor, microcontroller or other control module.

[0107] The computer system can also include a main memory, such as random access memory (RAM) or other dynamic storage devices, for storing information and instructions to be executed by the processor. Such main memory also can be used for storing temporary variables or other intermediate information during execution of instructions by the processor. The computer system can likewise include a read only memory (ROM) or other static storage device for storing static information and instructions for the processor.

[0108] The computer system can further include an information storage system, which can include, for example, a media drive and a removable storage interface. The media drive can include a drive or other mechanism to support fixed or removable storage media, such as a hard disk drive, a floppy disk drive, a magnetic tape drive, an optical disk drive, a compact disk (CD) or digital video drive (DVD), a read or write drive (R or RW), or other removable or fixed media drive. Storage media can include, for example, a hard disk, floppy disk, magnetic tape, optical disk, CD or DVD, or other fixed or removable medium that is read by and written to by the media drive. Storage media can include a computer-readable storage medium having instructions or data embodied as computer-executable instructions stored thereon.

[0109] In other embodiments, an information storage system can include other similar components for allowing computer programs or other instructions or data to be loaded into a computer system. Such components can include, for example, a removable storage unit and an interface, such as a program cartridge and cartridge interface, a removable memory (for example, a flash memory or other removable memory module) and memory slot, and other removable storage units and interfaces that allow software and data to be transferred from the removable storage unit to the computer system.

[0110] The computer system can also include a communications interface. This communications interface can allow software and data to be transferred between the computer system and external devices. Examples of communications interface can include a modem, a network interface (such as an Ethernet or other NIC card), a communications port (such as a universal serial bus (USB) port), a PCMCIA slot and card, etc. Software and data transferred via the communications interface are in the form of signals which can be electronic, electromagnetic, and optical or other signals capable of being received by a communications interface.

[0111] In this document, the terms "computer program product," "computer-readable medium," and the like can be used generally to refer to tangible media such as memory, storage devices, or storage units. These, and other forms of computer-readable media, can store one or more instructions for use by one or more processors of a computer system to cause the processors to perform a certain operation. Such instructions, generally referred to as "computer program code" (which can be grouped in the form of computer programs or other groupings), when executed, enable a computer system to perform a function of the present embodiments. Note that the code that forms the computer program can directly cause a processor to perform a specified operation, be compiled to cause a processor to perform a specified operation, and / or be executed by one or more processors using, for example, the library routines of a standard operating system.

[0112] Non-volatile computer-readable media can include at least one of the following media in the group consisting of: a hard disk, a CD-ROM, an optical storage device, a magnetic storage device, a read-only memory, a programmable read-only memory, an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory, and a flash memory. In embodiments where elements are implemented using software, the software can be stored in a computer-readable medium and loaded into the computer system using, for example, a removable storage drive. The control module (in this example, software instructions or executable computer program code) when executed by a processor in the computer system causes the processor to perform the functions of the present embodiments as described herein.

[0113] Furthermore, the inventive concept can be applied to any circuitry performing signal processing functions within a network element. It is contemplated that, for example, semiconductor manufacturers design the various embodiments of the present inventive concept into the design of a standalone device, such as a microcontroller, or digital signal processor (DSP), or application specific integrated circuit (ASIC), and / or any other subsystem elements.

[0114] It should be appreciated that, for clarity, the above description has described embodiments of the present inventive concept with reference to a single processing logic. However, the inventive concept can equally be implemented by a plurality of different functional units and processors to provide the signal processing functionality. Accordingly, references to specific functional units are only to be seen as references to suitable means for providing the described functionality, rather than indicative of a strict logical or physical structure or organization.

[0115] Aspects of the application can be implemented in any suitable form including hardware, software, firmware or any combination of these. The application can optionally be implemented (at least partly) as computer software running on one or more data processors and / or digital signal processors or configurable module components such as FGPA devices.

[0116] Thus elements and components of an embodiment of the application can be physically, functionally and logically implemented in any suitable way. Indeed the functionality can be implemented in a single unit, in a plurality of units or as part of other functional units. As such, the application should not be limited to the specific embodiments described herein, but should be given a broad interpretation and the scope of the application is defined by the appended claims. Furthermore, although the features of the application are described in conjunction with particular embodiments, numerous modifications and / or additions are possible which fall within the scope of the application. For example, the order of the steps can differ from those described. Likewise, additives, not specifically described may

[0117] Also, although individual features can be discussed or claimed as important, the present application is not to be limited to these selected features. Rather, the scope of the present application includes all novel and / or nonobvious combinations of these and / or other features. In addition, singular references do not exclude a plurality. Thus references to "a", "an", "the", or "one" often are

[0118] Also, the order of the steps of the methods of the application is not limited to the order described. Further, the features of the application are not limited to use in the specific embodiments described herein, but can be employed in any number of environments and applications within the scope of the application described and / or claimed. Furthermore, the features of the application are not limited to use in the specific embodiments described herein, but can be employed in any number of environments and applications within the scope of the application described and / or claimed.

[0119] Although the application has been described in connection with some embodiments, it is not intended to be limited to the particular form set forth herein, but on the contrary, it is intended to cover such alternatives, modifications, and equivalents, as can be within the scope of the application. For example, it will be appreciated that features described in relation to one embodiment can be interchanged with features described in relation to another embodiment. As the skilled person will appreciate, various features of the described embodiments can be combined to form further embodiments of the application. In the claims, the term comprising does not exclude other elements or steps.

Claims

1. A method for scheduling sidelink communication in a cellular communication network, characterized in that, Includes the following steps: The base station sends an instruction to at least one mobile station, instructing the mobile station to select transmission resources using either the coverage-area transmission resource selection process or the autonomous transmission resource selection process, even when the mobile station is within the coverage area; and Send to the mobile station an indication of sidelink resources reserved by the base station. The indication includes a bitmap, the size of which is equal to the product of the number of subchannels in the relevant resource pool and the number of time slots in the time period to which the indication applies. Each bit of the bitmap is applied to the corresponding subchannel and time slot, or a predefined set of subchannels and time slots.

2. The method according to claim 1, characterized in that, The instruction is sent as an RRC message.

3. The method according to claim 1, characterized in that, The autonomous transmission resource selection process utilizes a listen-before-transmit procedure at the mobile station to determine available transmission resources.

4. The method according to claim 1, characterized in that, The transmission resource selection process within the coverage area includes the base station receiving a resource request from the mobile station, and the base station sending an indication of the transmission resources to be used by the mobile station.

5. The method according to claim 1, characterized in that, The selection process instructions apply only to a subset of the resource pool available for transmission by the mobile station.

6. The method according to claim 1, characterized in that, The selection process instruction allows the mobile station to use the autonomous transmission resource selection process for retransmission, even if the initial transmission or at least one earlier retransmission was performed using the coverage-based transmission resource selection process.

7. The method according to claim 1, characterized in that, The selection process is indicated in relation to the pool of resources that the mobile station can autonomously select, even if the mobile station is within the coverage area of ​​the base station.

8. The method according to claim 1, characterized in that, The base station uses a sensing process before scheduling transmissions from a resource pool that allows for autonomous transmission resource selection.

9. The method according to claim 1, characterized in that, The base station is allowed to autonomously select transmission resources based on a metric for channel utilization.

10. The method according to claim 1, characterized in that, The method further includes receiving an instruction from a mobile station at the base station, the mobile station autonomously selecting transmission resources for the selected resources.

11. The method according to claim 10, characterized in that, The indication of the selected resource includes the sub-channel selected by the mobile station.

12. The method according to claim 10, characterized in that, Receive instructions for the selected resource before or after transmission.

13. The method according to claim 10, characterized in that, Receive the indication of the selected resource on the uplink control channel.

14. The method according to claim 10, characterized in that, Receive the indication of the selected resource on the uplink data channel.

15. The method according to claim 10, characterized in that, Receive an indication of the selected resource within the time defined by the base station.

16. The method according to claim 10, characterized in that, Receive instructions for the selected resources periodically.

17. The method according to claim 10, characterized in that, The method further includes the step of canceling the transmission of the base station, wherein the transmission resource conflicts with the resource indicated to be selected by the user equipment for transmission.

18. The method according to claim 10, characterized in that, The method also includes scheduling additional transmission resources for the mobile station based on the indicated selected transmission resources.

19. The method according to claim 18, characterized in that, The additional transmission resources are scheduled for retransmission.

20. The method according to claim 10, characterized in that, The base station sends a cancellation message to the mobile station in response to the indicated transmission resources selected by the mobile station for transmission.

21. The method according to claim 1, characterized in that, The indication of the sidelink resources reserved by the base station is sent only in relation to the mobile station being allowed to use the autonomously selected resource pool when it is within coverage area.

22. The method according to claim 1, characterized in that, Send the instructions periodically.

23. The method according to claim 1, characterized in that, The instruction is sent in a set of common downlink control information.

24. The method according to claim 1, characterized in that, The instruction includes the reservation of transmission resources within a predetermined time period.

25. The method according to claim 1, characterized in that, The instructions include indications of changes in resource reservations since previous instructions.

26. A base station, characterized in that, The base station is configured to perform the method according to any one of claims 1 to 25.

27. A method for scheduling sidelink communication in a cellular communication network, characterized in that, The method includes the following steps: The mobile station receives an instruction from the base station instructing it to select transmission resources using either an in-coverage transmission resource selection process or an autonomous transmission resource selection process, even when the mobile station is within the coverage area; and The system receives an indication of sidelink resources reserved by the base station. The indication includes a bitmap, the size of which is equal to the product of the number of subchannels in the relevant resource pool and the number of time slots in the time period to which the indication applies. Each bit of the bitmap is applied to the corresponding subchannel and time slot, or a predefined set of subchannels and time slots.

28. The method according to claim 27, characterized in that, The instruction is received as an RRC message.

29. The method according to claim 27, characterized in that, The autonomous transmission resource selection process utilizes a listen-before-transmit procedure at the mobile station to determine available transmission resources.

30. The method according to claim 27, characterized in that, The process of selecting transmission resources within the coverage area includes sending a request for transmission resources to the base station and receiving an indication of available transmission resources from the base station.

31. The method according to claim 27, characterized in that, The selection process instructions apply only to a subset of the resource pool available for transmission by the mobile station.

32. The method according to claim 27, characterized in that, The selection process instruction allows the mobile station to use the autonomous transmission resource selection process for retransmission, even if the initial transmission or at least one earlier retransmission was performed using the coverage-based transmission resource selection process.

33. The method according to claim 27, characterized in that, The selection process is indicated in relation to the pool of resources that the mobile station can autonomously select, even if the mobile station is within the coverage area of ​​the base station.

34. The method according to claim 27, characterized in that, The method further includes sending an instruction to the base station that the mobile station uses resources selected by the autonomous selection process.

35. The method according to claim 34, characterized in that, The indication of the selected resource includes the sub-channel selected by the mobile station.

36. The method according to claim 34, characterized in that, Send an instruction for the selected resource before or after transmission.

37. The method according to claim 34, characterized in that, Send an indication of the selected resource on the uplink control channel.

38. The method according to claim 34, characterized in that, Send an indication of the selected resource on the uplink data channel.

39. The method according to claim 34, characterized in that, Instructions for the selected resources are transmitted within the time defined by the base station.

40. The method according to claim 34, characterized in that, Send instructions for the selected resources periodically.

41. The method according to claim 34, characterized in that, The method further includes the step of receiving from the base station an instruction to schedule additional transmission resources for the mobile station based on the indicated selected transmission resources.

42. The method according to claim 41, characterized in that, The additional transmission resources are scheduled for retransmission.

43. The method according to claim 34, characterized in that, The method also includes receiving from the base station a cancellation message relating to the selected transmission resource.

44. The method according to claim 27, characterized in that, The indication of the sidelink resources reserved by the base station is received only in relation to the mobile station being allowed to use the autonomously selected resource pool when it is within coverage area.

45. The method according to claim 27, characterized in that, Receive the instructions periodically.

46. ​​The method according to claim 27, characterized in that, The instruction is received in a set of common downlink control information.

47. The method according to claim 27, characterized in that, The instruction includes the reservation of transmission resources within a predetermined time period.

48. The method according to claim 27, characterized in that, The instructions include indications of changes in resource reservations since previous instructions.

49. A mobile station, characterized in that, The mobile station is configured to perform the method as described in any one of claims 27 to 48.

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