CN116325903A - Periodic reservation of side-link communications in cellular networks - Google Patents

Abstract

A method of reselecting a periodic resource reservation upon detection of a collision. The reselection procedure may reselect all resources forming the periodic resource reservation or only a subset. The re-selected resources may be eliminated. The UE may reuse the reselected resources for another transmission than originally intended.

Description

Periodic reservation of side-link communications in cellular networks

Technical Field

The following disclosure relates to periodic resource reservation (periodic resource reservations) in cellular networks, and in particular to such reservation for side link (sidelink) communications.

Background

Wireless communication systems, such as third generation (3G) mobile telephone standards and technologies are well known. Such 3G standards and techniques have been developed by the third generation partnership project (Third Generation Partnership Project,3 GPP) (RTM). Third generation wireless communications have been commonly developed to support macro-cellular (macro-cell) mobile phone communications. Communication systems and networks have evolved towards broadband and mobile systems.

In a cellular wireless communication system, a User Equipment (UE) is connected to a radio access network (Radio Access Network, RAN) by a wireless link. The RAN includes a set of base stations that provide radio links to UEs located in cells covered by the base stations, and an interface that provides overall Network control to a Core Network (CN). It should be appreciated that the RAN and CN each perform a respective function related to the overall network. For convenience, the term "cellular network" will be used to refer to the RAN and CN in combination, and it should be understood that the term is used to refer to the corresponding system for performing the disclosed functions.

The third generation partnership project has developed a so-called long term evolution (Long Term Evolution, LTE) (RTM) system, i.e. an evolved universal mobile telecommunications system terrestrially received radio access network (Evolved Universal Mobile Telecommunication System Territorial Radio Access Network, E-UTRAN) for mobile access networks in which one or more macro cells are supported by base stations called enodebs or enbs (evolved nodebs). Recently, LTE is further evolving towards so-called 5G or NR (new radio) systems, where one or more cells are supported by a base station called a gNB. NR is proposed to use an orthogonal frequency division multiplexing (Orthogonal Frequency Division Multiplexed, OFDM) physical transport format.

The NR protocol is intended to provide an option to operate in an unlicensed radio band (unlicensed radio bands), referred to as NR-U. While operating in the unlicensed radio band, the gNB and UE must compete for physical media/resource access with other devices. For example, wi-Fi (RTM), NR-U, and LAA may use the same physical resources.

The trend in wireless communication is to provide lower latency (lower latency) and higher reliability (higher reliability) services. For example, NR is intended to support ultra-reliability and low latencyCommunication (Ultra-reliable and low-latency communications, URLLC), while large-scale Machine-type communication (mctc) aims to provide low latency and high reliability for small packet sizes (typically 32 bytes). A user-plane latency of 1ms with a reliability of 99.99999% was proposed, 10 at the physical layer ^-5 Or 10 ^-6 Packet loss rate (packet loss rate).

The mctc service aims to support a large number of devices over a long lifecycle through an energy efficient communication channel, with occasional and infrequent data transmissions with each device. For example, one cell may be expected to support thousands of devices.

The following disclosure relates to various improvements to cellular wireless communication systems.

Disclosure of Invention

This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the detailed description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.

A method of changing periodic resource reservations for side-uplink communications is provided. A UE with a periodic resource reservation listens for reservations that may collide with transmission resources of the periodic resource reservation and determines a level of collision between the periodic resource reservation and the conflicting transmission. The UE compares the level of conflict to a threshold to determine whether to trigger a preemption procedure. Such a procedure may result in reselection of the periodic resource reservation, or reselection of only one or more periods of the periodic resource reservation.

The UE may then reselect new resources based on the determination. The new resources may be new periodic resource reservations or aperiodic resource reservations that replace only some of the original resources and/or periods.

There is also provided a resource reselection method associated with periodic resource reservation, the method being performed at a UE, comprising the steps of: reserving periodic resources for side-uplink communications; identifying a conflict with the resource during at least one cycle of the periodic resource; and reselecting the resource in at least one cycle of the periodic resource, wherein the reselection process depends on the identified level of conflict.

Only the resource or period where the conflict occurred may be reselected.

All resources or periods of the periodic resources may be re-selected.

The level of conflict may depend on the number or portion of cycles in which the conflict is detected.

The level of conflict may depend on the portion of the resource that is in conflict per cycle.

The reselection procedure may reserve new periodic resources.

The reselection procedure may reserve new aperiodic resources.

The UE may use the source of the reselection resources without collision for other transmissions than the original reservation.

The level of conflict may be determined by comparing the identified conflict to a predetermined threshold.

The predetermined threshold may be indicated to the UE in higher layer signaling.

The predetermined threshold may be defined on the basis of a resource pool or a UE.

The level of conflict may be determined by comparing the identified conflict with two predetermined thresholds, wherein reselection of non-periodic resources is performed below a first threshold and reselection of periodic resources is performed above a second threshold, the UE selecting the type of reselection between the first and second thresholds.

After the reselection procedure, the reserved periodic resources may be canceled.

The SCI message can be used to cancel the reserved periodic resources.

The SCI message may comprise a first stage SCI message.

The SCI message may comprise a second stage SCI message.

The SCI message may include an explicit cancellation indication.

The SCI message may include the identity of the resource to be cancelled.

The identity may include the frequency and time of the resource.

A UE configured to perform the methods described herein is also provided.

Drawings

Further details, aspects and embodiments of the invention will be described, by way of example only, with reference to the accompanying drawings. The components in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. Like reference numerals have been included in the respective drawings for ease of understanding.

Fig. 1 and 2 show schematic diagrams of selected elements of a cellular communication network;

FIG. 3 shows a method of resource reselection; and

fig. 4 shows an example of resource reselection.

Detailed Description

Those skilled in the art will recognize and appreciate that the specifics of the examples described are merely illustrative of some embodiments and that the teachings set forth herein are applicable in a variety of alternative settings.

Fig. 1 shows a schematic diagram of three base stations (e.g., enbs or gnbs depending on the particular cellular standard and terminology) forming a cellular network. Typically, each base station will be deployed by one cellular network operator to provide geographic coverage for UEs in that area. The base stations form a radio area network (Radio Area Network, RAN). Each base station provides wireless coverage for UEs in its area or cell. The base stations are interconnected by an X2 interface and connected to the core network by an S1 interface. It should be understood that only basic details are shown for the purpose of illustrating key features of a cellular network. The PC5 interface is provided between UEs for side-link communication. The interface and component names associated with fig. 1 are for example only, and different systems operating on the same principles may use different nomenclature.

Each base station includes hardware and software to implement the functions of the RAN, including communication with the core network and other base stations, control and data signaling between the core network and UEs, and UEs associated with each base station remain in wireless communication. The core network includes hardware and software that implements network functions such as overall network management and control, and routing of calls and data.

In addition to uplink (uplink)/downlink (downlink) communications between UEs and a base station, side-link communications in which UEs communicate directly with each other may also be implemented. Fig. 2 shows a base station 102 forming a RAN, as well as a side-uplink transmitter (SL Tx UE) UE 150 and a side-uplink receiver (SL Rx UE) UE 152 in the RAN. UEs 150 and 152 are depicted as transmitters and receivers for explanation only during a particular communication and their roles may likewise be reversed. Base station 102 is arranged to communicate wirelessly with each of SL Tx UE 150 and SL Rx UE 152 via respective connections 154. SL Tx UE 150 and SL Rx UE 152 are arranged to communicate wirelessly with each other via side links 156.

The side-uplink transmission utilizes a conventional Uu transmission between the TDD (half duplex) and the base station and UE on a dedicated carrier (dedicated carrier) or shared carrier (shared carrier). The resource pool of transmission resources is 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 can be selected for transmission. UEs may configure multiple transmit and receive resource pools.

Two modes of operation are used for resource allocation for side-link communications, depending on whether UEs are within the coverage of the cellular network. In Mode 1 (Mode 1), V2X communications are operating within the coverage of a base station (e.g., eNBs or gNBs). All scheduling and resource assignments may be made by the base station.

Mode 2 (Mode 2) is applied when the side-link service is operating outside the coverage of the cellular base station. Where UEs need to schedule themselves. For fair utilization, perceptually based resource allocation of transmission resources is typically used by UEs. It is expected that resource selection will include two steps. In a first step, the UE will identify resources that are considered to be alternative, and in a second step, will select a particular resource for transmission. The first step may be performed by starting with a set of all resources within a selection window (selection window) and removing those resources that are not considered candidates, e.g. reserved by another UE with a SL-RSRP above a threshold. The step of selecting the resources may be a random selection, possibly with constraints such as HARQ timing and delay between resources.

In mode 2, UEs select the transmission resources they wish to use for transmission and transmit side-uplink control information (Sidelink Control Information, SCI) messages indicating these resources. The SCI informs the recipient (possibly a single UE in unicast, a group of UEs in multicast, or all reachable UEs in broadcast) of the details of the transmission it can expect.

In NR, the resource pool may be configured to allow reservation of periodic resources for side-uplink communications. When reserving periodic resources, the SCI message includes an indication of the reservation period, which may be based on a configuration from higher layers (highers), which may be received in RRC signaling (RRC signaling).

One particular problem that may occur with periodic reservations is that repeated collisions (repeated collisions) may occur if two UEs select overlapping resources having the same period. Similarly, reservations with common multiple periods will also collide periodically (e.g., 10ms and 15ms will collide every 30ms (half or one third of what happens). Each collision will result in transmission errors or preemption (pre-transmission), resulting in the UE re-selecting (re-select) resources, which requires additional signaling and processing.

The following disclosure provides techniques directed to improving periodic resource selection for side-link communications. In particular, in case the UE has reserved periodic resources and the UE receives an indication that another UE has reserved overlapping resources, this means preemption, the UE at least reselects the reserved overlapping resources.

In the present disclosure, the term "periodic resource reservation" is used to refer to a reservation (a reservation of apattern of resources) of a resource pattern repeated in the time and frequency domains with a given period (typically indicated in the first stage SCI). The term "period" is used to refer to a single occurrence of a resource pattern within a periodic resource. A single period corresponds to the reserved initial transmission and associated retransmission (associated retransmissions reserved).

Collisions may occur on a subset of the periods of the periodic resource reservation or on all periods. For example, dynamic grants (dynamic grants) may only conflict/preempt one cycle, while subsequent cycles of the periodic reservation are still available. In the event that only a few cycles collide, it may be inefficient to reselect resources for all cycles, as this may result in unused resources for a different cycle than the collision. Similarly, when there are a large number of collisions, it is inefficient to reselect individual cycles.

In a first reselection method, a UE with periodic resource reservation detects a conflict with resources in at least a subset of reservation periods. The UE triggers a preemption procedure (pre-emption procedure) in which the UE performs a reselection procedure only for periods with collisions and reserves a reservation of non-collision periods. Non-conflicting resources may also be reselected if it is determined that this is preferred. For example, if a resource reselected for a conflicting resource collides with other resources (e.g., the time interval between two retransmissions does not meet the HARQ/PSFCH constraint), more resources may need to be reselected. Some previously selected resources may also be reselected if they are no longer available during step 1 but do not meet the criteria for triggering preemption (criterion). Furthermore, the selection process in step 2 of the process may be configured to allow only all resources to be reselected within a given period. Reselection of resources only during certain periods (e.g., one period) may be described as aperiodic reselection (aperiodic reselection).

In a second reselection method, a UE that detects a collision and has a periodic resource reservation may choose to reselect a new periodic resource reservation to replace all of the previous periods. This approach may be used even if only a portion of the resources collide. Once a new periodic resource reservation is made, the previous reservation will be discarded and not used by the UE for the periodic transmission.

In the case where resources are not to be used by the UE for the original transmission, the UE may choose to use these resources for another transmission, leave them unused, or use a cancellation procedure (cancellation procedure) as described below.

The UE may select one of these methods based on a predefined configuration, which may specify that the preempted periodic reservation is reselected as a new periodic resource, or one or more non-periodic resources (along with the non-conflicting resources of the original reservation (original reservation)). The configuration may be defined by higher layer (RRC) signaling or other configuration methods. The configuration may be defined by a resource pool, a UE, a cell, or according to UE capabilities. The improved configuration granularity (Improved granularity in the configuration) may be provided by indicating in the configuration whether the UE is allowed to reselect periodic resources or it has to perform aperiodic reselection. The UE may then decide how to behave in different situations.

The choice of which method to use may be based on an estimate of how many resources or cycles are subject to collision, as shown in fig. 3. In step 300, the ue detects a collision with a periodic resource reservation it does and starts the preemption/reselection procedure. In step 301, the ue evaluates the number of periods and/or resources within the periodic resource reservation where collisions are expected to occur. If the number of collisions is high (e.g., the UE may detect that the collision/preemption reservation is a periodic resource reservation with the same periodicity as the UE original reservation), the UE performs periodic resource reservation to reselect the entire original reservation (step 302). Conversely, if the UE determines that the number of collisions is small, aperiodic reselection is performed to replace only the collided resources in step 303.

The determination of high or low may be made based on a preset threshold that is determined by the UE or signaled to the UE, e.g., in higher layer (RRC) signaling. More than one threshold may be configured so that in the central region, the UE may decide on its own which technology to select. In one example, a small number of conflicts may be 2 cycles requiring reselection, and/or a large number of conflicts may be 5 cycles requiring reselection. The threshold may also be defined as a fraction of the number of cycles in the periodic resource selection. For example, if less than (in a particular example) 10% or 50% of the period suffers from collisions and needs to be reselected, aperiodic reselection may be used.

The evaluation of the collision requires calculating a collision that will occur between the resources of the periodic resource reservation and the resources of another periodic resource reservation. Collisions may also occur between periodic resource reservations and other non-periodic resource reservations. For example, the accumulation of aperiodic reservations (accumulation of aperiodic reservations) may conflict with multiple periods of periodic resource reservations. The methods discussed herein may treat collisions with any other type of reservation equally. Thus, in evaluating conflicts, it may be necessary to evaluate the accumulation of all other reservations, not just periodic reservations. Depending on the resources reserved per reservation and the period of each reservation.

The criteria used may be a function of the number of conflicting resources to calculate a single conflict (which may help to evaluate the loss of unused resources if a new periodic reservation is made) and/or the number of periods of periodic resource reservation including at least one conflict (given an indication of control signaling overhead (control signalling overhead), the number of reselection and SCI reservations required is calculated). As described above, the criteria may also be based on a fraction or ratio instead of an absolute count (absolute count).

The criteria may be evaluated over a defined period of time (time period), which may be a configured number of periods, a future time (in milliseconds or logical time slots), e.g., t_scal/c_remainder, and/or a number of periods (or a minimum or maximum of these) remaining in the periodic resource reservation. The period may be defined by a standard and/or according to a configuration of the UE. The threshold may depend on the method and time period used to calculate the conflict, so the configuration should be defined as a set to ensure predictable behavior.

In one example, the time period for evaluation may be the minimum of the configuration time (t_scal) and the remaining time of the periodic resource reservation. The first periodic resource reservation of the first UE may have a period of 20 ms with 3 transmissions in each period. There are 3 cycles (20 milliseconds) left in the reservation. The second UE makes a preemptive reservation consisting of 10ms periods, with a collision occurring in each period. This may be calculated as 1 out of one third (1/3) transmissions of each cycle of the first reservation having a collision, three (100%) of the remaining first reservation cycles having at least one collision, or three (50%) of the second (preemption) cycles having at least one collision. In this example, the threshold may be set to 25% of the remaining period that has at least one collision, in which case periodic reselection will occur. More complex evaluations may be performed using more than one criterion, each criterion possibly having a different threshold.

Different criteria and thresholds may be applied according to each reserved priority (priorities), which may be configured through higher layer signaling (RRC).

As mentioned above, UEs are currently not likely to cancel the earlier periodic resource reservation, and therefore, if the resources are reselected, they may become unused. Thus, the method discussed above may be extended to allow the UE to cancel and reselect periodic resource reservations (or as a separate process).

In a first method, a UE provides a dedicated signal (dedicated signal) for transmission to cancel a periodic resource reservation. In one example, the field (field) is provided in a SCI message format for indicating cancellation. The UE may include the cancellation in the SCI message selecting the new resource or in a separate message (standalone message).

The indication may be provided in a first stage SCI message. To avoid changing the size of the existing message format (which would increase decoding complexity), a reserved bit (reserved bit) of SCI may be used to indicate that the SCI message is a cancel message (cancellation message). The message should indicate the periodic reserved resources to cancel and the source identity (source identity) that helps ensure that the receiving UEs cancel the correct reservation. For example, the frequency and time fields of the SCI may be used to indicate those respective parameters of the reservation to cancel. The source identity may be defined as the identity (typically 16 bits) transmitted in the original second stage SCI. These may include the location of bits that are not needed in cancelling the SCI. For example, MCS, DMRS pattern and number of ports, reservation period and beta_offset indicator fields may be used. A complete original source tag identity, or a shorter version (e.g., 8 LSBs) may be included. The cancellation SCI may be transmitted as a separate transmission (standalone transmission) without an associated second stage SCI. The use of the first stage SCI should decode faster, more reliably, and allow receiving UEs to obtain the cancellation indication faster than the use of the second stage SCI.

In the current side-uplink transmission design, the first stage SCI, the second stage SCI and the side-uplink data are always mapped in rectangular form in the time-frequency resources. The specific resources of the side-uplink resource pool can be dedicated to where the separate first stage SCI can be transmitted. The dedicated resource may be used for transmission cancellation SCI (cancellation SCI) and may accommodate new control transmissions without associated data.

To limit the addition of blind decoding (blind decoding) due to the addition of the first stage SCI format, cancellation of SCI (and other special signaling first stage SCI formats if needed) can be limited exclusively to certain time slots and subchannels pre-configured and/or mapped as a function of reserved resources.

In an alternative configuration, a cancel indication (cancellation indication) may be provided in the second stage SCI message, e.g., no data or dummy data in the payload. In this configuration, the first stage SCI points to the second stage SCI in a conventional manner, and also indicates that the second stage CSI is a cancel SCI. The only purpose of the second stage SCI transmission is to cancel the reservation and no data is being transmitted, which can be limited to single subchannel transmissions.

As described above, the cancel message should indicate the time/frequency resource that was canceled (or point to the resource that was executing the reservation). It may be beneficial to also indicate the identity of the reservation source, the identity of the destination of the reserved resource and/or the HARQ ID which may further reduce ambiguity.

When the cancellation indication is carried in the second stage SCI, a high reliability transport format may be selected, in particular because a lot of bits (bits) may not be needed and the whole radio resources may be utilized. Multiple cancels can be sent using the same resources with multiplexed second stage SCI messages, or a new format can be defined, including multiple cancelation indications.

In a further example, cancelling the second stage SCI may be sent (multiplexed) with the regular transmission. Thus, the transfer will include a first stage SCI, a second stage SCI for data, and a second stage cancellation SCI for cancellation and payload data. The multiplexing order (cancelling SCI before second stage SCI of data) may implicitly indicate that at least one second stage SCI is also expected after cancelling SCI. Alternatively, the first stage SCI may indicate the number of second stage SCIs that are expected.

In another example, the second stage SCI format may be defined to include cancel information and normal data information.

In all examples, the first stage SCI uses a second stage format indicator field (second-stage format indicator field) to indicate the format of the second stage SCI that can be expected in the PSSCH.

In another approach, a portion of the previous periodic resource reservation may be utilized to directly indicate new resources by changing the SCI transmitted in the relevant period. For example, if only one of the three resources within a cycle is in conflict, the SCI of the cycle transmission indicates only non-conflicting resources. Other UEs are aware of the previous periodic reservation and can therefore explicitly infer that the new SCI represents updated information for the previous reservation for that period. When using this technique, preemption can be applied on subsequent transmission resources, so the process must be notified early enough (e.g., processing time T3) before the resources will collide. Therefore, UEs must be configured to transmit collision reservations early enough.

An indication may be provided in the configuration indicating whether the changed reservation is for a specific period only or for all future periods of the periodic resource reservation. Alternatively, the indication may be provided in the SCI reserving the changed resources.

Fig. 4 (a) shows one example where all cycles of reserved resources are changed (periodic reselection), while fig. 4 (b) shows one example where only one cycle is changed (non-periodic reselection).

In another approach, the SCI (not necessarily part of the previous reservation) may include an indication that the reservation replaces the previous periodic reservation. To determine which reservations have been canceled by the new SCI, the receiving UEs need to decode the second stage SCI to identify SRC, DST and HARQ ID so that the new reservation can be associated with the replaced previous reservation. While this may increase the complexity of the process (and require the storage of the sensed SCI information), this approach may enable reselection to be performed at any time and send a new reservation on previously unreserved resources. This approach also relaxes the limitation on the resource selection time (since there is no need to leave time to process before a conflict occurs).

Various methods for managing the change and cancellation of periodic resource reservations for side-uplink communications have been described.

Although not shown in detail, any apparatus or device forming part of a network may comprise at least a processor, a storage unit, and a communication interface, wherein the processor unit, the storage unit, and the communication interface are configured to perform the methods of any aspect of the invention. Further options and selections are described below.

The signal processing functions of embodiments of the present invention, particularly the gNB and UE, may be implemented using computing systems or architectures known to those skilled in the relevant art. It may be desirable or appropriate to use a computing system, such as 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 for a given application process or environment. A computing system may include one or more processors, which may be implemented using a general-purpose or special-purpose processing engine, such as a microprocessor, microcontroller, or other control module.

The computing system may also include a main memory, such as random access memory (Random Access Memory, RAM) or other dynamic memory, for storing information and instructions for execution by the processor. Such main memory may also be used for storing temporary variables or other intermediate information during execution of instructions to be executed by the processor. The computing system may also include Read Only Memory (ROM) or other static storage device for storing static information and instructions for the processor.

The computing system may also include an information storage system, which may include, for example, a media drive and a removable storage interface. The media drive may include a drive or other mechanism to support fixed or removable storage media, such as a hard disk drive, floppy disk drive, magnetic tape drive, optical disk drive, compact Disc (CD) or digital video drive (Digital Video Drive, DVD) (RTM), read or write drive (Read or Write Drive, R or RW), or other removable or fixed media drive. Storage media may include, for example, 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 a media drive. The storage medium may include a computer-readable storage medium having stored therein specific computer software or data.

In alternative embodiments, the information storage system may include other similar components for allowing computer processes or other instructions or data to be loaded into the computing system. Such components may include, for example, removable storage units and interfaces such as process cartridge and cartridge interfaces, removable memory (e.g., flash memory or other removable memory modules) and memory slots, and other removable storage units and interfaces that allow software and data to be transferred from the removable storage units to the computing system.

The computing system may also include a communication interface. Such a communication interface may be used to allow software and data to be transferred between the computing system and external devices. Examples of communication interfaces may include modems, network interfaces (e.g., ethernet or other NIC cards), communication ports (e.g., universal Serial Bus (USB) ports), PCMCIA slots and cards, etc. Software and data transferred via the communications interface are in the form of signals which may be electronic, electromagnetic and optical or other signals capable of being received by the communications interface medium.

In this document, the terms "computer process product," "computer-readable medium," and the like may be used to generally refer to tangible media, such as memory, storage devices, or storage units. These and other forms of computer-readable media may store one or more instructions for use by a processor, including a computer system, to cause the processor to perform specified operations. Such instructions, commonly referred to as "computer process code" (which may be grouped in the form of computer processes or other groupings), when executed, enable a computing system to perform functions of embodiments of the present invention. Note that the code may directly cause the processor to perform the specified operation, be compiled to do so, and/or be combined with other software, hardware, and/or firmware elements (e.g., libraries for performing standard functions) to do so.

The non-transitory computer readable medium may include at least one from the group consisting of: hard disks, CD-ROMs, optical storage devices, magnetic storage devices, read-only memory, programmable read-only memory, erasable programmable read-only memory, EPROM, electrically erasable programmable read-only memory, and flash memory. In embodiments where the components are implemented using software, the software may be stored in a computer readable medium and loaded into a computing system using, for example, a removable storage drive. The control module (in this example, software instructions or executable computer process code) when executed by a processor in a computer system causes the processor to perform the functions of the invention as described herein.

Furthermore, the concepts of the present invention may be applied to any circuit for performing signal processing functions within a network component. It is further contemplated that the inventive concept may be employed by, for example, a semiconductor manufacturer in the design of a stand-alone device, such as a microcontroller of a digital signal processor (Digital Signal Processor, DSP), or an Application-specific integrated circuit (ASIC), and/or any other subsystem element.

It should be appreciated that for clarity, the above description has described embodiments of the invention with reference to a single processing logic. However, the inventive concept may equally be implemented by a number of different functional units and processors to provide signal processing functionality. Thus, 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.

Aspects of the invention may be implemented in any suitable form including hardware, software, firmware or any combination of these. The invention may 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 of e.g. FPGA devices.

Thus, the components and assemblies of embodiments of the invention can be physically, functionally and logically implemented in any suitable way. Indeed the functionality may be implemented in a single unit, in a plurality of units or as part of other functional units. Although the present invention has been described in connection with some embodiments, it is not intended to be limited to the specific form set forth herein. Rather, the scope of the invention is limited only by the appended claims. Furthermore, although a feature may appear to be described in connection with particular embodiments, one skilled in the art would recognize that various features of the described embodiments may be combined in accordance with the invention. In the claims, the term "comprising" does not exclude the presence of other elements or steps.

Furthermore, although individually listed, a plurality of means, components or method steps may be implemented by e.g. a single unit or processor. Furthermore, although individual features may be included in different claims, these may possibly be advantageously combined, and the inclusion in different claims does not imply that a combination of features is not feasible and/or advantageous. Furthermore, the inclusion of a feature in one category of claims does not imply a limitation to this category but rather indicates that the feature is equally applicable to other claim categories as appropriate.

Furthermore, the order of features in the claims does not imply any specific order in which the features must be performed, and in particular the order of individual steps in a method claim does not imply that the steps must be performed in this order. Rather, the steps may be performed in any suitable order. Furthermore, singular references do not exclude a plurality. Thus, references to "a," "an," "the first," "the second," etc. do not exclude a plurality.

Although the present invention has been described in connection with some embodiments, it is not intended to be limited to the specific form set forth herein. Rather, the scope of the invention is limited only by the appended claims. Furthermore, although a feature may appear to be described in connection with particular embodiments, one skilled in the art would recognize that various features of the described embodiments may be combined in accordance with the invention. In the claims, the term "comprising" or "comprises" does not exclude the presence of other elements.

Claims (20)

1. A method of resource reselection in connection with periodic resource reservation, the method being performed at a UE, comprising the steps of:

reserving periodic resources for side-uplink communications;

identifying a conflict with the resource during at least one cycle of the periodic resource; and

the resources are reselected in at least one cycle of the periodic resources, wherein the reselection process depends on the level of the identified conflict.

2. The method of claim 1, wherein only the resource or period at which the conflict occurred is reselected.

3. The method of claim 1, wherein all resources or periods of periodic resources are reselected.

4. A method according to any one of the preceding claims, wherein the level of conflict depends on the number or portion of cycles in which a conflict is detected.

5. A method according to any one of the preceding claims, wherein the level of conflict depends on the portion of the resource where the conflict occurs per cycle.

6. A method according to any of the preceding claims, wherein the reselection procedure reserves new periodic resources.

7. The method according to any of claims 1 to 5, wherein the reselection procedure reserves new aperiodic resources.

8. The method according to any of the preceding claims, wherein the UE uses the re-selected resources without collision for other transmissions than the original reservation.

9. A method according to any one of the preceding claims, wherein the level of conflict is determined by comparing the identified conflict with a predetermined threshold.

10. The method of claim 9, wherein the predetermined threshold is indicated to the UE in higher layer signaling.

11. The method according to claim 9 or 10, wherein the predetermined threshold is defined on the basis of a resource pool or UE.

12. The method of claim 1, wherein the level of conflict is determined by comparing the identified conflict with two predetermined thresholds, wherein reselection of non-periodic resources is performed below a first threshold, reselection of periodic resources is performed above a second threshold, and the UE selects the type of reselection between the first and second thresholds.

13. A method according to any of the preceding claims, wherein the reserved periodic resources are cancelled after the reselection procedure.

14. The method of claim 13 wherein the reserved periodic resources are canceled using SCI messages.

15. The method of claim 14 wherein the SCI message comprises a first stage SCI message.

16. The method of any of claims 13-15 wherein the SCI message comprises a second stage SCI message.

17. The method of any of claims 13-16 wherein the SCI message includes an explicit cancellation indication.

18. The method according to any of claims 13 to 17, wherein the SCI message comprises the identity of the resource to be cancelled.

19. The method of claim 18, wherein the identity comprises a frequency of the resource and a time.

20. A UE configured to perform the method of any of the preceding claims.

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