WO2020173536A1

WO2020173536A1 - Devices and methods for reducing the impact of half-duplex and in-band emissions in autonomous resource selection for 5g nr v2x sidelink communication

Info

Publication number: WO2020173536A1
Application number: PCT/EP2019/054504
Authority: WO
Inventors: Daniel Medina; Serkan AYAZ; Sandip GANGAKHEDKAR; Philippe Sartori
Original assignee: Huawei Technologies Co., Ltd.
Priority date: 2019-02-25
Filing date: 2019-02-25
Publication date: 2020-09-03

Abstract

The invention relates to a sidelink communication device comprising a processor configured to select one or more radio resources for transmission of sidelink data, wherein the processor is configured to exclude all candidate radio resources that overlap in the time domain with a radio resource indicated and/or reserved by received sidelink control information (SCI). In addition, the invention relates to a sidelink communication device comprising a processor configured to exclude a candidate radio resource on the basis of a distance or relative location in the frequency domain between the candidate radio resource and a radio resource indicated and/or reserved by received sidelink control information (SCI) or indicated by sidelink feedback control information (SFCI), in particular if the candidate radio resource is an adjacent and/or image radio resource, in the frequency domain, with respect to the radio resource indicated and/or reserved. Moreover, the invention relates to a sidelink communication device comprising a processor configured to select a radio resource within a resource selection window comprising a plurality of cycles, in particular radio frames, wherein the processor is configured to select the radio resource on the basis of a time offset, in particular a subframe number, of the radio resource with respect to the beginning and/or the end of the cycle in which the radio resource occurs. Furthermore, the invention relates to a sidelink communication device comprising a processor configured to select a radio resource from a plurality of candidate radio resources, wherein at least one candidate radio resource comprises a plurality of time resources, in particular contiguous time slots, and wherein the processor is configured to determine an expected received signal quality of the at least one candidate radio resource on the basis of an energy to be transmitted in the plurality of time resources and select the radio resource on the basis of the expected received signal quality.

Description

Devices and Methods for Reducing the Impact of Half-Duplex and In-Band Emissions in Autonomous Resource Selection for 5G NR V2X Sidelink Communication

TECHNICAL FIELD

In general, the present invention relates to the field of wireless communications. More specifically, the present invention relates to devices and methods for sidelink communication in a 5G NR V2X communication network, in particular sidelink communication devices for allocating sidelink radio resources as well as corresponding methods.

BACKGROUND

The 3rd Generation Partnership Project (3GPP) is in the process of standardizing 5G New Radio (NR) sidelink communication specifications to support enhanced Cellular Vehicle-to- Everything (C-V2X) services, including platooning, sensor sharing and cooperative maneuvers. These new use cases (also referred to as eV2X) come with significantly more stringent requirements (specified in 3GPP TS 22.186,“Enhancement of 3GPP support for V2X scenarios”) in terms of latency (10 ms) and reliability (99.999%), well beyond what can be achieved by Long Term Evolution (LTE) specifications for C-V2X, commonly known as LTE-V.

One of the new types of standardized messages in 5G NR C-V2X is the so-called Collective Perception Message (CPM) specified in ETSI TS 103 324,“Intelligent Transport System (ITS); Vehicular Communications; Basic Set of Applications; Specification of the Collective Perception Service”. CPM complements and is similar in behavior to the Cooperative Awareness Message (CAM). It contains externally observable information about detected road users or objects (actual time, position and motion state) and, in case of vehicles, may include other attributes such as dimensions, vehicle type, role in road traffic, etc. CPMs are generated periodically. The generation frequency is determined taking into account the dynamic behavior of the detected object (e.g., change of position, speed or direction), sending of CPMs for the same (perceived) object by another vehicle, as well as radio channel load. CPMs are broadcast by the originating vehicle to all vehicles within direct communication range in a single hop (i.e., they are not forwarded).

A key distinctive feature of C-V2X, not found in other vehicular communication standards such as Dedicated Short Range Communications (DSRC), is the use of Orthogonal Frequency Division Multiple Access (OFDMA), allowing frequency multiplexing of different users’ transmissions on different sets of subcarriers within a given carrier. At present, however, two Radio Frequency (RF) technological limitations constrain the ability to use OFDMA for user multiplexing on the so-called Physical Sidelink Shared Channel (PSSCH): a) Half-Duplex (HD) constraint: on a given carrier, a User Equipment (UE) cannot transmit and receive PSSCH in the same Transmission Time Interval (TTI) (e.g., subframe, slot, mini slot, OFDM symbol, etc.) due to self-interference; and b) near-far effect as a result of In-Band Emissions (IBE): on a given carrier, a UE may not be able to receive a very weak PSSCH transmission from a UE if there is a very strong PSSCH transmission from another UE in the same TTI.

In-band emissions arise as a result of transmitter imperfections, such as Power Amplifier (PA) nonlinearities, phase noise and IQ imbalance. The first two influence the subcarriers adjacent to the transmitted signal, while the third manifests itself in the mirror image of the allocated subcarriers around the carrier frequency. Figure 1 shows the power spectral density measured at UE B from two received signals (transmitted by UE A and UE C). UE B is unable to decode the signal from UE C due to IBE interference from UE As adjacent, much stronger signal.

In the Uplink (UL), IBE interference is managed by means of Physical Uplink Shared

Channel (PUSCH) power control and/or scheduling by the serving base station (receiving node). However, in V2X sidelink broadcast (e.g., CPM) there may be many intended receivers, thus receiver-based PSSCH power control and/or scheduling are not possible.

In UE autonomous resource selection (also referred to as‘mode 4’ in LTE-V), a UE having data to transmit (re)selects PSSCH resources autonomously based on sensing within a (pre)configured PSSCH resource pool. At the end of each reselection period, the UE keeps the previously selected radio resource according to a configurable probability. If the UE does not keep the previously selected radio resource, the UE: selects the number of

retransmissions (0 or 1 ); selects an amount of frequency resources (number of contiguous subchannels) within the range configured by upper layers; sets the resource reservation interval to one of the allowed values configured by upper layers; randomly selects a radio resource among the radio resources reported by the PHY (physical) layer and uses it to select a set of periodic radio resources spaced by the resource reservation interval.

In the time domain, the set of subframes assigned to a PSSCH resource pool is specified as part of the resource pool configuration by means of a bitmap b₀ ... b_Lbltmap-1 of length L_bitmap bits. Similarly, in the frequency domain, the set of Physical Resource Blocks (PRBs) assigned to the PSSCH resource pool is specified by a starting PRB number ( n_subCHRBstart ) and a number of subchannels ( N_subCH ), each consisting of a set of contiguous PRBs

( -subCHsize )

Figure 2 shows an example of candidate radio resources (according to 3GPP Rel-14/15 specifications) for initial transmission (left) and retransmission (right), each consisting of L_subc_H = 2 contiguous subchannels in a single subframe, within a PSSCH resource pool (Parameters: b₀ ... b₉ = 10000 00000, n_subCHRBstart = 10 PRBs, N_subCH = 5 subchannels, ⁿ _subc_Hsize = 5 PRBs). Any set of L_subCH contiguous subchannels in a given subframe within the PSSCH resource pool within a certain resource selection window (so as to fulfill the latency requirement, e.g., 100 ms) corresponds to a candidate radio resource.

The specification 3GPP TS 36.213,“Physical layer procedures” standardizes a“UE procedure for determining the subset of resources to be reported to higher layers in PSSCH resource selection in sideiink transmission mode 4”, which is based on sensing. Specifically, the UE performs two measurements defined in 3GPP TS 36.214,“Physical layer

measurements”: PSSCH Reference Signal Received Power (PSSCH-RSRP) and Sideiink Received Signal Strength Indicator (S-RSSI).

When requested by higher layers, the UE determines the set of radio resources to be reported to higher layers for PSSCH transmission according to the following steps.

First, the UE excludes among all candidate radio resources: a) radio resources it has no measurement information for (e.g., corresponding to subframes in which its own

transmissions occur - as it cannot monitor those subframes due to self-interference); and b) radio resources indicated or reserved by decoded Sideiink Control Information (SCI) from nearby UEs with an associated PSSCH-RSRP above a certain (priority-dependent) threshold.

From the remaining candidate radio resources, the PHY layer reports to the MAC (Medium Access Control) layer only 20% of the total number of candidate radio resources, namely those with the lowest observed S-RSSI values. The MAC layer then selects a radio resource randomly among the reported radio resources.

This resource selection procedure in and of itself does not address the impact of the Half- Duplex (HD) constraint nor does it attempt to reduce the impact of In-Band Emissions (I BE). Instead, these problems are dealt with indirectly by introducing two additional features: retransmissions and geographical zones, respectively. In order to reduce the impact of HD, LTE-V uses blind retransmissions. The radio resource for retransmission of a Transport Block (TB) is selected independently from the radio resource selected for initial transmission of the TB, as shown in Figure 2. In this way, if a certain UE B did not receive the initial transmission from UE A because it was busy transmitting its own data, there is a second chance to receive the TB in the retransmission radio resource. It is unlikely that both UEs will select the same TTI for both their initial transmission and retransmission. The obvious disadvantage of blind retransmissions is the loss of spectral efficiency due to (possibly) unnecessary redundancy.

In order to reduce the impact of IBE, LTE-V uses geographical zones. If UE A and UE B are sufficiently far away, they will determine themselves to be in different zones and

consequently use orthogonal resource pools, thus minimizing the impact of the near-far effect. However, in order to significantly reduce the impact of IBE, zones need to be rather small (a few tens of meters), causing very frequent resource pool reselection at high speed. This leads to a reduction in the reliability of sensing-based resource selection, which relies on stable measurements. In addition, resource pool under-utilization in low-density zones leads to loss of spectral efficiency and system capacity.

In light of the above, there is a need for improved devices and methods for sidelink communication, allowing efficient and cost-effective radio resource allocation and data transmission for sidelink communication.

SUMMARY

It is an object of the invention to provide improved devices and methods for sidelink communication, allowing efficient and cost-effective radio resource allocation and data transmission for sidelink communication.

The foregoing and other objects are achieved by the subject matter of the independent claims. Further implementation forms are apparent from the dependent claims, the description and the figures.

Generally, embodiments of the invention relate to a sidelink communication device (S) as well as corresponding methods for selecting sidelink radio resources and transmitting sidelink data efficiently and cost-effectively. More specifically, embodiments of the present invention can reduce the impact of In-Band Emissions (I BE) and Half-Duplex (HD) in UE autonomous resource selection based on Physical Sidelink Control Channel (PSCCH) decoding. In order to avoid self-interference and minimize the impact of Half-Duplex, a UE interested in receiving Physical Sidelink Shared Channel (PSSCH) transmissions from nearby UEs (e.g., Collective Perception Messages, CPMs) on a given carrier refrains from transmitting its own PSSCH in the Transmission Time Intervals (TTIs) used by the nearby UEs. The UE may become aware of the TTIs used in its proximity by decoding PSCCH carrying Sidelink Control Information (SCI). A candidate TTI (e.g., subframe, slot, mini-slot, OFDM symbol, etc.) is entirely excluded from resource selection if it contains a radio resource indicated or reserved by a decoded SCI, in particular with an associated PSSCH Reference Signal Received Power (PSSCH-RSRP) above a threshold.

In addition, in order to minimize the impact of In-Band Emission (IBE) interference, a candidate radio resource is excluded from resource selection if it is an adjacent or image radio resource, in the frequency domain, with respect to a radio resource indicated or reserved by a decoded SCI with an associated PSSCH-RSRP below a threshold.

Alternatively, a candidate radio resource may be excluded if it is an adjacent or image radio resource with respect to an interference sensitive radio resource explicitly indicated as such by received sidelink feedback control information (SFCI).

Compared to the currently standardized PSSCH resource selection procedure (3GPP Rel- 14/15), embodiments of the present invention can provide increased reliability for a given communication range as a result of the reduced impact of HD and IBE, without the spectral efficiency cost of blind retransmissions and/or geographical zones introduced in LTE-V.

More specifically, according to a first aspect, the invention relates to a sidelink

communication device (S) comprising a transceiver configured to receive sidelink control information (SCI), in particular on a Physical Sidelink Control Channel (PSCCH), from at least one neighboring sidelink communication device (B, C) indicating and/or reserving a radio resource for transmission of sidelink data on a pre-defined carrier by the at least one neighboring sidelink communication device (B, C), and a processor configured to select one or more radio resources from a plurality of candidate radio resources, in particular Physical Sidelink Shared Channel (PSSCH) resources, for transmission of sidelink data by the sidelink communication device (S), wherein the processor is further configured to exclude from the radio resource selection on the pre-defined carrier all candidate radio resources that overlap in the time domain with the radio resource indicated and/or reserved. Thus, an improved sidelink communication device (S) is provided, allowing for efficient radio resource selection for sidelink communication.

In a further possible implementation form of the first aspect, the processor is configured to exclude from the radio resource selection on the pre-defined carrier all candidate radio resources for which a future occurrence of the candidate radio resource, according to a pre determined resource reservation interval, overlaps in the time domain with the radio resource indicated and/or reserved.

In a further possible implementation form of the first aspect, the transceiver is configured to measure a received signal strength, in particular a PSSCH Reference Signal Received Power (PSSCH-RSRP), and the processor is configured to exclude the overlapping radio resources on the basis of the measured received signal strength, in particular if the measured received signal strength is above a threshold value.

In a further possible implementation form of the first aspect, the processor is configured to determine a plurality of time resources, in particular time slots, for transmission of sidelink data by the sidelink communication device (S), rank each of the plurality of time resources on the basis of a measured received signal strength, and exclude from the radio resource selection on the pre-defined carrier all candidate radio resources that overlap in the time domain with a time resource that ranks above a percentile.

In a further possible implementation form of the first aspect, the transceiver is configured to measure the received signal strength in a radio resource associated with sidelink control information (SCI) received from a neighboring sidelink communication device (B, C) indicating and/or reserving a radio resource that overlaps in the time domain with the time resource and/or a future occurrence thereof.

In a further possible implementation form of the first aspect, the processor is configured to rank the time resources on the basis of the strongest among a plurality of measured received signal strengths, in particular PSSCH Reference Signal Received Powers (PSSCH-RSRPs).

According to a second aspect, the invention relates to a method of operating a sidelink communication device (S) comprising a processor configured to select one or more radio resources from a plurality of candidate radio resources, in particular Physical Sidelink Shared Channel (PSSCH) resources, for transmission of sidelink data by the sidelink communication device (S), wherein the method comprises: receiving sidelink control information (SCI), in particular on a Physical Sidelink Control Channel (PSCCH), from at least one neighboring sidelink communication device (B, C) indicating and/or reserving a radio resource for transmission of sidelink data on a pre-defined carrier by the at least one neighboring sidelink communication device (B, C); measuring a received signal strength, in particular a PSSCH Reference Signal Received Power (PSSCH-RSRP); and excluding from the radio resource selection on the pre-defined carrier all candidate radio resources that overlap in the time domain with the radio resource indicated and/or reserved, in particular on the basis of the measured received signal strength.

Thus, an improved method for selecting radio resources for sidelink communication is provided.

According to a third aspect, the invention relates to a sidelink communication device (S) comprising a transceiver configured to receive sidelink control information (SCI), in particular on a Physical Sidelink Control Channel (PSCCH), from at least one neighboring sidelink communication device (A, D) indicating and/or reserving a radio resource for transmission of sidelink data on a pre-defined carrier by the at least one neighboring sidelink communication device (A, D), and a processor configured to select one or more radio resources from a plurality of candidate radio resources, in particular Physical Sidelink Shared Channel (PSSCH) resources, for transmission of sidelink data by the sidelink communication device (S), wherein the processor is further configured to exclude from the radio resource selection on the pre-defined carrier a candidate radio resource on the basis of a distance or relative location in the frequency domain between the candidate radio resource and the radio resource indicated and/or reserved.

Thus, an improved sidelink communication device (S) is provided, allowing for efficient radio resource selection for sidelink communication.

In a further possible implementation form of the third aspect, the processor is configured to exclude from the radio resource selection on the pre-defined carrier a candidate radio resource if the candidate radio resource or a future occurrence thereof, according to a pre determined resource reservation interval, is an adjacent or image radio resource, in the frequency domain, with respect to the radio resource indicated and/or reserved.

In a further possible implementation form of the third aspect, the transceiver is configured to measure a received signal strength, in particular a PSSCH Reference Signal Received Power (PSSCH-RSRP), and the processor is configured to exclude from the radio resource selection on the pre-defined carrier a candidate radio resource on the basis of the measured received signal strength, in particular if the measured received signal strength is below a threshold value.

According to a fourth aspect, the invention relates to a method of operating a sidelink communication device (S) comprising a processor configured to select one or more radio resources from a plurality of candidate radio resources, in particular Physical Sidelink Shared Channel (PSSCH) resources, for transmission of sidelink data by the sidelink communication device (S), wherein the method comprises: receiving sidelink control information (SCI), in particular on a Physical Sidelink Control Channel (PSCCH), from at least one neighboring sidelink communication device (A, D) indicating and/or reserving a radio resource for transmission of sidelink data on a pre-defined carrier by the at least one neighboring sidelink communication device (A, D); and excluding from the radio resource selection on the pre defined carrier a candidate radio resource on the basis of a distance or relative location in the frequency domain between the candidate radio resource and the radio resource indicated and/or reserved, in particular if the candidate radio resource or a future occurrence thereof, according to a pre-determined resource reservation interval, is an adjacent or image radio resource, in the frequency domain, with respect to the radio resource indicated and/or reserved.

According to a fifth aspect, the invention relates to a sidelink communication device (S) comprising a transceiver configured to receive sidelink feedback control information (SFCI), in particular on a Physical Sidelink Feedback Channel (PSFCH), from at least one neighboring sidelink communication device (B, C) indicating an interference sensitive radio resource, and a processor configured to select one or more radio resources from a plurality of candidate radio resources, in particular Physical Sidelink Shared Channel (PSSCH) resources, for transmission of sidelink data by the sidelink communication device (S), wherein the processor is further configured to exclude from the radio resource selection a candidate radio resource on the basis of a distance or relative location in the frequency domain between the candidate radio resource and the interference sensitive radio resource indicated. Thus, an improved sidelink communication device (S) is provided, allowing for efficient radio resource selection for sidelink communication.

In a further possible implementation form of the fifth aspect, the processor is configured to exclude from the radio resource selection a candidate radio resource if the candidate radio resource or a future occurrence thereof, according to a pre-determined resource reservation interval, is an adjacent or image radio resource, in the frequency domain, with respect to the interference sensitive radio resource indicated and/or a future occurrence thereof.

In a further possible implementation form of the fifth aspect, the processor is configured to exclude from the radio resource selection a candidate radio resource on the basis of a sensitivity measure indicated by the at least one neighboring sidelink communication device (B, C).

In a further possible implementation form of the fifth aspect, the processor is configured to exclude from the radio resource selection a candidate radio resource on the basis of a proximity measure of the sidelink communication device (S) with respect to the at least one neighboring sidelink communication device (B, C), in particular wherein the proximity measure is derived from a measured received signal strength.

In a further possible implementation form of the fifth aspect, the transceiver comprises a plurality of antennas or beams and the processor is configured to exclude from the radio resource selection a candidate radio resource on the basis of the antenna or beam on which the sidelink feedback control information (SFCI) is received and/or the antenna or beam to be used for transmission.

According to a sixth aspect, the invention relates to a method of operating a sidelink communication device (S) comprising a processor configured to select one or more radio resources from a plurality of candidate radio resources, in particular Physical Sidelink Shared Channel (PSSCH) resources, for transmission of sidelink data by the sidelink communication device (S), wherein the method comprises: receiving sidelink feedback control information (SFCI), in particular on a Physical Sidelink Feedback Channel (PSFCH), from at least one neighboring sidelink communication device (B, C) indicating an interference sensitive radio resource; and excluding from the radio resource selection a candidate radio resource on the basis of a distance or relative location in the frequency domain between the candidate radio resource and the interference sensitive radio resource indicated, in particular if the candidate radio resource or a future occurrence thereof, according to a pre-determined resource reservation interval, is an adjacent or image radio resource, in the frequency domain, with respect to the interference sensitive radio resource indicated and/or a future occurrence thereof.

According to a seventh aspect, the invention relates to a sidelink communication device (B, C) comprising a transceiver configured to receive sidelink control information (SCI), in particular on a Physical Sidelink Control Channel (PSCCH), from at least one neighboring sidelink communication device (A, D) indicating and/or reserving a radio resource for transmission of sidelink data by the at least one neighboring sidelink communication device (A, D), and measure a received signal strength, in particular a PSSCH Reference Signal Received Power (PSSCH-RSRP), and a processor configured to determine whether the radio resource indicated and/or reserved is interference sensitive on the basis of the measured received signal strength, in particular if the measured received signal strength is below a threshold value, wherein the transceiver is further configured to transmit sidelink feedback control information (SFCI), in particular on a Physical Sidelink Feedback Channel (PSFCH), to at least one other neighboring sidelink communication device (S) indicating the determined interference sensitive radio resource.

Thus, an improved sidelink communication device (B, C) is provided, allowing for efficient radio resource selection for sidelink communication.

In a further possible implementation form of the seventh aspect, the sidelink feedback control information (SFCI) comprises a sensitivity measure, in particular on the basis of the measured received signal strength.

According to an eighth aspect, the invention relates to a method of operating a sidelink communication device (B, C), wherein the method comprises: receiving sidelink control information (SCI), in particular on a Physical Sidelink Control Channel (PSCCH), from at least one neighboring sidelink communication device (A, D) indicating and/or reserving a radio resource for transmission of sidelink data by the at least one neighboring sidelink communication device (A, D); measuring a received signal strength, in particular a PSSCH Reference Signal Received Power (PSSCH-RSRP); determining whether the radio resource indicated and/or reserved is interference sensitive on the basis of the measured received signal strength, in particular if the measured received signal strength is below a threshold value; and transmitting sidelink feedback control information (SFCI), in particular on a Physical Sidelink Feedback Channel (PSFCH), to at least one other neighboring sidelink communication device (S) indicating the determined interference sensitive radio resource.

According to a ninth aspect, the invention relates to a sidelink communication device (S) comprising a processor configured to select a radio resource from a plurality of candidate radio resources, in particular Physical Sidelink Shared Channel (PSSCH) resources, within a resource selection window comprising a plurality of cycles, in particular radio frames, wherein the processor is configured to select the radio resource on the basis of a time offset, in particular a subframe number, of the radio resource with respect to the beginning and/or the end of the cycle in which the radio resource occurs.

In a further possible implementation form of the ninth aspect, the processor is configured to select the radio resource according to an order of preference of a plurality of possible time offsets, in particular subframe numbers, within the cycle.

In a further possible implementation form of the ninth aspect, the order of preference corresponds to the order of increasing or decreasing time offsets.

In a further possible implementation form of the ninth aspect, the processor is configured to select the radio resource on the basis of a measured interference signal strength, in particular a Sidelink Received Signal Strength Indicator (S-RSSI) and/or a PSSCH

Reference Signal Received Power (PSSCH-RSRP).

In a further possible implementation form of the ninth aspect, the processor is configured to determine an expected received signal quality on the basis of the measured interference signal strength, in particular wherein the expected received signal quality is inversely proportional to the measured interference signal strength, and select the radio resource on the basis of the expected received signal quality. In a further possible implementation form of the ninth aspect, the processor is configured to determine a first set of time resources, in particular subframes, within the resource selection window comprising the first preferred time resource, according to the order of preference, in every cycle, and select the radio resource among a plurality of candidate radio resources contained within the determined first set of time resources, in particular on the basis of the expected received signal quality of the radio resource, in particular the radio resource with the highest expected received signal quality.

In a further possible implementation form of the ninth aspect, the processor is configured to determine whether the expected received signal quality of the radio resource selected in the first set of time resources is above a threshold value, and in case it is not, determine a second set of time resources, in particular subframes, within the resource selection window comprising the second preferred time resource, according to the order of preference, in every cycle, and select the radio resource among a plurality of candidate radio resources contained within the determined second set of time resources, in particular on the basis of the expected received signal quality of the radio resource, in particular the radio resource with the highest expected received signal quality.

According to a tenth aspect, the invention relates to a method of operating a sidelink communication device (S) comprising a processor configured to select a radio resource from a plurality of candidate radio resources, in particular Physical Sidelink Shared Channel (PSSCH) resources, within a resource selection window comprising a plurality of cycles, in particular radio frames, wherein the method comprises: determining a first set of time resources, in particular subframes, within the resource selection window comprising the first preferred time resource, according to an order of preference, in every cycle; and selecting the radio resource among a plurality of candidate radio resources contained within the determined first set of time resources, in particular on the basis of an expected received signal quality of the radio resource, in particular the radio resource with the highest expected received signal quality.

According to an eleventh aspect, the invention relates to a sidelink communication device (S) comprising a processor configured to select a radio resource from a plurality of candidate radio resources, in particular Physical Sidelink Shared Channel (PSSCH) resources, for transmission of sidelink data by the sidelink communication device (S), wherein at least one candidate radio resource comprises a plurality of time resources, in particular contiguous time slots, and wherein the processor is configured to determine an expected received signal quality of the at least one candidate radio resource on the basis of an energy to be transmitted in the plurality of time resources, in particular wherein the energy is proportional to the number of time resources, and select the radio resource on the basis of the expected received signal quality.

In a further possible implementation form of the eleventh aspect, the processor is configured to determine the expected received signal quality of the at least one candidate radio resource comprising a plurality of time resources on the basis of a measured interference signal strength, in particular a Sidelink Received Signal Strength Indicator (S-RSSI) and/or a PSSCH Reference Signal Received Power (PSSCH-RSRP).

In a further possible implementation form of the eleventh aspect, the processor is configured to determine a maximum allowed number of contiguous time resources, construct a set of candidate radio resources for transmission of the sidelink data as a single block comprising a plurality of contiguous time and/or frequency resources, wherein the number of contiguous time resources is at most equal to the maximum allowed number of contiguous time resources, and select the radio resource on the basis of the expected received signal quality of the radio resource, in particular the radio resource with the highest expected received signal quality among the set of candidate radio resources.

In a further possible implementation form of the eleventh aspect, the processor is configured to determine the maximum allowed number of contiguous time resources on the basis of an observed traffic load, in particular a Channel Busy Ratio (CBR).

According to a twelfth aspect, the invention relates to a method of operating a sidelink communication device (S) comprising a processor configured to select a radio resource from a plurality of candidate radio resources, in particular Physical Sidelink Shared Channel (PSSCH) resources, for transmission of sidelink data by the sidelink communication device (S), wherein the method comprises: determining a maximum allowed number of contiguous time resources, in particular on the basis of an observed traffic load; constructing a set of candidate radio resources for transmission of the sidelink data as a single block comprising a plurality of contiguous time and/or frequency resources, wherein the number of contiguous time resources is at most equal to the maximum allowed number of contiguous time resources; and selecting the radio resource on the basis of an expected received signal quality of the radio resource, in particular determined on the basis of an energy to be transmitted in the plurality of contiguous time resources, in particular the radio resource with the highest expected received signal quality among the set of candidate radio resources.

According to a thirteenth aspect, the invention relates to a computer program comprising program code for performing the method of the second, fourth, sixth, eighth, tenth and/or twelfth aspect when executed on a computer.

The invention can be implemented in hardware and/or software.

BRIEF DESCRIPTION OF THE DRAWINGS

Further embodiments of the invention will be described with respect to the following figures, wherein:

Figure 1 shows a schematic diagram illustrating the power spectral density measured at UE B from two received signals (transmitted by UE A and UE C), wherein UE B is unable to decode the signal from UE C due to In-Band Emission (IBE) interference from UE A’s adjacent, much stronger signal;

Figure 2 shows a schematic diagram illustrating an example of candidate radio resources for initial transmission (left) and retransmission (right), within a PSSCH resource pool, according to prior art;

Figure 3 shows a schematic diagram illustrating how PSCCH decoding may be used by a sensing UE (S) to exclude from radio resource selection TTIs used by nearby UEs (B and C), reducing the impact of Half-Duplex (HD), according to an embodiment;

Figure 4 shows a schematic diagram illustrating how PSCCH decoding may be used by a sensing UE (S) to exclude from resource selection radio resources where its transmission would cause In-Band Emission (IBE) interference at nearby UEs (B and C), according to an embodiment; Figure 5 shows a schematic diagram illustrating how, with directional transmission, radio resources may not need to be excluded if the transmission occurs in a direction (Beam 1 , Beam 2) away from an interference sensitive UE (C, B, respectively);

Figure 6 shows a schematic diagram summarizing radio resource exclusion based on PSCCH decoding, according to an embodiment;

Figure 7 shows a schematic diagram illustrating the difficulties that may arise regarding coexistence of services with different periodicities;

Figure 8 shows a schematic diagram illustrating how time-domain‘combs’ may be used to improve coexistence of services with different periodicities, according to an embodiment;

Figure 9 shows a schematic diagram illustrating how multi-slot transmission can be exploited to increase Signal-to-Noise Ratio (SNR), and therefore communication range, especially in a low density scenario;

Figure 10 shows a schematic diagram illustrating a plurality of candidate radio resources for transmission of sidelink data, including multi-slot radio resources, according to an embodiment;

Figure 1 1 shows a diagram illustrating a corresponding method of operating a sidelink communication device according to an embodiment, wherein all candidate radio resources that overlap in the time domain with a radio resource indicated or reserved by a received sidelink control information (SCI) are excluded;

Figure 12 shows a diagram illustrating a corresponding method of operating a sidelink communication device according to an embodiment, wherein a candidate radio resource is excluded if it is an adjacent or image radio resource, in the frequency domain, with respect to a radio resource indicated or reserved by a received sidelink control information (SCI);

Figure 13 shows a diagram illustrating a corresponding method of operating a sidelink communication device according to an embodiment, wherein a candidate radio resource is excluded if it is an adjacent or image radio resource, in the frequency domain, with respect to an interference sensitive radio resource indicated by a received sidelink feedback control information (SFCI); Figure 14 shows a diagram illustrating a corresponding method of operating a sidelink communication device according to an embodiment, wherein the sidelink communication device is configured to transmit sidelink feedback control information (SFCI) indicating an interference sensitive radio resource;

Figure 15 shows a diagram illustrating a corresponding method of operating a sidelink communication device according to an embodiment, wherein the sidelink communication device is configured to determine a first set of time resources within a resource selection window and select a radio resource on the basis of an expected received signal quality; and

Figure 16 shows a diagram illustrating a corresponding method of operating a sidelink communication device according to an embodiment, wherein the sidelink communication device is configured to construct a set of candidate radio resources for transmission of sidelink data as a single block comprising a plurality of contiguous time and/or frequency resources and select a radio resource on the basis of an expected received signal quality.

In the various figures, identical reference signs will be used for identical or at least functionally equivalent features.

DETAILED DESCRIPTION OF EMBODIMENTS

In the following description, reference is made to the accompanying drawings, which form part of the disclosure, and in which are shown, by way of illustration, specific aspects in which the present invention may be placed. It will be appreciated that other aspects may be utilized and structural or logical changes may be made without departing from the scope of the present invention. The following detailed description, therefore, is not to be taken in a limiting sense, as the scope of the present invention is defined by the appended claims.

For instance, it will be appreciated that a disclosure in connection with a described method may also hold true for a corresponding device or system configured to perform the method and vice versa. For example, if a specific method step is described, a corresponding device may include a unit to perform the described method step, even if such unit is not explicitly described or illustrated in the figures.

Moreover, in the following detailed description as well as in the claims, embodiments with different functional blocks or processing units are described, which are connected with each other or exchange signals. It will be appreciated that the present invention covers embodiments as well, which include additional functional blocks or processing units that are arranged between the functional blocks or processing units of the embodiments described below.

Finally, it is understood that the features of the various exemplary aspects described herein may be combined with each other, unless specifically noted otherwise.

As will be described in more detail in the following, embodiments of the invention relate to a V2X communication network comprising a sidelink communication device (S) and

corresponding methods for autonomous resource selection, which allow for an efficient utilization of sidelink radio resources.

Figure 3 shows a schematic diagram illustrating how Physical Sidelink Control Channel (PSCCH) decoding may be used by a sensing UE (S) 301 to exclude from radio resource selection Transmission Time Intervals (TTIs) used by nearby UEs (B and C) 302, 303, reducing the impact of the Half-Duplex (HD) constraint.

According to an embodiment, in order to avoid self-interference and minimize the impact of the HD constraint, a UE (S) 301 interested in receiving a Physical Sidelink Shared Channel (PSSCH) transmission from nearby UEs (B, C) 302, 303 on a given carrier refrains from transmitting its own PSSCH transmission in the TTIs used by the nearby UEs (B, C) 302,

303. The UE may become aware of the TTIs used in its proximity by decoding the Physical Sidelink Control Channel (PSCCH) carrying Sidelink Control Information (SCI). A candidate TTI (e.g., subframe, slot, mini-slot, OFDM symbol, etc.) is entirely excluded from radio resource selection if the candidate TTI (or a future TTI occurring at a pre-determined resource reservation interval thereafter) contains a radio resource indicated or reserved by a decoded SCI, in particular with an associated PSSCH Reference Signal Received Power (PSSCH-RSRP) above a threshold.

In an embodiment, a UE ranks each candidate TTI according to a ranking metric, in particular the strongest PSSCH-RSRP among several PSSCH-RSRPs associated with decoded SCIs indicating or reserving a radio resource that overlaps in the time domain with the candidate TTI (or a future TTI occurring at a pre-determined resource reservation interval thereafter), and exclude a subset of TTIs, e.g., the [X]% worst TTIs (i.e., those with the highest values of the metric), from further consideration in resource selection. If a candidate TTI does not contain any radio resource indicated or reserved by a decoded SCI, the metric value is 0 and the TTI is a good candidate. On the other hand, if a candidate TTI contains a radio resource indicated or reserved by a decoded SCI with very high PSSCH-RSRP, this means the UE expected to transmit on that TTI is in close proximity (therefore, it should be listened to), and the TTI is not a good candidate for transmission.

Figure 4 shows a schematic diagram illustrating how PSCCH decoding may be used by a sensing UE (S) 401 to exclude from resource selection radio resources where its

transmission would cause In-Band Emission (IBE) interference at nearby UEs (B and C) 402, 403.

According to an embodiment, in order to minimize the impact of IBE interference, a candidate radio resource is excluded from resource selection by a UE (S) 401 if the candidate radio resource (or a future radio resource occurring at a pre-determined resource reservation interval thereafter) is an adjacent or image radio resource, in the frequency domain, with respect to a radio resource indicated or reserved by a decoded SCI. An image radio resource is a radio resource that is located symmetrically in the frequency domain with respect to the carrier frequency used by the sensing UE (S) 401. If the UE (S) 401 does not use adjacent and image radio resources for transmission, in-band emissions (IBE) will not have a negative impact on nearby receivers (B, C) 402, 403.

According to an embodiment, a UE (S) 401 decides whether to exclude adjacent and/or image radio resources based on the associated PSSCH-RSRP of a decoded SCI. In particular, if the PSSCH-RSRP associated with a decoded SCI is below a threshold, e.g.,

SCI received from far-away UEs (A, D) 404, 405, the sensing UE (S) 401 may infer that nearby UEs (B, C) 402, 403 would be experiencing a large power imbalance, and thus refrain from transmitting in adjacent and/or image radio resources to those used by the far-away UEs (A, D) 404, 405.

In an embodiment, adjacency is relaxed to include proximal radio resources located within a certain distance in the frequency domain.

Nearby UEs (B, C) 402, 403 may explicitly indicate to the UE (S) 401 one or more

interference sensitive radio resources. This alternative is more reliable, e.g., in Non-Line-Of- Sight (NLOS) conditions, but incurs higher overhead.

According to an embodiment, explicit indication of interference sensitive radio resources is achieved by transmitting sidelink feedback control information (SFCI) on the Physical Sidelink Feedback Channel (PSFCH) including information on the interference sensitive radio resources. Explicit indication may also be achieved by means of control signaling in higher layers (e.g., a MAC Control Element). Referring to Figure 4, according to an embodiment, a UE (B, C) 402, 403 explicitly indicates a given radio resource as being interference sensitive if the UE (B, C) 402, 403 decodes SCI from another UE (A, D) 404,

405 indicating or reserving that radio resource and the associated PSSCH-RSRP is below a threshold. In an embodiment, the SFCI includes information indicating a sensitivity measure, e.g., based on the measured PSSCH-RSRP.

A UE (S) 401 receiving SFCI uses this information to exclude a candidate radio resource if the candidate radio resource (or a future radio resource occurring at a pre-determined resource reservation interval thereafter) is an adjacent or image radio resource with respect to the interference sensitive radio resource indicated by the received SFCI (or a future occurrence thereof).

In an embodiment, the sensitivity measure (if indicated) and/or the proximity of the UE (S)

401 to the UE (B, C) 402, 403 from which the SFCI is received (e.g., derived from a measured received signal strength) are used to decide whether or not to exclude a candidate radio resource. Higher sensitivity and/or proximity may lead to resource exclusion, whereas lower sensitivity and/or proximity may not.

According to an embodiment, the SFCI is encoded by means of a list of resource indices, where each resource index points to a location in time and/or frequency relative to the location in time and/or frequency where SFCI itself is transmitted. A list of n resource indices incurs an overhead of n [log₂QV_r)l bits, where N_r denotes the number of indexable radio resources. For example, if there are 1000 indexable radio resources (e.g., 10 subchannels x 100 slots), 10 bits are needed to indicate each radio resource. The number N_r of indexable radio resources can be reduced if the resource pool to which the radio resources belong is implicitly known, or by indicating only the location in time or frequency (not both).

According to an embodiment, in order to further reduce overhead, the SFCI encodes a change in state (binary toggle) rather than the state itself, i.e., whether a specific radio resource has become interference sensitive or ceased to be interference sensitive since the last SFCI update was sent. For example, if SFCI is sent on PSFCH every 100 ms, only a very small number of radio resources may have changed their state from‘interference sensitive’ to‘non interference sensitive’ (or vice versa) since the last update. This is especially the case if vehicles in opposite directions of travel are time-multiplexed (e.g., use time-orthogonal resource pools). Figure 5 shows a schematic diagram illustrating how exclusion of adjacent and/or image radio resources may be relaxed when using directional transmission, if the transmission occurs in a direction (Beam 1 , Beam 2) 501 , 502 away from an interference sensitive UE (C, B) 403, 402.

According to an embodiment, a UE (S) 401 excludes a candidate radio resource 511 (512) for transmission on a certain beam (or antenna) 501 (502) if the candidate radio resource 511 (512) is an adjacent or image radio resource with respect to a radio resource indicated to be interference sensitive by SFCI received from another UE (B (C)) 402 (403) on beam (or antenna) 501 (502). Thus, if SFCI is received from a direction away from that of the intended transmission beam (or antenna) 501 (502), a candidate radio resource is not excluded, as the transmission will not have an impact (IBE interference) on a UE (B (C)) 402 (403) located in that direction. This has the advantage that radio resources are not excluded unnecessarily, resulting in increased radio resource reuse and higher system capacity.

Figure 6 shows a schematic diagram summarizing radio resource exclusion based on PSCCH decoding. The impact of HD and IBE is mitigated by: a) excluding candidate radio resources that overlap in time with those indicated or reserved by nearby UEs (within

PSSCH range), and b) excluding candidate radio resources that are adjacent and/or image radio resources, in the frequency domain, with respect to those indicated or reserved by nearby UEs (within PSCCH range).

Figure 7 shows a schematic diagram illustrating the difficulties that may arise regarding coexistence of services with different periodicities. UEs A and B want to form a platoon, requiring updates at 100 Hz (i.e., every 10 ms). However, UEs 1-10 (e.g., located on a parallel lane) transmit sensor updates at 10 Hz (broadcast CPMs, Collective Perception Messages, containing detected objects) in radio resources that, in this example, are spread uniformly not only over the 100 ms resource selection window but, more importantly, over the 10 ms radio frame (i.e., each UE uses a different subframe number 1-10 for transmission). If UE A selects the marked radio resource, it won’t be able to listen to UE 3’s sensor updates due to the HD constraint. Similarly, UE B won’t be able to listen to UE 8’s sensor updates. According to the proposed radio resource exclusion strategy, UEs A and B, when selecting a radio resource in the 10 ms resource selection window (100 Hz service), will exclude all subframes 1-10 from consideration, since they are able to predict the HD conflicts occurring later on (radio frames 3 and 8). Thus, the 100 Hz service will be blocked, and the vehicles A and B won’t be able to form the platoon. Figure 8 shows a schematic diagram illustrating how time-domain‘combs’ may be used to improve coexistence of services with different periodicities.

According to an embodiment, time-domain‘combs’ 801 , 802, ..., 810 are defined as time- orthogonal resource pools organized according to the shortest periodicity supported by the C-V2X system. In eV2X, 10 ms is the shortest periodicity (corresponding to an update rate of 100 Hz) required for High Density Platooning. In the example of Figure 8, there are 10 ‘combs’ 801 , 802, ..., 810, each consisting of one subframe per radio frame: the first‘comb’ (COMB 0) 801 corresponds to subframe #0 of each radio frame, the second‘comb’ (COMB 1 ) 802 corresponds to subframe #1 of each radio frame, and so on. Other designs are possible (e.g., 5‘combs’, each consisting of 2 subframes per radio frame, etc.).

When selecting a radio resource according to an embodiment, a UE (S) 301 , 401 first tries to find a radio resource in the first‘comb’ (COMB 0) 801. After radio resource exclusion based on decoded SCIs from nearby UEs (summarized in Figure 6), the UE (S) 301 , 401 ranks all remaining candidate radio resources in the first‘comb’ (COMB 0) 801 according to an expected received signal quality and selects the best radio resource (highest expected quality), or one among the best. If the expected quality is below a threshold, the UE (S) 301 , 401 tries to find a radio resource in the second‘comb’ (COMB 1 ) 802, and so on (803, 804, etc.) - until a radio resource is found with expected quality above the threshold. By proceeding sequentially‘comb’-wise, the radio resource grid 800 is filled in such a way that gaps appear at 10 ms intervals (the shortest periodicity supported by the system). This increases the probability that the UE (S) 301 , 401 will be able to transmit updates at 100 Hz (e.g., when later joining a platoon, see Figure 7) in the gaps, since it won’t be blocked by having to listen to (10 Hz) sensor updates in those subframes.

In an embodiment, the threshold depends on a target Block Error Rate (BLER) to be guaranteed and/or a Modulation and Coding Scheme (MCS) to be used for the PSSCH transmission.

The expected received signal quality may be based on measurements at the sensing UE (S) 301 , 401 , e.g., a Sidelink Received Signal Strength Indicator (S-RSSI) and/or a PSSCH Reference Signal Received Power (PSSCH-RSRP).

The gain, in terms of reduction of the blockage probability for the shortest periodicity service, achieved by such‘comb’-based radio resource selection depends on the specific traffic mix, i.e., the relative amount of traffic corresponding to each periodicity (e.g., 10 ms, 20 ms, 50 ms, 100 ms, etc.)· If all traffic has the same periodicity, there will be no gain. The gain will be highest with a diverse traffic mix, and especially at high traffic loads.

Figure 9 shows a schematic diagram illustrating how multi-slot transmission can be exploited to increase Signal-to-Noise Ratio (SNR) for reliable sidelink communication over a longer range, especially in a low density scenario. Multi-slot transmission, however, increases the channel dwell time and therefore the chances of a Half-Duplex (HD) collision (i.e., a UE not being able to receive because it is still transmitting, or vice versa). Advantageously, the chances of an HD collision are low when UEs are further apart (i.e., low density), whereas the increased SNR becomes important. At high density, on the other hand, the HD constraint makes it desirable to transmit in a single slot, so that many UEs within close range can be time-multiplexed within a short time. In this case, distances are shorter, thus the SNR gain of multi-slot transmission is not essential.

Figure 10 shows a schematic diagram illustrating a plurality of candidate radio resources for transmission of sidelink data, including multi-slot radio resources.

According to the traffic model in specification 3GPP TS 37.885, eV2X payloads may be as large as 60,000 bytes per 30 ms interval (e.g., MPEG video stream for‘see-through’ use case). Instead of constraining candidate radio resources to occupy a single slot, which may be too limiting for large payloads, a Transport Block (TB) may be transmitted over multiple slots using multi-slot radio resources. For example, a TB requiring 6 frequency subchannels when transmitted in a single slot (1001 ) may instead be transmitted on one single frequency subchannel over 6 slots (1004). Other ways may also exist (1002, 1003) to transmit the TB in a single block of contiguous time/frequency resources.

According to an embodiment, when ranking candidate radio resources based on their expected received signal quality, all possibilities (i.e.,‘shapes’) 1001 , 1002, 1003, 1004 are taken into consideration, thus leveraging the increased link budget (higher energy per bit) associated with multi-slot radio resources. For example, transmitting on 3 frequency subchannels over 2 slots (1002) brings a 3 dB gain compared to transmitting on 6 frequency subchannels over 1 slot (1001 ). By considering multi-slot radio resources as candidates in the ranking algorithm, higher flexibility is provided to the scheduler for optimization. Note that, after exclusion, some‘shapes’ 1003, 1004 may not fit within the remaining set of candidate radio resources 1010, 101 1. In an embodiment, the maximum allowed number of slots over which the TB may be transmitted is limited based on an observed traffic load, e.g., a Channel Busy Ratio (CBR). In this way, the impact of the Half-Duplex (HD) constraint, as well as In-Band Emission (IBE) interference, as a result of longer channel dwell times can be reduced (HD limited scenario, see Figure 9).

Figure 1 1 shows a diagram illustrating a corresponding method 1100 of operating a sidelink communication device (S) 301 according to an embodiment which comprises a processor configured to select one or more radio resources from a plurality of candidate radio resources 310, in particular Physical Sidelink Shared Channel (PSSCH) resources, for transmission of sidelink data by the sidelink communication device (S) 301.

The method 1100 comprises the following steps: a first step 1 101 of receiving sidelink control information (SCI), in particular on a Physical Sidelink Control Channel (PSCCH), from at least one neighboring sidelink communication device (B, C) 302, 303 indicating and/or reserving a radio resource for transmission of sidelink data on a pre-defined carrier by the at least one neighboring sidelink communication device (B, C) 302, 303; a second step 1103 of measuring a received signal strength, in particular a PSSCH Reference Signal Received Power (PSSCH-RSRP); and a third step 1 105 of excluding from the radio resource selection on the pre-defined carrier all candidate radio resources 311 , 312 that overlap in the time domain with the radio resource indicated and/or reserved, in particular on the basis of the measured received signal strength.

Figure 12 shows a diagram illustrating a corresponding method 1200 of operating a sidelink communication device (S) 401 according to an embodiment which comprises a processor configured to select one or more radio resources from a plurality of candidate radio resources 410, in particular Physical Sidelink Shared Channel (PSSCH) resources, for transmission of sidelink data by the sidelink communication device (S) 401.

The method 1200 comprises the following steps: a first step 1201 of receiving sidelink control information (SCI), in particular on a Physical Sidelink Control Channel (PSCCH), from at least one neighboring sidelink communication device (A, D) 404, 405 indicating and/or reserving a radio resource for transmission of sidelink data on a pre-defined carrier by the at least one neighboring sidelink communication device (A, D) 404, 405; and a second step 1203 of excluding from the radio resource selection on the pre-defined carrier a candidate radio resource 411 , 412 on the basis of a distance or relative location in the frequency domain between the candidate radio resource 41 1 , 412 and the radio resource indicated and/or reserved, in particular if the candidate radio resource 411 , 412 or a future occurrence thereof, according to a pre-determined resource reservation interval, is an adjacent or image radio resource, in the frequency domain, with respect to the radio resource indicated and/or reserved.

Figure 13 shows a diagram illustrating a corresponding method 1300 of operating a sidelink communication device (S) 401 according to an embodiment which comprises a processor configured to select one or more radio resources from a plurality of candidate radio resources 410, in particular Physical Sidelink Shared Channel (PSSCH) resources, for transmission of sidelink data by the sidelink communication device (S) 401.

The method 1300 comprises the following steps: a first step 1301 of receiving sidelink feedback control information (SFCI), in particular on a Physical Sidelink Feedback Channel (PSFCH), from at least one neighboring sidelink communication device (B, C) 402, 403 indicating an interference sensitive radio resource; and a second step 1303 of excluding from the radio resource selection a candidate radio resource 41 1 , 412 on the basis of a distance or relative location in the frequency domain between the candidate radio resource 411 , 412 and the interference sensitive radio resource indicated, in particular if the candidate radio resource 411 , 412 or a future occurrence thereof, according to a pre-determined resource reservation interval, is an adjacent or image radio resource, in the frequency domain, with respect to the interference sensitive radio resource indicated and/or a future occurrence thereof.

Figure 14 shows a diagram illustrating a corresponding method 1400 of operating a sidelink communication device (B, C) 402, 403 according to an embodiment.

The method 1400 comprises the following steps: a first step 1401 of receiving sidelink control information (SCI), in particular on a Physical Sidelink Control Channel (PSCCH), from at least one neighboring sidelink communication device (A, D) 404, 405 indicating and/or reserving a radio resource for transmission of sidelink data by the at least one neighboring sidelink communication device (A, D) 404, 405; a second step 1403 of measuring a received signal strength, in particular a PSSCH Reference Signal Received Power (PSSCH-RSRP); a third step 1405 of determining whether the radio resource indicated and/or reserved is interference sensitive on the basis of the measured received signal strength, in particular if the measured received signal strength is below a threshold value; and a fourth step 1407 of transmitting sidelink feedback control information (SFCI), in particular on a Physical Sidelink Feedback Channel (PSFCH), to at least one other neighboring sidelink communication device (S) 401 indicating the determined interference sensitive radio resource.

Figure 15 shows a diagram illustrating a corresponding method 1500 of operating a sidelink communication device (S) 301 , 401 according to an embodiment which comprises a processor configured to select a radio resource from a plurality of candidate radio resources 800, in particular Physical Sidelink Shared Channel (PSSCH) resources, within a resource selection window 812 comprising a plurality of cycles 820, 821 , ..., 829, in particular radio frames.

The method 1500 comprises the following steps: a first step 1501 of determining a first set of time resources 801 , in particular subframes, within the resource selection window 812 comprising the first preferred time resource 840, according to an order of preference 840, 841 , ..., 849, in every cycle 820, 821 , ..., 829; and a second step 1503 of selecting a radio resource among a plurality of candidate radio resources contained within the determined first set of time resources 801 , in particular on the basis of an expected received signal quality, in particular the radio resource with the highest expected received signal quality.

Figure 16 shows a diagram illustrating a corresponding method 1600 of operating a sidelink communication device (S) 301 , 401 according to an embodiment which comprises a processor configured to select a radio resource from a plurality of candidate radio resources 1010, 101 1 , in particular Physical Sidelink Shared Channel (PSSCH) resources, for transmission of sidelink data by the sidelink communication device (S) 301 , 401.

The method 1600 comprises the following steps: a first step 1601 of determining a maximum allowed number of contiguous time resources, in particular on the basis of an observed traffic load; a second step 1603 of constructing a set of candidate radio resources 1001 , 1002,

1003, 1004 for transmission of the sidelink data as a single block comprising a plurality of contiguous time and/or frequency resources, wherein the number of contiguous time resources is at most equal to the maximum allowed number of contiguous time resources; and a third step 1605 of selecting the radio resource on the basis of an expected received signal quality of the radio resource, in particular determined on the basis of an energy to be transmitted in the plurality of contiguous time resources, in particular the radio resource with the highest expected received signal quality among the set of candidate radio resources.

While a particular feature or aspect of the disclosure may have been disclosed with respect to only one of several implementations or embodiments, such feature or aspect may be combined with one or more other features or aspects of the other implementations or embodiments as may be desired and advantageous for any given or particular application. Furthermore, to the extent that the terms“include”,“have”,“with”, or other variants thereof are used in either the detailed description or the claims, such terms are intended to be inclusive in a manner similar to the term“comprise”. Also, the terms“exemplary”,“for example” and“e.g.” are merely meant as an example, rather than the best or optimal. The terms“coupled” and“connected”, along with derivatives may have been used. It should be understood that these terms may have been used to indicate that two elements cooperate or interact with each other regardless of whether they are in direct physical or electrical contact, or they are not in direct contact with each other.

Although specific aspects have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that a variety of alternate and/or equivalent

implementations may be substituted for the specific aspects shown and described without departing from the scope of the present disclosure. This application is intended to cover any adaptations or variations of the specific aspects discussed herein.

Although the elements in the following claims are recited in a particular sequence with corresponding labeling, unless the claim recitations otherwise imply a particular sequence for implementing some or all of those elements, those elements are not necessarily intended to be limited to being implemented in that particular sequence.

Many alternatives, modifications, and variations will be apparent to those skilled in the art in light of the above teachings. Of course, those skilled in the art readily recognize that there are numerous applications of the invention beyond those described herein. While the present invention has been described with reference to one or more particular embodiments, those skilled in the art recognize that many changes may be made thereto without departing from the scope of the present invention. It is therefore to be understood that within the scope of the appended claims and their equivalents, the invention may be practiced otherwise than as specifically described herein.

Claims

1. A sidelink communication device (S, 301 ) comprising a transceiver configured to receive sidelink control information (SCI), in particular on a Physical Sidelink Control Channel (PSCCH), from at least one neighboring sidelink communication device (B, C, 302, 303) indicating and/or reserving a radio resource for transmission of sidelink data on a pre-defined carrier by the at least one neighboring sidelink communication device (B, C, 302, 303), and a processor configured to select one or more radio resources from a plurality of candidate radio resources (310), in particular Physical Sidelink Shared Channel (PSSCH) resources, for transmission of sidelink data by the sidelink communication device (S, 301 ), wherein the processor is further configured to exclude from the radio resource selection on the pre-defined carrier all candidate radio resources (311 , 312) that overlap in the time domain with the radio resource indicated and/or reserved.

2. The sidelink communication device (S, 301 ) of claim 1 , wherein the processor is configured to exclude from the radio resource selection on the pre-defined carrier all candidate radio resources for which a future occurrence of the candidate radio resource, according to a pre-determined resource reservation interval, overlaps in the time domain with the radio resource indicated and/or reserved.

3. The sidelink communication device (S, 301 ) of claims 1 or 2, wherein the transceiver is configured to measure a received signal strength, in particular a PSSCH Reference Signal Received Power (PSSCH-RSRP), and the processor is configured to exclude the

overlapping radio resources (311 , 312) on the basis of the measured received signal strength, in particular if the measured received signal strength is above a threshold value.

4. The sidelink communication device (S, 301 ) of claim 3, wherein the processor is configured to determine a plurality of time resources, in particular time slots, for transmission of sidelink data by the sidelink communication device (S, 301 ), rank each of the plurality of time resources on the basis of a measured received signal strength, and exclude from the radio resource selection on the pre-defined carrier all candidate radio resources (311 , 312) that overlap in the time domain with a time resource that ranks above a percentile.

5. The sidelink communication device (S, 301 ) of claim 4, wherein the transceiver is configured to measure the received signal strength in a radio resource associated with sidelink control information (SCI) received from a neighboring sidelink communication device (B, C, 302, 303) indicating and/or reserving a radio resource that overlaps in the time domain with the time resource and/or a future occurrence thereof.

6. The sidelink communication device (S, 301 ) of claims 4 or 5, wherein the processor is configured to rank the time resources on the basis of the strongest among a plurality of measured received signal strengths, in particular PSSCH Reference Signal Received Powers (PSSCH-RSRPs).

7. A method (1100) of operating a sidelink communication device (S, 301 ) comprising a processor configured to select one or more radio resources from a plurality of candidate radio resources (310), in particular Physical Sidelink Shared Channel (PSSCH) resources, for transmission of sidelink data by the sidelink communication device (S, 301 ), wherein the method (1 100) comprises: receiving (1101 ) sidelink control information (SCI), in particular on a Physical Sidelink Control Channel (PSCCH), from at least one neighboring sidelink communication device (B, C, 302, 303) indicating and/or reserving a radio resource for transmission of sidelink data on a pre defined carrier by the at least one neighboring sidelink communication device (B, C, 302, 303); measuring (1 103) a received signal strength, in particular a PSSCH Reference Signal Received Power (PSSCH-RSRP); and excluding (1 105) from the radio resource selection on the pre-defined carrier all candidate radio resources (311 , 312) that overlap in the time domain with the radio resource indicated and/or reserved, in particular on the basis of the measured received signal strength.

8. A sidelink communication device (S, 401 ) comprising a transceiver configured to receive sidelink control information (SCI), in particular on a Physical Sidelink Control Channel (PSCCH), from at least one neighboring sidelink communication device (A, D, 404, 405) indicating and/or reserving a radio resource for transmission of sidelink data on a pre-defined carrier by the at least one neighboring sidelink communication device (A, D, 404, 405), and a processor configured to select one or more radio resources from a plurality of candidate radio resources (410), in particular Physical Sidelink Shared Channel (PSSCH) resources, for transmission of sidelink data by the sidelink communication device (S, 401 ), wherein the processor is further configured to exclude from the radio resource selection on the pre-defined carrier a candidate radio resource (41 1 , 412) on the basis of a distance or relative location in the frequency domain between the candidate radio resource (411 , 412) and the radio resource indicated and/or reserved.

9. The sidelink communication device (S, 401 ) of claim 8, wherein the processor is configured to exclude from the radio resource selection on the pre-defined carrier a candidate radio resource (41 1 , 412) if the candidate radio resource (411 , 412) or a future occurrence thereof, according to a pre-determined resource reservation interval, is an adjacent or image radio resource, in the frequency domain, with respect to the radio resource indicated and/or reserved.

10. The sidelink communication device (S, 401 ) of claims 8 or 9, wherein the transceiver is configured to measure a received signal strength, in particular a PSSCH Reference Signal Received Power (PSSCH-RSRP), and the processor is configured to exclude from the radio resource selection on the pre-defined carrier a candidate radio resource (411 , 412) on the basis of the measured received signal strength, in particular if the measured received signal strength is below a threshold value.

1 1. A method (1200) of operating a sidelink communication device (S, 401 ) comprising a processor configured to select one or more radio resources from a plurality of candidate radio resources (410), in particular Physical Sidelink Shared Channel (PSSCH) resources, for transmission of sidelink data by the sidelink communication device (S, 401 ), wherein the method (1200) comprises: receiving (1201 ) sidelink control information (SCI), in particular on a Physical Sidelink Control Channel (PSCCH), from at least one neighboring sidelink communication device (A, D, 404, 405) indicating and/or reserving a radio resource for transmission of sidelink data on a pre defined carrier by the at least one neighboring sidelink communication device (A, D, 404, 405); and excluding (1203) from the radio resource selection on the pre-defined carrier a candidate radio resource (41 1 , 412) on the basis of a distance or relative location in the frequency domain between the candidate radio resource (411 , 412) and the radio resource indicated and/or reserved, in particular if the candidate radio resource (41 1 , 412) or a future

occurrence thereof, according to a pre-determined resource reservation interval, is an adjacent or image radio resource, in the frequency domain, with respect to the radio resource indicated and/or reserved.

12. A sidelink communication device (S, 401 ) comprising a transceiver configured to receive sidelink feedback control information (SFCI), in particular on a Physical Sidelink Feedback Channel (PSFCH), from at least one neighboring sidelink communication device (B, C, 402, 403) indicating an interference sensitive radio resource, and a processor configured to select one or more radio resources from a plurality of candidate radio resources (410), in particular Physical Sidelink Shared Channel (PSSCH) resources, for transmission of sidelink data by the sidelink communication device (S, 401 ), wherein the processor is further configured to exclude from the radio resource selection a candidate radio resource (41 1 , 412) on the basis of a distance or relative location in the frequency domain between the candidate radio resource (411 , 412) and the interference sensitive radio resource indicated.

13. The sidelink communication device (S, 401 ) of claim 12, wherein the processor is configured to exclude from the radio resource selection a candidate radio resource (41 1 ,

412) if the candidate radio resource (411 , 412) or a future occurrence thereof, according to a pre-determined resource reservation interval, is an adjacent or image radio resource, in the frequency domain, with respect to the interference sensitive radio resource indicated and/or a future occurrence thereof.

14. The sidelink communication device (S, 401 ) of claims 12 or 13, wherein the processor is configured to exclude from the radio resource selection a candidate radio resource (411 , 412) on the basis of a sensitivity measure indicated by the at least one neighboring sidelink communication device (B, C, 402, 403).

15. The sidelink communication device (S, 401 ) of any one of claims 12 to 14, wherein the processor is configured to exclude from the radio resource selection a candidate radio resource (411 , 412) on the basis of a proximity measure of the sidelink communication device (S, 401 ) with respect to the at least one neighboring sidelink communication device (B, C, 402, 403), in particular wherein the proximity measure is derived from a measured received signal strength.

16. The sidelink communication device (S, 401 ) of any one of claims 12 to 15, wherein the transceiver comprises a plurality of antennas or beams (501 , 502) and the processor is configured to exclude from the radio resource selection a candidate radio resource (51 1 ,

512) on the basis of the antenna or beam (501 , 502) on which the sidelink feedback control information (SFCI) is received and/or the antenna or beam (501 , 502) to be used for transmission.

17. A method (1300) of operating a sidelink communication device (S, 401 ) comprising a processor configured to select one or more radio resources from a plurality of candidate radio resources (410), in particular Physical Sidelink Shared Channel (PSSCH) resources, for transmission of sidelink data by the sidelink communication device (S, 401 ), wherein the method (1300) comprises: receiving (1301 ) sidelink feedback control information (SFCI), in particular on a Physical Sidelink Feedback Channel (PSFCH), from at least one neighboring sidelink communication device (B, C, 402, 403) indicating an interference sensitive radio resource; and excluding (1303) from the radio resource selection a candidate radio resource (41 1 , 412) on the basis of a distance or relative location in the frequency domain between the candidate radio resource (411 , 412) and the interference sensitive radio resource indicated, in particular if the candidate radio resource (411 , 412) or a future occurrence thereof, according to a pre-determined resource reservation interval, is an adjacent or image radio resource, in the frequency domain, with respect to the interference sensitive radio resource indicated and/or a future occurrence thereof.

18. A sidelink communication device (B, C, 402, 403) comprising a transceiver configured to receive sidelink control information (SCI), in particular on a Physical Sidelink Control Channel (PSCCH), from at least one neighboring sidelink communication device (A, D, 404, 405) indicating and/or reserving a radio resource for transmission of sidelink data by the at least one neighboring sidelink communication device (A, D, 404, 405), and measure a received signal strength, in particular a PSSCH Reference Signal Received Power (PSSCH-RSRP), and a processor configured to determine whether the radio resource indicated and/or reserved is interference sensitive on the basis of the measured received signal strength, in particular if the measured received signal strength is below a threshold value, wherein the transceiver is further configured to transmit sidelink feedback control information (SFCI), in particular on a Physical Sidelink Feedback Channel (PSFCH), to at least one other neighboring sidelink communication device (S, 401 ) indicating the determined interference sensitive radio resource.

19. The sidelink communication device (B, C, 402, 403) of claim 18, wherein the sidelink feedback control information (SFCI) comprises a sensitivity measure, in particular on the basis of the measured received signal strength.

20. A method (1400) of operating a sidelink communication device (B, C, 402, 403), wherein the method (1400) comprises: receiving (1401 ) sidelink control information (SCI), in particular on a Physical Sidelink Control Channel (PSCCH), from at least one neighboring sidelink communication device (A, D, 404, 405) indicating and/or reserving a radio resource for transmission of sidelink data by the at least one neighboring sidelink communication device (A, D, 404, 405); measuring (1403) a received signal strength, in particular a PSSCH Reference Signal Received Power (PSSCH-RSRP); determining (1405) whether the radio resource indicated and/or reserved is interference sensitive on the basis of the measured received signal strength, in particular if the measured received signal strength is below a threshold value; and transmitting (1407) sidelink feedback control information (SFCI), in particular on a Physical Sidelink Feedback Channel (PSFCH), to at least one other neighboring sidelink

communication device (S, 401 ) indicating the determined interference sensitive radio resource.

21. A sidelink communication device (S, 301 , 401 ) comprising a processor configured to select a radio resource from a plurality of candidate radio resources (800), in particular Physical Sidelink Shared Channel (PSSCH) resources, within a resource selection window (812) comprising a plurality of cycles (820, 821 , ..., 829), in particular radio frames, wherein the processor is configured to select the radio resource on the basis of a time offset, in particular a subframe number, of the radio resource with respect to the beginning and/or the end of the cycle (820, 821 , ..., 829) in which the radio resource occurs.

22. The sidelink communication device (S, 301 , 401 ) of claim 21 , wherein the processor is configured to select the radio resource according to an order of preference of a plurality of possible time offsets (840, 841 , ..., 849), in particular subframe numbers, within the cycle (820, 821 , ..., 829).

23. The sidelink communication device (S, 301 , 401 ) of claim 22, wherein the order of preference corresponds to the order of increasing or decreasing time offsets (840, 841 , ..., 849).

24. The sidelink communication device (S, 301 , 401 ) of any one of claims 21 to 23, wherein the processor is configured to select the radio resource on the basis of a measured interference signal strength, in particular a Sidelink Received Signal Strength Indicator (S- RSSI) and/or a PSSCH Reference Signal Received Power (PSSCH-RSRP).

25. The sidelink communication device (S, 301 , 401 ) of claim 24, wherein the processor is configured to determine an expected received signal quality on the basis of the measured interference signal strength, in particular wherein the expected received signal quality is inversely proportional to the measured interference signal strength, and select the radio resource on the basis of the expected received signal quality.

26. The sidelink communication device (S, 301 , 401 ) of claim 25, wherein the processor is configured to determine a first set of time resources (801 ), in particular subframes, within the resource selection window (812) comprising the first preferred time resource (840), according to the order of preference (840, 841 , ..., 849), in every cycle (820, 821 , ..., 829), and select the radio resource among a plurality of candidate radio resources contained within the determined first set of time resources (801 ), in particular on the basis of the expected received signal quality of the radio resource, in particular the radio resource with the highest expected received signal quality.

27. The sidelink communication device (S, 301 , 401 ) of claim 26, wherein the processor is configured to determine whether the expected received signal quality of the radio resource selected in the first set of time resources (801 ) is above a threshold value, and in case it is not, determine a second set of time resources (802), in particular subframes, within the resource selection window (812) comprising the second preferred time resource (841 ), according to the order of preference (840, 841 , ..., 849), in every cycle (820, 821 , ..., 829), and select the radio resource among a plurality of candidate radio resources contained within the determined second set of time resources (802), in particular on the basis of the expected received signal quality of the radio resource, in particular the radio resource with the highest expected received signal quality.

28. A method (1500) of operating a sidelink communication device (S, 301 , 401 ) comprising a processor configured to select a radio resource from a plurality of candidate radio resources (800), in particular Physical Sidelink Shared Channel (PSSCH) resources, within a resource selection window (812) comprising a plurality of cycles (820, 821 , ..., 829), in particular radio frames, wherein the method (1500) comprises: determining (1501 ) a first set of time resources (801 ), in particular subframes, within the resource selection window (812) comprising the first preferred time resource (840), according to an order of preference (840, 841 , ..., 849), in every cycle (820, 821 , ..., 829); and selecting (1503) the radio resource among a plurality of candidate radio resources contained within the determined first set of time resources (801 ), in particular on the basis of an expected received signal quality of the radio resource, in particular the radio resource with the highest expected received signal quality.

29. A sidelink communication device (S, 301 , 401 ) comprising a processor configured to select a radio resource from a plurality of candidate radio resources (1010, 101 1 ), in particular Physical Sidelink Shared Channel (PSSCH) resources, for transmission of sidelink data by the sidelink communication device (S, 301 , 401 ), wherein at least one candidate radio resource (1002, 1003, 1004) comprises a plurality of time resources, in particular contiguous time slots, and wherein the processor is configured to determine an expected received signal quality of the at least one candidate radio resource (1002, 1003, 1004) on the basis of an energy to be transmitted in the plurality of time resources, in particular wherein the energy is proportional to the number of time resources, and select the radio resource on the basis of the expected received signal quality.

30. The sidelink communication device (S, 301 , 401 ) of claim 29, wherein the processor is configured to determine the expected received signal quality of the at least one candidate radio resource comprising a plurality of time resources on the basis of a measured interference signal strength, in particular a Sidelink Received Signal Strength Indicator (S- RSSI) and/or a PSSCH Reference Signal Received Power (PSSCH-RSRP).

31. The sidelink communication device (S, 301 , 401 ) of claims 29 or 30, wherein the processor is configured to determine a maximum allowed number of contiguous time resources, construct a set of candidate radio resources (1001 , 1002, 1003, 1004) for transmission of the sidelink data as a single block comprising a plurality of contiguous time and/or frequency resources, wherein the number of contiguous time resources is at most equal to the maximum allowed number of contiguous time resources, and select the radio resource on the basis of the expected received signal quality of the radio resource, in particular the radio resource with the highest expected received signal quality among the set of candidate radio resources.

32. The sidelink communication device (S, 301 , 401 ) of claim 31 , wherein the processor is configured to determine the maximum allowed number of contiguous time resources on the basis of an observed traffic load, in particular a Channel Busy Ratio (CBR).

33. A method (1600) of operating a sidelink communication device (S, 301 , 401 ) comprising a processor configured to select a radio resource from a plurality of candidate radio resources (1010, 1011 ), in particular Physical Sidelink Shared Channel (PSSCH) resources, for transmission of sidelink data by the sidelink communication device (S, 301 , 401 ), wherein the method (1600) comprises: determining (1601 ) a maximum allowed number of contiguous time resources, in particular on the basis of an observed traffic load; constructing (1603) a set of candidate radio resources (1001 , 1002, 1003, 1004) for transmission of the sidelink data as a single block comprising a plurality of contiguous time and/or frequency resources, wherein the number of contiguous time resources is at most equal to the maximum allowed number of contiguous time resources; and selecting (1605) the radio resource on the basis of an expected received signal quality of the radio resource, in particular determined on the basis of an energy to be transmitted in the plurality of contiguous time resources, in particular the radio resource with the highest expected received signal quality among the set of candidate radio resources.

34. A computer program comprising program code for performing the methods (1 100,

1200, 1300, 1400, 1500, 1600) of claims 7, 11 , 17, 20, 28 and/or 33 when executed on a computer or a processor.