WO2020093052A1 - System and method for sidelink discovery in vehicular communications - Google Patents

Abstract

Example systems and methods for transmitting discovery signals for vehicle-to-everything (V2X) communications are described. In one example method, a resource configuration is obtained. The data communication resources and discovery resources of the resource configuration can be frequency-division multiplexed (FDM), and the control resources and discovery resources of the resource configuration can be time-division multiplexed (TDM). The discovery resources can be configured as one or multiple resource pools, which can be partitioned into sub-resource pools according to attributes and geographical information based on configuration information. A sub-resource pool is determined and used to transmit a discovery message. For any communication simultaneous with the discovery message or the sub-resource pool, a negative-acknowledgement (NACK) can be sent.

Description

SYSTEM AND METHOD FOR SIDELINK DISCOVERY IN VEHICULAR

COMMUNICATIONS

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Patent

Application No. 62,755,012, filed November 2, 2018, which is incorporated by reference herein in its entirety.

TECHNICAL FIELD

[0002] This disclosure relates to vehicle-to-vehicle communications (V2V).

BACKGROUND

[0003] Vehicle-to-vehicle communications (V2V) unicast or groupcast mode may utilize sidelink communications and may require a discovery process. Due to the potentially high density of user equipment (UEs) in a vicinity such as in a congested highway, efficient methods of discovery may be required.

SUMMARY

[0004] The present disclosure relates to systems and methods for transmitting discovery signals for vehicle-to-everything (V2X) communications.

[0005] In some implementations, a resource configuration is obtained. The data communication resources and discovery resources of the resource can be frequency- division multiplexed (FDM), and the control resources and discovery resources of the resource configuration can be time-division multiplexed (TDM). The discovery resources can be configured as one or multiple resource pools, which can be partitioned into sub-resource pools according to attributes and geographical information based on configuration information. The sub-resource pool where to transmit a discovery message is determined, and the discovery message is transmitted. For any communication simultaneous with the discovery message or the sub-resource pool, a negative-acknowledgement (NACK) can be sent.

[0006] The details of one or more implementations of the subj ect matter of this specification are set forth in the accompanying drawings and the description. Other features, aspects, and advantages of the subject matter will become apparent from the description, the drawings, and the claims.

DESCRIPTION OF DRAWINGS

[0007] FIG. 1 A is an illustration of an example of UE discovery signal transmissions, according to an implementation.

[0008] FIG. 1B is an illustration of example resource configurations, according to an implementation.

[0009] FIG. 2 is an illustration of an example set of discovery resources (DR) in within a subframe, according to an implementation.

[0010] FIG. 3 is an illustration of an example of multiplexing of discovery resources, control resources, and communication resources in a slot, according to an implementation.

[0011] FIG. 4 illustrates several examples of an FDM requirement between discovery resources and control resources, according to an implementation.

[0012] FIG. 5 illustrates an example of a location-based resource pool for device discovery, according to an implementation.

[0013] FIG. 6 illustrates an example of a location-based resource pool additionally associated with a velocity parameter for device discovery, according to an implementation.

[0014] FIG. 7 illustrates examples for discovery pool partitioning, according to an implementation.

[0015] FIG. 8 illustrates an example of atribute-based resource pool configuration, according to an implementation.

[0016] FIG. 9 illustrates an example table of resource pool attributes and values maintained by a UE, according to an implementation.

[0017] FIG. 10 illustrates an example flowchart for transmiting and/or receiving discovery messages, according to an implementation.

[0018] FIG. 11 illustrates an example of discovery messages comprising reference signals and payloads.

[0019] FIG. 12 illustrates an example flowchart for transmiting discovery signals by a UE, according to an implementation.

[0020] FIG. 13 illustrates an example flowchart for receiving discovery signals by a UE, according to an implementation.

[0021] FIG. 14 illustrates an example flowchart for transmiting discovery signals by a UE, according to an implementation. [0022] FIG. 15 illustrates an example flowchart for receiving discovery signals by a UE, according to an implementation.

[0023] FIG. 16 illustrates an example of when negative-acknowledgment

(NACK) messages may be sent in relation to the receipt or transmission of discovery messages.

DETAILED DESCRIPTION

[0024] The following detailed description relates to vehicle-to-vehicle (V2V) communications, and is presented to enable any person skilled in the art to make and use the disclosed subject matter in the context of one or more particular implementations.

[0025] Various modifications, alterations, and permutations of the disclosed implementations can be made and will be readily apparent to those of ordinary skill in the art, and the general principles defined may be applied to other implementations and applications, without departing from scope of the disclosure. In some instances, details unnecessary to obtain an understanding of the described subject matter may be omitted so as to not obscure one or more described implementations with unnecessary detail inasmuch as such details are within the skill of one of ordinary skill in the art. The present disclosure is not intended to be limited to the described or illustrated implementations, but to be accorded the widest scope consistent with the described principles and features.

[0026] It is expected that vehicle-to-every thing (V2X) communications will play an essential role in the evolution of the automotive industry in the near future and revolutionize the field. Dedicated short-range communication (DSRC) by the Institute of Electrical and Electronics Engineers (IEEE) and the long-term evolution-vehicular (LTE-V) developed by the Third Generation Partnership Project (3 GPP) are two major vehicular communication technologies developed thus far.

[0027] The 3GPP has also approved a study item for the fifth generation (5G) new radio access technology (NR) vehicle-to-everything (V2X) wireless communication with the goal of providing 5G-compatible high-speed reliable connectivity for vehicular communications in the near future for applications such as safety systems and autonomous driving.

[0028] Device-to-device (D2D) mode of communication is key to enabling

V2X. A major improvement by NR V2X with respect to its counterpart LTE-V is that it is planned to support unicast and groupcast communications. An element for enabling unicast and groupcast communication is discovering other vehicle user equipment (UEs), particularly vehicle UEs that are in the vicinity. This disclosure presents a discovery method for V2X in particular and sidelink communications in general. It describes a frame structure to accommodate both discovery and communications. [0029] It should be noted that despite emphasis on sidelink discovery for unicast and groupcast communications, the methods proposed herein may be applicable to other types of communications that may need or benefit from a discovery process, such as multicast. It should also be noted that device discovery in this disclosure may refer to any process that may comprise communication of signals by a device to find other devices in a vicinity with which it may communicate. Communications that follow a discovery process may be preceded by processes that establish a link, which may be called a sidelink, update or refine a currently established link, or recover a link that was established at an earlier time. The systems and methods proposed in this disclosure may, therefore, be applicable to a variety of applications whether or not they are associated with the term discovery. Furthermore, elements of the disclosure such as resource pool configurations, partitioning of resource pools, association of resource pools to locations or other attributes, and multiplexing rules may be applicable to communications other than discovery.

[0030] The following options for discovery can be considered for establishing a sidelink:

a. “Option 0”: Discovery through the network: UEs connected to a network can be assisted by the network to discover each other. A discovery process may be initiated by the network or by a UE interested to establish a sidelink connection with another UE in its vicinity.

b. Option 1 : Discovery through safety messages or other communication messages: Safety messages, such as basic safety messages (BSMs), are to be broadcast by UEs in V2X communications. It has been proposed previously that the safety messages be used for the purpose of discovering other UEs, i.e., when a first UE receives a safety message from a second UE, it automatically realizes that the second UE is in its vicinity and can establish a sidelink with the second UE for unicast or groupcast communications. There are multiple issues with this method. Firstly, this method overloads the role of safety messages and, therefore, limits and/or complicates the design of safety messaging and/or discovery signaling. Secondly, a UE broadcasting safety messages may not be necessarily interested in establishing a sidelink for unicast or groupcast or may not be interested in a specific service or otherwise a specific connection. In these cases, a significant amount of resources may be wasted on unsuccessful attempts to establish sidebnks. Thirdly, this method is useful specifically for V2X applications and may not be feasible for other D2D applications.

c. Option 2: Discovery through the use of a specific channel between devices: With this method, a set of resources or resource pools is reserved for the UEs to transmit discovery messages, possibly on a dedicated channel such as physical sidelink discovery channel (PSDCH). Although this option may be enabled without a PSDCH, using a PSDCH may be beneficial compared to using physical sidelink shared channel (PSSCH), since it may reduce transmission constraints. For instance, a message can be transmitted on less than a physical resource block (PRB) per slot, and can enjoy a lower overhead without, e.g., a medium access control (MAC) overhead. This option avoids disadvantages of Option 1 and allows flexible designs for discovery in terms of message size, message content, discovery period, and so on. The content of the discovery messages can then be designed to minimize overhead. The discovery message may contain information similar to the LTE D2D discovery message, e.g., a UE identity (such as a physical layer identifier (ID)) and a service indicator, along with reference signals for demodulation. While more information may be added such as UE capability, channel conditions, and so on, a compact message may be sufficient to enable discovery for unicast or groupcast purposes.

[0031] One of the LTE D2D techniques is sidelink discovery, which consists in the ability to discover neighboring UEs. Discovery can be either eNB-assisted discovery or open discovery:

a. With eNB-assisted discovery one UE is directed to transmit a signal, e.g., a sounding reference signal (SRS), and another UE is required to listen and report the signal quality to the enhanced NodeB (eNB). The eNB can then, based on this reported signal quality, decide if proximity services (ProSe) can be enabled for the two UEs. b. With open discovery any UE can transmit a“beacon” signal to advertise its presence to other UEs. Note that this process can possibly involve idle UEs.

[0032] For D2D communications, it is also generally assumed that D2D occurs on the uplink (UL) portion of the bandwidth since the interference would be less prejudicial to cellular UEs on the UL: on the UL, a transmitting D2D UE interferes with the eNB. Consequently, as long as the D2D UE is at a reasonable distance from the eNB, the interference created by the D2D UE may not have significant impact. Conversely, on the downlink (DL), D2D interference affects neighboring UEs and, potentially, their ability to receive synchronization channels and control channels may be affected and can result in significantly higher impact than if the D2D UE were transmitting only on the UL frequencies.

[0033] Given that D2D communication takes place on the UL frequencies, it is reasonable to assume that the D2D discovery occurs on the UL frequencies as well.

[0034] For open discovery, a given number of subframes, e.g., 1%, are reserved for discovery. During these subframes, there usually is no cellular communication multiplexed simultaneously. Only UE discovery signals are transmitted as shown in FIG. 1A.

[0035] The subframe devoted for discovery is composed of several discovery resources (DR). A DR comprises a set of resource elements (REs) within the subframe. For instance, a DR could be an entire physical resource block (PRB) pair as shown in FIG. 2.

[0036] While some principles of LTE D2D discovery can be reused for NR

V2X, the discovery procedure of LTE D2D has the following shortcomings for NR V2X.

a. Discovery in LTE D2D is an intrinsically slow process since the main goal of D2D discovery is to discover services. For NR V2X, the goal is to establish a unicast or groupcast link and, thus, the process needs to be faster.

b. Discovery in LTE D2D relies on a time-division multiplexing subframe- based partitioning of resources between communication and discovery resource pools. Such an approach is impractical in NR V2X because some advanced V2X services have latency requirements in the order of 3 milliseconds. Thus, the communication resource pool cannot be fractioned at the subframe/slot level.

c. Discovery in LTE is undifferentiated: all services share the same pools, and all UEs, regardless of their location, use the same pools. This approach is suboptimal for NR V2X discovery where a UE is typically interested in one type of service and where the location information is crucial. For instance, on a separated highway, a vehicle UE may not need to communicate with the vehicle UEs traveling in the opposite direction.

[0037] Consequently, there is a need for a frame structure to accommodate the specific needs of NR V2X discovery.

[0038] In some embodiments, an NR sidelink is structured as follows.

[0039] Three types of resource pools are defined:

a. Communication resource pools, where physical sidelink shared channel (PSSCH) signals are transmitted. Communication resource pools may also be called data resource pools.

b. Control resource pools, where physical sidelink control channel (PSCCH) signals are transmitted.

c. Discovery resource pools, where discovery messages are transmitted.

[0040] Three example options are shown in FIG. 1B, where C stands for control and S stands for shared/data. It is noted that some of these pools may be overlapping or shared. For instance, there may not be a separate control resource pool, but instead, control signals may be transmitted in a communication resource pool. Similarly, discovery resource pools may overlap or be located in a communication resource pool.

[0041] In some embodiments, discovery resource pools are time-division multiplexed (TDM'ed) with control resource pools so that a UE can decode control signals and know whether it should expect a communication message. This multiplexing constraint may apply to all discovery and control signals, or they may apply to discovery and control signals from a point of view of a UE.

[0042] In some embodiments, discovery resource pools are frequency-division multiplexed (FDM'ed) and/or time-division multiplexed (TDM'ed) with communication resource pools.

[0043] Discovery resource pools may be fractioned into sub-resource pools according to attributes such as services requested or offered, location information, proximity information, and so on, so that different needs can be accommodated, e.g., different quality of service (QoS) requirements such as discovery/connection latency, different message sizes, and different density of UEs interested in a particular service in a vicinity.

[0044] A possible configuration according to earlier descriptions is where discovery resources are FDM’ed with communication resources and TDM’ed with control resources. An example is shown in FIG. 3 where multiplexing between control and data follows option 3 in FIG. 1B.

[0045] Note that this is only shown as an example. Other examples are shown in FIG. 4, where C stands for control, D stands for discovery, and labels for shared/data resources are omitted for brevity. Note also that, there may be deviations from the examples shown. For example, there may be time gaps between control and discovery resources, discovery resources may not span the entire slot, different fractions of discovery resources may not have symmetries, configurations may be different in consecutive slots, configurations may be different from different UE perspectives, etc. In addition, example multiplexing configurations may go to levels other than the slot level, e.g., at the level of a symbol, several symbols, a mini-slot, a subframe, a group of subframes, a frame, etc.

[0046] The resource pool configuration for discovery signals can be sent, for example, by a radio resource control (RRC) message, a medium access control (MAC) message, a control message from the physical layer, or another message, and/or may be preconfigured. The configuration message can be dedicated or broadcast (e.g., a system information block (SIB) message). The configuration message may comprise:

a. Time resource parameters such as: a time offset for a starting point in time, a periodicity (if the allocation is periodic or semi-persistent), a bitmap indicating the resource allocation, symbol indexes, a number of repetitions, etc.;

b. Frequency resource parameters such as: a starting point in frequency, an ending point in frequency, a list of PRBs, etc.;

c. A list of CDMA codes or discovery patterns;

d. Spatial resource parameters conveying information for beamforming such as directions, beam-widths, beamforming patterns, etc. [0047] The discovery resources, whether in an explicit or implicit pool, may be further partitioned. This has the following advantages for a UE performing discovery:

a. The UE performs discovery only for UEs of interest, and can eliminate other UEs it is not interested in, e.g., UEs on a different road/lane/direction, UEs requiring a different service, etc. b. The communication operation is affected as little as possible: the interruption to communication is minimal, and only occurs when the UE needs to perform a specific discovery. This helps maintaining high reliability and high throughput for the V2X communications other than the discovery.

c. Discovery messages of different types can be allocated different resource pools, for example discovery messages of different size or requiring different QoS requirements may be allocated different resource pools.

[0048] It should be noted that different terms may be used in a standard that follow the same principles of resource pool configurations, partitioning, and so on. For example, the term resource pool may be used to refer to a plurality of resource sets while the term sub-resource pool may be used to refer to each partition within the resource pool. Alternatively, each of the partitions may be called a resource pool, while a plurality of resource pools may also be called a resource pool. Other variations or a higher number of levels in a hierarchy of resource pool configuration is not precluded and, therefore, terms may be used interchangeably herein. For example, a resource pool may refer to a resource pool partition or may refer to a plurality of resource pool partitions.

[0049] Examples of discovery resource pools partitioning are described herein based on different attributes. First, as an example, partitioning based on location/proximity information is presented. Then, a more general example of partitioning based on attributes such as location/proximity, required services, and so on, is presented.

[0050] An example of a location-based resource pool for device discovery is illustrated in FIG. 5. In this example, UE1 510 and UE2 512 locate themselves in Location Zone 1 501 and therefore use resource pool 1 (RP1) 520 for transmissions of discovery signals. UE3 514 and UE4 516 locate themselves in Location Zone 2 502, and therefore use resource pool 2 (RP2) 522 for transmissions of discovery signals. It can be seen in the figure that although UE2 512 and UE4 516 are in a close vicinity, they use different resource pools for transmitting discovery signals. Hence, a UE may need to monitor not only resource pools associated with its own location, but also resource pools associated with nearby locations in order to detect UEs in its vicinity. The nearby location zones may be selected by the UE, determined by the network, or determined by the standard.

[0051] In this example, a UE monitors and discovers other UEs in its vicinity based on the location information. This may result in receiving discovery messages from UEs that are not of interest. An example in vehicular communications is where vehicles in a divided highway may only be interested to communicate with other vehicles driving in the same direction.

[0052] In order to address the above issue, in an example implementation, a resource pool is additionally associated with a velocity parameter, such as the direction of a UE’s movement. An example is shown in FIG. 6. In this example, UE1 610, UE2 612, UE5 618, UE7 622 are in Location Zone 1 601. However, based on information on the direction of their movement, UE1 610 and UE2 612 use resource pool RP11 630, and UE5 618 and UE7 622 use resource pool RP12 632. Similarly, UE3 614, UE4 616, UE6 620, UE8 624 locate themselves in Location Zone 2 602, but based on direction of their movement, UE3 614 and UE4 616 use resource pool RP21 634, and UE6 620 and UE8 624 use resource pool RP22 636.

[0053] In some embodiments, an association between the location of the UE and location-dependent parameters in a configuration may be static (e.g., determined by the standard), dynamic (e.g., configured by a network), or a combination thereof (some static and some dynamic, or dynamic with default values determined by the standard, etc.). When a UE is in the coverage (IC) of a network entity, it may receive configuration of discovery resource pools and association of location-dependent parameters with the location. The configuration may be sent, for example, in a unicast or a broadcast transmission by the network. If a UE is out of coverage (OOC), such as UE9 626 of FIG. 6, it may be informed of the configuration from the last time it was in coverage and it received a configuration.

[0054] In an embodiment for configuration of location-based resource pool, all possible locations may be divided into zones where resource pools within a zone are identical. The relationship between a location and its associated resource pool may be specified by a function, a lookup table, a combination thereof, or other methods. For example, parameters of resources allocated to a resource pool may be divided into rectangular zones in a two-dimensional plane, each zone specified by values of longitudes and latitudes of its edges. Resource pools may then be configured in a way that attempts to limit interference from UEs in one zone to UEs in other zones that are in the vicinity.

[0055] It should be noted that in the present disclosure, a UE determines the location-based resources based on its estimation of the location, which is obtained through a system, for example a GPS receiver, which may be subject to inaccuracies and errors. Therefore, in this disclosure, the term“location” associated with a specific UE or a generic UE may either refer to an actual location, understood by an outside observer or by the network, or refer to a location estimated by a specific UE that is naturally subject to inaccuracies and errors.

[0056] In another embodiment, a location zone may not be contiguous, but fractioned. Due to the possibly fine granularity of fractions of each zone, a UE in the area may need to monitor multiple resource pools for receiving discovery messages. Fractions of a location zone may be configured by a formula, a lookup table, a pseudorandom seed, or other methods. The advantage of this embodiment is possible interference reduction on each resource pool, especially when an area is populated by a large number of UEs.

[0057] In yet another embodiment, locations in an area may be divided to fractions, each possibly with a fine granularity. Resources or resource pools are then configured and associated with different fractions. The associations between fractions and resources or resource pools may be determined by a formula, a lookup table, a pseudorandom seed, or other methods. Then, a location zone may be defined as the plurality of fractions that share same resources or a same resource pool.

[0058] Resource pools for discovery may further be associated with other parameters such as UE direction, a UE lane, a UE elevation (which may be useful for example, for a highway crossing another highway through a bridge), and so on.

[0059] As an example, a discovery resource pool partitioning can be done as follows: a. A discovery resource pool or a discovery channel is (pre)configured following similar rules as described earlier with regards to multiplexing and so on.

b. Then, the resource pool or the channel can further be partitioned for different UEs, different group of UEs, different services, different connection types, different message attributes such as message sizes, and so on.

[0060] Examples for discovery resource pool partitioning are illustrated in FIG.

7.

[0061] The discovery resource partitioning may be done at the slot level, at the symbol level, or at the level of several symbols, a mini-slot, a subframe, a group of subframes, a frame, and so on. The discovery resource partitioning may be done using the same or similar signaling as for a resource pool. Each sub-resource pool may be described as a separate resource pool or instead may be signaled as partitioning of a larger resource pool or a channel (pre)configured earlier.

[0062] It should be noted that despite the emphasis on the phrase“resource pool” in this disclosure, the pool of resources allocated to the discovery signals or other signals may not be called a resource pool explicitly.

[0063] It should be noted that although example embodiments of this disclosure are mentioned for discovering any UE by any other UE, configurations and signaling by the network may be dedicated to a particular pair or a group of UEs that have communicated their interest to the network.

[0064] Alternatively or additionally, resource pools for discovery may further be associated with other parameters such as a type of service or connection for which a sidelink of interest is about to be used. This allows a generalization of the location- based resource pool to attribute-based resource pools. In this approach, multiple resource pools are configured and distinguished by different attributes that may include location, direction of velocity or orientation of a UE, a type of service, a type of sidelink of interest, and so on. It should be noted that:

a. As mentioned earlier, the multiple resource pools may be considered by a standard as one resource pool (RP) comprising several sub-RPs. Other terms may be used instead. This should be considered only a matter of terminology while the principles are common among the possible alternatives.

b. Resource pools or sub-RPs may be configured and maintained through separate configurations or joint configurations. Configurations may be provided by various communication entities and produced in various network layers, e.g., radio resource control (RRC), medium access control (MAC), and/or the physical layer.

[0065] An example of attribute-based resource pool configuration is illustrated in FIG. 8. In this example, resource pools RP1, RP2, RP3, and RP4 are time-division- multiplexed (TDM’ed), while those resource pools are frequency-division-multiplexed (FDM’ed) with the rest of the resources available for sidelink communications. Consider an example UE, called UE1, which based on its location and other attributes selects RP2 and RP4 for discovery, which may include transmission of a discovery signal and listening to discovery signals from other UEs. As a result, UE1 may be unable to transmit other signals during those period due to the half-duplex constraint of the transceivers on UE1 and, therefore, nodes may need to refrain from scheduling UE1 transmissions during those periods. This scheduling constraint will be explained below.

[0066] Attributes may include location information and service type. Different attributes may be obtained by the UE from different entities. For example, location information may be obtained from a GPS receiver while service type of interest may be obtained from a higher layer application. It should be noted that the nature of the attributes and the value for the corresponding parameters may or may not be recognized by the physical layer or other lower layers involved in the process of discovery. Indeed, the attribute information provided to the lower layers may be in abstract forms comprising attribute fields and value fields.

[0067] It should be noted that FDM between resource pools is not precluded as an alternative or in addition to TDM between resource pools. By way of example and not by way of limitation, TDM and FDM may be used to represent different attributes. For instance, resource pools for different locations may be TDM’ed while resource pools for different services in a location may be FDM’ed. Then, UEs interested in services in a location may need to monitor FDM’ed resource pools and be available for other communications the rest of the time. Such a differentiation between attributes based on multiplexing method may be preconfigured by the standard or may be configured during the operation of the system.

[0068] In one example illustrated in FIG. 9, based on the attributes and values provided in the resource pool configurations, a UE may maintain a table 900 of resource pool attributes 904 and values 906 that are associated with resource pools 902. The content of the table 900 may expire, may be updated through more recent configurations, or may otherwise change over time. In some examples, the resource pool attribute 904 can include at least one of the following: services requested or offered, location information, proximity information, direction of velocity or orientation of a UE, a type of service, a type of sidelink of interest, and so on.

[0069] Then, the UE may select one or more resource pools based on its attributes of interest. The UE may indeed use different resource pools to discover or offer different services or applications. For example, one resource pool may be associated with vehicle platooning while another resource pool may be associated with a sensor fusion application. Associating numbers to attributes and values may be specified by the standard or may be communicated through signaling, or may be preconfigured.

[0070] The UE can perform discovery while operating in a V2X mode in a number of ways. Several operational flows are described herein. In some instances, an issue may arise when the UE is scheduled to receive a communication message while having to transmit a discovery message at the same time. A flowchart for an example method 1000 of transmitting and/or receiving discovery messages is illustrated in FIG. 10

[0071] As illustrated, the UE first obtains (pre)configuration for a discovery channel and/or at least a resource pool at 1002. As previously indicated, multiple resource pools may be configured as a resource pool partitioned into sub-resource pools. Then, based on attributes of each resource pool, the UE determines what resource pools it wants to use for transmission and/or reception of discovery messages at 1004. The resource pools may be preconfigured or configured by control signaling such as RRC signaling.

[0072] The UE can then decode the PSCCH at 1006 and determine, at 1008, if it has to receive messages on the sidelink based on the decoded PSCCH. The messages can be unicast, groupcast, multicast, and so on. The messages may be for the same subframe or for a following subframe, for the same (component) carrier or for another (component) carrier, and so on.

[0073] If there are no data scheduled in reception for the UE, the UE can proceed with transmitting and/or receiving discovery messages at 1010. If there is a half-duplex issue, e.g., the UE should transmit a communication message and listen to discovery messages simultaneously, priority rules may apply. For instance, the UE can prioritize transmitting a communication message over monitoring a discovery channel, or vice versa. Prioritization between a discovery and other communications (such as data) may depend on various factors such as QoS requirements for the discovery and those for other communications, a number of retransmissions thus far for the other communications, priorities set by a standard, priorities set by a network, and so on.

[0074] If there are data scheduled for the UE, the UE needs to determine and resolve multiplexing conflicts between data and discovery at 1012, and transmit and/or receive discovery messages or transmit and/or receive other data at 1014. For example, a conflict happens when the UE should transmit a discovery message and receive a communication message simultaneously, e.g., in the same subframe. These conflicts can be resolved by determining priorities such as quality-of-service (QoS) requirements. For instance, a low-priority data can be ignored in favor of a discovery resource pool that is for a higher priority service, or vice versa.

[0075] If a data reception is de-prioritized in favor of a discovery resource pool, the UE can treat the discovery transmission as follows:

a. A puncture in the received communication message: if the transmission of the discovery message is shorter than the received communication message, the UE may still attempt to decode the communication message. Depending on success/failure of the decoding, the UE may send an acknowledgement (ACK) or a negative-acknowledgment (NACK).

b. An automatic NACK: if the transmission of the discovery message is the same or longer length of the communication message the UE is attempting to receive, the UE cannot receive the communication message. In such a case, the UE may send a NACK and rely on a hybrid automatic repeat request (HARQ) process to attempt to successfully receive the message in later retransmissions. [0076] A discovery message may be a sequence-type signal (e.g., a reference signal, a synchronization signal, or a preamble), a message-type signal (e.g., a packet of data or payload in a broadcast channel), or a combination thereof, such as a data transmission containing reference signals or a synchronization signal block comprising synchronization signals and a broadcast message. Information may be carried in the sequence, in the message, or in a combination thereof.

[0077] FIG. 11 illustrates an example of discovery messages 1101 comprising reference signals 1102 and payloads 1104. The information carried by a discovery message 1101 transmitted by a UE may include any or all of the following:

a. an identity parameter of the discovery message such as a sequence number,

b. information related to a type of the discovery message,

c. an identity parameter of the UE, or a group of UEs, or a connection, and so forth,

d. information related to a service or a type of connection that the UE is offering or requesting,

e. information related to a minimum signal quality for initiating a sidelink connection,

f. information related to the environment such as the interference being detected by the UE, channel conditions, number of current sidelink connections, and so forth,

g. information related to resources used for transmission of the discovery message, e.g., a spatial resource information such as a beam index, h. information related to other discovery messages from the UE such as information of any other replicas of the discovery message, i. information related to resources allocated for transmission of a discovery report by another UE that may detect the discovery message, or

J· other information for establishing, updating, or recovering a sidelink.

[0078] The size of a discovery message 1101 may be fixed or may be variable based on what fields and what values are included in the message.

[0079] The modulation and coding scheme (MCS) to transmit a discovery message 1101 may be fixed by the standard or may be variable. In the latter case, selection of an MCS from a set of possible MCSs may be up to the UE based on, for example, an interference it is detecting; alternatively, an MCS for transmission of discovery messages may be selected and communicated by the network, for example, as a part of a resource pool configuration.

[0080] It is noted that depending on whether a discovery message contains a variable number of information bits and whether the UE uses a variable MCS for transmitting a discovery message, different discovery messages may need a variable amount of resources.

[0081] Variations may also be distinguished based on whether or not analog beamforming is employed, which may depend on the frequency band. For example, if only digital beamforming is employed, the UE may be able to transmit other signals simultaneously with transmitting a discovery signal, or it may be able to receive other signals simultaneously with listening to the discovery pool. If, instead, analog beamforming is employed, possibly in addition to digital beamforming in a hybrid manner, the UE may not be able to transmit or receive other signals to/from a particular direction simultaneously with transmitting or listening to discovery signals.

[0082] As a result, multiplexing rules may be affected by presence of analog beamforming and/or by the frequency band. For example, from a perspective of a UE that is interested to receive control signals and search for discovery messages, the control signals and the discovery messages may need to be TDM’ed if at higher frequencies such as frequency range 2 (FR2) while they may be allowed to be FDM’ed at lower frequencies such as frequency range 1 (FR1).

[0083] In addition, cases of transmission and reception are distinguished due to the half-duplex constraint. Different example cases are distinguished as below.

[0084] If such scheduling constraints are applicable to a UE, other nodes that may transmit to the UE, expect a transmission from the UE, or schedule a transmission for the UE may need to be informed of the constraints. That may be implicit or explicit through signaling. An implicit way is when other nodes know which resource pools are selected by the UE. An explicit way may be that the UE informs other nodes of the scheduling constraints or the resource pools of its interest. For example, the UE may inform the network or other UEs on sidelinks that it will be busy during certain periods of time or certain resource pools are of interest to the UE. The informing of other nodes by a UE may be through designated signaling such as control messages sent by the UE. [0085] A UE intending to transmit a discovery message may use resources from a resource pool for transmission. If a resource pool is associated with a location or a set of locations, for example through a configuration, the UE may need to obtain (an estimate of) its own location in order to specify which resources are available to it. The selected resources may or may not be contiguous in time or frequency, but may follow a pattern known to other nodes.

[0086] FIG. 12 illustrates a flowchart of an example method 1200 for transmitting discovery signals by a UE. At 1202, the UE obtains configurations of resource pool(s) for discovery signals and associations of the resource pool(s) with a location of the UE. The obtaining of the configuration may comprise a preconfiguration by the network or by the standard and/or receiving a configuration, fully or partially, from the network.

[0087] At 1204, the UE obtains (an estimate of) its location from a positioning system such as a GPS receiver.

[0088] At 1206, the UE selects resources from the resource pool(s) in association with its current location.

[0089] At 1208, the UE transmits discovery signals on the selected resources.

The UE may select different resources for different transmissions of discovery signals. Also, at any point in time where the current location or the configurations change, the UE may need to select different resources for transmission of discovery signals.

[0090] FIG. 13 illustrates a flowchart of an example method 1300 for receiving discovery signals by a UE. At 1302, the UE obtains configurations of resource pool(s) for discovery signals and associations of the resource pool(s) with a location of the UE. The obtaining of the configuration may comprise a preconfiguration by the network or by the standard and/or receiving a configuration, fully or partially, from the network.

[0091] At 1304, the UE obtains (an estimate of) its location from a positioning system such as a GPS receiver.

[0092] At 1306, the UE listens to the resource pool(s) in association with its location. At any point in time where the current location or the configurations change, the UE may listen to different resource pool(s) to receive discovery signals.

[0093] FIG. 14 illustrates a flowchart of an example method 1400 for transmitting discovery signals by a UE through a generalized attribute-based method. At 1402, the UE obtains configurations of resource pool(s) for discovery signals and associations of the resource pool(s) with one or multiple attributes. The obtaining of the configuration may comprise a preconfiguration by the network or by the standard and/or receiving a configuration, fully or partially, from the network. In some examples, attributes may include location information and service type, and so on.

[0094] At 1404, the UE obtains attributes of interest from possibly various entities such as a positioning system, higher layers, and so on. For example, location information may be obtained from a GPS receiver while service type of interest may be obtained from a higher layer application.

[0095] At 1406, the UE selects resources from the resource pool(s) in association with its attributes of interest and their values. In some examples, the UE can identify a resource pool in a resource pool table maintained by the UE (e.g., table 900 of FIG. 9) that is associated with the attributes and values as obtained at 1404, and selects resource(s) from the identified resource pool.

[0096] At 1408, the UE transmits discovery signals on the selected resources.

The UE may select different resources for different transmissions of discovery signals. Also, at any point in time where the resource pool configurations, the attributes of interest or their values may change, the UE may need to select different resource pools for transmission of discovery signals.

[0097] FIG. 15 illustrates a flowchart of an example method 1500 for receiving discovery signals by a UE through a generalized attribute-based method. At 1502, the UE obtains configurations of resource pool(s) for discovery signals and associations of the resource pool(s) with one or multiple attributes. The obtaining of the configuration may comprise a preconfiguration by the network or by the standard and/or receiving a configuration, fully or partially, from the network.

[0098] At 1504, the UE obtains attributes of interest from possibly various entities such as a positioning system, higher layers, and so on.

[0099] At 1506, the UE listens to the resource pool(s) in association with the attributes. At any point in time where the resource pool configurations, the attributes of interest or their values may change, the UE may need to select different resource pools to receive discovery signals.

[00100] In embodiments of the present disclosure, obtaining location information by a UE may normally require a positioning system on the UE such as a receiver for a global navigation satellite system (GNSS), e.g., the global positioning system (GPS). While it is expected that a wide range of UEs such as vehicle UEs will be equipped with GPS receivers, devising alternative means may provide advantages in situations where a positioning system is not available or positioning accuracy is not sufficient. Therefore, examples are provided in the present disclosure under the terms proximity information and proximity-based methods as alternatives to location information and location-based methods. Those terms are explained in the following.

[00101] In some embodiments, proximity information may comprise: information on identity or the number of devices in the vicinity, e.g., obtained through detectable signals received from the devices; information on interference in the vicinity, e.g., obtained through detectable and undetectable signals received from other devices; information on signal levels from devices in the vicinity, e.g., in terms of reference signal received power (RSRP) measured on signals received from those devices; and information on directions from which signals are received from devices in the vicinity, e.g., obtained through applying analog receive beams. Information on the transmission counterpart of the above, e.g., obtained through feedback from devices in the vicinity.

[00102] FIG. 16 illustrates an example of when negative-acknowledgement (NACK) messages may be sent in relation to the receipt or transmission of discovery messages. In some instances, a method for transmitting discovery signals for vehicle- to-every thing (V2X) communications may include obtaining resource configurations, wherein data communication resources and discovery resources are frequency-division multiplexed (FDM), wherein control resources and the discovery resources are time- division multiplexed (TDM). As shown, the data communication resource pools 1606 and 1608 can be multiplexed with the discovery resource pools 1602 and 1604 in the time domain. The control resource pool 1612 (e.g., control channel) can be multiplexed with the discovery resource pools 1602 and 1604 in the frequency domain. In some instances, the discovery resources are configured as at least one resource pool, and the at least one resource pool is partitioned into sub-resource pools according to at least one attribute. In this example, the discovery resource pools 1602 and 1604 can be considered as sub-resource pools of a larger resource pool that includes the discovery resource pools 1602, 1604, and any other discovery resource pools. At least one of the sub-resource pools (e.g., discovery resource pools 1602 or 1604) may be selected for transmitting or receiving at least one discovery message as described herein. In this example, the discovery message 1610 is transmitted on the discovery resource pool 1602. In some instances, a negative-acknowledgement (NACK) can be transmitted for communications that are simultaneous or concurrent with the at least one discovery message. In a first example, a NACK is sent only in response to communications that occur specifically during the transmission of the at least one discovery message. In this example, as shown, the NACK can be sent in response to communications that are transmitted or received on the data communication resource l606b that overlaps the transmission of the discovery message 1610 in time. In a second example, the NACK can be sent for any communication received simultaneous to a resource pool or sub resource pool in which the discovery message is transmitted. In this example, the NACK can be sent for any communications that are transmitted or received on any of the three data communication resources l606a, l606b, or l606c of the data communication resource pool 1606 which overlaps the discovery resource pool 1602 in which the discovery message 1610 is transmitted.

[00103] Embodiments in the present disclosure are described for communication between different types of entities. The term“network” may refer to a communication network communicating with subscriber devices through a gNodeB (gNB), a base station (BS), a transmission-reception point (TRP), an access point (AP), a relay node (RN), a network controller for a macro-cell or micro-cell or femto-cell or pico-cell, and so forth. The terms user equipment (UE) and vehicle UE may refer to a subscriber device such as a communication system on a vehicle, a mobile phone, and so forth. The term communication node or simply a“node” may refer to any communication entity controlled by a network or a subscriber.

[00104] Embodiments in the present disclosure may use signaling on different channels including control channels, shared/data channels, and discovery channels. It should be noted that despite emphasis on transmitting control signals on control channels, data signals on shared channels, and discovery signals on discovery channels, other variations such as transmitting control signals on shared channels are not precluded. The terms “discovery signal” and“discovery message” may be used interchangeably herein. Systems and methods described in the present disclosure may use signaling at different layers including Layer 1 or the physical layer, Layer 2 or the data link layer comprising a medium access control (MAC) sub-layer, and Layer 3 or the radio resource control (RRC) layer, which may be used for communicating UE capabilities, configurations, and so forth. Each signaling such as a configuration of signals and resources may be communicated through one or multiple channels and/or layers in a combination.

[00105] Embodiments in the present disclosure may be implemented on a variety of devices and communication entities. They may be implemented to operate on one or multiple frequency bands, component carriers (CCs), bandwidth parts (BWPs), and so forth. Communications may be on one or multiple numerologies including the subcarrier spacing and symbol duration in an air interface that is based on orthogonal frequency-division multiplexing / multiple-access (OFDM/OFDMA).

[00106] Embodiments of the present disclosure, including embodiments comprising more than one embodiment described herein, may require nodes to support a specific feature that may be mandatory or optional by a standard. A feature supported by a node such as a UE may be communicated, e.g., via RRC signaling, at the time of connection to the network, prior to or during communication with other devices, in response to a request from the network or from another node, and so forth.

[00107] Implementations of the subject matter and the functional operations described in this specification can be implemented in digital electronic circuitry, in tangibly embodied computer software or firmware, in computer hardware, including the structures disclosed in this specification and their structural equivalents, or in combinations of one or more of them. Implementations of the subject matter described in this specification can be implemented as one or more computer programs, that is, one or more modules of computer program instructions encoded on a tangible, non-transitory, computer-readable computer-storage medium for execution by, or to control the operation of, data processing apparatus. Alternatively, or additionally, the program instructions can be encoded in/on an artificially generated propagated signal, for example, a machine-generated electrical, optical, or electromagnetic signal that is generated to encode information for transmission to suitable receiver apparatus for execution by a data processing apparatus. The computer-storage medium can be a machine-readable storage device, a machine-readable storage substrate, a random or serial access memory device, or a combination of computer-storage mediums.

[00108] The terms “data processing apparatus,” “computer,” or“electronic computer device” (or equivalent as understood by one of ordinary skill in the art) refer to data processing hardware and encompass all kinds of apparatus, devices, and machines for processing data, including by way of example, a programmable processor, a computer, or multiple processors or computers. The apparatus can also be or further include special purpose logic circuitry, for example, a central processing unit (CPU), an FPGA (field programmable gate array), or an ASIC (application-specific integrated circuit). In some implementations, the data processing apparatus or special purpose logic circuitry (or a combination of the data processing apparatus or special purpose logic circuitry) may be hardware- or software-based (or a combination of both hardware- and software-based). The apparatus can optionally include code that creates an execution environment for computer programs, for example, code that constitutes processor firmware, a protocol stack, a database management system, an operating system, or a combination of execution environments. The present disclosure contemplates the use of data processing apparatuses with or without conventional operating systems, for example LINUX, UNIX, WINDOWS, MAC OS, ANDROID, IOS, or any other suitable conventional operating system.

[00109] A computer program, which may also be referred to or described as a program, software, a software application, a module, a software module, a script, or code can be written in any form of programming language, including compiled or interpreted languages, or declarative or procedural languages, and it can be deployed in any form, including as a stand-alone program or as a module, component, subroutine, or other unit suitable for use in a computing environment. A computer program may, but need not, correspond to a file in a file system. A program can be stored in a portion of a file that holds other programs or data, for example, one or more scripts stored in a markup language document, in a single file dedicated to the program in question, or in multiple coordinated files, for example, files that store one or more modules, sub-programs, or portions of code. A computer program can be deployed to be executed on one computer or on multiple computers that are located at one site or distributed across multiple sites and interconnected by a communication network. While portions of the programs illustrated in the various figures are shown as individual modules that implement the various features and functionality through various objects, methods, or other processes, the programs may instead include a number of sub- modules, third-party services, components, libraries, and such, as appropriate. Conversely, the features and functionality of various components can be combined into single components, as appropriate. Thresholds used to make computational determinations can be statically, dynamically, or both statically and dynamically determined.

[00110] The methods, processes, or logic flows described in this specification can be performed by one or more programmable computers that execute one or more computer programs to perform functions by operating on input data and generating output. The methods, processes, or logic flows can also be performed by, and apparatus can also be implemented as, special purpose logic circuitry, for example, a CPU, an FPGA, or an ASIC.

[00111] Computers suitable for the execution of a computer program can be based on general or special purpose microprocessors, both, or any other kind of CPU. Generally, a CPU will receive instructions and data from a read-only memory (ROM) or a random access memory (RAM), or both. The elements of a computer include a CPU, for performing or that execute instructions, and one or more memory devices for storing instructions and data. Generally, a computer will also include, or be operatively coupled to, receive data from or transfer data to, or both, one or more mass storage devices for storing data, for example, magnetic, magneto-optical disks, or optical disks. However, a computer need not have such devices. Moreover, a computer can be embedded in another device, for example, a mobile telephone, a personal digital assistant (PDA), a mobile audio or video player, a game console, a global positioning system (GPS) receiver, or a portable storage device, for example, a universal serial bus (USB) flash drive, to name just a few.

[00112] Computer-readable media (transitory or non-transitory, as appropriate) suitable for storing computer program instructions and data includes all forms of non-volatile memory, media, and memory devices, including by way of example semiconductor memory devices, for example, erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), and flash memory devices; magnetic disks, for example, internal hard disks or removable disks; magneto-optical disks; and CD-ROM, DVD+/-R, DVD- RAM, and DVD-ROM disks. The memory may store various objects or data, including caches, classes, frameworks, applications, backup data, jobs, web pages, web page templates, database tables, repositories storing dynamic information, and any other appropriate information including any parameters, variables, algorithms, instructions, rules, constraints, or references thereto. Additionally, the memory may include any other appropriate data, such as logs, policies, security or access data, reporting files, as well as others. The processor and the memory can be supplemented by, or incorporated in, special purpose logic circuitry.

[00113] To provide for interaction with a user, implementations of the subject matter described in this specification can be implemented on a computer having a display device, for example, a CRT (cathode ray tube), LCD (liquid crystal display), LED (Light Emitting Diode), or plasma monitor, for displaying information to the user and a keyboard and a pointing device, for example, a mouse, trackball, or trackpad by which the user can provide input to the computer. Input may also be provided to the computer using a touchscreen, such as a tablet computer surface with pressure sensitivity, a multi-touch screen using capacitive or electric sensing, or other type of touchscreen. Other kinds of devices can be used to provide for interaction with a user as well; for example, feedback provided to the user can be any form of sensory feedback, for example, visual feedback, auditory feedback, or tactile feedback; and input from the user can be received in any form, including acoustic, speech, or tactile input. In addition, a computer can interact with a user by sending documents to and receiving documents from a device that is used by the user; for example, by sending web pages to a web browser on a user’s client device in response to requests received from the web browser.

[00114] The term“graphical user interface,” or“GUI,” may be used in the singular or the plural to describe one or more graphical user interfaces and each of the displays of a particular graphical user interface. Therefore, a GUI may represent any graphical user interface, including but not limited to, a web browser, a touch screen, or a command line interface (CLI) that processes information and efficiently presents the information results to the user. In general, a GUI may include a number of user interface (UI) elements, some or all associated with a web browser, such as interactive fields, pull-down lists, and buttons. These and other UI elements may be related to or represent the functions of the web browser.

[00115] Implementations of the subj ect matter described in this specification can be implemented in a computing system that includes a back-end component, for example, as a data server, or that includes a middleware component, for example, an application server, or that includes a front-end component, for example, a client computer having a graphical user interface or a Web browser through which a user can interact with an implementation of the subject matter described in this specification, or any combination of one or more such back-end, middleware, or front-end components. The components of the system can be interconnected by any form or medium of wireline or wireless digital data communication (or a combination of data communication), for example, a communication network. Examples of communication networks include a local area network (LAN), a radio access network (RAN), a metropolitan area network (MAN), a wide area network (WAN), Worldwide Interoperability for Microwave Access (WIMAX), a wireless local area network (WLAN) using, for example, 802.11 a/b/g/n or 802.20 (or a combination of 802.1 lx and 802.20 or other protocols consistent with this disclosure), all or a portion of the Internet, or any other communication system or systems at one or more locations (or a combination of communication networks). The network may communicate with, for example, Internet Protocol (IP) packets, Frame Relay frames, Asynchronous Transfer Mode (ATM) cells, voice, video, data, or other suitable information (or a combination of communication types) between network addresses.

[00116] The computing system can include clients and servers. A client and server are generally remote from each other and typically interact through a communication network. The relationship of client and server arises by virtue of computer programs running on the respective computers and having a client-server relationship to each other.

[00117] While this specification contains many specific implementation details, these should not be construed as limitations on the scope of any solution or on the scope of what may be claimed, but rather as descriptions of features that may be specific to particular implementations of particular solutions. Certain features that are described in this specification in the context of separate implementations can also be implemented, in combination, in a single implementation. Conversely, various features that are described in the context of a single implementation can also be implemented in multiple implementations, separately, or in any suitable sub-combination. Moreover, although previously described features may be described as acting in certain combinations and even initially claimed as such, one or more features from a claimed combination can, in some cases, be excised from the combination, and the claimed combination may be directed to a sub-combination or variation of a sub-combination. [00118] Particular implementations of the subject matter have been described. Other implementations, alterations, and permutations of the described implementations are within the scope of the following claims as will be apparent to those skilled in the art. While operations are depicted in the drawings or claims in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed (some operations may be considered optional), to achieve desirable results. In certain circumstances, multitasking or parallel processing (or a combination of multitasking and parallel processing) may be advantageous and performed as deemed appropriate.

[00119] Moreover, the separation or integration of various system modules and components in the previously described implementations should not be understood as requiring such separation or integration in all implementations, and it should be understood that the described program components and systems can generally be integrated together in a single software product or packaged into multiple software products.

[00120] Accordingly, the previously described example implementations do not define or constrain this disclosure. Other changes, substitutions, and alterations are also possible without departing from the spirit and scope of this disclosure.

[00121] Furthermore, any claimed implementation is considered to be applicable to at least a computer-implemented method; a non-transitory, computer-readable medium storing computer-readable instructions to perform the computer-implemented method; and a computer system including a computer memory interoperably coupled with a hardware processor configured to perform the computer-implemented method or the instructions stored on the non-transitory, computer-readable medium.

Claims

CLAIMS What is claimed is:

1. A method for transmitting discovery signals for vehicle-to-everything (V2X) communications, the method comprising:

obtaining resource configurations, wherein data communication resources and discovery resources of the resource configuration are frequency-division multiplexed (FDM’ed), wherein control resources and the discovery resources of the resource configuration are time-division multiplexed (TDM’ed), wherein the discovery resources are configured as at least one resource pool, and wherein the at least one resource pool is partitioned into sub-resource pools according to at least one attribute; selecting at least one of the sub-resource pools based on the at least one attribute;

transmitting at least one discovery message on the at least one of the sub resource pools; and

transmitting a negative-acknowledgement (NACK) for any communication that is simultaneous with the at least one discovery message.

2. The method of claim 1, further comprising transmitting a negative- acknowledgement (NACK) for any communication that is simultaneous with the at least one of the sub-resource pools.

3. The method of claim 1 , wherein the resource configuration is obtained from one of a radio resource control (RRC) message, a medium access control (MAC) message, or a control message from a physical layer.

4. The method of claim 1, wherein the attributes comprise at least one of services requested, services offered, location information, or proximity information.

5. The method of claim 4, wherein the attributes further comprise a direction of velocity information.

6. The method of claim 1, wherein the discovery message is one of a sequence- type signal, a message-type signal, or a combination thereof.

7. A method for transmitting discovery signals for vehicle-to-everything (V2X) communications, the method comprising:

obtaining resource configurations, wherein data communication resources and discovery resources are frequency-division multiplexed (FDM’ed), and wherein control resources and the discovery resources are time-division multiplexed (TDM’ed); and determining at least one subset of the discovery resources for a discovery communication.

8. The method of claim 7, wherein the discovery communication is one of a transmission or reception.

9. The method of claim 7, wherein the resource configurations comprise an association between the at least one subset of the discovery resources and at least one attribute.

10. The method of claim 9, wherein the discovery resources are configured as at least one resource pool, wherein the association comprises a partitioning of the at least one resource pool into at least one sub-resource pool based on the at least one attribute, and wherein the determining the at least one subset of the discovery resources comprises selecting at least one sub-resource pool based on at least a value of the at least one attribute.

11. The method of claim 10, wherein the value of the at least one attribute comprises at lesat one of a location estimation from a global positioniing satellite system, a velocity value, or a service type from a higher level.

12. The method of claim 10, further comprising:

selecting at least one subset of the at least one sub-resource pool;

transmitting at least one discovery message on the selected at least one subset of the at least one sub-resource pool; and refraining from at least one data communication that is simultaneous with the the selected at least one subset of the at least one sub-resource pool.

13. The method of claim 12, wherein seleting the at least one subset of the at least one sub-resourc pool is based on at least one of a quality of service (QoS) and a priority value.

14. The method of claim 12, further comprising:

transmitting at least one negative-acknowledgement (NACK) in association with the at least one data communication.

15. A user equipment, the user equipment comprising:

at least one processor;

a memory storing instructions executable by the at least one processor, wherein the instructions, when executed by the at least one processor, instruct the processor to perform the following operations:

obtaining resource configurations, wherein data communication resources and discovery resources of the resource configuration are frequency-division multiplexed (FDM’ed), wherein control resources and the discovery resources of the resource configuration are time-division multiplexed (TDM’ed), wherein the discovery resources are configured as at least one resource pool, and wherein the at least one resource pool is partitioned into sub-resource pools according to at least one attribute;

selecting at least one of the sub-resource pools based on the at least one attribute;

transmitting at least one discovery message on the at least one of the sub-resource pools; and

transmitting a negative-acknowledgement (NACK) for any communication that is simultaneous with the at least one discovery message.

16. The user equipment of claim 15, wherein the operations further comprise transmitting a negative-acknowledgement (NACK) for any communication that is simultaneous with the at least one of the sub-resource pools.

17. A user equipment, the user equipment comprising:

at least one processor;

a memory storing instructions executable by the at least one processor, wherein the instructions, when executed by the at least one processor, instruct the processor to perform the following operations:

obtaining resource configurations, wherein data communication resources and discovery resources are frequency-division multiplexed (FDM’ed), and wherein control resources and the discovery resources are time-division multiplexed (TDM’ed); and

determining at least one subset of the discovery resources for a discovery communication.

18. The user equipment of claim 17, wherein the resource configurations comprise an association between the at least one subset of the discovery resources and at least one attribute.

19. The user equipment of claim 18, wherein the discovery resources are configured as at least one resource pool, wherein the association comprises a partitioning of the at least one resource pool into at least one sub-resource pool based on the at least one attribute, and wherein the determining at least one subset of the discovery resources comprises selecting at least one sub-resource pool based on at least a value of the at least one attribute.

20. The user equipment of claim 19, wherein the operations further comprise: selecting at least one subset of the at least one sub-resource pool;

transmitting at least one discovery message on the selected at least one subset of the at least one sub-resource pool; and

refraining from at least one data communication that is simultaneous with the the selected at least one subset of the at least one sub-resource pool.