Autonomous Resource Selection for Multiple Transmissions in Device-to-Device Communication

Abstract

A user equipment (UE) may communicate with one or more other UEs using multiple transmissions in a device-to-device (D2D) communication deployment. Multiple UEs may be configured with D2D resources, and a transmitting UE may identify available D2D resources from the configured resources. The transmitting UE may identify a resource for a first transmission of the D2D transmission from the available D2D resources, and may identify a second resource for a second transmission of the D2D transmission. The second transmission may be a blind HARQ transmission, which may be sent to enhance the likelihood that one or more receiving UEs successfully receive the transmission. In some examples, the second resource may be identified based on other available resources within a predetermined time window near the first transmission.

Description

[0001] This application is a divisional application of the application with the application date of August 18, 2017, application number 201780051740.X, and title "Autonomous Resource Selection for Multiple Transmissions in Device-to-Device Communications".

[0002] Cross References

[0003] This patent application claims the benefit of U.S. Patent Application No. 15 / 680,014, entitled "Autonomous Resource Selection For Multiple Transmissions In Device-To-Device Communications", filed by Gulati et al. on August 17, 2017, and U.S. Provisional Patent Application No. 62 / 379,726, entitled "Autonomous Resource Selection For Multiple Transmissions In Device-To-Device Communications", filed by Gulati et al. on August 25, 2016; each of which is assigned to the assignee hereof. Technical Field

[0004] The following generally relates to wireless communications and, more specifically, to autonomous resource selection for multiple transmissions in device-to-device (D2D) communications. Background Art

[0005] Wireless communication systems are widely deployed to provide various types of communication content, such as voice, video, packet data, messaging, broadcasts, etc. These systems can support communication with multiple users by sharing available system resources (e.g., time, frequency, and power). Examples of such multi-access systems include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, and orthogonal frequency division multiple access (OFDMA) systems.

[0006] These multiple access technologies have been adopted in various telecommunication standards to provide a common protocol that enables different wireless devices to communicate at the municipal, national, regional, or even global levels. An example telecommunication standard is Long Term Evolution (LTE). LTE is designed to improve spectral efficiency, reduce costs, enhance services, utilize new spectrum, and better integrate with other open standards. LTE can use Orthogonal Frequency Division Multiple Access (OFDMA) on the downlink (DL), Single-Carrier Frequency Division Multiple Access (SC-FDMA) on the uplink (UL), and Multiple-Input Multiple-Output (MIMO) antenna technology. A wireless multiple access communication system (including an LTE system) can include multiple base stations, each of which supports the communication of multiple communication devices, which may alternatively be referred to as user equipment (UE).

[0007] Some wireless systems can support Device-to-Device (D2D) communication, which can enable UEs to communicate directly with each other without an intermediate connection to a central node such as a base station. In some cases, UEs can send control and data transmissions to each other. In some cases, a UE can send to multiple other UEs, such as a UE associated with vehicle control, which can send information to multiple other vehicles that may be within a relatively close range. SUMMARY

[0008] A user equipment (UE) can use multiple transmissions to communicate with one or more other UEs in a Device-to-Device (D2D) communication deployment. Multiple UEs can be configured with D2D resources, and a transmitting UE can identify available D2D resources from the configured resources (e.g., based on scheduling assignment (SA) information of one or more other UEs). The transmitting UE can identify a resource for a first transmission of the D2D transmission from the available D2D resources and can identify a second resource for a second transmission of the D2D transmission. The second transmission can be, for example, a blind hybrid automatic repeat request (HARQ) transmission, which can be sent to enhance the likelihood that one or more receiving UEs successfully receive the transmission. In some examples, the second resource can be identified based on other available resources within a predetermined time window near the first transmission.

[0009] A wireless communication method is described. The method can include: identifying a set of candidate resources for sending a D2D transmission within a set of available resources, selecting a first resource within the set of candidate resources for sending a first transmission of the D2D transmission, determining a subset of the set of available resources for sending a second transmission of the D2D transmission, selecting a second resource within the subset of the set of available resources for sending the second transmission, using the first resource to send the first transmission, and using the second resource to send the second transmission.

[0010] A device for wireless communication is described. The device may include a unit for identifying a set of candidate resources for sending a D2D transmission within a set of available resources, a unit for selecting a first resource within the set of candidate resources for sending a first transmission for the D2D transmission, a unit for determining a subset of the set of available resources for sending a second transmission for the D2D transmission, a unit for selecting a second resource within the subset of the set of available resources for sending the second transmission, a unit for sending the first transmission using the first resource, and a unit for sending the second transmission using the second resource.

[0011] Another device for wireless communication is described. The device may include a processor, a memory in electronic communication with the processor, and instructions stored in the memory. The instructions may be operable to cause the processor to perform the following operations: identify a set of candidate resources for sending a D2D transmission within a set of available resources, select a first resource within the set of candidate resources for sending a first transmission for the D2D transmission, determine a subset of the set of available resources for sending a second transmission for the D2D transmission, select a second resource within the subset of the set of available resources for sending the second transmission, send the first transmission using the first resource, and send the second transmission using the second resource.

[0012] A non-transitory computer-readable medium for wireless communication is described. The non-transitory computer-readable medium may include instructions operable to cause a processor to perform the following operations: identify a set of candidate resources for sending a D2D transmission within a set of available resources, select a first resource within the set of candidate resources for sending a first transmission for the D2D transmission, determine a subset of the set of available resources for sending a second transmission for the D2D transmission, select a second resource within the subset of the set of available resources for sending the second transmission, send the first transmission using the first resource, and send the second transmission using the second resource.

[0013] In some examples of the above methods, devices, and non-transitory computer-readable media, determining the subset of the set of available resources includes determining the remaining resources in the set of candidate resources at least partially based on removing the first resource from the set of candidate resources.

[0014] In some examples of the above methods, apparatuses, and non-transitory computer-readable media, the determining of the subset of the available resource set further includes identifying a first time for transmitting the first transmission. Some examples of the above methods, apparatuses, and non-transitory computer-readable media may further include a process, feature, unit, or instruction for identifying a time window near the first time. Some examples of the above methods, apparatuses, and non-transitory computer-readable media may further include a process, feature, unit, or instruction for determining the subset of the available resource set as the remaining resources within the time window. In some examples of the above methods, apparatuses, and non-transitory computer-readable media, the selecting of the second resource includes randomly selecting the second resource from the subset of the available resource set.

[0015] In some examples of the above methods, apparatuses, and non-transitory computer-readable media, the time window may be configured by a base station. In some examples of the above methods, apparatuses, and non-transitory computer-readable media, the time window includes a predetermined fixed time window.

[0016] Some examples of the above methods, apparatuses, and non-transitory computer-readable media may further include a process, feature, unit, or instruction for determining that the subset of the available resource set for transmitting the second transmission may be empty. Some examples of the above methods, apparatuses, and non-transitory computer-readable media may further include a process, feature, unit, or instruction for skipping the selecting of the second resource and transmitting the second transmission.

[0017] Some examples of the above methods, apparatuses, and non-transitory computer-readable media may further include a process, feature, unit, or instruction for determining that the subset of the available resource set for transmitting the second transmission may be empty. Some examples of the above methods, apparatuses, and non-transitory computer-readable media may further include a process, feature, unit, or instruction for modifying the candidate resource set to include additional resources from the available resource set such that the subset of the available resource set may be non-empty.

[0018] In some examples of the above methods, apparatuses, and non-transitory computer-readable media, the candidate resource set may be identified as resources in the available resource set having a received energy that may be below a threshold, and wherein the modifying includes increasing the threshold until the subset of the available resource set may be non-empty.

[0019] In some examples of the above methods, apparatuses, and non-transitory computer-readable media, the first resource may be randomly selected from the candidate resource set.

[0020] In some examples of the above methods, apparatuses, and non-transitory computer-readable media, the D2D transmission includes sidelink transmission between two D2D UE devices, and wherein the set of available resources may be Physical Sidelink Shared Channel (PSSCH) resources.

[0021] In some examples of the above methods, apparatuses, and non-transitory computer-readable media, the set of available resources includes a subset of the set of configured resources that is available for D2D transmission and may be identified at least in part based on one or more SAs associated with one or more D2D transmitters.

[0022] The features and technical advantages of examples in accordance with the present disclosure have been outlined rather broadly above so that the following detailed description may be better understood. Additional features and advantages will be described hereinafter. The disclosed concepts and specific examples may be readily used as a basis for modifying or designing other structures for carrying out the same purposes of the present disclosure. Such equivalent structures do not depart from the scope of the appended claims. When considered in conjunction with the accompanying drawings, the features (both their organization and method of operation) of the concepts disclosed herein, as well as the associated advantages, will be better understood from the following description. Each of the drawings is provided for the purpose of illustration and description and is not to be construed as a definition of the limits of the claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] A further understanding of the nature and advantages of the present disclosure may be realized by reference to the following drawings. In the drawings, like components or functions may have the same reference numerals. Additionally, various components of the same type may be distinguished by following the reference numeral with a dash and a second reference numeral that differentiates the similar components. If only the first reference numeral is used in the specification, the description applies to any one of the similar components having the same first reference numeral regardless of the second reference numeral.

[0024] Figure 1 An example of a system for wireless communication in accordance with various aspects of the present disclosure is shown that supports autonomous resource selection for multiple transmissions in D2D communication.

[0025] Figure 2 An example of a wireless communication system in accordance with various aspects of the present disclosure is shown that supports autonomous resource selection for multiple transmissions in D2D communication.

[0026] Figure 3 An example of wireless resources in accordance with various aspects of the present disclosure is shown that supports autonomous resource selection for multiple transmissions in D2D communication.

[0027] Figure 4An example of a processing procedure flow supporting autonomous resource selection for multiple transmissions in D2D communication in accordance with various aspects of the present disclosure is shown.

[0028] Figures 5 to 7 A block diagram of a device supporting autonomous resource selection for multiple transmissions in D2D communication in accordance with various aspects of the present disclosure is shown.

[0029] Figure 8 A block diagram of a system including a UE supporting autonomous resource selection for multiple transmissions in D2D communication in accordance with various aspects of the present disclosure is shown.

[0030] Figures 9 to 11 A method for autonomous resource selection for multiple transmissions in D2D communication in accordance with various aspects of the present disclosure is shown. Detailed Description

[0031] Some wireless systems may support device-to-device (D2D) communication between devices, which may enable user equipment (UEs) to communicate directly with each other without an intermediate connection to a central device such as a base station. The system may support D2D communication by, for example, adopting a pattern known or recognized by the devices within the system. In D2D, one UE may be referred to as the transmitting UE, and another UE may be referred to as the receiving UE. In some cases, the D2D structure for communication between UEs may include control information signaled by the base station. For example, the transmitting UE may receive downlink control information (DCI) from the base station, and the DCI may include control information - including a configured resource set for D2D devices to use for D2D communication - that supports D2D communication with the receiving UE. The transmitting UE may send sidelink control information (SCI) to the receiving UE configured by a higher layer to monitor for this information. After configuring data transmission, the transmitting UE may use the physical sidelink shared channel (PSSCH) for transmission. The resource block allocation may be from the original DCI format grant and may be replicated in the SCI format grant from the transmitting UE. The receiving UE may configure the PSSCH based on the receipt of the SCI.

[0032] In some cases, it may be desirable for D2D communication to have relatively high reliability such that any receiving UE is highly likely to successfully receive and decode a D2D transmission from a transmitting UE. In many traditional systems, a Hybrid Automatic Repeat reQuest (HARQ) process can provide relatively high reliability, and the receiving UE can provide acknowledgement feedback to the transmitting UE to indicate successful reception of the transmission. If the transmission is not successfully received, the transmitting UE can retransmit the transmission. Aspects of the present disclosure provide that a transmitting UE can send a blind HARQ transmission, where a D2D transmission can be retransmitted without receiving a negative acknowledgement of the original transmission. Such a blind HARQ transmission can provide an increased likelihood that the receiving UE will successfully receive the transmission.

[0033] In some examples, a UE of a D2D system can autonomously select resources for a D2D transmission, such as for Physical Sidelink Shared Channel (PSSCH) transmission. Multiple UEs can be configured with D2D resources by a serving base station. One or more UEs can send Scheduling Assignment (SA) information that indicates the resources among the configured resources that are being used for D2D transmission. The transmitting UE can identify available D2D resources for sending a D2D transmission based on the configured resources and the SA information of one or more other UEs. The transmitting UE can identify a resource for a first transmission of a D2D transmission from the available D2D resources, and can identify a second resource for a second transmission of the D2D transmission. The second transmission can be, for example, a blind HARQ transmission that can be sent to enhance the likelihood that one or more receiving UEs successfully receive the transmission. In some examples, the second resource can be identified based on other available resources within a predetermined time window near the first transmission. In some cases, the transmitting UE can identify a candidate resource set within a set of available resources, which can be identified based on, for example, ranking the available resources based on total received energy (e.g., to reduce potential interference to other transmitting UEs). In some cases, a resource for the blind HARQ transmission can be randomly selected from any remaining resources in the candidate resource set (e.g., the remaining resources within the candidate set trimmed based on the time window).

[0034] In some cases, the transmitting UE can determine that there are no remaining resources in the candidate resource set, and the blind HARQ transmission can be skipped, or alternative resources can be identified for the blind HARQ transmission. In some examples, the alternative resources can be determined by randomly selecting the remaining resources among the available D2D resources. In other examples, the alternative resources can be determined by modifying the candidate resource set until a resource is available for the blind HARQ transmission (e.g., by modifying the received energy threshold of the candidate resource set).

[0035] Aspects of the present disclosure discussed above are further described below in the context of a wireless communication system. Specific examples for resource selection for D2D transmissions and blind HARQ transmissions are then described. These and other aspects of the present disclosure are further illustrated and described with reference to apparatus diagrams, system diagrams, and flowcharts related to low-latency D2D communication.

[0036] Figure 1 An example of a wireless communication system in accordance with aspects of the present disclosure is shown. The wireless communication system 100 includes a base station 105, a UE 115, and a core network 130. In some examples, the wireless communication system 100 may be a Long Term Evolution (LTE) / LTE-Advanced (LTE-A) network. The wireless communication system 100 may support D2D communication between one or more UEs 115. For example, the UE 115 may autonomously select resources for multiple D2D transmissions according to the techniques provided herein.

[0037] The base station 105 may communicate wirelessly with the UE 115 via one or more base station antennas. Each base station 105 may provide communication coverage for a corresponding geographic coverage area 110. The communication link 125 shown in the wireless communication system 100 may include an uplink (UL) transmission from the UE 115 to the base station 105, or a downlink (DL) transmission from the base station 105 to the UE 115. The UEs 115 may be dispersed throughout the wireless communication system 100, and each UE 115 may be fixed or mobile. The UE 115 may also be referred to as a mobile station, subscriber station, remote unit, wireless device, access terminal, cellular phone, user agent, client, or some other suitable term. The UE 115 may also be a cellular phone, wireless modem, handheld device, personal computer, tablet, personal electronic device, machine type communication (MTC) device, etc.

[0038] The base station 105 may communicate with the core network 130 and with each other. For example, the base station 105 may interface with the core network 130 via a backhaul link 132 (e.g., S1, etc.). The base stations 105 may communicate with each other directly or indirectly (e.g., via the core network 130) via a backhaul link 134 (e.g., X2, etc.). The base station 105 may perform radio configuration and scheduling for communication with the UE 115, or may operate under the control of a base station controller (not shown). In some examples, the base station 105 may be a macro cell, small cell, hot spot, etc. The base station 105 may also be referred to as an evolved Node B (eNB) 105.

[0039] A wireless communication link 126 can also be established between UEs 115 in a D2D communication configuration, which can be referred to as a sidelink. One or more UEs in a group of UEs 115 utilizing D2D communication can be within the geographical coverage area 110 of the cell. Other UEs 115 in such a group can be outside the coverage area 110 of the cell or cannot receive transmissions from the base station 105. In some cases, a group of UEs 115 communicating via D2D communication can use a one-to-many (1:M) system, where each UE 115 transmits to each other UE 115 in the group. In some cases, the base station 105 facilitates the scheduling of resources for D2D communication. In other cases, autonomous resource selection is used to perform D2D communication independently of the base station 105.

[0040] As described above, in some cases, the UE 115 can autonomously select resources for D2D transmission. In such cases, the transmitting UE 115 can identify available D2D resources for sending a D2D transmission based on, for example, configured D2D resources (e.g., resources configured by the base station 105 for D2D transmission) and SA information of one or more other UEs 115. In some examples, the UE 115 can identify a first resource for sending a D2D transmission and can identify a second resource for sending a blind HARQ transmission for the D2D transmission. Aspects of the present disclosure provide techniques for identifying and selecting resources to be used for multiple D2D transmissions such as a first D2D transmission and an associated blind HARQ transmission.

[0041] Figure 2 An example of a wireless communication system 200 for autonomous resource selection for multiple transmissions in D2D communication in accordance with aspects of the present disclosure is shown. The wireless communication system 200 can include a UE 115-a and a base station 105-a, which can be examples of the UE 115 and the base station 105 described with reference to Figure 1 The wireless communication system 200 can support D2D communication and peer-to-peer communication between the UE 115-a and the UE 115-b. The UE 115-a can be referred to as the transmitting UE, and the UE 115-b can be referred to as the receiving UE. The UE 115-a can be coupled to the base station 105-a via a communication link 125-a. In some cases, the UE 115-b can communicate with the base station 105-a via a communication link 125-b. The UE 115-a can be configured to perform D2D communication with the UE 115-b via a sidelink 205. In some cases, the UE 115-b can send to the UE 115-a via a sidelink 210.

[0042] Establishing a D2D connection may include a discovery process and a synchronization process. For example, the discovery process includes configuration of the period of the discovery period or user timing, payload content and size adjustment, and the structure of the subframe-based Tx / Rx resource pool. In some examples, UE 115-a may receive DCI and may send a Physical SideLink Control Channel (PSCCH) transmission to UE 115-b. Information transmitted from base station 105-a and transmitted between UEs 115 using higher layer signaling may be used to configure resources for the PSCCH. The PSCCH payload may be sent by the transmitting UE 115-b based on autonomous resource selection. The PSCCH may contain SCI format payload content, which may not include a destination ID specifying the intended receiving UE, but may include, for example, frequency resource allocation, hopping enable flag, time allocation bitmask, modulation and coding scheme (MCS) and timing advance (e.g., UE 115 may be based on its uplink timing) and cyclic redundancy check (CRC) information. In some cases, the above information may be copied from the DCI format grant.

[0043] In some examples, UE 115 may perform autonomous selection of resources for D2D transmission. In some examples, UE 115 may autonomously select resources for PSSCH transmission. In some cases, all PSCCH / PSSCH transmissions may have the same priority, and all resources configured by base station 105-a may be considered available for D2D transmission. UE 115 may exclude some resources at least partially based on the SA of other UEs 115 and identify a set of available resources. In some examples, if the configured resources are indicated or reserved by the decoded SA and the received Demodulation Reference Signal (DMRS) power in the associated data resources is higher than a threshold, the configured resources may be excluded from the set of available resources. Then, the transmitting UE 115 may determine a set of candidate resources. In some examples, the set of candidate resources may be determined by measuring and ranking the available PSSCH resources based on the total received energy and selecting a subset based on a received energy threshold. Then, the transmitting UE 115 may randomly select resources for D2D transmission from the set of candidate resources.

[0044] In the case where the transmitting UE 115 is to send a blind HARQ transmission for a D2D transmission, some examples provide that the UE 115 may randomly select a second resource from the remaining candidate resources that satisfy the time-domain constraint and are near (e.g., within + / -X milliseconds) the selected first D2D resource. In some examples, the transmitting UE 115 may proactively select the second resource by trimming a subset of the candidate resources to a smaller subset that includes resources occurring within X ms of the selected first resource. In some cases, the value of X may be configured in the communication standard. In some cases, the value of X may be set by the base station 105 to a predetermined value, such as + / -7 ms or + / -8 ms from the selected first resource. In the case where the trimmed subset is non-empty, the transmitting UE 115 may randomly select a second resource from the trimmed subset and use the second resource for sending the blind HARQ transmission. In the case where the trimmed subset is empty, the transmitting UE 115 may send a first transmission on the first resource without sending a blind HARQ retransmission. Alternatively, in the case where the trimmed subset is empty, the transmitting UE may randomly select a second resource within X ms of the selected first resource from the original set of available resources. In other examples, the transmitting UE may increase the size of the set of candidate resources to a larger subset (e.g., by increasing the value of the received energy threshold) until a non-empty subset is obtained, and the second resource may be randomly selected from the now non-empty subset.

[0045] Figure 3 An example of a D2D resource 300 for autonomous resource selection for multiple transmissions in D2D communication in accordance with various aspects of the present disclosure is shown. As described above, such as Figures 1 - 2The UE of UE 115 can autonomously select D2D resources for multiple D2D transmissions. In this example, a set 305 of configured resources can be configured for D2D transmissions. Available resource set 310 can be identified, for example, by identifying available resources that are not yet identified in the SA of one or more other UEs. As described above, candidate resource set 315 can include, for example, resources among the available resources that have received energy below a threshold. A first D2D transmission resource 325 can be selected from candidate resources 315. Candidate resources 315 can then be trimmed to obtain a subset 320 of trimmed candidate resources within a predetermined time window 325 of, for example, the selected D2D transmission resource 325. For example, a selected blind HARQ transmission resource 330 can be randomly selected from the trimmed candidate resources 320. Although this example shows the blind HARQ transmission resource 330 after the selected D2D transmission resource 325 in time, other examples can have the blind HARQ transmission resource 330 start before the selected D2D transmission resource 325 in time. Additionally, although the various resource subsets are shown to be contiguous in frequency and time, these resources can be non - contiguous in frequency, time, or both.

[0046] Figure 4 An example of a processing procedure flow 400 for autonomous resource selection for multiple transmissions in D2D communication in accordance with various aspects of the present disclosure is shown. Processing flow 400 can include UE 115 - c, UE 115 - d, and base station 105 - b, which can be examples of UE 115 and base station 105 as Figures 1 - 2 described. UE 115 - d can be referred to as the transmitting UE, and UE 115 - c can be referred to as the receiving UE. UE 115 - c and 115 - d can communicate directly via a sidelink configured for autonomous resource selection by UE 115. UE 115 - c can receive DCI from base station 105 - b and can then send an SA to UE 115 - d based on the received DCI. UE 115 - d can send multiple D2D transmissions to a plurality of other UEs including UE 115 - c.

[0047] At 405, UE 115-c, UE 115-d, and base station 105-b may initiate a D2D sidelink, and base station 105-b may configure a set of configured resources that may be used for autonomous resource selection by UE 115. Base station 105-b may send a sidelink initiation signal to UE 115-c and UE 115-d. In some examples, the sidelink initiation signal may indicate that the sidelink communication is a broadcast communication sent from transmitting UE 115 to multiple receiving UEs 115. In such a case, UE 115 may be configured to autonomously determine resources for D2D transmission. Base station 105-b may additionally or alternatively configure blind HARQ transmission for UE 115.

[0048] At 410, base station 105-b may send DCI to UE 115-c and UE 115-d. At 415, UE 115-c may send an SA to UE 115-d. According to block 420, UE 115-d may identify the SA and use the information therein to determine a set of available resources for D2D transmission.

[0049] At block 425, UE 115-d may identify a set of candidate resources, which may be based on resources in the set of available resources that meet a certain criterion (e.g., it has a received energy level below a threshold). Then, as shown at 430, UE 115-d may select a first resource from the set of candidate resources. Such a selection may be a random selection of a resource from the set of candidate resources.

[0050] At block 435, UE 115-d may determine a subset of the set of available resources to identify blind HARQ resources. Such a determination may be made based on, for example, the remaining resources in the set of candidate resources within a predetermined time period of the selected first resource.

[0051] At block 440, UE 115-d may select a second resource as a blind HARQ resource for a second transmission such as a blind HARQ transmission. The selection of the second resource may be, for example, a random selection of a resource from the subset of the set of available resources. Then, UE 115-d may use the first resource to send a D2D transmission 445, and may use the second resource to send a blind HARQ transmission 450. In some examples, the second resource may have a start time point that is later or earlier than that of the first resource.

[0052] Figure 5 Block diagram 500 shows a wireless device 505 that supports autonomous resource selection for multiple transmissions in D2D communication according to various aspects of the present disclosure. The wireless device 505 may be as referred to in Figure 1Examples of aspects of the UE 115 described. The wireless device 505 may include a receiver 510, a communication manager 515, and a transmitter 520. The wireless device 505 may also include a processor. Each of these components may communicate with each other (e.g., via one or more buses).

[0053] The receiver 510 may receive information such as packets, user data, or control information associated with various information channels (e.g., control channel information, data channel information, and information related to autonomous resource selection for multiple transmissions in D2D communication, etc.). The information may be passed to other components of the device. The receiver 510 may be an example of aspects of the transceiver 835 described with reference to Figure 8 the transceiver 835 described with reference to

[0054] The communication manager 515 may be an example of aspects of the communication manager 815 described with reference to Figure 8 the communication manager 815 described with reference to

[0055] The communication manager 515 may identify a set of candidate resources for sending a D2D transmission within a set of available resources, select a first resource within the set of candidate resources for sending a first transmission of the D2D transmission, determine a subset of the set of available resources for sending a second transmission of the D2D transmission, select a second resource within the subset of the set of available resources for sending the second transmission, send the first transmission using the first resource, and send the second transmission using the second resource.

[0056] The transmitter 520 may transmit signals generated by other components of the device. In some examples, the transmitter 520 may be collocated with the receiver 510 in a transceiver module. For example, the transmitter 520 may be an example of aspects of the transceiver 835 described with reference to Figure 8 the transceiver 835 described with reference to

[0057] Figure 6 Block diagram 600 of a wireless device 605 supporting autonomous resource selection for multiple transmissions in D2D communication in accordance with various aspects of the present disclosure is shown. The wireless device 605 may be an example of aspects of the wireless device 505 or UE 115 described with reference to Figure 1 and 5 the wireless device 505 or UE 115 described with reference to

[0058] The receiver 610 may receive information such as packets, user data, or control information associated with various information channels (e.g., control channel information, data channel information, and information related to autonomous resource selection for multiple transmissions in D2D communication, etc.). The information may be passed to other components of the device. The receiver 610 may be an example of aspects of the transceiver 835 described with reference to Figure 8 .

[0059] The communication manager 615 may be an example of aspects of the communication manager 815 described with reference to Figure 8 . The communication manager 615 may further include a candidate resource identification component 625, a D2D transmission resource selection component 630, a blind HARQ resource determination component 635, a HARQ transmission resource selection component 640, and a D2D transmission component 645.

[0060] The candidate resource identification component 625 may identify a set of candidate resources for sending a D2D transmission within a set of available resources. In some cases, if a subset of the available resources for sending a second transmission is empty, the candidate resource identification component 625 may modify the set of candidate resources to include additional resources from the set of available resources such that the subset within the set of available resources is non - empty. In some cases, the set of candidate resources is identified as resources in the set of available resources having a received energy below a threshold. In some cases, the modification includes: increasing the threshold until the subset within the set of available resources is non - empty. In some cases, the set of available resources includes a subset of the configured resources that are available for D2D transmission and is identified based on one or more SAs associated with one or more D2D transmitters.

[0061] The D2D transmission resource selection component 630 may select a first resource within the set of candidate resources for sending a first transmission of the D2D transmission. In certain cases, the first resource is randomly selected from the set of candidate resources.

[0062] The blind HARQ resource determination component 635 may determine a subset of the set of available resources for sending a second transmission of the D2D transmission. In some cases, the blind HARQ resource determination component 635 may determine that the subset of the set of available resources for sending the second transmission is empty and skip selecting a second resource and sending the second transmission. In some cases, the subset within the set of available resources is determined based on the remaining resources of the set of candidate resources after removing the first resource from the set of candidate resources.

[0063] The HARQ transmission resource selection component 640 may select a second resource within a subset of a set of available resources for transmitting a second transmission. In some cases, selecting the second resource includes randomly selecting the second resource from a subset of the set of available resources.

[0064] The D2D transmission component 645 may use the first resource to transmit a first transmission and use the second resource to transmit a second transmission.

[0065] The transmitter 620 may transmit signals generated by other components of the device. In some examples, the transmitter 620 may be collocated with the receiver 610 in a transceiver module. For example, the transmitter 620 may be an example of aspects of the transceiver 835 described with reference to Figure 8 The transmitter 620 may include a single antenna, or it may include a set of antennas.

[0066] Figure 7 FIG. 700 is a block diagram showing a communication manager 715 that supports autonomous resource selection for multiple transmissions in D2D communication in accordance with various aspects of the present disclosure. The communication manager 715 may be an example of aspects of the communication manager 515, the communication manager 615, or the communication manager 815 described with reference to Figure 5 , 6 and 8. The communication manager 715 may include a candidate resource identification component 720, a D2D transmission resource selection component 725, a blind HARQ resource determination component 730, a HARQ transmission resource selection component 735, a D2D transmission component 740, a time window identification component 745, and a D2D configuration component 750. Each of these modules may communicate directly or indirectly with each other (e.g., via one or more buses).

[0067] The candidate resource identification component 720 may identify a set of candidate resources within a set of available resources for transmitting a D2D transmission. In some cases, if the subset of available resources for transmitting a second transmission is empty, the candidate resource identification component 720 may modify the set of candidate resources to include additional resources from the set of available resources such that the subset of the set of available resources is non-empty. In some cases, the set of candidate resources is identified as resources in the set of available resources having a received energy below a threshold. In some cases, modifying includes: increasing the threshold until the subset of the set of available resources is non-empty. In some cases, the set of available resources includes a subset of the set of configured resources that is available for D2D transmission and is identified based on one or more SAs associated with one or more D2D transmitters.

[0068] The D2D transmission resource selection component 725 may select a first resource within a candidate resource set for transmitting a first transmission for D2D transmission. In some cases, the first resource is randomly selected from the candidate resource set.

[0069] The blind HARQ resource determination component 730 may determine a subset of available resources for transmitting a second transmission for D2D transmission. In some cases, the blind HARQ resource determination component 730 may determine that the subset of available resources for transmitting the second transmission is empty and skip selecting the second resource and transmitting the second transmission. In some cases, the subset within the set of available resources is determined based on the remaining resources in the candidate resource set after removing the first resource from the candidate resource set.

[0070] The HARQ transmission resource selection component 735 may select a second resource within a subset of the set of available resources for transmitting the second transmission. In some cases, selecting the second resource includes randomly selecting the second resource from the subset within the set of available resources.

[0071] The D2D transmission component 740 may use the first resource to transmit the first transmission and use the second resource to transmit the second transmission.

[0072] The time window identification component 745 may identify a time window near the first time and determine the subset of the set of available resources as the remaining resources within the time window. In some cases, additionally or alternatively, determining the subset of the set of available resources includes identifying the first time for transmitting the first transmission.

[0073] The D2D configuration component 750 may receive D2D configuration information from a base station. In some cases, the time window is configured by the base station. In some cases, the time window includes a predetermined fixed time window. In some cases, the D2D transmission includes a sidelink transmission between two D2D UE devices, and the set of available resources is the PSSCH resource.

[0074] Figure 8 FIG. shows a diagram of a system 800 according to various aspects of the present disclosure. The system 800 includes a device 805 that supports autonomous resource selection for multiple transmissions in D2D communication. The device 805 may be, for example, with reference to Figure 1 、 5Examples of the wireless device 505, wireless device 605, or UE 115 described above and 6 or components thereof. The device 805 may include components for two-way voice and data communication, including components for sending and receiving communications, including a communication manager 815, a processor 820, a memory 825, software 830, a transceiver 835, an antenna 840, and an I / O controller 845. These components may communicate electronically via one or more buses (e.g., bus 810). The device 805 may communicate wirelessly with one or more base stations 105.

[0075] The processor 820 may include intelligent hardware devices (e.g., a general-purpose processor, a digital signal processor (DSP), a central processing unit (CPU), a microcontroller, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), a programmable logic device, discrete gate or transistor logic components, discrete hardware components, or any combination of the foregoing). In some cases, the processor 820 may be configured to operate a memory array using a memory controller. In other cases, the memory controller may be integrated into the processor 820. The processor 820 may be configured to execute computer-readable instructions stored in the memory to perform various functions (e.g., functions or tasks for supporting autonomous resource selection for multiple transmissions in D2D communication).

[0076] The memory 825 may include random access memory (RAM) and read-only memory (ROM). The memory 825 may store computer-readable computer-executable software 830 including instructions that, when executed, cause the processor to perform the various functions described herein. In some cases, the memory 825 may contain a basic input / output system (BIOS) or the like that may control basic hardware or software operations such as interactions with peripheral components or devices.

[0077] The software 830 may include code for implementing aspects of the present disclosure, including code for supporting autonomous resource selection for multiple transmissions in D2D communication. The software 830 may be stored in a non-transitory computer-readable medium such as system memory or other memory. In some cases, the software 830 may not be directly executable by the processor but may cause a computer (e.g., when compiled and executed) to perform the functions described herein.

[0078] As described above, the transceiver 835 may communicate bidirectionally via one or more antennas, wired or wireless links. For example, the transceiver 835 may represent a wireless transceiver and may communicate bidirectionally with another wireless transceiver. The transceiver 835 may also include: a modem for modulating packets and providing the modulated packets to the antenna for transmission and for demodulating packets received from the antenna.

[0079] In some cases, a wireless device may include a single antenna 840. However, in some cases, the device may have more than one antenna 840 capable of simultaneously transmitting or receiving multiple wireless transmissions.

[0080] The I / O controller 845 may manage the input and output signals of the device 805. The I / O controller 845 may also manage peripheral devices not integrated into the device 805. In some cases, the I / O controller 845 may represent a physical connection or port to an external peripheral. In some cases, the I / O controller 845 may utilize an operating system such as or other known operating systems.

[0081] Figure 9 FIG. shows a flow chart of a method 900 for autonomous resource selection for multiple transmissions in D2D communication in accordance with various aspects of the present disclosure. Operations of the method 900 may be implemented by a UE 115 or its components as described herein. For example, operations of the method 900 may be performed by a communication manager as described with reference to Figures 5 to 8 In some examples, the UE 115 may execute a set of code to control the functional elements of the device to perform the functions described below. Additionally or alternatively, the UE 115 may use dedicated hardware to perform aspects of the functions described below.

[0082] At block 905, the UE 115 may identify a set of candidate resources for transmitting a D2D transmission within a set of available resources. The operation of block 905 may be performed according to the method described with reference to Figures 1 - 4 In some examples, aspects of the operation of block 905 may be performed by a candidate resource identification component as described with reference to Figures 5 to 8 At block 910, the UE 115 may select a first resource within the set of candidate resources for transmitting a first transmission of the D2D transmission. The operation of block 910 may be performed according to the method described with reference to

[0083] In some examples, aspects of the operation of block 910 may be performed by a D2D transmission resource selection component as described with reference to Figures 1 - 4 At block 915, the UE 115 may determine a subset of the set of available resources for transmitting a second transmission of the D2D transmission. The operation of block 915 may be performed according to the method described with reference to Figures 5 to 8 In some examples, aspects of the operation of block 915 may be performed by a blind HARQ resource determination component as described with reference to

[0084] Figures 1 to 4 At block 915, the UE 115 may determine a subset of the set of available resources for transmitting a second transmission of the D2D transmission. The operation of block 915 may be performed according to the method described with reference to Figures 5 to 8 In some examples, aspects of the operation of block 915 may be performed by a blind HARQ resource determination component as described with reference to

[0085] At block 920, the UE 115 may select a second resource within a subset of a set of available resources for transmitting a second transmission. The operation of block 920 may be performed according to the method described with reference to Figures 1 to 4 The aspects of the operation of block 920 may be performed by a HARQ transmission resource selection component as described with reference to Figures 5 to 8 described.

[0086] At block 925, the UE 115 may use the first resource to transmit a first transmission. The operation of block 925 may be performed according to the method described with reference to Figures 1 to 4 The aspects of the operation of block 925 may be performed by a D2D transmission component as described with reference to Figures 5 to 8 described.

[0087] At block 930, the UE 115 may use the second resource to transmit a second transmission. The operation of block 930 may be performed according to the method described with reference to Figures 1 to 4 The aspects of the operation of block 930 may be performed by a D2D transmission component as described with reference to Figures 5 to 8 described.

[0088] Figure 10 FIG. shows a flow chart of a method 1000 for autonomous resource selection for multiple transmissions in D2D communication in accordance with various aspects of the present disclosure. The operations of method 1000 may be implemented by the UE 115 or its components as described herein. For example, the operations of method 1000 may be performed by a communication manager as described with reference to Figures 5 to 8 described. In some examples, the UE 115 may execute a set of code to control the functional elements of the device to perform the functions described below. Additionally or alternatively, the UE 115 may use dedicated hardware to perform aspects of the functions described below.

[0089] At block 1005, the UE 115 may identify a set of candidate resources within a set of available resources for transmitting a D2D transmission. The operation of block 1005 may be performed according to the method described with reference to Figures 1 to 4 The aspects of the operation of block 1005 may be performed by a candidate resource identification component as described with reference to Figures 5 to 8 described.

[0090] At block 1010, the UE 115 may select a first resource within the set of candidate resources for transmitting a first transmission of the D2D transmission. The operation of block 1010 may be performed according to the method described with reference to Figures 1 to 4 The aspects of the operation of block 1010 may be performed by a component as described with reference to Figures 5 to 8Execute using the described D2D transmission resource selection component.

[0091] At block 1015, the UE 115 may determine a subset of the set of available resources as the remaining resources within a time window near the first resource in the candidate resource set. The operation of block 1015 may be performed according to the method described with reference to Figures 1 to 4 In some examples, aspects of the operation of block 1015 may be performed by a blind HARQ resource determination or time window identification component as described with reference to Figures 5 to 8 Execute.

[0092] At block 1020, the UE 115 may select a second resource within a subset of the set of available resources for transmitting a second transmission. The operation of block 1020 may be performed according to the method described with reference to Figures 1 to 4 In some examples, aspects of the operation of block 1020 may be performed by a HARQ transmission resource selection component as described with reference to Figures 5 to 8 Execute.

[0093] At block 1025, the UE 115 may use the first resource to transmit a first transmission. The operation of block 1025 may be performed according to the method described with reference to Figures 1 to 4 In some examples, aspects of the operation of block 1025 may be performed by a D2D transmission component as described with reference to Figures 5 to 8 Execute.

[0094] At block 1030, the UE 115 may use the second resource to transmit a second transmission. The operation of block 1030 may be performed according to the method described with reference to Figures 1 to 4 In some examples, aspects of the operation of block 1030 may be performed by a D2D transmission component as described with reference to Figures 5 to 8 Execute.

[0095] Figure 11 FIG. shows a flow chart of a method 1100 for autonomous resource selection for multiple transmissions in D2D communication in accordance with various aspects of the present disclosure. The operations of method 1100 may be implemented by the UE 115 or its components as described herein. For example, the operations of method 1100 may be performed by a communication manager as described with reference to Figures 5 to 8 Execute. In some examples, the UE 115 may execute a set of code to control the functional elements of the device to perform the functions described below. Additionally or alternatively, the UE 115 may use dedicated hardware to perform aspects of the functions described below.

[0096] At block 1105, the UE 115 may identify a candidate resource set within the set of available resources for transmitting a D2D transmission. The operation of block 1105 may be performed according to the method described with reference to Figures 1 to 4The described method is used to perform the operations in block 1105. In some examples, aspects of the operations in block 1105 can be performed by a candidate resource identification component as described with reference to Figures 5 to 8 as described.

[0097] At block 1110, the UE 115 may select a first resource within the set of candidate resources for transmitting a first transmission of the D2D transmission. The operations in block 1110 can be performed according to the method described with reference to Figures 1 to 4 as described. In some examples, aspects of the operations in block 1110 can be performed by a D2D transmission resource selection component as described with reference to Figures 5 to 8 as described.

[0098] At block 1115, the UE 115 may determine a subset of the set of available resources as the remaining resources within a time window near the first resource in the set of candidate resources. The operations in block 1115 can be performed according to the method described with reference to Figures 1 to 4 as described. In some examples, aspects of the operations in block 1115 can be performed by a blind HARQ resource determination and time window determination component as described with reference to Figures 5 to 8 as described.

[0099] At block 1120, the UE 115 may determine that the subset of the set of available resources for transmitting a second transmission is empty. The operations in block 1120 can be performed according to the method described with reference to Figures 1 to 4 as described. In some examples, aspects of the operations in block 1120 can be performed by a blind HARQ resource determination component as described with reference to Figures 5 to 8 as described.

[0100] At block 1125, the UE 115 may modify the set of candidate resources to include additional resources from the set of available resources such that the subset of the set of available resources is non - empty. The operations in block 1125 can be performed according to the method described with reference to Figures 1 to 4 as described. In some examples, aspects of the operations in block 1125 can be performed by a candidate resource identification component as described with reference to Figures 5 to 8 as described.

[0101] At block 1130, the UE 115 may select a second resource within the subset of the set of available resources for transmitting a second transmission. The operations in block 1130 can be performed according to the method described with reference to Figures 1 to 4 as described. In some examples, aspects of the operations in block 1130 can be performed by a HARQ transmission resource selection component as described with reference to Figures 5 to 8 as described.

[0102] At block 1135, the UE 115 may use the first resource to transmit the first transmission. The operations in block 1135 can be performed according to the method described with reference to Figures 1 to 4The described method is used to perform the operations of block 1135. In some examples, aspects of the operations of block 1135 can be performed by a D2D transmission component as described with reference to Figures 5 to 8 The D2D transmission component described.

[0103] At block 1140, the UE 115 can use a second resource to send a second transmission. The operations of block 1140 can be performed according to the method described with reference to Figures 1 to 4 The described method is used to perform the operations of block 1140. In some examples, aspects of the operations of block 1140 can be performed by a D2D transmission component as described with reference to Figures 5 to 8 The D2D transmission component described.

[0104] It should be noted that the above methods describe possible implementations, and the operations and steps can be rearranged or otherwise modified, and other implementations are also possible. In addition, aspects of two or more methods can be combined.

[0105] The techniques described herein can be used in various wireless communication systems, such as code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, single carrier frequency division multiple access (SC-FDMA) systems, and other systems. The terms "system" and "network" are generally used interchangeably. CDMA systems can implement radio technologies such as CDMA2000, Universal Terrestrial Radio Access (UTRA), etc. CDMA2000 covers standards such as IS-2000, IS-95, and IS-856. The IS-2000 version is commonly referred to as CDMA2000 1X, 1X, etc. IS-856 (TIA-856) is commonly referred to as CDMA2000 1xEV-DO, High Rate Packet Data (HRPD), etc. UTRA includes Wideband CDMA (WCDMA) and other variants of CDMA. TDMA systems can implement radio technologies such as Global System for Mobile Communications (GSM).

[0106] OFDMA systems can implement radio technologies such as Ultra Mobile Broadband (UMB), Evolved UTRA (E-UTRA), Institute of Electrical and Electronics Engineers (IEEE) 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, Flash-OFDM, etc. UTRA and E-UTRA are part of the Universal Mobile Telecommunications System (UMTS). 3GPP LTE and LTE-A are versions of UMTS that use E-UTRA. UTRA, E-UTRA, UMTS, LTE, LTE-A, and GSM are described in the literature from an organization called the "3rd Generation Partnership Project" (3GPP). CDMA2000 and UMB are described in the literature from an organization called the "3rd Generation Partnership Project 2" (3GPP2). The techniques described herein can be used in the systems and radio technologies mentioned above as well as other systems and radio technologies. Although aspects of the LTE system may be described for purposes of example and LTE terminology may be used in most of the description, the techniques described herein can be applied beyond LTE applications.

[0107] In an LTE / LTE-A network including such a network described herein, the term evolved Node B (eNB) can be used, for example, to describe a base station. One or more wireless communication systems described herein can include a heterogeneous LTE / LTE-A network where different types of eNBs provide coverage for various geographical areas. For example, each eNB or base station can provide communication coverage for a macro cell, a small cell, or other types of cells. The term "cell" can be used to describe a base station, a carrier or component carrier associated with the base station, or the coverage area of the carrier or base station (e.g., a sector, etc.), depending on the context.

[0108] A base station can include or can be referred to by those skilled in the art as a base transceiver station, radio base station, access point, radio transceiver, Node B, eNB, home Node B, home eNode B, or some other suitable term. The geographical coverage area of a base station can be divided into sectors that form part of the coverage area. One or more wireless communication systems described herein can include different types of base stations (e.g., macro cell base stations or small cell base stations). The UEs described herein are capable of communicating with various types of base stations and network devices including macro eNBs, small cell eNBs, relay base stations, etc. There may be overlapping geographical coverage areas for different technologies.

[0109] Macro cells typically cover a relatively large geographical area (e.g., with a radius of several kilometers) and can allow unrestricted access for UEs having a service subscription with the network provider. Compared with macro cells, small cells can be associated with a lower-power base station, and small cells can operate in the same or different (e.g., licensed, unlicensed, etc.) frequency bands compared with macro cells. According to various examples, small cells can include pico cells, femto cells, and micro cells. For example, a pico cell can cover a smaller geographical area and can allow unrestricted access for UEs having a service subscription with the network provider. A femto cell can also cover a small geographical area (e.g., a home) and can provide restricted access for UEs associated with the femto cell (e.g., UEs in a closed subscriber group (CSG), UEs of home users, etc.). The eNB of a macro cell can be referred to as a macro eNB. The eNB of a small cell can be referred to as a small cell eNB, pico eNB, femto eNB, or home eNB. An eNB can support one or more (e.g., two, three, four, etc.) cells. A UE is capable of communicating with various types of base stations and network devices including macro eNBs, small cell eNBs, relay base stations, etc.

[0110] One or more wireless communication systems described herein can support synchronous or asynchronous operation. For synchronous operation, base stations can have similar frame timings, and transmissions from different base stations can be approximately aligned in time. For asynchronous operation, base stations may have different frame timings, and transmissions from different base stations may not be aligned in time. The techniques described herein can be used for synchronous or asynchronous operation.

[0111] The downlink transmissions described herein can also be referred to as forward link transmissions, while the uplink transmissions can also be referred to as reverse link transmissions. Each communication link described herein - including, for example Figure 1 and 2 wireless communication systems 100 and 200 - can include one or more carriers, where each carrier can be a signal composed of multiple subcarriers (e.g., waveform signals of different frequencies).

[0112] The description given herein in conjunction with the figures describes example configurations and does not represent all examples that can be implemented or that are within the scope of the claims. The term "exemplary" as used herein means "serving as an example, instance, or illustration" and not "preferred" or "advantageous over other examples". The detailed description includes specific details for providing an understanding of the described techniques. However, these techniques can be implemented without these specific details. In some cases, well-known structures and devices are shown in block diagram form to avoid obscuring the concepts of the described examples.

[0113] The information and signals described in this document can be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referred to throughout the above description can be represented by voltage, current, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

[0114] The various illustrative blocks and modules described in connection with the disclosure herein can be implemented or performed with a general purpose processor, DSP, ASIC, FPGA or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. The processor may also be implemented as a combination of computing devices (e.g., a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration).

[0115] The functions described herein can be implemented in hardware, software executed by a processor, firmware, or any combination thereof. If implemented in software executed by a processor, the functions can be stored on or transmitted via a computer-readable medium as one or more instructions or code. Other examples and implementations are within the scope of the present disclosure and the appended claims. For example, due to the nature of software, the above-described functions can be implemented using software executed by a processor, hardware, firmware, hardwiring, or any combination of these items. The features for implementing the functions can also be physically located in various positions, including being distributed such that portions of the functions are implemented at different physical locations. As used herein, including in the claims, when used in a list of two or more items, the term “and / or” means that any one of the listed items can be used alone, or any combination of two or more of the listed items can be used. For example, if a composition is described as containing components A, B, and / or C, the composition can contain only A; only B; only C; a combination of A and B; a combination of A and C; a combination of B and C; or a combination of A, B, and C. Additionally, as used herein, including in the claims, as used in a list of items (e.g., a list of items followed by a phrase such as “at least one of” or “one or more of”), “or” indicates an inclusive list such that, for example, a phrase referring to a list of items “at least one of” means any combination of those items, including a single member. As an example, “at least one of A, B, or C” is intended to cover A, B, C, A - B, A - C, B - C, and A - B - C, as well as any combination having multiple identical elements (e.g., A - A, A - A - A, A - A - B, A - A - C, A - B - B, A - C - C, B - B, B - B - B, B - B - C, C - C, and C - C - C, or any other ordering of A, B, and C). As used herein, the phrase “based on” should not be construed as a reference to a closed set of conditions. For example, without departing from the scope of the present disclosure, an exemplary step described as “based on condition A” can be based on both condition A and condition B. In other words, as used herein, the phrase “based on” should be interpreted in the same manner as the phrase “at least partially based on”.

[0116] A computer-readable medium includes both a non-transitory computer storage medium and a communication medium, where the communication medium includes any medium that facilitates transfer of a computer program from one place to another. The non-transitory storage medium can be any available medium that can be accessed by a general-purpose or a special-purpose computer. By way of example and not limitation, the non-transitory computer-readable medium can include RAM, ROM, electrically erasable programmable read-only memory (EEPROM), compact disc read-only memory (CD-ROM) or other optical disc storage, magnetic disk storage or other magnetic disk storage devices, or any other non-transitory medium that can be used to carry or store desired program code units in the form of instructions or data structures and that can be accessed by a general-purpose or a special-purpose computer or a general-purpose or a special-purpose processor computer. Also, any connection is properly termed a computer-readable medium. For example, if software is transmitted from a website, server, or other remote source using coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of the medium. Discs and disks as used herein include CD, laser disc, optical disc, digital versatile disc (DVD), floppy disk, and Blu-ray disc, where discs generally reproduce data magnetically, while disks reproduce data optically with lasers. Combinations of the above are also included within the scope of computer-readable media.

[0117] The description provided herein is to enable a person skilled in the art to make or use the present disclosure. Various modifications to the present disclosure will be apparent to those skilled in the art, and the general principles defined herein can be applied to other variations without departing from the scope of the present disclosure. Thus, the present disclosure is not limited to the examples and designs described herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for wireless communication, comprising: identifying a set of candidate resources for device-to-device (D2D) transmission within a set of available resources; selecting a first resource within the set of candidate resources for a first transmission of the D2D transmission; obtaining a subset of trimmed candidate resources for a second transmission of the D2D transmission, wherein the trimmed candidate resources are within a predetermined time window of the selected first resource; determining that the subset of trimmed candidate resources for the second transmission is empty; transmitting the first transmission on the first resource; and not transmitting the second transmission.

2. The method according to claim 1, wherein, The obtaining the subset of trimmed candidate resources includes: determining the remaining resources in the set of candidate resources at least in part based on removing the first resource from the set of candidate resources.

3. The method according to claim 2, wherein, The obtaining the subset of trimmed candidate resources further includes: identifying a first time for transmitting the first transmission; identifying a time window near the first time; and determining the subset of trimmed candidate resources as the remaining resources within the time window.

4. The method according to claim 1, wherein Resources for the second transmission start after the selected first resource in time, or resources for the second transmission start before the selected first resource in time.

5. The method according to claim 1, wherein The time window is configured by a base station.

6. The method according to claim 1, wherein The time window includes a predetermined fixed time window.

7. The method according to claim 1, wherein the determining that the subset of trimmed candidate resources for the second transmission is empty includes: skipping the selection of resources for the second transmission.

8. The method according to claim 1, further comprising: modifying the set of candidate resources to include additional resources in the set of available resources such that the subset of trimmed candidate resources is non-empty.

9. The method according to claim 8, wherein, The set of candidate resources is identified as resources in the set of available resources having received energy below a threshold, and wherein the modification includes increasing the threshold until the subset of trimmed candidate resources is non-empty.

10. The method according to claim 1, wherein, The first resource is randomly selected from the set of candidate resources.

11. The method according to claim 1, wherein, The second transmission is a retransmitted D2D transmission without receiving a negative determination of the first transmission.

12. The method according to claim 1, wherein, The set of available resources includes a subset of configured resources available for D2D transmission and is identified at least in part based on one or more scheduling allocations (SAs) associated with one or more D2D transmitters. Optionally, the D2D transmission includes a sidelink transmission between two D2D user equipment (UE) devices, and wherein the set of available resources includes physical sidelink shared channel (PSSCH) resources, and wherein the second transmission is a blind hybrid automatic repeat request (HARQ).

13. An apparatus for wireless communication, comprising: a processor; a memory in electronic communication with the processor; and instructions stored in the memory and executable by the processor to cause the apparatus to perform the following operations: Identify a set of candidate resources for device-to-device (D2D) transmission within a set of available resources; Select a first resource within the set of candidate resources for transmitting a first transmission of the D2D transmission; Obtain a subset of trimmed candidate resources for transmitting a second transmission of the D2D transmission, wherein the trimmed candidate resources are within a predetermined time window of the selected first resource; Determine that the subset of trimmed candidate resources for transmitting the second transmission is empty; Transmit the first transmission on the first resource; and Do not transmit the second transmission.

14. The apparatus according to claim 13, wherein, The instructions may also be executable to perform the following operations: Determine the remaining resources in the set of candidate resources based at least in part on removing the first resource from the set of candidate resources, Wherein, optionally, the D2D transmission includes a sidelink transmission between two D2D user equipment (UE) devices, and wherein the set of available resources includes physical sidelink shared channel (PSSCH) resources, and wherein the second transmission is a blind hybrid automatic repeat request (HARQ).

15. The device according to claim 14, wherein, The instructions may also be executable to perform the following operations: Identify a first time for transmitting the first transmission; Identify a time window near the first time; and Determine the subset of trimmed candidate resources as the remaining resources within the time window.

16. An apparatus for wireless communication in a system, comprising: A unit for identifying a set of candidate resources for device-to-device (D2D) transmission within a set of available resources; A unit for selecting a first resource within the set of candidate resources for transmitting a first transmission of the D2D transmission; A unit for obtaining a subset of trimmed candidate resources for transmitting a second transmission of the D2D transmission, wherein the trimmed candidate resources are within a predetermined time window of the selected first resource; A unit for determining that the subset of trimmed candidate resources for transmitting the second transmission is empty; A unit for transmitting the first transmission on the first resource; and A unit for not transmitting the second transmission.

17. The apparatus according to claim 16, further comprising: A unit for determining the remaining resources in the set of candidate resources based at least in part on removing the first resource from the set of candidate resources.

18. The apparatus according to claim 17, further comprising: A unit for identifying a first time for transmitting the first transmission; A unit for identifying a time window near the first time; And A unit for determining the subset of trimmed candidate resources as the remaining resources within the time window.

19. The apparatus according to claim 16, wherein the resources for the second transmission are after the selected first resource in time, or the resources for the second transmission start before the selected first resource in time.

20. The apparatus according to claim 16, wherein The time window is configured by a base station.

21. The apparatus according to claim 16, wherein, The time window includes a predetermined fixed time window.

22. The apparatus according to claim 16, wherein the unit for determining that the subset of trimmed candidate resources for transmitting the second transmission is empty comprises: A unit for skipping the selection of resources for the second transmission.

23. The apparatus according to claim 16, further comprising: A unit for modifying the candidate resource set to include additional resources in the set of available resources such that the trimmed subset of candidate resources is non-empty.

24. The device according to claim 23, wherein, The candidate resource set is identified as resources in the set of available resources having received energy below a threshold, and wherein the apparatus further comprises: A unit for increasing the threshold until the trimmed subset of candidate resources is non-empty.

25. The apparatus according to claim 16, wherein, The first resource is randomly selected from the candidate resource set.

26. The apparatus according to claim 16, wherein, The second transmission is a D2D transmission retransmitted without receiving a negative determination of the first transmission.

27. The apparatus according to claim 16, wherein, The set of available resources includes a subset of the configured resource set that is available for D2D transmission and is at least partially identified based on one or more scheduling allocations (SAs) associated with one or more D2D transmitters, wherein optionally, the D2D transmission includes a sidelink transmission between two D2D user equipment (UE) devices, and wherein the set of available resources includes physical sidelink shared channel (PSSCH) resources, and wherein the second transmission is a blind hybrid automatic repeat request (HARQ).

28. A non-transitory computer-readable medium storing code for wireless communication, the code including instructions executable by a processor to perform the following operations: Identify a set of candidate resources for a device-to-device (D2D) transmission within a set of available resources; Select a first resource from within the candidate resource set for transmitting a first transmission of the D2D transmission; Obtain a trimmed subset of candidate resources for transmitting a second transmission of the D2D transmission, wherein the trimmed candidate resources are within a predetermined time window of the selected first resource; Determine that the trimmed subset of candidate resources for transmitting the second transmission is empty; Transmit the first transmission on the first resource; and Do not transmit the second transmission.

29. The non-transitory computer-readable medium according to claim 28, wherein, The instructions are further executable to perform the following operations: Determine the remaining resources in the candidate resource set at least partially based on removing the first resource from the candidate resource set, wherein optionally, the D2D transmission includes a sidelink transmission between two D2D user equipment (UE) devices, and wherein the set of available resources includes physical sidelink shared channel (PSSCH) resources, and wherein the second transmission is a blind hybrid automatic repeat request (HARQ).

30. The non-transitory computer-readable medium according to claim 29, wherein, The instructions are further executable to perform the following operations: Identify a first time for transmitting the first transmission; Identify a time window near the first time; and Determine the trimmed subset of candidate resources as the remaining resources within the time window.

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