Resource reservation and release in sidelink

Abstract

Techniques and apparatus for managing the release of resource reservations for sidelink communications are provided. At least one resource reservation is determined from a resource pool having time-frequency resources allocated for sidelink communications with one or more user devices. Control information including an indication of the at least one resource reservation and an indication of whether the at least one resource reservation is releasable is sent. Based on the control information, a determination is made whether to reclaim the at least one resource reservation. Based on the determination, a set of resource reservations is selected from the resource pool for sidelink communications.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of priority to U.S. application No. 17 / 062,049, filed on October 2, 2020, which claims the benefit of and priority to U.S. provisional patent application serial No. 62 / 910,968, filed on October 4, 2019, both of which have been assigned to the assignee of this application, and their entire contents are expressly incorporated herein by reference. Technical Field

[0003]

[0004] Aspects of the present disclosure generally relate to wireless communications, and more particularly, to techniques for managing release of resource reservations for sidelink communications. Background Art

[0004] Wireless communication systems are widely deployed to provide a variety of telecommunication services such as telephony, video, data, messaging, broadcasts, and the like. These wireless communication systems may employ multiple-access technologies that can support communication with multiple users by sharing available system resources (e.g., bandwidth, transmit power, and the like). Examples of such multiple-access systems include third generation partnership project (3GPP) long term evolution (LTE) systems, LTE-Advanced (LTE-A) systems, 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 time division synchronous code division multiple access (TD-SCDMA) systems, to name a few.

[0005] These multiple access technologies have been adopted in various telecommunication standards to provide a common protocol that enables different wireless devices to communicate on a city-wide, national-wide, regional-wide, and even global scale. New radio (e.g., 5G NR) is an example of an emerging telecommunication standard. NR is an evolution of the LTE mobile standard released by 3GPP. NR is designed to better support mobile broadband Internet access by improving spectrum efficiency, reducing costs, improving services, making full use of new spectrum, and better integrating with other open standards using OFDMA and cyclic prefix (CP) on downlink (DL) and uplink (UL). To this end, NR supports beamforming, multiple-input multiple-output (MIMO) antenna technology, and carrier aggregation.

[0006] However, as the demand for mobile broadband access continues to increase, there is a need to further improve NR and LTE technologies. Preferably, these improvements can also be applied to other multiple access technologies and communication standards that adopt these technologies. Summary of the invention

[0007] The systems, methods, and apparatus of the present disclosure each have aspects, no single one of which is solely responsible for its desirable attributes. The claims set forth below do not limit the scope of the present disclosure, and some features will now be briefly discussed. After careful consideration of this discussion, and particularly after reading the section entitled "Detailed Description of the Invention," one will understand how the features of the present disclosure provide advantages, including improved management of resource reservations for sidelink communications.

[0008] Certain aspects provide a method for wireless communication by a first user equipment (UE). The method generally includes: determining at least one resource reservation from a resource pool, the resource pool including a plurality of time-frequency resources allocated for sidelink communication with one or more second UEs. The method also includes: sending control information including a first indication of the at least one resource reservation and a second indication of whether the at least one resource reservation is releasable.

[0009] Certain aspects provide an apparatus (e.g., a UE) for wireless communication. The apparatus generally includes at least one processor, a transmitter, and a memory coupled to the at least one processor. The at least one processor is configured to determine at least one resource reservation from a resource pool, the resource pool including a plurality of time-frequency resources allocated for sidelink communications with one or more other apparatuses. The transmitter is configured to send control information including a first indication of the at least one resource reservation and a second indication of whether the at least one resource reservation is releasable.

[0010] Certain aspects provide an apparatus (e.g., a UE) for wireless communication. The apparatus generally includes: means for determining at least one resource reservation from a resource pool, the resource pool including a plurality of time-frequency resources allocated for sidelink communications with one or more other apparatuses. The apparatus also includes: means for sending control information including a first indication of the at least one resource reservation and a second indication of whether the at least one resource reservation is releasable.

[0011] Certain aspects provide a computer-readable medium having computer executable code stored thereon for wireless communication by a first UE. The computer executable code generally includes: code for determining at least one resource reservation from a resource pool, the resource pool including a plurality of time-frequency resources allocated for sidelink communication with one or more second UEs. The computer executable code also includes: code for sending control information including a first indication of the at least one resource reservation and a second indication of whether the at least one resource reservation is releasable.

[0012] Certain aspects provide a method for wireless communication by a first UE. The method generally includes receiving control information, the control information including: (i) a first indication of at least one resource reservation for a second UE from a resource pool, the resource pool including a plurality of time-frequency resources that can be used for sidelink communication, and (ii) a second indication of whether the at least one resource reservation is releasable. The method also includes determining whether to reclaim the at least one resource reservation based at least in part on the control information. The method also includes selecting a set of resource reservations from the resource pool for sidelink communication based on the determination.

[0013] Certain aspects provide an apparatus (e.g., a UE) for wireless communication. The apparatus generally includes a receiver, at least one processor, and a memory coupled to the at least one processor. The receiver is configured to receive control information, the control information including: (i) a first indication of at least one resource reservation made by another apparatus from a resource pool, the resource pool including a plurality of time-frequency resources that can be used for sidelink communication, and (ii) a second indication of whether the at least one resource reservation is releasable. The at least one processor is configured to determine whether to reclaim the at least one resource reservation based at least in part on the control information. The at least one processor is also configured to select a set of resource reservations from the resource pool for sidelink communication based on the determination.

[0014] Certain aspects provide an apparatus (e.g., a UE) for wireless communication. The apparatus generally includes: means for receiving control information, the control information including: (i) a first indication of at least one resource reservation made by another apparatus from a resource pool, the resource pool including a plurality of time-frequency resources that can be used for sidelink communication, and (ii) a second indication of whether the at least one resource reservation is releasable. The apparatus also includes: means for determining whether to reclaim the at least one resource reservation based at least in part on the control information. The apparatus also includes: means for selecting a set of resource reservations from the resource pool for sidelink communication based on the determination.

[0015] Certain aspects provide a computer-readable medium having computer executable code stored thereon for wireless communication by a first UE. The computer executable code generally includes: code for receiving control information, the control information including: (i) a first indication to another device to make at least one resource reservation from a resource pool, the resource pool including multiple time-frequency resources that can be used for sidelink communication, and (ii) a second indication of whether the at least one resource reservation is releasable. The computer executable code also includes: code for determining whether to reclaim the at least one resource reservation based at least in part on the control information. The computer executable code also includes: code for selecting a set of resource reservations from the resource pool for sidelink communication based on the determination.

[0016] To achieve the aforementioned and related purposes, one or more aspects include the features described in detail below and specifically pointed out in the claims. The following description and the accompanying drawings describe in detail certain exemplary features of one or more aspects. However, these features are only illustrative of some of the various ways in which the basic principles of these various aspects can be employed. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to understand in detail the implementation of the above-described features of the present disclosure, the present application provides a more specific description with reference to some aspects for the above brief summary, some of which are illustrated in the accompanying drawings. However, it should be noted that since the description of the present invention allows for other equally effective aspects, these drawings only depict some typical aspects of the present disclosure, which should not be considered to limit the scope of protection of the present invention.

[0018] Figure 1 is a block diagram conceptually illustrating an example telecommunications system in accordance with certain aspects of the present disclosure.

[0019] Figure 2 is a block diagram conceptually illustrating designs of exemplary base stations (BSs) and user equipments (UEs) in accordance with certain aspects of the present disclosure.

[0020] Figure 3A and Figure 3B According to certain aspects of the present disclosure, a graphical representation of an example vehicle-to-everything (V2X) system is shown.

[0021] Figure 4 is a flow chart illustrating example operations for wireless communications of a UE in accordance with certain aspects of the present disclosure.

[0022] Figure 5 is a flow chart illustrating example operations for wireless communications of a BS in accordance with certain aspects of the present disclosure.

[0023] Figure 6 According to aspects of the present disclosure, a communication device is shown that may include various components configured to perform operations of the techniques disclosed herein.

[0024] To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It will be appreciated that elements disclosed in one aspect may be beneficially utilized in other aspects without specific recitation. DETAILED DESCRIPTION

[0025] Various aspects of the present disclosure provide apparatus, methods, processing systems, and computer-readable media for managing the release of resource reservations for sidelink communications. In a communication system (e.g., 5G NR) supporting sidelink communications, a UE may signal sidelink control information (SCI) to one or more other UEs, wherein the SCI includes resource (e.g., frequency domain resources and / or time domain resources) reservations for sidelink communications. In some cases, the UE may broadcast the SCI to multiple UEs to enable the UEs to avoid communicating during these resource reservations. Resources may be reserved from a resource pool that includes resources allocated for sidelink transmissions (e.g., configured by a gNB).

[0026] The resource reservation may be used for transmission of the same transport block (TB) (e.g., retransmission of a TB), or for transmission of different TBs. In addition, the resource reservation may be used for feedback-based transmission, or for non-feedback-based transmission. As described in more detail below, in some aspects, one or more of the resource reservations of the transmitting UE may be releasable (e.g., may be reclaimed by another UE) based in part on the resource reservation (e.g., whether the resource reservation is for a (re)transmission of the same TB as the current TB being transmitted, whether the resource reservation is for transmission of a different TB, whether the resource reservation is for feedback-based transmission, whether the resource reservation is for non-feedback-based transmission, whether the resource reservation is associated with a specific transmission parameter (e.g., modulation and coding scheme (MCS)), etc.).

[0027] In some systems, the receiving UE may not be able to determine whether the resource reservation of the sending UE can be released from the SCI sent by the sending UE. For example, in current systems, the UE usually monitors (e.g., listens to) a feedback channel to determine whether a retransmission will occur. However, this information obtained by monitoring the feedback channel may not be sufficient to determine whether the resource reservation is likely to be used by the sending UE for the transmission of another TB.

[0028] To address this issue, various aspects provide techniques that enable a transmitting UE to indicate in an SCI (and a receiving UE to determine from the SCI) whether a resource reservation of the transmitting UE can be released, so that the resource reservation can potentially be used by other UEs. Based in part on the indication in the SCI, one or more receiving UEs can determine whether to reclaim the resource reservation when selecting resources to be reserved for their own sidelink communications from a resource pool. For example, the receiving UE may reclaim the resource reservation for its sidelink communication if the receiving UE determines the following: (1) based on the SCI, it is determined that the resource reservation is releasable; and (2) it is determined that the resource is available in the resource pool. On the other hand, the receiving UE may avoid reclaiming the resource reservation for its sidelink communication if the receiving UE determines at least one of the following: (1) based on the SCI, it is determined that the resource reservation is not releasable; or (2) the resource is not available in the resource pool.

[0029] The following description provides an example of the release of resource reservations for managing sidelink communications in a communication system, but it is not intended to limit the scope of protection, applicability or examples set forth in the claims. Without departing from the scope of protection of the present disclosure, the functions and arrangements of the components discussed may be changed. Various examples may omit, replace or add various processes or components as needed. For example, the described method may be performed in a different order than described, and various steps may be added, omitted or combined. In addition, the features described with respect to some examples may be combined in other examples. For example, a device may be implemented or a method may be implemented using any number of aspects set forth herein. In addition, the scope of protection of the present disclosure is intended to cover such a device or method, which may be implemented by using other structures, functions, or structures and functions other than or different from the various aspects of the present disclosure set forth herein. It should be understood that any aspect of the disclosure disclosed herein may be embodied by one or more components of the present invention. The word "exemplary" used herein means "used as an example, illustration or description". Any aspect described as "exemplary" herein should not be interpreted as being more preferred or advantageous than other aspects.

[0030] Typically, any number of wireless networks may be deployed in a given geographic area. Each wireless network may support a specific radio access technology (RAT) and may operate on one or more frequencies. RAT may also be referred to as radio technology, air interface, etc. Frequency may also be referred to as carrier, subcarrier, frequency channel, tone, subband, etc. Each frequency may support a single RAT in a given geographic area to avoid interference between wireless networks of different RATs. In some cases, a 5G NR RAT network may be deployed.

[0031] Figure 1 An exemplary wireless communication network 100 is shown in which aspects of the present disclosure may be performed. For example, the wireless communication network 100 may be a NR system (e.g., a 5G NR network).

[0032] like Figure 1 As shown in , the wireless communication network 100 may include multiple base stations (BSs) 110a-z (each also individually referred to herein as BS 110 or collectively referred to as BS 110) and other network entities. BS 110 may provide communication coverage for a particular geographic area, which is sometimes referred to as a "cell", which may be stationary or may move depending on the location of the mobile BS 110. In some examples, BS 110 may be interconnected to each other and / or to one or more other BSs or network nodes (not shown) using any suitable transport network via various types of backhaul interfaces (e.g., direct physical connections, wireless connections, virtual networks, etc.). Figure 1 In the illustrated example, BS 110a, BS 110b, and BS 110c may be macro BSs for macro cell 102a, macro cell 102b, and macro cell 102c, respectively. BS 110x may be a pico BS for pico cell 102x. BS 110y and BS 110z may be femto BSs for femto cells 102y and 102z, respectively. A BS may support one or more cells. BS 110 communicates with user equipment (UE) 120a-y (each also individually referred to herein as UE 120 or collectively referred to as UE 120) in wireless communication network 100. UE 120 (e.g., 120x, 120y, etc.) may be dispersed throughout wireless communication network 100, and each UE 120 may be fixed or mobile.

[0033] According to certain aspects, UE 120 can be configured to implement sidelink communications. Figure 1 As shown in , UE 120a includes a side link resource manager 122a and UE 120b includes a side link resource manager 122b. In some aspects, UE 120a and / or UE 120b may be sending side link communications and may use their respective side link resource managers to indicate in control information (e.g., SCI) whether one or more resource reservations (reserved by the UE) are releasable. Resource reservations may be resources reserved by UE 120a (or UE 120b) in a current transmission of UE 120a (or UE 120b) that will be used for future transmissions of UE 120a (or UE 120b).

[0034] For example, using the sidelink resource manager 122a (or the sidelink resource manager 122b), the UE 120a (or the UE 120b) may determine at least one resource reservation from a resource pool that includes a plurality of time-frequency resources allocated for sidelink communications with one or more other UEs 120. In addition, the UE 120a (or the UE 120b) may use the sidelink resource manager 122a (or the sidelink resource manager 122b) to send control information including a first indication of the at least one resource reservation and a second indication of whether the at least one resource reservation is releasable.

[0035] In some aspects, UE 120a and / or UE 120b may be receiving sidelink communications and may use their respective sidelink resource managers to determine whether a resource reservation (reserved by another UE 120) is releasable based on control information received from another UE 120. For example, using sidelink resource manager 122a (or sidelink resource manager 122b), UE 120a (or UE 120b) may receive control information including: (i) a first indication of at least one resource reservation made by a second UE from a resource pool, the resource pool including a plurality of time-frequency resources that may be used for sidelink communications, and (ii) a second indication of whether the at least one resource reservation is releasable. Using sidelink resource manager 122a (or sidelink resource manager 122b), UE 120a (or UE 120b) may determine whether to reclaim the at least one resource reservation based at least in part on the control information, and select a set of resource reservations from the resource pool for sidelink communications based on the determination.

[0036] The wireless communication network 100 may also include a relay station (e.g., relay station 110r), also known as a repeater, etc., which receives transmissions of data and / or other information from an upstream station (e.g., BS 110a or UE 120r) and sends transmissions of data and / or other information to a downstream station (e.g., UE 120 or BS 110), or relays transmissions between UEs 120 to facilitate communication between devices.

[0037] The network controller 130 may be coupled to a set of BSs 110 and provide coordination and control for the BSs 110. The network controller 130 may communicate with the BSs 110 via a backhaul. The BSs 110 may also communicate with each other (eg, directly or indirectly) via a wireless backhaul or a wired backhaul.

[0038] Figure 2 Exemplary components of BS 110a and UE 120a are shown (eg, in Figure 1Wireless communication networks 100), which can be used to implement aspects of the present disclosure.

[0039] At BS 110a, a transmit processor 220 may receive data from a data source 212 and control information from a controller / processor 240. The control information may be for a physical broadcast channel (PBCH), a physical control format indicator channel (PCFICH), a physical hybrid ARQ indicator channel (PHICH), a physical downlink control channel (PDCCH), a group common PDCCH (GC PDCCH), etc. The data may be for a physical downlink shared channel (PDSCH), etc. The processor 220 may process (e.g., encode and symbol map) the data and control information to obtain data symbols and control symbols, respectively. The transmit processor 220 may also generate reference symbols, e.g., for a primary synchronization signal (PSS), a secondary synchronization signal (SSS), and a cell-specific reference signal (CRS). A transmit (TX) multiple-input multiple-output (MIMO) processor 230 may perform spatial processing (e.g., precoding) on ​​the data symbols, control symbols, and / or reference symbols (if any), and provide output symbol streams to modulators (MODs) 232a-232t. Each modulator 232 can process a respective output symbol stream (e.g., for OFDM, etc.) to obtain an output sample stream. Each modulator can further process (e.g., convert to analog, amplify, filter, and upconvert) the output sample stream to obtain a downlink signal. The downlink signals from modulators 232a-232t can be transmitted via antennas 234a-234t, respectively.

[0040] At UE 120a, antennas 252a-252r can receive downlink signals from BS 110a and provide received signals to demodulators (DEMODs) in transceivers 254a-254r, respectively. Each demodulator 254 can condition (e.g., filter, amplify, downconvert, and digitize) the respective received signals to obtain input samples. Each demodulator can further process the input samples (e.g., for OFDM, etc.) to obtain received symbols. MIMO detector 256 can obtain received symbols from all demodulators 254a-254r, perform MIMO detection on the received symbols (if any), and provide detected symbols. Receive processor 258 can process (e.g., demodulate, deinterleave, and decode) the detected symbols, provide decoded data for UE 120a to data sink 260, and provide decoded control information to controller / processor 280.

[0041] On the uplink, at the UE 120a, a transmit processor 264 may receive data from a data source 262 (e.g., for a physical uplink shared channel (PUSCH)), control information from a controller / processor 280 (e.g., for a physical uplink control channel (PUCCH)), and process the data and control information. The transmit processor 264 may also generate reference symbols for a reference signal (e.g., for a sounding reference signal (SRS)). The symbols from the transmit processor 264 may be precoded by the TX MIMO processor 266 (if applicable), further processed by a demodulator in the transceiver 254a-254r (e.g., for SC-FDM, etc.), and sent to the BS 110a. At BS 110a, the uplink signal from UE 120a may be received by antenna 234, processed by modulator 232, detected by MIMO detector 236 (if applicable), and further processed by receive processor 238 to obtain decoded data and control information sent by UE 120a. Receive processor 238 may provide decoded data to data sink 239 and decoded control information to controller / processor 240.

[0042] Memories 242 and 282 may store data and program codes for BS 110a and UE 120a, respectively.A scheduler 244 may schedule UEs for data transmission on the downlink and / or uplink.

[0043] The controller / processor 280 and / or other processors and modules at the UE 120a may perform or direct the execution of the processes for the techniques described herein. Figure 2 As shown in, according to aspects described herein, a controller / processor 280 of a UE 120 (e.g., UE 120a) has a sidelink resource manager 122 (e.g., sidelink resource manager 122a) configured to implement one or more techniques described herein to manage the release of resource reservations for sidelink communications. Although shown at the controller / processor, other components of the UE 120 may also be used to perform the operations described herein.

[0044] In some examples, access to the air interface may be scheduled. A scheduling entity (e.g., BS 110) allocates resources for communications between some or all devices and apparatuses within its service area or cell. The scheduling entity may be responsible for scheduling, allocating, reconfiguring, and releasing resources for one or more subordinate entities. That is, for scheduled communications, subordinate entities utilize resources allocated by the scheduling entity. BS 110 is not the only entity that acts as a scheduling entity. In some examples, UE 120 may act as a scheduling entity, and resources for one or more subordinate entities (e.g., one or more other UEs 120) may be scheduled, and other UEs 120 may utilize the resources scheduled by the UE 120 for wireless communications. In some examples, UE 120 may act as a scheduling entity in a peer-to-peer (P2P) network and / or a mesh network. In a mesh network example, UE 120 may communicate directly with each other in addition to communicating with the scheduling entity.

[0045] In some examples, the communication between UE 120 and BS 110 is referred to as an access link. The access link may be provided via a Uu interface. The communication between devices may be referred to as a side link.

[0046] In some examples, two or more slave entities (e.g., UE 120) can communicate with each other using sidelink signals. Practical applications of such sidelink communications may include public safety, proximity services, UE to network relay, vehicle to vehicle (V2V) communications, Internet of Everything (IoE) communications, IoT communications, mission-critical grids, and / or various other appropriate applications. Typically, a sidelink signal may refer to a signal that is transmitted from one slave entity (e.g., UE 120a) to another slave entity (e.g., another UE 120) without relaying the communication through a scheduling entity (e.g., UE 120 or BS 110), even if the scheduling entity may be used for scheduling and / or control purposes. In some examples, licensed spectrum may be used to transmit sidelink signals (unlike wireless local area networks that typically use unlicensed spectrum). An example of sidelink communication is PC5, for example, as used in V2V, LTE, and / or NR.

[0047] Various sidelink channels can be used for sidelink communications, including a physical sidelink discovery channel (PSCCH), a physical sidelink control channel (PSCCH), a physical sidelink shared channel (PSSCH), and a physical sidelink feedback channel (PSFCH). The PSSCH can carry a discovery expression that enables neighboring devices to discover each other. The PSCCH can carry control signaling, such as sidelink resource configuration, resource reservation, and other parameters for data transmission, and the PSSCH can carry data transmission. The PSFCH can carry feedback such as CSI related to the sidelink channel quality. In some systems (e.g., NR version 16), two-stage SCI may be supported. The two-stage SCI may include a first-stage SCI (SCI-1) and a second-stage SCI (e.g., SCI-2). SCI-1 may include resource reservation and allocation information, information that can be used to decode SCI-2, and the like. SCI-2 may include information that can be used to decode data and determine whether the UE is the intended recipient of the transmission. SCI-1 and / or SCI-2 may be transmitted via the PSCCH.

[0048] Figure 3A and Figure 3B According to some aspects of the present disclosure, a graphical representation of an exemplary V2X system is shown. For example, Figure 3A and Figure 3B The vehicles shown in FIG. 4 can communicate via a side link channel and can manage resource reservations and / or release of resource reservations as described herein.

[0049] Figure 3A and Figure 3B The V2X system provided in the present invention provides two complementary transmission modes. The first transmission mode (in Figure 3A The second transmission mode (shown by way of example in FIG. 1 ) involves direct communication (e.g., also referred to as sidelink communication) between participants that are close to each other in a local area. Figure 3B ) involves network communication through a network, which can be achieved through a Uu interface (e.g., a wireless communication interface between a radio access network (RAN) and a UE).

[0050] refer to Figure 3A, a V2X system 300 (e.g., which includes vehicle-to-vehicle (V2V) communications) is shown as having two vehicles 302, 304. A first transmission mode allows direct communication between different participants in a given geographic location. As shown, the vehicles can have a wireless communication link 306 with an individual (V2P) (e.g., via a UE) through a PC5 interface. Communication between vehicles 302 and 304 can also occur through a PC5 interface 308. In a similar manner, communication can occur from vehicle 302 to other highway components (e.g., highway component 310), such as traffic signals or signs (V2I) through a PC5 interface 312. About Figure 3A Each communication link shown in , can enable two-way communication between elements, so each element can be a transmitter and receiver of information. The V2X system 300 can be a self-managed system that is implemented without the help of a network entity. Since no network service interruption occurs during switching operations of a moving vehicle, the self-managed system can improve spectrum efficiency, reduce costs, and improve reliability. The V2X system can be configured to operate in a licensed or unlicensed spectrum, so any vehicle equipped with the system can access common frequencies and share information. This coordinated / common spectrum operation allows for safe and reliable operation.

[0051] Figure 3B A V2X system 350 is shown for communicating between a vehicle 352 and a vehicle 354 via a network entity 356. These network communications may occur via discrete nodes such as base stations (e.g., eNBs or gNBs) that send and receive information to and from the vehicles 352, 354 (e.g., relay information between the vehicles 352, 354). For long-range communications between vehicles, network communications via vehicle-to-network (V2N) links 358 and 310 may be used, such as for transmitting a car accident that occurred some distance ahead along a road or highway. The nodes may send other types of communications to the vehicles, such as traffic flow conditions, road hazard warnings, environmental / weather reports, and service station availability, among others. This data may be obtained from a cloud-based sharing service.

[0052] As described above, some systems supporting sidelink communications (e.g., NR Rel-16) may enable a UE to reserve resources for current and / or future transmissions. For example, resource allocation mode 2 in NR Rel-16 is a reservation-based resource allocation mode in which a UE may reserve (time-frequency) resources from a resource pool for one or more transmissions (to other UEs). The resource pool (or multiple resource pools) may be resources allocated for sidelink transmissions (e.g., configured by a base station (gNB)). The (sender) UE may send (e.g., broadcast) an SCI that includes an indication of resource reservations by the UE. The (receiver) UE may use the indication of resource reservations to determine when to suppress communications during resource reservations. A single SCI may include a maximum number of reservations (e.g., 2, 3, or 4 resource reservations), which may be a preconfigured value or may be configurable via control signaling (e.g., radio resource control (RRC) signaling) from a base station (e.g., BS110a, such as a gNB).

[0053] In some cases, there may be situations where one or more resource reservations (for future transmissions) made by a sending UE (during a current transmission) may be released by the sending UE (and possibly reclaimed by a receiving UE). For example, a given resource reservation for a future transmission may be releasable (e.g., allowing another UE to reclaim it) depending on whether hybrid automatic repeat request (HARQ) feedback is expected for the current transmission. For example, if the resource reservation is for a blind hybrid automatic repeat request (HARQ) (re)transmission of a TB currently being transmitted, the resource reservation may not depend on the HARQ feedback of the current TB transmission, and the resource reservation may not be releasable. Similarly, if the resource reservation is for a TB different from the current TB being transmitted, the resource reservation may not depend on the HARQ feedback of the current TB transmission, and the resource reservation may not be releasable. On the other hand, if the resource reservation is for a HARQ (re)transmission of a TB currently being transmitted and / or for the same TB as the current TB being transmitted, the resource reservation may depend on the HARQ feedback of the current TB transmission, and the resource reservation may be releasable.

[0054] However, in some systems, the sending UE may not be able to indicate in the SCI (and the receiving UE may not be able to determine from the SCI) whether the resource reservation of the sending UE can be released. Therefore, it is desirable to provide techniques that enable a sidelink device to indicate in the SCI and / or determine from the SCI whether a resource reservation can be released (e.g., is releasable). Doing so can improve the management of resource reservations in a communication system that supports sidelink communication.

[0055] Example of resource reservation and release in sidelink

[0056] Various aspects of the present disclosure provide techniques for improving the management of the release of resource reservations for sidelink communications. Specifically, various aspects provide techniques for enabling a (sender) UE to indicate to other UEs whether future reserved resources (e.g., for future transmissions of the sender UE) reserved in a current transmission (performed by the sender UE) are releasable. It should be noted that, as used herein, an indication of whether a resource reservation is "releasable" is an indication of whether the resource reservation "can" be released (e.g., has the possibility of being released), as compared to an indication that the resource reservation is "actually released." As described in more detail below, when the sender UE indicates that a resource reservation is "releasable," one or more other UEs may monitor a feedback channel to determine whether the resource reservation will be used and whether the resource reservation can be reclaimed.

[0057] Figure 4 4 is a flow chart illustrating example operations 400 for wireless communications according to certain aspects of the present disclosure. Operations 400 may be performed by a (first) UE (e.g., UE 120a or UE 120b in wireless communication network 100). For example, the (first) UE may be sending data to one or more other UEs as part of a sidelink communication. Operations 400 may be implemented as a processor (e.g., Figure 2 In addition, the communication may be performed, for example, via one or more antennas (e.g., Figure 2 The UE may transmit and receive signals in operation 400 using antenna 252. In some aspects, the UE may transmit and / or receive signals via a bus interface of one or more processors (e.g., controller / processor 280) that obtain and / or output signals.

[0058] Operation 400 may begin at 402, where a (first) UE determines at least one resource reservation from a resource pool that includes a plurality of time-frequency resources allocated for sidelink communications with one or more (second) UEs. At 404, the UE sends control information including a first indication of the at least one resource reservation and a second indication of whether the at least one resource reservation is releasable. In one aspect, the control information may indicate resources reserved for future transmissions of the UE in a current transmission of the UE. That is, the control information may be associated with a first transmission sent (by the first UE) at a first time, and the at least one resource reservation may be allocated to a second transmission to be sent (by the first UE) at a subsequent second time.

[0059] Figure 54 is a flow chart illustrating example operations 500 for wireless communications in accordance with certain aspects of the present disclosure. Operations 400 may be performed by a (first) UE (e.g., UE 120a or UE 120b in wireless communication network 100). For example, the (first) UE may be an intended recipient of a transmission from another sender UE and / or may not be an intended recipient of a transmission from a sender UE (e.g., the UE may be in the process of selecting resources for sidelink communications). Operations 500 may be implemented as a processor (e.g., Figure 2 In addition, the communication may be performed, for example, via one or more antennas (e.g., Figure 2 The UE may transmit and receive signals in operation 500 using antenna 252. In some aspects, the UE may transmit and / or receive signals via a bus interface of one or more processors (e.g., controller / processor 280) that obtain and / or output signals.

[0060] Operation 500 may begin at 502, where a (first) UE receives control information including: (i) a first indication by a second (sender) UE of at least one resource reservation from a resource pool, the resource pool including a plurality of time-frequency resources available for sidelink communications, and (ii) a second indication of whether the at least one resource reservation is releasable. In one aspect, the (first) UE may receive the control information as part of a current transmission by the (second) UE, where the resource reservation is for a future transmission by the (second) UE. That is, the control information may be associated with a first transmission sent by the second UE at a first time, and the at least one resource reservation may be allocated to a second transmission to be sent by the second UE at a subsequent second time.

[0061] At 504, the UE determines whether to reclaim the at least one resource reservation based at least in part on the control information. At 506, the UE selects a set of resource reservations from a resource pool for sidelink communications based on the determination.

[0062] In some aspects, the second indication in the SCI (e.g., in operations 402 and 502) may include an explicit indication of whether the at least one resource reservation is releasable. For example, the SCI may include a dedicated field having one or more bits to indicate whether the at least one resource reservation is releasable or not. In one aspect, the dedicated field may include a bitmap, each bit in the bitmap indicating whether a different resource reservation is releasable. For example, assuming that the SCI includes 4 resource reservations, the dedicated field may include "1011", which indicates that resource reservations (RR) 1, RR3, and RR4 (with bit value "1") are releasable, while RR2 (with bit value "0") is not releasable. However, it should be noted that this is merely a reference example, and other values ​​may be used to explicitly indicate whether a resource reservation is releasable.

[0063] In some aspects, the second indication in the SCI (e.g., in operations 402 and 502) may include an implicit indication of whether the at least one resource reservation is releasable. The implicit indication may be based on the type of resource reservation (also referred to herein as the type of transmission associated with the resource reservation). In one aspect, for example, the implicit indication may be an indication of at least one of the following: whether the transmission is for the same TB as the current transmission or a different TB, or whether the transmission is a feedback-based transmission or a non-feedback-based transmission.

[0064] In some aspects, the SCI may implicitly indicate whether the at least one resource reservation is releasable by the value of a field in the SCI. For example, the second indication may include an indication of whether the second transmission is a feedback-based transmission or a non-feedback-based transmission. If the second indication is used to indicate a feedback-based transmission, the resource reservation is releasable. Feedback-based transmission may include a transmission associated with HARQ feedback. For example, the resource reservation may be a HARQ (re) transmission for a TB being transmitted in the current transmission. In this case, whether the resource reservation is actually used may depend on the HARQ feedback of the current transmission. If a NACK is received, the transmitting UE may use the resource reservation to retransmit the TB. On the other hand, if an ACK is received, the transmitting UE may not use the resource reservation to retransmit the TB. In other HARQ feedback modes, if the current transmission is successful, the transmitting UE may not receive an ACK, but may receive a NACK only if the current transmission is unsuccessful. In this case, if an ACK is not received after a predetermined amount of time has passed since the transmission of the TB, the transmitting UE may not use the resource reservation to retransmit the TB.

[0065] If the second indication is used to indicate a non-feedback based transmission, the resource reservation may be non-releasable. A non-feedback based transmission may be a transmission that does not require HARQ feedback. An example of a non-feedback based transmission may include a blind HARQ (re)transmission of a TB. Another example of a non-feedback based transmission may include a transmission for a TB different from the TB currently being transmitted.

[0066] In some aspects, the SCI may implicitly indicate whether the at least one resource reservation is releasable by the value of the MCS field in the SCI. For example, the second indication (e.g., in operation 402) may include an indication of at least one MCS. If the value of the MCS field (or MCS index) satisfies a predetermined condition, the resource reservation may be releasable. If the value of the MCS field does not satisfy the predetermined condition, the resource reservation may be non-releasable. In one aspect, the predetermined condition may be a reserved MCS index.

[0067] In some aspects, the second indication (e.g., in operation 402) may include an indication of whether the second transmission is for the same TB as the first transmission. For example, if the second transmission is for the same TB as the first transmission, the at least one resource reservation (which is allocated to the second transmission) may be releasable. On the other hand, if the second transmission is for a different TB than the first transmission, the at least one resource reservation (which is allocated to the second transmission) may be non-releasable.

[0068] In some aspects, if the second indication is used to indicate that the second transmission is for a different TB than the first transmission, this may further implicitly indicate that the first transmission and the second transmission are associated with the same service data unit (SDU). That is, the SCI may implicitly indicate that the resource reservation is for a different TB that is a fragment of the same radio link control (RLC) service data unit (SDU) as the current TB being transmitted. For example, in some systems, a single SCI may not be able to indicate resource reservation for a different TB that belongs to a different SDU than the current TB being transmitted.

[0069] Similarly, in some aspects, a UE receiving an SCI (e.g., in operation 502) may determine whether a resource reservation is releasable based on an explicit indication in the SCI or an implicit indication in the SCI. If at least one resource reservation is releasable and at least one resource reservation has been released, the UE (e.g., in operation 504) may determine to reclaim the at least one resource reservation. In one aspect, the UE (e.g., in operation 504) may monitor a feedback channel to determine whether the at least one resource reservation has been released. For example, if an ACK is detected for a first transmission or an ACK is not detected after a predetermined amount of time (after the first transmission), the UE may determine that the resource reservation will no longer be used (e.g., the resource reservation has been released). In another example, if a NACK is detected for the first transmission, the UE may determine that the resource reservation will be used (e.g., the resource reservation has not been released).

[0070] Figure 6 A communication device 600 is shown that may include various components (eg, corresponding to functional unit components), wherein these components are configured to perform operations of the techniques disclosed herein (eg, Figure 4-5 ). The communication device 600 includes a processing system 614 coupled to a transceiver 612. The transceiver 612 is configured to send and receive signals (e.g., various signals described herein) for the communication device 600 via an antenna 620. The processing system 614 can be configured to perform processing functions for the communication device 600, including processing signals received and / or to be sent by the communication device 600.

[0071] The processing system 614 includes a processor 608 coupled to a computer readable medium / memory 610 via a bus 624. In some aspects, the computer readable medium / memory 610 is configured to store instructions that, when executed by the processor 608, cause the processor 608 to perform Figure 4-5 The operations shown in and / or other operations for performing the various techniques discussed herein.

[0072] In some aspects, the processing system 614 also includes a communication component 602 for performing Figure 4 404 in Figure 5 502 in the above, and / or other communication operations described herein. In addition, the processing system 614 includes a side link resource manager 122 for performing Figure 4 402 and Figure 5The operations shown in 504 and 506 of and / or the operations described herein. The communication component 602 and the lateral link resource manager 122 may be coupled to the processor 608 via the bus 624. In some aspects, the communication component 602 and the lateral link resource manager 122 may be hardware circuits. In some aspects, the communication component 602 and the lateral link resource manager 122 may be software components that are executed and run on the processor 608.

[0073] The techniques described herein can be used for various wireless communication technologies, for example, NR (e.g., 5G NR), 3GPP Long Term Evolution (LTE), Advanced LTE (LTE-A), Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), Orthogonal Frequency Division Multiple Access (OFDMA), Single Carrier Frequency Division Multiple Access (SC-FDMA), Time Division Synchronous Code Division Multiple Access (TD-SCDMA), and other networks. The terms "network" and "system" are often used interchangeably. A CDMA network can implement radio technologies such as Universal Terrestrial Radio Access (UTRA), cdma2000, and the like. UTRA includes Wideband CDMA (WCDMA) and other variants of CDMA. cdma2000 covers IS-2000, IS-95, and IS-856 standards. A TDMA network can implement radio technologies such as Global System for Mobile Communications (GSM). OFDMA networks may implement radio technologies such as NR (e.g., 5G RA), Evolved UTRA (E-UTRA), Ultra Mobile Broadband (UMB), IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, Flash-OFDMA, and the like. UTRA and E-UTRA are part of Universal Mobile Telecommunications System (UMTS). LTE and LTE-A are releases of UMTS that use E-UTRA. UTRA, E-UTRA, UMTS, LTE, LTE-A, and GSM are described in documents from an organization named "3rd Generation Partnership Project" (3GPP). cdma 2000 and UMB are described in documents from an organization named "3rd Generation Partnership Project 2" (3GPP2). NR is an emerging wireless communication technology under development.

[0074] The technology described herein can be used for the wireless networks and radio technologies mentioned above as well as other wireless networks and radio technologies. For the sake of clarity, although the terms commonly associated with 3G, 4G and / or 5G wireless technologies are used herein to describe various aspects, various aspects of the present disclosure may also be applied to communication systems based on other generations.

[0075] In 3GPP, the term "cell" may refer to the coverage area of ​​a Node B (NB) and / or a NB subsystem serving the coverage area, depending on the context in which the term "cell" is used. In NR systems, the terms "cell" and BS, next-generation Node B (gNB or gNodeB), access point (AP), distributed unit (DU), operator or transmission reception point (TRP) may be used interchangeably. A BS may provide communication coverage for a macro cell, a pico cell, a femto cell and / or other types of cells. A macro cell may cover a relatively large geographic area (e.g., a radius of several kilometers), which allows unrestricted access to UEs with service subscriptions. A pico cell may cover a relatively small geographic area, which allows unrestricted access to UEs with service subscriptions. A femto cell may cover a relatively small geographic area (e.g., a home), which allows restricted access to UEs associated with the femto cell (e.g., UEs in a closed subscriber group (CSG), UEs for users in the home, etc.). A BS for a macro cell may be referred to as a macro BS. A BS for a pico cell may be referred to as a pico BS. A BS for a femto cell may be called a femto BS or a home BS.

[0076] UE may also be referred to as a mobile station, a terminal, an access terminal, a subscriber unit, a station, a customer premises equipment (CPE), a cellular phone, a smart phone, a personal digital assistant (PDA), a wireless modem, a wireless communication device, a handheld device, a laptop computer, a cordless phone, a wireless local loop (WLL) station, a tablet computer, a camera, a gaming device, a netbook, a smartbook, an ultrabook, a home appliance, a medical device or medical apparatus, a biosensor / device, a wearable device such as a smart watch, smart clothes, smart glasses, a smart bracelet, smart jewelry (e.g., a smart bracelet, a smart bracelet, etc.), an entertainment device (e.g., a music device, a video device, a satellite radio device, etc.), a vehicle component or sensor, a smart meter / sensor, an industrial manufacturing device, a global positioning system device, or any other suitable device configured to communicate via a wireless or wired medium. Some UEs may be considered as machine type communication (MTC) devices or evolved MTC (eMTC) devices. For example, MTC and eMTC UEs include robots, drones, remote devices, sensors, meters, monitors, location tags, etc. that can communicate with a BS, another device (e.g., a remote device), or some other entity. A wireless node may provide connectivity for or to a network (e.g., a wide area network such as the Internet or a cellular network), for example, via a wired or wireless communication link. Some UEs may be considered Internet of Things (IoT) devices, which may be narrowband IoT (NB-IoT) devices.

[0077] Some wireless networks (e.g., LTE) utilize orthogonal frequency division multiplexing (OFDM) on the downlink and single carrier frequency division multiplexing (SC-FDM) on the uplink. OFDM and SC-FDM divide the system bandwidth into multiple (K) orthogonal subcarriers, which are also commonly referred to as tones, frequencies, etc. Each subcarrier can be modulated with data. Typically, modulation symbols are sent in the frequency domain using OFDM and in the time domain using SC-FDM. The spacing between adjacent subcarriers can be fixed, and the total number of subcarriers (K) can depend on the system bandwidth. For example, the spacing of the subcarriers can be 15kHz, and the minimum resource allocation (which is called a "resource block" (RB)) can be 12 subcarriers (or 180kHz). Therefore, for system bandwidths of 1.25, 2.5, 5, 10, or 20 megahertz (MHz), the nominal fast Fourier transform (FFT) size can be equal to 128, 256, 512, 1024, or 2048, respectively. The system bandwidth may also be divided into some subbands. For example, one subband may cover 1.08 MHz (i.e., 6 RBs), and there may be 1, 2, 4, 8, or 16 subbands for system bandwidths of 1.25, 2.5, 5, 10, or 20 MHz, respectively. In LTE, the basic transmission time interval (TTI) or packet duration is a 1 ms subframe.

[0078] NR can utilize OFDM with CP on both the uplink and downlink, and includes support for half-duplex operation using TDD. In NR, the subframe is still 1ms, but the basic TTI is called a time slot. A subframe contains a variable number of time slots (e.g., 1, 2, 4, 8, 16, ... time slots) depending on the subcarrier spacing. NR RB is 12 consecutive frequency subcarriers. NR can support a basic subcarrier spacing of 15KHz, and other subcarrier spacings (e.g., 30kHz, 60kHz, 120kHz, 240kHz, etc.) can be specified relative to the basic subcarrier spacing. Symbol and time slot lengths scale with subcarrier spacing. The CP length also depends on the subcarrier spacing. Beamforming can be supported, and the beam direction can be dynamically configured. MIMO transmission with precoding can also be supported. In some examples, the MIMO configuration in the DL can support up to 8 transmit antennas with up to 8 streams in multi-layer DL transmission and up to 4 streams per UE. In some examples, multi-layer transmission of up to 2 streams per UE can be supported. Aggregation of multiple cells up to 8 serving cells can be supported.

[0079] In some examples, access to the air interface may be scheduled. A scheduling entity (e.g., BS) allocates resources for communications between some or all devices and equipment within its service area or cell. A scheduling entity may be responsible for scheduling, allocating, reconfiguring, and releasing resources for one or more subordinate entities. That is, for scheduled communications, subordinate entities utilize resources allocated by the scheduling entity. The base station is not the only entity that acts as a scheduling entity. In some examples, a UE may act as a scheduling entity, and resources for one or more subordinate entities (e.g., one or more other UEs) may be scheduled, and other UEs may utilize the resources scheduled by the UE for wireless communications. In some examples, a UE may act as a scheduling entity in a peer-to-peer (P2P) network and / or a mesh network. In a mesh network example, UEs may communicate directly with each other in addition to communicating with a scheduling entity.

[0080] In some examples, two or more slave entities (e.g., UEs) can communicate with each other using sidelink signals. Practical applications of such sidelink communications may include public safety, proximity services, UE-to-network relay, vehicle-to-vehicle (V2V) communications, Internet of Everything (IoE) communications, Internet of Things communications, mission-critical grids, and / or various other appropriate applications. Generally, a sidelink signal may refer to a signal that is transmitted from one slave entity (e.g., UE1) to another slave entity (e.g., UE2) without relaying the communication through a scheduling entity (e.g., UE or BS), even if the scheduling entity may be used for scheduling and / or control purposes. In some examples, licensed spectrum may be used to transmit sidelink signals (unlike wireless local area networks that typically use unlicensed spectrum).

[0081] The disclosed methods herein include one or more steps or actions for implementing these methods. Without departing from the scope of protection of the present invention, these method steps and / or actions can be interchangeable. In other words, unless a specific order of steps or actions is specified, the order and / or use of specific steps and / or actions can be modified without departing from the scope of protection of the present invention.

[0082] As used herein, a phrase referring to "at least one of" a list of items refers to any combination of those items, including single members. For example, "at least one of a, b, or c" is intended to cover: a, b, c, ab, ac, bc, and abc, as well as any combination with multiple of the same elements (e.g., aa, aaa, aab, aac, abb, acc, bb, bbb, bbc, cc, and ccc or any other ordering of a, b, and c).

[0083] As used herein, the term "determine" encompasses a wide variety of actions. For example, "determine" may include calculating, computing, processing, deriving, investigating, querying (e.g., querying a table, a database, or other data structure), ascertaining, and the like. In addition, "determine" may also include receiving (e.g., receiving information), accessing (e.g., accessing data in a memory), and the like. In addition, "determine" may also include resolving, selecting, choosing, establishing, and the like.

[0084] To enable any person of ordinary skill in the art to implement the various aspects described herein, the above description is made around various aspects. It is obvious to those of ordinary skill in the art that various modifications to these aspects are possible, and the general principles defined herein may also be applicable to other aspects. Therefore, the present invention is not limited to the aspects shown herein, but is consistent with the full scope of the present invention, wherein, unless otherwise specified, modifying a certain component in the singular form does not mean "one and only one", but may be "one or more". Unless otherwise specifically stated, the term "some" refers to one or more. All structural and functional equivalents of the components of the various aspects described throughout the present disclosure are expressly incorporated herein by reference, and are intended to be covered by the claims, and these structural and functional equivalents are known or will be known to those of ordinary skill in the art. In addition, no disclosure herein is intended to be dedicated to the public, regardless of whether such disclosure is clearly recorded in the claims. In addition, any claim element should not be interpreted under 35 U.S.C. §112, paragraph 6, unless the element is explicitly recited using the wording of “functional means” or, in a method claim, the element is recited using the wording of “functional step.”

[0085] The various operations of the methods described above may be performed by any suitable unit capable of performing the corresponding functions. These units may include various hardware and / or software components and / or modules, including but not limited to: circuits, application specific integrated circuits (ASICs) or processors. Generally, where operations are shown in the accompanying drawings, these operations may have corresponding paired functional module components that are similarly numbered.

[0086] A general purpose processor, digital signal processor (DSP), application specific integrated circuit (ASIC), field programmable gate array (FPGA) or other programmable logic device (PLD), discrete gate or transistor logic, discrete hardware components or any combination thereof for performing the functions described herein may implement or perform various exemplary logic blocks, modules and circuits described in conjunction with the contents disclosed herein. A general purpose processor may be a microprocessor, or the processor may be any commercially available processor, controller, microcontroller or state machine. A processor may also be implemented as a combination of computing devices, for example, a combination of a DSP and a microprocessor, a plurality of microprocessors, a combination of one or more microprocessors and a DSP core, or any other such structure.

[0087] When implemented in hardware, an exemplary hardware configuration may include a processing system in a wireless node. The processing system may be implemented using a bus architecture. Depending on the specific application and overall design constraints of the processing system, the bus may include any number of interconnected buses and bridges. The bus may link together various circuits including a processor, a machine-readable medium, and a bus interface. The bus interface may be used to connect a network adapter, etc., to the processing system via the bus. The network adapter may be used to implement signal processing functions at the physical layer. In the user terminal 120 (see Figure 1 ), a user interface (e.g., keyboard, display, mouse, joystick, etc.) may also be connected to the bus. The bus also links various other circuits such as clock sources, peripherals, voltage regulators, power management circuits, etc., which are well known in the art and are not described any further. The processor may be implemented using one or more general purpose processors and / or special purpose processors. Examples include microprocessors, microcontrollers, DSP processors, and other circuits capable of executing software. One of ordinary skill in the art will recognize how to best implement the described functionality of the processing system depending on the specific application and the overall design constraints imposed on the entire system.

[0088] When implemented using software, these functions can be stored on a computer-readable medium or transmitted as one or more instructions or codes on a computer-readable medium. Software should be broadly interpreted as meaning instructions, data, or any combination thereof, etc., whether it is referred to as software, firmware, middleware, microcode, hardware description language, or other terms. Computer-readable media include computer storage media and communication media, wherein the communication medium includes any medium that facilitates the transmission of a computer program from one place to another. The processor can be responsible for managing the bus and general processing, which includes executing the software stored on the machine-readable storage medium. The computer-readable storage medium can be coupled to the processor so that the processor can read information from the storage medium and write information to the storage medium. Alternatively, the storage medium can also be a part of the processor. For example, the machine-readable medium can include a transmission line, a carrier waveform modulated with data, and / or a computer-readable storage medium with instructions stored thereon separated from the wireless node, all of which can be accessed by the processor through a bus interface. Alternatively or additionally, the machine-readable medium or any part thereof can be a component of the processor, for example, the case can be a cache and / or a general register file. For example, examples of machine-readable storage media may include RAM (random access memory), flash memory, ROM (read-only memory), PROM (programmable read-only memory), EPROM (erasable programmable read-only memory), EEPROM (electrically erasable programmable read-only memory), registers, magnetic disks, optical disks, hard disks, or any other suitable storage media, or any combination thereof. Machine-readable media may be embodied in a computer program product.

[0089] A software module may include a single instruction or multiple instructions, and the software module may be distributed over several different code segments, distributed among different programs, and distributed among multiple storage media. A computer-readable medium may include multiple software modules. These software modules include instructions that, when executed by a device such as a processor, cause a processing system to perform various functions. A software module may include a transmission module and a receiving module. Each software module may be located in a single storage device or distributed among multiple storage devices. For example, when a triggering event occurs, a software module may be loaded from a hard disk into a RAM. During the execution of the software module, the processor may load some of these instructions into a cache to increase access speed. Subsequently, one or more cache lines may be loaded into a general register file for execution by the processor. When referring to the function of the following software module, it should be understood that the function is implemented by the processor when executing instructions from the software module.

[0090] Moreover, any connection may be properly referred to as a computer-readable medium. For example, if the software is transmitted from a website, server or other remote source using a coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared (IR), wireless and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, wireless and microwave are included in the definition of the medium. As used herein, disk and disc include compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disk and Optical disks, where magnetic disks typically reproduce data magnetically, and optical disks use lasers to reproduce data optically. Thus, in some aspects, computer-readable media may include non-transitory computer-readable media (e.g., tangible media). Additionally, for other aspects, computer-readable media may include temporary computer-readable media (e.g., signals). Combinations of the above should also be included within the scope of protection of computer-readable media.

[0091] Thus, certain aspects may include a computer program product for performing the operations presented herein. For example, the computer program product may include a computer-readable medium having instructions stored thereon (and / or encoded thereon), which instructions may be executed by one or more processors to perform the operations described herein (e.g., for performing the operations described herein and in Figure 4 and / or Figure 5 ).

[0092] In addition, it should be understood that the modules and / or other appropriate units for performing the methods and techniques described herein can be downloaded and / or obtained on demand by a user terminal and / or a base station. For example, such a device can be coupled to a server to facilitate the implementation of a unit for transmitting and performing the methods described herein. Alternatively, the various methods described herein can be provided by a storage unit (e.g., RAM, ROM, a physical storage medium such as a compact disc (CD) or a floppy disk, etc.), so that when a user terminal and / or a base station couples the storage unit to or provides it to the device, the various methods can be obtained. In addition, any other appropriate technology for providing the methods and techniques described herein to a device can also be used.

[0093] It should be understood that the present invention is not limited to the precise configuration and components shown above. Various modifications, changes and variations may be made to the arrangement, operation and details of the methods and devices described above without departing from the scope of the present invention.

Claims

1. A method for wireless communication by a first user equipment (UE), comprising: reserving at least one resource from a resource pool, the resource pool comprising a plurality of time-frequency resources allocated for sidelink communications with one or more second UEs, wherein reserving the at least one resource results in at least one resource reservation; and Send control information including a first indication of the at least one resource reservation and a second indication of whether the at least one resource reservation can be released, wherein the second indication indicates whether the at least one resource reserved by the first UE can be reclaimed by the one or more second UEs based on the at least one resource being used for feedback-based transmission.

2. The method according to claim 1, wherein: The control information is associated with a first transmission sent at a first time, and the at least one resource reservation is allocated to a second transmission to be sent at a subsequent second time.

3. The method according to claim 1, wherein: The second indication comprises an explicit indication of whether the at least one resource reservation is releasable.

4. The method according to claim 2, wherein: The second indication comprises an implicit indication of whether the at least one resource reservation is releasable.

5. The method according to claim 4, wherein: The implicit indication is used to indicate whether the second transmission is the feedback-based transmission or the non-feedback-based transmission.

6. The method according to claim 5, wherein: The feedback-based transmissions include transmissions associated with hybrid automatic repeat request (HARQ) feedback; and The non-feedback based transmissions include transmissions that do not require hybrid automatic repeat request (HARQ) feedback.

7. The method according to claim 5, wherein: The at least one resource reservation is releasable when the second transmission is the feedback-based transmission.

8. The method according to claim 5, wherein: When the second transmission is a non-feedback based transmission, the at least one resource reservation is non-releasable.

9. The method according to claim 4, wherein: The implicit indication is used to indicate whether the second transmission is for the same transport block as the first transmission.

10. The method according to claim 9, wherein: The at least one resource reservation is releasable when the second transmission is for the same transport block as the first transmission.

11. The method according to claim 9, wherein: The at least one resource reservation is non-releasable when the second transmission is for a different transport block than the first transmission.

12. The method according to claim 9, wherein: The implicit indication is used to indicate that the second transmission is for a transport block different from that of the first transmission; and The first transmission and the second transmission are associated with the same service data unit (SDU).

13. An apparatus for wireless communication, comprising: at least one processor configured to reserve at least one resource from a resource pool, the resource pool comprising a plurality of time-frequency resources allocated for sidelink communications with one or more other apparatuses, wherein reserving the at least one resource results in at least one resource reservation; a transmitter configured to send control information including a first indication of the at least one resource reservation and a second indication of whether the at least one resource reservation is releasable, wherein the second indication indicates whether the at least one resource reserved by the apparatus is reclaimable by one or more user equipments (UEs) based on the at least one resource being used for feedback-based transmission; and A memory is coupled to the at least one processor.

14. The device according to claim 13, wherein: The second indication includes: (i) an explicit indication of whether the at least one resource reservation is releasable, or (ii) an implicit indication of whether the at least one resource reservation is releasable.

15. A method for wireless communication by a first user equipment (UE), comprising: receiving control information comprising: (i) a first indication of at least one resource reservation by a second UE from a resource pool, the resource pool comprising a plurality of time-frequency resources that can be used for sidelink communication, and (ii) a second indication of whether the at least one resource reservation is releasable, wherein the at least one resource reservation comprises a reservation of at least one resource by the second UE from the resource pool, and wherein the second indication indicates whether the at least one resource reserved by the second UE can be reclaimed by the first UE based on the at least one resource being used for feedback-based transmission; reclaiming the at least one resource reservation based at least in part on the control information; and Based on reclaiming the at least one resource reservation, a set of resource reservations is selected from the resource pool for sidelink communications.

16. The method according to claim 15, wherein: The control information is associated with a first transmission sent by the second UE at a first time, and the at least one resource reservation is allocated to a second transmission to be sent by the second UE at a subsequent second time.

17. The method according to claim 15, wherein: The second indication comprises an explicit indication of whether the at least one resource reservation is releasable.

18. The method according to claim 16, wherein: The second indication comprises an implicit indication of whether the at least one resource reservation is releasable.

19. The method according to claim 18, wherein: The implicit indication is used to indicate whether the second transmission is the feedback-based transmission or the non-feedback-based transmission.

20. The method of claim 19, wherein: The feedback-based transmissions include transmissions associated with hybrid automatic repeat request (HARQ) feedback; and The non-feedback based transmissions include transmissions that do not require hybrid automatic repeat request (HARQ) feedback.

21. The method of claim 19, further comprising: When the second transmission is the feedback-based transmission, determining that the at least one resource reservation is releasable.

22. The method according to claim 19, wherein: When the second transmission is a non-feedback based transmission, the at least one resource reservation is non-releasable.

23. The method according to claim 18, wherein: The implicit indication is used to indicate whether the second transmission is for the same transport block as the first transmission.

24. The method according to claim 23, further comprising: The at least one resource reservation is releasable when the second transmission is for the same transport block as the first transmission.

25. The method according to claim 23, wherein: The at least one resource reservation is non-releasable when the second transmission is for a different transport block than the first transmission.

26. The method of claim 15, wherein: When the at least one resource reservation is releasable and the at least one resource reservation has been released, the at least one resource reservation is reclaimed.

27. The method according to claim 26, further comprising: A feedback channel is monitored to determine whether the at least one resource reservation has been released.

28. The method of claim 15, wherein: The at least one resource reservation is not reclaimed when at least one of the following is satisfied: (i) the at least one resource reservation is not releasable, or (ii) the at least one resource reservation is not released.

29. An apparatus for wireless communication, comprising: a receiver configured to receive control information, the control information comprising (i) a first indication of at least one resource reservation made by another apparatus from a resource pool, the resource pool comprising a plurality of time-frequency resources that can be used for sidelink communications, and (ii) a second indication of whether the at least one resource reservation is releasable, wherein the at least one resource reservation comprises a reservation of at least one resource from the resource pool by a user equipment (UE), and wherein the second indication indicates whether the at least one resource reserved by the UE can be reclaimed by the apparatus based on the at least one resource being used for feedback-based transmission; At least one processor configured to: reclaiming the at least one resource reservation based at least in part on the control information; and selecting a set of resource reservations from the resource pool for sidelink communications based on reclaiming the at least one resource reservation; and A memory is coupled to the at least one processor.

30. The device according to claim 29, wherein: The second indication includes (i) an explicit indication of whether the at least one resource reservation is releasable, or (ii) an implicit indication of whether the at least one resource reservation is releasable.

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