Method, forward packet, user equipment and computer software

Abstract

The present invention relates to a method comprising: obtaining a first set of radio resources available for transmitting a forward packet from a first user equipment; obtaining a second set of radio resources available for performing operations related to the forward packet; selecting a first radio resource having a first time among the radio resources of the first set such that at least one second radio resource from a second set is included in a time window, the time window has a lower bound after the first time and an upper bound defined according to at least one of the forward packets; the forward packet is transmitted by the first user equipment using the first radio resource.

Description

Field of the Invention

[0001] The present disclosure relates to the field of wireless communication systems.

[0002] More specifically, it relates to the field of radio resource selection. Background Art

[0003] Wireless communication systems allow devices to communicate wirelessly. To allow seamless interaction of devices from a large number of different manufacturers, wireless communication generally complies with radio communication standards, such as those established by IEEE (e.g., IEEE 802.11 for WI-FI communication) or those established by 3GPP (e.g., 3G, 4G, or 5G standards for cellular network communication).

[0004] Most radio communication standards rely on the selection of radio resources for wireless communication. Each radio resource can be assigned to a single wireless device to prevent the radio resource from being used by multiple devices, thus preventing interference in wireless communication.

[0005] In existing systems, a wireless device requests radio resources when it needs to send a message. However, this only provides radio resources for sending the message. In certain cases, some further operations need to be performed after sending the message. For example:

[0006] - If the first transmission fails, the message may need to be sent again;

[0007] - After the message has been sent, some measurements may need to be performed within a limited time;

[0008] - After sending the first message, a response message may need to be received within a bounded time.

[0009] In each of these exemplary cases, compliance with the time limit depends on the availability of future radio resources, and existing schemes for selecting radio resources cannot guarantee this.

[0010] For example, some applications for closed-loop control (e.g., motion control) are based on a working mode that requires round-trip information interaction. The round-trip is characterized by the transmission time and / or the transmission of a response or backward packet whose content is completely determined by the arrival time and content of the request or forward packet. Then the performance of these applications depends on the time of this round-trip, i.e., the round-trip time (RTT).

[0011] RTT is an application metric that is generally unknown to lower layers (e.g., the access layer). In 5G NR, the physical layer only knows the remaining packet delay budget (PDB) for transmitting data packets or transport blocks. The PDB is an upper bound on the time for the transmitter to send a packet. Due to radio conditions, some transmissions may fail and require some retransmissions. Then it is difficult to know exactly when a packet is successfully received with high precision. Therefore, the experimental round-trip time will be significantly lower than the sum of the PDBs from one pair of forward-backward packets to another pair of forward-backward packets. This time-varying RTT or jitter is harmful to application performance.

[0012] Existing solutions fail to ensure that the RTT is met after the first message is sent. More generally, existing solutions fail to ensure compliance with any time constraints that depend on radio communication and are related to the transmission of the first message.

[0013] Therefore, there is a need for a radio resource selection method that allows ensuring compliance with time constraints related to operations resulting from the transmission of the first message. SUMMARY OF THE INVENTION

[0014] The present disclosure improves this situation.

[0015] A method is proposed, which includes the following steps: obtaining a first set of radio resources available for sending a forward packet from a first user equipment; obtaining a second set of radio resources available for performing operations related to the forward packet; obtaining at least one first radio resource associated with at least one first time among the radio resources of the first set, such that at least one second radio resource from the second set is included in a time window with a lower bound after the at least one first time; using the at least one first radio resource by the first user equipment to send the forward packet.

[0016] By radio resources available for sending a forward packet from a first user equipment, we mean radio resources determined to be suitable for sending a forward packet by the first user equipment. This determination can be performed, for example, by determining for each radio resource whether it is suitable for sending a packet by the first user equipment, or conversely by excluding resources determined to be unsuitable for sending a packet. This can be performed, for example, by the first user equipment screening its environment and / or by the process defined in standard TS38.214 / 8.1.4. The screening of the environment can be a sensing process, for example.

[0017] "Operations related to a forward packet", we mean operations that are caused by a forward packet and are expected to be the result of the transmission of the forward packet and that require the use of radio resources. For example, such an operation can be receiving a backward packet in response to a forward packet, measuring on a radio network after transmitting a forward packet, or transmitting another forward packet related to the forward packet (e.g., another packet sent by the same application).

[0018] "Radio resources available for performing an operation", we mean radio resources that are determined to be suitable for use in an operation.

[0019] "At least one first radio resource associated with at least one first time", we mean that at least one first time is respectively associated with at least one first radio resource. Each first radio resource is associated with a first time, and the first time corresponds to the time when the first radio resource can be used.

[0020] A single first radio resource or multiple radio resources can be obtained at the same time. For example, multiple first radio resources are obtained at the same time to plan to use multiple radio resources to transmit multiple forward packets. In another example, multiple first radio resources are obtained at the same time to plan to use multiple radio resources to continuously retransmit the same forward packet.

[0021] This ensures that a second radio resource can be selected that complies with the time limit related to the forward packet.

[0022] In another aspect, a method is proposed that includes the following steps: receiving, by a second user equipment in D2D communication, a forward packet from a first user equipment using a first radio resource having a first time; selecting a second radio resource available for the second user equipment to send a backward packet related to the forward packet in a time window that includes a lower bound after the first time and an upper bound defined according to at least one of the forward packet and the first time; and sending, by the second user equipment using the second radio resource, the backward packet to the first user equipment.

[0023] In another aspect, a forward packet is proposed that is sent by a first user equipment using a first radio resource having a first time, the first radio resource being selected among a first set of radio resources available for sending the forward packet from the first user equipment, such that at least one second resource from a second set of radio resources available for performing operations related to the forward packet is included in a time window having a lower bound after the first time.

[0024] In another aspect, a user equipment is proposed that includes at least one processor configured to execute a method according to one of the embodiments of the present disclosure.

[0025] In another aspect, there is provided a computer software including instructions that, when executed by a processor, implement at least a part of the method according to one of the embodiments of the present disclosure.

[0026] In another aspect, there is provided a computer-readable non-transitory recording medium having software registered thereon that, when executed by a processor, implements the method according to one of the embodiments of the present disclosure.

[0027] In another aspect, there is provided a user equipment including at least one processor configured to execute at least a part of the method as defined herein when the software is executed by the processor.

[0028] In another aspect, there is provided a computer software including instructions that, when executed by a processor, implement at least a part of the method as defined herein.

[0029] In another aspect, there is provided a computer-readable non-transitory recording medium having software registered thereon that, when executed by a processor, implements the method as defined herein.

[0030] The following features may be implemented optionally, implemented individually, or implemented in combination with each other:

[0031] In various embodiments of the present invention, the first radio resource is selected such that the number of second radio resources from a second set in a time window is at least equal to a threshold of the number of radio resources.

[0032] This ensures that the number of radio resources available in the second set for performing operations is at least equal to the threshold, so as to obtain a sufficient probability that at least one resource of the second set in the time window will be actually available at the time of requesting the second resource.

[0033] In various embodiments of the present invention, the radio resources of the first set and the radio resources of the second set are obtained in a global time window having a global upper bound.

[0034] This allows ensuring that radio resources will be selected such that the last possible time for selecting radio resources from the second set complies with the operation constraints.

[0035] In various embodiments of the present invention, the time window has an upper bound defined according to at least one of the forward packet and the first time.

[0036] "Upper bound defined according to at least one of the forward packet and the first time", we mean a time that depends on the forward packet and / or the first time. For example, the forward packet may be related to a time threshold for performing an operation that can be applied after the first time, a maximum time for performing the operation, etc.

[0037] This allows ensuring that radio resources will be available for performing an operation within a time range that complies with the time limit defined by the forward packet and the first time associated therewith. In particular, if the operation is to receive a backward packet, this allows ensuring that the time constraints of the communication are met.

[0038] In various embodiments of the present invention, the upper bound is defined as a maximum threshold after the first time.

[0039] This allows ensuring that radio resources will be available for performing an operation within a time range of a limited time after the time of sending the forward packet. In particular, if the operation is to receive a backward packet, this allows ensuring that the time constraints of the communication are met.

[0040] In various embodiments of the present invention, the method includes iteratively modifying one or more parameters of one or more of the following steps while not complying with at least one selection criterion: obtaining a first set of radio resources; obtaining a second set of radio resources; and selecting a first radio resource.

[0041] This allows selecting the best first radio resource by modifying the parameter selection until a suitable radio resource can be selected.

[0042] In various embodiments of the present invention, the method includes the step of associating at least one data related to an indication of performing an operation related to the forward packet with the forward packet.

[0043] "At least one data related to an indication of performing an operation related to the forward packet", we mean data related to performing an operation related to the forward packet. This may, for example, be a constraint related to the operation, such as a limit time or an indication of radio resources that can be selected to send a backward packet in response to the forward packet.

[0044] This allows the recipient of the forward packet to benefit from all relevant information for performing an operation related to the forward packet.

[0045] In various embodiments of the present invention, the operation includes sending (S51) a backward packet related to the forward packet to a first device.

[0046] "Backward packet related to the forward packet", we mean a backward packet that is transmitted as a result of the transmission of the forward packet and is expected to be the result of the forward packet transmission. For example, the backward packet may include a response to the content of the forward packet. This response may be generated by the application that receives the backward packet.

[0047] In various embodiments of the present invention, the radio resources of the second set include radio resources that can be used by the first user equipment to receive the backward packet.

[0048] "Radio resources that can be used by the first user equipment to receive the backward packet", we mean radio resources that are determined to be suitable for the first user equipment to receive the backward packet.

[0049] This ensures that the resources in the second set will actually allow the first user equipment to receive the backward packet.

[0050] In various embodiments of the present invention, the first user equipment sends a forward packet to the second user equipment that performs D2D communication with the first user equipment; the second user equipment sends a backward packet to the first user equipment.

[0051] This allows compliance with the time constraints of D2D communication.

[0052] In various embodiments of the present invention, the radio resources of the second set are obtained based on at least one data related to the ability of the second user equipment to send the backward packet to the first user equipment.

[0053] "Data related to the ability of the second user equipment to send the data packet to the user equipment", we mean any type of data that provides an indication of the ability of the second user equipment to use radio resources to send data packets.

[0054] This allows ensuring that the radio resources in the second set allow both the second user equipment to transmit the backward packet and the first user equipment to receive it.

[0055] In various embodiments of the present invention, the method includes the following steps: associating at least one data related to the selection of radio resources by the second user equipment with the forward packet.

[0056] "At least one data related to the selection of radio resources by the second user equipment", we mean at least one data that provides the second user equipment with insights into the radio resources to be selected or selection constraints that comply with the time requirements of the communication.

[0057] This increases the chance for the second user equipment to select, among the possible radio resources for sending the backward packet, radio resources that can be received by the first user equipment and / or comply with the operation constraints during the time window.

[0058] Other features, details, and advantages will be shown in the following detailed description and the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] Figure 1 Figure 1 An example of a first user equipment in multiple embodiments of the present invention is shown.

[0060] Figure 2 Figure 2 An example of two user equipments in device - to - device communication in multiple embodiments of the present invention is shown.

[0061] Figure 3 Figure 3 A first example of a method in multiple embodiments of the present invention is shown.

[0062] Figure 4 Figure 4 A second example of a method in multiple embodiments of the present invention including iterative modification of parameters is shown.

[0063] Figure 5 Figure 5 A third example of a method in multiple embodiments of the present invention is shown.

[0064] Figure 6 Figure 6 A fourth example of a method in multiple embodiments of the present invention including the step of adding information in a forward packet is shown.

[0065] Figure 7 Figure 7 A fifth example of a method in multiple embodiments of the present invention performed by a second user equipment is shown.

[0066] Figure 8 Figure 8 A first example of the selection of a first radio resource in multiple embodiments of the present invention is shown.

[0067] Figure 9 Figure 9 A second example of the selection of a first radio resource in multiple embodiments of the present invention is shown. DETAILED DESCRIPTION

[0068] Now refer to Figure 1 .

[0069] Figure 1 ​​​​​​​​​​​​​​​​​​A first user equipment user UE1 that emits radio signals is shown. It is requested that user equipment 1 can be within the coverage of base station 3. The communication with the radio signals can be, for example, an OFDM-based transmission. The requested user equipment 1 is a mobile device participating in communication (such as communication with base station 3 in the context of a standard LTE or NR, vehicle-to-everything (V2X) communication). More generally, the requested user equipment 1 can be any type of mobile user equipment, such as an in-vehicle communication system, a personal communication device (e.g., a user equipment), etc.

[0070] Communication is implemented in the context of a forward packet (FWP), which requests operations related to the forward packet. The operations related to the forward packet can be of different types. For example, it can be receiving a backward packet related to the forward packet by the first user equipment UE1, performing measurements related to radio communication (e.g., performing measurements by base station 3), or sending a second forward packet by the first device.

[0071] The first user equipment 1 includes a communication module (COM) 1.1, a computing module (PROC) 1.2, and a memory unit (MEMO) 1.3. MEMO 1.3 includes a non-volatile unit for fetching computer programs and a volatile unit for fetching parameters that can be implemented for operations related to the forward packet. For example, it can be configured to calculate the time delay between sending a forward packet and performing an operation, or calculate the time for performing an operation.

[0072] COM 1.1 is configured to transmit forward packets and ultimately retransmit packets.

[0073] In some embodiments of the present invention, COM 1.1 can also be configured to receive information related to operations, such as receiving a backward packet related to the forward packet.

[0074] In Figure 1 Base station 3 (BS) is also shown. Optionally, UE1 can communicate with BS 3, and thus can receive data from BS 3 via its communication module (COM 1.1).

[0075] In Figure 1 Only one user equipment is represented in the example. However, the present invention is not limited to this configuration and also covers the case where there are more than one user equipment, especially if the first user equipment UE1 performs D2D communication with other user equipment or devices.

[0076] Now refer to Figure 2 .

[0077] Figure 2Two user equipments in D2D communication are shown, where the first (requesting) user equipment 1 (UE1) transmits a radio signal received by the second (responding) user equipment 2 (UE2). The first user equipment 1 and / or the second user equipment 2 may be within the coverage of the base station 3, or only one of the two devices may be within the coverage area of the base station, or both devices may be outside the coverage area of the base station. This D2D communication may be, for example, OFDM-based transmission. The requesting user equipment 1 and the responding user equipment 2 are mobile devices, that is, these user equipments participate in D2D communication, such as vehicle-to-everything (V2X) communication in the context of standard LTE or NR. More generally, the requesting user equipment 1 and / or the responding user equipment 2 may be any type of mobile user equipment, such as in-vehicle communication systems, personal communication devices (e.g., user equipments), etc. The D2D communication is implemented in the context of a forward packet (FWP) that requests specific data from UE2, and UE2 sends the requested data to UE1 in a backward packet (BWP). This specific exchange between UE1 and UE2 is called a round-trip transmission.

[0078] The requesting user equipment 1 is similar to Figure 1 the user equipment UE1 shown, and thus includes a communication module (COM) 1.1, a processing module (PROC) 1.2, and a memory unit (MEMO) 1.3. MEMO 1.3 includes a non-volatile unit for fetching computer programs and a volatile unit for fetching parameters that can be implemented for round-trip transmission. For example, the volatile unit can fetch PDB (PDB1), target RTT, measured RTT, an estimate of the propagation delay between UE1 and UE2, the content of the request packet, TD E (the duration between the generation and transmission of the forward packet by the user equipment UE1 (TD E ), TD R (the remaining duration, that is, the duration corresponding to the target RTT minus the duration (TD E ), a preferred set of radio resources, retransmission resources for specific packets, etc.

[0079] PROC 1.2 is configured to generate a forward packet (FWP) and configure COM 1.1 to send it to the responding user equipment 2. PROC 1.2 is also configured to calculate TD E , TD R or determine a preferred set of radio resources or determine retransmission resources for specific packets. PROC 1.2 is configured to decode the BWP and obtain the information requested by the FWP.

[0080] COM 1.1 is configured to transmit the FWP and ultimately retransmit packets.

[0081] COM 1.1 is also configured to receive the BWP.

[0082] The responding user equipment 2 includes a communication module (COM) 2.1, a computing module (PROC) 2.2, and a memory unit (MEMO) 2.3. MEMO 2.3 includes a non-volatile unit for fetching computer programs and a volatile unit for fetching parameters that can be implemented for round-trip transmission. For example, the volatile unit can fetch PDB (PDB2), target RTT, duration, an estimate of the propagation delay between UE1 and UE2, request packet content (FWP content), response packet content, TD E 、TD R 、a preferred radio resource set, retransmission resources for a specific packet, new PDB2 (PDB2’), TBR, the computing time of another user equipment, etc.

[0083] PROC 2.2 configures COM 2.1 to receive and decode FWP from UE1. PROC 2.2 is configured to generate a backward packet (BWP) in response to FWP and configure COM 2.1 to send it to UE1. PROC 2.2 is also configured to calculate the duration (e.g., TD E 、TD R ) and / or PDB2’. PROC 2.2 is also configured to select a radio resource among the radio resources of the preferred radio resource set or based on the retransmission radio resources indicated for FWP. PROC 2.2 is configured to decode BWP and obtain the information requested by FWP.

[0084] COM 2.1 is configured to transmit BWP and finally retransmit the packet.

[0085] COM 1.1 is also configured to receive BWP.

[0086] In Figure 1 a base station 3 (BS) is also shown. UE1 and / or UE2 can communicate with BS 3, and thus can receive data from BS 3 via their communication modules (COM 1.1 and COM 2.1). For example, if the target RTT is not yet configured on UE1 and / or UE2, UE1 and / or UE2 can receive the target RTT.

[0087] In Figure 1 the example only two user equipments are shown. However, the present invention is not limited to such one-to-one D2D communication, and also covers cases where more than one user equipment is expected to receive FWP and respond to it.

[0088] Now refer to Figure 3 .

[0089] Figure 3 Shows a first example of method P3 according to multiple embodiments of the present invention.

[0090] All or some of the steps of method P3 can be performed by a user equipment, such as Figure 1 and Figure 2 the first user equipment UE1 as represented in

[0091] Method P3 includes a first step S31 of obtaining a first set of radio resources available for sending forward packets from the first user equipment.

[0092] This allows obtaining a first set of radio resources available for sending forward packets.

[0093] As described above, this can be performed, for example, by the first user equipment screening its environment and / or by the process defined in standard TS38.214 / 8.1.4.

[0094] Method P3 further includes a second step S32 of obtaining a second set of radio resources available for performing operations related to forward packets.

[0095] As described above, the operations related to forward packets are operations caused by the transmission of forward packets and expected to be the result of the forward packet transmission. This operation can depend, for example, on the application that causes the backward packet transmission, and can be, for example:

[0096] - The first user device receives a backward packet in response to the transmission of the forward packet;

[0097] - The first user device transmits another forward packet related to the forward packet, such as another packet sent by the same application;

[0098] - Further perform measurements on the transmission of the forward packet, such as sending future packets for the same application as the forward packet;

[0099] - Others.

[0100] Performing operations related to forward packets requires the use of at least one radio resource. For example, sending and receiving additional packets, performing radio measurements, etc. require radio resources.

[0101] Therefore, step S32 allows obtaining a second set of radio resources available for performing operations. Of course, determining the radio resources available for performing operations depends on the operation itself. For example:

[0102] - If the operation is that the first user device receives a forward packet in response to the transmission of the forward packet, determining the availability of radio resources can be performed according to the availability of the first user device to receive packets and / or the availability of the second user device to send packets to the first user device;

[0103] - if the operation is transmission of another forward packet by the first user device, determining the availability to perform the operation may include determining the availability of radio resources for sending another forward packet by the first user device;

[0104] - if the operation is to perform radio measurements by the first user equipment, determining the availability of performing the operation may comprise determining the availability of radio resources to perform the measurements;

[0105] - if the operation is to perform radio measurements by the second user equipment, determining the availability of performing the operation may comprise determining the availability of radio resources for performing the measurements by the second device;

[0106] -other.

[0107] The radio resources of the second set may be at least partially different from, and may be completely different from, the radio resources of the first set. There may be at least one radio resource in the radio resources of the first set that is not included in the radio resources of the second set. For example, for each radio resource in the radio resources of the first set, there may be an associated time window including at least one of the radio resources of the second set, and possibly a group of associated radio resources. The associated radio resources in the second set may be after the radio resources in the first set. In this case, a minimum and / or maximum time gap may be required between the resources in the first set and the associated resources in the second set. In other words, at least one resource in the first resource set may be before any other resource in the second set or the earliest resource in the second resource set. In another interpretation, at least one resource in the second resource set may be after any other resource in the first resource set or after the latest resource in the first resource set. The first resource set and the second resource set may be completely disjoint. For example, the first resource set may include only resources that can be used for transmission, and the second resource set may include resources that can be used for reception, and vice versa. For half-duplex terminals, the two sets do not have any common resources. In another example, one resource set (e.g., a first resource set) includes resources that can be used for communication (e.g., transmission and / or reception), and another set (e.g., a second resource set) includes resources that can be used for measurement. Availability can be viewed from the perspective of a user device that sends a forward packet or from the perspective of another user device (e.g., a user device that performs measurements or a user device that is expected to send a backward packet).

[0108] Method P3 further comprises a third step S33: obtaining, from among the radio resources of the first set, a radio resource corresponding to the first time t i At least one first radio resource associated with the forward packet such that at least one second radio resource from a second set is included in a time window having a lower bound after the first time and an upper bound optionally defined based on at least one of the forward packet and the first time.

[0109] In other words, a first radio resource having a first time t i can be selected so that at least one second radio resource from a second set is included in a time window defined after the first time t i , where the time window is defined according to the forward packet and / or the first time, for example, to comply with the time constraints caused by the transmission of the first packet.

[0110] This thus allows ensuring that a second radio resource can be selected thereafter, which at the same time:

[0111] - belongs to the second set and can thus be used to perform an operation;

[0112] - and has a time within this time window and thus has a time that complies with the time constraints caused by the transmission of the first packet.

[0113] According to various embodiments of the present invention, the third step S33 may include obtaining:

[0114] - a single first radio resource associated with a single time window; or

[0115] - a plurality of first radio resources respectively associated with a plurality of time windows, which means that each first radio resource among the plurality of first radio resources is associated with a corresponding time window.

[0116] The plurality of first radio resources obtained at the same time may, for example, correspond to a plurality of forward messages respectively sent by the same application or consecutive retransmissions of the same forward packet.

[0117] Thus, during the execution of step S33, a list of candidate first radio resources belonging to the first set can be obtained, which complies with the conditions associated with the time window including at least one second radio resource from the second set.

[0118] This time window may be defined, for example, by:

[0119] - a minimum time t i +t min , where t min is a minimum time threshold; and / or

[0120] - a maximum time t i +t max , where t max is a maximum time threshold.

[0121] The window can thus be defined as [t i +t min ; t i+ t max ​

[0122] Minimum time threshold t min can be defined according to different rules. For example, it can be defined so that the device has enough time to send a forward packet to receive and process the forward packet before the second radio resource needs to be used (e.g., to send a backward packet).

[0123] Maximum time threshold t max can be defined according to different rules. For example, it can be defined to ensure that the second radio resource will be used within a time range that complies with time requirements (e.g., communication time requirements).

[0124] For example, if the second radio resource is to be used to send a backward packet, the maximum time threshold t max can be defined to ensure that the maximum time t max appears between the transmission of the forward packet and the transmission of the backward packet, thus complying with one or more target communication metrics. For example, the maximum time t max can be defined according to one or more of the following:

[0125] - The target round-trip time (RTT) of the communication;

[0126] - The packet delay budget (PDB) of the forward and / or backward packet;

[0127] - Others.

[0128] Minimum time threshold t min and the maximum time threshold t max can be fixed or vary over time. Thus they can be time-varying (t min (t i ), t max (t i )) or, for example, change at each moment t i To improve readability, we will skip the time index in the following description. For example, its value can be defined according to the requirements of the application requesting the forward packet transmission and / or modified iteratively during the process of the application. For example, its value can be modified iteratively according to criteria such as the time from the first attempt to send the initial forward packet, the number of retransmissions of the forward packet, the number of previous retransmissions of the previous packet, information about the channel quality, information related to the characteristics of the first and / or second terminal (e.g., processing time, capabilities, etc.).

[0129] In various embodiments of the present invention, a first set of radio resources and a second set of radio resources are selected within a global time window having an upper bound RTTboundmax_1. For example, the upper bound RTTboundmax_1 can be defined according to the maximum time for performing an operation. For example, if the second set of radio resources is used to send a backward packet, the upper bound RTTboundmax_1 of the global time window can be set to ensure that the last possible time for the backward packet reception of the first user equipment complies with the latest expected reception time.

[0130] The upper bound of the global time window can be, for example:

[0131] - fixed;

[0132] - provided by the application causing the communication;

[0133] - provided by the upper layer;

[0134] - and / or coordinated by a central server to obtain the best trade-off between RTT and resource occupancy;

[0135] - defined according to the TCP transport layer used by the application causing the communication, the rate of which depends on the RTT;

[0136] - defined to ensure the stability of the automatic control related to the application causing the communication, the stability of the automatic control being calculated from the RTT;

[0137] - others.

[0138] If a global time window with an upper bound is used, the time window can be bounded by the upper bound of the global time window. For example, if the time t of the candidate first radio resource i such that t i+ t max > RTTboundmax_1, where RTTboundmax_1 is the maximum value of the global time window, the time window associated with this resource will be [t i+ t min ; RTTboundmax_1], rather than [t i+ t min ; t i+ t max . If t i+ t min > RTTboundmax_1, then simply this first candidate radio resource cannot be selected because there is no second radio resource available for selection in the global time window after this candidate first radio resource.

[0139] This method can result in the generation of multiple candidate first radio resources, each candidate first radio resource being associated with a time window. For example, if the time window associated with each candidate first radio resource is defined by a lower bound of time after the time of the candidate radio resource by t min and an upper bound of time after the time of the candidate radio resource by t max :

[0140] - The first candidate radio resource at time t 1 is associated with the time window [t 1 + t min ; t 1 + t max , where n 1 radio resources are found from the second set;

[0141] - The second candidate radio resource at time t 2 is associated with the time window [t 2 + t min ; t 2 + t max , where n 2 radio resources are found from the second set;

[0142] - The third candidate radio resource at time t 3 is associated with the time window [t 3 + t min ; t 3 + t max , where n 3 radio resources are found from the second set;

[0143] - Others.

[0144] Then at least one first radio resource can be obtained (e.g., selected) among the candidate first radio resources.

[0145] Generally, obtaining a first radio resource associated with a time window including a number of radio resources from the second set that is at least equal to a threshold increases the probability that the radio resource will actually be available for performing an operation or ensures that the radio resource will actually be available for performing an operation.

[0146] In fact, in some specific cases, it may be possible that the first user equipment detects a second radio resource from the second set as available for performing an operation, but at the time of the second radio resource, it turns out that the second radio resource is not available for performing an operation. For example, the following situations:

[0147] - The second radio resource is requested by a higher-priority application at the same time, so it is not available at the time when the operation needs to be performed;

[0148] - Operations include sending a packet from a second user device to a first user device, and a second radio resource is detected as available for reception by the first user device but turns out to be unavailable for transmission by the second user device;

[0149] - The location of the device has changed, so the availability of radio resources has changed;

[0150] - Others.

[0151] Therefore, having more resources from the second set in the time window associated with the first resource increases the probability of having available radio resources from the second set at the time when an operation needs to be performed.

[0152] Selecting a first radio resource among candidate first radio resources can thus be performed in different ways. For example:

[0153] - A candidate associated with a time window including the most radio resources from the second set can be selected;

[0154] - A candidate associated with a time window having the most uniform distribution of radio resources from the second set over the time window can be selected;

[0155] - A candidate can be randomly selected among candidates that comply with requirements such as the following:

[0156] ○ A candidate associated with a time window including radio resources from the second set with a quantity at least equal to a threshold Mi can be selected. In this case, the threshold Mi corresponds to the minimum quantity of radio resources to ensure that at least one second radio resource will ultimately be available;

[0157] ○ The candidate is associated with a time window having a satisfactory uniformity in the time distribution of radio resources belonging to the second set;

[0158] ○ Others.

[0159] - Others.

[0160] In the case where the candidate first radio resource must comply with the requirement of being associated with a time window including radio resources from the second set with a quantity at least equal to a threshold Mi, the threshold Mi can be equal to 1 or higher. It can also be fixed or variable, for example depending on:

[0161] - The remaining RTT value or an indication related to the QoS of the two-way application;

[0162] - The priority of the backward packet expected in response to the forward packet;

[0163] - The number of transmissions / retransmissions that the forward packet has undergone;

[0164] - Indicators related to channel load (CBR, CR, etc.);

[0165] - Others.

[0166] More generally, the threshold Mi can be defined according to any information related to the success chance of the operation, in particular information related to the probability of successfully sending and receiving packets.

[0167] Method P3 further includes a fourth step S34: sending the forward packet by the first user equipment using the first radio resource.

[0168] We now refer to Figure 4 .

[0169] Method P4 includes Figure 3 all the steps of method P3 as represented in

[0170] In addition, it includes a step S41 of verifying whether at least one selection criterion is complied with before the step S34 of sending the forward packet.

[0171] At least one selection criterion may include one or more criteria related to the validity of the selection of the first radio resource.

[0172] For example, at least one selection criterion may include at least one criterion related to:

[0173] - The possibility of selecting at least one first radio resource in step S33;

[0174] - Comparing the number of second radio resources in the time window associated with the first radio resource in step S33 with a threshold (the number of radio resources in the second set in the time window must be higher than the threshold of the criterion to be verified);

[0175] - Others.

[0176] If at least one selection criterion is complied with, the step S34 of sending the forward packet using the first radio resource selected in step S33 can be executed.

[0177] Otherwise, that is, if at least one selection criterion is not complied with, method P4 includes a step S42 of modifying one or more parameters in steps S31, S32 and S33 before returning to the first step where at least one parameter has been modified.

[0178] The parameters that can be modified can be, for example:

[0179] - For steps S31 and S32:

[0180] ○ The priority of adding and / or removing radio resources in the first set in step S31 and in the second set in step S32;

[0181] ○ The RSRP threshold for adding and / or removing radio resources in the first set in step S31 and in the second set in step S32;

[0182] ○ Others.

[0183] - For step S33:

[0184] ○ Select the minimum number Mi of the second resources in the time window associated with the first resource required for the first resource;

[0185] ○ The maximum time threshold t for defining the upper bound of the time window associated with the first resource max ;

[0186] ○ Others.

[0187] Generally, the method P4 can start from strict parameters (i.e., parameters that result in obtaining fewer resources in steps S31 and S32 and selecting fewer resources in step S33), and until at least one selection criterion is met, modify the parameters to more relaxed values to obtain / select more radio resources.

[0188] For example, let's assume a case where step S33 requires a minimum number of resources Mi in the time window for selecting the first resource, and Mi is initially set to 4. If it is not possible to select the first radio resource using this parameter, the value of Mi can be set to 2, and then step S33 is executed again. If this still does not allow the selection of the first resource, Mi can be set to 1.

[0189] Therefore, if possible, use a higher number Mi to select the first resource (meaning there are a large number of second resources in the time window), and by default, use a lower number Mi for selection. Of course, the same reasoning can be applied to other parameters of this method. More than one parameter can be modified at the same time. After the modification, the method can return to step S31 or S32 (if the parameters of these steps have been modified).

[0190] For steps S31 and S32, more relaxed parameters will be those that result in selecting / obtaining more radio resources. For example, if step S32 includes selecting radio resources with an RSRP higher than the RSRP threshold for receiving backward packets, setting the RSRP threshold to a lower value will result in adding more resources to the resources in the second set, thus increasing the probability of meeting at least one selection criterion in step S41.

[0191] Thus, method P4 generally allows the selection of radio resources with the strictest parameters and, if it is not possible with the strictest parameters, relaxes the selection rules in order to select radio resources anyway.

[0192] However, the value of the parameter can be bounded. For example, the lowest possible value of the parameter Mi related to the minimum number of second radio resources must be at least equal to 1 and can be higher depending on the application. If at least one selection criterion is still not met when all parameters have their loosest values, method P4 can trigger an error indicating that it is not possible to select the first resource at this stage.

[0193] Now refer to Figure 5 。

[0194] Figure 5 Represents a third example of the method in multiple embodiments of the present invention.

[0195] In Figure 5 the example, method P5 includes all the steps of method P3 and further includes step S51 of sending a backward packet related to the forward packet to the first device.

[0196] The backward packet can be sent, for example, by the second user equipment UE2, by another user equipment or by the base station.

[0197] The backward packet can then be received by the first user equipment UE1.

[0198] For example, in the context of a given application, the backward packet can contain a response to the content of the forward packet.

[0199] In this case, obtaining the second set of radio resources in step S32 can be aimed at ensuring that the radio resources will be available for sending and receiving the backward packet.

[0200] For example, the radio resources in the second set can be selected such that the radio resources in the second set include the radio resources available for the first user equipment to receive the backward packet.

[0201] This determination of the radio resources available for the first user equipment to receive the backward packet can be performed, for example, by determining for each radio resource whether it is suitable for the first user equipment to receive the packet, or conversely by excluding the resources determined to be unsuitable for receiving the packet. For example:

[0202] - Resources affected by interference can be excluded;

[0203] - Resources declared as unavailable can be excluded;

[0204] - Resources with a perceived RSRP higher than the threshold can be excluded;

[0205] - Resources that can exclude interference from messages with a priority higher than a threshold;

[0206] - Others.

[0207] Therefore, in this example, the first radio resource is finally selected so that sufficient radio resources will be available for receiving backward packets in the time window after the first resource.

[0208] Method P5 can be used in particular in an example of D2D communication between a first user equipment and a second user equipment (e.g., Figure 2 the user equipment UE2 represented in), where, in the D2D communication with the first user equipment, the first user equipment sends a forward packet to the second user equipment UE2, and where, the second user equipment sends a backward packet to the first user equipment.

[0209] In this case, the steps of method P5, in particular selecting the first radio resource so that there is a sufficient second set of radio resources in the time window after the first radio resource, allows compliance with the time constraints in D2D communication, because sufficient radio resources in the second set will be available for receiving backward packets in the time window for complying with the time constraints of D2D communication.

[0210] In various embodiments of the present invention, the radio resources in the second set can be obtained based on at least one data related to the ability of the second user equipment to send the backward packet to the first user equipment.

[0211] As described above, the at least one data related to the ability of the second user equipment to send the backward packet to the first user equipment can be any type of data that provides an indication of the ability of the second user equipment to use radio resources to send data packets.

[0212] Examples of such selection of radio resources can include selecting one or more of the following:

[0213] - Radio resources available for the second device to send packets. These radio resources can be obtained by screening from the second device;

[0214] - Radio resources with estimated radio resource management (RRM) values, timers or indicators higher or lower than a predefined threshold;

[0215] - Interference-free radio resources;

[0216] - Radio resources that are interfered with by a priority lower than that of the backward packet. By "lower priority", we mean that the radio resources are interfered with by a priority that is less important than the backward packet, which means that the resource request for the radio resources can be overridden by the backward packet. However, it should be noted that the index of the priority order can be reversed. For example, in the 3GPP specification, the highest priority is associated with index 0, while the lowest priority is associated with index 7;

[0217] - Others.

[0218] Therefore, this selection can consider the data received from the second user device. According to various embodiments of the present invention, the selection of radio resources in step S32 can consider the ability of the first user equipment to receive backward packets, the ability of the second user equipment to send backward packets, or a combination thereof.

[0219] Now refer to Figure 6 .

[0220] Figure 6 An example of method P6 in multiple embodiments of the present invention is shown.

[0221] Method P6 includes all steps of method P3.

[0222] It also includes step S61 of associating at least one data related to an indication of performing an operation related to the forward packet with the forward packet before step S34 of sending the forward packet.

[0223] Associating at least one data with the forward packet may include, for example, inserting the data into the forward packet itself, or sending at least one data together with the forward packet, or implicitly signaling at least one data. The at least one data may be sent simultaneously with the forward packet or not simultaneously, but needs to be sent and received by the same recipient as the forward packet. The at least one data may be transmitted using the same channel as the forward packet or a different channel. It may also be sent before, after, or simultaneously with the forward packet. Implicitly signaling at least one data may be accomplished, for example, using a specific format for sending data packets, by the presence / absence of a specific field, by an associated timer, or by any other means that allows the recipient of the forward packet to infer the at least one data.

[0224] Therefore, performing step S61 before step S34 allows the recipient of the forward packet to benefit from the data related to performing the operation related to the forward packet.

[0225] The at least one data may include, for example, one or more of the following:

[0226] - Data related to the constraints or objectives of the operation. Such data may include, for example, the minimum time for sending a backward message or performing an operation;

[0227] - Data related to the selection of radio resources for sending a backward message upon receiving a forward message. Such data may include any type of data that allows the receiver of the forward message to select the most relevant radio resources to send a backward message back to the first user equipment;

[0228] - An indication that a forward packet is expected to trigger a specific measurement within a given time range;

[0229] - An indication that a forward packet requires an acknowledgment (i.e., a backward packet);

[0230] - An indication to trigger resource selection on the receiver side;

[0231] - Others.

[0232] For example, in multiple embodiments of the present invention where the first user equipment performs D2D communication with the second user equipment, step S61 may include associating at least one data related to the selection of radio resources by the second user equipment with the forward packet.

[0233] At least one data related to the selection of radio resources by the second user equipment may, for example, include one or more of the following:

[0234] - An indicator related to the IND;

[0235] - A descriptor or indicator related to at least one radio resource. For example, such an indicator or descriptor may be a descriptor of the radio resource of the time window associated with the first radio resource detected as available for reception by the first user equipment;

[0236] - An indicator regarding the remaining RTT budget;

[0237] - An indicator regarding the time budget consumed since the first transmission attempt;

[0238] - Others.

[0239] Therefore, this allows the second user equipment to most accurately select the second radio resource to send a backward message to the first user equipment.

[0240] For example:

[0241] - If at least one data related to the selection of radio resources by the second user equipment includes an indicator regarding the remaining RTT budget, the second user equipment may use this information to select the second radio resource that complies with the remaining RTT budget to send a backward packet;

[0242] - If at least one data includes a descriptor of a radio resource of a time window associated with a first radio resource detected as available for reception by a first user equipment, a second user equipment may select one of the radio resources defined by the descriptor for transmitting a backward packet, so that the first user equipment will be able to maximize the opportunity to receive the backward packet.

[0243] Now refer to Figure 7 。

[0244] Figure 7 An example showing Method P7 in multiple embodiments of the present invention.

[0245] All or part of the steps of Method P7 may be performed by a second user equipment (e.g., Figure 2 the second user equipment UE2 as represented in

[0246] Method P7 includes a first step S71: A second user equipment UE2 in D2D communication receives a forward packet from a first user equipment UE1 using a first radio resource having a first time.

[0247] The forward packet may be, for example, a forward packet sent during step S34 of one of Methods P3, P4, P5, and P6.

[0248] Method P7 further includes a second step S72: Select a second radio resource included in a time window available for the second user equipment to send a backward packet related to the forward packet, the time window having a lower bound after the first time and an upper bound defined according to at least one of the forward packet and the first time.

[0249] Step S72 may generally include: The second user equipment selects a radio resource that belongs to both a second set of radio resources obtained in step S32 of one of Methods P3, P4, P5, and P6 and a time window associated with the first radio resource.

[0250] In an embodiment where the forward packet has been associated with at least one data related to the radio resource selection by the second user equipment in step S61, the second user equipment may use the data to select the second radio resource in step S72.

[0251] Method P7 further includes a third step S73: The second user equipment uses the second radio resource to send the backward packet to the first user equipment.

[0252] Therefore, method P7 allows enhancing D2D communication with the first user equipment. In particular, the selection of the second radio resource related to the first radio resource and optionally at least one data related to the selection of the radio resource by the second user equipment allow the selection of the second radio resource and the transmission of the backward packet that complies with the operation requirements of the application caused by the transmission of the forward packet.

[0253] Now refer to Figure 8 and Figure 9 。

[0254] Figure 8 and Figure 9 respectively represent the first example and the second example of the selection of the first radio resource in multiple embodiments of the present invention.

[0255] In Figure 8 and Figure 9 both, the radio resource is represented using a 2D representation, where:

[0256] - The horizontal axis represents time. In this example, for the sake of clarity and understandability of the example, a basic time unit is used to define time. Each column in the 2D representation represents one time unit. The time unit can be represented by the symbol duration (e.g., OFDM symbol in a system based on OFDM transmission, etc.) or the duration of a group of symbols (e.g., mini-slot, slot, slot part dedicated to a given physical channel, subframe, frame, etc.) or more generally the duration of an allocation unit. The allocation unit is usually defined as the smallest time / frequency resource that can be signaled using available signals as part of the resource allocation process;

[0257] - The vertical axis represents the frequency domain. Each row in the 2D representation represents one frequency unit. For a system based on multi-carrier transmission (e.g., based on OFDM), the frequency unit can be a sub-carrier, a set of sub-carriers such as a resource block or a resource block group, a sub-channel, or more generally the frequency span of an allocation unit. In this example, the first column will have a time equal to 1, and then in each column, the time increases by 1 time unit;

[0258] Therefore, the radio resource is defined by both the time unit and the frequency unit.

[0259] In both cases, the radio resources of the first set Set1 are obtained in step S31. In this example, in both cases, the first set Set1 includes:

[0260] - The radio resource Res1.1 at time t 1.1 = 2;

[0261] - The radio resource Res1.2 at time t 1.2 = 4;

[0262] - At time t 1.3 = 8 radio resource Res1.3;

[0263] - At time t 1.4 = 12 radio resource Res1.4;

[0264] - At time t 1.5 = 14 radio resource Res1.5;

[0265] - At time t 1.6 = 20 radio resource Res1.6;

[0266] - At time t 1.7 = 24 radio resource Res1.7;

[0267] - At time t 1.8＝ 25 radio resource Res1.8.

[0268] In both cases, the radio resources of the second set Set2 are obtained in step S32. In this example, in both cases the first set Set2 includes:

[0269] - At time t 2.1 = 1 radio resource Res2.1;

[0270] - At time t 2.2 = 2 radio resource Res2.2;

[0271] - At time t 2.3 = 8 radio resource Res2.3;

[0272] - At time t 2.4 = 8 radio resource Res2.4;

[0273] - At time t 2.5 = 10 radio resource Res2.5,;

[0274] - At time t 2.6 = 14 radio resource Res2.6;

[0275] - At time t 2.7 = 23 radio resource Res2.7;

[0276] - At time t 2.8 = 27 radio resource Res2.8.

[0277] However, the two examples are different because they implement different steps S33 for selecting the first radio resource.

[0278] In Figure 8In the example, step S33 includes associating a time window with each candidate first radio resource, the time window having:

[0279] - a lower bound equal to the minimum time threshold t after the time of the candidate first radio resource min Here, t min is equal to 3 time units. It should be noted that t min has a constant value here to provide a simple example for illustrative purposes only. More generally, the value of t min can vary over time and is thus different for each radio resource in the first set;

[0280] - an upper bound equal to the global maximum value of the global time window RTTboundmax_1. The global time window RTTboundmax_1 can be counted, for example, from a selection trigger (the time window starts, for example, from Res2.1, i.e., the first resource depicted in the figure) or from a previously predetermined time.

[0281] For example:

[0282] - the time window associated with resource Res1.1 is the time window [t 1.1 + t min ; RTTboundmax_1];

[0283] - the time window associated with resource Res1.2 is the time window [t 1.2 + t min ; RTTboundmax_1];

[0284] - the time window associated with resource Res1.3 is the time window [t 1.3 + t min ; RTTboundmax_1];

[0285] - the time window associated with resource Res1.4 is the time window [t 1.4 + t min ; RTTboundmax_1];

[0286] - the time window associated with resource Res1.5 is the time window [t 1.5 + t min ; RTTboundmax_1];

[0287] - the time window associated with resource Res1.6 is the time window [t 1.6 + t min ; RTTboundmax_1];

[0288] - The time window associated with resource Res1.7 is the time window [t 1.7 + t min ; RTTboundmax_1];

[0289] - The time window associated with resource Res1.8 is the time window [t 1.8 + t min ; RTTboundmax_1].

[0290] Then, resource Res1.8 can be excluded from the first set of selectable radio resources because t 8.1 + t min = RTTboundmax_1, which means that selecting Res1.8 to send forward packets will not allow later selection of resources from the second set.

[0291] In addition, other resources can be removed from the first set. For example, resources having the same time as the resources in the second set can be removed from the first set. In fact, if the first user equipment UE1 is half-duplex, it cannot send and receive signals at the same time, so it is not advisable to have radio resources from the first set and the second set at the same time. Therefore, the following resources can be excluded from the first set:

[0292] - Res1.3, because t 1.3 = t 2.3＝ t 2.4＝ 8

[0293] - Res1.5, because t 1.5 = t 2.6 = 14.

[0294] In Figure 9 the example of, each radio resource of the first set having time t i is associated with a time window having a lower bound of time t i + t min and an upper bound of time t i + t max where t min = 3 time units and t max = 6 time units. It should be noted that t min and t max have constant values here to provide a simple example for illustrative purposes only. More generally, the values of t min and t max can vary with time and are thus different for each radio resource of the first set.

[0295] Therefore, in this example:

[0296] - Resource Res1.1 is associated with time window Win1.1[t 1.1 +t min ; t 1.1 +t max , and it does not contain resources from the second set;

[0297] - Resource Res1.2 is associated with time window Win1.2[t 1.2 +t min ; t 1.2 +t max , and it contains two resources (Res2.3, Res2.4) from the second set;

[0298] - Resource Res1.3 is associated with time window Win1.3[t 1.3 +t min ; t 1.3 +t max , and it does not contain resources from the second set;

[0299] - Resource Res1.4 is associated with time window Win1.4[t 1.4 +t min ; t 1.4 +t max , and it does not contain resources from the second set;

[0300] - Resource Res1.5 is associated with time window Win1.5[t 1.5 +t min ; t 1.5 +t max , and it does not contain resources from the second set;

[0301] - Resource Res1.6 is associated with time window Win1.6[t 1.6 +t min ; t 1.6 +t max , and it contains one resource (Res2.7) from the second set;

[0302] - Resource Res1.7 is associated with time window Win1.7[t 1.7 +t min ; t 1.7 +t max , and it contains one resource (Res2.8) from the second set. In multiple embodiments of the present invention, this window can be bounded by RTTboundmax_1;

[0303] - Resource Res1.8 is associated with time window Win1.8[t 1.8 +t min ; t 1.8+t max is associated and does not contain resources from the second set. In various embodiments of the present invention, this window may not even exist because t 8 +t max > RTTboundmax1.

[0304] Therefore, candidate first radio resources Res1.1, Res1.3, Res1.4, Res1.5, and Res1.8 should be excluded from the list of possible candidates because the time windows associated with these resources do not contain any resources from the second set, which means that if one of these resources is to be selected, there are no radio resources from the second set available within the desired time range to perform operations related to the transmission of the first radio resource.

[0305] In Figure 9 's example, step S33 thus selects one of radio resources Res1.2, Res1.6, and Res1.7 as the first radio resource for sending the forward packet. The first radio resource can be selected among the three candidate first radio resources Res1.2, Res1.6, and Res1.7 based on different criteria. For example:

[0306] - The first radio resource can be randomly selected among the three resources Res1.2, Res1.6, and Res1.7;

[0307] - The radio resource associated with the time window that includes the most radio resources from the second set can be selected. In this example, resource Res1.2 will be selected because the associated time window Win1.2 includes 2 radio resources from the second set, while the time windows Win1.6 and Win1.7 associated with resources Res1.6 and Res1.7 respectively contain only one radio resource from the second set;

[0308] - Select the radio resources from the second set with a threshold Mi = 2 in the time window associated with the candidate first radio resource. In this case, resource Res1.2 will be selected because it is the only one that meets this condition;

[0309] - The candidate first radio resource with the earliest time can be selected. In this example, resource Res1.2 will be selected because t 2 <t 6 and t 2 <t 6 .

[0310] Figure 8 and Figure 9The examples are provided only as non - limiting examples of the selection rules for the first resource among the multiple embodiments of the present invention, and other selection rules can be implemented within the scope of the present disclosure.

[0311] The present disclosure is not limited to the methods, computer software, computer - readable non - transitory media, and packet user equipment described herein, which are merely examples. The present invention encompasses every alternative that would occur to those skilled in the art upon reading this text.

[0312] For example, all non - mutually exclusive embodiments presented herein can be combined. For example, Figure 4 、 Figure 5 and Figure 6 multiple embodiments of the methods presented therein can be combined.

Claims

1. A method (P3, P4, P5), the method comprises the following steps: - Obtain (S31) radio resources for a first set (Set1) available for sending forward packets from a first user equipment (UE1); - Obtain (S32) radio resources for a second set (Set2) available for performing operations related to the forward packets; - Among the radio resources of the first set, obtain (S33) at least one first radio resource associated with at least one first time (Ti) such that at least one second radio resource from the second set is included in a time window having a lower bound after the at least one first time; - Use the at least one first radio resource by the first user equipment to send (S34) the forward packet.

2. The method according to claim 1, wherein, select the first radio resource such that the number of second radio resources from the second set in the time window is at least equal to a threshold of the number of radio resources.

3. The method according to any one of the preceding claims, wherein, obtain the radio resources of the first set and the radio resources of the second set in a global time window having a global upper bound (RTTboundmax_1).

4. The method according to any one of the preceding claims, wherein, the time window has an upper bound defined according to at least one of the forward packet and the first time.

5. The method according to any one of the preceding claims (P4), the method comprises the following steps: While not complying with (S41) at least one selection criterion, iteratively modify (S42) one or more parameters of one or more of the following steps: - Obtain radio resources of a first set; - Obtain the radio resources of the second set; - And select the first radio resource.

6. The method according to any one of the preceding claims (P6), the method comprises the following steps: Associate (S61) at least one data related to an indication for performing operations related to the forward packet with the forward packet.

7. The method according to any one of the preceding claims (P5), wherein, the operations include: sending (S51) a backward packet related to the forward packet to the first device.

8. The method according to claim 7, wherein, the radio resources of the second set include radio resources available for the first user equipment to receive the backward packet.

9. The method according to claim 8, wherein, - The first user equipment sends the forward packet to a second user equipment (UE2) performing D2D communication with the first user equipment; - The second user equipment sends the backward packet to the first user equipment.

10. The method according to claim 9, wherein, obtain the radio resources of the second set based on at least one data related to the ability of the second user equipment to send the backward packet to the first user equipment.

11. The method according to any one of claims 9 to 10, the method comprises the following steps: associating at least one data related to radio resources selected by the second user equipment with the forward packet.

12. A method (P7), the method comprises the following steps: - In D2D communication, a second user equipment (UE2) receives (S71) a forward packet from a first user equipment (UE1) using a first radio resource having a first time (t i ); - selecting (S72) a second radio resource available for the second user equipment to send a backward packet related to the forward packet within a time window, the time window having a lower bound after the first time and an upper bound defined according to at least one of the forward packet and the first time; - sending (S73) the backward packet from the second user equipment to the first user equipment using the second radio resource.

13. A forward packet, the forward packet is sent by a first user equipment (UE1) using a first radio resource having a first time (ti), the first radio resource is selected among a first set of radio resources available for sending the forward packet from the first user equipment, such that at least one second resource from a second set of radio resources available for performing operations related to the forward packet is included in a time window having a lower bound after the first time.

14. A user equipment (UE), the user equipment comprises at least one processor, the at least one processor is configured to execute the method according to any one of claims 1 to 13.

15. A computer software, the computer software comprises instructions which, when executed by a processor, implement at least a part of the method according to any one of claims 1 to 13.

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