Reducing power consumption in a direct wireless communication system

Abstract

An energy saving resource pool is defined for sidelink transmissions of energy saving user equipment, UE. The energy saving resource pool defines a subset of time slots that power saving UEs can use to transmit or receive. The power saving resource pool can be shared among UEs so that only relevant time slots are used and needs to be monitored.

Description

Technical Field

[0001] This disclosure relates to point-to-point communication in a wireless communication system, and more particularly to an energy-saving procedure in partially sensor-side walk-link communication. Background Technology

[0002] Wireless communication systems such as third-generation (3G) mobile phone standards and technologies are well-known. These 3G standards and technologies were developed by the 3rd Generation Partnership Project (3GPP) (RTM). Third-generation wireless communication is typically used to support macrocell mobile phone communication. Communication systems and networks have evolved towards broadband and mobile systems.

[0003] In a cellular wireless communication system, user equipment (UE) connects to a radio access network (RAN) via a radio link. The RAN comprises a set of base stations that provide radio links to UEs within their coverage cells. The RAN also provides an interface to the core network (CN) for overall network control. It is important to note that the RAN and CN each perform their respective functions relevant to the overall network. For convenience, the term "cellular network" is used to refer to the combination of the RAN and CN, and can be understood as referring to the corresponding system used to perform the disclosed functions.

[0004] The 3G Partnership developed the so-called Long Term Evolution (LTE) system for mobile access networks, namely the Evolved Universal Mobile Communications System Regional Radio Access Network (E-UTRAN), in which one or more macro cells are supported by base stations called eNodeBs or eNBs (evolved NodeBs). More recently, LTE has been evolving further towards 5G, or New Radio (NR) systems, in which one or more cells are supported by base stations called gNBs. NR recommends using the Orthogonal Frequency Division Multiplexing (OFDM) physical transmission format.

[0005] The NR protocol is designed to provide the option to operate in unlicensed radio bands (known as NR-U). When operating in unlicensed radio bands, the gNB and UE must compete with other devices for physical media / resource access. For example, Wi-Fi (RTM), NR-U, and LAA can use the same physical resources.

[0006] The trend in wireless communication is towards providing services with lower latency and higher reliability. For example, NR aims to support Ultra-Reliable and Low-Latency Communication (URLLC), while Massive Machine-Type Communication (mMTC) aims to provide low latency and high reliability for small data packets (typically 32 bytes), with a user plane latency of 1ms, a reliability of 99.99999%, and a physical layer packet loss rate of 10%. -5 Or 10 -6 .

[0007] mMTC services are designed to support a large number of devices over a long lifespan via energy-efficient communication channels, where data transmission between each device is occasional and infrequent. For example, a single unit may need to support thousands of devices.

[0008] The following disclosure relates to various improvements to cellular wireless communication systems. Summary of the Invention

[0009] This application provides a sidelink communication method between at least two user equipment (UEs) in a cellular communication network. The method includes: defining an energy-saving resource pool used by an energy-saving UE; transmitting an indication of transmission resources in the energy-saving resource pool from a base station to at least two UEs; and using only the transmission resources of the energy-saving resource pool when communicating with or transmitting from the energy-saving UE.

[0010] The energy-saving resource pool is defined as a subset of the resource pool used by the at least two UEs.

[0011] The energy-saving resource pool is defined as a subset of time slots within the resource pool.

[0012] The indication of transmission resources in the energy-saving resource pool is sent using RRC signaling.

[0013] The energy-saving UE only monitors the time slots in the energy-saving resource pool before transmission.

[0014] The UE using the energy-saving resource pool sends an indication of the resources in the energy-saving resource pool to other UEs.

[0015] The energy-saving resource pool is defined by the UE that utilizes the resource pool.

[0016] The energy-saving resource pool is defined by the base station. Attached Figure Description

[0017] Further details, aspects, and embodiments of the invention will be described by way of example only with reference to the accompanying drawings. The components in the drawings are for ease of illustration and are not necessarily drawn to scale. For ease of understanding, the same components are referred to by the same reference numerals in the various drawings.

[0018] Figure 1 Draw a schematic diagram of selected elements in a cellular communication network.

[0019] Figure 2 Draw Figure 1 A schematic diagram of selected components in a radio area network of a cellular wireless communication network.

[0020] Figures 3 to 8 A time sequence diagram is drawn showing the time slots detected for evaluating potential resources to be selected. Detailed Implementation

[0021] Those skilled in the art will recognize and understand that the specific details of the described examples are merely illustrative of some embodiments, and that the teachings set forth herein are applicable to various alternative settings.

[0022] Figure 1 This diagram illustrates three base stations (e.g., eNB or gNB, depending on the specific cellular standard and terminology) that make up a cellular network. Typically, each base station is deployed by a cellular network operator to provide geographic coverage for UEs in that area. The base stations form a Radio Area Network (RAN). Each base station provides wireless network coverage for UEs in its area or cell. The base stations interconnect via the X2 interface and connect to the core network via the S1 interface. Only basic details are shown here to illustrate the key features of the cellular network. Sidelink (SL) communication between UEs is achieved via the PC5 interface. Figure 1 The related interface and component names are for illustrative purposes only; different systems operating on the same principles may use different naming conventions.

[0023] Each base station contains the hardware and software that implements RAN functions, including communication with the core network and other base stations, control and data signaling between the core network and UEs, and maintaining wireless communication with the UEs associated with each base station. The core network includes the hardware and software that implements network functions, such as overall network management and control, and call and data routing.

[0024] In vehicle-to-vehicle (V2V) applications, onboard UEs can be integrated into vehicles such as cars, trucks, and buses. These onboard UEs can communicate with each other in both in-coverage and out-of-coverage modes. In in-coverage mode, the base station can manage and allocate resources to the UEs within the base station, while in out-of-coverage mode, no base station management or resource allocation is required. In vehicle-to-everything (V2X) applications, vehicles can communicate not only with other vehicles but also with infrastructure, pedestrians, cellular networks, and potentially other devices in the surrounding environment. Examples of V2X application scenarios include:

[0025] Vehicle platooning – This allows vehicles to dynamically form a platoon and travel together. All vehicles in the platoon receive information from the lead vehicle to manage the platoon. This information enables all vehicles to travel closer together than normally would, moving in the same direction in a coordinated manner.

[0026] Extended Sensor Capabilities – This enables the exchange of raw or processed data collected by local sensors or real-time video imagery between vehicles, roadside units, pedestrians, and V2X application servers. Vehicles can increase their environmental sensing beyond what their own sensors can detect, gaining a broader and more comprehensive understanding of local conditions. High data rates are one of the key features.

[0027] Advanced Driving – Enables semi-autonomous or fully autonomous driving. Each vehicle and / or RSU shares sensing data obtained from its local sensors with nearby vehicles, allowing vehicles to synchronize and coordinate their trajectories or maneuvers. Each vehicle also shares its driving intentions with nearby vehicles.

[0028] Remote driving – This enables remote drivers or V2X applications to operate remote vehicles for passengers who cannot drive themselves or for vehicles in hazardous environments. For situations with limited variation and predictable routes, such as public transportation, cloud-based driving can be used. High reliability and low latency are key requirements for this feature.

[0029] Figure 2 A base station 102 forming a RAN is shown, along with a UE 150 having a sidelink transmitter (i.e., UE-A) and a UE 152 having a sidelink receiver (i.e., UE-B) within the RAN. Base station 102 wirelessly communicates with SL Tx UE 150 and SL Rx UE 152 via their respective connections 154. Tx UE 150 and Rx UE 152 are used to wirelessly communicate with each other via sidelink 156.

[0030] Sidelink transmission utilizes traditional Uu transmission between the base station and the UE, operating on a dedicated or shared carrier using TDD (half-duplex). Resource pools are used to manage and allocate transmission resources, and to manage interference between potential concurrent transmissions. A resource pool is a set of time-frequency resources from which transmission resources can be selected. A UE can configure multiple transmit and receive resource pools.

[0031] There are two operating modes for resource allocation in sidelink communication, depending on whether the UE is within the coverage area of ​​the cellular network. In Mode 1, V2X communication operates within the coverage area of ​​the base station (e.g., eNB or gNB). All scheduling and resource allocation can be performed by that base station.

[0032] Mode 2 applies when sidelink service operates outside the coverage area of ​​the cellular base station, in which case the UE needs to make its own arrangements. For fair utilization, the UE typically uses sensed transmission resource allocation. In Mode 2, the UE selects the transmission resources it wishes to use for transmission and transmits a Sidelink Control Information (SCI) message indicating these resources. The recipient of the SCI message (which could be a single UE in unicast, a group of UEs in multicast, or all accessible UEs in broadcast) can obtain the expected transmission details through the SCI. The SCI message is the control information required to decode the sidelink data content and is also a reserved resource indication. The first-phase SCI is transmitted in the Physical Sidelink Control Channel (PSCCH), and the second-phase SCI is transmitted in the Physical Sidelink Shared Channel (PSSCH). The UE can reserve transmission resources for the initial transmission of the transport block (TB) and can also reserve transmission resources for repeated transmissions of the TB to improve reliability in the event of an initial transmission failure.

[0033] 3GPP TR 37.985, v16.0.0 describes the functionalities required for LTE and NR standards to support V2X services and adequately meet basic road safety service requirements. Vehicles with UEs containing these functionalities can use uplink, downlink, and sidelinks to exchange information about their own status, such as location, speed, and direction of travel, with other nearby vehicles, infrastructure nodes, and pedestrians. Sidelink communication improves efficiency through features including sidelink carrier aggregation, higher-order modulation, and reduced latency.

[0034] The apparatus, method, and system described in this application reduce device power consumption in a side-link autonomous resource selection mode. The set of time slots (sub-slots) to be sensed is configured and matched to the resource pool configuration. This is achieved by monitoring retransmitted reserved resources and periodically reserved resources. The apparatus, method, and system of this application also describe performing sensing by enabling downselection and configuring sensing functions to match user needs to achieve further power reduction.

[0035] In particular, the apparatus, methods and systems described in this application focus on improvements to the power consumption portion and the standard-defined portion of sensing.

[0036] In the LTE standard, to reduce power consumption and avoid the UE fully sensing the resource pool, the UE can have limited or no sensing capabilities. When the UE does not sense, it simply performs a random selection, but this carries the risk of collisions. A tradeoff method called "partial sensing" allows the UE to sense the resource pool for a limited time to search for reserved resources that might influence its selection. Reservation is periodic, with possible reservation periods being multiples of 100 milliseconds. During a partial sensing operation for resource selection, a partially sensing UE can select any resource within a selection window. If n is the resource selection time, the selection window is [n+T1, n+T2]. To determine whether a resource in the selection window is reserved, the partially sensing UE must sense potential transmission channels that might fall within the reserved resources of the selection window.

[0037] Figure 3 The required time slots are shown (only 8 1ms sensing slots are shown for clarity) to determine if the required time slot A is available. In this example, the limited-sensing UE senses all previous (logical) time slots to search for retransmission reserved resources.

[0038] Partial sensing is defined and permitted by Radio Resource Control (RRC or higher). If partial sensing is configured by a higher layer, the following two steps are used:

[0039] Step 1) The candidate single subframe resources Rx, y for PSSCH transmission are defined as subframes. A set of LsubCH consecutive sub-channels with sub-channels x+j, where j = 0,...,LsubCH-1. During implementation, the UE determines a set of subframes that consist of at least Y subframes within the time interval [n+T1, n+T2], where T1 and T2 are selected by the UE according to T1≤4 and T... 2min (prio TX If T ≤ T2 ≤ 100, then T 2min (prio TX (prio can be provided by a higher level) TX This parameter is set such that 20 ≤ T2 ≤ 100 otherwise. The Y value is set in RRC, where n is the resource selection time, n+T1 is the start of the selection window, and n+T2 is the end of the selection window. The UE will appropriately select T2 to meet the delay requirements, and the Y value must be greater than or equal to the higher layer parameter minNumCandidate SF. As described in Section 14.1.5 of TS36.213g20, the UE sets that for any LsubCH consecutive sub-channel groups within the PSSCH resource pool, consecutive sub-channels within a defined subframe set correspond to a candidate subframe resource. The total number of candidate single subframe resources is M. total .

[0040] Step 2) If subframe In the subframe set included in step 1, if the k-th bit of the higher-layer parameter gapCandidateSensing is set to 1, the UE will monitor the subframe. Where ty is the time of the selected resource, and Pstep is 100ms in LTE. The UE should perform the actions in the following steps based on the PSCCH decoded in these subframes and the measured S-RSSI values ​​of each subframe.

[0041] In LTE, the period is selected from a list of standardized values. When configuring some sensing UEs in a resource pool, the period can be set to a multiple of 100ms, with a maximum of 1000ms. Alternatively, a subset of multiples of 100ms can be configured by the ResourceReservePeriod parameter to select multiple periods allowed in the pool.

[0042] For partially sensing UEs, only a subset of resources (Y resources) within the selection window needs to be considered. Therefore, for a specific resource within the selection window (at time t_Y), checking t_Y-k*Pstep is sufficient, where Pstep = 100ms means the partially sensing UE checks once every 100ms, as this is the only possible location of the existing reserved resource for another UE to fall into during the required time. Thus, partially sensing allows the partially sensing UE to evaluate at least Y resources (resources configured in the resource pool) within the selection window.

[0043] In particular, partial sensing is configured using the gapCandidate Sensing parameter over an absolute time period. This parameter is a list of 10 Boolean values, where the k-th value (k = 1, ..., 10) tells the partially sensing UE whether it needs to sense k * 100 ms before evaluating resources.

[0044] If only partial period values ​​are allowed, the actual sensing required is reduced because only these periods result in reserved resources. However, these two lists are configurable independently, leaving ample flexibility in period configuration and partial sensing, depending on a trade-off between three factors: possible periods; reduced sensing power; and collision risk. Collision risk arises when a partially sensing UE does not need to sense for a period matching the configured timeframe to reduce its power consumption.

[0045] The resource pool can be configured to support periodic reservation, which can be configured up to 1000 milliseconds in advance. However, improper sensing may lead to conflicts. When configured to support periodic reservation, the resource pool has a sensing window that starts up to 1100 milliseconds before the resource selection time.

[0046] In NR, the possible periods (up to 16) in the resource pool can be set in the ResourceReservePeriod parameter, but this parameter can be greatly extended to allow any integer value between 1ms and 99ms, and to be a multiple of 100ms to 1000ms. Furthermore, NR introduces several different mechanisms that require partial sensing on the sidelink. In NR, the allocation of retransmission resources in terms of frequency and time is completely flexible, so up to 32 logical time slots can be reserved in advance (one or two). Reusing existing LTE partial sensing mechanisms to sense NR would require a very long bitstring pointing to all possible moments within the 1100ms window.

[0047] The devices, methods, and systems described in this application provide efficient signaling and configuration that enable the UE to perform partial sensing and obtain possible reserved resources for retransmission or periodically reserved resources based on the time periods defined in the NR and retransmission allocation.

[0048] In the resource pool, some sensing UEs can be configured or pre-configured to perform time slot sensing, which indicates retransmission resources that may conflict with potential resources selected by the sensing UEs for their own use.

[0049] In NR, SCI can reserve up to 32 logical time slots in advance (compared to a maximum of 16 logical time slots in LTE). To ensure that resources selected for evaluation are not continuously re-reserved, some sensing UEs perform sensing on all logical time slots prior to the selected time slot, which is within the retransmission time resource indication range.

[0050] By listening to only these 16 or 32 time slots, it is possible to avoid listening to the full 100ms sensing window (for non-periodic resource pools; 1100ms for resource pools that allow periodic reservations), thereby reducing power consumption.

[0051] To limit the cost of sensing 16 or 32 time slots before selecting the required resources, some sensing UEs can be configured to sense only a portion of the available time slots according to a (pre)configured mode. This mode can be preset using (pre)configured indexed signals or by using a bitmap to indicate the logical time slots to be sensed.

[0052] Figure 4 The required time slots are shown to determine if the desired time slot A is available. In this example, the partially sensing UE senses only 4 out of 8 (logical) time slots before searching for retransmission reservations for its selected resources.

[0053] Figure 5The displayed data shows a missed retransmission hold (SCI), which caused a conflict with the desired time slot A. While limiting sensing can save battery power, holding onto unsensed time slots can conflict with the retransmission hold. Therefore, a trade-off needs to be set up by configuration based on its traffic and the capabilities configured for each resource pool.

[0054] The resource selection for retransmissions in the resource pool of some sensing UEs can be configured so that retransmission resources are matched with the limited sensing time pattern. This limits the flexibility of resource allocation, but allows some sensing users to listen for all conflicting retransmission resources that may affect their resource selection.

[0055] Therefore, if the resource selection and retransmission for transmission are completed immediately in step 2 of the NR side-link resource allocation mode 2, then it is checked whether the selected candidate is suitable for the configured time mode. The time mode must be reversed; for example, if a partially sensing UE senses 5 time slots before evaluating resources, it means that the resources are reserved for retransmission 5 time slots in advance. If resources are selected independently for transmission and retransmission, then the devices, systems, and methods described in this application can remove any resources in the time slots not listened to by the partially sensing UE from the candidate resource set in step 1.

[0056] Limited sensing can be enabled / disabled using resource pool configuration flags. This feature may affect resource selection flexibility and device power consumption, so it should be enabled when a limited sensing UE is present or expected to be present in the resource pool.

[0057] This approach may be suitable for resource pools in blind transfer operations that always use reserved retransmission resources. HARQ-based retransmission resource pools may also benefit from this approach.

[0058] Partial sensing UEs can exchange functions between UEs and / or with the network. Partial sensing UE functions can define which sensing methods and / or how many measurements a partial sensing UE can perform; for example, a partial sensing UE can define which evaluation resource or each time unit it should sense. When exchanging this information, resource pools can be configured appropriately, for example, by determining which set of resources to listen to and whether to manage the functions and expectations of each partial sensing UE.

[0059] The method described in this application works regardless of whether the resource pool is configured only as a non-periodic resource or periodically reserved, and therefore can capture the retransmission of both types of reserved resources.

[0060] Even if these sensing methods are enabled in the resource pool configuration, these limited sensing methods can still be applied to some sensing UEs with limited sensing capabilities, and not necessarily to all UEs in the resource pool. This configuration can affect other sensing UEs not configured through the system and method described in this application by restricting their resource selection, etc.

[0061] Partial sensing UEs can be configured to perform sensing on a limited set of time slots in a resource pool, including all time slots that overlap with any configured possible reserved periods. These reserved periods may conflict with the evaluated resources. Therefore, the partial sensing function monitors time slots corresponding to time point t. y-j*Pi All time slots, where the period value P i It is configured in the ResourceReservePeriodList parameter, and j satisfies P. i *j≤SensingWindow.

[0062] Some sensing UEs can be configured to perform sensing on a limited set of time slots in the resource pool, including the last N time slots that coincide with a configured possible reserved period, which may conflict with the evaluated resources. Therefore, N can be (pre-)configured for each configured period. Figure 6 An example is shown where periods of 20ms and 50ms are configured in the resource pool. Partial sensing UEs evaluate the time slot marked as evaluation resource A by listening to the time slot every 20ms and every 50ms, without needing to sense or listen to other time slots. More specifically, sensing is performed on the exact time slot where periodic collisions may occur, and the exact listening duration is limited to listening to the first phase of the SCI that needs to be decoded on the PSCCH, and possibly listening to the second phase of the SCI in these specific time slots on the PSSCH to determine if it is the expected received data.

[0063] Therefore, some sensing functions will monitor the corresponding time point t. y-j*Pi All time slots, where the period value P i It is configured in the ResourceReservePeriodList parameter, and j satisfies j≤N.

[0064] To reduce sensing time and power consumption, when N=1, only the last time slot corresponding to the time difference equal to the configured possible period is sensed. Figure 7 In this configuration, only one time slot is sensed per configuration period; before evaluating resource A, one time slot is sensed every 50 milliseconds and another every 20 milliseconds. If the time slot corresponding to the moment of a potential periodic reservation conflict is not an SL time slot, some sensing UEs will sense that the moment corresponding to the last SL time slot is corresponding to the configuration period.

[0065] If any partially sensed UE performing periodic reservation has no data to transmit, it will not transmit on the reserved resources at all. Therefore, sensing only the last partially sensed UE (N=1) cannot guarantee whether periodic resources were reserved at that time. Therefore, to improve reliability, N>1 can be set.

[0066] To reduce sensing time, a limited set of sensing UEs can be configured to sense only time slots corresponding to a set of possible periods. While this offers power savings, it can lead to conflicts. The sensing period can be configured and signaled by setting the `ReducedSensingPeriodList` parameter, and can be represented using a bitmap with the same length as the list of possible periods.

[0067] Optionally, the apparatus, method, and system can set minimum and / or maximum period values ​​for the sensing period. These finite sensing periods can be configured to match the partially sensing UE functionality that signals through a resource pool. The partially sensing UE can be configured to perform sensing on a finite set of time slots in the resource pool, including all time slots that overlap with potentially reserved periods. These reserved periods may conflict with the evaluated resources. Therefore, the partially sensing functionality monitors the time corresponding to time point t. y-j*Pi All time slots, where the period value P i It is configured in the ResourceReservePeriodList parameter, and j satisfies P. i *j≤SensingWindow (or ≤N).

[0068] Partial sensing UEs can be configured to perform the partial sensing method described in this application within a limited sensing window.

[0069] In NR, a window of 1100 milliseconds for periodically activating resource pools is long compared to many short-cycle reservations. Therefore, reserving resource pools allows UEs with limited sensing capabilities to reduce their sensing windows to a minimum size, such as 100ms. The exact value of the sensing window can be left to implementation, but a minimum configured value can be limited. UEs with limited sensing capabilities can share their user-limited sensing capabilities, including the maximum possible sensing window size.

[0070] The apparatus, method, and system described in this application can be configured to activate / deactivate using a dedicated flag or by the presence or absence of desired configuration parameters. Such configuration changes can be triggered by a limited sensing of the presence of the UE and its functionality.

[0071] Typically, a sidelink resource pool will allow for multiple periodically reserved transmissions and retain multiple repeated non-periodic transmissions within a single SCI, where periodically reserved transmissions may also include retransmissions. Furthermore, periodically reserved transmissions may require a one-off transmission, for example, a retransmission can be performed within the packet delay budget upon receiving a HARQ NACK. Power-constrained UEs need to apply the strategy combination described in this application to minimize their sensing requirements.

[0072] Therefore, some sensing UEs will listen to a set of resources before their selection window (evaluation resource A) to sense any retransmission reserved resources that may conflict with the candidate resources. Then, some sensing UEs will sense the corresponding time slots from outside the retransmission reserved resources according to the period value set by the period configuration as part of the resource pool configuration.

[0073] Resource pool configurations can use appropriate fields to indicate the boundary between two intervals of partial sensing. The partial sensing boundary may be associated with transmission priority. For a simple example, a resource pool configuration can define a priority threshold. If a power-constrained UE is transmitting packets with a priority higher than this threshold, a boundary-indicating sensing event can be performed first, such as periodic and aperiodic partial sensing, with a duration limited to 100ms. If the packet priority is equal to or lower than this priority threshold, these UEs will perform partial sensing for a longer duration, either across the entire sensing window or indicated by explicitly configuring the duration as part of the resource pool configuration.

[0074] The sensing methods described in this application can further reduce power consumption caused by monitoring radio resources by configuring a UE with limited sensing capabilities to stop or suspend its monitoring of a set of time slots / sub-channels that correspond to potential reservation notifications of reserved resources.

[0075] exist Figure 8 In this context, the SCI is used to monitor reserved time slots for potential conflicts sensed by some sensing UEs. The SCI will reserve resources that overlap with evaluation resource A for another UE. When one of the resources is selected from the list of Y resources as the new evaluation resource, sensing for future conflict reservations will stop and be set to unavailable.

[0076] Optionally, a partially sensing UE can sense the last moment of a reserved conflict to verify whether the periodic resource is still in use. Note that if a limited-sensing UE is considering multiple frequency-division resources (different sub-channels) within the same time slot and only reserves a portion of that time slot, the limited-sensing UE can still monitor the remaining time slots to check for further conflicts with non-conflicting resources. This will still require the partially sensing UE to activate its radio reception, but it reduces the decoding and processing of the PSCCH area, which may still lead to further conflicts.

[0077] This interruption sensing applies to both periodically reserved partial sensing and retransmission partial sensing. In the case of periodically reserved partial sensing, potential collision moments use the same sub-channels as the selected resources, and these sub-channels can be easily identified and removed from sensing. In the case of retransmission partial sensing, retransmission resources have sufficient flexibility in both the time and frequency domains; therefore, to interrupt sensing at potentially conflicting time slots, all candidate resources for the selected time slot must have already been reserved to cancel monitoring of the corresponding time slot.

[0078] The following are various techniques related to sidelink communication power consumption, particularly reducing power consumption during sensing and transmission operations through resource scheduling. As described below, power-saving user equipment (PSUE – defined as a UE using power-saving techniques such as partial sensing) shares information about monitoring and transmission time slots to assist other UEs in scheduling their transmissions. Other UEs may use time slots designated for monitoring to transmit data or configuration / radio resource control (RRC) information to the PSUE, reservation information related to the PSUE (the PSUE may not be the destination of the reservation, but the reservation may affect which resources the UE selects for transmission), or scheduling information that the UE needs to know. Similarly, other UEs may use non-monitored time slots for transmissions unrelated to the PSUE, prioritizing them over monitored time slots.

[0079] As described above, the PSUE can be configured in partial sensing mode to monitor only a subset of transmission slots / resources before selecting transmission resources. Assuming the monitored resources relate to those available for transmission, the PSUE monitors a (pre-defined) set of previously defined slots for each slot containing potential transmission resources. Slots are monitored to detect periodic or forwarding reservations. While monitoring the PSUE, potential reservations for the entire slot must be listened to, and the SCI must be decoded in all possible PSCCHs for each monitored slot. It is then in listening mode with radio receiving hardware and decoding capabilities for the entire slot. The PSUE can be configured to receive data in the monitored slot; it should also decode a second-stage SCI in the corresponding PSSCH to check if it is the destination. If so, it can further decode the PSSCH payload transmitted in the same slot, meaning the receiver can receive data during a single "on" period, rather than just being on for receiving scheduling information. In NR, the retransmission reservation mechanism allows any time-frequency resource to be reserved within a given future window (32 slots). Because the frequency of the resources can be changed (and noted in the reserved SCI), when a UE wants to monitor potential reservations that conflict with candidate resources, it must decode all possible frequency locations of the SCI in the monitoring slot. For periodic reservations and monitoring, periodic reservations automatically reserve the same frequency resources as those transmitted in the future. However, because the size of the resources may vary, the PSUE should still monitor most possible PSCCH locations to address potential conflicts.

[0080] For example, the PSUE can be (pre-)configured as a sidelink receiver and partially monitor time slots according to the configuration. The PSUE can select the time slots to monitor based on the configuration defined for the UE or based on the configured candidate transmission time slots and sensing modes. The PSUE explicitly or implicitly communicates information about the monitored time slots to other UEs. UEs transmitting to the PSUE use the shared information as input for transmission time slot selection.

[0081] The time slots that the PSUE needs to monitor are defined in a deterministic way. For example, time slots can be (pre-)defined for the PSUE and shared among related devices, or the PSUE's transmission time slots can be (pre-)defined and shared so that the time slots to be monitored can be derived from their relationship with the transmission time slots.

[0082] In the first approach, the PSUE defines a set of monitored time slots and transmits information about these time slots to other UEs. The monitored time slots can be selected from a receive resource pool configured for the PSUE. Information about this set can be shared with other UEs using an appropriate format, such as a bit string or equivalent pattern. The PSUE can use PSSCH (Media Access Control, MAC Level) scheduling information. PSSCH data can be transmitted as unicast or multicast to the relevant UEs, or as broadcast to all UEs with receive range. The monitoring sequence length and periodicity can be (pre-)configured for the PSUE or the relevant resource pool. This approach is expected to be readily implementable, but incurs overhead when periodically transmitting information for monitored time periods.

[0083] A monitoring resource set can be defined as a power-saving resource pool (PSRP) for multiple PSUEs. In one example, it is a (sparse) receive resource pool. Such resource pools can be defined with parameters to achieve power-saving behavior across multiple PSUEs. A PSUE can be configured to monitor all time slots in the PSRP, just as a normal UE does in its allocated resource pool. The time slot structure of the PSRP defines the monitoring scope of the PSUE. The PSRP can be configured to be relatively sparse in time slot allocation to avoid the PSUE being active on too many time slots, thus increasing power consumption. A dedicated time slot selection format or a predefined sequence can be defined to provide a sparse time slot structure for the PSRP.

[0084] When PSRP is configured, other UEs that transmit to a PSUE configured with PSRP utilize PSRP resources to transmit to the PSUE.

[0085] To avoid restricting access to transmission resources for UEs without power-saving requirements, other UEs can be configured with a resource pool that overlaps with the PSRP. This resource pool and the PSRP should have a similar port physical layer (PHY) structure and configuration (e.g., subchannel size, SCI format, physical sidelink shared channel (PSFCH) design, etc.).

[0086] A UE can be configured with multiple resource pools, and one resource pool is always active. Some resource pools configured for the UE may be PSRPs, which may be implicitly represented by their characteristics (such as sensing modes) or explicitly represented by indicators such as flags.

[0087] It should be understood that, to avoid misunderstandings regarding timing and reservations, the UE needs to switch the logical time slots used with the regular resource pool and PSRP to understand when reservations and transmissions actually occur. This can be done if the UE is aware of the different resource pools active each time.

[0088] In a specific example, the PSRP can be defined as a subset of a resource pool. The PSRP can be defined as a sub-resource pool within the resource pool, available only to the PSUE receiver. The subset of time slots is sent via (pre)configuration, and the inclusion of resource time slots in the PSRP can be selected based on a set of binary logical time slots. The configuration of the PSRP is similar to its associated main resource pool, but only a subset of time slots. This avoids configuration compatibility issues and saves configuration overhead or logical time. UEs communicating with a PSUE should use the subset of PSRP to perform their transmissions. UEs communicating with non-PSUEs should preferentially use resources not in the subset of PSRP to perform their communication, keeping PSRP resources free.

[0089] By sharing PSRP (pre)configuration information with other UEs, the PSUE can inform other UEs which time slots it is monitoring. This (pre)configuration information can be shared as RRC parameters or pre-configured to the UE. Therefore, each UE is aware of the receiving capabilities of other UEs during connection configuration, providing stable, non-dynamic modifications, which is preferred because monitoring periods can be long; thus, stable configuration is preferred.

[0090] As mentioned above, monitoring slots can also be defined based on the deterministic definition of transmission slots. The transmission slots of the PSUE can be defined early enough (either by the PSUE or through configuration) so that the corresponding monitoring slots are known and can be shared with other UEs.

[0091] A transmission time slot can be defined as:

[0092] Dedicated transport resource pool. The PSUE's transport pool can be set to be sufficiently sparse (to ensure limited sensing and processing) and to adapt to good behavior in monitoring modes (e.g., by using time slots whose monitoring modes are consistent with each other).

[0093] A subset of the regular transport pool. A set of binary time slots matching the configured transport pool can be applied to select time slots for the transport pool below; these time slots will be the possible transport time slots for the PSUE.

[0094] In the regular transport resource pool, PSUE additionally uses transport opportunities dynamically defined by PSUE.

[0095] The PSUE performs some sensing corresponding to (pre-defined) patterns that it has historically monitored to check reservations that will align with its intended use of transmission resources. These patterns can check broadcast reservations (using logical time slots) and / or periodic reservations (absolute time). The patterns to be used can be pre-defined, reused from other systems (e.g., LTE), or specifically configured for NR sidelink communication. Using the patterns and (pre-defined) transmission time slots, the PSUE can deduce the time slots to be monitored prior to these transmission time slots.

[0096] The PSUE can be configured to transmit its transmission slots to other UEs. Other UEs can combine this information with (pre)configured partial sensing patterns to deduce the slots the PSUE will monitor. If the transmission slots are defined as dedicated resource pools or sub-resource pools, the configurations of these pools can be shared among UEs (as RRC information). If multiple transmission resource pools are configured, the PSUE can exchange references (e.g., indexes) to the active transmission resource pools used by other UEs.

[0097] If the transmission slots are directly defined by the PSUE, it must transmit its expected transmission slots to other UEs in advance. This can be done dynamically using PSSCH to transmit the information. Transmissions can also be performed periodically (e.g., using periodic transmissions) to update other UEs whenever a configuration update or new settings become available, or as needed. This transmission can be unicast / multicast (to a single user / group connected to the PSUE) or broadcast (notifying all UEs within range).

[0098] When a UE receives a future resource reservation from a PSUE, it assumes that the corresponding time slot is a transmission opportunity for the PSUE. When a PSUE sends a future resource reservation, it means that the PSUE will transmit in the said time slot. This can be used for replay or periodic reservations. When a UE monitors and receives such reservations from a PSUE, it can assume that the reserved time slot is within the PSUE's transmission time slot, and thus derive the expected monitoring time slots based on these reservations and partial sensing patterns. The UE can also use the PSUE's reservation history and locally compiled statistics to infer the PSUE's usual transmission time slots and assume that they are also the PSUE's future transmission time slots.

[0099] The PSUE can determine the location and frequency (or density) of transmission opportunities based on its traffic, traffic history, traffic type, or quality of service (QoS). If based on a TX resource pool, the PSUE can adjust the TX resource pool used according to its traffic demand. Based on its continuous or anticipated traffic, the PSUE can determine its demand for transmission slots or transmission slot opportunities. Transmission slot candidates should reflect that each potential transmission will consider a resource selection window that includes several resource candidates (at least Y in LTE versions). For example, traffic with deterministic packet arrival times can predict its transmission demand. Changes in traffic demand can trigger changes in transmission configuration (e.g., the transmission mode or transmission resource pool used), and this change should be reported to other UEs.

[0100] The following is an example of a communication process with PSUE, which applies the principles described above to define and share its monitoring and transmission time slots.

[0101] The traditional NR Mode 2 resource selection procedure uses two principle steps. First, it identifies available / candidate resources, and second, it selects the resources to be used for transmission from the candidate resources.

[0102] In the first example using shared information, when selecting resources, the UE can define candidate time slots for transmission as time slots monitored by the PSUE. As step 1 of the resource selection identification phase, the transmitting UE will examine all candidate resources in a set of time slots, which may correspond to the transmission resource pool of the UE belonging to the resource selection window. This is particularly relevant in the general procedure:

[0103] Symbol: (t) 0SL , t 1SL , t 2SL , ...) represents the set of time slots that can belong to the sidelink resource pool, and is defined in Article 8.

[0104] 1) Candidate single-slot resource R for transmission x,y Defined as a set of L subCH Continuous sub-channels, sub-channel x+j in time slot tySL, where j = 0, ..., L subCH-1 The UE should assume that any set of L contained in the corresponding resource pool within the time interval [n+T1, +T2] subCH A continuous subchannel corresponds to a candidate single-slot resource, where:

[0105] Choose T1 where 0 ≤ T1 ≤ T proc,1SL The following implementation, where time slot T proc,1SL Defined in Table 8.1.4-2, where μ SLIt is the subcarrier spacing (SCS) configuration of the sidelink bandwidth part (SL BWP);

[0106] If T 2min If the delay is shorter than the remaining packet delay budget (in the time slot), then T2 depends on the UE implementation, but T 2min ≤T2≤Remaining packet budget (in the time slot); otherwise, T2 is set to the remaining packet delay budget (in the time slot).

[0107] The total number of candidate single-slot resources is denoted by M. total express.

[0108] Modify the first part of this process so that the output of step 1 corresponds to the resource selection window, the time slot set of the transport resource pool, and the resources in the monitoring time slot of the PSUE.

[0109] This can be accomplished in the following ways:

[0110] MAC selects the time slot used as the process input (i.e., time slot t) downwards. 0SL , t 1SL , t 2SL This means that the scheduling between the PSUE monitoring time slot and the UE transmitting to it can be maintained at the MAC level.

[0111] - Alternatively, the PHY may perform downlink selection by preserving the original time slot set, but by changing the included time slots or j=0,...,L in step 1. subCH A subset of the data is used to perform downlink selection, so that only the monitored time slots are monitored. This requires the PSUE to exchange information about the monitored time slots from the MAC layer to the PHY layer (assuming it was originally known by the MAC layer).

[0112] In this example, candidate resource M total This only includes candidate transmission slots for UE transmission and PSUE reception. However, according to normal procedures, this equipment will still be subject to further exclusion and downward selection.

[0113] In the second example, the exclusion step for identifying candidate resources can be modified to remove resources from time slots not monitored by the PSUE. In the traditional resource identification procedure, resources are excluded if they meet certain conditions:

[0114] 5) If all of the following conditions are met, the UE should allocate any candidate single-slot resource R x,y Excluded from set S A In the middle: The UE did not monitor the time slot t in step 2. mSL .

[0115] For higher-level parameters sl-ResourceReservePeriodList and in time slot t mSL The received assuming SCI format 1-A allows any periodic value, its "Resource Retention Period" field is set to the periodic value, and indicates that all sub-channels of the resource pool in this time slot will satisfy condition c in step 6.

[0116] 6) If all of the following conditions are met, the UE should allocate any candidate single-slot resource R x,y Excluded from set S A middle:

[0117] a) UE in time slot t mSL If an SCI format 1-A is received, and if a "Resource Retention Period" field exists, and a "Priority" field exists in the received SCI format 1-A, the value P is represented according to Clause 16.4 of the European Telecommunications Standards Institute (ETSI) [6, TS 38.213]. rsvp_RX and prio RX ;

[0118] b) According to clause 8.4.2.1, the reference signal receiving power (RSRP) measurement performed on the received SCI format 1-A is higher than Th(prio RX );

[0119] c) In time slot t mSL Or, the SCI format received in the same SCI format, if and only if the "Resource Retention Period" field exists in the received SCI format 1-A, assuming in time slot t m+q×Prsvp_RX′SL The system receives data and determines a set of resource blocks and time slots according to clause 8.1.5, which is related to R. x，+j×Prsvp_TX′ Overlap, q = 1, 2, ... Q, j = 0, 1, ..., C resel -1. Here, P rsvp_RX′ For P rsvp_RX According to clause 8.1.7, the unit is converted to a logical time slot if P rsvp_RX <T scal and n'-m≤P rsvp_RX′ , where Q = [T scal P rsvp_RX ], time slot t n’SL =n, if n belongs to set (t) 0SL,1SL ,…,t TmaxSL ...), otherwise, time slot t n’SL It is in the first time slot of time slot n; otherwise, Q = 1, and n belongs to the set (t).0SL,1SL ,…,t TmaxSL ...). T scal Set the selection window size T2 to be converted to milliseconds.

[0120] In this example, the exclusion procedure has been modified to include the exclusion of resources not monitored by the PSUE. In this example, the MAC should inform the PHY which time slots are monitored by the target PSUE (assuming the MAC initially retains this information). From the transmitter's perspective, candidate resource M... total This includes all initially selected resources, while the number of available candidate resources after exclusion takes into account transmitter, sensor, and PSUE constraints.

[0121] When step 7 above (3GPP TS 38.214 Section 8.1.4: Check if the output contains at least X. Candidate resource M) total If the first option is selected, it is more likely to satisfy requirement X because candidate resource M is selected. total Only resources monitored by PSUE are included; therefore, it's unlikely that increasing the RSRP power threshold to include more resources would provide more interference to the MAC layer. However, the first option provides fewer resources than the second.

[0122] In the third example, resource selection might be modified to remove candidate resources belonging to non-monitored time slots. Instead of excluding resources not monitored by PSUE in the PHY layer, this can be done at the MAC layer after resource identification is complete. This utilizes the traditional resource identification process, but after reporting the available resource set, the MAC layer excludes non-monitored resources before selecting the actual transport resources.

[0123] Please note that because the PHY layer does not delete unmonitored time slots, there may be few or no suitable resources available. In this case, the MAC layer can delete the transport or perform a reselection, providing a more suitable set of time slots to choose from (i.e., similar to the first option).

[0124] When a UE is preparing to transmit resources to a PSUE, parameters X and RSRP thresholds can be configured separately from those for regular users. This results in additional RRC configuration for the resource pool (RP) receiving the PSUE. For example, X can be set to a higher value to ensure more candidate users who might be further reduced in selection (especially in candidate resource M). total (Including resources that PSUE may not be monitoring).

[0125] In current LTE, power-limited users, specifically pedestrian UEs, can be configured to perform only transmissions, particularly during user location / identity (ID) transmissions. In this case, the UE does not need to perform any sensing before transmission, which may lead to collisions. Power-limited users can also be configured to perform partial sensing to be able to receive some data or perform more reliable resource selection (avoiding collisions).

[0126] In this embodiment, the PSUE is (pre-)configured to enable or disable the reception of sidelink transmissions. This (pre-)configuration follows UE functionality that specifies that this PSUE is capable of power-limited reception of sidelink data. Since the target ID is specified in the second-stage SCI for sidelink information, and the retention mode / periodicity is in the first-stage SCI, the following is observed:

[0127] When not configured as “receive capability”, a PSUE performing some sensing (e.g., partial or full sensing) only needs to decode the first-stage SCI, i.e., PSCCH, to obtain information on resource reservation.

[0128] When configured as “Receive Capability”, the PSUE should be able to detect and decode the first and second phase SCIs, as well as the data payload when the PSUE is the transmission destination.

[0129] For a PSUE with receiving capabilities, it can be configured to listen to the first and second phase SCIs only in the time slots configured to be monitored; while it may only listen to the first phase SCI or other time slots that do not have it (e.g., time slot splitting can be based on the configured RP and PSRP).

[0130] When the PSUE is configured as a "receiver," it will periodically sense whenever it has data to transmit, while monitoring time slots selected based on TX. If the PSUE has no data to transmit, it should still monitor other UE-known patterns to receive some RX. The PSUE can be (temporarily) configured as a limited receiver / can use a specific defined portion of the regular sensing patterns / sub-patterns.

[0131] When the PSUE receives data in sparse monitoring mode, it may trigger more frequent monitoring mode changes if the received data and connection require QoS that is incompatible with sparse monitoring.

[0132] In summary, various sidelink communication methods are provided between UEs. A UE can be configured to monitor only a subset of time slots and can explicitly or implicitly communicate information about these time slots to other UEs. UEs can communicate transmission time slots, from which monitored time slots can be identified. A UE communicating with a UE specifying its monitored time slots can only transmit to the UE in those monitored time slots. When selecting sidelink transmission resources, particularly in Mode 2, the UE should make the selection at least in part based on the indication of the monitored time slots.

[0133] Although not shown in detail, any device forming part of the network may include at least a processor, a storage unit, and a communication interface, wherein the processor, storage unit, and communication interface are configured to perform methods of any aspect of the invention. Further options and choices are described below.

[0134] Embodiments of the present invention, particularly the signal processing functions of the gNB and UE, can be implemented using computer systems or architectures known to those skilled in the art. This computer system can be a desktop computer, laptop computer or notebook computer, handheld computing device (PDA, mobile phone, PDA, etc.), server, client, or any other type of general-purpose computing device required for a given application or environment. The computer system may include one or more processors, which can be implemented using general-purpose or special-purpose processing engines, such as microprocessors, microcontrollers, or other control modules.

[0135] A computer system may also include main memory, such as random access memory (RAM) or other dynamic memory, for storing information and instructions that can be executed by the processor. This main memory may also be used to store temporary variables or other intermediate information needed during the execution of instructions by the processor. A computer system may also include read-only memory (ROM) or other static storage devices for storing static information and instructions of the processor.

[0136] The computer system may also include an information storage system, which may include media drives and removable storage interfaces. Media drives may include drives or other mechanisms for securing or supporting removable storage media, such as hard disk drives, floppy disk drives, magnetic tape drives, optical disc drives, optical disc (CD) or digital video drive (DVD) (RTM) read or write drives (including writable or erasable drives), or other removable or secured media drives. Storage media may include, for example, hard disks, floppy disks, magnetic tapes, optical discs, CDs, or DVDs, or other secured or removable media read and written by media drives. Storage media may include computer-readable storage media having specific computer software or data stored therein.

[0137] In alternative embodiments, the information storage system may include other similar components for allowing computer programs or other instructions or data to be loaded into the computer system. Such components may include, for example, removable storage units and interfaces, such as program boxes and box interfaces, removable memory (e.g., flash memory or other removable memory modules) and memory slots, as well as other removable storage units and interfaces that allow software and data to be transferred from the removable storage units to the computer system.

[0138] Computer systems may also include communication interfaces. These interfaces allow the transfer of software and data between the computer system and external devices. Examples of communication interfaces may include modems, network interfaces (such as Ethernet or other NIC cards), communication ports (such as Universal Serial Bus (USB) ports), PCMCIA time slots and cards, etc. The software and data transferred via the communication interface are in the form of signals, which can be electronic, electromagnetic, optical, or other signals that can be received by the communication interface medium.

[0139] In this document, the terms "computer program product," "computer-readable medium," etc., are generally used to refer to tangible media, such as memory, memory devices, or storage units. These and other forms of computer-readable media may store one or more instructions for use by a processor, including a computer system, to cause the processor to perform specified operations. Such instructions are generally referred to as "computer program code" (which may be grouped as a computer program or other groupings). When executed, the computer system is able to perform the functions of embodiments of the present invention. Note that the code may directly cause the processor to perform specified operations, be compiled to perform such operations, and / or be combined with other software, hardware, and / or firmware elements (e.g., function libraries for performing standard functions) to perform such operations.

[0140] Non-transitory computer-readable media may include at least one of the following: hard disk, CD-ROM, optical storage device, magnetic storage device, read-only memory, programmable read-only memory, erasable programmable read-only memory, EPROM, electrically erasable programmable read-only memory, and flash memory. In embodiments using software-implemented components, the software may be stored in a computer-readable medium and loaded into a computer system using, for example, a removable storage drive. The control module (in this example, software instructions or executable computer program code), when executed by a processor in the computer system, causes the processor to perform the functions of the invention as described herein.

[0141] Furthermore, the inventive concept can be applied to any circuit used to perform signal processing functions within network components. It is further envisioned that, for example, semiconductor manufacturers can incorporate the inventive concept into the design of standalone devices, such as microcontrollers for digital signal processors (DSPs), or application-specific integrated circuits (ASICs) and / or any other subsystem elements.

[0142] For clarity, the above description refers to embodiments of the invention with reference to a single processing logic. However, the inventive concept can also be implemented by multiple different functional units and processors to provide signal processing functionality. Therefore, references to specific functional units are considered merely as references to appropriate means of providing the described functionality, and not as indicating a strict logical or physical structure or organization.

[0143] Various aspects of this invention can be implemented in any suitable form, including hardware, software, firmware, or any combination thereof. This invention can be implemented, at least in part, as computer software running on one or more data processors and / or digital signal processors or configurable module components such as FPGA devices.

[0144] Therefore, the components and elements of embodiments of the present invention can be implemented physically, functionally, and logically in any suitable manner. In fact, the function may be implemented in a single unit, in multiple units, or as part of other functional units. Although the invention has been described in conjunction with some embodiments, it is not intended to be limited to the specific forms set forth herein. Rather, the scope of the invention is limited only by the appended claims. Furthermore, although features appear to have been described in conjunction with specific embodiments, those skilled in the art will recognize that various features of the described embodiments can be combined according to the invention. In the claims, the term "comprising" does not exclude the presence of other components or steps.

[0145] Furthermore, although listed separately, multiple means, components, or method steps can be implemented by, for example, a single unit or processor. Additionally, while individual features may be included in different claims, these features may be advantageously combined, and inclusion in different claims does not imply that such combination of features is infeasible and / or advantageous. Moreover, including a feature in one claim class does not imply limitation on that class, but rather indicates that the feature is equally applicable to other claim classes where appropriate.

[0146] Furthermore, the order of features in the claims does not imply that these features must be performed in any particular order, and in particular, the order of steps in a method claim does not imply that these steps must be performed in that order. On the contrary, these steps may be performed in any suitable order. Moreover, singular references do not exclude plural forms. Therefore, references to “a,” “an,” “first,” “second,” etc., do not exclude plural forms.

[0147] Although the invention has been described in conjunction with some embodiments, it is not intended to be limited to the specific forms set forth herein. Rather, the scope of the invention is limited only by the appended claims. Furthermore, although features appear to have been described in conjunction with specific embodiments, those skilled in the art will recognize that various features of the described embodiments can be combined according to the invention. In the claims, the terms "comprising" or "including" do not exclude the presence of other elements.

Claims

1. A sidelink communication method between at least two user equipments (UEs) in a cellular communication network, characterized in that, The method comprises: defining an energy saving resource pool used by energy saving UEs; transmitting, from a base station, an indication of transmission resources in the energy saving resource pool to at least two UEs; and using only the transmission resources of the energy saving resource pool when communicating with or transmitting from the energy saving UEs; wherein the energy saving resource pool is defined as a subset of time slots within a resource pool; the energy saving UEs only monitor time slots in the energy saving resource pool before transmission; the energy saving UEs communicate information about the monitored time slots to other UEs, UEs transmitting to the energy saving UEs use the shared information as input for transmission time slot selection, wherein the configuration of the energy saving resource pool is further used to indicate partial sensing time interval boundaries, the partial sensing time interval boundaries are associated with the priority of data to be transmitted; when the priority of data information transmitted by the energy saving UEs is higher than a preset priority threshold, the energy saving UEs only perform partial sensing for a limited duration; when the priority of the data information is equal to or lower than the priority threshold, the energy saving UEs perform partial sensing for a longer duration; and the energy saving UEs are configured to stop or suspend monitoring of a set of time slots and / or sub-channels corresponding to reserved resources.

2. The method of claim 1, wherein, The energy saving resource pool is defined as a subset of a resource pool used by the at least two UEs.

3. The method of claim 1, wherein, The indication of transmission resources in the energy saving resource pool is sent using RRC signaling.

4. The method of claim 1, wherein, UEs using the energy saving resource pool send an indication of resources in the energy saving resource pool to other UEs.

5. The method of claim 1, wherein, The energy saving resource pool is defined by UEs using the resource pool.

6. The method of claim 1, wherein, The energy saving resource pool is defined by the base station.

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