Energy saving for sidelink communication

Abstract

For energy-saving user equipment (UE), specific control areas can be defined to control transmissions to and / or from the power source to the energy-saving UE, allowing the energy-saving UE to listen only within a limited time or frequency range. A primary UE can be specified to select and reserve resources for UE sidelink communication and to notify the UE which resources to use.

Description

Technical Field

[0001] This disclosure relates to resource allocation for sidelink communication in a cellular network. 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 to provide services with lower latency and higher reliability. For example, NR is designed to support Ultra Reliable and Low Latency Communication (URLLC), while Massive Machine Type Communication (mMTC) is designed to provide low latency and high reliability for small data packets (typically 32 bytes in size), 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 invention is defined by the claims, which provide a method for transmitting sidelink control signals in a cellular communication network. The method includes the following steps: configuring a power-saving control region for transmission resources used by a power-saving user equipment (UE), wherein the transmission resources are a resource pool allocated for sidelink transmission, and wherein the power-saving control region is different from the control region of the resource pool; selecting a transmission resource from the power-saving control region for the power-saving UE; and sending a sidelink control signal to the power-saving UE through the selected transmission resource.

[0010] The power-saving control region is defined by time frequency and period, wherein the period is the repetition of the resource pool in the power-saving control region.

[0011] The frequency resources within the power-saving control area are a subset of all frequency resources available for side link transmission.

[0012] The transmission resources within the energy-saving control area overlap in time but not in frequency, and these transmission resources are allocated to feedback transmission.

[0013] The step of selecting transmission resources includes: sending a request from the UE to the base station; identifying the target UE as the power-saving UE; allocating resources from the power-saving control area by the base station; and sending an indication of the allocated transmission resources from the base station to the UE.

[0014] The step of selecting transmission resources is performed by the UE that is preparing to transmit to the energy-saving UE.

[0015] This disclosure also provides a method for sidelink transmission in a cellular communication network, the method comprising the following steps: sending an SCI message from a first user equipment (UE) to a second UE, wherein the indication time slot indicated by the SCI message is used for data transmission, and the indication time slot is different from the time slot used to transmit the SCI message; and the first UE sending a data message to the second UE through the indication time slot indicated by the SCI message.

[0016] The SCI message is a first-phase SCI message, which includes an implicit indication of the start of frequency resources for data transmission.

[0017] The SCI message includes the side link control signal.

[0018] The data transmission uses resources from different resource pools in the SCI message, and the SCI message identifies different resource pools.

[0019] This disclosure also provides a transmission resource allocation method for lateral link transmission in a cellular network, the method comprising the following steps: reserving transmission resources for other UEs to use for lateral link communication in a first user equipment (UE); sending an indication of reserving transmission resources to the other UEs to receive; and one of the other UEs selecting transmission resources from the reserved transmission resources for lateral link communication.

[0020] The indication of reserved transmission resources is an SCI message.

[0021] The reserved transmission resources include multiple resource groups, each resource group is assigned to a group of UEs, and each UE is only allowed to select transmission resources in the corresponding resource group.

[0022] The reserved transmission resources are periodic transmission resources.

[0023] The indication for reserving transmission resources is periodic transmission.

[0024] The indication of reserving transmission resources includes the side link control signal as described in any one of claims 1 to 6.

[0025] The other UEs randomly select transmission resources from the allocated reserved transmission resources.

[0026] The first UE executes the method to transmit resources in response to a request from another UE.

[0027] The request is an RRC signal.

[0028] The request uses a sequence-based format, wherein time-frequency resources and sequences are selected based on the identity of the requesting UE.

[0029] The indication of reserved transmission resources includes a one-bit graph.

[0030] This disclosure also provides a method for sidelink transmission in a cellular communication network, the method comprising the following steps: a first UE sending a scheduling request; a second UE receiving the scheduling request and selecting transmission resources required by the first UE according to the transmission indicated by the scheduling request; the second UE reserving the selected resources for use by the first UE; and transmitting an indication of the reserved resources from the first UE to the second UE.

[0031] The scheduling request is a broadcast message.

[0032] The scheduling request is an RRC message.

[0033] The scheduling request is directed to the UE designated as the primary UE responsible for allocating resources.

[0034] The scheduling request is a sequence-based signal.

[0035] This disclosure also provides a user equipment configured to perform the aforementioned methods. Attached Figure Description

[0036] 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.

[0037] Figure 1 and Figure 2 This displays a schematic diagram of the selected element in a cellular communication network. Detailed Implementation

[0038] 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.

[0039] 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.

[0040] 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.

[0041] In addition to uplink / downlink communication between the UE and the base station, sidelink communication can also be realized for direct communication between UEs. Figure 2 A base station 102 forming a RAN is shown, along with a UE 150 having a sidelink transmitter (SL Tx UE) and a UE 152 having a sidelink receiver (SL Rx UE) within the RAN. While UE 150 and UE 152 are described as transmitter and receiver, this is for illustrative purposes only during a specific communication session, and their roles can also be reversed. 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.

[0042] 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.

[0043] 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.

[0044] Mode 2 applies when the sidelink service operates outside the cellular base station coverage area, in which case the UE needs to make its own arrangements. For fair utilization, the UE typically uses sensed transmission resource allocation. Resource selection involves two steps. In step 1, the UE identifies resources deemed available, and in step 2, selects a specific resource for transmission. Step 1 can begin with a selection window of all resources, then removes those not considered candidates (e.g., resources reserved by another UE with an SL-RSRP higher than a threshold). The resource selection process may be randomized and may have constraints such as HARQ timing and delays between resources.

[0045] In Mode 2, the UE selects the transmission resources it wishes to use for transmission and transmits a Sidelink Control Information (SCI) message that indicates 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.

[0046] Existing sidelink communication development focuses on "always-on" devices, for which power consumption is not a major concern. The following reveals solutions to power-saving issues associated with using sidelink communication with UEs (Power Saving User Equipment, PSUE) that have limited power budgets.

[0047] This application provides various processes and systems designed to reduce power consumption in sidelink communication PSUEs. Current sidelink communication arrangements require the UE to continuously listen to allocated sidelink transmission resources in order to make possible transmissions to the UE. However, this arrangement consumes a significant amount of power and is unsuitable when power budgets are limited. In the first part of this application, resource allocation processes are described that are designed to reduce power consumption of the PSUE receiving transmissions. In particular, a specific periodic control region is defined within the transmission resources of a subset of time and frequency resources. The control region is used to transmit control / scheduling commands to the PSUE. By restricting the transmission of control / scheduling commands to the periodic control region, the PSUE only needs to listen to these control regions, thereby reducing power consumption. Signaling processes are also defined to allow cross-timeslot scheduling and cross-resource pool scheduling.

[0048] In the second part of the embodiments of this application (which can be used in conjunction with the first part), a UE system operating in mode 2 is proposed, in which the primary UE assumes the responsibility for transmission resource allocation, thereby reducing the requirements for the PSUE to perform resource selection procedures and thus reducing its power consumption.

[0049] As described above, currently, the sidelink UE must continuously listen to all its received resource pools to monitor the reception of SCI messages, as such messages can be received in any sidelink time slot and any subchannel. Since SCIs are transmitted through subchannels used for the same data transmission, the sidelink UE must listen to the configured frequency resources (subchannels) of all resource pools. To reduce this requirement, the UE can be configured to listen only to a subset of sidelink time slots and frequency resources by configuring control / scheduling commands to be transmitted only in a subset of the time slots and resources. Therefore, the UE is only active for a portion of the time and only needs to listen within a narrower frequency range, thus reducing power consumption.

[0050] To achieve this, the control region can be defined as a resource pool with a defined periodicity. Alternatively, the control region can be defined as part of the resource pool configuration, so that all PSUEs configured with the resource pool only need to listen to the resource pool's control region. This control region differs from the regular control region of the resource pool; it spans the entire frequency dimension for the first two or three symbols and repeats in each time slot. This approach makes the concept applicable to all broadcast types because UEs performing multicast and broadcast transmissions may include PSUEs as receivers, and therefore, their control / scheduling commands can be transmitted in the control region knowing that the PSUEs will be listening for transmissions.

[0051] Resource pool configuration defines the periodicity of time-frequency resources and control regions repeating within the resource pool. A variation of this approach defines control regions based on time and frequency resources. Furthermore, the periodicity and multiplexing of multiple control / scheduling commands within a defined control region can be controlled by configuring a search space and associating the search space with that space. Search space configuration can also be performed as part of the resource pool configuration.

[0052] All relevant UEs will learn about the control area and resource pool configuration used by the PSUE from the resource pool configuration process. Therefore, they can arrange to control / arrange the PSUEs transmitted to these resources so that they will be received by the PSUEs listening in the control area.

[0053] In a conventional arrangement, sidelink control / scheduling commands are transmitted in the first two or three symbols of a time slot. However, the control area defined for these commands is not limited to these symbols and can be defined in any suitable area. The control area can be defined as a finite frequency range to reduce listening bandwidth, but this reduces the number of control / scheduling commands that can be multiplexed using resources. To increase the number of commands that can be transmitted in the control area, the time of the area can be extended, for example, occupying the entire sidelink time slot. Therefore, a smaller frequency area can be used to carry an increased number of transmissions.

[0054] Currently, if a specific sidelink time slot has feedback resources / opportunities, the slot symbols and symbols containing sidelink feedback resources are not used for transmitting control / scheduling commands, but this reduces available resources. The arrangement can be modified so that if the control area and feedback resources overlap in time but not in frequency (not a single overlapping physical resource block (PRB)), the time overlap portion of the control area can be used for transmitting control / scheduling commands. This increases the available resources for transmitting control / scheduling commands to the PSUE.

[0055] When a sidelink UE operates in Mode 1 according to these principles, it will transmit a request for sidelink transmission resources to the base station. If the base station identifies the target UE as a PSUE, it will schedule control / scheduling commands in the control area of ​​the resource pool configured for the PSUE. As with the normal procedure, the base station instructs the requested UE to perform the transmission. If the sidelink data resources differ from the sidelink control resources, the downlink control information (DCI) for scheduling the sidelink resources needs to indicate both the sidelink control resources and the sidelink data resources to the sidelink transmitter UE.

[0056] When the UE is running in mode 2, it uses a resource selection procedure to automatically select transmission resources for sidelink transmission. If the target UE is a PSUE, the transmitter UE will select resources for control / scheduling command transmission from the control area of ​​the resource pool configured for the PSUE.

[0057] The control area defined for PSUE may be blocked by other types of transport in order to keep resources available for PSUE transport.

[0058] The same principle applies to PSUE control / scheduling command transmissions, defining a control region within the resource pool for such transmissions. All sidelink devices in the resource pool need to monitor this region to ensure reception of PSUE transmissions. The control region may be the same as or different from the control region transmitted to the PSUE.

[0059] The sidelink protocol uses a two-stage SCI (Short-Terminal Interchange Receiver) protocol. The first-stage SCI is transmitted on the physical sidelink control channel (PSCCH), and the second-stage SCI is transmitted on the physical sidelink shared channel (PSSCH), and demodulated using the demodulation reference signal (DMRS) of the shared channel. Since transmission can occur on any sub-channel in the resource pool, the sidelink UE needs to buffer all sub-channels (all PRBs in the frequency domain) across all its receive resource pools to allow for repeated use of the sub-channels for its data scheduling.

[0060] These buffering requirements can be reduced by utilizing cross-timeslot scheduling of sidelink transmissions. In conventional designs, the first-stage SCI provides an implicit indication of the start of shared channel frequency resources. With cross-timeslot scheduling, the first-stage SCI needs to indicate the full-time frequency resources of the shared channel in the relevant time slot. The first-stage SCI is a single sub-channel, but the shared channel can utilize multiple sub-channels. The following describes the method for indicating shared channel resources in the first-stage SCI.

[0061] In the first approach, the size of the first-stage SCI remains unchanged compared to the conventional design. The resource pool is configured with the `sl-MaxNumPerReserve` parameter, which specifies how many resources can be reserved in the future; for example, it might indicate that 2 or 3 resources can be reserved in the future. As shown by `sl-MaxNumPerReserve`, the number of resources specified for cross-slot scheduling can be defined as one less than the resource pool configuration. Therefore, if the resource pool is configured with 2 resources, 1 current resource and 1 future resource, the disclosed method reallocates the bit field of the future resource to indicate cross-slot scheduling of resources.

[0062] Frequency resource allocation The 5-bit time indicator is used to indicate the number of starting and planned subchannels. The 5-bit time indicator is used to indicate the scheduled time period. To make transmissions more meaningful, additional constraints can be imposed so that cross-slot planned transmissions fall within a given range. Similarly, when the resource pool is configured with an sl-MaxNumPerReserve value of 3, two frequency and time resource indicator bits for future resources can be used to indicate a first cross-slot planned resource and a future resource. This method does indeed reduce the number of resources a SCI can reserve to one less than the resource pool configuration. For this method, the "Time Resource Allocation" field can provide the location of future reserved resources.

[0063] In this approach, the first transmission is a control-only transmission without a shared channel, which can provide both a first-stage and a second-stage SCI. The first transmission is limited to the size of a single sub-channel; therefore, the size indicated in the SCI applies only to the reserved resources specified in the SCI. To ensure good reception of this particular control transmission at the PSUE, in one approach, such transmissions can be transmitted within the pre-configured control area discussed above for the PSUE. Thus, the UEs will know in advance that the transmission is for a single sub-channel, and the size indicated by the “Frequency Resource Allocation” field of the SCI applies to the resources reserved in this control command. In another approach, when these control transmissions are not limited to a pre-configured control area, an indication can be provided in the SCI to inform this control / scheduling command to schedule resources across time slots; therefore, the first transmission needs to be understood as limited to the size of a single sub-channel. Furthermore, the size shown in the SCI applies to reserved resources. This indication can be transmitted using reserved bits, indicated by a special second-stage SCI format, or using special values ​​from existing fields.

[0064] In the second approach, existing fields in the first-phase SCI are updated, or new fields are added, to indicate cross-slot scheduling time and frequency resources. This allows the amount of resources reserved by the SCI to remain consistent with the resource pool configuration, despite the use of cross-slot scheduling capabilities.

[0065] The first reserved resource needs to be specified in the SCI frequency section of the cross-slot resource plan. The timeslot for scheduling the first / current resource across timeslots also needs to be indicated in the SCI. This will result in a larger SCI size, but can retain all resources configured in the resource pool. The SCI size can be reduced by performing the first transmission after a known / configured delay following the sidelink control / scheduling message. For example, the resource pool configuration can provide configuration parameters for the timeslot delay between the control / scheduling command and the first data transmission. In this case, the SCI "Time Resource Allocation" field does not need to be updated because the first resource time is known through configuration, and future reserved resources are determined by the "Time Resource Allocation" in the SCI.

[0066] In the current sidelink protocol, control / scheduling commands and related planning data are transmitted within the same resource pool. As described below, this may be modified to allow scheduling data transmission to control / scheduling commands on a shared channel across different resource pools. Therefore, the UE can listen for scheduling / control commands in a specific resource pool (e.g., the control area defined in the aforementioned UE resource pool) and then monitor the indicated resource pool for the data.

[0067] Therefore, the PSUE is configured as the control area for monitoring resource pools to issue scheduling / control commands. These commands instruct on the scheduling of data transmissions, including indicating which resource pool the transmission will take place in. Thus, the first-phase SCI includes an indication of the resource pool for scheduling the shared channel on the relevant side walkway, for example, by adding parameters to the first-phase SCI message. Cross-resource pool scheduling requires all relevant devices to have the same resource pool identity, thus ensuring correct identification of resource pools among devices.

[0068] As described above, in Mode 2, the UE performs autonomous resource selection. The UE listens for transmissions and decodes scheduling / control commands to identify reserved resources, and then selects a transmission resource from those identified as available. However, this listening and decoding process requires significant power consumption. While some proposals have suggested partial sensing or random resource selection to reduce power consumption, these techniques increase the likelihood of collisions and may therefore compromise the overall quality of service.

[0069] To ensure careful selection of transmission resources to avoid collisions while reducing power consumption of the PSUE, a "primary" UE can be designated to select resources on behalf of the PSUE. The primary UE could be a more capable UE, a UE with greater authority over resources, or a platoon leader in a V2X system. The term "primary UE" will be used for convenience, but it is used only to indicate the UE assigned a resource selection role and does not specify any particular requirements beyond the ability to perform defined functions. For example, the primary UE could be the master UE in a master / slave UE pair, a platoon leader in a vehicle queue, a roadside unit (RSU), or any suitable UE capable of providing service. Because the primary UE performs the appropriate sensing procedures before allocating resources to the PSUE, the likelihood of collisions is reduced, and resource utilization reduces the PSUE's power consumption, as the PSUE does not need to perform sensing and selection procedures.

[0070] The master device executes a resource selection procedure and then transmits the selected resource (e.g., in a scheduling command) to the selected PSUE. The aforementioned control area can be used for communication from the master UE to the PSUE; therefore, the PSUE only needs to listen in this area to obtain an indication of the selected resource. The resource indication from the master UE to the PSUE can be executed in any suitable manner, for example, using the aforementioned techniques to execute scheduling commands, such as by reconfiguring bits or modifying SCI messages.

[0071] In the first example of using the master device to select resources, the master device can reserve periodically available resources and transmit a periodic scheduling indication in a pre-configured area (e.g., the control area discussed above), where the scheduling indication includes details of the reserved resources. Therefore, a PSUE wishing to transmit can listen in the pre-configured area and detect and decode the scheduling indication to determine the available resources for the desired transmission. The indicated resources are reserved by the master UE; therefore, the collision risk is the same as if the PSUE had reserved its own resources after the sensing procedure. Reservation is accomplished by a regular scheduling indication in the control area, which all UEs treat as a reservation indication.

[0072] The enhanced features of cross-timeslot scheduling and cross-resource pool scheduling discussed above can improve the efficiency of resource selection for the primary UE, which can be called proxy resource selection.

[0073] If the primary UE periodically reserves resources and indicates their availability, multiple PSUEs may receive instructions to use those resources. A collision occurs if multiple PSUEs choose to transmit on the same resource. This can be mitigated by having each PSUE select resources randomly, but the risk of collisions still exists, especially as the number of UEs increases. To mitigate collisions, the resources reserved by the primary UE can be grouped, and each PSUE is assigned to a group. Each PSUE then selects the resources reserved for its group, so that collisions only occur with other PSUEs in the group. If multiple resources are available for its group, resources can be selected randomly. For example, reserved resources in even-numbered time slots can be grouped and associated with UEs with even-numbered identities, and reserved resources in odd-numbered time slots can be grouped and associated with UEs with odd-numbered identities. Alternatively, resource grouping can be defined for sub-channel numbers associated with a PSUE identification function. Furthermore, resource grouping can be defined for a first reserved resource, a second reserved resource, a third reserved resource, etc., in a given scheduling command.

[0074] In summary, a method is provided in which a first UE reserves resources for other UEs to use for sidelink communication. The first UE transmits those reserved resources for UEs that may wish to use them. UEs that receive the indication and wish to transmit can select appropriate resources from the designated reserved resources and utilize those resources for transmission. The indication of reserved resources may be an SCI message. The other UEs may be PSUEs. The other UEs and reserved resources can be grouped so that each UE selects resources only from its group. Reserved resources may be periodic resources, and the indication of reserved resources can be transmitted periodically. The indication of reserved resources can be transmitted in the control area of ​​the resource pool defined for PSUE control / scheduling commands.

[0075] In another example, the primary UE might reserve resources for another UE (such as a PSUE) for sidelink transmissions, upon request from that UE. The PSUE wishing to transmit sends an indication to the primary UE, which then performs a resource selection procedure to choose appropriate resources for the PSUE. Once resources are selected, the primary UE transmits these resource indications to the PSUE, which can then utilize these resources for transmission. As described above, the indication to the PSUE can be provided within a defined control area of ​​the resource pool.

[0076] To identify a PSUE that intends to utilize resources, the PSUE's identity can be indicated in the first-stage SCI transmitted by the primary UE. For example, a small number of the least important bits in the device identification (ID), such as 2 or 4 (or other numbers), may be included in the first-stage SCI.

[0077] A PSUE's request for resource transmission (scheduling request) can be transmitted in a higher-level radio resource control (RRC) layer for reception by a nearby primary UE. The PSUE may not be aware that the primary UE is within range and can reserve resources for the PSUE; therefore, the PSUE can transmit its request as a broadcast message. The PSUE can use random resource selection to choose the resource for the request message, or it can perform partially sensor-based resource selection. This process should be defined to consume less power than the PSUE selecting its own sidelink resources, otherwise no net power saving will be achieved. Alternatively, resources in a resource pool can be defined as the requested transmissions, from which the PSUE selects resources for the requested transmission. A set of frequency PRBs and time symbols in the sidelink time slots can be defined as part of the resource pool configuration, where the sidelink UE will transmit its scheduling request. The resource pool configuration can also provide the periodicity of timely repetition of the resources. For example, the scheduling request can be transmitted using the PUCCH transmission method from the cellular system. In this way, the scheduling request can be transmitted using a designated area. The configuration of this area is similar to that configured for sidelink feedback. For optimized designs, the same resource area can be used to transmit HARQ feedback and scheduling requests.

[0078] Scheduling requests can use a sequence-based format, selecting time-frequency resources and sequences as functions of UE identity, for example, determined based on known relationships and resource pool configurations. The sequence can provide an indication of the PSUE on the primary UE, which can then associate the identity with selected resources reserved for the PSUE.

[0079] The resources that transmit scheduling requests from the PSUE to the primary UE, as well as the transmission-side walkway feedback, can be a single resource. The allocation of resources can be indicated to the PSUE, or it can be implicitly known how the UE determines the resources for feedback and scheduling requests.

[0080] Once the primary UE reserves resources for use by the PSUE, the primary UE can communicate the reservation to the PSUE in any appropriate manner. As mentioned above, control areas for resource pools can be defined for these indications. Elements of existing control messages can be reconfigured to carry the required indications, or new formats can be defined. Other UEs in the primary UE and PSUE domain may not be able to detect and decode the primary UE's reservation; therefore, these UEs may assume the reserved resources are available, potentially leading to conflicts with the PSUE's transmission of the appropriate reserved resources. To mitigate this situation, in addition to transmitting to the PSUE that reserved the resources, the primary UE can also transmit an indication of its reserved resources. This increases the probability that nearby UEs will decode this indication and understand the resources reserved by the primary UE. The UE will then avoid using such resources, avoiding conflicts by incorporating its reservation status into its resource allocation process.

[0081] The primary UE can transmit reservations in the form of a bitmap, which provides the reservation status of resources through a specified number of sideline walkway slots and subchannels. For example, reserved resources can be displayed over 32 slots (which corresponds to the duration for which reserved resources can be displayed in a normal SCI). Alternatively, the duration can be related to the period for which a reservation indication is transmitted. The reservation indication can be indicated in the resource pool configuration. In variants, it can be explicitly transmitted in the indication.

[0082] Indications in the frequency domain might be based on subchannels, but this can become bloated because the resource pool can have a large number of subchannels. To reduce size, each bit could represent a contiguous set of subchannels, presenting a trade-off between size and granularity. Reserving at least one subchannel in a set will result in the subchannel set being marked as reserved.

[0083] Indications of resources reserved by the primary UE can be transmitted as part of control or data transmission. For example, a standard first-stage SCI can be used, representing a single transmission consisting of a single sub-channel. A second-stage SCI format can then indicate a broadcast transmission. The Physical Side Link Shared Channel (PSSCH) can transmit indications of resources reserved by the primary UE for a given duration. The maximum duration can be part of the system configuration. Alternatively, a maximum duration of 32 sidelink slots can be used. This means that resources reserved within 32 slots can be displayed in the sidelink control information.

[0084] In another example, control transfers can be used without any shared channel data. In this approach, a novel second-stage SCI format can be designed to provide indications of reserved resources. This transfer can also be limited to a single sub-channel to reduce the overhead of such indications.

[0085] Therefore, a resource reservation method is provided for sidelink transmissions from a first UE. The first UE transmits a scheduling request, which is received by a second primary UE. The second UE performs a resource selection procedure and reserves resources for the first UE to use for its sidelink transmissions. The second UE transmits an indication of the reserved resources to the first UE, which can then use these resources for its own transmissions. The scheduling request can be a broadcast message and may be transmitted as an RRC message. The scheduling request may also be a sequence-based signal.

[0086] 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.

[0087] 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.

[0088] 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.

[0089] 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.

[0090] 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.

[0091] 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.

[0092] 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.

[0093] 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.

[0094] 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.

[0095] 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.

[0096] 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.

[0097] 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.

[0098] 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.

[0099] 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.

[0100] 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 method of transmitting a sidelink control signal in a cellular communications network, characterized by, The method comprises the steps of: configuring a power saving control region of transmission resources used by power saving user equipments (UEs), the transmission resources being a resource pool allocated for sidelink transmissions, wherein the power saving control region is different from a control region of the resource pool; selecting, for the power saving UEs, transmission resources from the power saving control region; and transmitting, to the power saving UEs, a sidelink control signal over the selected transmission resources, wherein the power saving control region spans the entire frequency dimension of the first 2 or 3 symbols and is repeated in each slot, the power saving control region occupies the entire sidelink slot in time, if the power saving control region and feedback resources overlap in time, the time overlapping part of the power saving control region, without overlapping in frequency, is used for transmission of control / scheduling commands, the resources reserved for the master UE are grouped, each power saving UE is also assigned to a group, each power saving UE selects the resources reserved for its group, the resource grouping is defined for a subchannel number, the subchannel number is associated with a power saving UE identification function, the resource grouping is defined for a first reserved resource, a second reserved resource, a third reserved resource in a given scheduling command.

2. The method of claim 1, wherein, The power saving control region is defined by time-frequency resources and a period, the period being a repetition of the resource pool in the power saving control region.

3. The method of claim 2, wherein, The frequency resources within the power saving control region are a subset of the total frequency resources available for sidelink transmissions.

4. The method of claim 1, wherein, The transmission resources within the power saving control region overlap in time but not in frequency, wherein the transmission resources are allocated for feedback transmissions.

5. The method of claim 1, wherein, The step of selecting transmission resources comprises: sending a request from the UE to a base station; identifying a target UE as the power saving UE; allocating resources from the power saving control region by the base station; and sending an indication of the allocated transmission resources from the base station to the UE.

6. The method of claim 1, wherein, The step of selecting transmission resources is performed by a UE that is preparing to transmit to the power saving UE.

7. A method of sidelink transmission in a cellular communications network, characterized by, The method comprises the steps of: sending, from a first user equipment (UE) to a second UE, a SCI message, wherein an indication slot indicated by the SCI message is used for data transmission, and the indication slot is different from a slot in which the SCI message is transmitted; and The first UE transmits a data message to the second UE in an indicated slot indicated by the SCI message, wherein the first UE is a master UE, the second UE is a power saving UE, the power saving UE uses power saving control region transmission resources, the power saving control region spans the entire frequency dimension of the first 2 or 3 symbols and is repeated in each slot, the power saving control region occupies the entire time of a sidelink slot, if the power saving control region and feedback resources overlap in time, there is no overlap in frequency, the time overlapping part of the power saving control region is used for transmission of control / scheduling commands, the resources reserved by the master UE are grouped, each power saving UE is also assigned to a group, each power saving UE selects the resources reserved for its group, the resource grouping is defined for a subchannel number, the subchannel number is associated with a power saving UE identification function, the resource grouping is defined for a first reserved resource, a second reserved resource, a third reserved resource in a given scheduling command.

8. The method of claim 7, wherein, The SCI message is a first stage SCI message that includes an implicit indication of a start of frequency resources for the data transmission.

9. The method of claim 7, wherein, The SCI message includes a sidelink control signal.

10. The method of claim 7, wherein, The data transmission uses resources of different resource pools in the SCI message, the SCI message identifies the different resource pools.

11. A method of transmission resource allocation for sidelink transmissions in a cellular network, the method comprising the steps of: reserving, by a first user equipment (UE), transmission resources for other UEs for sidelink communications; transmitting, by the first UE, an indication of the reserved transmission resources for reception by the other UEs; and selecting, by one of the other UEs, transmission resources from among the reserved transmission resources for sidelink communications, wherein the first UE is a master UE, the other UEs are power saving UEs, the power saving UEs use power saving control region transmission resources, the power saving control region spans the entire frequency dimension of the first 2 or 3 symbols and is repeated in each slot, the power saving control region occupies the entire time of a sidelink slot, if the power saving control region and feedback resources overlap in time, there is no overlap in frequency, the time overlapping part of the power saving control region is used for transmission of control / scheduling commands, the resources reserved by the master UE are grouped, each power saving UE is also assigned to a group, each power saving UE selects the resources reserved for its group, the resource grouping is defined for a subchannel number, the subchannel number is associated with a power saving UE identification function, the resource grouping is defined for a first reserved resource, a second reserved resource, a third reserved resource in a given scheduling command.

12. The method of claim 11, wherein, The indication of the reserved transmission resources is an SCI message.

13. The method of claim 11, wherein, The reserved transmission resources include a plurality of resource groups, each resource group is assigned to a group of UEs, and wherein each UE is only allowed to select transmission resources in the corresponding resource group.

14. The method of claim 11, wherein, The reserved transmission resources are periodic transmission resources.

15. The method of claim 11, wherein, The indication of the reserved transmission resources is a periodic transmission.

16. The method of claim 11, wherein, The indication of the reserved transmission resources includes a sidelink control signal.

17. The method of claim 11, wherein, The other UEs randomly select transmission resources from among the assigned reserved transmission resources.

18. The method of claim 11, wherein, The first UE performs the method to transmit resources in response to a request from a UE.

19. The method of claim 18, wherein, The request is an RRC signal.

20. The method of claim 19, wherein, The request uses a sequence-based format in which time-frequency resources and a sequence are selected based on an identity of the requesting UE.

21. The method of claim 11, wherein, The indication of reserved transmission resources includes a bitmap.

22. A method of sidelink transmission in a cellular communications network, characterized by, The method includes the following steps: A first UE sends a scheduling request. A second UE receives the scheduling request and performs resource selection for transmission resources required by the first UE as indicated by the scheduling request. The second UE reserves the selected resources for use by the first UE; and An indication of reserved resources is transmitted from the first UE to the second UE, wherein the first UE is a primary UE, the second UE is a power saving UE, the power saving UE uses a power saving control region transmission resource, the power saving control region spans the entire frequency dimension of the first 2 or 3 symbols and is repeated in each slot, the power saving control region occupies the entire time of a sidelink slot, if the power saving control region and feedback resources overlap in time, there is no overlap in frequency, the time overlap portion of the power saving control region is used to transmit control / scheduling commands, the resources reserved by the primary UE are grouped, each power saving UE is also assigned to a group, each power saving UE selects the resources reserved for its group, the resource grouping is defined for a subchannel number, the subchannel number is associated with a power saving UE identification function, the resource grouping is defined for a first reserved resource, a second reserved resource, a third reserved resource in a given scheduling command.

23. The method of claim 22, wherein, The scheduling request is a broadcast message.

24. The method of claim 22, wherein, The scheduling request is an RRC message.

25. The method of claim 22, wherein, The scheduling request is directed to a UE designated as a primary UE responsible for allocating resources.

26. The method of claim 22, wherein, The scheduling request is a sequence-based signal.

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