CN116326165A

CN116326165A - Reducing power consumption in a direct wireless communication system

Info

Publication number: CN116326165A
Application number: CN202180068610.3A
Authority: CN
Inventors: 维吉尔·加西亚; 欧麦尔·萨利姆
Original assignee: Huizhou TCL Cloud Internet Corp Technology Co Ltd
Current assignee: Huizhou TCL Cloud Internet Corp Technology Co Ltd
Priority date: 2020-10-09
Filing date: 2021-09-29
Publication date: 2023-06-23
Also published as: WO2022073455A1

Abstract

The energy saving resource pool is defined for side-uplink transmission of the energy saving user equipment UE. The power save resource pool defines a subset of time slots that the power save UE can use to transmit or receive. The battery resource pool may be shared between UEs so that only the relevant time slots are used and need to be monitored.

Description

Reducing power consumption in a direct wireless communication system

Technical Field

The present disclosure relates to point-to-point communications in a wireless communication system, and more particularly to power saving procedures in partial sensor-side uplink communications.

Background

Wireless communication systems, such as third generation (3G) mobile telephone standards and technologies, are well known. Such 3G standards and technologies were developed by the third generation partnership project (3 GPP) (RTM). Third generation wireless communications are commonly used to support macrocell mobile telephone communications. Communication systems and networks have evolved to broadband and mobile systems.

In a cellular wireless communication system, user Equipment (UE) is connected to a Radio Access Network (RAN) through a wireless link. The RAN includes a set of base stations that provide radio links to UEs in a cell covered by the base stations, and also provides an interface to a Core Network (CN) for overall network control. Notably, the RAN and CN each perform a respective function related to the overall network. For convenience, the term cellular network is used to refer to a combination of RAN and CN, it being understood that the term is used to refer to the corresponding system for performing the disclosed functions.

The third generation partnership project has developed a so-called Long Term Evolution (LTE) system, i.e. an evolved universal mobile telecommunications system area radio access network (E-UTRAN) for mobile access networks, wherein one or more macro cells are supported by base stations called enodebs or enbs (evolved nodebs). Recently, LTE is further evolving towards 5G or New Radio (NR) systems, where one or more cells are supported by base stations called gnbs. NR recommends the use of Orthogonal Frequency Division Multiplexing (OFDM) physical transport formats.

The NR protocol is intended to provide the option of operating in the unlicensed radio frequency range (referred to as NR-U). While operating in the unlicensed radio frequency band, the gNB and UE must compete with other devices for physical medium/resource access while operating in the unlicensed radio frequency band. For example, wi-Fi (RTM), NR-U, and LAA may use the same physical resources.

The trend in wireless communication is to provide lower latency and higher reliability services. For example, NR is intended to support ultra-reliable and low-latency communications (URLLC), while large-scale machine type communications (mctc) is intended to provide low latency and high reliability for small data packets (typically 32 bytes in size), with a user plane latency of 1ms, reliability of 99.99999%, and a packet loss rate of 10 for the physical layer ^-5 Or 10 ^-6 。

The mctc service aims to support a large number of devices over a long lifecycle through an energy efficient communication channel, where data transmission with each device is occasional and infrequent. For example, one unit may need to support thousands of devices.

The following disclosure relates to various improvements to cellular wireless communication systems.

Disclosure of Invention

The application provides a side link communication method between at least two User Equipments (UEs) in a cellular communication network, which comprises the following steps: defining an energy-saving resource pool used by energy-saving UE; transmitting an indication of transmission resources in the pool of energy-saving resources from a base station to at least two UEs; and using only transmission resources of the energy-saving resource pool when communicating with or transmitting from the energy-saving UE.

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

The energy-efficient resource pool is defined as a subset of time slots within the resource pool.

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

The power save UE monitors only time slots in the power save resource pool prior to transmission.

And the UE utilizing the energy-saving resource pool sends an indication of the resources in the energy-saving resource pool to other UEs.

The energy-saving resource pool is defined by UEs using the resource pool.

The energy-saving resource pool is defined by the base station.

Drawings

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 figures are for ease of illustration and are not necessarily drawn to scale. For ease of understanding, like components are given like reference numerals throughout the various figures.

Fig. 1 is a schematic diagram of selected elements of a cellular communication network.

Fig. 2 depicts a schematic diagram of selected components in a radio area network of the cellular wireless communication network of fig. 1.

Fig. 3-8 depict timing diagrams of time slots detected for evaluating potential resources to be selected.

Detailed Description

Those skilled in the art will recognize and appreciate that the specific details of the examples described are merely illustrative of some embodiments and that the teachings set forth herein are applicable in a variety of alternative settings.

Fig. 1 shows a schematic diagram of three base stations (e.g., enbs or gnbs, depending on the particular cellular standard and terminology) that make up a cellular network. Typically, each base station is deployed by one cellular network operator to provide geographic coverage for UEs in the 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 are interconnected through an X2 interface and connected with a core network through an S1 interface. To illustrate key features of a cellular network, only basic details are shown here. For Side Link (SL) communication between UEs via a PC5 interface. The interface and component names associated with fig. 1 are for example only, and different systems operating on the same principles may use different nomenclature.

Each base station contains hardware and software that implements RAN functionality, including communications with the core network and other base stations, control and data signaling between the core network and UEs, and UEs associated with each base station remain in wireless communication. The core network includes hardware and software that implements network functions such as overall network management and control, and routing of calls and data.

In vehicle-to-vehicle (V2V) applications, the in-vehicle UE may be integrated into vehicles such as automobiles, trucks, and buses. These in-vehicle UEs are able to communicate with each other in an in-coverage mode, which means that the base station can manage and allocate resources to UEs within the base station, and in an out-of-coverage mode, which does not require any base station to manage and allocate resources. In a vehicle networking (V2X) application, a vehicle may communicate not only with other vehicles, but also with infrastructure, pedestrians, cellular networks, and potentially other surrounding devices. Examples of V2X applications include:

vehicle alignment-this enables vehicles to dynamically form an alignment that travels together. The queue all vehicles obtain information from the lead vehicle to manage the queue. This information enables all vehicles to travel together in the same direction in a coordinated manner more closely than normal.

The extension sensor-this enables the exchange of raw or processed data collected by local sensors or real-time video images between vehicles, road field units, pedestrians and V2X application servers. The vehicle can increase the sensing of the environment beyond that which can be sensed by its own sensor and has a wider and comprehensive understanding of the local situation. High data rates are one of the key characteristics.

Advanced driving-semi-automatic or fully automatic driving can be achieved. Each vehicle and/or RSU shares sensed data obtained from its local sensors with nearby vehicles, which allows the vehicles to synchronize and coordinate their trajectories or maneuvers. Each vehicle also shares its driving intent with nearby vehicles.

Remote driving-this enables a remote driver or V2X application to operate a remote vehicle for those passengers who are unable to drive themselves or for vehicles located in a dangerous environment. For situations where the variation is limited and the route is predictable, such as public transportation, cloud computing based driving may be used. High reliability and low latency are the main requirements for this function.

Fig. 2 shows a base station 102 forming a RAN, as well as a UE 150 with a side-link transmitter (i.e., UE-a) and a UE 152 with a side-link receiver (i.e., UE-B) in the RAN. Base station 102 communicates wirelessly with SL Tx UE 150 and SL Rx UE 152 via respective connections 154. The Tx UE 150 and the Rx UE 152 are used to wirelessly communicate with each other via a side uplink 156.

The side-uplink transmission is performed on a dedicated carrier or a shared carrier using TDD (half duplex) with a conventional Uu transmission between the base station and the UE. The resource pool of transmission resources is utilized to manage resources and allocations and to manage interference between potentially concurrent transmissions. The resource pool is a set of time-frequency resources from which transmission resources can be selected. The UE may configure multiple transmit and receive resource pools.

There are two modes of operation for resource allocation for side-link communications, depending on whether the UE is within the coverage of the cellular network. In mode 1, V2X communications are operating within the coverage of a base station (e.g., eNB or gNB). All scheduling and resource allocation can be done by the base station.

Mode 2 is applicable when the side-link service is operating outside the coverage of the cellular base station, at which point the UE needs to schedule itself. For fair utilization, UEs typically use transmission resource allocation based on sensing. In mode 2, the UE selects transmission resources that are desired for transmission and transmits a side-uplink control information (Sidelink Control Information, SCI) message indicating these resources. The receiver of the SCI message (which may be a single UE in unicast, a group of UEs in multicast, or all accessible UEs in broadcast) can learn the transmission details that can be expected through the SCI. The SCI message is control information required to decode the side uplink data content, and is also an indication of reserved resources, the first stage SCI being transmitted in a physical side uplink control channel (Physical sidelink Control Channel, PSCCH) and the second stage SCI being transmitted in a physical side uplink shared channel (Physical sidelink Shared Channel, PSSCH). The UE may reserve transmission resources for Transport Blocks (TBs) for first transmission of data, or may reserve transmission resources for repeated TBs to improve reliability when initial transmission fails.

The 3gpp TR 37.985, v16.0.0 standard document describes the functions required by the LTE and NR standards to support V2X services and to be sufficient to meet the requirements of basic road safety services. Vehicles containing UEs with these functions may use the uplink, downlink and sidelink to exchange information about their own status, such as location, speed and direction of travel, with other vehicles, infrastructure nodes and pedestrians in the vicinity. Side-link communications may improve efficiency, including side-link carrier aggregation, higher order modulation, and reduced delay.

The apparatus, methods, and systems described herein reduce power consumption of devices in a side-uplink autonomous resource selection mode. The set of time slots (sub-) to be sensed has been configured and matches the configuration of the resource pool. The present application is implemented by monitoring the reserved resources of retransmissions and the periodic reserved resources. The apparatus, method and system of the present application also describe performing sensing and configuring sensing functions to match user needs by enabling downward selection to achieve further power reduction.

In particular, the apparatus, methods, and systems described herein focus on power consumption components and improvements made to standard defined partial sensing.

In the LTE standard, to reduce power consumption in order to avoid full sensing of the resource pool by the UE, the UE may have limited or no sensing capability. When the UE is not sensing, the UE only performs random selection, but this presents a collision risk. A trade-off approach, known as "partial sensing", allows a UE to sense a pool of resources for a limited time to search for reserved resources that may affect its selection. The reservation is periodic, with a possible reservation period being a multiple of 100 milliseconds. During operation of the partial sensing for selecting resources, the partially sensed UE may select any resource in the selection window. If n is the resource selection time, the selection window is [ n+T ] ₁ ，n+T ₂ ]. To determine whether resources in the selection window are reserved, the partial sensing UE must sense potential transmission channels of reserved resources that may fall within the selection window.

Fig. 3 shows the time slots that need to be sensed (only 8 1ms sensing time slots are shown for clarity) to determine if the required time slot a is available. In this example, the limited sensing UE would sense all previous (logical) time slots to search for retransmission reservation resources.

Partial sensing is defined and allowed by radio resource control (RRC or higher layer) configuration. If partial sensing is configured by higher layers, the following two steps are used:

Step 1) candidate single subframe resource Rx, y for PSSCH transmission is defined as subframe

A set of LsubCH consecutive subchannels having subchannel x+j, where j=0. The UE determines a set of subframes during the implementation process, the set of subframes being at time interval [ n+t ] ₁ ，n+T ₂ ]Consisting of at least Y subframes, where T ₁ And T ₂ Is selected by the UE according to T ₁ 4 and T _2min (prio _TX )≤T ₂ Not more than 100, T _2min (prio _TX ) Prio can be provided by higher layers _TX This parameter, otherwise 20. Ltoreq.T ₂ Less than or equal to 100. The Y value is set in RRC, n is the time of resource selection, n+T ₁ Is the start of the selection window, n+T ₂ Is the end of the selection window. The UE may select T2 appropriately to meet the delay requirement, and the Y value needs to be equal to or greater than the higher layer parameter minNumCandidate SF. As described in TS 36.213g20, section 14.1.5, the UE sets for any LsubCH consecutive sub-channel groups in the PSSCH resource pool, consecutive sub-channels in the determined sub-frame set corresponding to one candidate sub-frame resource. The total number of candidate single subframe resources is M _total 。

Step 2) if the subframe

Included in the subframe set of step 1, the ue monitors subframe +_provided that the k-th bit of the higher layer parameter gapcandidetesensing is set to 1>

Where t y is the time of the selected resource, pstep is 100ms in LTE. The UE should perform the following actions based on the PSCCH decoded in these subframes and the measured S-RSSI values of the subframes.

In LTE, the period is selected from a list of standardized values. When the partial sensing UE is configured in the resource pool, the set value of the period may be a multiple of 100ms, and the maximum is 1000ms. A set of subsets consisting of multiples of 100ms each can also be configured by the resourcereserverperiod parameter to select the number of cycles allowed in the pool.

For a partially sensed UE, only a partial resource (Y resources) of the selection window needs to be considered. Thus, for a particular resource in the selection window (at time t_y), it is sufficient to check t_y-k Pstep, where pstep=100 ms means that the partial sensing UE checks every 100ms, because of the only possible location of the existing reserved resource that another UE falls down at the required time. Thus, the partial sensing allows the partial sensing UE to evaluate at least Y resources (resources configured in the resource pool) in the selection window.

In particular, partial sensing is configured in absolute time using gapCandidate Sensing parameters. This parameter is a list of 10 boolean values, where the kth value (k=1, …, 10) tells the partial sensing UE whether or not it needs to sense k x 100ms before evaluating the resources.

If only partial period values are allowed, the actual sensing required is reduced, since only these periods can result in reserved resources. But the two lists are independently configured, which leaves sufficient flexibility in terms of periodic configuration and partial sensing, by which configuration depends on trade-offs of three aspects: a possible period; sensing power reduction and collision risk. The collision risk occurs when the partially sensing UE does not need to sense for a time matching the configured time period to reduce its power consumption.

The resource pool may be configured to support periodic reservations, may be configured 1000 milliseconds in advance, and may cause collisions if sensed improperly. When configured to support periodic reservations, the resource pool has a sensing window that starts up to 1100 milliseconds before the resource selection time.

In NR, the possible period in the resource pool (up to 16) can be set to the resource reservation period parameter, but this parameter can be extended to a large extent and allows any integer value between 1ms and 99ms, and multiples of 100ms to 1000 ms. Furthermore, NR introduces several different mechanisms requiring side-link partial sensing. In NR, the allocation of retransmission resources in frequency and time is completely flexible, so that up to 32 logical slots can be reserved (one or two) for retransmission in advance. Reusing the LTE part sensing mechanism of the prior art to sense NR would require a long bit string (bitstring) to point to all possible instants in the 1100ms window.

The apparatus, methods and systems described herein provide efficient signaling and configuration that enables a UE to perform partial sensing and to acquire possible reserved resources from both for retransmissions and periodically reserved resources according to the time periods defined in the NR and retransmission allocations.

In the resource pool, the partial sensing UEs may be configured or preconfigured to perform sensing of time slots indicating retransmission resources that may collide with potential resources selected by the partial sensing UEs for their own use.

In NR, SCI can reserve up to 32 logical slots in advance (in LTE, up to 16 logical slots are reserved). To ensure that no persistent retransmission reservations are made for the resources selected for evaluation, the partial sensing UE performs sensing for all logical time slots preceding the selected time slot, which is within the retransmission time resource indication range.

Listening for a complete sensing window of 100ms (1100 ms for aperiodic resource pools; for resource pools that are allowed to be reserved periodically) can be avoided by listening for only 16 or 32 slots, thereby reducing power consumption.

To limit the cost of sensing 16 or 32 time slots before selecting the required resources, the partial sensing UE may set up to sense only part of the available time slots in a (pre) configured mode. The pattern may be preset by a (pre) configured indexed signal or a Bitmap (Bitmap) may be used to indicate logical time slots to be sensed.

Fig. 4 shows the time slots that need to be sensed to determine if the required time slot a is available. In this example, the partial sensing UE senses only 4 out of 8 (logical) slots before its selected resource search retransmission reservation.

Fig. 5 shows a missed retransmission reservation (SCI), which results in the collision of the required slots a. Limiting sensing, while saving battery power, may conflict with retransmission reservations if reserved to non-sensed time slots. Thus requiring a trade-off to be set by configuration according to its traffic and the functions configured for each resource pool.

The selection of resources for retransmission in the resource pool of the partially sensed UE may be configured such that the retransmission resources match the limited sensing time pattern. This limits the flexibility of resource allocation but allows partial sensing users to listen to all conflicting retransmission resources that may affect their resource selection.

For this purpose, if the resource selection of the transmission and its retransmission are completed immediately in step 2 of the NR side row resource allocation pattern 2, it is checked whether the selected candidate is suitable for the configured time pattern. The time pattern must be reversed, e.g. a limited sensing UE will sense 5 slots before evaluating the resource, meaning that the resource is reserved for retransmission 5 slots ahead in time. If the resources are independently selected for transmission and retransmission, the devices, systems, and methods described herein may remove any resources in the time slot that are not intercepted by the partially sensing UE from the candidate set of resources in step 1.

Limited sensing may use the configuration flags of the resource pool to enable/disable. This functionality may affect resource selection flexibility and device power consumption, and may therefore be enabled when there is limited sensing of UE presence or expected presence in the resource pool.

This approach may be applicable to resource pools for blind transfer transmissions, which always use reserved retransmission resources. A pool of retransmission resources based on HARQ feedback may also benefit from this approach.

The partial sensing UEs may exchange functionality between UEs and/or with the network, the partial sensing UE functionality may define what sensing method and/or how many sensing amounts the partial sensing UE may perform, e.g., the partial sensing UE may define to sense per evaluation resource or per time unit. When exchanging this information, the resource pool may be configured appropriately, for example by determining which set of resources to listen to and whether to manage the functionality and expectations of the respective partial sensing UEs.

The method described herein works without distinguishing whether the resource pool is configured as only aperiodic resources or periodic reservations, and is therefore able to capture retransmissions of both reserved resources.

Even if the resource pool configuration enables these sensing methods, these limited sensing methods can be applied to partially sensed UEs with limited sensing capabilities, not necessarily to all UEs of the resource pool. This configuration may affect other portions of the sensing UE that are not configured by the systems and methods described herein by limiting its resource selection, etc.

The partial sensing UE may configure to perform sensing on a set of limited time slots in the resource pool, including with a configured possible reservation periodAll time slots that coincide. These reservation periods may conflict with the assessed resources. Therefore, the function of partial sensing will monitor the corresponding time t _y-j*Pi In which the period value P _i Is configured in the resourceReserve PeriodList parameter, and j satisfies P _i *j≤SensingWindow。

The partial sensing UE may configure to perform sensing on a set of limited time slots in the resource pool, including the last N time slots consistent with the configured possible reservation periods that may conflict with the assessed resources. N can be (pre) configured for each configured period. Fig. 6 shows an example in which periods of 20ms and 50ms are configured in the resource pool. The partial sensing UE evaluates the time slot marked as evaluation resource a by listening to the time slot every 20ms and every 50ms without sensing or listening to other time slots. More specifically, sensing is performed on the exact time slots when periodic collisions may occur, the exact listening duration being limited to the first phase of listening to the PSCCH where SCI needs to be decoded, and the second phase of listening to the SCI for these particular time slots on the PSCCH to determine if it is intended to receive data.

Therefore, the function of partial sensing will monitor the corresponding time t _y-j*Pi In which the period value P _i Is configured in the resourceReservePeriodList parameter, and j satisfies j.ltoreq.N.

In order to reduce the sensing time and power consumption, when n=1, only the slot corresponding to the last time of the time difference equal to the possible period of the configuration is sensed. In fig. 7, only one slot is sensed per configured period; before evaluating resource a, one slot is sensed every 50 milliseconds and one slot is sensed every 20 milliseconds. If the slot corresponding to the instant of the potential periodic reservation collision is not a SL slot, the partial sensing UE will sense that the instant corresponding to the last SL slot instant corresponds to a configuration period.

When any part of the periodic reservation is performed sensing that the UE has no data to transmit, it will not transmit on the reserved resources at all. Therefore, only partially sensing UEs that sense the last time (n=1) cannot guarantee a determination of whether resources are reserved regularly at that time. Therefore, in order to improve reliability, N >1 may be set.

To reduce the sensing time, a limited sensing UE may also be configured to sense only time slots corresponding to a set of possible periods. While having the benefit of power saving, this may create a conflict. The sensing period may be set to the reduced SensingPeriodList parameter for configuration and signaling, and may be represented using a bitmap of the same length as the list of possible periods.

Optionally, the apparatus, method and system may set minimum and/or maximum period values for the sensing period. These limited sensing periods may be configured to match the partial sensing UE functions signaled through the resource pool. The partial sensing UE may configure to perform sensing on a set of limited time slots in the resource pool, including all time slots coinciding with the configured possible reservation period. These reservation periods may conflict with the assessed resources. Therefore, the function of partial sensing will monitor the corresponding time t _y-j*Pi In which the period value P _i Is configured in the resourceReserve PeriodList parameter, and j satisfies P _i * j is less than or equal to SensingWindow (or is less than or equal to N).

The partial sensing UE may be configured to perform the partial sensing method described in the present application within a limited sensing window.

In NR, the window for periodically enabling resource pools is 1100 milliseconds long, as opposed to many small-period reservations. Thus, reserving the resource pool allows the limited sensing UE to reduce its sensing window to a minimum size, e.g., 100ms. The exact value of window sensing may remain to be achieved, but may limit the configured minimum. UEs with limited sensing functionality may share their user limited sensing functionality, including the maximum sensing window size possible.

The apparatus, methods, and systems described herein may be configured to activate/deactivate using a dedicated flag or by the presence or absence of a desired configuration parameter. Such configuration changes may be triggered by limited sensing of the presence of the UE and its functionality.

Typically, the side-uplink resource pool will allow for multiple transmissions of periodically reserved resources and multiple repeated aperiodic transmissions to be reserved in a single SCI, where the periodically reserved transmissions may also include retransmissions. Furthermore, periodic transmissions may require the use of a one-time transmission, e.g., in case of a received HARQ NACK, retransmissions may be performed within the packet delay budget. A power-limited UE needs to apply the policy combinations described herein to minimize its sensing requirements.

Thus, the partial sensing UE will listen to a set of resources before it selects a window (evaluates resource a) to sense any retransmission reserved resources that may collide with candidate resources, and then the partial sensing UE will sense the corresponding time slots from outside the retransmission reserved resources according to the periodicity value set by the periodicity configuration as part of the resource pool configuration.

The resource pool configuration may indicate the boundary of the two intervals of partial sensing with an appropriate field. A portion of the sensing boundary may be associated with a priority of transmission. As a simple example, the resource pool configuration may define a priority threshold, and if the power-limited UE is transmitting packets with priority above the priority threshold, a sensing indicating a boundary, e.g. periodic and aperiodic partial sensing, may be performed first, with a duration limit of 100ms. If the priority of the data packets is equal to or below the priority threshold, then the UEs will perform partial sensing for a longer duration, either across the entire sensing window or indicated by configuring the explicit duration as part of the resource pool configuration.

The partial sensing approach described herein may further reduce power consumption due to monitoring radio resources, and a UE with limited sensing capability may be configured to stop or suspend its monitoring of a set of slots/sub-channels corresponding to potential reservation notifications of reserved resources.

In fig. 8, SCI is used to monitor the reserved slots that are partially sensed by the UE as possibly conflicting. The SCI will reserve for another UE the resources overlapping with the evaluation resource a. When one of the Y resources is selected as a new evaluation resource from the list of Y resources, the sensing of future conflicting reservations will cease and be set as unavailable.

Optionally, the partial sensing UE may sense the last time of the reservation collision to verify whether the periodic resources are still using the periodic resources. Note that if the limited sensing UE is considering multiple divided resources (different sub-channels) in the same slot and only a portion of that slot is reserved, the limited sensing UE may still monitor the remaining slots to check if further collision with non-conflicting resources occurs. This would still require a partially sensed UE to activate its radio reception, but it may reduce decoding and processing of PSCCH regions, which may still lead to further collisions.

Such interrupt sensing is applicable to both periodic reserved portion sensing and retransmission portion sensing. In the case of periodic reservation partial sensing, the same sub-channels as the selected resources are used at the time of the potential collision and can be easily identified and deleted from the sensing. In the case of retransmission partial sensing, the retransmission resources have sufficient flexibility in the time and frequency domains, so in order to interrupt sensing at time slots with potential collisions, all candidate resources of the selected time slot have to be reserved to cancel the monitoring of the corresponding time slot.

The following are various techniques related to the power consumption of side link communication, particularly by scheduling resources to reduce power consumption during sensing and transmission operations. As described below, power save UEs (power saving user equipment, PSUE-defined as UEs using partial sensing, etc. power save techniques) share information about monitoring and transmission slots to assist other UEs in scheduling their transmissions. Other UEs may use the slots indicated as monitored to transmit data or configuration/radio resource control (radio resource control, RRC) information to the PSUE, reservation information related to the PSUE (PSUE may not be the destination of the reservation, but the reservation may affect which resources the UE selects for transmission), or scheduling information the UE needs to know. Likewise, other UEs may use non-monitored slots for PSUE independent transmissions in preference to monitored slots.

As described above, the PSUE may be configured in a partial sensing mode to monitor only a subset of transmission slots/resources prior to selecting transmission resources. It is assumed that the monitored resources relate to the resources available for transmission, and therefore, for the time slots containing potential transmission resources, the ps ue monitors a set of (pre) defined previous time slots. The time slots are monitored to detect a periodic reservation or a forward reservation. In monitoring the PSUE, the potential reservation of the entire slot must be heard and an attempt must be made to decode the SCI in all possible PSCCHs of each monitored slot. It is then already in listening mode and the entire time slot has radio reception hardware and decoding functions. The PSUE may be configured to be able to receive data in the monitored slots, it should also decode the 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 that the receiver can receive data during a single "on" period, rather than just being on for receiving scheduling information. In NR, the reservation mechanism of retransmission allows for reservation of any time-frequency resource in a given future window (32 slots). Since the frequency of the resources can be changed (and noted in reserved SCIs), when the UE wants to monitor potential reservations conflicting with candidate resources, it must decode all possible frequency locations of SCIs in the monitoring slot. For periodic reservation and monitoring, the periodic reservation will automatically reserve the same frequency resources as the transmission in the future. However, since the size of the resources may vary, the PSCCH locations should still be monitored by the ps ue for most possible PSCCH locations to cope with potential collisions.

For example, the PSUE may be (pre) configured as a side link receiver and the time slots are partially monitored according to the configuration. The PSUE may select the time slots to monitor according to a configuration defined for the UE or according to configured candidate transmission time slots and a sensing pattern. The PSUE communicates information about the monitored time slots, either explicitly or implicitly, to other UEs. The UE transmitting to the PSUE uses the shared information as input for transmission slot selection.

The time slots to be monitored by the PSUE are defined in a deterministic manner. For example, time slots may be (pre) defined for the PSUE and shared between related devices, or the PSUE's transmission time slots may be (pre) defined and shared so that monitored time slots may be deduced from their relation to transmission time slots.

In the first method, the PSUE defines a set of monitored time slots and transmits information about those time slots to other UEs. The monitoring time slot may be selected from a pool of receive resources configured for the PSUE. Information about the set may be shared with other UEs using an appropriate format, such as a bit string or equivalent pattern. The PSUE may use PSSCH "Medium Access control (media access control, MAC) level" scheduling information. The PSSCH data may be transmitted to the relevant UEs as unicast or multicast, or may be transmitted to all UEs having a reception range as broadcast. The monitoring sequence length and periodicity may be (pre) configured for the PSUE or related resource pool. This approach is expected to be straightforward to implement, but would incur overhead in transmitting the monitored-period information periodically.

The monitoring resource set may be defined as a power save resource pool (power saving resource pool, PSRP) of the plurality of PSUEs. In one example, it is a (sparse) pool of reception resources. Such a resource pool may be defined with parameters, intended to achieve power saving behaviour by multiple PSUEs. The PSUE may be configured to monitor all slots in the PSRP as a normal UE does in its allocated resource pool. The slot structure of the PSRP defines the monitoring range of the PSUE. PSRP may be configured to be relatively sparse in time period allocation to avoid PSUEs being active on too many slots, thereby increasing power consumption. A dedicated slot selection format or predefined sequence may be defined to provide a sparse slot structure for the PSRP.

When the PSRP is configured, other UEs transmitting to the PSUE configured with the PSRP transmit to the PSUE using the PSRP resource.

To avoid limiting the access of UEs without power saving requirements to the transmission resources, other UEs may be configured with a pool of resources overlapping with the PSRP. This resource pool and PSRP should have a structure and configuration (e.g., subchannel size, SCI format, physical sidelink feedback channel (physical sidelink shared channel, PSFCH) design …) similar to that of the port physical layer (port physical layer, PHY).

The UE may configure multiple resource pools, one of which is active at any time. Some of the resource pools configured for the UE may be PSRP, and these resource pools may be implicitly represented by their characteristics (e.g., sensing patterns), or explicitly using indicators, etc.

It should be appreciated that to avoid misunderstanding in terms of time and reservation, the UE needs to switch logical slots used with the regular resource pool and PSRP to know when reservation and transmission actually occur. This may be done if the UE knows the different resource pools that are active each time.

In a particular example, the PSRP may be defined as a subset of the resource pool. The PSRP may be defined as a sub-resource pool in the resource pool that is only used by the PSUE receiver. A subset of the time slots is transmitted by a (pre) configuration and which resource slots are included in the PSRP may be selected based on a series of binary logical time slots. The configuration of the PSRP is similar to its associated primary resource pool, but only a subset of the time slots. This avoids configuration compatibility issues and saves configuration overhead or logic time issues. A UE communicating with a PSUE shall perform its transmission using a PSRP subset. UEs communicating with non-PSUEs should preferentially use resources not in the PSRP subset to perform their communications, keeping the PSRP resources free.

By sharing PSRP (pre) configuration information with other UEs, other UEs may be informed of which slots the PSUE is monitoring. The (pre) configuration information may be shared as RRC parameters or preconfigured as UEs. Thus, each UE is aware of the reception capabilities of the other UEs during the connection configuration, providing a stable, non-dynamic modification, which is preferred because the monitoring period may be long, and thus a stable configuration is preferred.

As mentioned above, the monitoring time slots may also be defined according to a deterministic definition of the transmission time slots. The transmission slots of the PSUE may be defined early enough (selected by the PSUE, or by configuration) so that the corresponding monitoring slots are known and may be shared with other UEs for use.

The transmission time slot may be defined as:

dedicated transport resource pools. The transmission pool of the PSUE may be set sufficiently sparse (to ensure limited sensing and processing) and to accommodate good behavior of the monitoring patterns (e.g., by using time slots whose monitoring patterns coincide with each other).

A subset of the regular transport pools. A set of binary time slots matching the configured transmission pool may be applied to select down the time slots of the transmission pool, which would be possible transmission slots of the PSUE.

In the conventional transmission resource pool, the PSUE additionally uses a dynamically defined transmission opportunity of the PSUE.

The partial sensing performed by the psu corresponds to (pre) defined patterns that the psu has monitored in the past in order to check reservations that will coincide with the transmission resources it expects to use. These modes may check for retransmission reservations (using logical time slots) and/or periodic reservations (absolute time). The mode to be used may be predefined, reused from other systems (e.g. LTE), or configured specifically for NR side link communication. Using the pattern and the (pre) defined transmission slots, the PSUE can derive the slots to be monitored before these transmission slots.

The PSUE may be configured to transmit its transmission slots to other UEs. Other UEs may combine this information with the (pre) configured partial sensing pattern to derive the time slots that the ps UE will monitor. If the transmission slots are defined as dedicated resource pools or sub-resource pools, the configuration of these pools may be shared between UEs (as RRC information). If multiple transmission resource pools are configured, the PSUE may exchange references (e.g., indexes) of active transmission resource pools used with other UEs.

If a transmission slot is defined directly by a PSUE, it must transmit its intended transmission slot to other UEs in advance. This may be done dynamically, using the PSSCH to transmit information. The transmission may be made periodically (e.g., using periodic transmissions) to update other UEs, or to update other UEs as needed, whenever configuration updates or new settings are available. This transmission may be unicast/multicast (for a single user/group connected to the PSUE) or broadcast (informing all UEs within reception range).

The UE receives a reservation for the ps UE in the future, assuming that the corresponding slot is the transmission opportunity for the ps UE. When the PSUE sends a future resource reservation, this means that the PSUE will transmit in the slot. This may be for playback or periodic reservation. When UEs monitor and receive such reservations of the psu, they can assume that the reserved slots are in the psu's transmission slots, and thus derive the expected monitoring slots from these reservations and partial sensing patterns. The UE may also use the reservation history of the ps UE and locally compiled statistics to infer the ps UE's usual transmission slots and assume that they are also ps UE future transmission slots.

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 (quality of service, qoS). If based on the TX resource pool, the ps ue may adjust the TX resource pool used according to its traffic demand. Based on its sustained or expected traffic, the PSUE may determine its need for transmission slots or transmission slot opportunities. The transmission slot candidates should reflect that each potential transmission will take into account a resource selection window comprising several resource candidates (at least Y in LTE release). For example, traffic with deterministic arrival times of data packets may predict its transmission needs. A change in traffic demand may trigger a change in transmission configuration (e.g., a transmission mode or a pool of transmission resources used) and this change should be reported to other UEs.

The following is an example of a communication procedure for communicating with a PSUE that applies the principles described above to define and share its monitoring and transmission slots.

The conventional NR mode 2 resource selection procedure uses two principle steps. Firstly, available/candidate resources are determined, and secondly, resources for transmission are selected, from among the candidate resources.

In a first example using shared information, the UE may define candidate slots for transmission as slots monitored by the PSUE when selecting resources. As step 1 of the resource selection identification phase, the transmitting UE will check all candidate resources in a set of time slots, which may correspond to the pool of transmission resources of the UE belonging to the resource selection window. In particular in the conventional procedure:

the symbols: (t) _0SL ，t _1SL ，t _2SL ,..) represents a set of timeslots that may belong to a side link resource pool and is defined in clause 8.

1) Candidate single-slot resource R for transmission _x,y Defined as a group L _subCH Continuous sonChannel, subchannel x+j in slot tyrl, where j=0,.. _subCH-1 . The UE shall assume that at time interval [ n+t1, +t2 ]]Any one set of L contained in a corresponding resource pool _subCH The consecutive subchannels correspond to one candidate single-slot resource, wherein:

select T ₁ T is 0.ltoreq.T ₁ ≤T _proc,1SL Lower implementation in which time slot T _proc,1SL Defined in Table 8.1.4-2, wherein μ _SL Is a subcarrier spacing (subcarrier spacing, SCS) configuration of a side uplink bandwidth part (sidelink bandwidth part, SL BWP);

if T _2min Shorter than the remaining packet delay budget (in the slot), then T ₂ Depending on UE implementation, but T _2min ≤T ₂ A residual packet budget (in time slots); otherwise T ₂ Set to the remaining packet delay budget (in the slot).

M is used for total number of candidate single time slot resources _total And (3) representing.

The first part of this procedure is modified so that the identified output of step 1 corresponds to the resource selection window, the set of time slots of the transmission resource pool, and the resources in the monitored time slots of the PSUE.

This may be accomplished by:

the MAC selects down the time slot used as the process input (instant slot t _0SL ，t _1SL ，t _2SL ,..); this means that the scheduling between the ps UE monitoring slot and the UE transmitting to it can be kept at the MAC level.

Or PHY downstream selection by reserving the original set of time slots, but in step 1 by modifying the included time slots or j=0,.. _subCH Is to perform downstream selection to monitor only the time slots. This requires the PSUE to exchange information of the monitoring slots from the MAC to the PHY layer (assuming it was originally known by the MAC).

In this example, candidate resource M _total Only candidate transmission slots for UE transmission and ps UE reception are included. However, according to the usual procedure, the set of equipment is still subject to further exclusion and downward selection. .

In a second example, the step of excluding the identified candidate resources may be modified to delete resources in the time slots that the PSUE is not monitoring. In a conventional resource identification procedure, if a resource meets certain conditions, the resource is excluded:

5) The UE shall select any candidate one-slot resource R if all the following conditions are met _x,y Excluded from the set S _A In (a): the UE does not monitor slot t of step 2 _mSL 。

For higher layer parameters sl-resourceReserve PeriodList and at time slot t _mSL The "resource reservation period" field of any periodicity value allowed by hypothetical SCI format 1-a, set to the periodicity value, and indicating all sub-channels of the resource pool in this slot will meet condition c in step 6.

6) The UE shall select any candidate one-slot resource R if all the following conditions are met _x,y Excluded from the set S _A In (a):

a) UE in time slot t _mSL If a "resource reservation period" field exists, and a "priority" field in the received SCI format 1-A, according to European Telecommunications standards institute (European telecommunications standards institute, ETSI) [6, TS 38.213, respectively ]The 16.4 th bar of (3) represents the value P _{rsvp_RX} And prio _RX ；

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

c) At time slot t _mSL Or received SCI formats in the same SCI format, if and only if the "resource reservation period" field is present in the received SCI format 1-a, it is assumed that at time slot t _{m+q×Prsvp_RX′SL} In determining a set of resource blocks and slots according to clause 8.1.5, where, with R _{x，+j×Prsvp_TX′} Overlap, q=1, 2, … Q, j=0, 1, …, C _resel -1. Here, P _{rsvp_RX′} Is P _{rsvp_RX} According to 8.1.7, if P _{rsvp_RX} <T _scal And n' -m.ltoreq.P _{rsvp_RX′} Wherein q= [ T _scal P _{rsvp_RX} ]Time slot t _n’SL =n, e.gFruit n belongs to the collection (t) _0SL,1SL ,…,t _TmaxSL ...), otherwise, time slot t _n’SL Is in the first slot of slot n, otherwise q=1, n belongs to the set (t _0SL,1SL ,…,t _TmaxSL ...)。T _scal Set to select window size T ₂ Converted into units of ms.

In this example, the excluding step is modified to add exclusion of resources not monitored by the PSUE. In this example, the MAC should inform the PHY which slots to monitor by the target PSUE (assuming the MAC initially retains information). From the perspective of the transmitter, candidate resource M _total Including all resources that were initially candidate, while the number of candidate resources available after exclusion takes into account both transmitter, sensing and PSUE limitations.

When step 7 above (3 GPP TS 38.214 section 8.1.4: check if the output contains at least X. Candidate resource M _total ) Is performed, the first option is more likely to meet the X requirement because of the candidate resource M _total Only the resources monitored by the PSUE are included, and therefore it is unlikely that the RSRP power threshold will be raised to include more resources, providing some more interfering resources for the MAC layer. However, the first option gives a smaller amount of resources than the second option

In a third example, the resource selection may be modified to delete candidate resources belonging to non-monitoring time slots. Rather than excluding resources in the PHY layer that are not monitored by the PSUE, they are done in the MAC layer after the resource identification is complete. Using a conventional resource identification procedure, but after reporting the set of available resources, the MAC layer excludes non-monitoring resources before selecting the actual transmission resources.

Note that since the PHY layer does not delete the unmonitored slots, few or no given resources may be appropriate. In this case, the MAC layer may delete the transmission or perform reselection, given a more appropriate set of time slots to choose from (i.e., similar to the first choice).

The parameter X and RSRP threshold may be configured separately from the threshold of the normal user when the UE is ready to transmit resources to the PSUE. This results in receiving additional RRC configuration of Resource Pool (RP) of the ps ue. Example(s) For example, X may be set to a higher value to ensure that more candidate users (particularly in candidate resource M) may be further reduced in selection _total Including the case of resources that the PSUE may not monitor).

In current LTE, a power limited user "pedestrian UE" may be configured to perform only transmissions, particularly if the user is transmitting during a user location/Identity (ID). In this case, the UE does not need to perform any sensing before transmission, which may lead to collision. The power limited user may also be configured to perform partial sensing in order to be able to receive some data or perform more reliable resource selection (avoid collisions).

In the embodiments of the present application, the PSUE (pre-) is configured to enable or disable reception of side link transmissions. This (pre) configuration follows the UE function, which specifies that this ps UE is able to limit the power reception of side link data. Since the target ID is specified by the side link information in the second stage SCI and the reservation mode/periodicity is in the first stage SCI, the following is observed:

when not configured as "reception capability", the PSUE performing some sensing (e.g. partial or full sensing) only needs to decode the first stage SCI, i.e. PSCCH, to obtain information of the resource reservation.

When configured as "reception capability", the PSUE should perceive and decode the first stage and second stage SCIs, and the data payload when the PSUE is the transmission destination.

For a PSUE with a receiving function, it may be configured to listen to the first stage and second stage SCIs only in time slots configured for monitoring; but may only listen to none of the first stage SCI or other time slots (e.g., time slot splitting may be based on configured RP and PSRP).

When the PSUE is configured as a "receiver", it senses periodically as long as the PSUE has data to transmit when monitoring the time slot selected based on the TX. If the PSUE has no data to transmit, it should still monitor the other UE-known patterns to accept some RX. The PSUE may be (temporarily) configured as a limited receiver/may use a specifically defined regular partial sensing mode/sub-mode.

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

In summary, various side link communication methods are provided between UEs. The UE may be configured to monitor only a subset of the time slots and may communicate information of these time slots to other UEs either explicitly or implicitly. The UE may communicate transmission time slots from which the monitored time slots may be identified. UEs communicating with UEs assigned their monitoring slots can only transmit to said UEs in these monitoring slots. In selecting side link transmission resources, particularly in mode 2, the UE should select based at least in part on the indication of the monitored time slot.

Although not shown in detail, any of the devices forming part of the network may comprise at least a processor, a storage unit and a communication interface, wherein the processor, the storage unit and the communication interface are configured to perform the methods of any aspect of the invention. Further options and selections are described below.

The signal processing functions of embodiments of the present invention, particularly the gNB and the UE, may be achieved using computer systems or architectures known to those skilled in the relevant art. The computer system may be a desktop, laptop or notebook computer, handheld computing device (PDA, cell phone, palmtop, etc.), server, client, or any other type of general purpose computing device that may be used as desired for a given application or environment. The computer system may include one or more processors, which may be implemented using a general-purpose or special-purpose processing engine, such as a microprocessor, microcontroller, or other control module.

The computer system may also include a main memory, such as a Random Access Memory (RAM) or other dynamic memory, for storing information and instructions that may be executed by the processor. The main memory may also be used for storing temporary variables or other intermediate information during execution of instructions to be executed by the processor. The computer system may also include a Read Only Memory (ROM) or other static storage device for storing static information and instructions for the processor.

The computer system may also include an information storage system, which may include a media drive and a removable storage interface. The media drive may include a drive or other mechanism to secure or support a removable storage medium, such as a hard disk drive, a floppy disk drive, a magnetic tape drive, an optical disk drive, a Compact Disk (CD) or Digital Video Drive (DVD) (RTM) read or write drive (including a writeable or erasable drive), or other removable or fixed media drive. Storage media may include, for example, hard disk, floppy disk, magnetic tape, optical disk, CD or DVD, or other fixed or removable medium that is read by and written to by a media drive. The storage medium may include a computer-readable storage medium having stored therein specific computer software or data.

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 cartridge and cartridge interfaces, removable memory (e.g., flash memory or other removable memory modules) and memory slots, and other removable storage units and interfaces that allow software and data to be transferred from the removable storage units to the computer system.

The computer system may also include a communication interface. Such a communication interface may be used to allow software and data to be transferred between a computer system and an external device. Examples of communication interfaces may include modems, network interfaces (e.g., ethernet or other NIC cards), communication ports (e.g., universal Serial Bus (USB) ports), PCMCIA slots and cards, etc. Software and data transferred via the communications interface are in the form of signals which may be electronic, electromagnetic and optical or other signals capable of being received by the communications interface medium.

In this document, the terms "computer program product," "computer-readable medium," and the like may be used to generally 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 often referred to as "computer program code" (which may be grouped in the form of computer programs or other groupings). When executed, the computer system is capable of performing the functions of embodiments of the present invention. Note that the code may directly cause the processor to perform the specified operations, be compiled to do so, and/or be combined with other software, hardware, and/or firmware elements (e.g., libraries for performing standard functions) to do so.

The non-transitory computer readable medium may include at least one of: hard disks, CD-ROMs, optical storage devices, magnetic storage devices, read-only memory, programmable read-only memory, erasable programmable read-only memory, EPROM, electrically erasable programmable read-only memory, and flash memory. In embodiments where the components are implemented using software, 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 a computer system causes the processor to perform the functions of the invention as described herein.

Furthermore, the inventive concept may be applied to any circuit for performing signal processing functions within a network component. It is further contemplated that, for example, a semiconductor manufacturer may employ the inventive concepts in the design of a stand-alone device, such as a microcontroller of a Digital Signal Processor (DSP), or an Application Specific Integrated Circuit (ASIC) and/or any other subsystem element.

For clarity, the above description describes embodiments of the invention with reference to a single processing logic. However, the inventive concept may equally be implemented by a number of different functional units and processors to provide signal processing functionality. Thus, references to specific functional units are only to be seen as references to suitable means for providing the described functionality rather than indicative of a strict logical or physical structure or organization.

Aspects of the invention may be implemented in any suitable form including hardware, software, firmware or any combination of these. The invention may 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.

Thus, the components and assemblies of embodiments of the invention can be physically, functionally and logically implemented in any suitable way. Indeed the functionality may be implemented in a single unit, in a plurality of units or as part of other functional units. Although the present invention has been described in connection with some embodiments, it is not intended to be limited to the specific form set forth herein. Rather, the scope of the invention is limited only by the appended claims. Furthermore, although features appear to be described in connection with particular embodiments, those skilled in the art will recognize that various features of the described embodiments can be combined in accordance with the invention. In the claims, the term "comprising" does not exclude the presence of other elements or steps.

Furthermore, although individually listed, a plurality of means, elements or method steps may be implemented by e.g. a single unit or processor. Furthermore, although individual features may be included in different claims, these may possibly be advantageously combined, and the inclusion in different claims does not imply that a combination of features is not feasible and/or advantageous. Furthermore, the inclusion of a feature in one claim category does not imply a limitation to this category but rather indicates that the feature is equally applicable to other claim categories as appropriate.

Furthermore, the order of features in the claims does not imply any specific order in which the features must be worked and in particular the order of individual steps in a method claim does not imply that the steps must be performed in this order. Rather, the steps may be performed in any suitable order. Furthermore, singular references do not exclude a plurality. Thus, references to "a," "an," "the first," "the second," etc. do not exclude a plurality.

Although the present invention has been described in connection with some embodiments, it is not intended to be limited to the specific form set forth herein. Rather, the scope of the invention is limited only by the appended claims. Furthermore, although features appear to be described in connection with particular embodiments, those skilled in the art will recognize that various features of the described embodiments can be combined in accordance with the invention. In the claims, the term "comprising" or "comprises" does not exclude the presence of other elements.

Claims

1. A method of side link communication between at least two user equipments, UEs, in a cellular communication network, the method comprising:

defining an energy-saving resource pool used by energy-saving UE;

transmitting an indication of transmission resources in the pool of energy-saving resources from a base station to at least two UEs; and

When communicating with or transmitting from the power saving UE, only the transmission resources of the power saving resource pool are used.

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 2, wherein the energy-efficient resource pool is defined as a subset of time slots within the resource pool.

4. A method according to any of claims 1-3, characterized in that the indication of transmission resources in the pool of energy-saving resources is sent using RRC signaling.

5. The method of any of claims 1-4, wherein the power saving UE monitors only time slots in the power saving resource pool prior to transmission.

6. The method according to any of claims 1-5, wherein a UE utilizing the pool of energy-saving resources sends an indication of resources in the pool of energy-saving resources to other UEs.

7. The method according to any of claims 1-6, characterized in that the energy saving resource pool is defined by UEs utilizing the resource pool.

8. The method according to any of claims 1-7, wherein the pool of energy-saving resources is defined by the base station.