CN113273121B

CN113273121B - Method, apparatus and computer readable medium for measuring sidelink received signal strength

Info

Publication number: CN113273121B
Application number: CN201980088592.8A
Authority: CN
Inventors: 李栋; 刘勇
Original assignee: Nokia Shanghai Bell Co Ltd; Nokia Solutions and Networks Oy
Current assignee: Nokia Shanghai Bell Co Ltd; Nokia Solutions and Networks Oy
Priority date: 2019-01-11
Filing date: 2019-01-11
Publication date: 2022-11-29
Anticipated expiration: 2039-01-11
Also published as: CN113273121A; WO2020143053A1

Abstract

Embodiments of the present invention provide a method, apparatus, and computer-readable medium for measuring sidelink received signal strength. The method includes obtaining, at a terminal device, received power measurements on subchannels of a sidelink over a time interval. The method also includes determining an indication for the subchannel based at least in part on the received power measurement, the indication indicating a received power associated with periodic transmissions within the time interval and not indicating a received power associated with aperiodic transmissions within the time interval. The method also includes determining a signal strength of the subchannel based at least in part on the indication.

Description

Method, apparatus and computer readable medium for measuring sidelink received signal strength

Technical Field

Embodiments of the present disclosure relate generally to communication technology and, more particularly, relate to a method, apparatus, and computer-readable medium for measuring sidelink received signal strength.

Background

Communication technologies have been developed in various communication standards to provide a common protocol that enables different wireless devices to communicate at a municipal, national, regional, or even global level. One example of an emerging communication standard is New Radio (NR), e.g., 5G radio access. NR is a set of enhancements to the Long Term Evolution (LTE) mobile standard promulgated by the third generation partnership project (3 GPP). Vehicle-to-all (V2X) communication is the transfer of information from a vehicle to any entity that may affect the vehicle, and vice versa. It is a vehicle communication system that incorporates other more specific communication types, such as V2I (vehicle-to-infrastructure), V2N (vehicle-to-network), V2V (vehicle-to-vehicle), V2P (vehicle-to-pedestrian), V2D (vehicle-to-device), and V2G (vehicle-to-grid). The problem of NR V2X also needs to be solved due to the improvement of NR over LTE.

Disclosure of Invention

In general, example embodiments of the present disclosure provide a solution for measuring sidelink received signal strength.

In a first aspect, a method for communication is provided. The method includes obtaining, at a terminal device, received power measurements on subchannels of a sidelink over a time interval. The method also includes determining an indication for the subchannel based at least in part on the received power measurement, the indication indicating a received power associated with the periodic transmission within the time interval and not indicating a received power associated with the aperiodic transmission within the time interval. The method also includes determining a signal strength of the subchannel based at least in part on the indication.

In a second aspect, an apparatus is provided. The apparatus includes at least one processor; and at least one memory including computer program code; the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus to: obtaining, at a terminal device, received power measurements on subchannels of a sidelink over a time interval; determining an indication for the subchannel based at least in part on the received power measurement, the indication indicating a received power associated with periodic transmissions within the time interval and not indicating a received power associated with aperiodic transmissions within the time interval; and determining a signal strength of the subchannel based, at least in part, on the indication.

In a third aspect, an apparatus for communication is provided. The apparatus includes means for obtaining received power measurements on subchannels of a sidelink over a time interval. The apparatus further includes means for determining an indication of the sub-channel based at least in part on the received power measurement, the indication indicating a received power associated with the periodic transmission within the time interval and not indicating a received power associated with the aperiodic transmission within the time interval. The apparatus also includes means for determining a signal strength of the subchannel based at least in part on the indication.

In a fourth aspect, a computer readable medium is provided, comprising program instructions for causing an apparatus to perform at least a method according to the first aspect described above.

It should be understood that this summary is not intended to identify key or essential features of the embodiments of the disclosure, nor is it intended to be used to limit the scope of the disclosure. Other features of the present disclosure will become readily apparent from the following description.

Drawings

Some example embodiments will now be described with reference to the accompanying drawings, in which:

FIG. 1 illustrates an example communication network in which embodiments of the present disclosure may be implemented;

fig. 2 illustrates a flow chart of a method implemented at a terminal device in accordance with an embodiment of the disclosure;

fig. 3 illustrates a schematic diagram of an example configuration of a Transmission Time Interval (TTI) in accordance with some embodiments of the present disclosure;

fig. 4 illustrates a schematic diagram showing an example of a Reference Signal (RS) pattern in the frequency domain, in accordance with some embodiments of the present disclosure;

figure 5 illustrates a schematic diagram showing another example configuration of TTIs, in accordance with some embodiments of the present disclosure;

FIG. 6 illustrates a graph showing simulation results, in accordance with some embodiments of the present disclosure; and

fig. 7 illustrates a simplified block diagram of an apparatus suitable for implementing embodiments of the present disclosure.

Throughout the drawings, the same or similar reference numbers represent the same or similar elements.

Detailed Description

The principles of the present disclosure will now be described with reference to a few exemplary embodiments. It is understood that these embodiments are described for illustrative purposes only and are presented to aid those skilled in the art in understanding and enabling the disclosure, without placing any limitation on the scope of the disclosure. The disclosure described herein may be implemented in a variety of other ways besides those described below.

In the following description and claims, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.

References in the present disclosure to "one embodiment," "an example embodiment," etc., indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.

It will be understood that, although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element, without departing from the scope of example embodiments. As used herein, the term "and/or" includes any and all combinations of one or more of the listed terms.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises," "comprising," "includes," "having," "with," "contains" and/or "containing," when used herein, specify the presence of stated features, elements, and/or components, etc., but do not preclude the presence or addition of one or more other features, elements, components, and/or groups thereof.

As used in this application, the term "circuitry" may refer to one or more or all of the following:

(a) Hardware-only circuit implementations (such as those in analog and/or digital circuitry only)

Now); and

(b) A combination of hardware circuitry and software, such as (as applicable):

(i) Combinations of analog and/or digital hardware circuit(s) and software/firmware, and

(ii) Hardware processor(s) with software (including digital signal processor (s)), software, and any portion of memory(s) that work in conjunction to cause a device, such as a mobile phone or server, to perform various functions; and

(c) Hardware circuit(s) and/or processor(s), such as microprocessor(s) or a portion of microprocessor(s), that require software (e.g., firmware) to operate (although software may not be present when operation is not required).

This definition of "circuitry" applies to all uses of the term in this application, including in any claims. As another example, as used in this application, the term "circuitry" also encompasses an implementation of purely hardware circuitry or a processor (or multiple processors) or a portion of a hardware circuitry or a processor and its (or their) accompanying software and/or firmware. The term "circuitry" also encompasses (e.g., and if applicable to the particular claim element) a baseband integrated circuit or processor integrated circuit for a mobile device or a similar integrated circuit in a server, a cellular network device, or other computing or network device.

As used herein, the term "communication network" refers to a network that conforms to any suitable communication standard, such as Long Term Evolution (LTE), LTE-advanced (LTE-a), wideband Code Division Multiple Access (WCDMA), high Speed Packet Access (HSPA), narrowband internet of things (NB-IoT), and so on. Further, communication between the terminal device and the network device in the communication network may be performed according to any suitable generation communication protocol, including but not limited to first generation (1G), second generation (2G), 2.5G, 2.75G, third generation (3G), fourth generation (4G), 4.5G, future fifth generation (5G) communication protocols, and/or any other protocol now known or developed in the future. Embodiments of the present disclosure may be applied to various communication systems. Given the rapid development of communications, there will of course also be future types of communication techniques and systems that may embody the present disclosure. The scope of the present disclosure should not be limited to the above-described systems.

As used herein, the term "network device" refers to a node in a communication network via which a terminal device accesses the network and receives services therefrom. A network device may refer to a Base Station (BS) or an Access Point (AP), e.g., a NodeB (NodeB or NB), evolved NodeB (eNodeB or eNB), NR NB (also known as gNB), remote Radio Unit (RRU), radio Header (RH), remote Radio Head (RRH), relay, low power node (such as femto, pico, etc.), depending on the terminology and technology applied.

The term "terminal device" refers to any end device that may be capable of wireless communication. By way of example, and not limitation, a terminal device may also be referred to as a communication device, user Equipment (UE), subscriber Station (SS), portable subscriber station, mobile Station (MS), or Access Terminal (AT). The end devices may include, but are not limited to, mobile phones, cellular phones, smart phones, voice over IP (VoIP) phones, wireless local loop phones, tablet computers, wearable end devices, personal Digital Assistants (PDAs), portable computers, desktop computers, image capture end devices such as digital cameras, gaming end devices, music storage and playback devices, in-vehicle wireless end devices, wireless endpoints, mobile stations, laptop embedded devices (LEEs), laptop installed devices (LMEs), USB dongles, smart devices, wireless Customer Premises Equipment (CPE), internet of things (loT) devices, watches or other wearable devices, head Mounted Displays (HMDs), vehicles, drones, medical devices and applications (e.g., tele-surgery), industrial devices and applications (e.g., robots and/or other wireless devices operating in industrial and/or automated processing chain environments), consumer electronics, devices operating on commercial and/or industrial wireless networks, and the like. In the following description, the terms "terminal device", "communication device", "terminal", "user equipment" and "UE" may be used interchangeably.

As described above, V2X has been proposed. LTE V2X sidelights have been defined in LTE release 14 to support direct communication of basic roadway safety services (e.g., vehicle status information such as location, speed, heading, etc.) between the vehicle and the vehicle/pedestrian/infrastructure. In LTE release 15, the V2X sidelink is further enhanced with carrier aggregation, higher order modulation, and delay reduction features to support more diverse traffic and more stringent service requirements.

In LTE V2X release 14/15, channel sensing based resource (re) selection and reservation is applied in V2X sidelink mode 4 (where the UE performs autonomous resource selection) to avoid resource selection conflicts as much as possible. Once the UE has a packet to transmit and the Medium Access Control (MAC) layer instructs the Physical (PHY) layer to make a candidate resource selection, the UE will perform a process of candidate resource subset selection based on channel sensing operations. The channel sensing procedure mainly comprises two main operations: (1) A control channel, i.e., a physical side link control channel (PSCCH), is decoded and a Reference Signal Received Power (RSRP) of a corresponding data channel, i.e., RSRP of a physical side link shared channel (PSCCH) (psch-RSRP), is measured. Excluding some resources from the set of candidate resources based on RSRP to avoid collisions with higher received power and/or higher packet priority; (2) The sidelink received signal strength (S-RSS) is measured and a sidelink received signal strength indicator (S-RSSI) is obtained for each sub-channel, then the remaining resources are sorted and the resource with the smallest S-RSSI is reported to the MAC sublayer for final resource determination.

The S-RSSI is defined as the linear average of the total received power in the configured sub-channel over all SC-FDMA symbols (i.e., sidelink TTIs) excluding the first and last symbols in the subframe, and the final S-RSSI measurement is obtained by averaging the S-RSSI values over multiple periods (typically fixed at 100ms in LTE V2X release 14/15).

Currently, for NR V2X, it has been agreed to define at least two resource allocation patterns (i.e., pattern 1 and pattern 2) for sidelink transmissions, where pattern 1 is based on gNB scheduling, while pattern 2 uses UE autonomous resource selection that may be based on sidelink channel sensing operations. Furthermore, it has been agreed to study side-link measurements in the channel sensing process.

Furthermore, sidelink channel sensing operations for UE autonomous resource selection in LTE V2X release 14/15 as discussed above assume that only periodic V2X traffic is supported. In this case, the measurement of the sidelink received signal strength (e.g., S-RSSI) and averaging over a number of consecutive periods reflects the statistics of resource usage and average received power levels, which has at least the following functions: a) Probing the associated control channel for side link channels/signals that are not decoded, e.g., due to severe collisions; b) Filtering out fast fading channel effect, and providing more robust measurement reference for side link resource selection; c) Flexibly supporting the situation where a certain packet does not exist in a certain period but still needs to reserve resources for the next period. In this case, although no packet is transmitted in this period (and thus resource exclusion based on psch-RSRP is not possible), S-RSSI results averaged over multiple periods may protect the resource for the next period.

However, in the NR V2X side link, one significant difference from LTE V2X is that for various V2X traffic types, such as broadcast, multicast, and unicast sidelink transmissions, both periodic V2X traffic and aperiodic V2X traffic will be supported. Meanwhile, in order to improve resource usage efficiency, periodic and aperiodic V2X packets may coexist in the same resource pool. In this case, the aperiodic packet will have a potentially negative impact on the channel sensing process, especially on the measurement of the received signal strength of the side link. This may reduce the benefit of sensing-based resource selection and reduce system performance.

In accordance with an embodiment of the present disclosure, a solution for measuring sidelink received signal strength is presented to address the above-referenced problems and other potential problems. In the proposed solution, the contribution of aperiodic packets to the received signal strength is explicitly or implicitly excluded. In some cases, received power measurements are performed on symbols used for data transmission and Reference Signal (RS) transmission, and S-RSs is determined by explicitly excluding Reference Signal Received Power (RSRP) associated with aperiodic transmissions. In some cases, the received power measurement is performed only on symbols used for RS transmission based on a configured RS pattern that distinguishes between periodic and aperiodic transmissions. In this way, the impact of aperiodic transmissions on sidelink received signal strength measurements may be reduced and sidelink measurements used in sidelink channel sensing procedures for NR V2X or other device-to-device (D2D) communications may be improved.

The principles and implementations of the present disclosure will be described in detail below in conjunction with fig. 1-7.

Fig. 1 illustrates an example communication network 100 in which embodiments of the present disclosure may be implemented. Network 100 includes a network device 110 and three

terminal devices

120, 130, and 140 served by network device 110. The service area of network device 110 is referred to as a cell 102. It should be understood that the number of network devices and terminal devices is for illustration purposes only and does not present any limitation. Network 100 may include any suitable number of network devices and terminal devices suitable for implementing embodiments of the present disclosure.

The

terminal devices

120, 130, and 140 shown in fig. 1 may be associated with a vehicle. For example, some or all of the

terminal devices

120, 130, and 140 may be in-vehicle terminal devices, or may be part of a vehicle. Some or all of the

end devices

120, 130, and 140 may be associated with infrastructure, pedestrians, other devices, or the power grid. Although embodiments of the present disclosure are described with respect to a V2X scene, it should be understood that embodiments of the present disclosure are equally applicable to any terminal device capable of D2D communication.

In communication network 100, network device 110 may communicate data and control information to

terminal devices

120, 130, and 140, and

terminal devices

120, 130, and 140 may also communicate data and control information to network device 110. The link from network device 110 to

terminal device

120 or 130 or 140 is referred to as the Downlink (DL) and the link from

terminal device

120 or 130 or 140 to network device 110 is referred to as the Uplink (UL).

In addition to communication via network device 110,

end devices

120, 130, and 140 may communicate with each other via D2D communication links. As used herein, the D2D communication link used for D2D communication between

terminal devices

120, 130, and 140 and other terminal devices not shown may be referred to as a sidelink. As shown in fig. 1, terminal device 120 may communicate with terminal device 130 via a side link 135 and with terminal device 140 via a side link 145. Further, in the case where the

terminal devices

120, 130, and 140 are in-vehicle terminal devices, communication related to the

terminal devices

120, 130, and 140 may be referred to as V2X communication.

Communications in communication system 100 may be implemented in accordance with any suitable communication protocol(s), including but not limited to first generation (1G), second generation (2G), third generation (3G), fourth generation (4G), and fifth generation (5G), cellular communication protocols such as Institute of Electrical and Electronics Engineers (IEEE) 802.11, wireless local area network communication protocols, and/or any other protocol currently known or developed in the future. Further, the communication may utilize any suitable wireless communication technology, including but not limited to: code Division Multiple Access (CDMA), frequency Division Multiple Access (FDMA), time Division Multiple Access (TDMA), frequency Division Duplex (FDD), time Division Duplex (TDD), multiple Input Multiple Output (MIMO), orthogonal Frequency Division Multiple Access (OFDMA), and/or any currently known or later developed technique.

When operating in an autonomous resource selection mode (e.g., mode 2 described above),

terminal devices

120, 130, and 140 may autonomously select resources for transmission from a pool of resources by means of a channel sensing procedure. In NR V2X, in order to better perform resource selection for sidelink transmission, the

terminal devices

120, 130, and 140 need to exclude the influence of aperiodic transmission during channel sensing.

Implementations of the present disclosure will now be described in detail below with reference to fig. 2-7. Fig. 2 illustrates a flow diagram of an example method 200 in accordance with an embodiment of the present disclosure. It should be understood that method 200 may include additional blocks not shown and/or may omit some blocks shown, and the scope of the present disclosure is not so limited. Method 200 may be implemented at a terminal device, such as terminal device 120 shown in fig. 1. Additionally or alternatively, method 200 may also be implemented at

terminal devices

130 and 140, as well as other terminal devices not shown in fig. 1. For discussion purposes only, the method 200 performed by the terminal device 120 will be described with reference to fig. 1.

When a terminal device 120 operating in autonomous resource selection mode has a packet to transmit, it may select a candidate resource for transmitting the packet via a sidelink based on a channel sensing procedure. As part of the channel sensing process, terminal device 120 may perform S-RSS measurements.

At block 210, terminal device 120 obtains received power measurements on subchannels of the sidelink over a time interval. The subchannels may comprise a configurable number of Physical Resource Blocks (PRBs) in the frequency domain and may be any configuration of subchannels. Although the process of S-RSS measurement is described herein with respect to one sub-channel, terminal device 120 may perform S-RSS measurement for each configured sub-channel.

The time interval may be a fraction of a TTI. For example, a time interval may include all SC-FDMA symbols except the first and last symbol in a TTI. The time interval may include symbols for transmitting data (referred to herein as data symbols for ease of discussion) and symbols for transmitting RSs (referred to herein as RS symbols for ease of discussion).

Referring now to fig. 3, fig. 3 illustrates a schematic diagram 300 showing an example configuration of a TTI310, according to some embodiments of the present disclosure. As shown in fig. 3, the time interval 350 includes symbols of the TTI310 except for the first symbol 311 and the last symbol 321. The first symbol 311 may be configured for automatic gain control and the last symbol 321 may be a punctured symbol as a guard time. RS, such as demodulation reference signals (DMRS), may be transmitted in RS symbols 301-304, and data may be transmitted in data symbols 311-319 in the same TTI 310. RS symbols used for transmission of DMRS may also be referred to as DMRS symbols.

The time interval may be defined as other lengths of time and the scope of the present disclosure is not limited in this respect. For example, the time interval may include all symbols in the TTI310 when the first symbol 311 and the last symbol 321 are not reserved for other purposes. Alternatively, the time interval may include symbols 301-304 and 311-319 in the TTI310 except for the last symbol 321.

In some embodiments, terminal device 120 may perform received power measurements on data symbols and RS symbols, as in the channel sensing procedure for LTE V2X. For example, terminal device 120 can measure received power for data symbols 312-319 and RS symbols 301-340. For scenarios with mixed periodic and aperiodic transmissions, the results of receiving the power measurement in this case may include a power contribution from the aperiodic transmission, which will be removed in subsequent steps described below with reference to block 220.

In some embodiments, terminal device 120 may perform received power measurements only on RS symbols (e.g., RS symbols 301-304) or some of the RS symbols in time interval 350 based on a predefined RS pattern that distinguishes reference signals associated with periodic transmissions from reference signals associated with aperiodic transmissions. For purposes of discussion, these embodiments may be referred to as "RS-only measurements. The periodic transmission and the aperiodic transmission may employ an orthogonal RS pattern. For example, the orthogonal RS pattern may be implemented in a Frequency Division Multiplexing (FDM) and/or Time Division Multiplexing (TDM) manner.

In such embodiments, resources configured for transmission of RSs associated with periodic transmissions may not be occupied by aperiodic transmissions. For orthogonal RS patterns implemented via TDM, different RS symbols in TTI310 may be configured to transmit RSs associated with periodic and aperiodic transmissions, respectively. For example,

RS symbols

301 and 303 may be configured to transmit RSs associated with periodic transmissions, while

RS symbols

302 and 304 may be configured to transmit RSs associated with aperiodic transmissions.

For orthogonal RS patterns implemented with FDM, different resource elements or subcarriers corresponding to RS symbols can be configured to transmit RS associated with periodic and aperiodic transmissions, respectively. For example, a comb-like RS pattern in the frequency domain may be employed. This will be described below with reference to fig. 4.

In such an embodiment, since the terminal device 120 can distinguish between the RS associated with the periodic transmission and the RS associated with the aperiodic transmission, the reception power measurement can be performed based only on the power received on the resource(s) for the RS associated with the periodic transmission. For example, terminal device 120 can determine a target subset of resources for RSs associated with the periodic transmission from a configured pool of resources for subchannels over an interval (e.g., interval 350). In this case, the target subset of resources is not occupied by aperiodic transmissions. Terminal device 120 may then perform receive power measurements based only on the target subset of resources. Such an embodiment will be described in detail below with reference to fig. 3, 4 and 5.

Still referring to fig. 2. At block 220, terminal device 120 determines an indication for the subchannel based at least in part on the received power measurement. The indication indicates a received power associated with periodic transmissions within the time interval and does not indicate a received power associated with non-periodic transmissions within the time interval. The determined indication may be in the form of an S-RSSI.

In the above-described embodiments where received power measurements are performed based on RS symbols only (i.e., RS-only measurements), the indication for the sub-channels within the time interval may be determined as a linear average of the total received power over the symbols for which received power measurements are performed. For example, if the received power measurements are performed based on

RS symbols

301 and 303 only, the indication may be a linear average of the total received power over the configured sub-channels within

symbols

301 and 303. In this case, since the power contribution from the aperiodic transmission is not included during the received power measurement, the indication may be determined simply based on the received power measurement at block 210.

In the above-described embodiments in which received power measurements are performed on data symbols and RS symbols, additional operations may be required to exclude power contributions from aperiodic transmissions. Terminal device 120 may determine the initial indication based on the results of the received power measurements. For example, the terminal device 120 may determine an initial S-RSSI, which is a linear average of the total received power over the configured subchannels in the data symbols and RS symbols (such as in data symbols 312-319 and RS symbols 301-304) for which received power measurements are performed.

The terminal device 120 can then obtain RSRP associated with the aperiodic transmission in the time interval. For example, terminal device 120 may measure the RSRP of an aperiodic packet on the data channel psch or the corresponding control channel PSCCH according to the decoded information for the corresponding control channel PSCCH.

The terminal device 120 may then determine the indication based on the initial indication and the RSRP. For example, an indication for a subchannel within a time interval (such as S-RSSI) may be determined by subtracting a value derived from RSRP from a corresponding initial indication (e.g., initial S-RSSI). It is noted that if RSRP is measured over more than one symbol, the average over more than one symbol should be considered.

At block 230, terminal device 120 may determine a signal strength of the subchannel based at least in part on the indication. In some embodiments, the signal strength of a subchannel may simply be determined as the value of the indication determined at block 220.

In some embodiments, the signal strength of a subchannel may be determined by averaging indications over multiple sidelink periods. In these embodiments, terminal device 120 may obtain another indication for the channel determined based at least in part on another received power measurement on the subchannel over another time interval. The further time interval precedes the time interval. Terminal device 120 may then determine the signal strength of the sub-channel based on the indication and the other indication. The signal strength may be an average of the indication and the further indication.

For example, the final S-RSSI for a subchannel may be determined by averaging the values of S-RSSI over multiple time intervals over a configurable number of consecutive sidelink periods. In this case, averaging of the S-RSSI values over multiple sidelink periods is performed over a configurable number of consecutive sidelink periods. The sidelink period herein may be a sidelink packet period of the terminal device 120 (e.g., a UE performing channel sensing), or may be configured by the network device 110, or may be fixed to a particular value.

Thus, in some embodiments, the further time interval precedes the time interval by a time period. The time period may be based on at least one of: a period of periodic transmissions to be performed by terminal device 120 on the sidelink; a value configured by the network device 110 serving the terminal device 120; and a fixed value.

The above described sidelink received signal strength measurement procedure is described with respect to one subchannel. Terminal device 120 may apply the same procedure to each configured sub-channel such that resource selection may be performed based on the channel sensing procedure. In this way, the impact of aperiodic transmissions on sidelink received signal strength measurements may be reduced and sensing-based resource selection may be improved.

As described above, an orthogonal RS pattern may be employed in some embodiments. Such an embodiment (i.e., RS-only based measurement) will be described in detail with reference to fig. 3-5.

Referring to fig. 3, for an orthogonal RS pattern implemented in a TDM manner, some of the RS symbols 301-304 may be configured for reference signals associated with periodic packets, while some other of the RS symbols 301-304 may be configured for reference signals associated with aperiodic packets. For example only,

RS symbols

301 and 302 may be configured for reference signals associated with periodic packets, while

RS symbols

303 and 304 may be configured for reference signals associated with aperiodic packets.

In such embodiments, to obtain the received power measurements at block 210, terminal device 120 may first determine the location(s) of RS symbol(s) used to transmit reference signals associated with the periodic transmission based on a predefined RS pattern. Terminal device 120 can determine from time interval 350 a set of symbols configured for transmission of a reference signal associated with a periodic transmission. For example, terminal device 120 may determine the locations of

symbols

301 and 302. The terminal device 120 can then determine resources corresponding to the set of symbols. For example, terminal device 120 can determine PRBs corresponding to

RS symbols

301 and 302 that are configured for subchannels.

As such, S-RSs measurements will be performed based only on the determined target subset of resources (e.g., in this case, the resources corresponding to RS symbols 301 and 302). In this way, the S-RSS measurements contain only the contribution from the received power of the periodic transmission, and the power contribution from the aperiodic transmission can be explicitly removed.

Referring now to fig. 4, fig. 4 illustrates a schematic diagram 400 showing an example of RS patterns in the frequency domain, in accordance with some embodiments of the present disclosure. For convenience of explanation, the RS pattern is shown in only one PRB.

In such embodiments, the RS may occupy only some of the frequencies/subcarriers configured for the subchannels. Fig. 4 shows RS 450 and RS 460 in a comb RS pattern (e.g., a comb DMRS pattern). RS 450 is associated with periodic transmissions and RS 460 is associated with aperiodic transmissions. In a comb-like DMRS structure with discontinuous frequency resources, a frequency offset may be used to indicate a starting frequency/subcarrier of the RS with respect to a starting frequency of the selected resource.

In the illustrated example, the comb offset of comb RS 450 is 0, so comb RS 450 occupies

subcarriers

0, 2, 4, 6, 8, and 10 of a PRB having a total of 12 subcarriers. Likewise, the comb offset of comb RS 460 is 1, and comb RS 460 occupies

subcarriers

1, 3, 5, 7, 9, and 11 of the PRB. For a comb RS 450 transmitted in a certain RS symbol, RS 450 occupies only resource elements that are evenly spaced in the frequency domain, e.g.,

resource elements

401, 403, 405, 407, 409, and 411. Thus,

resource elements

402, 404, 406, 408, 410, and 412 are null resource elements. Likewise, for a comb RS 460 transmitted in a certain RS symbol, the RS 460 occupies only resource elements, e.g.,

resource elements

422, 424, 426, 428, 430, and 432, that are evenly spaced in the frequency domain. As a result,

resource elements

421, 423, 425, 427, 429, and 431 are null resource elements.

It is understood that the comb-like RS pattern (comb-like 2RS structure) shown in fig. 4 is only an example, and other comb-like RS patterns may be adopted. For example, a Comb 4 (Comb-4) RS structure may be employed that has Comb offsets of 0 and 2 for RSs associated with periodic packets and Comb offsets of 1 and 3 for RSs associated with non-periodic packets.

Other orthogonal RS patterns besides the comb-like RS pattern may also be employed. For example, subcarriers 0-6 of a PRB may be configured for transmission of RSs associated with periodic packets and subcarriers 7-11 of a PRB may be configured for transmission of RSs associated with aperiodic packets.

Thus, in embodiments where the orthogonal RS pattern is implemented by FDM manner as described above, the terminal device 120 need only perform S-RSs measurements based on resource elements configured for transmission of RSs associated with periodic packets.

In such embodiments, to obtain the received power measurements at block 210, the terminal device 120 may determine a target subset of resources for performing the received power measurements from the resources corresponding to the RS symbols. Terminal device 120 may determine a set of resource elements in the configured subchannel that correspond to symbols within a time interval. The symbol is configured for transmission of reference signals associated with periodic and aperiodic transmissions, e.g., RS symbol 301. The terminal device 120 can then select a subset of resource elements from the set of resource elements, the subset of resource elements being used for transmitting reference signals associated with the periodic transmission. This process for selecting a subset of resource elements may be performed for some or all RS symbols within a time interval.

For the comb RS example shown in fig. 4,

resource elements

401, 403, 405, 407, 409, and 411 (and other resource elements not shown, if any) may be determined as a target subset of resources for performing received power measurements. In this way, the power contribution from the periodic transmission is included in the S-RSS measurements. Similarly,

resource elements

421, 423, 425, 427, 429, and 431 (and other resource elements not shown, if any) may also be determined to be the target resource subset. Since RS 460 is associated with aperiodic transmissions, these resource elements are null. As a result, the received power measured based on these resource elements is zero or very low. In this way, the power contribution from the aperiodic transmission is implicitly removed from the S-RSS measurements.

The orthogonal RS pattern implemented in FDM fashion as described with reference to fig. 4 is time efficient. Therefore, these embodiments are preferred for V2X traffic, especially in case of high mobility requirements.

In some embodiments, the RS symbols within a time interval may include a base RS symbol(s) and an additional RS symbol(s). The basic RS symbol is configured or pre-configured and thus the terminal device 120 can know the position of the basic RS symbol. The additional RS symbol(s) are dynamically configured to support high mobility scenarios. Thus, terminal device 120 may not know the location of the additional RS symbol(s) unless the corresponding control channel is decoded by terminal device 120. That is, the position of the additional RS symbol(s) will be determined based on the control information. In this case, the measurement of S-RSS may be performed based on only the basic RS symbol (S).

Referring to fig. 5, fig. 5 illustrates a schematic diagram 500 showing another example configuration of a TTI 510, according to some embodiments of the present disclosure. As shown, symbol 511 and symbol 521 are reserved for automatic gain control and guard time, respectively. The time interval 550 includes

basic RS symbols

501 and 503 and

additional RS symbols

502 and 504. As such, the S-RSS measurements described above with reference to fig. 3 and 4 will be performed on the

elementary RS symbols

501 and 503.

In such embodiments, terminal device 120 may determine the basic RS symbols, e.g.,

basic RS symbols

501 and 503, from time interval 550 and determine the target subset of resources based only on the basic RS symbols. The determination of the target resource subset based on the basic RS symbols may be performed according to the orthogonal RS pattern described with reference to fig. 3 and 4. It should be noted that the aspects described with reference to fig. 3-5 may be combined as desired.

Fig. 6 illustrates a graph 600 showing simulation results, in accordance with some embodiments of the present disclosure. A system level simulation is performed to evaluate the performance gain of the proposed solution. In the simulation, a highway scenario with a UE speed of 140kmph is assumed. Assume broadcast V2X traffic, where 50% of the UEs have periodic sidelink packets and 50% of the UEs have aperiodic sidelink packets. For periodic packets, the packet size is 800 bytes with 80% probability, or 1200 bytes with 20% probability; while for aperiodic packets, the packet sizes are evenly distributed among values of 200, 400, 600, … …, 2000 bytes. In the simulation, it is assumed that 16QAM with 1/2 rate LDPC coding is used without packet retransmission. Periodic and aperiodic sidelink packet transmissions share the same resource pool. In the simulation, UE autonomous resource selection based on sensing is used, and S-RSSI measurement (i.e., the energy measurement shown in the figure) is part of the sidelink channel sensing procedure.

As shown, two energy measurement processes are compared, where curve 601 is for measurements with the proposed solution to remove aperiodic packet received power, and curve 602 is for measurements without removing aperiodic packets, which means that the measured energy contains contributions from both periodic and aperiodic packets. As can be seen from the simulation results shown in fig. 6, the proposed measurement procedure for S-RSSI can greatly improve the system performance. For example, at a Packet Reception Rate (PRR) of 90%, the proposed scheme can increase the sidelink communication range from 180 meters to around 270 meters.

In some embodiments, an apparatus (e.g., terminal device 120) capable of performing method 200 may include means for performing the respective steps of method 200. The component may be implemented in any suitable form. For example, the components may be implemented in circuitry or software modules.

In some embodiments, the apparatus comprises: means for obtaining received power measurements on subchannels of a sidelink over a time interval; means for determining an indication of a sub-channel based at least in part on the received power measurement, the indication indicating a received power associated with periodic transmissions within the time interval and not indicating a received power associated with aperiodic transmissions within the time interval; and means for determining a signal strength of the subchannel based, at least in part, on the indication.

In some embodiments, the means for obtaining the received power measurement comprises: means for determining a target subset of resources for reference signals associated with periodic transmission from a set of resources of a subchannel allocated to the time interval, the target subset of resources not being occupied by aperiodic transmission; and means for performing receive power measurements based only on the subset of target resources.

In some embodiments, the means for determining the target subset of resources comprises: means for determining a set of resource elements corresponding to symbols within a time interval, the symbols configured for transmission of reference signals associated with periodic and aperiodic transmissions; and means for selecting a subset of resource elements from the set of resource elements, the subset of resource elements for transmitting reference signals associated with the periodic transmission.

In some embodiments, the resource elements in the subset are evenly spaced in the frequency domain.

In some embodiments, the means for determining the target subset of resources comprises: means for determining a set of symbols from a time interval configured for transmission of a reference signal associated with a periodic transmission; and means for determining resources corresponding to the set of symbols.

In some embodiments, the time interval comprises a first symbol and a second symbol for transmitting the reference signal, the position of the first symbol is configured or preconfigured and the position of the second symbol is to be determined based on the control information. The means for determining the target subset of resources comprises: means for determining a first symbol from a time interval; and means for determining the target subset of resources based only on the first symbol.

In some embodiments, the reference signal comprises a demodulation reference signal.

In some embodiments, the means for determining an indication for a subchannel comprises: means for determining an initial indication based on a result of the received power measurement; means for obtaining a reference signal received power, RSRP, associated with aperiodic transmission in the time interval; and means for determining an indication based on the initial indication and the RSRP.

In some embodiments, the means for determining the signal strength of a subchannel comprises: means for obtaining another indication for the sub-channel, the other indication determined based at least in part on another received power measurement on the sub-channel within another time interval, the other time interval preceding the time interval; and means for determining a signal strength of the subchannel based on the indication and the other indication.

In some embodiments, the further time interval is a time period before the time interval and the time period is based on at least one of: a period of periodic transmissions to be performed by the terminal device on the sidelink; a value configured by a network device serving the terminal device; and a fixed value.

Fig. 7 is a simplified block diagram of a device 700 suitable for implementing embodiments of the present disclosure. Device 700 may be viewed as another example implementation of

terminal device

120 or 130 or 140 as shown in fig. 1. Thus, device 700 may be implemented at

terminal device

120 or 130 or 140 or as at least a portion of

terminal device

120 or 130 or 140.

As shown, device 700 includes a processor 710, a memory 720 coupled to processor 710, a suitable Transmitter (TX) and Receiver (RX) 740 coupled to processor 710, and a communication interface coupled to TX/RX 740. The memory 720 stores at least a portion of the program 730. TX/RX 740 is used for bi-directional communication. TX/RX 740 has at least one antenna to facilitate communication, although in practice an access node referred to in this application may have several antennas. The communication interface may represent any interface required for communication with other network elements, such as an X2 interface for bidirectional communication between enbs, an S1 interface for communication between a Mobility Management Entity (MME)/serving gateway (S-GW) and an eNB, a Un interface for communication between an eNB and a Relay Node (RN), or a Uu interface for communication between an eNB and a terminal device.

The program 730 is assumed to include program instructions that, when executed by the associated processor 710, enable the device 700 to operate in accordance with embodiments of the present disclosure, as discussed herein with reference to fig. 2 and 5. Embodiments herein may be implemented by computer software executable by the processor 710 of the device 700, or by hardware, or by a combination of software and hardware. The processor 710 may be configured to implement various embodiments of the present disclosure. Further, the combination of processor 710 and memory 720 may form a processing device 750 suitable for implementing various embodiments of the present disclosure.

The memory 710 may be of any type suitable to a local technology network and may be implemented using any suitable data storage technology, such as non-transitory computer-readable storage media, semiconductor-based storage devices, magnetic storage devices and systems, optical storage devices and systems, fixed memory and removable memory, as non-limiting examples. Although only one memory 710 is shown in device 700, there may be several physically distinct memory modules in device 700. The processor 710 may be of any type suitable to the local technology network, and may include one or more of general purpose computers, special purpose computers, microprocessors, digital Signal Processors (DSPs) and processors based on a multi-core processor architecture, as non-limiting examples. The device 700 may have multiple processors, such as an application specific integrated circuit chip that is slaved in time to a clock that is synchronized to the main processor.

In general, the various embodiments of the disclosure may be implemented in hardware or special purpose circuits, software, logic or any combination thereof. Some aspects may be implemented in hardware, while other aspects may be implemented in firmware or software which may be executed by a controller, microprocessor or other computing device. While various aspects of the embodiments of the disclosure are illustrated and described as block diagrams, flow charts, or using some other pictorial representation, it is well understood that the blocks, apparatus, systems, techniques or methods described herein may be implemented in, as non-limiting examples, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof.

The present disclosure also provides at least one computer program product tangibly stored on a non-transitory computer-readable storage medium. The computer program product comprises computer-executable instructions, such as those included in program modules, that execute in a device on a target real or virtual processor to perform the processes or methods described above with reference to any of fig. 2 and 5. Generally, program modules include routines, programs, libraries, objects, classes, components, data types, etc. that perform particular tasks or implement particular abstract data types. The functionality of the program modules may be combined or split between program modules as desired in various embodiments. Machine-executable instructions for program modules may be executed within local or distributed devices. In a distributed arrangement, program modules may be located in both local and remote memory storage media.

Program code for performing the methods of the present disclosure may be written in any combination of one or more programming languages. These program codes may be provided to a processor or controller of a general purpose computer, special purpose computer, or other programmable data processing apparatus, such that the execution of the program codes by the processor or controller causes the functions/operations specified in the flowchart and/or block diagram to be performed. The program code may execute entirely on the machine, partly on the machine, as a stand-alone software package, partly on the machine and partly on a remote machine or entirely on the remote machine or server.

The above program code may be embodied on a machine-readable medium, which may be any tangible medium that can contain, or store a program for use by or in connection with an instruction execution system, apparatus, or device. The machine-readable medium may be a machine-readable signal medium or a machine-readable storage medium. A machine-readable medium may include, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination thereof. More specific examples of a machine-readable storage medium include an electrical connection having one or more wires, a portable computer diskette, a hard disk, a Random Access Memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination thereof.

Further, while operations are depicted in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. In some cases, multitasking and parallel processing may be advantageous. Also, while several specific implementation details are included in the above discussion, these should not be construed as limitations on the scope of the disclosure, but rather as descriptions of features that may be specific to particular embodiments. Certain features that are described in the context of separate embodiments can also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment can also be implemented in multiple embodiments separately or in any suitable subcombination.

Although the disclosure has been described in language specific to structural features and/or methodological acts, it is to be understood that the disclosure defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.

Claims

1. A method for communication, comprising:

obtaining, at a terminal device, received power measurements on subchannels of a sidelink over a time interval;

determining an indication for the sub-channel based at least in part on the received power measurement, the indication indicating a received power associated with periodic transmissions within the time interval and not indicating a received power associated with aperiodic transmissions within the time interval; and

determining a signal strength of the sub-channel based at least in part on the indication.

2. The method of claim 1, wherein obtaining the received power measurement comprises:

determining a target subset of resources for reference signals associated with the periodic transmission from a set of resources of the subchannel within the time interval, the target subset of resources not occupied by the aperiodic transmission; and

performing the received power measurement based only on the target subset of resources.

3. The method of claim 2, wherein determining the target subset of resources comprises:

determining a set of resource elements corresponding to symbols within the time interval, the symbols configured for transmission of reference signals associated with the periodic transmission and the aperiodic transmission; and

selecting a subset of resource elements from the set of resource elements, the subset of resource elements being used for transmitting the reference signal associated with the periodic transmission.

4. The method of claim 3, wherein the resource elements in the subset are evenly spaced in the frequency domain.

5. The method of claim 2, wherein determining the target subset of resources comprises:

determining, from the time interval, a set of symbols configured for transmission of the reference signal associated with the periodic transmission; and

determining resources corresponding to the set of symbols.

6. The method of claim 2, wherein the time interval comprises a first symbol and a second symbol for transmitting reference signals, a position of the first symbol is configured or preconfigured and a position of the second symbol is to be determined based on control information, and determining the target subset of resources comprises:

determining the first symbol from the time interval; and

determining the target subset of resources based only on the first symbol.

7. The method of claim 2, wherein the reference signal comprises a demodulation reference signal.

8. The method of claim 1, wherein determining the indication for the subchannel comprises:

determining an initial indication based on a result of the received power measurement;

obtaining reference signal received power, RSRP, associated with the aperiodic transmission within the time interval; and

determining the indication based on the initial indication and the RSRP.

9. The method of claim 1, wherein determining the signal strength of the subchannel comprises:

obtaining another indication for the subchannel, the other indication determined based at least in part on another received power measurement on the subchannel over another time interval, the other time interval preceding the time interval; and

determining the signal strength of the sub-channel based on the indication and the another indication.

10. The method of claim 9, wherein the other time interval precedes the time interval by a time period and the time period is based on at least one of:

a period of periodic transmissions to be performed by the terminal device on the sidelink;

a value configured by a network device serving the terminal device; and

a fixed value.

11. An apparatus for communication, comprising:

at least one processor; and

at least one memory including computer program code;

the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus to:

12. The apparatus of claim 11, wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus to:

determining a target subset of resources for reference signals associated with the periodic transmission from a set of resources of the subchannel within the time interval, the target subset of resources being unoccupied by the aperiodic transmission; and

13. The apparatus of claim 12, wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus to:

14. The apparatus of claim 13, wherein resource elements in the subset are evenly spaced in the frequency domain.

15. The apparatus of claim 12, wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus to:

determining resources corresponding to the set of symbols.

16. The apparatus of claim 12, wherein the time interval comprises first and second symbols for transmitting reference signals, a position of the first symbol is configured or preconfigured and a position of the second symbol is to be determined based on control information, and the at least one memory and the computer program code are configured, with the at least one processor, to cause the apparatus to:

determining the first symbol from the time interval; and

determining the target subset of resources based only on the first symbol.

17. The apparatus of claim 12, wherein the reference signal comprises a demodulation reference signal.

18. The apparatus of claim 11, wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus to:

obtaining a reference signal received power, RSRP, associated with the aperiodic transmission within the time interval; and

determining the indication based on the initial indication and the RSRP.

19. The apparatus of claim 11, wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus to:

determining the signal strength of the sub-channel based on the indication and the other indication.

20. The apparatus of claim 19, wherein the other time interval precedes the time interval by a time period, and the time period is based on at least one of:

a period of periodic transmission to be performed by the terminal device on the sidelink;

a value configured by a network device serving the terminal device; and

a fixed value.

21. An apparatus for communication, comprising:

means for obtaining received power measurements on subchannels of a sidelink over a time interval;

means for determining an indication for the sub-channel based at least in part on the received power measurement, the indication indicating a received power associated with periodic transmissions within the time interval and not indicating a received power associated with aperiodic transmissions within the time interval; and

means for determining a signal strength of the sub-channel based at least in part on the indication.

22. A non-transitory computer readable medium comprising program instructions for causing an apparatus to perform at least a method according to any one of claims 1 to 10.