WO2022008068A1

WO2022008068A1 - Measurement signals for sensing

Info

Publication number: WO2022008068A1
Application number: PCT/EP2020/069520
Authority: WO
Inventors: Miguel Lopez; Dennis SUNDMAN
Original assignee: Telefonaktiebolaget Lm Ericsson (Publ)
Priority date: 2020-07-10
Filing date: 2020-07-10
Publication date: 2022-01-13

Abstract

A method is disclosed of a transmitter configured to transmit a physical layer packet comprising a packet extension (PE) field. The method comprises providing the physical layer packet with at least one measurement signal for channel estimation comprised in the PE field, and transmitting the physical layer packet. In some embodiments, the method further comprises transmitting an announcement indicating that the PE field comprises the at least one measurement signal for channel estimation. In some embodiments, the method further comprises receiving a request for inclusion of at least one measurement signal for channel estimation in the PE field, wherein the physical layer packet is provided with the at least one measurement signal for channel estimation comprised in the PE field in response to receiving the request. In some embodiments, transmitting the physical layer packet comprises using a PE transmitter configuration for transmission of the PE. The PE transmitter configuration may be an omni- directional transmitter configuration. Alternatively or additionally, the PE transmitter configuration may differ from a transmitter configuration used for transmission of one or more other fields of the physical layer packet. Corresponding method for a receiver, apparatuses, wireless communication device, and computer program product are also disclosed.

Description

MEASUREMENT SIGNALS FOR SENSING

TECHNICAL FIELD

The present disclosure relates generally to the field of sensing; e.g., wireless local area network (WLAN) sensing. More particularly, it relates to provision of measurement signals for channel estimation in the context of sensing.

BACKGROUND

The IEEE 802.11 standardization group has approved a Project Authorization Request (PAR) for wireless local area network (WLAN) sensing, one object of which is to develop an amendment to the IEEE 802.11 standard as follows.

"This amendment defines modifications to the IEEE 802.11 medium access control layer (MAC), the physical layer (PHY) of Directional Multi Gigabit (DMG), and the PHY under development of Next Generation 60 GHz (NG60) that enhance Wireless Local Area Network (WLAN) sensing (SENS) operation in license-exempt freguency bands between 1 GHz and 7.125 GHz and above 45 GHz. This amendment defines: at least one mode that enables stations (ST As) to perform one or more of the following: to exchange WLAN sensing capabilities, to reguest and setup transmissions that allow for WLAN sensing measurements to be performed, to indicate that a transmission can be used for WLAN sensing, and to exchange WLAN sensing feedback and information; WLAN sensing operation that relies on transmissions that are reguested, unsolicited, or both"

Some sensing approaches use statistics based on channel estimates (e.g., changes in the propagation environment). Typically, several channel estimates are made over time and machine learning techniques, or artificial intelligence, are applied to the channel estimates in order to make inferences and/or take decisions based on the changes in the propagation environment (e.g., regarding device positioning, radio environments, etc.). Channel estimation in IEEE 802.11 is typically based on LTFs. A long training field (LTF) comprises orthogonal frequency division multiplexing (OFDM) symbols which are known at the receiver, and generally intended for channel estimation. A legacy LTF consists of two OFDM symbols, while a high efficiency (HE) LTF consists of a variable number of OFDM symbols depending on how many streams are transmitted.

Also typically in IEEE 802.11, one or more LTFs are located in the physical layer (PHY) preamble of each PHY protocol data unit (PPDU), and sensing STAs can utilize the LTFs for channel estimation.

Generally, PPDUs used for sensing may also carry data, and the recipient of the data may be the sensing STA or another STA.

Provision of measurement signals for channel estimation may be inefficient in terms of resource utilization.

Therefore, there is a need for alternative approaches to provision of measurement signals for channel estimation in the context of sensing.

SUMMARY

It should be emphasized that the term "comprises/comprising" (replaceable by "includes/including") when used in this specification is taken to specify the presence of stated features, integers, steps, or components, but does not preclude the presence or addition of one or more other features, integers, steps, components, or groups thereof. 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.

Generally, when an arrangement is referred to herein, it is to be understood as a physical product; e.g., an apparatus. The physical product may comprise one or more parts, such as controlling circuitry in the form of one or more controllers, one or more processors, or the like.

It is an object of some embodiments to solve or mitigate, alleviate, or eliminate at least some of the above or other disadvantages.

A first aspect is a method of a transmitter configured to transmit a physical layer packet comprising a packet extension (PE) field. The method comprises providing the physical layer packet with at least one measurement signal for channel estimation comprised in the PE field, and transmitting the physical layer packet.

In some embodiments, the method further comprises transmitting an announcement indicating that the PE field comprises the at least one measurement signal for channel estimation.

In some embodiments, the announcement is comprised in one or more of: a broadcast signal, a beacon signal, a receiver-dedicated signal, a header field of the physical layer packet, and a medium access control header field associated with the physical layer packet.

In some embodiments, the method further comprises receiving a request for inclusion of at least one measurement signal for channel estimation in the PE field. Then, the physical layer packet may be provided with the at least one measurement signal for channel estimation comprised in the PE field in response to receiving the request.

In some embodiments, transmitting the physical layer packet comprises using a PE transmitter configuration for transmission of the PE.

In some embodiments, the PE transmitter configuration is an omni-directional transmitter configuration.

In some embodiments, the PE transmitter configuration differs from a transmitter configuration used for transmission of one or more other fields of the physical layer packet.

In some embodiments, the physical layer packet is provided with the at least one measurement signal for channel estimation comprised in the PE field only when the physical layer packet is of a specified packet type.

In some embodiments, the specified packet type comprises a single user physical layer packet.

In some embodiments, the method further comprises adjusting an average transmission power of the PE field to correspond to an average transmission power of a data field of the physical layer packet.

In some embodiments, the method further comprises controlling the at least one measurement signal for channel estimation to fulfil a spectrum mask for the data field of the physical layer packet. In some embodiments, the physical layer packet is a physical layer (PHY) protocol data unit (PPDU), or a high efficiency (HE) PPDU, or an extremely high throughput (EHT) PPDU.

In some embodiments, the measurement signal for channel estimation comprises one or more of: a long training field (LTF), a HE-LTF, and a EHT-LTF.

In some embodiments, the transmitter is configured to transmit the physical layer packet in accordance with a listen-before-talk procedure.

In some embodiments, the transmitter is configured to operate in accordance with one or more of: an IEEE 802.11ax standard, an IEEE 802.11be standard, and an IEEE 802.11bf standard.

A second aspect is a method of a receiver. The method comprises receiving a physical layer packet comprising a packet extension (PE) field, wherein at least one measurement signal for channel estimation is comprised in the PE field, and performing channel estimation based on the at least one measurement signal for channel estimation.

In some embodiments, the method further comprises receiving an announcement indicating that the PE field comprises the at least one measurement signal for channel estimation.

In some embodiments, the method further comprises transmitting a request for inclusion of at least one measurement signal for channel estimation in the PE field.

In some embodiments, the method further comprises correlating the PE field with a pre specified measurement signal, and performing channel estimation in response to a correlation peak being larger than a measurement signal detection threshold value.

In some embodiments, the method further comprises using a channel estimation result for wireless local area network (WLAN) sensing.

A third aspect is a computer program product comprising a non-transitory computer readable medium, having thereon a computer program comprising program instructions. The computer program is loadable into a data processing unit and configured to cause execution of the method according to any of the first and second aspects when the computer program is run by the data processing unit.

A fourth aspect is an apparatus for a transmitter configured to transmit a physical layer packet comprising a packet extension (PE) field. The apparatus comprises controlling circuitry configured to cause provision of at least one measurement signal for channel estimation comprised in the PE field of the physical layer packet, and transmission of the physical layer packet.

A fifth aspect is an apparatus for a receiver. The apparatus comprises controlling circuitry configured to cause reception of a physical layer packet comprising a packet extension (PE) field, wherein at least one measurement signal for channel estimation is comprised in the PE field, and performance of channel estimation based on the at least one measurement signal for channel estimation.

A sixth aspect is a wireless communication device comprising the apparatus of any of the fourth and fifth aspects. In some embodiments, any of the above aspects may additionally have features identical with or corresponding to any of the various features as explained above for any of the other aspects.

An advantage of some embodiments is that alternative approaches are provided for provision of measurement signals for channel estimation in the context of sensing.

An advantage of some embodiments is that an existing packet extension may be utilized to provide measurement signals for channel estimation in the context of sensing.

An advantage of some embodiments is that extra measurement signals for channel estimation may be provided with no (or relatively small) increase of overhead.

An advantage of some embodiments is that the efficiency of provision of measurement signals for channel estimation may be increased (e.g., in terms of energy/power and/or resource utilization).

An advantage of some embodiments is that a more flexible provision of measurement signals for channel estimation is enabled, compared to one or more other approaches for provision of measurement signals for channel estimation. An advantage of some embodiments is that a channel estimation quality (e.g., signal-to-noise ratio, SNR) may be improved, compared to one or more other approaches for provision of measurement signals for channel estimation.

An advantage of some embodiments is that mitigation (e.g., reduction) is provided for jitter of the timing of a transmitted measurement signal around a specific time where measurement signaling for channel estimation is preferable.

For example, it may be desirable for a sensing device to perform channel estimations at specific times occurring at regular time intervals. One reason may be that algorithms for WLAN sensing perform better with evenly spaced channel estimations (e.g., some algorithms can be trained using unevenly spaced channel estimations, but the classification accuracy and the false detection rates can be improved when the channel estimations are evenly spaced in time).

An advantage of some embodiments is that it is transparent for non-sensing receiving devices.

BRIEF DESCRIPTION OF THE DRAWINGS

Further objects, features and advantages will appear from the following detailed description of embodiments, with reference being made to the accompanying drawings. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the example embodiments.

Figure 1 is a flowchart illustrating example method steps according to some embodiments;

Figure 2 is a flowchart illustrating example method steps according to some embodiments;

Figure 3 is a signaling diagram illustrating example signaling according to some embodiments;

Figure 4 is a schematic drawing illustrating an example physical layer packet according to some embodiments;

Figure 5 is a schematic block diagram illustrating an example apparatus according to some embodiments;

Figure 6 is a schematic block diagram illustrating an example apparatus according to some embodiments; and Figure 7 is a schematic drawing illustrating an example computer readable medium according to some embodiments.

DETAILED DESCRIPTION

As already mentioned above, it should be emphasized that the term "comprises/comprising" (replaceable by "includes/including") when used in this specification is taken to specify the presence of stated features, integers, steps, or components, but does not preclude the presence or addition of one or more other features, integers, steps, components, or groups thereof. 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.

Embodiments of the present disclosure will be described and exemplified more fully hereinafter with reference to the accompanying drawings. The solutions disclosed herein can, however, be realized in many different forms and should not be construed as being limited to the embodiments set forth herein.

As is well known, channel estimates can be achieved by performing measurements on received signals, which are transmitted with known content. Such signals are referred to herein as measurement signals, or measurement signals for channel estimation.

Some embodiments are particularly applicable to sensing; e.g., wireless local area network (WLAN) sensing under the standardization of IEEE 802.11.

Generally, a physical layer packet (e.g., physical layer protocol data unit; PPDU) used for sensing may (or may not) also carry data. The recipient of the data may be the sensing device (STA), or may be another receiving device (STA).

An applicable scenario for some embodiments is sensing when transmitter and receiver operate in accordance with a listen-before-talk procedure. Generally, references to a listen-before-talk (LBT) procedure are meant to include any procedure where a transmitter is required to perform measurements to determine that the channel is available (e.g., idle) before starting to transmit. Examples include carrier sense multiple access with collision avoidance (CSMA/CA).

In the following, embodiments will be described where alternative approaches are provided for channel estimation measurement signals in the context of sensing. Generally, even if exemplification is made using a context for IEEE 802.11, it should be noted that some embodiments are equally applicable in other contexts, e.g., sensing within a context of Third Generation Partnership Project (3GPP) standards.

Figure 1 illustrates an example method 100 for a transmitter (e.g., transmitting device and/or non-sensing device) according to some embodiments, and Figure 2 illustrates an example (corresponding) method 200 for a receiver (e.g., receiving device and/or sensing device) according to some embodiments. Figures 1 and 2 are described in relation to each other in the following.

The method 100 is a method for a transmitter configured to transmit a physical layer packet comprising a packet extension (PE) field. Correspondingly, the method 200 is a method for a receiver configured to operate as a sensing device and to receive a physical layer packet comprising a packet extinction (PE) field.

The transmitter and receiver are typically configured to operate (e.g., transmit/receive the physical layer packet(s)) in accordance with a listen-before-talk procedure. For example, the transmitter and receiver may be configured to operate in accordance with one or more of: an IEEE 802.11ax standard, an IEEE 802.11be standard, an IEEE 802.11bf standard, or any other suitable IEEE 802.11 standard. Thus, the transmitter may be a WLAN transmitter and the receiver may be a WLAN receiver.

When the transmitter is a WLAN transmitter and/or when the receiver is a WLAN receiver, the physical layer packet may be a physical layer (PHY) protocol data unit (PPDU), a high efficiency (HE) PPDU, an extremely high throughput (EHT) PPDU, or a physical layer packet which is compatible with any of these PPDU formats; and each measurement signal for channel estimation may correspond to a long training field (LTF), a HE-LTF, or a EHT-LTF.

Typically, the packet extension (PE) field may be a field appended (or otherwise added) to a physical layer packet. For example, the PE field may have a purpose to prolong the physical layer packet without addition of data (or other useful information). Thus, the PE field may achieve that the medium is occupied for a longer period of time. This may be beneficial, for example, to cause other transmitters in an LBT context to defer transmission and/or to provide a receiver of the physical layer packet with an increased amount of time for processing of the physical layer packet.

The packet extension (PE) filed may, for example, be as defined in any suitable IEEE 802.11 standard. One example is the PE field specified for IEEE 802.11ax HE: "A PE field of duration 4ps, 8ps, 12ps, or 16ps may be present in an HE PPDU. The PE field provides additional receive processing time at the end of the HE PPDU. The PE field, if present, shall be transmitted with the same average power as the data field and shall not cause significant power leakage outside of the spectrum used by the data field. Other than that, its content is arbitrary."

In step 140, the physical layer packet is provided with at least one measurement signal for channel estimation comprised in the PE field.

The approach of using the PE field to provide measurement signal(s) for channel estimation is typically very resource efficient. For example, since a PE filed usually does not carry any useful information at all (merely some dummy content to fulfill the purpose to prolong the physical layer packet), utilizing the PE field to provide measurement signal(s) for channel estimation does not require additional communication resources to be used.

Additionally, one or more measurement signal for channel estimation may be comprised in other parts of the physical layer packet in some embodiments. For example, one or more (e.g., one, two, some, etc.) measurement signals for channel estimation may be comprised in a preamble of the physical layer packet. Alternatively or additionally, one or more (e.g., one, two, three, some, all but two, all but one, etc.) of the plurality of measurement signals for channel estimation may be comprised in a midamble of the physical layer packet. Generally, a midamble may be defined as a non-data-carrying symbol block inserted in the data-carrying part of a physical layer packet.

The approach of using the PE field to provide measurement signal(s) for channel estimation increases the probability provision of a measurement signal for channel estimation within a maximum acceptable absolute deviation from a specific time where measurement signaling for channel estimation is preferable. Alternatively or additionally, the approach of using the PE field to provide measurement signal(s) for channel estimation provides additional sample(s) for interpolation and/or extrapolation over two or more measurement signal(s) for channel estimation.

The physical layer packet is transmitted by the transmitter in step 150 and received by the receiver in step 250.

In step 260, channel estimation is performed based on the received measurement signal(s) for channel estimation. The channel estimation may be performed according to any suitable approach (e.g., according to any known approach for channel estimation).

Generally, the result of the channel estimation may be used for any suitable purpose. For example, the channel estimation result (e.g., in the form of channel state information, CSI) may be used for positioning and/or radio environment derivation (e.g., in the context of WLAN sensing). Alternatively or additionally, the channel estimation result may be used for radio calibration.

In optional step 270, the channel estimation result is used for sensing (e.g., WLAN sensing). The sensing may be performed according to any suitable approach (e.g., according to any known approach for sensing). For example, use of the channel estimation result for sensing may comprise transmitting the channel estimation result to a central processing node configured to perform WLAN sensing and/or reporting the channel estimation result to a higher layer of a protocol stack. In some embodiments, a sensing method (e.g., a WLAN sensing method) comprises causing execution of the method 200 in a plurality of sensing devices, collection of corresponding channel estimation results, and using machine learning to provide sensing results (e.g., positioning information and/or radio environment information) based on statistics of the collected channel estimation results. Such a sensing method may be performed in a sensing device (e.g., one of the receivers executing the method 200) or in a central node associated with the plurality of sensing devices.

Step 150 may comprise using a PE transmitter configuration for transmission of the PE, as illustrated by optional sub-step 152. Generally, a transmitter configuration may, for example, refer to a precoding setting used for transmission. The PE transmitter configuration may be an omni-directional transmitter configuration, or a transmitter configuration beamformed towards some specific direction(s) (e.g., direction(s) that are particularly interesting for the sensing device; i.e., direction(s) for which the sensing device would like to get more information, i.e., measurement signals), for example.

An omni-directional transmitter configuration may be achieved using any suitable approach. For example, an omni-directional transmitter configuration may comprise performing a beam sweep using several consecutive physical layer packets. Alternatively or additionally, an omni directional transmitter configuration may comprise applying cyclic shift diversity.

The PE transmitter configuration may differ from a transmitter configuration used for transmission of one or more other fields of the physical layer packet according to some embodiments. For example, other fields of the physical layer packet (e.g., a data field and/or (part of) a preamble) may be beamformed towards one or more other (non-sensing) receivers, while the PE field is not beamformed in the same way, or not beamformed at all (e.g., omni directional).

This approach may be particularly useful, for example, for a beamforming mode (e.g., in HE) where all the other fields of the PPDU - including the legacy preamble - are beamformed towards the receiver of the data field. A purpose of this beamforming mode is to allow the receiver of the data field to use the fields in the legacy preamble together with the HE-LTF to estimate the channel. Thus, the quality of the channel estimates are typically improved for the receiver of the data field. However, a sensing device (which is not in a similar direction as the receiver of the data field) may experience a deteriorated quality of the channel estimates due to the beamforming of the legacy preamble. This problem may be solved by inclusion of measurement signal(s) for channel estimation in the PE field and use of a PE transmitter configuration that differs from the transmitter configuration used for the other fields of the PPDU.

Alternatively or additionally, step 150 may comprise adjusting an average transmission power of the PE field to correspond to an average transmission power of a data field of the physical layer packet and/or controlling the at least one measurement signal for channel estimation to fulfil a spectrum mask for the data field of the physical layer packet. For example, such features may be for fulfilling standardized PE field requirements regarding transmission power and/or spectral emission (e.g., "...PE field, if present, shall be transmitted with the same average power as the data field and shall not cause significant power leakage outside of the spectrum used by the data field").

In association with transmitting the physical layer packet, the method 100 may further comprise transmitting an announcement indicating that the PE field comprises the at least one measurement signal for channel estimation, as illustrated by optional step 120. The method 200 may correspondingly comprise receiving the announcement, as illustrated by optional step 220. It should be noted that, in other embodiments, the information of the announcement may be already known to the receivers, implicitly conveyed, or announced from a central node.

Generally, the announcement may be transmitted before the physical layer packet or in combination with the physical layer packet. For example, the announcement may be comprised in one or more of: a broadcast signal, a beacon signal, a receiver-dedicated signal, a header field (e.g., in a preamble) of the physical layer packet, and a medium access control (MAC) header field associated with the physical layer packet. For example, the announcement may be comprised in a management frame, or in a signaling field in the PHY or MAC header of the PPDU.

Generally, the announcement may inform the sensing device that the PE field comprises the at least one measurement signal for channel estimation.

Additionally or alternatively, the announcement may indicate that the physical layer packet is of a specified packet type (eligible for inclusion of measurement signal(s) for channel estimation in the PE field).

In some embodiments, the announcement further informs the sensing device about the PE transmitter configuration used. For example, the announcement may be indicative of PE precoding settings (e.g., by comprising precoding setting indices corresponding to the precoding settings used).

As illustrated by optional step 210, the sensing device may transmit a request for inclusion of at least one measurement signal for channel estimation in the PE field.

In some embodiments, the request further informs the transmitter about a desired PE transmitter configuration (e.g., corresponding to direction(s) that are particularly interesting for the sensing device). For example, the request may be indicative of desired PE precoding settings (e.g., by comprising precoding setting indices corresponding to the desired PE precoding settings).

Typically, the desired PE precoding settings may be based on the channel estimations of step 260 and/or the WLAN sensing of step 270. For example, the request may be indicative of pre coding settings where the sensing device has detected channel variations. Alternatively or additionally, the request may be indicative of spatial directions where the probability of movement is considered to be high (e.g., above a threshold value). Alternatively or additionally, the request may be indicative of spatial directions where information acquired from a sensor indicates movement.

The request is received by the transmitter device as illustrated by optional step 110, and the provision of step 140 may be based on the request. For example, step 140 may comprise that the physical layer packet is provided with the at least one measurement signal for channel estimation comprised in the PE field in response to receiving the request; and possibly also using the desired precoding settings as indicated by the request.

In some embodiments, the physical layer packet is provided with the at least one measurement signal for channel estimation comprised in the PE field only when the physical layer packet is of a specified packet type (e.g., a single user physical layer packet). This is illustrated by optional step 130. When the physical layer packet is of the specified packet type (Y-path out of step 130), the method 100 proceeds to step 140 and provides the physical layer packet with the measurement signal(s) in the PE field before transmission in step 150. On the other hand, when the physical layer packet is not of the specified packet type (N-path out of step 130), the method 100 proceeds to step 150, where a physical layer packet is transmitted without any measurement signal for channel estimation included in a PE field.

The method 200 may comprise determining whether the physical layer packet is of a specified packet type, as illustrated by optional step 252. For example, the method 200 may comprise receiving (e.g., in the announcement) an indication regarding the physical layer packet being of the specified packet type, or determining that the physical layer packet is of the specified packet type according to any other suitable approach. When the physical layer packet is of the specified packet type (Y-path out of step 252), the method 200 proceeds towards the channel estimation step 260. When the physical layer packet is not of the specified packet type (N-path out of step 252), the method 200 may conclude that there is no prospect for channel estimation based on a PE field of the physical layer packet.

Whether optional step 252 is applied or not, the method 200 may comprise determining whether the physical layer packet received in step 250 comprises a PE field, as illustrated by optional step 254. For example, the method 200 may comprise receiving (e.g., in the announcement) an indication regarding the physical layer packet comprises a PE field, or determining that the physical layer packet comprises a PE field according to any other suitable approach.

When the physical layer packet comprises a PE field (Y-path out of step 254), the method 200 proceeds towards the channel estimation step 260. When the physical layer packet does not comprise a PE field (N-path out of step 254), the method 200 may conclude that there is no prospect for channel estimation based on a PE field of the physical layer packet.

Whether optional steps 252 and/or 254 is/are applied or not, the method 200 may comprise determining whether the PE field comprises any measurement signal(s) for channel estimation. For example, the method 200 may comprise receiving (e.g., in the announcement) an indication that the PE field comprises measurement signal(s) for channel estimation, or determining that the PE field comprises measurement signal(s) for channel estimation according to any other suitable approach.

As illustrated by optional step 256, the method 200 may comprise determining whether the PE field comprises any measurement signal(s) for channel estimation by correlating the PE field with a pre-specified measurement signal (e.g., an LTF) and comparing the correlation peak with a measurement signal detection threshold value (thr). The correlation peak exceeding the threshold value (Y-path out of step 256) may correspond to a determination that the PE field comprises measurement signal(s) for channel estimation. The correlation peak not exceeding the threshold value (N-path out of step 256) may correspond to a determination that the PE field does not comprise any measurement signal(s) for channel estimation. When it is determined that the PE field comprises measurement signal(s) for channel estimation, the method 200 proceeds towards the channel estimation step 260. When it is determined that the PE field comprises measurement signal(s) for channel estimation, the method 200 may conclude that there is no prospect for channel estimation based on a PE field of the physical layer packet.

When there is no prospect for channel estimation based on a PE field of the physical layer packet, the method 200 may comprise returning to step 250; possibly after processing the physical layer packet in other ways (e.g., performing channel estimation based on one or more measurement signal for channel estimation comprised in other parts of the physical layer packet).

The methods 100, 200 (or parts thereof) may be repeated for a plurality of physical layer packets, as suitable. For example, a single execution of steps 110/210 and/or 120/220 may be followed by repetitive execution of steps 140/150/250/260 for a corresponding collection (burst) of physical layer packets. Thus, the request and/or the announcement may be associated with a collection of physical layer packets.

Figure 3 schematically illustrates example signaling according to some embodiments, between a transmitter (TX; e.g., the transmitting device adapted to perform the method 100 of Figure 1) 310 and a receiver (RX; e.g., the receiving device adapted to perform the method 200 of Figure 2) 320.

The receiver 320 may or may not transmit a request 331 (compare with step 210) indicating that it is desired to get measurement signal(s) in the PE field and/or precoding settings of interest.

The transmitter 310 transmits one or more physical layer packets 334, 335, 336 (compare with step 150) accordingly; with or without transmission of a corresponding announcement 332 (compare with step 120).

It should be noted that, in various embodiments, the process may be initiated by the transmitter (e.g., by transmission of the announcement 332 or by transmission of the physical layer packet 334), or bythe receiver (e.g., by transmission ofthe request 331), or by a central node (triggering one or more of 331, 332, 334). Figure 4 schematically illustrates an example physical layer packet 400 according to some embodiments. The example physical layer packet 400 may be applicable in the context described above for the methods of Figures 1 and 2, for example.

The physical layer packet 400 has a preamble (PA) 410 and a data field 420. The data field may (or may not) be provided with one or more midambles, each of which may (or may not) comprise one or more measurement signals for channel estimation. The preamble may also comprise one or more measurement signals for channel estimation.

Figure 4 also illustrates an example content of the preamble for an IEEE 802.11 PPDU: a legacy short training field (L-STF) 412, a legacy long training field (L-LTF) 413, a legacy signal field (L- SIG) 414, a repeated legacy signal field (RL-SIG) 415, a high efficiency signal field A (HE-SIG-A) 416, a high efficiency short training field (HE-STF) 417, and two or more high efficiency long training fields (HE-LTF) 418, 419.

The physical layer packet also comprises a packet extension (PE) field 430. Embodiments presented herein suggest that the PE field may be used to carry one or more measurement signals for channel estimation (e.g., as exemplified in connection with Figures 1 and 2).

When the physical layer packet 400 is an IEEE 802.11 PPDU, a measurement signal for channel estimation may be an LTF or a HE-LTF.

Using IEEE 802.11ax as an example, the HE-LTFs of the preamble are intended to support channel estimation at the receiver. The HE PHY is based on OFDM, and a so-called guard interval (Gl) is prepended to every OFDM symbol. The HE PHY supports Gl durations of 0.8ps, 1.6ps, and 3.2ps, and HE-LTF symbol durations - excluding the Gl duration - of 3.2ps (lx), 6.4ps (2x), and 12.8ps (4x).

It is proposed according to some embodiments to generate the PE field in a HE PPDU by means of HE-LTFs having the appropriate duration (e.g., 4ps, 8ps, 12ps, or 16ps as specified for IEEE 802.11ax).

Prepending a Gl of duration 0.8ps, 1.6ps, and 3.2ps to the lx, 2x, and 4x HE-LTFs, respectively, results in the respective symbol durations 4ps, 8ps, and 16ps. Furthermore, a lx HE-LTF followed by a 2x HE-LTF has a duration of 12ps. Thus, HE-LTFs can be utilized to generate PE fields of 4ps, 8ps, 12ps, or 16ps in HE PPDUs. Figure 5 schematically illustrates an example apparatus 510 according to some embodiments. The apparatus is for a transmitter (TX; e.g., transmitting circuitry or a transmission module) - illustrated herein as part of a transceiver (TX/RX) 530 - configured to transmit a physical layer packet comprising a packet extension (PE) field.

The apparatus 510 and/or the transceiver 530 may be comprised in a transmitter device (e.g., a non-sensing device), such as a wireless communication device. An example wireless communication device is a station (STA; e.g., an access point, AP) configured for operation in accordance with IEEE 802.11.

For example, the apparatus 510 may be configured to perform, or cause performance of, one or more of the method steps described in connection with Figure 1. Any suitable feature described above, in connection with Figure 1 or otherwise, may be equally applicable for the context of Figure 5, even if all details are not repeated below.

The apparatus 510 comprises a controller (CNTR; e.g., controlling circuitry or a control module) 500.

The controller is configured to cause provision of at least one measurement signal for channel estimation comprised in the PE field of the physical layer packet (compare with step 140 of Figure 1).

To this end, the controller may be associated with (e.g., connectable, or connected, to) a PE provisioner (PROV; e.g., PE provisioning circuitry or a PE provision module) 501. The PE provisioner 501 may be adapted to provide at least one measurement signal for channel estimation comprised in the PE field of the physical layer packet.

The controller is also configured to cause transmission of the physical layer packet (compare with step 150 of Figure 1).

To this end, the controller may be associated with (e.g., connectable, or connected, to) a transmitter (e.g., transmitting circuitry or a transmission module); here illustrated as part of the transceiver 530. The transmitter may be adapted to transmit the physical layer packet. The controller may also be configured to cause reception of a request for inclusion of at least one measurement signal for channel estimation in the PE field (compare with step 110 of Figure 1).

To this end, the controller may be associated with (e.g., connectable, or connected, to) a receiver (e.g., receiving circuitry or a reception module); here illustrated as part of the transceiver 530. The receiver may be adapted to receive the request.

The controller may also be configured to cause transmission of an announcement (compare with step 120 of Figure 1).

To this end, the controller may be associated with (e.g., connectable, or connected, to) a transmitter (e.g., transmitting circuitry or a transmission module); here illustrated as part of the transceiver 530. The transmitter may be adapted to transmit the announcement.

The controller may also be configured to cause use of a PE transmitter configuration (compare with sub-step 152 of Figure 1).

To this end, the controller may be associated with (e.g., connectable, or connected, to) a configurer (CONF; e.g., configuring circuitry or a configuration module) 502. The configurer may be adapted to configure the transmitter with the PE transmitter configuration.

Figure 6 schematically illustrates an example apparatus 610 according to some embodiments. The apparatus is for a receiver (RX; e.g., receiving circuitry or a reception module) - illustrated herein as part of a transceiver (TX/RX) 630 - configured to receive a physical layer packet comprising a packet extension (PE) field.

The apparatus 610 and/or the transceiver 630 may be comprised in a receiver device (e.g., a sensing device), such as a wireless communication device. An example wireless communication device is a station (STA; e.g., a non-AP STA) configured for operation in accordance with IEEE 802.11.

For example, the apparatus 610 may be configured to perform, or cause performance of, one or more of the method steps described in connection with Figure 2. Any suitable feature described above, in connection with Figure 2 or otherwise, may be equally applicable for the context of Figure 6, even if all details are not repeated below. The apparatus 610 comprises a controller (CNTR; e.g., controlling circuitry or a control module) 600.

The controller is configured to cause reception of the physical layer packet comprising a PE field, wherein at least one measurement signal for channel estimation is comprised in the PE field (compare with step 250 of Figure 2).

To this end, the controller may be associated with (e.g., connectable, or connected, to) a receiver (e.g., receiving circuitry or a reception module); here illustrated as part of the transceiver 630. The receiver may be adapted to receive the physical layer packet.

The controller is also configured to cause performance of channel estimation based on the at least one measurement signal for channel estimation (compare with step 260 of Figure 2).

To this end, the controller may be associated with (e.g., connectable, or connected, to) a channel estimator (CE; e.g., channel estimating circuitry or a channel estimation module) 601. The channel estimator 601 may be adapted to perform channel estimation based on the measurement signal(s) for channel estimation.

The controller may also be configured to cause use of a channel estimation result for sensing (e.g., WLAN sensing). For example, causing the use of the channel estimation result for sensing may comprise transmitting the channel estimation result to a central processing node configured to perform WLAN sensing and/or reporting the channel estimation result to a higher layer of a protocol stack.

The controller may also be configured to cause transmission of a request for inclusion of at least one measurement signal for channel estimation in the PE field (compare with step 210 of Figure 2).

To this end, the controller may be associated with (e.g., connectable, or connected, to) a transmitter (e.g., transmitting circuitry or a transmission module); here illustrated as part of the transceiver 630. The transmitter may be adapted to transmit the request.

The controller may also be configured to cause reception of an announcement indicating that the PE field comprises the at least one measurement signal for channel estimation (compare with step 220 of Figure 2). To this end, the controller may be associated with (e.g., connectable, or connected, to) a receiver (e.g., receiving circuitry or a reception module); here illustrated as part of the transceiver 630. The receiver may be adapted to receive the announcement.

The controller may also be configured to cause correlation of the PE field with a pre-specified measurement signal and comparison of a correlation peak to a measurement signal detection threshold value (compare with step 256 of Figure 2).

To this end, the controller may be associated with (e.g., connectable, or connected, to) a correlator (CORR; e.g., correlating circuitry or a correlation module) 602. The correlator 602 may be adapted to perform the correlation and comparison.

The described embodiments and their equivalents may be realized in software or hardware or a combination thereof. The embodiments may be performed by general purpose circuitry. Examples of general purpose circuitry include digital signal processors (DSP), central processing units (CPU), co-processor units, field programmable gate arrays (FPGA) and other programmable hardware. Alternatively or additionally, the embodiments may be performed by specialized circuitry, such as application specific integrated circuits (ASIC). The general purpose circuitry and/or the specialized circuitry may, for example, be associated with or comprised in an apparatus such as a wireless communication device (e.g., a station - STA - such as an access point - AP - or a non-AP STA).

Embodiments may appear within an electronic apparatus (such as a wireless communication device) comprising arrangements, circuitry, and/or logic according to any of the embodiments described herein. Alternatively or additionally, an electronic apparatus (such as a wireless communication device) may be configured to perform methods according to any of the embodiments described herein.

According to some embodiments, a computer program product comprises a tangible, or non tangible, computer readable medium such as, for example a universal serial bus (USB) memory, a plug-in card, an embedded drive or a read only memory (ROM). Figure 7 illustrates an example computer readable medium in the form of a compact disc (CD) ROM 700. The computer readable medium has stored thereon a computer program comprising program instructions. The computer program is loadable into a data processor (PROC; e.g., data processing circuitry or a data processing unit) 720, which may, for example, be comprised in a wireless communication device 710. When loaded into the data processor, the computer program may be stored in a memory (MEM) 730 associated with or comprised in the data processor. According to some embodiments, the computer program may, when loaded into and run by the data processor, cause execution of method steps according to, for example, any of the methods illustrated in Figures 1-3 or otherwise described herein.

Generally, all terms used herein are to be interpreted according to their ordinary meaning in the relevant technical field, unless a different meaning is clearly given and/or is implied from the context in which it is used.

Reference has been made herein to various embodiments. However, a person skilled in the art would recognize numerous variations to the described embodiments that would still fall within the scope of the claims.

For example, the method embodiments described herein discloses example methods through steps being performed in a certain order. However, it is recognized that these sequences of events may take place in another order without departing from the scope of the claims. Furthermore, some method steps may be performed in parallel even though they have been described as being performed in sequence. Thus, the steps of any methods disclosed herein do not have to be performed in the exact order disclosed, unless a step is explicitly described as following or preceding another step and/or where it is implicit that a step must follow or precede another step.

In the same manner, it should be noted that in the description of embodiments, the partition of functional blocks into particular units is by no means intended as limiting. Contrarily, these partitions are merely examples. Functional blocks described herein as one unit may be split into two or more units. Furthermore, functional blocks described herein as being implemented as two or more units may be merged into fewer (e.g. a single) unit.

Any feature of any of the embodiments disclosed herein may be applied to any other embodiment, wherever suitable. Likewise, any advantage of any of the embodiments may apply to any other embodiments, and vice versa. Hence, it should be understood that the details of the described embodiments are merely examples brought forward for illustrative purposes, and that all variations that fall within the scope of the claims are intended to be embraced therein.

Claims

1. A method of a transmitter configured to transmit a physical layer packet comprising a packet extension - PE - field, the method comprising: providing (140) the physical layer packet with at least one measurement signal for channel estimation comprised in the PE field (430); and transmitting (150) the physical layer packet (400, 334, 335, 336).

2. The method of claim 1, further comprising transmitting (120) an announcement (332) indicating that the PE field comprises the at least one measurement signal for channel estimation.

3. The method of claim 2, wherein the announcement is comprised in one or more of: a broadcast signal, a beacon signal, a receiver-dedicated signal, a headerfield of the physical layer packet, and a medium access control header field associated with the physical layer packet.

4. The method of any of claims 1 through 3, further comprising receiving (110) a request (331) for inclusion of at least one measurement signal for channel estimation in the PE field, wherein the physical layer packet is provided with the at least one measurement signal for channel estimation comprised in the PE field in response to receiving the request.

5. The method of any of claims 1 through 4, wherein transmitting the physical layer packet comprises using (152) a PE transmitter configuration for transmission of the PE.

6. The method of claim 5, wherein the PE transmitter configuration is an omni-directional transmitter configuration.

7. The method of any of claims 5 through 6, wherein the PE transmitter configuration differs from a transmitter configuration used for transmission of one or more other fields of the physical layer packet.

8. The method of any of claims 1 through 7, wherein the physical layer packet is provided with the at least one measurement signal for channel estimation comprised in the PE field only when (130) the physical layer packet is of a specified packet type. 9. The method of claim 8, wherein the specified packet type comprises a single user physical layer packet.

10. The method of any of claims 1 through 9, further comprising one or more of: adjusting an average transmission power of the PE field to correspond to an average transmission power of a data field of the physical layer packet; and controlling the at least one measurement signal for channel estimation to fulfil a spectrum mask for the data field of the physical layer packet.

11. The method of any of claims 1 through 10, wherein the physical layer packet is a physical layer - PHY - protocol data unit - PPDU, or a high efficiency - HE - PPDU, or an extremely high throughput - EHT- PPDU.

12. The method of any of claims 1 through 11, wherein the measurement signal for channel estimation comprises one or more of: a long training field - LTF, a HE-LTF, and a EHT-LTF.

13. The method of any of claims 1 through 12, wherein the transmitter is configured to transmit the physical layer packet in accordance with a listen-before-talk procedure.

14. The method of any of claims 1 through 13, wherein the transmitter is configured to operate in accordance with one or more of: an IEEE 802.11ax standard, an IEEE 802.11be standard, and an IEEE 802.11bf standard.

15. A method of a receiver, the method comprising: receiving (250) a physical layer packet (400, 334, 335, 336) comprising a packet extension - PE - field (430), wherein at least one measurement signal for channel estimation is comprised in the PE field; and performing (260) channel estimation based on the at least one measurement signal for channel estimation.

16. The method of claim 15, further comprising receiving (220) an announcement (332) indicating that the PE field comprises the at least one measurement signal for channel estimation.

17. The method of claim 16, wherein the announcement is comprised in one or more of: a broadcast signal, a beacon signal, a receiver-dedicated signal, a headerfield of the physical layer packet, and a medium access control header field associated with the physical layer packet.

18. The method of any of claims 15 through 17, further comprising transmitting (210) a request

(331) for inclusion of at least one measurement signal for channel estimation in the PE field.

19. The method of any of claims 15 through 18, further comprising: correlating the PE field with a pre-specified measurement signal; and performing channel estimation in response to (256) a correlation peak being larger than a measurement signal detection threshold value.

20. The method of any of claims 15 through 19, further comprising using a channel estimation result for wireless local area network - WLAN - sensing.

21. A computer program product comprising a non-transitory computer readable medium

(700), having thereon a computer program comprising program instructions, the computer program being loadable into a data processing unit and configured to cause execution of the method according to any of claims 1 through 20 when the computer program is run by the data processing unit.

22. An apparatus for a transmitter configured to transmit a physical layer packet comprising a packet extension - PE - field, the apparatus comprising controlling circuitry (500) configured to cause: provision of at least one measurement signal for channel estimation comprised in the PE field of the physical layer packet; and transmission of the physical layer packet.

23. The apparatus of claim 22, wherein the controlling circuitry is further configured to cause transmission of an announcement indicating that the PE field comprises the at least one measurement signal for channel estimation.

24. The apparatus of claim 23, wherein the announcement is comprised in one or more of: a broadcast signal, a beacon signal, a receiver-dedicated signal, a headerfield of the physical layer packet, and a medium access control header field associated with the physical layer packet.

25. The apparatus of any of claims 22 through 24, wherein the controlling circuitry is further configured to cause reception of a request for inclusion of at least one measurement signal for channel estimation in the PE field, wherein the physical layer packet is provided with the at least one measurement signal for channel estimation comprised in the PE field in response to receiving the request.

26. The apparatus of any of claims 22 through 25, wherein transmission of the physical layer packet comprises use of a PE transmitter configuration for transmission of the PE.

27. The apparatus of claim 26, wherein the PE transmitter configuration is an omni-directional transmitter configuration.

28. The apparatus of any of claims 26 through 27, wherein the PE transmitter configuration differs from a transmitter configuration used for transmission of one or more other fields of the physical layer packet.

29. The apparatus of any of claims 22 through 28, wherein the physical layer packet is provided with the at least one measurement signal for channel estimation comprised in the PE field only when the physical layer packet is of a specified packet type.

30. The apparatus of claim 29, wherein the specified packet type comprises a single user physical layer packet.

31. The apparatus of any of claims 22 through 30, wherein the controlling circuitry is further configured to cause one or more of: adjustment of an average transmission power of the PE field to correspond to an average transmission power of a data field of the physical layer packet; and control of the at least one measurement signal for channel estimation to fulfil a spectrum mask for the data field of the physical layer packet.

32. The apparatus of any of claims 22 through 31, wherein the physical layer packet is a physical layer - PHY - protocol data unit - PPDU, or a high efficiency - HE - PPDU, or an extremely high throughput - EHT- PPDU.

33. The apparatus of any of claims 22 through 32, wherein the measurement signal for channel estimation comprises one or more of: a long training field - LTF, a HE-LTF, and a EHT-LTF.

34. The apparatus of any of claims 22 through 33, wherein the transmitter is configured to transmit the physical layer packet in accordance with a listen-before-talk procedure.

35. The apparatus of any of claims 22 through 34, wherein the transmitter is configured to operate in accordance with one or more of: an IEEE 802.11ax standard, an IEEE 802.11be standard, and an IEEE 802.11bf standard.

36. An apparatus for a receiver, the apparatus comprising controlling circuitry (600) configured to cause: reception of a physical layer packet comprising a packet extension - PE - field, wherein at least one measurement signal for channel estimation is comprised in the PE field; and performance of channel estimation based on the at least one measurement signal for channel estimation.

37. The apparatus of claim 36, wherein the controlling circuitry is further configured to cause reception of an announcement indicating that the PE field comprises the at least one measurement signal for channel estimation.

38. The apparatus of claim 37, wherein the announcement is comprised in one or more of: a broadcast signal, a beacon signal, a receiver-dedicated signal, a headerfield of the physical layer packet, and a medium access control header field associated with the physical layer packet.

39. The apparatus of any of claims 36 through 38, wherein the controlling circuitry is further configured to cause transmission of a request for inclusion of at least one measurement signal for channel estimation in the PE field. 40. The apparatus of any of claims 36 through 39, wherein the controlling circuitry is further configured to cause: correlation of the PE field with a pre-specified measurement signal; and performance of channel estimation in response to a correlation peak being larger than a measurement signal detection threshold value.

41. The apparatus of any of claims 36 through 40, wherein the controlling circuitry is further configured to cause use of a channel estimation result for wireless local area network - WLAN - sensing.

42. A wireless communication device comprising the apparatus of any of claims 22 through 41.