WO2022040927A1

WO2022040927A1 - Relative phase determination for frequency drift compensation

Info

Publication number: WO2022040927A1
Application number: PCT/CN2020/111122
Authority: WO
Inventors: Chaojun Xu; Gang Shen; Fei Gao; Quan Wang; Liuhai LI; Liutao Zhang; Kan LIN
Original assignee: Nokia Shanghai Bell Co., Ltd.; Nokia Solutions And Networks Oy; Nokia Technologies Oy
Priority date: 2020-08-25
Filing date: 2020-08-25
Publication date: 2022-03-03
Also published as: CN115997430A

Abstract

Embodiments of the present disclosure relate to device, method, apparatus and computer readable storage medium of relative phase determination for frequency drift compensation. The method comprises obtaining, at a first device and from a second device, a first reference signal associated with a reference antenna in a first time period and a second reference signal associated with the reference antenna in a second time period after the first time period; and determining a phase relationship between the reference antenna and at least one target antenna at least based on the first reference signal and the second reference signal, the at least one target antenna and the reference antenna being located in a same antenna array. In this way, the compensation of the frequency drift can be achieved based on the determination of the relative phase, which critical for the localization accuracy and stability in a high-accuracy BLE AoA/AoD localization solution.

Description

RELATIVE PHASE DETERMINATION FOR FREQUENCY DRIFT COMPENSATION

FIELD

Embodiments of the present disclosure generally relate to the field of telecommunication and in particular, to device, method, apparatus and computer readable storage medium of relative phase determination for frequency drift compensation.

BACKGROUND

Reliable and accurate location services are the key point for the Internet of Things (IoT) applications, such as asset tracking, intelligent manufacturing, public safety, etc. By capturing and processing the environment information, the system can improve the work efficiency and enhance the safety care by monitoring the behaviour of the staff and self-sensing of the environment. The consumers will benefit from personalized contextual information and offers, as well as new services such as public safety for a smart city.

To promote intelligence of the factory, a Location-Based Service (LBS) with low cost and high accuracy will be an important value-added service. The BLE provides a feasible technique for the indoor localization. Specifically, a direction-finding solution based on Angle of Arrival (AoA) and Angle of Departure (AoD) has been introduced, which may provide a location technique for high-accuracy localization in two or three dimensions.

SUMMARY

In general, example embodiments of the present disclosure provide a solution of relative phase determination for frequency drift compensation.

In a first aspect, there is provided a first device. The first device comprises at least one processor; and at least one memory including computer program codes; the at least one memory and the computer program codes are configured to, with the at least one processor, cause the first device at least to obtain, from a second device, a first reference signal associated with a reference antenna in a first time period and a second reference signal associated with the reference antenna in a second time period after the first time period; and determine a phase relationship between the reference antenna and at least one target antenna at least based on the first reference signal and the second reference signal, the at least one target antenna and the reference antenna being located in a same antenna array.

In a second aspect, there is provided a method. The method comprises obtaining, at a first device and from a second device, a first reference signal associated with a reference antenna in a first time period and a second reference signal associated with the reference antenna in a second time period after the first time period; and determining a phase relationship between the reference antenna and at least one target antenna at least based on the first reference signal and the second reference signal, the at least one target antenna and the reference antenna being located in a same antenna array.

In a third aspect, there is provided an apparatus comprises means for obtaining, at a first device and from a second device, a first reference signal associated with a reference antenna in a first time period and a second reference signal associated with the reference antenna in a second time period after the first time period; and means for determining a phase relationship between the reference antenna and at least one target antenna at least based on the first reference signal and the second reference signal, the at least one target antenna and the reference antenna being located in a same antenna array.

In a fourth aspect, there is provided a computer readable medium having a computer program stored thereon which, when executed by at least one processor of a device, causes the device to carry out the method according to the second aspect.

Other features and advantages of the embodiments of the present disclosure will also be apparent from the following description of specific embodiments when read in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of embodiments of the disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the disclosure are presented in the sense of examples and their advantages are explained in greater detail below, with reference to the accompanying drawings, where

FIG. 1 illustrates an example environment in which example embodiments of the present disclosure can be implemented;

FIG. 2 shows a flowchart of an example method of relative phase determination for frequency drift compensation according to some example embodiments of the present disclosure;

FIGs. 3A and 3D shows examples of the antenna switching pattern according to some example embodiments of the present disclosure;

FIG. 4A and 4B shows an example of virtual signal reconstruction and relative phase determination according to some example embodiments of the present disclosure;

FIG. 5 shows a simplified block diagram of a device that is suitable for implementing example embodiments of the present disclosure; and

FIG. 6 shows a block diagram of an example computer readable medium in accordance with some embodiments of the present disclosure.

Throughout the drawings, the same or similar reference numerals represent the same or similar element.

DETAILED DESCRIPTION

Principle of the present disclosure will now be described with reference to some example embodiments. It is to be understood that these embodiments are described only for the purpose of illustration and help those skilled in the art to understand and implement the present disclosure, without suggesting any limitation as to the scope of the disclosure. The disclosure described herein can be implemented in various manners other than the ones 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 skills in the art to which this disclosure belongs.

References in the present disclosure to “one embodiment, ” “an embodiment, ” “an example embodiment, ” and the like indicate that the embodiment described may include a particular feature, structure, or characteristic, but it is not necessary that every embodiment includes 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 example 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 shall be understood that although the terms “first” and “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 functionalities of various elements. 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” , “has” , “having” , “includes” and/or “including” , 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 combinations 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 implementations in only analog and/or digital circuitry) and

(b) combinations of hardware circuits and software, such as (as applicable) :

(i) a combination of analog and/or digital hardware circuit (s) with software/firmware and

(ii) any portions of hardware processor (s) with software (including digital signal processor (s) ) , software, and memory (ies) that work together to cause an apparatus, such as a mobile phone or server, to perform various functions) and

(c) hardware circuit (s) and or processor (s) , such as a microprocessor (s) or a portion of a microprocessor (s) , that requires software (e.g., firmware) for operation, but the software may not be present when it is not needed for operation.

This definition of circuitry applies to all uses of this term in this application, including in any claims. As a further example, as used in this application, the term circuitry also covers an implementation of merely a hardware circuit or processor (or multiple processors) or portion of a hardware circuit or processor and its (or their) accompanying software and/or firmware. The term circuitry also covers, for example 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 server, a cellular network device, or other computing or network device.

As used herein, the term “communication network” refers to a network following any suitable communication standards, such as fifth generation (5G) systems, Long Term Evolution (LTE) , LTE-Advanced (LTE-A) , Wideband Code Division Multiple Access (WCDMA) , High-Speed Packet Access (HSPA) , Narrow Band Internet of Things (NB-IoT) and so on. Furthermore, the communications between a terminal device and a network device in the communication network may be performed according to any suitable generation communication protocols, including, but not limited to, the first generation (1G) , the second generation (2G) , 2.5G, 2.75G, the third generation (3G) , the fourth generation (4G) , 4.5G, the future fifth generation (5G) new radio (NR) communication protocols, and/or any other protocols either currently known or to be developed in the future. Embodiments of the present disclosure may be applied in various communication systems. Given the rapid development in communications, there will of course also be future type communication technologies and systems with which the present disclosure may be embodied. It should not be seen as limiting the scope of the present disclosure to only the aforementioned system.

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. The network device may refer to a base station (BS) or an access point (AP) , for example, a node B (NodeB or NB) , an evolved NodeB (eNodeB or eNB) , a NR Next Generation NodeB (gNB) , a Remote Radio Unit (RRU) , a radio header (RH) , a remote radio head (RRH) , a relay, a low power node such as a femto, a pico, and so forth, depending on the applied terminology and technology. A RAN split architecture comprises a gNB-CU (Centralized unit, hosting RRC, SDAP and PDCP) controlling a plurality of gNB-DUs (Distributed unit, hosting RLC, MAC and PHY) . A relay node may correspond to DU part of the IAB node.

The term “terminal device” refers to any end device that may be capable of wireless communication. By way of example rather than limitation, a terminal device may also be referred to as a communication device, user equipment (UE) , a Subscriber Station (SS) , a Portable Subscriber Station, a Mobile Station (MS) , or an Access Terminal (AT) . The terminal device may include, but not limited to, a mobile phone, a cellular phone, a smart phone, voice over IP (VoIP) phones, wireless local loop phones, a tablet, a wearable terminal device, a personal digital assistant (PDA) , portable computers, desktop computer, image capture terminal devices such as digital cameras, gaming terminal devices, music storage and playback appliances, vehicle-mounted wireless terminal devices, wireless endpoints, mobile stations, laptop-embedded equipment (LEE) , laptop-mounted equipment (LME) , USB dongles, smart devices, wireless customer-premises equipment (CPE) , an Internet of Things (IoT) device, a watch or other wearable, a head-mounted display (HMD) , a vehicle, a drone, a medical device and applications (e.g., remote surgery) , an industrial device and applications (e.g., a robot and/or other wireless devices operating in an industrial and/or an automated processing chain contexts) , a consumer electronics device, a device operating on commercial and/or industrial wireless networks, and the like. The terminal device may also correspond to Mobile Termination (MT) part of the integrated access and backhaul (IAB) node (a.k.a. a relay node) . In the following description, the terms “terminal device” , “communication device” , “terminal” , “user equipment” and “UE” may be used interchangeably.

Although functionalities described herein can be performed, in various example embodiments, in a fixed and/or a wireless network node, in other example embodiments, functionalities may be implemented in a user equipment apparatus (such as a cell phone or tablet computer or laptop computer or desktop computer or mobile IoT device or fixed IoT device) . This user equipment apparatus can, for example, be furnished with corresponding capabilities as described in connection with the fixed and/or the wireless network node (s) , as appropriate. The user equipment apparatus may be the user equipment and/or or a control device, such as a chipset or processor, configured to control the user equipment when installed therein. Examples of such functionalities include the bootstrapping server function and/or the home subscriber server, which may be implemented in the user equipment apparatus by providing the user equipment apparatus with software configured to cause the user equipment apparatus to perform from the point of view of these functions/nodes.

FIG. 1 shows an example communication network 100 in which embodiments of the present disclosure can be implemented. As shown in FIG. 1, the communication network 100 comprises a receiving device 110 (hereafter also referred to as a first device 110) and a transmitting device 120 (hereafter also referred to as a second device 120) . The transmitting device 120 may communicate with the receiving device 110. It is to be understood that the number of network devices and terminal devices shown in FIG. 1 is given for the purpose of illustration without suggesting any limitations. The communication network 100 may include any suitable number of network devices and terminal devices. Furthermore, it is to be understood that the receiving device 110 may be referred to a terminal device and the transmitting device 120 may be referred to as a network device in some case. In some cases, the receiving device 110 may be referred to a network device while the transmitting device 120 may be referred to as a terminal device.

Depending on the communication technologies, the network 100 may be a Code Division Multiple Access (CDMA) network, a Time Division Multiple Address (TDMA) network, a Frequency Division Multiple Access (FDMA) network, an Orthogonal Frequency-Division Multiple Access (OFDMA) network, a Single Carrier-Frequency Division Multiple Access (SC-FDMA) network or any others. Communications discussed in the network 100 may conform to any suitable standards including, but not limited to, New Radio Access (NR) , Long Term Evolution (LTE) , LTE-Evolution, LTE-Advanced (LTE-A) , Wideband Code Division Multiple Access (WCDMA) , Code Division Multiple Access (CDMA) , cdma2000, and Global System for Mobile Communications (GSM) and the like. Furthermore, the communications may be performed according to any generation communication protocols either currently known or to be developed in the future. Examples of the communication protocols include, but not limited to, the first generation (1G) , the second generation (2G) , 2.5G, 2.75G, the third generation (3G) , the fourth generation (4G) , 4.5G, the fifth generation (5G) communication protocols. The techniques described herein may be used for the wireless networks and radio technologies mentioned above as well as other wireless networks and radio technologies. For clarity, certain aspects of the techniques are described below for LTE, and LTE terminology is used in much of the description below.

In the direction-finding solution, the measurement of relative phase between different antennas of the antenna array is critical for the accuracy of the AoA/AoD estimation. However, BLE has only single RF chain for low cost. Therefore, a switchable antenna array is used to send a Constant Tone Extension (CTE) signal in AoD scenario or receive a CTE signal in the AoA scenario. The CTE signal is a sinewave with the frequency of 250 KHz. In the receiving device, the phase of each antenna is measured based on the received CTE signal in different time slot.

To compute the relative phase between two specified antennas, it is necessary to estimate the phase of one antenna during the time slot when another antenna is active. For example, for a 2-antennas array, , it is usually assumed the frequency of the received CTE signal keep unchanged in one packet. Unfortunately, the assumption is not true because of the frequency drift in both the transmitting device and receiving. The frequency drift may be up to 20 KHz, which will result in average error up to ±15 degrees in the relative phase computation.

Therefore, the present disclosure proposes a solution of relative phase determination for frequency drift compensation. In this solution, a certain reference antenna can be used to transmit or receive a reference signal. By means of the reference signal, a virtual signal associated with the reference antenna can be generated. Based on the virtual signal and the target signal associated with a target antenna in an antenna array, the relative phase of the target antenna and the reference antenna can be determined. In this way, the compensation of the frequency drift can be achieved based on the determination of the relative phase, which critical for the localization accuracy and stability in a high-accuracy BLE AoA/AoD localization solution.

Principle and implementations of the present disclosure will be described in detail below with reference to FIGs. 2-6. FIG. 2 shows a flowchart of an example method 200 of relative phase determination for frequency drift compensation according to some example embodiments of the present disclosure. The method 200 can be implemented at the receiving device 110 as shown in FIG. 1. For the purpose of discussion, the method 200 will be described with reference to FIG. 1.

As shown in FIG. 2, at 210, the receiving device 110 obtains, from the transmitting device 120, a first reference signal associated with a reference antenna in a first time period and a second reference signal associated with the reference antenna in a second time period. It is to be understood that the first time period and the second time period can be continuous. For example, the second time period is after the first time period.

In some example embodiments, an antenna array can be located at the receiving device 110, and a certain antenna in the antenna array can be specified as the reference antenna. In this case, the receiving device 110 can be considered as a network device, while the transmitting device 120 can be considered as a terminal device. The transmitting device 120 may transmit the reference signal, such as CTE signal as mentioned above, to the receiving device 110. The receiving device 110 may receive the reference signal via the reference antenna. The receiving device 110 may obtain a first reference signal and a second reference signal in different sample time period. For example, the receiving device 110 may receive the first reference signal via the reference antenna in the first time period and receive the second reference signal via the reference antenna in the second time period.

In some example embodiments, an antenna array can be located at the transmitting device 120, and a certain antenna in the antenna array can be specified as the reference antenna. In this case, the receiving device 110 can be considered as a terminal device, while the transmitting device 120 can be considered as a network device. The reference signal, such as CTE signal as mentioned above, may be transmitted from the reference antenna of the transmitting device 120 to the receiving device 110. The receiving device 110 may obtain a first reference signal and a second reference signal in different sample time period. For example, the receiving device 110 may receive the first reference signal transmitted from the reference antenna in the first time period and receive the second reference signal transmitted from the reference antenna in the second time period.

Referring back to FIG. 2, at 220, the receiving device 110 determines a phase relationship between the reference antenna and at least one target antenna at least based on the first reference signal and the second reference signal. The at least one target antenna and the reference antenna may be located in a same antenna array. That is, if the reference antenna is located at the receiving device 110, the at least one target antenna is also located at the receiving device 110. If the reference antenna is located at the transmitting device 120, the at least one target antenna is also located at the transmitting device 120. The at least one target antenna may also transmit or receive CTE signal in its activated slot.

The antennas of the antenna array may be operated in different mode, which may be referred to the antenna switching pattern design. The antenna switching pattern may indicate which antenna of the antenna array, for example, which antenna of the reference antenna and at least one target antenna is to be activated in each slot for receiving or transmitting the CTE signal. One of the antennas in the antenna array is allowed to be activated in a single slot.

FIGs. 3A and 3D shows examples of the antenna switching pattern according to some example embodiments of the present disclosure.

FIG. 3A and FIG. 3B shows a Type-RAR antenna switching pattern for 3-antennas array and 7-antennas array, respectively. In Type-RAR antenna switching pattern, one in every two slots is allocated to the reference antenna, and the rest slots are evenly allocated to the target antennas.

For example, as shown in FIG. 3A, for 3-antennas array, there are a reference antenna 352 and two

target antennas

351 and 353. The switching of the antenna can be performed within the

switch slots

321, 322 and the

sample slots

331, 332. During the switching process, the reference antenna 352 and the

target antennas

351 or 353 can be activated alternately. The reference antenna 352 and the

target antennas

351 or 353 can transmit /receive CTE signal in its active time period. There is a switching slot (slots 341-348) between each active time period of the reference antenna 352 and the

target antenna

351 or 353. Since the slot for target antennas 351 or 353 (i.e. target antenna A1 or A2) can be embedded between two slots for the reference antenna 352 (i.e. reference antenna R) , an antenna unit of RAR can be formed and therefore this antenna switching pattern may be referred to as Type-RAR pattern.

For 7-antennas array as shown in FIG. 3B, there are a reference antenna 352 and 7 target antennas 351 and 353-357. The switching of the antenna can be performed within the

switch slots

321, 322 and the

sample slots

331, 332. During the switching process, the reference antenna 352 and one of the target antennas 351 and 353-357 can be activated alternately. The reference antenna 352 and the target antennas 351 and 353-357 can transmit /receive CTE signal in its active time period. There is a switching slot (slots 361-372) between each active time period of the reference antenna 352 and one of the target antennas 351 and 353-357.

FIG. 3C and FIG. 3D shows a Type-RAAR antenna switching pattern for 3-antennas array and 7-antennas array, respectively. In Type-RAAR antenna switching pattern, one in every three slots is allocated to the reference antenna and the rest slots are evenly allocated to the other antennas.

For example, as shown in FIG. 3C, for 3-antennas array, there are a reference antenna 352 and two

target antennas

351 and 353. The switching of the antenna can be performed within the

switch slots

321, 322 and the

sample slots

331, 332. The reference antenna 352 and the

target antennas

351 or 353 can transmit /receive CTE signal in its active time period. There is a switching slot (slots 373-378) between each active time period of the reference antenna 352 and the

target antenna

351 or 353. During the switching process, the slots for two target antennas 351 and 353 (i.e. target antenna A1 or A2) can be embedded between every two slots for the reference antenna 352 (i.e. reference antenna R) . An antenna unit of RAAR can be formed and therefore this antenna switching pattern may be referred to as Type-RAAR pattern.

For 7-antennas array as shown in FIG. 3D, there are a reference antenna 352 and 7 target antennas 351 and 353-357. The switching of the antenna can be performed within the

switch slots

321, 322 and the

sample slots

331, 332. The reference antenna 352 and the target antennas 351 and 353-357 can transmit /receive CTE signal in its active time period. There is a switching slot (slots 381-389) between each active time period of the reference antenna 352 and one of the target antennas 351 and 353-357. During the switching process, the slots for two of the target antennas 351 and 353-357 can be embedded between every two slots for the reference antenna 352.

FIG. 4A and 4B shows an example of virtual signal reconstruction and relative phase determination according to some example embodiments of the present disclosure. Hereinafter the determination of the relative phase between the reference antenna and the target antenna for both Type-RAR pattern and Type-RAAR pattern can be described with FIG. 4A and FIG. 4B as below.

In both the AoD scenario and the AoA scenario, the CTE signal can be sampled as a complex signal at the receiving device 110. As mentioned above, the receiving device 110 can obtain a first reference signal associated with the reference antenna in a first time period and a second reference signal associated with the reference antenna in a second time period.

For Type-RAR pattern, as shown in FIG. 4A, for example, the receiving device 110 can obtain a first reference signal 406 associated with the reference antenna in the slot 401 and a second reference signal 409 associated with the reference antenna in the slot 405.

The receiving device 110 may also obtain a target signal associated with a target antenna in a third time period after the first time period and before the second time period. For example, as shown in FIG. 4A, a target signal 408 can be obtained in a slot 403.

The receiving device 110 may generate a virtual signal associated with the reference antenna corresponding to the third time period based on the first reference signal and the second reference signal. FIG. 4A also shows the virtual signal 407 generated based on the first reference signal 406 and the second reference signal 409.

In some example embodiments, the virtual signal 407 can be generated based on the reference initial phase 412 of the virtual signal 407 and the target frequency of the target signal 408. The target frequency of the target signal 408 can be measured by the receiving device 110. The reference initial phase 412 of the virtual signal 407 can be determined at least based on the first reference frequency and reference terminal phase 411 of the first reference signal 406 and the second reference frequency and the reference initial phase 413 of the second reference signal 409.

In some example embodiments, the reference initial phase 412 of the virtual signal 407 can be determined by:

where ф represents the reference initial phase of the virtual signal, ф _R1 represents the reference terminal phase, ф _R2 represents the further reference initial phase, f _R1 represents the first reference frequency, f _R2 represents the second reference frequency, T _SW represents a switching time interval between a transmission of the target signal and a transmission of the first reference signal or the second reference signal, f _A represents the target frequency and T _A represents a duration of the third time period.

Based on the the reference initial phase 412 of the virtual signal 407 and the target frequency of the target signal 408, the virtual signal 407 can be determined as below:

ф _V (t) =2πf _At+ф (2)

The receiving device 110 may determine phase difference between the target signal 408 and the virtual signal 407 and determine the phase relationship between the reference antenna and the target antenna based on the phase difference. For example, the phase relationship can be referred to as the phase difference as the relative phase between the reference antenna and the target antenna. The relative phased ф _AR (t) can be determined by:

ф _AR (t) =ф _A (t) -ф _V (t) (3)

wherein ф _A (t) may represent the raw phase of the target signal in the slot 403.

The target signal 408 can be associated with any of

antennas

351 and 353 as shown in FIG. 3A for 3-antennas array or any of antennas 351 and 353-357 as shown in FIG. 3B for 7-antennas array. In a similar way, the receiving device 110 may determine the relative phases between the reference antenna and each of the target antennas. The receiving device 110 may also determine an average relative phase based on the determined relative phases.

For Type-RAAR pattern, as shown in FIG. 4B, for example, the receiving device 110 can obtain a first reference signal 421 associated with the reference antenna in the slot 411 and a second reference signal 426 associated with the reference antenna in the slot 417.

The receiving device 110 may also obtain a target signal associated with a target antenna in a third time period after the first time period and before the second time period and a second target signal associated with the second target antenna in a fourth time period after the first time period and before the second time period.

For example, as shown in FIG. 4B, a first target signal 423 can be obtained in a slot 413 and the second target signal 424 can be obtained in a slot 415.

The receiving device 110 may generate a first virtual signal associated with the reference antenna corresponding to the third time period and a second virtual signal associated with the reference antenna corresponding to the fourth time period based on the first reference signal and the second reference signal. FIG. 4B also shows the

virtual signals

422 and 425 generated based on the first reference signal 421 and the second reference signal 426.

In some example embodiments, the first virtual signal 422 can be generated based on the reference initial phase 415 of the virtual signal 422 and the first target frequency of the first target signal 423. The first virtual signal 425 can be generated based on the reference initial phase 416 of the virtual signal 425 and the second target frequency of the first target signal 424.

The first target frequency of the first target signal 423 and the second target frequency of the first target signal 424 can be measured by the receiving device 110. The reference initial phase 415 of the virtual signal 422 and the reference initial phase 416 of the virtual signal 425 can be determined at least based on the first reference frequency and reference terminal phase 414 of the first reference signal 421 and the second reference frequency and the reference initial phase 417 of the second reference signal 426.

In some example embodiments, the reference initial phase 415 of the virtual signal 422 can be determined by:

where ф ₁ represents the first reference initial phase of the first virtual signal, ф _R1 represents the reference terminal phase, ф _R2 represents the further reference initial phase, f _R1 represents the first reference frequency, f _R2 represents the second reference frequency, T _SW represents a time interval between a transmission of the first target signal and a transmission of the first reference signal or a time interval between a transmission of the second target signal and a transmission of the second reference signal, f _A1 represents the first target frequency, f _A2 represents the second target frequency, and T _A represents a total duration of the third time period and the fourth time period.

In some example embodiments, the reference initial phase 416 of the virtual signal 425 can be determined by:

where ф ₂ represents the second reference initial phase of the second virtual signal, ф _R1 represents the reference terminal phase, ф _R2 represents the further reference initial phase, f _R1 represents the first reference frequency, f _R2 represents the second reference frequency, T _SW represents a time interval between a transmission of the first target signal and a transmission of the first reference signal or a time interval between a transmission of the second target signal and a transmission of the second reference signal, f _A1 represents the first target frequency, f _A2 represents the second target frequency, and T _A represents a total duration of the third time period and the fourth time period.

Based on the reference initial phase 415 of the virtual signal 422 and the first target frequency of the first target signal 423, the virtual signal 422 can be determined as below:

ф _V1 (t) =2πf _A1t+ф ₁ (6)

Based on the reference initial phase 416 of the virtual signal 425 and the second target frequency of the second target signal 424, the virtual signal 425 can be determined as below:

ф _V2 (t) =2πf _A2t+ф ₂ (7)

Then the receiving device 110 may determine phase difference between the target signal 423 and the virtual signal 422, and also the phase difference between the target signal 424 and the virtual signal 425. The relative phase between the reference antenna and target antenna, which is associated with the target signal 423, can be determined based on the phase difference between the target signal 423 and the virtual signal 422. The relative phase between the reference antenna and target antenna, which is associated with the target signal 424, can be determined based on the phase difference between the target signal 424 and the virtual signal 425.

The relative phased ф _A1R (t) between the reference antenna and target antenna, which is associated with the target signal 423, can be determined by:

ф _A1R (t) =ф _A1 (t) -ф _V1 (t) (8)

The relative phased ф _A2R (t) between the reference antenna and target antenna, which is associated with the target signal 424, can be determined by:

ф _A2R (t) =ф _A2 (t) -ф _V2 (t) (9)

where ф _A1 (t) and ф _A2 (t) denote the raw phase of the received target signal in the slot 413 and slot 415, respectively.

The target signals 423 and 425 can be associated with

antennas

351 and 353 respectively as shown in FIG. 3A for 3-antennas array or any two of antennas 351 and 353-357 as shown in FIG. 3B for 7-antennas array. In a similar way, the receiving device 110 may determine the relative phases between the reference antenna and each of the target antennas. The receiving device 110 may also determine an average relative phase based on the determined relative phases.

In this way, the compensation of the frequency drift can be achieved based on the determination of the relative phase, which critical for the localization accuracy and stability in a high-accuracy BLE AoA/AoD localization solution.

The residual relative phase errors after frequency drift compensation by using the solution of the present disclosure can be listed as below.

Table 1: Residual relative phase error (Unit: degrees)

As shown in Table 1, for 3-antennas array, the residual error is reduced to less than 2 degrees, while for 7-antennas array, the residual error is reduced to less than 5 degrees. Thus, the accuracy and stability of direction finding is improved.

In some example embodiments, an apparatus capable of performing the method 200 (for example, implemented at the receiving device 110) may comprise means for performing the respective steps of the method 200. The means may be implemented in any suitable form. For example, the means may be implemented in a circuitry or software module.

In some example embodiments, the apparatus comprises means for obtaining, at a first device and from a second device, a first reference signal associated with a reference antenna in a first time period and a second reference signal associated with the reference antenna in a second time period after the first time period; and means for determining a phase relationship between the reference antenna and at least one target antenna at least based on the first reference signal and the second reference signal, the at least one target antenna and the reference antenna being located in a same antenna array. During the switching process,

FIG. 5 is a simplified block diagram of a device 500 that is suitable for implementing embodiments of the present disclosure. The device 500 may be provided to implement the communication device, for example the receiving device 110 as shown in FIG. 1. As shown, the device 500 includes one or more processors 510, one or more memories 550 coupled to the processor 510, and one or more transmitters and/or receivers (TX/RX) 540 coupled to the processor 510.

The TX/RX 540 is for bidirectional communications. The TX/RX 540 has at least one antenna to facilitate communication. The communication interface may represent any interface that is necessary for communication with other network elements.

The processor 510 may be of any type suitable to the local technical network and may include one or more of the following: general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs) and processors based on multicore processor architecture, as non-limiting examples. The device 500 may have multiple processors, such as an application specific integrated circuit chip that is slaved in time to a clock which synchronizes the main processor.

The memory 520 may include one or more non-volatile memories and one or more volatile memories. Examples of the non-volatile memories include, but are not limited to, a Read Only Memory (ROM) 524, an electrically programmable read only memory (EPROM) , a flash memory, a hard disk, a compact disc (CD) , a digital video disk (DVD) , and other magnetic storage and/or optical storage. Examples of the volatile memories include, but are not limited to, a random access memory (RAM) 522 and other volatile memories that will not last in the power-down duration.

A computer program 530 includes computer executable instructions that are executed by the associated processor 510. The program 530 may be stored in the ROM 520. The processor 510 may perform any suitable actions and processing by loading the program 530 into the RAM 520.

The embodiments of the present disclosure may be implemented by means of the program 530 so that the device 500 may perform any process of the disclosure as discussed with reference to FIGs. 2-4B. The embodiments of the present disclosure may also be implemented by hardware or by a combination of software and hardware.

In some embodiments, the program 530 may be tangibly contained in a computer readable medium which may be included in the device 500 (such as in the memory 520) or other storage devices that are accessible by the device 500. The device 500 may load the program 530 from the computer readable medium to the RAM 522 for execution. The computer readable medium may include any types of tangible non-volatile storage, such as ROM, EPROM, a flash memory, a hard disk, CD, DVD, and the like. FIG. 6 shows an example of the computer readable medium 600 in form of CD or DVD. The computer readable medium has the program 530 stored thereon.

Generally, various embodiments of the present 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 embodiments of the present disclosure are illustrated and described as block diagrams, flowcharts, or using some other pictorial representations, it is to be understood that the block, device, system, technique or method 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 includes computer-executable instructions, such as those included in program modules, being executed in a device on a target real or virtual processor, to carry out the method 200 as described above with reference to FIG. 2. Generally, program modules include routines, programs, libraries, objects, classes, components, data structures, or the like 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 a local or distributed device. In a distributed device, program modules may be located in both local and remote storage media.

Program code for carrying out 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 device, such that the program codes, when executed by the processor or controller, cause the functions/operations specified in the flowcharts and/or block diagrams to be implemented. The program code may execute entirely on a 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.

In the context of the present disclosure, the computer program codes or related data may be carried by any suitable carrier to enable the device, device or processor to perform various processes and operations as described above. Examples of the carrier include a signal, computer readable medium, and the like.

The computer readable medium may be a computer readable signal medium or a computer readable storage medium. A computer readable medium may include but not limited to an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, device, or device, or any suitable combination of the foregoing. More specific examples of the computer readable storage medium would 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 of the foregoing.

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 certain circumstances, multitasking and parallel processing may be advantageous. Likewise, while several specific implementation details are contained in the above discussions, these should not be construed as limitations on the scope of the present 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 may also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment may also be implemented in multiple embodiments separately or in any suitable sub-combination.

Although the present disclosure has been described in languages specific to structural features and/or methodological acts, it is to be understood that the present 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

A first device comprising:

at least one processor; and

at least one memory including computer program codes;

the at least one memory and the computer program codes are configured to, with the at least one processor, cause the first device at least to:

obtain, from a second device, a first reference signal associated with a reference antenna in a first time period and a second reference signal associated with the reference antenna in a second time period after the first time period; and

determine a phase relationship between the reference antenna and at least one target antenna at least based on the first reference signal and the second reference signal, the at least one target antenna and the reference antenna being located in a same antenna array.
The first device of Claim 1, wherein the first device comprises the antenna array, and wherein the first device is caused to obtain the first reference signal and the second reference signal by:

receiving the first reference signal via the reference antenna of the first device in the first time period; and

receiving the second reference signal via the reference antenna in the second time period.
The first device of Claim 1, wherein the second device comprises the antenna array, and wherein the first device is caused to obtain the first reference signal and the second reference signal by:

receiving the first reference signal transmitted from the reference antenna of second device in the first time period; and

receiving the second reference signal transmitted from the reference antenna in the second time period.
The first device of Claim 1, wherein the at least one target antenna comprises a single target antenna, and wherein the first device is caused to determine the phase relationship by:

obtaining, from the second device, a target signal associated with the target antenna in a third time period after the first time period and before the second time period;

generating, based on the first reference signal and the second reference signal, a virtual signal associated with the reference antenna corresponding to the third time period;

determining a phase difference between the target signal and the virtual signal; and

determining the phase relationship based on the phase difference.
The first device of Claim 4, wherein the first device is caused to generate the virtual signal by:

determining a reference initial phase of the virtual signal based on the first reference signal and the second reference signal;

determining a target frequency of the target signal; and

generating the virtual signal based on the reference initial phase and the target frequency.
The first device of Claim 5, wherein the first device is caused to determine the reference initial phase by:

determining a first reference frequency and a reference terminal phase of the first reference signal;

determining a second reference frequency and a further reference initial phase of the second reference signal; and

determining the reference initial phase of the virtual signal based on the first reference frequency, the reference terminal phase, the second reference frequency and the further reference initial phase.
The first device of Claim 6, wherein the reference initial phase of the virtual signal is determined by:

where ф represents the reference initial phase of the virtual signal, ф _R1 represents the reference terminal phase, ф _R2 represents the further reference initial phase, f _R1 represents the first reference frequency, f _R2 represents the second reference frequency, T _SW represents a time interval between a transmission of the target signal and a transmission of the first reference signal or the second reference signal, f _A represents the target frequency and T _A represents a duration of the third time period.
The first device of Claim 1, wherein the at least one target antenna comprises a first target antenna and a second target antenna, and wherein the first device is caused to determine the phase relationship by:

obtaining, from the second device, a first target signal associated with the first target antenna in a third time period after the first time period and before the second time period;

obtaining, from the second device, a second target signal associated with the second target antenna in a fourth time period after the first time period and before the second time period, the fourth time period being different from the third time period;

generating, based on the first reference signal and the second reference signal, a first virtual signal associated with the reference antenna corresponding to the third time period and a second virtual signal associated with the reference antenna corresponding to the fourth time period;

determining a first phase difference between the first signal and the first virtual signal and a second phase difference between the second signal and the second virtual signal; and

determining the phase relationship based on the first phase difference and the second phase difference.
The first device of Claim 8, wherein the first device is caused to generate the first virtual signal by:

determining, based on the first reference signal and the second reference signal, a first reference initial phase of the first virtual signal and a second reference initial phase of the second virtual signal;

determining a first target frequency of the first target signal and the second target frequency of the second target signal; and

generating the first virtual signal based on the first reference initial phase and the first target frequency and the second virtual signal based on the second reference initial phase and the second target frequency.
The first device of Claim 9, wherein the first device is caused to determine the first reference initial phase and the second reference initial phase by:

determining a first reference frequency and a reference terminal phase of the first reference signal;

determining a second reference frequency and a further reference initial phase of the second reference signal; and

determining the first reference initial phase and the second reference initial phase based on the first reference frequency, the reference terminal phase, the second reference frequency and the further reference initial phase.
The first device of Claim 10, wherein the first reference initial phase of the first virtual signal is determined by:

where ф ₁ represents the first reference initial phase of the first virtual signal, ф _R1 represents the reference terminal phase, ф _R2 represents the further reference initial phase, f _R1 represents the first reference frequency, f _R2 represents the second reference frequency, T _SW represents a time interval between a transmission of the first target signal and a transmission of the first reference signal or a time interval between a transmission of the second target signal and a transmission of the second reference signal, f _A1 represents the first target frequency, f _A2 represents the second target frequency, and T _A represents a total duration of the third time period and the fourth time period.
The first device of Claim 10, wherein the second reference initial phase of the second virtual signal is determined by:

where ф ₂ represents the second reference initial phase of the second virtual signal, ф _R1 represents the reference terminal phase, ф _R2 represents the further reference initial phase, f _R1 represents the first reference frequency, f _R2 represents the second reference frequency, T _SW represents a time interval between a transmission of the first target signal and a transmission of the first reference signal or a time interval between a transmission of the second target signal and a transmission of the second reference signal, f _A1 represents the first target frequency, f _A2 represents the second target frequency, and T _A represents a total duration of the third time period and the fourth time period.
The first device of Claim 1, wherein the first device comprises a receiving device and the second device comprises a transmitting device.
A method comprising:

obtaining, at a first device and from a second device, a first reference signal associated with a reference antenna in a first time period and a second reference signal associated with the reference antenna in a second time period after the first time period; and

determining a phase relationship between the reference antenna and at least one target antenna at least based on the first reference signal and the second reference signal, the at least one target antenna and the reference antenna being located in a same antenna array.
The method of Claim 14, wherein the first device comprises the antenna array, and wherein obtaining the first reference signal and the second reference signal comprises:

receiving the first reference signal via the reference antenna of the first device in the first time period; and

receiving the second reference signal via the reference antenna in the second time period.
The method of Claim 14, wherein the second device comprises the antenna array, and wherein obtaining the first reference signal and the second reference signal comprises:

receiving the first reference signal transmitted from the reference antenna of second device in the first time period; and

receiving the second reference signal transmitted from the reference antenna in the second time period.
The method of Claim 14, wherein the at least one target antenna comprises a single target antenna, and wherein determining the phase relationship comprises:

obtaining, from the second device, a target signal associated with the target antenna in a third time period after the first time period and before the second time period;

generating, based on the first reference signal and the second reference signal, a virtual signal associated with the reference antenna corresponding to the third time period;

determining a phase difference between the target signal and the virtual signal; and

determining the phase relationship based on the phase difference.
The method of Claim 17, wherein generating the virtual signal comprises:

determining a reference initial phase of the virtual signal based on the first reference signal and the second reference signal;

determining a target frequency of the target signal; and

generating the virtual signal based on the reference initial phase and the target frequency.
The method of Claim 18, wherein determining the reference initial phase comprises:

determining a first reference frequency and a reference terminal phase of the first reference signal;

determining a second reference frequency and a further reference initial phase of the second reference signal; and

determining the reference initial phase of the virtual signal based on the first reference frequency, the reference terminal phase, the second reference frequency and the further reference initial phase.
The method of Claim 19, wherein the reference initial phase of the virtual signal is determined by:

where ф represents the reference initial phase of the virtual signal, ф _R1 represents the reference terminal phase, ф _R2 represents the further reference initial phase, f _R1 represents the first reference frequency, f _R2 represents the second reference frequency, T _SW represents a time interval between a transmission of the target signal and a transmission of the first reference signal or the second reference signal, f _A represents the target frequency and T _A represents a duration of the third time period.
The method of Claim 14, wherein the at least one target antenna comprises a first target antenna and a second target antenna, and wherein determining the phase relationship comprises:

obtaining, from the second device, a first target signal associated with the first target antenna in a third time period after the first time period and before the second time period;

obtaining, from the second device, a second target signal associated with the second target antenna in a fourth time period after the first time period and before the second time period, the fourth time period being different from the third time period;

generating, based on the first reference signal and the second reference signal, a first virtual signal associated with the reference antenna corresponding to the third time period and a second virtual signal associated with the reference antenna corresponding to the fourth time period;

determining a first phase difference between the first signal and the first virtual signal and a second phase difference between the second signal and the second virtual signal; and

determining the phase relationship based on the first phase difference and the second phase difference.
The method of Claim 21, wherein generating the first virtual signal comprises:

determining, based on the first reference signal and the second reference signal, a first reference initial phase of the first virtual signal and a second reference initial phase of the second virtual signal;

determining a first target frequency of the first target signal and the second target frequency of the second target signal; and

generating the first virtual signal based on the first reference initial phase and the first target frequency and the second virtual signal based on the second reference initial phase and the second target frequency.
The method of Claim 22, wherein determining the first reference initial phase and the second reference initial phase comprises:

determining a first reference frequency and a reference terminal phase of the first reference signal;

determining a second reference frequency and a further reference initial phase of the second reference signal; and

determining the first reference initial phase and the second reference initial phase based on the first reference frequency, the reference terminal phase, the second reference frequency and the further reference initial phase.
The method of Claim 23, wherein the first reference initial phase of the first virtual signal is determined by:

where ф ₁ represents the first reference initial phase of the first virtual signal, ф _R1 represents the reference terminal phase, ф _R2 represents the further reference initial phase, f _R1 represents the first reference frequency, f _R2 represents the second reference frequency, T _SW represents a time interval between a transmission of the first target signal and a transmission of the first reference signal or a time interval between a transmission of the second target signal and a transmission of the second reference signal, f _A1 represents the first target frequency, f _A2 represents the second target frequency, and T _A represents a total duration of the third time period and the fourth time period.
The method of Claim 23, wherein the second reference initial phase of the second virtual signal is determined by:

where ф ₂ represents the second reference initial phase of the second virtual signal, ф _R1 represents the reference terminal phase, ф _R2 represents the further reference initial phase, f _R1 represents the first reference frequency, f _R2 represents the second reference frequency, T _SW represents a time interval between a transmission of the first target signal and a transmission of the first reference signal or a time interval between a transmission of the second target signal and a transmission of the second reference signal, f _A1 represents the first target frequency, f _A2 represents the second target frequency, and T _A represents a total duration of the third time period and the fourth time period.
The method of Claim 14, wherein the first device comprises a receiving device and the second device comprises a transmitting device.
An apparatus comprising:

means for obtaining, at a first device and from a second device, a first reference signal associated with a reference antenna in a first time period and a second reference signal associated with the reference antenna in a second time period after the first time period; and

means for determining a phase relationship between the reference antenna and at least one target antenna at least based on the first reference signal and the second reference signal, the at least one target antenna and the reference antenna being located in a same antenna array.
A non-transitory computer readable medium comprising program instructions for causing an apparatus to perform at least the method of any of claims 14-26.