WO2022148694A1 - Point d'extrémité de communication optique sans fil efficace en énergie - Google Patents

Point d'extrémité de communication optique sans fil efficace en énergie Download PDF

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Publication number
WO2022148694A1
WO2022148694A1 PCT/EP2021/087737 EP2021087737W WO2022148694A1 WO 2022148694 A1 WO2022148694 A1 WO 2022148694A1 EP 2021087737 W EP2021087737 W EP 2021087737W WO 2022148694 A1 WO2022148694 A1 WO 2022148694A1
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WIPO (PCT)
Prior art keywords
optical
point apparatus
wireless communication
end point
access point
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Application number
PCT/EP2021/087737
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English (en)
Inventor
Matthias Wendt
Pieter Johannes STOBBELAAR
Johan Paul Marie Gerard Linnartz
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Signify Holding B.V.
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Publication of WO2022148694A1 publication Critical patent/WO2022148694A1/fr

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/11—Arrangements specific to free-space transmission, i.e. transmission through air or vacuum
    • H04B10/114—Indoor or close-range type systems
    • H04B10/116—Visible light communication
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/11—Arrangements specific to free-space transmission, i.e. transmission through air or vacuum
    • H04B10/114—Indoor or close-range type systems
    • H04B10/1143—Bidirectional transmission
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/11—Arrangements specific to free-space transmission, i.e. transmission through air or vacuum
    • H04B10/114—Indoor or close-range type systems
    • H04B10/1149—Arrangements for indoor wireless networking of information

Definitions

  • the present invention relates to an optical wireless communication end point apparatus comprising an optical receiver configured to receive information from more than one optical connection. Specifically, the present invention relates to an energy efficient optical wireless communication end point apparatus.
  • Optical wireless communication is a type of data communication using light, e.g., visible and infrared (IR) light, to transmit information.
  • the information is normally encoded in the light emitted by a light source.
  • OWC may also be referred to as coded light, Light Fidelity (Li-Fi), visible light communication (VLC) or free-space optical communication (FSO).
  • Li-Fi Light Fidelity
  • VLC visible light communication
  • FSO free-space optical communication
  • United States patent US9813150 B1 discloses a VLC based localization system, which includes a mobile device including multiple image capturing devices, wherein an image capturing device is selected based on the device orientation and wherein the selected image capturing device captures at least one image, comprising at least one Visual Light Communication (VLC)-capable light device, decoding at least part of an identifier of the at least one VLC-capable light device, and determining the location of the mobile device based, at least in part, on the identifier of the at least one VLC-capable light device.
  • VLC Visual Light Communication
  • the visible light has a wavelength in a range of 380 nm to 740 nm; and infrared (IR) light has a wavelength in a range of 740 nm to 1.5 mm.
  • IR infrared
  • the downlink makes use of illumination light, or (for instance when the illumination light is switched off and OWC needs to remain available) IR light.
  • the uplink signal which may originate from handheld devices make use of IR light so as to avoid user disturbance.
  • a typical optical wireless communication system comprises a plurality of access points (APs), e.g., installed on a ceiling of a room.
  • An end point (EP) apparatus e.g., a mobile phone, held by a user, can move within the room, while being wirelessly connected to a wired network, via an optical wireless communication link established between the APs and the EP.
  • OWC techniques uses analogous techniques known from radio frequency (RF) communication systems, such as Multiple-Input-Multiple-Output (MIMO) and Orthogonal Frequency Division Multiplexing (OFDM), to improve efficiencies and robustness of the communication.
  • RF radio frequency
  • MIMO Multiple-Input-Multiple-Output
  • OFDM Orthogonal Frequency Division Multiplexing
  • multiple independent Optical Front-Ends (OFEs) controlled by a single PHY and MAC layer can be used as multiple “antennas” of a MIMO optical wireless communication system.
  • the multiple OFEs can be used in different ways. For example, depending on the numbers of transmitters and receivers used, it may be Single-Input-Single- Output (SISO), Single-Input-Multiple-Output (SIMO), Multiple-Input-Single-Output (MISO) and MIMO.
  • SISO Single-Input-Single- Output
  • SIMO Single-Input-Multiple-Output
  • Li-Fi is one variant of optical wireless communication, capable of transmitting data at high speeds over light.
  • a Li-Fi system is comparable to a Wi-Fi system.
  • the Wi-Fi system uses modulated RF signals to transmit information
  • the Li-Fi system uses the modulated light to transmit information.
  • Light emitting diodes (LEDs) which can be pulsed at a very high speed without noticeable effect on the lighting outputs and human eyes, are widely used by the Li-Fi systems in a variety of different applications, including wireless local area networks (WLAN), wireless personal area networks (WPAN).
  • WLAN wireless local area networks
  • WPAN wireless personal area networks
  • Li-Fi can provide a high transmission speed up to 100 Gbit/s, theoretically.
  • Li-Fi can be used in electromagnetic sensitive areas such as in aircraft cabins, hospitals and nuclear power plants, without causing electromagnetic interferences, whereas RF communications cannot be used. Since the light can be easily blocked, e.g., by walls, Li-Fi can provide a more secured connection, and is more resistant to hacking, comparing to RF based wireless communication technologies, such as Wi-Fi.
  • Chinese patent application CN112152709A discloses a mobile terminal with a plurality of LiFi receivers oriented differently.
  • the mobile terminal detects signal intensity of currently working LiFi receiver and determines whether switching is needed. When it is required it requests a signal quality measurement from the the LiFi receivers that are not working. Based on this the device determines which LiFi receiver to switch to.
  • United States patent US10855369 B2 discloses a mobile device comprising a plurality of transmitters and receivers, each configured for optical wireless communication, wherein the plurality of transmitters and/or receivers are arranged on at least three surfaces of the mobile device. Such that each of the three surfaces has a respective at least one of the transmitters and/or each of the three surfaces has a respective at least one of the receivers, wherein the mobile device includes a processor for controlling or the selecting of the at least one of the plurality of transmitters is determined by the processor using a weighting of received signals from the one or more receivers and at least one position or orientation signal received from a further component of the mobile device.
  • the link quality may be affected.
  • an optimal communication link between the EP and the APs may change, when the EP moves.
  • the SISO transmission is used, the OWC system will typically have to handle handovers. That is, the user would unavoidably experience connection interruptions.
  • MIMO transmission is used this may be ameliorated, since it is likely that at least one AP may remain connected during the motion of the EP, the user experience may be improved.
  • one well-known issue is that such data transmission would consume a lot of power.
  • the battery of the EP may need to be re-charged more frequently, which is not only inconvenient for the user, but also would reduce the battery lifecycle.
  • an optical wireless communication end point apparatus for use in an optical network system including multiple optical wireless communication access points, the optical wireless communication end point apparatus comprising an optical receiver configured to receive information from more than one possible optical connection with respective optical wireless access points via optical communication; a sensor configured to measure motion information representing a motion of the optical wireless communication end point apparatus; and a controller configured to control the optical receiver, which is configured to base on the motion information, determine a first set of optical connections of the more than one possible optical connection to be used to receive information; utilize the first set of optical connections for receiving information and not utilize any optical connection of a complement of the first set of optical connections for receiving said information, determine whether to activate a candidate access point apparatus based on the motion information, and spatial location information of the candidate access point apparatus; when it is determined to activate the candidate access point apparatus, generate an activation signal for activating the candidate access point apparatus; wherein the optical wireless communication end point apparatus further comprises a transmitter for transmitting the activation signal to any of: the candidate access point apparatus, the
  • the optical receiver may receive information from more than one possible optical wireless communication device simultaneously, e.g., via three connections with three APs provided in different spatial locations within its field of view (FoV). Such information can be separately received, e.g., by time multiplexing or frequency multiplexing.
  • Such optical wireless communication end point apparatus is suitable for separating MIMO signals overlapping both in terms of time and frequency band used. While in the RF communications, one can exploit different multipath communications from almost co-located antennas, in optical wireless communications, a spatial and/or angular separation is preferably used to ensure that the overlapping signals can be separated by MIMO means.
  • the selected first set of optical connections is a proper subset of the more than one optical connection
  • at least one of the more than one optical connection does not belong to the selected first set.
  • at least one of the more than one optical connection is not to be used for receiving information. That is, only a proper subset of all available optical connections is used for receiving information at a time, instead of energizing all the available optical connections for receiving information all the time.
  • the end point apparatus can effectively reduce its power consumption.
  • One or all of the remaining available optical connections may be deactivated. Consequently, the battery of the end point apparatus can be re-charged less frequently, and a longer battery lifecycle can be achieved.
  • Different levels of power saving may be achieved, and may involve powering down optical receiver segments, or alternatively placing the receiver in a low-power mode, or more alternatively suppressing down-stream processing of the optical receiver segment signals.
  • the controller may be configured to stop using the remainder of the optical connections not belonging to the selected subset.
  • the optical wireless communication end point apparatus may be a user device (UE), such as a laptop, a mobile phone, a tablet computer, a virtual reality (VR) or an augmented reality (AR) head set with binocular vision display, camera devices mounted on headsets, drones, or autonomous vehicles.
  • UE user device
  • VR virtual reality
  • AR augmented reality
  • the optical wireless communication end point apparatus may be an end point module, as an integrated part of a UE, or connected to the UE as a standalone apparatus.
  • the motion of the end point apparatus may be caused by a user.
  • the user lifting the end point apparatus from a table surface, walking with a handheld device in hand, or tilting for interacting with its display may cause the motion being detected by the sensor.
  • the optical receiver may be an optical angle diversity receiver (ADR).
  • ADR optical angle diversity receiver
  • the sensor may be a device for measuring orientation and/or angular velocity, such as a gyroscope.
  • a gyroscope Preferably such sensors are three-axis orientation and/or angular motion sensors.
  • the controller may be configured to determine whether to activate a candidate access point apparatus; when it is determined to activate it, to generate an activation signal for activating the candidate access point apparatus.
  • the optical wireless communication end point apparatus may further comprise a transmitter for transmitting the activation signal to: the candidate access point apparatus, an activated access point apparatus, from which the optical receiver receives information via optical communication, and a central access point controller for controlling a plurality of optical wireless communication access point apparatuses comprising the candidate access point apparatus.
  • the candidate and access point apparatus may be optical wireless communication access point apparatuses configured to communicate with the optical wireless communication end point apparatus.
  • Activating an access point apparatus may refer to powering on the access point apparatus from a power off status. Alternatively, it may refer to powering up the access point apparatus from a low power mode, such as a sleep mode, which consumes a significantly reduced energy compared to when it is fully powered on.
  • Optical wireless communication access point devices generally are connected to a back-bone network; which provides network access to the access points. The end point apparatus may communicate the activation signal directly or indirectly to the candidate access point apparatus.
  • the end point apparatus may wake up and prepare the candidate AP in advance if the candidate AP will be used soon following the motion.
  • the candidate AP may comprise a plurality of optical transceivers, each configured to receive and transmit information via optical communication.
  • the plurality of optical transceivers may be set to directions different from each other.
  • the controller may be configured to: determine a first set of optical transceivers of the candidate AP to be used to communicate with the end point apparatus; and activate the first set of optical transceivers of the candidate AP.
  • the activation signal may comprise information of the first set of optical transceivers to be activated.
  • the candidate AP comprises multiple optical transceivers, it is possible to only activate a subset of its optical transceivers, instead of energizing all the optical transceivers. This may reduce power consumption of the candidate AP.
  • the first set of optical transceivers may be determined based on e.g., the motion information, and a link quality indication of optical connections between the optical transceivers of the candidate AP and the end point apparatus.
  • the controller may be configured to determine whether to activate the candidate access point apparatus based on the motion information, and spatial location information of the candidate access point apparatus.
  • the spatial location information of an access point apparatus may be provided to the end point apparatus or estimated by the end point apparatus.
  • the end point apparatus may estimate whether the candidate AP would be used for communicating with the end point apparatus when it is moved. For example, if the candidate AP is provided in an orientation in line with a rotational direction of the end point apparatus, it may determine to activate the candidate AP.
  • the spatial location information of an access point apparatus may be an absolute location, such as a set of x, y, z values of a known coordinate system. Alternatively, it may be a relative location information in relation to a known AP, e.g., the AP currently used for communicating with the end point apparatus, or an imagined zero point, e.g., a center point of the ceiling.
  • the end point apparatus may estimate spatial location information of an access point apparatus based on previously known orientation information of the APs which have been connected to the end point apparatus, and/or assumptions that the AP is mounted on the ceiling.
  • the optical receiver may comprise a plurality of optical receiver segments, each configured to independently receive information via optical communication, wherein the plurality of optical receiver segments may be set to directions different from each other, such that each optical receiver segment may have a different field of view.
  • a first set of optical receiver segments of the plurality of optical receiver segments may be configured to respectively receive information by the first set of optical connections. Remainder of the plurality of optical receiver segments not belonging to the first set may form a second set of optical receiver segments.
  • the controller may be configured to activate the first set of optical receiver segments for receiving information; and deactivate an optical receiver segment of the second set of optical receiver segments.
  • a transimpedance amplifier is a power consuming component of the receiver path of a typical optical wireless communication end point apparatus. Consequently, energizing all available receiver paths would definitely cause a higher than necessary power consumption.
  • TIA transimpedance amplifier
  • the end point apparatus can effectively reduce its power consumption at its receiver side.
  • One or all of the remaining available optical receiver segments may be deactivated.
  • end-point devices typically receiver more data (i.e. downlink internet traffic) and only occasionally transmit data (e.g. acknowledgements), there is a substantial potential for power saving. Consequently, the battery of the end point apparatus can be re-charged less frequently, and a longer battery lifecycle can be achieved.
  • the optical receiver such as an optical angle diversity receiver (ADR) may comprise a plurality of optical receiver segments.
  • the controller may be configured to independently control the plurality of optical receiver segments.
  • Each optical receiver segment may receive information from more than one optical connection via optical communication.
  • the FoVs of the plurality of optical receivers may be non-overlapping.
  • the “different” FoVs may refer to disjoint FoVs.
  • the “different” FoVs may refer to partially overlapping FoVs. That is, even if two FoVs are partially overlapping, as long as they are not exactly the same, they are considered to be different.
  • Activating an optical receiver segment may refer to powering on the optical receiver segment from a power off status. Alternatively, it may refer to powering up the optical receiver segment from a low power mode, such as a sleep mode, which consumes a significantly reduced energy compared to when it is fully powered on.
  • a low power mode such as a sleep mode
  • Deactivating an optical receiver segment may refer to disconnecting or at least severely attenuating signals falling on that segment from contributing to a reception of signals. Deactivating an optical receiver segment may optionally even refer to interrupting its signal flow, so as to suppress further down-stream processing of the receiver segment signals.
  • Deactivating an optical receiver segment may refer to powering off the optical receiver segment from a power on status. Alternatively, it may refer to powering down the optical receiver segment to a low power mode, such as a sleep mode, which consumes a significantly reduced energy compared to when it is fully powered on.
  • a low power mode such as a sleep mode
  • the optical wireless communication end point apparatus may comprise an optical transmitter configured to transmit information by more than one possible optical connection via optical communication.
  • the controller may be configured to: determine a second set of optical connections of the more than one possible optical connection to be used to transmit information; and utilize the second set of optical connections for transmitting information.
  • the optical transmitter may comprise a plurality of optical transmitter segments, each configured to independently transmit information via optical communication.
  • the plurality of optical transmitter segments may be set to directions different from each other, such that each optical transmitter segment may have a different field of view.
  • a set of optical transmitter segments of the plurality of optical transmitter segments may be configured to respectively transmit information by the set of optical connections. Remainder of the plurality of optical transmitter segments not belonging to the set may form a second set of optical transmitter segments.
  • the controller may be configured to activate the set of optical transmitter segments for transmitting information; and deactivate an optical transmitter segment of the second set of optical transmitter segments.
  • optical receiver in the application may be analogous applicable to the optical transmitter.
  • Deactivating an optical transmitter segment may refer to refraining from driving the light source, such as a Light Emitting Diode (LED), or Vertical Cavity Surface Emitting Laser (VCSEL). Optionally a small bias/drive current may be preserved to enable fast activation of the light source. Deactivating an optical transmitter segment may alternatively refer to interrupting its signal flow to the driver, such that the drive signal no longer is modulated using the data signal.
  • LED Light Emitting Diode
  • VCSEL Vertical Cavity Surface Emitting Laser
  • Deactivating an optical transmitter segment may refer to powering off the optical transmitter segment from a power on status. Alternatively, it may refer to powering down the optical transmitter segment to a low power mode, such as a sleep mode, which consumes a significantly reduced energy compared to when it is fully powered on.
  • the motion information may comprise a rotational motion information.
  • the controller may be configured to activate an optical receiver segment of the second set of optical receiver segments.
  • the optical receiver segment to be activated may have a field of view immediately adjacent to a field of view of any of: the first set of optical receiver segments and an optical receiver segment of the plurality of optical receiver segments currently used for receiving information.
  • immediately adjacent may refer to two FoVs being neighboring to each other. These two FoVs may partly overlap with each other, or non-overlapping.
  • the end point apparatus By activating the optical receiver segments having a field of view very close to that of the optical receiver segments to be used or currently used, the end point apparatus is already prepared for accommodating small movements, e.g., a small direction change, whereby the amount of rotational motion remains under a certain threshold.
  • Determining a first set of optical receiver segments may comprise the controller being configured to determine a first field of view of an optical receiver segment of the plurality of optical receiver segments currently used for receiving information; based on further motion information indicative of a further motion of the optical wireless communication end point apparatus, subsequent to said determination, determine an optical receiver segment of the plurality of optical receiver segments, which subsequent to the further motion of the optical wireless communication end point apparatus, would have a field of view at least partly overlapping with the determined current field of view.
  • the optical receiver segment Following the motion of the end point apparatus, the optical receiver segment would have a FoV partly overlapping with the current FoV of this optical receiver segment currently used for receiving information, may likely be a candidate optical receiver segment to be used.
  • partly overlapping may refer to a 30%, 50%, preferably 70% or more preferably 90% overlapping of two FoVs.
  • the relationship between the rotational motion may be used to more directly control the selection of the segments.
  • Knowledge of a determined first set and of the detected motion may be combined and used to determine the new orientation of the end point apparatus and thus a new set of optical receiver segments to use.
  • Rotational sensor input may be further advantageously combined with other modalities, such as a three-axis accelerometer. This improves the determination of the orientation of the end point device, as it measures the gravitational force pulling down.
  • the controller is configured to determine a relationship of the motion information and the candidate access point apparatus determined to be activated; utilize the relationship to facilitate determination of a next candidate access point apparatus.
  • the end point apparatus e.g. a mobile phone
  • the end point apparatus may build a relationship of this specific “tilting movement” and the candidate AP.
  • the user tilts the mobile phone once again, it may recognize the “tilting movement”, and use the known relationship to facilitate determination of whether to activate the same or a different candidate AP. This may provide a faster identification and preparation of the candidate AP.
  • the controller may be configured to determine whether to activate the candidate access point apparatus based on a link quality indication of an optical connection between the optical receiver and the candidate access point apparatus; wherein when the link quality indication meets a predetermined criterion, it is determined to activate the candidate access point apparatus.
  • the link quality indication may comprise at least one of: a signal-noise-ratio, SNR, an error vector magnitude, EVM, a subcarrier SNR, a subcarrier Quadrature Amplitude Modulation, QAM, constellation size, a link quality indicator, LQI, a Quality of Service,
  • an optical wireless communication end point apparatus for use in an optical network system including multiple optical wireless communication access points, the optical wireless communication end point apparatus comprising: an optical transceiver configured to transmit and receive information from more than one possible optical connection with respective optical wireless access points via optical communication; a sensor configured to measure motion information representing a motion of the optical wireless communication end point apparatus; and a controller configured to control the optical transceiver.
  • the controller is configured to: based on the motion information, determine a third set of optical connections of the more than one possible optical connection to be used to transmit information, wherein the third set of optical connections is a proper subset of the more than one possible optical connection; and utilize the third set of optical connections for transmitting information; not utilize any optical connection of a complement of the third set of optical connections for transmitting said information, determine whether to activate a candidate access point apparatus based on the motion information, and spatial location information of the candidate access point apparatus; when it is determined to activate the candidate access point apparatus, generate an activation signal for activating the candidate access point apparatus; wherein the optical wireless communication end point apparatus further comprises a transmitter for transmitting the activation signal to any of: the candidate access point apparatus, an activated access point apparatus, and a central access point controller for controlling a plurality of optical wireless communication access point apparatuses comprising the candidate access point apparatus.
  • the optical transceiver may comprise a plurality of optical transmitter segments, each configured to independently transmit information via optical communication, wherein the plurality of optical transmitter segments is set to directions different from each other, such that each optical transmitter segment has a different field of view.
  • a third set of optical transmitter segments of the plurality of optical transmitter segments may be configured to respectively transmit information by the third set of optical connections. Remainder of the plurality of optical transmitter segments not belonging to the third set forms a fourth set of optical transmitter segments.
  • the controller may be configured to: activate the third set of optical transmitter segments for transmitting information; and deactivate an optical transmitter segment of the fourth set of optical transmitter segments.
  • One component of the power consumption of any end point apparatus resides in its transmitter path, i.e. a path that outputs optical signals carrying information.
  • LEDs/VCSELs are power consuming component of the transmitter path of a typical optical wireless communication end point apparatus. Consequently, energizing all available transmitter connections/transmitter segments would definitely cause a high power consumption.
  • the end point apparatus can effectively reduce its power consumption at its transmitter side.
  • One or all of the remaining available optical connections/transmitter segments may be deactivated. Consequently, the battery of the end point apparatus can be re-charged less frequently, and a longer battery lifecycle can be achieved.
  • the end point apparatus can achieve power saving in its transmitter side, power saving may focus on receiver-side only, transmitter-side only or both. Different levels of power saving in transmission may be achieved, and may involve powering down optical transmitter segments, or alternatively placing the transmitter in a low- power mode, or more alternatively suppressing up-stream processing of the optical transmitter segment signals.
  • the end point apparatus may use the receiver side information and motion information to determine which optical connections/transmitter segments of its transmitter side to use.
  • the optical transceiver may comprise a plurality of optical transmitter segments and a plurality of optical receiver segments.
  • optical transmitter and optical receiver segments of the optical transceiver may have a one to one corresponding relationship. That is, each pair of receiver and transmitter segment has a substantially same FoV (e.g., two FoVs overlapping at least 90% may be considered to be substantially the same). Consequently, once a subset of optical receiver segments is determined to be activated, its corresponding subset of optical transmitter segments having the same FoVs can be determined to be activated, or vice versa. Once one optical receiver segment is determined to be deactivated, its corresponding optical transmitter segment having the same FoV can be determined to be deactivated, or vice versa.
  • FoV e.g., two FoVs overlapping at least 90% may be considered to be substantially the same
  • optical transmitter and optical receiver segments of the optical transceiver may not have a strict one to one corresponding relationship.
  • the number of the transmitter segments and the number of receiver segments may be different. That is, for any receiver segment, there may be no transmitter segment having a substantially same FoV. Rather, the FoVs of a few transmitter segments combined together may overlap a substantially part of receiver segment’s FoV. Consequently, once the optical receiver segment is determined to be activated, the few optical transmitter segments having the combined FoV overlapped with its FoV may be determined to be activated, or vice versa.
  • the second aspect allows the use of both receiver side information as regards the most suitable receivers for communication and motion information to be used for determining the third set.
  • the second aspect may provide substantial power saving even when without selectively utilizing receiver segments.
  • the first and second aspects of the invention may be combined, such that the end point apparatus may save energy in both the receiver side and the transmitter side. Consequently, a further improved energy saving effect can be achieved.
  • a central optical wireless communication access point controller comprising a transceiver unit configured to receive an activation signal from the optical wireless communication end point apparatus of the first aspect of the invention; a control unit configured to independently control a plurality of optical wireless communication access point apparatuses.
  • the activation signal comprises information of a candidate optical wireless communication access point apparatus to be activated for communicating with the optical wireless communication end point apparatus.
  • the plurality of optical wireless communication access point apparatuses comprises the candidate optical wireless communication access point apparatus.
  • the control unit is configured to: activate the candidate optical wireless communication access point apparatus based on the information of the activation signal.
  • a central controller may be used for driving and controlling a plurality of distributed optical wireless communication access point apparatuses.
  • the APs may emit beacons to the end point apparatus from time to time. This may allow the end point apparatus to compare link qualities of the connections, and potentially change the links, e.g., MIMO channels used for communication.
  • the central optical wireless communication access point controller may be co located with a Li-Fi AP.
  • an optical wireless communication system comprising the optical wireless communication end point apparatus of the first aspect of the invention, an optical wireless communication access point apparatus, and optionally the central optical wireless communication access point controller of the second aspect of the invention.
  • the optical wireless communication system may be a Li-Fi system.
  • an optical wireless communication method of an optical wireless communication end point apparatus comprising: an optical receiver configured to receive information from more than one optical connection via optical communication; a sensor configured to measure motion information representing a motion of the optical wireless communication end point apparatus; and a controller configured to control the optical receiver; the method comprising: based on the motion information, determining a first set of optical connections of the more than one optical connection to be used to receive information; and utilizing the first set of optical connections for receiving information.
  • an optical wireless communication method of an optical wireless communication end point apparatus comprising: an optical transceiver configured to transmit and receive information from more than one optical connection via optical communication; a sensor configured to measure motion information representing a motion of the optical wireless communication end point apparatus; and a controller configured to control the optical transceiver.
  • the method comprises: based on the motion information, determining a third set of optical connections of the more than one optical connection to be used to transmit information, wherein the third set of optical connections is a proper subset of the more than one optical connection; utilizing the third set of optical connections for transmitting information; and not utilizing any optical connection of a complement of the third set of optical connections for transmitting said information.
  • Figure 1 A shows a schematic illustration of an example of an optical wireless communication end point apparatus.
  • Figure IB shows a schematic illustration of an example of a central optical wireless communication access point controller.
  • Figure 2 shows a schematic illustration of an example of an optical receiver of an optical wireless communication end point apparatus.
  • Figure 3 schematically shows an example environment comprising an optical wireless communication system.
  • Figure 4 shows an example of using an optical wireless communication access point apparatus.
  • Figure 5 shows an example of using an optical wireless communication end point apparatus.
  • Fig. 1 A shows a schematic illustration of an example of an optical wireless communication end point apparatus.
  • the end point apparatus 1 comprises an optical receiver 11, configured to receive information from more than one optical connection via optical communication.
  • the optical receiver 11 may be a Li-Fi receiver.
  • the end point apparatus 1 may be a Li-Fi communication end point apparatus.
  • the end point apparatus 1 comprises a controller 12 configured to control the optical receiver 11.
  • the controller 12 may include a processor, such as a central processing unit (CPU), microcontroller, or microprocessor.
  • the end point apparatus 1 may comprise an optical transmitter 13 for transmitting information via optical communication.
  • the optical transmitter 13 may be a Li- Fi transmitter.
  • the optical transmitter 13 may be used for transmitting information via optical communication to other optical communication devices, such as APs.
  • the optical transmitter 13 may be used for transmitting information via optical communication to other optical communication devices, such as APs.
  • 13 may be used for transmitting information, e.g., an activation signal for activating a candidate access point apparatus.
  • the end point apparatus 1 may comprise an optical transceiver, configured to transmit and receive information from more than one optical connection via optical communication.
  • the optical transceiver may comprise the optical receiver 11 and the optical transmitter 13.
  • the end point apparatus 1 may comprise a memory unit 14.
  • the memory unit 14 may be any type of memory.
  • the memory unit 14 may be a separate module, as shown in fig. 1 A, or an integrated part of the controller 12.
  • the memory unit 14 may store information, such as operation parameters of the end point apparatus 1, and/or parameters of the optical receivers 11 and of the optical transmitter 13.
  • the memory unit 14 may be one or more of a buffer, a flash memory, a hard drive, a removable medium, a volatile memory, a non-volatile memory, a random access memory (RAM), or another suitable device.
  • the memory unit 14 may include a non-volatile memory for long term data storage and a volatile memory that functions as system memory for the end point apparatus 1.
  • the memory unit 14 may exchange data with the controller 12 over a data bus. Accompanying control lines and an address bus between the memory unit 14 and the controller 12 also may be present.
  • Functions and operations of the end point apparatus 1 may be embodied in the form of executable logic routines (e.g., lines of code, software programs, etc.) that are stored on a non-transitory computer readable medium (e.g., the memory) of the end point apparatus 1 and are executed by the controller 12.
  • the functions and operations of the end point apparatus 1 may be a stand-alone software application or form a part of a software application that carries out additional tasks related to the end point apparatus 1.
  • the described functions and operations may be considered a method that the corresponding device is configured to carry out.
  • the described functions and operations may be implemented in software, such functionality may as well be carried out via dedicated hardware or firmware, or some combination of hardware, firmware and/or software.
  • the end point apparatus 1 comprises a sensor 15 for measuring motion information representing a motion of the end point apparatus 1. The measured motion information may be sent to the controller 12 for processing.
  • the sensor 15 may be a gyrator or an accelerometer, which can detect motion of the end point apparatus 1.
  • the central AP controller 3 may be a device for controlling a plurality of access point apparatuses.
  • a room may be provided with a plurality of access point apparatuses and one central AP controller for controlling these access point apparatuses.
  • the central AP controller 3 may activate or deactivate any of plurality of access point apparatuses.
  • the central AP controller 3 comprises a control unit 32 configured to independently control a plurality of optical wireless communication access point apparatuses.
  • the central AP controller 3 may be connected to the APs by means of a wired backbone network, which is used to relay data amongst the central AP controller, the APs and other network devices connected to the backbone network or internet.
  • the central AP controller 3 further comprises a transceiver unit 31, configured to receive and transmit signals from other devices.
  • the central AP controller 3 may transmit signals by the transceiver unit 31 to an access point apparatus, e.g., for activating or deactivating the access point apparatus.
  • the transceiver unit 31 may communicate with the end point apparatus 1, e.g., receiving an activation signal from the end point apparatus 1 for activating any candidate access point apparatus.
  • Fig. 2 shows a schematic illustration of an example of an optical receiver of an optical wireless communication end point apparatus.
  • an artificial coordinate system with three axes X-Y-Z is introduced for illustration.
  • the optical receiver 11 of fig. 2 comprises a plurality of optical receiver segments. Each optical receiver segment is configured to independently receive information via optical communication. The plurality of optical receiver segments is set to directions different from each other, such that each optical receiver segment has a different field of view. Each receiver segment may be a photo detector. Each optical receiver segments may be configured to receive information from more than one optical connection.
  • the optical receiver 11 of fig. 2 comprises a mounting plate 24, which is parallel to the axes X and Y, and perpendicular to the axis Z, and three layers of optical receiver segments 21, 22 and 23.
  • the first layer 21 comprises only one optical receiver segment 210 facing a direction substantially perpendicular to the mounting plate 24.
  • the optical receiver segment 210 has a field of view (FoV) being substantially parallel to the axis Z, for receiving information from other optical communication devices provided within its FoV.
  • FoV field of view
  • the second layer 22 comprises multiple optical receiver segments 220, 221,
  • Each of the optical receiver segments 220, 221, 222, ... can receive signals from optical communication devices provided within its FoV.
  • the optical receiver segments 220, 221, 222, ... may be set angularly evenly around the axis Z, as shown in fig. 2, such that each of the FoVs has a same spatial volume.
  • the FoVs may be non-overlapping or overlapping. When the FOVs are overlapping, communication blind spots may be effectively avoided.
  • the third layer 23 comprises fewer optical receiver segments 230, 231, comparing to the second layer 22. These optical receiver segments 230, 231, ... , are set to different directions (having different FoVs).
  • the segmented optical receiver presented here has all segments located spatially adjacent on a convex surface, the segments may also be house inside a device along a concave surface or may be placed internal to the apparatus with suitable optics for guaranteeing the different fields-of-view.
  • the respective optical receiver segments may be located on different sides of the end point apparatus.
  • the different segments could be located on each of the respective planes of the box facing in different directions.
  • the devices in question has beveled or rounded edges these may be advantageously used to house the optical receiver segments so as to get further angular diversity.
  • the segmented optical receiver 11 can be used to simultaneously receive signals from multiple optical communication devices provided within a same or different FoVs of its multiple optical receiver segments.
  • these optical receiver segments can be activated for receiving information, and at least one of remainder of the optical receiver segments not to be used can be deactivated, for reducing power consumption.
  • the segmented optical receiver 11 has a hemispherical shape, most optical connections would be expected to be made by the optical receiver segments of the second layer 22. Consequently, a larger number of optical receiver segments are provided in the second layer 22, than in the first and third layer 21 and 23.
  • the segmented optical receiver 11 may have different shapes.
  • the shape of the segmented optical receiver 11 and the exact arrangement of its optical receiver segments may depend on specific usages.
  • the optical transmitter 13 may comprise a plurality of optical transmitters having respective transmitting FoVs similar to those of the receiving FoVs of the multiple optical receiver elements of the optical receiver 11 shown in Fig. 2.
  • the features of the optical receiver 11 are analogously applicable to the optical transmitter 13.
  • the optical transceiver may comprise a plurality of optical transceivers having respective transceiver FoVs similar to those of the receiving FoVs of the multiple optical receiver elements as the optical receiver 11 shown in Fig. 2, each of the optical transceiver may be configured to transmit and receive information.
  • the features of the optical receiver 11 are analogously applicable to the optical transceiver.
  • the optical transceiver may comprise a separate optical receiver 11 comprising a plurality of optical receiver segments as shown in fig. 2 and a separate optical transmitter 13 comprising a plurality of optical transmitter segments.
  • Fig. 3 is a schematic example environment comprising an optical wireless communication system.
  • the optical wireless communication system of fig. 3 comprises a plurality of optical wireless communication access point apparatuses (APs) 2, and one central optical wireless communication access point controller 3, mounted on a ceiling of a room.
  • APs optical wireless communication access point apparatuses
  • central optical wireless communication access point controller 3 mounted on a ceiling of a room.
  • the optical wireless communication AP 2 is an optical networking hardware device allowing other optical wireless communication devices to connect to a wired network, e.g., a wired local area network. Such APs can provide optical wireless connections using wireless technology, e.g., Li-Fi, for other devices to connect to the wired network. Such APs 2 can simultaneously support connections of multiple optical wireless end point devices.
  • the central AP controller 3 is a device for controlling the plurality of APs 2.
  • first optical wireless communication end point apparatus 1 e.g., a mobile phone.
  • second optical wireless communication end point apparatus 4 e.g., a laptop, being stably placed on a table.
  • the relative position of the end point apparatus 1, 4 and the APs 2 is not static since the end point apparatus 1, 4 may be moved, e.g., by the user 5.
  • a current optical communication link used for receiving information may no longer be available after the end point apparatus 1, 4 has been moved to a new position or a new angle, as an object, e.g., the user 5, may block a direct light of sight between the end point apparatus 1, 4 and the AP 2. Instead, a new optical communication link may be established for receiving information after the end point apparatus 1, 4 has been moved.
  • the motion of the end point apparatus 1 can be monitored and detected by the sensor 15 of the end point apparatus 1. Based on the detected motion information, the controller 12 of the end point apparatus 1 is configured to determine a first set of optical connections to be used to receive information; and utilize the determined set of optical connections for receiving information.
  • the optical receiver 11 comprises a plurality of optical receiver segments as shown in Fig. 2, the motion information can be used to determine and utilize a subset of the optical receiver segments for receiving information.
  • the end point apparatus 1 may comprise an optical transmitter 13 configured to transmit information by more than one optical connection.
  • the controller 12 may be configured to determine a second set of optical connections of the more than one optical connection to be used to transmit information; and utilize the second set of optical connections for transmitting information.
  • the optical transmitter 13 may comprise a plurality of optical transmitter segments, each configured to independently transmit information via optical communication.
  • the plurality of optical transmitter segments may be set to directions different from each other, such that each optical transmitter segment has a different field of view.
  • the controller 12 may determine and utilize a subset of the optical transmitter segments for transmitting information. Only using a subset of all the connections and/or all the optical transmitter segments may further reduce power consumption of the end point apparatus 1.
  • the end point apparatus may save energy at its receiver side or its transmitter side, or at both of its receiver and transmitter side.
  • Determination of the first subset of connections to be used for receiving information, and the third subset of connections to be used for transmitting information may be performed individually. For example, determination of the subset of optical connections and/or the subset of optical transmitter segments for transmitting information may be based on the motion information, in a similar manner to the determination of the subset of optical connections and/or the subset of optical receiver segments for receiving information, respectively.
  • the other subset may be determined based on the already determined subset.
  • the optical connection may be a bi-directional link. That is, if the bi-directional link is determined to be used for receiving information, it can also be determined to be used for transmitting information. In other words, if a connection is considered to be good in one direction (receiving), it is considered to be good in another direction (transmitting).
  • the plurality of optical receiver segments and the plurality of transmitter segments may have a corresponding relationship, such that each pair of receiver and transmitter has a substantially same FoV (e.g., two FoVs overlapping at least 90% may be considered to be substantially the same).
  • FoV e.g., two FoVs overlapping at least 90% may be considered to be substantially the same.
  • the neighboring optical receiver/transmitter segment which has a field of view immediately adjacent to a field of view of one optical receiver/transmitter segment currently used, and/or immediately adjacent to a field of view of any of the selected subset of optical receiver/transmitter segments to be used, may be energized.
  • the end point apparatus 1 has been prepared for any relatively small motions, e.g., a small orientation change of the end point apparatus 1.
  • the immediately adjacent FoVs may be non-overlapping or overlapping.
  • the end point apparatus 1, 4 may determine a field of view of an AP 2 currently used for communicating with the end point apparatus 1, 4.
  • the controller 12 may select an optical receiver/transmitter segment, which following the motion of the end point apparatus 1, 4, would have a field of view facing or at least partly facing the determined current field of view of the AP 2, to belong to the subset of optical receiver/transmitter segments to be used.
  • the end point apparatus 1, 4 may determine a field of view of an optical receiver/transmitter segment currently used. Based on the motion information, the controller 12 may determine an optical receiver segment/transmitter, which following the motion of the end point apparatus 1, 4, would have a field of view at least partly overlapping with the determined current field of view of the currently used segment belonging to the subset of optical receiver/transmitter segments to be used.
  • the motion information indicates that the end point apparatus 1, 4 is in a stable status, e.g., when the acceleration magnitude and the moving speed are both zero, it is determined that the end point apparatus 1, 4 is not moving and is not about to move.
  • the optical connections and/or the optical receiver/transmitter segments currently used for communication may continue being used. At least one of the connections, and/or the optical receiver/transmitter segments not currently used may be deactivated for saving power.
  • Figs 4 and 5 illustrate two different examples of using an optical wireless communication access point apparatus.
  • a floorplan is divided into 18 portions, i.e. portion PI, P2,
  • end point apparatus 1 can communicate with at least one AP, no matter in which portion of the floorplan the user 5 holding the end point apparatus 1 stands.
  • the user 5 holding the end point apparatus 1 is at a first position within the portion P5. Then, the user 5 starts moving linearly through the portion P8, and finally stops at the second position within the portion PI 1.
  • the artificial coordinate system with three axes X-Y-Z is introduced for illustration, wherein the axes X and Y are parallel to a floor and the axis Z is perpendicular to the axes X and Y.
  • the user 5 holding the end point apparatus 4 is turning around an axis being parallel to the Z axis, which causes the end point apparatus 4 and its segmented optical receiver 11 to rotate following a rotational direction around the axis Z.
  • the optical wireless communication system in fig. 5 may only comprise the end point apparatus 4, and the APs 2a, 2b. That is, the existence of the central AP controller 3 is optional. When no central AP controller is provided, and the coverage areas of optical wireless access point apparatuses overlap, the respective APs may need to perform the functions normally provided by the central controller, such as interference handling and horizontal handover of end-devices amongst the APs.
  • the system may be designed to have APs with non-overlapping coverage areas, which in turn may result in more and longer link establishment times.
  • the linear motion of the end point apparatus normally corresponds to a linear physical displacement of the end point apparatus 1, e.g., from the portion P5 to PI 1 as shown in fig. 4.
  • Such movement has a large time-constant due to that the actual displacement takes time.
  • it is less urgent to determine the next optical connections and/or the receiver/transmitter segments to be used along the motion.
  • the motion since the motion is linear, it may be easier to estimate how the movement would influence the next optical connections, the next receiver/transmitter segments, and the next APs to be used. For example, it is likely that one of the receiver/transmitter segments and/or AP immediately adjacent to the currently used ones are to be used along the motion.
  • the rotational motion of the end point apparatus normally corresponds to a fast rotation of the apparatus, as shown in fig. 5.
  • such movement has a much shorter time-constant due to its quick movement.
  • it is more urgent to determine the next optical connections and/or receiver/transmitter segments to be used along the motion.
  • the motion since the motion is rotational, it may be more difficult to estimate how the movement would influence the next optical connections, the next receiver/transmitter segments, and the next APs to be used.
  • the receiver segments and/or AP not immediately adjacent to the currently used ones are to be used following the motion.
  • the rotational and linear motion of the end point apparatus may need to be handled differently, especially when there is a large number of available connections and/or a large number of optical receiver/transmitter segments to select from.
  • the invention is aimed to effectively reduce the energy consumption of the end point apparatus 1 when the motion is rotational or is a combination of a rotational and linear motion, which is more complicated than the situation when the motion is linear.
  • the invention can be used for reducing the energy consumption of the end point apparatus when the motion is linear.
  • the motion information may comprise any of: an acceleration/deceleration magnitude, an acceleration/deceleration direction, a magnitude of moving speed, and a moving direction.
  • a first optical receiver segment of the segmented optical receiver 11 is currently used for receiving information from the AP 2a.
  • the first optical receiver segment has a field of view (FoV) facing the AP 2a. All other optical receiver segments of the segmented optical receiver 11 are deactivated.
  • a first optical transmitter segment may have a FoV facing the AP 2a.
  • the user 5 starts turning around and the motion information, e.g., a rotational acceleration and/or an angle speed around the axis Z, of the end point apparatus 4 is detected by the sensor 15 (not shown) of the end point apparatus 4.
  • the controller 12 may determine that the end point apparatus 4 will turn around, such that a second optical receiver segment will have the FoV facing the AP 2a, instead of the first optical receiver segment.
  • the second optical receiver segment may be activated based on the motion information.
  • a second optical transmitter segment of the end point apparatus 1 having a substantially same FOV as the second optical receiver segment may be determined to be activated to be used for transmitting information to the AP 2a.
  • the controller 12 may determine that the end point apparatus 4 may stop turning, such that the second optical receiver segment would have the FoV facing the AP 2a and the first optical receiver segment has been turned away and would not face the AP 2a anymore.
  • the first optical receiver segment may be deactivated. Consequently, one optical transmitter segment having a substantially same FOV as the first optical receiver segment may be determined to be deactivated for saving power.
  • the controller 12 may determine that the second optical transmitter segment would have the FoV facing the AP 2a and the first optical transmitter segment has been turned away and would not face the AP 2a anymore.
  • the first optical transmitter segment may be deactivated for saving power.
  • the end point apparatus 4 may be prepared to activate a subset of its optical receiver/transmitter segments facing and about to face the AP 2a for receiving/transmitting information, instead of energizing all the segments.
  • a seamless connection having a good QoS can be secured even if the user 5 holding the end point apparatus 4 rotates.
  • Those optical receiver/transmitter segments no longer used may be deactivated, such that energy efficiency of the end point apparatus 4 can be improved.
  • the end point apparatus 4 may identify a candidate AP 2b that could be used for communicating with the end point apparatus 4 when it moves. For example, the end point apparatus 4 can be used to wake up (activate) the candidate AP 2b to be used and/or deactivate the AP not to be used.
  • the APs including the AP 2a currently communicating with the end point apparatus 4 and the candidate AP 2b, are optical wireless communication access point apparatuses configured to communicate with optical wireless communication end point apparatuses.
  • the controller 12 may be configured to determine whether to activate the candidate AP 2b. If yes, an activation signal for activating the candidate AP 2b may be generated.
  • the end point apparatus 4 may further comprise a transmitter for transmitting the activation signal.
  • the transmitter may be the optical transmitter 13.
  • the activation signal may be directly transmitted to the candidate AP 2b for activating it.
  • the activation signal may be transmitted to the central AP controller 3.
  • the AP center controller 3 may activate the candidate AP 2b according to the activation signal.
  • the activation signal may be transmitted to the AP 2a currently communicating with the end point apparatus 4.
  • the AP 2a may further transmit the activation signal directly to the candidate AP 2b, or via the central AP controller 3.
  • the controller 12 may be configured to determine whether to activate a candidate AP 2b based on the motion information of the end point apparatus 4, and spatial location information of the candidate AP 2b.
  • the end point apparatus 4 may estimate a series of candidate APs to be used following the motion of the end point apparatus.
  • the spatial location information of the candidate AP 2b may be an absolute location.
  • the absolute location of the candidate AP and the motion information can be used to determine whether the candidate AP 2b should be activated.
  • the spatial location information of the candidate AP 2b may be a relative location information in relation to a reference, e.g., the central AP controller 3, or an imagined zero point, e.g., a center point of the ceiling.
  • the spatial location information of the candidate AP 2b may be provided to the end point apparatus 4, e.g., by the central AP controller 3. Although here reference is made to a central AP controller, it is noted that within a building it may be possible to have multiple central AP controllers, whereby each respective central AP controller controls a number of optical access points.
  • the spatial location information of the candidate AP 2b may be estimated by the end point apparatus 4. If no spatial location information of the candidate AP 2b is available, the end point apparatus 4 may determine whether to activate the candidate AP 2b based on experiences, including but not limited to: previously known orientations of the APs, and a common arrangement of the APs, such as an assumption of that the candidate AP 2b is ceiling mounted, and a common ceiling height.
  • the end point apparatus 4 may determine a relationship of the motion information and the candidate AP 2b determined to be activated; and utilize the relationship to facilitate determination of a next candidate AP. For example, the end point apparatus 4 may “remember” that when the user turns around as shown in fig. 5, the AP 2b is the candidate AP to be used. Such experience may facilitate determination of the candidate APs to be used, when a similar motion is detected.
  • the end point apparatus 4 may determine whether to activate the candidate AP 2b based on a link quality indication of an optical connection between the optical receiver/transmitter and the candidate AP 2b. When the link quality indication meets a predetermined criterion, it is determined to activate the candidate access point apparatus. For example, when the link quality indication indicates that the link is sufficiently good, it may be determined to activate the candidate AP 2b. When the link quality indication indicates that the link is poor, it may be determined not to activate the candidate AP 2b.
  • Link quality indications may provide a straight forward indication of the quality of a link. Thus, it may facilitate determination of whether to activate the candidate AP 2b. Using more than one way to determine whether to activate the candidate access point apparatus can improve the robustness of the determination, especially when the motion is long-lasting, the motion is a combination of different types of movements, or no spatial position information of the candidate AP 2b is available.
  • link quality indication may be signal-noise-ratio, SNR.
  • Other examples of the link quality indication include: EVM, subcarrier SNR, subcarrier Quadrature amplitude modulation, QAM, constellation size, LQI, QoS, an optical power measurement, and a receiving signal strength.
  • an interference level is very low compared to the RF communications.
  • the SNR can for instance be measured at the optical receiver 11 at a level sheer, where an “analog” (in practice a high resolution digital) signal is converted in to symbol values.
  • these level slicers implement a threshold in between any two reference signal values, and “rounds off’ to a nearest valid signal level.
  • a distance between the received signal and the reference point can be interpreted as a noise contribution, which distance can be used to estimate a noise level, thus also the SNR.
  • Such distances are also known as the error vector magnitude, EVM.
  • SNR may, e.g., influence a selection of modulation, in particular a size of the QAM constellation on OFDM subcarriers.
  • an average of EVMs, estimated SNRs per subcarrier or an average of QAM constellation sizes may be used to estimate a “digital SNR” value.
  • the motion information may comprise a motion duration time of a current uninterrupted motion of the end point apparatus 4.
  • the controller 12 may be configured to stop utilizing the motion information to determine whether to activate the candidate AP 2b, when the motion duration time is larger than a threshold value.
  • the motion continues for a longer period of time, e.g., the user 5 turns around, then walks toward a working station and places the end point apparatus 4 down on a table, it may be less accurate to using the motion information only to determine whether to activate the candidate AP. Instead, using the link quality indication may provide a more accurate determination result.
  • the end point apparatus 4 uses MIMO, it is customary to limit a number of MIMO channels to a fairly small number, e.g. 2 or 3, such that a strong enough signal can be guaranteed.
  • the central AP controller 3 comprises a transceiver unit configured to receive an activation signal from the end point apparatus 4.
  • the central AP controller 3 comprises a control unit for independently controlling a plurality of APs 2a, 2b.
  • the activation signal comprises information of the candidate AP 2b to be activated.
  • the control unit is configured to: activate the candidate AP 2b based on the information of the activation signal.
  • the central AP controller 3 may be used for driving and controlling a plurality of distributed APs 2a, 2b.
  • the APs 2a, 2b may emit beacons to the end point apparatus 4 from time to time. This may allow the end point apparatus 4 to compare link qualities of different connections, and potentially change the links e.g., MIMO channels, used for communication. Indeed, in order to provide needed MIMO data crunching, it is beneficial to drive all the used APs 2a, 2b from the central AP controller 3.
  • the central AP controller 3 Another reason to provide the central AP controller 3 is that the overlapping MIMO signals must have a very strict time synchronization, preferably created by a common circuit in a centralized unit, e.g., the control unit of the central AP controller 3. Furthermore, signal processing operations may involve matrix inversion operations of multiple spatial streams spread over multiple transmitters, such that after cross talk on the channels, signals are free of crosstalk because of the inverse preprocessing. Consequently, it is preferable to centrally perform the matrix inversion operations.
  • processors referred to herein may in practice be implemented using an integrated circuit or plural integrated circuits, an application-specific integrated circuit (ASIC), field-programmable gate array (FPGA), or digital signal processor (DSP), etc.
  • ASIC application-specific integrated circuit
  • FPGA field-programmable gate array
  • DSP digital signal processor
  • At least some aspects of the embodiments described herein with reference to the drawings may comprise computing processes performed in a processor.
  • the invention thus also extends to computer programs and computer programs on or in a machine-readable carrier, adapted for putting the invention into practice.
  • the program may be in the form of non-transitory source code, object code, a code intermediate between source and object code such as in partially compiled form, or in any other non-transitory form suitable for use in the implementation of processes according to the invention.
  • the carrier may be any entity or device capable of carrying the program.
  • the carrier may comprise a storage medium, such as a solid-state drive (SSD) or other semiconductor-based RAM; a ROM, for example a CD ROM or a semiconductor ROM; a magnetic recording medium, for example a hard disk or an optical data storage device.
  • SSD solid-state drive
  • the optical wireless communication end point apparatus may be arranged in many different ways, e.g., the optical receiver may be of different types, numbers and arrangements of directions. Such details are not considered to be an important part of the present invention, which relates to the energy efficient optical wireless communication end point apparatus.

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Optical Communication System (AREA)
  • Mobile Radio Communication Systems (AREA)

Abstract

L'invention concerne un appareil de point d'extrémité de communication optique sans fil (4) comprenant un récepteur optique (11) pour recevoir des informations de plus d'une connexion optique, un capteur pour détecter des informations de mouvement de l'appareil de point d'extrémité, et une commande, dans lequel la commande est configurée pour, sur la base des informations de mouvement, déterminer et utiliser un sous-ensemble approprié des connexions optiques pour recevoir des informations et pour déterminer s'il faut activer un appareil de point d'accès candidat (2b) ; lorsqu'il est déterminé qu'il faut activer l'appareil de point d'accès candidat (2b), générer un signal d'activation pour activer l'appareil de point d'accès candidat.
PCT/EP2021/087737 2021-01-05 2021-12-28 Point d'extrémité de communication optique sans fil efficace en énergie WO2022148694A1 (fr)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9813150B1 (en) 2016-09-23 2017-11-07 Qualcomm Incorporated Controllable selection of light-capture devices
WO2020169378A1 (fr) * 2019-02-18 2020-08-27 Signify Holding B.V. Procédé et système de communication par signaux lumineux
US10855369B2 (en) 2017-04-18 2020-12-01 Purelifi Limited Mobile device for optical wireless communication
CN112152709A (zh) 2019-06-28 2020-12-29 Oppo广东移动通信有限公司 移动终端的光保真LiFi控制方法、装置、移动终端及介质

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9813150B1 (en) 2016-09-23 2017-11-07 Qualcomm Incorporated Controllable selection of light-capture devices
US10855369B2 (en) 2017-04-18 2020-12-01 Purelifi Limited Mobile device for optical wireless communication
WO2020169378A1 (fr) * 2019-02-18 2020-08-27 Signify Holding B.V. Procédé et système de communication par signaux lumineux
CN112152709A (zh) 2019-06-28 2020-12-29 Oppo广东移动通信有限公司 移动终端的光保真LiFi控制方法、装置、移动终端及介质

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