Abstract: Because of the line-of-sight character of optical wireless communication and a limited field-of-view of optical receivers, the coverage of an access point and the overlapping coverage area of adjacent access points in an optical system are smaller as compared to a RF system. It turns more challenging to support an end point (110) to roam securely in an optical multi-cell wireless communication network. To speed up the derivation of a new pairwise transient key with a new access point during a handover procedure, the end point of this invention comprises a controller (118) that is configured to act as a second supplicant (1181), on behalf of a first supplicant (1186) comprised in a host processor (1185), to communicate with an authenticator to establish a new pairwise transient key for the end point (110) and a candidate access point, and an active pairwise transient key with the currently associated access point is used to secure the communication for new key derivation.

Abstract: In a LiFi network with multiple coordinators, interference in the overlapping areas between the local parts of the network can occur if each coordinator determines its own local time schedule for communicating with devices. To solve this problem, the invention proposes cooperation between the coordinators to determine non-interfering local time schedules whereby the coordinators rely on interference reports from the devices in the overlapping areas and apply a small number of simple rules. The proposed method is simple, scalable and independent from a central unit.

Abstract: A power transmitter (101) of a wireless power transfer system comprises a resonance including a transmitter coil (103) for generating a power transfer signal for wirelessly transferring power to a power receiver (105). Further, a driver (1303) generates a drive signal for the resonance circuit (201) and a message receiver (1305) is arranged to receive messages from the power receiver (105). A power loop controller (1307) implements a power control loop by adapting the power of the drive signal in response to power control messages received from the power receiver (105). However, the regulation is subject to a constraint of at least one of a current or voltage of the resonance circuit and a power of the drive signal being below a maximum limit. Further, the power transmitter (101) comprises an adapter (1309) which adapts the maximum limit in response to a load indication indicative of a loading of the power transfer signal by the power receiver (105).

Abstract: The power transmitter (101) providing power to a power receiver (105) comprises a communicator (309) communicating with the power receiver (105) and a negotiator (305) negotiating a guaranteed power level with the power receiver (105) prior to a power transfer phase. The guaranteed power level is a minimum power level guaranteed by the power transmitter (101) throughout the power transfer phase. During the power transfer phase, a determiner (307) dynamically determines an available power level based on the prevailing operating parameters. The available power level is one that can currently be provided but is not guaranteed. The power controller (309) is arranged to, during the power transfer phase, increase the power level above the guaranteed minimum level in response to power control messages, and to reduce the power level regardless of the power control messages in response to a detection that the power level exceeds the available power level.

Abstract: A wireless power transmitter (101) an output circuit (203, 103) comprises a transmitter coil (103) for which generates the power transfer signal a drive signal generated by a driver circuit (201) is applied. A power loop controller (209) implements a power control loop for controlling the drive signal to adjust a power level of the power transfer signal in response to power control error messages received from the power receiver (105). A mode store (213) stores a plurality of power level modes for the power receiver where each power level mode is associated with a reference power level for the power transfer signal. A mode circuit (211) adapts the drive signal to set the power level of the power transfer signal to a first reference value in response to receiving a mode request message where the first reference value corresponds to a reference power level for a first power level mode indicated in the mode request message.

Abstract: According to one aspect disclosed herein, there is provided a client device for use in an optical wireless communications network, the client device comprising a transceiver configured to receive data via an optical wireless connection. The transceiver comprises an upward facing optical transducer configured to detect or transmit an optical wireless transmission, the sensor arranged to have a coverage area with at least two 5 concentric segments. A portion of the sensor is configured to provide an outermost segment of the at least two concentric segments.

Abstract: In an optical wireless communication, OWC, network (100), time division multiple access, TDMA, is commonly used for interference suppression among multiple network devices (D1-Dn) associated to a single coordinator, or among adjacent coordinators (C1-Cn). However, an offset of MAC cycles among two adjacent coordinators (C1-C2) may still result in interference to a network device (D1) located in the overlapping area of the coverage areas of these two adjacent coordinators (C1-Cn). This invention is directed to various methods, apparatus, systems, computer program and computer-readable media for providing a mechanism to make use of an out-of-band channel to send a signal from a network device (D1) to the two adjacent coordinators (C1-C2), for assisting the alignment of MAC cycles among the two adjacent coordinators (C1-C2), and the out-of-band channel has a line-of-sight character, and is out-of-band as compared to the OWC network (100).

Abstract: The power transmitter (101) providing power to a power receiver (105) comprises a communicator (309) communicating with the power receiver (105) and a negotiator (305) negotiating a guaranteed power level with the power receiver (105) prior to a power transfer phase. The guaranteed power level is a minimum power level guaranteed by the power transmitter (101) throughout the power transfer phase. During the power transfer phase, a determiner (307) dynamically determines an available power level based on the prevailing operating parameters. The available power level is one that can currently be provided but is not guaranteed. The power controller (309) is arranged to, during the power transfer phase, increase the power level above the guaranteed minimum level in response to power control messages, and to reduce the power level regardless of the power control messages in response to a detection that the power level exceeds the available power level.

Abstract: To fully enjoy the benefit of adaptive modulation or bit loading in a multi-carrier wireless communication system, a bit loading control method (700) is disclosed to reduce the system complexity and signaling overhead by making use of an attribute of the communication channel, which has a declining channel response with increasing frequency. Instead of applying adaptive bit loading on a per subcarrier basis, the disclosed method (700) obtains (S703) an estimated channel response based a test signa; and determines (S704) according to the estimated channel response a bit loading scheme for allocating the plurality of subcarriers into one or more non-overlapping frequency segments. For each frequency segment, an individual modulation scheme is assigned, which is shared by the more than one adjacent subcarrier comprised in the same frequency segment. The monotonicity of the channel response is used to accelerate the algorithm, as well as to make control information more compact.

Abstract: Because of the line-of-sight character of optical wireless communication and a limited field-of-view of optical receivers, the coverage of an access point (120) and the overlapping coverage area of adjacent access points (120) in an optical system are smaller as compared to a RF system. It turns more challenging to support an end point (110) to roam securely in an optical multi-cell wireless communication network (100). To address that problem, a subsystem is disclosed to select for the end point (110) a candidate access point out of the plurality of access points (120) in view of one or more neighbor relationships, and to inform the end point (110) about the candidate access point to trigger the end point (110) to start a procedure for pre-establishing a new pairwise transient key between the end point (110) and the candidate access point (120) for a secure handover.

Abstract: This invention proposes a mechanism to improve system performance in an optical wireless communication system by examining whether time slots in time channels are to be scheduled for exclusive use or could be utilized for parallel communication. The examination is based on a cross-over point from tolerating interference to applying time division. A reserved period for each access point is defined within its assigned time channel, which is exclusively reserved for communication with its endpoint(s). This reduces the communication overhead and keeps freedom of adapting slot-scheduling in the exclusive period at the cost of some performance reduction. To minimize this performance reduction, the size of the reserved period can be adapted to the actual need based on the traffic demand for exclusive use and non-exclusive use.

Abstract: Power saving is achieved in an optical wireless communication (VLC/LiFi) system by using a polling-based medium access control (MAC) scheme, wherein an access point can use a silent period when no one is polled (and EPs can thus sleep). When transmission queues are empty, the access point may apply the silent period which may be based on a minimum polling interval announced by broadcast.

Abstract: A wireless inductive power transfer system comprises a power transmitter for transmitting power inductively to a power receiver via transmitter coil 11 to receiver coil 21. In the system, a communication method comprises a step 37 of transmitting, by the power receiver, first data and second data to the power transmitter, the first data indicating a modulation requirement, and the second data indicating an inquiry message; a step 32 for receiving, by the power transmitter, the first data and the second data from the power receiver; a step 34 for transmitting, by the power transmitter, a response message for responding to said inquiry message, by modulating a power signal according to said modulation requirement so as to carry the response message; and a step 35 for receiving the response message by the power receiver by demodulating the modulated power signal carrying the response message received via the receiver coil from the power transmitter.

Abstract: An optical wireless communications, OWC, network (100) comprises a plurality of access points (120) for communicating with a plurality of endpoint devices (110) via modulated light. A control system (13) receives a report indicating a timeslot during which a first one of the access points (120a) detected an event indicative of interference and transmits an indication of the timeslot to at least one other access point (120b). The other access point (120b) provides to the control system (13) identifiers of any registered endpoint devices which used or are using that timeslot. If the control system (13) receives an identifier of a single endpoint device from the other access point (120b), it determines that endpoint device as a cause of the interference experienced at the first access point (120a). If the control system (13) receives identifiers of plural endpoint devices from other access points (120), it causes endpoint devices in the OWC network (100) to advertise their presence.

Abstract: A power receiver receives a wireless power transfer from a power transfer signal generated by a wireless power transmitter during a power transfer phase. The power transfer signal employing a repeating time frame during the power transfer phase where the frame comprises at least a power transfer time interval and a foreign object detection time interval. The power receiver comprises a synchronizer (311) which synchronizes a local time reference to the repeating time frame and a load controller (309) which disconnects a load (303) during at least part of the foreign object time detection time intervals during at least part of the power transfer phase. The timing of the disconnecting is dependent on the local time reference. A mode controller (313) switches between a first operational mode and a second operational mode for the power transfer time intervals in response to a reliability measure for the synchronization.

Abstract: This invention relates to an interference handling method and system for an optical wireless communication system, wherein multiple levels and operating modes are provided to flexibly handle partitioning of a coordination functionality between a central entity and distributed entities. Thereby, the coordination functionality which relies on interference reports from devices in overlapping coverage areas of access points can be central or distributed over access points or partly central and partly distributed.

Abstract: The invention proposes a method of encoding data packet by encoding type information and size information of said data packet into the same field. The invention also proposes a method of processing data packets received. The data packet comprises a header part and a message part. The header part comprises at least one bit for indicating the type of said data packet, said method comprising a step 101 of obtaining the size information of said data packet based on said at least one bit.

Abstract: Power saving is achieved in an optical wireless communication (VLC/LiFi) system by using a polling-based medium access control (MAC) scheme, wherein an access point can use a silent period when no one is polled (and EPs can thus sleep). When transmission queues are empty, the access point may apply the silent period which may be based on a minimum polling interval announced by broadcast.

Abstract: A system comprising: a plurality of first devices, each configured to transmit a low-frequency, LF, light signal comprising an identifier of the respective first device, and to transmit and/or receive a high-frequency, HF, light signal comprising data content; and a second device configured to receive a LF light signal from each of the first devices, and to transmit and/or receive a HF light signal from at least one first device, wherein the second device has an adaptable receiving and/or transmitting direction for respectively receiving and/or transmitting the HF light signal, and wherein the second device comprises a controller configured to: based on the identifiers encoded in the LF light signals, determine a position of the second device relative to the first devices and select a first device; and based on the determination, adapt the receiving and/or transmitting direction toward the selected first device.

Abstract: Because of the line-of-sight character of optical wireless communication and a limited field-of-view of optical receivers, the coverage of an access point and the overlapping coverage area of adjacent access points in an optical system are smaller as compared to a RF system. It turns more challenging to support an end point (110) to roam securely in an optical multi-cell wireless communication network. To speed up the derivation of a new pairwise transient key with a new access point during a handover procedure, the end point of this invention comprises a controller (118) that is configured to act as a second supplicant (1181), on behalf of a first supplicant (1186) comprised in a host processor (1185), to communicate with an authenticator to establish a new pairwise transient key for the end point (110) and a candidate access point, and an active pairwise transient key with the currently associated access point is used to secure the communication for new key derivation.