WO2022013146A1

WO2022013146A1 - A flexible and reliable wireless communication system

Info

Publication number: WO2022013146A1
Application number: PCT/EP2021/069319
Authority: WO
Inventors: Michel Germe; Andreas Felix Alfred BLUSCHKE; Haimin Tao
Original assignee: Signify Holding B.V.
Priority date: 2020-07-16
Filing date: 2021-07-12
Publication date: 2022-01-20

Abstract

In a wireless communication system (100), an access point (120) is configured to provide at least two air interfaces concurrently, with one is based on RF communication and the other is based on optical wireless communication. An end device (110) may select, according to certain requirements or preferences, at least one out of the two available air interfaces to connect to the access point (120). Different system setup options are disclosed for the access point and the end device. According to the present invention, additional flexibility and reliability is provided to the end device with minimized change to the hardware, in terms of cost, power efficiency, and form factor.

Description

A flexible and reliable wireless communication system

FIELD OF THE INVENTION

The invention relates to the field of wireless communication networks, such as Wi-Fi and Li-Fi networks. More particularly, various methods, apparatus, systems, and computer-readable media are disclosed herein related to reliability enhancement of the wireless system via a hybrid configuration at both an access point side and an end point side.

BACKGROUND OF THE INVENTION

To enable more and more electronic devices like laptops, tablets, and smartphones to connect wirelessly to the Internet, wireless communication confronts unprecedented requirements on data rates and also link qualities, and such requirements keep on growing year over year, considering the emerging digital revolution related to Internet-of- Things (IoT). Radio frequency technology like Wi-Fi has limited spectrum capacity to embrace this revolution. In the meanwhile, light fidelity (Li-Fi) is drawing more and more attention with its intrinsic security enhancement and capability to support higher data rates over the available bandwidth in visible light, Ultraviolet (UV), and Infrared (IR) spectra. Furthermore, Li-Fi is directional and shielded by light blocking materials, which provides it with the potential to deploy a larger number of access points, as compared to Wi-Fi, in a dense area of users by spatially reusing the same bandwidth. These key advantages over the wireless radio frequency communication make Li-Fi a promising secure solution to mitigate the pressure on the crowded radio spectrum for IoT applications. Other benefits of Li-Fi include guaranteed bandwidth for a certain user, and the ability to function safely in areas otherwise susceptible to electromagnetic interference. Therefore, Li-Fi is a very promising technology to enable the next generation of immersive connectivity.

There are several related terminologies in the area of lighting-based communication. Visible-light communication (VLC) transmits data by intensity modulating optical sources, such as light emitting diodes (LEDs) and laser diodes (LDs), faster than the persistence of the human eye. VLC is often used to embed a signal in the light emitted by an illumination source such as an everyday luminaire, e.g. room lighting or outdoor lighting, thus allowing use of the illumination from the luminaires as a carrier of information. The light may thus comprise both a visible illumination contribution for illuminating a target environment such as a room (typically the primary purpose of the light), and an embedded signal for providing information into the environment (typically considered a secondary function of the light). In such cases, the modulation may typically be performed at a high enough frequency to be beyond human perception, or at least such that any visible temporal light artefacts (e.g. flicker and/or strobe artefacts) are weak enough and at sufficiently high frequencies not to be noticeable or at least to be tolerable to humans. Thus, the embedded signal does not affect the primary illumination function, i.e., so the user only perceives the overall illumination and not the effect of the data being modulated into that illumination.

The IEEE 802.15.7 visible-light communication personal area network (VP AN) standard maps the intended applications to four topologies: peer-to-peer, star, broadcast and coordinated. Optical Wireless PAN (OWPAN) is a more generic term than VP AN also allowing invisible light, such as UV and IR, for communication. Thus, Li-Fi is generally accepted as a derivative of optical wireless communications (OWC) technology, which makes use of the light spectrum in a broad scope to support bi-directional data communication.

In a Li-Fi system, the signal is embedded by modulating a property of the light, typically the intensity, according to any of a variety of suitable modulation techniques. For communication at high speed, often Infrared (IR) rather than visible light communication is used. Although the ultraviolet and infrared radiation is not visible to the human eye, the technology for utilizing these regions of the spectra is the same, although variations may occur as a result of wavelength dependencies, such as in the case of refractive indices. In many instances there are advantages to using ultraviolet and/or infrared as these frequency ranges are not visible to the human eye, and more flexibility can be introduced in the system. Of course, ultraviolet quanta have higher energy levels compared to those of infrared and/or visible light, which in turn may render use of ultraviolet light undesirable in certain circumstances.

Based on the modulations, the information in the light can be detected using any suitable light sensor or photodetector. For example, the light sensor may be a photodiode. The light sensor may be a dedicated photocell (point detector), an array of photocells possibly with a lens, reflector, diffuser, or phosphor converter (for lower speeds), or an array of photocells (pixels) and a lens for forming an image on the array. E.g., the light sensor may be a dedicated photocell included in a dongle which plugs into a user device such as a smartphone, tablet or laptop, or the sensor may be integrated and or dual-purpose, such as an array of infrared detectors initially designed for 3D face recognition. Either way this may enable an application running on the user device to receive data via the light.

Considering other technologies for local area networking, Wi-Fi is one of the most widely used wireless communication technologies. With the recent development of 5G cellular networks, great efforts are also spent on rolling out 5G indoor deployments. There are different network architectures or options available to network operators for deploying 5G technology indoors, such as based on distributed antenna system (DAS), distributed radio, or small cells. DAS allows existing base station and radio equipment to remain almost unchanged. In a passive DAS configuration, the high transmit power of macro radios are distributed across many low-power antenna points within a venue, typically via coaxial cables. Active DAS replaces many of the coaxial RF cables with structured fiber and copper cabling. Instead of directly propagating RF signals from the radio, active DAS transmits the signals over a communication network within the building, then reconstitutes the signals closer to the antenna points. Similar to a Wi-Fi network, uncoordinated indoor small cells often have the advantages of low unit cost and simple installation with IT-grade structured cabling. An extra layer of network coordination may be needed to ensure seamless mobility across the network. Like DAS and small cells, distributed radios ensure high RF signal dominance throughout a venue by placing many low-power transmitters close to the users. Like uncoordinated small cells, they can often use low-cost IT-grade cabling for both signaling and power. Since the complex signal processing functions are in a centralized location, capacity can be flexibly shifted between antenna points and advanced coordination features can be utilized.

In the following, the term “access point” of a Li-Fi system is used to designate a logical access device that can be connected to one or more physical access devices (e.g. optical transceivers). Such a physical access device may typically, but not necessary, be located at a luminaire and the logical access point may be connected to one or more physical access devices each located at one or more luminaires. An access point in turn may serve one or more network devices or end devices associated to it to thereby form an optical cell.

US2011087879A1 relates to a communication network comprising one or more wireless access points each with both a RF transceiver and an optical transceiver. And each access point is configured to direct unsecure data via RF link and to direct secure data via optical wireless link. The same setup also applies to a wireless handset. JP2006148341 A is related to high speed wireless LAN, where both an access point and a station apparatus have radio wave communication means and optical radio communication means.

MCBRIDE ALEXANDER ET AL “Transitioning to Hybrid Radio/Optical Networks: Development of a Flexible Visible Light Communication Testbed” is related to a VLC/RF hybrid system.

SUMMARY OF THE INVENTION

To enable an electronic device or an end device to support higher data rate communication catering for IoT applications, optical wireless communication or Li-Fi is proposed as a complementary, or even replacing, technology to a wired connection or a radio frequency (RF) based wireless communication. Although the line-of-sight character of optical wireless communication provides the intrinsic security of an optical link, because of limited field-of-views (FoV) of optical receivers, optical cells usually have a relatively small coverage.

Since Wi-Fi networks are deployed almost everywhere, at home, in the office, in the bus, on the train, at the station, at the airport, at the stadium, and etc, it is advantageous to integrate Li-Fi access points to an existing infrastructure, such as a Wi-Fi infrastructure, to provide the connection between the Li-Fi access points and the backbone network. In view of the recent development of indoor extension of 5G cellular network, it may also be an option that the Li-Fi access point is integrated in a 5G small cell base station infrastructure. Thus, the access point with a hybrid configuration may provide two or more air interfaces to a user concurrently.

The coexistence of radio frequency (RF) and optical networks in the same area also provides extra reliability, flexibility, and freedom to the end device. Depending on the application requirements, user preferences, or link qualities, the end device may preferentially select one network and keep another network as a backup mode, or one is used as control channel for the other, such as to realize navigation/positioning. The end device may also use the two or more coexisting networks in combination, such as to aggregate the data communication over two or more heterogenous links with the same access point.

In view of the above, the present disclosure is directed to methods, apparatus, systems, computer program and computer-readable media for providing at least two concurrent air interfaces at an access point side and allowing an end point device the freedom to select one out of the two air interfaces to connect to the access point. More particularly, the goal of this invention is achieved by a method of a wireless communication system as claimed in claim 1, by an end device as claimed in claim 6, by a method of an end device as claimed in claim 11, and by a computer program as claimed in claim 12.

In accordance with a first aspect of the invention a wireless communication system is provided, wherein the wireless communication system comprises: an access point comprising a first optical transceiver configured to provide a first air interface based on optical wireless communication; and a first Radio Frequency, RF, wireless transceiver configured to provide a second air interface based on RF wireless communication; and wherein the access point is configured to provide the first air interface and the second air interface concurrently; and an end device comprising a second RF wireless transceiver configured to carry out RF wireless communication; a first baseband module is selectively routed to enable optical wireless communication or another wireless communication; a first optical front end configured to connect to the first baseband module to carry out optical wireless communication; a controller configured to select one wireless communication mode out of the optical wireless communication and the RF wireless communication to connect to the access point, and wherein the selection is according to at least one of: maximum data rates supported by the optical wireless communication or the RF wireless communication; a link quality evaluation parameter about an optical wireless communication link or an RF wireless communication link; an application requirement; a battery status parameter; and a user preference; and wherein the end device is configured to connect to the access point via the selected wireless communication mode, and when the optical wireless communication is selected, the second RF wireless transceiver is reused partially or in its entirety to enable the optical wireless communication.

The wireless communication system may be deployed in different scenarios, such as at home, in an office, in a factory, in a stadium, in an exhibition hall, at an airport, or another indoor environment. The end device is typically a portable device or mobile device, such as a smart phone, a tablet, a laptop, a remote controller, or another mobile device.

It is beneficial that the access point is capable to provide at least two heterogeneous air interfaces in parallel, allowing the end device the flexibility to select one out of the at least two air interfaces according to one or more parameters or requirements. Preferably, one of the at least two air interfaces is based on RF wireless communication. Note that the RF wireless communication should be understood in a broad sense, such that it may also be a wireless communication carried out in a millimeter wave frequency range. The other air interface is preferably based on optical wireless communication. As compared to a RF communication, the optical wireless communication may be characterized in that it supports higher data rates, but with a narrower FoV. Thus, the end device may benefit from the optical wireless communication when it is located within the FoV of the optical link; and then when it is roaming out of that range, the end device may seamlessly switch to or handover to the RF wireless communication.

Although it may be an option that the end device can support both links with the access point in parallel for further improved throughput, it may be more cost-effective that the end device mainly supports one link at a time. And thus, some hardware may be shared in the end device for the RF wireless communication and the optical wireless communication in a time-interleaved manner. For example, the first optical front end may be configured to connect to the first baseband module to carry out optical wireless communication. It may also be that the first optical front end is subsequently disconnected from the first baseband module, and then the first baseband module may be free for another use, such as to support another communication link.

For the end device to select one wireless communication mode rather than the other or another, different considerations may be taken. For example, an optical wireless communication link and an RF wireless communication link may be bounded by different maximum data rates to be supported by the link, which may be determined by the bandwidth of the communication channel, the output power level of a transmitter, a regulation according to a communication protocol, a sensitivity level of a receiver, a noise level of the channel or the hardware. On the other hand, an application running on the mobile end device may impose a minimum requirement on the data rate. Thus, the mobile end device may take that requirement into account when making the selection.

Furthermore, the mobile end device may also take an actual link quality evaluation parameter into account, such as a signal-to-noise ratio (SNR.) parameter, a link quality indicator (LQI) parameter, or another indicator. This is because a wireless channel may confront different channel conditions resulted from sporadic interference, varying orientations between a pair of transmitter and receiver, an obstacle between the pair of transmitter and receiver, or even a moving object passing by. The real data rate to be supported over a certain link is determined by the actual link quality. Since the mobile end device is powered by a battery, the battery status may also be considered, especially when one communication mode consumes significantly more power than the other. In addition to that, the selection may also be dominated by an application requirement or a user preference. For example, the optical wireless communication may have an intrinsic security benefit as compared to RF communication.

For certain application data, it may be beneficial to preferentially select the optical wireless communication.

In one embodiment, the RF wireless communication and/or the other wireless communication is based on Wi-Fi technology.

Since Wi-Fi infrastructure is widely deployed in the indoor environment, a most straight-forward way to apply the present invention may be to upgrade a conventional Wi-Fi access point by incorporating an optical wireless communication air interface.

In another option, the RF wireless communication may be based on Bluetooth technology. Since many Wi-Fi solutions also comprise an additional Bluetooth Low Energy (BLE) mode, it may also be an option to use BLE for RF wireless communication, such as for navigation/positioning

In another embodiment, the RF wireless communication and/or the other wireless communication is based on indoor 5G cellular technology.

Given the recent development on 5G cellular communication, especially indoor small cell deployment, it may also be an option that an optical wireless communication air interface is added to a small cell base station.

Advantageously, the access point is further configured to send a control signal via the RF wireless communication for setting up the optical wireless communication.

The two concurrent air interfaces may operate in a coordinated manner. For example, the RF wireless communication is typically omni-directional and supports non-line- of-sight (NLOS) channel, while optical wireless communication implies a LOS channel and typically a narrow FoV angle. Therefore, it may be beneficial that the access point makes use of the RF wireless communication to send control information indicative of how to set up the optical wireless communication to the mobile end device. Thus, the mobile end device may first obtain such information via the RF channel, and then may assess if it is beneficial to establish an optical wireless link with the same access point.

In one example, the optical communication, or Li-Fi communication, is used for secure data transmission, and the RF communication is for auxiliary communication, such as network management and/or positioning (for navigating toward the coverage of the optical link).

Of course, it may also be an option that the optical air interface is used for auxiliary communication. In this way, the RF air interface is used for main data communication, while security sensitive data, such as passwords or keys, may be sent via the optical channel.

In another preferred setup, the access point is further configured to send data via packet aggregation over the two air interfaces.

In one example, packet aggregation may be implemented as a multiple-input and multiple-output (MIMO) setup, and the two air interfaces may be employed as a 2 by 2 MIMO. Thus, the effective throughput between the access point and the mobile end device can be improved even further.

In accordance with a second aspect of the invention an access point is provided for use in a wireless communication system, wherein the access point comprises: a first optical transceiver configured to provide a first air interface based on optical wireless communication; and a first Radio Frequency, RF, wireless transceiver configured to provide a second air interface based on RF wireless communication; and wherein the access point is configured to provide the first air interface and the second air interface concurrently.

The access point has at least two dedicated transceivers to provide the at least two concurrent air interfaces. For RF communication, the RF wireless transceiver may be a single chip radio, such as of a system-on-chip (SoC) solution. It may also comprise one or more integrated circuits, each providing a different part of the functionality of the transceiver chain. As one example, the RF wireless transceiver may comprise a first chip operating as a baseband modem and a second chip operating as analog front end (AFE) part. The antenna for RF communication may be standalone device or may be integrated in the SoC chip or the AFE chip.

Preferably, the first optical transceiver of the access point comprises: a second optical front end; and a second baseband module; and wherein the second baseband module comprises either: a dedicated integrated circuit operating as a baseband modem; or a third RF wireless transceiver and a second conversion circuit, wherein the second conversion circuit configured to down-convert an RF output signal from the third RF wireless transceiver to a baseband signal for input to the second optical front end; and to up-convert a baseband output signal from the second optical front end to an RF signal for input to the third RF wireless transceiver. Therefore, the optical transceiver typically comprises at least two parts: the optical front end and the baseband module. The optical front end comprises at least a light source and a light sensor, which implement the conversion between electrical signals and optical signals for the transmitter chain and the receiver chain, respectively.

For the baseband module, it may be a dedicated baseband module chip suitable for signal processing typical for use in optical wireless communication. The dedicated baseband module chip may be a dedicated design for the optical communication, or it may be reused from another communication protocol that has similar signal processing procedure.

In another option, the baseband module is not a dedicated integrated circuit for digital signal processing. Instead, it may be reused from a single chip radio. For example, the single chip radio may be a third RF wireless transceiver, which outputs signals at RF frequency. In order to adapt the RF output signals from the third wireless transceiver so as to make them suitable for the input to the optical front end, a conversion circuit is needed. The conversion circuit is configured to down-convert the RF output signal from the third RF wireless transceiver to a baseband signal for input to the second optical front end; and to up- convert a baseband output signal from the second optical front end to an RF signal for input to the third RF wireless transceiver.

In accordance with a third aspect of the invention an end device is provided. A end device in a wireless communication system, the end device comprising: a second Radio Frequency, RF, wireless transceiver configured to carry out RF wireless communication; a first baseband module is selectively routed to enable optical wireless communication or another wireless communication; a first optical front end configured to connect to the first baseband module to carry out optical wireless communication; a controller configured to select one wireless communication mode out of the optical wireless communication and the RF wireless communication to connect to an access point, and wherein the selection is according to at least one of: maximum data rates to be supported by the optical wireless communication and the RF wireless communication; a link quality evaluation parameter about an optical wireless communication link or an RF wireless communication link; an application requirement; a battery status parameter; and a user preference; and wherein the end device is configured to connect to the access point via the selected wireless communication mode, and when the optical wireless communication is selected, the second RF wireless transceiver is reused partially or in its entirety to enable the optical wireless communication. To complement the access point according to the present invention, an end device also has the capability to support two air interfaces. But the difference is that the mobile end device may support only one out of the two air interfaces, either the optical wireless communication or the RF wireless communication, at a time. This is due to some practical consideration that the mobile end device may face more restrictive requirements in terms of power consumption, form factor and cost. By enabling only one communication interface at a time, the hardware for different communication modes may be reused, i.e. shared in a time-interleaved manner.

In one embodiment, the first baseband module comprises a conversion circuit that comprises at least a mixer, and wherein the baseband module is configured to connect to the second RF wireless transceiver: to down-convert an RF output signal from the second RF wireless transceiver to a baseband signal for input to the first optical front end; and to up- convert a baseband output signal from the first optical front-end to an RF signal for input to the second RF wireless transceiver.

In this example, the second RF wireless transceiver is used for both RF communication and optical communication. By default, the second RF wireless transceiver is used for the RF wireless communication. In order to support optical communication, a conversion circuit is needed to adapt the second RF wireless transceiver for use as a baseband module for the optical front end.

In a preferred setup, the end device is further configured to switch between the optical wireless communication and the RF wireless communication by enabling and disabling the conversion circuit.

Since the same second RF wireless transceiver is needed for both RF communication and optical communication, when the conversion circuit is enabled, the second RF wireless transceiver is connected via the conversion circuit to the optical front end for optical communication; when the conversion circuit is disabled, the second RF wireless transceiver is connected to the antenna for RF wireless communication.

In another embodiment, the second RF wireless transceiver comprises a first integrated circuit operating as a baseband modem and a second integrated circuit as an RF front end; and the first baseband module is reused from the first integrated circuit of the second RF wireless transceiver.

When the second RF wireless transceiver is not a single chip radio but comprises multiple integrated circuits serving different functions, e.g. a baseband modem and an analog frontend. It may be more convenient to simply reuse the baseband modem of the second RF wireless transceiver as the first baseband module for the optical communication. And hence, no further conversion circuit is needed.

Advantageously, the end device is further configured to switch between the optical wireless communication and the RF wireless communication by adaptively connecting the first integrated circuit of the second RF wireless transceiver to the first optical front end or to the second integrated circuit of the second RF wireless transceiver.

In one configuration, the end device reuses the baseband modem of a cellular communication chipset for optical communication. For example, when the 4G or 5G cellular data service is not available for an indoor environment, the end device disables 4G or 5G cellular communication, and reuses the 4G or 5G baseband modem for optical wireless communication. Thus, in this configuration the end device switches between cellular and Li- Fi communication with a same chipset. In the meanwhile, the end device may also keep a separate Wi-Fi chipset enabled, in parallel to the Li-Fi communication. Hence, the end device can cooperate with an access point, which enables concurrent Wi-Fi and optical air interfaces, for packet aggregation.

In accordance with a further aspect of the invention a method of an access point is provided. A method of an access point in a wireless communication system, the method comprises the access point providing a first air interface based on optical wireless communication technology; and providing a second air interface based on Radio Frequency, RF, wireless communication technology; and wherein the first air interface and the second air interface are provided concurrently.

In accordance with a further aspect of the invention a method of an end device is provided. A method of an end device in a wireless communication system, the method comprising the end device: carrying out RF wireless communication; carrying out optical wireless communication; selecting one wireless communication mode out of the optical wireless communication and the RF wireless communication to connect to an access point, and wherein the selection is according to at least one of: maximum data rates to be supported by an optical wireless communication link and an RF wireless communication link; a link quality evaluation parameter about an optical wireless communication link or an RF wireless communication link; an application requirement; a battery status parameter; and a user preference; and connecting to an access point via the selected wireless communication mode, wherein when the optical wireless communication is selected, the second RF wireless transceiver is reused partially or in its entirety to enable the optical wireless communication. The invention may further be embodied in a computing program comprising code means which, when the program is executed by an access point comprising processing means, cause the processing means to perform the method of the access point as disclosed in the present invention.

The invention may further be embodied in a computing program comprising code means which, when the program is executed by an end device comprising processing means, cause the processing means to perform the method of the end device as disclosed in the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings, like reference characters generally refer to the same parts throughout the different figures. Also, the drawings are not necessarily to scale, emphasis instead generally being placed upon illustrating the principles of the invention.

FIG. 1 demonstrates an overview of the wireless communication system, with one or more access points comprising at least two concurrent air interfaces;

FIG. 2 illustrates one possible system setup of an access point;

FIG. 3 illustrates one possible system setup of an access point;

FIG. 4 illustrates one possible system setup of an access point;

FIG. 5 illustrates one possible system setup of an end device;

FIG. 6 illustrates one possible system setup of an end device;

FIG. 7 schematically depicts basic components of an access point of the present invention;

FIG. 8 schematically depicts basic components of an access point of the present invention;

FIG. 9 schematically depicts basic components of an access point of the present invention;

FIG. 10 schematically depicts basic components of an end device of the present invention;

FIG. 11 schematically depicts basic components of an end device of the present invention;

FIG. 12 schematically depicts basic components of an end device of the present invention;

FIG. 13 shows a flow chart of a method of an access point; and

FIG. 14 shows a flow chart of a method of an end device. DETAILED DESCRIPTION OF EMBODIMENTS

Various embodiments of the present invention will now be described based on a wireless communication system as shown in FIG. 1. For illustration purposes, the wireless communication system 100 is connected to a backbone network 20 via an IP router 15 and an Ethernet switch 14, while in a practical system more routers and switches may be deployed to connect the backbone network to the multi-cell wireless communication system. Note that the Ethernet switch 14 and the IP router 15 are also part of the backbone network. The symbol of the backbone network 20 in FIG. 1 is for illustration purpose, which should be considered as the rest part of the backbone network apart from the Ethernet switch 14 and the IP router 15 shown in the figure. In this example, the connection between the one or more access points and the backbone network is called a backbone connection 21. The backbone connection is a stable and high-speed link, which can be a wired connection, such as Ethernet, optical fiber, or a wireless connection based on radio frequency (RF) or millimeter- wave. The backbone connection can also be another kind of optical wireless link that is different from the one that an end device is performing in the multi-cell wireless network. One example of the other kind of optical wireless link can be free space point-to-point optical links.

The wireless communication system 100 comprises a plurality of access points (APs) 120 and one or more network devices or end devices (EDs) 110. In the example of FIG. 1, API and AP2 are the access points according to the present invention, which comprise at least two concurrent air interfaces. One is for optical wireless communication, or preferably Li-Fi communication, and the other is for RF communication, or preferably Wi-Fi communication, which may be in accordance with IEEE 802.1 In, IEEE 802.1 lac and/or IEEE 802.1 lax or WiFi 6, or indoor cellular communication. As a wireless communication technology for local area networking, optical wireless, or Li-Fi, plays a similar role as Wi-Fi or indoor cellular to provide the last meters connectivity. However, because of the different signal propagation properties, the coverage area of an RF-based access point is typically much bigger than the coverage area of a Li-Fi access point. On the other hand, the optical wireless communication has the potential to provide higher data rate and has the intrinsic security benefit resulted from a direct-line-of-sight channel. Thus, it is beneficial to provide the at least two air interfaces concurrently by an access point to leverage the advantages from both technologies.

To provide an optical wireless air interface, the AP 120 may be connected to one or multiple optical front ends or optical transceivers (TRX). The shadowed trapezoids illustrate field-of-views (FoVs) or coverage of an individual optical front end. Only when a mobile end device or ED 110 is located in the coverage of the optical link (within the trapezoid of the AP), will it be able to establish an optical wireless link with that AP 120. In addition to the wireless optical air interface, the AP 120 also provides RF air interface illustrated by radio wave. Usually the RF wireless link has a much larger coverage area because of the propagation property of a RF signal and the antenna characteristic, such as that of an omni-directional antenna.

The two concurrent air interfaces may operate in a coordinated, instead of completely independent, manner. In a first option, in addition to other communication data sent via the RF air interface, the access point may use the RF air interface to provide control information related to the setup of the wireless optical air interface to the mobile end device. Considering the large coverage of a RF communication link versus the relatively small coverage area of an optical wireless link, this option may enable the mobile end device to prepare for an optical link before reaching the actual coverage of the optical link. The control information may comprise at least one of: a wavelength configuration parameter, a frequency channel control parameter, an orientation control parameter, an authentication code, and a modulation and/or coding parameter.

In a second option, the two air interfaces may be used in combination to further improve the throughput. For example, when a mobile end device is within the coverage of both the RF link and the optical wireless link, the access point may send data via packet aggregation over the two air interfaces. This means that for a certain application or communication session, data packets are split into two streams to be sent via the RF link and the optical wireless link, respectively. In this scenario, the mobile end device also needs to enable the two links concurrently, instead of supporting only one selected communication mode in the default setup. Furthermore, when hardware resource is not a limitation to the mobile end device, the two streams (RF and optical) may also be extended to more than two streams, such as the optical link with two active RF links (Wi-Fi and Cellular).

It may also be a further option that the same data is transmitted via the two concurrent air interfaces. This can be quite beneficial for providing a smooth handover when the mobile end device moves out of the LOS area for optical wireless communication with the access point when it has an active optical wireless link at that moment. When the same data are transmitted via the RF communication link, the mobile end device can simply handover from an optical link to an RF link. To provide the at least two concurrent air interfaces at the access point, different system setups may be adopted. It may be two dedicated transceivers, one operating as an RF transceiver and the other operating as an optical wireless transceiver. Depending on if the transceiver is single-chip or not, a few examples of the system setup are illustrated in Fig. 2 - Fig. 4. In a first option, the two concurrent air interfaces may be provided by two identical RF transceivers (TRX), such as single-chip Wi-Fi transceivers or cellular transceiver. One RF transceiver is connected directly to the antenna to provide the RF air interface. And the other RF transceiver is connected to an optical front end (OFE) via a conversion circuit, as indicated by CC in FIG. 2. The conversion circuit may comprise a mixer, a local oscillator to generate a local carrier with the same frequency as the transmitting or receiving RF signals, or an external carrier signal obtained from the RF transceiver. The conversion circuit is configured to either down-convert an RF output signal from the RF transceiver to a baseband signal for input to the optical front end in a transmitter chain, or up- convert a baseband output signal from the optical front end to an RF signal for input to the RF transceiver in a receiver chain.

In a second option, the optical wireless transceiver comprises one dedicated circuit operating as a baseband module, shown as DBB block in Fig. 3, and an optical front end (OFE). The baseband module may be a dedicated baseband module according to an optical communication standard. It may also be reused from another communication technology that has similar baseband processing as the optical wireless communication. For example, the baseband module may be originally designed for RF communication, such as Wi-Fi or cellular communication, or another communication protocol, such as power line communication (PLC). By using different configuration parameters, the baseband module originally designed for another communication protocol may be used for the baseband processing in the optical wireless communication.

In the third option as shown in FIG. 4, both the RF transceiver and the optical transceiver comprise more than one component. For the RF transceiver, it has one dedicated circuit for use as a baseband module, and one dedicated circuit for use as analog front end. Similarly, the optical transceiver has one baseband module and one optical front end. The baseband module in the optical transceiver may be the same as the one in the RF transceiver, but it may also be a different one. As an example, it may well be that the RF transceiver is to carry out indoor cellular communication, and the optical transceiver has the same baseband module reused from cellular communication. In another example, the RF transceiver is to carry out Wi-Fi communication with a baseband module dedicated to Wi-Fi technology, while the optical transceiver reuses a baseband module from a cellular communication technology or a PLC communication technology. For the compatibility of a certain baseband module to the optical transceiver, it is important that the proper modulation and coding schemes required by an optical communication standard can be supported, and the required data rates or signal processing speeds can be satisfied as well.

The mobile end device may adopt the same system setup as the access point. However, given the mobile end device may confront strict requirements on performance, size and cost, it may be more practical that the mobile end device builds up the optical transceiver by reusing some existing hardware components on the mobile end device, and to just enable one communication link at a time. Then it may well be that the same RF transceiver is used in both RF communication and optical communication, or part of the RF transceiver is reused in the optical communication. It may also be that part of another RF transceiver that is not in use for the indoor environment is used for indoor optical communication. Two possible system setup examples for the mobile end device are shown in FIG. 5 and FIG. 6.

In FIG. 5, by controlling the switch, the same RF transceiver is either connected to the antenna for carrying out RF communication or connected to OFE via a conversion circuit, indicated as CC in the figure, for carrying out optical wireless communication. Similar to the conversion circuit aforementioned for the access point, the conversion circuit may comprise a mixer, a local oscillator to generate a local carrier with the same frequency as the transmitting or receiving RF signals, or an external carrier signal obtained from the RF transceiver. The conversion circuit is configured to either down- convert an RF output signal from the RF transceiver to a baseband signal for input to the optical front end in a transmitter chain, or up-convert a baseband output signal from the optical front end to an RF signal for input to the RF transceiver in a receiver chain. The RF transceiver may also be a different RF transceiver for the RF communication and the optical communication.

In FIG. 6, the RF transceiver is not a single-chip radio, but comprises two separate components, the baseband module or DBB and the analog front end (AFE) module or radio frequency integrated circuit (RFIC). The same DBB module also fulfills the signal processing requirement of optical communication. And hence, the switch after the DBB module may be controlled to adaptively connect to either the AFE or OFE to enable different communication modes.

The proposed setup for the mobile end device may be understood as a new method to integrate Li-Fi into a smartphone, a tablet, a laptop, or another mobile electronic device. The Li-Fi transceiver is mainly built with existing hardware and software resources that are already available in the mobile devices, such as the cellular digital baseband module. The 5G baseband is not used indoor when a 5G small cell is absent. And then, it may be reused for Li-Fi communication with an additional Li-Fi optical frontend. The additional Li- Fi optical frontend may be connected, as an add-on module, to a smartphone, a tablet, a laptop, or another mobile electronic device. In a further option, some existing optical components in a smartphone, a tablet, a laptop, or another mobile electronic device, such as a Flash-LED, a brightness sensor, or a time-of-flight (ToF) sensor, may also be reused for optical communication.

FIG. 7 schematically depicts basic components of an access point of the present invention. The access point 120 comprises at least an optical transceiver 300 and an RF transceiver 400, which are configured to carry out optical wireless communication and RF wireless communication, respectively. The RF transceiver may be a single chip radio. The RF transceiver may also comprise multiple chips or modules each providing different functions. In one example, it may comprise one chip operating as digital baseband or modem, and one chip operating as analog front end or RFIC. Similarly, the optical transceiver may also comprise multiple modules.

As shown in the example of FIG. 8 and FIG. 9, the optical transceiver comprises an optical front end (OFE) module 310 and a baseband module 320. The baseband module 320 comprises may comprise a dedicated integrated circuit 321 operating as a baseband modem. The dedicated integrated circuit 321 may be a baseband chip dedicated for optical communication. It may also be a baseband chip reused from another communication technology, such as PLC, Wi-Fi, or Cellular communication. In the example of FIG. 9, the baseband module 320 comprises another RF transceiver 410 and a conversion circuit 322, and the conversion circuit 322 is configured to carry out bi-directional signal conversion between the RF transceiver 410 and the OFE 310. So that, the conversion circuit 322 is configured to down-convert the RF output signal from the RF wireless transceiver 410 to a baseband signal for input to the OFE 310, and to up-convert a baseband output signal from the OFE 310 to an RF signal for input to the RF transceiver 410. For example, for the RF wireless transceiver 410, the output and input signals operate at the radio frequency bands, such as 2.4GHz or 5GHz band, depending on the standards. For the optical front end, the expected interfacing signals towards the remaining part of the optical transceiver operate at the baseband without a carrier. Thus, the conversion circuit 322 is employed to implement the frequency conversion to make the output and input signals of the RF transceiver 410 compatible to the input and output of the OFE 310.

FIG. 10 schematically depicts basic components of an end device 110 of the present invention. The end device 110 comprises at least an RF transceiver 420, a controller 115, an optical front end 301, and a baseband module 302. The controller 115 is configured to select one wireless communication mode out of the optical wireless communication and the RF wireless communication to connect to an access point 110. Different parameters may be considered for the controller to make the selection, such as according to at least one of: maximum data rates to be supported by the optical wireless communication and the RF wireless communication; a link quality evaluation parameter about an optical wireless communication link or an RF wireless communication link; an application requirement; a battery status parameter; and a user preference. The mobile end device 110 then connects to the access point 120 via the selected wireless communication mode.

The mobile end device 110 may optionally comprise a user interface, which can provide users with added convenience of status inquiry or operation of the device. For example, via the user interface, the user may query the status of a data link, such as the actual data rate, or set a preference of the user when selecting among an optical network and a RF network. In one example, the user may have a preference to establish a secure data link, and then the user may preferentially select the optical link when it is available.

Similar to FIG. 8 and FIG. 9, the baseband module 302 for optical communication in the mobile end device 110 may have different setups, as shown in FIG. 11 and FIG. 12. In FIG. 11, the baseband module 302 comprises a conversion circuit 322, which is configured to provide bi-directional signal conversion between the RF transceiver 420 and the OFE 301. Typically, this option is used when the RF transceiver 420 is a single chip RF radio. Then the controller 115 is configured to enable or disable the conversion circuit, depending on which communication mode is selected. In FIG. 12, the RF transceiver 420 is not a single chip radio but comprises at least a first integrated circuit 402 operating as a baseband modem and a second integrated circuit 401 operating as an analog front end or RFIC. In this scenario, the baseband module 302 of the optical transceiver is reused from the first integrated circuit 402 from the RF transceiver. Thus, the controller 115 is configured to control the first integrated circuit to connect to the second integrated circuit 401 for RF communication or to connect to the optical front end 301 for optical wireless communication.

The mobile end device 110, only supports one communication mode at a time. Thus, it is beneficial to reuse hardware components between the two modes (e.g. an optical communication mode and an RF communication mode), in view of power consumption, size and cost.

In a further option, the optical transceiver may reuse the hardware components from another communication technology that was not enabled in the current wireless communication system. For example, the mobile end device may have a Wi-Fi transceiver with either single chip or multiple chip solution. In addition to the Wi-Fi transceiver, the mobile end device also has cellular communication capability. The cellular communication radio is of two-chip solution, one baseband chip and one AFE chip or RFIC chip. In a certain environment, the cellular link may not be available anymore, and there is no cellular small cell deployment or the cellular base station signals are not available. The mobile end device may adaptively connect the baseband chip from the cellular radio to the optical front end to build up the optical transceiver for the indoor environment. Thus, it may well be that the mobile end device can support Wi-Fi communication and optical communication concurrently for throughput enhancement, such as via packet aggregation. For power consumption reason, the mobile end device may also just enable one communication mode according to a certain selection. And for security reason, the mobile end device may also preferentially select one communication mode rather than the other.

With regard to this further option, a detailed example on the system setup is provided as follows:

Setup of a Li-Fi enabled 5G smartphone:

• 5G smartphone may be configured for use of the present invention by adding a switch and an OFE. Here we assume that no 5G indoor infrastructure is provided, and thus, 5G is used only for outdoor data communication and all the 5G components are unused in the indoor environment. For example, the 5G baseband chip includes a Digital Signal Processor/Processing Unit for OFDM modulation and demodulation. The switch is controlled by the controller to control the baseband chip and connect it alternatively to the 5G front end or the OFE. The OFE can be part of the smartphone, such as via a pop-up or in-display solution, or it may be connected as an add-on module.

• Li-Fi communication link may be used for secure data communication between the smartphone and the access point for the indoor environment.

• Wi-Fi may be used for other data communication between the smartphone and the access point or alternatively for management or control data, such as for navigation/positioning (coded light can also be used as an addition). Setup of a Li-Fi enabled laptop:

• A conventional laptop may be configured for use of the present invention by adding several components, a peripheral Component Interconnect Express (PCIe) card with 5G baseband chip and an OFE;

• The OFE may be integrated into a laptop via a moveable pop-up configuration.

• Li-Fi communication link may be used for secure data communication between the laptop with PCIe card and the access point for the indoor environment.

• Wi-Fi may be used for other data communication between the laptop and the access point or be used for management or control data, such as for navigation/positioning.

FIG. 13 shows a flow chart of a method 500 of an access point 120 in a wireless communication system. The method 500 comprises the access point 120 providing a first air interface based on optical wireless communication technology in step S501; and providing a second air interface based on Radio Frequency, RF, wireless communication technology in step S502. The first air interface and the second air interface are provided concurrently by the access point 120.

FIG. 14 shows a flow chart of a method 600 of an end device 110 in a wireless communication system 100. The method 600 comprises the end device 110 communicating over an RF wireless communication link in step S601 and communicating over an optical wireless communication link in step S602. In step S603, the end device 110 selects one wireless communication mode out of the optical wireless communication and the RF wireless communication to connect to an access point, and wherein the selection is according to at least one of: maximum data rates to be supported by an optical wireless communication link and an RF wireless communication link; a link quality evaluation parameter about an optical wireless communication link or an RF wireless communication link; an application requirement; a battery status parameter; and a user preference. Then in step S604, the end device 110 connects to the access point 120 via the selected wireless communication mode.

The methods according to the invention may be implemented on a computer as a computer implemented method, or in dedicated hardware, or in a combination of both.

Executable code for a method according to the invention may be stored on computer/machine readable storage means. Examples of computer/machine readable storage means include non-volatile memory devices, optical storage medium/devices, solid-state media, integrated circuits, servers, etc. Preferably, the computer program product comprises non-transitory program code means stored on a computer readable medium for performing a method according to the invention when said program product is executed on a computer.

Methods, systems, and computer-readable media (transitory and non- transitory) may also be provided to implement selected aspects of the above-described embodiments.

The term “controller” is used herein generally to describe various apparatus relating to, among other functions, the operation of one or more network devices or coordinators. A controller can be implemented in numerous ways (e.g., such as with dedicated hardware) to perform various functions discussed herein. A “processor” is one example of a controller which employs one or more microprocessors that may be programmed using software (e.g., microcode) to perform various functions discussed herein. A controller may be implemented with or without employing a processor, and also may be implemented as a combination of dedicated hardware to perform some functions and a processor (e.g., one or more programmed microprocessors and associated circuitry) to perform other functions. Examples of controller components that may be employed in various embodiments of the present disclosure include, but are not limited to, conventional microprocessors, application specific integrated circuits (ASICs), and field-programmable gate arrays (FPGAs).

In various implementations, a processor or controller may be associated with one or more storage media (generically referred to herein as “memory,” e.g., volatile and non-volatile computer memory such as RAM, PROM, EPROM, and EEPROM, compact disks, optical disks, etc.). In some implementations, the storage media may be encoded with one or more programs that, when executed on one or more processors and/or controllers, perform at least some of the functions discussed herein. Various storage media may be fixed within a processor or controller or may be transportable, such that the one or more programs stored thereon can be loaded into a processor or controller so as to implement various aspects of the present invention discussed herein. The terms “program” or “computer program” are used herein in a generic sense to refer to any type of computer code (e.g., software or microcode) that can be employed to program one or more processors or controllers.

The term “network” as used herein refers to any interconnection of two or more devices (including controllers or processors) that facilitates the transport of information (e.g. for device control, data storage, data exchange, etc.) between any two or more devices and/or among multiple devices coupled to the network.

Claims

CLAIMS:

1. A wireless communication system (100) comprising: an access point (120) comprising: o a first optical transceiver configured to provide a first air interface based on optical wireless communication; and o a first Radio Frequency, RF, wireless transceiver configured to provide a second air interface based on RF wireless communication; and wherein the access point (120) is configured to provide the first air interface and the second air interface concurrently; and an end device (110) comprising: o a second RF wireless transceiver (420) configured to carry out RF wireless communication; o a first baseband module (302) is selectively routed to enable optical wireless communication or another wireless communication; o a first optical front end (301) configured to connect to the first baseband module (302) to carry out optical wireless communication; o a controller (115) configured to select one wireless communication mode out of the optical wireless communication and the RF wireless communication to connect to the access point, and wherein the selection is according to at least one of:

^■ a battery status parameter; and

^■ a user preference; and wherein the end device (110) is configured to connect to the access point (120) via the selected wireless communication mode, and when the optical wireless communication is selected, the second RF wireless transceiver is reused partially or in its entirety to enable the optical wireless communication.

2. The wireless communication system (100) of claim 1, wherein the RF wireless communication and/or the other wireless communication is based on Wi-Fi technology.

3. The wireless communication system (100) of claim 1, wherein the RF wireless communication and/or the other wireless communication is based on indoor 5G cellular technology.

4. The wireless communication system (100) of claim 1, wherein the access point (110) is further configured to send a control signal via the RF wireless communication for setting up the optical wireless communication.

5. The wireless communication system (100) of claim 1, wherein the access point (110) is further configured to send data via packet aggregation over the two air interfaces.

6. An end device (110) in a wireless communication system (100), the end device (110) comprising: a second Radio Frequency, RF, wireless transceiver (420) configured to carry out RF wireless communication; a first baseband module (302) is selectively routed to enable optical wireless communication or another wireless communication; a first optical front end (301) configured to connect to the first baseband module (302) to carry out optical wireless communication; a controller (115) configured to select one wireless communication mode out of the optical wireless communication and the RF wireless communication to connect to an access point, and wherein the selection is according to at least one of: o a battery status parameter; and o a user preference; and wherein the end device (110) is configured to connect to the access point (120) via the selected wireless communication mode; and when the optical wireless communication is selected, the second RF wireless transceiver is reused partially or in its entirety to enable the optical wireless communication.

7. The end device (110) of claim 6, wherein the first baseband module (302) comprises a conversion circuit (322) that comprises at least a mixer, and wherein the baseband module is configured to connect to the second RF wireless transceiver: - to down-convert an RF output signal from the second RF wireless transceiver to a baseband signal for input to the first optical front end; and

- to up-convert a baseband output signal from the first optical front-end to an RF signal for input to the second RF wireless transceiver.

8. The end device (110) of claim 7, the end device (110) is further configured to switch between the optical wireless communication and the RF wireless communication by enabling and disabling the conversion circuit.

9. The end device (110) of claim 6, wherein the second RF wireless transceiver comprising a first integrated circuit (402) operating as a baseband modem and a second integrated circuit (401) as an RF front end; and wherein the first baseband module (302) is reused from the first integrated circuit (402) of the second RF wireless transceiver (420).

10. The end device (110) of claim 9, the end device (110) is further configured to switch between the optical wireless communication and the RF wireless communication by adaptively connecting the first integrated circuit of the second RF wireless transceiver to the first optical front end or to the second integrated circuit of the second RF wireless transceiver.

11. A method (600) of an end device (110) in a wireless communication system (100), the method (600) comprising the end device (110): carrying out (S601) RF wireless communication; carrying out (S602) optical wireless communication; selecting (S603) one wireless communication mode out of the optical wireless communication and the RF wireless communication to connect to an access point, and wherein the selection is according to at least one of: o a battery status parameter; and o a user preference; and connecting (S604) to the access point (120) via the selected wireless communication mode; wherein when the optical wireless communication is selected, the second RF wireless transceiver is reused partially or in its entirety to enable the optical wireless communication.

12. A computing program comprising code means which, when the program is executed by an end device (110) comprising processing means, cause the processing means of the end device (110) to perform the method of claim 11.