Holder for optical transmitter providing optical beam cutting

Abstract

A holder (100) including a fastening means (110) configured to fix an optical transmitter for optical wireless communication, and a mechanical side shield (120) configured to shield a portion of the beam coverage zone of the optical transmitter with a straight cut.

Description

[Technical Field]

[0001] The present invention relates to the field of optical wireless communications, such as Li-Fi communications. Among other things, various devices, systems, and methods are disclosed herein for holders that secure optical transmitters and provide optical beam cutting. [Background technology]

[0002] As more and more electronic devices, such as laptops, tablets, and smartphones, are able to connect to the Internet wirelessly, wireless communications are facing unprecedented requirements regarding data rates and link quality, and these requirements continue to increase year by year, taking into account the new digital revolution associated with the Internet-of-Things (IoT). Radio frequency technologies, such as Wi-Fi®, have limited spectrum capacity to accommodate this revolution.

[0003] Meanwhile, optical wireless communication (OWC) has attracted increasing attention due to its intrinsic security enhancements and its ability to support higher data rates within the available bandwidth of the visible, ultraviolet (UV), and infrared (IR) spectrum. Depending on the wavelength used, such technologies are also sometimes referred to as coded light, light fidelity (LiFi), visible light communication (VLC), or free-space optical communication (FSO). Because OWC or Li-Fi is directional and shielded by light blocking materials, it offers the potential to deploy more access points in densely populated areas compared to Wi-Fi by spatially reusing the same bandwidth. These key advantages over wireless radio frequency communication make OWC or Li-Fi a promising secure solution to relieve pressure on the crowded radio spectrum for IoT applications and indoor wireless access. Other potential advantages of Li-Fi include guaranteed bandwidth for a given user and its ability to function safely in areas prone to electromagnetic interference. Li-Fi is therefore a very promising technology to enable the next generation of immersive connectivity.

[0004] Due to the line-of-sight requirements of optical wireless communications, the coverage area of ​​a single optical cell is typically limited compared to an RF-based cell. Therefore, to provide sufficient coverage in an area, multiple optical cells are typically deployed. However, adjacent optical access points (APs) may interfere with each other if there is overlap between the wavelengths used by the two APs and / or if two APs transmit simultaneously.

[0005] One way to allow two wireless optical networks to coexist in the same area without interference is to use separate wavelengths for each network. However, this solution has several limitations and disadvantages: - limitations on the number of "off the shelf" wavelengths in the IR spectrum: only a few LEDs can offer reasonably high powers that guarantee a large coverage (i.e. 850 nm and 940 nm); - In order to provide sufficient attenuation of undesired wavelengths, an IR filter (low-pass, high-pass, or band-pass) must be placed in front of the photoreceiver, and these IR filters are expensive; - Performance degradation over temperature: LEDs typically exhibit a peak wavelength shift over temperature (i.e., 25 nm wavelength shift at a Delta Temperature of 70°C), which translates into optical receive power loss due to the fixed cutoff frequency of the IR filter.

[0006] Another way to enable the coexistence of two wireless optical networks in the same area without interference is to apply the channel access control method of time division multiple access (TDMA). Some baseband modules used in optical wireless communications have controllable time slots. For example, by synchronizing the baseband modules, it is possible to schedule the emission of light from multiple neighboring optical APs by allowing only one optical AP to emit light at a time.

[0007] US10992380B2 relates to a system for transferring data between a rotating element and a fixed element by wireless optical communication.

[0008] Japanese Patent Application Laid-Open No. 8-97768 relates to an optical signal transmitting unit that amplifies a received optical signal to a predetermined level and emits the signal, and an optical signal receiving unit that receives / detects a modulated optical signal, which are provided at the top and bottom of an optical repeater that amplifies the received optical signal to a predetermined level and emits it into space, and an optical diffusion plate that diffuses the emitted optical signal into space is provided in an appropriate position on the optical signal transmitting unit. Summary of the Invention [Problem to be solved by the invention]

[0009] To provide good coverage in an area, multiple optical cells are typically deployed to access one or more external networks. As mentioned above, the coexistence of multiple optical APs in the same area can be solved by using wavelength-division multiplexing (WDM) or TDMA between the optical APs. However, such solutions introduce additional system complexity.

[0010] In view of the above, the present disclosure is directed to an apparatus and system for providing a simple and efficient solution for controlling optical beam shape for interference avoidance in optical wireless communication systems. In particular, the object of the present invention is achieved by an optical access point as set forth in claims 1 and 6, respectively. [Means for solving the problem]

[0011] According to a first aspect of the present invention, there is provided an optical access point, the optical access point including: an optical transceiver configured to perform optical wireless communication with an end device; and a holder including fastening means configured to secure an optical transmitter for the optical wireless communication, and a mechanical side shield having a straight edge for shielding a portion of a beam coverage zone of the optical transmitter with a straight cut.

[0012] The mechanical side shields are made of a type of light-blocking material, such as opaque metal, plastic, and wood, etc. A portion of the light beam emitted by the optical transmitter is blocked by the mechanical side shields with a straight-line cut.

[0013] The holder may be placed on a support surface, such as a floor, a table, or other piece of furniture. Alternatively, the holder may be used to fix the light transmitter to a mounting surface, such as to suspend the light transmitter from a ceiling. In this case, the holder may include additional fastening means for this function.

[0014] The holder may also be used to secure the optical transceiver to create optical beam cutting to avoid interference on both the uplink and downlink between adjacent optical communication zones.

[0015] The mechanical side shield has at least one straight edge for shielding a portion of the beam coverage zone of the optical transmitter with a straight cut.

[0016] Preferably, the mechanical side shield is rectangular in shape.

[0017] Considering a typical cone beam, it is preferable to make the mechanical side shields rectangular in shape to provide a straight optical cut to the beam footprint.

[0018] If the light cut is along a straight line, other shapes may be used, for example, one or more sides of the mechanical side shield may be curved.

[0019] Beneficially, the mechanical side shields have an adjustable size and / or orientation.

[0020] Considering that different light sources and different lenses may be used in the optical transmitter, it is desirable for the holder to be able to provide more flexibility.

[0021] As one option, the mechanical side shield may have an adjustable size, such as the mechanical side shield further including a folding or sliding portion.

[0022] As another option, the mechanical side shields may have an adjustable orientation, in which case the portion of the beam area that is blocked compared to the maximum beam area supported by the optical transmitter can be easily controlled by adjusting the orientation of the mechanical side shields.

[0023] The two options may be used independently or in combination to accommodate different application scenarios, such as different layouts of the deployment area or different optical transmitters including different light sources and / or lenses.

[0024] In one setup, the fastening means is configured to secure the optical transmitter in a tilted position with respect to a plane perpendicular to the mounting or support surface of the holder.

[0025] The tilted position may be determined depending on the coverage area to be achieved, the beam angle of the optical transmitter, and the distance from the optical transmitter to the target end device.

[0026] As an example, if the optical transceiver has a beam angle of ±35 degrees, the tilt angle of the transceiver is preferably 30 degrees from vertical to enable vertical communication as the transceiver.

[0027] The tilt angle may be adjustable so that the tilted position can be reconfigured depending on the actual beam angle to be used and the actual deployment requirements.

[0028] As one option, the tilt angle of the fastening means may be controlled independently of the orientation of the mechanical side shield. As another option, the mechanical side shield may be coupled to the fastening means, in which case the tilt angle of the fastening means will also determine the orientation of the mechanical side shield.

[0029] Advantageously, the fastening means are configured to releasably secure the optical transmitter.

[0030] The holder may be permanently attached to a mounting or support surface, in which case the light transmitter is conveniently removably arranged on the fastening means.

[0031] According to a second aspect of the present invention, there is provided an optical access point including two or more optical transceivers configured to perform optical wireless communication with one or more end devices, fastening means configured to fix two or more optical transmitters for the optical wireless communication, and a holder including two or more mechanical side shields each having a straight edge for shielding a part of a beam coverage zone of each of the two or more optical transmitters with a straight cut.

[0032] In order to provide as complete coverage of the area as possible, it is beneficial for two or more adjacent optical cells to be close to each other, but their mutual interference can be reduced. Therefore, the holder according to the second aspect can be used to meet this requirement, in which two or more adjacent optical transmitters are fixed to the same holder, and the beam area of ​​each optical transmitter is controlled by the corresponding mechanical side shield.

[0033] Depending on the target coverage area and the number of optical transmitters or transceivers to be deployed, the holder may be constructed as a double holder, triple holder, or multiple holder. The use of either type of holder, or a combination of different types of holders, depends on the layout of the target coverage area.

[0034] The holder may also be used to secure two or more optical transceivers to create optical beam cutting for the two or more optical transceivers to avoid interference on both the uplink and downlink between any two adjacent optical communication zones.

[0035] Preferably, each mechanical side shield is rectangular in shape.

[0036] Beneficially, each mechanical side shield has an adjustable size and / or orientation.

[0037] In one setup, the fastening means is configured to secure each optical transmitter in an inclined position relative to a plane perpendicular to the mounting or support surface of the holder.

[0038] Advantageously, the fastening means are configured to secure the two or more optical transmitters in a manner that avoids overlap between the beam coverage zones of any two of the two or more optical transmitters.

[0039] Preferably, the fastening means is further configured to secure two or more optical transmitters together to generate full coverage of a targeted communication area.

[0040] By controlling one or more of the tilt angle of the optical transmitter, the size and / or orientation of the two or more mechanical side shields, the fastening means may be configured to secure the two or more optical transmitters to avoid overlap between the beam coverage zones of any two optical transmitters and to provide complete optical wireless communication coverage of the target area.

[0041] Advantageously, the fastening means are configured to releasably secure each optical transmitter.

[0042] The holder may be permanently attached to a mounting or support surface, in which case the light transmitter is conveniently removably arranged on the fastening means.

[0043] According to a third aspect of the present invention, there is provided an optical access point, comprising: an optical transceiver configured to perform optical wireless communication with an end device; and a holder according to the present invention configured to fix the optical transceiver and to shield a portion of a beam coverage zone of the optical transceiver.

[0044] 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 physical access devices may typically, but not necessarily, be located in lighting fixtures, and a logical access point may be connected to one or more physical access devices each located in one or more lighting fixtures. An access point may thereby provide services to one or more network devices or end devices associated with it.

[0045] An optical wireless communication (OWC) access point, or Li-Fi access point, provides electronic devices or end devices within a corresponding optical cell with access to external networks via optical wireless links, and can simultaneously support bidirectional optical links with two or more end devices.

[0046] Optical wireless communication may be performed in the visible, ultraviolet (UV), and infrared (IR) spectrum. Thus, optical wireless communication is sometimes referred to as Li-Fi communication or visible light communication (VLC). An optical transceiver may include at least a light source for optical data transmission and a light detector for optical data reception. The light source or light emitter may be a light-emitting diode (LED), a laser diode, a vertical-cavity surface-emitting laser (VCSEL), or an edge-emitting laser diode (EELD). Preferably, the light source includes at least one of an LED and a VCSEL. The light detector, also referred to as a photodetector or photosensor, is a photodiode, which may be a PIN diode, an avalanche photodiode (APD), or a photomultiplier.

[0047] According to a further aspect of the present invention, there is provided an optical access point, the optical access point including two or more optical transceivers configured to conduct optical wireless communication with one or more end devices, and a holder according to the present invention configured to secure the two or more optical transceivers and to shade a portion of each beam coverage zone of each of the two or more optical transceivers.

[0048] An optical AP may also include more than one optical transceiver with the help of a double, triple or multi-holder according to the present invention.

[0049] Advantageously, the optical access point further includes two or more communication interfaces connected to two or more networks, and at least two of the two or more optical transceivers are configured to provide connection to different ones of the two or more networks.

[0050] In some application scenarios, end devices within the same area may need to access different external networks, which may have different domains, security levels, and / or priority levels. Example use cases include scenarios where accessibility to both public and private networks within the same area needs to be provided, such as hotels, public sectors, and businesses. Other applications include military and defense, such as providing accessibility to multiple networks with different security levels. To provide connectivity to these multiple external networks within the same area, one or more of the two or more optical transceivers may be connected to different external networks.

[0051] The different external networks may be wired networks or wireless networks. Also, one of the external networks may be a wired network and another of the external networks may be a wireless network. The wired network may be an Ethernet, a power line communication (PLC) network, or a plastic optical fiber (POF) network. The wireless network may be based on a millimeter wave communication system or a 5G cellular network. [Brief explanation of the drawings]

[0052] In the drawings, like reference characters generally refer to the same parts throughout the different views. Also, the drawings are not necessarily to scale, emphasis instead generally being placed upon illustrating the principles of the invention. [Figure 1] 1 shows an example of a holder. [Figure 2] 1 shows a picture of the above example of a folder. [Figure 3] 1 shows an example of a holder. [Figure 4] 1 shows a picture of the above example of a folder. [Figure 5] 1 shows a block diagram of an optical access point. [Figure 6] 1 shows a block diagram of an optical access point. [Figure 7] 1 shows a block diagram of an optical access point. [Figure 8] 1 shows the coverage area of ​​an optical transceiver on surfaces at different distances from the optical transceiver. [Figure 9] 1 illustrates an interference scenario between two adjacent optical cells in a conventional system. [Figure 10] 1 shows the deployment of optical cells in a conventional system providing full coverage. [Figure 11] An example of installing an optical transceiver in a holder is shown. [Figure 12] 1 shows an example of the resulting coverage area of ​​two adjacent optical cells. [Figure 13] Measurements of achievable data rates at different distances to the access point and at different locations within the coverage areas of two adjacent optical cells are shown. [Figure 14] An example of arranging light cells in a rectangular area is shown. DETAILED DESCRIPTION OF THE INVENTION

[0053] The embodiments described below represent information to enable those skilled in the art to practice the embodiments. Upon reading the following description in light of the accompanying drawings, those skilled in the art will understand the concepts of the present disclosure and will recognize applications of these concepts not specifically addressed herein. It is understood that these concepts and applications fall within the scope of the present disclosure.

[0054] 1 shows an example of a holder 100. The holder 100 includes a fastening means 110 configured to fix an optical transmitter for optical wireless communication, and a mechanical side shield 120 configured to shield a part of the beam coverage zone of the optical transmitter with a straight cut.

[0055] 1, the holder 100 includes additional fastening means that are used to attach the holder to a mounting surface, such as suspending the holder and optical transceiver from a ceiling. In an alternative scenario, the holder may not require additional fastening means if placed on a support surface, such as a tabletop.

[0056] The holder 100 may also be used to secure optical transceivers to create optical beam cutting to avoid interference between adjacent optical communication zones, both uplink and downlink.

[0057] Figure 2 shows the same picture of the holder 100 as in Figure 1. The beam shape of the optical transmitter is shown in shading. It can be seen that the mechanical side shield 120 provides a straight cut on one side of the beam.

[0058] 3 shows an example of a holder 200. The holder 200 includes a fastening means 210 configured to secure two or more optical transmitters for optical wireless communication, and two or more mechanical side shields 220, 220′ each configured to shield a portion of a beam coverage zone of an individual optical transmitter of the two or more optical transmitters with a straight cut.

[0059] The holder 200 may also be used to secure two or more optical transceivers to create optical beam cutting for the two or more optical transceivers to avoid both uplink and downlink interference between any two adjacent optical communication zones.

[0060] This example shows a double holder 200. As previously mentioned, a triple or multi-holder 200 may be used to secure three or more optical transceivers. The use of either type of holder, or a combination of different types of holders, depends on the layout of the target coverage area.

[0061] 3, the double holder 200 includes additional fastening means that are used to attach the holder to a mounting surface, such as suspending the holder 200 and optical transceiver from a ceiling. In an alternative scenario, the holder 200 may not have additional fastening means when placed on a support surface, such as on a table.

[0062] Figure 4 shows the same picture of the holder 200 as Figure 3. The beam shapes of the optical transmitters are shown in shading. It can be seen that the mechanical side shields 220, 220' provide straight cuts at the adjacent edges of the beams from the two optical transceivers.

[0063] 5 shows a block diagram of an optical access point 300. The optical access point 300 includes an optical transceiver 350 configured to perform optical wireless communication with an end device, and a holder 100 according to the present invention configured to fix the optical transceiver 350 and to shield a portion of the beam coverage zone of the optical transceiver 350.

[0064] The optical transceiver 350 may include at least a light source for optical data transmission and a light detector for optical data reception. The light source or light emitter may be a light-emitting diode (LED), a laser diode, a vertical-cavity surface-emitting laser (VCSEL), or an edge-emitting laser diode (EELD). Preferably, the light source includes at least one of an LED and a VCSEL. The light detector, also called a photodetector or photosensor, is a photodiode and may be a PIN diode, an avalanche photodiode (APD), or a photomultiplier.

[0065] 6 shows a block diagram of an optical access point 400. The optical access point 400 includes two or more optical transceivers 350, 350′ and a holder 200 according to the present invention. The optical transceivers 350, 350′ are configured to perform optical wireless communication with one or more end devices. The holder 200 is configured to secure the two or more optical transceivers 350, 350′ and to shade a portion of each beam coverage zone of each of the two or more optical transceivers 350, 350′.

[0066] 7 shows a block diagram of a further example optical access point 400. The optical access point 400 further includes two or more communication interfaces 460, 460′ connected to two or more networks, and at least two of the two or more optical transceivers 350, 350′ are configured to provide connections to different ones of the two or more networks.

[0067] In certain application scenarios, end devices within the same area may need to access different external networks, which may have different domains, security levels, and / or priority levels. Example use cases include scenarios where accessibility to both public and private networks within the same area needs to be provided, such as hotels, public sector, and businesses. Other applications include military and defense, such as providing accessibility to multiple networks with different security levels.

[0068] The two or more external networks may be wired networks or wireless networks. Also, one of the external networks may be a wired network and another of the external networks may be a wireless network. The wired network may be an Ethernet, a Power-Line Communication (PLC) network, or a Plastic Optical Fiber (POF) network. The wireless network may be based on a millimeter-wave communication system or a 5G cellular network.

[0069] Figure 8 shows an example of the coverage area of ​​an optical transceiver on surfaces at different distances from the optical transceiver. In this example, a circular beam is assumed, and the coverage area of ​​the optical cell has a nominal radius that increases with distance from the optical transceiver. Depending on the beam shape used by the system, the coverage area may have other shapes. Of course, the data rate provided to end devices located on a surface decreases as the distance from the optical transceiver increases. In this sense, deploying the AP farther away from the target end device allows for a larger coverage area, but the supported data rate may be lower.

[0070] In one example of an optical wireless communications (OWC) system, a ceiling-mounted OWC access point (AP) may be integrated with a luminaire for general lighting functions. This can be a good placement for the AP function, as luminaires are preferably positioned to uniformly and completely illuminate a space. To ensure coverage, beams from adjacent APs have overlapping regions, and end devices (EDs) located in such overlapping regions may experience interference when adjacent APs transmit simultaneously. Similarly, these EDs may also generate overlapping beams at the AP side, potentially causing interference with each other in the uplink.

[0071] Figure 9 illustrates an interference scenario between two adjacent optical cells in a conventional system. Optical access points AP1 and AP2 include optical transceivers TRX1 and TRX2, respectively, and the separation distance between the two transceivers is denoted as s in the figure. Also, the distance between the optical transceiver and the targeted end device is d. Area A represents the non-overlapping coverage area, and area B represents the overlapping area, i.e., the interference zone. The radius of the conventional optical cell is r MAX The width of the interference area is denoted by b, and correspondingly, the radius to the interference-free neighboring cell is a, which is r MAX Equivalent to -b.

[0072] Figure 10 shows the deployment of optical cells in a conventional system providing full coverage. Each circle represents an optical cell. Twelve optical cells are deployed to provide full coverage of a rectangular area. If an end device is located in the overlap area between any two or more adjacent optical cells, it will experience interference from two or more adjacent APs. Furthermore, in such conventional systems, it can be seen that there is always a trade-off in deployment design between coverage and interference. To achieve full coverage, overlapping or interference areas are inevitable.

[0073] Interference avoidance between multiple APs can be addressed using wavelength multiplexing or time division multiple access (TDMA). However, these conventional interference avoidance techniques have certain limitations and disadvantages, such as adding extra complexity and overhead to the system.

[0074] 11 shows an example of installation of the optical transceiver 350 in the holder 100. The black dots exemplarily indicate preferred positions for locating the light source and light sensor of the optical transceiver 350. The dashed lines indicate that the mechanical side shield 120 provides a vertical optical cut to the outgoing and incoming beams of the optical transceiver 350.

[0075] 12 shows an example of a coverage area resulting from two adjacent optical cells according to the present invention. The juxtaposition of two adjacent coverage zones, zone 1 and zone 2, is achieved by using a double holder 200 with two optical transceivers. If the two optical transceivers are connected to different external networks via separate communication interfaces 460, zone 1 and zone 2 provide different optical networks, such as two different LiFi networks, to end devices located in nearby areas.

[0076] FIG. 13 exemplarily illustrates measurement results of achievable data rates at different distances to the access point and at different locations within the coverage area of ​​two adjacent optical cells, such as Zone 1 and Zone 2 shown in FIG. 12. In this example, the maximum supported data rate is 200 Mbps. As shown in the figure, the data rate provided to an end device located on a surface decreases as the distance from the optical transceiver increases. In this sense, deploying the AP farther away from the target end device allows for a larger coverage area, but the supported data rate may be lower. In a double holder, two optical cuts are provided at adjacent edges of the two optical cells. It can be seen that an advantage of the disclosed solution is that the optical cut provided by the mechanical side shield 120 is independent of the distance between the EP and the transceiver, especially when the optical cuts are perpendicular.

[0077] 14 shows an example of deploying optical cells in a rectangular area. Depending on the shape and / or size of the overall surface to be covered by optical wireless communication, different combinations of single transceiver holders 100, double transceiver holders, or multi-transceiver holders 200 can be used. Further adjustments can be made by changing the size and / or orientation of the mechanical side shields of one or more holders, or by adjusting the fastening means of one or more holders to change the tilted position of the corresponding optical transceiver.

[0078] In this example, which has a rectangular coverage area, three APs 400, each with a double transceiver holder 200, are deployed in the center of the zone, and three APs 300, each with a single transceiver holder 100, are deployed at the top and bottom of the zone, respectively.

[0079] In this example, the APs 300, 400 are arranged in ceiling lighting fixtures at a horizontal pitch of 1.8 m and a vertical pitch of 3.6 m in the picture. If the shape and / or size of the room does not match the standard or default beam shape of the optical transceivers, further adjustments as described above can be made, such as adding more transceivers to the AP, changing the shape of the beam, adjusting the tilt position of the transceivers, changing the size and / or orientation of the mechanical side shields, etc.

Claims

1. an optical transceiver configured to communicate optically wirelessly with an end device; a fastening means configured to fasten an optical transmitter for optical wireless communication; and a mechanical side shield having a straight edge for shielding a portion of the beam coverage zone of the optical transmitter with a straight cut; a holder including: an optical access point.

2. The optical access point of claim 1 , wherein the mechanical side shield is rectangular in shape.

3. 3. The optical access point of claim 1 or 2, wherein the mechanical side shields have an adjustable size and / or orientation.

4. 4. An optical access point according to any one of claims 1 to 3, wherein the fastening means is configured to secure the optical transmitter in an inclined position with respect to a plane perpendicular to a mounting or support surface of the holder.

5. 5. The optical access point according to claim 1, wherein the fastening means is configured to removably secure the optical transmitter.

6. two or more optical transceivers configured to communicate optically wirelessly with one or more end devices; fastening means configured to fasten two or more optical transmitters for optical wireless communication; and two or more mechanical side shields, each having a straight edge for shielding a portion of a beam coverage zone of each of the two or more optical transmitters with a straight cut; a holder including: an optical access point.

7. The optical access point of claim 6 , wherein each mechanical side shield is rectangular in shape.

8. 8. The optical access point of claim 6 or 7, wherein each mechanical side shield has an adjustable size and / or orientation.

9. 9. An optical access point according to any one of claims 6 to 8, wherein the fastening means are configured to secure each optical transmitter in an inclined position relative to a plane perpendicular to a mounting or support surface of the holder.

10. 10. The optical access point of claim 6, wherein the fastening means is configured to secure the two or more optical transmitters so as to avoid overlap between beam coverage zones of any two of the two or more optical transmitters.

11. 11. The optical access point of claim 10, wherein the fastening means is configured to secure the two or more optical transmitters to generate full coverage of a targeted communication area.

12. 12. The optical access point according to any one of claims 6 to 11, wherein the fastening means are configured to releasably secure each optical transmitter.

13. 13. The optical access point of claim 6, wherein the optical access point comprises two or more communication interfaces connected to two or more networks, and at least two of the two or more optical transceivers are configured to provide connection to different ones of the two or more networks.

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