HK1170601A - Method and apparatus for dimming with rate control for visible light communications (vlc) - Google Patents

Description

Method and apparatus for rate controlled dimming of Visible Light Communication (VLC)

Cross Reference to Related Applications

This application claims the benefit of united states provisional application 61/243,862 filed on 9/18/2009, united states provisional application 61/243,819 filed on 9/18/2009, and united states provisional application 61/250,811 filed on 10/12/2009, the contents of which are incorporated herein by reference.

Background

Visible Light Communication (VLC) is a communication medium that wirelessly transmits data, such as voice data, digital data, and image data, using visible light, such as light having a wavelength in the range of approximately 400 to 700 nanometers (nm) that is visible to the unaided human eye. To transmit data using VLC, a visible light source, such as a fluorescent light bulb or Light Emitting Diode (LED), may be turned on and off or modulated in brightness at a very fast rate. A receiving device (e.g., a camera, an imager of a mobile phone, or a backlight sensor) may receive the brightness modulated light and convert it into data that the receiving device is capable of processing for use and/or entertainment by a user.

One of the main attractions of VLC is that visible light sources available for transmitting data to receiving devices are ubiquitous. For example, light fixtures, consumer electronics products with LED backlit displays, and other LEDs (such as indicator lights and traffic signals) include one or more sources of visible light. Thus, visible light sources have the potential to wirelessly transmit data to users located almost anywhere.

VLC may provide many benefits, for example, may free up a limited radio frequency bandwidth for other uses, as it does not require the use of radio frequency bandwidth. Furthermore, since light sources have been used for other purposes (e.g. providing illumination and displaying television programs, movies and data), light sources can easily be converted to transmitters by simply coupling the light source to a control device. However, a drawback of VLC is that it interferes with dimming.

VLC may be used in a variety of applications including, but not limited to, the categories listed in table 1 below.

TABLE 1

Node point	Definition of	Application example
			Infrastructure	Networked communication node installed in invariant location	VLAN, ATM machine
Moving object	Low mobility devices, which may include stationary devices	PDA
			Vehicle with a steering wheel	High mobility node associated with a transportation application	Automobile

Disclosure of Invention

A method and apparatus for dimming a luminary for lighting and data transmission in Visible Light Communication (VLC).

Drawings

A more detailed understanding can be derived from the following description of examples, taken in conjunction with the accompanying drawings, in which:

FIG. 1A is a system diagram of an exemplary communication system in which one or more disclosed embodiments may be implemented;

FIG. 1B is a system diagram of an exemplary wireless transmit/receive unit (WTRU) that may be used in the communication system shown in FIG. 1A;

FIG. 2 illustrates an IEEE 802.15.7 network topology including communication interfaces;

FIG. 3 illustrates an IEEE 802.15 topology stack;

FIG. 4 is a block diagram of VLC physical data flow using one illuminant;

figure 5 shows a multi-emitter architecture;

fig. 6 shows a walsh code tree used in VLC;

FIG. 7 shows an example of a data duty cycle;

FIG. 8 shows an example of average luminance of multiple modulations;

FIG. 9 illustrates the relationship between data duty cycle and desired dimming or brightness level;

FIG. 10 illustrates an embodiment of VLC in a MAC architecture;

FIG. 11 shows a proposed MAC Protocol Data Unit (PDU);

fig. 12 illustrates MAC multiplexing and multiple access;

FIG. 13 shows a flow diagram of a discovery process;

fig. 14 is an example of VLC dimming controlled by MAC; and

fig. 15 is a block diagram illustrating VLC including adaptation layer support.

Detailed Description

Fig. 1A is a block diagram of an exemplary communication system 100, which may implement one or more of the disclosed embodiments. The communication system 100 may be a multiple access system that provides content, such as voice, data, video, messaging, broadcast, etc., to a plurality of wireless users. Communication system 100 may enable multiple wireless users to access such content by sharing system resources, including wireless bandwidth. For example, communication system 100 may use one or more channel access methods, such as Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), Orthogonal FDMA (OFDMA), single carrier FDMA (SC-FDMA), and the like.

As shown in fig. 1A, the communication system 100 may include wireless transmit/receive units (WTRUs) 102a, 102b, 102c, 102d, AN Access Network (AN) or Radio Access Network (RAN)104, a core network 106, a Public Switched Telephone Network (PSTN)108, the internet 110, and other networks 112, although it is understood that the disclosed embodiments are applicable to any number of WTRUs, base stations, networks, and/or network elements. Each WTRU102 a, 102b, 102c, 102d may be any type of device configured to operate and/or communicate in a wireless environment. By way of example, the WTRUs 102a, 102b, 102c, 102d may be configured to transmit and/or receive wireless signals and may include User Equipment (UE), a mobile station, a fixed or mobile subscriber unit, a pager, a cellular telephone, a Personal Digital Assistant (PDA), a smartphone, a laptop, a netbook, a personal computer, a wireless sensor, a media transfer protocol (MTC) device, consumer electronics, and the like.

Communication system 100 may also include base station 114a and base station 114 b. Each base station 114a, 114b may be any type of device configured to wirelessly connect at least one of the WTRUs 102a, 102b, 102c, 102d to facilitate access to one or more communication networks, such as the core network 106, the internet 110, and/or the networks 112. By way of example, the base stations 114a, 114B may be Base Transceiver Stations (BTSs), node bs, evolved node bs, home evolved node bs, site controllers, Access Points (APs), wireless routers, and so forth. Although the base stations 114a, 114b are each depicted as a separate element, it is to be understood that the base stations 114a, 114b may include any number of interconnected base stations and/or network elements.

The base station 114a may be part of the RAN 104, which RAN 104 may also include other base stations and/or network elements (not shown), such as Base Station Controllers (BSCs), network controllers or Radio Network Controllers (RNCs), relay nodes, and so forth. Base station 114a and/or base station 114b may be configured to transmit and/or receive wireless signals within a particular geographic area, which may be referred to as a cell (not shown). The cell may be further divided into cell sectors. For example, the cell associated with base station 114a may be divided into three sectors. Thus, in one embodiment, the base station 114a may include three transceivers, i.e., one for each sector of the cell. In another embodiment, the base station 114a may use multiple-input multiple-output (MIMO) technology and, thus, may use multiple transceivers for each sector of the cell.

The base stations 114a, 114b may communicate with one or more of the WTRUs 102a, 102b, 102c, 102d over an air interface 116, which air interface 116 may be any suitable wireless communication link (e.g., Radio Frequency (RF), microwave, Infrared (IR), Ultraviolet (UV), visible light, etc.). Air interface 116 may be established using any suitable Radio Access Technology (RAT).

More specifically, as described above, communication system 100 may be a multiple access system and may use one or more channel access schemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, and the like. For example, the base station 114a in the RAN 104 and the WTRUs 102a, 102b, 102c may implement a wireless technology such as Universal Mobile Telecommunications System (UMTS) terrestrial radio access (UTRA), which may establish the air interface 116 using wideband cdma (wcdma). WCDMA may include communication protocols such as High Speed Packet Access (HSPA) and/or evolved HSPA (HSPA +). HSPA may include High Speed Downlink Packet Access (HSDPA) and/or High Speed Uplink Packet Access (HSUPA).

In another embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a wireless technology, such as evolved UMTS terrestrial radio access (E-UTRA), which may establish the air interface 116 using Long Term Evolution (LTE) and/or LTE-advanced (LTE-a) technologies.

In another embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement wireless technologies such as IEEE 802.16 (i.e., Worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000, CDMA20001X, CDMA2000EV-DO, temporary Standard 2000(IS-2000), temporary Standard 95(IS-95), temporary Standard 856(IS-856), Global System for Mobile communications (GSM), enhanced data rates for GSM evolution (EDGE), GSM EDGE (GERAN), and so forth.

The base station 114B in fig. 1A may be a wireless router, home nodeb, home enodeb, or access point, for example, and may facilitate wireless connectivity in a local area, such as a business office, home, vehicle, campus, etc., using any suitable access technology or RAT. In one embodiment, the base station 114b and the WTRUs 102c, 102d may implement techniques such as IEEE 802.11 to establish a Wireless Local Area Network (WLAN). In another embodiment, the base station 114b and the WTRUs 102c, 102d may implement a technology such as IEEE 802.15 to establish a Wireless Personal Area Network (WPAN). In yet another embodiment, the base station 114b and the WTRUs 102c, 102d may establish the pico cell or the femto cell using a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE-a, etc.). As shown in fig. 1A, the base station 114b may have a direct connection to the internet 110. Thus, the base station 114b may not have to access the internet 110 via the core network 106.

The RAN 104 may communicate with a core network 106, which core network 106 may be any type of network configured to provide voice, data, application, and/or voice over internet protocol (VoIP) services to one or more of the WTRUs 102a, 102b, 102c, 102 d. For example, the core network 106 may provide call control, billing services, mobile location-based services, pre-paid calling, internet connectivity, video distribution, etc., and/or perform high-level security functions, such as user authentication. Although not shown in fig. 1A, it should be understood that the RAN 104 and/or the core network 106 may communicate directly or indirectly with other RANs that employ the same RAT as the RAN 104 or a different RAT. For example, in addition to being connected to the RAN 104, which RAN 104 may be using E-UTRA radio technology, the core network 106 may also communicate with another RAN (not shown) using GSM radio technology.

The core network 106 may also act as a gateway for the WTRUs 102a, 102b, 102c, 102d to access the PSTN 108, the internet 110, and/or other networks 112. The PSTN 108 may include a circuit-switched telephone network that provides Plain Old Telephone Service (POTS). The internet 110 may include a global system of interconnected computer networks and devices that use common communication protocols, such as the Transmission Control Protocol (TCP), the User Datagram Protocol (UDP), and the Internet Protocol (IP) in the TCP/IP internet protocol suite. The network 112 may include wired or wireless communication networks owned and/or operated by other service providers. For example, the network 112 may include another core network connected to one or more RANs, which may employ the same RAT as the RAN 104 or a different RAT.

Some or all of the WTRUs 102a, 102b, 102c, 102d in the communication system 100 may include multi-mode capabilities, i.e., the WTRUs 102a, 102b, 102c, 102d may include multiple transceivers that communicate with different wireless networks over different wireless links. For example, the WTRU102c shown in fig. 1A may be configured to communicate with a base station 114a using a cellular-based radio technology and with a base station 114b using an IEEE 802 radio technology.

Figure 1B is a system diagram of an exemplary WTRU 102. As shown in fig. 1B, the WTRU102 may include a processor 118, a transceiver 120, a transmit/receive element 122, a speaker/microphone 124, a keypad 126, a display/touch screen 128, non-removable memory 130, removable memory 132, a power supply 134, a Global Positioning System (GPS) chipset 136, and other peripherals 138. It should be understood that WTRU102 may include any subcombination of the foregoing elements while remaining consistent with an embodiment.

The processor 118 may be a general purpose processor, a special purpose processor, a conventional processor, a Digital Signal Processor (DSP), a plurality of microprocessors, one or more microprocessors in association with a DSP core, a controller, a microcontroller, Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs) circuits, any other type of Integrated Circuit (IC), a state machine, or the like. The processor 118 may perform signal coding, data processing, power control, input/output processing, and/or any other functions that enable the WTRU102 to operate in a wireless environment. The processor 118 may be coupled to a transceiver 120, which transceiver 120 may be coupled to a transmit/receive element 122. Although fig. 1B shows processor 118 and transceiver 120 as separate components, it should be understood that processor 118 and transceiver 120 may be integrated together in an electronic package or chip.

Transmit/receive element 122 may be configured to transmit signals to a base station (e.g., base station 114a) or receive signals from a base station (e.g., base station 114a) via air interface 116. For example, in one embodiment, the transmit/receive element 122 may be an antenna configured to transmit and/or receive RF signals. In another embodiment, the transmit/receive element 122 may be an emitter/detector configured to transmit and/or receive, for example, IR, UV, or visible light signals. In yet another embodiment, the transmit/receive element 122 may be configured to transmit and receive both RF and optical signals. It should be appreciated that transmit/receive element 122 may be configured to transmit and/or receive any combination of wireless signals.

Furthermore, although transmit/receive elements 122 are shown in fig. 1B as separate elements, WTRU102 may include any number of transmit/receive elements 122. More specifically, the WTRU102 may use MIMO technology. Thus, in one embodiment, the WTRU102 may include two or more transmit/receive elements 122 (e.g., multiple antennas) for transmitting and receiving wireless signals over the air interface 116.

Transceiver 120 may be configured to modulate signals to be transmitted by transmit/receive element 122 and to demodulate signals received by transmit/receive element 122. As described above, the WTRU102 may have multi-mode capabilities. Thus, the transceiver 120 may include multiple transceivers that enable the WTRU102 to communicate via multiple RATs, such as UTRA and IEEE 802.11.

The processor 118 of the WTRU102 may be coupled to and may receive user input data from a speaker/microphone 124, a keypad 126, and/or a display/touch screen 128, such as a Liquid Crystal Display (LCD) display unit or an Organic Light Emitting Diode (OLED) display unit. The processor 118 may also output user data to a speaker/microphone 124, a keypad 126, and/or a display/touch screen 128. Further, processor 118 may access information from, and store data in, any type of suitable memory, such as non-removable memory 106 and/or removable memory 132. Non-removable memory 106 may include Random Access Memory (RAM), Read Only Memory (ROM), a hard disk, or any other type of memory device. The removable memory 132 may include a Subscriber Identity Module (SIM) card, a memory stick, a Secure Digital (SD) memory card, and so forth. In other embodiments, the processor 118 may access information from, and store data in, a memory not physically located on the WTRU102, such as in a server or home computer (not shown).

The processor 118 may receive power from the power supply 134 and may be configured to distribute and/or control the power to other components in the WTRU 102. The power source 134 may be any suitable device for powering the WTRU 102. For example, the power source 134 may include one or more dry cell batteries (e.g., nickel cadmium (NiCd), nickel zinc (NiZn), nickel metal hydride (NiMH), lithium ion (Li-ion), etc.), solar cells, fuel cells, and the like.

The processor 118 may also be coupled to a GPS chipset 136, which the GPS chipset 136 may be configured to provide location information (e.g., longitude and latitude) regarding the current location of the WTRU 102. In addition to or in lieu of information from the GPS chipset 136, the WTRU102 may receive location information from base stations (e.g., base stations 114a, 114b) via the air interface 116 and/or determine its location based on the timing of signals received from two or more neighboring base stations. It should be appreciated that the WTRU102 may obtain location information by any suitable location determination method while maintaining implementation consistency.

The processor 118 is further coupled to other peripherals 138, which may include one or more software and/or hardware modules that provide additional features, functionality, and/or wired or wireless connectivity. For example, the peripheral devices 138 may include an accelerometer, an electronic compass, a satellite transceiver, a digital camera (for images or video), a Universal Serial Bus (USB) port, a vibrating device, a television transceiver, a hands-free headset, BluetoothA module, a Frequency Modulation (FM) radio unit, a digital music player, a media player, a video game player unit, an internet browser, and so forth.

Fig. 2 shows an IEEE 802.15.7 network topology including a communication interface 200. The Core Network (CN)210 may be connected to the infrastructure node 225 via the Q interface 220 using techniques including, but not limited to, Power Line Communications (PLC) or ethernet. The infrastructure node may use R_xInterface 230 is connected to a fixed, mobile or vehicle node 235, said R_xThe interface 230 may be a VLC link. The R is_xThe interface 230 may be an inter-emitter interference for spatial multiplexing. P-interface 240 may indicate point-to-point (P2P) communication that does not include a connection to a network.

VLC may be used for various applications and topologies including P2P, infrastructure, and simplex (simplex), where each topology may include a special mode. The infrastructure topology may include an infrastructure mode that provides communication features while maintaining lighting as a basic function of the LED sources. Dimming can be achieved in this mode to maximize data throughput and multiplexing can be used to support multiple end users. Furthermore, interference from unintended light sources may be rejected in this mode. Also, infrastructure nodes in this mode may use R_xThe interface 230 performs linking.

In the P2P topology, the P2P mode may use spatial isolation to limit interference from other VLC sources. In which a maximum data rate can be achieved by eliminating the added signaling and physical layer redundancy. Also, the P2P nodes in this mode may be linked using P interface 240.

In addition to P2P and infrastructure mode, VLC may use simplex mode to allow visible light links to act as a toll-free (complementary) wireless access technology with unidirectional support. This may allow the visible light link to act as a unidirectional broadcast channel. Also, a fixed number of retransmissions may be repeated, independent of the external entity.

Fig. 3 shows an IEEE 802.15 topology stack 300. Including both physical layer (PHY)310 and MAC 320 layers. There may be a Logical Link Control (LLC) layer 330 above the MAC layer. In simplex mode, the Medium Access Control (MAC) protocol may provide for the reception of control information including Acknowledgements (ACKs) and channel quality measurements from external entities outside the MAC. Other LLC sub-layers may also be included in the VLC architecture 340.

Fig. 4 is a block diagram 400 of VLC PHY data flow including data band splitting and aggregation using a light emitter. In fig. 4, lights 405 are used to display separate data streams to illustrate interference in the communication channel. Bit stream x for use as a length-N input vector₁，x₂，x₃，...x_N407, where N is the size of the MAC Protocol Data Unit (PDU) is input into the PHY band splitter 410. Bit-stuffing "0" is used to guarantee that the length of the vector is N', which is a multiple of M, where M is the total number of data bands or colors:

equation [1 ]]

The bitstream 407 input into the band separator block 410 is denoted x₁，x₂，x₃，...x_N. Frequency converterThe band splitter 410 aggregates the bit streams across multiple data bands 415. The output of band splitter 410 is M data bands, b_m,415. Each data band includes data bits mapped by the band separator. The mathematical representation of the mapping of the data bits by the band separator can be determined by the following equation, which shows how the bits x are multiplexed into the bits b of each band:

b_m，k＝x_M(k-1)+mequation [2 ]]

1, 2, 3,.., X equation [3]

Equation [4 ]]

1, 2,., M equation [5]

Where k is the channel number, X is the total number of channels, m is the data band, and b_m，kIs data.

To provide maximum capacity in the infrastructure system when using multiple bands of light, the PHY separates and aggregates the data through a band separator 410. Each data symbol transmitted in parallel over the air interface is converted into a serial data stream starting from the symbol of the lowest wavelength band up to the highest wavelength band. In infrastructure topologies, support for multiple wavelengths or multiple frequency bands is provided. These bands may be associated with colors and different wavelengths of the visible spectrum, where the different wavelengths correspond to different colors of the visible spectrum. When the frequency bands are multiplexed together, the overlapping color (the overlapping color) is white light.

For each band m, the data is spread by a channelization code C (k, SF) in channelization block 420b_m，kThe channelization codes are specific to the luminaries, where (SF) is the spreading factor of the code, k is the channel number:

k is 0-0.ltoreq.SF-1 equation [6]

In other words, (SF) is the number of illuminants used and k is the index of the particular illuminant.

The scrambling code s may then be encoded in the scrambled or line code block 425_mOr a line code is applied to each data band. The unipolar data may then be converted in a Direct Current (DC) offset or unipolar conversion block 430 for each data band. The conversion of DC offset or to unipolar signaling is necessary to provide consistency in on/off keying (OOK) of the LED light sources.

To transmit data while maintaining the brightness of the luminary, dimming is implemented. Dimming is performed in the dimming block 435. The desired brightness level is received in the dimming block 435. A data duty cycle for the data transmission is determined based on the desired brightness level. A fill brightness value is determined based on the received brightness level. One of the fill brightness values "1" or "0" is added to the data by the single or multi-band LED device 440 that allows changes to be made to the data and illumination in the luminary before conversion to illumination.

Another aspect of VLC network topology concerns PHY band splitting and aggregation. For infrastructure VLC, single chip (band) based LEDs may be used for energy saving schemes, while three chip (band) (i.e., RGB) LEDs may provide enhanced data rates. For RGB, white light is still desired to serve as the basic function of illumination, meaning that all frequency bands are active. Thus, to maximize data capacity, each luminaire may use each frequency band. Any frequency band that remains active for illumination purposes and does not carry data may increase system interference and lower overall capacity.

PHY multiplexing provides independent channels between multiple light sources (between luminaires) so that multiple light sources can exist simultaneously. PHY multiplexing allows for the separation of the signal of one light emitting source from the signal of another light emitting source. In infrastructure topologies, interference between light emitting sources can be mitigated using Code Division Multiplexing (CDM). Variable length spreading codes are defined where the spreading factor is equal to the reuse factor or the number of channels desired within the geographic area.

Fig. 5 illustrates a multi-emitter architecture 500. Fig. 5 shows two data streams or two luminaires 505, 508. Multiple emitters may be present simultaneously. Bit stream x for each luminary₁，x₂，x₃，...x_N507. 509 may be used as an input vector of length N and input into the PHY band splitters 510, 511. The bit padding "0" is used to guarantee that the vector length is N', which is a multiple of M, whose relationship is expressed using equation 1. The output of the band splitters 510, 511 may be M data bands 515, 516 for each illuminant 505, 508.

Channelization codes C (k, SF) are applied to each data band in channelization code blocks 520, 521. Then scrambling or line codes s_mIs applied to each data band in scrambling or line code blocks 525, 526. If the number of luminaires is more than the spreading code, at least two luminaires may have the same spreading code. In this case, different scrambling codes may be used. In the input or receiver, there is interference between the lights. However, the interference may be reduced by (SF). Interference can be reduced by CDM using walsh codes and variable spreading based on system reuse parameters. For each band data, conversion to unipolar data may occur in DC offset or unipolar conversion blocks 530, 531.

Dimming may be performed at dimming blocks 535, 536 for each band data. The desired brightness level is received in each of the dimming blocks 535, 536. A data duty cycle for the data transmission is determined based on the desired brightness level. The fill luminance value is based on the received luminance level. The single or multi-band LED devices 540, 541 add one of the fill luminance values "1" or "0" to the data before the data is converted to illumination before the frequency band is output to the transmission channel 550. Filling values of luminance values or filling bits, b_BIs represented by the following equationDetermining:

equation [7 ]]

Where B is the average brightness for a given modulation and L is the desired brightness level.

Data transmission and reception are performed using a transmission channel 550 provided by the VLC physical layer. There are two different types of transport channels, a Broadcast Channel (BCH) and a Shared Traffic Channel (STCH), according to the purpose and characteristics of the transport channels. The BCH is a downlink channel that broadcasts the current state of the system and cell to all cells. The STCH is a channel for user data transmission. Since the channel is shared by many users, the data flow on the channel is managed by the scheduler and the medium access mechanism. The STCH is used for both uplink and downlink communications.

Fig. 6 shows a walsh code tree for use in VLC. The walsh spreading codes are orthogonal. Thus, if a plurality of light emitters are assigned different spreading codes and the same scrambling code, and if they are transmitted synchronously, they can be separated by the receiver and do not interfere with each other. This property can be used to solve the "near-far" problem often encountered in wireless transmission. The near-far problem is the case where the receiver cannot detect a weaker signal due to acquisition of a strong signal. The near-far problem can be reduced by using synchronized walsh codes, where the codes are orthogonal.

Walsh codes have a property such that the channelization code C (0, SF) is a pure DC offset, while all other codes have no DC offset component. After scrambling, each code may result in a random DC offset component. Low frequency ambient noise can still interfere with the transmission, however, the use of an SF factor reduces this effect compared to using OOK.

Fig. 7 shows an example 700 of a data duty cycle. VLC may use indoor lighting, the primary function of which is lighting, and VLC is an auxiliary function. To maintain communication while changing the light intensity, dimming is implemented. The lamp brightness corresponds to an on/off cycle portion of the lamp. When the light is turned off very quickly, flicker is not detected by the naked eye. If the light is on more times than it is off, then the light may be brighter than if it is off more times than it is on. The data stream using VLC is mapped to the on time of the light. To achieve the desired brightness and maximum transmission level of data, a data duty cycle is performed.

In fig. 7, in time interval T710, when the average luminance level 730 is half the maximum luminance level, the data duty cycle 720 is the highest, which means that the maximum amount of data can be transmitted. For example, a data duty cycle operates at 100% at a 50% brightness level. When the brightness is highest or lowest, the data duty cycle is lowest, meaning that the minimum amount of data is transmitted. For example, when the average brightness level is 100%, it means that the light is on and no data is transmitted, and when the average brightness level is 0%, it means that the light is off and no data is transmitted.

When the minimum amount of data is transmitted and the brightness is highest, the LED fill brightness value is 1. An LED fill brightness value of 1 is equivalent to the LED being on, indicating that the light is on. When the minimum amount of data is transmitted and the brightness is lowest, the LED pad is 0. An LED fill of 0 is equivalent to the LED being off, indicating that the light is off. The average brightness level L over the time interval T is no data inData transmission duty ratio Y in line transfer_BAnd LED fill level.

The desired light source brightness may be controlled by varying or modulating the length of the duty cycle of the active data transmission. Dimming is used for link power control in communications. Data may be transmitted when the average brightness level is less than 100% and greater than 0%. When data is sent, the lights are adjusted by percentage.

Dimming can increase the data duty cycle when the average brightness level is above 50%, and further dimming forces the data duty cycle to decrease when the average brightness level is below 50%. At an average brightness level of 50%, data transmission is performed at the highest rate. In the absolute maximum brightness level and in the completely dark situation, no data transmission takes place.

When the plurality of luminaires are adjusted independently, they may have different data duty cycles. To minimize interference, the phase adjustments of the duty cycles of the multiple illuminants may be staggered. The phase of the duty cycle may be controlled by the timing of the switching point calibration or the phase signal in the dimming blocks 535, 536, which is input from the MAC.

Optimal performance in terms of interference may be obtained when the data transmission in the duty cycles of multiple emitters has minimal overlap. This can be achieved by estimating or removing one of the padding bits. When the padding bit value is 0, there is no interference with the data.

Fig. 8 shows an example 800 of the relation between the average brightness B of the LEDs and the different methods used to modulate the transmission. For example, the data transmission may be determined by OOK or manchester modulation, where the average brightness during the data transmission is 50% of the peak brightness. In another example, the data transmission may be determined by 4-pulse position modulation (4-PPM), where the average brightness during the data transmission is 25% of the peak brightness.

FIG. 9 shows the data duty cycle Y_BAnd a desired dimming or brightness level. Temporal under absolute maximum LED brightnessBrightness level 910 allows a minimum level of data transmission. Where L is the average brightness level desired by the user and B is the average brightness for a given modulation.

Fig. 10 illustrates an embodiment where VLC exists in the MAC architecture 1000. The MAC subsystem interacts with upper layers via control and data signaling. The MAC subsystem performs various functions including classification and allocation of control and traffic packets interacting with upper layers, status management of the WTRU, depending on whether there is data to transmit, packet scheduling, and downlink broadcast for information delivery.

The MAC sublayer is responsible for access to the physical channels and for tasks including, but not limited to: (1) dimming control; (2) broadcast and public data; (3) packet scheduling; (4) using multiple access Time Division Multiplexing (TDM) in a luminaire; and (5) data construction including segmentation and assembly.

To perform the above functions, several functional blocks are used, including but not limited to: (1) reorganization/deconstruction block 1010; (2) a state management block 1020; (3) broadcast/common control block 1030; (4) a buffer management block 1040; (5) a transmission/reception control block 1050; and (6) a packet scheduling block 1060.

In fig. 10, the mobile device MAC is a subset of the infrastructure MAC. Dimming control 1070 is managed before packet scheduling 1060. Dimming control 1070 includes a color quality index for scheduling and managing data streams. The MAC determines the duty cycle γ by receiving the desired average brightness level L as an input to the MAC and determining the duty cycle γ from the equation_BTo control dimming:

equation [8 ]]

Where B is the average brightness for a given modulation. The size of the data stream and data packets are based on dimming and channel measurements 1065, the channel measurements 1065 including but not limited to Channel Quality Index (CQI), color quality index, and power level.

FIG. 11 shows a size N_PDUMAC Protocol Data Unit (PDU) 1100. The structure of the MAC PDU includes a preamble, a PHY header 1130, a MAC header 1140, a start of packet separator 1120, a payload 1150, and an optional frame check sequence 1160. The preamble 1110 may be used for receiver timing and synchronization. The size of the MAC PDU may be calculated as:

N_PDU＝N_Fγ_Balpha equation [9 ]]

Wherein N is_FIs the size of the physical layer data frame (including the padding bits), γ_BIs the data duty cycle and alpha is the FEC code rate.

In order to provide data services to multiple users under a luminaire, the MAC multiple access feature may be used in the luminaire (within the luminaire).

Fig. 12 shows an example of MAC multiplexing and multiple access. The MAC multiple access feature may be used in a luminaire (within the luminaire) or infrastructure node 1210 for providing data services to the multi-end user nodes 1230, 1235. MAC channelization may be accomplished through logical channels including a broadcast channel 1220, a multicast channel 1240, and a unicast channel 1225. The broadcast channel may be used for system information. Unicast and multicast channels may be used for user or group data.

The logical channels may relate to the type and content of data communicated over the air or over the radio interface. Data traffic mapped to logical channels may have different classifications. The broadcast channel may be a downlink only channel that broadcasts infrastructure node capabilities and system current status to all of the light areas. The broadcast channel may be mapped to a broadcast control channel (BCH). The multicast channel may be a downlink-only channel for sending common user data transmissions to the subgroups of users. It may be mapped to a Shared Traffic Channel (STCH). Further, the identification of each packet of the group may be generated using a multicast MAC address. The unicast channel may be a point-to-point duplex channel between the infrastructure node and each end user node. It may be used to carry user data transmissions and may be mapped to the STCH.

Fig. 13 is a flow diagram 1300 of a discovery process. The discovery process comprises a process in which an end user discovers luminaires to be associated. The discovery and association process begins with the newly turned on end user device receiving beacons from all nearby infrastructure luminaires. Upon entering the luminary area, the new device starts receiving on the configured channel. In periodic intervals, the luminaires transmit beacons that include capabilities on the broadcast channel 1310.

The device receiving the beacon makes a decision based on the received capabilities. The device processes capabilities received from the luminaire infrastructure nodes. The capabilities include PHY capability, MAC capability, unidirectional traffic support, bidirectional traffic support, dimming support, and visibility support 1320. The end user device executes a selection algorithm to determine luminaires to associate based on the received capabilities, which may also include signal measurements and data rate requirements. The end user device sends an association request to the selected luminaires initiating an association procedure 1330-. Once the lights confirm that they have been associated with the end user, additional information is transmitted including resource allocation information, Transmission (TX) and Reception (RX) information, CDMA parameters and available frequency bands 1360. The end user can exchange data 1370 with the luminaires over an agreed-upon channel.

Fig. 14 is a block diagram 1400 illustrating dimming controlled by a MAC. The dimming signal is received from a higher layer, such as a light extraction layer (LAL). The dimming signal is used to determine the duty cycle 1420. MAC based on duty cycle gamma_BThe switch point 1430 is determined. And then outputs the data to the LED device 1440.

Fig. 15 is a block diagram 1500 illustrating VLC including application layer support. In order to perform infrastructure uplink on different Radio Access Technologies (RATs), application layer support is required in MAC. The management component 1560 may be characterized by RAT availability, QoS mapping, control/data multiplexing selection and configuration. The management component 1560 transmits information to the PHY layer 1565 and receives information from the PHY layer 1565.

The architecture includes the following layers that can be used in uplink and downlink transmissions: an application layer 1510, a middleware layer 1520, a network protocol layer 1530, an adaptation data layer 1540, a first adapter 1550 coupled to the MAC layer associated with the first technology, and a second adapter 1555 coupled to the MAC layer associated with the second technology. Although two adapters are described in this example, the number of adapters may be limited by the number of RATs supported by the device.

One of the difficulties with VLC is that the availability of uplink and downlink is independent of each other due to device limitations. In some environments, a high intensity visible light based downlink may be readily provided in an infrastructure lighting fixture, while an uplink is limited to the transmitted power of the portable device and needs to be provided by other frequency spectrums (e.g., RF) than visible light.

Another feature of visible light is that the optical confinement of LED lamps can provide a locally high bandwidth density. This may be balanced by allowing spectrum aggregation and using multiple access techniques in a single direction. Visible light may serve as a supplemental communication link between two devices by using, for example, visible light communication in the downlink and infrared in the uplink, or by generating a hybrid topology that performs control and data communication in different access technologies, or by generating a "hot spot" function of multiple access technologies that work in concert in each direction.

Detailed description of the preferred embodiments

1. A wireless transmit/receive unit (WTRU) for use in dimming a luminaire for lighting and data transmission in Visible Light Communication (VLC), comprising:

an input port configured to receive a brightness level.

2. The WTRU of embodiment 1, further comprising:

a processor configured to determine a data duty cycle and a fill brightness value for the data transmission based on the brightness level.

3. The WTRU as in any one of embodiments 1-2, further comprising:

a transmitter configured to alter the luminary data transmission and fill brightness values.

4. The WTRU of any of embodiments 1-3, wherein the data duty cycle is based onWherein gamma is_BRepresents the data duty cycle of the data transmission, L represents the brightness level, and B represents the average brightness of the light emitted from the light emitter.

5. The WTRU of any of embodiments 2-4, wherein the padding luminance values are based onWherein b is_BRepresenting the value of one or more padding bits, L representing the brightness level, and B representing the average brightness of the light emitted from the luminary.

6. The WTRU as in any one of embodiments 2-5 wherein the amount of data transmitted is proportional to the padding luminance value.

7. A wireless transmit/receive unit (WTRU) for use in multiplexing a plurality of light signals in Visible Light Communication (VLC), comprising:

an input port configured to receive a plurality of luminary signals, wherein the luminary signals comprise a plurality of data.

8. The WTRU of embodiment 7, further comprising:

a parser configured to parse the plurality of data into data of one or more frequency bands.

9. The WTRU as in any one of embodiments 7-8, further comprising:

a channelization code block configured to apply channelization codes to data in each frequency band.

10. The WTRU as in any one of embodiments 7-9, further comprising:

a Direct Current (DC) offset block configured to convert data in each frequency band to unipolar data.

11. The WTRU as in any one of embodiments 7-10, further comprising:

a dimmer configured to calculate a duty cycle for the data of each frequency band, and configured to add a fill brightness value to the data of each frequency band.

12. The WTRU as in any one of embodiments 7-11, further comprising:

a transmitter configured to transmit data.

13. The WTRU as in any one of embodiments 7-12 wherein the light signal is an intra-light signal or an inter-light signal.

14. The WTRU as in any one of embodiments 7-13 wherein a scrambling code or line code is applied to the data in each frequency band.

15. The WTRU as in any one of embodiments 7-14 wherein the data for each band corresponds to a different wavelength.

16. The WTRU as in any one of embodiments 7-15 wherein the data for each frequency band has a different data duty cycle.

17. The WTRU as in any one of embodiments 7-16 wherein an amount of data transmitted on a wavelength is proportional to an amount of illumination transmitted on the wavelength.

18. A method of dimming a luminaire for lighting and data transmission in Visible Light Communication (VLC), the method comprising:

a brightness level is received.

19. The method of embodiment 18, further comprising:

a data duty cycle for the data transmission is determined based on the brightness level.

20. The method according to any one of embodiments 18-19, further comprising:

a fill brightness value is determined based on the brightness level.

21. The method according to any one of embodiments 18-20, further comprising:

the data transmission and the fill brightness value of the luminaries are altered.

22. The method as in any one of embodiments 18-21, wherein the data duty cycle is based onWherein gamma is_BIndicating the duty cycle of the data for data transmission, L indicating the brightness level, and B indicating the average brightness of the light emitted from the light emitter.

23. The method as in any one of embodiments 19-22, wherein the fill-in luminance values are based onWherein b is_BRepresenting the value of one or more padding bits, L representing the brightness level, and B representing the average brightness of the light emitted from the luminary.

24. The method as in any one of embodiments 19-23, wherein an amount of data transferred is proportional to the fill brightness value.

25. A method for multiplexing a plurality of luminary signals in Visible Light Communications (VLC), the method comprising:

a plurality of light signals is received, wherein the light signals comprise a plurality of data.

26. The method of embodiment 25, further comprising:

the plurality of data is parsed into data of one or more frequency bands.

27. The method of any one of embodiments 25-26, further comprising:

channelization codes are applied to the data in each frequency band.

28. The method according to any one of embodiments 25-27, further comprising:

the data in each band is converted to unipolar data.

29. The method of any one of embodiments 25-28, further comprising:

a duty cycle is calculated for the data of each frequency band, and a fill luminance value is added to the data of each frequency band based on the duty cycle.

30. The method according to any one of embodiments 25-29, further comprising:

data for each frequency band is transmitted.

31. The method of any one of embodiments 25-30, wherein the luminophore signal is an intraluminophore signal or an interluminophore signal.

32. The method as in any one of embodiments 25-31, wherein a scrambling code or line code is applied to the data in each band.

33. The method of any one of embodiments 25-32, wherein the data for each band corresponds to a different wavelength.

34. The method as in any one of embodiments 25-33, wherein the data for each frequency band has a different data duty cycle.

35. The method of any of embodiments 25-34 wherein an amount of data transmitted on a wavelength is proportional to an amount of illumination transmitted on the wavelength.

Even though features and elements are described above in particular combinations, it will be understood by those of ordinary skill in the art that each feature or element can be used alone or in combination with other features and elements. Furthermore, the methods described herein may be implemented in a computer program, software, or firmware incorporated into a computer readable medium for execution by a general purpose computer or a processor. Examples of computer readable media include electronic signals (transmitted over wired or wireless connections) and computer-readable storage media. Examples of computer-readable storage media include, but are not limited to, read-only memory (ROM), random-access memory (RAM), registers, cache memory, semiconductor memory devices, magnetic media such as internal hard disks and removable magnetic disks, magneto-optical media and optical media such as CD-ROM disks, and Digital Versatile Disks (DVDs). A processor in association with software is used to implement a radio frequency transceiver for a WTRU, UE, terminal, base station, RNC, or any host computer.

Claims (20)

1. A wireless transmit/receive unit (WTRU) for use in dimming a luminaire for lighting and data transmission in Visible Light Communication (VLC), the WTRU comprising:

an input port configured to receive a brightness level;

a processor configured to determine a data duty cycle and a fill brightness value for the data transmission based on the brightness level; and

a transmitter configured to alter the data transmission and the fill brightness value of the luminaire.

2. The WTRU of claim 1, wherein the data duty cycle is based onWherein gamma is_BRepresents the data duty cycle of the data transmission, L represents a brightness level, and B represents an average brightness of light emitted from the light emitter.

3. The WTRU of claim 1, wherein the padding brightness values are based onWherein b is_BRepresents the value of one or more padding bits, L represents the brightness level, and B represents the average brightness of the light emitted from the luminary.

4. The WTRU of claim 1, wherein an amount of data transmitted is proportional to the padding luminance values.

5. A wireless transmit/receive unit (WTRU) for use in multiplexing a plurality of light signals in Visible Light Communication (VLC), the WTRU comprising:

an input port configured to receive the plurality of luminary signals, wherein the luminary signals comprise a plurality of data;

a parser configured to parse the plurality of data into data of one or more frequency bands;

a channelization code block configured to apply channelization codes to data in each frequency band;

a Direct Current (DC) offset block configured to convert data in each frequency band into unipolar data;

a dimmer configured to calculate a duty cycle for the data for each frequency band and to add a fill brightness value to the data for each frequency band; and

a transmitter configured to transmit the data.

6. The WTRU of claim 5, wherein the luminophore signal is an intra-luminophore signal or an inter-luminophore signal.

7. The WTRU of claim 5, wherein a scrambling code or line code is applied to the data in each frequency band.

8. The WTRU of claim 5, wherein the data for each band corresponds to a different wavelength.

9. The WTRU of claim 5, wherein the data for each frequency band has a different data duty cycle.

10. The WTRU of claim 5, wherein an amount of data transmitted on a wavelength is proportional to an amount of illumination sent on the wavelength.

11. A method of dimming a luminaire for lighting and data transmission in Visible Light Communication (VLC), the method comprising:

receiving a brightness level;

determining a data duty cycle for the data transmission based on the brightness level;

determining a fill brightness value based on the brightness level; and

altering the data transmission and the fill brightness value of the luminaire.

12. The method of claim 11, wherein the data duty cycle is based onWherein gamma is_BRepresents the data duty cycle for the data transmission, L represents the brightness level, and B represents the average brightness of the light emitted from the light emitter.

13. The method of claim 11, wherein the fill brightness value is based onWherein b is_BRepresents the value of one or more padding bits, L represents the brightness level, and B represents the average brightness of the light emitted from the luminary.

14. The method of claim 11, wherein an amount of data transferred is proportional to the fill brightness value.

15. A method for multiplexing a plurality of luminary signals in Visible Light Communication (VLC), the method comprising:

receiving a plurality of illuminant signals, wherein the illuminant signals comprise a plurality of data;

parsing the plurality of data into data of one or more frequency bands;

applying channelization codes to the data in each frequency band;

converting the data in each frequency band into unipolar data;

calculating a duty cycle for the data of each frequency band, and adding a fill luminance value to the data of each frequency band based on the duty cycle; and

data for each frequency band is transmitted.

16. The method of claim 15, wherein the luminophore signal is an intra-luminophore signal or an inter-luminophore signal.

17. The method of claim 15, wherein a scrambling code or line code is applied to the data in each frequency band.

18. The method of claim 15, wherein the data for each band corresponds to a different wavelength.

19. The method of claim 15, wherein the data for each frequency band has a different data duty cycle.

20. The method of claim 15, wherein an amount of data communicated on a wavelength is proportional to an amount of illumination sent on the wavelength.