EP1125380A2 - Systeme et procede pour communication infra-rouge - Google Patents

Systeme et procede pour communication infra-rouge

Info

Publication number
EP1125380A2
EP1125380A2 EP99952777A EP99952777A EP1125380A2 EP 1125380 A2 EP1125380 A2 EP 1125380A2 EP 99952777 A EP99952777 A EP 99952777A EP 99952777 A EP99952777 A EP 99952777A EP 1125380 A2 EP1125380 A2 EP 1125380A2
Authority
EP
European Patent Office
Prior art keywords
reader
data
location
transceiver
badge
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
EP99952777A
Other languages
German (de)
English (en)
Inventor
Israel Radomsky
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Visonic Technologies 1993 Ltd
Original Assignee
Elpas Electro Optic Systems Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Elpas Electro Optic Systems Ltd filed Critical Elpas Electro Optic Systems Ltd
Publication of EP1125380A2 publication Critical patent/EP1125380A2/fr
Ceased legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06K—GRAPHICAL DATA READING; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
    • G06K7/00—Methods or arrangements for sensing record carriers, e.g. for reading patterns
    • G06K7/10—Methods or arrangements for sensing record carriers, e.g. for reading patterns by electromagnetic radiation, e.g. optical sensing; by corpuscular radiation
    • G06K7/10544—Methods or arrangements for sensing record carriers, e.g. for reading patterns by electromagnetic radiation, e.g. optical sensing; by corpuscular radiation by scanning of the records by radiation in the optical part of the electromagnetic spectrum
    • G06K7/10821—Methods or arrangements for sensing record carriers, e.g. for reading patterns by electromagnetic radiation, e.g. optical sensing; by corpuscular radiation by scanning of the records by radiation in the optical part of the electromagnetic spectrum further details of bar or optical code scanning devices
    • G06K7/1097—Optical sensing of electronic memory record carriers, such as interrogation of RFIDs with an additional optical interface
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06K—GRAPHICAL DATA READING; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
    • G06K7/00—Methods or arrangements for sensing record carriers, e.g. for reading patterns
    • G06K7/0008—General problems related to the reading of electronic memory record carriers, independent of its reading method, e.g. power transfer
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06K—GRAPHICAL DATA READING; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
    • G06K7/00—Methods or arrangements for sensing record carriers, e.g. for reading patterns
    • G06K7/10—Methods or arrangements for sensing record carriers, e.g. for reading patterns by electromagnetic radiation, e.g. optical sensing; by corpuscular radiation
    • G06K7/10009—Methods or arrangements for sensing record carriers, e.g. for reading patterns by electromagnetic radiation, e.g. optical sensing; by corpuscular radiation sensing by radiation using wavelengths larger than 0.1 mm, e.g. radio-waves or microwaves
    • G06K7/10019—Methods or arrangements for sensing record carriers, e.g. for reading patterns by electromagnetic radiation, e.g. optical sensing; by corpuscular radiation sensing by radiation using wavelengths larger than 0.1 mm, e.g. radio-waves or microwaves resolving collision on the communication channels between simultaneously or concurrently interrogated record carriers.
    • G06K7/10029—Methods or arrangements for sensing record carriers, e.g. for reading patterns by electromagnetic radiation, e.g. optical sensing; by corpuscular radiation sensing by radiation using wavelengths larger than 0.1 mm, e.g. radio-waves or microwaves resolving collision on the communication channels between simultaneously or concurrently interrogated record carriers. the collision being resolved in the time domain, e.g. using binary tree search or RFID responses allocated to a random time slot
    • G06K7/10039—Methods or arrangements for sensing record carriers, e.g. for reading patterns by electromagnetic radiation, e.g. optical sensing; by corpuscular radiation sensing by radiation using wavelengths larger than 0.1 mm, e.g. radio-waves or microwaves resolving collision on the communication channels between simultaneously or concurrently interrogated record carriers. the collision being resolved in the time domain, e.g. using binary tree search or RFID responses allocated to a random time slot interrogator driven, i.e. synchronous
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06K—GRAPHICAL DATA READING; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
    • G06K7/00—Methods or arrangements for sensing record carriers, e.g. for reading patterns
    • G06K7/10—Methods or arrangements for sensing record carriers, e.g. for reading patterns by electromagnetic radiation, e.g. optical sensing; by corpuscular radiation
    • G06K7/10009—Methods or arrangements for sensing record carriers, e.g. for reading patterns by electromagnetic radiation, e.g. optical sensing; by corpuscular radiation sensing by radiation using wavelengths larger than 0.1 mm, e.g. radio-waves or microwaves
    • G06K7/10316—Methods or arrangements for sensing record carriers, e.g. for reading patterns by electromagnetic radiation, e.g. optical sensing; by corpuscular radiation sensing by radiation using wavelengths larger than 0.1 mm, e.g. radio-waves or microwaves using at least one antenna particularly designed for interrogating the wireless record carriers
    • G06K7/10356—Methods or arrangements for sensing record carriers, e.g. for reading patterns by electromagnetic radiation, e.g. optical sensing; by corpuscular radiation sensing by radiation using wavelengths larger than 0.1 mm, e.g. radio-waves or microwaves using at least one antenna particularly designed for interrogating the wireless record carriers using a plurality of antennas, e.g. configurations including means to resolve interference between the plurality of antennas
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/11—Arrangements specific to free-space transmission, i.e. transmission through air or vacuum
    • H04B10/114—Indoor or close-range type systems
    • H04B10/1143—Bidirectional transmission
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W76/00—Connection management
    • H04W76/10—Connection setup
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S17/00—Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
    • G01S17/74—Systems using reradiation of electromagnetic waves other than radio waves, e.g. IFF, i.e. identification of friend or foe
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W52/00—Power management, e.g. TPC [Transmission Power Control], power saving or power classes
    • H04W52/02—Power saving arrangements
    • H04W52/0209—Power saving arrangements in terminal devices
    • H04W52/0212—Power saving arrangements in terminal devices managed by the network, e.g. network or access point is master and terminal is slave
    • H04W52/0216—Power saving arrangements in terminal devices managed by the network, e.g. network or access point is master and terminal is slave using a pre-established activity schedule, e.g. traffic indication frame
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W52/00—Power management, e.g. TPC [Transmission Power Control], power saving or power classes
    • H04W52/02—Power saving arrangements
    • H04W52/0209—Power saving arrangements in terminal devices
    • H04W52/0212—Power saving arrangements in terminal devices managed by the network, e.g. network or access point is master and terminal is slave
    • H04W52/0219—Power saving arrangements in terminal devices managed by the network, e.g. network or access point is master and terminal is slave where the power saving management affects multiple terminals
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W52/00—Power management, e.g. TPC [Transmission Power Control], power saving or power classes
    • H04W52/02—Power saving arrangements
    • H04W52/0209—Power saving arrangements in terminal devices
    • H04W52/0225—Power saving arrangements in terminal devices using monitoring of external events, e.g. the presence of a signal
    • H04W52/0229—Power saving arrangements in terminal devices using monitoring of external events, e.g. the presence of a signal where the received signal is a wanted signal
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W72/00—Local resource management
    • H04W72/04—Wireless resource allocation
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W8/00—Network data management
    • H04W8/26—Network addressing or numbering for mobility support
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02D—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE
    • Y02D30/00—Reducing energy consumption in communication networks
    • Y02D30/70—Reducing energy consumption in communication networks in wireless communication networks

Definitions

  • This invention relates to a method for keeping track of objects and, in particular, to such a method for use with low consumption portable tags that may be affixed to movable objects so as to keep track of their geographic location.
  • One way in which this can be done is to affix to each file a portable tag which contains a memory for storing a unique identity which may be read by a suitable interrogation device located, for example, at the entry to a room so that whenever the file moves into a new room, its identity is automatically determined for onward transmission to a central tracking computer which keeps a record of each file identification and its corresponding location.
  • a suitable interrogation device located, for example, at the entry to a room so that whenever the file moves into a new room, its identity is automatically determined for onward transmission to a central tracking computer which keeps a record of each file identification and its corresponding location.
  • infrared (IR) transceivers are particularly suited for the kind of task in question and require an optically transparent path unencumbered by obstacles for effective data transmission.
  • IR infrared
  • optical transparency might, for example, be the result of a dividing door between the two rooms being ajar; or owing to a window between the two rooms permitting infrared transmission therethrough.
  • a method for effecting bi-directional IR data communication between a plurality N of readers and a plurality M of portable objects each having associated therewith a respective object transceiver which is initially dormant and has embedded therein a respective object ID uniquely identifying the object comprising the steps of: each reader transmitting to an object transceiver a preamble containing a carrier signal for awaking the object transceiver from its initially dormant state, each reader transmitting a Reader Control Message (RCM) including a header; a respective reader ID so as to allow the reader to be addressed when required followed by up to K object IDs (K ⁇ M) each in respect of one of said object transceivers and each being followed by a respective command for controlling the respective object transceiver, allocating up to K data slots each for allowing communication of a data message between the respective reader one of said object transceivers, and allowing each of the M object transceivers to randomly select of
  • a particular application of such a communications protocol relates to a method for keeping track of objects each having a respective unique identity and subject to movement between different locations, wherein: (a) in each different location there is provided a respective one of said readers each having associated therewith a location ID uniquely identifying the respective location,
  • each of said location transceivers periodically transmits its location ID for receipt by any object transceiver within a boundary associated with said location, (d) any object transceiver receiving the location ID of a proximate reader; compares said location ID with a current location ID stored in the object transceiver corresponding to the object's current location,
  • the object transceiver randomly selects one of said R allocation slot for transmitting its respective object ID to the reader associated with its current location and stores the respective location ID of said reader, and
  • a geographic area may be split into corresponding cells each representing a discrete geographical area such as, for example, a separate room each of which is allocated a separate time slice for transmitting therein its corresponding location ID.
  • a plurality of separate data slots may be provided within each frame of data and each of the object transceivers may select one of the plurality of data slots randomly.
  • the risk of two or more object transceivers attempting to transmit within the same data slot may be sufficiently reduced.
  • conventional data collision techniques requiring re-allocation of data .slots and re-transmission of data may be employed in the event that, notwithstanding efforts to the contrary, two different obj ect IDs are transmitted simultaneously .
  • Fig. 1 is plan view showing pictorially a geographical area split into adjacent rooms each containing a reader and one or more portable badges for carrying out the method according to the invention
  • Fig. 2 is a block diagram showing functionally a portable badge transceiver for employing the method of the invention:
  • Fig. 3 is a block diagram showing functionally an IR receiver for use in the readers and badges illustrated in Fig. 1 ;
  • Fig. 4 shows pictorially a message frame configuration according to a preferred communications protocol for use with the transceiver;
  • Figs. 5a to 5d show further details of long and short message communications protocols employed by the reader and badge;
  • Figs. 6a and 6b show details of the modulation scheme and reader transmission protocol;
  • Figs. 7a to 7e are timing diagrams showing successive frames of data of a long message transmitted by the Reader to the Badge;
  • Figs. 8a to 8c are timing diagrams of a data decoding circuit used in the LR receiver of the Badge;
  • Fig. 9a is a flow diagram showing details of a communications protocol for use by the reader during transmission of a long message from the reader to the badge;
  • Fig. 9b is a flow diagram showing details of a communications protocol for use by the badge during transmission of a long message from the reader to the badge;
  • Fig. 10a is a flow diagram showing details of a communications protocol for use by the reader during transmission of a long message from the badge to the reader
  • Fig. 10b is a flow diagram showing details of a communications protocol for use by the badge during transmission of a long message from the badge to the reader;
  • Fig. 11a is a flow diagram showing details of a communications protocol for use by the reader during transmission of a short message from the badge to the reader;
  • Fig. lib is a flow diagram showing details of a communications protocol for use by the badge during transmission of a short message from the badge to the reader.
  • Fig. 1 shows in plan view a pictorial representation of a geographical area depicted generally as 10 comprising three separate and mutually adjacent rooms 11, 12. and 13.
  • a corresponding reader 21, 22 and 23 constituting a location transceiver which allows transmission and reception of data using IR transmission. If a door (not shown) between the two rooms 11 and 12 be ajar, then an IR signal transmitted by the reader 21 so as to read all objects within the room 11 can pass through the open door into the adjacent room 12 and thus, incorrectly, read the objects therein.
  • the reader 22 can incorrectly read objects within the room 11 if the door between the two rooms is open.
  • a respective object transceiver 24, 25, 26 and 27 each constituted by a portable badge which can transmit data to a nearby reader as well as receiving data therefrom.
  • the readers 21, 22 and 23 are connected via a communications network to a server 28 constituting a central tracking receiver.
  • Fig. 2 shows a block diagram of a badge depicted generally as 30 and including an IR photodiode 31 connected to an LR receiver 32 for receiving an IR signal from one of the ceiling-mounted readers 21, 22 and 23 shown in Fig. 1.
  • An array of LEDs 33 is connected to an IR transmitter 34 for transmitting an LR signal to one of the readers 21, 22 and 23.
  • a micro-controller 35 is coupled to both the IR receiver 32 and the IR transmitter 34 and operates in accordance with a stored instruction set defining communications protocols allowing both long and short messages to be communicated between the badge and reader. The various communications protocols are described in detail below with particular reference to Figs. 9a to 1 lb of the drawings.
  • a buzzer 36 and a display 37 are Coupled to the micro-controller 35 as well as an array of manual switches SI, S2, S3 and S4 allowing pre-programmed functions to be manually selected in accordance with the instruction set stored in the micro- controller 35.
  • the badge circuitry is powered by a battery 38 connected to the micro-controller 35, the IR receiver 32 and the IR transmitter 34 via a power supply controller 39.
  • the buzzer 36 and the display 37 in addition to the manual switches SI, S2, S3 and S4, allow customization of the badge for specific applications.
  • the badge can serve as a paging device for displaying a short message upon receiving a remote communication and sounding the buzzer so as to alert the owner of an awaiting message.
  • Fig. 3 shows in greater detail the circuitry associated with the IR receiver 32 used in the badge 30.
  • a similar circuit is likewise employed in the ceiling-mounted IR transceivers 21, 22 and 23 shown in Fig. 1.
  • an IR photodiode array 41 is connected to a tuned resonant circuit comprising an tuned antenna coil 42 and a capacitor 43 for applying data to the gate of a MOSFET 44.
  • the source of the MOSFET 44 is connected to the capacitor 43 via a resistor 45 and is fed via a coupling capacitor 46 to the LR transceiver 32 having therein a memory (not shown) for allowing data to be stored therein and to be extracted, or read, therefrom.
  • the coupling capacitor 46 blocks the DC level but allows data to pass through to a low noise linear amplifier 47 operating at a basic frequency 455KHz and having an output coupled to a band pass filter 48 having a bandwidth of 32KHz.
  • the resulting carrier signal is fed to the input of a logarithmic amplifier and Received Signal Strength Indicator (RSSI) 49 allowing the signal strength to be displayed in suitable form.
  • RSSI 49 Received Signal Strength Indicator
  • the signal passed by the RSSI 49 includes both data and noise and it is obviously important to filter out the noise so that the IR receiver 32 does not receive false signals. Only those signals which are determined to be genuine data signals are demodulated so as to extract the data.
  • a noise subtract unit 50 an output of which is fed to a capacitor 51 operating as a noise integrator whose output is fed to a first input of a summing amplifier 52.
  • a second input of the summing amplifier 52 is connected to a variable threshold generator 53 whose threshold may be set by a variable resistor 54 external to the IR receiver 32.
  • the output of the summing amplifier 52 corresponding to the sum of the average noise and the noise threshold, is fed to the inverting input of a comparator 55 whose non-inverting input is fed to the RSSI signal produced by the amplifier and detector 49.
  • the output of the comparator 55 is fed to a "wake-up" signal generator 56 and to a deglitcher 57 which suppresses any pulse whose time duration is less than 25 ⁇ s and thus constitutes spurious glitches rather than actual signal data.
  • a signal is detected at the output of the deglitcher 57, corresponding to an actual received signal, the corresponding data associated therewith is extracted and detected.
  • the RSSI signal is fed to a peak detector 60 which measures its peak value and feeds it to a first, summing input of a summing amplifier 61 having a second, subtracting input connected to a variable threshold generator 62 whose threshold may be set by a variable resistor 63 external to the IR receiver 32.
  • the output of the summing amplifier 61 corresponding to the difference between the peak value of the RSSI signal and the threshold, is fed to the inverting input of a comparator 64 whose non-inverting input is fed to the RSSI signal produced by the amplifier and detector 49.
  • the output of the comparator 64 is fed to a deglitcher 65 which suppresses any pulse whose time duration is less than 25 ⁇ s and thus constitutes spurious glitches rather than actual data.
  • the waveforms associated with the decoded data, the RSSI and the "wake-up" signals are shown in Figs. 8a, 8b and 8c of the drawings.
  • Fig. 4 shows the frame configuration associated with the communications protocol according to the invention allowing up to four readers to effect bi-directional communication with a corresponding badge simultaneously.
  • each of each of the readers 21 to 23 (constituting location transceivers) has associated therewith a respective location ID so that each location ID uniquely addresses the respective location in which the location transceiver is mounted
  • the respective location IDs for each of the location transceivers 21, 22 and 23 will be denoted by the corresponding room number #11, #12 and #13.
  • Each of the readers 21 to 23 periodically communicates its location ID to the badges in its area of reception so that the location of each badge may be stored therein.
  • the communications protocol employs a data frame configuration wherein four different data slots DS1, DS2, DS3 and DS4 are allocated one to each of four different readers.
  • each of the location transceivers 21 to 23 can transmit data only in its own data slot thus avoiding the risk of ' data collisions between two or more respective location transceivers in mutual line of sight with the same badge.
  • Each of the badges 25 and 26 receives an IR data string transmitted by the location transceiver 22 and, possibly, also by the location transceivers 21 and 23 if the adjoining door between adjacent rooms 11 and 12 or between 12 and 13 is open.
  • the intensity of the data received from the adjoining location transceiver 21 will be reduced compared to that received by the correct location transceiver 22. This difference in signal intensity may be used in order to reject a weak signal emanating from a location transceiver in an adjoining room and thus containing the location ID of an incorrect location.
  • one of the badges 25 or 26 When one of the badges 25 or 26 receives the location ID #12 associated with the location transceiver 22, it compares the received location ID with the current location LD stored within its internal memory. If these are identical, this means that the ID associated with the location transceiver 22 corresponds to the current location ID within the memory of the badge and that consequently the badge has not moved since it was previously updated. In this case, unless the badges 25 or 26 need, for some reason, to transmit data other than their respective ID, their respective IR transceivers may remain silent. By such means, battery consumption may be reduced to an absolute minimum.
  • the location ID (#12) transmitted by the location transceiver 22 is different to that stored in the badge memory, this implies that the badge transceiver was moved into the room 12 since it was previously read.
  • the location LD (#12) associated with the current location i.e. the room 12 is now stored in the badge memory and the cycle is repeated.
  • Each Reader Control Message includes a header, a reader LD and a cellular slot ID so as to allow a particular reader to be addressed when required.
  • the RCM further includes a badge ID in respect of four different badges which may be addressed at a corresponding one of four data slots in the frame so as to provide each badge with a command whose encoded data is transmitted at the corresponding slot.
  • each RCM includes a CRC checksum which allows the integrity of the data received by the badge to be checked.
  • Each DSM includes a header and a reader ID.
  • the data slot may be used to transmit a long data message having between 16 to 64 bytes included within the DSM slot followed by a validation check and a CRC checksum byte. If, on the other hand, the data which is to be transmitted to a particular badge corresponds to a short data message, this is provided in the form of an Allocation Slot Message (ASM) which is transmitted in one of sixteen slots following the fourth data slot (DSM4).
  • ASM Allocation Slot Message
  • Each ASM comprises a header and a message type followed by a short data message of up to 16 bytes.
  • each data cycle commences with a synchronization signal after which start synchronization signals are allocated in respect of each of the four data slots relating to the corresponding rooms 11 to 14.
  • the four data slots may be needed (according to the four-color map theorem) in order to avoid having two areas whose respective readers attempt to transmit during the same data slot and thus avoid data collisions. It will be appreciated that if the topography shown in Fig. 1 is extended to include additional rooms, then those additional rooms may likewise be allocated data slots within the same overall cycle without in any way conflicting with the three location transceivers 21 to 23 shown in Fig. 1.
  • the manner in which the data slots are allocated so as to avoid data collisions may be pre-determined either by a professional installation expert with a software interface and an exact map of the area 10; or, it may be determined automatically, on a trial-and-error basis, by the location transceivers themselves by means of listening to each other's transmissions and proceeding with the definition in a neural/serial manner.
  • each RCM may contain commands and corresponding LDs in respect of up to five different badges.
  • the commands control the use of the rest of the frame which, as shown, is divided into four data slots. An additional time is allocated at the end of the frame for badge allocation slots. Collision avoidance between the different location transceivers is achieved as explained above by allocating discrete data slots so that adjacent location transceivers may transmit only in their own respective data slots. Collision of data transmitted by different badges within a given area is achieved as follows. The badges do not transmit asynchronously Instead, the location transceiver transmits the RCM and this defines the start of each frame.
  • each frame there are four data slots and sixteen allocation slots, if there is a message to be transmitted from the location transceiver to the badge, then the RCM transmitted to the badge includes command data for instructing the badge to receive the message in an allocated data slot.
  • Longer messages may use more than one slot per frame (if preferred) or, alternatively, more slots in multiple frames.
  • Fig. 5a shows respective data structures 70 and 71 for the reader and the badge during the nth frame as well as respective data structures 72 and 73 for the reader and the badge during a subsequent (n+l)th frame for data transmission of a long message from the reader to the badge.
  • the reader transmits a RCM which is received by the badge to which it is addressed, whereby it is decoded and an acknowledgement is transmitted by the badge to the reader during a randomly allocated slot
  • the reader informs the addressed badge during which data slot message information will be transmitted.
  • message data for the addressed badge is transmitted in the third data slot DSM3.
  • the addressed badge receives the data during this slot and transmits an acknowledge signal ACK back to the reader during a randomly allocated ASM.
  • Fig. 5b shows corresponding data structures 74 and 75 for the reader and the badge during the nth frame as well as respective data structures 76 and 77 for the reader and the badge during a subsequent (n+1) frame for data transmission of a long message from the badge to the reader.
  • data structure 74 the RCM is transmitted from the reader to the badge and during the randomly allocated ASM, the badge transmits a request to the reader for Long Message Transmission.
  • the reader commands the badge at what DSM to transmit, e.g. DSM3. In this case also, correct data transmission is acknowledged by means of an ACK signal transmitted during a randomly allocated ASM.
  • Fig. 5 c shows corresponding data structures 78 and 79 for the reader and the badge during the n frame and during a subsequent (n+1) frame for data transmission of a short message transmission from the badge to the reader.
  • the badge upon receipt of an RCM by the badge, the badge transmits a short message during a randomly allocated ASM which is received by the reader and acknowledged during the subsequent RCM transmitted thereby.
  • Fig. 5d shows identical data structures 80 and 81 for the reader and the badge, during the nth frame and during a subsequent (n+l) ft frame for short location messages sent by the badge to the reader, which is transmitted during one of the randomly allocated ASMs.
  • Figs. 6a shows the IR modulation scheme employing on-off keying (OOK) modulation of the 455KHz pulse train constituting the modulated carrier transmitted by the reader.
  • OOK on-off keying
  • Fig. 6b shows a Reader Control Message (RCM) transmitted by the reader to the badge comprising a 455KHz carrier preamble followed by a plurality of data words.
  • RCM Reader Control Message
  • a similar data slot message or allocation slot message is sent by the .badge to the reader comprising a short preamble in the form of a 455KHz carrier signal followed by words of actual data.
  • Figs. 7a to 7e show various timing diagrams associated with the LR Receiver 32 within the badge 30.
  • the LR Receiver 32 within the badge 30 is dormant until read by a "wake up" signal having a time duration of approximately 1 ms as shown in Fig. 71).
  • Each data packet transmitted by the reader to the badge comprises an initial preamble in the form of a 455KHz carrier signal having a time duration of approximately 2 ms.
  • the power supply controller 39 becomes operative for supplying power to the IR Receiver 32 so that after a small time delay T ⁇ ata delay an " er me preamble, data transmitted by the reader is received by the badge as shown in Fig. 7d.
  • Figs. 8a, 8b and 8c show timing diagrams of a data decoding circuit used in the IR receiver 32 of the Badge 30.
  • the RSSI signal shown as 90 in Fig. 8a is taken from the output of a logarithmic amplifier thus accounting for its irregular shape.
  • the average noise derived at the output of the noise integrator is shown in Fig. 8a as a noise floor 91, whilst an upper noise limit 92 is shown as a 13.5 dB offset from the noise floor 91.
  • the 13.5 dB offset is set by the noise threshold generator 53 and the external potentiometer 54 shown in Fig. 3.
  • the upper noise limit 92 defines the largest signal which could conceivably be noise: anything larger is accepted as genuine data.
  • the upper noise limit 92 thus defines the level of the "wake up" signal 93 shown in Fig. 8b.
  • the "wake up" signal 93 is HIGH, and the data signal derived from the peak detected RSSI signal is demodulated to produce the pulse train shown as 94 in Fig. 8c.
  • the pulse train 94 is derived by clipping the RSSI signal 90 by 6dB, this being the peak threshold set by the threshold generator 62 and the external potentiometer 63 shown in Fig. 3 and shown as 95 in Fig. 8a.
  • the threshold 95 is subtracted from the RSSI signal 90 by the summing amplifier 61 which operates as a subtracter.
  • Fig. 9a is a flow diagram -showing the principal operating steps carried out by the reader during the transmission of a long message to the badge.
  • the reader obtains from a central computer message data destined for a specified badge.
  • the reader prepares an RCM for the identified badge and transmits the RCM, whereafter it awaits acknowledgement from the specified badge during one of the ASM slots.
  • the data is decoded and, if correct, the next RCM is prepared indicating that a command destined for the identified badge will be encoded at slot K.
  • the appropriate DSM is prepared by the reader at slot K and transmitted therein to the badge.
  • the reader then awaits acknowledgment from the badge during the allocated slot, upon receipt of which this cycle of communication is complete.
  • Fig. 9b is a flow diagram showing the principal operating steps carried out by the badge during the transmission of long message data by the reader to the badge.
  • the badge is in standby mode until it receives an RCM from the reader.
  • the RCM is decoded by the badge in order to establish the badge LD to whom the data is transmitted.
  • the receiving badge prepares an acknowledge signal ACK which is then transmitted during the randomly allocated ASM
  • the badge then awaits receipt of the next RCM having a destination LD which corresponds to its own LD.
  • the RCM is decoded and establishes that data will be sent by the reader to the badge in slot K.
  • the data is received at slot K of the DSM and is decoded. If the data is received intact, the badge executes whatever function is required and then prepares and acknowledge signal so as to indicate whether the required function were carried out successfully or not.
  • the ACK signal is transmitted by the badge to the reader during a randomly allocated ASM slot and the badge returns to standby mode.
  • Fig. 10a is a flow diagram showing the principal operating steps carried out by the reader during the transmission of a long message from the badge to the reader.
  • the ASM is decoded and the parameters therein are stored.
  • the next RCM is prepared and transmitted to the badge.
  • the reader then awaits receipt of a DSM from the badge, upon receipt of which the data is decoded and, if intact, is stored and forwarded to the central computer. Thereafter; the next RCM is prepared acknowledging receipt of the DSM.
  • the RCM is transmitted to the badge and receipt of the ASM transmitted by the badge is then awaited.
  • the reader decodes the data, and, if intact, resumes normal operation.
  • Fig. 10b shows the corresponding flow chart relating to the principal operating steps carried out by the badge during the transmission of a long message to the reader.
  • the ASM and DSM are prepared and the badge then awaits receipt of a RCM transmitted thereto by the reader.
  • the data is decoded and, if intact, the parameters are stored. It will be recalled that the parameters correspond to the information fransmitted by the reader to the badge indicating in which DSM subsequent data is to be transmitted by the badge to the reader. Receipt of the RCM is then acknowledged by the badge in the next ASM.
  • the badge then awaits receipt of the next RCM, upon receipt of which the data is decoded and, if intact, this permits determination as to which data slot contains the transmitted data intended for the current badge. If no ED is found, the loop is repeated until a valid RCM is received. Again, in the absence of a valid RCM being received within a predetermined number of cycles (i.e. as shown in the figure) a communication error is provided and the badge returned to standby mode.
  • the badge is informed that it must transmit the data to the reader in DSM slot K.
  • the required data is therefore decoded in slot K and transmitted by the badge to the reader, whereupon the badge now awaits receipt of a subsequent RCM from the reader.
  • the badge Upon receipt thereof the transmitted information is decoded and if the RCM is valid, the badge checks whether the receipt of the data previously sent by the badge to the reader has been acknowledged by the reader. If so, then a suitable signal may be output (e.g. an audible beep); the end ASM is prepared and transmitted; and the badge returns to standby mode.
  • a suitable signal may be output (e.g. an audible beep); the end ASM is prepared and transmitted; and the badge returns to standby mode.
  • Fig. 1 la is a flow diagram showing the principal operating steps carried out by the reader when the badge sends a short-location message thereto.
  • the reader upon receipt by the reader of a badge ASM, the received data is decoded and, if valid, the short parameters are stored and the message corresponding thereto is transmitted to the central computer. Thereafter; the reader prepares the next RCM containing a suitable acknowledge signal which is then transmitted to the badge, whereupon the reader resumes normal operation.
  • Fig. l ib shows the corresponding flow diagram of the functions performed by. the badge during transmission of a short location message to the reader.
  • the ASM-short message is prepared whereafter the badge awaits the RCM from the reader which should be received within a predetermined time period t ⁇ T. if the RCM is received within the correct time period, it is decoded and, if valid, the parameters encoded therein are stored. The ASM-short message is then transmitted to the reader and the badge awaits the RCM transmitted by the reader. Upon receipt thereof the RCM is decoded and, if valid, the acknowledged message is decoded in order to verify that the short message transmitted by the badge to the reader was received correctly. In this case, no further action is required.
  • the badge re-transmits the short message to the reader, the whole cycle being repeated for a predetermined number of cycles e.g. 3 whereafter, if still no acknowledged signal is correctly received, a communication error is displayed and the badge returns to standby mode.
  • the badge resorts to standby mode. The assumption is that when a badge indicates to the reader that it wishes to transmit a short message thereto, the reader will acknowledge that request substantially immediately unless, of course, communication between the reader and the badge is broken for some reason. Therefore, lack of receipt by the badge of the RCM within this time period is interpreted as a fault in the communication between the reader and the badge.

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Abstract

La présente invention concerne un procédé et un système destinés à effectuer une communication IR de données bidirectionnelle entre une pluralité de N de lecteurs (21, 22, 23) et une pluralité M d'objets portables, chacun étant associé à un émetteur-récepteur d'objet (24, 25, 26, 27) respectif, initialement en sommeil, et dans lequel est intégré une identification (ID) respective d'objet qui identifie l'objet de manière unique. Chaque lecteur émet vers un émetteur-récepteur d'objet un préambule contenant l'ID d'objet afin d'éveiller l'émetteur-récepteur d'objet de son état initial dormant, ainsi qu'un message de commande de lecteur (RCM) comprenant une en-tête, une ID de lecteur respectif de manière à permettre au lecteur d'être adressé si besoin, suivi de K ID d'objet (K < M) chacune concernant l'un des émetteurs-récepteurs d'objet et chacune étant suivie d'une commande respective destinée à commander l'émetteur-récepteur d'objet respectif. Jusqu'à K intervalles de données sont alloués à chacun afin de permettre une communication d'un message de données entre le lecteur respectif et l'un des émetteurs-récepteurs d'objet, et chacun des M émetteurs-récepteurs d'objet peut choisir aléatoirement un des R intervalles d'allocation afin de transmettre des données de capacité limitées au lecteur respectif.
EP99952777A 1998-10-29 1999-10-29 Systeme et procede pour communication infra-rouge Ceased EP1125380A2 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
IL12679998A IL126799A (en) 1998-10-29 1998-10-29 System for infrared communication and method therefor
IL12679998 1998-10-29
PCT/IL1999/000572 WO2000026686A2 (fr) 1998-10-29 1999-10-29 Systeme et procede pour communication infra-rouge

Publications (1)

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EP1125380A2 true EP1125380A2 (fr) 2001-08-22

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EP99952777A Ceased EP1125380A2 (fr) 1998-10-29 1999-10-29 Systeme et procede pour communication infra-rouge

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EP (1) EP1125380A2 (fr)
AU (1) AU6486199A (fr)
IL (1) IL126799A (fr)
WO (1) WO2000026686A2 (fr)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1485858B1 (fr) 2002-03-13 2009-11-11 Nxp B.V. Station de communication pour la communication avec des transpondeurs et d'autres stations de communication au moyen de protocoles differents
EP1432151A1 (fr) * 2002-12-19 2004-06-23 Abb Research Ltd. Système et procédé de localisation sur site
ES2291097B2 (es) * 2005-12-20 2009-08-17 Universidad Politecnica De Cartagena Procedimiento y sistema para la identificacion de elementos identificadores moviles y lector y elemento identificador movil utilizados en dicho procedimiento.

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5742238A (en) * 1995-09-01 1998-04-21 Emtrak, Inc. System for communication between a central controller and items in a factory using infrared light

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO0026686A2 *

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Publication number Publication date
WO2000026686A3 (fr) 2000-09-08
WO2000026686A2 (fr) 2000-05-11
IL126799A0 (en) 1999-08-17
AU6486199A (en) 2000-05-22
IL126799A (en) 2005-05-17

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