Classifications

• • 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
  • H04W52/0225—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
  • H04W68/00—User notification, e.g. alerting and paging, for incoming communication, change of service or the like
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W84/00—Network topologies
  • H04W84/18—Self-organising networks, e.g. ad-hoc networks or sensor networks
• • 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

• the present invention relates to a method of reducing the consumption of electric current when establishing a connection for communication through the medium of a Bluetooth link.
• Bluetooth technology involves radiocommunication with a link between two Bluetooth units.
• a typical feature of Bluetooth communication is that the communication frequency hops between 79 channels with a band width of 1 MHz in the license-free ISM-band, i.e. 2.4 GHz.
• a Bluetooth radio will normally hop, i.e. change frequency, 1600 times per second.
• Bluetooth is a so-called TDM-system (Time Division Multiplexing) and each time slot has a duration of 625 microseconds.
• All Bluetooth units have a world-unique address, a so-called Bluetooth Device Address (BD_ADDR) that has a length of 48 bits.
• BD_ADDR Bluetooth Device Address
• the frequency hop sequence is a pseudo random sequence that is determined by BD_ADDR and a real time clock (CLK), which is found in all Bluetooth units or devices.
• the Bluetooth unit that initiates a coupling between two units is called the “Master” and the unit that accepts a coupling request is called the “Slave”.
• the frequency hop sequence is determined by the clock and the address of the Master.
• the Slave adjusts its clock to coincide with the Master clock, so that the Master and Slave will constantly be in synchronisation.
• a Slave unit awaiting a paging message awakens every 1.28 seconds (Scan Interval) and listens for a paging message for a time duration of 11.25 milliseconds (Scan Window).
• a paging message includes the Slave access code, which is constructed on the basis of the Slave's BD_ADDR.
• a new frequency is chosen from said 32 frequencies, each time the Slave awakens.
• the Master divides the 32 page frequencies into two trains, train A and train B each consisting of 16 frequencies.
• Train A includes the frequency on which the Master anticipates that the Slave will awaken together with the remaining 15 frequencies.
• Train B consists of the remaining 16 .
• Estimation of the frequency on which the Slave will awaken is based typically on clock information from an earlier connection with the Slave or on the basis on information that has been obtained from an inquiry.
• the average time for a paging message will not be shorter than 0.64 sec, since the Master is forced to wait until the Slave awakens and carries out a page scan. In the worst case, it takes 1.27 sec. before the Slave awakens.
• the page-scan interval can be extended to 2.56 seconds in order to save energy, although at the cost of a longer paging message time.
• Inquiry Procedure Inquiry Procedure
• the inquiry procedure has very much in common with the paging procedure described above.
• the Slave that makes an inquiry scan awakens every 1.28 seconds on one of the 32 frequencies in 11.25 milliseconds and listens for a code (Inquiry Scan), the so-called GIAC (General Inquiry Access Code) or DIAC (dedicated Inquiry Access Code). Because the inquiry may be heard by several Slaves, it is possible that a collision would occur if all Slaves answered simultaneously.
• GIAC General Inquiry Access Code
• DIAC dedicated Inquiry Access Code
• the Slave responses to an inquiry are in the form of a so-called FHS (Frequency Hop Synchronisation) packet.
• FHS-packet has 144 bits of useful information and includes the following information, among other things: BD_ADDR, CLK, the class of device.
• the types of device concerned may be a cellphone, mobile telephone. LAN access point, printers, etc..
• the FHS-packet thus includes the information required to establish the connection.
• the present invention solves this problem.
• the present invention relates to a method of reducing the amount of electric current required in the establishment of a connection in accordance with Bluetooth technology, comprising an inquiry and a paging procedure between a master unit and a slave unit, each of which includes a Bluetooth module, wherein the invention is characterised in that the Bluetooth module of the slave unit is caused, when not connected, to take a standby mode in which it does not listen for an inquiry or for paging from the master unit (1); in that when a master unit wishes to be connected to a slave unit, the master unit is caused to send by means of a first transceiver a signal to a second transceiver in the slave unit; in that upon receipt of said signal, the transceiver in the slave unit sends to the Bluetooth module of the slave unit a wake-up signal; and in that the two Bluetooth modules then establish a connection.
• Figure 1 is a block diagram of an arrangement with which the invention can be applied.
• the present invention is intended to reduce the amount of electric current required to establish a connection in accordance with Bluetooth technology.
• Such technology involves an inquiry and a paging procedure between a master unit 1 and a slave unit 2 in order to establish a connection.
• the Bluetooth module 5 of the slave unit 2 when not connected, the Bluetooth module 5 of the slave unit 2 is caused to take a standby mode in which the Bluetooth module 5 does not listen for an inquiry or to paging from the master unit 1.
• the master unit When a master unit 1 wishes to page a slave unit 2, the master unit is caused to activate a first transceiver 4 in the master unit with a signal 11.
• the first transceiver unit 4 is therewith caused to send a signal 8 to a second transceiver unit 6, included in the slave unit
• the transceiver 6 of the slave unit 2 Upon receipt of the signal 8, the transceiver 6 of the slave unit 2 is caused to send a wake-up signal 9 to the Bluetooth module 5 of the slave unit 2.
• the two Bluetooth modules
• the transmission shown in Figure 1 by the arrows 7 and 8 is a radio transmission effected with the aid of an antenna (not shown) included in the master unit 1 and an antenna (not shown) included in the slave unit 2.
• the amount of current required to power the Bluetooth modules is reduced solely to the current required for the actual inquiry and paging procedures.
• the slave units draw very little current whilst in their standby mode, since they do not listen for an inquiry or for paging from the master unit in this mode
• each of the transceivers 4, 6 includes an RFID (Radio Frequency Identification) module.
• RFID Radio Frequency Identification
• RFID-modules are known to the art and are described in Swedish Patent Specification 0103762-1 for instance. This Patent Specification also describes the co-action between Bluetooth modules and RFID modules. Consequently, an RFLO module will not be described in greater detail here.
• One big advantage with RFID is that in certain applications a Bluetooth connection can be established within a limited geographical zone whose magnitude is determined by the communication between the RFID-modules.
• the inquiry is in the form of a carrier wave 8 which is caused to be sent from the first transceiver unit 4 to the second transceiver unit 6.
• the second transceiver unit 6 when the carrier wave 8 is received by the second transceiver unit 6 said second transceiver unit is caused to re-transmit the received carrier wave 8 and to modulate said signal with FHS-information for the slave unit.
• This procedure eliminates the conventional inquiry procedure and therewith further lowers the amount of current required in addition to shortening the inquiry procedure of the Bluetooth link.
• the second transceiver unit 6 it is preferred to cause the second transceiver unit 6 to reflect the received carrier wave 8 and therewith modulate the same, and to re-transmit the modulated carrier wave to the first transceiver unit 4.
• Such an embodiment can be implemented so that the RFID-module of the slave unit will not need to deliver fresh energy to the received carrier wave, therewith rendering the slave unit extremely lean with regard to electric current requirements.
• the FHS-information of the slave unit 2 is caused to be stored in a memory accessible to the second transceiver unit 6.
• the invention enables the electric current required to power the slave unit to be reduced significantly, as repetitive inquiries of the slaves are eliminated.
• Typical applications of the present invention include those in which contact with a current- lean slave unit is desired within a geographically restricted area. Examples of such applications are authorisation checks, bus and train adaptation, road tolls, etc..

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• Engineering & Computer Science (AREA)
• Computer Networks & Wireless Communication (AREA)
• Signal Processing (AREA)
• Mobile Radio Communication Systems (AREA)
• Transceivers (AREA)
• Small-Scale Networks (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=20286780

Family Applications (1)

Country Status (2)

Cited By (10)

Citations (2)

• 2002
  • 2002-01-28 SE SE0200233A patent/SE0200233L/sv not_active Application Discontinuation
• 2003
  • 2003-01-21 WO PCT/SE2003/000091 patent/WO2003065289A1/en not_active Application Discontinuation

Patent Citations (2)

Non-Patent Citations (4)

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