Communications system and communications apparatus

Abstract

A communications system configured to execute data transmission between a transponder having no radio wave generating source thereof and a reader/writer is provided. The communications system includes, a service permission level notifier configured to tell a service permission level for associated with a received signal level for permitting service acceptance from the reader/writer to the transponder, and an access controller configured to determine in the transponder whether the received signal level from the reader/writer is at the notified service permission level to determine accessibility to the transponder from the reader/writer.

Claims

1. A first apparatus comprising: a communication circuit which is configured to communicate with a second apparatus; and a controller which is configured to control the first apparatus to: receive, from the second apparatus, a beacon frame including identification information written in the beacon frame; wherein the controller is further configured to determine whether the first apparatus is within a service area identified by said identification information, and wherein the service area, which is identified by said identification information written in the beacon frame, has an access range that is determined depending on a service, and a first service has a different service area than a second service.

2. The first apparatus of claim 1, further comprising: a measuring unit which is configured to measure an RSSI (Receiving Signal Strength Indicator) of the beacon frame.

3. The first apparatus of claim 2, wherein the controller is further configured to estimate an approximate proximity to the second apparatus using the RSSI of the beacon frame measured with the measuring unit.

4. The first apparatus of claim 3, further comprising: a memory which is configured to store at least one application.

5. The first apparatus of claim 4, wherein the controller is further configured to activate the at least one application when the controller determined that the first apparatus is within the service area.

6. The first apparatus of claim 5, wherein the at least one application is associated with said identification information.

7. The first apparatus of claim 4, wherein the controller is further configured to control access to the memory based on said approximate proximity.

8. A method for communicating between a first apparatus and a second apparatus, the method comprising: receiving, from the second apparatus, a beacon frame including identification information written in the beacon frame; and determining whether the first apparatus is within a service area identified by said identification information, wherein the service area, which is identified by said identification information written in the beacon frame, has an access range that is determined depending on a service, and a first service has a different service area than a second service.

9. The method of claim 8, wherein the method is further comprising: measuring an RSSI (Receiving Signal Strength Indicator) of the beacon frame.

10. The method of claim 9, further comprising: estimating an approximate proximity to the second apparatus using the RSSI of the beacon frame.

11. The method of claim 10, further comprising: activating an application in response to determining that the first apparatus is within the service area.

12. The method of claim 11, wherein the application is associated with said identification information.

13. The method of claim 10, further comprising: controlling access to a memory based on said approximate proximity.

14. A non-transitory computer readable medium storing instructions for communicating between a first apparatus and a second apparatus which, when executed, cause the first apparatus to: receive, from the second apparatus, a beacon frame including identification information written in the beacon frame; and determine whether the first apparatus is within a service area identified by said identification information, wherein the service area, which is identified by said identification information written in the beacon frame, has an access range that is determined depending on a service, and a first service has a different service area than a second service.

15. The non-transitory computer readable medium of claim 14, wherein the instructions stored in the medium, when executed, further cause the first apparatus to: measure an RSSI (Receiving Signal Strength Indicator) of the beacon frame.

16. The non-transitory computer readable medium of claim 15, wherein the instructions stored in the medium, when executed, further cause the first apparatus to: estimate an approximate proximity to the second apparatus using the RSSI of the beacon frame.

17. The non-transitory computer readable medium of claim 16, wherein the instructions stored in the medium, when executed, further cause the first apparatus to: activate an application in response to determining that the first apparatus is within the service area.

18. The non-transitory computer readable medium of claim 16, wherein the instructions stored in the medium, when executed, further cause the first apparatus to: activate an application associated with said identification information in response to determining that the first apparatus is within the service area.

19. The non-transitory computer readable medium of claim 16, wherein the instructions stored in the medium, when executed, further cause the first apparatus to: control access to a memory based on said approximate proximity.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) FIG. 1 is a schematic diagram illustrating an exemplary configuration of a communications system practiced as one embodiment;

(2) FIG. 2 is a block diagram illustrating an exemplary internal configuration of a memory card in which a transponder is incorporated;

(3) FIG. 3 is a circuit diagram illustrating an exemplary internal configuration of a radio section in the memory card shown in FIG. 2;

(4) FIG. 4 is a block diagram schematically illustrating an exemplary internal configuration of a reader/writer that functions as a reflected-wave reader with which the radio section shown in FIG. 3 communicates;

(5) FIG. 5 is a diagram illustrating an exemplary frame format of a beacon signal that is used in the communications system according to an embodiment;

(6) FIG. 6 is a circuit diagram illustrating an exemplary configuration of the radio section having means of transmitting RSSI measurement results to a memory/communications control section;

(7) FIG. 7 is a sequence chart indicative of an exemplary communications sequence to be executed between a transponder and a reader/writer in the communications system according to an embodiment;

(8) FIG. 8 is a perspective view of a host device incorporating a transponder such as a reflector arranged on a reading surface of a reader/writer such as a reflected-wave reader, thereby executing a reading/writing operation with the transponder;

(9) FIG. 9 is a sequence chart indicative of a communications control sequence for executing reflected-wave transmission between a transponder and a reader/writer by use of a service entry sequence; and

(10) FIG. 10 is a sequence chart indicative of a sequence to be executed when starting a communications operation by use of the service entry sequence shown in FIG. 9 between a reader/writer and a transponder.

DETAILED DESCRIPTION

(11) Referring to FIG. 1, there is schematically shown a communications system according to one embodiment. The communications system shown is made up of a memory card 100 incorporating a transponder, not shown, a host device 120 with this memory card 100 loaded in a dedicated slot thereof, and a reader/writer 300 configured to execute noncontact data transmission with the transponder. The host device 120 may be a mobile device configured to accommodate the memory card 100, such as a digital camera or a mobile phone with camera. The transponder passively operates on a radio wave energy supplied from the reader/writer 300. The reader/writer 300 reads information stored in the transponder and writes information thereto.

(12) Noncontact communications methods include electrostatic coupling, electromagnetic induction, and radio communicating, for example. In what follows, the application of radio communicating is assumed, thereby executing reflected-wave transmission called backscatter. The reflected-wave communicating is characterized by a low power dissipation in a communications form in which the transmission from the reflector side occupies most of communication.

(13) The transponder has a reflector configured to transmit data by a reflected wave obtained by modulating a non-modulated carrier. The reader/writer 300 has a reflected-wave reader configured to read the data out of a modulated reflected-wave signal supplied from the reflector. Receiving a non-modulated carrier from the reflected-wave reader, the reflector modulates the received reflected wave by switching between antenna load impedances for example, thereby superimposing data on the non-modulated carrier. The reflected-wave reader receives this modulated reflected wave to demodulate and decode the received modulated reflected wave, thereby obtaining transmission data.

(14) Configuring an antenna load impedance switch with a GaAs IC allows a high-speed switching operation with low power dissipation, which is smaller than about several 10 μW. This configuration can also realize high-speed data transmission in a high frequency band of 2.4 GHz (micro wave).

(15) Although the transponder can obtain electrical power by rectifying a carrier transmitted by the reader/writer 300, the electrical power thus obtained is insufficient for the transmission of large amounts of data at high speeds. Namely, the transponder need not the electrical power for generating a carrier at the time of transmission. However, an electrical power necessary for executing a transmitting operation for modulating a reflected wave and a receiving operation for demodulating and decoding a modulated signal from the reader/writer 300 is supplied from the host device 120.

(16) FIG. 2 shows an exemplary internal configuration of the memory card 100 in which a transponder is built. The memory card 100 shown has a flash memory 103 making up a storage block, a terminal section 101, a memory/communications control section 102, a radio section 104, and an antenna 105.

(17) A contact portion of the terminal section 101 is exposed outside, being connectable with the host device 120 as with an ordinary memory card. The flash memory 103 is able to store data in an electrically rewritable manner. The memory/communications control section 102 transfers data between the host device 120 and the flash memory 103 via the terminal section 101 and transmits data of the memory/communications control section 102 to the reader/writer 300 via the radio section 104 and the antenna 105 in the form of reflected waves. The radio section 104 is equivalent to a transponder in a noncontact communications system.

(18) FIG. 3 shows an exemplary internal configuration of the radio section 104 in the memory card 100 shown in FIG. 2. The radio section 104 shown, equivalent to a transponder in a noncontact system, can operate here as a reflector in reflected-wave transmission.

(19) Reference numeral 200 denotes an antenna switch of an SPDT (Single Pole/Double Throw) switch, which also switches between reflected-wave generation and transmission/reception. In the figure, terminal c is connected to the antenna 105 in the memory card 100. The antenna switch 200 is configured by a GaAs IC, for example, separate from another CMOS circuit module.

(20) When transmission is made from the radio section 104, terminal b is turned off by a control signal (TX/RX) from a baseband control section (not shown). Next, transmission data (TX_DATA) is applied to terminal a from the baseband control section. As shown in the figure, because terminal d of the antenna switch 200 is grounded, if the transmission data is “1”, the terminal of the antenna 105 is short-circuited. If the transmission data is “0”, the terminal of the antenna 105 is opened. Thus, on the basis of a bit image of transmission data, the switching of the antenna switch 200 (namely, the switching of the terminal of the antenna 105) phase-modulates a non-modulated carrier received from the antenna 105, the phase-modulated carrier being radiated from the antenna 105 as a modulated reflected-wave signal.

(21) On the other hand, at the time of reception by the radio section 104, terminal b is kept on by the baseband control section, not shown. Therefore, an ASK (Amplitude Shift Keying) modulated signal received at the antenna 105 is transmitted to an ASK reception block 201 via terminal e to be demodulated into reception data (RX_DATA). Thus, the reception data is passed to the baseband control section, not shown.

(22) FIG. 4 schematically shows an exemplary internal configuration of the reader/writer 300 as a reflected-wave reader with which the radio section 104 shown in FIG. 3 makes communication. The reader/writer 300 shown has an antenna 301, a circulator 302, a reception section 303, a transmission section 304, and a baseband control section 305.

(23) The transmission section 304 generates a non-modulated carrier as instructed by the baseband control section 305. The non-modulated carrier is radiated toward the radio section 104 from the antenna 301 via the circulator 302. The circulator 302 is used to separate the transmission wave from the reception wave when transmission and reception are executed at the same time.

(24) As described above, the radio section 104 generates a reflected wave for the non-modulated carrier from the reader/writer 300, the reflected wave being phase modulated in accordance with read data, so that the reflected wave is returned to the reader/writer 300 as a modulated reflected wave. Being received by the reception section 303 via the antenna 301 and the circulator 302, this modulated reflected wave is converted into a baseband IQ signal made up of in-phase (I) and quadrature (Q) thereof to be demodulated in the baseband control section 305.

(25) In transmitting data and a control command from the reader/writer 300 to the radio section 104, the transmission section 304 generates an ASK modulated wave in accordance with transmission data from the baseband control section 305, the generated ASK modulated wave being radiated from the antenna 301.

(26) The baseband control section 305 has an interface for other devices. This interface can decode read image data and supply the decoded image data to a television set, not shown, as a video signal to be displayed or to a PC, not shown, connected via USB (Universal Serial Bus).

(27) In the present embodiment, it is assumed that the service entry sequence shown in FIGS. 9 and 10 be applied to the communications control between the transponder and the reader/writer 300. Namely, the reader/writer 300 transmits a beacon frame to tell a service area of the reader/writer 300 and the transponder returns an entry frame within a predetermined entry period in response, upon which the connection between the reader/writer 300 and the transponder is established via a connection request and a connection response sequence.

(28) It is not necessary for the reader/writer 300 to always keep transmitting a beacon frame at a certain time interval. However, when the reading of information from the transponder becomes necessary (to be more specific, every time an application for reading/writing data with the transponder is started up), the reader/writer 300 starts a beacon transmitting operation. For example, the reader/writer 300 transmits a beacon frame every 10 to 100 millisecond.

(29) Also, in the present embodiment, when the reader/writer 300 starts up an application for reading/writing information with the transponder, the reader/writer 300 sets a service permission level suitable for that application (or the type of the application) and writes the service permission level to the beacon frame. In response, having received the beacon frame, the transponder interprets the contents of the received beacon frame and determines the accessibility by the reader/writer depending on whether the received signal level of this beacon frame is at the service permission level.

(30) Here, it is assumed that the reader/writer transmit a beacon frame at a certain transmission power and the transponder receive the beacon frame basically by direct wave (line-of-sight communication), the received signal level at the transponder side being proportional to the communication distance with the reader/writer.

(31) For example, having started up an application for executing data communication of high security, the reader/writer 300 sets a higher service permission level to transmit a beacon frame. In response, if the beacon received signal level is high, or only if the reader/writer 300 is located in the proximity, the transponder permits access by the reader/writer 300, so that the interception by nearby communications terminals can be prevented.

(32) On the other hand, if the reader/writer 300 has started up an application for executing data communication, such as image or audio data requiring low security, there is little need for caring about interception. Therefore, the reader/writer 300 sets a low service permission level to transmit a beacon frame and, in response, the transponder permits access by the reader/writer 300 when the beacon received signal level is low, or the communication distance with the reader/writer 300 is comparatively long, so that the user need not bring the reader/writer 300 and the transponder closest to each other, thereby enhancing the ease of use.

(33) FIG. 5 shows a frame format of a beacon signal that is used in the communications system according to an embodiment.

(34) A beacon frame 500 is made up of elements of information, such as a preamble 501, a unique word 502, an ID 503 of reader, a service permission level 504, notification information 505, and an error verification code (CRC) 506.

(35) The preamble 501 is used for bit (symbol) synchronization to be executed at demodulation. The unique word 502 is indicative of a data start position. The ID 503 is an identifier uniquely assigned to every reader. The notification information 505 stores communication-associated parameters and service information. A beacon period is also stored in the notification information 505. The error verification code (CRC) 506 is a CRC (Cyclic Redundancy Code) parity assigned to the data from the ID 503 to the notification information 505 of every beacon frame.

(36) The service permission level 504 is an information element newly added to the present embodiment in order for the reader/writer 300 to control a communicable area corresponding to every application. The service permission level 504 is indicative how high the reception level of a beacon signal from the reader/writer 300 should be.

(37) For example, assume that 60 [dBμV] be displayed as the service permission level 504. In this case, if a beacon signal is received from the reader/writer 300 at 50 [dB μV], the transponder cannot request the reader/writer 300 for connection. If a beacon signal is received from the reader/writer 300 at 65 [dBμV], the transponder can transmit a connection request signal to the reader/writer 300.

(38) Therefore, having started up an application for executing data communication of high security, the reader/writer 300 sets the service permission level 504 at a high level to transmit a beacon frame. In response, the transponder operates to permit access by the reader/writer 300 only when the reader/writer 300 is in the proximity, thereby preventing the interception by nearby communications terminals.

(39) On the other hand, when the reader/writer 300 has started up an application for executing data communication of image or audio data of low security, there is little necessity for taking the interception into consideration, so that the reader/writer 300 sets the service permission level to a low level to transmit a beacon frame. In this case, if the communications distance is comparatively long, the transponder permits the access by the reader/writer 300, so that the user need not bring the communications devices closest to each other, thereby enhancing the ease of use.

(40) In accordance with the service permission level 504 in the received beacon frame, the transponder controls the access by the reader/writer 300 depending on the received signal strength of the received beacon (or another frame received from the reader/writer 300).

(41) Hence, the radio section 104 in the transponder has means of measuring RSSI (Receiving Signal Strength Indicator). In the basis of a result of RSSI measurement, the memory/communications control section 102 determines whether to transmit a connection request frame to the reader/writer 300 (or whether to return a connection response frame in response to the connection request frame received from the reader/writer 300).

(42) FIG. 6 shows an exemplary configuration of the radio section 104 having the means of transmitting RSSI measurement results to the memory/communications control section 102. A difference between the configuration shown in FIG. 6 from that shown in FIG. 3 lies in that the ASK reception block 201 is provided with the means of transmitting RSSI to the memory/communications control section 102. The measurement of reception level is easy because ASK reception is executed originally.

(43) FIG. 7 shows an exemplary communications sequence that is executed between the transponder and the reader/writer 300 in the communications system according to the embodiment. It should be noted that, although not shown in the figure, the transponder is assumed to return an entry frame in response to a beacon frame transmitted from the reader/writer 300. Also, when the transponder transmits a connection request signal or other signals, it is assumed that a non-modulated carrier be supplied from the reader/writer 300 in advance.

(44) Having received the beacon frame 400, the transponder reads and stores the service permission level 504 contained in the beacon frame 400. Further, the transponder measures the reception level of the beacon frame 400 (601) to determine whether the reception level is higher than the service permission level (602).

(45) If the reception level is found to be higher than the service permission level 504, then the transponder transmits, to the reader/writer 300, the connection request frame 401 as a modulated reflected-wave signal in response to the non-modulated carrier received from the reader/writer 300.

(46) In response, having received the connection request signal 401 from the transponder, the reader/writer 300 returns a connection response frame 402 to the transponder. This establishes connection between the transponder and the reader/writer 300, thereby putting the communications system into the communication state 403.

(47) While embodiments have been described using specific terms, such description is for illustrative purpose only.

(48) In the description hereof made so far, the embodiment applied to communications systems configured to execute reflected-wave transmission has been mainly described. However, the embodiments not limited thereto. For example, even with communications systems employing another communications scheme in which the transponder having no radio wave generating source of its own executes a data transmitting operation, such as electrostatic coupling or electromagnetic induction, the embodiments are applicable in the same manner in a situation where the reader/writer need to control the communicable area with the transponder for every application. Alternatively, the present embodiments are applicable in the same manner to communications systems in which both the transmitting and receiving communications devices have radio wave generating sources of their own.

(49) It should be understood that various changes and modifications to the presently preferred embodiments described herein will be apparent to those skilled in the art. Such changes and modifications can be made without departing from the spirit and scope of the present subject matter and without diminishing its intended advantages. It is therefore intended that such changes and modifications be covered by the appended claims.