Communication apparatus and communication method

• US 7,209,706 B2
• Filed: 11/19/2003
• Issued: 04/24/2007
• Est. Priority Date: 12/17/2002
• Status: Active Grant

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Morita, Tadashi, Arisawa, Shigeru, Fujii, Kunihide, Takayama, Yoshihisa
• Primary Examiner(s): Phu; Sanh D.
• Application Number:
  US10/715,447
• Publication Number:
  US 20040116074A1
• Time in Patent Office: 1,252 Days
• Field of Search: 455/41.2, 455/88, 455/410, 342/42, 342/44, 342/50
• US Class Current: 455/41.2
• CPC Class Codes: G06K 19/0723 the record carrier comprising an arrangement for non-contact communication, e.g. wireless communication circuits on transponder cards, non-contact smart cards or RFIDs
• CPC Class Codes: G06K 7/0008 General problems related to the reading of electronic memory record carriers, independent of its reading method, e.g. power transfer
• CPC Class Codes: G06K 7/10029 the collision being resolved in the time domain, e.g. using binary tree search or RFID responses allocated to a random time slot
• CPC Class Codes: G06K 7/10237 the reader and the record carrier being capable of selectively switching between reader and record carrier appearance, e.g. in near field communication [NFC] devices where the NFC device may function as an RFID reader or as an RFID tag

Abstract

A communication apparatus and a communication method prevent responses from being simultaneously received from two or more communicating parties. A first NFC apparatus transmits data for requesting IDs, and acquires IDs sent from second and third NFC apparatuses in reply to the request. After acquiring the IDs of the second and third NFC apparatuses, the first NFC apparatus transmits data that includes their IDs as the data for the second and third NFC apparatuses. If the first NFC apparatus cannot properly acquire the IDs of the second and third NFC apparatuses, then it sends the data for requesting their IDs again. Upon receipt of the request for the IDs, the second and third NFC apparatuses generate their own IDs by using random numbers and send the generated IDs. If the second and third NFC apparatuses receive the request for their IDs again, then they re-generate their own IDs by using random numbers, and send the re-generated IDs again. The present invention can be applied to, for example, an IC card system.

Claims

1. A communication apparatus for sending and receiving data by electromagnetic waves, comprising:

electromagnetic wave generating means for forming a radio frequency (RF) field by generating electromagnetic waves;

modulating means for sending data at one of a plurality of transmission rates by modulating electromagnetic waves;

demodulating means for demodulating electromagnetic waves so as to acquire data sent from other apparatus at one of the plurality of transmission; and

a detector configured to detect a radio frequency field within a first time period before the communication apparatus initiates a communication with other communication apparatus and within a second time period before the communication apparatus responds to a request of said other communication apparatus,

the first time period is defined by T_IDT+nxT_RFW, where T_IDT is a first initial delay time, n is a first random number, and T_RFW is a first radio frequency waiting time, and said communication apparatus generates a first radio frequency when the radio frequency field is not detected by the detector within the first time period,

the second time period is defined by T_ADT+n′

xT_RFW, where T_ADT is a second active delay time, n′

is a second random number, and T_IDT is larger than T_ADT and said communication apparatus generates a second radio frequency when the radio frequency field is not detected by the detector within the second time period,

wherein data for requesting an identification (ID) to identify the other apparatus is sent,

the ID sent from the other apparatus in reply to the request for the ID is acquired, and the ID sent from the other apparatus includes a random number generated in the other apparatus;

data that includes the ID of the other apparatus is sent as the data for the other apparatuses after acquiring the ID of the other apparatus, and

data for requesting the ID is sent again if the ID of the other apparatus has not been properly acquired.

2. The communication apparatus according to claim 1, wherein the data for requesting IDs is sent again if the IDs are simultaneously received from a plurality of other apparatuses or if any overlapping IDs are received from the plurality of other apparatuses.

3. A communication method for a communication apparatus for sending and receiving data by electromagnetic waves, comprising:

generating electromagnetic waves to form a radio frequency (RF) field;

modulating electromagnetic waves to send data at one of a plurality of transmission rates;

demodulating electromagnetic waves to acquire data transmitted from other apparatus at one of the plurality of transmission rates;

detecting a radio frequency field within a first time period before the communication apparatus initiates a communication with other communication apparatus and within a second time period before the communication apparatus responds to a request of said other communication apparatus, wherein

the first time period is defined by T_IDT+nxT_RFW, where T_IDT is a first initial delay time, n is a first random number, and T_RFW is a first radio frequency waiting time, and said communication apparatus generates a first radio frequency when the radio frequency field is not detected by the detector within the first time period, and

the second time period is defined by T_ADT+n′

xT_RFW, where T_ADT is a second active delay time, n′

is a second random number, and T_IDT is larger than T_ADT and said communication apparatus generates a second radio frequency when the radio frequency field is not detected by the detector within the second time period;

sending data for requesting identification (ID) to identify the other apparatus;

acquiring the ID sent from the other apparatus in reply to the request for the ID, wherein the ID sent from the other apparatus includes a random number generated in the other apparatus;

sending data that includes the ID of the other apparatus as the data for the other apparatus after acquiring the ID of the other apparatus; and

sending data for requesting the ID again if the ID of the other apparatus has not been properly acquired.

4. A communication apparatus for sending and receiving data by electromagnetic waves, comprising:

modulating means for modulating electromagnetic waves to send data at any one of a plurality of transmission rates;

demodulating means for demodulating electromagnetic waves to acquire data sent from other apparatus at any one of the plurality of transmission rates; and

a detector configured to detect a radio frequency field within a time period before the communication apparatus responds to a request of said other apparatus, wherein the time period is defined by T_ADT+n′

xT_RFW, where T_ADT is an initial delay time, n′

is a random number, and T_RFW is a radio frequency waiting time;

said communication apparatus is configured to send, when an active communication mode is initiated, a response to said other apparatus by emitting an electromagnetic wave that prevents the other apparatus from starting an emission of electromagnetic waves to a plurality of target devices at the same time;

said communication apparatus is configured to send, when a passive communication mode is initiated, a response from the communication apparatus to said other apparatus at a timing determined by a random number, the response including an identification (ID) to identify said communication apparatus,

wherein, when data for requesting the ID for identifying itself is received from the other apparatus, its ID is generated using a random number and the generated ID is sent,

when data for requesting the ID is received again from the other apparatus, its ID is generated again by using a random number and the re-generated ID is sent again, and

data that includes the ID of itself among the data sent from the other apparatus is received as the data for itself.

5. The communication apparatus according to claim 4, further comprising electromagnetic wave generating means for forming an RF field by generating electromagnetic waves,

wherein the modulating means sends data by modulating the electromagnetic waves output from the electromagnetic wave generating means.

6. The communication apparatus according to claim 4, wherein the modulating means sends data by load-modulating the electromagnetic waves generated by the other apparatus.

7. A communication method for a communication apparatus for sending and receiving data by electromagnetic waves, comprising:

modulating electromagnetic waves to send data at one of a plurality of transmission rates;

demodulating electromagnetic waves to acquire data sent from other apparatus at one of the plurality of transmission rates;

detecting a radio frequency field within a time period before the communication apparatus responds to a request of said other communication apparatus, wherein the time period is defined by T_ADT+n′

xT_RFW, where T_ADT is an initial delay time, n′

is a random number, and T_RFW is a radio frequency waiting time;

sending, when an active communication mode is initiated, a response to said other communication apparatus by emitting an electromagnetic wave that prevents the other communication apparatus from starting an emission of electromagnetic waves to a plurality of target devices at the same time;

sending, when a passive communication mode is initiated, a response from the communication apparatus to said other communication apparatus at a timing determined by a random number, the response including an identification (ID) to identify said communication apparatus;

receiving data for requesting the ID for identifying itself from the other apparatus, and generating the ID by using a random number and transmitting the generated ID,

when data for requesting ID is received again from the other apparatus, its ID is re-generated by using a random number and the re-generated ID is transmitted again, and

data that includes its ID among the data sent from the other apparatus is received as the data for itself.

8. A method of performing near-field communication between an initiator device and a target device, wherein the initiator device sends a command to the target device for starting the communication with a first electromagnetic wave modulated by data, the method comprising:

detecting at the initiator device a presence of a radio frequency field;

emitting the first electromagnetic wave from the initiator device to the target device, the first electromagnetic wave being configured to carry a request, when a radio frequency field is not detected within a time period defined by T_IDT+nxT_RFW, where T_IDT is an initial delay time, n is a random number, and T_RFW is a radio frequency waiting time;

initiating communication with the target device selectively in one of an active mode and a passive mode of communication, wherein

(1) when the active communication mode is initiated, there are a plurality of target devices which receive the command and the radio frequency field is not detected in the detecting step within a time period defined by T_ADT+n′

xT_RFW, where TADT is an active delay time, n′

is a random number, and T_IDT>

T_ADT, the initiator device detects a response from the target device through a second electromagnetic wave emitted by the target device to avoid starting the emission of electromagnetic wave by different target devices at the same time, and

(2) when the passive communication mode is initiated and there are a plurality of target devices which receive the command, the initiator device detects a response from the target device including an identification (ID) determined by a random number generated in the target device; and

resending the command to the target device when a collision of responses from a plurality of target devices occurs.

9. A method of performing near-field communication between an initiator device and a target device, wherein the initiator device is capable of initiating communication with the target device selectively in one of an active mode and a passive mode of communication and the target device responds to a command from the initiator device for starting communication with a first electromagnetic wave modulated by data, the method comprising:

(1) when the active communication mode is initiated and there are a plurality of target devices which receive the command;

detecting at the target device a presence of a radio frequency field,

when the radio frequency yield is not detected in said detecting step within a time period defined by T_ADT+n′

T_RFW, where T_ADT is an active delay time n′

is a random number, and T_RFW is a radio frequency waiting time, sending a response to the initiator device by emitting from the target device a second electromagnetic wave to avoid starting the emission of electromagnetic waves by a plurality of target devices at the same time; and

when the passive communication mode is initiated and where there are a plurality of target devices which receive the command;

sending a response from the target device to the initiator device at a timing determined by a random number, the response including an identification (ID) to identify the respective target device.

10. A communication apparatus for near-field wireless communications at a specified carrier frequency, the communication apparatus being configured to operate in active and passive communication modes and comprising:

a transmitter configured to generate a radio frequency field by generating carrier electromagnetic waves;

a modulator configured to transmit data by modulating the carrier electromagnetic waves in accordance with the data;

a detector configured to detect a presence of a radio frequency field; and

a controller arranged to configure the transmitter, modulator and detector such that;

(a) when the communication apparatus initiates an active or passive communication mode with another communication apparatus

the detector is configured to detect a presence of a radio frequency field within a first time period defined by T_IDT+nxT_RFW, where T_IDT is an initial delay time, n is a random number, and T_RFW a radio frequency waiting time, the transmitter is configured to generate a radio frequency when a radio frequency field is not detected by the detector within the first time period, and the modulator is configured to transmit a request to start communication with the another communication apparatus via the radio frequency field at one of a predetermined transfer rates, and

(b) when the communication apparatus responds to a request for initiation of an active communication mode by another communication apparatus

the detector is configured to detect a presence of a radio frequency field within a second time period defined by T_ADT+n′

xT_RFW, where T_ADT is an active delay time, n′

is a random number, and T_IDT>

T_ADT, the transmitter is configured to generate a radio frequency field when a radio frequency field is not detected by the detect in the second time period, and the modulator is configured to modulate the carrier electromagnetic device waves with a data signal to be transmitted to said another communication apparatus and to transmit a response to the request for initiation from the another communication apparatus via the radio frequency-field; and

(c) when the communication apparatus receives a request for initiation of a passive communication mode from another communication apparatus

the transmitter is configured to send a response to the request transmitted from the said another communication apparatus, the response including an identification (ID) determined by a random number generated in the communication apparatus to identify the communication apparatus.