Abstract:
A wireless communication method utilizing a wireless communication apparatus is provided. The method includes: providing an antenna unit being used by both a first wireless communication circuit and a second wireless communication circuit, using the first wireless communication circuit for RFID communication via the antenna unit in a first mode, and utilizing the second wireless communication circuit for RFID communication via the antenna unit in a second mode.

Description:
CROSS REFERENCE TO RELATED PATENT APPLICATION 
     This patent application is based on a Taiwan, R.O.C. patent application No. 097106605 filed on Feb. 26, 2008. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a radio-frequency identification (RFID) communication scheme, and more particularly to a near field communication (NFC) apparatus using the RFID technology, and a method thereof. 
     2. Description of the Prior Art 
     The latest mobile phones with a near field communication (NFC) function have built-in radio-frequency identification (RFID) circuits. The RFID circuit includes the capabilities of peer-to-peer communication with an external RFID circuit, reading data of an external RFID tag, and simulating as an RFID tag. A user can therefore replace an original RFID card (such as a travel card) with his/her mobile phone when utilizing an underground travel system, such as the Taipei&#39;s Mass Rapid Transit (MRT) system. A denouncing problem can arise, however. For instance, when the user enters a station A of the MRT system, the user uses the RFID circuit within the mobile phone to communicate with an RFID reader of a gate in the station A for recording the station the user enters. When leaving the MRT system at another station B, the user uses the RFID circuit to communicate with an RFID reader of a gate in the station B, and then the RFID reader of the station B reads the recorded information from the RFID circuit for determining the traveling expenses the user should pay. If the battery of the mobile phone is exhausted while the user is still inside the MRT system, the user cannot use the RFID circuit built within the mobile phone to communicate with the RFID reader at an exit gate; this is because the RFID reader is designed as being powered by the battery of the mobile phone. In this situation, the user cannot pay the traveling expenses for the MRT system using the mobile phone. It is not convenient for the user. Additionally, when the user changes his/her mobile phone, the user is faced with the risk of losing any remaining money recorded by the old mobile phone since the amount may not be transferred to the user&#39;s new mobile phone. Regularly, the amount of money is recorded on another circuit within the mobile phone. Thus, unless a conversion scheme between different mobile phone manufacturers or different service providers can be designed beforehand, the money cannot be directly transferred to and recorded in a circuit built within the new mobile phone when the user changes his/her mobile phone. 
     Regarding a well-known conversion scheme, the RFID circuit is arranged to transmit data associated with the amount of remaining money to the host circuit of the old mobile phone, and the host circuit is arranged to record the data into the SIM card. Thus, after changing mobile phones, if the SIM card is still used by the user, the user can continue to use the remaining money as payment. Moreover, in the situation where the battery of the mobile phone is exhausted while the user is inside the MRT system, a recently provided solution proposes that the SIM card includes a dual interface. That is, the SIM card has the communication functions of both a SIM card and RFID. The SIM card is connected to an antenna of another NFC circuit and installed within the mobile phone before it is used. Therefore, the user can still use the mobile phone to replace the conventional RFID card to pay traveling expenses when the user travels by the MRT system. When the user exits the MRT system, an RFID reader installed at the gate communicates with the above-mentioned SIM card for the purpose of collecting traveling expenses. The SIM card having the dual interface, however, only provides the function of making payments, but does not include the functions regarding pier-to-pier data transmission and reading data of an RFID tag. It is hoped that a single handheld product such as a mobile phone can integrate diversified applications, where the above-mentioned RFID circuit built in the mobile phone will be required. If the RFID circuit, the SIM card having the dual interface, and the related antenna connected to the SIM card are all installed within the mobile phone to achieve the objective of the mobile phone being integrated with diversified applications, then, in practice, the mobile phone should include two antennas operating at the same frequency. This substantially increases the manufacturing costs, the size of the circuit area of the mobile phone, and the layout difficulty. 
     SUMMARY OF THE INVENTION 
     Therefore, an objective of the present invention is to provide an NFC apparatus capable of performing different radio-frequency identification (RFID) communication by sharing an antenna unit, and a related method, to achieve the goals of decreased production cost and circuitry size. 
     According to an embodiment of the present invention, a wireless communication apparatus is disclosed. The apparatus comprises an antenna unit, a switch module, and a first and a second NFC circuit. The switch module is coupled to the antenna unit, and the first NFC circuit is coupled to the antenna unit and performs RFID communication operation via the antenna unit. The second NFC circuit is coupled to the switch module, and controls the state of the switch module to perform RFID communication operations via the antenna unit. The first and second NFC circuits share the antenna unit. 
     According to an embodiment of the present invention, a wireless communication method is further disclosed. The method comprises the steps of: providing an antenna unit being shared by a first and a second NFC circuit, utilizing the first NFC circuit to perform RFID communication operations through the antenna unit under a first mode, and utilizing the second NFC circuit to perform RFID communication operations through the antenna unit under a second mode. 
     According to an embodiment of the present invention, a wireless communication apparatus is further disclosed. The wireless communication apparatus comprises an antenna unit, a first wireless communication circuit, and a second wireless communication circuit. The first wireless communication circuit is coupled to the antenna unit and performs RFID communication operations through the antenna unit, and the second wireless communication circuit is coupled to the antenna unit and performs RFID communication operations through the antenna unit; wherein the first and second wireless communication circuits share the antenna unit. 
     These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a diagram of a near field communication (NFC) apparatus according to a first embodiment of the present invention. 
         FIG. 2  is a diagram of an NFC apparatus according to a second embodiment of the present invention. 
         FIG. 3  is an operating diagram showing the operation of an NFC circuit within an NFC apparatus according to a third embodiment of the present invention. 
         FIG. 4  is an operating diagram showing the operation of another NFC circuit within the NFC apparatus shown in  FIG. 3 . 
     
    
    
     DETAILED DESCRIPTION 
     Please refer to  FIG. 1 .  FIG. 1  is a diagram of a near field communication (NFC) apparatus  100  according to a first embodiment of the present invention. The NFC apparatus  100 , such as a mobile phone having radio-frequency identification (RFID) communication functionality, comprises a host circuit  105 , an antenna unit  110 , a switch module  115  including a switching element SW therein, two NFC circuits  120  and  125 , two impedance matching circuits  130   a  and  130   b , and a voltage regulating and filtering circuit  135 . The antenna unit  110  is represented by two inductors, but can be represented by only one inductor in another example. Additionally, the voltage regulating and filtering circuit  135  is an optional element; this is not a limitation to the present invention. Regarding the circuitry configuration, the first transmission terminal TXA′ of the NFC circuit  120  is coupled to the first end of the antenna unit  110 , and the first transmission terminal TXA of the NFC circuit  125  is coupled to the second end of the antenna unit  110  and the first end of the switching element SW. The second transmission terminal TXB of the NFC circuit  125  is coupled to the second end of the switching element SW, and further connected to the second transmission terminal TXB′ of the NFC circuit  120  through the antenna unit  110 . 
     In this embodiment, the NFC circuit  125  is built in the NFC apparatus  100  and includes the functionalities of pier-to-pier data communication with an external RFID circuit, reading information from an external RFID tag, and simulating as an RFID tag. The NFC circuit  125  is an active RFID circuit, which means that the NFC circuit  125  is powered by the battery of the NFC apparatus  100 . The NFC circuit  125  outputs a differential transmitting signal from the transmission terminals TXA and TXB to an external receiving circuit via the antenna unit  110 , and receives a signal coming from the antenna unit  110  at the receiving terminal RX. The NFC circuit  120  can be implemented by a semi-active/passive RFID circuit. In this embodiment, the NFC circuit  120  is a passive RFID circuit set up on a user&#39;s subscriber identity module (SIM) card, so it is convenient for the user to take out the NFC circuit  120  from the NFC apparatus  100  if necessary. The SIM card includes a pad connected to the functionality of SIM card and a wireless interface capable of performing wireless communication. The NFC circuit  120  is used as an RFID tag for payment or identification of the user, and can provide requested data to the external RFID reader based on the signal(s) sent from the external RFID reader, without consuming the battery of the mobile phone, i.e., the NFC apparatus  100 . The above-mentioned NFC circuits  120  and  125  both use the antenna unit  110  to perform respective RFID communications. 
     Since the NFC circuits  120  and  125  both use the antenna unit  110 , it is important that the impedance should be matched. Therefore, the host circuit  105  of this embodiment timely informs the NFC circuit  125  to switch the state of the switching element SW so that the NFC apparatus  100  has better impedance matching characteristics when the NFC circuits  120  and  125  respectively use the antenna unit  110  for transmission. Under the first mode, the NFC circuit  125  controls the switching element SW to be in a closed state, wherein the default state of the switching element SW is also set as the closed state in this embodiment. Once the NFC circuit  120  receives a signal coming from an external RFID reader, the NFC circuit  120  communicates with the external RFID reader via the antenna unit  110  for performing identification of an RFID tag by the backscatter modulation technology. In addition, when the pier-to-pier data transmission or other data communication is desired, the NFC apparatus  100  is arranged to switch to the second mode from the first mode. Under the second mode, the NFC circuit  125  controls the switching element SW to be in an open state, and a circuit loop, including the NFC circuits  120  and  125 , the impedance matching circuit  130   a , and the antenna unit  110 , is formed. The NFC circuit  125  then communicates with an external RFID reader or an external RFID tag through the impedance matching circuit  130   a , the NFC circuit  120 , and the antenna unit  110 ; at the same time, the NFC circuit  120  can still operate for RFID communication. It should be noted that the NFC circuit  125  may also receive data of the NFC circuit  120  (i.e. an RFID tag) when communicating with an external RFID tag since the NFC circuit  120  is located near the NFC circuit  125 . In this situation, the NFC circuit  125  can be designed as not to read the data of the NFC circuit  120 , to avoid incurring any error. The NFC circuit  125  switches the state of the switching element SW to the closed state after the communication or data transfer is finished. In practice, the NFC circuit  125  can be designed to immediately switch the state of the switching element SW to the closed state when the NFC circuit  125  is running out of power. An advantage of this design is that a circuit loop, including the NFC circuit  120 , the switching element SW and the antenna unit  110 , can still be established to maintain the operation of the NFC circuit  120  even though the NFC circuit  125  cannot operate due to the lack of power. In other words, when the NFC circuit  125  is lacking power, the external RFID reader can still access the data of the NFC circuit  120 . Accordingly, it becomes more convenient for a user to use the NFC apparatus  100 ; for example, if the user travels to another location using the Metropolitan/Mass Rapid Transit (MRT) system and wishes to use the NFC apparatus  100  to pay traveling expenses, the NFC circuit  120  can be used for communicating with an RFID reader of the MRT system to make his/her payment regardless of whether the NFC apparatus  100  lacks power. Thus, the user can pass through the gate of the MRT system successfully. Additionally, because the NFC circuits  120  and  125  share the antenna unit  110 , the manufacturing costs of the NFC apparatus will not increase and the size of the circuit area of the NFC apparatus  100  can be minimized. Moreover, since it is convenient for the user to take the NFC circuit  120  out of the NFC apparatus  100  to put into another mobile phone, the problem that an amount of remaining money recorded in the original mobile phone cannot be transferred to another apparatus is resolved. 
     Please refer to  FIG. 2 .  FIG. 2  is a diagram of an NFC apparatus  200  according to the second embodiment of the present invention. The difference between the NFC apparatuses  100  and  200  is that the NFC apparatus  100  utilizes a Normal Close switching element for implementation while the NFC apparatus  200  utilizes a Normal Open switching element for implementation. With regards to the circuitry, a switch module  215  is composed of switching elements SW 1  and SW 2 . The first transmission terminal TXA′ of the NFC circuit  220  is coupled to one end of the antenna unit  210  and one end of the switching element SW 1 , the second transmission terminal TXB′ of the NFC circuit  220  is coupled to the other end of the antenna unit  210  and one end of the switching element SW 2 , the first transmission terminal of TXA of the NFC circuit  225  is coupled to the other end of the switching element SW 1 , and the second transmission terminal TXB of the NFC circuit  225  is coupled to the other end of the switching element SW 2 . Impedance matching circuits  230   a ,  230   b , and a resistor R, are all used to carry out impedance matching for the antenna unit  110  with other circuits; the function of a voltage regulating and filtering circuit  235  is identical to that of the voltage regulating and filtering circuit  135 . Under the first mode, the NFC circuit  225  controls the switching elements SW 1  and SW 2  to be in the open state; in this embodiment, the default state of the switching elements SW 1  and SW 2  are set as the open. The NFC circuit  220  under the first mode is arranged to communicate with an external RFID reader (e.g., an RFID reader of the MRT system) via the antenna unit  210  for performing identification of an RFID tag. In other words, the NFC circuit  220  can be used as an RFID tag for a payment scheme, and the RFID tag can be set up on a SIM card including a pad connected to the functionality of the SIM card and a wireless interface capable of performing wireless communication. Under the second mode, the NFC circuit  225  controls the switching elements SW 1  and SW 2  to be in the closed state, and the NFC circuit  225  can connect to the antenna unit  210  via the switching elements SW 1  and SW 2  so as to communicate with an external RFID reader or an external RFID tag. The advantage of the NFC apparatus  200  is similar to that of the NFC apparatus  100  of the first embodiment, and therefore is not further detailed here. 
     Please refer to  FIG. 3  in conjunction with  FIG. 4 .  FIG. 3  and  FIG. 4  respectively show the illustrative operating diagrams of NFC circuits  320  and  325  within an NFC apparatus  300  according to a third embodiment of the present invention. Compared to the NFC apparatuses  100  and  200 , the NFC apparatus  300  does not use any switching element for circuit design. Instead the NFC apparatus  300  performs data communication with an external RFID reader or an external RFID tag by impedance matching circuits  330 ,  331 , and  332 , to achieve an objective of minimizing production costs. The first transmission terminal TXA′ of the NFC circuit  320  is coupled to the impedance matching circuit  330 , which is coupled to one end of the antenna unit  310 . The second transmission terminal TXB′ of the NFC circuit  320  is coupled to the impedance matching circuit  331 , which is coupled to the other end of the antenna unit  310 . In addition, the transmission terminals TXA and TXB of the NFC circuit  325  are respectively coupled to the impedance matching circuits  330  and  331 . As shown in  FIG. 3 , under the first mode, the NFC circuit  320  communicates with an external RFID reader such as an RFID reader of the MRT system through the antenna unit  310  for achieving RFID tag identification. In other words, the NFC circuit  320  works as an RFID tag for a payment scheme or an identification scheme; moreover, the RFID tag can be set up on a SIM card, which includes a pad connected to the SIM card functionality and a wireless interface having the wireless communication operation. As shown in  FIG. 4 , under the second mode the NFC circuit  325  is arranged to communicate with an external RFID circuit or an external RFID tag through the impedance matching circuits  330  and  331 , and the antenna unit  310 . Please note that, even though the impedance matching circuits  330  and  331  of this embodiment are designed to be the same circuit, in another embodiment, the circuit design of the impedance matching circuit  330  can be different from that of the impedance matching circuit  331 . This is not intended to be a limitation to the present invention. In addition, a designer can appropriately adjust the impedance matching circuits  330  and  331  to control the operation of the NFC circuit  325  for determining whether the NFC circuit  325  can receive/read signals sent from by the NFC circuit  320 . The advantage of the NFC apparatus  300  is identical to that of the NFC apparatus  100  of the first embodiment, and therefore is not further detailed here for simplicity of the specification. 
     Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention.