Patent Publication Number: US-2010112940-A1

Title: Apparatus and method for improving data transmission speed of terminal transmitting data using near field communication scheme

Description:
PRIORITY 
     This application claims the benefit under 35 U.S.C. §119(a) of a Korean patent application filed in the Korean Intellectual Property Office on November 5, 2008 and assigned Serial No. 10-2008-0109403, the entire disclosure of which is hereby incorporated by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an apparatus and a method for transmitting data using a Near Field Communication (NFC) scheme. More particularly, the present invention relates to an apparatus and a method for improving data transmission speed of a terminal transmitting data using an NFC scheme. 
     2. Description of the Related Art 
     As communication apparatuses and equipment develop, mobile communication terminals have become an essential element to everyday life. As a result, communication terminal services requiring high bandwidth, such as Electronic (E)-mail, Digital Multimedia Broadcasting (DMB), Digital Audio Broadcasting (DAB) and Digital Video Broadcasting-Handheld (DVB-H), have increased. Also, as personal mobile communication terminals such as cellular phones and Personal Digital Assistants (PDAs) are used, a short distance communication scheme is necessary which does not need a base station. 
     Near Field Communication (NFC) is a type of Radio Frequency IDentification (RFID) which is a short distance communication scheme that does not need a base station. The NFC is a non-contact wireless communication technique which may transmit data using a simple process and low power within a maximum distance of 20 cm via a frequency of 13.56 MHz. According to the NFC, when two or more terminals are put close to each other, even without artificial manipulation of a user, basic information, such as a phone number, and data, such as an MP3 file and images, may be transmitted and received between the terminals. The NFC supports transmission speeds of 106 kbps, 212 kbps and 424 kbps, and is currently applied to a personal mobile communication apparatus, such as a cellular phone. However, since the NFC uses a fixed modulation scheme (for example, Amplitude Shift Keying (ASK) and Phase Shift Keying (PSK)), transmission speed is low. 
     According to a long distance communication scheme which uses a general cellular phone network, such as Global System for Mobile communications (GSM), General Packet Radio Service (GPRS) and Code Division Multiple Access (CDMA), data transmission speed and a Bit Error Rate (BER) vary depending on time and space due to a path loss by multipath fading. Therefore, a base station determines the BER and control power, and transmits data using a fixed modulation method. In a case of using a cellular phone network, such as High-Speed Downlink Packet Access (HSDPA), a base station transmits data using an AMC scheme. That is, the base station determines a target BER and power, and transmits data using a modulation scheme suitable for the power. 
     As described above, in a data transmission scheme which uses a conventional cellular phone network, a base station exists and a complicated process may be applied to the conventional cellular phone network. Accordingly, a transmission speed may be increased to meet circumstances of the complicated process. However, in an NFC scheme which uses a Point-to-Point scheme without a base station, a complicated process is difficult to apply. Therefore, the NFC has a limit in transmission speed due to a simple communication process and low power. 
     Therefore, a need exists for an apparatus and method for improving data transmission speed of a communication terminal. 
     SUMMARY OF THE INVENTION 
     An aspect of the present invention is to address at least the above-mentioned problems and/or disadvantages and to provide at least the advantages described below. Accordingly, an aspect of the present invention is to provide an apparatus and a method for improving data transmission speed of a terminal which transmits data using a Near Field Communication (NFC) scheme. 
     Another aspect of the present invention is to provide an apparatus and a method for improving data transmission speed of a terminal which transmits data using an NFC scheme by generating an approximate power table representing a power threshold for each modulation scheme using an approximate Bit Error Rate (BER) equation, and applying Adaptive Modulation &amp; Code (AMC) to the NFC scheme using the approximate power table. 
     In accordance with an aspect of the present invention, a data transmission method using a NFC scheme in a mobile communication terminal is provided. The method includes measuring NFC power, detecting a modulation scheme corresponding to the measured NFC power in an approximate power table, modulating data using the detected modulation scheme, and transmitting the modulated data using the NFC scheme. 
     In accordance with another aspect of the present invention, a data transmission apparatus using an NFC scheme in a mobile communication terminal is provided. The apparatus includes an NFC power measuring unit for measuring NFC power, a storage unit for storing an approximate power table, a modulation scheme detector for detecting a modulation scheme corresponding to the measured NFC power from the approximate power table, and an NFC communication unit for modulating data using the detected modulation scheme and for transmitting the modulated data using the NFC scheme. 
     In accordance with another aspect of the present invention, a data transmission apparatus using an NFC scheme in a mobile communication terminal is provided. The apparatus includes an NFC power measuring unit for measuring NFC power, a modulation scheme detector for extracting an approximate power table from a storage unit and detecting a modulation scheme corresponding to the measured NFC power from the approximate power table, and an NFC communication unit for modulating data using the detected modulation scheme, and for transmitting the modulated data using the NFC scheme. 
     Other aspects, advantages, and salient features of the invention will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses exemplary embodiments of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other aspects, features and advantages of certain exemplary embodiments of the present invention will be more apparent from the following description taken in conjunction with the accompanying drawings, in which: 
         FIG. 1  is a block diagram illustrating an apparatus of a terminal for transmitting data using a Near Filed Communication (NFC) scheme according to an exemplary embodiment of the present invention; 
         FIG. 2  is a flowchart illustrating a method for allowing a terminal to transmit data using an NFC scheme according to an exemplary embodiment of the present invention; and 
         FIG. 3  is a graph comparing a conventional Adaptive Modulation &amp; Coding (AMC) applying method with an AMC applying method using an approximate power table according to an exemplary embodiment of the present invention. 
     
    
    
     Throughout the drawings, like reference numerals will be understood to refer to like parts, components and structures. 
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     The following description with reference to the accompanying drawings is provided to assist in a comprehensive understanding of exemplary embodiments of the present invention as defined by the claims and their equivalents. It includes various specific details to assist in that understanding but these are to be regarded as merely exemplary. Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the embodiments described herein can be made without departing from the scope and spirit of the invention. Also, descriptions of well-known functions and constructions are omitted for clarity and conciseness. 
     The terms and words used in the following description and claims are not limited to the bibliographical meanings, but, are merely used by the inventor to enable a clear and consistent understanding of the invention. Accordingly, it should be apparent to those skilled in the art that the following description of exemplary embodiments of the present invention are provided for illustration purpose only and not for the purpose of limiting the invention as defined by the appended claims and their equivalents. 
     It is to be understood that the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “a component surface” includes reference to one or more of such surfaces. 
     By the term “substantially” it is meant that the recited characteristic, parameter, or value need not be achieved exactly, but that deviations or variations, including for example, tolerances, measurement error, measurement accuracy limitations and other factors known to those of skill in the art, may occur in amounts that do not preclude the effect the characteristic was intended to provide. 
     Exemplary embodiments of the present invention provide an apparatus and a method for improving data transmission speed of a terminal which transmits data using a Near Field Communication (NFC) scheme by generating an approximate power table representing a power threshold for each modulation scheme using an approximate Bit Error Rate (BER) equation, and applying Adaptive Modulation &amp; Coding (AMC) to the NFC scheme using the approximate power table. 
     In a case of the NFC, since communication is performed using Line Of Sight (LOS) in a short distance range within a maximum of 20 cm, multipath fading does not exist. Therefore, a BER determination and complicated power control are not used in real-time during data communication. Instead, an approximate power table representing a power threshold for each modulation scheme using an approximate BER equation may be generated, and then AMC may be applied to the NFC scheme using the approximate power table. 
     Assuming that the number of bits which may be transmitted per symbol in an NFC system is n, a power threshold which may transmit n bits per symbol for T times may be determined using Equation (1) below. 
     
       
         
           
             
               
                 
                   
                     γ 
                     T 
                     n 
                   
                   = 
                   
                     B 
                      
                     
                         
                     
                      
                     E 
                      
                     
                         
                     
                      
                     
                       
                         R 
                         n 
                         
                           - 
                           1 
                         
                       
                        
                       
                         ( 
                         0.001 
                         ) 
                       
                     
                   
                 
               
               
                 
                   ( 
                   1 
                   ) 
                 
               
             
           
         
       
     
     In an exemplary implementation, when Equation (1) is arranged in terms of BER of n-ary Quadrature Amplitude Modulation (QAM), assuming that a minimum BER (target BER), i.e., BER 0 , which may perform communication, is a constant, Equation (1) may be expressed as an approximate BER equation shown in Equation (2). 
     
       
         
           
             
               
                 
                   
                     γ 
                     T 
                     n 
                   
                   = 
                   
                     
                       - 
                       
                         2 
                         3 
                       
                     
                      
                     
                       ln 
                        
                       
                         ( 
                         
                           5 
                            
                           
                               
                           
                            
                           B 
                            
                           
                               
                           
                            
                           E 
                            
                           
                               
                           
                            
                           
                             R 
                             0 
                           
                         
                         ) 
                       
                     
                      
                     
                       ( 
                       
                         
                           2 
                           n 
                         
                         - 
                         1 
                       
                       ) 
                     
                   
                 
               
               
                 
                   ( 
                   2 
                   ) 
                 
               
             
           
         
       
     
     In Equation (2), BER 0  is variably set depending on the type of data. Therefore, Equation (2) may generate an approximate power table representing a power threshold for each modulation scheme using the approximate BER equation shown in Equation (2). 
     For example, assuming that BER 0 =0.0001, the approximate power table may be generated as in Table 1 below. 
     
       
         
           
               
               
               
               
             
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                 n (Spectral Efficiency) 
                 γ T   n  [dB] 
                 Modulation 
               
               
                   
                   
               
             
            
               
                   
                 1 
                 5.4805 
                 BPSK 
               
               
                   
                 2 
                 10.2517 
                 QPSK 
               
               
                   
                 3 
                 13.9314 
                  8QAM 
               
               
                   
                 4 
                 17.2414 
                  16QAM 
               
               
                   
                 5 
                 20.3914 
                  32QAM 
               
               
                   
                 6 
                 23.4739 
                  64QAM 
               
               
                   
                 7 
                 26.5185 
                 128QAM 
               
               
                   
                 8 
                 29.5459 
                 256QAM 
               
               
                   
                   
               
            
           
         
       
     
     Therefore, during data transmission, AMC may be applied to the NFC scheme using the approximate power table without BER determination and power control. That is, a terminal which intends to transmit data using the NFC scheme measures NFC power and compares the measured NFC power with a power threshold of the approximate power table as in Equation (3). 
         r   T   n   ≦NFC Power &lt;r T   n+1    (3) 
     Here, in the case where a maximum value is set to n in the approximate power table, since n+1 does not exist, r T   n ≦NFCPower needs to be met rather than Equation (3). Subsequently, r T   n  meeting Equation (3) is searched and a modulation scheme corresponding to the r T   n  searched from the approximate power table is detected. Data is then modulated and transmitted using the detected modulation scheme. 
     For example, in a case of using the approximate power table shown in Table 1, a modulation scheme of data is detected as described below and data may be modulated and transmitted.
         5.4805≦NFC power&lt;10.2517   modulate using Binary Phase-Shift Keying (BPSK)   10.2517≦NFC power&lt;13.9314   modulate using Quadrature Phase-Shift Keying (QPSK)   13.9314≦NFC power&lt;17.2414   modulate using 8 QAM   17.2414≦NFC power&lt;20.3914   modulate using 16 QAM   20.3914≦NFC power&lt;23.4739   modulate using 32 QAM   23.4739≦NFC power&lt;26.5185   modulate using 64 QAM   26.5185≦NFC power&lt;29.5459   modulate using 128 QAM   29.5459≦NFC power   modulate using 256 QAM       

       FIG. 1  is a block diagram illustrating an apparatus of a terminal for transmitting data using an NFC scheme according to an exemplary embodiment of the present invention. 
     As illustrated in  FIG. 1 , the terminal includes a controller  100 , an NFC power measuring unit  102 , a modulation scheme detector  104 , an NFC communication unit  106 , an input unit  108 , a display unit  110  and a storage unit  112 . 
     Referring to  FIG. 1 , the controller  100  performs a control and process for an overall operation of the terminal. More particularly, the controller  100  performs a control and process for improving data transmission speed of the terminal which transmits data using an NFC scheme by applying AMC to the NFC scheme using an approximate power table  114 . 
     The NFC power measuring unit  102  measures NFC power according to a user&#39;s selection of a data transmission menu which uses the NFC scheme. 
     The modulation scheme detector  104  extracts the approximate power table  114  from the storage unit  112  according to the user&#39;s selection of the data transmission menu which uses the NFC scheme. The modulation scheme detector  104  then detects a modulation scheme corresponding to the NFC power measured by the NFC power measuring unit  102  from the extracted approximate power table  114 . That is, the modulation scheme detector  104  compares a power threshold for each modulation scheme with the measured NFC power using the extracted approximate power table  114 , thereby determining whether the measured NFC power meets Equation (3). When the measured NFC power meets Equation (3), the modulation scheme detector  104  detects a modulation scheme which meets Equation (3) and corresponds to r T   n  from the approximate power table  114 . 
     The NFC communication unit  106  transmits/receives data to/from a different terminal located in an area where data transmission using the NFC scheme is possible. More particularly, the NFC communication unit  106  modulates data using the modulation scheme detected by the modulation scheme detector  104 , and transmits the modulated data using the NFC scheme. 
     The input unit  108  includes a plurality of function keys, and provides data corresponding to a key pressed by the user to the controller  100 . The display unit  110  displays state information, numbers and letters generated during an operation of the terminal. 
     The storage unit  112  stores programs used for an overall operation of the terminal and various information. More particularly, the storage unit  112  stores the approximate power table  114 . Here, the approximate power table  114  is a table regarding a power threshold for each modulation scheme. The power threshold for each modulation scheme may be determined using the approximate BER equation shown in Equation (2). 
       FIG. 2  is a flowchart illustrating a method for allowing a terminal to transmit data using an NFC scheme according to an exemplary embodiment of the present invention. 
     Referring to  FIG. 2 , in step  201 , the terminal determines whether a data transmission menu which uses the NFC scheme is selected by a user&#39;s key manipulation. When the selection of the data transmission menu which uses the NFC scheme is detected, the terminal measures NFC power in step  203 , and performs initialization by setting n=1 in step  205 . Here, n denotes the number of bits which may be transmitted per symbol. 
     In step  207 , the terminal determines whether the measured NFC power meets Equation (3) by comparing a power threshold for each modulation scheme with the measured NFC power using an approximate power table. When the measured NFC power does not meet Equation (3), the terminal replaces n by n+1 in step  215 , and returns to step  207  to repeatedly perform subsequent steps. 
     On the other hand, when the measured NFC meets Equation (3), the terminal detects a modulation scheme corresponding to r T   n  meeting Equation (3) from the approximate power table in step  209 . 
     In step  211 , the terminal modulates data using the detected modulation scheme, and in step  213 , the terminal transmits the modulated data. 
     The terminal then ends the process. 
       FIG. 3  is a graph comparing a conventional AMC applying method with an AMC applying method using an approximate power table according to an exemplary embodiment of the present invention. 
     Referring to  FIG. 3 , according to the conventional AMC applying method which uses a real BER, when 10000 bit-data per power of 0.5 dB is transmitted using 1024 QAM, a BER of 0.01% is generated. It is revealed that an AMC applying method which uses the approximate BER according to an exemplary embodiment of the present invention may generate a BER substantially similar to that of the conventional AMC applying method. 
     As described above, exemplary embodiments of the present invention may improve data transmission speed by generating an approximate power table representing a power threshold for each modulation scheme using an approximate BER equation, and applying AMC to the NFC scheme using the approximate power table, thereby applying the AMC using a simple process. 
     While the invention has been shown and described with reference to certain exemplary embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims and their equivalents.