Patent Publication Number: US-2011053507-A1

Title: Apparatus and method for improving bluetooth communication performance in mobile terminal

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 Sep. 2, 2009 and assigned Serial No. 10-2009-0082473, 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 connecting via Bluetooth communication in a mobile terminal. More particularly, the present invention relates to an apparatus and a method for maintaining a communication connection by increasing a transmission bandwidth of voice data and changing a compression rate depending on a Bluetooth communication state, to transmit voice data with improved Bluetooth communication performance. 
     2. Description of the Related Art 
     The now ubiquitous mobile terminal has become indispensable to modern people, and service providers and terminal manufacturers competitively develop products (or services) for differentiation from one another. 
     For example, the mobile terminal has evolved into a multimedia apparatus that can provide one or more of a phonebook, games, a Short Message Service (SMS), Electronic (E)-mail, a Motion Picture Expert Group Audio Layer-3 (MP3) player, a digital camera, a wireless Internet service, various services, and the like. 
     Furthermore, the mobile terminal may enable a short range communication between terminals that are closely located to one another. 
     As an example of the above short range communication, the mobile terminal may provide various services such as a headset, music, printing, file transmission, and the like using a Bluetooth function. 
     The Bluetooth function is a communication technique for use by terminals located a short distance apart that include Bluetooth apparatuses for wirelessly communicating within a narrow range at low cost. In other words, the mobile terminal transmits/receives voice and data without a physical cable during communication between Bluetooth apparatuses located a short distance apart using a Radio Frequency (RF). 
     In the Bluetooth function, voice information is transmitted via a Synchronous Connection-Oriented (SCO) link, and data information is transmitted via an Asynchronous Connection-Less (ACL) link. 
     Only one SCO link may exist and a transmitted SCO packet is not retransmitted. Accordingly, a real-time characteristic is achieved but sound quality deterioration may occur. 
     Additionally, the SCO link limits a transmission bandwidth of voice data to 64 kbps. Accordingly, sound quality of voice data cannot be improved. 
     Furthermore, the mobile terminal only supports one headset. Thus, use of two or more headsets is not possible. 
     Therefore, an apparatus and a method for improving Bluetooth performance by addressing the above shortcomings are desired. 
     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 increasing a transmission bandwidth of voice data when performing Bluetooth communication in a mobile terminal. 
     Another aspect of the present invention is to provide an apparatus and a method for connecting to a plurality of Bluetooth apparatuses to transmit voice data when performing Bluetooth communication in a mobile terminal. 
     Still another aspect of the present invention is to provide an apparatus and a method for maintaining a communication connection by changing a data compression rate depending on a Bluetooth communication state when performing Bluetooth communication in a mobile terminal. 
     In accordance with an aspect of the present invention, an apparatus for improving Bluetooth communication performance in a mobile terminal is provided. The apparatus includes a device connector for transmitting voice data through an Asynchronous Connection-Less (ACL) link during data transmission when transmitting voice data via a Bluetooth apparatus. 
     In accordance with another aspect of the present invention, an apparatus for improving Bluetooth communication performance in a mobile terminal is provided. The apparatus includes a device connector for transmitting voice data to a plurality of Bluetooth apparatuses through an ACL link during data transmission when transmitting voice data via a Bluetooth apparatus, wherein the device connector comprises a data compressor for maintaining a communication connection after the ACL link is established by establishing the ACL link and then changing a compression rate of the voice data depending on a Bluetooth communication state. 
     In accordance with yet another aspect of the present invention, a method for improving Bluetooth communication performance in a mobile terminal is provided. The method includes transmitting voice data through an ACL link during data transmission when transmitting voice data via a Bluetooth apparatus. 
     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 a mobile terminal for improving Bluetooth communication performance according to an exemplary embodiment of the present invention; and 
         FIG. 2  is a flowchart illustrating a process for transmitting data through Bluetooth communication in a mobile terminal 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 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 maintaining a communication connection by increasing a transmission bandwidth of voice data and changing a data compression rate depending on a Bluetooth communication state in order to improve Bluetooth communication performance. The above mobile terminal increases a transmission bandwidth of voice data and connects to a plurality of Bluetooth apparatuses to enable transmission of voice data. 
       FIG. 1  is a block diagram illustrating a mobile terminal for improving Bluetooth communication performance according to an exemplary embodiment of the present invention. 
     Referring to  FIG. 1 , the mobile terminal includes a controller  100 , a device connector  102 , a memory unit  106 , an input unit  108 , a display unit  110 , and a communication unit  112 . The device connector  102  may include a data compressor  104 . The portable terminal may include additional units. Similarly, the functionality of two or more of the above units may be integrated into a single component. 
     The controller  100  of the mobile terminal controls overall operations of the mobile terminal. For example, the controller  100  controls a process for voice communication and data communication. In addition to the overall operations, according to an exemplary embodiment of the present invention, the controller  100  increases a transmission bandwidth of voice data, and changes a compression rate depending on a Bluetooth communication state to transmit voice data with improved Bluetooth communication performance, thereby maintaining a communication connection. 
     Additionally, according to an exemplary embodiment of the present invention, the controller  100  may connect to a plurality of Bluetooth apparatuses to transmit voice data by increasing a transmission bandwidth of the voice data. 
     The controller  100  is described in more detail below. 
     First, to increase the transmission bandwidth of the voice data, in the case of transmitting the voice data to a counterpart mobile terminal through Bluetooth communication, the controller  100  establishes a Bluetooth connection through an Asynchronous Connection-Less (ACL) link which has been used by the conventional mobile terminal to transmit data, but not voice, in order to enable a point-to-multipoint access. That is, the controller  100  connects to a plurality of Bluetooth apparatuses via the ACL link that supports multiple channels to process the same data and different data of various types. 
     Additionally, the controller  100  of the mobile terminal, monitors the Bluetooth communication state and changes a compression rate, depending on the Bluetooth communication state, of thee voice data transmitted via the Bluetooth connection. If it is determined that the Bluetooth communication state is sufficient, the controller  100  compresses data without changing a compression rate. In contrast, if it is determined that the Bluetooth communication state is poor, the controller  100  changes the compression rate to reduce a transmission rate, in order to maintaining the communication connection. 
     To improve Bluetooth communication performance, the device connector  102  increases a transmission bandwidth of the voice data using voice data transmission via an ACL link, and changes a compression rate depending on a Bluetooth communication state to transmit voice data under control of the controller  100 , thereby maintaining a communication connection. 
     The data compressor  104  of the device connector  102  changes the compression rate depending on the Bluetooth communication state to maintain a communication connection under the control of the device connector  102 . 
     The memory unit  106  includes, for example, a Read Only Memory (ROM), a Random Access Memory (RAM), a flash ROM, and the like. The ROM may store microcode (i.e., code) of programs for processes and control of the controller  100  and the device connector  102 , and various reference data. 
     The RAM serves as a working memory of the controller  100  and stores temporary data that occurs during execution of various programs. The flash ROM stores various updatable data for storage such as a phonebook, calling messages, received messages, and information of a user&#39;s touch input point. 
     The input unit  108  includes a plurality of function keys such as numerical key buttons of 0 to 9, a menu button, a cancel button, an OK button, a TALK button, an END button, an Internet access button, navigation key (or direction key) buttons, letter input keys, and the like. The input unit  110  provides key input data corresponding to a key pressed by a user to the controller  100 . These keys are merely examples of keys which may make up the input unit  110 . That is, the input unit may include additional or different keys, or different input mechanisms through which the user supplies input to the portable terminal 
     The display unit  110  displays status information generated during an operation of the mobile terminal, a limited number of letters, a large amount of moving images, still images, and the like. The display unit  110  may be a color Liquid Crystal Display (LCD), an Active Mode Organic Light Emitting Diode (AMOLED), and the like. The display unit  110  may include a touch input device, and when it is applied to a touch input type mobile terminal, it can be used as an input unit. 
     The communication unit  112  transmits/receives a Radio Frequency (RF) signal of data input/output via an antenna (not illustrated). For example, during transmission, the communication unit  112  channel-codes and spreads data to be transmitted, and then performs an RF process on the signal to transmit the signal. During reception, the communication unit  112  converts a received RF signal into a baseband signal, and despreads and channel-decodes the baseband signal to recover data. 
     The function of the device connector  102  may be performed by the controller  100  of the mobile terminal. Separate configuration and illustration of the device connector  102  is an example for convenience in description, and is not to be construed as limiting the scope of the present invention. It would be obvious to those skilled in the art that various modifications may be made within the scope of the present invention. For example, all functions of the device connector  102  may be processed by the controller  100 . 
     An exemplary apparatus for maintaining a communication connection by increasing a transmission bandwidth of voice data and changing a data compression rate depending on a Bluetooth communication state in order to improve Bluetooth communication connection performance has been described above. An exemplary method for maintaining a communication connection by increasing a transmission bandwidth of voice data and changing a data compression rate depending on a Bluetooth communication state using the above-described apparatus according to an exemplary embodiment of the present invention is described below. 
       FIG. 2  is a flowchart illustrating a process for transmitting data through Bluetooth communication in a mobile terminal according to an exemplary embodiment of the present invention. 
     Referring to  FIG. 2 , the mobile terminal transfers voice via Bluetooth communication. The mobile terminal does not transfer voice data through a Synchronous Connection-Oriented (SCO) link as in the conventional mobile terminal. Instead, the mobile terminal transfers voice data through an ACL link to increase a transmission bandwidth of voice data and enable a communication connection with a plurality of Bluetooth apparatuses. 
     To perform the above-described operation, the mobile terminal according to an exemplary embodiment of the present invention determines whether an event for transmitting voice data using a Bluetooth apparatus, such as a headset, occurs in step  201 . 
     If it is determined in step  201  that the event for transmitting voice data using the Bluetooth apparatus does not occur, the mobile terminal performs a relevant function (e.g., a standby mode) in step  219 . 
     In contrast, if it is determined in step  201  that the event for transmitting voice data using the Bluetooth apparatus occurs, the mobile terminal performs a Bluetooth connection process through an ACL link in step  203 . 
     At this point, according to an exemplary embodiment of the present invention, the mobile terminal determines a data transmission order using a Real-Time Transport Protocol (RTP) and a Real-Time Transport Control Protocol (RTCP), and compresses data to transmit the same, thereby performing voice data transmission through an ACL link that is performed during data transmission in the conventional mobile terminal to enable a point-to-multipoint access. That is, the mobile terminal addressed a data loss problem generated during voice data transmission that uses the ACL link supporting multiple channels through data transmission according to a data retransmission rate and a priority, and enables a connection with a plurality of Bluetooth apparatuses. 
     A mobile terminal for transmitting voice data through the ACL link compresses voice data in step  205 , and generates a packet to be transmitted in step  207 . Here, the mobile terminal may compress the voice data using a codec, such as G.723.1, depending on a user&#39;s voice quality. This raises transmission efficiency of a radio section to enable transmission of voice data via the ACL link. The compressed voice data is packetized by an RTP and prepared for transmission. 
     The mobile terminal that has compressed the voice data transmits the packet compressed and generated to raise transmission efficiency (in step  207 ) to a counterpart mobile terminal in step  209 , and determines whether a request for releasing a Bluetooth connection that performs communication with the counterpart mobile terminal via the ACL channel is received in step  211 . 
     When not receiving a request for releasing the Bluetooth connection with the counterpart mobile terminal in step  211 , the mobile terminal determines whether communication with the mobile terminal is possible by determining a Bluetooth communication state based on an intensity of a reception signal in step  213 . 
     The mobile terminal determines whether a compression rate change for a communication should be performed based on the Bluetooth communication state (performed in step  213 ) in step  215 . At this point, when the Bluetooth communication state is determined to be poor, the mobile terminal changes a compression rate of voice data to maintain communication with the counterpart mobile terminal When the Bluetooth communication state once again becomes acceptable, the mobile terminal recovers the original compression rate to perform communication. This changes the compression rate depending on the Bluetooth communication state to enable real-time voice data transmission via the ACL link. The mobile terminal changes the compression rate using an RTCP for controlling an RTP. 
     If it is determined in step  215  that the Bluetooth communication state is improved and that communication with the counterpart mobile terminal is not impaired, the mobile terminal re-performs the process of step  205  to perform the Bluetooth communication with the counterpart mobile terminal. 
     In contrast, if it is determined in step  215  that the Bluetooth communication state is poor and the communication with the counterpart mobile terminal is impaired, the mobile terminal changes a compression rate depending on the Bluetooth communication state in step  217 , and compresses voice data at the compression rate (changed in step  217 ) to generate a packet to be transmitted in step  205 . The above-described process is performed until the Bluetooth connection with the counterpart mobile terminal is released. 
     That is, the mobile terminal raises a compression rate to a predefined compression rate to lower an amount of data being transmitted so that communication is possible when a Bluetooth communication state is poor, and lowers the compression rate which increases the amount of data being transmitted when the Bluetooth communication state improves. Accordingly, when the mobile terminal determines that the Bluetooth connection with the mobile terminal is released in step  211 , the mobile terminal ends the present algorithm. 
     As described above, a mobile terminal according to an exemplary embodiment of the present invention may address a problem of the conventional mobile terminal that allows only one voice channel transmission by increasing a transmission bandwidth of voice data, and changing a data compression rate depending on a Bluetooth communication state to maintain a communication connection in order to improve performance of Bluetooth communication connection. 
     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.