Patent Publication Number: US-8125851-B2

Title: Apparatus and method for controlling acoustic radiation pattern output through array of speakers

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
     This application claims the benefit under 35 U.S.C. §119(a) of a Korean Patent Application No. 10-2008-129342, filed on Dec. 18, 2008, the disclosure of which is incorporated herein in its entirety by reference. 
     BACKGROUND 
     1. Field 
     The following description relates to a speaker array system, and more particularly, to an apparatus and method for controlling an acoustic radiation pattern output through an array of speakers. 
     2. Description of Related Art 
     An array of speakers, that is, a speaker array includes a plurality of speakers and is used to adjust a direction of sound to be reproduced or deliver sound to a specific region. According to the principle of sound transmission, that is, directivity, a plurality of sound source signals are superimposed to increase the signal intensity in a specific direction using phase differences between the sound source signals, so as to transmit the sound source signal in the specific direction. A plurality of speakers may be arranged in a specific array form, and sound source signals output through the respective speakers may be adjusted to implement such directivity. 
     To obtain an intended frequency beam pattern, a general speaker array system uses filter values, gain and delay values, and the like appropriate for the intended beam pattern calculated in advance. Thus, in this case, a beam pattern not recorded in advance may not be formed, and moreover, the recorded beam pattern may not be modified. 
     SUMMARY 
     According to one general aspect, there is provided an apparatus for controlling an acoustic radiation pattern output through an array of speakers, including a focusing filter to process an input signal to form an acoustic radiation pattern, a control pattern filter to store a plurality of filter values for forming a plurality of corresponding control patterns set in advance from the input signal, and process the input signal using a filter value corresponding to at least one control pattern selected according to a control pattern selection signal, and a controller to generate the control pattern selection signal for selecting the at least one of the control patterns in order to generate a compensation control pattern such that signals output through the array of speakers have an intended pattern, which is an intended acoustic radiation pattern, using a filter value of the focusing filter and a filter value for the intended pattern. 
     The apparatus may further include a user interface to receive a user input signal for setting the intended pattern. 
     To generate the compensation control pattern, the controller may generate the control pattern selection signal to select at least one of a control pattern to be added to a reference pattern formed by the focusing filter and a control pattern for removing the whole or a part of the reference pattern. 
     In response to the compensation control pattern not being included in the plurality of control patterns, the controller may generate the control pattern selection signal to select at least two of the control patterns to be combined into the compensation control pattern. 
     In response to the controller combining the at least two control patterns into the compensation control pattern, the controller may calculate form factors which are weight data about the respective control patterns used to combine the at least two control patterns. 
     The filter value of the reference pattern formed by the focusing filter may be orthogonal to a plurality of filter values corresponding to the plurality of control patterns, and the filter values corresponding to the control patterns may be orthogonal to each other. 
     The apparatus may further include a signal synthesizer to synthesize a first output signal that is the input signal processed and output by the focusing filter with a second output signal that is the input signal processed and output by the control pattern filter, and an output unit to output the synthesized signal. 
     The apparatus may further include a first output unit to output a first output signal that is the input signal processed and output by the focusing filter, and a second output unit to output a second output signal that is the input signal processed and output by the control pattern filter. 
     According to another aspect, there is provided an apparatus for controlling an acoustic radiation pattern output through an array of speakers, including a control pattern filter to store a plurality of filter values for forming a plurality of corresponding control patterns set in advance from an input signal, and process the input signal using a filter value corresponding to at least one control pattern selected according to a control pattern selection signal, and a controller to receive a filter value of a focusing filter processing the input signal to form an acoustic radiation pattern from another apparatus, and generate the control pattern selection signal to select the at least one of the control patterns in order to generate a compensation control pattern such that signals output through the array of speakers have an intended pattern using the filter value of the focusing filter and a filter value for the intended pattern. 
     According to still another aspect, there is provided a method of controlling an acoustic radiation pattern output through an array of speakers, the method including setting an intended pattern, which is an intended acoustic radiation pattern, generating a compensation control pattern such that signals output through the array of speakers have the intended pattern using a filter value of a focusing filter processing an input signal to form an acoustic radiation pattern and a filter value for the intended pattern, generating a control pattern selection signal to select at least one of a plurality of control patterns in order to generate the compensation control pattern, and processing the input signal using a filter value corresponding to the control pattern selected according to the control pattern selection signal. 
     Other features and aspects will be apparent from the following detailed description, the drawings, and the claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram illustrating an exemplary apparatus to control an acoustic radiation pattern output through a speaker array. 
         FIG. 2A  is a diagram illustrating a reference pattern formed by a conventional focusing filter, and  FIG. 2B  is a diagram illustrating examples of a control pattern and a form factor to form an intended pattern according to an exemplary embodiment. 
         FIG. 3  is a diagram illustrating examples of a control pattern. 
         FIGS. 4A to 4C  are diagrams illustrating exemplary structures for a speaker array device. 
         FIG. 5  is a block diagram illustrating an exemplary apparatus to control an acoustic radiation pattern whereby a signal processed by a focusing filter and a signal processed by a control pattern filter unit are synthesized and output. 
         FIGS. 6A and 6B  are diagrams further illustrating the details of the apparatus for controlling an acoustic radiation pattern shown in  FIG. 5 . 
         FIG. 7  is a block diagram illustrating an exemplary apparatus to control an acoustic radiation pattern whereby a signal processed by a focusing filter and a signal processed by a control pattern filter unit are separately output. 
         FIG. 8  is a diagram further illustrating the details of the apparatus for controlling an acoustic radiation pattern shown in  FIG. 7 . 
         FIG. 9  is a flowchart showing an exemplary method of controlling an acoustic radiation pattern. 
         FIG. 10  is a flowchart showing another exemplary method of controlling an acoustic radiation pattern. 
     
    
    
     Throughout the drawings and the detailed description, unless otherwise described, the same drawing reference numerals will be understood to refer to the same elements, features, and structures. The relative size and depiction of these elements may be exaggerated for clarity, illustration, and convenience. 
     DETAILED DESCRIPTION 
     The following detailed description is provided to assist the reader in gaining a comprehensive understanding of the methods, apparatuses, and/or systems described herein. Accordingly, various changes, modifications, and equivalents of the systems, apparatuses and/or methods described herein will be suggested to those of ordinary skill in the art. Also, descriptions of well-known functions and constructions may be omitted for increased clarity and conciseness. 
     In the following description, an acoustic radiation pattern denotes a pattern of a sound field formed by sound radiated from a signal output apparatus such as a speaker or antenna. A sound field conceptually denotes an area of sound pressure output in all directions from a sound source. Here, sound pressure denotes force of acoustic energy using the physical quantity of pressure. An acoustic signal radiated from an array of speakers is received by a measurer measuring an output signal according to distance from the array of speakers, and intensity of the received acoustic signal versus measurement distance may be shown in a graph, thereby obtaining such an acoustic radiation pattern. 
       FIG. 1  shows an exemplary apparatus  100  to control an acoustic radiation pattern output through an array of speakers, that is, a speaker array. 
     The apparatus  100  includes a focusing filter  110 , a controller  120 , and a control pattern filter  130 . 
     The focusing filter  110  processes an input signal to form an acoustic radiation pattern. The focusing filter  110  is generally used in a speaker array system processing an input signal to form a fixed acoustic radiation pattern. An acoustic radiation pattern formed by the focusing filter  110  may also be referred to as a reference pattern. 
     To form an intended acoustic radiation pattern (hereinafter, “intended pattern”) using an array of speakers, a filter appropriate for the intended pattern is calculated and used. Since the filter is fixed by the intended pattern defined in advance, another filter is calculated to generate another acoustic radiation pattern. In a general environment, however, it is difficult to change a filter value of a speaker array system to transform an intended pattern (e.g., removal of an unnecessary pattern such as a sidelobe) according to change in a filter design method or environment. 
     The apparatus  100  performs an operation to transform an intended pattern without modifying the focusing filter  110 . To this end, as one example, the apparatus  100  further includes the controller  120  and the control pattern filter  130 . 
     A method of transforming an intended pattern without modifying the focusing filter  110  will be described with reference to  FIGS. 2A and 2B . 
       FIG. 2A  illustrates an acoustic radiation pattern formed by a conventional focusing filter, and  FIG. 2B  illustrates examples of a control pattern and a form factor for forming an intended pattern according to an exemplary embodiment. 
     Referring to  FIG. 2A , it is assumed that acoustic radiation patterns  211 ,  212  and  213  are formed by a speaker array device  200 . A user may want to obtain the pattern  212  alone and remove the sidelobe patterns  211  and  213 . 
     According to an exemplary embodiment, an input signal may be processed using a control pattern  210  and a form factor  220  shown in  FIG. 2B , so as to remove the sidelobe patterns  211  and  213 . 
     Here, control patterns denote some previously-defined acoustic radiation patterns radiated using an array of speakers. A filter value for forming a control pattern is applied to a plurality of array of speakers and thus may have a matrix form. In this case, the filter value for forming a control pattern may be called a control pattern matrix. 
     Meanwhile, a form factor denotes weight data about a control pattern. A form factor may be data indicating a weight for each control pattern used when two or more filter values are combined. A weight may be a constant, or a window-shaped value varying according to an acoustic signal of each channel output through an array of speakers as shown in a graph  220  of the form factor shown in  FIG. 2B . 
     Referring back to  FIG. 1 , the control pattern filter  130  stores a plurality of filter values to form a plurality of corresponding control patterns set in advance from an input signal. The controller  120  calculates a compensation control pattern such that signals output through the array of speakers have an intended pattern, which is an intended acoustic radiation pattern, using a filter value of the focusing filter  110  and a filter value for the intended pattern. The controller  120  generates a control pattern selection signal to select at least one of control patterns stored in the focusing filter  110  in order to generate the compensation control pattern. Then, the control pattern filter  130  receives the control pattern selection signal, and processes the input signal using a filter value corresponding to the at least one control pattern selected according to the control pattern selection signal. 
     Examples of a control pattern will be described with reference to  FIG. 3 . 
     Referring to  FIG. 3 , in an exemplary control pattern filter  310 , a plurality of control pattern matrices  301 ,  302  and  303  are defined. The control pattern matrices  301 ,  302  and  303  denote filter values corresponding to a plurality of control patterns  311 ,  312  and  313 . 
     The control pattern matrices  301 ,  302  and  303  are of filter values for forming previously-defined patterns. The filter values corresponding to the patterns  311 ,  312  and  313  are calculated such that a beam pattern output from an array matches the previously-defined patterns  311 ,  312  and  313 , and then the matrices  301 ,  302  and  303  are derived from the filter values. 
     For example, the control pattern matrix  302  may be generated by calculating a filter value corresponding to the control pattern  312  using a least square error (LSE) filter design method. Here, the filter value of the control pattern  312  is defined to be orthogonal to a filter value of a reference pattern formed by an initially-defined focusing filter such that an acoustic radiation pattern can be controlled without affecting the reference pattern. Also, when filter values of respective control patterns are defined to be orthogonal to each other, a new pattern may be generated by combining existing filter values of control patterns. 
     When an intended pattern is determined, an acoustic signal can be radiated in a defined pattern form using such a control pattern matrix. 
     For example, given that a filter vector indicating a filter value for a focusing filter is R and a filter vector of an intended pattern is C, a vector of a compensation control pattern is −R+C. In other words, when control patterns corresponding to −R and C are stored in the control pattern filter  130 , the same effect as output of an input signal can be obtained using the vector (−R+C) of the compensation control pattern and finally the vector C of the intended pattern. 
     However, to form a pattern other than defined patterns, control patterns defined in advance is combined. Here, form factors are used to assign weights to pattern vectors and to combine them. 
     A form factor may be a constant, or a window-shaped weight varying according to channel. For example, when a pattern A and a pattern B are combined into a new pattern C, the pattern C, for example, (c 1 *A+c 2 *B), may be obtained by combining the pattern A with the pattern B using form factors c 1  and c 2 . 
     For example, a compensation control pattern and a form factor may be calculated as described below. 
     Given that a signal obtained by processing an input signal x using a filter value w r  of a focusing filter is v, a signal from a form factor w c  and a control pattern C is c, and a signal obtained by adding the two signals v and c is u, v, c and u may be expressed as follows:
 
V=W r X   [Equation 1]
 
c=Cw c x   [Equation 2]
 
 u=v−c =( w   r   −Cw   c ) x    [Equation 3]
 
     Given that a transfer function between an output device and a response position is G, a response Y to the summed signal u is as follows:
 
 Y=Gu=G ( w   r   −Cw   c ) x    [Equation 4]
 
     Here, regardless of the input signal x, a response pattern H according to frequency may be expressed as follows:
 
 H=G ( w   r   −Cw   c )   [Equation 5]
 
     Here, given that an intended response is D, an error between the target pattern D and the response pattern II is defined in Equation 6. Here, an optimum filter value is expressed in Equation 7 , and the optimum filter value based on the LSE filter design method is expressed in Equation 8.
 
 E=|D−H|   2   =|D−G ( w   r   −Cw   c )| 2    [Equation 6]
 
 w   a =( w   r   −Cw   c )   [Equation 7]
 
 w   a =( G   H    G ) −1   G   H    D    [Equation 8]
 
     By applying Equation 8 to Equation 7, a filter value for the control pattern C to form an intended pattern may be calculated. The optimum filter value w a  is a filter value corresponding to the above-mentioned compensation control pattern. 
     Here, a form factor may be calculated using the LSE filter design method as expressed in Equation 9. Given that a difference between the filter value w r  of a focusing filter and the optimum filter value w a  is T, and an error between the form factor w c  and the control pattern C is defined in Equation 10, an optimum form factor based on the LSE filter design method may be calculated as shown in Equation 11. 
     
       
         
           
             
               
                 
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     Meanwhile, a control pattern matrix may be expressed using output data of respective channels of an array of speakers. For example, given that a filter value, that is, a vector value, is defined as [1 1 1 1 1 1 1], a radiation pattern based on the filter value corresponds to a pattern radiated when all speakers in a seven-channel array output a signal at the same volume. In this way, simple forms of vectors such as [1 0 1 0 . . . ] and [1 −1 1 −1 . . . ] may be defined as pattern matrices, and pattern matrix values for the respective patterns are calculated and stored. 
     The apparatus  100  for controlling an acoustic radiation pattern may further include a user interface (not shown) which receives a user input signal for setting an intended pattern. An intended pattern may be input to the apparatus  100  to control an acoustic radiation pattern in various ways. For example, a user may select a plurality of control patterns, or may input a part and direction of an acoustic radiation pattern to be removed after the apparatus  100  shows the user the acoustic radiation pattern currently provided by the focusing filter. In this case, the controller  120  may select at least one of the control patterns based on the user input signal. 
     The controller  120  may generate a control pattern selection signal to select at least one of a control pattern to be added to a reference pattern formed by the focusing filter  130  and a control pattern to remove the whole or a part of the reference pattern. Then, the control pattern filter  130  may process an input signal using a control pattern selected according to the control pattern selection signal such that the intended pattern can be finally output. 
     Also, where an intended pattern may be not generated using the stored control patterns, the controller  120  may generate a control pattern selection signal to select at least two of the control patterns for at least one combination. Furthermore, the controller  120  may calculate form factors, which are weight data about the respective control patterns used for combining at least two filter values, to form the intended pattern. Then, the control pattern filter  130  may process the input signal using the control pattern selected according to the control pattern selection signal and the calculated form factors such that the intended pattern can be finally output. 
     As illustrated in  FIG. 1 , the controller  120  may include a control pattern setter  122  to set a control pattern, and a form factor calculator  124  to calculate a form factor. A signal generated by the control pattern setter  122  to select a control pattern and a form factor calculated by the form factor calculator  124  may be transferred to the control pattern filter  130 . 
       FIGS. 4A to 4C  illustrate exemplary structures for a speaker array device. 
       FIG. 4A  illustrates a structure of a speaker array device that performs acoustic focusing and controls an acoustic radiation pattern. The speaker array device of  FIG. 4A  may be used to modify a whole existing sound focusing pattern. 
       FIG. 4B  illustrates a structure of a speaker array device of which a part is used to control an acoustic radiation pattern. The speaker array device of  FIG. 4B  is used when speakers in one array are grouped and the respective speaker groups separately control, control patterns. For example, an array group  411  may output a reference pattern processed by a focusing filter, and an array group  412  may output a compensation control pattern processed by the control pattern filter. Also, depending on the size of the array of speakers and the number of the speakers, a speaker array device may generate two patterns or a combination of at least two patterns. 
       FIG. 4C  illustrates a case in which separate pattern control array devices are used to control an acoustic radiation pattern.  FIG. 4C  shows two completely separated acoustic systems  421  and  422 . The one speaker array device  421  may form a fixed reference pattern, and the other speaker array device  422  may control the fixed reference pattern. For example, a speaker array system may be additionally installed in an apparatus such as a television (TV) speaker system and used to adjust an acoustic radiation pattern for a specific area in space. 
       FIG. 5  illustrates an exemplary apparatus  500  to control an acoustic radiation pattern, including the speaker array device shown in  FIG. 4A . 
     The apparatus  500  includes a focusing filter  510 , a controller  520 , a control pattern filter unit  530 , a signal synthesizer  540 , and an output unit  550 . The focusing filter  510 , the controller  520  and the control pattern filter unit  530  correspond to the focusing filter  110 , the controller  120  and the control pattern filter  130  shown in  FIG. 1 , perform similar functions, and thus further descriptions thereof will be omitted for conciseness. 
     The signal synthesizer  540  synthesizes a first output signal that is an input signal processed and output by the focusing filter  510  with a second output signal that is the input signal processed and output by the control pattern filter unit  530 . The output unit  550  outputs the synthesized signal. 
       FIGS. 6A and 6B  illustrate further details of the apparatus shown in  FIG. 5 . 
     The structure of  FIG. 6A  may be used when there are no control pattern combinations but when only control patterns defined in the control pattern filter unit  530  are used. An input signal x(ω) is separately processed by the focusing filter  510  and the control pattern filter unit  530 . In the control pattern filter unit  530 , the input signal x(ω) is reproduced as a multi-channel signal by a reproducer  531 , processed by a control pattern filter  532  using a filter value corresponding to a control pattern set according to control of the controller  520 , and transferred to the signal synthesizer  540 . 
     The signal synthesizer  540  synthesizes the signals output from the focusing filter  510  and the control pattern filter  532  and outputs the synthesized signal to the output unit  550 . An amplification unit  552  of the output unit  550  amplifies the input signal and outputs it to an array of speakers  554 . 
       FIG. 6B  illustrates further details the apparatus  500  for controlling an acoustic radiation pattern using a control pattern and a form factor. 
     An input signal x(ω) is separately processed by the focusing filter  510  and the control pattern filter unit  530 . In the control pattern filter unit  530 , the input signal x(ω) is reproduced as a multi-channel signal by a form factor filter  533  according to a form factor set by the controller  520 , processed by a control pattern filter  534  using a filter value corresponding to a control pattern set according to control of the controller  520 , and transferred to the signal synthesizer  540 . 
     The signal synthesizer  540  synthesizes the signals output from the focusing filter  510  and the control pattern filter  534  and outputs the synthesized signal to the output unit  550 . The amplification unit  552  of the output unit  550  amplifies the input signal and outputs it to the array speakers  554 . 
       FIG. 7  illustrates an exemplary apparatus  700  to control an acoustic radiation pattern whereby a signal processed by a focusing filter and a signal processed by a control pattern filter unit are separately output. 
     The apparatus  700  may be additionally installed in a conventional speaker array device having a focusing filter  710  and a first output unit  750 . The apparatus  700  includes a controller  720 , a control pattern filter unit  730 , and a second output unit  760 . 
     The controller  720  receives a filter value of the focusing filter  710  processing an input signal to form one acoustic radiation pattern from another apparatus. The controller  720  calculates a compensation control pattern using the received filter value of the focusing filter  710  and a filter value for an intended pattern such that signals output through an array of speakers have the intended pattern. To form the compensation control pattern, a control pattern setter  722  generates a control pattern selection signal to select at least one of a plurality of control patterns set in advance in the control pattern filter unit  730 . 
     The function and operation of the controller  720  and the control pattern filter unit  730  are similar to those of the above-described controller  120  and the control pattern filter  130 , and thus will not be described again for conciseness. 
     The first output unit  750  outputs a first output signal that is an input signal processed and output by the focusing filter  710 , and the second output unit  760  outputs a second output signal that is the input signal processed and output by the control pattern filter unit  730 . 
       FIG. 8  illustrates further details of the apparatus shown in  FIG. 7 . 
     When a focusing array device is not the same as the apparatus  700  for controlling an acoustic radiation pattern as illustrated in  FIG. 7 , a signal is separately processed and output though different devices as illustrated in  FIG. 8 . 
     An input signal x(ω) is separately processed by the focusing filter  710  and the control pattern filter unit  730 . The signal processed by the focusing filter  710  is output to an array of speakers  754  via an amplifier unit  752  of the first output unit  750 . 
     In the control pattern filter unit  730 , the input signal x(ω) is reproduced as a multi-channel signal by a form factor filter  732  according to a form factor set by the controller  720 , processed by a control pattern filter  734  using a filter value corresponding to a control pattern set according to control of the controller  720 , and output to an array of speakers  764  via an amplifier unit  762  of the second output unit  760 . 
       FIG. 9  is a flowchart showing an exemplary method of controlling an acoustic radiation pattern. The method may be performed by an apparatus described above to control an acoustic radiation pattern. 
     An input signal to be output through an array of speakers is received in operation  910 . An intended pattern, which is an intended acoustic radiation pattern, is set in operation  920 . 
     A compensation control pattern such that signals output through the array of speakers have the intended pattern is generated using a filter value of a focusing filter, which processes an input signal to form one acoustic radiation pattern, and a filter value for the intended pattern, in operation  930 . 
     In operation  940 , a control pattern selection signal for selecting at least one of a plurality of control patterns is generated in order to form the compensation control pattern. In operation  950 , the input signal is processed using a filter value of the control pattern set depending on the control pattern selection signal. 
       FIG. 10  is a flowchart showing another exemplary method of controlling an acoustic radiation pattern. The method may be performed by an apparatus described above to control an acoustic radiation pattern 
     An input signal to be output through an array of speakers is received in operation  1010 . An intended pattern, which is an intended acoustic radiation pattern, is set by a user input signal, in operation  1020 . 
     In operation  1030 , a compensation control pattern such that signals output through the array of speakers form the intended pattern is calculated using a filter value for a focusing filter to form a reference pattern and a filter value for the intended pattern. 
     In operation  1040 , it is determined whether the compensation control pattern can be generated using a plurality of filter values corresponding to a plurality of control patterns defined in advance. 
     Where it is determined in operation  1040  that the compensation control pattern can be generated using a plurality of control patterns defined in advance, at least one of the control patterns is selected in operation  1080 , and a control pattern selection signal is generated in operation  1085 . For example, to form the intended pattern, the control pattern selection signal to select at least one of a control pattern to be added to the reference pattern formed by the focusing filter and a control pattern for removing the whole or a part of the reference pattern may be generated. The input signal is processed using a filter value of the control pattern selected according to the control pattern selection signal in operation  1090 . 
     Where it is determined in operation  1040  that the compensation control pattern cannot be generated using a plurality of control patterns defined in advance, at least two of the control patterns are selected for at least one control pattern combination in operation  1050 . Also, form factors, which are weight data about the respective control patterns, are calculated for the at least one control pattern combination in operation  1060 . A control pattern selection signal to set the selected control patterns and the form factors is generated in operation  1070 . The input signal is processed using the set control patterns and the calculated form factors in operation  1090 . 
     According to example(s) described above, there is provided an apparatus and method for forming an intended beam pattern using a plurality of filter values for forming a plurality of corresponding control patterns set in advance from an input signal and form factors, whereby weights of the control patterns are adjusted. 
     The methods described above may be recorded, stored, or fixed in one or more computer-readable media that includes program instructions to be implemented by a computer to cause a processor to execute or perform the program instructions. The media may also include, alone or in combination with the program instructions, data files, data structures, and the like. Examples of computer-readable media include magnetic media, such as hard disks, floppy disks, and magnetic tape; optical media such as CD ROM disks and DVDs; magneto-optical media, such as optical disks; and hardware devices that are specially configured to store and perform program instructions, such as read-only memory (ROM), random access memory (RAM), flash memory, and the like. Examples of program instructions include machine code, such as produced by a compiler, and files containing higher level code that may be executed by the computer using an interpreter. The described hardware devices may be configured to act as one or more software modules in order to perform the operations and methods described above, or vice versa. In addition, a computer-readable recording medium may be distributed among computer systems connected through a network and computer-readable codes may be stored and executed in a decentralized manner. 
     A number of exemplary embodiments have been described above. Nevertheless, it will be understood that various modifications may be made. For example, suitable results may be achieved if the described techniques are performed in a different order and/or if components in a described system, architecture, device, or circuit are combined in a different manner and/or replaced or supplemented by other components or their equivalents. Accordingly, other implementations are within the scope of the following claims.