Abstract:
A system and method for transmitting data. The system and method is configured to dynamically implement one of a differential signaling method or a single-ended signaling method during a transmission of data. The signaling method is selected based on a measured interference level during the transmission of data. The implementation of the signaling method is performed without interrupting the data transmission.

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) AND CLAIM OF PRIORITY 
     The present application claims priority under 35 U.S.C. §119(a) to a Chinese patent application filed in the Chinese Intellectual Property Office on Dec. 15, 2009 and assigned Serial No. 200910259164.5, the entire disclosure of which is hereby incorporated by reference. 
     TECHNICAL FIELD 
     The disclosure relates generally to data transmission systems, and in particular to differential transmission systems. 
     BACKGROUND 
     Differential signaling is a method of transmitting information electrically by means of two complementary signals sent on two separate lines. The technique can be used for both analog signaling, as in some audio systems, and digital signaling, as in RS-422, RS-485, Ethernet (twisted-pair only), PCI Express and USB. The opposite technique, which is more common but lacks some of the benefits of differential signaling, is called single-ended signaling. 
     In differential signaling, at one end of a transmission channel connection, a receiving device reads the difference between the two signals. Since the receiver ignores the wires&#39; voltages with respect to ground, small changes in ground potential between transmitter and receiver do not affect the receiver&#39;s ability to detect the signal. 
     SUMMARY 
     Embodiments of the present disclosure provide an article of manufacture for transmitting data. The article of manufacture includes a computer readable medium. The computer readable medium includes a plurality of instructions configured to cause a processor to determine an interference level on a transmission channel; dynamically implement a signaling method corresponding to the interference level on the transmission channel; and transmit data utilizing the selected signaling method. 
     Embodiments of the present disclosure provide a system for data communications. The system includes a transmitter adapted to determine an interference level on a transmission channel. The transmitter is configured to dynamically implement a signaling method based on the interference level. The system further includes a receiver configured to receive data transmitted using the implemented signaling method. 
     Embodiments of the present disclosure provide a method for data communications. The method includes determining an interference level on a transmission channel. The method further includes dynamically implementing a signaling method based on the interference level and transmitting data using the selected signaling method. 
     Other technical features may be readily apparent to one skilled in the art from the following figures, descriptions and claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a more complete understanding of this disclosure and its features, reference is now made to the following description, taken in conjunction with the accompanying drawings, in which: 
         FIG. 1A  illustrates a device that may be used to transmit data according to embodiments of the present disclosure; 
         FIGS. 1B ,  1 C and  1 D illustrate a communication system according to embodiments of the present disclosure; 
         FIG. 2A  illustrates a differential signaling transmission format according to embodiments of the present disclosure; 
         FIG. 2B  illustrates a single-ended signaling transmission format according to embodiments of the present disclosure; 
         FIG. 3  illustrates a simple flow diagram for selecting signaling methods according to embodiments of the present disclosure; 
         FIG. 4A  illustrates a flexible differential signaling transmission format according to embodiments of the present disclosure. 
         FIG. 4B  illustrates data transmissions utilizing a differential signaling method according to embodiments of the present disclosure; 
         FIG. 4C  illustrates data transmissions utilizing a flexible differential signaling method according to embodiments of the present disclosure. 
     
    
    
     Before undertaking the DETAILED DESCRIPTION OF THE INVENTION below, it may be advantageous to set forth definitions of certain words and phrases used throughout this patent document. The term “packet” refers to any information-bearing communication signal, regardless of the format used for a particular communication signal. The terms “application,” “program,” and “routine” refer to one or more computer programs, sets of instructions, procedures, functions, objects, classes, instances, or related data adapted for implementation in a suitable computer language. The term “couple” and its derivatives refer to any direct or indirect communication between two or more elements, whether or not those elements are in physical contact with one another. The terms “transmit,” “receive,” and “communicate,” as well as derivatives thereof, encompass both direct and indirect communication. The terms “include” and “comprise,” as well as derivatives thereof, mean inclusion without limitation. The term “or” is inclusive, meaning and/or. The phrases “associated with” and “associated therewith,” as well as derivatives thereof, may mean to include, be included within, interconnect with, contain, be contained within, connect to or with, couple to or with, be communicable with, cooperate with, interleave, juxtapose, be proximate to, be bound to or with, have, have a property of, or the like. The term “controller” means any device, system, or part thereof that controls at least one operation. A controller may be implemented in hardware, firmware, software, or some combination of at least two of the same. The functionality associated with any particular controller may be centralized or distributed, whether locally or remotely. 
     DETAILED DESCRIPTION 
       FIGS. 1A through 4C , discussed below, and the various embodiments used to describe the principles of the present disclosure in this patent document are by way of illustration only and should not be construed in any way to limit the scope of the disclosure. Those skilled in the art will understand that the principles of the present disclosure may be implemented in any suitably arranged wireless or wireline communication network. 
       FIG. 1A  illustrates a device  100  that may be used to transmit data according to embodiments of the present disclosure. It would be understood that illustration of the device merely is exemplary and other devices can be utilized without departing from the scope of the present disclosure. 
     The device  100  may be a computer, personal digital assistant (FDA), cellular telephone, or any other device capable of transmitting, processing, and/or receiving signals via wireless and/or wireline communication links. The device  100  may include components such as a central processing unit (“CPU”)  105  (e.g., a processor or special purpose controller), a memory unit  110 , an input/output (“I/O”) device  115 , a network interface  120 , and a communication device  125 . The network interface  120  may be, for example, one or more network interface cards (NICs) that are each associated with a media access control (MAC) address. The components  105 ,  110 ,  115 ,  120  and  125  are interconnected by one or more communication links  130  (e.g., a bus). It is understood that the device  100  may be differently configured and that each of the listed components may actually represent several different components. For example, the CPU  105  may actually represent a multi-processor or a distributed processing system; the memory unit  110  may include different levels of cache memory, main memory, hard disks, and remote storage locations; and the I/O device  115  may include monitors, keyboards, and the like. The network interface  120  enables the device  100  to connect to a network. The communication device  125  can include a plurality of transmission antennas configured to transmit data via a wireless communication medium and/or a plurality of receiving antennas configured to receive data from a wireless communications medium. In some embodiments, the communication device  125  includes transmitters and/or receivers configured to communicate data via an infrared medium, wireless fidelity (wifi) medium, and an acoustic medium. 
     Referring now to  FIGS. 1B ,  1 C and  1 D a communications system  140  according to embodiments of the present disclosure is illustrated. It would be understood that illustration of the communication system  140  merely is exemplary and other communications systems can be utilized without departing from the scope of the present disclosure. 
     The system includes a transmitter  150  and a receiver  155 . The transmitter  150  can include the same general structure as the device  100 . In some embodiments, the communication device  125  in the transmitter  150  is configured to transmit data via a wireline medium. In some embodiments, the communications device  125  in the transmitter  150  includes a plurality of transmission antennas configured to transmit data via a wireless medium. Additionally, the receiver  155  can include the same general structure as the device  100 . In some embodiments, the communication device  125  in the receiver  155  is configured to receive data via a wireline medium. In some embodiments, the communications device  125  in the receiver  155  includes a plurality of receiving antennas configured to receive data via a wireless medium. 
     A transmitter  150  transmits data to a second device the receiver  155 . The data is transmitted differentially along a transmission channel  145 . The transmission channel  145  includes Line Input One  160  (IN 1 ) and Line Input Two  165  (IN 2 ). The signal levels in each of IN 1   160  and IN 2   165  are opposite in order to counter the effects of noise. Accordingly, a first pulse  170  on IN 1   160  is opposite to a second pulse  175  on IN 2   165  as illustrated in  FIG. 1C . The first pulse  170  and the second pulse  175  are transmitted substantially simultaneously. The receiver  155  is configured to sum the differential signals to obtain an output pulse  180  on an output line  185 . However, if a noise  190  occurs on the lines IN 1   160  and IN 2   165 , the receiver  155  will not produce a pulse on the output line  185  since the noise is not differential. 
       FIG. 2A  illustrates a frame format  200  according to embodiments of the present disclosure. It would be understood that illustration of the frame format  200  merely is exemplary and other formats can be utilized without departing from the scope of the present disclosure. 
     Transmitting differential signals IND 1   205  and IND 2   210  inhibit the errors caused by interference on the transmission channel  145  (e.g., noise on IN 1   160  and/or IN 2   165 ) such that the data transmission is reliable. Accordingly, to inhibit the effects of noise, the system  140  utilizes additional bandwidth to transmit the data. 
     One measure of the interference (e.g., noise) on the transmission channel  145  (IN 1   160  and/or IN 2   165 ) is the level of erroneous bits in a transmission. The level of erroneous bits in a transmission is the Bit Error Rate (BER). The BER is the ratio of the number of bits, elements, characters, or blocks incorrectly received to the total number of bits, elements, characters, or blocks sent during a specified time interval. Examples of the BER are (a) transmission BER, i.e., the number of erroneous bits received divided by the total number of bits transmitted; and (b) information BER, i.e., the number of erroneous decoded (corrected) bits divided by the total number of decoded (corrected) bits. 
     In some embodiments, a single-ended signaling is utilized by the transmitter  150 . In single-ended signaling, the transmitter  150  generates a single voltage that the receiver  155  compares with a fixed reference voltage, both relative to a common ground connection shared by both ends. An RS-232 system is an example of single-ended signaling, which uses ±12V to represent a signal (e.g., a logical “1”), and anything less than ±3V to represent the lack of a signal (e.g., a logical “0”). The high voltage levels give the signals some immunity from noise, since few naturally occurring signals can create that sort of voltage. Single-ended signaling also has the advantage of requiring only one wire per signal in some embodiments. 
       FIG. 2B  illustrates a frame format  220  according to embodiments of the present disclosure. It would be understood that illustration of the frame format  220  merely is exemplary and other formats can be utilized without departing from the scope of the present disclosure. 
     In some embodiments, the communication system  140  is adapted to vary the method utilized to transmit data. In such embodiments, the transmitter  150  is configured to determine a level of interference on the transmission channel  145 , e.g., IN 1   160  and/or IN 2   165 . If the interference level is above a certain threshold, the transmitter  150  is configured to transmit the data differentially. However, if the interference level is below a certain threshold, the transmitter  150  is configured to transmit the data via a single-ended communication format. Further, the transmitter is configured to dynamically change transmission formats from differential to single-ended and from single-ended to differential based on a change in the interference level. The receiver  155  is configured to determine what format, e.g., differential or single-ended, was utilized to transmit the data. Thus, the receiver  155  is configured to receive, and decode as needed, the data from the transmitter  150  in both the differential format and the single-ended format. 
       FIG. 3  illustrates a simple flow diagram for selecting transmission formats according to embodiments of the present disclosure. It would be understood that illustration of the transmission format selection process merely is exemplary and other transmission format selection processes can be utilized without departing from the scope of the present disclosure. 
     The transmitter  150  starts the process to transmit data in step  305 . In step  310 , the transmitter  150  determines an interference level on the transmission channel, e.g., on IN 1   160  and/or IN 2   165 . In one embodiment, the interference level (e.g., noise) on the transmission channel  145  may be determined by the BER for the transmission channel  145 . In some embodiments, the transmitter  150  makes an transmission format selection based on factors that indicate an interference in the voltage or temperature on the transmission channel  145 . For simplicity, BER will be utilized in this example. However, it would be understood that other factors can be utilized without departing from the scope of this disclosure. 
     If the interference is above a specified threshold (e.g., BER&gt;threshold) in step  315 , then the transmitter  150  transmits the data differentially in step  320 . Thereafter, the process returns to step  310  wherein the transmitter  150  continues to determine the interference level on the transmission channel  145 . 
     If the interference is equal to or below a specified threshold (e.g., BER&lt;threshold) in step  315 , then the transmitter  150  transmits the data in a single-ended format in step  325 . The transmitter  150  transmits the data in a single-ended format by transmitting one or more data bits substantially simultaneously via IN 1   160  and IN 2   165 . The receiver  155  is configured to combine the data received via IN 1   1605  and IN 2   165 . In additional embodiments, the data transmitted via IN 1   160  and IN 2   165  is encoded utilizing an error correction coding such as, but not limited to, a repetition scheme, parity scheme (e.g., even-check or odd-check), checksum, Cyclic Redundancy Check (CRC), Hamming distance based checks, Hash function, horizontal and vertical redundancy check and polarity schemes. In such embodiments, the receiver  155  is configured to decode and combine the data received on IN 1   160  and IN 2   165 . In some embodiments, the transmitter  150  transmits a first data via IN 1   160  while transmitting a second data via IN 2   165 . In such embodiments, the receiver  155  is configured to receive the different data (e.g., the first data and second data) via IN 1   160  and IN 2   165 . Thereafter, the process returns to step  310  wherein the transmitter  150  continues to determine the interference level on the transmission channel  145 . 
     Referring now to  FIG. 4A , a frame format  400  for data transmissions according to embodiments of the present disclosure is illustrated. It would be understood that illustration of the frame format  400  merely is exemplary and other frame formats can be utilized without departing from the scope of the present disclosure. 
     The transmitter  150  transmits data along IN 1   160  and IN 2   165 . IN 1 D  405  represents a frame format for data transmitted along IN 1   160 . IN 2 D  410  represents a frame format for data transmitted along IN 2   165 . The transmitter  150  determines that the interference on IN 1   160  and IN 2   165  is above a threshold level. Therefore, the transmitter  150  transmits the first eight (8) bits of data  415  (e.g., D 0  to D 7 ) utilizing the differential method (e.g., differentially). Thereafter, the transmitter  150  determines that the interference level drops below the threshold. Therefore, the transmitter  150  transmits the second eight (8) bits of data  205  (e.g., D 8  to D 15 ) via the single-ended method. Therefore, the transmitter dynamically changes the transmission format from a differential system to a single-ended system. 
     Further, as illustrated in  FIG. 4A , the transmitter  150  transmits D 8 , D 10  D 12  and D 14  along IN 1   160  and D 9 , D 11 , D 13  and D 15  along IN 2   165 . Therefore, the flexible differential transmission requires less time to transmit data than traditional differential systems. 
     Referring now to  FIGS. 4B and 4C , two transmission formats according to embodiments of the present disclosure are illustrated. In  FIG. 4B , the transmitter  150  transmits the data using a traditional differential transmission  430  according to embodiments of the present disclosure. The transmitter  150  transmits two bytes  450  and  455 . The first byte  450  is transmitted along IN 1   160  and IN 2   165  in a first time interval. The second byte  455  is transmitted along IN 1   160  and IN 2   165  in a second time interval. IN 1 D  435  represents a frame format for data transmitted along IN 1   160 . IN 2 D  440  represents a frame format for data transmitted along IN 2   165 . The data are coded according to the following:
     IN 1   435  as clocked by clock signal  445 :   00110100 in the first time interval  460 .   10001011 in the second time interval  465 .   IN 2   440  as clocked by clock signal  445 :   11001011 in the first time interval  460 .   01110100 in the second time interval  465 .   

     Thus, in the above example, the transmitter  150  transmits the data to the receiver  155  in one-hundred-sixty (160) nanoseconds. 
     In  FIG. 4C , the transmitter  150  transmits the data utilizing a flexible differential transmission  470  according to embodiments of the present disclosure. The transmitter  150  transmits two bytes  485  and  490 . The first byte  485  is transmitted along IN 1   160  and IN 2   165  in a first time interval. The second byte  490  is transmitted along IN 1   160  and IN 2   165  in a second time interval. IN 1 D  475  represents a frame format for data transmitted along IN 1   160 . IN 2 D  480  represents a frame format for data transmitted along IN 2   165 . The data are coded according to the following:
     IN 1   475  as clocked by clock signal  445 :   00110100 in the first time interval  460 .   1011 in the second time interval  495  which is half the second time interval  465  illustrated in  FIG. 4B .   IN 2   480  as clocked by clock signal  445 :   11001011 in the first time interval  460 .   0001 in the second time interval  495  which is half the second time interval  465  illustrated in  FIG. 4B .   

     Thus, in the above example, the transmitter  150  transmits the data to the receiver  155  in one-hundred-twenty (120) nanoseconds. Further, the second byte  490  transmitted by the flexible differential transmission is transmitted in half the time required to transmit the second byte  455  transmitted by the traditional differential transmission. 
     While this disclosure has described certain embodiments and generally associated methods, alterations and permutations of these embodiments and methods will be apparent to those skilled in the art. Accordingly, the above description of example embodiments does not define or constrain this disclosure. Other changes, substitutions, and alterations are also possible without departing from the spirit and scope of this disclosure, as defined by the following claims.