Abstract:
The present invention provides a system and a method for transferring data between a Bluetooth device (BTD) and a wireless local area network (WLAN) device which uses packet traffic arbitration (PTA). The method of the present invention includes encoding data using a plurality of control lines between the BTD and WLAN, transmitting the data and acknowledging the data reception using the existing control lines. The method according to the present invention allows BTD and WLAN device to transmit additional scheduling information, schedule the medium access, and reduce the number of collisions between the two devices.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention generally relates to wireless communication, and more specifically relates to the data transfer between a collocated Bluetooth device (BTD) and a wireless local area network (WLAN) device. 
       BACKGROUND 
       [0002]    In today&#39;s world the use of wireless personal area networks (WPANs) has been gaining popularity because of the flexibility and convenience in connectivity they provide. WPAN systems, such as those based on Bluetooth technology, provides wireless connectivity to peripheral devices and/or mobile terminals by providing short distance wireless links that allow connectivity within a specific distance (10-meter range). In contrast to WPAN systems, wireless local area networks (WLANs) provide connectivity to devices that are located within a slightly larger geographical area, such as the area covered by a building or a campus, for example. WLAN systems are typically based on IEEE 802.11 standard specifications, typically operate within a 100-meter range, and are generally utilized to supplement the communication capacity provided by traditional wired local area networks (LANs) installed in the same geographic area as the WLAN system. In some instances, WLAN systems may be operated in conjunction with WPAN systems to provide users with an enhanced overall functionality. 
         [0003]    When operating a Bluetooth device (BTD) and a WLAN device in, for example, a wireless device, at two different types of interference effects may occur. One interference effect happens because the Bluetooth devices and WLAN devices transmit on the same or overlapping frequencies. 
         [0004]    The second effect occurs if the transceiver of a Bluetooth device is in close proximity to the transceiver of a WLAN device as it is the case in mobile phones or personal digital assistants (PDA). In this instance the transmitter of one device overloads the receiver of the other device and the receiver is not able to receive any signals independent of whether the Bluetooth device and WLAN device use the same frequencies. 
         [0005]    The collocation interferences are solved using packet traffic arbitration (PTA) technique. The solution requires physical connections between the BTD and WLAN device as well as software modifications. To accommodate different receive/transmit scenarios, a total of four control signals are set up between the BTD and WLAN device. The control signals include a Bluetooth line (BT line), a wireless local area network line (WL line), a wireless local area network receive indicator line (RXIND line), and a priority line (PRI line). BT line and WL line are basic arbitration signals from BTD and WLAN device respectively. PRI line is a Bluetooth priority indicator for very important traffic. 
         [0006]    These control lines between the BTD and WLAN device provide very limited amount of information to efficiently arbitrate the medium access between BTD and WLAN device and also the do not provide information such as connection type and type of link of communication (asynchronous connection-less (ACL) link, synchronous connection oriented (SCO) link or enhanced synchronous connection oriented (eSCO) link). Also BTD or WLAN device do not know the time period for which the other device needs the medium and for what purpose. This lack of knowledge leads to sub-optimal scheduling of the medium access for BTD and WLAN device. The BTD and WLAN device are connected to a host system (main processor or micro controller) and some of the data transfer between the BTD and WLAN device occurs through the host system. In case of time critical data, the data transfer through the host system takes too much time. 
         [0007]    Hence, it would be advantageous to provide a method and a system for transferring data between the collocated BTD and WLAN device through the existing control lines between the two devices. The present invention has been developed to meet these needs in the art. 
       SUMMARY OF THE INVENTION 
       [0008]    The present invention provides a system and a method for transferring data between a Bluetooth device (BTD) and a wireless local area network (WLAN) device which uses packet traffic arbitration (PTA). The method of the present invention includes encoding data using a plurality of control lines between the BTD and WLAN device, transmitting the data, and acknowledging the data reception using the existing control lines. The method according to the present invention allows BTD and WLAN device to transmit additional scheduling information, schedule the medium access, and reduce the number of collisions between the two devices. 
         [0009]    In an example embodiment of the present invention, a method for transferring data between a collocated BTD and a WLAN device is provided. The method includes the steps of encoding data using a plurality of control lines between the BTD and WLAN device, transmitting the data from the BTD to the WLAN device, and acknowledging data reception by the WLAN device using another control line between the BTD and the WLAN device. The plurality of control lines used for encoding data includes a priority line (PRI line) and a Bluetooth line (BT line). The WLAN device uses a wireless local area network line (WL line) to acknowledge the data reception. After the data is sent to the WLAN device, the BTD raises the PRI line before the start of next Bluetooth frame. 
         [0010]    In another example embodiment of the present invention, a method for transferring data between a collocated BTD and a WLAN device is provided. The method includes the steps of encoding data using a plurality of control lines between the BTD and WLAN device, transmitting data from the WLAN device to the BTD, and acknowledging data reception by the BTD using another control line between the BTD and the WLAN device. The plurality of control lines used for encoding data includes a wireless local area network receive indicator line (RXIND line) and WL line. The WLAN device uses BT line to acknowledge the data reception. 
         [0011]    In another example embodiment of the present invention, a system is provided for transferring data in wireless communication. The system includes a BTD collocated with a WLAN device for enabling the wireless communication, an interface between the BTD and WLAN device, where the interface includes a plurality of control lines between the BTD and WLAN device, a data encoding state machine for encoding and transmitting the data using the plurality of control lines, and another control line within the plurality of control lines for acknowledging a data reception between the Bluetooth device and wireless local area network device. When the data transfer occurs from BTD to WLAN device, PRI line and BT line are used to encode the data, and data reception is acknowledged from the WLAN device using WL line. When the data transfer occurs from WLAN device to the BTD, RXIND line and WL line are used to encode the data, and data reception is acknowledged from the BTD using BT line. 
         [0012]    The above summary of the present invention is not intended to represent each disclosed embodiment, or every aspect, of the present invention. Other aspects and example embodiments are provided in the figures and the detailed description that follows. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]    The invention may be more completely understood in consideration of the following detailed description of various embodiments of the invention in connection with the accompanying drawings, in which: 
           [0014]      FIG. 1A  is a flow diagram illustrating the method of transferring data from a collocated BTD to a WLAN device according to an example embodiment of the present invention. 
           [0015]      FIG. 1B  is a flow diagram illustrating the method of transferring data from the collocated WLAN to the BTD according to an example embodiment of the present invention. 
           [0016]      FIG. 2  is a block diagram illustrating the system for transferring data from the collocated WLAN to the BTD according to an example embodiment of the present invention. 
           [0017]      FIG. 3  illustrates the data protocol for transferring data from collocated BTD to the WLAN device. 
           [0018]      FIG. 4  illustrates the data encoding state diagram for encoding data. 
           [0019]      FIG. 5  illustrates an example when BTD transmits the data bits ‘010’ to the WLAN device according to the method of the present invention. 
           [0020]      FIG. 6  illustrates the order and description of the information elements in the PTA data protocol. 
       
    
    
       [0021]    While the invention is amenable to various modifications and alternative forms, specifics thereof have been shown by way of example in the drawings and will be described in detail. It should be understood, however, that the intention is not to limit the invention to the particular embodiments described. On the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims. 
       DETAILED DESCRIPTION  
       [0022]      FIG. 1A  is a flow diagram illustrating the method of transferring data from the collocated BTD to the WLAN device according to an example embodiment of the present invention. The PTA data protocol for transferring data from BTD to the WLAN device is explained as follows. The PTA data protocol transmits data during the PRI period from the BTD to the WLAN device. In a step  100 , the data is encoded using the PRI line and BT line. A step  105  transmits the data from the BTD to the WLAN device. In a step  110 , the WLAN device acknowledges the data reception using WL line. The PRI line and BT line undergoes at least one state transition for each data bit of the data sent to the WLAN device. After the data bits are sent to the WLAN device, the BTD raises the PRI line before the start of next Bluetooth frame. This method allows the transmission of additional information over the existing control lines between the BTD and WLAN device. This information allows BTD and WLAN device to efficiently schedule the medium access and reduce the number of collisions between the two devices. 
         [0023]      FIG. 1B  is a flow diagram illustrating the method of transferring data from the collocated WLAN to the BTD according to an example embodiment of the present invention. The PTA data protocol for transferring data from WLAN device to the BTD is explained as follows. In a step  115 , the data is encoded using the RXIND line and WL line. A step  120  transmits the data from the WLAN device to the BTD. In a step  125 , the BTD acknowledges the data reception using BT line. The RXIND line and WL line undergoes at least one state transition for each data bit of the data sent to the BTD. After the data bits are sent to the BTD, the WLAN device raises the WL line before the start of next WLAN frame. 
         [0024]      FIG. 2  is a block diagram illustrating the system for transferring data from the collocated WLAN to the BTD according to an example embodiment of the present invention  200 . The system includes a host controller  205 , the BTD  210  and WLAN device  215 . There are four control lines between the BTD  210  and WLAN device  215  as an interface. The control lines include RXIND line, WL line, BT line and PRI line. BT line and PRI line goes from BTD  210  to the WLAN device  215  and RXIND line and WL line goes in the opposite direction. The system also includes a data encoding state machine (not shown) for encoding data using the control lines between the BTD  210  and WLAN device  215 . The data bits are encoded using the control lines. If data is transmitted from the BTD  210  to the WLAN device  215 , PRI line and BT line are used for encoding data. The WLAN device  215  acknowledges the data reception by WL line. If data is transmitted from the WLAN device  215  to the BTD  210 , RXIND line and WL line are used for encoding data. The BTD  210  acknowledges the data reception using BT line. 
         [0025]      FIG. 3  illustrates the data protocol for transferring data from collocated BTD to the WLAN device  300 . The data bits are encoded using PRI line and BT line. As shown in  FIG. 3 , the data transfer starts after the PRI line is raised by the BTD and WLAN device has acknowledged the raised PRI line. For each data bit sent to the WLAN device the PRI line and BT line undergoes at least one state transition. After the data bits are sent to the WLAN device, BTD raises the PRI line again after a period of time (time period depends of the time left after the communication period) before the beginning of the next Bluetooth frame (BTD does not raise the PRI line earlier). 
         [0026]      FIG. 4  illustrates the data encoding state diagram for encoding data  400 . The first number (on the left side of the circles) indicates the PRI line state and the second number (number on the right side of the circles) indicates the BT line state. This state diagram is applicable to the case where data is transferred from BTD to WLAN device. The communication starts when the PRI line is raised. When the PRI line is raised by BTD, the PRI line state is ‘1’ and BT line state is ‘0’. So, at the start of the communication the state of PRI line and BT line is ‘10’. The data transmission is terminated by setting both PRI line and BT line to ‘0’ and WL line has acknowledged the termination. 
         [0027]      FIG. 5  illustrates an example when BTD transmits the data bits ‘010’ to the WLAN device according to the method of the present invention  500 . PRI line is raised by the BTD and data bits are encoded using PRI and BT lines. The data transmission starts after the WLAN device acknowledges the raised PRI line. The BTD transmits the data bits ‘010’ to the WLAN device. For each data bit sent to the WLAN device, the PRI line and BT line undergoes at least one state transition. 
         [0028]      FIG. 6  illustrates the order and description of the information elements in one embodiment of the PTA data protocol  600 . The PTA data protocol is structured so that important information is encoded with few number of data bits and other information is encoded with more number of data bits. Depending on the link information element at the beginning, the different information elements include role information element, asynchronous connection-less (ACL) link transmission packet element, ACL link reception packet element, NBf element and NFc element  605 . The description for the link information element is as follows. An ACL link is indicated by ‘00’. The state ‘01’ is reserved, ‘10’ for synchronous connection oriented (SCO) link and ‘11’ for enhanced synchronous connection oriented (eSCO) link  610 . 
         [0029]    In the role information element table, ‘0’ indicates a master configuration and ‘1’ indicates a slave configuration  615 . In the ACL transmission (ACL TX) packet element, bits ‘00’, ‘01’, ‘10’ indicates one slot, three slots and five slots respectively. The state ‘11’ is reserved  620 . In the ACL reception (ACL RX) packet element, bits ‘00’, ‘01’, ‘10’ indicates one slot, three slots and five slots respectively and the state ‘11’ is reserved  625 . In the NBf element table and NFc element table, bits 0-3 indicate the number of frames  630 ,  635 . 
       INDUSTRIAL APPLICATION 
       [0030]    The applications of the present invention includes, but not limited to, such as mobile phones or personal digital assistants (PDAs) that use Bluetooth and WLAN in a close proximity. 
         [0031]    While the present invention has been described with reference to several particular example embodiments, those skilled in the art will recognize that many changes may be made thereto without departing from the spirit and scope of the present invention, which is set forth in the following claims.