Patent Publication Number: US-2004057455-A1

Title: Wireless LAN card and method of controlling the same

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
       [0001] This application claims the benefit of Korean Application No. 2002-57235, filed Sep. 19, 2002, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference.  
       BACKGROUND OF THE INVENTION  
       [0002] 1. Field of the Invention  
       [0003] The present invention relates to a wireless LAN card and a method of controlling the same, and more particularly, to a wireless LAN card and a method of controlling the same, in which an RF (radio frequency) part is detachably connected.  
       [0004] 2. Description of the Related Art  
       [0005] An OSI (open system interconnection) protocol layer standardized by an OSI reference model defines a hierarchy of seven layers. The lowermost layer of the OSI model is a physical layer. A data-link layer containing a MAC (media access control) sublayer and a LLC (logical link control) sublayer is directly above the physical layer. Further, a network layer to set up an Internet protocol is above the data-link layer, and a transport layer to set up a TCP (transmission control protocol) is above the network layer. A session layer, a presentation layer, and an application layer being uppermost layers are in sequence above the transport layer.  
       [0006] Further, a LAN (local area network) card is employed as an interface to send and receive data between any two computers in a network, and furnishes the physical layer operation in the OSI protocol layers.  
       [0007] Further, a PCMCIA (personal computer memory card international association) type card is suitable to provide extended capability to a portable computer, and is connected to the portable computer through a PCMCIA bus adapter communicating with a standard bus such as, for example, an ISA (industry standard architecture) bus, an EISA (extended industry standard architecture) bus, a PCI (peripheral component interconnect) bus.  
       [0008] Further, a wireless LAN card of the PCMCIA type card furnishes both the physical layer operation and the MAC layer operation, and communicates with the portable computer by control of the PCMCIA controller.  
       [0009] The wireless LAN card sends and receives data through airwaves, so that the physical layer is needed which can convert a baseband signal into an airwave band of the wireless connection. Hence, the physical layer includes an A/D (analog/digital) converter, a D/A converter, a modulator, a demodulator, and an antenna.  
       [0010] A family of specifications for wireless LANs developed by a working group of IEEE (institute of electrical and electronics engineers) is 802.11, and is currently part of a series of wireless specifications together with 802.11a, 802.11b, and 802.11g. All four specifications use Ethernet protocol and CSMA/CA (carrier sense multiple access with collision avoidance) to path share.  
       [0011] A modulation operation used in 802.11 is PSK (phase-shift keying), and a modulation operation selected for 802.11b (often called Wi-Fi) upgraded from the 802.11 specification is known as CCK (complementary code keying), which allows higher data speeds and is less susceptible to a multipath-propagation interface. The 802.11b (Wi-Fi) specification operates in a 2.4 GHz range, offering data speeds up to 11 Mbps (megabits per second). Further, the 802.11a specification upgraded from the 802.11b specification applies to wireless ATM (asynchronous transfer mode) systems, operates at radio frequencies (RF) band between 5 GHz and 6 GHz, and uses a modulation operation known as OFDM (orthogonal frequency-division multiplexing) which makes possible data speeds as high as 54 Mbps.  
       [0012] Thus, the PCMCIA wireless LAN card for the 802.11b specification should have a CCK demodulator and a 2.4 GHz RF processing part. The PCMCIA wireless LAN card for the 802.11a specification should have an OFDM demodulator and a 5 GHz RF processing part. The PCMCIA wireless LAN card for both the 802.11a and 802.11b specifications should have the CCK and OFDM demodulators and the 2.4 GHz and 5 GHz RF processing parts.  
       [0013] However, because a regulation of a 5 GHz band for the 802.11a specification varies according to regulations of each nation, the PCMCIA wireless LAN card for the 802.1a specification should be individually manufactured with a radio frequency of the PCMCIA wireless LAN card being tuned according to a selected nation, thereby decreasing productive efficiency of the PCMCIA wireless LAN card. Further, the PCMCIA wireless LAN card for both the 802.11a and 802.11b specifications includes two demodulators and two RF processing parts all together, so that costs of the PCMCIA wireless LAN card are relatively expensive. Also, the 802.11a and 802.11b specifications are compatible with each other in the MAC layers, so that if a user replaces the PCMCIA wireless LAN card of the 802.11a specification or 802.11b specification with another specification, components for one MAC layer are wasted.  
       [0014] Therefore, if the physical layer is detachably provided in the PCMCIA wireless LAN card, the PCMCIA wireless LAN card is easily changeable for another specification by changing only the physical layer. Further, a PCMCIA memory card is identical with the PCMCIA wireless LAN card in the specification except for the physical layer, so that if the PCMCIA memory card is combined with the PCMCIA wireless LAN card, the PCMCIA wireless LAN card is variously utilizable.  
       SUMMARY OF THE INVENTION  
       [0015] Accordingly, it is an aspect of the present invention to provide a wireless LAN card and a method of controlling the same, in which the wireless LAN card is usable as a memory card and a wireless sending/receiving part thereof is easily replaceable for one of a desired specification.  
       [0016] Additional aspects and/or advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.  
       [0017] The above and/or other aspects are achieved by providing a wireless LAN card connectable to a portable computer having a main body with a PCMCIA socket, comprising a wireless transmission board including a wireless sending/receiving part to modulate and demodulate packet data of a specific frequency modulation range and to wirelessly send and receive data; and a wireless LAN board including a controller to sense whether or not the wireless transmission board is connected to the wireless LAN board, to convert data received through the PCMCIA socket into packet data, and to transmit the packet data to the wireless transmission board.  
       [0018] According to an aspect, the wireless LAN board includes a main body connection part connectable to the PCMCIA socket, a connection part to which the wireless transmission board is detachably connected, and a memory part to store the data received through the main body connection part, and the controller operates in a PCMCIA memory card mode when the wireless transmission board is not connected to the wireless LAN board, which stores the data received through the main body connection part in the memory part and reads the data stored in the memory part according to a reading order from the main body so as to transmit the read data to the main body through the PCMCIA socket.  
       [0019] According to a further aspect, the wireless LAN board includes a connection sensing part to sense whether or not the wireless transmission board is connected to the wireless LAN board, and the controller operates in a wireless LAN card mode when the wireless transmission board is connected to the wireless LAN board, the connection sensing part outputting an interrupt signal to the main body and transmits the data from the main body to the wireless transmission board.  
       [0020] According to another aspect, the wireless sending/receiving part includes an antenna; an A/D converter converting an analog signal into a digital signal and/or converting a digital signal into an analog signal; an RF processing part modulating the packet data received from the controller through the A/D converter into a high frequency signal having a specific IF intermediate frequency, and sending a high frequency analog signal through the antenna; and a baseband processing part demodulating a high frequency signal directed by the antenna into a low frequency signal by filtering the IF, and transmits the low frequency signal to the controller through the A/D converter.  
       [0021] According to an aspect, the baseband processing part demodulates the packet data by using one of OFDM and CCK modulation operations.  
       [0022] According to another aspect, the above and/or other aspects may be achieved by providing a method of controlling a wireless LAN card connectable to a portable computer having a main body with a PCMCIA socket, comprising connecting a wireless LAN board to the PCMCIA socket, the wireless LAN board converting data received though the PCMCIA socket into packet data; sensing whether or not a wireless transmission board is connected to the wireless LAN board, the wireless transmission board modulating and demodulating the packet data of a specific frequency modulation range and to wirelessly send and receive data; and sending and receiving the packet data wirelessly via the wireless transmission board when the wireless LAN board and the wireless transmission board are connected.  
       [0023] According to a further aspect, the wireless LAN board includes a memory part to store data received through the PCMCIA socket, and further comprises storing the data in the memory part of the wireless LAN board when the wireless transmission board is not connected to the wireless LAN board; and reading the data stored in the memory part in response to a control of the main body, and transmits the read data to the main body.  
       [0024] According to an aspect, the method further comprises transmitting an interrupt signal to the main body through the PCMCIA socket when the wireless transmission board is connected to the wireless LAN board, so that the wireless LAN card operates in a wireless LAN card mode.  
       [0025] According to another aspect, the wireless transmission board includes an antenna; an RF processing part modulating packet data of a specific frequency modulation range; and a baseband processing part demodulating a high frequency signal directed by the antenna, and further comprises modulating the packet data transmitted from the wireless LAN board into a high frequency signal having a specific IF; and sending and receiving the high frequency signal through the antenna. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0026] These and/or other aspects and advantages of the present invention will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompany drawings of which:  
     [0027]FIG. 1 is a perspective view of a portable computer according to an embodiment of the present invention;  
     [0028]FIG. 2 is a block diagram showing a PCMCIA wireless LAN card of FIG. 1;  
     [0029] FIGS.  3 A- 3 B are block diagrams illustrating a circuit diagram of a second board sensing part of FIG. 2; and  
     [0030]FIG. 4 is a control flowchart of a wireless LAN card according to the present invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
     [0031] Reference will now be made in detail to the embodiment of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout. The embodiment is described below in order to explain the present invention by referring to the figures.  
     [0032]FIG. 1 is a perspective view of a portable computer according to an embodiment of the present invention. As shown therein, a portable computer  1  comprises a main body  3  mounted with a CPU (central processing unit), a PCMCIA controller  4  (refer to FIG. 2) connected to the CPU and controlling a PCMCIA type card, etc., and an LCD (liquid crystal display) part  2  combined with the main body  3  by a hinge. The main body is provided with an input unit such as a touch pad  7  and a keyboard  9 , and a bay  5  in which a wireless LAN card  10  and  20  is inserted. Inside the bay  5  a PCMCIA socket  6  (refer to FIG. 2) electrically connected to the PCMCIA controller  4  is provided.  
     [0033]FIG. 2 is a block diagram showing a PCMCIA wireless LAN card of FIG. 1, which is operable as a memory card. As shown therein, the PCMCIA wireless LAN card comprises a wireless sending/receiving part  20  or  30  sending and receiving a high frequency analog signal by wireless, and a wireless LAN board  10  transmitting data from the main body  3  to the wireless sending/receiving part  20  or  30  after converting data into packet data, and is operable as a memory to store the data. Further, the wireless sending/receiving parts  20  and  30  are different in a specification for a wireless LAN, and each of the wireless sending/receiving parts  20  and  30  is individually connected to the wireless LAN board  10 . Hereinbelow, the wireless LAN board  10  will be called a first board and the wireless sending/receiving part  20  or  30  will be called a second board. Further, the wireless sending/receiving part  20  or  30  will be representatively described as the second board.  
     [0034] The first board  10  includes a main body connection part  12  to be connected to the PCMCIA socket  6  of the main body  3 , a second board connection part  17  to which the second board  20  or  30  is connected, a memory part  11 , a second board sensing part  15  sensing whether or not the second board  20  or  30  is connected, and a controller  13 . When the second board  20  or  30  is sensed to be connected to the first board  10 , the controller  13  transmits data received through the main body connection part  12  to the second board  20  or  30  through the second board connection part  17  after dividing the data into packet data by buffering the data in the memory part  11 . When the second board  20  is sensed to not be connected to the first board  10 , the controller  13  controls the memory part  11  to store the data received through the main body  3 .  
     [0035] That is, the controller  13  includes a MAC controller  13   a  converting the data received from the PCMCIA socket  6  into the packet data (i.e., into a unit of data for a network) and controlling access to an external terminal when the second board  20  or  30  is connected to the first board  10 , and a memory controller  13   b  controlling the memory part  11  to store the data received from the main body connection part  12  when the second board  20  or  30  is not connected to the first board  10 , according to a sensing signal from the second board sensing part  15 .  
     [0036] Thus, the PCMCIA controller  4  of the main body  3  transmits the data to the first board  10 , and then the controller  13  converts the data of a bit stream into the data of a packet unit for the network, thereby transmitting the data of the packet unit to the second board  20  or  30 .  
     [0037] The second boards  20  and  30  are interchangeable and each is detachably combinable with the first board  10 . The second board  20  or  30  detachably combined with the first board  10  includes a respective antenna  25  or  35 , a respective baseband processing part  21  or  31  converting a high frequency analog signal directed by the respective antenna  25  or  35  into a low frequency analog signal by filtering an IF (intermediate frequency) signal, a respective A/D converter  22  or  32  converting an analog signal outputted from the respective baseband processing part  21  or  31  into a digital signal and converting a digital signal transmitted from the first board  10  into an analog signal, and a respective RF processing part  23  or  33  converting the signals outputted from the respective A/D converter  22  or  32  into the high frequency analog signal having a specific IF (immediate frequency) and transmitting the analog signal having a specific IF according to the respective second board  20  or  30  through the respective antenna  25  or  35 .  
     [0038] Further, the baseband processing parts  21  and  31  use different modulation operations selected according to the respective specifications, 802.11b and 802.11a. That is, a CCK modulation operation is selected for a 802.11b specification, and a OFDM modulation operation is selected for a 802.11a specification.  
     [0039] The RF processing parts  23  and  33  are different according to the respective specifications. That is, a 2.4 GHz RF processing part  23  is used in the 802.11b specification, and a 5 GHz RF processing part  33  is used in the 802.11a specification,  
     [0040] When the first board  10  and second board  20  or  30  are connected to the main body  3 , each component thereof is operated as follows. When the first board  10  is connected to the PCMCIA socket  6  of the main body  3 , a connection signal is generated and transmitted to the PCMCIA controller  4 . Further, the PCMCIA controller  4  initializes a register of the memory part  11  provided in the first board  10 . Thereafter, when the second board  20  is connected to the second board connection part  17  of the first board  10 , a sensing circuit of the second board sensing part  15  is connected to a preset voltage level (e.g., ground) of the second board  20 , so that a signal of a low level is generated and transmitted to the MAC controller  13   a  of the controller  13  provided in the first board  10 . Further, the MAC controller  13   a  outputs an interrupt signal to the PCMCIA controller  4  through the PCMCIA socket  6 . Thus, the PCMCIA controller  4  determines the first board  10  as the wireless LAN card based on the interrupt signal from the MAC controller  13   a , and transmits the data (to be wirelessly sent) to the controller  13 . The controller  13  divides the data received from the PCMCIA controller  4  into packets, and outputs the data packets to the second board  20  or  30  through the second board connection part  17 .  
     [0041] Further, the second board  20  or  30  modulates the data from the controller  13  of the first board  10  and sends the modulated data through the antenna  25  or  35 , and demodulates the high frequency analog signal directed by the antenna  25  or  35  and transmits the demodulated analog signal to the controller  13  of the first board  10 . Further, the controller  13  of the first board  10  converts the demodulated analog signal into digital data of a bit stream, and transmits the bit stream digital data to the main body  3  through the PCMCIA socket  6 .  
     [0042]FIGS. 3A and 3B are block diagrams illustrating a circuit diagram of the second board sensing part of FIG. 2. As shown in FIGS. 3A and 3B, the first board  10  includes a resistor  15   a , which is connected to an internal power line (not shown) of the first board  10 , used as the second board sensing part  15  generating a connection signal when the second board  20  or  30  is connected to the second board connection part  17 . The resistor  15   a  used as the second board sensing part  15  is connected to the preset voltage level (ground) of the second board  20  or  30  when the first board  10  and second board  20  or  30  are connected, and outputs the low level signal. When the first board  10  and second board  20  or  30  are not connected, the second board sensing part  15  outputs a signal of a high level. Thus, the controller  13  determines whether the first board  10  and second board  20  or  30  are connected based on the high level signal or the low level signal.  
     [0043]FIG. 4 is a control flowchart of a wireless LAN card which is usable as a memory card according to an embodiment of the present invention. As shown in FIG. 4, operations of the wireless LAN card will be described. At operation S 1 , there are provided the first board (wireless LAN board)  10  having the memory part  11  and the controller  13 , and the second board (wireless transmission board)  20  or  30  modulating and demodulating signals for wireless transmission. At operation S 3 , the first board  10  is connected to the main body  3 , and the CPU of the main body  3  determines the first board  10  as the memory card and outputs data to the first board  10 . At operation S 5 , the first board  10  stores the data from the main body  3  in the memory part  11 . Thereafter, at operation S 7 , the second board sensing part  15  determines whether or not the second board  20  or  30  is connected to the first board  10 . When the first board  10  and the second board  20  or  30  are connected, at operation S 9 , the controller  13  transmits the interrupt signal to the main body  3  so as to change a memory card mode into a wireless LAN card mode. At operation S 11 , the controller  13  of the first board  10  converts the data from the main body  3  into the packet data, and transmits the packet data to the second board  20  or  30 . At operation S 13 , the second board  20  or  30  modulates the packet data into the high frequency analog signal, and sends the modulated analog signal through the antenna  23  or  33 .  
     [0044] With this configuration, there is detachably provided the wireless LAN board and the wireless transmission board which correspond to the MAC controller (MAC layer) and the RF part (physical layer) of the PCMCIA wireless LAN card, respectively. Therefore, a user can interchange the wireless specification of the wireless LAN card between 802.11a and 802.11b by replacing the wireless transmission board (physical layer) of the 802.11a or 802.11b specification with another specification without replacing a whole wireless LAN card. Further, because only the RF part (physical layer) is changed without changing the MAC layer, the costs to change the wireless specification are relatively low to send and receive various IF signals through airwaves. Further, only boards corresponding to the physical layer having the RF processing part and the baseband processing part are manufactured according to frequency regulations of the respective nations separately from the MAC layer, thereby increasing a productive efficiency. Further, the wireless LAN board includes the memory part, so that the wireless LAN board is usable as the memory card.  
     [0045] As described above, a wireless LAN card and an operation of controlling the same is provided, in which the wireless LAN card is usable as a memory card and a wireless sending/receiving part thereof is easily replaceable for one of a desired specification.  
     [0046] Although an embodiment of the present invention has been shown and described, it will be appreciated by those skilled in the art that changes may be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.