Abstract:
The communication performance between an access point and a station is improved by automatically setting up a free channel not used for communication. This invention relates to a wireless LAN access point including means for searching for a wireless LAN channel not in use, and means for setting up as a communication channel the wireless LAN channel not in use that is found by the search by the search means.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
         [0001]    This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2001-304573, filed Sep. 28, 2001, the entire contents of which are incorporated herein by reference.  
         BACKGROUND OF THE INVENTION  
         [0002]    1. Field of the Invention  
           [0003]    The present invention relates to a wireless LAN access point having a function of automatically setting up its own channel from free channels by recognizing channels in use for wireless communication.  
           [0004]    2. Description of the Related Art  
           [0005]    Recently, a wireless network environment is becoming popular with the development of the wireless communication technology. As a technique which replaces a conventional wire LAN, wireless LANs based on IEEE 802.11b and the like are pervading.  
           [0006]    The IEEE 802.11b standard executes wireless communication using a 2.4-GHz band called an ISM (Industrial Scientific Medical) band, and adopts DSSS (Direct Sequence Spread Spectrum) as a transmission/reception signal modulation method.  
           [0007]    A wireless base station called an access point having wireless and wire LAN interfaces is often used to maintain connection compatibility between a wireless LAN terminal having an IEEE 802.11b wireless communication function and a device connected to a wired LAN terminal.  
           [0008]    This access point functions as a bridge between the wireless LAN terminal and the wired LAN terminal so as to allow them to exchange data. In some cases, wireless communication is possible via an access point called an infrastructure mode when communication is made with another wireless LAN terminal.  
           [0009]    In communication between wireless communication devices, the 2.4-GHz band (2.4000 to 2.4835 GHz) is split into 14 channels in practical use (channels that can be used are limited in some countries). This communication channel must be set up to use an identical channel between devices which make wireless communication.  
           [0010]    The access point has an interface for the setups of a wireless LAN including group identification information (to be referred to as an ID hereinafter) between the access point and the station, and a wireless communication channel (to be referred to as a channel hereinafter). An ID and channel used for communication must be set up in advance.  
           [0011]    The setups of the access point change depending on the device, but are generally done from terminal software, a dedicated tool, or a Web browser which uses a network interface.  
           [0012]    If the station makes communication via the access point, it is set to an infrastructure mode. While changing the wireless LAN channel, the station receives a signal (to be referred to as a beacon hereinafter) which is periodically transmitted by the access point. The station transmits a connection request including ID information to the access point of a channel from which the station has received the beacon.  
           [0013]    Having received the connection request, the access point determines “connection enable” as far as the ID included in the connection request is the same as an ID set at the access point. Then, the access point sends back a connection response to establish communication between the access point and the station.  
           [0014]    In the conventional wireless LAN access point described above, setups must be manually done from a browser or setup tool. In general, the wireless LAN access point is used as a bridge function for connection to a wire LAN network at office or home, so that the installation location is fixed. Once the access point is installed, access point setup values including a wireless LAN channel need not be frequently changed.  
           [0015]    If the user carries the wireless LAN access point and the wireless LAN access point function is incorporated in, e.g., a docking station (to be referred to as a docker hereinafter) used in combination with a wireless LAN notebook type personal computer (to be referred to as a wireless LAN notebook type PC hereinafter), the user must carry and use both the access point and station.  
           [0016]    In this case, wireless communication between the docker serving as an access point and the wireless LAN notebook type PC serving as a station depends on the environment at the current location of the wireless device on the move. If the channel of the wireless device contends with that of another wireless device on the move, the communication performance using the channel degrades.  
           [0017]    For example, when the wireless device is connected to a wire LAN at office as a destination by using the network interface of the docker, a channel used by the access point function of the docker must be set up. However, it is difficult to immediately recognize which channel is an optimal one. In general, the user asks a network manager about a channel used by the wireless access point of the office, or manually changes the setups to a channel which seems to be free. This is a cumbersome operation.  
         BRIEF SUMMARY OF THE INVENTION  
         [0018]    The present invention has been made in consideration of the above situation, and has as its object to provide a wireless communication device capable of avoiding communication channel collision with another wireless device, and which can improve the communication performance between the access point and the station.  
           [0019]    To achieve the above object, according to a first aspect of the invention, there is provided a wireless communication device which performs wireless communication by using one of wireless channels obtained by splitting a predetermined frequency band into a plurality of wireless channels, comprising: means for modulating and demodulating data for performing wireless communication; means for detecting a usable wireless channel out of the plurality of wireless channels; and means for setting up the wireless channel detected by the detection means as a communication channel for wireless communication performed via the wireless communication means.  
           [0020]    According to a second aspect of the invention, there is provided a communication channel setup method at a wireless LAN access point, comprising: determining whether a beacon from another wireless LAN access point has been received in a wireless LAN channel; determining whether the wireless LAN channel is a final channel when a beacon has been received; and returning to the step of determining whether a beacon has been received when the wireless LAN channel is not determined as a final channel.  
           [0021]    This wireless LAN access point can automatically set up a free channel not used for communication as a communication channel, and can improve the communication performance between the access point and the station.  
           [0022]    Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter. 
       
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING  
       [0023]    The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the invention, and together with the general description given above and the detailed description of the embodiments given below, serve to explain the principles of the invention.  
         [0024]    [0024]FIG. 1 is a block diagram showing a wireless LAN access point according to an embodiment of the present invention;  
         [0025]    [0025]FIG. 2 is a flow chart for explaining the operation of the wireless LAN access point;  
         [0026]    [0026]FIG. 3 is a view showing a state in which a notebook type personal computer as a wireless LAN terminal is connected to a docking station (docker);  
         [0027]    [0027]FIG. 4 is a view showing a state in which the notebook type personal computer is disconnected from the docking station (docker); and  
         [0028]    [0028]FIG. 5 is a block diagram showing the arrangement of the notebook type personal computer and docking station. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0029]    A wireless LAN access point according to an embodiment of the present invention will be described below with reference to the several views of the accompanying drawing.  
         [0030]    [0030]FIG. 1 is a block diagram showing a wireless LAN access point according to the embodiment of the present invention.  
         [0031]    As shown in FIG. 1, a wireless LAN access point  10  according to the embodiment of the present invention comprises a CPU  11 , RAM  12 , flash ROM  13 , switch  14 , network controller  15 , wireless LAN controller  16 , and antenna  17 .  
         [0032]    The CPU  11  reads a control program loaded onto the RAM  12 , and controls the network controller  15  and the wireless LAN controller.  
         [0033]    The RAM  12  stores a program for controlling the operation of the CPU  11 , or is used as a temporary storage area for communication packets exchanged between the network controller  15  and the wireless LAN controller  16 .  
         [0034]    The flash ROM  13  saves a control program loaded onto the RAM  12  and the system setup values of the access point.  
         [0035]    The switch  14  is used to designate the scan start of a free wireless channel upon reception of a user instruction.  
         [0036]    The network controller  15  controls exchange of communication packets between a wired network and the device of the network controller  15 . For example, the network controller  15  is an Ethernet controller.  
         [0037]    The wireless LAN controller  16  controls picketing, modulation/demodulation, and encryption of data exchanged between the wireless communication device and the device of the wireless LAN controller  16 .  
         [0038]    The antenna  17  is used to receive/transmit data from/to the wireless LAN controller.  
         [0039]    The operation of the wireless LAN access point according to the embodiment of the present invention will be explained with reference to the flow chart of FIG. 2.  
         [0040]    After the wireless LAN access point is activated, the CPU  11  loads a control program from the flash ROM  13  onto the RAM  12 , and starts execution of the program.  
         [0041]    The network controller  15  and wireless LAN controller  16  are initialized. Then, their device is initialized by reading out the setup values of the system stored in the flash ROM  13  in advance. If the switch  14  is pressed, a wireless channel is automatically set up subsequent to initialization.  
         [0042]    In step S 1 , wireless communication starts while the access point  10  is used as a station mode similar to a wireless LAN terminal. In step S 1 , the access point  10  operates not as a wireless access point but a wireless LAN terminal (station) in order to detect another wireless access point or wireless communication terminal.  
         [0043]    In step S 2 , the wireless channel used for communication as the station mode is set to a default channel value. IEEE 802.11b will be exemplified herein. In Japan, the 2.4-GHz band is split into 14 channels in practical use. The band occupied by each channel is ±11 MHz from the center frequency of each channel, i.e., 22 MHz. In this case, the first channel out of the 14 channels is set up, and “1” is set at a wireless LAN channel counter.  
         [0044]    In step S 3 , the access point  10  starts operating as a wireless station and waits to receive a beacon transmitted from peripheral wireless access points.  
         [0045]    In step S 4 , whether the access point  10  has received a beacon in the wireless channel currently set as the station mode is checked. If the access point  10  has received a beacon (YES in step S 4 ), the wireless channel currently set at the access point  10  is determined to be in use by another access point or wireless communication device within the radio receiving range, and the flow shifts to step S 5 .  
         [0046]    In step S 5 , whether a channel not set yet among usable wireless channels exists except for the current channel is checked. If a channel not set yet exists (NO in step S 5 ), the flow advances to step S 6 . In step S 6 , the wireless channel is set to the next channel number (adjacent channel in frequency), and the wireless LAN counter is incremented by one. Then, the flow returns to S 4 , and beacon acquisition by the newly set wireless channel is checked.  
         [0047]    If no beacon is received by the current channel in step S 4  (NO in step S 4 ), it is determined that a device which is performing wireless communication using the currently set wireless channel does not exist around, and the flow shifts to step S 7 .  
         [0048]    In step S 7 , the detected free channel is defined as the set channel of the access point. In step S 9 , beacon reception of the wireless access point serving as the station mode ends.  
         [0049]    In step S 10 , the device is changed to an access point mode in which the device operates as an access point. In step S 11 , the operation of the wireless access point starts by using the channel set in step S 7 .  
         [0050]    If the current channel is the final channel among usable wireless channels (YES in step S 5 ), the flow advances to step S 8 . In step S 8 , the set channel saved in the flash ROM  13  is defined as the set channel of the access point.  
         [0051]    In step S 9 , beacon reception of the wireless access point serving as the station mode ends. In step S 10 , the device is changed to a mode in which the device operates as an access point. In step S 11 , the operation of the wireless LAN access point starts by using the channel set in step S 7 .  
         [0052]    Automatic setup processing of a wireless channel is done after initialization in this embodiment, but the present invention is not limited to this. For example, when another wireless device enters the currently used channel, automatic setup processing of a wireless channel is executed again to move the communication channel to a free channel and optimize communication.  
         [0053]    &lt;Another Embodiment&gt; 
         [0054]    A wireless LAN access point according to another embodiment of the present invention will be described. The wireless LAN access point of this embodiment is incorporated in a docking station detachably connected to a notebook type personal computer.  
         [0055]    [0055]FIG. 3 is a view showing a state in which the notebook type personal computer as a wireless LAN terminal is connected to the docking station (docker). FIG. 4 is a view showing a state in which the notebook type personal computer is disconnected from the docking station (docker).  
         [0056]    In FIGS. 3 and 4, reference numeral  21  denotes a notebook type personal computer as a wireless LAN terminal; and  22 , a docking station (docker) which incorporates a wireless LAN access point according to the embodiment.  
         [0057]    The docking station  22  has a CD-ROM drive  23 , an Ethernet connector  24  for connecting a wired network such as an Ethernet, and a switch  25  for allowing the user to retry search for a free channel.  
         [0058]    The docking station  22  is connected to a network hub  26  via an Ethernet cable  27  connected to the Ethernet connector  24 . In addition to the docking station, the network hub  26  is connected to a network at office or a home LAN.  
         [0059]    When the notebook type personal computer  21  and docking station  22  are not connected, as shown in FIG. 4, they perform wireless communication.  
         [0060]    At this time, the wireless LAN access point determines a communication channel used for communication with the notebook type personal computer  21  by executing the operation explained with reference to FIG. 2.  
         [0061]    [0061]FIG. 5 is a block diagram showing the arrangement of the notebook type personal computer  21  and docking station  22 . In FIGS. 1, 4, and  5 , the same reference numerals denote the same parts, and a description thereof will be omitted.  
         [0062]    As for the docking station  22 , a CPU  11  is connected to a CD-ROM drive  32  via an IDE (Intelligent Drive Electronics) controller  31 , in addition to the access point arrangement shown in FIG. 1. The IDE controller  31  controls data transfer of the CD-ROM drive  32 . Data on a CD-ROM that is stored in the CD-ROM drive  32  is accessible by the notebook type personal computer  21 .  
         [0063]    More specifically, the notebook type personal computer  21  accesses the CD-ROM drive  32  by communication via interfaces  41  and  33  when the notebook type personal computer  21  and docking station  22  are connected, or by wireless communication using wireless LAN controllers  44  and  16  when they are not connected. Wireless communication between the notebook type personal computer  21  and the docking station  22  uses a wireless channel determined by the docking station  22  by executing the processing of the flow chart shown in FIG. 2.  
         [0064]    The CD-ROM drive  32  can be accessed not only by the notebook type personal computer  21  but also by an information device such as another notebook type personal computer which performs communication using the same communication channel. In this case, the CD-ROM drive  32  of the docking station  22  is used as a shared resource within the wireless network.  
         [0065]    The docking station  22  comprises the interface  33  for connecting the notebook type personal computer  21 . The docking station  22  communicates with the notebook type personal computer  21  via the interface  33 .  
         [0066]    The notebook type personal computer  21  has the interface  41 , a CPU  42 , a RAM  43 , the wireless LAN controller  44 , an antenna  45 , a hard disk controller (HDC)  46 , and a hard disk drive (HDD)  47 .  
         [0067]    The interface  41  is detachably connected to the interface  33  of the docking station  22 . The notebook type personal computer  21  communicates with the docking station  22  via the interface  41 .  
         [0068]    The CPU  42  controls the entire notebook type personal computer, and controls wireless communication with the docking station  22 . The RAM  43  is used as a work area of the notebook type personal computer  21 .  
         [0069]    The wireless LAN controller  44  controls wireless communication with the docking station  22  via the antenna  45 . The hard disk controller  46  controls write/read with respect to the hard disk drive  47 .  
         [0070]    This embodiment enables connecting the notebook type personal computer  21  to a wire LAN network via the docking station  22  by using a communication channel determined by the docking station  22 .  
         [0071]    The above-described embodiment has exemplified a CD-ROM drive as a storage device incorporated in the docking station. However, the storage device is not limited to this, and may be a DVD-RAM or HDD.  
         [0072]    The wireless LAN access point of the embodiment can automatically set up a free channel not in use for communication. Communication channel collision with another wireless device can be avoided, and the communication performance between the access point and the station can be improved.  
         [0073]    Incorporating a wireless LAN access point according to the embodiments of the present invention in the docking station can optimize the setups of a communication channel at a wireless LAN access point which is frequently moved.  
         [0074]    The present invention is not limited to the above-described embodiments, and can be variously modified without departing from the spirit and scope of the invention in practical use.  
         [0075]    As has been described above, the present invention can provide a wireless LAN point which recognizes a wireless channel in use at a destination, and automatically sets up a free channel not in use for communication as a communication channel, thus avoiding communication channel collision with another wireless device, and which can improve the communication performance between the access point and the station.  
         [0076]    Additional advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described herein. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.