Abstract:
Wireless terminals that are configured to communicate over a wireless local area network include a data processor and at least one MAC control unit that is responsive to the data processor that controls communications with an access point over first and second communications channels. The wireless terminals may further include a first interface between the at least one MAC control unit and the first communications channel and a second interface between the at least one MAC control unit and the second communications channel.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
   This application claims priority under 35 U.S.C. § 119 to Korean Patent Application No. 2003-26484, filed Apr. 25, 2003, the contents of which are incorporated herein in its entirety by reference. 
   FIELD OF THE INVENTION 
   The present invention relates to wireless communications terminals, and more particularly, to wireless communications terminals that support communications over separate wireless channels. 
   BACKGROUND OF THE INVENTION 
   A wireless LAN (local area network) system is one example of a general wireless communication system.  FIG. 1  is a schematic diagram illustrating an exemplary wireless LAN system that is suggested in IEEE 802.11. 
   As shown in  FIG. 1 , the wireless LAN system has, as a basic unit, a basic service set (BSS) 100. BSS 100 includes at least one wireless terminal or “station”  104  and an access point (AP)  102 . Two basic service sets (BSS-A, BSS-B) are depicted in  FIG. 1 . As shown in  FIG. 1 , the two basic service sets BSS-A and BSS-B may be connected with each other through a distribution system (DS)  110 . BSS-A and/or BSS-B may also be connected with the Internet or with other external processing servers through a wire network or a wireless network. 
   The above-described wireless LAN system may communicate in a 5 GHz band using orthogonal frequency division multiplexing (OFDM) as suggested as a standard in version “a” of the IEEE 802.11 standard (i.e., IEEE 802.11a). Alternatively, the wireless LAN system may communicate in a 2.4 GHz band using direct sequence spread spectrum (DSSS) as suggested as a standard in version “b” of the IEEE 802.11 (i.e., IEEE 802.11b). 
   As will be understood by persons of skill in the art, orthogonal frequency division multiplexing (OFDM) refers to multi carrier digital wave modulation multiple access technique that may support hundreds of carriers. OFDM may provide for increased transmission rates per unit bandwidth and may reduce or prevent multi-route interference. Each of the carriers is designed to have an orthogonal relationship to each of the other carriers. Since the orthogonal frequency division multiplexing (OFDM) can multiplex more carriers per unit bandwidth than can be multiplexed using a general frequency division multiplexing technique, OFDM systems can provide for increased transmission rates per unit bandwidth. 
   Direct sequence spread spectrum (DSSS) refers to a method in which pseudo-random noise sequences that are orthogonal with one another are added to an origin signal within a predetermined frequency bandwidth for transmission and reception. The transmitter and receiver share the pseudo-random noise sequences such that data transmission and reception for a plurality of users can be made over a single channel. 
   Wireless LAN systems may be configured to support both the orthogonal frequency division multiplexing technique of IEEE 802.11a and the direct sequence spread spectrum technique of IEEE 802.11b. To facilitate this, a network interface card for the physical interface to the wireless LAN has been developed that supports dual mode IEEE 802.11a/b or tri-mode IEEE 802.11a/b/g. 
     FIG. 2  is a block diagram depicting a conventional wireless communication system for transmitting and receiving data between one of the wireless terminals and an access point in the wireless LAN system of  FIG. 1 . As shown in  FIG. 2 , the wireless communication system transmits and receives data using a single wireless channel  206  between the access point  202  and the wireless terminal  204 . 
     FIG. 3  is a block diagram of the access point  202  and the wireless terminal  204  in the wireless communication system of  FIG. 2 . As described previously, the access point  202  is a device that is used to interface the wireless terminals to an external communication network such as, for example, the Internet, a satellite broadcasting network or a cable network. Thus, the access point  202  allows the user of the wireless terminal  204  to access services provided on an external network such as the Internet or games. Further, in a special case, the access point  202  can use data stored within the access point  202  to provide one or more services to users without interfacing with an external network. This is called an ad-hoc mode in the wireless LAN. In the ad hoc mode, the access point  202  not only interfaces the wireless terminal  204  to an external service network, but it also can construct a data service network in itself. 
     FIG. 4  is a flowchart illustrating a procedure for data transmission and reception between the access point  202  and the wireless terminal  204  of  FIG. 3 . In the example of  FIG. 4 , the data flow illustrated is the date flow associated with a user that is watching a bi-directional high definition television set (HD-TV) while sending an e-mail through the Internet by using the access point  202  and the wireless terminal  204 . As shown in  FIG. 4 , the access point  202  transmits broadcasting data  401  from a broadcasting server (not shown in  FIG. 4 ) to the wireless terminal  204 . The wireless terminal  204  may also transmit response signals (ACK) to the broadcasting data  401  and/or broadcasting control signals (volume, channel, etc.) to the access point  202 . The wireless terminal  204  also transmits mail data  412  that is generated by the user of the wireless terminal  204  to a mail server (not shown in  FIG. 4 ) through the access point  202 . A response signal to the mail data  412  may also be transmitted from the access point  202  to the wireless terminal  204 . 
   In the example of  FIG. 4 , the data processor  318  resident at the wireless terminal  204  (see  FIG. 3 ) may perform multiple different applications simultaneously such as transmission of the mail data  412  and display of the HD-TV signal  411  using the broadcasting data  401  received from the access point  202 . The data processor  318  also performs protocols  413  and  414  for execution and transmission of the corresponding applications  411  and  412 . The protocols performed in the wireless LAN system are exemplified as a resource reservation protocol (RSVP) for reserving/securing the band needed for the communication, and a transmission control protocol/Internet protocol (TCP/IP) for performing routing functions on the Internet. 
   The MAC control unit  314  on the wireless terminal  204  (see  FIG. 3 ), through a wireless channel interface unit  312 , checks the state of the wireless channel  206  for communication. If the wireless channel  206  is available, the interface unit  312  occupies the channel  206 . Once the channel  206  is occupied, the wireless channel interface unit  312  transmits  417  data (e.g., mail, response signals, control signals, etc.) from the data processor  318  to the access point  202  over the wireless channel  206 , and receives  418  data (broadcasting data, response signals, etc.) from the access point  202  and forwards this received data to the data processor  318  via the MAC control unit  314 . For this data transmission and reception, the wireless channel interface unit  312  includes a transmitter for transmission and a receiver for reception. 
   In the example of  FIG. 4 , the data processor  302  resident at the access point  202  (see  FIG. 3 ) likewise performs multiple different applications. In particular, the data processor  302  interfaces with external servers such as a broadcasting server and a mail server to transmit the broadcasting data  401  from the broadcasting server to the wireless terminal  204  and to forward mail data  402  from the wireless terminal  204  to the mail server. The data processor  302  also performs protocols  403  and  404  for execution and transmission of the corresponding applications  401  and  402 , where protocol  403  is a resource reservation protocol and protocol  404  is a TCP/IP protocol. 
   The MAC control unit  306  of the access point  202 , via the wireless channel interface unit  308 , checks the state of the wireless channel  206  for communications and occupies the channel  206 . Once the channel  206  is occupied, the wireless channel interface unit  308  transmits the broadcasting data  401  from the data processor  302  to the wireless terminal  204  over the wireless channel  206 , or receives data  402  from the wireless terminal  204  and forwards the received data  402  to the data processor  302  via the MAC control unit  306 . The wireless channel interface unit  308  of the access point  202  also includes a transmitter and a receiver for data transmission and reception. 
   When only a single wireless channel  206  is provided, a conventional wireless communication system cannot transmit data from the access point  202  to the wireless terminal  204  while simultaneously transmitting data from the wireless terminal  204  to the access point  202 . 
     FIG. 5  depicts a frame of data that may be transmitted and received through the wireless channel  206  as part of the data flow illustrated in  FIG. 4 . As shown in  FIG. 5 , data that is transmitted and received for each of the applications is intermixed over one channel for transmission and reception. 
   SUMMARY OF THE INVENTION 
   Embodiments of the present invention provide wireless terminals that are configured to communicate over a wireless local area network. The wireless terminals may include a data processor and at least one control unit that is responsive to the data processor. The control unit may control communications between the wireless terminal and an access point over a first communications channel and a second, full-duplex, communications channel. The wireless terminal may further include a first interface between the control unit(s) and the first communications channel and a second interface between the control unit(s) and the second communications channel. The control units may comprise MAC control units. 
   The wireless terminal may also include a traffic control unit that is responsive to the data processor. The traffic control unit may be used to form the data transmission route for data associated with applications running on the wireless terminal. The MAC control unit(s) may be implemented as a first MAC control unit that controls communications with the access point over the first communications channel and a second MAC control unit that controls communications with the access point over the second communications channel. The traffic control unit may be implemented as part of one or more of the MAC control units. 
   In further embodiments of the present invention, the first communications channel is implemented as an orthogonal frequency division multiplexing channel and the second communications channel is implemented as a direct sequence spread spectrum communications channel. The first channel may be implemented as a uni-directional channel that only carries data from the access point to the wireless terminal or as a bi-directional communications channel. Data associated with a first application running on the wireless terminal may be transmitted to the wireless terminal over the first communications channel, and at least some of the control signals associated with the first application may transmitted from the wireless terminal to the access point over the second communications channel. The wireless local area network may operate, at least in part, under the IEEE 802.11 standard, and the first communications channel and the second communications channel may be implemented in different frequency bands. 
   Pursuant to further embodiments of the present invention, wireless communications systems are provided that include a wireless terminal that transmits and receives data associated with first and second applications that are running on the wireless terminal. The systems further include an access point that serves as an interface between the wireless terminal and one or more processing servers that are located on external network(s). Data associated with the first application may be transmitted between the wireless terminal and the access point over the first communications channel, and data associated with the second application may be transmitted between the wireless terminal and the access point over the second communications channel. The second communications channel may also be used to transmit control information associated with the first application. 
   Pursuant to additional embodiments of the present invention, methods for simultaneously supporting at least two applications on a wireless terminal are provided. Pursuant to these methods, data associated with a first application may be received at the wireless terminal over a first communications channel between the wireless terminal and the access point. A transmission path between the wireless terminal and the access point over a second communications channel may also be established for application data associated with a second application. The application data associated with the second application may then be transmitted over the second communications channel via the transmission path. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a schematic view illustrating an IEEE 802.11 wireless LAN system. 
       FIG. 2  is a block diagram depicting a conventional wireless communication system for transmitting and receiving data between a wireless terminal and an access point via a single wireless channel using the wireless LAN system of  FIG. 1 . 
       FIG. 3  is a block diagram of an access point and a wireless terminal in the wireless communication system of  FIG. 2 . 
       FIG. 4  is a flow chart illustrating a procedure for data transmission and reception between the access point and the wireless terminal of  FIG. 3 . 
       FIG. 5  depicts a frame of data that may be transmitted and received through a wireless channel as part of the data flow illustrated in  FIG. 4 . 
       FIG. 6  is a block diagram depicting a wireless communication system for transmitting and receiving data using two separate wireless channels according to embodiments of the present invention. 
       FIG. 7  is a block diagram of an access point and a wireless terminal that may be used in a wireless communication system of  FIG. 6  according to embodiments of the present invention. 
       FIG. 8  is a flow chart illustrating a procedure for data transmission and reception between the access point and the wireless terminal of  FIG. 7 . 
       FIGS. 9A and 9B  depict frames of data that may be transmitted and received by each respective wireless channel in the procedure of  FIG. 8 . 
       FIG. 10  is a block diagram illustrating an access point and a wireless channel according to further embodiments of the present invention. 
       FIG. 11  is a flow chart illustrating a procedure for data transmission and reception between the access point and the wireless terminal of  FIG. 10 . 
       FIG. 12  is a block diagram illustrating a wireless communications system according to still further embodiments of the present invention. 
       FIG. 13  is a flow chart illustrating a procedure for data transmission and reception between access point and the wireless terminal of  FIG. 12 . 
       FIGS. 14A and 14B  depict frames of data that may be transmitted and received by each respective wireless channel in the procedure of  FIG. 13 . 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   The present invention will now be described more fully with reference to the accompanying drawings, in which embodiments of the invention are shown. This invention, however, may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like reference numerals refer to like elements throughout. 
   In embodiments the present invention, a plurality of separate wireless channels are used in one wireless communication system such that one channel group among the plurality of channels is used for a download channel and another channel group is used for an upload channel. Herein, “download” and “upload” are used to specify the direction in which data is transmitted, where the download channel refers to a channel that is used primarily with respect to data flow from the access point to the wireless terminal, and the upload channel refers to a channel that is used primarily with respect to data flow from the wireless terminal to the access point. As is made clear herein, the download channel may comprise a full duplex channel that, in addition to carrying data from the access point to the wireless terminal, may also carry other data or control signals such as, for example, control signals or responses associated with the data flow that are transmitted from the wireless terminal to the access point. Similarly, the upload channel may comprise a full duplex channel that, in addition to carrying data from the wireless terminal to the access point, may also carry other data or control signals such as, for example, control signals or responses associated with the data flow that are transmitted from the access point to the wireless terminal. Additionally, as discussed herein, in embodiments of the present invention, one of the upload channel or the download channel may comprise a half-duplex channel while the other comprises a full-duplex channel, and control signals and responses associated with the data carried on the half-duplex channel may be carried on the full-duplex channel. 
   Hereinafter, embodiments of the present invention are described in which the wireless communication systems have two wireless channels. It will be appreciated, however, that the methods and systems of the present invention may also be applied to wireless communication systems having more than two wireless channels. Additionally, it will also be understood that when a device or element is referred to as being “coupled” or “connected” to a second device or element, it can be directly coupled or connected to the second device or element or, alternatively, intervening devices, elements and/or connections may also be present. In contrast, when a device or element is referred to as being “directly connected” to a second device or element, there are no intervening devices, elements and/or connections present. 
     FIG. 6  is a block diagram depicting a wireless communication system for transmitting and receiving data over two separate wireless channels according to embodiments of the present invention. As shown in  FIG. 6 , the wireless communication system includes an access point  602 , a wireless terminal  604 , a download channel  606  and an upload channel  608 . The download channel  606  and the upload channel  608  are separate from each other, allowing for simultaneous data transmission and reception over both channels. 
     FIG. 7  is a block diagram of the access point  602  and the wireless terminal  604  used in the wireless communication system of  FIG. 6 . As shown in  FIG. 7 , the wireless terminal  604  includes a data processor  725  that performs protocols (RSVP, TCP/IP, etc.) used in the execution of applications and/or in the transmission and reception of application data. The wireless terminal  604  further includes a traffic control unit  724  that forms a data transmission route for each of the applications and that controls the transmission and reception of data therefore. The wireless terminal  604  further includes MAC control units  722  and  723  that check the channel state for each of the wireless channels  606  and  608  and control channel occupation. Finally, the wireless terminal  604  includes a download channel interface unit  720  for transmitting and receiving data through an interface with the download channel  606 , and a upload channel interface unit  721  for transmitting and receiving data through an interface with the upload channel  608 . The download channel interface unit  720  and the upload channel interface unit  721  may each include a transmitter and a receiver for data transmission and reception. 
   As is also shown in  FIG. 7 , the access point  602  includes a data processor  710  and a traffic control unit  711 . The data processor  710  interfaces with one or more external processing servers  600 . The data processor  710 , for example, may forward data from the external processing server(s)  600  to the wireless terminal  604  and/or transmit data received from the wireless terminal to the external processing server(s)  600 . The traffic control unit  724  may form a data transmission route for each of the applications and may control the transmission and reception of data therefore. 
   The access point  602  may further include MAC control units  712 ,  713  that check the channel state for each of the wireless channels  606  and  608  and control channel operation. Finally, the access point  602  includes a download channel interface unit  714  for transmitting and/or receiving data through an interface with download channel  606 , and an upload channel interface unit  715  for transmitting and receiving data through an interface with the upload channel  608 . The download channel interface unit  714  and the upload channel interface unit  715  may each include a transmitter and a receiver for data transmission and reception. 
     FIG. 8  is a flowchart illustrating a procedure for data transmission and reception between the access point  602  and the wireless terminal  604  of  FIG. 7 . In the example of  FIG. 8 , the data flow is depicted for the case in which the user of the wireless terminal  604  watches HD-TV while transmitting an e-mail through the Internet. 
   As shown in  FIGS. 7 and 8 , broadcasting data  801  received from the broadcasting server is transmitted to the traffic control unit  711  through the data processor  710  of the access point  602 . The traffic control unit  711  forms a route (block  805  of  FIG. 8 ) for transmission of the broadcasting data  801 . The broadcasting data  801  is transmitted (see block  808  of  FIG. 8 ) through the MAC control unit  712  and the download channel interface unit  714  over the download channel  606 . The MAC control unit  712  checks the state of the download channel  606  through the download channel interface unit  714 , and if the download channel  606  is in an idle state, the download channel  606  is occupied and used to transmit the broadcasting data  801  to the wireless terminal  604 . If the channel is in a busy state, transmission is delayed until the channel returns to an idle state. 
   The broadcasting data  801  transmitted to the wireless terminal  604  from the access point  602  over the download channel  606  as described above is received through the download channel interface unit  720  of the wireless terminal  604 . The data is then transmitted to the data processor  725  of the wireless terminal  604  via the MAC control unit  722  and the traffic control unit  724 . The data processor  725  uses the received broadcasting data  801  so as to perform the application such as the HD-TV  821 . The data processor  725  may also transmit (see block  828  of  FIG. 8 ) to the access point  602  a response signal to the received broadcasting data  801  using the same route. Alternatively, broadcasting control signals may also be transmitted to the access point  602  using the upload channel  608 , which might, for example, be used to transmit a volume control signal, a broadcasting channel retrieval signal or other signals that do not necessarily require a high throughput connection. 
   If the user of the wireless terminal  604  executes the mail data application  822  or another application that can be transmitted on a lower throughput connection, the data associated with the application may be switched (see block  825  of  FIG. 8 ) via the data processor  725  and the traffic control until  724  of the wireless terminal  604  through the MAC control unit  723  and the upload channel interface unit  721  to the upload channel  608 . To accomplish this, the MAC control unit  723  may check the state of the upload channel  608  through the upload channel interface unit  721 . If the upload channel  608  is in the idle state, the channel  608  is occupied to transmit the mail data  822  to the access point  602  over the upload channel  608 . 
   The mail data  822  transmitted from the wireless terminal  604  to the access point  602  over the upload channel  608  as described above is received (see block  811  of  FIG. 8 ) through the upload channel interface unit  715  of the access point  602 , and then is transmitted to the data processor  710  of the access point  602  via the MAC control unit  713  and the traffic control unit  711 . The data processor  710  of the access point  602  may transmit the received mail data  822  to a mail server through an Internet interface  802 . 
     FIGS. 9A and 9B  depict frames of data that may be transmitted and received by each of the respective wireless channels in the procedure of  FIG. 8 .  FIG. 9A  depicts a frame of data that may be transmitted and received through the download channel  606  in the embodiment of  FIGS. 7 and 8 .  FIG. 9B  depicts a frame of data that may be transmitted and received through the upload channel  608  in the embodiment of  FIGS. 7 and 8 . 
   As shown in  FIGS. 9A and 9B , the broadcasting data is consecutively transmitted and received over the download channel  606 , while the mail data is consecutively transmitted and received over the upload channel  608 . Since the download channel  606  and the upload channel  608  are separate channels that operate independently, the data can be transmitted simultaneously. Accordingly, a much higher QoS of transmission data may be secured as compared to the case where a single channel is used. 
   In embodiments of the present invention, the download channel  606  and the upload channel  608  may use different communication protocols. For example, the download channel  606  which is used to transmit and receive high data rate data such as the broadcasting data may comprise an IEEE 802.11 a/g orthogonal frequency division multiplexing channel, while the upload channel  608  that is used to transmit and receive lower data rate data such as the mail data may use an IEEE 802.11b direct sequence spread spectrum channel. 
     FIG. 10  illustrates an access point  602 - 1  and a wireless terminal  604 - 1  according to further embodiments of the present invention in which the traffic control unit and the MAC control units are implemented as a single unit.  FIG. 11  illustrates a procedure for data transmission and reception between the access point and the wireless terminal of  FIG. 10 . 
   As shown in  FIGS. 10 and 11 , the operation and data flow of the embodiments of the present invention depicted in  FIGS. 10 and 11  is the same as the operation and data flow of the embodiments of  FIGS. 7 and 8 , while the access point  602 - 1  and the wireless terminal  604 - 1  have simpler structure in light of the use of combined traffic/MAC control units  1004  and  1024 . 
     FIG. 12  is a block diagram illustrating a system according to embodiments of the present invention in which the download channel  606  only supports communications from the access point to the wireless terminal.  FIG. 13  is a flowchart that illustrates a procedure for data transmission and reception between the access point and the wireless terminal in the embodiment of  FIG. 12 . 
   In the wireless communication system as shown in  FIG. 12 , the download channel  606  only supports communications from the access point  602 - 2  to the wireless terminal  604 - 2 . Since the download channel interface unit  714 - 1  of the access point  602 - 2  performs only the transmission function, it can be embodied as a stand-alone transmitter. Likewise, since the download channel interface unit  720 - 1  of the wireless terminal  604 - 2  performs only the reception function, it can be embodied only as a stand-alone receiver. In the embodiments of the present invention depicted in  FIGS. 12 and 13 , the response signal to the received broadcasting data and the broadcasting control signals may be transmitted over the upload channel  608 . 
   The system operation in the embodiment of  FIG. 12  is similar to operation of the system depicted in  FIG. 7 , but the traffic/MAC control units  1004  and  1024  operate in a different fashion. Referring to  FIGS. 12 and 13 , the traffic/MAC control unit  1024  of the wireless terminal  604 - 2  controls the transmission and reception of the mail data over the upload channel  608 . The traffic/MAC control unit  1024  loads up received data on the TCP/IP block  1214  of the data processor  725  and loads down data to be transmitted to the upload channel interface unit  721 . The broadcasting data received over the download channel is also loaded-up on the TCP/IP block  1214 , and the response signal thereto and/or the broadcasting control signals are transmitted to the access point  602 - 2  through the upload channel interface unit  721 . 
   The operation of the access point  602 - 2  is the same as in the above-described wireless terminal  604 - 2  except that only the transmission  1206  (and not reception) is enabled in the download channel interface unit  714 - 1 . 
     FIG. 14A  depicts a frame of data that may be transmitted from the access point  602 - 2  to the wireless terminal  604 - 2  over the download channel  606  in the embodiment of  FIG. 12 .  FIG. 14B  depicts a frame of data that may be transmitted and received between the access point  602 - 2  and the wireless terminal  604 - 2  over the upload channel  608 . As shown in  FIG. 14A , only the broadcasting data is transmitted over the download channel  606 . The transmission and reception of the mail data, the response signals (ACK) and the broadcasting control signals is performed over the upload channel  608 . 
   While this invention has been particularly shown and described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims and equivalents.