Abstract:
A technique is disclosed that enables both an IEEE 802.11 transceiver and a Bluetooth transceiver to be employed in a single wireless telecommunication station (e.g., a device supporting a wireless telephone, personal digital assistant, etc.) without interfering on each other. In particular, the illustrative embodiment enables standard “off-the-shelf” IEEE 802.11 and Bluetooth transceivers to work in a coordinated fashion in a single telecommunications terminal. In the illustrative embodiment, an IEEE 802.11 transceiver that uses a shared-communications channel notifies a Bluetooth transceiver that a transmit opportunity exists and that the Bluetooth transceiver has permission to use the shared-communications channel. The technique disclosed is also applicable to communications protocols other than IEEE 802.11 and Bluetooth.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of: 
     1. U.S. provisional application Ser. No. 60/452,310, filed 5 Mar. 2003, entitled “Blue802 Advanced Notification of Idle Time”, which is also incorporated by reference. 
     The following patent applications are incorporated by reference: 
     1. U.S. patent application Ser. No. 10/444,383, filed May 23, 2003, entitled “Multi-Protocol Interchip Interface”, 
     2. U.S. patent application Ser. No. 10/444,519, filed May 23, 2003, entitled “Coordination of Competing Protocols”, and 
     3. U.S. patent application Ser. No 10/380,877 entitled “Coordinating Multiple Air-Interface Subsystems that Serve a Common Host”. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to telecommunications in general, and, more particularly, to wireless local area networks. 
     BACKGROUND OF THE INVENTION 
       FIG. 1  depicts a schematic diagram of local area network  100  in the prior art, which comprises telecommunication stations  101 - 1  through  101 -K, wherein K is a positive integer, and shared-communications channel  102 , interconnected as shown. Stations  101 - 1  through  101 -K enable associated host computers to communicate blocks of data, or “frames,” to each other. Stations  101 - 1  through  101 -K comprise transceivers that enable communications via shared-communications channel  102 . 
     In a mixed network such as local area network  100 , some of the stations (e.g., station  101 - 1 , etc.) operate in accordance with the IEEE 802.11 set of protocols, and some of the stations (e.g., station  101 - 4 , etc.) operate in accordance with the Bluetooth set of protocols. Still other stations of local area network  100  operate in accordance with both protocols. The stations comprising transceivers that communicate in accordance with IEEE 802.11 are able to take turns accessing shared-communications channel  102  because they all embody IEEE 802.11 access rules and follow those rules. Similarly, the stations comprising transceivers that communicate in accordance with Bluetooth are able to take turns accessing shared-communications channel  102  because they all embody Bluetooth access rules and follow those rules. 
     When IEEE 802.11 transceivers and Bluetooth transceivers—situated either in separate stations or within the same station-have to use the same, shared-communications channel (i.e., shared-communications channel  102 ), the rules for accessing (and sharing) shared-communications channel  102  are not as well defined as for the case where all transceivers use the same protocol. For example, Bluetooth station  101 - 4  might attempt to transmit when IEEE 802.11 station  101 - 1  is already transmitting, and the result would most likely be that neither station successfully transmits during that particular attempt. Depending on the contention for shared-communications channel  102 , neither the Bluetooth stations nor the IEEE 802.11 stations would operate effectively enough to be of much value to the end user. 
     Therefore, the need exists for a way to coordinate multiple air interface protocols that are used to access the same, shared-communications channel without some of the disadvantages in the prior art. 
     SUMMARY OF THE INVENTION 
     The present invention enables both an IEEE 802.11 transceiver and a Bluetooth transceiver to be employed in a single telecommunication station without the transceivers interfering on each other. In particular, the illustrative embodiment enables standard, “off-the-shelf,” IEEE 802.11 and Bluetooth transceivers to work in a coordinated fashion in a single telecommunications station. In some embodiments, the two transceivers are in separate stations. 
     In the illustrative embodiment, an IEEE 802.11 transceiver that uses a shared-communications channel notifies a Bluetooth transceiver that a transmit opportunity exists and that the Bluetooth transceiver has permission to use the shared-communications channel. The channel access controller associated with the IEEE 802.11 transceiver determines the optimal times to relinquish control of the shared-communications channel to the Bluetooth transceiver, in part based on (i) the times of arrival of beacon frames and (ii) the information within each beacon frame. The IEEE 802.11 transceiver can choose to (i) power down or (ii) stay powered up when it relinquishes control of the shared-communications channel. 
     In this specification, the illustrative embodiment is disclosed in the context of the IEEE 802.11 and Bluetooth protocols; it will be clear to those skilled in the art, however, how to make and use alternative embodiments of the present invention for other combinations of competing protocols (i.e., protocols that might interfere with each other). In addition, although the illustrative embodiment is disclosed in the context of radio transceivers, it will be clear to those skilled in the art how to make and use alternative embodiments of the present invention for non-radio frequency wireless devices or wireline transceivers that might interfere with each other. 
     The illustrative embodiment of the present invention comprises: receiving at a first transceiver a beacon frame wherein the beacon frame comprises a beacon interval and wherein the first transceiver communicates in accordance with a first communications protocol using a shared-communications channel; determining a transmit opportunity on the shared-communications channel wherein the transmit opportunity is based on the time at which the beacon frame is received and on the beacon interval; and notifying a second transceiver of the transmit opportunity wherein the second transceiver communicates in accordance with a second communications protocol using the shared-communications channel. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  depicts a schematic diagram of wireless local area network  100  in the prior art. 
         FIG. 2  depicts a schematic diagram of a portion of local area network  200  in accordance with the illustrative embodiment of the present invention. 
         FIG. 3  depicts a block diagram of the salient components of dual station  204 - 1  in accordance with the illustrative embodiment of the present invention. 
         FIG. 4  depicts a block diagram of the salient components of air interface subsystem  301 -i in accordance with the illustrative embodiment of the present invention. 
         FIG. 5  depicts a flowchart of the salient tasks performed by air interface subsystem  301 -i in accordance with the first illustrative embodiment of the present invention. 
         FIG. 6  depicts a schematic diagram of a beacon frame in accordance with the illustrative embodiment of the present invention. 
         FIG. 7  depicts a flowchart of the salient tasks performed by air interface subsystem  301 -i in accordance with the second illustrative embodiment of the present invention. 
         FIG. 8  depicts a message flow diagram of message transmissions between air interface subsystems in accordance with the illustrative embodiment of the present invention. 
         FIG. 9  depicts a message flow diagram of message transmissions between stations in accordance with the illustrative embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 2  depicts a schematic diagram of a portion of local area network  200  in accordance with the illustrative embodiment of the present invention. Network  200  operates in accordance with the IEEE 802.11 and Bluetooth sets of protocols, and comprises access point  201 , first protocol 802.11 stations  202 - 1  through  202 -L, wherein L is a natural number; second protocol stations  203 - 1  through  203 -M, wherein M is a natural number; dual protocol stations  204 - 1  through  204 -N, wherein N is a natural number; host computers  205 - 1  through  205 -P, wherein P is equal to the sum of L, M, and N; and wireless shared-communications channel  206 , interconnected as shown. 
       FIG. 2  depicts a network configuration with L equal to two, M equal to two, and N equal to one. It will be clear, however, to those skilled in the art, after reading this specification, how to make and use embodiments of the present invention that use different values for L, M, and N. 
     In the examples provided in this specification, first protocol stations  202 - 1  through  202 -L and second protocol stations  203 - 1  through  203 -M are IEEE 802.11 and Bluetooth compliant, respectively. Furthermore, dual stations  204 - 1  through  204 -N are both IEEE 802.11 and Bluetooth compliant. Access point  201 , a coordinating station that is described below, is at least IEEE 802.11 compliant. In some embodiments, access point  201  is both IEEE 802.11 and Bluetooth compliant. It will be clear, however, to those skilled in the art, after reading this specification, how to make and use embodiments of the present invention that operate in accordance with other protocols. Furthermore, it will be clear to those skilled in the art, after reading this specification, how to make and use embodiments of the present invention that use a wireline or tangible shared-communications channel. 
     Access point  201  coordinates the communications of at least some of the stations within local area network  200 . For example, first protocol stations  202 - 1  through  202 -L and dual protocol stations  204 - 1  through  204 -N, when using the protocol of first protocol stations  202 - 1  through  202 -L, communicate with each other through access point  201 . It will be clear to those skilled in the art how to make and use access point  201 . 
     Each station comprises one or more transceivers that enable host computer  205 - j , for j=1 to P, to transmit signals and receive signals via shared-communications channel  206 . A “transceiver” is capable of two-way communication over a communications channel (e.g., shared-communications channel  206 , etc.). For example, dual station  204 - 1  is capable of receiving data blocks from host computer  205 - 5  (i.e., the host computer with which dual station  204 - 1  is associated) and transmitting over shared-communications channel  206  data frames comprising the data received from host computer  205 - 5 . Dual station  204 - 1  is also capable of receiving data frames from shared communications channel  206  and sending to host computer  205 - 5  data blocks comprising data from the data frames. It will be clear to those skilled in the art, after reading this specification, how to make and use dual station  204 - 1 . The salient details for dual station  204 - 1  are described below and with respect to  FIG. 3 . 
     Host computer  205 - j , for j=1 to P, is capable of generating data blocks and providing those data blocks to its associated station. Host computer  205 - j  is also capable of receiving data blocks from its associated station and of processing and using the data contained within those data blocks. Host computer  205 - j  can be, for example, a desktop computer, a laptop computer, a wireless telephone, or a personal digital assistant (PDA) that uses local area network  200  to communicate with other hosts and devices. It will be clear to those skilled in the art how to make and use host computer  205 - j.    
       FIG. 3  depicts a block diagram of the salient components of dual station  204 - 1  in accordance with the illustrative embodiment of the present invention. Dual station  204 - 1  supports two distinct wireless air interface protocols for the purpose of transmitting and receiving data over the air via shared-communications channel  206 . The wireless protocols supported by dual station  204 - 1  can be, for example, IEEE 802.11 and Bluetooth. Dual station  204 - 1  comprises: air interface subsystem  301 - 1 , air interface subsystem  301 - 2 , and antenna switch  302 , interconnected as shown. Air interface subsystem  301 - 1  and air interface subsystem  301 - 2  communicate with each other via interface  303 . 
     Air interface subsystem  301 - i , for i=1 to Q wherein Q is a positive integer greater than one, enables associated host computer  205 - j  (i.e., host computer  205 - 5  paired with dual station  204 - 1 ) to communicate via shared-communications channel  206 . In the illustrative example, Q is equal to two. It will be clear, however, to those skilled in the art, after reading this specification, how to make and use dual station  204 - i  with other values of Q. 
     Air interface subsystems  301 - 1  and  301 - 2  comprise the transceivers that enable host computer  205 - j  to communicate using two different air interface protocols. Each of air interface subsystems  301 - 1  and  301 - 2  operates in accordance with a different air interface protocol (e.g., IEEE 802.11, Bluetooth, etc.). It will be clear to those skilled in the art, after reading this specification, how to make and use air interface subsystems  302 - 1  and  302 - 2 . 
     Antenna switch  302  enables air interface subsystems  301 - 1  and  301 - 2  to share a single antenna unit for the purpose of using shared-communications channel  206 . Antenna switch  302  provides signals to air interface subsystem  301 - i . Antenna switch  302  also accepts signals from air interface subsystem  301 - i . It will be clear to those skilled in the-art how to make and use antenna switch  302 . 
       FIG. 4  depicts a block diagram of the salient components of air interface subsystem  301 - i  in accordance with the illustrative embodiment of the present invention. Air interface subsystem  301 - i  comprises receiver  401 - i , processor  402 - i , memory  403 - i , and transmitter  404 - i , interconnected as shown. 
     Receiver  401 - i  is a circuit that is capable of receiving frames from shared-communications channel  206 , in well-known fashion, and of forwarding them to processor  402 - i . It will be clear to those skilled in the art how to make and use receiver  401 - i.    
     Processor  402 - i  is a general-purpose processor that is capable of performing the tasks described below and with respect to  FIGS. 5 through 9 . It will be clear to those skilled in the art, after reading this specification, how to make and use processor  402 - i.    
     Memory  403 - i  is capable of storing programs and data used by processor  402 - i . It will be clear to those skilled in the art how to make and use memory  403 - i.    
     Transmitter  404 - i  is a circuit that is capable of receiving frames from processor  402 - i , in well-known fashion, and of transmitting them on shared-communications channel  206 . It will be clear to those skilled in the art how to make and use transmitter  404 - i.    
     The combination of receiver  401 - i  and transmitter  404 - i  constitutes the transceiver part of air interface subsystem  301 - i.    
       FIG. 5  depicts a flowchart of the salient tasks performed by air interface subsystem  301 - i  in accordance with the first illustrative embodiment of the present invention. It will be clear to those skilled in the art which tasks depicted in  FIG. 5  can be performed simultaneously or in a different order than that depicted. Although air interface subsystems  301 - 1  and  301 - 2  of dual station  204 - 1  are used as examples, it will be clear to those skilled in the art how to apply the tasks represented in  FIG. 5  of the illustrative embodiment to other air interface subsystems. 
     Air interface subsystem  301 - 1  communicates in accordance with a first communications protocol (e.g., IEEE 802.11, etc.) using shared-communications channel  206 . Air interface subsystem  301 - 2  communicates in accordance with a second communications protocol (e.g., Bluetooth, etc.), also using shared-communications channel  206 . 
     At task  501 , air interface subsystem  301 - 1  receives a beacon frame. In some embodiments, access point  201  transmits the beacon frame in well-known fashion. The beacon frame, depicted in  FIG. 6 , comprises a “beacon interval” as is known in the art. The beacon interval defines how far apart in time successive beacon frames are spaced. Air interface subsystem  301 - 1  can determine when subsequent beacon frames will arrive based on the arrival time of the beacon frame received at task  501  and on the beacon interval. 
     At task  502 , air interface subsystem  301 - 1  determines the optimal time to relinquish control to air interface subsystem  301 - 2  (i.e., when to provide a “transmit opportunity” on shared-communications channel  206 ). Air interface subsystem  301 - 1  bases the transmit opportunity on when and how long it expects shared-communications channel  206  to be free of at least predictable traffic, such as beacon frames and the traffic generated by air interface subsystem  301 - 1 . 
     For example, if air interface subsystem  301 - 1  calculates that the time until the next beacon frame transmission is relatively long and it does not have to transmit immediately on shared-communications channel  206 , then air interface subsystem  301 - 1  determines a transmit opportunity to exist for air interface subsystem  301 - 2 . Conversely, if air interface subsystem  301 - 1  calculates that the time until the next beacon frame transmission is relatively short or if air interface subsystem  301 - 1  is continuing to use shared-communications channel  206 , then air interface  301 - 1  determines a transmit opportunity to not exist. The latter determination is based on the preference to avoid interfering with anticipated transmissions. 
     In some embodiments, air interface subsystem  301 - 1  also bases the transmit opportunity on receiving from air interface subsystem  301 - 2  at least one request to transmit. The request to transmit, if received from air interface subsystem  301 - 2 , can arrive periodically or not. If the request to transmit is periodic, air interface subsystem  301 - 1  can determine in well-known fashion the periodicity of air interface subsystem  301 - 2 &#39;s requests, predict when the next request to transmit will arrive, and proactively issue a transmit opportunity that coincides with the anticipated request to transmit. 
     It will be clear to those skilled in the art, after reading this specification, how to determine whether or not a transmit opportunity exists and, if a transmit opportunity exists, for how long. 
     In some embodiments, air interface subsystem  301 - 1  transmits a control frame (e.g., request_to_send, clear_to_send, etc.) to itself in well-known fashion, specifying a duration value based on the length of the transmit opportunity. The duration value, in combination with the virtual carrier sense mechanism known in the art, has the effect of muting the transceivers of other stations that communicate in accordance with the protocol used by air interface subsystem  301 - 1 . 
     Air interface subsystem  301 - 1  can power down its transceiver after air interface subsystem  301 - 1  determines the transmit opportunity, or it can keep its transceiver turned on. Air interface subsystem  301 - 1  can direct the action of powering down at the transmitter part, the receiver part, or both parts of the transceiver. 
     At task  503 , air interface subsystem  301 - 1  notifies air interface subsystem  301 - 2  of the transmit opportunity. The notification can occur through a direct link, such as interface  303 , or an indirect link. The notification can be in the form of a message, a discrete signal, or other form. It will be clear to those skilled in the art how one subsystem can notify another subsystem of a transmit opportunity. 
     In some embodiments, air interface subsystem  301 - 1  notifies more than one co-existing air interface subsystem of the transmit opportunity. In other embodiments, air interface subsystem  301 - 1  selects a single air interface subsystem to notify for each transmit opportunity, out of multiple air interface subsystems. The selection criteria can be based on a round-robin approach, a random selection approach, the number of requests to transmit made by co-existing air interface subsystems, etc. It will be clear to those skilled in the art how to select the air interface subsystem or subsystems to notify. 
     Later in some embodiments, when the transmit opportunity is at an end, air interface subsystem  301 - 1  notifies air interface subsystem  301 - 2  of that event. Air interface  301 - 2  can determine the end of the transmit opportunity by knowing when the next beacon frame is to be transmitted or through some other criteria. It will be clear to those skilled in the art, after reading this specification, how to determine when the transmit opportunity is at an end. 
       FIG. 7  depicts a flowchart of the salient tasks performed by air interface subsystem  301 - i  in accordance with the second illustrative embodiment of the present invention. It will be clear to those skilled in the art which tasks depicted in  FIG. 7  can be performed simultaneously or in a different order than that depicted. Although air interface subsystems  301 - 1  and  301 - 2  of dual station  204 - 1  are used as examples, it will be clear to those skilled in the art how to apply the tasks represented in  FIG. 7  of the illustrative embodiment to other air interface subsystems. 
     Air interface subsystem  301 - 1  communicates in accordance with a first communications protocol (e.g., IEEE 802.11, etc.) using shared-communications channel  206 . Air interface subsystem  301 - 2  communicates in accordance with a second communications protocol (e.g., Bluetooth, etc.), also using shared-communications channel  206 . 
     At task  701 , air interface subsystem  301 - 1  receives a first beacon frame. In some embodiments, access point  201  transmits the beacon frame in well-known fashion. The first beacon frame comprises a “beacon interval” as is known in the art. Air interface subsystem  301 - 1  can determine when subsequent beacon frames will arrive based on the arrival time of the first beacon frame received at task  701  and on the beacon interval. 
     At task  702 , air interface subsystem  301 - 1  determines the optimal time to relinquish control to air interface subsystem  301 - 2  (i.e., when to provide a “transmit opportunity” on shared-communications channel  206 ). Air interface subsystem  301 - 1  can base the transmit opportunity on when and how long it expects shared-communications channel  206  to be free of at least predictable traffic, such as beacon frames and the traffic generated by air interface subsystem  301 - 1 . 
     In some embodiments, air interface subsystem  301 - 1  can also base the transmit opportunity on receiving from air interface subsystem  301 - 2  at least one request to transmit. The request to transmit, if received from air interface subsystem  301 - 2 , can arrive periodically or not. If the request to transmit is periodic, air interface subsystem  301 - 1  can determine the periodicity of air interface subsystem  301 - 2 &#39;s requests in well-known fashion, predict when the next request to transmit will arrive, and proactively declare a transmit opportunity that coincides with the anticipated request to transmit. 
     It will be clear to those skilled in the art, after reading this specification, how to determine whether or not a transmit opportunity exists and, if a transmit opportunity exists, for how long. 
     In some embodiments, air interface subsystem  301 - 1  transmits a control frame (e.g., request_to_send, clear_to_send, etc.) to itself in well-known fashion, specifying a duration value based on the length of the transmit opportunity. The duration value, in combination with the virtual carrier sense mechanism known in the art, has the effect of muting the transceivers of other stations that communicate in accordance with the protocol used by air interface subsystem  301 - 1 . 
     At task  703 , air interface subsystem  301 - 1  notifies air interface subsystem  301 - 2  of the transmit opportunity. Notification can occur through a direct link, such as interface  303 , or an indirect link. It will be clear to those skilled in the art how one subsystem can notify another subsystem of a transmit opportunity. 
     In some embodiments air interface subsystem  301 - 1  notifies more than one co-existing air interface subsystem of the transmit opportunity. In other embodiments, air interface subsystem  301 - 1  selects a single air interface subsystem to notify for each transmit opportunity, out of multiple air interface subsystems. The selection criteria can be based on a round-robin approach, a random selection approach, the number of requests to transmit made by co-existing air interface subsystems, etc. It will be clear to those skilled in the art how to select the air interface subsystem or subsystems to notify. 
     At task  704 , air interface subsystem  301 - 1  powers down its transceiver. Air interface subsystem  301 - 1  can direct the action of powering down at transmitter  404 - i , receiver  401 - i , or both transmitter  404 - i  and receiver  401 - i  (i.e., one or both parts of the transceiver). The length of time that the transceiver is powered down depends on the time remaining before air interface subsystem  301 - 1  receives a second beacon frame. The length of time can also depend on the time it takes the transceiver to recover from being powered down (i.e., to transition electronically from a powered down to a powered up state). 
     Later in some embodiments, when the transmit opportunity is at an end, air interface subsystem  301 - 1  notifies air interface subsystem  301 - 2  of that event. Air interface  301 - 2  can determine the end of the transmit opportunity by knowing when the next beacon frame is to be transmitted or through some other criteria. It will be clear to those skilled in the art, after reading this specification, how to determine when the transmit opportunity is at an end. 
       FIG. 8  depicts a message flow diagram of message transmissions between air interface subsystems in accordance with the illustrative embodiment of the present invention. For illustrative purposes, air interface  301 - 1  and access point  201  operate in accordance with the IEEE 802.11 set of protocols and air interface  301 - 2  operates in accordance with the Bluetooth set of protocols. Although air interface subsystems  301 - 1  and  301 - 2  of dual station  204 - 1  are used as examples, it will be clear to those skilled in the art how to apply the tasks represented in  FIG. 8  of the illustrative embodiment to other air interface subsystems. 
     With message  801 , air interface subsystem  301 - 2  transmits to air interface subsystem  301 - 1  a request to use shared-communications channel  206 . 
     With message  802 , access point  201  broadcasts a beacon frame comprising a beacon interval. 
     With message  803 , air interface subsystem  301 - 1 , having received the beacon frame, notifies air interface subsystem  301 - 2  of the transmit opportunity (i.e., the opportunity to use shared-communications channel  206 ). Air interface subsystem  301 - 2  might take advantage of the transmit opportunity by transmitting one or more frames to another station (e.g., second protocol station  203 - 2 , etc.), or it might not. 
     With message  804 , air interface subsystem  301 - 1  notifies air interface subsystem  301 - 2  that the transmit opportunity is at an end. 
     With message  805 , access point  201  broadcasts the next beacon frame, also comprising a beacon interval. 
       FIG. 9  depicts a message flow diagram of message transmissions between stations in accordance with the illustrative embodiment of the present invention. For illustrative purposes, access point  201  operates in accordance with both the IEEE 802.11 and Bluetooth sets of protocols, and second protocol stations  203 - 1  and  203 - 2  operate in accordance with the Bluetooth set of protocols. Although second protocol stations  203 - 1  and  203 - 2  are referred to as examples, it will be clear to those skilled in the art how to apply the tasks represented in  FIG. 9  of the illustrative embodiment to other stations. 
     With message  901 , second protocol station  203 - 1  transmits to access point  201  a request to use shared-communications channel  206 . 
     With message  902 , access point  201  broadcasts a beacon frame comprising a beacon interval. 
     With message  903 , access point  201 , aware of the beacon frame timing and beacon interval, notifies second protocol station  203 - 1  of the transmit opportunity (i.e., the opportunity to use shared-communications channel  206 ). 
     Second protocol station  203 - 1  takes advantage of the transmit opportunity by transmitting one or more frames to another station (e.g., message  904  transmitted to second protocol station  203 - 2 , etc.). 
     With message  905 , access point  201  notifies second protocol station  203 - 1  that the transmit opportunity is at an end. 
     With message  906 , access point  201  broadcasts the next beacon frame, also comprising a beacon interval. 
     It is to be understood that the above-described embodiments are merely illustrative of the present invention and that many variations of the above-described embodiments can be devised by those skilled in the art without departing from the scope of the invention. It is therefore intended that such variations be included within the scope of the following claims and their equivalents.