Abstract:
A multiple-interface radio terminal is provided with facilities which dynamically assign a stream of packet data to be transmitted to a selected one of a plurality of interface(s). The interfaces respectively support channels that share a common frequency spectrum but that operate with different transmission protocols, for example the Bluetooth and 802.11 protocols. The terminal is provided with an interface manager that periodically transmits query signals to the respective channels to obtain and store refreshable inputs representative of a selected transmission condition(s) on such channels. Upon the occurrence of a connection request at the terminal, the interface manager compares the latest stored samples from the respective channels with a reference metric to generate an indication which represents the relative states of the channels with regard to the selected transmission condition. The terminal further includes a selector which utilizes an indication from the interface manager to route the incoming packets to be transmitted to the particular interface whose associated channel exhibits the desired relative state.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    This invention relates to packet transmission systems whose channels operate with diverse transmission protocols, and more particularly to such systems and related terminals whose channels share a common frequency spectrum.  
           [0002]    Packet data transmission on parallel channels operating over a common frequency range but utilizing different radio protocols is now common. For example, when such transmission is in the 2.4 GHz Industrial—Scientific—Medical band, a first subset of the channels may utilize the Bluetooth protocol, while another subset of the channels may utilize the IEEE802.11 protocol. Streams of data to be transmitted in this manner are often assigned to specified ones of such parallel channels by associated radio terminals. In the presence of a deterioration of transmission conditions on one of the channels, the data assigned to such channel is subject to distortion, delay and the like. Certain techniques are available that attempt to minimize such adverse effects on data that is currently propagating on the affected channel. However, such techniques have not been fully satisfactory, particularly where real-time or other high-priority information is being transmitted.  
         SUMMARY OF THE INVENTION  
         [0003]    The present invention provides a multiple -interface radio terminal that, a priori, assigns a stream of packet data to be transmitted to a selected one of a plurality of interface(s) that support disparate channels that share a common frequency spectrum but that operate with different transmission protocols. The selection is made dynamically by the terminal through an interface manager in response to periodically obtained refreshable inputs representative of selected transmission conditions on the respective channels.  
           [0004]    In an illustrative embodiment wherein the terminal utilizes disparate first and second interfaces of the type indicated in the previous paragraph, the terminal includes a selector operable between first and second modes for respectively directing incoming packets to the first and second interfaces. The interface manager periodically receives samples of quantities representing the selected transmission criteria on the respective channels, and stores them over separately selectable times. Upon the occurrence of a connection request at the terminal, the interface manager compares the latest stored samples from the respective channels with a reference metric to generate first and second indications. The interface manager operates the selector in the first mode when the first and second indications differ in one sense and in the second mode when such indications differ in the opposite sense. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWING  
       [0005]    These and other features of the invention are further set forth in the following detailed description taken in conjunction with the appended drawing, in which:  
         [0006]    [0006]FIG. 1 is a block diagram of an illustrative multiple-interface radio terminal for separately supporting packet transmission using the Bluetooth and 802.11 protocols;  
         [0007]    [0007]FIG. 2 is a representation of a pair of separate Bluetooth and 802.11 channels over which the terminal of FIG. 1 may communicate with selective ones of a plurality of Bluetooth access points and 802.11 access points; and  
         [0008]    [0008]FIG. 3 is a block diagram of an interface manager implemented in accordance with the invention and used in connection with the terminal of FIG. 1. 
     
    
     DETAILED DESCRIPTION  
       [0009]    Referring to the drawing, FIG. 1 depicts a terminal  10  illustratively having a plurality of co-located radio interfaces, two of which are shown and represented at  11  and  12 . The interfaces  11  and  12  respectively support wireless transmission of application data packets on separate channels or links  13  and  14  that operate within the same frequency band but utilize different standard transmission protocols. Illustratively, the interface  11  supports Bluetooth transmission on the channel  13  via a radio module  16 , and the interface  12  supports 802.11 transmission on the channel  14  via a radio module  17 .  
         [0010]    Connection requests, illustratively in TCP/IP format, are conventionally applied to a host interface  18  of the terminal  10  under the control of an upper layer application, followed by data packets to be transmitted from the terminal  10  after such connection is established. (The structure and operation of the terminal  10 , both as already described and as will be further described below, are completely transparent to such upper layer application).  
         [0011]    The data packets applied to the host interface  18  for transmission from the terminal  10  are coupled through a CPU core  19  to a selector  21  that is implemented in accordance with one aspect of the invention. The selector  21  has a pair of operating modes wherein the incoming packets associated with each connection request are routed to a separate one of two outputs  22  and  23 . The outputs  22  and  23  are respectively associated with the Bluetooth interface  11  and the  802 . 11  interface  12 . In particular, operation of the selector  21  in a first one of such modes will cause packets incident on the terminal  10  to be routed to the Blue tooth output  22 , while operation of such selector in the other (second) mode will cause such packets to be routed to the  802 . 11  output  23 . Determination of the operating mode of the selector  21  for any given connection request is governed by an interface manager  24  as indicated below.  
         [0012]    The output  22  of the selector  21  is connected to a baseband controller  26  which conventionally encodes packets appearing at the output  22  with conventional FH-CDMA frequency hopping patterns unique to each Bluetooth channel established by the terminal  10 . The output  23  of the selector  21  is correspondingly connected to a baseband controller  27  which conventionally encodes packets appearing at the output  23  with conventional 802.11 direct spread frequency patterns unique to each 802.11 channel established by the terminal  10 . (As indicated above, only a single pair of channels that respectively carry Blue tooth and 802.11 traffic are depicted in FIG. 1).  
         [0013]    While not specifically indicated in the drawing, it will be understood that the generation of frequency hopping patterns emanating from the controller  26  under Bluetooth protocols may utilize suitable information concerning, e. g., the time of establishment of the Blue tooth connection  13  and the unique, factory set Blue tooth address of the master radio module (illustratively the module  16 ) that establishes the channel  13 . Such inputs are conventionally provided by the module  13  to the controller  26 . Corresponding information for the generation of the direct spread frequency patterns by the controller  27  in accordance with  802 . 11  protocols may be suitably provided to the controller  14  for the channel  14  by the associated radio module  17 . Referring to FIG. 2, each of the radio modules  16  and  17  may conventionally establish a connection, over the associated one of the channels  13  and  14 , with a correspondent device operating in accordance with the applicable transmission protocol. The correspondent device for the Blue tooth radio module  16  may be a conventional Bluetooth device  31 , with which the module  16  may establish a direct peer-to-peer connection. Alternatively, the correspondent device for the radio module  16  may be a selected one of a plurality of conventional Bluetooth access points (3AD&#39;s), three of which are illustrated at  32 A,  32 B and  32 C. Such BAD&#39;s respectively have radio interfaces  33 A,  33 B and  33 C which are connectable to the channel  13 . The BAD&#39;s  32 A- 32 C are also respectively provided with second interfaces  34 A,  34 B and  34 C which serve to connect such access points with an external network or terminal represented at  36 , either directly or through an intervening wireless network (not shown) as appropriate.  
         [0014]    On the 802.11 side, the correspondent device for the radio module  17  on the channel  14  may be a selected one of a plurality of 802.11 access points (AP&#39;s), three of which are illustrated at  37 A,  37 B and  37 C. Such AP&#39;s respectively have radio interfaces  38 A,  38 B and  38 C which are connectable to the channel  14 . The AP&#39;s  37 A- 37 C are also respectively provided with second interfaces  39 A,  39 B and  39 C which are connectable to an external network  40 .  
         [0015]    In accordance with another aspect of the invention, the interface manager  24  determines the operating mode of the selector  21  in accordance with a selected relative transmission condition(s) on the channels  13  and  14 . For example, if a connection request is received by the terminal  10  when one of the channels (illustratively the 802.11 channel  14 ) is already operating at full capacity, the interface manager  24  operates the selector  21  in the first mode, which routes the incoming packets to the output  22 . As a result, transmission of such packets will take place over the Bluetooth channel  13 .  
         [0016]    By contrast, during times when capacity is available on both of the channels  13  and  14 , the mode selection by the interface manager  24  may illustratively be governed by a comparison of selected transmission conditions that are sampled at periodic intervals on the respective channels  13  and  14 . Among the typical transmission conditions which the interface manager  24  may utilize for this purpose with respect to the Bluetooth channel  13  may be the usage levels of the several access points  32 A- 32 C (as measured in terms of a percentage of available resources), the received signal strength on the channel  13 , and transmission delays on such channel. In like manner, typical conditions that may be utilized by the interface manager  24  in connection with  802 . 11  transmissions over the channel  14  may include the usage level of the several access points  37 A- 37 C, an indication of received signal strength on the channel  14 , and transmission delays on such channel. As explained below, the interface manager  24  periodically evaluates indications representative of the selected condition on each of the channels  13  and  14  against a predetermined metric and determines the most advantageous mode for the selector  21  based on such evaluation.  
         [0017]    An illustrative embodiment of the interface manager  24  is described in more detail in connection with FIGS. 1 and 3. A pair of diagnostic circuits  41  and  42  are independently coupled to the channels  13  and  14  through the interfaces  11  and  12  and the radio modules  16  and  17 . At recurrent first intervals dictated by a pair of associated timers  43  and  44 , each of the diagnostic circuits  41  and  42  transmits a beacon signal to the associated channel to collect samples indicative of the selected transmission condition to be evaluated. In response to such beacon signals, samples indicative of the applicable condition on the respective channels are returned to the diagnostic circuit  41  and  42  and are stored in associated buffers  46  and  47  for second recurrent intervals set by the respective timers  43  and  44 . The periodic collection of samples continues during the time that the terminal  10  is active, even when there is no connection request incident on the terminal  10 .  
         [0018]    Preferably, the collection intervals and storage times for the samples requested by the diagnostic circuits  41  and  42  are independently selectable. For example, the diagnostic circuit  41  may collect samples of the relative criteria on the channel  13  every ten seconds, and store them in the associated buffer  46  for five minutes. On the other hand, the diagnostic circuit  42  may collect samples from the channel  14  every twenty seconds, and store them in the associated buffer  47  for sixty minutes. If no connection request occurs during a particular storage interval for one of the samples, such sample is discarded by the associated buffer at the end of the storage interval and refreshed as a later-collected sample.  
         [0019]    The outputs of the respective buffers  46  and  47  are applied to first inputs of a pair of comparators  48  and  49 . A reference metric for the condition(s) being measured on the channels  13  and  14  is created by a suitable generator  51  and is applied in parallel to second inputs of the comparators  48  and  49 . The outputs of the comparators  48  and  49  may therefore represent deviations, from the reference metric established by the generator  51 , of the latest refreshed samples of the measured criteria on the channels.  
         [0020]    The characteristics of a connection request incident of the terminal  10  may also be employed to fine-tune the information applied to the comparators  48  and  49 . For this purpose such connection requests may also be individually applied, via core  19 , to inputs  52  and  53  of the comparators  48  and  49 . Typical information from the connection requests for this purpose may include, e. g., information regarding bandwidth requirements for the packets to be transmitted and, where the connection request is for a file transfer, the total number of bytes to be transferred.  
         [0021]    The outputs of the comparators  48  and  49  are respectively applied to differential inputs  54  and  56  of a mode determination circuit  57 . In addition, signals indicative of the occurrence of connection requests applied to the terminal  10  are coupled to a gating input  58  of the determination circuit  57  from the core  19 . With this arrangement, each time a connection request is applied to the terminal  10 , the then-refreshed output of the determination circuit  57  is gated to the selector  21 .  
         [0022]    The determination circuit  57  is so configured that when the output of the comparator  48  is greater than the output of the comparator  49 , the determination circuit will operate the selector  21  in the first mode. Conversely, when the output of the comparator  49  is greater than the output of the comparator  48 , the determination circuit will operate the selector  21  in its second mode. As one example, such opposite relative states on the outputs of the comparators  48  and  49  may illustratively indicate greater or lesser usage levels, respectively, of the 802.11 access points  38 A- 38 C (FIG. 2) relative to those of the Bluetooth access points  32 A- 32 C.  
         [0023]    In the foregoing, the invention has been described in connection with illustrative implementations thereof. Many variations, modifications, and other examples will now occur to those skilled in the art. For instance, while the terminal  10  has been exemplified in connection with two channels each operating with a different transmission protocol, it will be appreciated that the principles of the invention are applicable to any reasonable number of channels of each type. It is accordingly desired that the scope of the appended claims not be limited to or by the specific disclosure herein contained.