Abstract:
A method and apparatus is provided for managing bandwidth and prioritizing different forms of data to be transmitted from a central hub or node to a plurality of ground stations. All data of all types including image data and text data is processed into frames of TCP formatted data at the central hub or node and passed through a bandwidth flow control system which imposes flow control on the data. Some of the TCP formatted data has inserted therein a conversion flag which denotes a desire to convert the TCP formatted data into UDP formatted data. A computer or controller/converter reads the conversion flags and converts TCP formatted data into UDP formatted data for multi-broadcasting simultaneously to a plurality of ground stations which reduces bandwidth.

Description:
RELATED APPLICATIONS  
       [0001]    This application is designed to make use of information supplied by ground stations as taught in our copending U.S. application Ser. No. 08/854,104 filed May 11, 2001 for a Dual Mode of Operation Multiple Access System for Data Link Communication which is incorporated by reference herein. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    1. Field of the Invention  
           [0003]    The present invention relates to communication networks of the type employed between airborne platforms and ground stations. More particularly, the present invention relates to a method and system for controlling the bandwidth of data transmitted by airborne transmitters to multiple ground station receivers.  
           [0004]    2. Description of the Prior Art  
           [0005]    Heretofore, point-to-point networks have been employed as intranets in businesses and as internets in the worldwide web. Point-to-point communications relate to a message or data sent to a particular receiver or user from a single source. When there are a number of receivers, the same message must be sent to each of the receivers which increases the bandwidth proportional to the number of receivers. U.S. Pat. Nos. 6,038,216 and 6,046,980, and references cited therein, have suggested a method and system for managing bandwidth in point-to-point networks by assigning priorities to the type of data and to the individual receivers or users. There are no known systems or apparatus for prioritizing messages and data in multi-broadcast or point-to-multipoint network systems.  
           [0006]    It would be highly desirable to provide a method and a system for managing bandwidth in a point-to-multipoint central node airborne broadcasting system.  
         SUMMARY OF THE INVENTION  
         [0007]    It is a primary object of the present invention to provide a system and method for managing bandwidth in User Datagram Protocol (UDP) systems.  
           [0008]    It is a primary object of the present invention to provide a system and method for simultaneously managing bandwidth in both point-to-point and point-to-multipoint broadcast networking systems.  
           [0009]    It is a principal object of the present invention to provide a system and method for simultaneously managing bandwidth in Transmission Control Protocol (TCP) and UDP systems.  
           [0010]    It is a primary object of the present invention to provide a system and method for converting TCP data to UDP data.  
           [0011]    It is a primary object of the present invention to provide a dedicated controller or personal computer (PC) for reading fields of a TCP header and determining whether or not it will be converted into a UDP format data and header.  
           [0012]    It is a principal object of the present invention to provide a dedicated controller or PC for assimilating data from a plurality of TCP headers and converting the TCP data into UDP headers and data for multipoint broadcasting of data.  
           [0013]    It is a primary object of the present invention to provide a method and system for broadcasting TCP headers and data and UDP headers and data randomly intersperced.  
           [0014]    According to these and other objects of the present invention there is provided a communications network between an airborne platform and a plurality of ground stations (or a central node and a plurality of internet stations or nodes). A bandwidth flow control system is interposed between the stations and the central hub or platform which manages flow bandwidth of data in both TCP and UDP format simultaneously. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]    [0015]FIG. 1 is a table showing the seven protocol layers or levels of information used in Open Systems Interface (OSI) standard protocols;  
         [0016]    [0016]FIG. 2 is a schematic representation or arrangement of data in an Internet Protocol Header (IP Header) layer shown in FIG. 1;  
         [0017]    [0017]FIG. 3 is a schematic representation of a UDP Header which resides in the data field of the IP Header;  
         [0018]    [0018]FIG. 4 is a schematic representation of a TCP Header which resides in the data field of the IP Header; and  
         [0019]    [0019]FIG. 5 is a block diagram of the preferred embodiment of the present invention showing a computer in a central hub or airborne station connected to both a conventional internet network and to an airborne communications network.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0020]    Before referring to a detailed description, the applicants will use in this application the terms central node or central hub to mean any transmitting station that transmits to and receives from a plurality of stations various types of data. Thus, typical systems that would be employed in the present invention would be a system on the internet, a segment of the internet and/or a military airborne platform that disseminates surveillance data over wireless communication means to a plurality of ground stations.  
         [0021]    Refer now to FIG. l showing a table  10  having seven layers of protocol information as used in an OSI standard protocol system. The purpose of the OSI layers and the different layers within the OSI protocol is to provide a set of services at each of the layers which allows the layers to communicate with each other and allows computers or other devices to communicate with each other. The known layers are numbered L1 to L7.  
         [0022]    Refer now to FIG. 2 showing a schematic representation of the arrangement of data in the L3 network layer (IP Header) layer shown in FIG. 1. The IP Header format  12  is shown comprising rows of 32 bits numbered 0 to 31. The first five of the rows comprises 20 bytes and form the IP Header as part of the total length of the IP Header format. The field  13  is used to identify the version of IP Header being used. The field  14  is used to identify the number of 32 bit rows in the IP Header format. The field  15  is used to identify the type of service which was formerly a quality of service (QoS) and is now used for various uses. The field  16  is employed to denote the total length of the complete IP Header format as shown in the right margin. Since the data field  18  may comprise a variable number of rows R7 to RX, the total length of the IP Header format is needed. The only other field of importance to this invention is the field  11  which is used to designate the destination IP address. The remaining fields which have not been specifically discussed are standards fields and are found in textbooks and do not require additional explanation herein.  
         [0023]    Refer now to FIG. 3 showing a schematic representation of a UPD Header format which comprises two rows of 32 bits each comprising eight bytes and a data field which may comprise a variable length of data as will now be explained. The UPD Header format  20  is shown comprising a source port number field  19  and a destination port number field  21 . In order to identify the length of data there is a field  22  which defines the total number of bytes in the header and data field  24 . A 16 bit check sum is provided in field  23 .  
         [0024]    Refer now to FIG. 4 showing a schematic representation of a TCP Header format which resides in the data field  18  of the IP Header. The TCP Header format  25  is shown having a field  19 ′ which identifies the sender port number similar to that described in FIG. 3. The field  21 ′ defines the destination port number of the receiver and is similar to the field  21  in FIG. 3. The 32 bit sequence number  26  identifies the first sequence number for the data being sent in this particular TCP Header. The remaining fields of the TCP Header format shown in FIG. 4 are standard and are well known in this industry and do not require a detailed description.  
         [0025]    Refer now to FIG. 5 showing a block diagram of the preferred embodiment of the present invention system  27  comprising a central hub or airborne platform computer  28  connected to a conventional internet network and also connected in a broadcast configuration showing an airborne communications network. The central processing unit  28  is shown having protocol levels L1 and L2 at the ethernet level, having level L3 at the internet protocol level and having a transport control protocol level L4 at the transport level as described hereinbefore with reference to FIG. 1. The information formatted at the ethernet level is outputted as a TCP protocol data format package on line  29  and is inputted to a flow control system  31 . In the preferred embodiment of the present invention, the flow control system has been implemented in Packeteer™ software similar to QoS software packages provided by such firms as Cisco, Starburst, Sitara and Checkpoint Systems. The TCP data on line  29  also appears at the output of the flow control system on line  32  and is input into the PC or controller  33  at the TCP input port. The PC or controller  33  is shown comprising a logic portion  34  and a memory portion  35 . The memory and logic of the controller  33  determines by examining the flag data in the TCP format header whether or not the data should be converted to UDP format or should continue its journey in its TCP format at the output port  33 P.  
         [0026]    The UDP or TCP data and its header is coupled to a transmitter/receiver  36  which is provided with an antenna  37 . The information is broadcast to a plurality of ground stations  39  each comprising a transmitter/receiver and an antenna  38 . The ground stations  39  are capable of determining their maximum rate of data input or reception and may transmit this information from antenna  38  to antenna  37  which in turn is transmitted via line  43  to the CPU  28 . The CPU  28  uses this information to reprogram the flow control system  31  via line  45 .  
         [0027]    In a similar manner, the system described hereinbefore also may operate on an internet or a LAN or a WAN. In this event, the output information from port  33 P is supplied to the interface  41  which may be an internet interface and to line  42  which may be a local area network (LAN) line or wide area network (WAN) line  42 . The information on the network  42  is supplied to the plurality of stations  39 ′ or to individual stations as the case may be if it is a point-to-point network system. Similarly, the plural stations  39 ′ may transmit on network  42  to the interface  41  their ability to receive information from the computer  28  and this information is supplied via line  44  as shown.  
         [0028]    Having explained the preferred embodiment system FIG. 5 and an equivalent alternative system in the same drawing, it will be appreciated that both systems may not be operated together at the same time because one is airborne and the other one is basically a ground system. However, the computer or controller  33  which performs the conversion of TCP input data to UDP input data is the same and may be explained as follows with reference to FIGS. 3 and 4. In FIG. 4 there is shown a field number  21 ′ for the destination port number. When a predetermined number appears in the field  21 ′ of the TCP header the controller knows that the data in this header should be converted into a UDP header format. This predetermined number is also used by the controller  33  to modify the destination IP address  11  of IP header format  12  into a network destination IP address or a subnet destination IP address which may be read by all ground stations or a subset of the ground stations, respectively. The information shown in FIG. 4 is transferable directly from fields  19 ′, and  21 ′ directly into fields  19  and  21 . The controller  23  has to calculate the other fields and insert them in the proper place in the UDP header format. It will be understood that the data field  24  in the UPD header is usually much larger than the data field  24 ′ in the TCP header. To overcome this problem, the length of the field is sent over first and as subsequent TCP headers arrive they are assimilated and sent over to complete a UDP header. Stated differently, a plurality of TCP headers may be employed to generate one UPD header.  
         [0029]    Having explained a preferred embodiment of using a portion of the field  21  to flag or designate a TCP header for conversion to a UDP header, it will be understood and appreciated that the same flag or a similar flag could have been inserted in the data field  24 ′ and accomplish the same results. The fact that the field can vary from one of the fields  21  to one of the other unnumbered fields does not affect the result achieved by the controller  33 .  
         [0030]    A typical example of the utility of the present invention is a system which employs in an airborne platform the computer  28  which has assimilated from numerous other sources surveillance radar images, moving target indicator (MTI) images and all types of data which accompanies this information in textual form. As many as a thousand ground stations may be able to implement this information. However, it would be impossible to take particular information and send it by a point-to-point communication mode to each of the receiving stations and have sufficient bandwidth to disseminate the information in a reasonable length of time in which it could be utilized. In order to overcome this problem, the present invention not only prioritizes the information which is assimilated in point-to-point information format, but converts the information which may be disseminated in a point-to-multipoint format so that many or virtually all of the receiving stations may receive the most important information simultaneously and from time to time individual stations may receive point-to-point information which is not needed or should not be disseminated to all of the ground stations.  
         [0031]    Another example which is yet to be implemented is a food chain or department store or retail store that has a large number of outlets and desires to change the prices on a number of individual items throughout all of the outlets. Thus, the outlets will be treated as the ground stations and the central hub is the central headquarters CPU which disseminates the information to the retail outlets. The present system will allow the headquarters store to simultaneously change the price in the computers of the ground stations or outlets by equating a new price to the bar code scanned without changing the marked designated price on counter or display unit.  
         [0032]    Another example is a corporation or other entity that desires to send out meeting notices to all required attendees. The computer  28  can program the TCP data so that it is converted to UDP data and disseminated to the desired plural stations  39 ′ simultaneously.  
         [0033]    Since CPU  28  has updated information from its ground stations, it can dynamically change or prioritize the transmission of types of data to the individual stations in a point-to-multipoint mode.  
         [0034]    Having explained a preferred embodiment in which the IP destination address  11  and TCP formatted data may be converted to network destination IP addresses and UDP formatted data, respectively, it will be understood that other formats and fields may be employed to accomplish the same desired result.