Abstract:
A packet transfer system for transferring data from or to a plurality of terminals while sectioning the data into given data-length packets, the system having a communication system that has the plurality of terminals, a base station connected through a wireless line with the plurality of terminals and a switching office connected through one or more wired lines with the base station, the wired lines being of shared channels that the plurality of terminals can use commonly and a leased channel that one terminal can use exclusively. When the amount of data transferred from or to one of the plurality of terminals is greater than a predetermined value, one of the shared channels is assigned exclusively to the one of the plurality of terminals or the leased channel is assigned to the one of the plurality of terminals.

Description:
FIELD OF THE INVENTION 
     This invention relates to a system for transferring packet data. 
     BACKGROUND OF THE INVENTION 
     Packet transfer systems, where data are transferred within a wired section of communication network while being sectioned into given data-length packets each of which is provided with a destination code, are of a connectionless type that without establishing a line when calling a packet, packet data are transferred using shared channel and of a connection-oriented type that a leased channel is assigned to each user when calling a packet and then packet data are transferred using the leased channel. 
     FIG. 1 is an illustration showing a connectionless type packet transfer system. 
     As shown in FIG. 1, a communication system that the conventional connectionless type packet transfer system is applied is composed of multiple terminals  110   a  to  110   c,  a wireless base station  120  that is connected through wireless lines with the terminals  110   a  to  110   c,  and a packet switching office  130  that is connected through wired packet lines with the wireless base station  120 . The packet switching office  130  is connected with a network  140 , such as a packet network as a public network and PSTN as a circuit switched network. Also, in the packet switching office  130 , packet terminal equipment  135  to perform a Layer  2  protocol terminal function is provided, where the other Layer  2  protocol terminal function is performed by the terminals  110   a  to  110   c.    
     In the communication system using the connectionless type packet transfer system, all the lines between the wireless base station  120  and the packet switching office  130  are used as shared channels that the multiple terminals  110   a  to  110   c  can use commonly. So, through one channel, the transferring of packet data by the terminals  110   a  to  110   c  may be performed. 
     FIG. 2 is an illustration showing a connection-oriented type packet transfer system. 
     As shown in FIG. 2, a communication system that the conventional connection-oriented type packet transfer system is applied is similar to that in FIG.  1 . 
     In the communication system using the conventional connection-oriented type packet transfer system, when calling a packet, multiple channels between the wireless base station  120  and the packet switching office  130  are used as leased channels each of which only one of the terminals  110   a  to  110   c  can use, where the transferring of packet data by the terminals  110   a  to  110   c  can be performed using the leased channels assigned to the respective terminals  110   a  to  110   c.    
     However, in the conventional packet transfer systems, the following problems may occur. 
     (1) In the connectionless type packet transfer system, since one channel is used commonly by multiple users, the utilization efficiency per one channel is enhanced. However, the retransmission throughput for guaranteeing the packet data of multiple users at that channel must be reduced. 
     (2) In the connection-oriented type packet transfer system, since one channel is assigned to one user, the retransmission throughput at that channel is enhanced. However, since the leased channel is used exclusively by one user from calling to releasing of packet, the hard physical quantity must increase. 
     Also, when packet data are transferred intermittently, the leased channel will be established even when there is no data transferred. Therefore, the ineffective reserved hard resource must increase. Here, for the packet communications, the per-unit charging system (charging based on the amount of information transferred) is employed in place of the time charging system (charging based on the time during the line is used) for line switching. Therefore, in the above case, a wasteful cost will occur. 
     SUMMARY OF THE INVENTION 
     Accordingly, it is an object of the invention to provide a packet transfer system that packet data can be transferred efficiently without reducing the retransmission throughput of line and without increasing the hard physical quantity. 
     According to the invention, a packet transfer system for transferring data from a plurality of terminals while sectioning the data into given data-length packets, comprises: 
     a communication system that is composed of the plurality of terminals, a base station connected through a wireless line with the plurality of terminals and a switching office connected through one or more wired lines with the base station, the wired lines being composed of shared channels that the plurality of terminals can use commonly; 
     wherein when the amount of data transferred from one of the plurality of terminals is greater than a predetermined value, one of the shared channels is assigned exclusively to the one of the plurality of terminals and data transferred from the one of the plurality of terminals is transferred using only the one of the shared channels. 
     According to another aspect of the invention, a packet transfer system for transferring data to a plurality of terminals while sectioning the data into given data-length packets, comprises: 
     a communication system that is composed of the plurality or terminals, a base station connected through a wireless line with the plurality of terminals and a switching office connected through one or more wired lines with the base station, the wired lines being composed of shared channels that the plurality of terminals can use commonly; 
     wherein when the amount of data transferred to one of the plurality of terminals is greater than a predetermined value, one of the shared channels is assigned exclusively to the one of the plurality of terminals and data transferred to the one of the plurality of terminals is transferred using only the one of the shared channels. 
     According to another aspect of the invention, a packet transfer system for transferring data from a plurality of terminals while sectioning the data into given data-length packets, comprises: 
     a communication system that is composed of the plurality of terminals, a base station connected through a wireless line with the plurality of terminals and a stitching office connected through one or more wired lines with the base station, the wired lines being composed of shared channels that the plurality of terminals can use commonly and a leased channel that only one of the plurality of terminals can use; 
     wherein only when the amount of data transferred from one of the plurality of terminals is greater than a predetermined value, the leased channel is assigned to the one of the plurality of terminals and data transferred from the one of the plurality of terminals is transferred using the leased channel. 
     According to another aspect of the invention, a packet transfer system for transferring data to a plurality of terminals while sectioning the data into given data-length packets, comprises: 
     a communication system that is composed of the plurality of terminals, a base station connected through a wireless line with the plurality of terminals and a switching office connected through one or more wired lines with the base station, the wired lines being composed of shared channels that the plurality of terminals can use commonly and a leased channel that only one of the plurality of terminals can use; 
     wherein only when the amount of data transferred to one of the plurality of terminals is greater than a predetermined value, the leased channel is assigned to the one of the plurality of terminals and data transferred to the one of the plurality of terminals is transferred using the leased channel. 
     According to another aspect of the invention, a packer transfer system for transferring data from a plurality of terminals while sectioning the data into given data-length packets, comprises: 
     a communication system that is composed of the plurality of terminals, a base station connected through a wireless line with the plurality of terminals and a switching office connected through one or more wired lines with the base station, the wired lines being composed of shared channels that the plurality of terminals can use commonly; 
     wherein the base station is composed of means for counting packet data transferred from the plurality of terminals, the counting means being provided for each of the plurality of terminals, a mode switching means for switching the shared channels into a shared mode that the plurality of terminals can use commonly or a leased mode that one of the plurality of terminals can use exclusively, the mode switching means being provided for each of the shared channels, and a control means for comparing a count value of the counting means with a predetermined value and controlling the operation of the mode switching means based on the comparison result, wherein the control means, when the count value of the counting means is greater than the predetermined value, controls the mode switching means to switch one of the shared channels into the leased mode that concerned one of the plurality of terminals can use exclusively. 
     According to another aspect of the invention, a packet transfer system for transferring data from a plurality of terminals while sectioning the data into given data-length packets, comprises: 
     a communication system that is composed of the plurality of terminals, a base station connected through a wireless line with the plurality of terminals and a switching office connected through one or more wired lines with the base station, the wired lines being composed of shared channels that the plurality of terminals can use commonly and a leased channel that only one of the plurality of terminals can use; 
     wherein the base station is composed of means for counting packet data transferred from the plurality of terminals, the counting mean; being provided for each of the plurality of terminals, and a control means for comparing a count value of the counting means with a predetermined value and controlling the setting of the wired lines to the plurality of terminals based on the comparison result, wherein the control means, when the count value of the counting means is greater than the predetermined value, controls the leased channel to be set to concerned one of the plurality of terminals. 
     In this invention, when data transferred from or to a terminal is greater than a predetermined value, one of shared channels is assigned exclusively to the terminal and data is transferred from or to the terminal using only the assigned channel. 
     Thus, in normal packet transferring, the communications are performed using by the shared channel with leased mode, and when specific-calling traffic increases, one of shared channels is switched into a leased mode that only the specific calling uses the channel. Since only the specific calling is transferred using the channel, packet data can be transferred efficiently without reducing the retransmission throughput of line and without increasing the hard physical quantity. 
     Alternatively, when data transferred from or to a terminal is greater than a predetermined value, a leased channel that one terminal can use exclusively is assigned to the terminal and data is transferred from or to the terminal using only the leased channel. 
     Thus, in normal packet transferring, the communications are performed using by the shared channel with leased mode, and when specific calling traffic increases, the leased channel is newly assigned to the specific calling. Since only the specific calling is transferred using the leased channel, packet data can be transferred efficiently without reducing the retransmission throughput of line and without increasing the hard physical quantity. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     The invention will be explained in more detail in conjunction with the appended drawings, wherein: 
     FIG. 1 is an illustration showing a conventional connectionless type of packet transfer system, 
     FIG. 2 is an illustration showing a conventional connection-oriented type of packet transfer system, 
     FIG. 3 is an illustration showing a packet transfer system in a first preferred embodiment according to the invention, 
     FIG. 4 is a block diagram showing the composition of a wireless base station in FIG. 3, 
     FIG. 5 is a flow chart showing an operation of the packet transfer system in FIG. 3, 
     FIG. 6 is an illustration showing a packet transfer system in second preferred embodiment according to the invention, 
     FIG. 7 is a block diagram showing the composition of a wireless base station in FIG. 6, and 
     FIG. 8 is a flow chart showing an operation of the packet transfer system in FIG.  6 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The preferred embodiments of the invention will be explained below, referring to the drawings. 
     &lt;First Embodiment&gt; 
     FIG. 3 is an illustration showing a packet transfer system in the first preferred embodiment according to the invention. 
     The system in the first embodiment is, as shown in FIG. 3, is composed of multiple terminals  10   a  to  10   c,  a wireless base station that is connected through wireless lines with the terminals  10   a  to  10   c,  and a packet switching office  30  that is connected through wired packet lines with the wireless base station  20 . The packet switching office  30  is connected with a network  40 , such as a packet network as a public network and PSTN as a circuit switched network. Also, in the packet switching office  30 , packer terminal equipment to perform a Layer  2  protocol terminal function is provided, where the other Layer  2  protocol terminal function is performed by the terminals  10   a  to  10   c.    
     Although in FIG. 3 only the three terminals  10   a  to  10   c  are shown, the other several terminals exist. 
     In this embodiment, the wired lines connecting the wireless base station  20  with the packet switching office  30  are of a shared channel type that multiple terminals can use commonly. 
     Meanwhile, in the shared channels, channels equal to the sum of the number of users who use currently the packet transfer and the number of a predetermined percentage of users (non-packet-transfer users) who have the packet transfer contract and do not use currently the packet transfer are established. They are always ready to transfer packets. The total number is predetermined in reference to the number of peak-hour calls on the previous day. 
     Also, the shared channels in this embodiment can be set to a shared mode that multiple terminals can use the channel commonly and a leased mode that one terminal uses the channel exclusively. 
     FIG. 4 is a block diagram showing a composition of the wireless base station  20  in FIG.  3 . 
     As shown in FIG. 4, the wireless base station  20  is composed of counters  21   a  to  21   c  each of which counts packet data transferred from the corresponding one of the terminals  10   a  to  10   c,  mode switching sections  23 - 1  to  23 -n that are provided for the respective shared channels and switch the mode of shared channel into the shared mode or leased mode, and a control section  22  that compares the count values of the counters  21   a  to  21   c  with a predetermined value and controls the operation of the mode switching sections  23 - 1  to  23 -n based on the comparison result. 
     The operation or the packet transfer system thus composed is explained below. 
     FIG. 5 is a flow chart showing the operation of the packet transfer system in FIG.  3 . 
     When the packet transfer at the terminals  10   a  to  10   c  starts (step S 1 ), the counters  21   a  to  21   c  of the wireless base station  20  count packet data transferred from the terminals  10   a  to  10   c.    
     Then, in the control section  22  of the wireless base station  20 , the count values at the counters  21   a  to  21   c  are compared with a predetermined value, and it is judged whether the packet data transferred from the terminals  10   a  to  10   c  are greater than the predetermined value or not (step S 2 ). Meanwhile, to each of packet data transferred from the terminals, a user ID to indicate each property is added. Also, the predetermined value, which is the criteria of judgement, can be changed according to the number of callings. 
     When it is judged that the packet data transferred from one of the terminals  10   a  to  10   c  at step S 2  is greater than the predetermined value, through the shared channel, the control section  22  requests for the packet switching office  30  to set one of the shared channels into the leased mode and to assign it to that terminal (step S 3 ). For example, in this embodiment, it is assumed that the packet data transferred from the terminal  10   c  is greater than the predetermined value. In this case, through the shared channel, the control section  22  of the wireless base station  20  requests for the packet switching office  30  to set one of the shared channels into the leased mode and to assign it to the terminal  10   c.  Meanwhile, the channel used in requesting for assigning it to the terminal  10   c  is different From the channel used in transferring that request from the control section  22  of the wireless base station  20  to the packet switching office  30 . 
     Then, in the packet switching office  30 , it is judged whether one of the shared channels is allowed to be set to the leased mode and to be assigned to the terminal  10   c  or not (step S 4 ). 
     When at step S 4  it is judged that one of the shared channels is allowed to be set to the leased mode and to be assigned to the terminal  10   c,  this judgement is sent to the control section  22  of the wireless base station  20 . Then, by the control of the control section  22 , of the mode switching sections  23 - 1  to  23 -n, a mode switching section provided for the shared channel to be set to the leased mode is controlled to operate. Thereby, the concerned shared channel is met to the leased mode, and then the packet data is transferred from the terminal  10   c,  using the shared channel set to the leased mode (step S 5 ). 
     On the other hand, when at step S 2  it is judged that packet data transferred from the terminal  10   c  is fewer than the predetermined value, or when at step S 4  it is judged that one of the shared channels is not allowed to be set to the leased mode and to be assigned to the terminal  10   c,  the packet data is transferred using the shared channel of shared mode (step S 6 ). Meanwhile, in this embodiment, since the packet data transferred from the terminals  10   a,    10   b  are fewer than the predetermined value, for the terminals  10   a,    10   b,  the packet data are transferred using the shared channel of shared mode. 
     Also, in transferring packet data from the packet switching office  30  to the wireless base station  20 , similar operations to those described above are conducted. In this case, the Layer  2  protocol termination is conducted between the terminals  10   a  to  10   c  and the packet terminal equipment  35 . The retransmission control for when retransmission is required including the wireless section is conducted between the Layer  2  protocol, for each user ID. This user ID is administered by an anchor packet switching office (not shown) where ID does not change even when a hand-over etc. occurs. 
     After completing the transferring of packet data, the number of shared channels set to the shared mode is detected, and based on the channel number detected, the shared channel set to the leased mode is returned to the shared mode or released. 
     &lt;Second Embodiment&gt; 
     FIG. 6 is an illustration showing a packet transfer system in the second preferred embodiment according to the invention. FIG. 7 is a block diagram showing a composition of a wireless base station  50  in FIG.  6 . 
     As shown in FIGS. 6 and 7, this embodiment has a composition similar to that in FIG. 3, except the wireless base station  50 . The wired lines to connect the wireless base station  50  and the packet switching office  30  are composed of shared channels that multiple terminals can use commonly and a leased channel that one terminal can use exclusively. 
     Also, the wireless base station  50  in this embodiment is, as shown in FIG. 7, composed of counters  51   a  to  51   c  each of which counts packet data transferred from the corresponding one of the terminals  10   a  to  10   c,  and a control section  52  that compares the count values of the counters  51   a  to  51   c  with a predetermined value and controls the setting of the shared channels and leased channel based on the comparison result. 
     The operation of the packet transfer system in this embodiment is explained below. 
     FIG. 8 is a flow chart showing the operation of the packet transfer system in FIG.  6 . 
     When the packet transfer at the terminals  10   a  to  10   c  starts (step S 1 ) the counters  51   a  to  51   c  of the wireless base station  50  count packet data transferred from the terminals  10   a  to  10   c.    
     Then, in the control section  52  of the wireless base station  50 , the count values at the counters  51   a  to  51   c  are compared with a predetermined value, and it is judged whether the packet data transferred from the terminals  10   a  to  10   c  are greater than the predetermined value or not (step  312 ). Meanwhile, to each of packet data transferred from the terminals, a user ID to indicate each property is added. Also, the predetermined value, which is the criteria of judgement, can be changed according to the number of callings. 
     When at step S 2  it is judged that the packet data transferred from one of the terminals  10   a  to  10   c  is greater than the predetermined value, the control section  52  requests for the packet switching office  30  to assign the leased channel to that terminal (step S 13 ). For example, in this embodiment, it is assumed that the packet data transferred from the terminal  10   c  is greater than the predetermined value. In this case, through the shared channel, the control section  52  of the wireless base station  50  requests for the packet switching office  30  to assign the leased channel to the terminal  10   c.    
     Then, in the packet switching office  30 , it is judged whether the leased channel is allowed to be assigned to the terminal  10   c  or not (step S 14 ). 
     When at step S 14  it is judged that the leased channel is allowed to be assigned to the terminal  10   c , this judgement is sent to the control section  52  of the wireless base station  50 . Then, by the control of the control section  52 , the leased channel is set to the terminal  10   c , and then the packet data is transferred from the terminal  10   c , using the leased channel (step S 15 ). Here, when the packet data is transferred using the leased channel, since the terminal and the leased channel are corresponding to each other in one-to-one relation, no user ID is necessary to add to the packet data. 
     On the other hand, when at step S 12  it is judged that packet data transferred from the terminal  10   c  is fewer than the predetermined value, or when at step S 14  it is judged that the leased channel is not allowed to be assigned to the terminal  10   c , the packet data is transferred using the shared channel (step S 16 ). Meanwhile, in this embodiment, since the packet data transferred from the terminals  10   a ,  10   b  are fewer than the predetermined value, for the terminals  10   a ,  10   b , the packet data are transferred using the shared channel. 
     Also, in transferring packet data from the packet switching office  30  to the wireless base station  50 , similar operations to those described above are conducted. In this case, the Layer  2  protocol termination is conducted between the terminals  10   a  to  10   c  and the packet terminal equipment  35 . The retransmission control for when retransmission is required including the wireless section is conducted between the Layer  2  protocol, for each user ID. This user ID is administered by an anchor packet switching office (not shown) where ID does not change even when a hand-over etc. occurs. 
     After completing the transferring of packet data, the leased channel is released. 
     &lt;Third Embodiment&gt; 
     In the first and second embodiments described above, at the wireless base station, it is judged whether the packet data transferred from each of the terminals  10   a  to  10   c  is greater than the predetermined value. However, when the packer data transferred from each of the terminals  10   a  to  10   c  is greater than the predetermined value, at the terminals  10   a  to  10   c  such information may be added to the packet data and then transferred to the wireless base station with the packet data. Then, the control section of the wireless base station may detect the information, and based on the information the mode switching of shared channel or the setting of leased channel can be performed. 
     For such a case, the counters  21   a  to  21   c  and  51   a  to  51   c  are not necessary. The information about whether the packet data transferred from each of the terminals  10   a  to  10   c  is greater than the predetermined value is sent directly to the control section  22 ,  52  from tho terminals  10   a  to  10   c . Based an the information, the control section  22 ,  52  operates. 
     Advantages of the Invention 
     (1) When data transferred from or to the terminal is greater than a predetermined value, one of shared channels is assigned exclusively to the terminal and the data transferred from or to the terminal is transferred using only the assigned channel. Therefore, without reducing the retransmission throughput of line and without increasing the hard physical quantity, the packet data can be transferred efficiently. 
     (2) When data transferred from or to the terminal is greater than a predetermined value, a leased channel that only one terminal can use is assigned to the terminal and the data transferred from or to the terminal is transferred using only the leased channel. Therefore, like effect described above can be obtained. 
     Also, since no user ID is necessary to add to the packet data, the data transfer in wired section can be made further efficient. 
     Although the invention has been described with respect to specific embodiment for complete and clear disclosure, the appended claims are not to be thus limited but are to be construed as embodying all modification and alternative constructions that may be occurred to one skilled in the art which fairly fall within the basic teaching here is set forth.