Abstract:
A transmitting direct mode communication apparatus, a receiving direct mode communication apparatus and a communication path switching method thereof are provided. The transmitting direct mode communication apparatus and the receiving direct mode communication apparatus maintain a backend network connection, and communicate with each other via a direct communication connection. The transmitting direct mode communication apparatus and the receiving direct mode communication apparatus are capable of switching the communication to backend network connection rapidly and seamlessly for transmitting data normally after the direct communication connection failed.

Description:
This application claims the benefit of U.S. Provisional Application Ser. No. 61/757,588 filed on Jan. 28, 2013, which is hereby incorporated by reference in its entirety. 
    
    
     CROSS-REFERENCES TO RELATED APPLICATIONS 
     Not applicable. 
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention relates to a transmitting direct mode communication apparatus, a receiving direct mode communication apparatus and communication path switching methods thereof. More particularly, the transmitting direct mode communication apparatus, the receiving direct mode communication apparatus and the communication path switching methods thereof accomplish switching of the communication path in a lower layer. 
     Descriptions of the Related Art 
     In the conventional Long Term Evolution (LTE) network technology, mobile apparatuses can communicate with each other directly through a specific protocol. For the direct mode communication apparatuses in such a direct mode communication system, firstly infrastructure connections are created via a backend network and then, when the direct mode communication apparatuses enter into each other&#39;s communication coverage and create direct communication connections therebetween, data can be exchanged via the direct mode communication connection. 
     Further speaking, a mobile apparatus which is to transmit data in an LTE network must categorize the data packets through use of a packet filter and, according to one of a source address, a source TCP/UDP port number, a destination address, a destination TCP/UDP port number of each packet and a combination thereof, determine a quality of service (QoS) of the data packets and determine which data radio bearer will be used for data transmission. It should be noted that, in LTE network, the mobile apparatus may have many activated packet filters at the same time, and these packet filters are usually collectively termed as Traffic Flow Template. 
     Unfortunately, in LTE network, direct mode connection is less stable than backend network connection. Therefore, data must still be transmitted via the infrastructure connection of the backend network when the direct communication connection between the direct mode communication apparatuses is interrupted. However, no primary connection switching mechanism is available in the conventional technology, so usually the infrastructure connection of the backend network must be reactivated in order to continue the data transmission when the direct communication connection between the direct mode communication apparatuses is interrupted. 
     Moreover, although management of communications across connections between the direct mode communication apparatuses can be accomplished by the application-layer session initiation protocol, the procedure is very complex and packet loss tends to occur due to long communication interruption time during the connection switching. 
     Accordingly, there is an urgent need in the art to provide a solution capable of switching the connection between direct mode communication apparatuses in the LTE network technology while avoiding the shortcomings of the complex connection switching procedure and the long interruption time during the connection switching 
     SUMMARY OF THE INVENTION 
     The primary objective of the present invention is to provide a communication path switching method for a transmitting direct mode communication apparatus. The transmitting direct mode communication apparatus comprises a packet processing module and a transceiver, and maintains a backend network connection with a receiving direct mode communication apparatus via a backend network server. The communication path switching method comprises: (a) enabling the packet processing module to create a direct communication connection with the receiving direct mode communication apparatus via the transceiver; (b) enabling the packet processing module to determine that the direct communication connection is interrupted; and (c) enabling the packet processing module to switch the communication with the receiving direct mode communication apparatus from the direct communication connection to the backend network connection. 
     To achieve the aforesaid objective, the present invention further provides a transmitting direct mode communication apparatus, which maintains a backend network connection with a receiving direct mode communication apparatus via a backend network server. The transmitting direct mode communication apparatus comprises a transceiver and a packet processing module. The packet processing module is configured to create a direct communication connection with the receiving direct mode communication apparatus via the transceiver. The packet processing module is further configured to determine that the direct communication connection is interrupted and, through the transceiver, switch the communication with the receiving direct mode communication apparatus from the direct communication connection to the backend network connection. 
     To achieve the aforesaid objective, the present invention further provides a communication path switching method for a receiving direct mode communication apparatus. The receiving direct mode communication apparatus comprises a packet processing module and a transceiver, and maintains a backend network connection with a transmitting direct mode communication apparatus via a backend network server. The communication path switching method comprises: (a) enabling the packet processing module to create a direct communication connection with the transmitting direct mode communication apparatus via the transceiver; and (b) enabling the packet processing module to communicate with the transmitting direct mode communication apparatus via the backend network connection after the direct communication connection is interrupted. 
     To achieve the aforesaid objective, the present invention further provides a receiving direct mode communication apparatus, which maintains a backend network connection with a transmitting direct mode communication apparatus via a backend network server. The receiving direct mode communication apparatus comprises a transceiver and a packet processing module. The packet processing module is configured to create a direct communication connection with the transmitting direct mode communication apparatus via the transceiver, and communicate with the transmitting direct mode communication apparatus via the backend network connection after the direct communication connection is interrupted. 
     The detailed technology and preferred embodiments implemented for the subject invention are described in the following paragraphs accompanying the appended drawings for people skilled in this field to well appreciate the features of the claimed invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  is a schematic view of a direct mode communication system according to a first embodiment of the present invention; 
         FIG. 1B  is a block diagram of a transmitting direct mode communication apparatus and a receiving direct mode communication apparatus according to the first embodiment of the present invention; 
         FIG. 2A  is a schematic view of a direct mode communication system according to a second embodiment of the present invention; 
         FIG. 2B  is a block diagram of a transmitting direct mode communication apparatus and a receiving direct mode communication apparatus according to the second embodiment of the present invention; 
         FIG. 3A  is a schematic view of a direct mode communication system according to a third embodiment of the present invention; 
         FIG. 3B  is a block diagram of a transmitting direct mode communication apparatus and a receiving direct mode communication apparatus according to the third embodiment of the present invention; 
         FIG. 4A  is a schematic view of a direct mode communication system according to a fourth embodiment of the present invention; 
         FIG. 4B  is a block diagram of a transmitting direct mode communication apparatus and a receiving direct mode communication apparatus according to the fourth embodiment of the present invention; 
         FIG. 5A  is a schematic view of a direct mode communication system according to a fifth embodiment of the present invention; 
         FIG. 5B  is a block diagram of a transmitting direct mode communication apparatus and a receiving direct mode communication apparatus according to the fifth embodiment of the present invention; 
         FIG. 6  is a flowchart diagram of a communication path switching method according to a sixth embodiment of the present invention; 
         FIGS. 7A-7B  illustrate a flowchart diagram of a communication path switching method according to a seventh embodiment of the present invention; 
         FIGS. 8A-8B  illustrate a flowchart diagram of a communication path switching method according to an eighth embodiment of the present invention; 
         FIGS. 9A-9B  illustrate a flowchart diagram of a communication path switching method according to a ninth embodiment of the present invention; and 
         FIGS. 10A-10B  illustrate a flowchart diagram of a communication path switching method according to a tenth embodiment of the present invention. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     In the following description, the present invention will be explained with reference to embodiments thereof. However, these embodiments are not intended to limit the present invention to any specific environment, applications or particular implementations described in these embodiments. Therefore, description of these embodiments is only for purpose of illustration rather than to limit the present invention. It should be appreciated that, in the following embodiments and the attached drawings, elements unrelated to the present invention are omitted from depiction; and dimensional relationships among individual elements in the attached drawings are illustrated only for ease of understanding, but not to limit the actual scale. 
     Refer to  FIG. 1A  and  FIG. 1B  together.  FIG. 1A  is a schematic view of a direct mode communication system  1  according to a first embodiment of the present invention. The direct mode communication system  1  comprises a transmitting direct mode communication apparatus  11 , a receiving direct mode communication apparatus  13  and a backend network server  15 . The transmitting direct mode communication apparatus  11  maintains a backend network connection  10  with the receiving direct mode communication apparatus  13  via the backend network server  15 . 
       FIG. 1B  is a block diagram of the transmitting direct mode communication apparatus  11  and the receiving direct mode communication apparatus  13  according to the first embodiment of the present invention. The transmitting direct mode communication apparatus  11  comprises a transceiver  111  and a packet processing module  113 . The receiving direct mode communication apparatus  13  comprises a transceiver  131  and a packet processing module  133 . Interactions among the individual elements will be further described hereinbelow. 
     Firstly, the packet processing module  113  of the transmitting direct mode communication apparatus  11  creates a direct communication connection  12  with the receiving direct mode communication apparatus  13  via the transceiver  111 . In other words, the packet processing module  133  of the receiving direct mode communication apparatus  13  creates the direct communication connection  12  with the transmitting direct mode communication apparatus  11  via the transceiver  113 . Then, when the direct communication connection  12  between the transmitting direct mode communication apparatus  11  and the receiving direct mode communication apparatus  13  is interrupted due to external factors, the packet processing module  113  of the transmitting direct mode communication apparatus  11  can directly detect and determine that the direct communication connection  12  is interrupted. 
     Then, the packet processing module  113  of the transmitting direct mode communication apparatus  11  can switch the communication of the transmitting direct mode communication apparatus  11  and the receiving direct mode communication apparatus  13  from the direct communication connection  12  back to the backend network connection  10  that has already been created. On the other hand, the packet processing module  131  of the receiving direct mode communication apparatus  13  communicates with the transmitting direct mode communication apparatus  11  via the backend network connection  10  when the direct communication connection  12  is interrupted. In this way, switching of the connection can be achieved between the direct mode communication apparatuses to maintain continuity of the data transmission. 
     It shall be particularly appreciated that, in the first embodiment, the receiving direct mode communication apparatus  13  can switch the communication with the transmitting direct mode communication apparatus  11  from the direct communication connection  12  back to the backend network connection  10  via the packet processing module  131 . Further, the receiving direct mode communication apparatus  13  may also set two internal packet processing paths therein, and then determine a processing path of the packet according to a logical channel ID (LCID) that is set in a Media Access Control (MAC) Layer header. Therefore, network packets incoming from either of the connections (the direct communication connection and the backend network connection) can be collected and then processed together. However, what described above is not intended to limit the way in which the receiving direct mode communication apparatus of the present invention processes the packet. 
     Referring to  FIG. 2A  and  FIG. 2B  together.  FIG. 2A  is a schematic view of a direct mode communication system  2  according to a second embodiment of the present invention. The direct mode communication system  2  comprises a transmitting direct mode communication apparatus  21 , a receiving direct mode communication apparatus  23  and a backend network server  25 . The transmitting direct mode communication apparatus  21  maintains a backend network connection  20  with the receiving direct mode communication apparatus  23  via the backend network server  25 . 
       FIG. 2B  is a block diagram of the transmitting direct mode communication apparatus  21  and the receiving direct mode communication apparatus  23  according to the second embodiment of the present invention. The transmitting direct mode communication apparatus  21  comprises a transceiver  211  and a packet processing module  213 . The packet processing module  213  further comprises a backend network address processing unit  2131 , a direct mode communication network address processing unit  2133 , a backend network traffic filter template (TFT) processing unit  2135  and a direct mode communication network TFT processing unit  2137 . 
     On the other hand, the receiving direct mode communication apparatus  23  comprises a transceiver  231  and a packet processing module  233 . The packet processing module  233  further comprises a backend network address processing unit  2333  and a direct mode communication network address processing unit  2331 . The second embodiment mainly details the packet transmission and switching processes for a connection of a different form. Interactions among the individual elements will be further described hereinbelow. 
     Firstly, the packet processing module  213  of the transmitting direct mode communication apparatus  21  creates a direct communication connection  22  with the receiving direct mode communication apparatus  23  via the transceiver  211 . In other words, the packet processing module  233  of the receiving direct mode communication apparatus  23  creates the direct communication connection  22  with the transmitting direct mode communication apparatus  21  via the transceiver  213 . 
     Then, before a first network packet  210  is transmitted by the transmitting direct mode communication apparatus  21  to the receiving direct mode communication apparatus  23 , the backend network address processing unit  2131  of the transmitting direct mode communication apparatus  21  receives the first network packet  210  from the TCP/UDP layer and transmits internally the first network packet  210  to the backend network TFT processing unit  2135 . The first network packet  210  comprises a backend network source address Badd 20  and a backend network destination address Badd 22 . 
     Next, the backend network TFT processing unit  2135  internally forwards the first network packet  210  to the direct mode communication network address processing unit  2133 . Then, the backend network source address Badd 20  and the backend network destination address Badd 22  of the first network packet  210  are transformed by the direct mode communication network address processing unit  2133  into a direct mode communication network source address Dadd 20  and a direct mode communication network destination address Dadd 22  respectively. 
     After the network addresses of the first network packet  210  have been transformed by the direct mode communication network address processing unit  2133 , the direct mode communication network TFT processing unit  2137  transmits the first network packet  210  to the receiving direct mode communication apparatus  23  through the transceiver  211  and via the direct communication connection  22  according to one of the direct mode communication network source address Dadd 20 , the direct mode communication network destination address Dadd 22  and a combination thereof (i.e., according to the direct mode communication network source address Dadd 20  or the direct mode communication network destination address Dadd 22  separately or according to a combination of the both). 
     On the other hand, the direct mode communication network address processing unit  2331  of the receiving direct mode communication apparatus  23  receives the first network packet  210  from the transmitting direct mode communication apparatus  21  through the transceiver  231  and via the direct mode communication connection  22 , and transforms the direct mode communication network source address Dadd 20  and the direct mode communication network destination address Dadd 22  of the first network packet  210  into the backend network source address Badd 20  and the backend network destination address Badd 22  respectively. 
     After the network addresses of the first network packet  210  have been processed by the direct mode communication network address processing unit  2331 , the backend network address processing unit  2333  analyzes the first network packet  210  according to one of the backend network source address Badd 20 , the backend network destination address Badd 22  and a combination thereof (i.e., according to the backend network source address Badd 20  or the backend network destination address Badd 22  separately or according to a combination of the both) and forwards the first network packet  210  to the TCP/UDP layer for subsequent processing. 
     Then when the packet processing module  213  of the transmitting direct mode communication apparatus  21  detects and determines that the direct communication connection  22  is interrupted and the transmitting direct mode communication apparatus  21  is to transmit a second network packet  212  to the receiving direct mode communication apparatus  23 , the backend network address processing unit  2131  of the transmitting direct mode communication apparatus  21  transmits the second network packet  212  to the backend network TFT processing unit  2135 . Similarly, the second network packet  212  comprises the backend network source address Badd 20  and the backend network destination address Badd 22 . 
     Because the direct communication connection  22  has been interrupted, the backend network TFT processing unit  2135  of the transmitting direct mode communication apparatus  21  transmits the second network packet  212  to the receiving direct mode communication apparatus  23  through the transceiver  211  and via the backend network connection  20  according to one of the backend network source address Badd 20 , the backend network destination address Badd 22  and a combination thereof (i.e., according to the backend network source address Badd 20  or the backend network destination address Badd 22  separately or according to a combination of the both). 
     Similarly, after the direct communication connection  22  is interrupted, the backend network address processing unit  2333  of the receiving direct mode communication apparatus  23  receives the second network packet  212  from the transmitting direct mode communication apparatus  21  through the transceiver  231  and via the backend network connection  20 , and analyzes the second network packet  212  according to one of the backend network source address Badd 20 , the backend network destination address Badd 22  and a combination thereof (i.e., according to the backend network source address Badd 20  or the backend network destination address Badd 22  separately or according to a combination of the both) directly. Then, the second network packet  212  is forwarded to the TCP/UDP layer for subsequent processing. 
     It shall be particularly appreciated that, besides the source address and the destination address, the network packet of the aforesaid embodiment may also comprise related information such as a source network address port number and a destination network address port number; and appropriate use of network information will be readily appreciated by those skilled in the art upon reviewing the aforesaid descriptions. 
     In addition, in LTE network, the above address translation method is usually IP-in-IP Tunneling method or Network Address Translation (NAT) method. In NAT method, the source address, the destination address, the source network address port number and the destination network address port number may be changed after the packets are translated. However, it is not to limit or influence the present invention no matter IP-in-IP Tunneling method or NAT method is applied (or any possible address translation method). 
     Refer to  FIG. 3A  and  FIG. 3B  together.  FIG. 3A  is a schematic view of a direct mode communication system  3  according to a third embodiment of the present invention. The direct mode communication system  3  comprises a transmitting direct mode communication apparatus  31 , a receiving direct mode communication apparatus  33  and a backend network server  35 . The transmitting direct mode communication apparatus  31  maintains a backend network connection  30  with the receiving direct mode communication apparatus  33  via the backend network server  35 . 
       FIG. 3B  is a block diagram of the transmitting direct mode communication apparatus  31  and the receiving direct mode communication apparatus  33  according to the third embodiment of the present invention. The transmitting direct mode communication apparatus  31  comprises a transceiver  311  and a packet processing module  313 . The packet processing module  313  further comprises a network address processing unit  3131 , a backend network TFT processing unit  3135  and a direct mode communication network TFT processing unit  3137 . 
     On the other hand, the receiving direct mode communication apparatus  33  comprises a transceiver  331  and a packet processing module  333 . The packet processing module  333  further comprises a backend network address processing unit  3331 . The third embodiment mainly details the packet transmission and switching processes for a connection of a different form. Interactions among the individual elements will be further described hereinbelow. 
     Firstly, the packet processing module  313  of the transmitting direct mode communication apparatus  31  creates a direct communication connection  32  with the receiving direct mode communication apparatus  33  via the transceiver  311 . In other words, the packet processing module  333  of the receiving direct mode communication apparatus  33  creates the direct communication connection  32  with the transmitting direct mode communication apparatus  31  via the transceiver  313 . 
     Then, before a first network packet  310  is transmitted by the transmitting direct mode communication apparatus  31  to the receiving direct mode communication apparatus  33 , the backend network address processing unit  3131  of the transmitting direct mode communication apparatus  31  receives the first network packet  310  from the TCP/UDP layer and transmits internally the first network packet  310  to the direct mode communication network TFT processing unit  3137 . The first network packet  310  comprises a backend network source address Badd 30  and a backend network destination address Badd 32 . 
     Then, the direct mode communication network TFT processing unit  3137  transmits the first network packet  310  to the receiving direct mode communication apparatus  33  through the transceiver  311  and via the direct communication connection  32  according to one of the backend network source address Badd 30 , the backend network destination address Badd 32  and a combination thereof (i.e., according to the backend network source address Badd 30  or the backend network destination address Badd 32  separately or according to a combination of the both). 
     On the other hand, the backend network address processing unit  3331  of the receiving direct mode communication apparatus  33  receives the first network packet  310  from the transmitting direct mode communication apparatus  31  through the transceiver  331  and via the direct mode communication connection  32 , analyzes the first network packet  310  according to one of the backend network source address Badd 30 , the backend network destination address Badd 32  and a combination thereof (i.e., according to the backend network source address Badd 30  or the backend network destination address Badd 32  separately or according to a combination of the both) and forwards the first network packet  310  to the TCP/UDP layer for subsequent processing. 
     Then when the packet processing module  313  of the transmitting direct mode communication apparatus  31  detects and determines that the direct communication connection  32  is interrupted and the transmitting direct mode communication apparatus  31  is to transmit a second network packet  312  to the receiving direct mode communication apparatus  33 , the backend network address processing unit  3131  of the transmitting direct mode communication apparatus  31  transmits the second network packet  312  to the backend network TFT processing unit  3135 . Similarly, the second network packet  312  comprises the backend network source address Badd 30  and the backend network destination address Badd 32 . 
     Because the direct communication connection  32  has been interrupted, the backend network TFT processing unit  3135  of the transmitting direct mode communication apparatus  31  transmits the second network packet  312  to the receiving direct mode communication apparatus  33  through the transceiver  311  and via the backend network connection  30  according to one of the backend network source address Badd 30 , the backend network destination address Badd 32  and a combination thereof (i.e., according to the backend network source address Badd 30  or the backend network destination address Badd 32  separately or according to a combination of the both). 
     Similarly, after the direct communication connection  32  is interrupted, the backend network address processing unit  3331  of the receiving direct mode communication apparatus  33  receives the second network packet  312  from the transmitting direct mode communication apparatus  31  through the transceiver  331  and via the backend network connection  30 , analyzes the second network packet  312  according to one of the backend network source address Badd 30 , the backend network destination address Badd 32  and a combination thereof (i.e., according to the backend network source address Badd 30  or the backend network destination address Badd 32  separately or according to a combination of the both) directly, and forwards the second network packet  312  to the TCP/UDP layer for subsequent processing. 
     It shall be particularly appreciated that, in the third embodiment, both the backend network address processing unit  3131  of the transmitting direct mode communication apparatus  31  and the backend network address processing unit  3331  of the receiving direct mode communication apparatus  33  have the capability of multi-homed IP processing so that network addresses can be transformed when the backend network source address Badd 30  and the backend network destination address Badd 32  belong to different domains. 
     Refer to  FIG. 4A  and  FIG. 4B  together.  FIG. 4A  is a schematic view of a direct mode communication system  4  according to a fourth embodiment of the present invention. The direct mode communication system  4  comprises a transmitting direct mode communication apparatus  41 , a receiving direct mode communication apparatus  43  and a backend network server  45 . The transmitting direct mode communication apparatus  41  maintains a backend network connection  40  with the receiving direct mode communication apparatus  43  via the backend network server  45 . 
       FIG. 4B  is a block diagram of the transmitting direct mode communication apparatus  41  and the receiving direct mode communication apparatus  43  according to the fourth embodiment of the present invention. The transmitting direct mode communication apparatus  41  comprises a transceiver  411  and a packet processing module  413 . The packet processing module  413  further comprises a backend network address processing unit  4131 , a direct mode communication network address processing unit  4133 , a backend network TFT processing unit  4135  and a direct mode communication network TFT processing unit  4137 . 
     On the other hand, the receiving direct mode communication apparatus  43  comprises a transceiver  431  and a packet processing module  433 . The packet processing module  433  further comprises a backend network address processing unit  4333  and a direct mode communication network address processing unit  4331 . The fourth embodiment mainly details the packet transmission and switching processes for a connection of a different form. Interactions among the individual elements will be further described hereinbelow. 
     Firstly, the packet processing module  413  of the transmitting direct mode communication apparatus  41  creates a direct communication connection  42  with the receiving direct mode communication apparatus  43  via the transceiver  411 . In other words, the packet processing module  433  of the receiving direct mode communication apparatus  43  creates the direct communication connection  42  with the transmitting direct mode communication apparatus  41  via the transceiver  413 . 
     Then, before a first network packet  410  is transmitted by the transmitting direct mode communication apparatus  41  to the receiving direct mode communication apparatus  43 , the backend network address processing unit  4131  of the transmitting direct mode communication apparatus  41  receives the first network packet  410  from the TCP/UDP layer and transmits internally the first network packet  410  to the direct mode communication network address processing unit  4133 . The first network packet  410  comprises a backend network source address Badd 40  and a backend network destination address Badd 42 . 
     Then, the backend network source address Badd 40  and the backend network destination address Badd 42  of the first network packet  410  are directly transformed by the direct mode communication network address processing unit  4133  into a direct mode communication network source address Dadd 40  and a direct mode communication network destination address Dadd 44  respectively. 
     After the network addresses of the first network packet  410  have been transformed by the direct mode communication network address processing unit  4133 , the direct mode communication network TFT processing unit  4137  transmits the first network packet  410  to the receiving direct mode communication apparatus  43  through the transceiver  411  and via the direct communication connection  42  according to one of the direct mode communication network source address Dadd 40 , the direct mode communication network destination address Dadd 42  and a combination thereof (i.e., according to the direct mode communication network source address Dadd 40  or the direct mode communication network destination address Dadd 42  separately or according to a combination of the both). 
     On the other hand, the direct mode communication network address processing unit  4331  of the receiving direct mode communication apparatus  43  receives the first network packet  410  from the transmitting direct mode communication apparatus  41  through the transceiver  431  and via the direct mode communication connection  42 , and transforms the direct mode communication network source address Dadd 40  and the direct mode communication network destination address Dadd 42  of the first network packet  410  into the backend network source address Badd 40  and the backend network destination address Badd 42  respectively. 
     After the network addresses of the first network packet  410  have been processed by the direct mode communication network address processing unit  4331 , the backend network address processing unit  4333  analyzes the first network packet  410  according to one of the backend network source address Badd 40 , the backend network destination address Badd 42  and a combination thereof (i.e., according to the backend network source address Badd 40  or the backend network destination address Badd 42  separately or according to a combination of the both) and forwards the first network packet  410  to the TCP/UDP layer for subsequent processing. 
     Then when the packet processing module  413  of the transmitting direct mode communication apparatus  41  detects and determines that the direct communication connection  42  is interrupted and the transmitting direct mode communication apparatus  41  is to transmit a second network packet  412  to the receiving direct mode communication apparatus  43 , the backend network address processing unit  4131  of the transmitting direct mode communication apparatus  41  transmits the second network packet  412  to the backend network TFT processing unit  4135 . Similarly, the second network packet  412  comprises the backend network source address Badd 40  and the backend network destination address Badd 42 . 
     Because the direct communication connection  42  has been interrupted, the backend network TFT processing unit  4135  of the transmitting direct mode communication apparatus  41  transmits the second network packet  412  to the receiving direct mode communication apparatus  43  through the transceiver  411  and via the backend network connection  40  according to one of the backend network source address Badd 40 , the backend network destination address Badd 42  and a combination thereof (i.e., according to the backend network source address Badd 40  or the backend network destination address Badd 42  separately or according to a combination of the both). 
     Similarly, after the direct communication connection  42  is interrupted, the backend network address processing unit  4333  of the receiving direct mode communication apparatus  43  receives the second network packet  412  from the transmitting direct mode communication apparatus  41  through the transceiver  431  and via the backend network connection  40 , and analyzes the second network packet  412  according to one of the backend network source address Badd 40 , the backend network destination address Badd 42  and a combination thereof (i.e., according to the backend network source address Badd 40  or the backend network destination address Badd 42  separately or according to a combination of the both) directly. Then, the second network packet  412  is forwarded to the TCP/UDP layer for subsequent processing. 
     Refer to  FIG. 5A  and  FIG. 5B  together.  FIG. 5A  is a schematic view of a direct mode communication system  5  according to a fifth embodiment of the present invention. The direct mode communication system  5  comprises a transmitting direct mode communication apparatus  51 , a receiving direct mode communication apparatus  53  and a backend network server  55 . The transmitting direct mode communication apparatus  51  maintains a backend network connection  50  with the receiving direct mode communication apparatus  53  via the backend network server  55 . 
       FIG. 5B  is a block diagram of the transmitting direct mode communication apparatus  51  and the receiving direct mode communication apparatus  53  according to the fifth embodiment of the present invention. The transmitting direct mode communication apparatus  51  comprises a transceiver  511  and a packet processing module  513 . The packet processing module  513  further comprises a TFT processing unit  5131 , a dual-mode Packet Data Convergence Protocol (PDCP) processing unit  5133  and a dual-mode Radio Link Control (RLC) processing unit  5135 . 
     On the other hand, the receiving direct mode communication apparatus  53  comprises a transceiver  531  and a packet processing module  533 . The packet processing module  533  further comprises a dual-mode PDCP processing unit  5333  and a dual-mode RLC processing unit  5335 . The fifth embodiment mainly details the packet transmission and switching processes for a connection of a different form. Interactions among the individual elements will be further described hereinbelow. 
     Firstly, the packet processing module  513  of the transmitting direct mode communication apparatus  51  creates a direct communication connection  52  with the receiving direct mode communication apparatus  53  via the transceiver  511 . In other words, the packet processing module  533  of the receiving direct mode communication apparatus  53  creates the direct communication connection  52  with the transmitting direct mode communication apparatus  51  via the transceiver  531 . 
     Then, before a first network packet  510  is transmitted by the transmitting direct mode communication apparatus  51  to the receiving direct mode communication apparatus  53 , the TFT processing unit  5131  of the transmitting direct mode communication apparatus  51  receives the first network packet  510  from the IP layer and transmits internally the first network packet  510  to the dual-mode PDCP processing unit  5133 . 
     Next, the dual-mode PDCP processing unit  5133  transmits the first network packet  510  to the dual-mode RLC processing unit  5135  in a PDCP direct communication mode (not shown). The dual-mode RLC processing unit  5335  further transmits the first network packet  510  to the receiving direct mode communication apparatus  53  through the transceiver  511  and via the direct communication connection  52  in an RLC direct communication mode. 
     On the other hand, the dual-mode RLC processing unit  5335  of the receiving direct mode communication apparatus  53  receives the first network packet  510  from the transmitting direct mode communication apparatus  51  through the transceiver  531  and via the direct communication connection  52  in an RLC direct communication mode (not shown), and forwards the first network packet  510  to the dual-mode PDCP processing unit  5333 . Then, the dual-mode PDCP processing unit  5333  further analyzes the first network packet  510  in a PDCP direct communication mode (not shown), and forwards the first network packet  510  to the IP layer for subsequent processing. 
     Subsequently, when the packet processing module  513  of the transmitting direct mode communication apparatus  51  detects and determines that the direct communication connection  52  is interrupted and the transmitting direct mode communication apparatus  51  is to transmit a second network packet  512  to the receiving direct mode communication apparatus  53 , the TFT processing unit  5131  of the transmitting direct mode communication apparatus  51  receives the second network packet  512  from the IP layer and transmits internally the second network packet  512  to the dual-mode PDCP processing unit  5133 . 
     Afterwards, the dual-mode PDCP processing unit  5133  transmits the second network packet  512  to the dual-mode RLC processing unit  5135  in a PDCP backend network mode (not shown). The dual-mode RLC processing unit  5135  further transmits the second network packet  512  to the receiving direct mode communication apparatus  53  through the transceiver  511  and via the backend network connection  50  in an RLC backend network mode (not shown). 
     On the other hand, after the direct communication connection  52  is interrupted, the dual-mode RLC processing unit  5335  of the receiving direct mode communication apparatus  53  receives the second network packet  512  from the transmitting direct mode communication apparatus  51  through the transceiver  531  and via the backend network connection  50  in an RLC backend network mode (not shown). Then, the dual-mode PDCP processing unit  5333  analyzes the second network packet  512  in a PDCP backend network mode (not shown) and further forwards the second network packet  512  to the IP layer for subsequent processing. 
     A sixth embodiment of the present invention is a communication path switching method, a flowchart diagram of which is shown in  FIG. 6 . The method of the sixth embodiment is for use in a transmitting direct mode communication apparatus and a receiving direct mode communication apparatus (e.g., the transmitting direct mode communication apparatus  11  and the receiving direct mode communication apparatus  13  of the aforesaid embodiment). 
     The transmitting direct mode communication apparatus comprises a first packet processing module and a first transceiver; and the receiving direct mode communication apparatus comprises a second packet processing module and a second transceiver. The transmitting direct mode communication apparatus maintains a backend network connection with the receiving direct mode communication apparatus via a backend network server. Steps of the sixth embodiment are detailed as follows. 
     Firstly, step  601   a  is executed to enable the first packet processing module to create a direct communication connection with the receiving direct mode communication apparatus via the first transceiver. Simultaneously, step  601   b  is executed to enable the second packet processing module to create the direct communication connection with the transmitting direct mode communication apparatus via the second transceiver. Then, step  602  is executed to enable the first packet processing module to determine that the direct communication connection is interrupted. 
     Next, step  603   a  is executed to enable the first packet processing module to switch the communication with the receiving direct mode communication apparatus from the direct communication connection to the backend network connection. Simultaneously, step  603   b  is executed to enable the second packet processing module to communicate with the transmitting direct mode communication apparatus via the backend network connection after the direct communication connection is interrupted. 
     A seventh embodiment of the present invention is a communication path switching method, a flowchart diagram of which is shown in  FIGS. 7A-7B . The method of the seventh embodiment is for use in a transmitting direct mode communication apparatus and a receiving direct mode communication apparatus (e.g., the transmitting direct mode communication apparatus  21  and the receiving direct mode communication apparatus  23  of the aforesaid embodiment). 
     The transmitting direct mode communication apparatus comprises a first packet processing module and a first transceiver; and the receiving direct mode communication apparatus comprises a second packet processing module and a second transceiver. The transmitting direct mode communication apparatus maintains a backend network connection with the receiving direct mode communication apparatus via a backend network server. 
     The first packet processing module further comprises a first backend network address processing unit, a first direct mode communication network address processing unit, a first backend network traffic filter template (TFT) processing unit and a first direct mode communication network TFT processing unit. The second packet processing module further comprises a second backend network address processing unit and a second direct mode communication network address processing unit. Steps of the seventh embodiment are detailed as follows. 
     Firstly, step  701   a  is executed to enable the first packet processing module to create a direct communication connection with the receiving direct mode communication apparatus via the first transceiver. Simultaneously, step  701   b  is executed to enable the second packet processing module to create the direct communication connection with the transmitting direct mode communication apparatus via the second transceiver. 
     Then, step  702  is executed to enable the first backend network address processing unit to transmit a first network packet to the first backend network TFT processing unit. The first network packet comprises a backend network source address and a backend network destination address. Step  703  is executed to enable the first backend network TFT processing unit to forward the first network packet to the first direct mode communication network address processing unit. 
     Step  704  is executed to enable the first direct mode communication network address processing unit to transform the backend network source address and the backend network destination address of the first network packet into a direct mode communication network source address and a direct mode communication network destination address respectively. Step  705  is executed to enable the first direct mode communication network TFT processing unit to transmit the first network packet to the receiving direct mode communication apparatus through the first transceiver and via the direct communication connection according to one of the direct mode communication network source address, the direct mode communication network destination address and a combination thereof. 
     Then, step  706  is executed to enable the second direct mode communication network address processing unit to receive the first network packet from the transmitting direct mode communication apparatus through the second transceiver and via the direct communication connection. Step  707  is executed to enable the second direct mode communication network address processing unit to transform the direct mode communication network source address and the direct mode communication network destination address of the first network packet into a backend network source address and a backend network destination address respectively. Step  708  is executed to enable the second backend network address processing unit to analyze the first network packet according to one of the backend network source address, the backend network destination address and a combination thereof. 
     Step  709  is executed to enable the first packet processing module to determine that the direct communication connection is interrupted. Step  710   a  is executed to enable the first packet processing module to switch the communication with the receiving direct mode communication apparatus from the direct communication connection to the backend network connection. Simultaneously, step  710   b  is executed to enable the second packet processing module to communicate with the transmitting direct mode communication apparatus via the backend network connection after the direct communication connection is interrupted. 
     Step  711  is executed to enable the first backend network address processing unit to transmit a second network packet to the first backend network TFT processing unit. The second network packet comprises the backend network source address and the backend network destination address. Step  712  is executed to enable the first backend network TFT processing unit to transmit the second network packet to the receiving direct mode communication apparatus through the first transceiver and via the backend network connection according to one of the backend network source address, the backend network destination address and a combination thereof. 
     Step  713  is executed to enable the second backend network address processing unit to receive the second network packet through the second transceiver and via the backend network connection. Step  714  is executed to enable the second backend network address processing unit to analyze the second network packet according to one of the backend network source address, the backend network destination address and a combination thereof. 
     An eighth embodiment of the present invention is a communication path switching method, a flowchart diagram of which is shown in  FIG. 8 . The method of the eighth embodiment is for use in a transmitting direct mode communication apparatus and a receiving direct mode communication apparatus (e.g., the transmitting direct mode communication apparatus  31  and the receiving direct mode communication apparatus  33  of the aforesaid embodiment). 
     The transmitting direct mode communication apparatus comprises a first packet processing module and a first transceiver; and the receiving direct mode communication apparatus comprises a second packet processing module and a second transceiver. The transmitting direct mode communication apparatus maintains a backend network connection with the receiving direct mode communication apparatus via a backend network server. 
     The first packet processing module further comprises a first backend network address processing unit, a first backend network TFT processing unit and a first direct mode communication network TFT processing unit. The second packet processing module further comprises a second backend network address processing unit. Steps of the eighth embodiment are detailed as follows. 
     Firstly, step  801   a  is executed to enable the first packet processing module to create a direct communication connection with the receiving direct mode communication apparatus via the first transceiver. Simultaneously, step  801   b  is executed to enable the second packet processing module to create the direct communication connection with the transmitting direct mode communication apparatus via the second transceiver. 
     Then, step  802  is executed to enable the first backend network address processing unit to transmit a first network packet to the first direct mode communication network TFT processing unit. The first network packet comprises a backend network source address and a backend network destination address. Step  803  is executed to enable the first direct mode communication network TFT processing unit to transmit the first network packet to the receiving direct mode communication apparatus through the first transceiver and via the direct communication connection according to one of the backend network source address, the backend network destination address and a combination thereof. 
     Then, step  804  is executed to enable the second backend network address processing unit to receive the first network packet from the transmitting direct mode communication apparatus through the second transceiver and via the direct communication connection. Step  805  is executed to enable the second backend network address processing unit to analyze the first network packet according to one of the backend network source address, the backend network destination address and a combination thereof. 
     Step  806  is executed to enable the first packet processing module to determine that the direct communication connection is interrupted. Step  807   a  is executed to enable the first packet processing module to switch the communication with the receiving direct mode communication apparatus from the direct communication connection to the backend network connection. Simultaneously, step  807   b  is executed to enable the second packet processing module to communicate with the transmitting direct mode communication apparatus via the backend network connection after the direct communication connection is interrupted. 
     Step  808  is executed to enable the first backend network address processing unit to transmit a second network packet to the first backend network TFT processing unit. The second network packet comprises the backend network source address and the backend network destination address. Step  809  is executed to enable the first backend network TFT processing unit to transmit the second network packet to the receiving direct mode communication apparatus through the first transceiver and via the backend network connection according to one of the backend network source address, the backend network destination address and a combination thereof. 
     Step  810  is executed to enable the second backend network address processing unit to receive the second network packet through the second transceiver and via the backend network connection. Step  811  is executed to enable the second backend network address processing unit to analyze the second network packet according to one of the backend network source address, the backend network destination address and a combination thereof. 
     A ninth embodiment of the present invention is a communication path switching method, a flowchart diagram of which is shown in  FIGS. 9A-9B . The method of the ninth embodiment is for use in a transmitting direct mode communication apparatus and a receiving direct mode communication apparatus (e.g., the transmitting direct mode communication apparatus  41  and the receiving direct mode communication apparatus  43  of the aforesaid embodiment). 
     The transmitting direct mode communication apparatus comprises a first packet processing module and a first transceiver; and the receiving direct mode communication apparatus comprises a second packet processing module and a second transceiver. The transmitting direct mode communication apparatus maintains a backend network connection with the receiving direct mode communication apparatus via a backend network server. 
     The first packet processing module further comprises a first backend network address processing unit, a first direct mode communication network address processing unit, a first backend network TFT processing unit and a first direct mode communication network TFT processing unit. The second packet processing module further comprises a second backend network address processing unit and a second direct mode communication network address processing unit. Steps of the ninth embodiment are detailed as follows. 
     Firstly, step  901   a  is executed to enable the first packet processing module to create a direct communication connection with the receiving direct mode communication apparatus via the first transceiver. Simultaneously, step  901   b  is executed to enable the second packet processing module to create the direct communication connection with the transmitting direct mode communication apparatus via the second transceiver. 
     Then, step  902  is executed to enable the first backend network address processing unit to transmit a first network packet to the first direct mode communication network TFT processing unit. The first network packet comprises a backend network source address and a backend network destination address. Step  903  is executed to enable the first direct mode communication network address processing unit to transform the backend network source address and the backend network destination address of the first network packet into a direct mode communication network source address and a direct mode communication network destination address respectively. 
     Step  904  is executed to enable the first direct mode communication network TFT processing unit to transmit the first network packet to the receiving direct mode communication apparatus through the first transceiver and via the direct communication connection according to one of the direct mode communication network source address, the direct mode communication network destination address and a combination thereof. Step  905  is executed to enable the second backend network address processing unit to receive the first network packet from the transmitting direct mode communication apparatus through the second transceiver and via the direct communication connection. 
     Step  906  is executed to enable the second direct mode communication network address processing unit to transform the direct mode communication network source address and the direct mode communication network destination address of the first network packet into a backend network source address and a backend network destination address respectively. Step  907  is executed to enable the second backend network address processing unit to analyze the first network packet according to one of the backend network source address, the backend network destination address and a combination thereof. 
     Step  908  is executed to enable the first packet processing module to determine that the direct communication connection is interrupted. Step  909   a  is executed to enable the first packet processing module to switch the communication with the receiving direct mode communication apparatus from the direct communication connection to the backend network connection. Simultaneously, step  909   b  is executed at the same time to enable the second packet processing module to communicate with the transmitting direct mode communication apparatus via the backend network connection after the direct communication connection is interrupted. 
     Step  910  is executed to enable the first backend network address processing unit to transmit a second network packet to the first backend network TFT processing unit. The second network packet comprises the backend network source address and the backend network destination address. Step  911  is executed to enable the first backend network TFT processing unit to transmit the second network packet to the receiving direct mode communication apparatus through the first transceiver and via the backend network connection according to one of the backend network source address, the backend network destination address and a combination thereof. 
     Step  912  is executed to enable the second backend network address processing unit to receive the second network packet through the second transceiver and via the backend network connection. Step  913  is executed to enable the second backend network address processing unit to analyze the second network packet according to one of the backend network source address, the backend network destination address and a combination thereof. 
     A tenth embodiment of the present invention is a communication path switching method, a flowchart diagram of which is shown in  FIGS. 10A-10B . The method of the tenth embodiment is for use in a transmitting direct mode communication apparatus and a receiving direct mode communication apparatus (e.g., the transmitting direct mode communication apparatus  51  and the receiving direct mode communication apparatus  53  of the aforesaid embodiment). 
     The transmitting direct mode communication apparatus comprises a first packet processing module and a first transceiver; and the receiving direct mode communication apparatus comprises a second packet processing module and a second transceiver. The transmitting direct mode communication apparatus maintains a backend network connection with the receiving direct mode communication apparatus via a backend network server. 
     The first packet processing module further comprises a first TFT processing unit, a first dual-mode PDCP processing unit and a first dual-mode RLC processing unit. The second packet processing module further comprises a second dual-mode PDCP processing unit and a second dual-mode RLC processing unit. Steps of the tenth embodiment are detailed as follows. 
     Firstly, step  1001   a  is executed to enable the first packet processing module to create a direct communication connection with the receiving direct mode communication apparatus via the first transceiver. Simultaneously, step  1001   b  is executed to enable the second packet processing module to create the direct communication connection with the transmitting direct mode communication apparatus via the second transceiver. 
     Then, step  1002  is executed to enable the first TFT processing unit to transmit a first network packet to the first dual-mode PDCP processing unit. Step  1003  is executed to enable the first dual-mode PDCP processing unit to transmit the first network packet to the first dual-mode RLC processing unit in a PDCP direct communication mode. Step  1004  is executed to enable the first dual-mode RLC processing unit to transmit the first network packet to the receiving direct mode communication apparatus through the first transceiver and via the direct communication connection in an RLC direct communication mode. 
     Step  1005  is executed to enable the second dual-mode RLC processing unit to receive the first network packet from the transmitting direct mode communication apparatus through the second transceiver and via the direct communication connection in an RLC direct communication mode. Step  1006  is executed to enable the second dual-mode PDCP processing unit to analyze the first network packet in a PDCP direct communication mode. 
     Step  1007  is executed to enable the first packet processing module to determine that the direct communication connection is interrupted. Step  1008   a  is executed to enable the first packet processing module to switch the communication with the receiving direct mode communication apparatus from the direct communication connection to the backend network connection. Simultaneously, step  1008   b  is executed to enable the second packet processing module to communicate with the transmitting direct mode communication apparatus via the backend network connection after the direct communication connection is interrupted. 
     Next, step  1009  is executed to enable the first TFT processing unit to transmit a second network packet to the first dual-mode PDCP processing unit. Step  1010  is executed to enable the first dual-mode PDCP processing unit to transmit the second network packet to the first dual-mode RLC processing unit in a PDCP backend network mode. Step  1011  is executed to enable the first dual-mode RLC processing unit to transmit the second network packet to the receiving direct mode communication apparatus through the first transceiver and via the backend network connection in an RLC backend network mode. 
     Then, step  1012  is executed to enable the second dual-mode RLC processing unit to receive the second network packet from the transmitting direct mode communication apparatus through the second transceiver and via the backend network connection in an RLC backend network mode. Step  1013  is executed to enable the second dual-mode PDCP processing unit to analyze the second network packet in a PDCP backend network mode. 
     According to the above descriptions, the transmitting direct mode communication apparatus, the receiving direct mode communication apparatus and the communication path switching methods thereof according to the present invention can accomplish switching of the connection more properly and, by modifying the lower-layer protocol, make an improvement on the shortcomings of the complex connection switching procedure and the long interruption time during the connection switching. 
     The above disclosure is related to the detailed technical contents and inventive features thereof. People skilled in this field may proceed with a variety of modifications and replacements based on the disclosures and suggestions of the invention as described without departing from the characteristics thereof. Nevertheless, although such modifications and replacements are not fully disclosed in the above descriptions, they have substantially been covered in the following claims as appended.