Abstract:
A packet transmission system, a packet transmission method, a packet update method, a host apparatus, and a computer program product thereof for the packet transmission system are provided. The packet transmission method comprises the following steps: transmitting a first positioning packet that has a first message serial number; receiving the first positioning packet; generating a temporary packet that has a second message serial number; determining that the first message serial number is smaller than the second message serial number; transmitting the temporary packet; receiving the temporary packet and updating the first message serial as the second message serial number; and transmitting a second positioning packet that has the second message serial number. Thereby, the system not only prevents repeat transmission, but also enhances positioning reliability by using two-way transmission.

Description:
This application claims the benefit of priority based on Taiwan Patent Application No. 097136809 filed on Sep. 25, 2008, the disclosures of which are incorporated herein by reference in their entirety. 
     CROSS-REFERENCES TO RELATED APPLICATIONS 
     Not applicable. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a packet transmission system, a packet transmission method, a packet update method, a host apparatus and a computer program product thereof for the packet transmission system. In particular, the present invention relates to a packet transmission system that increases the positioning speed and accuracy by using two-way transmission of packets, and a packet transmission method, a packet update method, a host apparatus and a computer program product thereof for the packet transmission system. 
     2. Descriptions of the Related Art 
     Over recent years, with the widespread use of mobile communications, mobile communication apparatuses are becoming more diversified and prevalent. However, current mobile communication apparatuses commercially available, for example, those compatible with Global System for Mobile Communications (GSM), Wideband Code Division Multiple Access (WCDMA), General Packet Radio Service (GPRS), Personal Handy Phone System (PHS), Wireless Fidelity (WiFi) System or Worldwide Interoperability for Microwave Access (WiMAX), all utilize base stations to provide voice, image and data communications and mobile apparatus positioning service. 
     However, the aforesaid mobile communication systems can provide the positioning service with satisfactory accuracy only when the mobile apparatus is not moving at a high speed or not moving continuously. For instance, only when the user uses the positioning function of a Personal Digital Assistant (PDA) at a fixed location or in a vehicle moving at a low speed, can the aforesaid mobile communication systems provide positioning functions adequate to allow the user to know his own position exactly while still allowing for various communications such as voice, image and data communications. Moreover, the positioning functions of the aforesaid mobile communication systems are mostly limited to coverage areas due to the electromagnetic waves transmitted by the base stations thereof. 
     However, if a mobile apparatus provides positioning functions with high accuracy only when it is located at a fixed location or moving at a low speed, it will fail to meet requirements of the modern society in most cases. For instance, for a business person in a bus running on an expressway or a train running at a high speed, the positioning function of his mobile apparatus will experience a degradation in positioning accuracy or even failure of the positioning function due to loss of positioning packets transmitted between the mobile apparatus and host apparatus (e.g., a server or switch). 
     Furthermore, in addition to the problem with positioning accuracy, the aforesaid mobile communication systems all have to establish data transmission channels with the base stations or the host apparatuses continuously to position the mobile apparatus by performing the positioning function at any time. Because of this, the mobile apparatus has to transmit and receive various positioning information on a continuous basis, leading to considerable power consumption. 
     In view of this, it is important to improve the accuracy of positioning a mobile apparatus while transmitting information and reduce power consumption. 
     SUMMARY OF THE INVENTION 
     One objective of this invention is to provide a packet transmission system, a packet transmission method, and a computer program product thereof for the packet transmission system, in which the temporary packet is sent according to the serial number of a positioning packet and that of the temporary packet. This method may not only prevent repeated transmission of the packets, but also confirm whether the packets have been received through two-way transmission of the packets, thus further enhancing the reliability and accuracy of positioning the mobile apparatus. 
     To this end, the packet transmission system of this invention comprises a mobile apparatus and a host apparatus. The mobile apparatus is configured to generate and transmit a first positioning packet including a first message serial number. The host apparatus is configured to receive the first positioning packet and generate a temporary packet including a second message serial number. When the host apparatus determines that the first message serial number of the first positioning packet is smaller than the second message serial number of the temporary packet, the host apparatus transmits the temporary packet to the mobile apparatus. Upon receiving the temporary packet, the mobile apparatus updates the first message serial number into the second message serial number, and then generates and transmits a second positioning packet including the second message serial number to the host apparatus. 
     Similarly, to this end, the packet transmission method of this invention comprises the following steps of: transmitting a first positioning packet including a first message serial number; receiving the first positioning packet; generating a temporary packet including a second message serial number; determining that the first message serial number of the first positioning packet is smaller than the second message serial number of the temporary packet; transmitting the temporary packet; receiving the temporary packet, and updating the first message serial number into the second message serial number; and transmitting a second positioning packet including the second message serial number. 
     This invention further provides a computer program product comprising a plurality of instructions stored in a computer readable medium for the packet transmission system of this invention to perform the packet transmission method described above. 
     Another objective of this invention is to provide a host apparatus, a packet update method and a computer program product thereof for the packet transmission system. The host apparatus decides whether to delete the temporary packet stored in the host apparatus according to the serial number of the positioning packet and the temporary packet. This method may prevent repeated transmission of the packets, thereby increasing the efficiency of packet transmissions. 
     To this end, the host apparatus for the packet transmission system of this invention comprises a receiving module, a microprocessor, a comparison module, and a transmitting module. The receiving module is configured to receive a first positioning packet including a first message serial number. The microprocessor is configured to generate a temporary packet including a second message serial number. The comparison module is configured to determine whether the first message serial number of the first positioning packet is smaller than the second message serial number of the temporary packet. If the comparison module determines that the first message serial number is smaller than the second message serial number, then the transmitting module transmits the temporary packet. 
     Similarly, the packet update method of this invention comprises the following steps of: receiving a first positioning packet including a first message serial number; generating a temporary packet with a second message serial number; determining that the first message serial number of the first positioning packet is smaller than the second message serial number of the temporary packet; and transmitting the temporary packet. 
     Furthermore, this invention further provides a computer program product comprising a plurality of instructions stored in a computer readable medium for the host apparatus of this invention to perform the packet update method described above. 
     In summary, instead of transmitting positioning packets on a continuous basis as in the prior art, the packet transmission system, packet transmission method, packet update method, host apparatus and computer program product thereof for the packet transmission system disclosed in this invention can position a mobile apparatus by only transmitting a minimum amount of packets through the positioning packets using limited power sources of the mobile apparatus. 
     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. 1  is a schematic view illustrating a first embodiment of this invention; 
         FIG. 2  is a schematic view illustrating the host apparatus of the first embodiment; 
         FIG. 3  is a schematic view illustrating packets in the first embodiment; 
         FIG. 4  is a flowchart of a second embodiment of this invention; 
         FIG. 5  is a flowchart of a third embodiment of this invention; 
         FIG. 6  is a flowchart of a fourth embodiment of this invention; 
         FIG. 7  is a flowchart of a fifth embodiment of this invention; and 
         FIG. 8  is a flowchart of a sixth embodiment of this invention. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     In the following description, embodiments will be described to explain this invention, which provides a packet transmission system, a packet transmission method, a packet update method, a host apparatus, and a computer program product thereof for the packet transmission system. However, these embodiments are not intended to limit this invention to any specific environment, applications, or particular implementations described in these embodiments. Therefore, the description of these embodiments is only intended to illustrate rather than to limit this invention. It should be appreciated that in the following embodiments and the attached drawings, elements not related directly to this invention are omitted from depiction. 
     As shown in  FIG. 1 , a first embodiment of this invention is a packet transmission system  1 . The packet transmission system  1  comprises a mobile apparatus  11 , a plurality of base stations  131 ,  132 , . . . ,  136  and a host apparatus  15 . The mobile apparatus  11  may be an apparatus that moves with a user such as a cell phone, a navigation apparatus, a PDA or a notebook computer. However, the mobile apparatus  11  described in this invention is not limited to what is set forth herein, and any apparatus that is portable and movable at random may act as the mobile apparatus  11 . The base stations  131 ,  132 , . . . ,  136  may be any commercially available apparatus capable of forwarding packets. The host apparatus  15 , which is as shown in  FIG. 2 , may be an apparatus capable of processing massive data streams such as a server or a communication switch. The host apparatus  15  comprises a receiving module  151 , a microprocessor  153 , a comparison module  155 , and a transmitting module  157 . By using these elements, the host apparatus  15  can use the packet update method for the packet transmission system  1 . The operations and functions of the individual elements of the packet transmission system  1  will be detailed hereinbelow. 
     The mobile apparatus  11  generates and transmits a positioning packet to the host apparatus  15  at regular intervals. The host apparatus  15  then performs positioning of the mobile apparatus  11  by receiving the positioning packets transmitted by the mobile apparatus  11  at different times. For instance, when generated by the mobile apparatus  11 , a first positioning packet  31  is transmitted to one of the base stations  131 ,  132 , . . . ,  136 . More specifically, if the mobile apparatus  11  is located within the coverage of the base station  131 , the first positioning packet  31  will be transmitted to the base station  131 . Upon receiving the first positioning packet  31 , the base station  131  transmits a response packet  37  to the mobile apparatus  11  and forwards the first positioning packet  31  to the host apparatus  15  at the same time. 
     The first positioning packet  31  is depicted in  FIG. 3 . The first positioning packet  31  comprises a first mobile apparatus serial number  311 , a first positioning packet serial number  313 , a first message serial number  315  and a data field  317 . The first mobile apparatus serial number  311  is configured to identify that the first positioning packet  31  is transmitted by the mobile apparatus  11 . More specifically, the first mobile apparatus serial number  311  has been assigned by the host apparatus  15  to the mobile apparatus  11  early when the packet transmission system  1  was initially established. The first positioning packet serial number  313  is only used to indicate a number of positioning packets transmitted by the mobile apparatus  11 . The first message serial number  315  is configured to indicate the number of temporary packets received by the mobile apparatus  11  from the host apparatus  15 , a detailed description of which will be made later. The data field  317  is configured to carry other data to be transmitted by the mobile apparatus  11  to the host apparatus  15 . By transmitting the positioning packets at regular intervals, the power consumption of the mobile apparatus  11  is reduced and consequently, the battery endurance of the mobile apparatus  11  is prolonged. 
     Upon receiving the response packet  37  transmitted by the base station  131 , the mobile apparatus  11  deletes the data originally carried by the data field  317  of the first positioning packet  31  to prevent data that has been transmitted through the first positioning packet  31  from being re-transmitted during the transmission of the next positioning packet. However, after the host apparatus  15  has received the first positioning packet  31 , the response packet  37  may also be transmitted by the host apparatus  15  back to the mobile apparatus  11  directly so that the mobile apparatus  11  deletes the data originally carried by the data field  317  of the first positioning packet  31 . 
     In case the host apparatus  15  is to transmit data to the mobile apparatus  11 , the microprocessor  153  of the host apparatus  15  will generate a first temporary packet  33 . As shown in  FIG. 3 , the first temporary packet  33  comprises a second mobile apparatus serial number  331 , a second message serial number  333  and a temporary data field  335 . The second mobile apparatus serial number  331  is substantially the same as the first mobile apparatus serial number  311  described above, which means that the first temporary packet  33  is to be transmitted to the mobile apparatus  11 . The second message serial number  333  is configured to indicate a number of temporary packets transmitted by the host apparatus  15  to the mobile apparatus  11 . 
     After the receiving module  151  of the host apparatus  15  has received the first positioning packet  31 , the comparison module  155  retrieves the first positioning packet  31  from the receiving module  151  and the first temporary packet  33  from the microprocessor  153  to determine whether the first message serial number  313  of the first positioning packet  31  is smaller than the second message serial number  333  of the first temporary packet  33 . If smaller, it means that the first temporary packet  33  has not been received by the mobile apparatus  11  yet at that time when the mobile apparatus  11  transmitted the first positioning packet  31 . Accordingly, the host apparatus  15  must transmit the first temporary packet  33  to the mobile apparatus  11 . In this case, the comparison module  155  transmits a transmission signal  150  to the microprocessor  153 . 
     If the comparison module  155  determines that the first message serial number  313  of the first positioning packet  31  is not smaller than the second message serial number  333  of the first temporary packet  33 , it means that the mobile apparatus  11  has already received the first temporary packet  33  before it transmitted the first positioning packet  31 . Then, the host apparatus  15  must delete the first temporary packet  33 . In this case, the comparison module  155  transmits a deletion signal  152  to the microprocessor  153  to delete the first temporary packet  33 . 
     When the host apparatus  15  is ready to transmit the first temporary packet  33 , the microprocessor  153  of the host apparatus  15  estimates the direction in and the rate at which the mobile apparatus  11  will possibly move next by making a series of computations according to the positioning packet received by the mobile apparatus  11 . Based on this information, the host apparatus  15  selects at least one base station whose coverage is adequate to cover the mobile apparatus  11  to transmit the first temporary packet  33 . The estimation to the direction in and the rate at which the mobile apparatus  11  will possibly move next is well known to those of ordinary skill in the art and thus will not be further described herein. 
     In this embodiment, the microprocessor  153  of the host apparatus  15  calculates that the mobile apparatus  11  will move from a position A where it transmitted the first positioning packets  31  (i.e., the position of the mobile apparatus  11  depicted by a dashed line in  FIG. 1 ) to a position B (i.e., the position of the mobile apparatus  11  depicted by a solid line in  FIG. 1 ). Thus, the microprocessor  153  of the host apparatus  15  first selects the base station  133  and the base station  135  near the chosen position B as destinations to which the first temporary packet  33  is to be transmitted. Then, the transmitting module  157  transmits the first temporary packet  33  to the base stations  133  and the base station  135 . Subsequently, one of the base station  133  and the base station  135  forwards the first temporary packet  33  received by it to the mobile apparatus  11  located at the position B. More specifically, when the mobile apparatus  11  has moved to the position B in the coverage area of the base station  135 , the first temporary packet  33  will be forwarded by the base station  135  to the mobile apparatus  11 . 
     In this embodiment, upon receiving the first temporary packet  33 , the mobile apparatus  11  located at the position B updates the first message serial number  315  of the first positioning packet  31  originally stored in the mobile apparatus  11  into the second message serial number  333  of the first temporary packet  33 . 
     When the mobile apparatus  11  generates and is ready to transmit a second positioning packet  35  to the host apparatus  15 , the second positioning packet  35  is as shown in  FIG. 3 . The second positioning packet  35  comprises a third mobile apparatus serial number  351 , a second positioning serial number  353 , a second message serial number  333  and a data field  357 . The third mobile apparatus serial number  351  of the second positioning packet  35  is substantially the same as the first mobile apparatus serial number  311  and the second mobile apparatus serial number  331 . Similarly, the second positioning packet serial number  353  is configured to indicate the number of positioning packets transmitted by the mobile apparatus  11 . Because the second positioning packet  35  is transmitted following the first positioning packet  31 , the second positioning packet serial number  353  is larger than the first positioning packet serial number  313 . The data field  357  is also only used to carry other data to be transmitted by the mobile apparatus  11  to the host apparatus  15 . The detailed process of transmitting the second positioning packet  35  to the host apparatus  15  is just the same as the aforesaid process of transmitting the first positioning packet  31  to the host apparatus  15 , and thus will not be further described herein. 
     If the host apparatus  15  transmits the next data to the mobile apparatus  11  after it has transmitted the first temporary packet  33 , the microprocessor  153  of the host apparatus  15  will generate a second temporary packet  39 . As depicted in  FIG. 3 , the second temporary packet  39  comprises a fourth mobile apparatus serial number  391 , a third message serial number  393  and a temporary data field  395 . The fourth mobile apparatus serial number  391  is substantially the same as the first mobile apparatus serial number  31 , the second mobile apparatus serial number  331  and the third mobile apparatus serial number  351  described above, which means that the second temporary packet  39  will be transmitted to the mobile apparatus  11 . The third message serial number  393  is configured to indicate a number of the temporary packets transmitted by the host apparatus  15  to the mobile apparatus  11 . Because the second temporary packet  39  is transmitted following the first temporary packet  33 , the third message serial number  393  is larger than the second message serial number  333 . The detailed process of transmitting the second temporary packet  39  to the mobile apparatus  11  is just the same as the aforesaid process of transmitting the first temporary packet  33  to the mobile apparatus  11 , and thus will not be further described herein. 
       FIG. 4  depicts a second embodiment of this invention, which is a packet transmission method adapted for a packet transmission system, such as the packet transmission system  1  described in the first embodiment. In particular, the packet transmission method of the second embodiment may be implemented by a computer program product. When the computer program product is loaded in the packet transmission system via a computer and a plurality of instructions embodied therein is executed, the packet transmission method of the second embodiment will be accomplished. This computer program product may be stored in a tangible machine-readable medium, such as a read only memory (ROM), a flash memory, a floppy disk, a hard disk, a compact disk, a mobile disk, a magnetic tape, a database accessible to networks, or any other storage media with the same function and well known to those skilled in the art. 
     The packet transmission method of the second embodiment comprises the following steps. Initially in step S 401 , a first positioning packet includes a first message serial number that is transmitted. Then, in step S 403 , the first positioning packet is received. Next, in step S 405 , a response packet is transmitted. It should be noted that the response packet may be transmitted by one of a plurality of base stations. Subsequently, in step S 407 , a first temporary packet includes a second message serial number that is generated. Step S 409  follows step S 407 , where the first message serial number of the first positioning packet is compared to the second message serial number of the first temporary packet. If the first message serial number is not smaller the second message serial number, step S 421  is executed to delete the first temporary packet. 
     Otherwise, if the first message serial number is smaller than the second message serial number, step S 411  is executed, where at least one base station is chosen from the plurality of base stations. Then, in step S 413 , the first temporary packet is transmitted to the at least one chosen base station to be transmitted therefrom. Subsequent to step S 413 , step S 415  is executed to receive the first temporary packet and update the first message serial number into the second message serial number. Next, in step S 417 , a second positioning packet includes a second message serial number that is transmitted, and in step S 419 , the second positioning packet is received. Finally, in step S 421 , the first temporary packet is deleted. 
     In addition to the aforesaid steps, the second embodiment can also execute all the operations and functions described with reference to the packet transmission system  1  of the first embodiment. The method in which the second embodiment executes these operations and functions will be readily appreciated by those of ordinary skill in the art based on the explanation of the first embodiment, and thus will not be further described herein. 
       FIG. 5  depicts a third embodiment of this invention, which is a packet update method adapted for a host apparatus of a packet transmission system, such as the host apparatus  15  described in the first embodiment. The packet update method of the third embodiment may be implemented by a computer program product. When the computer program product is loaded in the host apparatus via a computer and a plurality of instructions embodied therein is executed, the packet update method of the third embodiment will be accomplished. This computer program product may be stored in a tangible machine-readable medium, such as a read only memory (ROM), a flash memory, a floppy disk, a hard disk, a compact disk, a mobile disk, a magnetic tape, a database accessible to networks, or any other storage media with the same function and well known to those skilled in the art. 
     The packet update method of the third embodiment comprises the following steps. Initially, in step S 501 , a first positioning packet includes a first message serial number that is received. In step S 503 , a response packet is transmitted. It should be noted that the response packet may be transmitted by one of a plurality of base stations. Subsequently in step S 505 , a first temporary packet includes a second message serial number that is generated. Step S 507  follows step S 505 , in which the first message serial number of the first positioning packet is compared to the second message serial number of the first temporary packet. If the first message serial number is not smaller than the second message serial number, step S 515  is executed to delete the first temporary packet. 
     Otherwise, if the first messages serial number is smaller than the second message serial number, step S 509  is executed, where at least one base station is chosen from the plurality of base stations. Then, in step S 511 , the first temporary packet is transmitted to the at least one chosen base station. Next, in step S 513 , where the at least one chosen base station transmits the first temporary packet to the mobile apparatus. In step S 515 , the second positioning packet includes a second message serial number that is received. Finally, in step S 517 , the first temporary packet is deleted. 
     In addition to the aforesaid steps, the third embodiment can also execute all the operations and functions of the host apparatus  15  of the first embodiment. The method in which the third embodiment executes these operations and functions will be readily appreciated by those of ordinary skill in the art based on the explanation of the first embodiment, and thus will not be further described herein. 
       FIG. 6  depicts a fourth embodiment of this invention, which is another packet transmission system  6  without a base station. Therefore, the host apparatus  15  communicates positioning packets, temporary packets or response packets with the mobile apparatus  11  directly. The operations of individual elements in the packet transmission system  6  are identical to those of the packet transmission system  1  in the first embodiment. The operations and functions of the packet transmission system  6  will be readily appreciated by those of ordinary skill in the art based on the above description, and thus will not be further described herein. 
       FIG. 7  depicts a fifth embodiment of this invention, which is a packet transmission method adapted for a packet transmission system, such as the packet transmission system  6  described in the fourth embodiment. In particular, the packet transmission method of the fifth embodiment may be implemented by a computer program product. When the computer program product is loaded in the packet transmission system via a computer and a plurality of instructions embodied therein is executed, the packet transmission method of the fifth embodiment will be accomplished. This computer program product may be stored in a tangible machine-readable medium, such as a read only memory (ROM), a flash memory, a floppy disk, a hard disk, a compact disk, a mobile disk, a magnetic tape, a database accessible to networks, or any other storage media with the same function and well known to those skilled in the art. 
     The packet transmission method of the fifth embodiment comprises the following steps. Initially, in step S 701 , a first positioning packet includes a first message serial number that is transmitted. Then, in step S 703 , the first positioning packet is received. Subsequently, in step S 705 , a response packet is transmitted. In step S 707 , a first temporary packet includes a second message serial number that is generated. Subsequent to step S 707  is step S 709 , where the first message serial number of the first positioning packet is compared to the second message serial number of the first temporary packet. If the first message serial number is not smaller than the second message serial number, step S 719  is executed to delete the first temporary packet. 
     Otherwise, if the first message serial number is smaller than the second message serial number, step S 711  is executed, where the first temporary packet is transmitted. Subsequent to step S 711  is step S 713  where the first temporary packet is received and the first message serial number is updated into the second message serial number. Then, in step S 715 , a second positioning packet includes a second message serial number that is received, and in step S 717 , the second positioning packet is received. Finally, in step S 719 , the first temporary packet is deleted. 
     In addition to the aforesaid steps, the fifth embodiment can also execute all the operations and functions of the packet transmission system  6  of the fourth embodiment. The method in which the fifth embodiment executes these operations and functions will be readily appreciated by those of ordinary skill in the art based on the explanation of the fourth embodiment, and thus will not be further described herein. 
       FIG. 8  depicts a sixth embodiment of this invention, which is a packet update method adapted for use in a host apparatus of a packet transmission system, such as the host apparatus  15  described in the fourth embodiment. More particularly, the packet update method of the sixth embodiment may be implemented by a computer program product. When the computer program product is loaded in the host apparatus via a computer and a plurality of instructions embodied therein is executed, the packet update method of the sixth embodiment can be accomplished. This computer program product may be stored in a tangible machine-readable medium, such as a read only memory (ROM), a flash memory, a floppy disk, a hard disk, a compact disk, a mobile disk, a magnetic tape, a database accessible to networks, or any other storage media with the same function and well known to those skilled in the art. 
     The packet update method of the sixth embodiment comprises the following steps. Initially, in step S 801 , a first positioning packet includes a first message serial number that is received. Subsequent to step S 801  is step S 803  where a response packet is transmitted. Subsequently in step S 805 , a first temporary packet includes a second message serial number that is generated. Next, in step S 807 , the first message serial number of the first positioning packet is compared to the second message serial number of the first temporary packet. If the first message serial number is not smaller than the second message serial number, step S 813  is executed to delete the first temporary packet. 
     Otherwise, if the first message serial number is smaller than the second message serial number, step S 809  is executed, where the first temporary packet is transmitted to the mobile apparatus. Subsequent to step S 809  is step S 811  where a second positioning packet includes the second message serial number that is received. Finally, in step S 821 , the first temporary packet is deleted. 
     In addition to the aforesaid steps, the sixth embodiment can also execute all the operations and functions of the host apparatus  15  of the fourth embodiment. The method in which the sixth embodiment executes these operations and functions will be readily appreciated by those of ordinary skill in the art based on the explanation of the fourth embodiment, and thus will not be further described herein. 
     In summary, the packet transmission system, the packet transmission method, the packet update method, the host apparatus and the computer program product thereof for the packet transmission system of this invention determine whether the content of an mobile apparatus has not been updated yet by comparing the positioning packet received via the host apparatus against the temporary packet stored therein to determine whether to transmit the temporary packet stored in the host apparatus to the mobile apparatus. Upon receiving the temporary packet, the mobile apparatus transmits another positioning packet to the host packet to confirm that the message contained in the temporary packet has been received by the mobile apparatus. This may not only prevent repeated transmission of the packets which would otherwise cause waste of network resources, but also accomplish the positioning purpose by using simple two-way transmission, thus further reducing power consumed in and enhancing the reliability of positioning the mobile apparatus. 
     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.