JP5012994B2 - Communication method and communication system - Google Patents

Description

The present invention relates to a communications method and communications system.

  HSDPA (High Speed Downlink Packet Access), which is one of high-speed packet transmission technologies developed by 3GPP (3rd Generation Partnership Project), a well-known industry group, Information buffering in a base station host apparatus (RNC: radio network controller, the same applies hereinafter) and a serial number (hereinafter simply referred to as SN) assigned by the base station host apparatus are used.

  The principle will be described below with reference to the drawings.

  FIG. 1 shows a system configuration example of HSDPA. The figure shows that a function for transferring information transmitted from an external communication station through a network to a user terminal (hereinafter simply referred to as a terminal) 10 is a base station (so-called BTS: base transceiver station, hereinafter the same) 30-1 An example in which a so-called handover is performed on the station 30-2 is shown.

  Here, the handover is a function that is responsible for transferring information to the terminal 10 and is at the most suitable position for transferring information to the terminal 10 as the mobile station such as a mobile phone as the terminal 10 moves. This means the operation of sequentially transferring to the base station.

  The base station host apparatus 30 assigns SN-20 to the SN for each predetermined unit information amount of information received from the network (step S1) (step S2), and transmits it to the base station 30-1 (step S1). S3). At this time, the base station host apparatus 30 buffers such information internally.

  The base station 30-1 transmits the reception information to the terminal 10 without being aware of this SN (step S4). When handover is performed here, as a result, the base station host apparatus 30 transmits information SN-32 to be transmitted from that point to the base station 30-2 different from the base station 30-1 (step S5). .

  At this time, in the base station 30-1, it is assumed that, from the information received from the base station host apparatus 30, up to SN-20 to 27 is transmitted to the terminal 10 (step S5), and the radio line is disconnected by the handover. . In this case, since the information SN-28 to 31 that have not been transmitted cannot be transmitted, they are discarded (step S5).

  The base station 30-2 starts transmitting the information SN-32 received from the base station host apparatus 30 to the terminal 10 (step S7). At that time, the terminal 10 has not received the information SN-28 to 31. As described above, this is information that cannot be sent from the base station 30-1 to the terminal 10 at the time of handover and is discarded. The terminal 10 recognizes this lack of received information by referring to the SN attached to the information.

  As a result, the terminal 10 makes a retransmission request for the missing received information to the base station host apparatus 30 through the base station 30-2 (step S8). In response to this, the base station host apparatus 30 transmits the corresponding information SN-28 to 31 to the base station 30-2 (step S9). The base station 30-2 transmits the received information SN28 to 31 to the terminal 10 (step S10).

  As a result, the terminal 10 can supplement the missing information and ensure the continuity of the information.

  Since the base station host apparatus 30 buffers the information transmitted to the base station as described above, when there is a retransmission request from the terminal 10 as described above, the buffered information is transmitted.

  FIG. 2 shows another conventional example. This example is the method disclosed in Patent Document 2.

  In this method, the SN is not assigned, a transmission serial number (hereinafter simply referred to as TSN) is given, and the continuity of information is ensured by the TSN.

  In FIG. 2, the base station 30-1 receives information from the external communication station through the network, shakes TSN-12-14 (step S12), and transmits information TSN-12-13 to the terminal 10 (step S12). S13).

  When a handover occurs here, the external communication station transmits information to be transmitted thereafter to the handover destination base station 30-2 (step S14). The base station 30-1 transfers the information TSN-14 that can no longer be transmitted to the terminal 10 due to the handover to the handover destination base station 30-2 (step S15).

  The base station 30-2 waits for the transfer of the information from the base station 30-1 (step S15), and during that time, the information received from the external communication station is buffered without being transferred to the terminal 10.

  When the information TSN-14 is received from the base station 30-1, it is transmitted to the terminal 10 (step S16). At this time, the base station 30-2 assigns TSN-15 to the information transmitted from the external communication station after the handover and buffered as described above, and transmits the information to the terminal 10 (step S7).

  In the case of FIG. 2, as described above, the handover destination base station 30-2 waits for transfer of untransmitted information from the handover source base station 30-1. And after receiving this, it transmits to the terminal 10, and the information transmitted from the external communication station after the handover is transmitted to the terminal 10. As a result, the terminal 10 can receive information in a predetermined order without loss of received information due to handover.

JP 11-331208 A JP 9-186704 A

3GPP TS25.321 3GPP TS25.322

  In the case of the conventional example of FIG. 1, the terminal 10 recognizes the lack of received information by referring to the SN, and makes a retransmission request for the missing information to the base station host apparatus 30. By going through such a process, it takes time to finally secure the continuity of information, thereby causing information delay.

  In the case of this example, as described above, the base station host apparatus 30 needs to buffer transmitted information in preparation for a retransmission request from the terminal 10. For this reason, the base station host apparatus 30 needs to secure a storage capacity for buffering transmitted information.

  In the case of the conventional example of FIG. 2, the handover destination base station 30-2 performs handover until it receives transfer of untransmitted information TSN-14 from the handover source base station 30-1 in order to ensure continuity of transmission information. Information TSN-15 received later from the external communication station cannot be transmitted. This causes information delay. Further, in this case, transmission of information to the terminal 10 is interrupted while waiting for transfer of untransmitted information from the base station 30-1. As a result, the corresponding communication channel is not used during that period, and communication resources cannot be effectively used.

  The present invention has been made in view of the above problems, and minimizes the delay of information generated at the time of handover, minimizes the storage capacity to be secured in the base station host apparatus 30, and effectively uses communication resources. An object is to provide a communication system to obtain.

  In the present invention, in order to achieve the above object, when the function of the first communication station having the transfer function when the second communication station receives the predetermined information is transferred to another first communication station. The other first communication station receives the transfer of the predetermined information from the first communication station and transfers it to the second communication station. The predetermined information transferred from the first first communication station to the second communication station via the other first communication station, and the second information directly from the other first communication station. Predetermined identification information for distinguishing from the predetermined information transferred to the communication station is added.

  As described above, when the function of transferring information is shifted from one first communication station as a base station to another first communication station, that is, at the time of handover, Information that has not yet been transferred to the second communication station is transferred from the first communication station of the handover source. This untransmitted information is finally transferred from the other first communication station to the second communication station.

  According to this method, information that has not been transmitted to the second communication station by the first communication station of the handover source is not discarded, and the other first communication station of the handover destination is finally And transmitted to the second communication station. As a result, there is no loss of received information in the second communication station, and there is no need to make a retransmission request. Therefore, information delay is minimized.

  In the present invention, the transfer of the information transfer function, that is, the information directly transferred from the other first communication station to be handed over to the second communication station, and the first communication of the handover source Predetermined distinguishing information for distinguishing information transferred from the station via the other first communication station to the second communication station is added.

  As described above, information transmitted from the first first communication station of the handover source to the second communication station via the other first communication station of the handover destination and the first first communication station directly When the information transmitted from the other first communication station to the second communication station is received by the second communication station without passing through, the information reception order may be changed. Even in such a case, as described above, by adding predetermined identification information for distinguishing these pieces of information, the predetermined identification information is finally received at the second communication station that is finally received. By referring to the information, continuity of information can be ensured.

  As described above, according to the present invention, information is not discarded, so that a retransmission request is not required, and delay of information due to retransmission control is prevented.

  Further, since no retransmission request is generated, it is not necessary to secure a storage capacity for buffering transmitted information in preparation for the retransmission request in the upper station.

  In addition, due to the function of the discrimination information, the other first communication station of the handover destination waits for the transfer of untransmitted information from the first communication station of the handover source, and after that is received, it is buffered until then. It is not necessary to go through the process of performing transmission after arranging the order together with the information that has been received, and information received after handover can be transmitted immediately. Therefore, effective use of communication resources can be achieved.

It is a figure for demonstrating the example of a conventional communication system. It is a figure for demonstrating the communication system of the other conventional example. It is a figure for demonstrating the communication system by one Example of this invention. It is a time chart for demonstrating an example of a conventional communication system. It is a time chart for demonstrating the communication system of the other conventional example. 3 is a time chart for explaining a communication method according to an embodiment of the present invention; It is a time chart for demonstrating the communication system by the other Example of this invention. It is a block diagram for demonstrating the structure of each communication apparatus in the communication system by an example of the past. It is a block diagram for demonstrating the structure of each communication apparatus in the communication system by the other conventional example. It is a block diagram for demonstrating the structure of each communication apparatus in the communication system by one Example of this invention. It is a block diagram for demonstrating the structure of each communication apparatus in the communication system by the other Example of this invention. It is a figure which compares and shows the operation sequence (a) of the communication system of an example of the past, and the operation sequence (b) of the communication system by the other Example of this invention. It is a figure which compares and shows the operation sequence (a) of the communication system of the other conventional example, and the operation sequence (b) of the communication system by one Example of this invention.

  Hereinafter, the configuration of the embodiment of the present invention will be described in detail with reference to the drawings.

  FIG. 3 is a diagram for explaining the operation in the communication system according to an embodiment of the present invention when handing over from the base station 30-1 to the base station 30-2.

  In the figure, the base station 30-1 assigns TSN12 to TSN12 (step S22) to the information received from the external communication station 100 through the network (step S21), and transmits it to the terminal 10 (step S23).

  When the handover is performed here, the external communication station 100 stops information transmission to the base station 30-1, and starts transmission toward the base station 30-1 (step S4).

  The base station 30-1 transfers untransmitted information TSN-14 to the terminal 10 to the base station 30-2 (step S25). The base station 30-2 transmits the information transferred from the base station 30-1 (step S25) to the terminal 10 without changing the TSN assigned by the base station 30-1 (step S26).

  The base station 30-2 assigns TSN-33 as a new TSN to the information directly received from the external communication station (step S24) and transmits it to the terminal 10 (step S27).

  Here, the terminal 10 has means for separately controlling the order of the TSN assigned by the base station 30-1 and the TSN assigned by the base station 30-2. As a result, even if both are present, it can be restored in the correct order (step S28).

  Hereinafter, examples of the present invention will be described in more detail with reference to FIGS.

  For the purpose of helping understanding of the features of the embodiment of the present invention, the description will be made in comparison with the above-described conventional example (FIG. 1) and the other conventional example (FIG. 2).

  FIG. 4 shows an example of an operation time chart in the case of the conventional communication method.

  Until time T1, the information received by the base station host apparatus 50 from the external communication station is transmitted to the terminal 10 through the transfer of the base station 30-1. The base station host apparatus 50 uses the so-called RLC (Radio Link Control) function to transmit the received information to the base station 30-1 after shaking the SN as described above. Further, the base station 30-1 sets an optimal packet size according to the status of the communication channel with the terminal 10 by the so-called MAC-hs (medium access control-high speed, the same applies hereinafter) function, and sets each packet. Wave the TSN and send it to the terminal 10.

  The terminal 10 confirms the continuity of the TSN and SN added to the received information by the same MAC-hs function and RLC function as described above, and transmits this to the host computer.

  If a handover (HO) occurs at time T1, in this example, the base station 30-1 discards untransmitted information in the received information. After the handover (T2), the base station host apparatus 50 transmits information to the base station 30-2. Similarly to the above, the base station 30-2 sets the packet size by the MAC-hs function, assigns a TSN to each packet, and transmits the packet to the terminal 10.

  Here, the lack of received information is recognized from the lack of continuity of SN by the RLC function of the terminal 10, and a retransmission request is made to the base station host apparatus 50. The terminal 10 interrupts transmission of information to the host computer by the RLC function in order to ensure continuity of information transmitted to the host computer until the corresponding information is retransmitted. Meanwhile, information received from the base station 30-1 is buffered in the terminal 10.

  The base station host apparatus 50 receives the retransmission request from the terminal 10 and transmits the buffered corresponding information to the base station 30-2 between times T3 and T4. Receiving this, the base station 30-2 recognizes the SN as described above, sets the packet by the MAC-hs function according to the reception order, and transmits the packet to the terminal 10 with the TSN.

  The terminal 10 recognizes that the information related to the retransmission request has been received by referring to the SN attached to the information by the RLC function. Then, at time T1 when the corresponding information is satisfied, together with the reception information buffered so far, the information is arranged in order so that the continuity of the reception information is obtained according to the SN, and then transmitted to the host computer. .

  As described above, in the case of the conventional communication method, the terminal 10 makes a retransmission request for the missing information and transmits it to the host computer together with the received information during that time until the corresponding information is satisfied. Accordingly, transmission to the host computer is interrupted during this period, that is, during times T1 to T4.

  FIG. 5 shows an operation time chart in the case of the communication system of another example of the conventional art.

  In this case, unlike the example of FIG. 4 described above, the base station host apparatus 50 is not provided. For this reason, the information transmitted from the external communication station is directly received by the base station 30-1. As a result, the SN is not added to the received information.

  Similarly to the above, the base station 30-1 sets a packet by the MAC-hs function, and transmits the packet to the terminal 10 with a TSN.

  As described above, when a handover occurs at time T1, information received by the base station 30-1 during the handover, that is, between times T1 and T3, cannot be transferred to the terminal 10. In this example, this is not discarded, but is transferred to the handover destination base station 30-2.

  The base station 30-2 buffers the information received after the handover (time T2) without transmitting it to the terminal 10, and waits for transfer of untransmitted information from the handover source base station 30-1. Further, the base station 30-2 receives the notification of the TSN information from the base station 30-1 by the MAC-hs function, and takes over the TSN numbering to TSN-14. Thereafter, the TSN is continuously assigned to the reception information according to the inherited numbering (TSN-15 to 15).

  When the transmission of untransmitted information (TSN-14) is received from the base station 30-1 between times T13 and T14, the base station 30-2 refers to the TSN attached to the received information by the MAC-hs function. Thus, the information is rearranged according to the continuity of information (TSN-14 ~) and then transmitted to the terminal 10 (time T14).

  The terminal 10 confirms the continuity of the information by referring to the TSN attached to the received information by the MAC-hs function, and transmits it to the host computer.

  As described above, according to another conventional communication method, the information received during the transmission until the untransmitted information TSN-14 is transferred from the handover source base station 30-1 to the handover destination base station 30-2. It is necessary to buffer TSN-15 to TSN-17, and it is necessary to secure storage capacity.

  Further, the base station 30-2 suspends information transmission to the terminal 10 while waiting for the transfer of the untransmitted information TSN-14 from the base station 30-1 (time T2 to T14). Accordingly, effective use of the corresponding communication resource cannot be achieved during that time.

  FIG. 6 shows an operation time chart in the case of a communication system according to an embodiment of the present invention (corresponding to FIG. 3).

  In this case, the base station host apparatus 50 is omitted as in the case of the other conventional example described above with reference to FIG.

  The difference from the example of FIG. 5 is that, after handover (T1 to T2), the handover destination base station 30-2 receives the untransmitted information TSN-14 from the handover source base station 30-1 while it is being transferred. The received information is not buffered but transmitted to the terminal 10 as it is. At that time, for example, the base station 30-2 receives from the terminal 10 in advance a notification of a number that does not possibly overlap with the TSN attached to the information received by the terminal 10 from the handover source base station 30-1.

  In the case of the example of FIG. 6, the last information received by the terminal 10 is TSN-13. Therefore, in the terminal 10, it is predicted that the TSN of the untransmitted information included in the handover source base station 30-1 is TSN-14 or later. Accordingly, the terminal 10 notifies the handover destination base station 30-2 of, for example, TSN-0 as a number that does not possibly overlap with those numbers. Receiving this, the base station 30-2 sequentially assigns TSNs to information received after the handover (T2) with TSN-0 as an initial value, and transmits the information to the terminal 10 without buffering.

  When the untransmitted information TSN-14 is received from the base station 30-1 at time T13, the base station 30-2 transmits it to the terminal 10 as it is without changing the TSN (T13 to T14).

  The terminal 10 manages the TSN of the reception information before the handover by the MAC-hs function 11-1. At time T2, information having TSN (TSN-0) having no continuity with TSN (to TSN-13) of received information so far is received. When this is detected, the MAC-hs function 11-1 activates a separate MAC-hs function 11-2. The new MAC-hs function 11-2 manages TSNs (TSN-0) that have no continuity.

  Thereafter, when the untransmitted information TSN-14 is transmitted via the handover source base station 30-1 at times T13 to T14, the MAC-hs function 11-1 of the terminal 10 receives this and manages it until then. The continuity with the TSN (-TSN-13) that was being used is detected. The terminal 10 obtains continuity of information based on this.

  That is, the information TSN-14 related to the detection of information continuity by the MAC-hs function 11-1 that has been managing the TSN from the beginning, and the information continuity by the MAC-hs function 11-2 activated after the handover. In contrast to the information TSN-0 to TSN-2, the former information TSN-14 is treated as information continuous to the information originally managed, and the latter newly managed TSN-0 to TSN-2 It is treated as information that follows. As a result, the terminal 10 rearranges the received information as a series of information in the order of TSN-14, TSN-0 to TSN2, and transmits them to the host computer.

  According to this method, a TSN that does not overlap with the TSN before the handover is newly assigned to the information after the handover without adding the SN as an absolute number that does not depend on the handover, Information before and after handover can be clearly distinguished. As a result, the untransmitted information received by the terminal 10 with a timing delay by passing from the handover source base station 30-1 to the handover destination base station 30-2 is not passed through the base station 30-1. It can be reliably distinguished from the information transmitted directly from the base station 30-2. Therefore, the terminal 10 can reliably obtain continuity of information.

  Each base station 30-1 and 30-2 is assumed to have a function of allocating and buffering a retransmission control TSN and performing retransmission control using the TSN with the terminal 10. Similarly, the terminal 10 has a function of performing retransmission control with the base station using TSN.

  In this method, in order to distinguish the information, the TSN attached to the base station 30-1 and the base station 30-2 may be different from each other, so that predetermined information may be attached to the TSN.

  Further, in this method, after the handover, the terminal 10 receives a new (proprietary) TSN without buffering information received before the untransmitted information TSN-14 is transferred from the base station 30-1. Send to. Therefore, the transmission of information from the base stations 30-1 and 30-2 to the terminal 10 is not interrupted during that time (T2 to T14). Therefore, the communication resources between them can be used effectively.

  Further, in this method, in order to facilitate continuity between received information before and after the handover, the last value (TSN-14) of the TSN attached by the handover source base station 30-1 and the handover destination base station 30- It is desirable to provide a configuration in which the terminal 10 is notified of the TSN value (TSN-0) that is initially assigned by 2. As a result, the terminal 10 can easily ensure continuity of information by combining the final TSN number and the head TSN number.

  Also, the terminal 10 notifies the base station 30-2 of the TSN number currently used with the base station 30-1 together with information notifying the occurrence of the handover, and the base station 30-2 receiving this May be used from, for example, a TSN number obtained by adding 20 to the TSN number used in the base station 30-1.

  In addition, the terminal 10 transmits a TSN number (for example, a value obtained by adding 20) having a value sufficiently separated from the TSN number currently used with the base station 30-1 together with information notifying the occurrence of handover. 30-2 may be used, and the base station 30-2 may use this as the initial value of the TSN. In this case, the base station 30-2 does not need to notify the terminal 10 of the initial value of the TSN.

  The untransmitted information in the base station 30-1 preferably includes information that the base station 30-1 has already transmitted to the terminal 10 but has not been confirmed for reception from the terminal 10. By treating such information, that is, information once transmitted from the base station 30-1 but not received in the complete state by the terminal 10 as untransmitted information, the base station 30- including such information is also included. 1 is transferred to the base station 30-2. As a result, the terminal 10 can reliably obtain continuity of information.

  At that time, whether the information to be transferred to the base station 30-2 is pure untransmitted information or whether the base station 30-1 has been transmitted but has not been confirmed for reception from the terminal 10 It is desirable to notify the distinction. As a result, in the base station 30-2, if it is pure untransmitted information, an optimum packet size corresponding to the communication quality between the base station 30-2 and the terminal 10 is set, and the TSN number is reassigned and transmitted. On the other hand, if the information has not been confirmed to be received, it can be recognized that it is necessary to transmit with the packet size as it is.

  This is different from the case of pure untransmitted information, and it is highly likely that once transmitted information, the terminal 10 that has received the packet has already recognized its packet size. In such a case, if the packet size is changed when retransmitting, the terminal 10 receives a packet different from the already recognized packet size, which may cause problems such as difficulty in recognizing the identity of information. It is.

  Also, the base station 30-2 is configured to transmit the information transferred from the base station 30-1 to the terminal 10 with a higher priority than that received directly without going through the base station 30-1. Is desirable.

  Next, the contents of the communication system according to another embodiment of the present invention will be described with reference to FIG.

  In this case, the base station host apparatus 50 ′ is used as in the conventional example described with reference to FIG. However, unlike the conventional example, the base station host apparatus 50 ′ does not need to buffer already transmitted information in preparation for a retransmission request, and therefore does not need to secure a storage capacity.

  In the system according to another embodiment of the present invention, the base station host apparatus 50 ′ is used as described above, and the SN is assigned to the transmission information there. This SN indicates the order of a series of information. Even when the information transmission order is changed before and after the occurrence of the handover, the SN is finally attached to the received information by the RLC function 12 of the terminal 10. By referring to this SN, the continuity of received information is ensured.

  4 is different from the conventional example in FIG. 4 in the time of handover (T1 to T2), the base station 30-1 does not discard the untransmitted information SN-28 to SN-31 that can no longer be transmitted to the terminal 10, and It is to transfer to the base station 30-2. Since the untransmitted information is transmitted to the terminal 10 by the base station 30-2, the terminal 10 can obtain all necessary information without making a retransmission request.

  Therefore, in the terminal 10, even if the continuity of the received information is lost during the handovers T1 to T2 (-SN-27, SN-32), a retransmission request is thereby made to the base station host apparatus 50 '. Do not do. And it waits until the defect information SN-28 to SN-31 is transmitted from the base station 30-1 via the base station 30-2 (T13 to T14). In the meantime, as in the example of FIG. 4, the information SN-32 to SN-37 received from the base station 30-2 is buffered, and transmission to the host computer is interrupted.

  When the missing information SN-28 to SN-31 are transmitted (T14), the base station 30-2 transmits them to the terminal 10 and continuously receives the received information SN-32 to buffer as described above. SN-37 is transmitted to the terminal 10. As a result, the continuity of received information is ensured in the host computer.

  In the communication system according to another embodiment of the present invention, it is not necessary to use the independent base station host apparatus 50 ′ as the function of allocating the SN. For example, any one of the base stations may have the function. In this case, it is desirable that the base station that first assigned the SN continues to assign the SN number until communication is disconnected. Furthermore, it is desirable that the function of assigning the SN number is transferred to the base station when the traffic amount is small or zero in a certain base station.

  Similarly to the above-described embodiment of the present invention with reference to FIG. 7, each base station 30-1 and 30-2 buffers and retransmits a TSN for retransmission control, and uses this TSN with the terminal 10. It is assumed that it has a function of performing retransmission control. Similarly, the terminal 10 also performs retransmission control with the base station using the TSN, and performs order control using SN as described above.

  When a handover occurs, the base station 30-1 transfers untransmitted information to the handover destination base station 30-2.

  As the handover occurs, the terminal 10 resets the TSN (T2), and the SN is continued as it is.

  Similarly to the above-described embodiment, the untransmitted information of the base station 30-1 preferably includes information transmitted from the base station 30-1 to the terminal 10 but not confirmed for reception from the terminal 10. Such information, that is, information that has been once transmitted from the base station 30-1 but not received in the complete state in the terminal 10 is also treated as untransmitted information, so that such information is included in the base station 30. -1 is transferred to the base station 30-2, and the terminal 10 that receives it through the base station 30-2 can reliably obtain continuity of information.

  At this time, the base station 30-1 distinguishes whether the information to be transferred is pure untransmitted information or information that has been transmitted but not received by the terminal 10 with respect to the base station 30-2. It is desirable to notify. As a result, in the base station 30-2, if it is pure untransmitted information, it becomes possible to retransmit the TSN number with the optimum packet size according to the communication quality between the base station 30-2 and the terminal 10. If the information has not been confirmed to be received, it can be recognized that it is necessary to transmit with the packet size as it is.

  As in the case of the embodiment, it is desirable that the base station 30-2 is configured to transmit the data transferred from the base station 30-1 to the terminal 10 by raising the priority.

  Next, with reference to FIGS. 8 to 11, a description will be given of the configuration of a communication apparatus for realizing the communication method according to the conventional examples and the embodiments of the present invention.

  FIG. 8 is a block diagram showing a configuration of each communication apparatus in the case of realizing the communication method according to the conventional example described above with reference to FIG.

  The illustrated base station host apparatus 50 includes a PDU (packet data unit) 51, an SN adding unit 52, and a buffer 53.

  The PDU 51 divides information received from the external communication device into predetermined information units. The SN assigning unit 53 assigns an SN to each information unit divided in this way. The buffer 53 buffers transmitted information in preparation for a retransmission request.

  The base stations 30-1 and 30-2 that receive information from the base station host apparatus 50 include a TSN adding unit 31, a buffer 32, a modulating unit 33, and a discarding unit 34.

  The TSN assigning unit 31 determines an optimum packet size according to the state of the communication channel with the terminal 10, collects information for the size, and shakes the TSN. The buffer 32 buffers transmission information for retransmission control with the terminal 10. The modulation unit 33 generates a transmission signal modulated with transmission information in order to perform radio transmission to the terminal 10. As described above, the discard unit 34 discards information that can no longer be sent to the terminal 10 at the time of handover.

  A terminal 10 (that is, a mobile phone or the like) that receives information transmission from the base stations 30-1 and 30-2 includes a demodulation unit 9, a TSN (retransmission) order control unit 11, and an SN (retransmission) order control unit 12.

  The demodulation unit 9 demodulates the signals transmitted from the base stations 30-1 and 30-2 to obtain reception information, and the TSN (retransmission) order control unit 11 having a buffer function includes the base stations 30-1 and 30-2. And retransmission control by TSN. Similarly, the SN (retransmission) order control unit 12 having a buffer function performs retransmission control by SN with the base stations 30-1 and 30-2.

  FIG. 9 is a block diagram showing a configuration of each communication apparatus in the case of realizing a communication method according to another conventional example described above with reference to FIG.

  As described above, the base station host apparatus 50 is omitted in this example.

  Base stations 30-1 and 30-2 that receive information from an external communication station 100 through a network include a TSN adding unit 31, a buffer 32, a modulation unit 33, and a TSN order control unit 36.

  The TSN assigning unit 31 determines an optimum packet size according to the state of the communication channel with the terminal 10, collects information for the size, and shakes the TSN. The buffer 32 buffers transmission information for retransmission control with the terminal 10. The modulation unit 33 generates a transmission signal modulated with transmission information in order to perform wireless transmission to the terminal 10. As described above, the TSN order control unit 36 waits for transfer of untransmitted information from the handover source base station, and when receiving this, rearranges the information together with the buffered information.

  The terminal 10 that receives information transmission from the base stations 30-1 and 30-2 has a demodulation unit 9 and a TSN (retransmission) order control unit 11.

  The demodulation unit 9 demodulates the signals transmitted from the base stations 30-1 and 30-2 to obtain reception information, and the TSN (retransmission) order control unit 11 having a buffer function includes the base stations 30-1 and 30-2. And retransmission control by TSN.

  FIG. 10 is a block diagram showing the configuration of each communication apparatus in the case of realizing the communication method according to the embodiment of the present invention described above with reference to FIG.

  Also in this case, the base station host apparatus 50 is omitted as in FIG.

  The difference from the case shown in FIG. 9 is that the TSN sequence control unit 36 is not required for each of the base stations 30-1 and 30-2. Other parts are the same as those in FIG.

  Unlike the case of FIG. 9, the terminal 10 that receives information transmission from the base stations 30-1 and 30-2 has two TSN (retransmission) order control units 11-1 and 11-2. Other parts are the same as those in FIG.

  The reason for having two TSN (retransmission) order control units 11-1 and 11-2 in this manner is that the terminal 10 needs to perform two systems of TSN management as described above with reference to FIG. That is, these TSN (retransmission) order control units 11-1 and 11-2 respectively correspond to the MAC-hs functions 11-1 and 11-2 described above with reference to FIG.

  Further, the terminal 10 includes a combining unit 13 that combines the two systems of information obtained from the TSN (retransmission) order control units 11-1 and 11-2. This is because the TSN is allocated by the handover source base station (30-1 in the example of FIG. 6) and the TSN is allocated by the handover destination base station (30-2 in the example of FIG. 6). It has a function of combining the received information and ensuring the continuity of the information between them.

  FIG. 11 is a block diagram showing the configuration of each communication apparatus for realizing the communication method according to the embodiment of the present invention described above with reference to FIG.

  Basically, it has the same configuration as that of the conventional communication system described above with reference to FIG.

  Only parts different from the case of FIG. 8 will be described, and description of common parts will be omitted.

  First, as described above, the base station host apparatus 50 ′ does not require the buffer 53. This is because it is not necessary to prepare for a retransmission request from the terminal 10. This is because, as described above, in the base stations 30-1 and 30-2, information that could not be sent to the terminal 10 at the time of the handover is not discarded, and is transferred to the terminal 10 via the handover destination base station. .

  In the base stations 30-1 and 30-2, the discard unit 34 is not necessary, and a transfer control unit 38 is provided instead.

  At the time of handover, the transfer control unit 38 recognizes the handover destination base station (30-2) by notification from the terminal 10 if it is the handover source (30-1 in the example of FIG. 7). It has a function of transferring unsent information buffered in the buffer 32 to the handover destination base station without being able to send. On the other hand, when the base station itself is the handover destination base station (30-2), it has a function of receiving untransmitted information from the handover source base station 30-1.

  Next, referring to FIG. 12, the communication system (a) of the conventional example is compared with the communication system (b) according to another embodiment of the present invention.

  When the base station host apparatus 50 receives transmission information from the external communication apparatus 100 (step S101), it adds an SN (step S102) and transmits it to the base station 30-1 (step S103).

  In response to this, the base station 30-1 sets a packet, adds a TSN (step S104), and transmits it to the terminal 10 (step S106). The terminal 10 transmits the received information to the host computer 1 (step S107).

  If a handover (HO) occurs at that time, the base station 30-1 discards untransmitted information that could not be transmitted to the terminal 10 (step S108), and the base station host apparatus 50 thereafter transmits the transmission information to the handover destination. It transmits to the base station 30-2 (Step S108).

  In response to this, the base station 30-2 sets a packet, adds a TSN (step S110), and transmits it to the terminal 10 (step S111). Here, the terminal 10 recognizes the loss of information by referring to the SN of the received information (step S112). As a result, a retransmission request is made to the base station host apparatus 50 via the base station 30-2 (steps S112 and S114).

  In response, the base station host apparatus 50 retransmits the corresponding information to the terminal 10 via the base station 30-2 (steps S115, S116, and S117).

  Receiving this, the terminal 10 sends the received information to the host computer 1 in the same order according to the SN, together with the received information that has been buffered without being sent to the host computer (step S118).

  In this method, as described above, the terminal 10 recognizes the loss of received information by referring to the SN, makes a retransmission request to the base station host apparatus 50, waits for retransmission from the base station host apparatus 50, and receives the received information up to that time. To the host computer 1 together. For this reason, the information delay increases by the time required for retransmission.

  On the other hand, in the case of the communication system according to another embodiment of the present invention shown in FIG. 12B, as described above, after the handover, the handover source base station 30-1 does not discard the untransmitted information, and the handover destination base station 30 -2 (step S124). The base station 30-2 transmits this to the terminal 10 as it is (step S125).

  In the case of this embodiment, a base station host apparatus 50 ′ to which an SN is assigned (step S102) is provided, and the SN assigned here is not affected by the subsequent handover HO. Therefore, regardless of the receiving order at the terminal 10, the terminal 10 can appropriately determine the order of the received information, and rearranges the information accordingly, thereby ensuring the continuity of information and transmitting it to the host computer 1 (step S126). can do.

  Unlike the method shown in FIG. 12A, this method does not go through a retransmission process from the base station host apparatus 50 ′ for missing information. As a result, it is possible to effectively shorten the time required to transmit the reception information to the host computer 1 after finally ensuring the continuity of the information.

  Next, referring to FIG. 13, the communication method (a) of another conventional example will be described in comparison with the communication method (b) according to an embodiment of the present invention.

  When the base station 30-1 receives transmission information from the external communication device 100 (step S101), the packet is set, a TSN is assigned (step S131), and the transmission is performed to the terminal 10 (step S132). The terminal 10 transmits the received information to the host computer 1 (step S133).

  If a handover (HO) occurs at that time, the base station 30-1 transfers untransmitted information, which cannot be transmitted to the terminal 10 as a result, to the handover destination base station 30-2 (step S136).

  The base station 30-2 receives transmission information from the external communication device 100, and waits for transfer of untransmitted information from the base station 30-1 while buffering it without transmitting it (step S135). When this is received, the received information that has been buffered until then is sent to the terminal 10 in the same order (steps S137 and S138). The terminal 10 transmits the received information to the host computer 1 (step S139).

  In this method, as described above, the handover destination base station 30-2 suspends transmission to the terminal 10 until untransmitted information is transferred from the handover source base station 30-1. Accordingly, the corresponding communication resource during that period cannot be effectively used.

  In addition, since the base station 30-2 needs to buffer received information during that time, it is necessary to ensure storage capacity.

  On the other hand, according to the configuration of one embodiment of the present invention shown in FIG. 13B, untransmitted information is transferred from the handover source base station 30-1 to the handover destination base station 30-2 (step S1). The transmission to the terminal 10 is continued without interruption until S136). Meanwhile, the TSN is assigned to the information received from the external communication station in a manner that does not overlap with the TSN in the base station 30-1 as described above (step S141), and is transmitted to the terminal 10 (step S142).

  At that time, the reception information received by the terminal 10 from the external communication device 100 via the base station 30-2 directly without passing through the base station 30-1 (steps S135 and S142), and the base stations 30-1 and 30-2 (Steps S136 and 143) is received from the terminal 10 so that the TSN does not overlap as described above. As a result, regardless of the order of reception at the terminal 10, the terminal 10 can appropriately discriminate both, and thus can correctly grasp the order between the two. The terminal 10 can rearrange the information according to the grasped contents, and can ensure the continuity of the information and transmit it to the host computer 1 (step S144).

  As described above, according to the communication system according to the embodiment of the present invention shown in FIG. 13B, the communication resources from the base stations 30-1 and 30-2 to the terminal 10 are not unused, and can be effectively used. In addition, since the base station does not require a storage capacity for buffering received information while waiting for transfer of untransmitted information from the handover source base station, the required facilities of the base station can be effectively reduced.

The present invention can have the following configurations.
(Appendix 1)
A communication method for transmitting predetermined information to a second communication station via a plurality of first communication stations,
The second communication station receiving the predetermined information via one communication station of the plurality of first communication stations;
When the function of the first communication station when the second communication station receives the predetermined information is transferred to another first communication station, the other first communication station Receiving the transfer of the predetermined information from one first communication station, and transferring it to the second communication station;
The predetermined information transferred from the first first communication station to the second communication station via the other first communication station; and the second information directly from the other first communication station. A communication method comprising the step of attaching predetermined discrimination information for distinguishing from the predetermined information transferred to a communication station.
(Appendix 2)
The step of attaching the predetermined distinction information is when the function of the first communication station when the second communication station receives the predetermined information is transferred to another first communication station. The communication method according to claim 1, further comprising the step of uniquely assigning a number to the predetermined information directly received by the other first communication station without passing through the first communication station.
(Appendix 3)
The step of assigning a unique number to information received directly without passing through the first communication station is a predetermined used by the second communication station with the first communication station. (2) comprising the step of notifying the other first communication station of the number value of the number, and adding a predetermined value to the notified value in the other first communication station as an initial value. The communication method described in 1.
(Appendix 4)
The step of assigning a unique number to the information directly received without passing through the first communication station is a predetermined number used by the second communication station with the first communication station. A value obtained by adding a predetermined value to the number value is notified to the other first communication station, and the other first communication station adds a number with the notified value as an initial value. The communication method described.
(Appendix 5)
The one first communication station treats predetermined information that has already been transferred to the second communication station and has not yet received notification of reception confirmation as having not been transferred to the second communication station. The communication method according to any one of supplementary notes 1 to 4 having stages.
(Appendix 6)
The one first communication station determines whether the predetermined information to be transferred to the second communication station is untransferred or has not yet received a notification of reception confirmation to the other first communication station. Notify
The other first communication station sets an optimal packet size according to the communication status with the second communication station for the predetermined information that has not been transferred, and has not yet received a reception confirmation notification. The communication method according to appendix 5, wherein the packet is transferred without changing the packet size.
(Appendix 7)
The communication method according to claim 1, wherein the step of attaching the predetermined distinction information is performed before the plurality of first communication stations process the predetermined information.
(Appendix 8)
The plurality of first communication stations handle predetermined information that has already been transferred to the second communication station and has not yet received a notification of reception confirmation as having not been transferred to the second communication station. The communication method according to appendix 7, wherein:
(Appendix 9)
The communication method according to appendix 7 or 8, wherein the step of attaching the predetermined discrimination information is configured by any one of the plurality of first communication stations.
(Appendix 10)
The communication method according to appendix 9, wherein the operation of attaching the predetermined distinction information is configured to be continuously performed until communication in the communication station is disconnected.
(Appendix 11)
There is a communication device for transferring predetermined information to a predetermined communication station,
When the function of transferring the predetermined information to the predetermined communication station is transferred from another communication device, the predetermined information is transferred from the other communication device and transferred to the predetermined communication station. Means,
When transferring the function of transferring the predetermined information, the information transferred from the other communication device is re-transferred to the predetermined communication station and directly received without passing through the other communication device. A communication apparatus comprising means for attaching predetermined identification information for distinguishing the information transmitted from the predetermined communication station from that transmitted to the predetermined communication station.
(Appendix 12)
The means for attaching the predetermined distinction information is a means for attaching a unique number to information directly received without passing through the other communication device when the function of transferring the predetermined information is transferred from the other communication device. The communication device according to appendix 11, further comprising:
(Appendix 13)
Further, it comprises means for notifying the first value of the number assigned by itself to the predetermined communication station, and the other communication device notifies the final value of the number assigned by itself to the predetermined communication station. 12. The communication device according to 12.
(Appendix 14)
The means for attaching the predetermined distinction information receives a notification of a value of a predetermined number used with the other communication device from the predetermined communication station, and adds the predetermined value to the notified value Item 12. The communication device according to item 11, comprising means for assigning a number with the value as an initial value.
(Appendix 15)
The means for attaching the predetermined distinction information is notified by receiving a notification of a value obtained by adding a predetermined value to a value of a predetermined number used with the other communication device from the predetermined communication station. Item 12. The communication device according to item 11, comprising means for assigning a number with the value as an initial value.
(Appendix 16)
The information according to any one of appendices 11 to 15, wherein information that has already been transferred to the predetermined communication station and has not yet received a notification of reception confirmation is handled as information that has not yet been transferred. Communication device.
(Appendix 17)
Receives notification of whether the information has not been transferred yet or has not received notification of reception confirmation, and if the former, sets the optimum packet size according to the communication status with the predetermined communication station However, in the latter case, the communication apparatus according to appendix 16, wherein the packet is transferred without changing the packet size.
(Appendix 18)
The communication device according to appendix 11, wherein the means for attaching the predetermined distinction information is means for receiving the predetermined information and assigning a predetermined number.
(Appendix 19)
19. The communication apparatus according to appendix 18, wherein information that has already been transferred to the predetermined communication station and has not yet received a reception confirmation notification is handled as information that has not yet been transferred.
(Appendix 20)
20. The communication device according to appendix 18 or 19, wherein the communication device is configured to serve as a function of assigning the predetermined number when the traffic amount is small or zero.

1 Host computer 10 Terminal device 30-1, 30-2 Base station (device)
50, 50 ′ Base station host apparatus 100 External communication station

Claims (6)

A communication method for transmitting predetermined information to a second communication station via a plurality of first communication stations ,
The second communication station receives the predetermined information via a first communication station of one of the plurality of first communication stations;
When handing over from the one first communication station to another first communication station, the other first communication station receives the transfer of the predetermined information from the one first communication station, Transferring the transferred predetermined information to the second communication station;
The one first communication station transferring predetermined information that has not yet received a reception confirmation notification from the second communication station to the other first communication station;
The other first communication station transfers the predetermined information and the other first information transferred from the one first communication station to the second communication station via the other first communication station. Providing a different number for distinguishing from the predetermined information transferred directly from the communication station to the second communication station . Wherein the predetermined information transferred directly to the second communication station from the another first communication station directly from the host device different the other of the first communication station with the first communication station of the one The predetermined information received,
Communication method according to claim 1, wherein a. The other first communication station receives a notification of a number subsequent to a number indicating the order of reception given to the transferred predetermined information,
The number included in the notification received by the other first communication station is given to the predetermined information transferred directly from the other first communication station to the second communication station. An initial value of the number, which is updated each time the predetermined information is transmitted directly from the other first communication station to the second communication station .
Communication method according to claim 1, wherein a. A communication system for transmitting predetermined information to a second communication station via a plurality of first communication stations ,
The second communication station has means for receiving the predetermined information via a first communication station of one of the plurality of first communication stations,
The other first communication station receives the transfer of the predetermined information from the one first communication station at the time of handover from the one first communication station to the other first communication station. And means for transferring the transferred predetermined information to the second communication station,
The one first communication station has means for transferring predetermined information that has not yet received a notification of reception confirmation from the second communication station to the other first communication station,
The other first communication station transmits the predetermined information transferred from the first first communication station to the second communication station via the other first communication station and the other first communication station. communication system that further comprising a means for applying a different number for distinguishing between the predetermined information transferred directly to the second communication station from the communication station. Wherein the predetermined information transferred directly to the second communication station from the another first communication station directly from the host device different the other of the first communication station with the first communication station of the one The predetermined information received,
Communication system according to claim 4, wherein a. The other first communication station has means for receiving a notification of a number subsequent to a number indicating the order of reception given to the transferred predetermined information, and is received by the other first communication station . The number included in the notification is an initial value of a number given to the predetermined information that is directly transferred from the other first communication station to the second communication station . Updated each time the predetermined information is transferred directly from the first communication station to the second communication station ;
Communication system according to claim 4, wherein a.

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