Embodiment
The method and system that the embodiment of the invention provides a kind of data service to switch.For making technical scheme of the present invention clearer, below with reference to accompanying drawing and enumerate embodiment, the present invention is described in more detail.
Please refer to Fig. 1, the flow chart of first embodiment of the method for switching for data service of the present invention.In the present embodiment, the The data Generic Routing Encapsulation (GRE, Generic RoutingEncapsulation) that BS sends encapsulates, and user terminal adopts non-ARQ to connect when source BS switches to target BS.
In the present embodiment, user terminal is travelling carriage (MS, Mobile Station).
The detailed process of the method that data service is switched comprises:
Step 101: when travelling carriage inserts source BS, when source BS sends datagram to MS, use SDUSN expansion head to inform the current associated sequence numbers information that sends to the SDU message of travelling carriage of MS;
In the present embodiment, the associated sequence numbers information of SDU message is the SDU sequence number of SDU message.Access service network gateway (ASN GW, Access Service Network Gateway) the The data GRE that sends to BS encapsulates, therefore, can adopt the SDUSN of the least-significant byte of GRE bag sequence number as the SDU message, also can take other algorithms to calculate the SDU SN of SDU message, as get low 7 etc. by GRE bag sequence number.The SDU SN of definition SDU message is generally 8 in the prior protocols, and value is 0 to 255.Therefore, in the present embodiment, the relevant information of SDU SN is the least-significant byte of the GRE bag sequence number of SDU message.
Described SDU sequence number can be generated according to the sequence number of GRE bag by BS, also can generate according to additive method to ASN GW by sending message, and at R4, carry serial number information in the message of R6 interface.
Source BS is sending medium access control (MAC, Media Access Control) protocol Data Unit (PDU, Protocol Data Unit) can expand the sequence number that son head (SDU SN extendedsub-header) is informed the SDU of the current transmission of MS by SDU SN the time, though source BS can send the sub-head of such expansion to each SDU, but MS can add up to the sequence number of follow-up SDU, so MS can know the sequence number of each SDU.
Step 102: after MS switched to target BS from source BS, MS went up header (SN reportheader) reports SDU SN from the SDU message to target BS by SN;
Step 103: target BS is according to the SDU SN of the SDU message that reports, the corresponding SDU message in location from the SDU message that target BS receives, and continue to send data to MS from described SDU start of heading.
The corresponding SDU message detailed process in described location comprises:
Steps A: target BS is according to the SDU SN of the SDU message that reports, calculates the GRE sequence number of the SDU message that MS need receive;
At first, after the R6 passage between hypothetical target BS and the GW was set up, the GRE sequence number of the SDU that target BS is received was G1, gets the SDU SN (be assumed to be S1) of the least-significant byte of G1 as this SDU message so;
Secondly, judge the SDU SN (being assumed to be S) of the SDU message that reports; And the size between the SDU SN S1 of the current SDU message of receiving of target BS:
If S>S1, and S-S1<128, then the GRE sequence number computing formula of the MS SDU message that need receive is: G=(G1 is high 24) moves to left 8+S;
If S<S1, and S1-S>128, then the GRE sequence number computing formula of the MS SDU message that need receive is: G=(G1 is high by 24+1) moves to left 8+S;
Other situations then illustrate to have unusual generation in the handoff procedure, cause data to have and lose, and target BS begins to send data to MS from the SDU of GRE sequence number G1.
Step B: target BS navigates to corresponding SDU message according to the GRE sequence number of calculating gained.
Be included in when switching in the SDU message that described target BS receives, source BS does not send to the SDU message of MS.The SDU message of the described MS of not sending to can return to target BS from source BS by GW, and source BS need carry the GRE serial number information of message during message in passback, when GW transmits described message and gives target BS, adopts the sequence number of the message that described source BS carries when the passback message; Also can resend target BS after the switching by the GW buffer memory before data service is switched; Can also be when data service is switched, source BS and target BS be carried out that data are two to be broadcast by GW, send to source BS and target BS simultaneously.
In the present embodiment, the The data GRE that BS sends and receives encapsulates, and therefore adopts the conversion of GRE bag sequence number to obtain the SDU SN of SDU message.The data that BS sends and receives can also adopt other packaged types to encapsulate.Described other packaged types have following characteristics: the corresponding SDU of R6 interface packets, and each encapsulated message all has a bag sequence number, message of every transmission, sequence number adds up 1; Perhaps SDU needs segmentation when the R6 interface transmits, can encapsulate earlier, segmentation again; Also can first segmentation, encapsulation again, but require all segmentations to have identical sequence number in this case, by other message identification segment informations, the SN that guarantees continuous SDU also is continuous, so then can adopt the pairing bag sequence number conversion of other packaged types to obtain the SDU SN of SDU message.
Please refer to Fig. 2, the flow chart of second embodiment of the method for switching for data service of the present invention.In the present embodiment, when MS switches to target BS from source BS, adopt ARQ to connect.
The detailed process of the method that described data service is switched comprises:
When step 201:MS inserts source BS, the SDU SN of source BS record SDU message and the corresponding relation of piece sequence number (BSN, Block Sequence Number);
Use fragmentation feature if ARQ connects, then SDU will carry out segmentation according to the automatic repeat requests data block size (ARQ_Block_Size) of default, and the SDU SN of source BS record SDU message is with the corresponding relation of the BSN of first ARQ data block;
If connecting, ARQ forbids segmentation, only corresponding ARQ data block of SDU then, and the SDU SN of source BS record SDU message is with the corresponding relation of the BSN of described ARQ data block.
Step 202: when MS when source BS switches to target BS, source BS informs the SDU that target BS does not send the earliest or do not replied and the BSN of pairing first piece of SDU message before thereof;
In the present embodiment, source BS informs the corresponding relation of the BSN of the SDU SN of SDU that target BS does not send the earliest or do not replied and one or more SDU before thereof and first piece.
Please, be the SDU SN of the received SDU message of target BS and the mapping table of BSN referring to following table 1.
Table 1 SDU SN and BSN mapping table
?SDU?SN |
S1 |
S2 |
Corresponding BSN |
B1 |
B2 |
In the above-mentioned table 1, S2 is the SDU SN of the SDU message that do not send the earliest or do not replied, and B2 is the BSN of first piece corresponding with described S2; S1 is the SDU SN (the SDU message of described S1 correspondence is sent by source BS) of a SDU message before the SDU message that does not send or do not replied, and B1 is the BSN of first piece corresponding with described S1.
In the present embodiment, SDU SN is 8, and the least-significant byte that can adopt GRE bag sequence number is as SDU SN, and the sequence number that also can adopt other packing forms is as SDN SN, and BSN is 11.
The comparison rule of SDU SN is: suppose 0<S2-S1<128, and perhaps S2-S1<-128, then S2 is greater than S1, otherwise is that S2 is less than S1; The comparison rule of BSN is: suppose 0<B2-B1<1024, and perhaps B2-B1<-1024, then B2 is greater than B1, otherwise is that B2 is less than B1.
Step 203:MS goes up header reports associated sequence numbers information from the SDU message to target BS by SN;
In the present embodiment, the associated sequence numbers information of SDU message is BSN.
MS knows that the mode of the BSN of SDU message is: source BS carries the BSN of described message when sending datagram to MS.
Step 204: the BSN of the SDU message that target BS reports according to MS, and the BSN of first piece of the source BS SDU message of informing, the SDU message that the location is corresponding, and send data to MS from described SDU start of heading;
If connecting, ARQ forbids segmentation, only corresponding ARQ data block of SDU so, and therefore the BSN of the SDU message that can report according to MS directly navigates to corresponding SDU message;
If connecting, ARQ uses fragmentation feature, the BSN (being assumed to be Bx) of the SDU message that target BS reports according to MS, and the BSN of first piece of the source BS SDU message of informing, navigate to corresponding SDU message, its concrete mode is: target BS navigates to corresponding SDU message by judging the size between Bx and B1, the B2.
Suppose that the BSN that MS reports target BS is Bx, and the S2>S1 in the table 1.
If Bx is greater than B1, and less than B2, then MS has received the part of the SDU message of S1 correspondence, so target BS begins to send data to MS from the position of (Bx-B1) * ARQ_Block_Size byte (the 0th byte is start byte) of the SDU message of S1 correspondence;
Have and lose (SDU between the SDU of Bx correspondence and this SDU SDU corresponding with B1 does not send to target BS) if Bx, then illustrates data less than B1, therefore the SDU start of heading from the S1 correspondence, send data to MS;
If Bx, then illustrates source BS greater than B2 and up-to-date SDU SN and the corresponding relation of BSN is not sent to target BS, carries out abnormality processing.
In the present embodiment, source BS does not send to the SDU message of MS when being included in switching in the SDU message that described target BS receives.This message can pass back to target BS by GW by source BS; Can also be when switching, source BS and target BS be carried out that data are two to be broadcast by GW, send to source BS and target BS simultaneously.
Please refer to Fig. 3, the structure chart of an embodiment of system who switches for data service of the present invention.Described data service switched system comprises travelling carriage 31, target BS 32 and source base station 33.Described travelling carriage 31 is used to provide the associated sequence numbers information of SDU message to target BS 32 and reception data; Described target BS 32 is used for the associated sequence numbers information of the SDU message that receiving mobile 31 provides, and according to the associated sequence numbers information of described SDU message, the SDU message that the location is corresponding, and continue to send data to travelling carriage 31 from described SDU start of heading; Described source base station 33 is used for the associated sequence numbers information to described travelling carriage 31 transmission SDU messages.
Described target BS 32 further comprises first receiving element 321, positioning unit 322, transmitting element 323.Described first receiving element 321 is used for the associated sequence numbers information of the SDU message that receiving mobile 31 provides; Described positioning unit 322 is used for the associated sequence numbers information of the SDU message that receives according to described receiving element 321, navigates to corresponding SDU message; Described transmitting element 323, the SDU start of heading that is used for being obtained from described positioning unit 322, send data to travelling carriage 31.
Described positioning unit 322 may further include:
Computing unit is used for the associated sequence numbers information of the SDU message that receives according to receiving element, calculates the Generic Routing Encapsulation bag sequence number of the SDU message that travelling carriage need receive;
Search the unit, be used for the Generic Routing Encapsulation bag sequence number of the SDU message that calculates according to described computing unit, find corresponding SDU message.
Described target BS 32 can also comprise:
Second receiving element is used for the SDU message that the reception sources base station do not send the earliest or do not replied and the piece sequence number of pairing first piece of SDU message before thereof.
Therefore, described positioning unit 322 may further include:
Size between the SDU message that does not send the earliest or do not replied that judging unit, the piece sequence number of the SDU message that is used to judge that travelling carriage reports and source base station are informed and the piece sequence number of each self-corresponding first piece of SDU message before thereof;
Search the unit, be used for judged result, find corresponding SDU message according to described judging unit.
Method and system, base station that the data service that provides by the embodiment of the invention is switched, the base station can be according to the relevant information of the SDU sequence number of feeding back, the SDU message that the location is corresponding also sends to travelling carriage, thereby after having guaranteed that user terminal switches to target BS from source base station, send to the continuity of the data of user terminal.
More than method and system, base station that a kind of data service provided by the present invention is switched be described in detail, used specific case herein principle of the present invention and execution mode are set forth, the explanation of above embodiment just is used to help to understand disclosed technical scheme; Simultaneously, for one of ordinary skill in the art, according to thought of the present invention, the part that all can change in specific embodiments and applications, in sum, this description should not be construed as limitation of the present invention.