Method and enodeb for forwarding downlink and uplink packets based on s1 handover

Abstract

A method for forwarding downlink packets based on S1 handover is disclosed. The method includes: numbering a packet not processed by using PDCP according to a message that carries PDCP Serial Number (SN) information if downlink packets to be forwarded include the packet not processed by using PDCP; and sending the downlink packets to the UE according to the PDCP SN corresponding to the packet included in the downlink packets. A method for forwarding uplink packets based on S1 handover is disclosed. The method includes: receiving state report information of the packet sent by the target eNodeB; and sending the packet according to the state report information of the packet. Another method for forwarding downlink packets based on S1 handover and an eNodeB are disclosed. Through the embodiments of the present invention, the packets are forwarded without loss in the case of S1 handover.

1 . A method for forwarding downlink packets based on S1 handover, comprising:
 numbering a packet not processed by using Packet Data Convergence Protocol (PDCP) according to a message that carries PDCP Serial Number (SN) information, if downlink packets to be forwarded include the packet not processed by using PDCP;   sending the downlink packets to a User Equipment (UE) according to the PDCNs of packages included in the downlink packets.   
   
   
       2 . The method according to  claim 1 , wherein the downlink packets further include a packet that is processed by using PDCP and carries a PDCP SN;
 wherein, sending the downlink packets to a UE according to the PDCNs of packages included in the downlink packets, comprises:   sending the downlink packets to the UE, according to the PDCP SN of the packet that is processed by using PDCP and a PDCP SN of the packet that is not processed by using PDCP and is numbered and included in the downlink packets.   
   
   
       3 . The method according to  claim 2 , wherein the packet not processed by using PDCP is sent by a source evolved NodeB, eNodeB, or a target System Architecture Evolution, SAE, GateWay, SGW; the packet processed by using PDCP is sent by the source eNodeB;
 before the numbering step, further comprising:   receiving the message that carries PDCP SN information;   wherein the message that carries PDCP SN information is: a newly constructed control message sent by the source eNodeB through a source Mobility Management Entity, MME, and a target MME to the target eNodeB; or a newly constructed control message sent by the source eNodeB through an X2 interface to the target eNodeB directly.   
   
   
       4 . The method according to  claim 3 , wherein the newly constructed control message comprises: an initial PDCP SN assigned by the target eNodeB, a relationship between the initial PDCP SN and a GPRS Tunneling Protocol-User Serial Number, GTP-U SN;
 wherein the numbering a packet not processed by using PDCP comprises:   if the packet not processed by using PDCP carries GTP-U SN, assigning a PDCP SN to the packet not processed by using PDCP according to the initial PDCP SN assigned by the target eNodeB, and the relationship between the PDCP SN and the GTP-U SN.   
   
   
       5 . The method according to  claim 3 , wherein the newly constructed control message comprises: an initial PDCP SN assigned by the target eNodeB, and a relationship between the initial PDCP SN and a GTP-U SN;
 the method further comprises:   when receiving a special packet sent from the source eNodeB, assigning a PDCP SN to the special packet according to the initial PDCP SN assigned by the target eNodeB, wherein the special packet is obtained by the source eNodeB when the source SGW stops sending packets;   wherein a information carried in the special packet is set through an extended field of a GTP-U packet header, the special packet is constructed by the source SGW and sent to the source eNodeB, or the special packet is constructed by the source eNodeB.   
   
   
       6 . The method according to  claim 3 , wherein the newly constructed control message comprises: an initial PDCP SN assigned by the target eNodeB, and a relationship between the initial PDCP SN and a GTP-U SN; the packet not processed by using PDCP and sent by the source eNodeB is a category-2 packet, the packet not processed by using PDCP and sent by the target SGW is a category-3 packet;
 the method further comprises:   obtaining a relocation request message sent from the source MME through the target MME, wherein the relocation request message carries the GTP-U SN of the packet finally sent by the source SGW to the source eNodeB.   wherein the numbering a packet not processed by using PDCP comprises:   if the category-2 packet and the category-3 packet each carries a GTP-U SN,   assigning a PDCP SN that begins from the initial PDCP SN to the category-2 packet according to the order of GTP-U SNs of the category-2 packets until the GTP-U SN of the category-2 packet is equal to the GTP-U SN−1 of a packet that is finally sent by the SGW to the target eNodeB; assigning a PDCP SN to the category-3 packet on the basis of the maximum PDCP SN of the category-2 packets, according to the order of the GTP-U SNs of the category-3 packets.   
   
   
       7 . The method according to  claim 2 , wherein the packet not processed by using PDCP is sent by a source evolved NodeB (eNodeB) or a target System Architecture Evolution (SAE) GateWay (SGW); the packet processed by using PDCP is sent by the source eNodeB; the packet processed by using PDCP is a category-1 packet, the packet not processed by using PDCP and sent by the source eNodeB is a category-2 packet, the packet not processed by using PDCP and sent by the target SGW is a category-3 packet. 
   
   
       8 . The method according to  claim 7 , wherein the message that carries PDCP SN information is a relocation request sent by the source eNodeB in a handover process;
 the PDCP SN information is information about the relationship between the PDCP SN and a GPRS Tunneling Protocol-User Serial Number (GTP-U SN).   
   
   
       9 . The method according to  claim 8 , wherein the information about the relationship between the PDCP SN and the GTP-U SN is a specific value of the PDCP SN and a specific value of the GTP-U SN, or a corresponding relationship between the PDCP SN and the GTP-U SN. 
   
   
       10 . The method according to  claim 7 , wherein the message that carries PDCP SN information is a handover confirm message sent by the UE in a handover process, the PDCP SN information is a maximum PDCP SN of the packet received by the UE. 
   
   
       11 . The method according to  claim 10 , wherein the numbering a packet not processed by using PDCP comprises:
 if the packet not processed by using PDCP carries no GTP-U SN, assigning a PDCP SN to the packet not processed by using PDCP according to an order of receiving the packet not processed by using PDCP and the maximum PDCP SN;   if the packet not processed by using PDCP carries GTP-U SN, assigning a PDCP SN to the packet not processed by using PDCP according to a size order of the GTP-U SN and the maximum PDCP SN.   
   
   
       12 . The method according to  claim 10 , wherein the handover confirm message further comprises: a PDCP SN of a non-received category-1 packet; when the target eNodeB forwards the category-1 packets, forwarding the category-1 packet which corresponds to the PDCP SN and is not received by the UE to the UE. 
   
   
       13 . A method for forwarding uplink packets based on S1 handover, comprising:
 receiving state report information of a packet sent by a target evolved NodeB (eNodeB), wherein the state report information of the packet comprises: a PDCP SN of the packets not received by the source eNodeB, and an initial PDCP SN of a packet required to be sent sequentially; and   sending the packet according to the state report information of the packet, wherein the sending the packet according to the state report information of the packet comprises:   sending a packet which corresponds to the PDCP SN of the packets not received by the source eNodeB; or   sending sequentially the packet which carries a PDCP SN that is equal to or greater than the initial PDCP SN.   
   
   
       14 . The method according to  claim 13 , wherein the PDCP SN of the packet not received by the source eNodeB, and the PDCP SN of the packet required to be sent sequentially are included in a newly constructed control message, the newly constructed control message is sent by the source eNodeB through the source MME and the target MME to the target eNodeB; or the newly constructed control message is sent by the source eNodeB through an X2 interface to the target eNodeB directly. 
   
   
       15 . An evolved NodeB (eNodeB), wherein the eNodeB serves as a target eNodeB, comprising:
 a receiving module, adapted to receive a message that includes Packet Data Convergence Protocol Serial Number (PDCP SN) information; and   a sorting module, connected with the receiving module and adapted to perform PDCP SN numbering for a packet according to the message.   
   
   
       16 . The eNodeB according to  claim 15 , wherein the message that includes PDCP SN information is a newly constructed control message which is sent by the source eNodeB through the source Mobility Management Entity (MME) and the target MME to the target eNodeB;
 wherein the newly constructed control message comprises: an initial PDCP SN assigned by the target eNodeB, and a GPRS Tunneling Protocol-User Serial Number (GTP-U SN) corresponding to the initial PDCP SN; or,   wherein the newly constructed control message comprises: an initial PDCP SN assigned by the target eNodeB to the packet.   
   
   
       17 . The eNodeB according to  claim 15 , wherein the message that carries the PDCP SN information of a packet is a Relocation Request message sent by the source eNodeB through the source MME and the target MME;
 wherein the relocation request message carries the information about the relationship between the PDCP SN and a GTP-U SN.   
   
   
       18 . The eNodeB according to  claim 15 , wherein the message that carries PDCP SN information is a handover confirm message sent by a User Equipment (UE) that carries the maximum PDCP SN of the packet received by the UE. 
   
   
       19 . A communication system, comprising any of the devices according to  claim 15  to  claim 18 .