Method of avoiding packet loss at a handover in a packet-based telecommunications network and handover method

• US 6,611,547 B1
• Filed: 01/06/2000
• Issued: 08/26/2003
• Est. Priority Date: 04/15/1997
• Status: Expired due to Term

• Current Assignee: Nokia Solutions and Networks US LLC (Nokia Corporation)
• Original Assignee: Nokia Telecommunications Oy (Nokia Corporation)
• Inventors: Rauhala, Kristian
• Primary Examiner(s): VANDERPUYE, KENNETH N
• Application Number:
  US09/402,343
• Time in Patent Office: 1,328 Days
• Field of Search: 370/331, 370/230, 370/235, 370/338, 370/401, 370/428, 370/429, 370/395.1, 455/436, 455/437, 455/438, 455/439, 455/440, 455/441, 455/442, 455/443, 455/412, 455/415
• US Class Current: 370/331
• CPC Class Codes: H04L 2012/5607 Radio
• CPC Class Codes: H04Q 11/0478 Provisions for broadband connections
• CPC Class Codes: H04W 36/02 Buffering or recovering information during reselection ; Modification of the traffic flow during hand-off

Abstract

The invention relates to a connection-oriented packet-based communication network, in which the terminal and the network access point of the terminal may move in the network. When the access point of the terminal changes during an active connection, the routing connection can also be changed from an old access point to a new one. The old access point may comprise buffered cells, which can be transferred to the new access point without packet loss. A connection from the old access point to the new one is established dynamically, when required. The connection establishment is controlled by a third network element, which is responsible for controlling the change of access point. The old access point can be arranged to send signaling messages and to establish a connection without requiring any additional intelligence at the access point. Upon the connection being established, the old access point sends buffered unsent packets to the new access point.

Claims

1. A method of transferring unsent packets from an old access point to a new access point in a packet-based connection-oriented telecommunications network, in which the access point of a terminal to the network may change during an active connection, the method comprising:

buffering at the old access point the packets which the old access point has not sent to the terminal before change of access point;

establishing a connection from the old access point to the new access point; and

transferring the buffered packets from the old access point to the new access point over said connection;

said establishing a connection further comprising;

generating a connection establishment signaling required for said connection establishment in a third network element, which is responsible for controlling the change of access point,

tunneling said generated connection establishment signaling to the old access point, and

transmitting said generated connection establishment signaling from the old access point to the new access point.

2. A method according to claim 1, wherein the tunneling comprises

encapsulating in the third network element a signaling message provided with an address of the actual destination into a packet provided with the address of the old access point;

sending the encapsulated signaling message to the old access point;

decapsulating the signaling message at the old access point; and

transmitting the signaling message forward on the basis of the address of the actual destination.

3. A method according to claim 1 or 2, further comprising

creating a connection release message in the third network element, after said buffered packets have been transferred from the old access point to the new access point;

tunneling the connection release message to the old access point; and

transmitting the connection release message from the old access point to the new access point.

4. A method according to claim 1 or 2, further comprising

using said connection as an extension of a path extension handover from the old access point to the new access point.

5. A method according to claim 1 or 2, wherein the telecommunications network is an ATM-based network and the packets are ATM cells.

6. A packet-based connection-oriented communications network, comprising an arrangement for transferring unsent packets from an old access point to a new access point, in which arrangement the access point of a terminal to the network changes during an active connection, the arrangement comprising:

means for buffering at the old access point the packets which the old access point has not sent to the terminal before change of access point; and

means for establishing a connection from the old access point to the new access point;

means for transferring the buffered packets from the old access point to the new access point over said connection, wherein said means for establishing a connection comprises;

means for generating a connection establishment signaling required for said connection establishment in a third network element, which is responsible for controlling the change of access point,

means for tunneling said generated connection establishment signaling to the old access point, and

means for transmitting said generated connection establishment signaling from the old access point to the new access point.

7. A network according to claim 6, wherein said tunneling means comprise

means in the third network element for encapsulating a signaling message provided with the address of the actual destination into a packet provided with the address of the old access point and for sending the encapsulated signaling message to the old access point; and

means for decapsulating the signaling message at the old access point and for restoring the original signaling message to be transmitted forward on the basis of the actual destination address.

8. A network according to claim 6 or 7, wherein the arrangement further comprises

means for creating a connection release message in the third network element, after said buffered packets have been transferred from the old access point to the new access point;

and

means for tunneling the connection release message to the old access point and for transmitting the connection release message from the old access point to the new access point.

9. A network according to claim 6 or 7, wherein said connection is an extension of a path extension handover from the old access point to the new access point.

10. A network according to claim 6 or 7, wherein the telecommunications network is an ATM-based network and the packets are ATM cells.

11. A network according to claim 10, wherein the telecommunications network is a wireless ATM network comprising mobile stations and at least one ATM switch connected to base stations, and wherein said third network element is an ATM switch and the access points are base stations.

12. A network according to claim 10, wherein the telecommunications network is a mobile network, comprising a plurality of mobile stations and base stations, at least one controlling element of a mobile network and an ATM transmission network interconnecting said controlling element of the mobile network and the base stations, and wherein said third network element is at least one of said controlling element of the mobile network and an ATM switch of the ATM transmission network and the access points are base stations.

13. A handover method for handing a terminal over from an old access point to a new access point during an active connection in a packet-based connection-oriented telecommunications network, the method comprising:

establishing a connection between the terminal and the new access point;

buffering at the old access point the packets which the old access point has not sent to the terminal before the change of access point;

routing an extension from the old access point to the new access point; and

transferring the buffered packets from the old access point to the new access point over said extension, said routing the extension comprises;

generating a routing signaling required for the routing in a third network element, which is responsible for controlling the change of access point;

tunneling said generated routing signaling to the old access point; and

transmitting said generated routing signaling from the old access point to the new access point.

14. A method according to claim 13, wherein the tunneling comprises

encapsulating, in the third network element, a signaling message provided with the address of the actual destination into a packet provided with the address of the old access point;

sending the encapsulated signaling message to the old access point;

decapsulating the signaling message at the old access point; and

transmitting the signaling message forward on the basis of the actual destination address.

15. A method according to claim 13 or 14, wherein the communications network is an ATM-based network and the packets are ATM cells.