Telecommunications – Radiotelephone system – Zoned or cellular telephone system
Reexamination Certificate
2001-07-30
2004-12-07
Kincaid, Lester G. (Department: 2686)
Telecommunications
Radiotelephone system
Zoned or cellular telephone system
C370S475000
Reexamination Certificate
active
06829483
ABSTRACT:
CROSS REFERENCE TO RELATED APPLICATION
This application claims priority of Great Britain Patent Application No. 0020581.5, which was filed on 21
st
Aug. 2000.
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to an improved method of operating a mobile telecommunications network, especially a method of addressing packets destined for a mobile terminal in a foreign network.
2. Description of Related Art
In third generation telecommunications networks such as GPRS (General Packet Radio Service) and EDGE (Enhanced Data-rate for GSM Evolution), when a mobile terminal moves into a foreign network, network connectivity is optionally maintained by the use of Mobile Internet Protocol (Mobile IP). In the home network, a Home Agent (HA) is set up which maintains the location information of the mobile by use of Binding Updates, i.e., registration of information sent to the HA by the mobile node.
Mobile IP has two working modes. The first is illustrated in
FIG. 1
; a mobile terminal is currently attached as Mobile Node (MN)
14
in a network different from its home network. The MN
14
is communicating with a Correspondent Node (CN)
12
. A Home Agent
16
is set up in the home network by the CN
12
, and a Foreign Agent (FA)
18
is set up in the foreign network. The FA
18
allocates a unique IP address for the visiting mobile, a Care of Address (COA) and this address is sent to the HA
16
in a Binding Update.
Packets for the mobile are encapsulated by the HA
16
and tunnelled along tunnel
20
to the FA
18
for transmission to MN
14
. In such encapsulation, an extra IP header is added to each packet, including the COA of the MN
14
. This is known as FA-COA working mode.
In the second working mode (not illustrated) there is no FA, the MN
14
is allocated a unique COA and encapsulated packets are tunnelled by HA
16
directly to MN
14
; this is known as Colocated Care of Address mode of working (CO-COA).
In both FA-COA and CO-COA modes of working, the encapsulation generates extra headers, and possibly only small payloads can be used, which results in inefficient transmission and inefficient use of expensive system and network resources, such as radio links. Further, encapsulation hides the flow identification, and the differentiation of classes of services is thus also disabled, so that Quality of Service (QoS) provision mechanisms, such as RSVP (Resource reSerVation Protocol) Int Serve, must be changed.
The disadvantages of encapsulation can be avoided by the use of Non Encapsulation Mobile IP technique, as set out in the applicant's co-pending patent application “Non-encapsulation Mobile IP” filed on 26 Feb. 1999 as no. 99301437.2. In this technique, the current COA of the mobile node is used as the destination address, and the original source address, i.e. the CN address, is maintained. For FA-COA working, this deletes a header of length at least 20 bytes and introduces a header of only 2 bytes; for CO-COA mode of working no header is introduced. However a disadvantage is that any firewall or egress filtering in the home network may reject such packets, because they have a source address different from the home network address.
SUMMARY OF THE INVENTION
It is an object of the invention to provide a method of packet addressing which overcomes the disadvantages set out above, and allows QoS to be provided.
According to the invention, a method of providing quality of service in a third generation mobile telecommunications system, in which packets are addressed to a mobile node which has a correspondent node in a home network and which is currently associated with a foreign network characterized by the steps of
sending a quality of service enquiry message from the correspondent node to the home network;
sending said quality of service enquiry message from the home network to the mobile node;
sending a quality of service response message from the mobile node to the home network by the same route as the enquiry message;
and sending a quality of service response message from the home network to the correspondent node only after receipt of the quality of service response message from the mobile node.
REFERENCES:
patent: 5793301 (1998-08-01), Patterson et al.
patent: 6452920 (2002-09-01), Comstock
patent: 2002/0015395 (2002-02-01), Karagiannis
patent: 2003/0021275 (2003-01-01), Shabeer
patent: 2004/0024901 (2004-02-01), Agrawal et al.
Kincaid Lester G.
Lucent Technolgies Inc.
Mehrpour N
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