Note: Descriptions are shown in the official language in which they were submitted.
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PATENT APPLICATION
DOCKET NO. P139a3CA
METHODS AND SYSTEM FOR INTER PACKET DATA SERVING NODE (PDSN)
HANDOVER AND MOBILITY IN A CDMA2040 NETWORK
z o BACKGROUND OF THE INVENTION
The present invention relates to radio telecommunication and more
particularly to systems and methods for handover between Packet Data Serving
Nodes (PDSNs) in a CDMA2000 network.
T~e~crinti~n ~f Rela . Art
Figure 1 shows a simplified block diagram for a Prior Art CDMA2000
(Code Division Multiple Access 2000) network 10, providing packet-switched
call routing through Packet Data Serving Nodes (PDSN) 16-17.
'The packet data network 10 provides services to a number of mobile nodes
ao (MN) 11-I2 (a CDMA2000 designation for mobile station) that access the
network I0 through a number of Radio Networks (RN) 13-14 via the air interface
15. The RNs 13-14 link to a number of PDSNs 16-17 using a Radio Packet (R-P)
interface 18, often but not necessarily over a first IP network 21. The MNs 11-
12
connect, over the underlying interfaces, to the PDSNs 16-17 using a Point to
2 5 Point Protocol {PPP} connection 24, as symbolically shown at the bottom of
the
figure. The PDSNs I6-17 are, for example, used as access concentrators,
concentarating the received transmissions before forwarding them over a second
IP
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network 19. This second IP network 19 is among other things connected to the
backbone network 22 with access to other networks (not shown) or directly to
said other networks. It is through this second IP network 19 that the PDSNs 16-
17
may connect to the Home Agent (HA) 20, the function of which will be partly
described below. An Authentication, Authorisation and Accounting (AAA) server
30 is connected to the rest of the network 10 through the second IP network
19.
The AAA server 30 is contacted in many instances that deal with security and
billing, such as for example during the set up of new PPP connections. It is
to be
understood that the PDSNs 16-17 may use the same HA 20 or different ones (of
which only one is shown in Figure 1).
The CDMA2000 network 10 described above is able to provide the mobile
user with two different packet data services, Simple IP and Mobile IP. In
Simple
IP, the user is provided with a dynamic IP address from the local FDSN and IP
routing service is provided by a service provider network. The user retains
this IP
1 s address as long as the PDSN remains in connection with the RN the user is
served
by. This means that handover, retaining active sessions, between different
PDSNs
is not possible, which is a major problem with Simple IP. It is, of course,
possible
for a MN to roam from one PDSN to another, but doing so means losing any
active sessions.
a o In Mobile IP howevex, inter-PDSN handover is possible. This is owing to
the fact that the Home Agent (HA) 20 acts as a kind of fix reference point for
the
MN 11-12. When the MN 11-12 receives packets from the outside, these packets
are sent to the HA 20, as the HA 20 is associated with the MN 11--12, and the
packets are sent from the HA 20 to the proper PDSN 16-17 that in turn forwards
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the packets to the MN 11-12. Therefore, inter-PDSN handover is made possible
by the fact that the HA 20 keeps track of where the MN 1 I-I2 is located.
As mentioned earlier, there is a PPP connection 24 between a MN 1I-12
and a PDSN 16-I7, while the further connection 25 is a Mobile IP (MIP)
connection in case of Mobile IP, and a normal IP connection or the like in
case of
Simple IP.
The inter-PDSN handover procedure for Mobile IP according to the Prior
Art is shown in Figure 2, which shows a MN 11, two PDSNs I6-17 and a HA 20,
as in figure 1. At first, with reference to Figure 2a, there exists a PPP
connection
a. 0 24 between the MN 11 and the first PDSN 16, as well as a MIP (Mobile IP)
connection 25 between then PDSN 16 and the HA 20. With reference to Figure
2b, to start the handover the PPP connection 24 is terminated and a new PPP
connection 26 is created between the MN I1 and the second PDSN 17. Then,
Figure 2c, the MIP connection 25 between the first PDSN 16 and the HA 20 is
replaced by a new MIP connection 27 between the second PDSN 17 and the HA
20. As can be seen, there is now a connection between the MN 11 and the HA 20
going through the second PDSN 17 instead of the first PDSN 16. As mentioned
earlier, there are no Prior Art handover methods for Simple IP.
Setting up a new connection is fairly cumbersome, as there is a lot of
2 o signalling back and forth, often negotiating various connection options.
There are
for example in PPP at least three different phases to go through: link set-up
{governed by the Link Connection Protocol - LCP), authentication (governed by
the Challenge Handshake Authentication Protocol - CHAP), and network level
configuration (governed by the IP Control Protocol - IPCP). A MIP connection
is
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also a rather complex matter.
It follows that some problems with the handover in CDMA2000 networks
are that Simple IP handover retaining active sessions is not possible, and
that
Mobile IP handover is quite complex and time consuming, owing to the need of
setting up the various negotiations and signal exchanges described above.
The present invention seeks to overcome these problems in providing
simple inter-PDSN handover methods for Simple IP and Mobile IP.
Throughout this application, it is assumed that the various nodes in the
network can send messages and signals to the other nodes in the network even
z o when there is no connection drawn between them in the drawings. This is
owing
to the fact that this enhances comprehension of the invention. A pexson
skilled in
the art will acknowledge that this does not put any limitations or constraints
on
the invention per se.
SUMMARY OF THE INVENTION
35 The present invention is directed to systems, methods and Packet Data
Service Nodes (PDSNs) for inter-PDSN handover using Point-to-Point Protocol
(PPP) in a CDMA2000 network.
In a first embodiment of the method, the CDMA2000 network comprises a
mobile node (MN) and at least two PDSNs, where the MN is connected to a first
a o of the PDSNs via a first PPP connection, and where the method comprising
the
steps of choosing the second PDSN to hand the MN over to, obtaining by the
second PDSN information about the first PPP connection, establishing a second
PPP connection from the MN to the second PDSN using the information,
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establishing a connection from the second PDSN to the first PDSN, extending
the
PPP connection from the second PDSN to the first PDSN, and informing the MN
that the handover is complete.
In a second embodiment of the method, the CDMA2000 network further
comprises an IP network that the first PDSN is connected to, the method
comprising the steps of choosing the second PDSN to hand the MN over to,
obtaining by the second PDSN information about the first PPP connection,
obtaining by the second PDSN information about the first connection from the
first PDSN to the IP network, establishing a second PPP connection from the MN
to the second PDSN using the information, establishing a connection from the
second PDSN to the IP network, and informing the MN that the handover is
complete.
A first embodiment of the system according to the invention comprises at
least two PDSNs, where the MN is connected to the first PDSN through a PPP
m connection and at least one Radio Network (RN) being an intermediate node
between the MN and the PDSN, connected to the MN through an air interface and
to the PDSN through a Radio Packet (R-P) interface, over which the PPP
connection is established, the RN choosing a second PDSN to hand over to. The
second PDSN obtains information about the first PPP connection, uses the
2 o information to establish a second PPP connection between the MN to the
second
PDSN, establishes a connection from the second PDSN to the first PDSN, over
which the second PDSN extends the PPP connection whereby the PPP connection
runs from the MN to the first PDSN, and informs the MN that the handover is
complete.
S
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A second embodiment of the system according to the invention comprises
at least two PDSNs, where the MN is connected to the first PDSN through a
first
PPP connection and where the first PDSN has a connection with an IP network,
and at least one Radio Network (RN), being an intermediate node between the
MN and the PDSN, connected to the MN through an air interface and to the
PDSN through a Radio Packet (R-P) interface, over which protocols the PPP
connection is established, the RN choosing a second PDSN to hand over to. 'The
second PDSN obtains information about the first PPP connection and the
connection to the IP network, uses the information about the first PPP
connection
Io to establish a second PPP connection between the MN and the second PDSN and
a connection between the second PDSN and the IP network, and informs the MN
that the handover is complete.
A first embodiment of the PDSN for MN handover where the MN is
handed over to the PDSN, where the PDSN obtains information about a Burst PPP
15 connection that connects the MN to a previous PDSN, uses the information to
establish a second PPP connection to the MN, establishes a connection to the
previous PDSN, extends the second PPP connection whereby the second PPP
connection runs from the MN to the previous PDSN, and informs the MN that the
handover is complete.
2 o A second embodiment of the PDSN for MN handover where the MN is
handed over to the PDSN from a second PDSN that is connected to an IP
network, where the PDSN obtains information about a first PPP connection that
connects the MN to a previous PDSN, uses the information to establish a second
PPP connection to the MN, establishes a connection to the second PDSN, obtains
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information about the connection between the second PDSN and the IP network,
uses the information to establish a second connection with the IP network, and
informs the MN that the handover is complete.
BRIEF DESCRIPTION OF THE DRAWINGS
A more complete understanding of the present invention may be had by
reference to the following Detailed Description when taken in conjunction with
the accompanying drawings wherein:
FIG. 1 depicts a simplified block diagxam of a Prior Art CDMA2000
network;
FIG. 2a depicts a block diagram illustrating the connection status prior to
inter-PDSN handover, for Mobile IP, in a CDMA2000 network according to the
Prior Art;
FIG. 2b depicts a block diagram illustrating the connection status during
inter-PDSN handover, for Mobile IP, in a CDMA2000 network according to the
1 s Prior Art;
FIG. 2c depicts a block diagxam illustrating the connection status aftex
inter-PDSN handover, for Mobile IP, in a CDMA2000 network according to the
Prior Art;
FIG. 3a shows a block diagxam illustrating inter-PDSN handover for
2 o Mobile IP according to a first preferred embodiment of the invention;
FAG. 3b shows a block diagram illustrating inter-PDSN handover for
Mobile IP according to a first preferred embodiment of the invention;
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FIG. 4a shows a block diagram illustrating inter-PDSN handover for
Simple IP according to the first preferred embodiment of the invention;
FIG. 4b shows a block diagram illustrating inter-PDSN handover for
Simple IP according to the first preferred embodiment of the invention;
FIG. 5a shows a block diagram illustrating inter-PDSN handover for
Mobile IP according to a second preferred embodiment of the invention;
FIG. 5b shows a block diagram illustrating inter-PDSN handover for
Mobile IP according to a second preferred embodiment of the invention;
FIG. 5c shows a block diagram illustrating inter-PDSN handover for
1 o Mobile IP according to a second preferred embodiment of the invention;
FIG. 6a shows a block diagram illustrating inter-PDSN handover for
Simple IP according to the second preferred embodiment of the invention;
FIG. 6b shows a block diagram illustrating inter-PDSN handover for
Simple IP according to the second preferred embodiment of the invention; and
FIG. 6c shows a block diagram illustrating inter-PDSN handover for
Simple IP according to the second preferred embodiment of the invention;
s
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DETAILED DESCRIPTION OF EMBODIMENTS
Reference is now made to Figure 3, where two block diagrams 3a-3b
illustrate logical connections during handover according to a first preferred
embodiment of the invention. Figure 3a shows, using the reference numbers from
s Figure l, the pre-handover situation for a Mobile Node (MN) 11, a first and
a
second Radio Network (RN) 13-14, a first and a second Packet Data Serving
Node (PDSN) 16-17, and a Home Agent (HA) 20. The MN 11 and the PDSN 16
are connected via a symbolically shown PPP connection 24 (over the air
interface
15 and the Radio Packet, R-P, interface 18) while the PDSN 16 and the HA 20
are
s o connected via a Mobile IP (MIP) connection 25.
During the handover procedure, wherein the MN is at least handed over
from the first PDSN 16 to the second PDSN 17, the second RN 14 is provided
with the PDSN iP Address, i.e. the IP address associated with the MN 11, by
the
MN 11 itself in a message 41, or by a node in the system, e.g. the first RN 13
or
15 an MSC (not shown). To keep the PPP connection 24 during the handover, the
MN 11 acts internally to maintain the Link Control Protocol (LCP) link (not
shown) over which the PPP connection 24 runs.
The second RN 14 then selects which PDSN 16-17 to connect to (as in the
example PDSN 17), in an accepted fashion according to the Prior Art. The
second
2 o RN I4 also sends, included in the standard connection set-up messages 42,
the
PDSN IP Address it received earlier to the second PDSN 17. This enables the
reduction of delay in the overall handover process as this makes it possible
to
begin setting up in parallel a new R-P connection 18 and an Layer 2 Tunnelling
Protocol (L2TP) tunnel 28 from the second PDSN 17 to the first PDSN 16. The
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PPP connection 24 between the MN 11 and the first PDSN 16 is terminated as
well. Figuxe 3b shows the logical connection status at this point. The first
PDSN
16 is now the anchor point for enabling mobility for the MN I 1.
The second PDSN 17 sends a new L2TP message 43, Fast L2TP Set-Up
Request, to extend the PPP connection from the second PDSN 17 to the first
PDSN 16. This message 43 contains information for both setting up the L2TP
tunnel 28 and for requesting information about the PPP and MIP connections for
the MN 11. In response to the message above, the first PDSN 16 returns a Fast
L2TP Set-Up Acknowledgement 44 containing the requested information. The
1o second PDSN 17 then sends a message 45 to the MN 11, indicating that the
original PPP connection 24 (although, unbeknownst to the MN 11, it is now
really
called 24') is active again, after which the handover is performed.
Any communication data is now sent from the MN 11 to the second PDSN
17, that tunnels the data via L2TP or any other tunnelling scheme to the first
1 s PDSN I6, which in turn tunnels the data to the HA 20 via the MIP
connection 25.
It should be understood that any tunnelling scheme, such as for example
MIP tunnelling, could be used between the two PDSNs 16-17, in which case the
tunnel and the corresponding messages are changed accordingly. It is also to
be
understood that the signalling is not limited to the hereinbefore-mentioned
a o messages, but that any number or type of messages could be used to
transfer the
necessary information.
Reference is now made to Figure 4, where two block diagrams 4a-4b
illustrate logical connections during handover according to a first preferred
embodiment of the invention for the case of Simple IP. Figure 4a shows, using
the
io
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reference numbers for similar elements from Figure 1, the pre-handover
situation
for a Mobile Node (MN) 11, a first and a second Radio Network (RN) 13-14, and
a first and a second Packet Data Serving Node (PDSN) 16-17. There is also an
IP
network 22. The MN 11 and the PDSN 16 are connected via a symbolically
s shown PPP connection 24 (over the air interface 15 and the Radio Packet, R-
P,
interface 18) while the PDSN 16 and the iP network 22 are connected via an IP
connection 25.
During the handover, the second RN 14 is provided with the PDSN IP
Address, i.e. the IP address associated with the MN 11, by the MN 11 itself in
to message 41, or by a node in the system, e.g. the first RN 13 or an MSC (not
shown). To keep the PPP connection 24 during the handover, the MN 11 acts
internally to maintain the Link Control Protocol (LCP) link (not shown) over
which the PPP connection 24 runs.
The second RN 14 then selects which PDSN 16-17 to connect to (as in the
example PDSN 17}, in an accepted fashion according to the Prior Art. The
second
RN 14 also sends, included in the standard connection set-up messages 42, the
PDSN IP Address it received earlier to the second PDSN 17. This enables the
reduction of delay in the overall handover process as this makes it possible
to
begin setting up in parallel a new R-P connection 18 and an Layer 2 Tunnelling
a o Protocol (L2TP) tunnel 28 from the second PDSN 17 to the first PDSN 16.
The
PPP connection 24 between the MN 11 and the first PDSN 16 is terminated as
well. Figure 4b shows the logical connection status at this point. The first
PDSN
16 is now the anchor point for enabling mobility for the MN 11.
The second PDSN 17 sends a new L2TP message 43, Fast L2TP Set-Up
11
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Request, to extend the PPP connection from the second PDSN I7 to the first
PDSN 16. This message contains information for both setting up the L2TP tunnel
28 and for requesting information about the PPP connection 24 for the MN 11.
In
response to the message above, the first PDSN 16 returns a Fast L2TP Set-Up
Acknowledgement 44 containing the requested information. The second PDSN
17 then sends a message 45 to the MN I1, indicating that the original PPP
connection 24 (although, unbeknownst to the MN 11, it is now really called
24')
is active, after which the handover is done.
Any communication data is now sent from the MN 1 I to the second PDSN
17, that tunnels the data via L2TP or any other tunnelling scheme to the first
PDSN 16, which in turn tunnels the data to the IP network 22 via the IP
connection 25.
It should be understood that any tunnelling scheme, for example MiP
tunnelling, could be used between the two PDSNs 16-17, in which case the
tunnel
z5 and the corresponding messages are changed accordingly. It is also to be
understood that the signalling is not limited to the above-mentioned messages;
but
that any number or type of messages could be used to transfer the necessary
information.
Figure 5 illustrates in Figures 5a-5c a second preferred embodiment of
z o handover for Mobile IP. Figure 5a shows the pre-handover situation for a
Mobile
Node (MN) I1, a first and a second Radio Network (RN) 13-I4, a first and a
second Packet Data Serving Node (PDSN) 16-17, and a Home Agent (HA) 20.
The MN 1 I and the PDSN 16 are connected via a PPP connection 24 (over the air
interface IS and the R-P interface I8) while the PDSN 1.6 and the HA are
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DOCKF'~' X10. P13903CA
connected via a MIP connection 25.
As previously, during the handover, the second RN 14 is provided with the
PDSN IP Address by the MN 11 in message 41, or by a node in the system, e.g.
the first RN 13 ox an MSC (not shown). To keep the PPP connection 24 during
s the handover, the MN 11 acts internally to maintain the Link Control
Protocol
(LCP) link (not shown) over which the PPP connection 24 runs.
The second RN i4 then selects which PDSN 16-17 to connect to {as in the
example, PDSN 17), in an accepted fashion. The second RN 14 also sends,
included in the standard set-up messages 42, the PDSN IP Address it received
1o earlier to the second PDSN 17. This enables the reduction of delay in the
overall
handover process as it makes it possible to begin in parallel setting up a new
R-P
connection (not shown) and, for the second PDSN 17, to obtain, from the first
PDSN 16 through a signalling link 29 shown in Figure Sb, information about the
PPP and MIP connections 24 and 25, respectively, the information being sent in
15 at least one message 46. The information could for example be exchanged via
L2TP tunnel control messages (as above) or any other suitable signalling
messages. Figure Sb shows the logical connection status at this point.
There are two different possibilities as to the downloading of information
from the first PDSN 16 to the second PDSN 17 described hereinbefore. One
a o possibility is to download relevant information about the connections as
quickly
as possible after the information is requested by the second PDSN 17 in order
to
enable the handover, while all other information in the first PDSN 16
pertaining
to the MN 11 is downloaded later. Using this possibility, the object is to
make the
first PDSN 16 superfluous after which the second PDSN 17 is the sole PDSN 16-
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17 dealing the MN 11, and the connection 29 between the two PDSNs I6-17 is
terminated. A second possibility is to download the connection information as
quickly as possible after the information is requested by the second PDSN 17,
while other information related to the MN 11, such as for example information
s about services the MN 11 accesses, remains with the frst PDSN 16. In this
case,
the connection 29 between the PDSNs 16-17 is kept.
The second PDSN 17 then either establishes a new MIP connection with
the HA 20 or copies the MIP connection 25 (the new connection denoted by 25'
in Figure Sc) between the first PDSN 16 and the HA 20, after which the first
1 o PDSN 1 b terminates its own MIP connection 25 with the HA 20. The second
PDSN 17 then sends a message 45 to the MN 11, indicating that the original PPP
connection 24 is active, after which the handover is done. Figure 5c shows the
network at this point.
Communication data is then sent between the MN 11 and the HA 20 via the
second PDSN 17 that copied at least the PPP connection 2~ via the first PDSN
Ib,
with which it keeps contact in case it has not downloaded all the relevant
informarion about the MN 11, as described above. As the second PDSN 17
simply copied at least the PPP connection 24, there was no need to fully
re-establish at least the PPP connection 24, which gives an efficient handover
2 o procedure.
Figure 6 illustrates in Figures 6a-6c a second preferred embodiment of
handover for Simple IP. Figure 6a shows the pre-handover situation for a
Mobile
Node (MN) 11, a first and a second Radio Network (RN) 13-14, a first and a
second Packet Data Serving Node (PDSN) 16-17, and an IP network 22. The MN
14
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11 and the PDSN 16 are connected via a PPP connection 24 (over the air
interface
15 and the R-P interface 18) while the PDSN 16 is connected to the IP network
22
via an IP connection 25.
As previously, during the handover, the second RN 14 is provided with the
PDSN IP Address by the MN 11 in message 41, or by a node in the system, e.g.
the first RN 13 or an MSC (not shown). To keep the PPP connection 24 during
the handover, the MN 11 acts internally to maintain the Link Control Protocol
(LCP) link (not shown) over which the PPP connection 24 runs.
The second RN 14 then selects which PDSN 16-17 to connect to (as in the
a. o example, PDSN 17), in an accepted fashion. The second RN 14 also sends,
included in the standard set-up messages 42, the PDSN IP Address it received
earlier to the second PDSN 17. This enables the reduction of delay in the
overall
handover process as it makes it possible to begin in parallel setting up a new
R-P
connection (not shown) and, for the second PDSN 17, to obtain, from the first
15 PDSN 16 through a signalling link 29 shown in Figure 6b, information about
the
PPP connection 24, the information being sent in at least one message 46. The
information could fox example be exchanged via L2TP tunnel control messages
(as hereinbefore) or any other suitable signalling messages. Figure 6b shows
the
logical connection status at this point.
2 o There are two different possibilities as to the downloading of information
from the first PDSN 16 to the second PDSN 17 described hereinbefore. One
possibility is to download relevant information about the connections as
quickly
as possible after the information is requested by the second PDSN 17 in order
to
enable the handover, while all other information in the first PDSN 16
pertaining
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to the MN 11 is downloaded later. Using this possibility, the object is to
make the
first PDSN 16 superfluous after which the second PDSN 17 is the sole PDSN 16-
17 dealing the MN 11, and the connection 29 between the two PDSNs 16-17 is
terminated. A second possibility is to download the connection information as
quickly as possible after the information is requested by the second PDSN I7,
while other information related to the MN 11, such as for example information
about services the MN 11 accesses, remains with the first PDSN 16. In this
case,
the connection 29 between the PDSNs 16-17 is kept.
The second PDSN 17 then either preferably establishes a new IP
1 o connection with the 1P network 22 or copies the l.P connection 25 (the new
connection denoted by 25' in Figure 6c) between the first PDSN 16 and the IP
network 22, after which the first PDSN 16 terminates its own IP connection 25
with the IP network 22. The second PDSN 17 then sends a message 45 to the MN
11, indicating that the original PPP connection 24 is active, after which the
handover is done. Figure 6c shows the network at this point.
Communication data is then sent between the MN 1 l and the IP network
22 via the second PDSN I7 that copied at least the PPP connection 24 via the
first
PDSN 16, with which it keeps contact in case it has not downloaded all the
relevant information about the MN 11, as described above. As the second PDSN
a o I7 simply copied at least the PPP connection 24, there was no need to
fully
re-establish at least the PPP connection 24, which gives an efficient handover
procedure.
There are two different options of handling the case where the MN 11
hands over to yet another, third, PDSN (not shown). The first option is simply
to
16
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apply the hereinbefore mentioned handover method one more time, in which case
there will be a series of tunnels or connections 28, 29 leading from the new
PDSN
through the previous to the first.
The second, preferable option is to inform the third PDSN {not shown)
s about the identity of the first PDSN 16. In the first embodiment, the third
PDSN
contacts the second PDSN 17 as in the description in order to receive
information
and to copy the PPP connection 24. The third PDSN also receives the identity
of
the first PDSN 16, for example from the MN 11 or the second PDSN I7. Then,
the third PDSN sets up a link to the first PDSN 16 and takes over the PPP
1o connection 24 to the MN 11, while the second PDSN 17 terminates its
connections 24, 28 or 29.
In the second embodiment, the procedure depends on whether the first
PDSN 16 still retains information about the MN 11 or not. In case the first
PDSN
16 does not retain any information about the MN 11, then the further handover
a5 procedure is straightforward following the description above. If, however,
the first
PDSN 16 still retains some responsibility for the MN 11, the procedure is as
described above, with some additions. The third PDSN (not shown) receives the
identity of the first PDSN 16, for example from the MN 11 or the second PDSN
17. Then it sets up a connection 28, 29 with the first PDSN 16, after which
the
a o second PDSN 17 can terminate its connection 28, 29 with the first PDSN 16.
It is also to be understood that there is no absolute necessity to change both
RN 13-14 and PDSN 16-17 during the handover. It is perfectly conceivable that
a
RN 13-14 might want to change PDSN 16-I7 for the MN 11, but the handover
m
CA 02359040 2001-09-27 ; 51 4 3457929
PATENT APPLICATION
DOCKET NO. P13903CA
would follow the same steps as detailed above, except that there is no need
for the
MN 11 to change RN 1.3-14.
As can be seen from the description above, thexe are provided efficient
handover methods for Simple IP and Mobile IP, that in the case of Simple IP
enables handover, and in the case of Mobile IP makes the handover more
efficient.
Although several preferred embodiments of the method and system of the
present invention have been illustrated in the accompanying Drawings and
described in the foregoing Detailed Description, it will be understood that
the
invention is not limited to the embodiments disclosed, but is capable of
numerous
rearrangements, modifications and substitutions without departing from the
spirit
of the invention as set forth and defined by the following claims.
I8
