Multiplex communications – Communication over free space – Having a plurality of contiguous regions served by...
Reexamination Certificate
2000-11-17
2004-09-28
Nguyen, Chau (Department: 2661)
Multiplex communications
Communication over free space
Having a plurality of contiguous regions served by...
C370S401000, C455S433000
Reexamination Certificate
active
06798763
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to system and method for mobile communication, and more particularly, to a mobile communication system and a mobile communication method that avoid delay in data transmission between a mobile node and a communication terminal.
2. Description of the Background Art
A standard Internet Protocol (IP) currently utilized is called Internet Protocol version 4 (IPv4). A next generation protocol for replacement of IPv4, Internet Protocol version 6 (IPv6), has now been under examination and inspection.
The mobile communication in accordance with IPv4 and IPv6, or, so-called Mobile IP, is controlled in the following procedures.
FIGS. 13 and 14
show conventional procedures for establishing communication between a partner appliance and a mobile node under IPv4. In
FIGS. 13 and 14
, the communication procedures are shown as {circle around (
1
)}-{circle around (
4
)}. {circle around (
1
)}-{circle around (
4
)} in
FIG. 13
correspond to {circle around (
1
)}-{circle around (
4
)} in FIG.
14
.
FIG. 14
shows a system to which the Mobile IP corresponding to IPv4 is applied. The system in
FIG. 14
includes: a communication network NE, such as the Internet, that is a main network to which the IP is applied; IP sub-networks
10
and
20
, such as local area network, to which the IP is applied; and a home agent HA, a foreign agent FA and a partner appliance PA connected to one another through communication network NE; and a mobile node MN.
Partner appliance PA and mobile node MN each are mobile information equipment such as IP telephone, video telephone or the like. Herein, for simplification of explanation, partner appliance PA is assumed to be information equipment that does not move. Home agent HA and foreign agent FA each are equipment such as a gateway, which receives data via communication network NE, understands the intention according to the situations, and performs processing based on an autonomous determination. Home agent HA and foreign agent FA correspond to stations that relay the communication between mobile node MN and partner appliance PA. Communication network NE connects partner appliance PA, home agent HA and foreign agent FA to one another. IP sub-networks
10
and
20
connect home agent HA and mobile node MN, and foreign agent FA and mobile node MN, respectively. Home agent HA is used when mobile node MN is in an area communicable via IP sub-network
10
; whereas foreign agent FA is used when mobile node MN has moved out of the area and is now in another area communicable with foreign agent FA via IP sub-network
20
. From the standpoint of IP sub-network
10
corresponding to home agent HA, IP sub-network
20
corresponds to a foreign link, and therefore, it is also called “a foreign link”. Herein, IP sub-networks
10
and
20
are assumed to be wireless communication networks.
Assume that mobile node MN that was being connected to IP sub-network
10
corresponding to home agent HA moves in a direction indicated by a dashed arrow AR and comes to be connected to IP sub-network
20
to which foreign agent FA belongs. Mobile node MN has a home address HAD when it is being connected via IP sub-network
10
to home agent HA. Home address HAD is a global address that is an IP address of mobile node MN when it is in the area communicable via IP sub-network
10
. When mobile node MN moves outside the area and comes to be connected via IP sub-network
20
to foreign agent FA, then mobile node MN acquires a care of address CAAD being also a global address. It then notifies home agent HA of the care of address CAAD via foreign agent FA, and receives, from foreign agent FA, a current address in the area where mobile node MN has moved in (hereinafter, referred to as a “moved address”) MAD as its temporary IP address. Moved address MAD is an address for uniquely identifying a corresponding mobile node MN. Care of address CAAD is an IP address of foreign agent FA belonging to an area where mobile node MN has moved in, and indicates a current connect point for the relevant mobile node MN. Accordingly, a message for mobile node MN is transferred to care of address CADD by home agent HA, and foreign agent FA receives the message and sends it to the mobile node MN. The detailed communication at this time will be described with reference to FIG.
13
.
The message for mobile node MN from partner appliance PA is sent as follows. Specifically, when home agent HA receives, from partner appliance PA, “call setup request” for a message in accordance with ITU-T Q.931, etc. (recommendation by International Telecommunication Union; hereinafter, simply referred to as Q.931, etc.) ({circle around (
1
)}), it sends the call setup request as capsulated data to foreign agent FA by tunneling ({circle around (
2
)}). Foreign agent FA performs decapsulation of the received call setup request, and sends the resultant to mobile node MN ({circle around (
3
)}). In response to receipt of the call setup request, mobile node MN sends “call accepted”, “call” and “response” to partner appliance PA, not via home agent HA, but via foreign agent FA belonging to the area where the mobile node MN has moved in ({circle around (
4
)}). Hereinafter, the case where, in a system corresponding to IPv4, mobile node MN (or partner appliance PA) sends information (data, signals) to partner appliance PA (or mobile node MN) not via home agent HA but via foreign agent FA is expressed as “to send directly” or “direct sending”.
Thus, communication is established between partner appliance PA and mobile node MN. Thereafter, data from mobile node MN to partner appliance PA is sent directly ({circle around (
4
)}); whereas data from partner appliance PA to mobile node MN is sent via home agent HA and foreign agent FA ({circle around (
1
)}, {circle around (
2
)} and ({circle around (
3
)}).
FIGS. 15 and 16
show conventional procedures for establishing communication between partner appliance PA and mobile node MN in the case of IPv6. In
FIGS. 15 and 16
, the communication procedures are shown as {circle around (
1
)}-{circle around (
4
)}. {circle around (
1
)}-{circle around (
4
)} shown in
FIG. 15
correspond to {circle around (
1
)}-{circle around (
4
)} shown in FIG.
16
.
FIG. 16
shows a system to which the Mobile IP corresponding to IPv6 is applied. The configuration of the system in
FIG. 16
is identical to that shown in
FIG. 14
, and therefore, detailed description thereof is not repeated. Referring to
FIG. 16
, mobile node MN has home address HAD while it is connected via IP sub-network
10
to home agent HA. When the mobile node MN that was connected to home agent HA via IP sub-network
10
moves in a direction indicated by the dashed arrow AR and comes to be connected to a foreign link (not shown), mobile node MN acquires a moved address MAD, i.e., a temporary IP address as a global address, from a server (not shown) on communication network NE, although the way of acquiring the moved address MAD is not limited thereto. Mobile node MN then notifies home agent HA of that moved address MAD as care of address CAAD indicating its current location. Thereafter, the message from partner appliance PA for mobile node MN is sent as follows.
Referring to
FIG. 15
, partner appliance PA sends “call setup request” to home agent HA for a message according to Q.931, etc. ({circle around (
1
)}). Home agent HA receives the call setup request, and sends it to mobile node MN by tunneling ({circle around (
2
)}). Mobile node MN, in response to receipt of the call setup request, directly sends “call accepted”, “call” and “response” to partner appliance PA ({circle around (
3
)}). Thus, connection between partner appliance PA and mobile node MN is established. Thereafter, data from partner appliance PA is sent to mobile node MN via home agent HA by tunneling ({circle around (
1
)}, {circle around (
2
)}); whereas data from mobile node MN is sent directly to partner appliance PA. Here, at an appropriate timing, mobile node MN notifies partner appliance PA o
Amano Miki
Kimura Shinya
Conlin David G.
Edwards & Angell LLP
Nguyen Chau
Sharp Kabushiki Kaisha
Wahba Andrew
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