U.S. patent application number 09/790383 was filed with the patent office on 2001-09-27 for distributed infrastructure for wireless data communications.
Invention is credited to Bender, Paul E., Grob, Matthew S., Karmi, Gadi, Kimball, Robert H..
Application Number | 20010024437 09/790383 |
Document ID | / |
Family ID | 22566487 |
Filed Date | 2001-09-27 |
United States Patent
Application |
20010024437 |
Kind Code |
A1 |
Bender, Paul E. ; et
al. |
September 27, 2001 |
Distributed infrastructure for wireless data communications
Abstract
A mobile user terminal 402 accesses a packet data network 450
through one or more of several network access points 404-412. One
or more control points 432-440 determines which network access
point or points the user terminal is to access. Control may be
retained in the current control point, or transferred to another
control point, whenever it is convenient. There are preferably
several routers, each having an associated home agent 418-420 which
determines which foreign agents need to be accessed on behalf of
each user terminal. There are several foreign agents 422-430, which
forward packets received from a user terminal's home agent to the
control point currently controlling communications with the user
terminal.
Inventors: |
Bender, Paul E.; (San Diego,
CA) ; Grob, Matthew S.; (La Jolla, CA) ;
Kimball, Robert H.; (San Diego, CA) ; Karmi,
Gadi; (San Diego, CA) |
Correspondence
Address: |
QUALCOMM Incorporated
5775 Morehouse Drive
San Diego
CA
92121-1714
US
|
Family ID: |
22566487 |
Appl. No.: |
09/790383 |
Filed: |
February 21, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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09790383 |
Feb 21, 2001 |
|
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09158047 |
Sep 22, 1998 |
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6215779 |
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Current U.S.
Class: |
370/352 ;
370/329 |
Current CPC
Class: |
H04W 88/08 20130101;
H04W 80/04 20130101; H04W 36/08 20130101; H04W 88/12 20130101 |
Class at
Publication: |
370/352 ;
370/329 |
International
Class: |
H04L 012/66 |
Claims
1. An article of manufacture, comprising in combination: a) a user
terminal configured to transmit and receive wireless data packets;
b) a plurality of network access points, each being configured to
transmit wireless data packets to, and to receive them from, the
user terminal; c) a router connected to transmit data packets to,
and to receive them from, the network access points; and d) a
plurality of control points, each control point being: 1)
associated with a network access point; and 2) configured to: (A)
select a network access point to communicate with the user
terminal; (B) manage a wireless link between the user terminal and
the selected network access point; and (C) retain control, or
transfer control to another control point, according to a
pre-established determination.
2. The article of claim 1, wherein the selected network access
point is different from the control point's associated network
access point.
3. The article of claim 1, wherein each control point is configured
to select a plurality of network access points to concurrently
communicate with the user terminal.
4. The article of claim 3, wherein all of the selected network
access points are different from the control point's associated
network access point.
5. The article of claim 1, wherein each control point is further
configured to cache data link protocol information for the user
terminal during periods when the user terminal is not assigned a
wireless forward link, or is not assigned a wireless reverse link,
or is assigned neither a wireless forward link nor a wireless
reverse link.
6. The article of claim 5, wherein the caching control point is
associated with the network access point first used by the user
terminal.
7. The article of claim 5, wherein the control point is associated
with the network access point last used by the user terminal.
8. An article of manufacture, comprising in combination: a) a user
terminal configured to transmit and receive wireless data packets;
b) a plurality of network access points, each configured to
transmit wireless data packets to, and to receive them from, the
user terminal; c) one or more routers connected to transmit data
packets to, and to receive them from, the network access points,
each network access point being connected to only one router; d)
one or more home agents, each home agent being: 1) associated with
a router; and 2) configured to select one or more of the
below-recited foreign agents to forward packets to the user
terminal e) a plurality of foreign agents, each foreign agent: 1)
also being associated with a network access point; 2) being
configured to forward data packets from a user terminal's home
agent to the control point that is currently controlling
communications with the user terminal; and 3) supporting transfer
of communications control for a particular user terminal between
different control points; f) a plurality of control points, each
control point being: 1) associated with a network access point; 2)
configured to: (A) select one or more network access points to
communicate with the user terminal; (B) manage a wireless link
between the user terminal and the selected network access point;
and (C) retain control, or transfer control to another control
point, according to a pre-established determination.
9. The article of claim 8, wherein the selected network access
point is different from the control point's associated network
access point.
10. The article of claim 8, wherein each control point is
configured to select a plurality of network access points to
concurrently communicate with the user terminal.
11. The article of claim 10, wherein all of the selected network
access points are different from the control point's associated
network access point.
12. The article of claim 8, wherein each control point is further
configured to cache data link protocol information for the user
terminal during periods when the user terminal is not assigned a
traffic channel.
13. The article of claim 12, wherein the control points are
configured to cache data link protocol information in the control
point associated with the network access point first used by the
user terminal.
14. The article of claim 12, wherein the control points are
configured to cache data link protocol information in the control
point associated with the network access point last used by the
user terminal.
Description
CROSS REFERENCE
[0001] This application is a continuation application of co-pending
Application Ser. No. 09/158,047, filed Sep. 22, 1998, entitled
"Distributed Infrastructure For Wireless Data Communications."
TECHNICAL FIELD
[0002] This invention pertains to wireless communications systems
and, in particular, to wireless packet data networks.
BACKGROUND ART
[0003] FIG. 1
[0004] FIG. 1 shows a conventional single-router wireless packet
data network 100. A packet router 102 receives data packets from
the remainder of a network 104 and routes them to one or more
network access points 106-110. The network access points 106-110
transmit the packets forward to a user terminal 112 over forward
wireless links 114-116. The user terminal 112 transmits packets
back to the network access points 106-110 over reverse wireless
links 118-120. The user terminal 112 may be a cellular telephone
carried by a person, a portable computer, a mobile telephone in an
automobile, or any other mobile device which must continue to
provide connectivity even while it moves.
[0005] A control point 122 is connected to the packet router 102.
It manages the wireless links 114-120. Management includes many
functions. For example, as the user terminal 112 moves around the
path loss between it and the network access points 106-110 changes.
In the situation shown in FIG. 1, the control point 122 must cause
the user terminal 112 to transmit with the minimum amount of power
required to be received by at least one of network access points
106-108. Mobile station transmit power is minimized since it causes
interference to transmissions from other mobile stations. When the
user terminal moves from the area served by network access point
106 to the area served by network access point 108, there will be a
handoff of the user terminal 112 from network access point 106 to
network access point 108. The control point 122 must manage the
handoff. Other management functions are known to those with skill
in the art.
[0006] FIG. 2
[0007] FIG. 2 shows a conventional multiple-router wireless packet
data network 200 supporting a mobility protocol such as Mobile IP
as described in the Internet Engineering Task Force RFC 2002. A
second packet router 202 is connected to the first packet router
102, to the rest of the network 104, or (as shown) to both. Second
packet router 202 is connected to network access points 204-206. In
FIG. 2, the user terminal 112 is moving from the area served by
network access point 110 (where it is served by forward link 208)
to the area served by network access point 204 (where it is served
by forward link 210). Control point 122 manages the wireless links
during this handoff (including the management of reverse links
212-214) in much the same way as during the handoff shown in FIG.
1. If desired, control can be passed from first control point 122
to second control point 222. These control points are connected to
first and second packet routers 102 and 202, respectively.
[0008] FIG. 2 also shows a home agent 224 and a foreign agent 226.
Home agent 224 is connected to first packet router 102, and foreign
agent 226 is connected to second packet router 202.
[0009] User terminal 112 has a network address for which packet
router 102 advertises reachability. A packet intended for user
terminal 112 is therefore sent to first packet router 102. When
user terminal 112 is in the coverage area of network access points
associated with packet router 102 (106-110), packet router 102 will
forward the packet to control point 122 which will send the packet
for transmission to the network access points that currently
provide a forward wireless link to the user terminal 112.
[0010] User terminal 112 may leave the area served by first packet
router 102 and may enter the area served by second packet router
202. The net 104 will send packets destined to user terminal 112 to
packet router 102 which will then forward them to home agent 224
which maintains track of user terminal 112's current location in
the form of a "care-of" address. The home agent will then
encapsulate these packets in packets destined to the care-of
address of the user terminal (e.g., foreign agent 226) and send
these packets through packet routers 102 and 202. Upon receiving
these packets, foreign agent 226 will de-capsulate the packets and
forward the packets destined for transmission to user terminal 112
to control point 222. Control point 222 will then forward the
packets for transmission to the network access points that
currently provide a forward wireless link to the user terminal
112.
[0011] In this method, control of the network access points for a
data connection has moved from control point 122 to control point
222. In another conventional method, control does not move between
the two control points, in which case packet router 102 continues
to forward packets for transmission to user terminal 112 to control
point 122 which then sends the packets directly to whatever network
access points provide a forward wireless link to user terminal 112,
regardless of the system in which these network access points are
located. E.g., control point 122 may forward packets for
transmission to network access points 106-110 as well as
204-206.
[0012] This architecture suffers from several fundamental problems:
the control points for each part of the network are single points
of failure which must be made highly reliable, increasing their
cost. Furthermore, since they are unique for each network, the
architecture does not scale well as the number of network access
points increase, increasing with it the population of mobile
terminals that can be served and consequently, the load presented
to the control points. Last, emerging high speed wireless protocols
require low-latency control by the control point which is not
possible due to the transmission and queuing delays between the
control points and the network access points.
DISCLOSURE OF INVENTION
[0013] Applicants provide a solution to the shortcomings of the
previously described architecture by distributing the functionality
of the control points and allowing the co-location of a control
point with every network access point. The architecture proposed by
the applicants is further optimized by co-locating foreign agents
with the network access points and control points.
BRIEF DESCRIPTION OF DRAWINGS
[0014] FIG. 1 shows a conventional single-router wireless packet
data network.
[0015] FIG. 2 shows a conventional multiple-router wireless packet
data network.
[0016] FIG. 3 shows a single-router wireless packet data network,
according to the present invention.
[0017] FIG. 4 shows a multiple-router wireless packet data network,
according to the present invention.
MODES FOR CARRYING OUT THE INVENTION
[0018] FIG. 3
[0019] FIG. 3 shows a single-router wireless packet data network
300, according to the present invention.
[0020] A user terminal 302 is configured to transmit and receive
wireless data packets. There is plurality of network access points
304-308, each being configured to transmit wireless data packets
to, and to receive them from, the user terminal 302. A router 310
is capable of transmitting data packets to, and receiving them
from, the network access points 304-308. FIG. 3 shows the situation
in which a user terminal is leaving the area served by first
network access point 304 and is entering the area served by second
network access point 306.
[0021] There is a plurality of control points 312-316. As in the
prior art, each control point is configured to manage a wireless
link 318-324 between the user terminal 302 and the selected network
access point 304-308. However, there are plural control points
312-316 instead of a single control point 122. In this invention, a
user terminal is served by the control point that is co-located
with the first network access point with which the user terminal
has established communications for a particular data exchange. In
the example of FIG. 3, user terminal 302 is currently connected to
both network access points 304 and 306. If the first network access
point to serve the user terminal was network access point 304, the
control point will be control point 312. Otherwise, the control
point will be control point 314. Using this convention multiple
user terminals accessing the network will be controlled by a
plurality of control points thus sharing the load between the
control points. Furthermore, a failure of a control point would
only affect the user terminals served by it, rather than the entire
population of user terminals.
[0022] Each control point 312-316 is configured to select a network
access point 304-308 to communicate with the user terminal 302. In
FIG. 3, first control point 312 has selected first network access
point 304 as the network access point to communicate with the user
terminal 302. However, as user terminal 302 leaves the area served
by first network access point 304 and enters the area served by
second network access point 306, first control point 312 selects
both network access points 304, 306 to communicate with user
terminal 302. First control point 312 then selects only second
network access point 306 to communicate with user terminal 302,
thus effecting a soft handoff. First control point 312 may retain
control even after the process has ended, or it may transfer
control to second control point 314. Third control point 316 was
not used during the process just described, but remains available
in case user terminal 302 moves into the area served by third
network access point 308. The operator may establish any convenient
method for determining when to retain control in the current
control point and when to transfer control to another control
point.
[0023] Soft handoff is not the only possible event which triggers a
decision on whether to retain control in the current control point
or to transfer control to another control point. Load sharing,
failure of a control point, and similar considerations may be used
by the operator to determine when to trigger a decision.
[0024] Using a mobility protocol such as Internet Engineering Task
Force RFC 2002, packets destined to user terminal 302 are routed
from router 310 to the control point that currently control
communications with user terminal 302.
[0025] The actual network access point used to communicate with the
user terminal may be different from the control point's associated
network access point, or may be the same.
[0026] If desired, each control point may be configured to select a
plurality of network access points to concurrently communicate with
the user terminal. In this case, all of the selected network access
points may be different from the control point's associated network
access point, or one of the selected network access points may be
the same as to control point's associated network access point.
[0027] Each control point may be configured, if desired, to cache
data link protocol information for the user terminal during periods
when the user terminal is not assigned a traffic channel. If this
is done, the caching control point may be associated with the
network access point first used by the user terminal, with the
network access point last used by the user terminal, or any other
point.
[0028] FIG. 4
[0029] FIG. 4 shows a multiple-router wireless packet data network
400, according to the present invention.
[0030] A user terminal 402 is configured to transmit and receive
wireless data packets. There is a plurality of network access
points 404-412, each configured to transmit wireless data packets
to, and to receive them from, the user terminal 402. There are one
or more routers 414-416 capable of transmitting data packets to,
and receiving them from, the network access points 404-412. Each
network access point 404-412 is connected to only one router
414-416. There are one or more home agents 418-420. Each home agent
418-420 is associated with a router 414-416. The home agents
encapsulate packets destined to user terminals registered with them
in packets destined to the current care-of address of the user
terminal. This address is the address of the foreign agent
co-located with the control point that is controlling
communications with the user terminal. The foreign agent may be
connected to the same router as the home agent or to a different
router. The use of home agents and foreign agents is well known to
those skilled in the art and is described in such mobility
protocols as Internet Engineering Task Force RFC 2002.
[0031] There is a plurality of foreign agents 422-430. Each foreign
agent 422430 is also associated with a network access point 404-412
and a control point 432-440. Each foreign agent is configured to
receive packets for user terminals currently being served by the
control point co-located with it. The foreign agent receives
packets destined to it. If these packets contain packets destined
to such user terminals, it de-capsulates these packets and forwards
them to the control point.
[0032] There is a plurality of control points 432-440. As in FIG.
3, each control point 432-440 is associated with a network access
point 404-412. Each control point 432-440 is configured to select
one or more network access points 404-412 to communicate with the
user terminal 402. Each control point 432-440 is further configured
to manage a wireless link 442-448 between the user terminal 402 and
the selected network access point or points 408-410. The user
terminal 402 thus stays in communication with the rest of the
network 450 even when moving.
[0033] The selected network access point may be different from, or
the same as, the control point's associated network access
point.
[0034] Each control point may be configured to select a plurality
of network access points to concurrently communicate with the user
terminal. If so, all of the selected network access points may be
different from the control point's associated network access point,
or one of them may be the same.
[0035] Following a handoff, control may either remain in the
original control point or may be transferred to the control point
associated with the new network access point. As in the apparatus
of FIG. 3, the operator may establish any convenient method for
determining when to retain control in the current control point and
when to transfer control to another control point. Also as in the
apparatus of FIG. 3, soft handoff is not the only possible event
which triggers a decision on whether to retain control in the
current control point or to transfer control to another control
point. Load sharing, failure of a control point, and similar
considerations may be used by the operator to determine when to
trigger a decision.
[0036] In any event, each control point may be further configured
to cache data link protocol information for the user terminal
during periods when the user terminal is not assigned a traffic
channel. This may be done in the control point associated with the
network access point first used by the user terminal, last used by
the user terminal, or any other control point.
INDUSTRIAL APPLICABILITY
[0037] The present invention is capable of exploitation in
industry, and can be made and used, whenever a distributed packet
data network providing mobility is desired.
[0038] Several examples and modes for practicing the present
description are described herein. However, the true spirit and
scope of the invention are not limited thereto, but are limited
only by the appended claims and their equivalents.
* * * * *