U.S. patent application number 12/751730 was filed with the patent office on 2010-07-29 for utilization of the internet protocol to facilitate communication involving mobile devices.
This patent application is currently assigned to BROADCOM CORPORATION. Invention is credited to Rajiv Kumar, Martin Morris, Lyn Nguyen, Hiep Pham.
Application Number | 20100189041 12/751730 |
Document ID | / |
Family ID | 34549096 |
Filed Date | 2010-07-29 |
United States Patent
Application |
20100189041 |
Kind Code |
A1 |
Morris; Martin ; et
al. |
July 29, 2010 |
UTILIZATION OF THE INTERNET PROTOCOL TO FACILITATE COMMUNICATION
INVOLVING MOBILE DEVICES
Abstract
A data communication system capable of forwarding IP-addressed
data to devices as such devices move among networks having
different IP addresses is dislcosed herein. The system includes
first and second networks containing first and second pluralities
of nodes. At least one of the first plurality of nodes is adapted
to receive data transmissions from an external IP-based network.
Upon joining the first network, this device is assigned an IP
address which remains with it irrespective of whether it moves
beyond the range of the first network. When this device roams into
the vicinity of the second network, data addressed to the device
which is received at the first network is forwarded via at least
one node of the second network to the roaming device.
Inventors: |
Morris; Martin; (Vista,
CA) ; Kumar; Rajiv; (San Diego, CA) ; Nguyen;
Lyn; (San Diego, CA) ; Pham; Hiep; (San Diego,
CA) |
Correspondence
Address: |
MCANDREWS HELD & MALLOY, LTD
500 WEST MADISON STREET, SUITE 3400
CHICAGO
IL
60661
US
|
Assignee: |
BROADCOM CORPORATION
Irvine
CA
|
Family ID: |
34549096 |
Appl. No.: |
12/751730 |
Filed: |
March 31, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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|
11024898 |
Dec 29, 2004 |
7697470 |
|
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12751730 |
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|
09347374 |
Jul 6, 1999 |
6891820 |
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11024898 |
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Current U.S.
Class: |
370/328 ;
370/401 |
Current CPC
Class: |
H04L 61/2084 20130101;
H04W 80/04 20130101; H04W 52/38 20130101; H04W 88/06 20130101; H04L
29/12311 20130101; H04W 8/02 20130101 |
Class at
Publication: |
370/328 ;
370/401 |
International
Class: |
H04W 40/00 20090101
H04W040/00 |
Claims
1. A data communication system comprising: A first network
including a first plurality of nodes, said first network having a
first network address; A second network including a second
plurality of nodes, said second network having a second network
address; and Means for forwarding, from said first network to said
second network, message information received at said first network
and addressed to a first node of said first plurality of nodes when
said first node establishes communication with said second
network
2-8. (canceled)
Description
CROSS REFERENCE TO RELATED PATENT APPLICATIONS
[0001] The entire disclosures of copending U.S. Patent Application
entitled "Distributed Management of an Extended Network Containing
Short-Range Wireless Links" and copending U.S. Patent Application
entitled " Implementation of Power Control in a Wireless Overlay
Network", both filed on even date herewith, are hereby incorporated
by reference.
FIELD OF THE INVENTION
[0002] The present invention relates generally to communication
systems, and more particularly to a method and associated apparatus
for allowing a device to continue communication via the Internet
Protocol ("IP") even while moving among networks having different
associated IP addresses.
BACKGROUND OF THE INVENTION
[0003] Computer networks allow multiple computers, peripherals and
other information storage, retrieval or processing devices to share
data. Each device attached to a network is typically referred to as
a node on the network, or a node that is part of the network. Local
Area Networks ("LANs") have historically consisted of nodes
interconnected by physical telecommunications media (e.g., coaxial
cable, twisted pair wire, or fiber optics). Recently wireless LANs,
the nodes of which are not connected by means of a physical medium,
have started to appear in the market. These wireless LANs
communicate by means of infra-red (IR), radio or other signals. One
of the benefits of using wireless LANs is that cabling is not
required. This is a particularly useful feature for mobile nodes
such as laptop and notebook computers, PDAs (personal digital
assistants), and the like. If equipped with an appropriate wireless
adapter, the mobile nodes can move around within a predefined
coverage area and remain connected to the network.
[0004] In order for the nodes of a particular network to be able to
communicate with each other, some sort of common addressing scheme
must be implemented. In a traditional wired network, one very
common method of communicating between nodes is to utilize Internet
Protocol ("IP") addressing. When a node initially joins a network
operating with the Internet Protocol, it is assigned an IP address
consisting of at least two portions: a network address and a
destination address. IP addresses are typically fixed and remain
with the node irrespective of whether the node relocates to another
network. In a traditional wired network, the fixed nature of IP
addresses is not problematic because nodes are stationary and
consequently do not migrate to networks outside of their original
home network. Recently, wireless nodes have been added to
traditionally hard-wired networks. Like all devices adhering to the
Internet Protocol, mobile devices are accorded IP addresses having
a network portion and a device portion. The network portion
identifies the mobile device's "home network" while the device
portion distinguishing the mobile device from other members of its
home network. The routing of data packets through the Internet is
generally exclusively based upon the network portion of the
destination IP address. Specifically, Internet routers extract the
destination network address from a given data packet and then
forward that packet to the appropriate network. Once the packet
reaches the appropriate network, the network server examines the
device portion of the IP address and forwards the packet to the
appropriate device.
[0005] When a mobile device is located in its home network, data
packets addressed to a particular mobile device are simply sent to
such device upon being received at the home network's access point.
This process is transparent to the user so long as the mobile unit
is located within range of its home network. However, when the
mobile device travels outside of its home network data packets
cannot easily be forwarded thereto and are often "dropped", which
results in loss of data.
[0006] Several methods have been proposed to allow mobile devices
to continue IP-based communication even when moving between
networks having different IP addresses. One such technique requires
that the mobile unit report changes in its address to the access
point or network manager in its home network. A router located in
its home network stores each new IP address for the mobile unit and
forwards any incoming packets to the mobile device's new IP
address. An alternate approach involves establishing a pseudo
presence, also called a "spoofed address," at the mobile's home
network location. However, when mobile devices frequently move
between networks having different IP addresses, these
address-mapping and forwarding techniques can results in packets
being forwarded to multiple locations, which may cause confusion
and loss of data.
SUMMARY OF THE INVENTION
[0007] Briefly, therefore, the present invention relates to a data
communication system capable of forwarding IP-addressed data to
devices as such devices move among networks having different IP
addresses. The present invention includes first and second networks
containing first and second pluralities of nodes. At least one of
the first plurality of nodes is adapted to receive data
transmissions from an external IP-based network. Upon joining the
first network, this device is assigned an IP address which remains
with it irrespective of whether it moves beyond the range of the
first network (i.e., the device's "home" network). When this device
roams into the vicinity of the second network, data addressed to
the device which is received at the first network is forwarded via
at least one node of the second network to the roaming device.
[0008] In a preferred embodiment, each of the nodes in the first
and second networks broadcast messages indicating the services that
it offers and the nodes that are within its range. These broadcasts
allow the mobile device to determine which devices it can use to
create a connection between itself and the local access point in
its home network. When the mobile device moves beyond its home
network, it reestablishes a connection to its local access point
using whatever combination of nodes it deems as being most
efficient. Once this connection is made, the local access point is
able to forward data to the mobile device. In an alternate
embodiment, an internetworking node participates in both the first
and second networks, and receives a first set of network
information relating to the first network from the first plurality
of nodes. In an another embodiment, the mobile device is capable of
anticipating when it is about to lose contact with one of the nodes
that is providing a connection between it and its home local access
point. When the mobile device makes this determination, it attempts
to establish an alternative route for the connection to its local
access point. If the mobile device is of a type requiring
continuous connection to an external network, an additional
embodiment allows the mobile device to simultaneously maintain more
than one connection between itself and its local access point. This
minimizes the risk that data packets addressed to the mobile device
will be "dropped".
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] In the accompanying drawings:
[0010] FIG. 1 shows a data communication system comprising two
wireless networks and a means for forwarding data between the
networks.
[0011] FIG. 2 contains a data communication system consisting of
two wireless networks and an internetworking node in accordance
with a preferred embodiment of the present invention.
[0012] FIG. 3 is a block diagram illustratively representing the
components of a wireless node and associated software configured in
accordance with a preferred embodiment of the present
invention.
DETAILED DESCRIPTION OF THE INVENTION
[0013] The present invention is more fully described with reference
to FIGS. 1-3. An exemplary implementation of the invention is
discussed and illustrated with reference to its implementation
using wireless networks predicated on the proposed "Bluetooth"
wireless communications protocol. This protocol contemplates the
grouping of physically proximate wireless nodes, and is described
in Specification of the Bluetooth System, v0.8, Jan. 22, 1999 (and
in subsequent revisions thereof). It should be understood that this
invention is not limited to such a wireless protocol, and could be
similarly implemented using other types of fixed or wireless
networks. As is described hereinafter, the present invention
discloses a method and apparatus for relaying data addressed to a
mobile device nominally associated with a first network when such
device becomes associated with other networks.
[0014] FIG. 1 illustrates a data communication system 10 consisting
of a hard-wired network 12 and first and second wireless networks
20 and 22, each containing a network address location A1 and A2.
The first and second wireless networks 20 and 22 each contain a
plurality of wireless nodes. For purposes of clarity, only wireless
nodes L1 and L3 are depicted in wireless networks 20 and 22. It
should nonetheless be understood that the present invention is
equally applicable to implementations in which first and second
wireless networks include numerous wireless nodes. The system 10
also contains a relay node L2 connecting the two wireless networks,
a first mobile device D1, and a hard-wired device D2 connected to
the hard-wired network 12. In a typical configuration, D2 would
actually be a network of devices rather than a single device. The
device D2 may comprise either a network of devices or simply a
single device. Since the actual number of devices represented by D2
is irrelevant for purposes of explanation of the present invention,
device D2 will hereinafter be referred to as a single device.
[0015] For purposes of illustration, it is assumed that certain of
the wireless nodes depicted in FIG. 1 are mobile relative to one
another. In the network architecture of FIG. 1, each node within
the first network 20 is within the wireless coverage area of
network access node A1 and each node within the second network 22
is within the wireless coverage area of network access node A2. The
network access nodes A1 and A2 serve as conduits to the external
network 12 for the first and second wireless networks 20 and 22,
respectively. The access nodes A1 and A2, as well as a relay node
L2, are also disposed for wireless communication with the nodes L1
and L3.
[0016] Because the nodes within the wireless networks 20 and 22 are
not necessarily within transmission range of all the other wireless
nodes within the same networks, each wireless node may not be able
to monitor all of the traffic within its network. For example,
wireless node L1 may be able to "listen" to wireless node L2 but
may not be able to monitor transmissions from wireless node L3. In
a preferred implementation each wireless node transmits an
advertisement identifying its address and the services it offers.
Each such advertisement also incorporates the address of all other
wireless nodes from which advertisements are received by the node
transmitting a given advertisement. Based on this information, the
mobile device D1 can determine all nodes participating in the
networks and the service offered by each. As used herein the term
"services" encompasses, without limitation, the capability of a
given node to relay message information to and from one or more
outside networks. Accordingly, the advertisement issued by each
wireless node may also identify the other networks within which the
wireless node is capable of communication and the services offered
by each.
[0017] Referring to FIG. 1, when D1 first seeks to join the first
wireless network 20 it transmits a signal to the network access
node A1 via wireless node L1 so that it can be assigned an IP
address by the Internet Service Provider ("ISP") providing network
access via node A1. Through this transmission, device D1
establishes the first wireless network 20 as its home network; that
is, it designates the network address of the first wireless network
20 as its network address. Because device D1 is not hard-wired to
node A1, it is necessary for device D1 to access node A1 via a
wireless communication link. In the exemplary implementation of
FIG. 1, device D1 determines that it can establish a connection to
node A1 through node L1 by listening to the periodic advertisements
issued by nodes A1 and L1. As was mentioned above, these broadcasts
contain network connectivity information pertinent to of all of the
devices within range of A1 and L1. For example, A1's broadcast
would indicate that it is connected to the hard-wired network 12,
and is capable of communication with nodes L1 and L2. Similarly,
node L1's broadcast would reveal that it is within range of, and
capable of communication with, nodes A1, L2 and D1.
[0018] Data may be routed to node D1 in a conventional manner when
node D1 is within its home network 20. In this situation data
destined for node D1 is sent to the IP address of node A1 from the
external network 12. On the basis of the advertisements broadcast
by L1, node A1 determines that node L1 has established a connection
to D1. Node A1 then sends the data received from the external
network 12 to node D1 via node L1.
[0019] Routing data to D1 using IP addressing becomes problematic
when D1 moves outside of its home network 20, since node D1's IP
address does not automatically change to reflect its new location
within a different network. As a consequence, all the data intended
to be sent to node D1 will continue to be routed over the external
network 12 to node A1. If node A1 does not have a separate
connection to device D1 when data packets arrive, node A1 will
either drop the data packets or queue them for retransmission on
the assumption that D1 will establish a new connection with A1.
[0020] Referring to FIG. 1, when D1 relocates to a position within
the wireless coverage area of network 22 it listens to the
connectivity information broadcast by the nodes within its range
(device D1 is shown in phantom in network 22). If device D1 becomes
located sufficiently near node L3, it may listen to its
connectivity advertisement and determine a path over which data may
be routed from node A1. After making this determination, D1
requests a connection to node A1 via a node along the chosen path
(e.g., node L3). In order to establish a connection between nodes
D1 and A1, node L3 establishes a connection to node L2 which in
establishes a connection to node A1. Once these connections have
been made, node A1 will forward any data packets addressed to D1
that it has received over the hard-wired network 12.
[0021] FIG. 2 depicts an alternate embodiment of the present
invention in which a wireless node L2' exists as a member of both
first and second wireless networks 20' and 22'. The node L2'
facilitates internetworking between the networks 20' and 22' in the
manner described in the aforementioned copending Patent Application
entitled "Distributed Management of an Extended Network Containing
Short-Range Wireless Links". The wireless node L2', or
"internetworking node", understands the protocols of both the first
and second wireless networks 20' and 22' and is capable of
transparently relaying data traffic therebetween.
[0022] Referring again to FIG. 2, once device D1' begins moving
outside of its home network 20' it may anticipate the loss of its
connection to the network access node A1'. This is because device
D1' monitors the signal strength of the advertisements being
transmitted from L1', and will take notice when this signal
strength drops below a predefined threshold. Once device D1'
determines that a dropped connection between itself and node L1' is
imminent, it will "listen" to the advertisements being broadcast by
other wireless nodes within its range to determine if it can
establish a simultaneous connection to node A1'. In the exemplary
implementation of FIG. 2, device D1' determines that it may
establish communication with node A1' via node L2'. Accordingly,
device D1' then drops its connection with L1' after establishing a
connection with node L2'. In this way device D1' endeavors to
minimize the risk of loss of data packets by briefly maintaining a
simultaneous connection to two distinct wireless nodes. In
applications where preventing any loss of data packets is very
important, device D1' may maintain such a simultaneous connection
continuously or for substantially longer periods of time.
[0023] FIG. 3 is a block diagram illustratively representing the
components of a wireless node 100 and associated software
configured in accordance with a preferred embodiment of the present
invention. Referring to FIG. 3, the wireless node 100 may be in the
form of an electronic device (e.g., a laptop or desktop computer,
hand-held electronic organizer, or printer) containing a first
wireless adapter card 104 and a first RF transceiver 106 disposed
for communication in accordance with a first network communication
standard. The wireless node 100 may also optionally include a
second wireless adapter card 108 and a second RF transceiver 110
for communicating in accordance with a second network communication
standard. The second wireless adapter card 108 and the second RF
transceiver 110 may be included within the wireless node 100 when,
for example, it is anticipated that the wireless node may
participate in networks operative in accordance with different
network standards. For example, internetworking node L2' would
preferably be configured with different wireless transceivers and
associated adapter cards to the extent the first network 20' and
second network 22' were governed by differing network communication
standards. The wireless node 100 may also include a LAN adapter
card 112 for facilitating communication with a wired LAN, or
alternately a wireline modem for effecting communication through
the PSTN.
[0024] Each wireless adapter card and transceiver is controlled by
a CPU 114 operative to execute program instructions of the various
software routines 122 stored in memory 126. Within wireless nodes,
a network resources table 130 is updated in response to interne
management broadcasts by transmitting nodes of the individual
wireless networks. The network resources table 130 stores the
network address and services offered by each wireless node. In the
case of internetworking node L2', these advertised services may
include the services provided by a wireless node from a neighboring
network in communication with the internetworking node.
[0025] Included among the software routines 122 within
internetworking nodes is a forwarding routine 138 for forwarding
messages to the wired LAN via the LAN adapter card 112, or to
another wireless node via one of the wireless transceivers 106, 110
and associated wireless adapter card 104, 108. An advertisement
generating routine 140 operates to generate the advertisements
issued by the wireless node 100 which specify its network address
and services offered.
[0026] Although the above application has been described primarily
with reference to specific embodiments, one skilled in the art can
readily appreciate that the teachings of the present invention may
be applied in other communication contexts. For example, in certain
embodiments the first and second wireless networks described above
could instead comprise networks of fixed devices linked by
hard-wired local area networks ("LANs"). Assuming a wireless or
other communication link could be established between a pair of
devices within the different networks, data could be forwarded
among such networks in accordance with the invention upon movement
of a device from one network to the other. Thus the application is
meant only to be limited by the scope of the appended claims.
* * * * *