Telecommunications – Radiotelephone system – Auxiliary data signaling
Reexamination Certificate
1997-03-20
2002-12-17
Kincaid, Lester G. (Department: 2685)
Telecommunications
Radiotelephone system
Auxiliary data signaling
C455S426100, C455S432300, C455S435100, C455S445000, C370S338000, C370S349000
Reexamination Certificate
active
06496704
ABSTRACT:
TECHNICAL FIELD
The application relates to the field of electronic communications and more particularly to the field of computer networks that provide services to mobile data devices.
BACKGROUND OF THE INVENTION
The advances of wireless communication and micro-electronic technologies have enabled the tremendous growth of wireless communication services. For example, in just a few years, cellular telephone networks have appeared all over the country, and cellular phones have become a common consumer item. Currently, the majority of wireless communication services are geared towards voice applications and/or paging. However, due to the increasing popularity of portable computers, telecommunications engineers are now developing wireless data communication networks that transmit packets of digital data. These systems will allow a mobile computer system to remain connected to a data network, while the computer system travels to different locations.
To this end, the cellular digital packet data (CDPD) protocol recently has been developed to address the issue of network layer mobility support for data networks. The CDPD protocol was developed by the CDPD Forum, an industry association consisting of cellular carriers and equipment vendors, to provide packet data services through the cellular telephony network. One attribute of CDPD is that it allows a network device to change its location within the network. This improves upon static network systems that employ network connectivity and routing that fails to support mobile network devices.
CDPD is designed to exploit unused capacity of the cellular telephone network for packetized data delivery. It employs the existing cellular infrastructure along with additional CDPD specific equipment.
Referring to
FIG. 1
, a CDPD network
20
has a first network area
22
that includes at least one mobile end system (MES)
24
. The MES
24
may be implemented as a mobile terminal with a wireless modem that accesses the CDPD network
20
through an airlink. The MES
24
may have one or more network entity identifiers (NEI) which can be either Internet protocol or connectionless network protocol addresses. The wireless modem used in connection with the MES
24
may also have a 48 bit CDPD equipment identifier assigned by the manufacturer.
The network area
22
also includes at least one mobile database station (MDBS)
26
that provides mobile data link relay functions for the MES
24
over the radio channel. In the CDPD protocol, the MDBS
26
performs part of the radio resource management function to insure that the user data does not interfere with the regular voice users of the cellular network. In the CDPD protocol, there may be up to two hundred MDBS's in the network area
22
.
The network area
22
also includes a mobile data intermediate system (MDIS)
28
which controls mobility and performs registration, authentication, and routing functions. The MDIS
28
is a network gateway and also controls the MDBS
26
in connection with radio resource management.
Another CDPD network area
32
also contains at least one MES
34
, at least one MDBS
36
and another MDIS
38
. The MES
34
, the MDBS
36
, and the MDIS
38
of the network area
32
are all analogous to corresponding components of the network area
22
. As described in more detail below, the CDPD network
20
allows the MES
24
from the first area
22
to migrate to and operate in the second area
32
and, similarly, allows the MES
34
from the second area
32
to migrate to and operate in the first area
22
.
The MDIS
28
from the first area
22
and the MDIS
38
from the second area
32
function as gateways into a conventional Internet protocol and/or connectionless protocol network backbone
42
. The backbone
42
is connected to one or more intermediate systems
44
which are connected to one or more fixed end systems
46
in a conventional manner. Accordingly, the MES
24
from the first network area
22
may communicate with the MES
34
in the second network area
32
and/or the fixed end system
46
. Similarly, the MES
34
from the second network area
32
may communicate with the MES
24
from the first network area
22
and/or the fixed end system
46
. Each of the network areas
22
,
32
may be treated as a single network segment (e.g. Ethernet) with each of the respective MDIS elements
28
,
38
serving as the network gateway. Note that, by convention, all CDPD network areas use 166 as the network prefix. For example,
FIG. 1
shows the first network area
22
having an address of 166.200.x.x and the second network area
32
having network addresses 166.100.x.x.
The CDPD protocol allows the MES
24
to migrate out of the area
22
and into the area
32
while still maintaining a data connection to the network. Such a migration is illustrated by a dotted line
48
. Once the MES
24
has entered the second area
32
, the MES
24
recognizes the new area during cell transfer by listening to a channel identification message broadcast from the MDBS
36
of the second area
32
during channel acquisition. Upon detecting the new area
32
, the MES
24
initiates a registration process using the conventional Mobile Network Registration Protocol (MNRP) via the new MDIS
38
. The new MDIS
38
handles the registration for the MES
24
and communicates with the home MDIS
28
(i.e., the original MDIS of the MES
24
) so that appropriate authentication can be performed, and appropriate routing can be set up at the home MDIS
28
to forward packets designated for the MES
24
in an appropriate manner, as described in more detail hereinafter.
When the MES
24
migrates from the first area
22
to the second area
32
, an authentication process is used to verify the identity of the MES
24
. In the CDPD network protocol, airlink security is accomplished by exchanging secret keys between the serving (i.e., new) MDIS
38
and the visiting MES
24
using a Diffe/Hellman key exchange scheme. After the MES
24
obtains a key from the MDIS
38
, the MES
24
sends authentication information to the serving MDIS
38
. This authentication information includes an authentication random number, an authentication sequence number, and the network entity identifier of the MES
24
. The serving MDIS
38
then relays this authentication information to the home MDIS
28
for confirmation.
After confirming the visiting MES
24
, the home MDIS
28
provides to the serving MDIS
38
a success indicator. The home MDIS
28
also assigns a new authentication random number and authentication sequence number and provides that information to the serving MDIS
38
, which then relays that information to the visiting MES
24
. The new authentication random number and authentication sequence number can be used for authentication in connection with a subsequent registration of the MES
24
. Once this information has been transferred from the home MDIS
28
to the serving MDIS
38
, the registration at the home MDIS
28
(or at another previous serving MDIS) is canceled.
FIG. 2
is a data flow diagram
50
illustrating an exchange of messages that occurs under the CDPD when an MES moves from a network being served by an old serving MDIS to a network being served by a new serving MDIS. The home MDIS is shown as a separate device because, generally, the home MDIS is not required to be either the old serving MDIS or the new serving MDIS. Note that in the example discussed in connection with
FIG. 1
, the home MDIS is illustrated as being the old serving MDIS.
The diagram
50
shows that the MES first exits from the network being served by the old serving MDIS. Following that, the MES enters the new network served by the new serving MDIS and establishes a datalink therewith. The MES then provides the new serving MDIS with an end system hello, which includes the authentication information discussed above. Upon receipt of the end system hello, the new serving MDIS forwards the authentication information to the home MDIS for confirmation by the home MDIS. The home MDIS then confirms the authentication information an
Kincaid Lester G.
Suchyta Leonard Charles
Verizon Laboratories Inc.
Weixel James K.
LandOfFree
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