Use of lower IP-address bits

Details Use of lower IP-address bits Use of lower IP-address bits

1998-12-30

2003-09-23

Olms, Douglas (Department: 2661)

Multiplex communications

Pathfinding or routing

Switching a message which includes an address header

C370S328000, C370S338000, C370S392000, C370S401000, C370S402000, C370S403000, C370S404000, C370S475000, C709S226000, C709S223000, C709S220000, C709S245000

Reexamination Certificate

active

06625145

ABSTRACT:

BACKGROUND
The present invention relates generally to radiocommunication systems and, ore particularly, to techniques and structures for using the lower bits of an IP address as a mobile station identifier in order to facilitate packet data transfers.
The growth of commercial communication systems and, in particular, the explosive growth of cellular radiotelephone systems, have compelled system designers to search for ways to increase system capacity without reducing communication quality beyond consumer tolerance thresholds. At the same time usage of mobile communication equipment for transmission of data rather than speech has become increasingly popular by consumers. The possibility to send and receive electronic mail and to use a web browser to obtain world-wide-web access is frequently discussed as services that are desirable for wireless communication systems. As a response to this, communication system designers search for ways to efficiently transfer data information to and from mobile users.
There are fundamental differences between requirements for data communication and e.g., speech communication. For example, delay requirements are higher for speech, which is a real time service, and the error requirements are higher for data communications, while the delay constraints are lower. The use of packet data protocols, which are more suitable for transmission of data than circuit switched protocols, has started to find its way into cellular communication systems. Packet service integration in both Global System for Mobile communication (GSM) cellular systems as well as Digital Advanced Mobile Phone System (DAMPS) cellular systems is presently being standardized.
Today, GSM systems provide a circuit switched data service, which can be used to interconnect with external data networks. The circuit switched data service is used for both circuit switched as well as packet switched data communication. To make packet switched data communication more efficient, a new packet switched data service called General Packet Radio Services (GPRS) has been introduced as a part of GSM. GPRS will allow for packet switched communication (e.g., IP or virtual circuit switched communication). GPRS will support both a connectionless protocol (e.g., IP) as well as a connection-oriented protocol (X.25). One of the advantages with a packet switched data communication protocol is that a single transmission resource can be shared between a number of users. Thus, in the case of e.g., a GSM cellular system, a timeslot on a radio frequency carrier can be utilized by several mobile users for reception and transmission of data. The shared transmission resource is managed by the network side of the cellular system both for downlink and uplink transmissions.
GPRS is a GSM service and parts of the GSM infrastructure will be used. Those parts of the GSM communication system are described in European Telecommunication Standard Institute (ETSI) document ETS 300 574 which is expressly incorporated by reference herein.
FIG. 1
illustrates a block diagram of an exemplary cellular packet data system. As illustrated, the exemplary cellular system includes a plurality of mobile stations (MS)
100
1
-
100
N
which communicate with base station (BS)
110
. The base station
110
is connected to a Mobile Switching Center/Packet Mobile Switching Center (MSC/PMSC)
120
which in turn is connected to the operator's backbone network
140
through router
130
. A router, as will be appreciated by one skilled in the art, is a piece of hardware which operates at the network layer to direct packets between various nodes of one or more networks. The operator's backbone network
140
is connected to a host
170
, which is located on an Internet Service Provider's (ISP's) external Internet Protocol (IP) network
160
, through router
150
. One skilled in the art will appreciate that the number of components provided in
FIG. 1
is provided merely by way of example and that a typical packet data network generally includes a plurality of base stations, MSC/PMSCs, etc. Moreover, a typical packet data network would also include a firewall (not shown) which protects a local network from external threats, such as hackers. It will be further appreciated that the MSC and PMSC could be provided as a single node, as illustrated, or as separate nodes.
The MSs
100
1
-
100
N
will typically send packets to locations both within its private network
140
and on the Internet
160
. In order to receive packets from the Internet
160
, a MS needs a globally unique 32-bit IP address. Each such address has a four octet format which is generally expressed in a dotted decimal point format, with each octet written as a decimal integer separated from other octets by decimal points (e.g.,
147
.
117
.
45
.
123
).
Global IP addresses are issued according to one of three commonly used classes. Class A IP addresses employ their first octet as a network identifier and their remaining three octets as a host identifier. Since three octets are available for specifying a particular host, an enterprise having class A addresses has nearly 2
24
, or nearly 17 million, addresses at its disposal for use with possible hosts. Class B IP addresses, on the other hand, employ their first two octets to identify the network and their second two octets to identify a particular host. Thus, an enterprise having class B addresses can use those addresses to identify approximately 64,000 hosts. Finally, class C IP addresses employ their first three octets to identify the network and their last octet to identify a host. As such, only 256 host addresses are available to enterprises having a single class C network identifier.
In the system of
FIG. 1
, the operator of the MSC/PMSC 120 generally has a plurality of IP networks which can be accessed by the MSs. As discussed above, class B and C networks provide the operator with the greatest number of available network identifiers, and therefore, the greatest number of possible networks which can be provided to the MSs. A typical class C network may have the following IP addresses at its disposal:
194.52.10 Net address
Local address
194.52.54 Net address
Local address
The local (i.e., host) address part is only 8 bits in class C networks. In the example above, this enables the MSC/PMSC operator to service 44*256 MSs for IP-communications. As will be appreciated by one skilled in the art, the router
130
and the MSC/PMSC 120 must be configured at installation in such a way so as to allow IP-addresses, which have been assigned to the MSs, to be routed correctly.
FIG. 2
illustrates a simplified block diagram of the exemplary network set forth in
FIG. 1
in order to describe the process by which a mobile station, for example MS
1001
, communicates with the host
170
. The ISP's IP network
160
, the operator's backbone network
140
, and routers
130
,
150
of
FIG. 1
are illustrated as a single IP network with routers
260
in the simplified block diagram. In order for the mobile station
1001
to communicate with host
170
, the mobile station must first register with the MSC/PMSC
120
. This registration process is simply a log-in process and is accomplished by the MS
1001
transmitting its unique long identifier to the MSC/PMSC
120
to request an Internet packet session. In turn, the MSC/PMSC
120
assigns the MS
1001
a globally unique IP-address from a pool of addresses kept by the node (i.e., the MSC/PMSC). The MSC/PMSC
120
may also assign, as will be discussed in more detail below, a short mobile station identifier.
As illustrated, the MSC/PMSC
120
comprises a memory
222
for storing local data for each mobile station that the MSC/PMSC
120
is servicing. This local data includes, among other things, protocol state variables and aids in the packet transmission process. The local data is referenced by either the mobile station's unique long or short identifier or the unique IP address which has been assigned to the mobile station for the current packet data session.
After successfu

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