Multiplex communications – Pathfinding or routing – Combined circuit switching and packet switching
Reexamination Certificate
2000-03-02
2002-07-09
Olms, Douglas (Department: 2661)
Multiplex communications
Pathfinding or routing
Combined circuit switching and packet switching
C370S355000, C455S414200
Reexamination Certificate
active
06418138
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a communication system, and more specifically relates to an Internet radio communication system including a plurality of mobile units (e.g., Internet radios) distributed within a wireless communication network.
2. Discussion of the Background
Currently, a user may connect to the Internet via a wireless network. Thus, the user may perform Internet activities without needing phone lines or cable connectors. For example,
FIG. 1
illustrates a Ricochet wireless MicroCellular Data Network (MCDN) developed by METRICOM. The Ricochet Network is a wide-area wireless system using spread-spectrum, packet-switching data technology and a frequency-hopping mesh architecture. The network operates within the license-free (902-998 MHZ) range of the Radio Frequency (RF) spectrum, providing Ricochet subscribers with an affordable wireless solution and an alternative to standard telephone modems requiring phone line connections.
As shown in
FIG. 1
, the Ricochet wireless network includes a Ricochet wireless modem
100
, which weighs about 13 ozs., attached to a laptop computer
102
. The network also includes shoebox-size radio transceivers
106
, which are typically mounted to street lights or utility poles
104
. The radio transceivers
106
require only a small amount of power from the street light itself (connected with a special adapter) and are otherwise self-contained units (no other wiring or connections are necessary). In addition, the microcell radio transceivers
106
are strategically placed every quarter to half mile in a checkerboard pattern. Each radio transceiver
106
employs 162 frequency-hopping channels, and uses a randomly selected hopping sequence. This allows for a very secure network, and enables many subscribers use of the network at the same time.
In addition, within a 20-square mile radius (containing about 100 radio transceivers), the Ricochet network includes Wired Access Points (WAPS)
108
. WAPS
108
collect and convert the RF packets into a format for transmission to a T
1
frame-relay connection to a wired IP network backbone in a network interconnection facility
110
.
The Ricochet network also includes a Ricochet name server
114
, which resides on the Metricom backbone provided within the network interconnection facility
110
and provides connection validation and path information to the Ricochet modems
100
. All connection requests go to the name server
114
for authorization before a connection can be made. When a Ricochet modem
100
is first powered on, it sends a packet to the name server
114
containing the Ricochet modem's serial number. The name server
114
validates the subscription and the service request. If either the subscriber serial number is invalid or the requested service is not what the subscriber has purchased, the accessed request is denied. Only after the Ricochet modem
100
successfully registers with the name server
114
can the subscriber obtain Internet or phone line service access to the Ricochet network. The router
107
and gateway
109
provide a connection between the Internet
112
and Ricochet wireless network.
Further, the Ricochet network distributes data between the Internet
112
and the laptop computer
102
using a unicast transmission method. Unicast transmission is designed to transmit a single packet to a single destination and is inherently a point-to-point type of communication. If a node wants to send the same information to many destinations, it must send a copy of the same data to each recipient in turn. That is, the same information must be carried over the network multiple times.
One problem with a wireless network based on the unicasting transmission method is tens of thousands of subscribers simultaneously access the network, and many of these subscribers may be accessing the same information. Thus, in the unicast transmission method, there is a substantial replication of data packets. Accordingly, bandwidth usage is inefficient and some users may be prevented from accessing the network during peak times, for example. Further, the name server
114
does not provide sufficient management and control operations for the network. Thus, the only way a user knows the system is at maximum capacity, for example, is by attempting to log onto the network and finding that he or she is unable to access the network.
SUMMARY OF THE INVENTION
Accordingly, one object of the present invention is to solve the above and other noted problems.
Another object of the present invention is to provide a novel Internet radio communication system which transmits data between a mobile unit (e.g., an Internet radio) and the Internet using a multicasting transmission method if more than one user selects a same Internet service.
Yet another object of the present invention is to provide a proxy server for determining a system capacity of the network, managing the network, and converting unicast data packets to multicast data packets, for example.
To achieve these and other objects, the present invention provides a novel communication system including mobile units distributed within a wireless communication network which are connected to a packet switched network (e.g., the Internet) via a proxy server. The proxy server converts unicast data packets coming from the packet switched network to multicast data packets being transmitted to the mobile units, if more than one mobile unit requests a same service (e.g., a same Uniform Resource Locator—URL). The proxy server is also responsible for the overall management and control of the communication system.
REFERENCES:
patent: 6122514 (2000-09-01), Spaur
patent: 6161008 (2000-12-01), Lee
patent: 6181697 (2001-01-01), Nurenberg
Cerf Vinton
Huddle Scott
Olms Douglas
Pizarro Ricardo M.
WorldCom, Inc.
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