The present invention relates in general to information communication systems, and more particularly, to a wireless communication system architecture and protocols.
The advent of powerful, low-cost minicomputers enabled the evolution from centralized mainframe computer architectures to distributed computer architectures connected over high-speed data networks. Distributed computer architectures now range from local networks of computers within a single office, to wide-area networks covering miles, to satellite transmission systems covering entire global regions.
In contrast to distributed computer architectures, information databases have primarily remained in a centralized architecture. Database information is therefore typically disseminated to the distributed computers over communication data links. Thus, modern distributed computer systems often require the installation of high-speed data links to transmit information between processing sites. To meet these transmission requirements, high-speed data networks have been developed to link centralized information databases with distributed computer processing sites. Installation of high-speed data links, however, often requires costly and time consuming setup of high-capacity communication lines. Moreover, deployment of high-speed data links in remote field locations not served by the existing communication infrastructure is extremely difficult.
Today's communication infrastructure also includes various communication systems intended to serve other communication needs. For example, broadcast and cable television systems enable television programming to reach millions of viewers. In comparison, the public telephone network allows one subscriber to connect with another subscriber. Cellular telephone networks have extended traditional telephone service beyond the home and office to mobile subscribers. In addition, orbiting earth satellites can communicate with virtually unlimited numbers of users over large geographical areas, including areas not reached by traditional terrestrial communication systems. Service providers have also made extensive local and wide-area computer network systems accessible to the public. Such computer networks now allow users access to on-line news, sports, video and audio programming, information databases, and other computer resources such as the Internet.
These communication system are primarily designed to operate as an independent system with a transmission bandwidth capacity appropriate to serve the intended application. For example, telephone systems are primarily designed to handle low-bandwidth voice and data traffic. Accordingly, telephone systems typically support relatively low-bandwidth transmission at 9.6 kilo-bits per second (kbps). In comparison, computer networks designed to process real-time data or handle large amounts of digital data, such as an information database or graphical images, usually operate at a higher transmission bandwidth. A typical Ethernet computer network, for example, transmits at 10 megabits-per-second (mbps) for enhanced networks. Satellite communication systems designed to transmit full-motion digital video images may require even higher bandwidth equipment capable of transmitting 10 mbps or more.
In addition, communication systems may employ different methodologies to distribute information. Telephone networks primarily form point-to-point connections to connect a single subscriber to another subscriber. Computer networks typically allow a number of network nodes to access a number of other network nodes. In comparison, broadcast systems, such as a television or satellite broadcast system, typically allow one communication source to communicate with a large number of receivers.
The differences between communication systems in bandwidth rates and distribution methodology limits the interconnection and integration of heterogenous communication systems. For example, communication systems of different bandwidth rates typically cannot be connected without compensating for their different transmission rates. A 2 Mbps communication network, for example, cannot directly handle the volume of data transmitted from a faster 10 mbps system. In addition, consideration should also be given to the different manner in which systems disseminate information. Communications transported via broadcast systems are typically modified to integrate with point-to-point communication systems. Compatibility issues thus arise when interconnecting systems with different bandwidth rates and different distribution schemes. Connectivity between different communication systems may therefore be limited.
Furthermore, communication systems suffer from inherent transmission propagation delays associated with transmitting information over long distances and processing delays in distributing updated information across the system. For example, transmitting a data signal up to a geosynchronous satellite orbiting 35786 kilometers above the earth's equator and back down to a receiving earth station incurs about a quarter second transmission propagation delay. Transmitting a return signal from the receiving earth station incurs another quarter second delay. In addition to transmission propagation delays, distributed information systems may also incur processing delays in distributing updated information to users. A typical distributed information system requires users to specifically request or poll the information source to receive updated information. Waiting for a specific polling request, however, delays the distribution of updated information. While transmission propagation delays are inherent to the transmission of signals and cannot be eliminated, a communication system architecture and protocols can be implemented to minimize the effects of processing delays in distributing updated information to users.
The present invention relates to an architecture and protocols for a flexible multimedia communication dissemination system which combines satellite transmission systems, terrestrial wireless networks, and the public telephone system. Providing for the interconnection and integration between these various communication systems allows a high-speed communication system to be quickly deployed.
In one aspect of the invention, the communication system includes a broadcast server for broadcasting an information signal, and a mobile base station for receiving the information signal broadcast from the broadcast server. A local area network distributes information received by the mobile base station. In the preferred embodiment, the broadcast server includes a satellite uplink facility capable of accessing an information database and transmitting an information signal over a space segment. The mobile base station receives the transmitted information signal and operates the local area network. The local area network is preferably a wireless communication network which disseminates information to a number of mobile users.
In another aspect of the invention, a mobile base station includes a receiver for receiving information signals transmitted from a broadcast server, a network interface for distributing processed information signals, and a software proxy process for processing information signals transmitted from the broadcast server. In the preferred embodiment, the mobile base station receives an information signal transmitted via the space segment. The network interface preferably implements a mobile wireless network to allow flexibility in deploying the local area network. The mobile network also enables users to use the system in different locations. The software proxy process provides the interface between the mobile base station and the local area network.
In yet another aspect of the invention, the mobile base station includes a software proxy process to control the dissemination of information through the network. The software proxy process provides filter and protocol functions to facilitate interconnection between different communication systems. A bandwidth-based filtering process matches the bandwidth of the space segment to the bandwidth of the local area network. A user-based filtering process minimizes the bandwidth impact upon the space segment bandwidth when a number of mobile users are accessing similar database information. An active broadcast protocol minimizes latency delays associated with updating information across a distributed network.
The present invention allows several heterogenous communication systems to be integrated to form a high-speed communication system capable of transmitting multimedia data. Differences in bandwidth capacity and distribution methodology may be resolved by the software proxy of the mobile base station. The software proxy process integrates heterogenous communication systems and reduces the overall network load by reducing unnecessary transmissions. The integration of heterogeneous communication systems enables high-capacity data networks to be quickly deployed. Remote installations may be reached by a satellite covering a large geographical area. Wireless and mobile technology allows the system to be rapidly deployed with minimal equipment installation requirements.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. The invention, together with the further objects and intended advantages, will best be understood by reference to the following detailed description, taken in conjunction with the accompanying drawings.
a-3b show diagrams of the bandwidth-based filtering of the mobile base station of FIG. 1.
Referring now to the drawings. FIG. I illustrates a communication system 20. The system 20 preferably includes a broadcast server 22, a space segment 24. and a mobile base station 26. The mobile base station 26 disseminates information to the mobile users 30 through a local area network 32. The broadcast server 22 uplinks an information signal 40 via space segment 24 to transmit information to the mobile base station 26.
The communication system 20 enables mobile users 30 to access and transmit information from a source or database 36 through the mobile base station 26. The broadcast server 22 accesses the information source or database 36 containing different types of information required by the mobile users 30. The broadcast server 22 preferably transmits the information database 36 via the space segment 24. Broadcast server preferably compresses, error-codes, multiplexes, and amplifies an information signal 40 for transmission via the space segment 24 using conventional digital satellite transmission techniques. Broadcast server 22 preferably includes a high-power amplifier and large aperture 23 antenna for uplinking signals to space segment 24. Hughes Network System's commercially available DirecPC service, for example, provides a broadcast server 22 and space segment 24. The DirecPC Operations Center accesses information database 36 for delivery over the space segment 24.
The space segment 24 may be implemented using a satellite transponder with a footprint covering the geographical region where the mobile base station 26 is located. Preferably, a digital satellite transponder capable of transmitting a high-power direct broadcast satellite (DBS) signal is utilized to provide space segment 24. For example, DirecPC uses a Ku-band satellite transponder to transmit the information database 36 via an information signal 40 to the mobile base station 26.
Referring to
The satellite receiver/decoder 44 decompresses, decodes, and demultiplexes the received information signal 40 using conventional digital techniques for satellite communications. The satellite receiver/decoder 44 is preferably implemented with software and logic including a logic processor with associated read-only-memory (ROM) and random-access-memory (RAM). The DirecPC space segment transmitting at 12 Mbps typically requires a dedicated processor or other dedicated receive hardware. One skilled in the art will recognize that other equivalent forms of logic such as a field programmable gate array (FPGA) or application specific integrated circuit (ASIC) may be used to implement the logic of satellite receiver/decoder 44.
DirecPC provides the satellite receiver/decoder 44 electronics on a 16-bit ISA adapter card to allow installation in a standard IBM compatible personal computer (PC). Accordingly, the mobile base station 26 may be implemented with a IBM compatible PC running MS Windows 3.11. A DirecPC software driver controls the operation of the satellite receiver/decoder 44 and the decoding of the information signal 40. The DirecPC software driver provides the received database information transmitted from the broadcast server 22 via the space segment 24 to the mobile base station 26.
The mobile base station 26 preferably stores database information transmitted from broadcast server 22. Mobile base station 26 thus includes memory 50 for storing database information. The mobile base station 26 stores database information according to the multiplexing and dissemination protocol of the broadcast server 22 which is described below in more detail.
Referring again to
For example, a wireless local area network (LAN) can be implemented with IBM compatible PCs and AT&T's commercially available WaveLAN product. AT&T WaveLAN includes a network interface card (NIC) 33 with network software to control mobile network operation, and an antenna 35 for transmitting and receiving signals. The WaveLAN NIC 33 is available in both PC AT bus format and Personal Computer Memory Card International Association (PCMCIA) Type II format for portable laptop computers. The WaveLAN antenna 35 is equipped with an 18-inch cable to allow the antenna to rest on a desktop or other worksurface. WaveLAN uses 900 MHz spread spectrum technology to implement an Ethernet type CSMA/CA (collision sense multiple access/collision avoidance) wireless network scheme with a 2 Mbps data rate. Transmitting at an output power of 250 mW, the wireless network provides a range of 600 to 800 feet in open space. It should be understood that those skilled in the art may use a time-division or frequency-division multiplexed scheme operating at different frequencies to implement the wireless network scheme. Of course, network protocols other than Ethernet or data rates other than 2 Mbps may be utilized.
Mobile users 30 preferably include IBM compatible PCs equipped with the WaveLAN NIC, antenna, and software. In the most preferred embodiment, mobile users 30 include a portable laptop PC equipped with PCMCIA WaveLAN NICs. Mobile users 30 are configured according to the desired application. The mobile users 30 are thus able to communicate with the mobile base station 26 through the WaveLAN network 32. The combination of a portable computer with the wireless network maximizes the transportability and flexibility of the system.
Referring again to
The communication base system 20 distributes the information database 36 to a number of mobile users 30. Service requests from the mobile users are sent over the local area network 32 to the mobile base station 26. The mobile base station 26 relays the service request over the communication uplink 34 to broadcast server 22. The broadcast server 22 accesses the information database 36 for the requested information. The broadcast server 22 packages the requested database information and transmits it over the space segment 24. The mobile base station 26 receives the database information transmitted over the space segment 24 and disseminates the information over the local area network 32 to the mobile user(s) 30.
Referring to
As shown in
As shown in
User-based filtering, optimizes the utilization of the available space segment 24 (
As seen in
For example, a relevant change to a financial information database may comprise a change in stock prices. When a stock price change occurs to a stock of interest as defined by the rule set 90 the updated stock price is automatically distributed to the mobile base station 32 by the broadcast server.
Alternatively, the active broadcast rule may be defined by a service provider according to when and how often it wishes to provide updated information to mobile users. In such a case, the rule is not changeable by the mobile users.
Active broadcast automatically transmits updated information as relevant changes to the information occur. The active broadcast of updated information automatically pushes updated information out to the mobile users, thus minimizing the latency in providing updated information across the distributed network. In addition, active broadcast reduces the overall network load by reducing user polling requests for updated information and minimizing the transmission of redundant data.
The present invention allows the high-speed, real-time dissemination of multimedia information over interconnected heterogeneous communication systems. The interconnection of different communication systems and the use of wireless technology allows a flexible communication architecture. The flexible architecture enables the rapid deployment of a communication infrastructure in a variety of different locations.
Of course, it should be understood that a wide range of changes and modifications can be made to the preferred embodiment described above. A communication system, for example, may include a plurality of mobile base stations implementing a number of local area networks. It is therefore intended that the foregoing detailed description be regarded as illustrative rather than limiting and that it be understood that it is the following claims, including all equivalents, which are intended to define the scope of this invention.
This is a continuation of application Ser. No. 09/238,333 filed Jan. 27, 1999 which was a divisional of Ser. No. 08/589,274 filed Jan. 22, 1996, now issued as U.S. Pat. No. 5,915,207, issued Jun. 22, 1999. The entire disclosure of Ser. No. 09/238,333 is incorporated herein by this reference.
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Child | 09238333 | US |
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Child | 09849399 | US |