Electrical computers and digital processing systems: support – Computer power control
Reexamination Certificate
2000-05-19
2003-12-23
Lee, Thomas (Department: 2185)
Electrical computers and digital processing systems: support
Computer power control
C713S310000, C709S249000, C709S250000, C340S315000
Reexamination Certificate
active
06668328
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to computer networks, and more particularly, to a system and method for coupling signals to a power line network.
2. Discussion of the Related Art
LANs are computer networks operating over a small area such as a single department in a company. Most LANs serve to transport data between personal computers and workstations and file servers. In general, the devices on a LAN must follow certain rules of operation to communicate effectively. These rules of operation are known as protocols. A variety of different LAN protocols are available. For example, the IEEE 802.3 standard deals with a network architecture and protocol termed Ethernet. Stations in an Ethernet network may be connected through interfaces to a coaxial cable, twisted pair wire or fiber optics. A major disadvantage associated with Ethernet technology is the cost of routing a transmission medium between each proposed station on the LAN.
The dramatic growth of Internet applications has created the need for small office, home office, and remote locations with multiple personal computers (PCs) to share high speed interfaces with the Internet. In addition, business and home office configurations have a need to share files and peripheral devices, such as printers, among several PCs. A variety of techniques to interconnect various closely located PCs, peripherals, and “Internet compatible appliances” have been proposed including: radio-frequency (RF), infrared, existing phone lines, power lines, and traditional cabling methods. Each of the alternative infrastructure configurations has advantages and disadvantages for the end user.
Radio-Frequency
RF transceivers may provide a wireless mechanism to interconnect various PCs and related peripherals inside a home or office. BLUETOOTH™—is an example of a low-power RF implementation. RF transceiver infrastructures eliminate most of the cabling from the LAN and provide limited location independence for their users. In order to effectively transfer data, the data transmissions must be broadcast with sufficient power to enable reception and accurate demodulation of the intended data signal at the receiving device. As a result, RF systems are subject to “eavesdroppers” that might intercept the radiated data signals. Furthermore, RF LAN infrastructure systems may require Federal Communications Commission (FCC) licenses to operate equipment at certain frequencies, adding to the installation and operating expense of the system. RF systems designed to operate in unlicensed frequency bands assume a potential risk of interference from other users. In order to achieve practical data rates and reasonable antenna sizes using RF technology without the added expense of procuring broadcast licenses, typical implementations operate between 2 to 3 GHz in the unlicensed band of frequencies. This frequency range suffers from significant degradation due to path loss in environments with significant water vapor. In short, RF LAN infrastructures suffer from low security and the risk of RF interference from operators of like equipment. In addition, RF LAN implementations may suffer from interference from microwave ovens and significant signal power loss in damp environments.
Radio-Frequency—BLUETOOTH™
BLUETOOTH™ is a low-power RF technology designed to operate in the 2.4 GHz ISM band. BLUETOOTH™ is designed to operate over a distance of 10 meters with the goal of interfacing various local devices without cables. Ideally, BLUETOOTH™ compatible devices could connect via the low-power RF link to enable a laptop computer to access an Email account via a cellular phone. The link is established without traditional cabling between the cellular phone and the laptop computer, assuming both devices are equipped with the BLUETOOTH™ RF technology and are within transmission range of each other. BLUETOOTH™ suffers from security issues like other RF technologies. Security issues are not as severe for BLUETOOTH™ due to its lower transmitted power. On the other hand, lower transmitted power results in a shorter effective range of operation.
Infrared Communications
Infrared (IR) communications were popularized by the television remote control and have since penetrated a host of other home electronic device, personal data assistant (PDA), and laptop computer markets. Current technology uses IR light emitting diodes (LEDs) to emit sufficient optical energy to communicate data between devices within line of sight of one another. As such, IR communications are limited to a particular room as the frequencies do not penetrate solid objects. Data rates as high as 16 Mbps are expected to soon be a reality as IR communications standardization groups drive the technology.
Telephone Lines
Telephone lines are a common fixture in most every US home. In addition, most PCs are equipped with telephone modem technology and are usually connected to a telephone line servicing the home via a jack and a patch cord. Modem manufacturers have interconnected PCs through the use of various modulation schemes at high frequencies to avoid interference from POTS and standard data modem communications. A home networking consortium technology (Home PNA) was formed to advance phone line networking. The consortium has developed a series of standards defining protocols. However, unterminated stubs, crosstalk, poor frequency response, noise, ingress, and egress are issues that have hindered a successful market deployment of phone line based LAN technology. Another shortcoming of the technology is the throughput capability of the system. The current Home PNA standard supports a throughput of 1 Mbps. Contrast the expected transfer rate of 16 Mbps for wireless IR connected systems. In addition to the aforementioned shortcomings of phone line based LAN technology, this technology may have difficulty traversing from home networks into the typical office environment as a significant number of offices are wired in a star topology to support private branch exchange (PBX) telephone systems.
Power Line Networks
Power Line networks are networks established across power lines, such as wiring within the structure of a home or small office. In such networks, data signals are carried (e.g. modulated) over the 60 Hz power signals that are carried on those lines. As is known, certain difficulties and issues exist in these systems. First, a power line is an inherently noisy medium for data transmission, particularly high frequency data transmissions. Another issue that arises in implementing power line networks relates to data security and loss of transmission bandwidth with others on the same side of the power line transformer. One example of a system and method for communicating data over power line, or in-wall, wiring is disclosed in U.S. Pat. No. 6,014,386, which is incorporated herein by reference.
There are various problems or difficulties in implementing power line networks. One problem or shortcoming that is present in prior art systems is the direct coupling of circuit components to the power line. When processing or component circuitry is directly coupled to power lines, then power surges, spikes, and other transients that occur on power lines are directly coupled to the processing or component circuitry. This leads to premature component failure and destruction. This shortcoming is avoided in systems that use “wall warts” to provide the gateway to the power line network. However, such systems generally have an unnecessary duplication of many circuit components. For example, the wall warts include transformers, filters, transient suppression circuitry, and other circuit components that are often present in the switching power supply of computer.
Accordingly, there is a desire for a system and method for providing power line networking that overcomes the problems and shortcomings of the prior art systems.
SUMMARY OF THE INVENTION
Certain objects, advantages and novel features of the invention will be set forth in part in the description that follows and in part will bec
Cao Chun
Globespanvirata, Inc.
Lee Thomas
Thomas Kayden Horstemeyer & Risley
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