Telecommunications – Radiotelephone system – Zoned or cellular telephone system
Reexamination Certificate
1997-03-31
2001-04-17
Eisenzopf, Reinhard (Department: 2682)
Telecommunications
Radiotelephone system
Zoned or cellular telephone system
C445S060000
Reexamination Certificate
active
06219553
ABSTRACT:
STATEMENT OF FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not Applicable
BACKGROUND OF THE INVENTION
1. Technical Field
This invention relates in general to mobile computing electronic devices and, more particularly, to a method and apparatus for wireless communications between mobile computing electronic devices.
2. Description of the Related Art
Mobile computing electronic devices, such as electronic calculators and portable computers, have evolved significantly in recent years. In addition to arithmetic calculations, current day calculators often provide programming and graphing functions. Graphing calculators include a screen able to display graphics in addition to alphanumeric characters. Portable computers, on the other hand, are progressively becoming more mobile, as the weight of the computer is reduced, while maintaining processing capabilities at the same level as desktop computers.
For some time, graphing calculators and portable computers have been able to communicate to one another through a wired connection. An example of a calculator of this type is the TI-
92
calculator produced by Texas Instruments Incorporated of Dallas, Tex. Wired connections may be used, for example, in a classroom setting where problem sets are downloaded from the teacher's calculator to the students' calculators. Once downloaded, the students can use the calculator to solve the problem. Teacher's can review the student's answers in real-time to determine which students are having difficulty solving the problems.
Portable computers also can communicate through computer networks. Recently, wireless networks have become available for computers. A great advantage of a wireless network is the ability to maintain a network connection within a defined area with a portable computer without losing the mobility of the computer. Wireless networks for graphing calculators have been proposed in U.S. application. Ser. No. 08/706,123 to Siep et al, filed Aug. 30, 1996, entitled “Active Wireless Network For Calculators,” U.S. application. Ser. No. 08/707,165 to Siep et al, filed Aug. 30, 1996, entitled “Passive Wireless Network For Calculators,” U.S. application. Ser. No. 08/697,808 to Siep et al, filed Aug. 30, 1996, entitled “Method of Implementing a Network in a Classroom Setting,” and U.S. application. Ser. No. 08/753,563 to Siep et al, filed Nov. 26, 1996, entitled “Method and Apparatus for Low Power Communications Between Mobile Computing Devices,” all of which are incorporated by reference herein.
Despite the advantages of networks in non-commercial setting such as classrooms, they have not been accepted in widespread use. Wired connections between calculators is somewhat inhibiting to the students. Wireless communications in a classroom or auditorium has several problems. First, in order to have effective communication between the teacher and the students, the student devices must have sufficient battery power to transmit a signal that will reach the teacher's calculator. Unfortunately, designing student devices with enough transmitted power to reach the teacher's desk in a normal sized classroom would deplete the smaller calculator batteries at an unacceptable rate. This is a particular problem with calculators which have relatively small batteries and would, without the wireless communications, last for approximately eight months. Adding wireless communications could decrease the battery life to a single month or less in normal use. Second, it is desirable that the devices operate in a frequency band which is designated as unlicensed by the FCC (Federal Communications Commission). In order to prevent interference between devices operating in an unlicensed frequency band (the ISM—Industrial, Scientific and Medical—band), the FCC has strict guidelines on the spread spectrum modulation schemes which must be used, if the devices broadcast at a power equal or greater than 0.7 milliwatts. Current day wireless transmission devices must exceed this level to accurately communicate over distances up to thirty meters; therefore, they must use a spread spectrum modulation scheme approved by the FCC which increases the complexity, cost and power consumption of the system.
Accordingly, a need has arisen in the industry for a low cost, low power, method and apparatus for communicating between mobile computing electronic devices.
BRIEF SUMMARY OF THE INVENTION
The wireless communications system of the present invention comprises a plurality of mobile computing electronic devices having circuitry for receiving and sending data by wireless communications and a distributed antenna system. The distributed antenna system has one or more segments extending proximate to the mobile computing electronic devices to provide a low loss propagation path for the wireless communication signals.
In a first embodiment of the invention, antenna segments are formed on desks and/or other furniture.
In a second embodiment of the invention, antenna segments are formed on ceiling or floor tiles of the type normally used in an office environment.
The present invention provides significant advantages over the prior art. The power requirement reduction afforded by the distributed antenna system significantly reduces the power used by a portable computer or other mobile computing electronic device to communicate using a wireless transmission. Further, the distributed antenna system eliminates the effect of obstructions between a portable computer and a receiving device which can block communications. Another advantage of the distributed antenna system is that the number of wireless network access points in a computer network can be greatly reduced, since the distance between a mobile computing electronic device and a network access point is effectively the distance between the mobile computing electronic device and the nearest antenna segment, regardless of the physical distance between the access point and the mobile computing electronic device. In classroom situations, the distance between the student calculators and the teacher's calculator can be any length, because the effective distance between the calculators is the distance between the calculators and the nearest antenna segment. For wireless network systems, the design and cost of access points can be greatly reduced due to a simpler modulation/demodulation scheme and, in some instances, dedicated access points can be used to reduce conflicts caused by multiple access in the time and frequency domains.
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Bhattacharya Sam
Eisenzopf Reinhard
Neerings Ronald O.
Telecky , Jr. Frederick J.
Texas Instruments Incorporated
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