Pulse or digital communications – Receivers – Interference or noise reduction
Reexamination Certificate
2000-04-18
2004-09-07
Chin, Stephen (Department: 2634)
Pulse or digital communications
Receivers
Interference or noise reduction
Reexamination Certificate
active
06788751
ABSTRACT:
BACKGROUND
The field of the invention relates generally to digital wireless communication, and more specifically, the transmission of digital audio and video data by means of a wireless connection.
Conventional methods of transmitting data place digital data in the form of QAM, QPSK, FSK or other coding scheme within a frequency band. The higher the data rate, the wider the bandwidth of the frequency band. Relatively, wide bands have the problem of frequency selective multipath fading and in-band interference. To avoid this problem, many systems utilize spread spectrum frequency hopping or direct sequence techniques. Spread spectrum schemes are effective, but require a large processing gain and therefore are limited as to data through-put. They are also too expensive for many high data rate consumer applications.
Therefore, what is needed is an invention that is an inexpensive alternative to transmit wireless digital audio and video data. Also what is needed is an invention that can transmit the wireless data and not be unduly limited as to data through-put.
SUMMARY
In contrast to the prior art, the present invention provides an inexpensive method for transmitting wireless digital audio and video data, while maintaining a high data through-put. To this end, in one embodiment the method utilizes a plurality of relatively narrow bands as opposed to one wider one. This minimizes the negative impact of frequency selective multipath fading and in-band interference. The serial data bits are divided by some predetermined pattern among the frequency bands providing frequency diversity. As one or more of the bands are lost to multipath fading or interference, the interpolated signals of the remaining bands are used.
An inexpensive implementation can use multiple averaging interpolators on each band to be summed or selected in a multiplexer to give the output signal.
A second implementation can have the data output of all bands applied to an interpolation filter curve in a Digital Signal Processor (DSP). An interpolation filter allows part of the received data to be lost without great harm because one can fall back to interpolation of the “good” data.
Therefore, in accordance with the previous summary, objects, features and advantages of the present invention will become apparent to one skilled in the art from the subsequent description and the appended claims taken in conjunction with the accompanying drawings.
REFERENCES:
patent: 5214678 (1993-05-01), Rault et al.
patent: 5485215 (1996-01-01), Meyer et al.
patent: 5544167 (1996-08-01), Lucas et al.
patent: 5960032 (1999-09-01), Letaief et al.
Hustig Charles H.
Moses Donald W.
Haynes and Boone LLP
Moses Donald W.
Williams Lawrence
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