Browse Prior Art Database

High Data Rate Direct Sequence Modulation

IP.com Disclosure Number: IPCOM000117968D
Original Publication Date: 1996-Jul-01
Included in the Prior Art Database: 2005-Mar-31
Document File: 2 page(s) / 41K

Publishing Venue

IBM

Related People

Camp Jr, WO: AUTHOR

Abstract

It is common for there to exist regulations to control the amount of bandwidth that one may utilize at any given time to transmit data. Additional regulations often specify minimum performance parameters. In the case of part 15 FCC regulations for the 2.4 GHz band, a combination of the requirement for a spreading sequence at least 10 chips long and the need to fit within the band with a reasonable number of channels, forces one to limit the data rate to 4 megabits per second.

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This is the abbreviated version, containing approximately 53% of the total text.

High Data Rate Direct Sequence Modulation

      It is common for there to exist regulations to control the
amount of bandwidth that one may utilize at any given time to
transmit data.  Additional regulations often specify minimum
performance parameters.  In the case of part 15 FCC regulations for
the 2.4 GHz band, a combination of the requirement for a spreading
sequence at least 10 chips long and the need to fit within the band
with a reasonable number of channels, forces one to limit the data
rate to 4 megabits per second.

      Normal operation is that a 10 chip long sequence is used to
signify a 1 and its inverse used for the 0.  Our proposal is to use
multiple 10 (or longer) chip sequences to send not just a 1 or 0, but
to send a 0, or a 1, or a 2, or ...  a n.  The number of bits per
second is now increased by log(base 2) n.  The method of decoding
this modulation is to use parallel searching for the n different 10
chip sequences.  This is shown below:
  CHIP STREAM -->   Shift register 1 bit wide by 10 bits long
                    |   |   |   |   |   |   |   |   |   |
                    |   |   |   |   |   |   |   |   |   |
                    x + x + x + x + x + x + x + x + x + x = >
Majority
                    |   |   |   |   |   |   |   |   |   |
                    x + x + x + x + x + x + x + x...