Devices and methods employing hermetic transforms for encoding and decoding digital information in spread-spectrum communications systems

摘要

In a direct sequence spread-spectrum (DSSS) systems, such as CDMA, information is encoded in symbols using phase shift keying or quadrature amplitude modulation. Further, a transmitter applied a selected time shifted lag to each symbol to convey additional information. A receiver detects both the symbol data and the lag value. The receiver can use a hermetic matched filter matrix to identify the lag.

主权项

1. A receiver method comprising:
receiving a direct sequence spread spectrum (DSSS) signal with a combination of data symbols and a code; deriving data from the data symbols; determining one of a plurality of different time-shifted lag values of the received code relative to a known reference value; deriving encoded data based on the lag value; outputting data derived from both the data symbols and from the lag value, wherein determining the lag value includes generating a plurality of vectors by shifting an input signal vector by a number N of time samples and applying a transform to produce a transformed signal; and wherein determining the lag value further includes providing the transformed signal to a hermetic matched filter matrix to produce a hermetic matched filtered signal.