Differential transmitter diversity technique for wireless communications
View Patent ↗Input signals of each frame are encoded by mapping the signals onto a coordinate system dictated by the symbols of the previous frame, and symbols from a constellation are selected based on the results of such mapping. Received signals are detected by preprocessing the signals detected at each antenna with signals detected by the antenna at the immediately previous frame, and then applied to a maximum likelihood detector circuit, followed by an inverse mapping circuit.
1. A receiver comprising:
a plurality of receiving elements, each responsive to a respective applied signal and developing two output signals;
a minimum distance decoding element responsive to the output signals of all of the plurality of receiving elements; and
a post processing element responsive to output signals of the minimum distance decoding element;
where each of the receiving elements includes a delay element and two dot product elements for developing said two output signals of the receiving elements, with the delay element and the two dot product elements receiving said respective applied signal as an input, and the two dot product elements also receiving an output signal of the delay element as another input.
2. The receiver of claim 1 where each the dot product element operate on frames of signals r, and each dot product element develops the product (r 2q+1 ,r 2q+2 • )·(r 2q−1 ,r 2q • ) where r j is the signal of frame j, r j • is the complex conjugate of r j , where j is 2q−1, 2q, 2q+1 and 2q+2.