Space-Time Codes for Linearly Labelled PAM, PSK, QAM and Related Constellations Using Gray Mapping
AssigneeThe Johns Hopkins University
InventorArthur Hammons
Life of this patent
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Abstract
General algebraic space-time code constructions are presented for Gray-mapped 2K-PSK, 2K-PAM, and 4K-QAM constellations. The space-time codes achieve the rate-diversity tradeoff—i.e., they allow the transmission of information at the maximum rate possible for the given signaling constellation and the achieved transmit diversity level. New codes created by applying a nonsingular linear or affine transformation to the constellation labels retain the optimality of the original codes with respect to the rate-diversity tradeoff. Extensions to pK-PSK, pK-PAM, p2K-QAM, and related constellations, for p prime, are also given.
Claims23
A system of space-time coding for a radio system utilizing M transmit antennas and T symbol intervals, where M and T are integers satisfying 2≦M≦T, said system comprising:
- a) a digital signaling constellation with pm constellation points, with p a prime integer and m ≧2 a positive integer;
- b) means for selecting the points in the digital signaling constellation via an address;
- c) means for computing a constellation point address from a vector of p-ary symbols of length m;
- d) transforming means that maps vectors of m p-ary symbols to transformed vectors of m p-ary symbols;
- e) at least one constituent p-ary code, each said constituent p-ary code being used to map sequences of source symbols to sequences of coded symbols;
- f) means for combining m p-ary code words from the constituent p-ary code to form a multi-level code word comprising pm-ary coded symbols from the pm-ary signaling constellation, said combining comprising taking an initial p-ary symbol from each of the m code words as a vector of length m, transforming the vector via the transforming means to produce a transformed vector, computing an address from the transformed vector via the address computation means, using the address to select a constellation point in accordance with the selection means, and repeating these steps for each of the next sets of p-ary symbols from the m code words;
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- g) means for distributing the pm-ary coded symbols among the M transmit antennas and T symbol intervals for transmission.
A computer-implemented method of space-time coding for a radio system utilizing M transmit antennas and T symbol intervals, where M and T are integers satisfying 2≦M ≦T, said method comprising:
- a) creating a digital signaling constellation with pm constellation points, with p a prime integer and m ≧2 a positive integer;
- b) selecting the points in the digital signaling constellation via an address;
- c) computing a constellation point address from a vector of p-ary symbols of length m;
- d) transforming means that maps vectors of m p-ary symbols to transformed vectors of m p-ary symbols;
- e) creating at least one constituent p-ary code, each said constituent p-ary code being used to map sequences of source symbols to sequences of coded symbols;
- f) combining m p-ary code words from the constituent p-ary code to form a multi-level code word comprising pm-ary coded symbols from the pm-ary signaling constellation, said combining comprising taking an initial p-ary symbol from each of the m code words as a vector of length m, transforming the vector via the transforming step to produce a transformed vector, computing an address from the transformed vector via the address computation step, using the address to select a constellation point in accordance with the selection means, and repeating these steps for each of the next sets of p-ary symbols from the m code words;
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- g) distributing the pm-ary coded symbols among the M transmit antennas and T symbol intervals for transmission.
A computer program product for space-time coding for a radio system utilizing M transmit antennas and T symbol intervals, where M and T are integers satisfying 2 ≦M ≦T, the computer program product comprising a computer-readable storage medium having computer-readable program code embodied in the medium, the computer-readable program code comprising:
- a) computer-readable program code that creates a digital signaling constellation with pm constellation points, with p a prime integer and m ≧2 a positive integer;
- b) computer-readable program code that selects the points in the digital signaling constellation via an address;
- c) computer-readable program code that computes a constellation point address from a vector of p-ary symbols of length m;
- d) computer-readable program code that transforms means that maps vectors of m p-ary symbols to transformed vectors of m p-ary symbols;
- e) computer-readable program code that generates at least one constituent p-ary code, each said constituent p-ary code being used to map sequences of source symbols to sequences of coded symbols;
- f) computer-readable program code that combines m p-ary code words from the constituent p-ary code to form a multi-level code word comprising p -ary coded symbols from the p -ary signaling constellation, said combining comprising computer-readable program code that takes an initial p-ary symbol from each of the m code words as a vector of length m, transforms the vector via the trans-forming means to produce a transformed vector, computes an address from the transformed vector via the address computation means, uses the address to select a constellation point in accordance with the selection means, and repeats these steps for each of the next sets of p-ary symbols from the m code words;
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- g) computer-readable program code that distributes the pm-ary coded symbols among the M transmit antennas and T symbol intervals for transmission.
Dependencies are inferred from the claim text.