A multiple description TCQ arrangement employs a trellis graph that is the tensor product, such as T1{circle over (X)}T2, of two trellis graphs, such as T1 and T2. The codevectors of the tensor-product trellis, c1, are incorporated within trellis graph T1 and also within trellis graph T2. The incorporation within trellis graph T1 is effected by assigning the c1 codevectors to sets, and by deriving therefrom codevectors for trellis graphs T1 and T2. The actual values that these codevectors take on are arranged to insure certain distortion results. Specifically, the distortion measure of the tensor-product trellis is minimized, subject to the condition that the distortion measures of approximations made by decoders operating with the T1 and T2 trellises do not exceed a predetermined value. Consequently, an improved arrangement is realized which, two encoders are cooperatively generating separate trellis-coded descriptions of the input sequence. Three different fidelity levels can thus be achieved: a first when only a first description is employed, a second when the second description is employed, and a third (and highest level of fidelity) when both descriptions are employed. This allows for use of receivers that are responsive to different rates, or the use of receivers that have adaptable rates.
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