Soft decision method and receiver
First Claim
1. A soft decision method, wherein bits having equal values for at least one symbol, which is used in a transmission system based on multilevel (amplitude and/or phase) modulation subjected to mapping with gray encoding, and serves as a candidate of a correct symbol determined by that region of signal space in which a received symbol is located, are subjected to soft decision in units of one bit, and one of a minimum value and maximum value is selected for each of the bits in the soft decision, thereby determining said one of the minimum and maximum values as the value of said each bit, and bits having different values for the symbol are subjected to soft decision.
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Accused Products
Abstract
When the received symbol is located (FIG. 4) within one of regions G, H, I, L, M, N, Q, R, and S, 2 bits are decided to be most reliable to obtain their soft decision values=0 or 7. As for the remaining 2 bits, a soft decision value=0 to 7 is decided by soft decision in the I- or Q-axis direction. When the received symbol is located within one of regions A, E, U, and Y, all the 4 bits are decided to obtain their soft decision values=0 or 7. When the received symbol is located with one of regions B, C, D, F, J, K, 0, P, T, V, W, and X, 3 bits are decided to be most reliable to obtain their soft decision values=0 or 7. As for the remaining 1 bit, a soft decision value=0 to 7 is obtained by soft decision in the I- or Q-axis direction. A soft decision method that can implement soft decision in multilevel (amplitude and/or phase) modulation and can fully exhibit the correction performance of maximum likelihood coding can be provided.
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Citations
8 Claims
- 1. A soft decision method, wherein bits having equal values for at least one symbol, which is used in a transmission system based on multilevel (amplitude and/or phase) modulation subjected to mapping with gray encoding, and serves as a candidate of a correct symbol determined by that region of signal space in which a received symbol is located, are subjected to soft decision in units of one bit, and one of a minimum value and maximum value is selected for each of the bits in the soft decision, thereby determining said one of the minimum and maximum values as the value of said each bit, and bits having different values for the symbol are subjected to soft decision.
Specification