finite-group-markov-noise-channel

Finite-group additive channel with Markov noise

Stationary irreducible aperiodic Markov noise subtracts its entropy rate from the group alphabet rate.

Point-to-point Finite alphabet Memory Additive noise Capacity Exact

Channel and question

Input
Elements of a fixed nonempty finite abelian group.
Output
An element of the same group at each time.
Law
Y_t=X_t+S_t. The noise state then transitions according to a fixed Markov kernel K.
Quantity
Finite-group additive channel with Markov noise capacity \(C\), measured in bits per channel use.

Criterion. Vanishing average block error, with the constraints specified in the model.

  • The initial noise law p is stationary for K.
  • K is primitive: all entries of every sufficiently large power are strictly positive.
  • The noise process is independent of the message. Neither terminal observes the state.
  • There is no feedback and no input cost constraint.

Current status

\[C=\log_2|G|-\sum_s p(s)H(K(\cdot\mid s))\]
Known results and bounds for Finite-group additive channel with Markov noise
ResultRelationMethodYear
Exact\(C=\log_2|G|-\sum_s p(s)H(K(\cdot\mid s))\)Additive-noise information-rate coding and an entropy-rate converse.1995

Formal verification

Lean coverageFormally stated

Concrete operational definitions and admitted research statements are present. Existing proofs are preserved. New statements require mathematical review and proof completion.

Claims

  • Stationary primitive Markov additive noise subtracts its entropy rate from log alphabet size.
    operational-capacity · exact capacity · solved · Formally stated · v2
Lean declarations (1)

References

  1. Fady Alajaji (1995). Feedback Does Not Increase the Capacity of Discrete Channels with Additive Noise. IEEE Transactions on Information Theory. DOI 10.1109/18.370168.

Discussion

Related problems

Noiseless output feedback improves reliability without changing AWGN capacity.

Point-to-point Continuous alphabet Gaussian Additive noise Feedback Power constraint Capacity Exact
Solved \(C_{\mathrm{AWGN,fb}}=\frac12\log_2\!\left(1+\frac PN\right)\)
Binary Z-channel Z-channel

One binary symbol is transmitted perfectly while the other can flip in only one direction.

Point-to-point Binary Finite alphabet Discrete memoryless Asymmetric Capacity Exact
Solved \(C_Z(p)=\log_2\!\left(1+(1-p)p^{p/(1-p)}\right)\)

Each transmitted bit is received correctly or replaced by a visible erasure symbol.

Point-to-point Binary Finite alphabet Discrete memoryless Symmetric Erasure Capacity Exact
Solved \(C_{\mathrm{BEC}}(\varepsilon)=1-\varepsilon\)

Independent stuck-at defects are known noncausally to the encoder but not the decoder.

Point-to-point Binary Finite alphabet Discrete memoryless Noncausal state information Capacity Exact
Solved \(C=1-\delta\)