Maximum a Posteriori Decoding of Arithmetic Codes in Joint Source-Channel Coding

An Effective Error Correction Scheme for Arithmetic Coding

“…As shown in Figure 4(c), the forecasted forbidden region is much larger than that in Figure 3, which obviously improves the error correcting capability. On the other hand, the look-ahead technique [26] usually employed in AC decoders can detect forbidden symbol quickly by decoding the source symbol even when the decoding interval bounds +1 and +1 are located in the encoding intervals for a particular source symbol and the forbidden region by assuming that it is error-free. An example of which is given in Figure 5, where the source symbol "1" is decoded in Figure 5(a) and then the forbidden symbol can be detected in Figure 5(b).…”

“…In this section, the proposed scheme is compared with the original MAP scheme [10] and the look-ahead scheme [26]. Binary source symbols with 0 = 0.8667 are randomly generated, which correspond to the memoryless source entropy = 0.567.…”

“…As the original MAP scheme [10] has already been shown to have a better error correction performance than the traditional separated source and channel coding scheme, a comparison with the latter scheme is not repeated here. As the placement of the forbidden symbol can affect the error correction performance [26,29], two placements are considered in our simulations, which are identified with source models A and B in Figures 7(a) Algorithm 3: Pseudocode of the modified decoder for error detection using forecasted forbidden symbols. the compared schemes is evaluated by the packet error rate (PER).…”

“…Here, the procedures of AC with forecasted forbidden symbols are described in detail. More analyses and simulation results are provided to justify that the proposed scheme outperforms the look-ahead scheme [26] and the original MAP scheme [10] on the error correction performance, especially at a low coding rate.…”

“…A sequential MAP estimation for CABAC coder was proposed in [25], which employs an improved sequential decoding technique to determine the tradeoff between complexity and efficiency. In [26], a look-ahead technique for AC decoder was proposed to allow quick error detection. Considering the improvement in the implementation efficiency, AC can be modeled as a finite-state machine corresponding to a variable-length trellis code.…”