On-chip implementation of memory mapping algorithm to support flexible decoder architecture

Parallel hardware architectures are used to design turbo-like iterative decoders to meet the requirement of high data rate applications. However, parallel architectures suffer from memory conflict problem due to interleaving law used in turbo-like codes. To solve conflict problem, different memory mapping approaches have been developed. These methods automatically generate a set of control words stored in ROM to drive the architecture. These approaches are used off-chip by the designer (i.e. prior the decoder implementation) to generate different set of control words i.e. one set for each block length used in the target telecommunication standard. This requires multiple ROMs to store mapping information for multiple block lengths and results in huge hardware cost. In this article, we propose to embed memory mapping algorithms on-chip. Hence, each time word-length changes, memory mapping algorithm is executed. Command words are thus generated at runtime and stored in a RAM. This is a first attempt to embed mapping algorithms on chip and experimental results show that a significant amount of memory can be saved by using on-chip execution of mapping algorithms. Results also highlight that improvement in design and implementation of mapping algorithms are still needed to embed mapping algorithms on-chip to implement flexible decoder architectures.