  Due to the ability to provide superior error-correction performance, the
successive cancellation list (SCL) algorithm is widely regarded as one of the
most promising decoding algorithms for polar codes with short-to-moderate code
lengths. However, the application of SCL decoding in low-latency communication
scenarios is limited due to its sequential nature. To reduce the decoding
latency, developing tailored fast and efficient list decoding algorithms of
specific polar substituent codes (special nodes) is a promising solution.
Recently, fast list decoding algorithms are proposed by considering special
nodes with low code rates. Aiming to further speedup the SCL decoding, this
paper presents fast list decoding algorithms for two types of high-rate special
nodes, namely single-parity-check (SPC) nodes and sequence rate one or
single-parity-check (SR1/SPC) nodes. In particular, we develop two classes of
fast list decoding algorithms for these nodes, where the first class uses a
sequential decoding procedure to yield decoding latency that is linear with the
list size, and the second further parallelizes the decoding process by
pre-determining the redundant candidate paths offline. Simulation results show
that the proposed list decoding algorithms are able to achieve up to 70.7\%
lower decoding latency than state-of-the-art fast SCL decoders, while
exhibiting the same error-correction performance.
