  With the rapid increase of available digital data, DNA storage is identified
as a storage media with high density and capability of long-term preservation,
especially for archival storage systems. However, the encoding density (i.e.,
how many binary bits can be encoded into one nucleotide) and error handling are
two major factors intertwined in DNA storage. Considering encoding density,
theoretically, one nucleotide can encode two binary bits (upper bound).
However, due to biochemical constraints and other necessary information
associated with payload, the encoding densities of various DNA storage systems
are much less than this upper bound. Additionally, all existing studies of DNA
encoding schemes are based on static analysis and really lack the awareness of
dynamically changed digital patterns. Therefore, the gap between the static
encoding and dynamic binary patterns prevents achieving a higher encoding
density for DNA storage systems.
  In this paper, we propose a new Digital Pattern-Aware DNA storage system,
called DP-DNA, which can efficiently store digital data in DNA storage with
high encoding density. DP-DNA maintains a set of encoding codes and uses a
digital pattern-aware code (DPAC) to analyze the patterns of a binary sequence
for a DNA strand and selects an appropriate code for encoding the binary
sequence to achieve a high encoding density. An additional encoding field is
added to the DNA encoding format, which can distinguish the encoding scheme
used for those DNA strands, and thus we can decode DNA data back to its
original digital data. Moreover, to further improve the encoding density, a
variable-length scheme is proposed to increase the feasibility of the coding
scheme with a high encoding density. Finally, the experimental results indicate
that the proposed DP-DNA achieves up to 103.5% higher encoding densities than
prior work.
