1. An operating method of a memory controller configured to control a nonvolatile memory device, the operating method comprising: generating by the memory controller a code word through polar encoding of information bits from an external device; reading by the memory controller a mapping pattern stored within the memory controller; generating by the memory controller a repeated mapping pattern through iteration of the mapping pattern; and mapping by the memory controller each bit of the code word onto a specific bit of multi-bit data of multi-bit cells of the nonvolatile memory device, based upon the repeated mapping pattern.