Optimization of non-binary LDPC coded massive MIMO systems with partial mapping and EP detection

In this work, a non-binary low density parity check (LDPC) coded high dimensional multiple input multiple output (MIMO) scheme with partial mapping for high order modulation is proposed. For the proposed scheme, when $M$ -ary quadrature amplitude modulation (QAM) is employed, then non-binary LDPC code constructed over Galois field with order $\sqrt{M}$ is used for partial mapping, where $\sqrt{M}$ is an integer. At the receiver side, a real-valued expectation propagation (REP) based detection algorithm is used. Furthermore, symbol-wise extrinsic information transfer (SEXIT) chart based iterative optimization algorithm is used to optimize the concatenated non-binary LDPC code. A simplified method is proposed to calculate the component EXIT chart of the massive MIMO detector, which can avoid a large amount of simulations. Numerical simulation results demonstrate the validity of the above idea.