Improved radius selection in sphere decoder for MIMO System

The MLD (Maximum-likelihood decoding) of a particular random code over an AWGN (additive white Gaussian noise) channel requires an exhaustive search over all the possible code-word, and so the computational complexity of the optimal decoding scheme is exponential in the length of the code-word. A new type of the detection technique called the sphere decoding algorithm is proposed to lower the computational complexity. The principle of the sphere decoding algorithm is to search the closest lattice point to the received signal within a sphere radius, where every codeword is represented by a lattice point in a lattice field.