Low complexity encoding of M-ary QAM constellation for linear index codes

An index coding problem consists of a single source S with K messages transmitted across a Gaussian broadcast channel, where each receiver demands a set of information from the source while having a subset of prior information in its cache, known as 'side information'. The power of the receiver which efficiently exploits receivers' side information is called the 'side information coding gain'. The known index codes have the heaviest quantity of side information gain, but finding the encoding matrix is a tedious process. This presented work aims to find the encoding matrix to construct the multidimensional Quadrature Amplitude Modulation (QAM) constellation proposed by Natarajan et al. (2015a), with a fewer number of computer searches. Furthermore, the side information gain achieved is compared with the existing method.