Capacity Enhancement in K shaped Sphere Decoders for various QAM Modulations

The main aim of the physical layer is to boost the data rates over wireless channel with better quality of services (QOS), thereby, increasing the efficiency and reliability of new generation wireless communication systems especially 5G/6G system. Performance of various space time block codes like quasi orthogonal space time block codes and rotational quasi orthogonal space time block codes is investigated using various decoding algorithms like Sphere Decoder, K 1, K 2, K 3, K 4 Sphere decoders. The Sphere Decoder has been modified in terms of K detection algorithms based on spectral efficiency. Different modulations are used to validate the analytic analysis. Simulations are performed in MATLAB software and the results obtained shows the significant incremented spectral efficiency.