Effective Utilization of Spectrum for Next Generation Wireless Communication Systems

The earlier idea of the communication system was to focus on modulation and channel coding schemes as separate entities. However, later the perspective of coded modulation was introduced by coding theorists and system designers. In this manuscript, we propose a Low Density Parity Check (LDPC) coded and bit-interleaved precoder, which is added before a 256-Quadrature Amplitude Modulation (QAM) and Reed-Solomon (RS) coded system. This technique significantly enhances the spectral efficiency (measured in bits per two-dimensional symbol) and improves the performance of coded modulation over a fading channel. By bitwise interleaving at the encoder output, the system disperses errors, making them easier to correct, while RS codes provide additional reliability by correcting symbol errors. Consequently, the proposed method boosts both spectral efficiency and overall system reliability, ensuring high data integrity in challenging transmission environments.