Enhancing Inter-Symbol Interference (ISI) and Co-Channel Interference Suppression Using Adaptive Arrays

In digital mobile communication systems, adaptive array technology is widely employed for interference suppression. However, traditional adaptive array processing exhibits limitations when addressing both Inter-Symbol Interference (ISI) and co-channel interference. The solution proposed in this paper introduces subband filter bank processing to effectively overcome these challenges. ISI primarily arises from multipath propagation causing signal overlap in the time domain, while co-channel interference originates from signal sources sharing the same frequency band. Conventional wideband processing methods often struggle to simultaneously address both types of interference effectively. By implementing subband filter bank technology, the system decomposes received signals into multiple narrower subbands for independent processing. A key advantage of this frequency-domain partitioning approach is its ability to enhance correlation among signals received by different array elements. Within narrower subbands, signal correlation increases, enabling adaptive array algorithms to more accurately distinguish desired signals from interference. Additionally, subband decomposition better matches frequency-selective fading characteristics across different array elements. For ISI suppression, subband processing enables more effective equalization of channel responses within individual subbands, reducing inter-symbol interference. Co-channel interference suppression benefits from clearer signal separation at the subband level. Implementation of this method requires careful consideration of subband partitioning strategies and filter bank design optimization to ensure performance improvements without introducing excessive computational complexity. The practical implementation typically involves designing a polyphase filter bank structure with efficient FFT-based processing. Key algorithm components include: - Subband decomposition using analysis filter banks - Independent adaptive beamforming per subband - Synthesis filter banks for signal reconstruction This technology shows promising applications in digital mobile communication environments, particularly in high-density user scenarios and complex propagation conditions, where it can significantly enhance system interference resistance and spectral efficiency.