Research on blockchain in next-generation communications and networks focuses on leveraging decentralized ledger technology to enhance security, reliability, and efficiency in emerging network paradigms such as 5G, 6G, IoT, and edge computing. Blockchain enables secure authentication, data integrity, and trustless coordination among heterogeneous devices and network nodes, addressing challenges posed by centralized management and potential single points of failure. Smart contracts facilitate automated network resource allocation, spectrum management, and service-level agreements, while consensus mechanisms ensure resilient and tamper-proof operation across distributed network architectures. Additionally, integrating blockchain with network slicing, software-defined networking, and network function virtualization supports scalable, transparent, and accountable communication infrastructures. Overall, blockchain adoption in next-generation networks promises improved trust, resilience, and operational efficiency for complex, large-scale communication systems.