COFDM (Coded Orthogonal Frequency Division Multiplexing) is a digital modulation technique widely used in various communication systems. It is primarily used in applications where reliable transmission of data over wireless channels is essential. Here are some common uses and purposes of COFDM:

1. Digital Television Broadcasting: COFDM is extensively used for terrestrial digital television broadcasting, including the popular DVB-T and DVB-T2 standards. It enables efficient transmission of video, audio, and data streams over the airwaves, providing high-quality reception even in challenging environments with multipath interference, such as urban areas.
2. Wireless Communication Systems: COFDM is employed in wireless communication systems, especially in situations where robustness against signal fading and interference is crucial. It is commonly used in wireless local area networks (WLANs) and wireless audio and video transmission systems, ensuring reliable data transfer in environments prone to multipath fading and interference.
3. Public Safety and Emergency Services: COFDM finds extensive usage in public safety and emergency communication systems. It offers robustness against multipath fading and interference, making it suitable for applications such as police and fire department communication, search and rescue operations, and disaster response scenarios.
4. Unmanned Aerial Vehicles (UAVs): COFDM is utilized in UAV communication systems, enabling reliable and high-bandwidth data links between the ground control station and the unmanned aircraft. It ensures stable transmission of video feeds, control signals, and other telemetry data, facilitating efficient operation and control of the UAV.
5. Wireless Surveillance Systems: COFDM is employed in wireless video surveillance systems, providing secure and high-quality video transmission over wireless links. It allows for real-time monitoring and recording of surveillance footage in various environments, including urban areas and challenging terrains.

The primary purpose of COFDM is to enhance the reliability and robustness of data transmission over wireless channels. By dividing the data stream into multiple orthogonal subcarriers and incorporating error correction coding, COFDM can combat multipath fading, interference, and other channel impairments. It enables the delivery of high-quality data, audio, and video with minimal transmission errors, even in challenging wireless environments.