What is REM Radio Environment Map

The technical details of the Radio Environment Map (REM).

1. Definition and Purpose:
   • A REM is a comprehensive wireless cognitive network map that represents the spatial distribution of various radio parameters within a given environment . These parameters include:
     • Geographic information data.
     • Radio device parameters.
     • Radio propagation models.
     • Spectrum data.
2. Functionality and Applications:
   • The REM serves several purposes in wireless communications:
     • Spectrum Management: It provides reliable and adequate knowledge of crowd sensing devices, allowing efficient spectrum monitoring and management.
     • Opportunistic Access: By understanding the radio environment, devices can opportunistically access available spectrum.
     • Interference-Free Routing: The REM helps route signals through interference-free channels.
     • Mobile Network Relaying: It aids in optimizing mobile network relaying.
3. Challenges and Updates:
   • As the wireless environment changes due to an increasing number of mobile devices, REM updates become crucial.
   • Traditional update methods rely on data collection without considering whether the wireless environment has changed significantly.
   • Frequent REM updates waste computational resources when the environment remains stable, while delayed updates reduce REM accuracy during significant changes.
4. Proposed Update Mechanism:
   • To address these challenges, a novel update mechanism combines the following techniques:
     • Siamese Neural Network: Inspired by computer vision, this network compares newly collected crowdsourced data with the existing REM to measure similarity.
     • Attention Mechanism: An attention mechanism further refines the update decision based on the amount of wireless environmental change.
     • Controlled Update: By setting a similarity threshold, the algorithm achieves controlled REM updates with good controllability.
5. Simulation and Effectiveness:
   • The proposed algorithm effectively detects changes in the wireless environment, as demonstrated through simulation data .