1：Experimental Design and Method Selection:

The study designs a two-hop cooperative network with multiple decode-and-forward (DF) relays. It employs OFDM-IM for modulation, per-subcarrier relay selection based on channel state information (CSI), and maximum-likelihood (ML) detection at relays and destination. The methodology includes theoretical modeling of channel gains, signal propagation, and error analysis using approximations like the Gaussian tail function.

2：Sample Selection and Data Sources:

Simulations use Monte Carlo methods with normalized average channel gains (μ1 = μ2 = 1). Data is generated based on Rayleigh fading channels and equiprobable bit streams.

3：1). Data is generated based on Rayleigh fading channels and equiprobable bit streams. List of Experimental Equipment and Materials:

3. List of Experimental Equipment and Materials: The paper does not specify physical equipment; it is a theoretical and simulation-based study. Assumed components include OFDM transmitters, relays, receivers, and computational tools for simulations.

4：Experimental Procedures and Operational Workflow:

The process involves mapping bit streams to OFDM blocks, performing per-subcarrier relay selection, transmitting signals over two hops with DF relaying, receiving and reconstructing OFDM blocks at the destination, and analyzing error rates and capacity through numerical simulations.

5：Data Analysis Methods:

Analysis includes deriving closed-form expressions for average block error rate (BLER) and modulation capacity, using statistical methods, binomial expansions, and approximations. Numerical results are verified via Monte Carlo simulations.