Relationship Curve Between System Capacity and Signal-to-Interference Ratio (SIR)

In OFDM (Orthogonal Frequency Division Multiplexing) systems, there exists a crucial relationship between system capacity and the signal-to-interference ratio (SIR). System capacity refers to the maximum data throughput that the system can transmit, while SIR serves as a key performance metric indicating the quality of the communication link. By studying the relationship curve between system capacity and SIR, we can gain deeper insights into system performance under varying interference conditions. This analysis typically involves implementing Shannon's capacity formula: C = B log₂(1 + SIR), where B represents the bandwidth. In MATLAB simulations, this can be modeled by sweeping SIR values (e.g., from -10 dB to 30 dB) and calculating the corresponding capacity. Key functions would include: - Generating OFDM signals with different modulation schemes (QPSK, 16-QAM) - Adding controlled interference to simulate various SIR conditions - Using spectrum analysis tools to measure actual SIR - Plotting capacity vs. SIR curves with parametric variations Such research is fundamental for optimizing system design parameters, selecting appropriate modulation schemes, and improving overall transmission efficiency in wireless communication systems. The curve typically demonstrates how capacity increases logarithmically with SIR until reaching saturation, highlighting the trade-offs in real-world system implementation.