Orthogonal Frequency Division Multiplexing (OFDM) subcarrier spacing is a critical parameter in 5G wireless communication systems, defining the frequency separation between adjacent subcarriers within the OFDM signal. OFDM is the modulation scheme used in 5G to transmit data over the airwaves efficiently.
The subcarrier spacing in 5G is designed to be flexible, allowing operators to choose different values based on specific use cases and deployment scenarios. The subcarrier spacing directly influences the symbol duration and, consequently, the time it takes to transmit data. In 5G, common subcarrier spacings include 15 kHz, 30 kHz, 60 kHz, and 120 kHz.
The choice of subcarrier spacing is associated with trade-offs between spectral efficiency and resilience to channel impairments. Smaller subcarrier spacings result in longer symbol durations, allowing for better frequency selectivity and improved performance in challenging radio environments. On the other hand, larger subcarrier spacings enhance spectral efficiency by enabling higher data rates.
The 5G New Radio (NR) standard defines different numerologies, each characterized by a specific subcarrier spacing and corresponding symbol duration. These numerologies are designed to accommodate diverse use cases, ranging from enhanced mobile broadband (eMBB) with high data rates to ultra-reliable low-latency communication (URLLC) with stringent latency requirements.
The flexibility in OFDM subcarrier spacing is a key feature of 5G, allowing for efficient use of the available spectrum and adaptation to varying deployment scenarios. It enables 5G networks to deliver a wide range of services and applications with diverse performance requirements while optimizing the use of radio resources.