Orthogonal Frequency Division Multiplexing (OFDM) in Wireless LAN



Wireless Local Area Networks (WLANs) are commonly used for wireless communication within a limited area, such as homes, offices, or public hotspots. To transmit data wirelessly in a WLAN, various multiplexing techniques can be employed. One of the most widely used multiplexing techniques in WLANs is Orthogonal Frequency Division Multiplexing (OFDM).

1. Introduction to OFDM

OFDM is a digital modulation technique that divides a high-speed data stream into multiple lower-speed substreams, which are then transmitted simultaneously over multiple orthogonal frequency subcarriers. Each subcarrier is modulated with a portion of the data, and all subcarriers are transmitted in parallel. This technique allows for efficient and reliable data transmission over wireless channels.

2. Advantages of OFDM in WLANs

- Interference Management: OFDM is particularly effective in managing interference caused by multipath propagation and other signal impairments. By dividing the data into multiple subcarriers, OFDM can mitigate the effects of multipath fading and improve the overall signal quality.

- Increased Data Throughput: OFDM allows for higher data rates by dividing the available frequency spectrum into smaller subcarriers. Each subcarrier can carry a lower-speed data stream, resulting in a higher overall data capacity.

- Robustness: OFDM is resilient to multipath fading and narrowband interference. By using a guard interval between symbols, OFDM can effectively combat intersymbol interference and maintain data integrity even in challenging wireless environments.

3. Comparison with other Multiplexing Techniques

a) Time Division Multiplexing (TDM): TDM divides the available time slots among users, allowing each user to transmit data during their allocated time slot. However, TDM is not efficient for high-speed data transmission and is more suitable for voice or low-rate data applications.

b) Space Division Multiplexing (SDM): SDM uses multiple antennas to transmit different data streams simultaneously. While SDM can provide high data rates, it requires multiple antennas and complex signal processing techniques, making it less practical for WLANs.

Conclusion

In conclusion, OFDM is the preferred multiplexing technique for wireless LANs due to its ability to manage interference, increase data throughput, and provide robustness in wireless environments. OFDM divides the data stream into multiple subcarriers and allows simultaneous transmission, resulting in efficient and reliable wireless communication.