Ali Al- Saihati ID# 200350130

1. King Fahd University of Petroleum & Minerals Electrical Engineering DepartmentEE 578 Simulation of Wireless SystemsOrthogonal Frequency Division Multiplexing Transmission Assignment # 3 Ali Al-Saihati ID# 200350130

2. OUTLINE • Introduction. • OFDM Transmission Scheme. • Guard band. • BER & PER Performance. • Pilot Symbol Aided OFDM. • Frame Format Configuration

3. Introduction • Received signal at the receiver contains reflected waves. • R should be in order of Mb/s for wireless networks. • One way to solve this problem solve this problem is use adaptive equalization at the receiver. • Another way is to use OFDM transmission.

4. OFDM Transmission Scheme • The multipath fading environment in time domain is characterized by impulse responses with different delays an powers. • In frequency domain, it is characterized by attenuation or enhancement of different frequencies of the impulse responses

6. OFDM Transmission • The signal is given by: • The subcarrier is given by:

7. When Bs > Bc, distortion increases but the total received power variation is less. • When Bs < Bc, distortion is little but the total received power is attenuated. • We use parallel transmission to solve this problem. • The high rate is decreased as we multiplex the data while the symbol duration increases.

11. IFFT Circuit

12. Guard Bands • Used to eliminate ISI that appears in the received signal. • Ttotal= Tg + Ts • Tg < Ts/4

14. Results

15. BER & PER Performance Thank You

17. Pilot Symbol Aided OFDM • Compensate for the phase and amplitude fluctuation. • Pilot symbols are inserted in at the transmitter at fixed time interval. • At the receiver, we estimate the channel behavior using the pilot symbols. • Fluctuation is independent of pilot symbols.

18. Frame Format Configuration • Sampling rate: 20 MHz . • Modulation scheme. • FEC: R= ½, K= 7 • Frame format . • Radio channel model.

19. Frame Format Using Channel Estimation

20. BER & PER Performance Using Channel Estimation

22. Thank You