1. 1 Lab. 13 SISO Wireless System I  In a typical communication system, receiving starts with synchronization.  For a packet-based system, it includes – Packet detection – Carrier frequency offset (CFO) estimation – Symbol timing  To recovery the transmit data, we also need – Equalization  To facilitate the operations, preambles are added before the payload data.  We will consider a packet-based wireless system with flat- fading channel.

2. 2  Define the packet with the following format :  Preamble: – Each packet has 5 short preambles and 1 long preamble. – Packet format : – Short preamble Length = 16 samples (for packet detection and CFO estimation) – Long preamble Length = 32 samples (for symbol timing and channel estimation) SSSSSLData S : short preamble L : long preamble

3. 3  Transmitter: Digital mod. Add preamble Up- sampling Pulse shaping PC FPGADAC EMIF RF Ethernet

4.  Practice 1: – Implement the four modules of the transmitter in Matlab to observe each input/output signal. – Cascade the four modules and observe the input/output signal. – Practice 2: – Implement the four modules with C. – Run the DSP to see if the output signal matches the Matlab result (to/from PC). 4 Digital mod. Add preamble Up- sampling Pulse shaping PC Ethernet

5. Chapter -5  Receiver: EMIF ADCFPGA Packet detection CFO Est./comp. RF Symbol timing Matching/ down sam. Channel est./Equal DetectionPC Ethernet SR OSRSR SR: symbol rate OSR: oversampled rate

6. 6  Packet detection: – Calculate autocorrelation of the received signal – Normalize with the signal power: – Decision statistic: – If m(n) exceeds a threshold, a packet is claimed detected.

7. Chapter -7  Example: – D=16 、 L=16 – Threshold= 0.7 Threshold

8.  Carrier frequency offset (CFO) estimation: – The oscillator frequencies of Tx and Rx are not the same in general. – The downconverted signal:  Then,  Compensation: 8

9.  Symbol timing: – Cross-correlation of received signal and a known reference signal (preamble) – Example: 9 t(k): a known reference signal

10.  Practice 3: – Implement the three modules in the receiver with Matlab. – Observe each input/output signal. – Cascade the three modules and observe the input/output signal.  Practice 4: – Implement the three modules with C and run the DSP to see the result is the same as that with Matlab. 10