Changes between Version 2 and Version 3 of WARPLab/Examples/OFDM

Timestamp:

Feb 21, 2014, 11:24:42 AM (10 years ago)

Author:

murphpo

Comment:

--

WARPLab/Examples/OFDM

@@ -41 +41 @@
 ||  [[Image(wl_ofdm_plots_sim_chanEst.png,nolink)]] [[BR]]Channel estimate per subcarrier (I/Q components and complex magnitude)  ||  [[Image(wl_ofdm_plots_sim_phaseError.png,nolink)]] [[BR]]Phase error per OFDM symbol based on pilot tones  ||  [[Image(wl_ofdm_plots_sim_constellations.png,nolink)]] [[BR]]Tx and Rx constellations  ||
 
+By default the simulation script applies AWGN with an arbitrary fixed SNR. You can change the simulated propagation characteristics in the m-code. Search for {{{AWGN}}} and apply whatever Tx->Rx degradations you like.
+
+For example to simulate a perfect (noiseless) link, set the noise power to zero:
+[{{
+rx_vec_air = tx_vec_air + 0*complex(randn(1,length(tx_vec_air)), randn(1,length(tx_vec_air)));
+}}}
+
+The script also prints statistics about the experiment to the MATLAB command prompt:
+{{{
+Results:
+Num Bytes:  4560
+Sym Errors:  0 (of 9120 total symbols)
+Bit Errors:  0 (of 36480 total bits)
+EVM:        3.912%
+LTS CFO Est: -0.26 kHz
+}}}
+
+
+=== Hardware in the Loop ===
+To use the example with WARP hardware you will need two WARP nodes each running WARPLab 7.3 (or later) and a WARPLab environment setup on your PC. Refer to the [wiki:../QuickStart WARPLab Quick Start] if you have not yet setup WARPLab.
+
+To target WARP hardware set the top-level param {{{USE_WARPLAB_TXRX = 1;}}}, then run the m-script. When the script finishes 6 plots will show:
+
+
+||  [[Image(wl_ofdm_plots_sim_txIQ.png,nolink)]][[BR]]Transmitted waveform  ||  [[Image(wl_ofdm_plots_sim_rxIQ.png,nolink)]] [[BR]]Received waveform  ||  [[Image(wl_ofdm_plots_sim_ltsCorr.png,nolink)]] [[BR]]Preamble correlation results (peaks indicate locations of preamble LTS)  ||
+||  [[Image(wl_ofdm_plots_sim_chanEst.png,nolink)]] [[BR]]Channel estimate per subcarrier (I/Q components and complex magnitude)  ||  [[Image(wl_ofdm_plots_sim_phaseError.png,nolink)]] [[BR]]Phase error per OFDM symbol based on pilot tones  ||  [[Image(wl_ofdm_plots_sim_constellations.png,nolink)]] [[BR]]Tx and Rx constellations  ||
+
 == Limitations ==
 This example is intended as a staring point for researchers wishing to use WARPLab to prototype a wireless communications link. This examples does not implement some some blocks common in deployed OFDM systems, such as scrambling, interleaving and error correcting coding. For an example of a real-time OFDM implementation that implements all of these subsystems, please see the PHY in the [wiki:802.11 802.11 Reference Design].