SOURCEFORGE » RALF » 2015 SDR for rapid prototyping of radio communications

h1. Results

When the communication between the USRPs was established, the transmitted constellation below was obtained.

p=. !{width: 60%}https://sourceforge.isae.fr/attachments/download/1513/Tx_Constellation.png(Transmitted Constellation)!

_Figure 2.2 Transmitted Constellation_

Using an IQ sampling of 500k, obtaining a symbol rate of 62500 symbols/sec, without any noise, the received constellation is shown below. The BER in this case is, evidently, 0.

p=. !{width: 60%}https://sourceforge.isae.fr/attachments/download/1511/Rx_Constellation_no_noise.png(Received Constellation)!

_Figure 2.2 Received Constellation without AWGN_

The constellation on figure 11 was obtained when adding AWGN, for a target $E_b/N_0$ (received $E_b/N_0$) of 5.The constellation will vary as the values of $E_b/N_0$ vary, making it either noisier, or making it resemble a noiseless channel.

p=. !{width: 60%}https://sourceforge.isae.fr/attachments/download/1512/Rx%20_Constellation_AWGN.png(Noisy Constellation)!

_Figure 2.3 Noisy Constellation_

With AWGN, the $BER$ is calculated, then compared to the theoretical one, obtaining a $BER$ vs $E_b/N_0$ graph like the one depicted below in figure 12. It can be seen that the simulated $BER$ follows, as expected, the same behavior as the theoretical $BER$.

p=. !{width: 30%}https://sourceforge.isae.fr/attachments/download/1300/sdr-ideal_real.jpg(Theroretical an Simulated)!

_Figure 2.3 BER vs Eb/No without coding_