BERkurver

BERkurver, or bit error rate curves, are graphs that show how the probability of a received bit being in error (the BER) changes as the signal-to-noise ratio or Eb/N0 increases. They are a fundamental tool for evaluating the reliability of digital communication systems and for determining the required SNR to achieve a target BER. BER curves can be obtained analytically for simple modulation schemes in additive white Gaussian noise (AWGN), or estimated through Monte Carlo simulations and measurements for more complex setups.

In AWGN with common modulation schemes, uncoded BER expressions are well known. For binary phase-shift keying (BPSK) and for Gray-codedquadrature phase-shift keying (QPSK), the BER is often written as BER = Q(sqrt(2 Eb/N0)). For M-PSK modulations, the approximate BER is typically expressed as BER ≈ 2 Q(sqrt(2 Eb/N0)) / log2 M, with the exact value depending on the modulation order and coding. Introducing forward error correction shifts the BER curve to lower Eb/N0 values, reflecting a coding gain; with soft-decision decoding, additional performance improvements are typically observed compared to hard-decision decoding.

BERkurver also apply to fading channels (e.g., Rayleigh, Rician) and with diversity, coding, and interleaving, where curves reflect the combined effects of modulation, coding, and channel statistics. They are used in link-budget calculations, system design, performance comparisons, and standard-compliance testing, helping engineers choose modulation and coding schemes that meet reliability targets.