Benefits of modulation diversity in turbo-coded OFDM systems

We show that the use of modulation diversity provides gains to punctured, turbo-coded OFDM systems. For an OFDM transmission scenario, based on the downlink of the 3GPP standard for mobile communications, we show that the order-2 modulation diversity, observed for the raw bit-error rate, transfers to the block-error rate in a number of investigated channel environments. We demonstrate gains of up to 2.5 dB, depending on the puncturing rate of the scheme and the particular channel characteristics. Alternatively, for schemes with higher puncturing rates, 2 or 3 turbo decoder iterations suffice to achieve the same performance as achieved by 8 decoder iterations in a regular transmission.