ancellation (SIC) equalizer as described in Laot, Glavieux, and Labat [16] and frequency domain equalization. This structure results in more efficient operation than the traditional time domain equalization [17] because the equalization is performed on one data block at a time. Moreover, the operations within this block involve an efficient FFT operation and a simple channel inversion operation. In the following, the performance of the receiver with turbo equalizer is evalu- ated using a 1 x 2 SIMO antenna scheme based on the simulation parameters in Table 6.2. © 2009 by Taylor & Francis Group, LLC Single-Carrier Transmission for UTRA LTE Uplink Subcar Removal Equalizer mapping Subcar Removal mapping req,k L(bi,i) Sk E(s)k) L1(bkij) Pa(sik) LA(b) LD(b) Turbo SISO Hard values Decoder L1(bm) Figure 6.20 Turbo equalizer structure. Figure 6.21 shows the BLER performance of the SC-FDMA 16 QAM system with three different coding rates. The results of TEQ with different iterations and SC-FDMA with simple MMSE are given. Two different results for turbo equal- ization are plotted with two and four iterations of the algorithm, respectively. Compared with the MMSE receiver, the turbo equalizer shows a gain of about 1 dB. In our assumptions, the cyclic prefix allows complete removal of the ISI; hence, the gain is exclusively due to the reduction of the noise component. The significant gain is already obtained from two iterations of the algorithm. In Figure 6.22 the performance of OFDMA has also been included, and the results are shown for both QPSK and 16 QAM modulations in comparison with the SC-FDMA TEQ receiver performance for two iterations of the algorithm. Note that for QPSK 2/3 and QPSK 3/4, the SC-FDMA with MMSE system performs better than OFDMA. This is due to the fact that low-order modulation schemes are robust to the noise enhancement of SC-FDMA transmission. Moreover, OFDM © 2009 by Taylor & Francis Group, LLC Long Term Evolution: 3GPPLTE Radio and Cellular Technology 16 QAM 1/2 16QAM 2/3 16QAM 4/5 TEQ 2x TEQ 4x 