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Abstract-For the uplink of the E-UTRA Long Term Evolution (LTE) system, single-carrier frequency-division multiple access (SC-FDMA) transmission has been selected. Frequency-domain linear and decision-feedback equalizers have been already given in the literature for an SC-FDMA transmission over a multipleinput multiple-output (MIMO) intersymbol interference (ISI) channel. In this paper, a soft-output trellis-based equalizer is proposed, taking into account the cyclic ISI structure arising in SC-FDMA, which is especially suited for turbo-encoded transmission over channels with low-to-moderate signal-to-noise ratios (SNRs). A preprocessing stage is necessary for the trellisbased equalizer consisting of a minimum mean-squared error (MMSE) MIMO linear equalizer and a MIMO prediction-error filter, whose design is addressed. Simulation results for an LTE scenario demonstrate that the novel receiver yields significant gains compared to MMSE linear equalization in particular for square MIMO systems.

The performance targets for the long term evolution (LTE) of the Universal Mobile Telecommunication System (UMTS) into a 4th generation system have been chosen to be very ambitious. While all of these targets may not be achievable in practice, they have served to motivate the decisions for a particular LTE design. Specifically, we discuss the choice of the multiple access scheme for LTE, provide details on the uplink and downlink transmission formats, analyze the benefits of multiple input multiple output (MIMO), and outline approaches for intercell interference mitigation. The trade-off between usage of MIMO spatial multiplexing and beamforming is shown for a practical system. The required signaling overhead is weighed against the performance improvements available from the additional information. Finally, some examples for the achievable physical layer performance are given. © 2007 Alcatel-Lucent.(HSDPA) using orthogonal frequency division multiple access (OFDMA) transmission in a second 5 MHz downlink carrier using and maintaining the same channel structure as wideband code division multiple access (W-CDMA) HSDPA. The study concluded in June 2004 that there were some questions on the performance advantage of OFDMA over W-CDMA in a 5 MHz bandwidth under certain simulation assumptions [1], although it was feasible to introduce OFDMA in UMTS terrestrial radio access networks (UTRANs) in the downlink. Nevertheless, the need for conducting a wider feasibility study for evolution for both uplink (UL) and downlink (DL) in bandwidths below and beyond 5 MHz (from 1.25 MHz up to 20 MHz) was emphasized.

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