2784 PIERS Proceedings, Prague, Czech Republic, July 6–9, 2015 Interference Aware Iterative Receiver Performance for the Uplink of LTE-A Carlos Reis, Nuno Souto, Am´ erico Correia, and M´ ario M. da Silva ISCTE-University Institute of Lisbon and Instituto de Telecomunica¸ c˜ oes, Portugal Abstract— In this paper we study the performance of an interference aware iterative block decision feedback equalizer (IBDFE) for the uplink of LTE-Advanced with single carrier (SC) transmissions. The receiver makes use of the correlation between the interference in the receiving antennas and minimizes the mean squared error (MMSE) of the detected symbols. Link level simulation results show that the proposed receiver clearly outperforms the conventional IBDFE and the linear interference rejection combining (IRC) detector. System level simulation results show that the use of the new iterative receiver achieves additional throughput gains. However, the gains obtained depend on the schedulers employed and on the number of receiving antennas. 1. INTRODUCTION Mobile data traffic is growing exponentially in 4G networks with new multimedia applications on smart mobile devices putting more stringent demands on the quality of service. In addition to supporting efficiently the signaling and traffic from interactive video and gaming applications, 4G networks also need to handle the signaling and traffic from a multitude of machine-type com- munication devices. In order to tackle the inter symbol interference (ISI) caused by the channel time dispersion, 4G networks use orthogonal frequency division multiplexing (OFDM) [1] or SC [2] transmission techniques. While OFDM allows a simple implementation of both the transmitter and receiver it suffers from a large peak to average power ratio (PAPR) which makes it more suitable for the downlink. For the uplink, the use of single carrier block transmissions with frequency domain equalization (SC-DFE) is often preferred due to its lower PAPR while still being robust in ISI inducing channels [3] (see also the 3GPP Long Term Evolution (LTE) [4]). However, in this case, the performance of low complexity linear receivers is far from the matched filter bound (MFB) [5]. In order to reduce this gap, one has to resort to nonlinear schemes [6], with the IBDFE [7–10] being one of the most promising solutions. Besides the channel dispersion problem, the emergence of denser heterogeneous cells creates large levels of interference among users which must be dealt using techniques like coordinated scheduling, cooperative processing or interference cancellation. Even though the interference can be removed using similar approaches to those used by spatial multiplexed receivers [11, 12] the resulting complexity can be excessive. Lower complexity techniques exist like the linear IRC [13] which does not require the estimation of the interferers’ streams. This receiver is a direct extension of the conventional minimum mean squared error (MMSE) detector and has been studied for use in 3GPP LTE systems [14–17]. However, linear IRC detectors applied in SC schemes will perform far from optimum in severe time dispersive channels. Therefore, in [18] we designed a modified IBDFE for SC transmissions whose feedforward and feedback filters are implemented in the frequency domain and optimized by taking into account the presence of correlated interference between multiple receiving antennas. In this paper we evaluate the performance of the interference aware IBDFE proposed in [18] for the uplink of LTE-Advanced and compare it against other receivers, namely the conventional IBDFE and the linear IRC detector. The comparison is accomplished through link level and system level simulations in time dispersive channels with cochannel interference. The rest of this paper is organized as follows. Section 2 describes the structure of an interference aware IBDFE with several antennas. Section 3 presents the system level simulation scenario. Numerical results are shown in Section 4 followed by the conclusions in Section 5. 2. INTERFERENCE AWARE IBDFE The structure of the interference aware IBDFE proposed in [18] with several receive antennas is shown in Fig. 1. A SC transmission with blocks of N modulated symbols, s n ,(n =1,...,N ), appended with a suitable cyclic prefix (CP) is assumed. After the application of an N -point DFT (Discrete Fourier Transform) the sequence of received samples can be written as Y k = H k S k + H I k S I k + N k . (1)