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In this paper, we propose two vector perturbation (VP) schemes for single-carrier (SC) multi-user (MU) multiple-input multiple-output (MIMO) downlink block transmission. The first VP scheme (called SC-VP-1) adds a perturbation vector to each user's signal block in time-domain and then, multiplies a precoding matrix to perturbation vector-added signal blocks in time-domain. The precoding matrix used...
In this paper, we propose two complexity reduction techniques for blind adaptive beamforming in orthogonal frequency division multiplexing (OFDM) antenna array systems. For each sub-carrier, a beamformer with generalized sidelobe canceller (GSC) structure is designed according to the constrained constant modulus (CCM) criterion with weight vectors adaptation based on the recursive least squares (RLS)...
In this paper, a software-based implementation for the Multiple Input and Multiple Output (MIMO) receiver baseband processing conforming to the IEEE 802.11ac standard on a DSP core with vector extensions is presented. The implementation is carried out for different operation points including 2×2 and 4×4 MIMO configurations, yielding beyond 1Gbps transmission bit rate. This implementation mainly focuses...
A massive MIMO technique uses more than 100 antennas. According to several recent results, it can increase 10 times or more channel capacity than a conventional MIMO system with small number of antennas. However, one critical problem of this system is that it should overcome channel correlations such as spatial correlation and antenna mutual coupling. In order to overcome these problems, a new massive...
A novel digital predistorter (DPD) for the linearization of power amplifiers (PAs) is presented. The structure is based on a doubly-symmetric Parafac tensor decomposition of Volterra kernels and takes advantage of a frequency-domain representation, what makes it specially attractive for the transmission of orthogonal frequency division multiplexing (OFDM) signals. The approach has been successfully...
Multipath delay, Doppler shift and spread lead to overlapping and distortion in both the time and frequency domain of a wireless wideband signal. Although the resulting time-and-frequency-selective (or namely, doubly selective) fading may degrade the system performance, it also enables possible multipath and Doppler diversity when the system is properly designed. In this paper, based on the basis...
In this paper we introduce an adaptive channel estimation scheme for two-way relay with node capability. The adaptive filter used is called Block Fast Array Multichannel 2D-Recursive Least Square (BFAM 2D-RLS). The modulation used is Orthogonal Frequency Division Multiplexing (OFDM) and channel estimation is done in the frequency domain. The proposed channel estimator considers correlation of channel...
An iterative low-complexity channel estimation algorithm for OFDM signals in frequency domain is presented. Algorithm uses initial channel estimation based on pilot subcarriers, 1-D adaptive Wiener filtering in the time direction and Maximum a-posteriori probability (MAP) estimation that uses both pilot and weighted data subcarriers. The final step is the simplified version of an iterative Expectation-Maximization...
In this paper, Orthogonal Frequency Division Multiplexing (OFDM) based full-duplex Cognitive Radio (CR) network is proposed in the presence of Narrow Band Interference (NBI). The proposed overlay CR network employs Decode and Forward (DF) strategy at the relay node. Analytical expressions are derived for outage probabilities at the relay and destination nodes of full-duplex CR network in the presence...
Bistatic/passive radars offer several advantages over monostatic radars. One of them is that the separation of transmitter and receiver opens the possibility to illuminate the targets from different aspect angels compared to the receiver. This spatial diversity can enhance the capability of target detection, parameter estimation, and identification, especially for stealth objects with low monostatic...
Channel estimation provides channel state information (CSI) for equalizing channel distortion and demodulating received signals. As a consequence, this technique takes an important part in modern wireless communications systems. Comparing with conventional pilot-aided channel estimators, compressive sensing based channel estimation methods can exploit the sparse property of the wireless channel and...
A sparse-training-sequence-aided orthogonal frequency division multiplexing system is proposed to enable channel estimation and data detection without being affected by carrier frequency offset (CFO) effect. With the aid of the sparse training sequence, an approximate maximum likelihood estimation on CFO effect and channel response is developed to retrieve the CFO and channel response information...
MIMO CDMA system with the calibration of OFDM method is proposed. To obtain the spatial diversity between the symbols, STBC block codes were used. Space time block coding (STBC) is the most efficient method due to its provision of full spatial diversity and simple linear decoder. The combination of space-time block coding (STBC) and Direct-Sequence CodeDivision Multiple Access (CDMA) has the potential...
The hopping pattern for D2D Discovery are investigated. We propose three metrics for hopping pattern performance evaluation: column period, maximal collision ratio, maximal continual collision number. A class of hopping patterns is constructed based on the metrics, and through simulation the patterns show better discovery performance.
This paper introduces filter bank multicarrier (FBMC) as a potential candidate in the application of massive MIMO communication. It also points out the advantages of FBMC over OFDM (orthogonal frequency division multiplexing) in the application of massive MIMO. The absence of cyclic prefix in FBMC increases the bandwidth efficiency. In addition, FBMC allows carrier aggregation straightforwardly. Self-equalization,...
We analyze the performance of an orthogonal frequency-division multiplexing interleave-division multiple access (OFDM-IDMA) system for channels with a carrier frequency offset. First we introduce a vector-valued transmission model for the OFDM-IDMA system, including an improved chip detector. A semi-analytical technique is applied to generate variance transfer charts and predict the performance of...
In our previous paper, we have proposed mutual superposition transmission (MST) for spatial multiplexing (SM) orthogonal frequency division multiplexing (OFDM) systems. In MST, two data symbols of two different subcarriers are mutually superposed on respective subcarriers after being weighted. As a result, a diversity gain is obtained without degrading the transmission speed. However, one drawback...
The design of efficient receivers for orthogonal frequency division multiplexing I space division multiple access (OFDM/SDMA) channels remain a challenging task especially when the number of mobile stations (MSs) transmitting exceed base station (BS) antennas. The benchmark performance is achieved by Maximum Likelihood (ML) detector at the cost of computational complexity that exponentially increases...
The scarcity of radio resources coupled with the high data rate demands in the last few years, induced incremental relaying techniques one of the most promising technologies. This is simply because it allows reaping spatial diversity and saving the channel resources at the same time. In this contribution, we make use of the Decode and Forward incremental relaying technique in OFDM cooperative systems...
Zero-tail Discrete Fourier Transform -spread OFDM (ZT DFT-s-OFDM) modulation allows to dynamically cope with the delay spread of the multipath channel, thus avoiding the limitations of hard-coded Cyclic Prefix (CP). In this paper, we discuss the potential of ZT DFT-s-OFDM modulation for the envisioned 5th generation (5G) radio access technology, characterized by an ultra-dense deployment of small...
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