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Optimizing energy efficiency (EE) for the MIMO broadcasting channels (BC) is considered in this paper, where a practical power model is taken into account. Although the EE of the MIMO BC is non-concave, we reformulate it as a quasiconcave function based on the uplink-downlink duality. After that, an energy efficient iterative waterfilling scheme is proposed based on the block-coordinate ascent algorithm...
Some recent communication systems like DVB-T2 standard set up a PAPR reduction technique followed by a linearization's one. So in such a scenario, the performance of the linearization is influenced undoubtedly by the PAPR reduction method. In this paper, we revisit the EVM metric and evaluate a closed form regarding the performance of both the PAPR reduction technique and the linearization's one....
The reduction of spurious emission is an important issue in future OFDM-based systems, especially in the context of cognitive radio, when the primary users must be protected from the interference. In this paper, flexible quasi-systematic precoder is presented for non-contiguous OFDM transmitter, which has the effect of relatively small distortion of the data symbols modulating the subcarriers. We...
In this paper, dual-hop amplify-and-forward (AF) cooperative systems in the presence of in-phase and quadrature-phase (I/Q) imbalance, which refers to the mismatch between components in I and Q branches, are investigated. First, we analyze the performance of the considered AF cooperative protocol without compensation for I/Q imbalance as the benchmark. Furthermore, a compensation algorithm for I/Q...
This paper proposes a novel clipping and filtering method employing transmit power control to improve the bit error rate (BER) performance in MIMO-OFDM transmission. The feature of the proposed approach is to perform the transmit power control before clipping and filtering to alleviate the BER degradation caused by clipping and filtering. Since the transmit power control to satisfy maximum signal-to-noise-plus-distortion...
Current trends in low-cost and low power consumption transmitters in state-of-the-art wireless systems is to use the direct-conversion principle. Such transmitters, however, suffer severely from the I/Q imbalance effect, which introduces mirror-frequency interference and degrades data detection. This paper proposes a novel method for frequency-dependent I/Q imbalance estimation and compensation. The...
A new space-time block code (STBC) is presented for distributed 4 × 2 multiple-input multiple-output (MIMO) systems. A 2 × 2 full-rate full-diversity (FR-FD) low complexity space-time code, presented by Sezginer and Sari, is employed for two distributed links. Alamouti STBC is applied over the two links to obtain a double layer space-time block code (DLSTBC) providing full diversity in a distributed...
We propose a packet delayed lattice reduction aided MIMO detection for 802.1 1n system. Lattice reduction algorithms are iterative in nature that results in long latency. In high throughput systems like 802.11n, reduction of latency via parallelization causes high hardware complexity. Without parallelization, the receiver needs to buffer the incoming data until the lattice reduction finishes. Depending...
In this paper, we propose an orthogonal space-time block coding (STBC) for continuous phase modulation (CPM) over frequency-selective channels. The new method maintains the constant envelope and the phase continuity of the CPM waveforms by inserting three blocks of data-dependent symbols in addition to a cyclic prefix (CP). At the transmitter, the data blocks are precoded and transmitted in two antennas...
In this paper we introduce an efficient decoding method which is based on the dimensionality reduction of the search tree in the sphere decoder for the golden code in a low SNR regime. A codeword of the golden code has four independent m-QAM data symbols, hence, the required complexity of the exhaustive-search decoder is m4. An efficient implementation of the maximum-likelihood decoder for the golden...
Distributed space-time block coding with orthogonal frequency division multiplexing (DSTBC-OFDM) and distributed space-frequency block coding with orthogonal frequency division multiplexing (DSFBC-OFDM) are introduced in this paper. Unlike the original DSTBC scheme which was designed for networks with a fixed number of relays operating in frequency-nonselective channels with insignificant Doppler...
Knowledge of the achievable restricted isometry constant (RIC) of the sensing matrix is crucial for assessing the signal reconstruction performance of compressive sensing systems. In this paper we consider compressive-domain interference cancellation via orthogonal projection, and study the achievable RIC of the effective sensing matrix, namely, the product of the orthogonal projection matrix and...
We consider rate splitting and interference cancelation in Device-to-Device (D2D) communications underlaying a cellular network. We assume that a transmitted message is split into a private and a public part, as in Han-Kobayashi scheme. The private part is decodable only by the intended receiver, whereas the public part is in addition decodable by an interference victim. The receivers run a best-effort...
A low-complexity detection algorithm is proposed for Multiple-Input Multiple-Output (MIMO) systems with many transmit and receive antennas. We involve QR Decomposition (QRD) to triangularize the effective MIMO channel matrix so that several MIMO sub-systems can be individually established, which allow detecting several (possibly overlapping) groups of data streams separately. This method is referred...
A multi-pair two-way relaying scenario with multi-antenna mobile stations is considered. The bidirectional communications between the mobile stations are supported by an intermediate non-regenerative multi-antenna relay station. It is assumed that the mobile stations can subtract the back-propagated self-interference. Different relay transceive filter design approaches which utilize the fact that...
We address joint design of robust precoder and equalizer in a MIMO communication system using the minimization of weighted sum of mean square errors. In addition to imperfect knowledge of channel state information, we also account for inaccurate awareness of interference plus noise covariance matrix and power shaping matrix. We follow the worst-case model for imperfect knowledge of these matrices...
In this paper, we investigate the performance of relay selection in an underlay cognitive radio system in the presence of primary user (PU) interference. In particular, we consider a secondary multi-relay network operating in the amplify-and-forward (AF) mode and only the “best” relay which satisfies an index of merit is selected. The proposed selection strategy takes into consideration the effect...
Cognitive radio (CR) can successfully deal with the growing demand and the scarcity of the wireless spectrum. To increase the spectrum usage, CR technology allows secondary users to access licensed spectrum bands. Since licensed users have priorities to use the bands, the secondary users need to continuously monitor the activities of the licensed users to avoid interference and collisions. In this...
We study the error and diversity-multiplexing tradeoff (DMT) performance of a (secondary) multi-user relay network, where a class of finite field network codes are applied in the relays to efficiently provide spatial diversity. To eliminate spectral efficiency loss induced by half-duplex limitation we adopt the cognitive radio overlay spectrum sharing concept and consider aligning the relays' operation...
Cognitive radio (CR) networks rely on the spectrum sensing function to ensure that there is no interference to the licensed or primary users (PUs). Typically, sensing algorithms assume a static PU activity model, i.e., spectrum usage model, which is constant for a given channel and known in advance. This approach fails to capture the dynamic and time-varying behavior of the PUs. In this paper, a spectrum...
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