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A multi-lattice-reduction aided (MLRA) vector precoding algorithm is proposed in this paper. Compared with traditional lattice-reduction-aided (LRA) method, the new method tries to find a set of candidates of perturbation vectors through reducing the formulated lattice to get subspaces of searching space. Within each subspace, a candidate vector is solved. Then the optimum vector is found in this...
We consider an Amplify-and-Forward relay selection for OFDM networks with fairness constraints where a source node communicates with a destination node with the help of one or more relays. The system model assumes all relays participate and considers the subcarrier pairing with fairness constraints on relays. Our subcarrier allocation algorithm is presented to maximize the system capacity based on...
Structured high-girth non-binary cycle codes on the high-girth symmetric Hamiltonian graphs are proposed in this paper. Using the high-girth property, we construct high-girth non-binary cycle codes with good performance in the waterfall region. By decomposing the Hamiltonian graph into Hamiltonian cycle plus chord edges and using a concise notation, the proposed cycle codes have very low description...
Four utility-based criteria are considered to study dynamic resource allocation in Multiple Input Multiple Output - Orthogonal Frequency Division Multiple Access (MIMO-OFDMA) multiuser cellular systems. In these criteria, two generalized bargaining strategies, GNBS and KSBS, are used to emphasize different levels of user fairness, while the criteria of utilitarian and egalitarian are briefly discussed...
In this paper, we propose a block-based OFDM decode-and-forward relaying scheme for cooperative wireless networks. In the scheme, an OFDM symbol is divided into blocks and one relay is selected for each block. Theoretical outage performance is analyzed and evaluated, and a unified outage expression is developed for our scheme and the other two schemes. Monte Carlo simulations are carried out to validate...
In this work, we propose a novel combined set-membership (SM) reduced-rank interference suppression scheme and consider its application to spread-spectrum multiuser direct sequence ultra-wideband (DS-UWB) systems. In the proposed scheme, the theory of set-membership filtering is applied to the training-based powers of R (PoR) multi-stage Wiener filter (MSWF) reduced-rank process and the reduced-rank...
Resources allocation of OFDM system is a key factor that affects system performance. Parteek Bansal proposed a bit-power allocation algorithm under different bit error rate (BER). But the process of its bit allocation will cause high complexity and bad real-time to build a power-increment table. In this paper, a low-complexity multi-user subcarrier-bit-power allocation algorithm for wireless OFDMA...
In this paper, we propose an extended semidefinite-relaxation (SDR) method for multiple-input multiple-output (MIMO) detection of high-order QAM signals. In the proposed method, high-order QAM constellations are represented by an equivalent virtually-antipodal form. Based on this form, the alphabet relaxation components in the existing SDR formulation can be constrained to the original alphabet set...
The cooperative operation can improve the sensing performance of cognitive radio networks and reduce the sensing time. Combining multiple cognitive users' local detection results and making accurate judgment is essential to improve cooperative gain. According to uploaded information from cognitive users, hard decision based on the combination of large numbers and soft decision based on the confidence...
To seek a decoding scheme with good performance, low complexity and fast convergence, we present an improved parallel weighted bit flipping (IPWBF) algorithm for finite geometry low-density parity-check codes whose parity check matrix is of heavy row and column weights. In the IPWBF, a bit flipping (BF) function and two parallel BF criteria, all of which scatter in the literature, are exploited jointly...
In this paper, the performance of an ultra-wideband (UWB) communication system employing orthogonal pulse position modulation (PPM) and non-orthogonal pulse position modulation (NPPM) is considered. Time hopping (TH) is used to decrease the effect of multiuser interference. It is shown that for a large number of users, NPPM provides better bit error rate (BER) performance than PPM. We also determine...
In this paper, we consider robust hashing based on a bit reliability function that allows to enhance the performance in terms of both average probability of error and identification complexity. The obtained results demonstrate the high efficiency of the prosed approach.
We consider the problem of detecting a primary signal over a wireless channel by a multiantenna cognitive spectral monitor with knowledge of the spectral shape of primary transmissions employing multicarrier modulation. As a starting point, a Locally Most Powerful (LMP) test is derived for the single-antenna case. The asymptotic performance improvement of the LMP detector over the standard Energy...
We consider communication over the block noncoherent AWGN channel with low-precision Analog-to-Digital Converters (ADCs) at the receiver. For standard uniform Phase Shift Keying (PSK) modulation, we investigate the performance of a receiver architecture that quantizes onlythephase of the received signal; this has the advantage of being implementablewithoutautomaticgaincontrol, using multiple...
A new affine projection (AP) algorithm based on dichotomous coordinate descent (DCD) iterations has been recently proposed for acoustic echo cancellation (AEC). It uses a constant step size parameter and, therefore, has to compromise between fast convergence and tracking on the one hand, and low misadjustment and robustness to the presence and variations of a near-end signal on the other hand. In...
We consider multiuser multicarrier systems, where each non-symmetrically distributed user reports only partial indices of subcarriers whose normalized SNRs exceed the predetermined threshold so that only partial feedback information is available at the base station. To accommodate both efficiency and fairness, the base station is assumed to perform the normalized SNR based proportional fair scheduling...
In this paper, we propose a novel radius control strategy for sphere decoding referred to as inter search radius control that provides further improvement of the computational complexity with minimal extra cost and negligible performance penalty. The proposed method focuses on the sphere radius control strategy when a candidate lattice point is found. For this purpose, the dynamic radius update strategy...
The problem of transmit beamforming for single-group multicasting is considered, where the objective is to transmit common information to a (large) number of users. The transmitter is assumed to have accurate downlink channel state information (CSI) for all users, and the objective is to design the beamformer weights to minimize the total transmitted power subject to meeting the quality-of-service...
We use the theory and algorithms developed for so-called shift-invariant spaces to develop a novel distributed architecture for sampling and reconstructing non-bandlimited fields in wireless sensor networks. Our scheme groups neighboring sensors into clusters that locally perform highly accurate field reconstruction with limited communication overhead. The overall complexity of our method scales only...
This paper considers combining the iterative soft output Viterbi algorithm (SOVA) and the logarithm maximum a posteriori (Log-MAP) algorithm for decoding turbo codes. We examine the differences between the two algorithms and discuss the suitability of combining both algorithms. In the proposed hybrid decoding scheme, frames are first applied with SOVA iterations with error detection for iteration...
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