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This paper investigates the performance of different low-complexity combining schemes in the context of dual-hop amplify-and-forward relaying networks. It is assumed that the relay uses single transmit (receive) antenna due to space limitation and to reduce the processing complexity. On the other hand, the transmitter and the receiver use antenna arrays to improve the overall diversity gain. However,...
We consider the uplink of a wireless sensor network with single-antenna sensors, an access point (AP) equipped with multiple antennas, and a common radio channel. To reduce the number of outages resulting from the noise amplification by the zero-forcing (ZF) within the successive interference cancellation (SIC) procedure, the AP is given the possibility to request a selected number of sensors to retransmit...
Low complexity, iterative MIMO detection algorithms are derived based on pair-wise Markov random fields (MRF). We consider two types, namely, the fully-connected and the ring-type MRF and, for the edge potentials, we use the bivariate Gaussian function obtained by marginalizing the posterior joint probability density under Gaussian-input assumption. Since the corresponding factor graphs has only 2...
Today's telecommunication systems require more and more flexibility, and reconfiguration mechanisms are becoming major topics especially when it comes to multi-standard designs. This paper capitalizes on the Common Operator technique to present a new common operator for the FFT and Viterbi algorithms. In the present work, the FFT/Viterbi common butterfly is investigated where reuse and power consumption...
Often, to increase the efficiency of high-power amplifiers (HPAs), these amplifiers are driven into a nonlinear region. The nonlinearities in HPAs warp the signal constellation, increasing out-of-band radiation and causing both EVM and BER degradation. Digital predistortion (DPD) is one of the most promising linearization techniques that could lead to more efficient and cost-effective HPAs. The DPD...
In this paper a distributed, low-complexity, fast and fair resource allocation algorithm for a multiuser, wireless LTE OFDMA channel is proposed. Based on the game theoretic concept of the Nash Bargaining Solution and by grouping users into coalitions of size 2, a cooperative solution to the problem of subcarrier allocation is achieved. The fairness that our algorithm provides matches that offered...
In this paper, a new successive interference cancellation (SIC) strategy for multiple-input multiple output (MIMO) spatial multiplexing systems is developed to combat the error propagation (EP) in decision feedback systems. The proposed scheme employs a parallel multi-branch (MB) structure. Each branch employs a SIC with multi-feedback (MF) strategy to detects the signals according to their respective...
In this paper, we propose a new detection algorithm for single carrier-frequency division multiple access (SC-FDMA) systems called duo maximum likelihood detector with transmit power allocation (DMLD-TPA). The proposed scheme is based on iteratively detecting two symbols out of Q transmit symbols by an orthogonal projection. It can make the detection complexity less than that of the maximum likelihood...
Radio Resource Management with Inter-cell Interference Coordination (ICIC), is a key issue under investigation for next generation wireless systems such as Long Term Evolution (LTE). Although centralized resource allocation (RA) and collaborative processing can optimally perform ICIC, the overall required complexity suggests the consideration of distributed techniques. In this paper we propose and...
Low Density Signature-Orthogonal Frequency Division Multiplexing (LDS-OFDM) has been introduced recently as an efficient multiple access technique. In this paper, we focus on the subcarrier and power allocation scheme for uplink LDS-OFDM system. Since the resource allocation problem is not convex due to the discrete nature of subcarrier allocation, the complexity of finding the optimal solutions is...
Coherent multi-cell cooperative transmission, also referred to as coordinated multi-point transmission (CoMP), is a promising way to provide high spectral efficiency for universal frequency reuse cellular systems. To report the required channel information to the transmitter in frequency division duplexing systems, limited feedback techniques are often applied. Considering that the large scale fading...
In a multiuser MIMO cellular system where there are many candidate users, it is critical to select a user group which maximizes the overall throughput of the system. However, the optimal scheduling strategy is computationally prohibitive when the total number of users is large. In this paper, we propose a determinant based user selection algorithm which reduces the search complexity without much performance...
The inherent high peak-to-average power ratio (PAPR) of multicarrier transmission, such as OFDM or DMT, is a major drawback that can significantly worsen the power efficiency and performance of these systems. As a consequence, a number of PAPR reduction techniques have been proposed in the literature each offering a different combination of system performance, complexity and bandwidth efficiency....
This paper discusses compressive sensing with sparse measurement matrices. Sparse matrices have several attractive properties, like low computational complexity in both encoding and recovery, easy incremental updates to signals, and low storage requirement, etc. Typical examples of existing algorithms for sparse signal recovery with sparse measurement matrices include convex relaxation, matching pursuit,...
For soft-input soft-output sphere decoding (SD), the combination of the Schnorr-Euchner (SE) enumeration and the radius reduction shrink the search space quickly but with considerable computational complexity. In this paper, a low complexity approach is proposed to reduce the tree search space before SD starts. Particularly, such reduction is achieved by 1) tightening the initial radius; 2) restricting...
A novel linear blind reduced-rank receiver based on the Joint Iterative Optimization (JIO) and the constrained constant modulus (CCM) design criterion is proposed for interference suppression in direct-sequence ultra-wideband (DS-UWB) systems. The proposed receiver consists of a projection matrix that performs dimensionality reduction and a reduced-rank filter that produces the output. The columns...
We propose a symbol-by-symbol (SBS) detector for Gaussian minimum shift keying (GMSK) signals in body area networks (BAN). Our detector exploits the orthogonality between adjacent GMSK-modulated symbols. By dividing the received signals into inphase-/quadrature-channels and odd-/even-streams, the strongest inter-symbol interference (ISI) from the adjacent symbols is removed. A whitened matched filter...
Spectrally Efficient FDM (SEFDM) signals employs non-orthogonal and overlapping carriers to provide higher spectrum utilization relative to Orthogonal FDM signals (OFDM). Complex detectors are employed to extract the signal from the intercarrier interference (ICI) created by the loss of orthogonality. Sphere Decoder (SD) is proposed for SEFDM detection as an algorithm that achieves ML bit error rate...
Spectrum sensing is the first key functionality to realize Cognitive Radios which also meet harsh performance demands under various severe conditions, e.g. the reliability and sensitivity demands under the low sensing overhead constraint. Cooperative sensing exploiting SPRT is an efficient sensing method which can significantly decrease sensing delay and sensing overhead, thereby, has been extensively...
Soft-In Soft-Out (SISO) MIMO detection algorithms providing soft information to subsequent channel decoder are computationally high complex. Realizations based on depth-first search e.g. the Tuple Search (TS) algorithm enables near full MaxLogAPP optimal detection at much reduced but still high complexity. This paper presents a novel method for the complexity reduction of SISO MIMO detection algorithms...
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