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In this paper, an iterative multiuser detector is proposed for uplink large-scale Multiple Input Multiple Output (MIMO). It is developed based on the Generalized Approximate Message Passing (GAMP) algorithm, and its convergence properties are analyzed by a one-dimensional iteration termed as State Evolution (SE). The SE analysis proves that the complexity of the GAMP detector (GAMPd) is one order...
This paper investigates the bit error rate (BER) performance of spatial diversity free-space optical (FSO) communication systems using on-off keying modulation. The study considers correlated log-normal FSO channels as well as path losses due to weather effects using intensity modulation and direct detection schemes. An approximated moment generating functions (MGF) for the joint probability density...
This work studies the problem of jointly estimating the carrier frequency offset (CFO) and sampling frequency offset (SFO) in orthogonal frequency-division multiplexing (OFDM) systems. Two scenarios are considered: known channel impulse response (CIR) and unknown CIR. It was shown in previous works that the exact joint maximum-likelihood estimate (MLE) of the CFO and the SFO requires a two-dimensional...
A hybrid automatic repeat request scheme with Chase combing (HARQ-CC) of polar codes is proposed. The existing analysis tools of the underlying rate-compatible punctured polar (RCPP) codes for additive white Gaussian noise (AWGN) channels are extended to Rayleigh fading channels. Then, an approximation bound of the throughput efficiency for the polar coded HARQ-CC scheme is derived. Utilizing this...
In this paper, power allocation between training and data symbols is investigated to maximize energy efficiency (EE) for multicell systems using coordinated beamforming (CBF). We formulate the EE optimization problem under a minimum rate requirement as a multi-variable non-quasiconcave fractional program. Based on an approximation of the ergodic rate, we transform the problem into a jointly quasiconcave...
We consider a coordinated multi-point (CoMP) uplink cellular network with a Poisson point process (PPP) model for the position of BSs. Our model assumes cooperation amongst two BSs and the required density is obtained under shadowing and Rayleigh fading for different LTE-A path loss models. We obtain accurate closed-form approximations for the worst-case rate coverage probability within the cooperation...
Capacity computations are presented for Faster-Than-Nyquist (FTN) signaling in the presence of interference from neighboring frequency bands. It is shown that Shannon's sinc pulses maximize the spectral efficiency for a multi-access channel, where spectral efficiency is defined as the sum rate in bits per second per Hertz. Comparisons using root raised cosine pulses show that the spectral efficiency...
A two-phase energy efficient collaborative spectrum sensing (CSS) strategy, namely EE-CSS, was proposed in [1], and expressions were derived for the steady-state (long term) average trust values and number of transmitted reports for honest as well as malicious secondary users. In this paper, we study the transient behavior of these quantities. A closed form expression is derived for the transient...
In this work, we investigate the robust energy-efficient transmission for the cognitive uplink wireless system. Precisely, we propose an optimization framework for maximizing the sum energy efficiency while taking into account the uncertainty of the channel between the primary and secondary users. Here, we assume that the base station has multiple antennas and employs a zero-forcing receive filter...
Recently, substantial attention has been paid to improve the spectral efficiency of communication setups using different spectrum sharing techniques. This paper studies the throughput of spectrum sharing channels utilizing hybrid automatic repeat request (HARQ) protocols. Considering different HARQ schemes, the unlicensed user throughput is obtained under an outage probability constraint for the licensed...
Multiple carrier frequency offsets (CFOs) present in the uplink of orthogonal frequency division multiple access (OFDMA) systems adversely affect subcarrier orthogonality and impose a serious performance loss. In this paper, we propose the application of time domain receiver windowing to concentrate the leakage caused by CFOs to a few adjacent subcarriers with almost no additional computational complexity...
We derive reduced order (light) Wiener filters for slow flat fading channel estimation in pilot aided Alamouti receiver. The concept is based on the approximation of the channel auto-covariance function to zero and second order Taylor series for the cases when there is only partial knowledge about channel statistics at the receiver. Moreover this approach reduces computational effort in design of...
In this paper, we characterize the average end-to-end delay and maximum achievable per-node throughput in an opportunistic secondary cognitive radio network coexisting with a primary network where both networks consist of static nodes that use random medium access schemes. Assuming an ideal sensing mechanism, we first model the secondary network as a two-class priority queuing network and use queuing...
In dynamic cognitive radio networks (CRNs), unlicensed secondary users (SUs) opportunistically transmit in the spectrum holes left available by licensed primary users (PUs), without knowing in advance their presence on the channels. For SUs with multi-channel transmission capability, the process of selecting the channels to use by sequentially sensing the presence of PUs and evaluating the channel...
Since mobile communications exhibit strong social characteristics, based on the potential common interests of mobile users, mobile social networks (MSNs) are capable of mitigating the tele-traffic bottleneck. By multicasting the content of common interest from a content owner to content seekers within the owner's transmission range, a distributed MSNs architecture is proposed, which is capable of...
In this paper, we study the issue of optimally allocating the transmission energy between a pilot symbol and data symbols for a point-to-point communication system over the slow fading channel. In the system studied, our performance criterion for the optimal energy allocation is the frame error probability (FEP). A pilot symbol-assisted modulation (PSAM) scheme is used along with a channel estimation...
We propose a simple, yet accurate, interference prediction model using the widely used two-ring hexagonal network layout in the absence or presence of shadowing. The proposed model only considers two dominant interferers out of the 18 ones that surround the serving base station. The proposed model, in contrast to the fluid model, takes the radial direction into account. This makes our proposed model...
In this paper, we present two approximation algorithms for minimizing power consumption of wireless sensor networks (WSNs) in environmental monitoring applications. Most approximation algorithms for similar problems assume that the cost function satisfies the triangle inequality. For a cost function defined based on power consumption for reliable transmission between two nodes in a WSN, this assumption...
Cooperative communication techniques are used in vehicular ad hoc networks (VANETs) to enhance system performance through distributed spatial diversity. In this paper, the average error rate performance of a VANET Cooperative Selection-Combining Receiver (CO-SCR) is analyzed over generalized statistically measured fading channels. Source-Destination and Source-Relay-Destination links are assumed to...
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