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In this paper, we consider the resource allocation problem in the uplink transmission of an orthogonal frequency-division multiple access (OFDMA) based cognitive radio (CR) network. The resource allocation aims to maximize the uplink throughput of secondary users (SUs) in CR network under the constraints of the primary user (PU) interference and the transmit power limits of SUs. In general, the optimal...
This paper proposes a novel recursive approach for orthogonal frequency division multiplexing (OFDM) channel estimation over highly mobile channels without any priori channel statistics. The key idea is to decompose each objective channel into the known component and the rest for estimation. The known component is the output of the prior iteration except that the first one is attained in linear time-varying...
In this paper, we propose a novel whitening-rotation (WR) based semi-blind (SB) scheme for frequency-selective channel estimation in multiple-input multiple-output (MIMO) multi-carrier (MC) CDMA systems. This scheme is based on a low complexity multi-path multi-carrier decorrelator (MMD) receiver structure developed for the MIMO MC-CDMA system. It is shown that the MMD based receiver naturally enables...
This paper addresses the problem of fractional timing offset and channel estimation in Multiple input Multiple output orthogonal frequency division multiplexing (MIMO OFDM) systems. The estimators have been derived assuming a flat fading channel and using the maximum likelihood criterion. Closed form Cramer Rao bound (CRB) expressions for fractional timing offset and channel response are also derived...
In this paper, the estimation of doubly selective channel is considered for amplify-and-forward (AF) relay networks. The complex exponential basis expansion model (CE-BEM) is chosen to describe the time-varying channel, from which the infinite channel parameters are mapped onto finite ones. Since direct estimation of these coefficients encounters high computational complexity and large spectral cost,...
In this paper, the truncated singular value decomposition expectation-maximization (TSVD-EM) based channel estimation on single transmit antenna transmission is extended to transmit diversity transmission. Particular attention is given to Long Term Evolution (LTE) systems. In order to obtain the received symbols for each transmit antenna, an approximation is proposed by using the soft symbols and...
In this paper, we propose a cooperative particle swarm optimization (CPSO) based channel estimation/equalization scheme for multiple-input multiple-output zero-padded single-carrier (MIMO-ZPSC) systems with large dimensions in frequency selective channels. We estimate the channel state information at the receiver in time domain using a PSO based algorithm during training phase. Using the estimated...
In order to maximize the spectral efficiency, the current wireless systems tend to allocate the same frequency resources to different users, which causes the so-called Co-Channel Interference (CCI) on the signal received by the mobile user. If not handled appropriately, CCI may seriously degrade the communication performance. Therefore, for more reliable performance, robust transceiver techniques...
In this work, the problem of receiver design for phase noise estimation and data detection in the presence of oscillator phase noise in a point-to-point multiple-input multiple-output (MIMO) system is addressed. First, we discuss some interesting and challenging aspects in receiver design for MIMO systems in the presence of Wiener phase noise. Then, using the variational Bayesian (VB) framework, a...
We investigate simplified, yet mismatched, receivers for SC-FDMA MIMO transmission currently employed in the 3GPP LTE-Advanced uplink. The receivers are based on frequency domain equalization and time domain detection. Rates achievable by those mismatched receivers with arbitrary input alphabets are derived in terms of generalized mutual information. The results allow to compare the impact of certain...
We consider the problem of designing binary antipodal uniquely decodable (errorless) code sets for overloaded code-division multiplexing applications where the number of signals K is larger than the code length L. Our proposed errorless code set design aims at identifying the maximum number of columns that can be potentially appended to a Sylvester-Hadamard matrix of order L, while maintaining the...
In the next generation cellular systems, such as LTE-A (Release 10 and beyond), relay node (RN) deployment has been adopted due to its potentials in enlarging coverage and increasing system throughput, even with primitive relaying functionalities. For example, in LTE-A Release 10 only Type-I (non-transparent) RNs are considered wherein no cooperative transmission to the Donor evolved-NodeBs (DeNBs)...
We present a flexible class of stochastic models that are developed for cooperative wireless relay networks systems, in which the relay processing functionality is not known at the destination. The challenge is then to perform system identification in this wireless relay network. We first construct a statistical model based on a representation of the system using Gaussian Processes. We then develop...
We design a multiple-access relay network with multiple sources and relays via network coded cooperation where the radio resources in three dimensions: time, space and user are jointly optimized. For this, we derive the decoding error probability of two MIMO modes and develop an optimal MIMO mode selection and power allocation strategy for multiple sources and relays, so as to minimize the decoding...
Deliberate clipping is a simple solution to high Peak-to-Average Power Ratio problem of OFDM signal. In Amplify-and-Forward OFDM relay networks, due to the limited resource, deliberate clipping is also suggested. However, clipping is a nonlinear process and may cause significant performance degradation. Based on Bussgang Linearization Theory, we provide a linear system model for Amplify-and-Forward...
In this paper, the performance of a dual-hop multiple-input multiple-output (MIMO) cooperative multiple-relay network using orthogonal space-time block coding (OS-TBC) transmission is examined. The fading environment is modeled as independent, not identical distributed (i.n.i.d.) Nakagami-m fading. Also, we consider the case that each terminal in the network has multiple-antennas, the relays operate...
For the design and performance evaluation of advanced wireless communication systems employing multiple-input multiple-output (MIMO) technologies, realistic MIMO channel models with a good tradeoff between accuracy and complexity are indispensable. This paper compares the statistical properties of the two latest standardized MIMO channel models: Long Term Evolution-Advanced (LTE-A) and IMT-Advanced...
This paper addresses the problem of feedback design for MU-MIMO (multi-user multiple input multiple output) transmission in 3GPP Long Term Evolution (LTE) systems. The CSI (channel state information)-based feedback introduced in the latest release of LTE, Rel-10 is adopted in MU-MIMO transmission and potential performance gains are demonstrated over Rel-8 CQI/PMI (channel quality indicator/precoding...
In a multi-cell wireless network, an efficient interference mitigation technique is an inevitable part of the current state-of-the-art wireless system. As opposed to conventional interference mitigation techniques which treat the interference as noise, a multi-layer rate splitting scheme can be considered to improve the performance by decoding part of the interference. In this paper, we adapt the...
In the 3rd generation partnership project (3GPP) long term evolution (LTE) time division duplex (TDD) systems, base stations use uplink sounding reference signals (SRSs) to estimate downlink channel state information (CSI) for downlink beamforming transmissions. Because SRSs sent by up to 8 users are multiplexed on the same time-frequency resources, there exist mutual interferences among these SRSs...
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