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This paper deals with the problem of estimating the average signal-to-noise ratio (SNR) for a communication system employing non-coherent binary frequency shift keying (NCBFSK) over fading channels with white Gaussian noise (AWGN). The maximum likelihood (ML) estimator and one using data statistics have been derived and simulated for various scenarios including data-aided (DA), non-data aided (NDA)...
In this paper, we consider the problem of multifunctional compression with side information. The problem is how we can compress a source X so that the receiver is able to compute some deterministic functions f1 (X,Y1), ..., fm(X,Ym), where Yi, 1 ? i ? m, are available at the receiver as side information. In, Wyner and Ziv considered this problem for the special case of m = 1 and f1(X, Y1) = X and...
This paper proposes a new hybrid structure for the practical MIMO receiver. The receiver operates in a QRMLD mode by default and achieves near-optimal performance. On the other hand, when the communication environment is not so favorable for a QR-MLD, it switches to a QR-MMSE mode and saves the mobile computing power. Using a common structure of QR decomposition from both receivers and the novel QR-MMSE...
This paper proposes a novel receiver scheme for multiple-input multiple-output (MIMO) systems with hybrid-automatic-retransmission-request (HARQ) mechanism. The proposed scheme improves the decoding performance by characterizing and counteracting uncertainty of the soft decisions. Furthermore, the proposed scheme can make full use of the received signals and especially performs well when the prior...
A new method for detecting packet-based OFDM signals in the presence of phase noise is presented. The scattered pilots in each data OFDM symbol are used to non-iteratively estimate and mitigate the phase noise induced inter-carrier interference (ICI). A significant improvement in the bit error rate (BER) is achieved using this technique, especially for systems suffering from high phase noise.
For a multi-user interference channel with multi-antenna transmitters and single-antenna receivers, by restricting each receiver to a single-user detector, computing the largest achievable rate region amounts to solving a family of nonconvex optimization problems. Recognizing the intrinsic connection between the signal power at the intended receiver and the interference power at the unintended receiver,...
We consider the problem of maximum likelihood (ML) signal detection in multiple-input multiple-output (MIMO) wireless communication systems. We propose a new preprocessing algorithm in the form of channel ordering for sphere decoders. Numerical results show that this new channel ordering leads to significantly lower complexity (in the form of the number of nodes visited by the search algorithm); for...
This paper discusses the application of iterative versus adaptive equalizers to a universal mobile telecommunications system (UMTS) high speed downlink packet access (HSDPA) receiver. Among the investigated algorithms are the least mean square (LMS) and recursive least square (RLS) algorithms and their adaptations to code division multiple access (CDMA), such as Griffith's algorithm, as well as the...
In this paper, we present a novel iterative receiver for MIMO-OFDM systems with synchronous interferers. The receiver is derived based on the Kullback-Leibler divergence minimization framework, and combines channel estimation, interference cancellation and residual noise estimation in an iterative manner. By using both the pilot and data symbols, the channel estimator improves the accuracy of the...
In this paper, we propose a novel low complexity two-stage minimum mean square error (MMSE)-based receiver for single carrier frequency-domain equalization (SC-FDE) for space-time block coded (STBC) transmissions over frequency selective channels. We demonstrate that the proposed receiver enjoys a remarkably simple decoding scheme. We further show that, by incorporating linear processing techniques,...
In many dynamic spectrum access networks, it is necessary for secondary users to monitor the frequency band in which they are communicating so that they can determine if the primary user has begun transmission. Traditional sensing methods require the transmitters of the secondary users to be silent while spectrum monitoring is performed. Statistics that are derived easily in a communications receiver...
In this paper, we introduce the three-user cognitive radio channels with asymmetric transmitter cooperation, and derive achievable rate regions under several scenarios depending on the type of cooperation and decoding capability at the receivers. Two of the most natural cooperation mechanisms for the three-user channel are considered here: cumulative message sharing (CMS) and primary-only message...
Video streaming over wireless links is a challenging problem due to both the unreliable, time-varying nature of the wireless channel and the stringent delivery requirements of media traffic. Layered encoded video can be used to improve the system performance by adapting the sending rate for different video frame layers to the varying network and playout situations. In this paper, we study the adaptive...
There have been a number of TCP variants proposed in the literature to combat random packet losses in wireless networks. In this paper we first perform a simulation study on the performance of these TCP variants in the context of IEEE 802.11 WLAN with various channel conditions, generated using different wireless error models and show that none of the existing TCP variants has superior performance...
Transmitter preceding is a crucial technique for harnessing the potential of multiple-input multiple-output (MIMO) fading channels. In many practical wireless systems, a limited amount of feedback from the receiver is available at the transmitter, which can be used to direct the choice of the precoder from a codebook to match the channel state. Assuming noiseless, limited-rate feedback, this work...
In this paper, we consider transmission of two correlated Gaussian sources to two receivers through a two-user Gaussian Z interference channel (Z IC). To facilitate our study, we first investigate Gaussian multiple access channels with correlated Gaussian sources and a single distortion constraint at the receiver. Lower bounds on the distortion as well as several achievable schemes are proposed. In...
Transmitter Leakage has a significant impact on the system performance in mobile devices using zero-IF receivers and thus requires a suitable compensation. In contrast to analog approaches, digital Tx Leakage compensation approaches can easily be reconfigured and therefore are highly attractive for future mobile devices, using software defined radios. In this contribution we present a digital Tx Leakage...
This paper introduces a new framework of the multiple-input multiple-output (MIMO) detection in iterative receivers. Unlike the conventional methods processing with symbol lattice, we consider the delta symbol lattice, i.e., the difference between two arbitrary points in the symbol lattice. The inherent flexible, symmetric, and sparse properties of the delta lattice enhance the detection in both complexity...
In this paper, we introduce a novel queue management technique for the buffer space at the base station of infrastructure 802.11 networks that considers mobile user's receiving characteristics. The maximum amount of the base station buffer that can be used by a given flow is updated proportionally to RTT, measured at the mobile nodes and sent to the base station my the mean of link layer acknowledgements...
In this paper, carrier frequency offsets (CFOs) are considered in a layered frequency-domain equalization (LFDE) architecture for a single carrier (SC) broadband wireless multiple-input multiple-output (MIMO) system. At each layer of detection, a group of best data streams are selected to be equalized and reliably detected via removing the phase and amplitude distortion caused by the multiple CFOs...
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