The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
In multiple-input multiple-output (MIMO) systems adopting space shift keying (SSK), the use of adaptive precoder on transmitter offers the opportunity to improve its performance significantly. One major challenge in precoder operation is the difficulty in obtaining the full channel state information on transmitter (CSIT). In this work, we investigate the precoder design for SSK-MIMO systems with limited...
Interference alignment (IA) is a scheme to achieve degrees of freedom (DOF) of interference network at high signal-to-noise ratio (SNR). In order to implement IA scheme in frequency-division duplexing (FDD) system, receivers feedback channel state information to transmitters. The key problem is to acquire accurate transmitter channel state information (CSIT) in the presence of the quantization error...
We present a novel approach to network security against passive eavesdroppers by employing a configurable beam-forming technique to create tightly defined regions of coverage for targeted users. In contrast to conventional encryption methods, our security scheme is developed at the physical layer by configuring antenna array beam patterns to transmit the data to specific regions. It is shown that...
To communicate over a priori unknown channels, pilot sequences can be exploited to assist the receiver in obtaining the channel state information. The analog-to-digital converter (ADC) at the front end of the receiver samples and quantizes the input signal, including both pilot and data symbols. This results in a reduction of the receive signal-to-noise ratio (SNR) as well as deteriorated quality...
In this study, we propose a robust transceiver scheme with switched preprocessing (SP) for K-user multiple-input multiple-output (MIMO) interference channels. The channel state information (CSI) available is assumed to be imperfect under norm-bounded errors (NBE). Each transmitter is provided with a codebook of permutation matrices, so that each arrangement of permutation matrices among the K transmitters...
To solve mobile traffic crunch, the usage of enormous bandwidth in millimeter wave (mm-Wave) is under discussion. In this paper, we investigate radio channel characteristics of mm-Wave frequency in the downtown area of Ottawa using 3D ray-tracing technique. In the results, important parameters of the radio channel model, such as path loss exponent, shadow fading, delay spread and angle spread, are...
In this paper we propose a coding and decoding strategy for computing modulo M sums in a Multiple Access Channel over Additive White Gaussian Noise based on linear codes in FM. The complexity of our strategy is the same as the complexity of the linear code and we show that when there are 2 users in the network and M = 2, our strategy is close to the theoretical limit. We also provide some figures...
Localization errors can play an important role in measurements of radio propagation or spectrum utilization, especially in urban environment where GPS localization accuracy is highly varying. In this paper we present a low cost and simple method for mitigating the impact of localization errors, based on multiple GPS receivers. The presented results are based primarily on performance evaluation of...
We study the problem of wireless communication over indoor pulsed terahertz (THz) channels. First, we characterize the THz channel using measurements and derive a channel model. This channel model is then implemented in a Matlab simulator that we use to study different modulation schemes. In this paper, our focus is on examining frequency-domain differential phase shift keying (FD-DPSK) modulation...
In this paper, we consider a single user block fading communication system where both the transmitter and receiver have multiple antennas. A transmission block is divided into training and data transmission phases. The channel estimation at the receiver is noisy. The transmitter has long term statistics of the estimated channel in the form of a covariance matrix. The general problem is to find optimum...
Interference alignment (IA) is a transmission technique for exploiting all available degrees of freedom (DoF) in the frequency- or time-selective interference channel with an arbitrary number of users, which can achieve linear capacity scaling with number of users. However, standard IA approach has limit performance in the low-to-moderate signal-to-noise ratio (SNR) region. Recently, linear combination...
In this paper, we investigate robust precoding for two-way relay cognitive networks consisting of a pair of cognitive transceiver users equipped with Multiple Input Multiple Output (MIMO) antenna communicating with each other through a common multi-antenna relay and sharing the same spectrum with primary users (PU). The uncertainty set in this CSI model is defined as Norm Bounded Error (NBE) model...
In this paper we study the performance of two-way relaying (TWR) over underwater acoustic (UWA) channels in conjunction with distributed space-time block coding (D-STBC). In particular, we consider the communication between two sources via relay nodes. The underlying channels are characterized as doubly selective channels. Orthogonal frequency division multiplexing (OFDM) is used to combat frequency...
Due to spectrum constraints most of cellular networks are deployed in frequency reuse one. In that scenario co-channel interference from neighboring cells becomes a limiting factor for the performance of all downlink physical channels. Therefore, the problem of interference suppression is being considered as one of the most important issues of modern wireless communication systems. In Long-Term Evolution...
Two-tier heterogeneous wireless networks are considered in this paper where nodes in the first tier are distributed as a Poisson Point Process (PPP). Nodes in the second tier are distributed as a Poisson Clustered Process (PCP). Nodes in the second tier have imperfect channel state information (CSI) of the first tier node whose Voronoi cell they are in. On one hand, cross-tier interference is coordinated...
This paper presents a robust and low-complexity non-linearity suppression scheme for radio frequency (RF) transceiver building blocks to efficiently mitigate intermodulation distortion. The scheme consists of tunable RF components assisted by an auxiliary path equipped with an adaptive digital signal processing algorithm to provide the tuning control. This proposed concept of digitally-assisted tuning...
Narrowband interference (NBI) is a known problem in wireless communications. However, analyses found in the NBI literature often model the signal of interest as a generic transport channel with all subcarriers conveying information of the same kind, e.g. user plane data. By taking the analysis down to physical channels' level, this paper aims to obtain a deeper understanding of the impact exerted...
In wireless interference networks, orthogonal medium access techniques like time division multiple access (TDMA) and frequency division multiple access (FDMA) achieve merely one degree of freedom (DoF). However, by using interference alignment (IA) the achievable DoF can be linearly scaled up with the number of users. Nevertheless, this outperformance of IA heavily depends on the availability of perfect...
In this paper we consider a decode-and-forward cooperative network, which is active in the same bandwidth as a primary user network. The cooperative or secondary user network applies a dynamic resource allocation algorithm to maximize its own performance while limiting the interference caused at the primary user receivers. The main contribution of this paper is the proposition of a new accurate approximation...
In this paper, we investigate the performance of cognitive multiple decode-and-forward relay networks under the interference power constraint of the primary receiver wherein the cognitive downlink channel is shared among multiple secondary relays and secondary receivers. In particular, only one relay and one secondary receiver which offers the highest instantaneous signal-to-noise ratio is scheduled...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.