Throughput maximization is one of the main challenges in cognitive radio <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ad hoc</i> networks, where availability local spectrum resources may change from time to and hop by hop. For this reason, a cross-layer opportunistic access dynamic routing algorithm for networks proposed, which called spectrum-allocation (ROSA) algorithm. Through control actions, ROSA aims maximize network throughput performing...

In this paper, we consider a heterogeneous ad-hoc network where primary users may cooperate with cognitive radio (CR) for the transmission of their data. We propose new cooperation protocol that allows CR to relay user signals in exchange some spectrum. The spectrum released by is used own data transmission. proposed maximizes power savings and users' rate. addition, it provides more robust (potentially continuous) service users, compared conventional practice networks transmit holes (i.e.,...

We review and discuss the challenges of adopting software-defined radio principles in underwater acoustic networks, propose a modem prototype based on commercial off-the-shelf components. first current SDR-based architectures for communications. Then we describe architecture new prototype, provide performance evaluation results both indoor (water tank) outdoor (lake) environments. present three experimental testbed scenarios that demonstrate real-time reconfigurable capabilities proposed...

There is an emerging need for high-rate underwater acoustic (UW-A) communication platforms to enable a new generation of monitoring applications including video streaming. At the same time, modern UW-A architectures be flexible adapt and optimize their parameters in real time based on environmental conditions. Existing modems are limited terms achievable data rates ability protocol stack time. To overcome this limitation, we present design, implementation, experimental evaluation...

Direct-sequence/code-division multiple-access (DS/CDMA) communication systems equipped with adaptive antenna arrays offer the opportunity for jointly effective spatial and temporal (code) interference (MAI) channel noise suppression. This work focuses on development of fast joint space-time (S-T) optimization procedures that may keep up fluctuation rates multipath fading channels. Along these lines, familiar S-T RAKE processor is a single orthogonal auxiliary vector (AV) selected under...

Terahertz (THz)-band (0.1 THz to 10 THz) communication is envisioned as a key technology meet the demand for faster, more ubiquitous wireless networks. For many years, lack of compact, fast and efficient ways generate, modulate, detect demodulate THz-band signals has limited feasibility such systems. Recently, major progress within different device technologies finally closing so-called gap. time being, testbeds have been developed at sub-THz frequencies, i.e., or near boundary with...

When the auxiliary vector (AV) filter generation algorithm utilizes sample average estimated input data statistics, it provides a sequence of estimates ideal minimum mean-square error or minimum-variance distortionless-response for given signal processing/receiver design application. Evidently, early nonasymptotic elements offer favorable bias/variance balance characteristics and outperform in estimation unbiased matrix inversion (SMI) estimator as well (constraint) least-mean square,...

Throughput maximization is one of the main challenges in cognitive radio ad hoc networks, where local spectrum resources may change from time to and hop-by-hop. For this reason, a cross-layer opportunistic access dynamic routing algorithm for networks proposed, called ROSA (ROuting Spectrum Allocation algorithm). Through control actions, aims at maximizing network throughput by performing joint routing, allocation, scheduling, transmit power control. Specifically, dynamically allocates...

Throughput maximization is one of the main challenges in cognitive radio ad hoc networks, where availability local spectrum resources may change from time to and hop-by-hop. Cooperative transmission exploits spatial diversity without multiple antennas at each node increase capacity with reliability guarantees. This idea particularly attractive wireless environments due diverse channel quality limited energy bandwidth resources. With cooperation, source relay cooperatively transmit data...

In this paper we develop a new analytical methodology for the evaluation of outage probability cooperative decode-and-forward (DF) automatic-repeat-request (ARQ) relaying under packet-rate fading (fast or block fading) channels, where channels remain fixed within each ARQ transmission round, but change independently from one round to another. We consider single relay forwarding Alamouti-based retransmission signals in scheme. particular, (i) derive closed-form asymptotically tight (as SNR →...

We consider the problem of extracting blindly data embedded over a wide band in spectrum (transform) domain digital medium (image, audio, video). develop novel multicarrier/signature iterative generalized least-squares (M-IGLS) core procedure to seek unknown hidden hosts via multicarrier spread-spectrum embedding. Neither original host nor embedding carriers are assumed available. Experimental studies on images show that developed algorithm can achieve recovery probability error close what...

Cooperative communication has emerged as a new wireless network concept, in which parameter optimization such power budget and time allocation plays an important role cooperative relaying protocol designs. While most existing works on designs considered equal-time scenario, i.e., equal duration is assigned to each source relay, this work we intend design optimize protocols by exploring all possible variations domains. We consider no channel state information (CSI) available at the...

We review commercially available software- defined radio platforms and classify them with respect to their ability enable rapid prototyping of next-generation wireless systems. In particular, we first discuss the research challenges imposed by latest software-defined enabling technologies including both analog digital processing hardware. Then present state-of-the-art commercial platforms, describe software hardware capabilities, based on advance experimental in networking. Finally, three...

The conventional signature-matched RAKE processor for multipath direct-sequence code division multiple access channels is viewed as a regular linear tap-weight filter of length equal to the sum system processing gain and user channel memory. In this paper, performance improvements are sought in context adaptive filtering under maximum signal-to-interference-plus-noise-ratio criteria. minimum-variance-distortionless-response (RAKE-MVDR) lower complexity scalar optimized auxiliary-vector...

In this work, a cognitive cooperative communication protocol is proposed for ad-hoc networks, in which primary users and radio (CR) may cooperate mutual benefit. The new cooperation allows active between CR assist to relay users' signals exchange some spectrum released from the users. While conventional radios do not guarantee continuous operation of (they use only when not), work provides service optimized terms maximizing user's energy savings own data transmission rate. It turns out that...

This article describes the design of a custom software-defined modem with adaptive physical layer for underwater acoustic (UWA) communications. The consists commercial radio (SDR) interfaced wideband transducer through amplifying circuitry. With this custom-built platform, we focus on unique challenges channel to demonstrate benefits real-time adaptation in such rapidly varying environments. We first an Orthogonal-Frequency-Division-Multiplexing (OFDM) transmission scheme. In particular,...

Wireless physical-layer security is an emerging field of research aiming at preventing eavesdropping in open wireless medium. In this paper, we propose a novel waveform design approach to minimize the likelihood that message transmitted between trusted single-antenna nodes intercepted by eavesdropper. particular, with knowledge first eavesdropper's channel state information (CSI), find optimum and transmit energy signal-to-interference-plus-noise ratio (SINR) output maximum-SINR linear...

Receiver architectures in the form of a linear filter front-end followed by hard-limiting decision maker are considered for DS-CDMA communication systems. Based on stochastic approximation concepts recursive algorithm is developed adaptive optimization minimum BER sense. The driven and distribution free. For additive white Gaussian noise (AWGN) channels, theoretical analysis surface receivers identifies subset space where optimal receiver lies offers formal proof guaranteed global with...

A fresh look on the design of practical low-complexity direct-sequence code-division multiple-access (DS/CDMA) receivers is proposed from Wiener reconstruction-filter point view. The natural outcome emergence a new class linear scalar-parameterized auxiliary-vector (filters). Then, blind optimization these in maximum signal-to-interference-plus-noise-ratio (SINR) sense becomes straightforward procedure. conceptual and computational simplicity this general approach promises immediate utility....

In this paper, the capacity of airborne multiple-input-multiple-output (MIMO) wireless communication systems with arbitrary alignments linear transmit and receive antenna arrays is systematically analyzed maximum achievable determined. Based on a general three-dimensional (3D) MIMO model, we are able to approximate as function array geometry in 3D space. The approximation asymptotically tight distance between large compared their size. approximation, derive an upper bound well lower...

We design, develop, and experimentally validate a complete integrated software/hardware platform for airborne cognitive networking in both indoor outdoor environments. first present the concept of all-spectrum describe distributed algorithm maximizing network spectral efficiency by jointly optimizing channel access code-waveforms routes multi-hop network. then discuss system design parameters implementation details setting up software-defined radio (SDR) testbed that enables...

We consider the problem of cognitive code-division channelization (simultaneous power and code-channel allocation) for secondary transmission links co-existing with an unknown primary multiple-access (CDMA) system. first develop a blind primary-user identification scheme to detect binary code sequences (signatures) utilized by users. To create link we propose two alternative procedures -one moderate one low computational complexity- that optimize transmitting assignment in accordance...

In this paper, low-complexity joint power assignment algorithms are developed for multi-source multi-destination relay networks where multiple sources share a common that forwards all received signals simultaneously to destinations. particular, we consider the following optimization strategies: (i) Minimization of total transmission and under constraint signal-to-interference-plus-noise ratio (SINR) requirement each source-destination pair is satisfied, (ii) Maximization minimum SINR among...

We consider the problem of compressed sensing and propose new deterministic low-storage constructions compressive sampling matrices based on classical finite-geometry generalized polygons. For noiseless measurements case, we develop a novel exact-recovery algorithm for strictly sparse signals that utilizes geometry properties polygons exhibits complexity depends sparsity value only. In presence measurement noise, recovery generalized-polygon sampled can be carried out effectively using...

We consider a secondary multi-hop cognitive radio network with decentralized control that operates cognitively to coexist primary users. propose new spread-spectrum management paradigm, in which, unlike mainstream dynamic spectrum access research, digital waveforms are designed occupy the entire available spectrum, and adaptively track interference profile at receiver maximize link capacity while avoiding In this context, we study problem of maximizing throughput through joint routing...