Serwis Infona wykorzystuje pliki cookies (ciasteczka). Są to wartości tekstowe, zapamiętywane przez przeglądarkę na urządzeniu użytkownika. Nasz serwis ma dostęp do tych wartości oraz wykorzystuje je do zapamiętania danych dotyczących użytkownika, takich jak np. ustawienia (typu widok ekranu, wybór języka interfejsu), zapamiętanie zalogowania. Korzystanie z serwisu Infona oznacza zgodę na zapis informacji i ich wykorzystanie dla celów korzytania z serwisu. Więcej informacji można znaleźć w Polityce prywatności oraz Regulaminie serwisu. Zamknięcie tego okienka potwierdza zapoznanie się z informacją o plikach cookies, akceptację polityki prywatności i regulaminu oraz sposobu wykorzystywania plików cookies w serwisie. Możesz zmienić ustawienia obsługi cookies w swojej przeglądarce.
Machine learning based link optimization of wireless communications often relies on past experience, accurate estimation of channel conditions, and theoretical performance models. Typically, theoretical models poorly match given situations, past experiences are limited, and spectrum sensing of noise and channel conditions pose many hurdles. Hence, traditional cognitive radio engines based on genetic...
This paper deals with the retransmission protocol design for cognitive radio networks by exploiting the primary hybrid ARQ. In contrast with previous work that focuses on cancellation based retransmissions, we propose a novel cooperative coding based retransmission protocol for cognitive radio networks. The design objective is to improve the throughput of the primary user and create the transmission...
We describe performance results for a Dynamic Spectrum Management (DSM) Platform, including over-the-air data captured outdoors near our Melville, NY facility and in an indoor office environment. The DSM system configuration used to generate the results, and the flexibility of the DSM system that allows it to operate in different bandwidth TV channels are presented. The results include data throughput,...
We propose a three-message superposition coding scheme in a cognitive radio relay network exploiting active cooperation between primary and secondary networks. The time resource is split into three transmission phases. The first two phases are dedicated to primary communication, while the third phase is for the secondary's transmission. We formulate a throughput maximization problem for the secondary...
Orthogonal frequency division multiplexing (OFDM) is a recognized transmission technique for Cognitive radio (CR) systems but one of the major draback of OFDM scheme is its out-of-band (OOB) leakage due to high spectral sidelobes. In this paper we propose a sidelobe suppression technique using a differential coding. The concept working behind the scheme is polynomial-cancellation-coding (PCC) in which...
Distributed communication has a great potential to become a promising foundation for future cognitive radio networks regarding its ability to provide a reliable multimedia transmission under lossy and delay constrained conditions. In this paper, we explore a novel distributed system for cognitive radio networks relying on the concept of multiple description coding for the more realistic case where...
In this paper, we propose, analyse and compare three different methods for opportunistic spectrum sharing access when the primary users implements an Incremental Redundancy (IR) type Hybrid Automatic ReQuest (H-ARQ) protocol. The first method consists in allowing the secondary user to communicate only during the first primary transmission round of the IR H-ARQ protocol. In this scenario, if the the...
Orthogonal frequency-division multiplexing (OFDM) is a candidate transmission technique for cognitive radio (CR) because of its flexible nature to support spectrum sharing. However, the out-of-band (OOB) radiation of OFDM signal from CR users must be strictly controlled to protect licensed users in adjacent bands. In this paper, we propose a spectral precoding scheme for multiple OFDM-based CR users...
In Cognitive Radio (CR) networks, it is common that the spectrum holes are too narrow to support high-speed communications. Discontinuous Orthogonal Frequency Division Multiplexing (DOFDM) is a good way for a secondary user to access several spectrum fragments simultaneously with one Radio Front (RF). In this paper, a novel Channel Characteristic Aware Spectrum Aggregation (CCASA) algorithm which...
The cooperation among the secondary users or among the secondary users and the primary users have proven to bring many benefits to both primary and secondary users in cognitive radio networks. In this paper, cooperative relaying in cognitive radio networks is studied for rateless coding error-control mechanism. For a pair of primary transmitter and receiver, we find the region in which any secondary...
In this paper we investigate the use of rateless codes by secondary users equipped with cognitive radio in a virtual unlicensed spectrum. Assuming a Poisson model for the arrival of primary users, we analyze the goodput and the throughput of secondary users. Rateless codes are used for transmitting the secondary data through parallel subchannels available in a spectrum. They can compensate for the...
Applying data-centric and cognitive techniques in the space communications infrastructure promises, by managing and even exploiting complexity, to enhance performance and operational efficiency and to enable future science and exploration operational concepts that require flexible and adaptive communications and networking not currently available.1 2 The paper presents a novel approach to decomposing...
In this paper, we provide a new perspective and insight into the process of finding the maximal performing method using a Cognitive Engine (CE) for link adaptation. It is found that near maximal performance can be reached relatively fast, even when a small number of the available communication methods provide adequate performance. The parameters that affect the expected number of trials are fully...
Cognitive radio is an emerging technology that allows secondary communication in a frequency band originally allocated to one or more primary users (PUs). Secondary user (SU) usually operates in a low power profile to avoid interference with the PU and sudden appearance of a PU causes loss of data of the SU. Appropriate erasure correction coding (also called as anti-jamming coding) is, thus, required...
Existing spectrum management policies have led to significant over-allocation and under-utilization of the licensed spectrum. To overcome this, cognitive radio is proposed for secondary users to share the licensed spectrum without causing harmful interference to primary users. As such, the transmit power of a secondary user is limited even when it accesses the spectrum hole. Therefore, multihop transmission...
In this paper, we propose an optimal TCP throughput framework to optimize the TCP throughput in CR networks, which jointly considers the channel sensing decision and access policy as well as low layer design parameters. The TCP throughput optimization is achieved by a two step process. First, we select a channel to maximize the spectrum utilization by reducing the probability of collision with primary...
We introduce simple yet efficient ARQ protocols in conjunction with two types of anti-jamming coding techniques - rateless coding and piecewise coding - for cognitive radios. For piecewise coding, we propose to employ systematic codes to facilitate efficient selected retransmissions and design short codes to maximize secondary user throughput. For rateless coding, we consider a protocol that transmits...
Cognitive radios have been proposed as a means to implement efficient reuse of the licensed spectrum. Commonly, wireless networks are characterized by a fixed spectrum assignment policy. The limited available spectrum and the inefficiency in the spectrum usage necessitate a new communication paradigm to exploit the existing wireless spectrum opportunistically. We consider a simple single-cell scenario...
Because of its flexible spectrum shaping, OFDM technologies can be used for cognitive radio as signaling method. Spectrum notches can be generated through turning off subcarriers to protect primary users (licensee users), but the intercarrier interference may limit the notch depth. This paper focuses on the enhancing methods to deepen spectrum notch and proposes two kinds of OFDM subcarriers coding...
Podaj zakres dat dla filtrowania wyświetlonych wyników. Możesz podać datę początkową, końcową lub obie daty. Daty możesz wpisać ręcznie lub wybrać za pomocą kalendarza.