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Emerging standards in Cognitive Radio seek to alleviate the problem of spectrum scarcity by leveraging spectrum under-utilization through dynamic spectrum access (DSA). Unlicensed users (“secondary”) may opportunistically make use of channels during times when the licensed (“primary”) user is absent. The “open access” paradigm proposed by FCC mandates the study of primary-secondary dynamics, as well...
Spectrum shortage and low spectrum utilization have attracted much attention. In order to meet the communication demands of users, the dynamic and efficient spectrum management scheme with cognitive radio technology has been used. Spectrum share is the key component in the dynamic spectrum management. To enable cognitive user (CU) to share spectrum fairly, an evolutionary game-based spectrum sharing...
This paper presents a bandwidth allocation and pricing framework for the spectrum underlay in cognitive radio networks. We assume that a cognitive radio network containing a set of primary users coexists with secondary users in an underlay spectrum sharing paradigm. Primary users use licensed bands of the spectrum while secondary users choose among the bands available on sale based on their prices...
We propose a cooperative spectrum sharing strategy in which the secondary system can access to the licensed spectrum of the primary system if it can help the primary system achieve the target rate. Specifically, the secondary system acts as a decode-and-forward relay for the primary system by splitting a fraction of its transmission bandwidth to help forward primary signal. It uses the remaining bandwidth...
In recent years, the problem of spectrum mobility in Cognitive Radio (CR) Networks has been widely investigated. In order to fully utilize spectrum resources, many spectrum handoff techniques based on game theory have been proposed, but most studies only concern how to achieve better payoffs for users, without paying much attention to the Quality of Service (QoS). Thus, we propose a new channel switching...
This paper proposes the use of an overloaded hybrid MC-CDMA system to improve the spectral efficiency of Cognitive Radio (CR) network. The overlay transmission in the unused parts of the spectrum is full-loaded MC-CDMA signals with scrambling. The underlay signal, using a separate scrambling code from the overlay signals, utilizes the whole spectrum taking into account of the interference threshold...
Spectrum auction has been considered as an economically incentive way to motivate both primary spectrum owners (POs) and secondary users (SUs) to participate in dynamic spectrum access (DSA). In this paper, we propose a new combinatorial spectrum auction framework for the scenarios that each PO has multiple channels to sell and each SU demands multiple channels. Moreover, the heterogeneity in terms...
In this paper we consider a cognitive radio network with access to N licensed primary frequency bands and their usage statistics, where the decentralized secondary users are subject to certain inter-network interference constraint. In particular, to limit the interference to the primary network, secondary users are equipped with spectrum sensors and are capable of sensing and accessing a limited number...
The paper investigate the cognitive radio opportunity to utilize Television White Spaces (TVWS) spectrum in Malaysian urban areas according to time and location. Data has been collected from eight different urban areas in Malaysia to measure the spectrum occupancy and received signal strength level. Channel bonding is a technique of searching and combining unoccupied contiguous channels, which resulted...
This paper proposes a cooperation protocol between a secondary user (SU) and a primary user (PU) which dedicates a free frequency subband for the SU if cooperation results in energy saving. Time is slotted and users are equipped with buffers. Under the proposed protocol, the PU releases portion of its bandwidth for secondary transmission. Moreover, it assigns a portion of the time slot duration for...
In recent years Cognitive radio and UWB technologies are emerging for efficient use of Spectrum for short range wireless communications. FCC also has released a wideband of 7.5 GHz (From 3.1GHz to 10.6GHz) as unlicensed to use it anytime anywhere. In cognitive radio for sensing purpose and in UWB transceiver, UWB antennas play a vital role. Since antenna dimensions are frequency dependent, designing...
In cognitive radio networks, the available spectrum holes are usually discontinuous. Hence, it is hard to exploit these spectrum holes because the bandwidth of an individual one may not be able to satisfy the wide bandwidth requirement imposed by secondary users (SUs). Spectrum aggregation (SA) enables SUs to integrate several spectrum holes into one channel with wide bandwidth which may support high...
A single cognitive radio transmitter-receiver pair shares the spectrum with two primary users communicating with their respective receivers. Each primary user has a local traffic queue, whereas the cognitive user has three queues; one storing its own traffic while the other two are relaying queues used to store primary relayed packets admitted from the two primary users. A new cooperative cognitive...
In this paper, we consider a cellular based primary network coexisting with a secondary network. The primary network consists of multiple service providers (SP) and there are several independent users in the secondary network. The SP are operating on the different frequency spectrum and a group of secondary users intend to share these spectrum with the primary services. This situation is formulated...
Recently cognitive radio has gain considerable interest by research community as a viable solution to mitigate the problems of spectrum scarcity and spectrum under-utilization. A cognitive radio selects a vacant channel opportunistically and perform its own transmission on it. Detecting an incumbent user along with self-coexistence has become one of the important aspects of the cognitive radio. The...
Today, and especially in the future, there is an increasing need for complementary techniques to meet the growing capacity requirements of wireless communications. A high data rate connection with power line communication (PLC) is one attractive solution to achieve this need. One way to improve the data rates obtained in PLC networks is to increase the used bandwidth and operate at higher frequencies...
An ultra-wideband (UWB) rectangular dielectric resonator antenna (DRA) integrated with a narrow-band (NB) DRA is presented. The proposed antenna consists of a UWB rectangular DRA excited by a bevel-shaped patch and a NB DRA excited by a strip. The simulated results demonstrate that the UWB antenna provides a 2:1 voltage standing wave ratio (VSWR) bandwidth for 2.5–12 GHz, integrated with a NB antenna...
Cognitive Radio is a novel technology that can potentially improve the utilization efficiency of the radio spectrum by opportunistically using the unused frequency bands. Spectrum sensing is the key function of cognitive radio technology. However, detection is compromised when a user experiences shadowing or fading effects. In such cases, user cannot distinguish between an unused band and a deep fade...
Cognitive radio radio networks employing distributed spectrum sensing techniques will need inexpensive, highly compact spectrum sensing front-ends. This paper presents a highly compact approach utilizing three custom radio-frequency integrated circuits realized in a 0.25 µm Si/SiGe:C BiCMOS technology, replacing a larger number of off-the-shelf components more commonly used. It provides more than...
Increasing the flexibility in spectrum access is a key to enhanced efficiency in radio spectrum utilization. Noncontiguous carrier aggregation (CA) is one enabling technology towards more flexible spectrum access, but can also lead to serious implementation challenges in terms of transmitter lin-earity. Especially when a single power amplifier (PA) is deployed for all carriers, serious intermodulation...
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