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Cognitive radio (CR) technology allows devices to opportunistically use the vacant portions of the licensed wireless spectrum. However, the available spectrum changes dynamically with the primary user (PU) activity, necessitating frequent PU sensing coordination and exchanging network topology information in a multihop CR ad hoc network. To facilitate these tasks, an always-on, out-of-band common...
In this paper, we propose a novel channel selection algorithm for a cognitive radio system that coexists with legacy wireless LAN systems operating in the ISM bands. The cognitive system is capable of scanning its environment to measure ISM channel occupancy in terms of WLAN channel utilization. The system takes the opportunity of spectrum availability to facilitate its communication to the cognitive...
A cognitive network consists of primary nodes, which have priority access to the spectrum, and cognitive (also referred to as secondary) nodes, which access the spectrum provided that the interference they generate in the primary system remains limited. In practice, it means that the cognitive terminals must remain outside of a region surrounding the primary receiver: the primary exclusive region...
In Cognitive Radio Networks (CRN), nodes can switch to different operating frequency bands and adapt their transmission power levels such that Cognitive Radio (CR) nodes transmissions remain transparent to the Primary Radios (PR). This constraint can be assured by keeping the aggregated interference caused by CR transmissions at PR nodes location below a defined threshold. In this paper, we propose:...
Due to the license-exempt nature of the cognitive radio (CR), multiple CR networks may operate (coexist) on the same channel. In this paper, we first discuss some techniques for self-coexistence of CR local and personal area networks, where the self-coexistence means the coexistence of homogeneous CR networks using the same PHY/MAC protocol. Then, we propose a self-coexistence etiquette for the ECMA...
This paper considers a distributed power allocation scheme for sum-rate-maximization under cognitive Gaussian multiple access channels (GMACs), where primary users and secondary users may communicate under mutual interference with the Gaussian noise. Formulating the problem as a standard nonconvex quadratically constrained quadratic problem (QCQP) provides a simple distributed method to find a solution...
Multiple Input Multiple Output (MIMO) opens new challenges to be exploited in Cognitive Radio (CR) by simultaneously serving several users. The spatial domain that is added through MIMO is another system resource that has to be optimized, and shared when possible. In this paper, we present a spatial sharing approach that is carried out through Zero Forcing beamforming (ZFB). Statistical assessment...
Cognitive radios (CRs) receive several users simultaneously. Therefore, the ADC of an CR requires a large dynamic range (DR) to guarantee adequate resolution per user. Thus far the ADC DR requirements have been prohibitive for the wide spread introduction of CR in the hand held market. The power consumption of an ADC reduces with an order of magnitude per decade. In the absence of disruptive new technologies,...
Cognitive wireless mesh networks have great potential to green communication. One of the critical challenges for realizing such networks is how to adaptively match transmit powers and allocate frequency resources among secondary users of the licensed frequency bands whilst maintaining the quality-of-service (QoS) requirement of the primary users, even in mutually entangled interferences environment...
Recently, the concept of self-organization has drawn considerable attention for its possible use in distributed interference management. To realize self-organized interference management, a minority game (MG) is a promising tool because it facilitates self-organized decision-making. Although the existing interference management scheme that involves the use of an MG achieves transmission control aware...
This paper addresses the spectrum-sharing for wireless communication with a licensee-primary and a secondary users interfering with each other. We propose a new practical power control policy for the secondary user, under outage performance requirements for both users, with partial knowledge of channel state information.
We propose an opportunistic channel access scheme for cognitive radio-enabled secondary networks. In our work, we model the channel occupancy due to Primary User (PU) activity as a 2-state Alternating Renewal Process, with alternating busy and idle periods. Once a Secondary Node (SN) senses the channel idle, the proposed scheme uses the residual idle time distribution to estimate the transmission...
Spectrum sensing is a critical step in cognitive radio to learn the radio environment. Despite its long history, in recent years spectrum sensing has attracted substantial interests from the cognitive radio community as well as other areas. Although there have been many methods, most of them need some idealistic assumptions and are hardly applicable in real cognitive radio practice. In this paper,...
In order to overcome the indoor coverage problem for residential users, the deployment of home base stations (also referred as home-eNB) has been regarded as a promising solution. However, the unpredictable deployment pattern of home-eNBs makes centralized network planning impractical and requires distributed spectrum planning to achieve effective interference management. In this paper, by enabling...
In this paper, we propose an interference aware throughput maximizing scheduler for cognitive radio networks (CRNs) as part of a MAC layer resource allocation framework. In the considered CRN scenario, the cognitive users with multiple antennas are coordinated by a centralized cognitive base station. We evaluate the performance of our proposed scheme using analysis of variation (ANOVA) technique....
Multiuser interference (MUI) and co-space interference (CSI) are two challenging issues in design of multicarrier code-division multiple-access (MC-CDMA) systems when multiple antennas are used at both the transmitter and receiver sides (MIMO transmission). On the other hand, in cognitive radio (CR) system, the secondary users that use MC-MCDA technique must deactivate the subcarriers used by the...
In this paper, we investigate the problem of spectrum sharing where a macro base station (MBS) is underlaid with multiple femto base stations (FBSs). This problem is investigated from a game theoretic perspective where two games are herein investigated. First, in the non-cooperative case, the MBS and FBSs (i.e., players) behave selfishly aiming at improving their respective payoffs (achievable rate),...
A distributed channel allocation scheme aware of interference in cognitive radio networks is proposed. The objective of the proposed scheme is to minimize the number of dominant interference signals over a threshold instead of the total interference power. The proposed channel allocation can be treated by using game theory and proved to be a potential game, thus it is guaranteed to converge to a Nash...
We study a cognitive channel reuse approach for autonomous femtocell deployment in an OFDMA-based cellular network. The objective is to manage the uplink interference from macrocell users to femtocell access points. Macrocell users are normally far away from the base station and may cause strong uplink interference to the close-by femtocells. By cognitive interference recognition, a femtocell access...
Wireless spectrum is a limited and valuable resource for communications. However, wireless spectrum is known to be underutilized in spacial, temporal, and spectral domains. The dynamic spectrum access (DSA) of cognitive radio networks provides the capability to improve the spectrum efficiency by allowing secondary users to access the spectrum opportunistically without interfering primary users. The...
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