The authors consider a cognitive radio network in which a set of cognitive users make opportunistic spectrum access to one primary channel by time-division multiplexing technologies. Multiple Input Multiple Output techniques (MIMO) are similarly considered to enhance the stable throughput for cognitive links while they should guarantee co-channel interference constraints to the primary link. He...

Sensing and Transmission Strategies in Wireless Cognitive Radio Systems by Babak Abbasi Bastami The main challenge in any cognitive radio system is to maximize secondary users throughput while limiting interference imposed on licensed users. In this regard, finding the optimal sensing and transmission timing strategies and accurate sensing techniques are of great importance in a cognitive radio...

Cognitive Interference Management in 4G Autonomous Femtocells Yangyang Li Doctor of Philosophy Department of Electrical and Computer Engineering University of Toronto 2010 We present a vision for 4G cellular networks based on the concept of autonomous infrastructure deployment. Cellular base stations, or femtocell access points, are deployed by network users without being constrained by the con...

In this paper, the performance of multichannel transmission in cognitive radio is studied. Both constraints and interference limitations are considered. The activities of the primary users (PU)s are initially detected by cognitive users (CU)s who perform sensing process over multiple channels. They transmit in a single channel at variable power and rates depending on the channel sensing decisio...

Beyond 3G (B3G) wireless connectivity can efficiently be realized by exploiting cognitive networking concepts. Cognitive systems dynamically reconfigure the Radio Access Technologies (RATs) and the spectrum they use, based on experience, in order to adapt to the changing environment conditions. However, dynamic reconfiguration decisions call for robust discovery, i.e. radio-scene analysis and c...

Cognitive radio (CR) is an emerging wireless communications paradigm of sharing spectrum among licensed (or, primary) and unlicensed (or, CR) users. In CR networks, interference mitigation is crucial not only for primary user protection, but also for the quality of service of CR user themselves. In this paper, we consider the problem of interference mitigation via channel assignment and power a...

In this paper a model to investigate the spectrum opportunities for cognitive radio networks in three radar frequency bands L, S and C at a specific location is introduced. We consider underlay unaware spectrum sharing model. The Secondary System we assume is an OFDM based system. The followed strategy is built upon defining a specific co or adjacent channel as a spectrum opportunity if -and on...

In this project we first define the model of a broadcast channel in the network information theory basis. This model was proposed in the pioneering work of Cover [1] for the first time. Then we will pay attention to the fact that in a broadcast network, interference from other users can be counted as side information known to the sender. The causal side information was discussed by Shannon in [...

Beamforming techniques can be used to suppress co-channel interference in radio devices. In a cognitive setting, beamforming can be beneficial as it can be applied to cancel interference among co-located primary users and cognitive users. In this study, the authors propose an antenna selection algorithm combined with zero-forcing beamforming to improve the throughput of cognitive multiple-input...