We analyse the spectral efficiency performance and limits of orthogonal frequency-division multiple access (OFDMA) cognitive radios (CRs) with imperfect availability of cross-link knowledge. In particular, in contrast to the conventional ‘average’ and ‘worst’ cases of channel estimation error in the literature, we propose a stochastic approach to mitigate the total imposed interference on prima...

The cognitive interference channel with unidirectional destination cooperation (CIFC-UDC) is a cognitive interference channel (CIFC) where the cognitive (secondary) destination not only decodes the information sent from its sending dual but also helps enhance the communication of the primary user. This channel model is an extension of the original CIFC to achieve a win-win solution under the co...

In this paper interference management in co-channel deployment of macrocell and cognitive femtocells is investigated. For the purpose of the aggregate interference mitigation from all femtocell access points (FAP) to macrocell user equipment (MUE) and the purpose to increase the radio link quality of femtocell system, a parameter named interference tolerable threshold (Ith) is introduced, the a...

In this paper, the performance of cognitive transmission under quality of service (QoS) constraints and interference limitations is studied. Cognitive secondary users are assumed to initially perform sensing over multiple frequency bands (or equivalently channels) to detect the activities of primary users. Subsequently, they perform transmission in a single channel at variable power and rates d...

—In this paper, we study the achievable region for a Gaussian broadcast channel in the presence of an additional interference at the receivers. We consider that a noisy version of this interference is known to the transmitter and the receivers. A nested lattice code coupled with a dirty paper code is used to compute the achievable region. A two phase causal encoding technique is also proposed ...

Cognitive radio and femtocell are promising technologies which can satisfy the requirements of future mobile communications in terms of dynamic spectrum sharing and high user density areas. Providing quality-of-service (QoS) guaranteed realtime services is challenging issue of future cognitive cellularfemtocell mobile networks. In this paper, we introduce a user’s QoS management mechanism used ...

CR and PU hidden terminals in multi-channel Cognitive MAC protocols result in increased packet drops. This is due to inefficient node synchronization with existing “Control Channel” design. To date, In-band and Out-of-band CCC based MAC protocols are proposed to avoid PU and CR hidden terminals. But, In-band CCC based CR-MAC protocols cannot efficiently resolve the hidden terminal packet drops ...