—In cognitive radio network the primary channel information is beneficial. But it can not be obtained by direct channel estimation in cognitive system as pervious methods. And only one possible way is the primary receiver broadcasts the primary channel information to the cognitive users, but it would require the modification of the primary receiver and additional precious spectrum resource. Coo...

We study the arbitrarily varying relay channel, and establish the cutset bound and partial decode-forward bound on the random code capacity. We further determine the random code capacity for special cases. Then, we consider conditions under which the deterministic code capacity is determined as well. In addition, we consider the arbitrarily varying Gaussian relay channel with sender frequency d...

From an information-theoretic point of view, it is well known that the capacity of relay channels comprised of three terminals is much greater than that of two terminal direct channels especially for low SNR region. Previously invented relay coding strategies have not designed to achieve this relaying gain occurred in the low SNR region. In this paper, we propose a new simple coding strategy fo...

Cognitive radios (CR) represent new technique that can effectively improve the spectrum efficiency of future wireless networks. In this paper, the problem of cooperative relay in CR networks will be investigated for further improve network performance. A scenario in which a secondary transmitter can communicate with a secondary receiver via a direct communication link or a relay channel will be...

In this paper, both the security and the reliability performance of the cognitive amplify-and-forward (AF) relay system are analyzed in the presence of the channel estimation error. The security and the reliability performance are represented by the outage probability and the intercept probability, respectively. Instead of perfect channel state information (CSI) predominantly assumed in the lit...

In this paper, a multi-way relay channel is considered with energy harvesting nodes. The harvested energy at each node can be stored in a battery of finite capacity. Additionally, each node employs a data buffer of limited size to store data prior to transmission. Data packets to be exchanged between the nodes arrive at the source nodes in an intermittent fashion. In this setup, the offline sum...

Several power allocation algorithms for cooperative relay networks are presented in the literature. These contributions assume perfect channel knowledge and capacity achieving codes. However in practice, obtaining the channel state information at a relay or at the destination is an estimation problem and can generally not be error free. The investigation of the power allocation mechanism in a w...

We investigate a multiple input multiple output (MIMO) relay broadcast channel (RBC) with full cooperation between users. A beamforming and combining design is proposed based on singular value decomposition (SVD) of the channel matrix between users. Then, users can simultaneously relay each other’s information on the same frequency band with zero interference from each antenna’s transmit signal...

One major limitation of wireless systems is the fading channel that exists between users and the base station. When a user’s channel realization is bad, it may be unable to communicate with the base station. To overcome this problem, many different forms of diversity have been studied including: spatial, temporal, and frequency diversity. Recently, there has been an increasing popularity in a s...