In this paper at wireless network we use the cognitive radio (CR) channels for communication. The performance of the process is limited by the self-interference which occur in the CR system. To overcome that problem beam forming method is used effectively which reduces the self-interference of smart meter channels. MMSE method is the main concept in the beam forming method utilized in the smart...

In this paper the secrecy problem in the cognitive statedependent interference channel is considered. In this scenario we have a primary and a cognitive transmitter-receiver pairs. The cognitive transmitter has the message of the primary sender as side information. In addition, the state of the channel is known at the cognitive encoder. So, the cognitive encoder uses this side information to co...

In this paper, we derive a capacity inner bound for a synchronous Gaussian Z channel with intersymbol interference (ISI) under input power constraints. This is done by converting the original channel model into an n-block memoryless circular Gaussian Z channel (n-CGZC) and successively decomposing the n-block memoryless channel into a series of independent parallel channels in the frequency dom...

We provide achievability as well as converse results for the degrees of freedom region of a MIMO channel, i.e., a system with two transmitters, two receivers, each equipped with multiple antennas, where independent messages need to be conveyed over fixed channels from each transmitter to each receiver. The inner and outerbounds on the degrees of freedom region are tight whenever integer degrees...

We provide achievability as well as converse results for the degrees of freedom region of a MIMO X channel, i.e., a system with two transmitters, two receivers, each equipped with multiple antennas, where independent messages need to be conveyed over fixed channels from each transmitter to each receiver. The inner and outerbounds on the degrees of freedom region are tight whenever integer degre...

Interference alignment scheme, because of non ideal channel, can cause interference to primary user increases, it is worse at the same time the user's transmission rate, aiming at this problem, this paper studies the multiple antenna system is a kind of cognitive radio interference can achieve full multiplexing gain alignment method, analyses the interference alignment method under the conditio...

We establish the capacity region for a class of discrete memoryless cognitive interference channel (DM-CIC) called cognitive-more-capable channel, and we show that superposition coding is the optimal encoding technique. This is the largest capacity region for the DM-CIC to date, as the existing capacity results are explicitly shown to be its subsets.

This paper studies optimum power control and sum-rate scaling laws for the distributed cognitive uplink. It is first shown that the optimum distributed power control policy is in the form of a threshold based water-filling power control. Each secondary user executes the derived power control policy in a distributed fashion by using local knowledge of its direct and interference channel gains su...

This paper addresses the issues in Underlay Cognitive Radio Networks employing amplify-and-forward relaying. The secondary users operating in an underlay mode in the frequency band of primary users must satisfy interference constraints to keep primary communication undisturbed. We propose a solution to this problem using cognitive relays and perform channel state information (CSI) based relay s...