This paper deals with the performance study of an asynchronous multicarrier based Cognitive Radio (CR) networks. We investigate the effect of asynchronism on the system's performance through a theoretical analysis and by using different types of fading channel in simulations. Since asynchronous interference could be very harmful on the system's QoS level, our work was principally to develop a n...

In Cognitive Radio Networks, the application throughput is not only affected by primary user activity but also by numerous environment factors such as interference. Therefore, channel assignment for cognitive radio networks should not only consider channel idle time but also an error rate perceived on the channel. The spectrum-aware channel assignment is vital to efficiently utilize the network...

We consider a network composed of two interfering point-to-point links where the two transmitters can exploit one common relay node to improve their individual transmission rate. Communications are assumed to be multiband and transmitters are assumed to selfishly allocate their resources to optimize their individual transmission rate. The main objective of this paper is to show that this confli...

The transmission system of wireless communication is induced the channel noise. The potential sources of any noise type, which make and diturb the transmission system in external or internal to the communication system for message delivering. The carrier signal mixed interference signal using the amplitude-locked loop (ALL) can be adopted to separat the co-channel system by operating at same fr...

Cognitive radio networks (CRNs) have received considerable attention and viewed as a promising paradigm for future wireless networking. Its major difference from the traditional wireless networks is that secondary users are allowed to access the channel if they pose no harmful interference to primary users. This distinct feature of CRNs has raised an essential and challenging question, i.e., ho...

Spectrum sensing allows cognitive radio systems to detect relevant signals even in the presence of interference for reliable communication. Most existing spectrum techniques use a particular signal-to-noise ratio model with assumptions and provide certain detection performance. Dynamic management enabled efficient allocation channels increasing number users. In system, dynamic is channel occupa...

Conventional fixed spectrum allocation results in a large part of frequency band remaining underutilized. Channels that are dedicated to licensed (primary) users are out of reach of unlicensed users, while the licensed users do not occupy the channel completely, at all times. Cognitive Radio is an attractive concept and solution, capable of addressing this issue. This paper investigates a stati...

This paper proposes symbol level precoding in the downlink of a MISO cognitive system. The new scheme tries to jointly utilize the data and channel information to design a precoding that minimizes the transmit power at a cognitive base station (CBS); without violating the interference temperature constraint imposed by the primary system. In this framework, the data information is handled at sym...

Cognitive Network is a technique which is used to improve the spectrum utilization. Current network scenario is experiencing the huge spectrum scarcity problem due to the fixed assignment policy so in this method great amount of spectrum remain unused. To overcome this limitation the spectrum allocation must be in dynamic manner. In this paper the spectrum allocation is discussed thoroughly. In...

As a key component of urban rail transit systems, communications-based train control (CBTC) is an automated train control system using train-ground communications to ensure efficient operation of rail vehicles. In addition to CBTC systems, passenger information systems (PISs) are adopted in urban rail transit systems to improve quality of service (QoS) offered to customers. The interference bet...