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This paper presents an interference mitigation algorithm for coexistence of Multiple-Input Multiple-Output (MIMO) Multiband OFDM ultra wideband (MB UWB) Cognitive Radio systems with other wireless communication systems. While other interference cancellation algorithms are applied for SISO system, an improved Active Interference Cancelation algorithm for MIMO MB-UWB systems is proposed with aims to...
Cognitive radio is an exciting emerging technology that has the potential of dealing with the urgent requirement and scarcity of the radio spectrum. Although having multiple radio interfaces and available spectrum bands can generally increase the effective throughput, a problem arises as to what the best strategy to dynamically assign available bands to secondary users for maximizing throughput by...
Cognitive Radio (CR) is viewed as a novel approach for improving the utilization of the radio electromagnetic spectrum. The radio spectrum is a scarce resource while wide spectral ranges are only rarely used. Spectrum Pooling enabling public access to these new spectral ranges without sacrificing the transmission quality of the actual license owners. However, in the Spectrum Pooling system, the interference...
Cognitive radio is thought to be a flexible way to improve the spectrum efficiency. The major challenge is that the communications in the cognitive radio network would be affected by the behaviors of licensed incumbents. The cognitive system must vacate the channel within moving time whenever the licensed incumbents re-occupy that channel, in order to reduce the interference to the licensed system...
This paper discusses an interference DAA (Detection And Avoidance) technique for coexisting pulse based UWB and OFDM systems when the both systems are operated in the same frequency band. In a UWB transmitter-receiver, utilization of the OFDM system is detected by correlating with the GI (Guard Interval) signals. And also timing of the GI period is detected for interference mitigation. The UWB signal...
In secondary underlay transmission in a host channel, the signal from primary transmitter produces high interference for secondary low power links. In this paper, we propose a primary interference suppression technique by using direct sequence spread spectrum. We show that secondary users can efficiently suppress the high power signal from a primary transmitter by using proper processing gains. Also,...
We propose a framework for designing an underlay secondary CDMA network. The objective is to select the secondary system's bit rate and spreading factor that improve the secondary network throughput given a required bit error rate and an allowable transmit power level acceptable to the primary network. The selection scheme is applied to both the case of random code assignment and an interference-minimizing...
Cognitive radio (CR) has attracted strong interest recently to solve the spectrum congestion problem. In conventional cognitive radio, either overlay waveform is used to exploit unused (white) spectrum holes to avoid interference to primary users, or underlay waveform is employed to spread over a ultrawide bandwidth with extremely low power spectrum density to minimize interference to primary users...
In this paper, two types of dual-band receivers are proposed in order to realize the concurrent reception of two separate frequency bands for a spectrum aggregation system. The proposed receivers consist of a common intermediate frequency stage with a common oscillator and common band-pass filter. By controlling the frequency of the oscillator, the proposed receiver eliminates interference from adjacent...
In this paper we develop a cellular cognitive radio network based on MC-CDMA, which is able to coexist with a number of legacy RANs in a shared band. Using the simple-to-obtain knowledge of RF environment, namely the bandwidth and frequency location of each legacy system, the cognitive MC-CDMA transmitter mitigates the interference in the corresponding receivers by adaptive transmission. We will develop...
In this paper, we studied the method that improves the downlink performance of cellular relay system in multiple-cell environment by using cognitive radio. When relay stations in the network have spectrum agility, they can establish downlink channels which are orthogonal to downlink of base station. In this way, interference between base station and relay station can be reduced and spectral resource...
We propose a novel distributed cross-layer optimization approach for cognitive radio wireless networks. A cognitive radio is a wireless device that is capable of sensing the prevailing environmental conditions and automatically adapting its operating parameters in order to enhance the performance of both the system and potentially the whole network. Given the lack of a centralized intelligence to...
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