SPRING SOURCE TECHNOLOGIES

An Adaptive Subcarrier Sharing Scheme for OFDM-Based Cooperative Cognitive Radios ABSTRACT: •                   Incorporation of orthogonal frequency division multiplexing (OFDM) in cooperative cognitive radio network facilitates subcarrier sharing to achieve spatial diversity with opportunistic spectrum access. •       In addition, adaptive modulation has been adopted widely in wireless communication to improve spectral efficiency. Use of adaptive modulation for cooperative cognitive relaying transmission to maximize throughput under bit error rate (BER) constraint is an open issue. •       In this paper, we propose an adaptive subcarrier sharing scheme for OFDM-based cooperative cognitive radio system, wherein cognitive (secondary) system helps the primary system to achieve its target rate of communication in exchange for opportunistic spectrum sharing. EXISTING SYSTEM: •            In this work, a joint optimization problem is formulated for selective subcarrier pai

Cooperative Spectrum Sensing with Data Mining of Multiple Users’ Historical Sensing Data ABSTRACT: •                            The current cooperative spectrum sensing still can not effectively exploit the temporal correlations among sensing data, especially the correlations between the current sensing data and the historical data. •       This paper uses sticky hierarchical Dirichlet process-hidden Markov model to exploit the historical sensing data of multiple users, and classifies the historical sensing data into groups according to their latent spectrum states. •        The proposed spectrum sensing algorithm can fuse the historical sensing data into prior knowledge, which can be used to improve the accuracy in spectrum decision. •        Furthermore, a rejection process is proposed to filter out some sensing data with high uncertainty in classification, which guarantees the effectiveness of historical sensing data. EXIXTING SYSTEM: •                  Furthermor

Cooperative Spectrum Sensing with Data Mining of Multiple Users’ Historical Sensing Data MODULES: ·         Corrective Spectrum Sensing Data ·         Historical sensing data DESCRIPTION Corrective Spectrum Sensing Data:           The PU state transition probability matrix can be inferred based on the historical data mining and be used as prior knowledge to improve the performance of spectrum decision. Historical sensing data:           Sensing data with the same latent spectrum state will be fused together according to their statistical correlation. The spectrum sensing decision is a special case in decision theory, since it decides whether the channel is available or not according to the sensing data.

An Adaptive Subcarrier Sharing Scheme for OFDM-Based Cooperative Cognitive Radios MODULES : ·         Node  Formation ·         Primary System Rate and Outage Probability ·         Secondary System Rate and Outage Probability ·         Data transmission DESCRIPTION: NODE FORMATION: The channels over the nodes are modeled as frequency non-selective Rayleigh block fading.The instantaneous channel gain for each subcarrier over different nodes. Primary System Rate and Outage Probability:             In other words instantaneous data rate with BER-SC increases, consequently outage probability decreases. With cooperation ST behaves as an adaptive DF relay so as to provide diversity gain to the primary system. we propose an adaptive subcarrier sharing scheme for OFDM-based cooperative cognitive radio system, wherein cognitive (secondary) system helps the primary system to achieve its target rate of communication in exchange for opportunistic spectrum sharing. Se