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In order to realize improving signal detection probability using interference canceler and multi-system detection techniques in spectrum sharing environment in cognitive radio of satellite and terrestrial system, it is required to classify the digital modulation type in an environment without handshaking between the transmitter and receiver. The previous methods can hardly classify modulation type...
Spectrum sharing by using cognitive radio technology has attracted attention as an effective solution to shortage of spectrum resource. In the spectrum sharing, unlicensed users (secondary users: SUs) exploit white space (WS) which is unused band by licensed users (primary users: PUs). In the related works, the channel assignment method maximizing the SU communication quality while protecting the...
Small cell networks enhance spectrum efficiency by handling the indoor traffic of mobile networks on a frequency-reuse operation. Because most of the current mobile traffic happens indoor, we introduce a prioritization shift by imposing a limitation on the outage generated by the outdoor mobile system to the indoor small cells. In this paper, we consider downlink spectrum sharing between a system...
This paper proposes a new evaluation model considering cost based on a cost parameter to evaluate the performance of cellular system. One of the issues of the next generation cellular systems is the improvement of cell-edge throughput performance. In order to improve the cell-edge throughput performance and to extend the coverage area, relay transmission is becoming a promising technique. The cell-edge...
In this paper, we have proposed secondary user (SU) resource assignment scheme for a multi-hop cognitive radio network. In Multi-hop networks, since each link has different SNR because of their different distance between the stations and some other circumstance, it degrades the end-to-end throughput. To overcome this problem, we have proposed to give a channel priority in each link based on the link...
This paper proposes a user pairing control method for multi-cell shared multi-user MIMO relay (MC-MU-MIMO relay) to improve the throughput of cellular networks. MC-MU-MIMO relay system sets a multi-antenna relay station (RS) at the cell boundary and the RS is shared with adjacent cells. The proposed relay system can improve the throughput of cell boundary due to increasing signal to noise ratio and...
In this paper, we propose a novel cooperative sensing method by iteratively improving the sensing ability. The proposed method can increase the number of cooperative sensing nodes. Moreover the harmful interference can be avoided, even if the sensing information of each sensing node is transmitted at the same spectrum of the primary system. In general, the cooperative sensing ability depends on the...
In cognitive radio system, it is necessary for spectrum sensing technology to search for vacant channel. Cyclostationary feature detection method has superior noise-immune and recognition. However, since the mismatch between the detected signal and detection duration by guard interval (GI) insertion occurs, the cyclostationarity is degraded. In this paper, we propose a high accuracy and low complexity...
In this paper, we have studied methods of detecting low signal-to-noise ratio (SNR) nodes by outlier detection in cooperative spectrum sensing. In many studies in the field of cooperative sensing, it is assumed that an average received energy among sensing nodes is equal. However, in practical wireless environment, the performance of cooperative sensing with low SNR nodes located underground, indoor,...
In this paper we evaluate the sensing performance by using a MRC based blind channel combining scheme in low SNR environment, to sense the low level primary signal in cognitive radio with multiple antenna. MRC based blind channel combining for multiple antennas is known as achieving almost the same performance compared with an optimum MRC which has full knowledge of the channels if we apply it in...
Cognitive radio system shares the frequency spectrum with the license system. As a result, the dramatic improvement of the frequency usage efficiency can be expected. Since the cognitive radio system is independent from the license system, it should recognize the wireless communication parameter of the license system, such as frequency, modulation scheme, and so on. Multiple-input multiple-output...
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