We consider the spectrum handoff delay of a Secondary User(SU)in cognitive radio networks.We propose a spectrum handoff scheme based on Recommended Channel Sensing Sequence(RCSS),which aims to optimise the spectrum ha...We consider the spectrum handoff delay of a Secondary User(SU)in cognitive radio networks.We propose a spectrum handoff scheme based on Recommended Channel Sensing Sequence(RCSS),which aims to optimise the spectrum handoff delay subject to the sensing reliability and link maintenance constraints.There are two cases that should be considered:1)the SU performs spectrum handoff successfully during the current frame,and 2)the SU successfully performs the spectrum handoff using several frames.We develop a dynamic programming algorithm for RCSS to identify the optimal sensing sequence for the first case,and an updating algorithm for RCSS to improve the handoff performance for the second case.The numerical results confirm that the proposed RCSS handoff scheme can achieve better handoff delay performance than others when the received signal-to-noise ratios of the Pus' signals on different channels are non-identical.展开更多
With the conditions of small data size and low Signal-to-Noise Ratio (SNR), the application of Higher Order Statistics (HOS) is restrained not only by its high estimation variance,but also by its low estimation precis...With the conditions of small data size and low Signal-to-Noise Ratio (SNR), the application of Higher Order Statistics (HOS) is restrained not only by its high estimation variance,but also by its low estimation precision. Therefore, a modified HOS based Time Delay Estimation (TDE) algorithm is proposed to overcome these problems. Comparing with the conventional TDE algorithms, the estimation variance is improved greatly. A typical simulation example is completed in order to test the performance of the algorithm proposed, which shows that the proposed algorithm has advantages over the traditional ones in both detection performance and computation efficiency.展开更多
基金supported by the National Natural Science Foundation of China under Grant No. 61172067
文摘We consider the spectrum handoff delay of a Secondary User(SU)in cognitive radio networks.We propose a spectrum handoff scheme based on Recommended Channel Sensing Sequence(RCSS),which aims to optimise the spectrum handoff delay subject to the sensing reliability and link maintenance constraints.There are two cases that should be considered:1)the SU performs spectrum handoff successfully during the current frame,and 2)the SU successfully performs the spectrum handoff using several frames.We develop a dynamic programming algorithm for RCSS to identify the optimal sensing sequence for the first case,and an updating algorithm for RCSS to improve the handoff performance for the second case.The numerical results confirm that the proposed RCSS handoff scheme can achieve better handoff delay performance than others when the received signal-to-noise ratios of the Pus' signals on different channels are non-identical.
基金Supported by the National Natural Science Foundation of China(No.60072027)
文摘With the conditions of small data size and low Signal-to-Noise Ratio (SNR), the application of Higher Order Statistics (HOS) is restrained not only by its high estimation variance,but also by its low estimation precision. Therefore, a modified HOS based Time Delay Estimation (TDE) algorithm is proposed to overcome these problems. Comparing with the conventional TDE algorithms, the estimation variance is improved greatly. A typical simulation example is completed in order to test the performance of the algorithm proposed, which shows that the proposed algorithm has advantages over the traditional ones in both detection performance and computation efficiency.
