One of the limitations of using OFDM technique is its higher PAPR in the time domain signal. The higher PAPR OFDM signal would cause the fatal degradation of BER performance and undesirable spectrum regrowth in the no...One of the limitations of using OFDM technique is its higher PAPR in the time domain signal. The higher PAPR OFDM signal would cause the fatal degradation of BER performance and undesirable spectrum regrowth in the nonlinear channel. One of the promising PAPR reduction methods for OFDM signal is the Partial Transmit Sequence (PTS) method which can achieve better PAPR performance with reasonable computation complexity. However the PTS method is required to inform the phase coefficients of PTS as the side information to the receiver for the correct demodulation of data information through the data or separate channels. To simplify the transceiver of OFDM system with the PTS method, the phase coefficients of PTS are usually embedded in the data information. However since the phase coefficients of PTS are obtained after the PTS processing only for the data information at each OFDM symbol, it is hard to embed the phase coefficients of PTS in the data information separately without degradation of PAPR performance. To solve this problem, this paper proposes a new PAPR reduction method based on the packet-switched transmission systems in which all the clusters within the certain number of OFDM symbols have the sequential cluster ID numbers embedded in the header of each cluster. The salient features of the proposed method are to reduce the PAPR performance by re-ordering of clusters (ROC) in the frequency domain at the transmitter and to reconstruct the original ordering of clusters by using the cluster ID number demodulated from each cluster at the receiver. This paper also proposes a reduction technique of computation complexity for the proposed ROC method by using the feature of IFFT processing. This paper presents various computer simulation results to verify the effectiveness of the proposed ROC method with the reduction technique of computation complexity.展开更多
LEACH(Low Energy Adaptive Clustering Hierarchy)路由协议是无线传感器网络拓扑控制中最具代表性和重要性的算法之一。针对LEACH路由协议簇头分布不均匀,节点死亡率高,易产生路由空洞及其所面临安全威胁等问题,提出一种基于散列链的...LEACH(Low Energy Adaptive Clustering Hierarchy)路由协议是无线传感器网络拓扑控制中最具代表性和重要性的算法之一。针对LEACH路由协议簇头分布不均匀,节点死亡率高,易产生路由空洞及其所面临安全威胁等问题,提出一种基于散列链的区域划分网格自治安全路由协议LEACH-SEED。剔除低能量节点入选簇头的权利,改进簇头选举机制,簇头选举完成之后,每个簇头节点随机从散列链组成的密钥池中分配q个链密钥,其他节点利用单向哈希函数和伪随机函数生成通信密钥,网络遭受攻击后利用网格自治和待选簇头身份标识编号进行网络恢复。实验结果表明,改进的分簇算法能有效地降低节点死亡率,增强抗攻击能力,提高数据融合度,延长网络生存时间。展开更多
文摘One of the limitations of using OFDM technique is its higher PAPR in the time domain signal. The higher PAPR OFDM signal would cause the fatal degradation of BER performance and undesirable spectrum regrowth in the nonlinear channel. One of the promising PAPR reduction methods for OFDM signal is the Partial Transmit Sequence (PTS) method which can achieve better PAPR performance with reasonable computation complexity. However the PTS method is required to inform the phase coefficients of PTS as the side information to the receiver for the correct demodulation of data information through the data or separate channels. To simplify the transceiver of OFDM system with the PTS method, the phase coefficients of PTS are usually embedded in the data information. However since the phase coefficients of PTS are obtained after the PTS processing only for the data information at each OFDM symbol, it is hard to embed the phase coefficients of PTS in the data information separately without degradation of PAPR performance. To solve this problem, this paper proposes a new PAPR reduction method based on the packet-switched transmission systems in which all the clusters within the certain number of OFDM symbols have the sequential cluster ID numbers embedded in the header of each cluster. The salient features of the proposed method are to reduce the PAPR performance by re-ordering of clusters (ROC) in the frequency domain at the transmitter and to reconstruct the original ordering of clusters by using the cluster ID number demodulated from each cluster at the receiver. This paper also proposes a reduction technique of computation complexity for the proposed ROC method by using the feature of IFFT processing. This paper presents various computer simulation results to verify the effectiveness of the proposed ROC method with the reduction technique of computation complexity.
文摘LEACH(Low Energy Adaptive Clustering Hierarchy)路由协议是无线传感器网络拓扑控制中最具代表性和重要性的算法之一。针对LEACH路由协议簇头分布不均匀,节点死亡率高,易产生路由空洞及其所面临安全威胁等问题,提出一种基于散列链的区域划分网格自治安全路由协议LEACH-SEED。剔除低能量节点入选簇头的权利,改进簇头选举机制,簇头选举完成之后,每个簇头节点随机从散列链组成的密钥池中分配q个链密钥,其他节点利用单向哈希函数和伪随机函数生成通信密钥,网络遭受攻击后利用网格自治和待选簇头身份标识编号进行网络恢复。实验结果表明,改进的分簇算法能有效地降低节点死亡率,增强抗攻击能力,提高数据融合度,延长网络生存时间。
