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Wang Y.,Xian Jiaotong University | Wang Y.,State Key Laboratory of Integrated Services Networks | Ren P.,Xian Jiaotong University | Su Z.,Waseda University
IEICE Transactions on Communications | Year: 2011

Utilizing available channels to improve the network performance is one of the most important targets for the cognitive MAC protocol design. Using antenna technologies is an efficient way to reach this target. Therefore, in this paper, we propose a novel cognitive MAC protocol, called Polarization-based Long-range Communication Directional MAC Protocol (PLRC-DMAC), for Cognitive Ad Hoc Networks (CAHNs). The proposed protocol uses directional antennas to acquire better spatial reuse and establish long-range communication links, which can support more nodes to access the same channel simultaneously. Moreover, the PLRCDMAC also uses polarization diversity to allow nodes in the CAHN to share the same channel with Primary Users (PUs). Furthermore, we also propose a Long-range Orientation (LRO) algorithm to orient the long-range nodes. Simulation results show that the LRO algorithm can accurately orient the long-range nodes, and the PLRC-DMAC can significantly increase the network throughput as well as reduce the end-to-end delay. Copyright © 2011 The Institute of Electronics, Information and Communication Engineers. Source


Yin W.,Xian Jiaotong University | Yin W.,State Key Laboratory of Integrated Services Networks | Ren P.,Xian Jiaotong University | Su Z.,Waseda University | Ma R.,Xian Jiaotong University
IEICE Transactions on Communications | Year: 2011

Multiple antenna is introduced into spectrum sensing in cognitive radios recently. However, conventional multiple antenna spectrum sensing schemes exploited only space diversity. In this paper, we propose a new multiple antenna sensing scheme based on space and time diversity (MASS-BSTD). First, the primary user signal to be sensed is oversampled at each antenna, and signal samples collected at the same time instant from different antennas are stacked into a column vector. Second, each column vector is utilized to estimate space correlation matrix that exploits space diversity, and two consecutive column vectors are utilized to estimate time correlation matrix that exploits time diversity. Third, the estimated space correlation matrix and time correlation matrix are combined and analyzed using eigenvalue decomposition to reduce information redundancy of signals from multiple antennas. Lastly, the derived eigenvalues are utilized to construct the test statistic and sense the presence of the primary user signal. Since the proposed MASS-BSTD exploits both space diversity and time diversity, it achieves performance gain over the counterparts that only exploit space diversity. Furthermore, the proposed MASS-BSTD requires no prior information on the primary user, the channel between primary user transmitter and secondary user receiver, and is robust to noise uncertainty. Theoretical analysis and simulation results show that the proposed MASS-BSTD can sense the presence of primary user signal reliably. Copyright © 2011 The Institute of Electronics, Information and Communication Engineers. Source


Wang Y.,Xian Jiaotong University | Wang Y.,State Key Laboratory of Integrated Services Networks | Ren P.,Xian Jiaotong University | Su Z.,Waseda University
IEICE Transactions on Communications | Year: 2011

In this letter, we propose a Partially Observable Markov Decision Process (POMDP) based Distributed Adaptive Opportunistic Spectrum Access (DA-OSA) Strategy for Cognitive Ad Hoc Networks (CAHNs). In each slot, the source and destination choose a set of channels to sense and then decide the transmission channels based on the sensing results. In order to maximize the throughput for each link, we use the theories of sequential decision and optimal stopping to determine the optimal sensing channel set. Moreover, we also establish the myopic policy and exploit the monotonicity of the reward function that we use, which can be used to reduce the complexity of the sequential decision. Copyright © 2011 The Institute of Electronics, Information and Communication Engineers. Source


Su C.-M.,Guilin University of Electronic Technology | Su C.-M.,State Key Laboratory of Integrated Services Networks | Wei Y.-Z.,Guilin University of Electronic Technology | Wei Y.-Z.,CAS Institute of Software | Ma C.-B.,Guilin University of Electronic Technology
Dianzi Yu Xinxi Xuebao/Journal of Electronics and Information Technology | Year: 2012

3D cipher is a new block cipher with Substitution-Permutation Network (SPN) structure. Unlike the Advanced Encryption Standard (AES), 3D cipher uses a 3-dimensional state. Based on the structure of 3D cipher, a 5-round meet-in-the-middle distinguisher and a new attack on 10-round 3D are found. It is shown that the attack requires a data complexity of about 2 128 chosen plaintexts and a time complexity of about 2 331.1 10-round 3D encryptions. Compared with the previous published cryptanalytic results, the attack reduces the data complexity and time complexity efficiently. Source


Ma C.,Guilin University of Electronic Technology | Ma C.,State Key Laboratory of Integrated Services Networks | Ao J.,Guilin University of Electronic Technology
Journal of Convergence Information Technology | Year: 2011

In this paper, we present an improved Rivest's ring signature scheme. In our scheme, the size of the signature is only related to the ring members, and the signer needs no to publish amount of random numbers. On this basis, we propose a group-oriented ring signature. In this scheme, only the person who belongs to the designated group can verify the validity of the ring signature. The security of these two schemes can be proved by using Forking Lemmas. Source

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