Beijing University of Posts and Telecommunications

About: Beijing University of Posts and Telecommunications is a education organization based out in Beijing, Beijing, China. It is known for research contribution in the topics: MIMO & Quality of service. The organization has 39576 authors who have published 41525 publications receiving 403759 citations. The organization is also known as: BUPT.

Analytical Design Method of Multiway Dual-Band Planar Power Dividers With Arbitrary Power Division

Abstract: In this paper, a novel closed-form design method of generalized Wilkinson power dividers is proposed. By using this method, the power divider could be designed to be arbitrary-way (N-way) with arbitrary power division, and arbitrary dual-band operations in a pure planar structure. A previous dual-band unequal Wilkinson power divider is extended to arbitrary terminal impedances case, thus, it can be used to construct multiway planar power dividers through the combination of the two-section dual-frequency transformers. To obtain three-way (or any odd-way) power dividers with dual-band and unequal power division features, a new developed recombinant structure is employed. This recombinant structure consists of a two-way dual-band unequal power divider/combiner without any isolation structures. Furthermore, the complete design procedures and analytical equations of these proposed generalized power dividers are presented. To verify our proposed design approach in theory, several three-way and four-way power dividers with different dual-band applications and various power divisions are designed and simulated. Finally, a practical three-way power divider operating at both 0.6 and 2.45 GHz with a power dividing ratio of 3:5:1 is fabricated in microstrip technology as a typical example. The measured results of the fabricated power divider verify our proposed idea.

Scalable Name Lookup with Adaptive Prefix Bloom Filter for Named Data Networking

Abstract: In Named Data Networking (NDN), packet forwarding decisions rely upon lookup operations on variable-length hierarchical names instead of fixed-length host addresses. This pivotal feature introduces new challenges in the deployment of NDN at the Internet scale. In this letter, a novel Name Lookup engine with Adaptive Prefix Bloom filter (NLAPB) is conceived, in which each NDN name/prefix is split into B-prefix followed by T-suffix. B-prefix is matched by Bloom filters whereas T-suffix is processed by the small-scale trie. The length of B-prefixes (and T-suffixes) is dynamically throttled based on their popularity in order to accelerate the lookup. Experimental results show that: (i) NLAPB is able to lower the false positive rate with respect to a lookup entirely based on Bloom filters; (ii) it decreases the memory requirements with respect to a trie-based approach; (iii) it reduces processing time with respect to both them.

Resource Allocation for D2D Communications Underlay in Rayleigh Fading Channels

Abstract: Device-to-device (D2D) communication has attracted substantial research attention recently, due to its potential to improve coverage, spectrum efficiency, and energy efficiency within the existing cellular infrastructure. One major challenge for spectrum resource sharing in D2D underlay lies in the mutual interference between cellular user equipments (CUEs) and D2D user equipments (DUEs). Considering this mutual interference constraint, this work investigates the problem of optimal matching of D2D links and CUEs to form spectrum-sharing partners to maximize ergodic sum rates under transmit power and outage constraints. Unlike previous works, full channel-state information (CSI) is not required. To solve the resulting high-complexity problem, candidate DUE sets are first narrowed down according to required outage probability constraints, which are used to construct a simplified bipartite graph. The weight of the bipartite graph is characterized as the maximization of ergodic sum rate of the associated D2D and cellular links under outage constraints for which a low-complexity algorithm is proposed to solve the nonconvex problem. After constructing the bipartite graph, the Hungarian algorithm is used to determine the optimal pairing between D2D links and CUEs. Numerical results demonstrate that the proposed algorithm can improve the outage-constrained spectrum efficiency of D2D networks with practical complexity.

Novel image encryption/decryption based on quantum Fourier transform and double phase encoding

Abstract: A novel gray-level image encryption/decryption scheme is proposed, which is based on quantum Fourier transform and double random-phase encoding technique. The biggest contribution of our work lies in that it is the first time that the double random-phase encoding technique is generalized to quantum scenarios. As the encryption keys, two phase coding operations are applied in the quantum image spatial domain and the Fourier transform domain respectively. Only applying the correct keys, the original image can be retrieved successfully. Because all operations in quantum computation must be invertible, decryption is the inverse of the encryption process. A detailed theoretical analysis is given to clarify its robustness, computational complexity and advantages over its classical counterparts. It paves the way for introducing more optical information processing techniques into quantum scenarios.

Postprocessing of the Oblivious Key in Quantum Private Query

Abstract: Private query is a kind of cryptographic protocols to protect both users' privacies in their communication. For instance, Alice wants to buy one item from Bob's database. The aim of private query is to ensure that Alice can get only one item from Bob, and simultaneously, Bob cannot know which one was taken by Alice. In pursuing high security and efficiency, some quantum private query protocols were proposed. As a practical model, Quantum-Oblivious-Key-Transfer (QOKT)-based private query, which utilizes a QOKT protocol to distribute oblivious key between Alice and Bob and then applies the key to achieve the aim of private query, has drawn much attention. Here, we focus on postprocessing of the oblivious key, and the following two contributions are achieved. 1) We analyze three recently proposed dilution methods and find two of them have serious security loophole. That is, Alice can illegally obtain much additional information about Bob's database by multiple queries. For example, Alice can obtain the whole database, which contains 10 4 items, by only 53.4 queries averagely. 2) We present an effective error-correction method for the oblivious key, which can address the realistic scenario with channel noises and make QOKT-based private query more practical.