Wen-Tsuen Chen

Bio: Wen-Tsuen Chen is an academic researcher from National Tsing Hua University. The author has contributed to research in topics: Wireless network & Network packet. The author has an hindex of 34, co-authored 263 publications receiving 4338 citations. Previous affiliations of Wen-Tsuen Chen include Academia Sinica & University of California, Berkeley.

On the Automated Generation of Program Test Data

Abstract: Software validation through testing will continue to be a very important tool for ensuring correctness of large scale software systems. Automation of testing tools can greatly enhance their power and reduce testing cost. In this paper, techniques for automated test data generation are discussed. Given a program graph, a set of paths are identified to satisfy some given testing criteria. When a path or a program segment is specified, symbolic execution is used for generating input constraints which define a set of inputs for executing this path or segment. Problems encountered in symbolic execution are discussed. A new approach for resolving array reference ambiguities and a procedure for generating test inputs satisfying input constraints are proposed. References to arrays are recorded in a table. during symbolic execution and ambiguities are resolved when test data are generated to evaluate the subscript expressions. The implementation of a test data generator for Fortran programs incorporating these techniques is also described.

Secure broadcasting using the secure lock

Abstract: The authors discuss secure broadcasting, effected by means of a secure lock, on broadcast channels, such as satellite, radio, etc. This lock is implemented by using the Chinese Remainder theorem (CRT). The secure lock offers the following advantages: only one copy of the ciphertext is sent; the deciphering operation is efficient; and the number of secret keys held by each user is minimized. Protocols for secure broadcasting using the secure lock, based on the public-key cryptosystem as well as the private-key cryptosystem, are presented. >

PRADA: Prioritized Random Access With Dynamic Access Barring for MTC in 3GPP LTE-A Networks

Abstract: Due to the huge amount of machine-type communications (MTC) devices, radio access network (RAN) overload is a critical issue in cellular-based MTC. The prioritized random access with dynamic access barring (PRADA) framework was proposed to efficiently tackle the RAN overload problem and provide quality of service (QoS) for different classes of MTC devices in Third-Generation Partnership Project (3GPP) Long-Term Evolution Advanced (LTE-A) networks. The RAN overload issue is solved by preallocating random access channel (RACH) resources for different MTC classes with class-dependent back-off procedures and preventing a large number of simultaneous random access requests using dynamic access barring. In this paper, the performances of LTE-A without access barring, extended access barring (EAB), and PRADA are mathematically derived and compared, showing the superior performance of the PRADA scheme.

Active application oriented vertical handoff in next-generation wireless networks

Abstract: The coexistence of heterogeneous wireless networks providing service anywhere at anytime is an inevitable trend in the development of next-generation wireless data networks. Vertical handoff is the switching of the mobile terminal (MT) among different types of wireless networks. How and when to carry out vertical handoff directly affects the performance and quality of network services. In this paper, we propose a novel vertical handoff scheme in which the MT can request and initiate the handoff actively, contrary to other schemes where the MTs participate passively during the handoff process. Our active application oriented scheme provides an efficient interface management for multi-interface MTs to reduce the power consumption caused by unnecessary interface activation. By treating the application running in the MT as the main vertical handoff decision factor, the proposed scheme is able to switch the MT at the right time to the most suitable network to minimize the waste of network resources. Finally, simulation results are presented to show the improved performance over passive schemes.

The strongly connecting problem on multihop packet radio networks

Abstract: The problem of strongly connecting a multihop packet radio network by using a minimal total amount of transmission power is investigated. This problem is shown to be NP-complete. An approximation algorithm with the same computational complexity as that of finding a minimum spanning tree is given. It is also shown that the approximation algorithm can find a solution no greater than twice that of the optimal solution. Experimental results show that the approximation solution may be close to the optimal solution. >

Hints on Test Data Selection: Help for the Practicing Programmer

Abstract: In many cases tests of a program that uncover simple errors are also effective in uncovering much more complex errors. This so-called coupling effect can be used to save work during the testing process.

The knowledge complexity of interactive proof-systems

Abstract: Usually, a proof of a theorem contains more knowledge than the mere fact that the theorem is true. For instance, to prove that a graph is Hamiltonian it suffices to exhibit a Hamiltonian tour in it; however, this seems to contain more knowledge than the single bit Hamiltonian/non-Hamiltonian.In this paper a computational complexity theory of the “knowledge” contained in a proof is developed. Zero-knowledge proofs are defined as those proofs that convey no additional knowledge other than the correctness of the proposition in question. Examples of zero-knowledge proof systems are given for the languages of quadratic residuosity and 'quadratic nonresiduosity. These are the first examples of zero-knowledge proofs for languages not known to be efficiently recognizable.

Broadcast encryption

Abstract: We introduce new theoretical measures for the qualitative and quantitative assessment of encryption schemes designed for broadcast transmissions. The goal is to allow a central broadcast site to broadcast secure transmissions to an arbitrary set of recipients while minimizing key management related transmissions. We present several schemes that allow a center to broadcast a secret to any subset of privileged users out of a universe of size n so that coalitions of k users not in the privileged set cannot learn the secret. The most interesting scheme requires every user to store O(klog klog n) keys and the center to broadcast O(k2 log2 k log n) messages regardless of the size of the privileged set. This scheme is resilient to any coalition of k users. We also present a scheme that is resilient with probability p against a random subset of k users. This scheme requires every user to store O(log k log(l/p)) keys and the center to broadcast O(klog2 fclog(l/p)) messages.