[Show abstract][Hide abstract] ABSTRACT: Random direction mobility model is commonly used in the simulation-based performance analysis for ad hoc networks. Recent works have shown that the distribution of nodes moving according to random direction is non-uniform. Apparently, the node distribution of the model will influence the accuracy of related researches and simulations. So in this paper, we give some in-depth investigation of random direction, and present a new method using the geometric probability to get the node distribution of random direction mobility. At last several simulations are provided to validate our results.
[Show abstract][Hide abstract] ABSTRACT: In this paper, the security mechanism of the digital packet radio protocol MIL-STD 188-220C is discussed. Based on an important DAP-NAD algorithm for channel access priority mechanism, an attack algorithm is proposed and analyzed using queuing theory. Related simulations have done to evaluate the performance of the protocol and verify the feasibility of the attack strategies.
[Show abstract][Hide abstract] ABSTRACT: Research scheme of frequency hopping (FH) communication system using signal processing worksystem (SPW) is presented. A VHF slow frequency-hopping communication system is designed and modeled using SPW. Then the designed system is tested under broadband noise and partial-band noise interference channel for its bit error rate performance. At last, the performance of synchronize algorithm in this system is analysis and simulated. The results showed that this scheme is helpful in FH communication system design.
[Show abstract][Hide abstract] ABSTRACT: This paper introduces a new algorithm for key features extraction of digital modulations recognition. This new algorithm utilizes complexity approach in which a set of value of Lempel-Ziv complexity for identifying different types of modulations is developed. The set of value is derived from three important parameters - the instantaneous amplitude, phase, and frequency of the intercepted digitally modulated signals. Computer simulations of different types of band-limited digitally modulated signals corrupted by band-limited Gaussian noise sequences have been carried out to measure the performance of the developed algorithm.