جستجوی مقالات مرتبط با کلیدواژه « space-time codes » در نشریات گروه « پدافند غیرعامل »

For eavesdropping of modern telecommunications systems, which employ multiple transmit and receive antennas, the first step is to recognize the space-time code. In this paper, we propose a method to classify within broad categories of space-time codes. The method is based on machine learning and pattern recognition. Compared to the previous published researches, the novelty of this paper is including quasi-orthogonal space-time codes and also single antenna transmitter in identification set. Moreover, the method described in this paper outperforms the current classification methods. It is shown that the decision tree classifier based on several features extracted from correlation matrices, has practical advantages over the current classification methods, especially when data is very noisy.

Control, inspection, detection, and transmitting or receiving data in modern defence principles, essentially requires the low-power radio frequency systems with the ability of operating at various communication standards. In this paper, employing the modern method of active and passive N-path filters, a receiver front-end with the ability of tunablity at various standards and frequencies is proposed. In addition to the analysis of conventional and advanced N-path filters, the prior similar structures are discussed in details. Applying some modifications in the previous structure, not only the NF has been improved but also the power consumption has been considerably decreased, while the stability has been guaranteed. To verify the correctness of the proposed receiver front-end, the cadence IC design tool has been used to simulate the system. According to the simulation results, using CMOS90nm transistors, the amount of power consumption has been remarkably decreased with respect to the previous similar structures. The NF and S11 values in the whole of frequency range, DC to 1.85GHz, are less than 3.6dB and -10dB, respectively. The power consumption is less than 15mW including the power consumption of the recombiners. The out of band IIP3 is +8dBm.