No abstract

Since the rapid developing of economy in Taiwan in recently years, a large numbers of constructions have made the changes on theterrain surrounding of the radio monitoring stations rapidly. Hence, the accuracy performance of the radio monitoring station configured by signal angle of arrival (AOA) location technology has been seriously degraded. In this paper, the simulated result of 20km ~ 30km coverage area is evaluated. Furthermore, the implementation and experiments supported by the radio frequency interference have been governed by authority of national communication commissions (NCC) in Taiwan. The results show that the locating accuracy at circle error probability (CEP) 50% is less than 950 m distance under multi-path effect in metropolitan area. Hence, the solution of integrated the AOA/TDOA technologies can be applied and the interference transmitter characterized with low transmitted power, burst and weak signal and metropolitan interference is easy identified, analyzed (located) and prevented.

The rapid development of wireless broadband communication technology has affected the location accuracy of radio monitoring stations that employ time-difference-of-arrival (TDOA) location technology worldwide. In this study, TDOA-based location technology was implemented in Taiwan for the first time according to International Telecommunications Union requirements regarding monitoring and location application. To improve location accuracy, various scenarios, such as a three-dimensional environment (considering an unequal locating antenna configuration), were investigated. Subsequently, the proposed integrated cross-correlation and genetic algorithm was evaluated in the metropolitan area of Tainan. The results show that the locating performance is improved significantly with genetic algorithm in the 3D free space. Hence, the interference transmitter characterized as having low transmitted power, burst and weak signal and metropolitan interference is easily identified, analyzed (located) and prevented.

No abstract

In order to overcome the vulnerability to eavesdropping on-off-keying based OCDMA scheme, a new multi-code keying reconfiguration is presented to enhance confidentiality over two dimensional time-spreading and wavelength-hopping (2D TS/WH) optical code division multiple access (OCDMA) schemes. The time-shifted carrier-hopping prime codes (CHPCs) are proposed and assigned as signature address code. This proposed scheme provides the integration of electronic and optical layer domain, which inherently comes from the data encryption and spectrum-spreading of the transmitted signals, and then achieves data-confidential enhancement in synchronous networks. Moreover, multi-code keying reconfiguration in a set of distinct codeword is assigned to individual user and random selection by using thin film filter, tunable delay line and optical switch. Here, the probability of interception performance in terms of various multi-code key numbers per user is analyzed. The result shows that the confidentiality is enhanced to combat against eavesdropping while signature address code number per user is increased in proposed multi-code key reconfiguration scheme.