Delay tolerant networking (DTN) is able to provide communication services in areas where there is no guarantee that a fully connected path between source and destination exists at any time, and seek to address the technical routing issues in wireless networks. Traditional routing protocols are unable to deliver messages between hosts in such conditions. PRoPHET protocol is among the most widely used routing protocols for such networks. The choice of message forwarding strategies can have a major impact on system performance. In this paper, we propose a controlled forwarding strategy for probabilistic routing protocols that can optimize different performance metrics. Based on some assumptions, we have set new rules for message transmission to neighboring nodes. We show that PRoPHET protocol along with our new forwarding strategy can result in much performance improvement in terms of delivered and relayed messages. Learning automata is used to give the optimal threshold value.
<div>In the context of cognitive radio (CR) or various military and civilian applications, modulation recognition (MR) is one of the most popular technical processes in the field of communication system recognition, by which the modulation type of the unknown received signal can be identified automatically by estimating one or more parameters of the modulated signal. This paper presents the performance evaluation of the new proposed blind system recognition method using only a particular property of the second-order statistics of the orthogonal frequency division multiplexing (OFDM) modulated signal. The effectiveness of the proposed method is illustrated using the implementation on universal software radio peripheral (USRP) platform. A comparison with computer simulations using MATLAB software is also performed, emphasizing the good performances of the method while the results obtained are close. We show the efficiency and behavior of the proposed method in the context of wireless communication systems based on OFDM modulation (3GPP/LTE, WiMAX, DVBT-2K, IEEE 802.22-1K,IEEE 802.22-2K, IEEE 802.22-4K). The proposed method can detect OF DM signals among other digital signals in a systematic and intelligent way even with low SNR values (when approaching to SNR=-2dB, the decision criteria tends towards 0).</div>
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