Suppression Technique Based On Iterative Interference Of Non-coherent Detection

In modern wireless communication, particularly in military communication there are a variety of man-made or natural interference. Facing with strong interference, the information will not be effective and reliable if the receiver does not have effective interference suppression method. Many Scholars home and abroad have been studying the interference suppression techniques because a successful war in future largely depends on reliable information transmission. Frequency-hopping (FH) is a promising technique for interference suppression and it is widely used in the civilian and military communication systems, because FH technique has good anti-jamming, anti-fading and anti-interception performance. Besides, it can also alleviate the "far - near" effect caused by interference to some extent. In addition to resisting interference by way of FH technique, we can employ iterative processing technique to reducing interference and thus improve system performance. Iterative processing technique, which using the exchange of useful signal to minimize the loss of information, can obtain better performance than that of traditional receiver.In the second chapter, the jamming suppression method and performance of non-coherent CPM (Continuous Phase Modulation) is studied. The CPM signals offer a narrow spectral mainlobe and extremely low spectral sidelobes which satisfies the requirements of good spectral efficiency. Additionally, CPM signals make it possible to use simple but low-cost power efficient amplifiers (nonlinear power amplifiers).In this Chapter, a finite length of observation window MAP algorithm is investigated to reduce the complexity. In this method, the complexity will not increase significantly as the length of one hop increases. In addition, we can set the length of observation window and thus make better tradeoff between complexity and system performance. The partial-band jamming information method is studied for suppressing partial-band jamming. Simulation results show that the gain of BER performance is within 1.5dB compared to that of the no jamming information estimate at BER 10^-3.Chapter three covers iterative interference suppression algorithm and its performance when non-coherent QPSK modulation is employed. A demodulation algorithm is proposed after assuming phase of signals is given. This algorithm assumes that the phase offset of each hop is fixed, so the phase offset can be divided equally into several parts, based on which we bring up a (grid pattern) trellis. According to the grid pattern, iterative detection result in very good system performance.Since Orthogonal Frequency Division Multiplexing (OFDM) has been adopted by Long Term Evolution (LTE) as a key technique and more attention is aroused on its interference-resist ability, chapter four introduces the application of iterative interference suppression and correspondingly the performance in both CPM-OFDM system and QPSK-OFDM system.