ÖZETÇEBu çalışmada, birden çok kaynağın karşılıklı olarak bilgi ilettiği iki yönlü röleli iletişim kanalında modülasyon çeşitlemesinin olası yararları incelenmiştir. Tek röleli ve iki kaynaktan oluşan temel yapı altında, modülasyon çeşitlemesi tekniğinin çöz-ve-ilet (DF, 'Decode-and-Forward') ve yükseltve-ilet (AF, 'Amplify-and-Forward') protokolleri ile birlikte uygulandığı sistem önerilmiştir. Tasarlanan sistemin sönümlemeli kanallardaki başarımı bilgisayar benzetimleri yardımıyla incelenmiş ve modülasyon çeşitlemesinin her iki protokol için sembol hata oranı başarımını arttırdığı gösterilmiştir.
ABSTRACTIn this work, modulation diversity is exploited for two way relay channel through which multiple sources transmit information to each other. Under a basic framework with two sources and a single relay, a system applying modulation diversity technique together with decode-and-forward (DF) and amplify-and-forward (AF) protocols is proposed. The performance of the proposed scheme is investigated through simulation results and modulation diversity is shown to improve the performance in terms of symbol error rate for both two protocols.
In this work, we investigate the effects of asynchronism arised by time delay between the source and relay transmissions over the wireless relay channel. We revise the maximum-a-posteriori (MAP) type detector designed for synchronous case and proposed a receiver for asynchronous relay channel. We also integrate source-relay cooperation with the low density parity check (LDPC) codes in decode and forward (DF) mode to enhance the system performance. The convergence threshold of the overall system is evaluated using extrinsic information transfer (EXIT) chart analysis. Also the performance of asynchronous system is compared with synchronous counterpart via Monte Carlo simulations for various level of delay time. Using the convergence behaviour and simulation results, its demonstrated that that the proposed receiver can cope with asynchronized transmission over the ergodic fading relay channel.
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