Equal-gain combining with interference mitigation for molecular type hopping assisted molecular shift keying systems

In multiple access molecular diffusive communications, many nano-machines exchange information and fuse data through a common Diffusive Molecular Communication (DMC) channel. Hence, there is Multiple-Access Interference (MAI), which should be sufficiently mitigated so as to achieve reliable communications. In this paper, we propose a novel low-complexity detection scheme, namely Equal-Gain Combining with Interference Mitigation (EGC-IM), for signal detection in the Molecular Type Hopping assisted Molecular Shift Keying (MTH-MoSK) DMC systems. By removing a number of entries from each row of the detection matrix formed during detection, the EGC-IM scheme shows its potential to significantly mitigate MAI and hence, outperform the conventional EGC scheme. Furthermore, the EGC-IM scheme has lower complexity than the conventional EGC scheme and therefore, it is beneficial for practical implementation.

DIVERSITY SIGNAL PROCESSING OVER WEIBULL FADING CHANNELS

We present a moments-based approach to the performance analysis of L-branch equal-gain combining and maximal-ratio combining receivers, operating in independent or correlated, not necessarily identically distributed, Weibull fading. For both equal-gain combining and maximal-ratio combining receivers the moments of the output signal-to-noise ratio are obtained in closed-form. An accurate approximate expression is derived for the moment-generating function of the output signal-to-noise ratio of the equal-gain combining receiver utilizing the Padé approximants theory, while a closed-form expression for the corresponding MGF of the maximal-ratio combining receiver, is obtained. Significant performance criteria, such as average output signal-to-noise ratio, amount of fading and spectral efficiency at the low power regime, are extracted in closed-forms, using the moments of the output signal-to-noise ratio for both independent and correlative fading. Moreover, using the well-known moment-generating function approach, the outage and the average symbol error probability for several coherent, non-coherent, binary, and multilevel modulation schemes, are studied. The average symbol error probability of dual-branch equal-gain combining and maximal-ratio combining receivers is also obtained when correlative fading is considered in the diversity input branches. The proposed mathematical analysis is illustrated by various numerical results and validated by computer simulations.

Dynamic Spatial Diversity Combiner pada Kanal Fading

ABSTRAKKanal transmisi radio berkontribusi pada terjadinya efek fading yang dapat berpengaruh pada terjadinya penurunan kualitas sinyal pada penerima. Salah satu solusi yang digunakan untuk menekan efek fading adalah penggunaan Spatial Diversity di sisi penerima. Pada penelitian ini digunakan suatu teknik Dynamic Spatial Diversity Combining yang memadukan Selection Combining, Equal Gain Combining, dan Maximal Ratio Combining untuk mendapatkan kinerja combiner yang lebih efektif dan efisien. Simulasi dilakukan dengan menggunakan modulasi BPSK pada beberapa jenis kanal yaitu Rayleigh, Rician, Nakagami-m, Weibull, dan Suzuki. Hasil simulasi MATLAB menunjukkan bahwa secara umum kanal yang mendapatkan perbaikan kinerja penerimaan, dimana nilai terendah sebesar 2 dB terjadi pada kanal Suzuki dan tertinggi sebesar 4 dB pada kanal Weibull.Kata kunci: fading, spatial diversity, rayleigh, rician, weibull, nakagami, suzuki. ABSTRACTRadio transmission channels contribute to the occurrence of fading effects that can affect the decrease in signal quality at the receiver. One solution that is used to suppress fading effects is the use of Spatial Diversity on the receiving side. In this research, a Dynamic Spatial Diversity Combining technique is used which combines Selection Combining, Equal Gain Combining, and Maximal Ratio Combining to get a more effective and efficient combiner performance. Simulation is done using BPSK modulation on several types of canals, namely Rayleigh, Rician, Nakagamim, Weibull, and Suzuki. The MATLAB simulation results show that in general canals that get improved performance, where the lowest value of 2 dB occurs on the Suzuki channel and the highest is 4 dB on the Weibull canal.Keywords: fading, spatial diversity, rayleigh, rician, weibull, nakagami, suzuki.