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Journal : Jurnal Nasional Teknik Elektro dan Teknologi Informasi

Alokasi Resource bagi Multicarrier-Low Density Sequence-Multiple Access Linda Meylani; Nur Andini; Desti Madya Saputri; Iswahyudi Hidayat
Jurnal Nasional Teknik Elektro dan Teknologi Informasi Vol 11 No 1: Februari 2022
Publisher : Departemen Teknik Elektro dan Teknologi Informasi, Fakultas Teknik, Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (1727.992 KB) | DOI: 10.22146/jnteti.v11i1.2303

Abstract

Multicarrier low-density sequence multiple access (MC-LDSMA) is a code domain type of non-orthogonal multiple access (NOMA) in a multicarrier system. Each user in this multiple access scheme has a non-orthogonal code to one another. Each user is only allowed to access dv from the available N resources and there are only dc users from the total of J users accessing the same resource. The non-orthogonal nature causes the MC-LDSMA system to have a higher overloading factor than other orthogonal multicarrier systems. This condition causes MC-LDSMA to become one of the multiple access techniques used in underlay cognitive radio communication systems, where secondary users (SUs) are permitted to access resources owned by primary users (PUs). This paper proposed a resource allocation algorithm for MC-LDSMA in an underlay cognitive radio system. The proposed algorithm aims to increase the number of SUs accessing PUs resources while maintaining the SUs quality factor. The system built consisted of I PUs and J SUs. PUs in the system was assumed to be orthogonal so that they did not interfere with each other. At the same time, some J SUs simultaneously accessed resources owned by PU using the MC-LDSMA multiple access schemes. The proposed algorithm considered several factors, including the parameters dc, dv, SU target signal-to-noise ratio (SNR), and the interference tolerance limit desired by PU. Performance parameters were indicated by the outage probability (OP), the throughput of PU and SU, and the ratio of the number of SUs that were allocated less than dv resources. The simulation results suggest that all performance parameters are affected by the number of resources accessed by each user, dv, the target SNR of SU, and the interference limit determined by PU.
Pengaruh Pembobotan Desain Codebook terhadap Kinerja Sistem Sparse Code Multiple Access Shilvy Fatma Fitria Rachmawati Fatma; Linda Meylani; Vinsensius Sigit Widhi Prabowo
Jurnal Nasional Teknik Elektro dan Teknologi Informasi Vol 13 No 2: Mei 2024
Publisher : Departemen Teknik Elektro dan Teknologi Informasi, Fakultas Teknik, Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22146/jnteti.v13i2.9430

Abstract

Sparse code multiple access (SCMA) can support the system when overloading on the receiving side, thereby improving the system’s spectral efficiency by designing mapping symbols appropriately. The performance of SCMA is assessed through the utilization of a sparse codebook, wherein bits are directly mapped to multidimensional codewords influenced by both the energy diversity and the minimum Euclidean distance of the multidimensional constellation (MC). The codebook design simulation was conducted using both Latin and non-Latin generators with phases of 60° and 45°, incorporating weighting values of w1 = 0.6; w2 = 0.3; w3 = 0.1. The simulation also included line constellation with additive white Gaussian noise (AWGN) channel, Rayleigh fading, and Rician channel. This study presented the optimal results across three channels: Latin 60° with BER 10−3 in the AWGN channel, non-Latin 60° with BER 10−3 in the Rayleigh fading, and non-Latin 45° with BER 10−3 in the Rician channel. Then, the results on the codebook design weighting were as follows: Latin 60° with BER 10−1 in the AWGN channel, non-Latin 45° with BER 10−1 in the Rayleigh fading, and Latin 45° with BER 10−3 in the Rician channel. The simulation results state the effect of weighting on each channel. It was found that Latin generators could improve BER performance by suppressing overlap at constellation points and eliminating errors occurred in SCMA codebooks. However, this improvement was observed only in AWGN channels and not for non-Latin generators.