Model Kanal 5G dengan Pengaruh Kelembapan pada Frekuensi 3,3 GHz dan Bandwidth 99 MHz Berbasis Convolutional Codes

ABSTRAKGenerasi telekomunikasi kelima (5G) diterapkan pada 2021 dengan frekuensi tinggi yang menyebabkan redaman yang besar dibandingkan pita sub-1 GHz. Penelitian ini mengkaji sistem 5G dengan frekuensi operasi 3,3 GHz dan bandwidth 99 MHz berdasarkan spesifikasi 5G dari Cyclic Prefix-Orthogonal Frequency Division Multiplexing (CP-OFDM) numerologi μ = 1 menggunakan parameter lingkungan yang diukur secara langsung di kota Bandung. Penelitian ini menemukan bahwa model kanal 5G dengan pengaruh kelembapan maksimum memiliki power delay profile (PDP) 9 path dengan nilai daya yang lebih kecil dan outage performances (𝑅>𝐶) yang lebih buruk dengan gap sebesar 0,3 dB dibandingkan dengan pengaruh kelembapan minimum. Hasil penelitian menunjukkan bahwa penggunaan convolutional codes dapat membantu menghemat Signal to Noise Ratio (SNR) dengan gap sebesar 3 dB. Hasil dari penelitian ini diharapkan dapat memberikan kontribusi bagi perkembangan komunikasi nirkabel 5G di Indonesia.Kata kunci: 5G, model kanal, convolutional codes, PDP, FER, BER. ABSTRACTThe fifth generation of telecommunications (5G) implemented in 2021, where high frequency which causes a large attenuation compared to the sub-1 GHz band. This research examines a 5G system with an operating frequency of 3.3 GHz and a bandwidth of 99 MHz based on the 5G specification of the Cyclic Prefix - Orthogonal Frequency Division Multiplexing (CP-OFDM) numerology μ = 1 using environmental parameters measured directly in Bandung, Indonesia. This research shows that the 5G channel model under maximum humidity has a 9 power delay profile (PDP) with a smaller power value and worse outage performances (𝑅>𝐶) with a gap of 0.3 dB compared to the effect of minimum humidity. The results showed that the use of convolutional codes can save the Signal to Noise Ratio (SNR) with gap of 3 dB. The results of this research are expected to contribute to the development of 5G wireless communications in Indonesia.Keywords: 5G, channel model, convolutional codes, PDP, FER, BER.

Statistical Analysis of 5G Channel Propagation using MIMO and Massive MIMO Technologies

Multiple Input Multiple Output (MIMO) and massive MIMO technologies play a significant role in mitigating five generation (5G) channel propagation impairments. These impairments increase as frequency increases, and they become worse at millimeter-waves (mmWaves). They include difficulties of material penetration, Line-of-Sight (LoS) inflexibility, small cell coverage, weather circumstances, etc. This paper simulates the 5G channel at the E-band frequency using the Monte Carlo approach-based NYUSIM tool. The urban microcell (UMi) is the communication environment of this simulation. Both MIMO and massive MIMO use uniformly spaced rectangular antenna arrays (URA). This study investigates the effects of MIMO and massive MIMO on LOS and Non-LOS (NLOS) environments. The simulations considered directional and omnidirectional antennas, the Power Delay Profile (PDP), Root Mean Square (RMS) delay spread, and small-scale PDP for both LOS and NLOS environments. As expected, the wide variety of the results showed that the massive MIMO antenna outperforms the MIMO antenna, especially in terms of the signal power received at the end-user and for longer path lengths.

PHY, MAC, and RLC Layer Based Estimation of Optimal Cyclic Prefix Length

This work is motivated by growing evidence that the standard Cyclic Prefix (CP) length, adopted in the Long Term Evolution (LTE) physical layer (PHY) specifications, is oversized in propagation environments ranging from indoor to typical urban. Although this ostensibly seems to be addressed by 5G New Radio (NR) numerology, its scalable CP length reduction is proportionally tracked by the OFDM symbol length, which preserves the relative CP overhead of LTE. Furthermore, some simple means to optimize fixed or introduce adaptive CP length arose from either simulations or models taking into account only the bit-oriented PHY transmission performance. On the contrary, in the novel crosslayer analytical model proposed here, the closed-form expression for the optimal CP length is derived such as to minimize the effective average codeblock length, by also considering the error recovery retransmissions through the layers above PHY—the Medium Access Control (MAC) and the Radio Link Control (RLC), in particular. It turns out that, for given protective coding, the optimal CP length is determined by the appropriate rms delay spread of the channel power delay profile part remaining outside the CP span. The optimal CP length values are found to be significantly lower than the corresponding industry-standard ones, which unveils the potential for improving the net throughput.

Effects of Synchronization Errors on Wavelet-based CR-OFDM Systems in Doubly Selective Fading Channels

The Major Setback of a Multi-Carrier Modulation (MCM) is Synchronization Errors, which includes time, frequency and phase offset. Especially, Wavelet based MCM catches the eyes of researchers due to its flexibilities which are seen as one of the strong contender for Cognitive Radios. Synchronization errors are mainly due to mobility between nodes and sub-optimal local oscillators and it is necessary to learn the behavior of wavelets under these channel fading conditions. In this paper, we present the joint effects of Wavelet-based Cognitive Radio OFDM (CR-WOFDM) systems under Synchronization Error in terms of based bit error rate (BER). BER Outputs of WOFDM is compared with FFT based OFDM with Cyclic Prefix (CP-OFDM) systems in a doubly-selective channel by designing a communication system for computer simulation. Several well-known wavelets are chosen and analyzed, including Daubechies (db), Symlets (sym), Coiflets (coif), Fejér-Korovkin (fk) filters, and biorthogonal (bior) wavelets. First, we show the behavior of wavelets in terms of BER by considering different doubly selective channel Power Delay Profile (PDP) like, AWGN, FLAT, Pedestrian and Vehicular and channel Doppler models like, Uniform and JAKES. Finally, we calculate and plot Signal-to-Interference Ratio (SIR) of WOFDM with Time and Frequency Offset and compared the results with FFT based CP-OFDM.

Analysis of Non-Stationarity for 5.9 GHz Channel in Multiple Vehicle-to-Vehicle Scenarios

The vehicle-to-vehicle (V2V) radio channel is non-stationary due to the rapid movement of vehicles. However, the stationarity of the V2V channels is an important indicator of the V2V channel characteristics. Therefore, we analyzed the non-stationarity of V2V radio channels using the local region of stationarity (LRS). We selected seven scenarios, including three directions of travel, i.e., in the same, vertical, and opposite directions, and different speeds and environments in a similar driving direction. The power delay profile (PDP) and LRS were estimated from the measured channel impulse responses. The results show that the most important influences on the stationary times are the direction and the speed of the vehicles. The average stationary times for driving in the same direction range from 0.3207 to 1.9419 s, the average stationary times for driving in the vertical direction are 0.0359–0.1348 s, and those for driving in the opposite direction are 0.0041–0.0103 s. These results are meaningful for the analysis of the statistical characteristics of the V2V channel, such as the delay spread and Doppler spread. Small-scale fading based on the stationary times affects the quality of signals transmitted in the V2V channel, including the information transmission rate and the information error code rate.

A Geometry-Based Beamforming Channel Model for UAV mmWave Communications

Considering the three-dimensional (3D) trajectory, 3D antenna array, and 3D beamforming of unmanned aerial vehicle (UAV), a novel non-stationary millimeter wave (mmWave) geometry-based stochastic model for UAV to vehicle communication channels is proposed. Based on the analysis results of measured and ray tracing simulation data of UAV mmWave communication links, the proposed parametric channel model is constructed by a line-of-sight path, a ground specular path, and two strongest single-bounce paths. Meanwhile, a new parameter computation method is also developed, which is divided into the deterministic (or geometry-based) part and the random (or empirical) part. The simulated power delay profile and power angle profile demonstrate that the statistical properties of proposed channel model are time-variant with respect to the scattering scenarios, positions and beam direction. Moreover, the simulation results of autocorrelation functions fit well with the theoretical ones as well as the measured ones.

Measurement and Statistical Analysis of Distinguishable Multipaths in Underground Tunnels

Compared with the line-of-sight (LOS) condition, the multipath effect is more serious in the non-line-of-sight (NLOS) condition. Therefore, the LOS and NLOS identification is necessary for the multipath analysis of signal propagation. The commonly used method is the support vector machine (SVM) method with high computational complexity. To tackle this problem, this paper adopts the SVM classifier based on fewer selected features of the normalized power delay profile (PDP). Therein, the PDP can be obtained using the sliding correlation method. The results show that the SVM-based classifier can achieve high accuracy on LOS and NLOS identification. We then analyze the impact of the signal-to-noise ratio (SNR) and transmitting-receiving (Tx-to-Rx) distance on distinguishable multipaths under LOS and NLOS conditions. According to statistical measurement results, a function of distinguishable multipath numbers is established. Finally, we investigate the multipath power and delay parameters of average delay spread and root mean square (RMS) delay spread based on multipath results. The outcomes of this paper provide a useful support for analyzing signal propagation characteristics.

Analisa Karakteristik Kanal HF Lintasan Jamak

Indonesia merupakan negara kepulauan terbesar di dunia. Oleh karena itu, diperlukan konsep dan perencanaan sistem komunikasi jarak jauh yang murah dan handal agar bisa terhubungnya komunikasi di wilayah kepulauan yang relatif sulit dijangkau oleh sistem kabel yang sudah terhubung saat ini. Sistem komunikasi high frequency (HF) yang beroperasi pada frekuensi 3-30 MHz. Sistem ini memanfaatkan lapisan ionosfer sebagai media transmisi gelombang radionya. Lapisan ionosfer sangat dipengaruhi oleh aktivitas matahari dan perubahan waktu sepanjang hari. Hal ini berakibat timbulnya gangguan-gangguan ionosfer yang menyebabkan kinerja sistem komunikasi HF terganggu juga kondisi dimana terdapat interferensi ketika sinyal lebih dari satu jalur pada saat ditransmisikan hal ini dinamakan multipath atau lintasan jamak. Karakteristik kanal HF menjadi hal yang sangat penting. Dengan mengetahui karakteristik kanal HF yang tepat kita dapat mencapai kinerja sistem komunikasi yang lebih baik. Perubahan kondisi lapisan ionosfer berpotensi mempengaruhi kinerja sistem komunikasi HF yang disebabkan oleh nilai delay spread. Pada penelitian ini dilakukan analisa parameter karakteristik kanal HF mengenai power delay profile dan delay spread yang dilakukan dengan uji simulasi. Berdasarkan hasil percobaan dalam kurun waktu 2 bulan. Dilakukan sebanyak 8 kali percobaan dalam 4 waktu yang berbeda. Menghasilkan nilai delay spread maksimal terjadi pada pagi hari yaitu bernilai 124,1 ms berbeda dengan sore hari yang memiliki nilai 41 ms.