ANALISA KERJA SPACE TIME TRELLIS CODE PADA WIFI SISTEM MIMO (2X2) OFDM
Abstract
Abstrak
Komunikasi Wireless saat ini menuntut adanya penyediaan sistem dengan performansi yang handal, penggunaan bandwidth yang efisien, power yang efisien serta coverage yang lebih baik karena seiring dengan kebutuhan manusia akan aplikasi-aplikasi yang membutuhkan data rate yang tinggi dan cepat. Salah satu konsep dan metoda untuk memenuhi kebutuhan tersebut yaitu menggunakan teknik antena dengan banyak pengirim dan penerima atau sering disebut dengan Multiple Input Multiple Output (MIMO) dengan menambahkan strategi pada saat pengiriman yaitu teknik Space Time Coding (STC). Selain itu, pengaplikasian Orthogonal Frequency Division Multiplexing (OFDM) pada MIMO-STC akan lebih mengefisiensikan penggunaan bandwidth. Metoda Space Time Trellis Code (STTC) sebagai salah satu teknik diversitas pengiriman data dengan pengkodean yang kompleks sehingga tercapainya penguatan pengkodean dan diterapkan pada sistem MIMO OFDM sehingga diharapkan pencapaian akan sistem dengan performansi yang handal dapat dicapai. Simulasi yang dilakukan ini menyajikan skema STTC dan OFDM pada multi antenna (2 pemancar x 2 penerima) dengan Combiner dan algoritma pendeteksi Maximum Likelihood Sequence Estimator (MLSE) pada receiver untuk mendapatkan kualitas sinyal pengiriman dalam analisa performasi Bit Error Rate (BER) dengan Signal to Noise Ratio (SNR). Hasil simulasi diperlihatkan dengan pemodulasian dengan M-aray Phase Shift Keying (MPSK) dan jumlah simbol yang dikirimkan dengan cara memberi nilai masukan parameter yang berbeda. Hasil menunjukkan bahwa dengan pemakaian jumlah carrier dan ukuran Fast Fourier Transform (FFT) yang besar dan jenis modulasi dengan konstelasi yang sedikit menghasilkan BER yang rendah dan troughput pada SNR tinggi.
Kata-kata kunci: MiMo, STC, STTC, OFDM, BER, SNR.
Abstract
Wireless communication nowadays requires the provision of a system with reliable performance, efficient use of bandwidth, efficient power and better coverage because it is in line with human needs for applications that require high and fast data rates. One of the concepts and methods to meet these needs is using an antenna technique with many transmitters and receivers or often called Multiple Input Multiple Output (MIMO) by adding a strategy at the time of delivery, namely the Space Time Coding (STC) technique. In addition, the application of Orthogonal Frequency Division Multiplexing (OFDM) on MIMO-STC will more efficiently use bandwidth. The Space Time Trellis Code (STTC) method is one of the techniques of diversity in sending data with complex coding so that coding reinforcement is achieved and is applied to the OFDM MIMO system so that it is hoped that the achievement of a system with reliable performance can be achieved. The simulation that is carried out presents the STTC and OFDM schemes on multi antennas (2 transmitters x 2 receivers) with a Combiner and Maximum Likelihood Sequence Estimator (MLSE) detection algorithm on the receiver to get the quality of the sending signal in the performance analysis of Bit Error Rate (BER) with Signal to Noise Ratio (SNR). The simulation results are shown by modulation with M-aray Phase Shift Keying (MPSK) and the number of symbols sent by giving different input parameter values. The results show that the use of the number of carriers and the size of the Fast Fourier Transform (FFT) is large and the modulation type with a small constellation produces a low BER and throughput at high SNR.
Keywords: MiMo, STC, STTC, OFDM, BER, SNR.
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