A simulation study of using communication signals for ranging
Khalek, Md Abdul (2021)
Khalek, Md Abdul
2021
Master's Programme in Information Technology
Informaatioteknologian ja viestinnän tiedekunta - Faculty of Information Technology and Communication Sciences
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Hyväksymispäivämäärä
2021-06-22
Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi:tuni-202106135844
https://urn.fi/URN:NBN:fi:tuni-202106135844
Tiivistelmä
Orthogonal frequency division multiplexing (OFDM) is a massive multicarrier technology which has been widely applied for the huge amount of data transmission in wireless communication. This technology is also more popular due to its advantageous benefits over other modulation schemes such as adaptability in severe channel condition, ability to cope up with new technology, robustness against multipath effects and the overall transmission quality etc. But there will still remain some issues with OFDM system if it is not properly aligned with suitable wireless scenario. Hence the importance of adjustment of OFDM system with proper parameters in wireless communication is really vast and the matter of huge research for present and future technological advancement. As a trend of development in wireless communication, we worked on two aspects of OFDM system one is OFDM signal for communication, and another is OFDM signal for ranging. However, we carried out the performance of the OFDM system for communication and ranging for wireless signals in MATLAB simulation by this thesis work. The first part of this work is based on the OFDM signal for communication. Here we investigated the communication performance of the OFDM system by applying on AWGN, Rayleigh fading and tapped-delay-line A(TDL-A) channel model with the combination of different parameters, for instance, cyclic prefix (CP) lengths, channel lengths, Quadrature Amplitude Modulation (QAM) schemes. Whenever we think about the OFDM system in multipath scenario, one major impediment intersymbol interference (ISI) automatically appears in the network which leads to the high bit-error-rate (BER) in the transmission. In order to overcome the dilapidated situation, suitable alignment of CP lengths must be ensured based on the multipath scenario. Another important factor is choosing appropriate modulation schemes because it also plays a vital role in case of data transmission. Modulation scheme allows how many bits will be transmitted. However, all of these combinations have been taken in consideration to achieve the better communication performance. The second part of this research work is based on target localization in OFDM system, we studied here on both the direction-of-arrival (DOA) and Time-of-arrival (TOA) estimation method for OFDM communication. For both the DOA and TOA estimation signal subspace-based Multiple Signal Classification (MUSIC) algorithm has been applied. The subspace-based technique usually divides the covariance matrix into two subspaces, signal subspace and noise subspace. Based on this two subspaces MUSIC returns estimation result smoothly by spectrum searching process. In order to enhance estimation accuracy, first we explored out resolvable angles and resolvable delays with respect to different parameters for DOA and TOA respectively, and then, in case of DOA estimation, how the parameters e.g. signal-to-noise ratio (SNR), the number of snapshots, the number of elements, the number of elements spacing etc. hinder and assist the estimation process. Similarly, in TOA estimation, the effect of SNR, the number of snapshots, the number of subcarriers, the subcarrier spacings have been identified. However, by performing this over all research work, we justified and figured out the issues, finally explored out an innovative high resolution estimation method for both the DOA and TOA towards target localization.