Wyniki wyszukiwania - BazTech

1

Analiza symulacyjna metody synchronizacji ramkowej opartej na symbolach pilota nałożonych na ciąg informacyjny

Sikora M., Ludwin W., Wszołek J.

Przegląd Telekomunikacyjny + Wiadomości Telekomunikacyjne

|

2018

|

nr 6

459--462, CD

PL

W prezentowanej pracy przedstawiono wyniki symulacji komputerowych systemu łączności radiowej, wykorzystującego do wykrywania początku ramki, zaproponowaną w [2], metodę opartą na sumowaniu sekwencji synchronizacyjnej z ciągiem symboli informacyjnych. Badania przeprowadzono zarówno dla przypadku idealnej synchronizacji częstotliwości nadajnika i odbiornika, jak również dla generatorów nośnej 434 MHz o stabilności częstotliwości ±20 ppm, a zatem przy założeniu braku idealnej synchronizacji czasów próbkowania sygnałów w nadajniku i odbiorniku.

EN

This paper presents the results of computer simulations of a radio communication system, which uses frame detection method (proposed in [2]) based on a synchronization sequence insertions into the data stream. Tests were performed for both the perfect synchronization of the transmitter and receiver frequencies, as well as imperfect synchronization of carrier generators operating on 434 MHz with frequency stability of ± 20 ppm.

2

Frequency Offset Compensation for OFDM Systems Using a Combined Autocorrelation and Wiener Filtering Scheme

Ramadan Ali A., Khanzada T. J., Omar A.

Journal of Telecommunications and Information Technology

|

2010

|

nr 1

40-47

EN

One of the orthogonal frequency division multiplexing (OFDM) system disadvantages is its sensitivity to frequency offset and phase noise, which lead to losing the orthogonality between the subcarriers and thereby degrade the system performance. In this paper a joint scheme for frequency offset and pilot-based channel estimation is introduced in which the frequency offset is first estimated using an autocorrelation method, and then is fined further by applying an iterative phase correction by means of pilot-based Wiener filtering method. In order to verify the capability of the estimation algorithm, the scheme has been implemented and tested using a real measurement system in a multipath indoor environment. The results show the algorithm capability of compensating for the frequency offset with different transmission and channel conditions.

3

Blind frequency offset estimation for overlap PCC-OFDM systems in presence of phase noise

Shentu J., Armstrong J.

Journal of Telecommunications and Information Technology

|

2003

|

nr 2

17-27

EN

This paper presents a technique for frequency offset estimation for polynomial cancellation coded orthogonal frequency division multiplexing with symbols overlapped in the time domain (overlap PCC-OFDM) in the presence of phase noise. The frequency offset estimator is designed based on the subcarrier pair imbalance (SPI) caused by frequency offset. The estimation is performed in the frequency domain at the output of the receiver discrete Fourier transform (DFT). No training symbols or pilot tones are required. Simulations show that this estimator is an approximately linear function of frequency offset. Phase noise does not significantly affect the variance performance of the estimator.