Hybrid slow frequency hopping/ direct sequence spread spectrum indoor communication systems with QPSK modulation

1994 ◽  
Vol 49 (9-10) ◽  
pp. 518-526
Author(s):  
Luc Vandendorpe ◽  
Ramjee Prasad
Author(s):  
Fawzan Galib Abdul Karim Bawahab ◽  
Elvan Yuniarti ◽  
Edi Kurniawan

Abstrak. Pada penelitian ini, telah dilakukan analisa karakterisasi pada teknologi Direct Sequence Spread Spectrum dan Frequency Hopping Spread Spectrum, sebagai salah satu teknik multiple-access pada sistem komunikasi. Karakterisasi dilakukan untuk mencari bagaimana cara meningkatkan keoptimalan kedua sistem tersebut, dalam mengatasi masalah interferensi dengan sistem dan channel yang sama. Dan juga untuk menentukan veriabel apa yang mempengaruhi keoptimalan kedua sistem tersebut. Karakterisasi dilakukan dengan menentukan variabel-variabel yang mempengaruhi keoptimalan keduanya. Hasil dari karakterisasi, diketahui variabel-variabel yang mempengaruhi kemampuan sistem DSSS yaitu nilai frekuensi spreading (). Sedangkan untuk sistem FHSS yaitu nilai frekuensi spreading ( dan ) dan selisih antara frekuensi hopping data dengan frekuensi hopping interferensi . Kata Kunci: BER, DSSS, FHSS, Interference, Spread spectrum. Abstract. In this study, characterization of Direct Sequence Spread Spectrum and Frequency Hopping Spread Spectrum technologies have been done, as one of the multiple-access techniques in communication systems. Characterization is done to find out how to improve the ability of the two systems, in solving interference problems with the same system and channel. And also to determine what veriabel affects the ability of the two systems. Characterization is done by determining the variables that affect the ability of both. The results of the characterization, known variables that affect the ability of the DSSS system are the spreading frequency value (). As for the FHSS system, the spreading frequency value ( and ) and the difference between frequency hopping data with frequency hopping interference .


2020 ◽  
Vol 30 (2) ◽  
pp. 49-54
Author(s):  
I. V. Egorov ◽  
D. V. Gaivoronskii

The physical and logical organization of most existing communication systems provides for additional options (transmission of known preambles, the presence of an additional synchronization channel) that simplify synchronization. At the same time, in the practical implementation of radio communication systems, it is necessary to solve the problems of developing additional synchronization mechanisms that can reduce the time it takes to synchronize to reduce energy consumption and increase channel capacity. Thus, the existing problem of the asynchrony of the generators of physically remote radio stations is relevant. One of the possible solutions is asynchronous signal reception with the direct sequence spread spectrum. It allows converting the original binary signal into a pseudo-random sequence for modulating the carrier. The current article is devoted to the characterization of this method and has the following items presented: the transmitter and receiver block diagram, sufficient to explain the proposed method; methods for compensating for effects arising from the asynchrony of the transmitter and receiver generators. Since synchronization is generated according to the correlation peaks that correspond to the data bits, it is possible to set the frequency of the chips on the transmitter to jitter artificially and supplement the pseudo-random sequence with several random chips, which complicates the unauthorized detection of the transmitted signal.


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