Research of Anti-Multipath Interference Capability in Direct Sequence Spread Spectrum Communication System by Simulation

2013 ◽  
Vol 846-847 ◽  
pp. 592-595
Author(s):  
Ping Hua Zhang ◽  
Xiu Liang Huang ◽  
Zhong Yue He
Keyword(s):  
Time Delay ◽  
Fading Channels ◽  
Spread Spectrum ◽  
Communication System ◽  
Rayleigh Fading ◽  
Multipath Fading ◽  
Direct Sequence Spread Spectrum ◽  
Rayleigh Fading Channels ◽  
Direct Sequence ◽  
Simulation Results

The effects of multipath fading with time delay longer or shorter than one chip interval on DSSS system are mathematically and experimentally researched. Simulation results indicate that DSSS system can efficiently overcome multipath fading in multipath Rayleigh Fading channels. And the spreading gain is not the higher the better, it must be chosen reasonably.

scholarly journals Digital Modulator and Demodulator IC for RFID Tag Employing DSSS and Barker Code

2012 ◽  
Vol 10 (6) ◽  
Author(s):  
M. S. Amin ◽  
M. B. I. Reaz ◽  
J. Jalil ◽  
L. F. Rahman
Keyword(s):  
Radio Frequency Identification ◽  
Spread Spectrum ◽  
Multipath Fading ◽  
Cmos Technology ◽  
Direct Sequence Spread Spectrum ◽  
Direct Sequence ◽  
Rfid Tag ◽  
Frequency Identification ◽  
Simulation Results ◽  
Barker Code

Radio frequency identification (RFID) is lagging behind because of vendor specific solutions and expensiveimplementation cost. In particular, the reader is the most expensive part. A WiFi compatible tag was proposed to usethe WNIC as an RFID reader. However, no specific modulator or demodulator was suggested. This paper analyzesthe various IEEE 802.11 standards and their modulation and coding techniques keeping the desired properties of anRFID system in consideration. After the analysis, a digital modulator and demodulator for RFID tag in IEEE 802.11protocol employing Direct Sequence Spread-Spectrum (DSSS) and coding is proposed. A MOD-11 synchronouscounter is designed for the 11-bit encoder which generates the desired Barker code. Data are multiplied with thisBarker code to modulate the data, and the received data are multiplied with the Barker code to demodulate them. Theproposed modulator and demodulator are implemented in 0.18μm CMOS technology. The simulation results showthat 1 bit is spread to 11 bits by the modulator and 11-bit received data are demodulated to 1 bit correctly. Theproposed design is simple, resistant to multipath fading and interference and offers the highest distance with thelowest BER for an RFID tag.

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