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Impact of Cooperative Space-Time/Frequency Diversity in OFDM Based Wireless Sensor Systems over Mobile Multipath
Jiayi Zhang1, Hamid Gharavi1, Bin Hu1
1National Institute of Standards and Technology, Gaithersburg, MD 20899-8920, USA.
IET Wireless Sensor Systems
|April 15, 2024
Summary
Cooperative linear dispersion coding (LDC) enhances wireless sensor networks by providing space-time/frequency diversity gains. This method outperforms traditional codes in complex fading channels, especially with multiple cooperative nodes.
Area of Science:
- Wireless communication systems
- Signal processing for wireless networks
- Information theory in wireless communications
Background:
- Virtual multi-input multi-output (MIMO) systems require robust coding schemes.
- Orthogonal frequency division multiplexing (OFDM) is widely used in wireless sensor systems.
- Achieving space-time/frequency (ST/SF) diversity is crucial for reliable communication over fading channels.
Purpose of the Study:
- Investigate spatial diversity applications of cooperative linear dispersion coding (LDC) in OFDM-based wireless sensor systems.
- Evaluate the performance of cooperative LDC-aided ST/SF-OFDM over time-/frequency-selective fading channels.
- Compare cooperative LDC with cooperative orthogonal block codes for ST/SF diversity gains.
Main Methods:
- Implementation of cooperative linear dispersion coding (LDC) for virtual MIMO systems.
- Application of LDC to orthogonal frequency division multiplexing (OFDM) for ST/SF diversity.
- Analysis of system performance under varying channel Doppler and delay spreads.
- Comparison with cooperative orthogonal block codes (e.g., Tarokh's codes).
Main Results:
- Cooperative LDC-aided ST/SF-OFDM offers flexibility in system configuration (nodes, time-slots, frequency-tones).
- The ST-OFDM scheme's diversity gains are sensitive to channel Doppler spreads.
- The SF-OFDM scheme's performance is primarily influenced by delay spread.
- Cooperative LDC-aided ST/SF-OFDM surpasses cooperative orthogonal block codes when more than two nodes are involved in high Doppler/delay spread environments.
Conclusions:
- Cooperative LDC provides a flexible and effective approach for achieving ST/SF diversity in OFDM-based wireless sensor systems.
- The choice between ST-OFDM and SF-OFDM depends on the dominant channel characteristic (Doppler vs. delay spread).
- Cooperative LDC demonstrates superior performance over traditional codes in challenging wireless channel conditions with multiple cooperative nodes.
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