Blind Channel Estimation in OFDM Systems by Relying on the Gaussian Assumption of the Input
(Semi) Blind Channel Estimation & Data Recovery in OFDM Presented by: Ahmed Abdul Quadeer Electrical...
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Transcript of (Semi) Blind Channel Estimation & Data Recovery in OFDM Presented by: Ahmed Abdul Quadeer Electrical...
(Semi) Blind Channel Estimation & Data Recovery in OFDM
Presented by: Ahmed Abdul QuadeerElectrical Engineering Department
2nd Graduates Seminar Day
Outline
Wireless Communication System
Transmitter Channel Receiver
OFDM
Problem
Transmitter Channel Receiver
X H Y = H ʘ X
X = Y ./ H
Channel Estimation Techniques
= HELLO
Training Based Technique
Transmitter Channel Receiver
HELLO ЧҒҐЮҨ
X H Y = H ʘ XY and X known
H = Y ./ X Wireless channel is time variant.
Necessary to train periodically Low Bandwidth Efficiency.
HELLO = HELLOℏℱℰℳℭ
Blind Technique
Transmitter Channel Receiver
No training used. Utilize structure of the communication system:
Finite Alphabet Set
Time Correlation
Coding
Data Transmitted = {A, B, C, D}
A 000 and B 111
t
Semi-Blind Technique
Transmitter Channel Receiver
Hybrid of Training and Blind techniques.
Training signal as well as other constraints of communication system are utilized.
Data Aided Technique
Use the refined channel estimate to detect data again. Joint Channel Estimation and Data Detection.
Use detected data to improve the channel estimate .X H
Conclusion
LOW HIGH
Trade off between Computational Complexity and Bandwidth Efficiency
Complexity
Bandwidth Efficiency
Explanation