A Novel SNR Estimation Technique for OFDM Systems

Shahid Manzoor, Shahid (2008) A Novel SNR Estimation Technique for OFDM Systems. Masters thesis, Universiti Teknologi Petronas.

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Abstract

Orthogonal Frequency Division Multiplexing (OFDM) systems have received a lot of
attention because of their robust performance in frequency dispersive channels. Further
performance improvement is achieved by employing more sophisticated receiver
techniques that often require the knowledge of signal-to-noise ratio (SNR) - broadly
defined as the ratio of the desired signal power to the unwanted noise power. For
example, noise variance and, hence, signal to noise ratio (SNR) estimates of the received
signal are very important for the channel quality control in communication systems.
Similarly. in advanced communication systems, SNR estimation is used for adaptive
algorithms for modulation, power control and coding.
The objective of the work undertaken in this thesis is to design a front-end noise power
estimator and. thence, SNR estimator. The proposed SNR estimator utilizes the OFDM
preamble signal - the preamble used for synchronization. The estimation is achieved by
auto correlating the preamble and it is deployed right at the front-end of the receiver.
Noise power and. hence, signal power is estimated from the correlation results. The
technique is also extended to obtaining noise power estimates of colored noise using
wavelet-packet based filter bank analysis of the noise.
In order to benchmark the proposed noise power and SNR estimation technique, a
complete end-to-end fixed-broadband-wireless-access-system (IEEE 802.16d) simulation
has been developed and the results are compared with other works reported in the
literature. The simulations are conducted in both frequency non-dispersive and dispersive
channels with real additive white Gaussian noise (AWGN) and also colored noise. It is
observed that the proposed estimator gives better SNR estimates. The proposed estimator
is also checked with WiMAX systems (IEEE802.16d. 2004) using SUI multipath
channels and with Wi-Fi systems (IEEE802.1la) with indoor channel models. The
estimator performs SNR estimation at front-end of the receiver unlike all other estimators
which perform SNR estimation at back-end of the receiver. Furthermore, the proposed
estimator has relatively low computational complexity. for it makes use of only one OFDM preamble signal to find the SNR estimates. The criteria of good SNR estimator
are accuracy of estimates. low complexity and easy to implement. The results show that
the proposed estimator fulfills these criteria successfully.

Item Type: Thesis (Masters)
Subjects: T Technology > TK Electrical engineering. Electronics Nuclear engineering
Departments / MOR / COE: Engineering > Electrical and Electronic
Depositing User: Users 5 not found.
Date Deposited: 11 Jan 2012 12:18
Last Modified: 15 May 2023 07:21
URI: http://utpedia.utp.edu.my/id/eprint/1033

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