Abstract
In this article, we address the challenges regarding the provision of channel state information as well as reducing peak-to-average power ratio (PAPR) of a multiple input multiple output orthogonal frequency multiplexing (MIMO–OFDM) system. The mean squared error (MSE) of the channel estimate is adopted as the optimization criterion to design pilot symbols for channel estimation in MIMO–OFDM systems with null subcarriers. We design the placement and power distribution to the pilot symbols for multiple transmit antennas to minimize the MSE of the least square (LS) channel estimates. To reduce interference of the pilot symbols transmitted from different antennas, an algorithm to guarantee that pilot symbols are disjoint from any other transmitter pilot set is proposed. To efficiently reduce the PAPR of the MIMO–OFDM signals, a method that mixes dummy symbols and phase information of the pilot symbols is presented. Simulation results based on IEEE 802.16e are presented to illustrate the superior performance of our proposed channel estimation method over the existing standard and the partially equi-spaced pilot symbols. We also demonstrate that, by mixing the dummy symbols and phase information of the pilot symbols, the PAPR of the MIMO–OFDM signals can significantly be reduced.
Highlights
Robustness of orthogonal frequency multiplexing (OFDM) systems in multipath environments together with the significant information capacity gain as well as improved bit error rate (BER) performance of multiple input multiple output (MIMO) systems, highlight the substantial potential of MIMO-OFDM systems [1,2,3]
In this article, we addressed the problem of channel estimation of MIMO–OFDM systems with null subcarriers
We have verified that the designed pilot subcarrier set for each transmit antenna has a better channel estimate performance than the existing equi-spaced and equi-powered IEEE 802.16e standard pilot symbols and the partially equi-spaced pilot symbols
Summary
Robustness of orthogonal frequency multiplexing (OFDM) systems in multipath environments together with the significant information capacity gain as well as improved bit error rate (BER) performance of multiple input multiple output (MIMO) systems, highlight the substantial potential of MIMO-OFDM systems [1,2,3]. We consider a set of frequency domain pilot symbols designed for channel estimation of the received OFDM symbol from the ith transmit antenna and design plausible phase information that lower the peak amplitudes of the pilot symbols in time domain. = XvNt. For an OFDM symbol with NG number of null edge subcarriers or guard subcarriers, we need to select a set of Kv subcarriers and optimally allocate the power as well as phase information to ensure that the designed dummy symbols Xvi , significantly reduces the PAPR of each transmit antenna link. This performance gap is a result of the PEP design having insignificant power distribution to the pilot symbols at the edge of the active subcarrier band which leads to poor estimate of the channels. Addition of the number of dummy symbols may lead to a lower PAPR, but this will increase the total transmit power per OFDM symbol
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callMore From: EURASIP Journal on Wireless Communications and Networking
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
