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OFDM Synthetic Aperture Radar Imaging with Sufficient Cyclic Prefix
The existing linear frequency modulated (LFM) (or step frequency) and random
noise synthetic aperture radar (SAR) systems may correspond to the frequency
hopping (FH) and direct sequence (DS) spread spectrum systems in the past
second and third generation wireless communications. Similar to the current and
future wireless communications generations, in this paper, we propose OFDM SAR
imaging, where a sufficient cyclic prefix (CP) is added to each OFDM pulse. The
sufficient CP insertion converts an inter-symbol interference (ISI) channel
from multipaths into multiple ISI-free subchannels as the key in a wireless
communications system, and analogously, it provides an inter-range-cell
interference (IRCI) free (high range resolution) SAR image in a SAR system. The
sufficient CP insertion along with our newly proposed SAR imaging algorithm
particularly for the OFDM signals also differentiates this paper from all the
existing studies in the literature on OFDM radar signal processing. Simulation
results are presented to illustrate the high range resolution performance of
our proposed CP based OFDM SAR imaging algorithm.Comment: This version has been accepted by IEEE Transactions on Geoscience and
Remote Sensing. IEEE Transactions on Geoscience and Remote Sensing 201
IRCI Free Range Reconstruction for SAR Imaging with Arbitrary Length OFDM Pulse
Our previously proposed OFDM with sufficient cyclic prefix (CP) synthetic
aperture radar (SAR) imaging algorithm is inter-range-cell interference (IRCI)
free and achieves ideally zero range sidelobes for range reconstruction. In
this OFDM SAR imaging algorithm, the minimum required CP length is almost equal
to the number of range cells in a swath, while the number of subcarriers of an
OFDM signal needs to be more than the CP length. This makes the length of a
transmitted OFDM sequence at least almost twice of the number of range cells in
a swath and for a wide swath imaging, the transmitted OFDM pulse length becomes
long, which may cause problems in some radar applications. In this paper, we
propose a CP based OFDM SAR imaging with arbitrary pulse length, which has IRCI
free range reconstruction and its pulse length is independent of a swath width.
We then present a novel design method for our proposed arbitrary length OFDM
pulses. Simulation results are presented to illustrate the performances of the
OFDM pulse design and the arbitrary pulse length CP based OFDM SAR imaging.Comment: 29 pages, 10 figures, regular pape
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