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Studies on an Iterative Frequency Domain Channel Estimation Technique for MIMOUWB Communications
Masaki TAKANASHI Yasutaka OGAWA Toshihiko NISHIMURA Takeo OHGANE
Publication
IEICE TRANSACTIONS on Communications
Vol.E91B
No.4
pp.10841094 Publication Date: 2008/04/01 Online ISSN: 17451345
DOI: 10.1093/ietcom/e91b.4.1084 Print ISSN: 09168516 Type of Manuscript: PAPER Category: Wireless Communication Technologies Keyword: MIMOUWB, MMSEFDE, least square channel estimation, iterative frequency domain channel estimation,
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Summary:
MIMO (MultipleInput MultipleOutput) technologies have attracted much interest for highrate and highcapacity wireless communications. MIMO technologies under frequencyselective fading environments (wideband MIMO technologies) have also been studied. A wideband MIMO system is affected by ISI (Inter Symbol Interference) and CCI (CoChannel Interference). Hence, we need a MIMO signal detection technique that simultaneously suppresses ISI and CCI. The OFDM system and SCFDE (Single CarrierFrequency Domain Equalization) techniques are often used for suppressing ISI. By employing these techniques with the ZF (Zero Forcing) or the MMSE (Minimum Mean Square Error) spatial filtering technique, we can cancel both ISI and CCI. To use ZF or MMSE, we need channel state information for calculating the receive weights. Although an LS (Least Square) channel estimation technique has been proposed for MIMOOFDM systems, it needs a large estimation matrix at the receiver side to obtain sufficient estimation performance in heavy multipath environments. However, the use of a large matrix increases computational complexity and the circuit size. We use frequency domain channel estimation to solve these problems and propose an iterative method for achieving better estimation performance. In this paper, we assume the use of a MIMOUWB system that employs a UWBIR (UltraWideband Impulse Radio) scheme with the FDE technique as the wideband wireless transmission scheme for heavy multipath environments, and we evaluate the iterative frequency domain channel estimation through computer simulations and computational complexity calculations.

