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This paper presents a multiple-access MIMO wireless transceiver combining space- and frequency-domain spreadings with a frequency-domain block-coding strategy. Spreading across space (transmit antennas) and frequency (subcarriers) adds resilience against deep channel fades while providing space and frequency diversities, and block-coding enables multiple-access transmission. The merits of the proposed...
In this paper, both a time-domain and a frequency-domain 2 × 2 MIMO channel sounders are presented. The time-domain channel sounder is mainly based on the transmission of Code Division Multiplexed (CDM) signals, modulated by a carrier, which are received and acquired by an oscilloscope. The frequency-domain channel sounder is based on a multiport network analyzer which measures the S21 scattering...
For mitigating inter-symbol interference (ISI) and inter-carrier interference (ICI) caused by insufficient cyclic prefix (CP), per-tone equalizer (PTEQ) outperforms traditional time domain equalizer (TEQ) since each tone is equalized independently. However, PTEQ with equal number of taps (equal length) for all the tones can not achieve the optimal performance because channel conditions of different...
In the LTE-Advanced downlink, to satisfy high-level performance requirements, advanced multi-antenna transmission techniques such as higher-order single-user (SU)-MIMO, multi-user (MU)-MIMO, and coordinated multi-point transmission/reception (CoMP) are key. At the 3GPP RAN WG1 meeting, the demodulation reference signal (DM-RS) was defined to support channel estimation and data demodulation for up...
Obtaining reliable channel state information (CSI) in future wireless standards is critical for the operation of downlink closed-loop techniques such as SU-MIMO, MU-MIMO, and coordinated multipoint (CoMP). However, this CSI is difficult to obtain especially when considering the potentially strong interference from neighboring sectors/base stations on the downlink reference symbols (RSs, aka pilot...
An estimation technique for Time-Invariant (TI) channels that utilizes an Extrapolation Matrix (EM) and specially designed pilot sequences is presented. We address the topic of pilot aided multi-user channel estimation for a proposed wireless system that uses OFDM in a synchronous SDMA environment, which can also be regarded as a Multiple-Input Multiple-Output (MIMO) environment. Unlike most multi-user...
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