Title :
Degradation and performance issues of MIMO/OFDM in the presence of motion
Author :
Tejera, Pedro ; Castaneda, Mario ; Morcos, Faruck ; Utschick, Wolfgang
Author_Institution :
Inst. for Circuit Theor. & Signal Process., Munich, Germany
Abstract :
Different degrees of channel knowledge at the transmitter lead to different transmission strategies with disparate performance in a multiple-input multiple-output (MIMO), orthogonal frequency-division multiplexing (OFDM) system. While in a frequency-division duplex (FDD) scheme instantaneous channel knowledge requires the feedback of channel state information (CSI) from the receiver, which, depending on system parameters, might be prohibitive, in a time-division duplex (TDD) system, channel estimates obtained during reception can be made use of during transmission. Thereby, the basic problem is obsolescence of CSI over a frame interval. Applying transmission strategies that adapt to the channel as much as the available CSI allows, the performance of a TDD MIMO/OFDM system is compared and discussed for four degrees of CSI: the theoretical case of perfect instantaneous CSI; perfect CSI that becomes outdated during the transmission of a frame; partial CSI, where partial refers to knowledge of the transmit correlation matrix of the channel; the case of no CSI. To this end, a channel model is introduced that permits the simulation of channel variations due to mobility for different spatial and temporal spreads.
Keywords :
MIMO systems; OFDM modulation; channel estimation; mobile radio; time division multiplexing; FDD scheme; MIMO/OFDM; TDD system; channel estimation; channel knowledge; channel model; channel state information; frequency-division duplex scheme; mobility; multiple-input multiple-output system; orthogonal frequency-division multiplexing system; partial CSI; perfect CSI; perfect instantaneous CSI; spatial spreads; temporal spreads; time-division duplex system; transmission strategies; wireless mobile systems; Broadband antennas; Circuit theory; Degradation; Frequency division multiplexing; Frequency estimation; MIMO; OFDM; Receivers; Signal processing; State feedback;
Conference_Titel :
Vehicular Technology Conference, 2004. VTC 2004-Spring. 2004 IEEE 59th
Print_ISBN :
0-7803-8255-2
DOI :
10.1109/VETECS.2004.1390457