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In the paper, we examine Doppler spectrum and bit-error rate (BER) performance of multiuser MIMO systems in an indoor time-varying environment based on our measured data conducted in a meeting room. Simulation results show that both Doppler spectrum and the BER performance are much dependent on the array orientation and the direction of the receiver motion. In the non-line-of-sight environment, the...
Frequency-domain equalization (FDE) has been studied for suppressing inter-symbol interference (ISI) due to frequency selective fading in single carrier systems. When a highmobility terminal is assumed in the system, channel transition within an FFT block cannot be ignored. Then, the ISI reduction performance of FDE degrades since cyclicity of the channel matrix is lost. To solve this problem, we...
In future cellular radio such as IMT-advanced systems, we will encounter a difficulty in sending uplink signals. This is because transmit power is limited by a battery in a terminal and we need higher transmit power to accommodate a wider frequency bandwidth in a higher frequency band. Virtual MIMO-based cooperative communication is expected to be a key technology to solve this problem. Especially,...
Recently, a multiuser MIMO system has attracted much attention. In the downlink of the multiuser MIMO system, since the base station simultaneously transmits signals to terminals, there is inter-user interference (IUI) at each terminal. Block diagonalization, which can achieve perfect IUI suppression, has been extensively studied to solve the issue. However, with the scheme we cannot obtain extra...
The UWB-IR (ultra wideband-impulse radio) technology and MIMO system have attracted interest for next generation high rate radio communications. The authors researched IMO-UWB systems using the FDE (frequency domain equalization) technique with the MMSE spatial filtering technique. The UWB system will be used in short range wireless transmissions. Then, we usually have line-of-sight (LOS) environments...
MIMO channel characteristics and spatial multiplexing are investigated from the viewpoint of antennas and propagation in this paper. We conducted 4x4 MIMO channel measurement campaigns in an indoor propagation environment. Using the measured data, we examined the detail of the MIMO channels. The MIMO channels and eigenvalues are largely different for MIMO array orientations in an LOS environment....
This paper deals with experimental considerations for an eigenbeam-space division multiplexing (E-SDM) system with time division duplex downlink in multiple-input multiple-output channels. Channel information in E-SDM is necessary for a transmitter. If the time difference between the transmit weight calculation from the channel information at a transmitter and the actual transmission is large, E-SDM...
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