Showing papers by "Hiroshi Harada published in 2006"

A Carrier Interferometry based Channel Estimation Technique for One-Cell Reuse MIMO-OFDM/TDMA Cellular Systems

Abstract: This paper propose a channel estimation technique for multiple-input multiple-output (MIMO) - orthogonal frequency division multiplexing (OFDM) / time division multiple access (TDMA) (MIMO-OFDM/TDMA) cellular systems based on the dynamic parameter controlled -OF/TDMA (DPC-OF/TDMA) systems. In the proposed scheme, impulse responses of all the transmit antennas are multiplexed in the time domain using a carrier interferometry (CI) signal, which is equivalent to an impulse signal, and each impulse response is discriminated using a time window with the length of the maximum delay time of delayed paths, in order to estimate a channel state information (CSI) using only 64 subcarriers. Computer simulation confirms that the proposed channel estimation scheme is effective even in the case of 64 subcarriers under MIMO and multi-cell conditions.

Multiple-QR-Decomposition Assisted Group Detection for Reduced-Complexity-and-Latency MIMO-OFDM Receivers

Abstract: We propose a new multiple-QR-decomposition assisted group detection (Multi-QRD-GD) algorithm for the development of reduced-complexity-and-latency multi-input multi-output (MIMO) orthogonal frequency division multiplexing (OFDM) receivers. In addition, we investigate an effect of adaptive grouping (AG) based on received signal-to-noise power ratio for Multi-QRD-GD. In this paper, we describe the functions of the Multi-QRD-GD algorithm and AG scheme. Then, we compare bit error rate (BER) performances of the proposed Multi-QRD-GD and conventional detection algorithms by computer simulations. In addition, we compare the computational complexities of the algorithms.

Implementation of Multi-channel Modern and Multi-channel Radio Broadcast Receiver on Reconfigurable Packet Routing-oriented Signal Processing Platform (RPPP)

Abstract: A new architecture for a signal processing platform suited for flexible software defined radio called RPPP has been proposed by the authors. In this architecture, the platform can change its functionality clock by clock and multiple function radio equipment is realized flexibility. This paper describes two implementations of SDR using RPPP. One is the receiver for DSRC which can handle two different standards of DSRC. The other is a multi-channel FM broadcast receiver. Through the implementation, efficiency of logic usage and the performance of the radio equipment are evaluated.

A Hybrid Detection Algorithm for MIMO Systems

Abstract: In this contribution, a hybrid detection algorithm based on QR decomposition for MIMO systems is proposed to reduce the complexity of the MIMO detection algorithm. The proposed algorithm combines vector searching with DF (Decision Feedback) technique to improve the reliability of the detected signals and meanwhile holds a low computational complexity. The computational complexity and BER performance can be controlled through setting different values to the parameters in the algorithm to satisfy complexity and performance requirements. In this paper, the performance and the complexity are analyzed in MIMO system with different modulation scheme.

Signal decoding apparatus, signal decoding method, program, and information record medium

Abstract: Signal decoding apparatus, signal decoding method, program, and information record medium are provided and can accomplish not only high-speed and high-capacity communication, but high-accuracy decoding. An initial channel estimation section 31 estimates an initial channel with a pilot symbol added at the beginning of each packet. After a replica of a transmission symbol is generated, for a reception signal vector, CCI components for L transmission antennas are generated. A CCI canceller 33 removes the CCI components from the reception signal vector. After the reception symbol vector from which the CCI components had been removed has been obtained, a division device 34 obtains an instantaneous estimation value. An update condition determination section 35 detects deterioration of a channel response accuracy based on a threshold value. An instantaneous estimation value whose SNR has been determined to be insufficient is discarded. An averaging circuit 36 outputs a channel response estimation matrix at time t+1 obtained by an averaging process and supplies the matrix to a symbol decoding section 13.

A Crosslayer Design with power control and AMC for Sub-band Based OFDM System

Abstract: This contribution focuses on the optimization of the parameters for the services in a sub-band based OFDM system using AMC and power control at the physical layer and having a finite-length queue at the data link layer. Since the length of the queue at the data link is not infinite, the packets are possible to be dropped before their transmission at the physical layer, and on the contrary, there may be inadequate packets in the queue for the physical layer to transmit. The dropping rate and the error rate will jointly affect the packet loss rate. It is necessary to consider the parameters in the physical layer and high layers to minimize the packet loss rate of the wireless systems, which will lead to an improved spectral efficiency and high data rate. Numerical results are presented to show the relationships between the performances and various parameters.