Hiromichi Tomeba

Joint Tomlinson-Harashima Precoding and Frequency-Domain Equalization for Broadband Single-Carrier Transmission

The performance of single-carrier (SC) transmission in a frequency-selective fading channel degrades due to a severe inter-symbol interference (ISI). Using frequency-domain equalization (FDE) based on the minimum mean square error (MMSE) criterion can improve the bit error rate (BER) performance of SC transmission. However, the residual ISI after FDE limits the performance improvement. In this paper, we propose a joint use of Tomlinson-Harashima precoding (THP) and FDE to remove the residual ISI. An approximate conditional BER analysis is presented for the given channel condition. The achievable average BER performance is evaluated by Monte-Carlo numerical computation method using the derived conditional BER. The BER analysis is confirmed by computer simulation of the signal transmission.

Frequency-Domain Space-Time Block Coded-Joint Transmit/Receive Diversity for Direct-Sequence Spread Spectrum Signal Transmission

SUMMARY Recently, we proposed space-time block coded-joint transmit/receive antenna diversity (STBC-JTRD) for narrow band transmission in a frequency-nonselective fading channel; it allows an arbitrary number of transmit antennas while limiting the number of receive antennas to 4. In this paper, we extend STBC-JTRD to the case of frequency-selective fading channels and propose frequency-domain STBC-JTRD for broadband direct sequence-spread spectrum (DSSS) signal transmission. A conditional bit error rate (BER) analysis is presented. The average BER performance in a frequency-selective Rayleigh fading is evaluated by MonteCarlo numerical computation method using the derived conditional BER and is confirmed by computer simulation of the signal transmission. Performance comparison between frequency-domain STBC-JTRD transmission and joint space-time transmit diversity (STTD) and frequency-domain equalization (FDE) reception is also presented.

Space-Time Block Coded Joint Transmit/Receive Diversity in a Frequency-Nonselective Rayleigh Fading Channel

Antenna diversity is an effective technique for improving the transmission performance in a multi-path fading channel. Recently, transmit diversity has been attracting much attention since it can alleviate the complexity problem of the mobile terminals. Joint transmit diversity/receive diversity achieves a much improved transmission performance. In this paper, we propose a new space-time block coding algorithm for joint transmit/receive diversity, which requires the channel state information (CSI) only at the transmitter side. Unlike the conventional space-time transmit diversity (STTD), the space-time block coded joint transmit/receive diversity (STBC-JTRD) can use arbitrary number of transmit ; antennas, while the number of receive antennas is limited to 4. STBC-JTRD achieves a larger diversity gain than joint STTD/receive antenna diversity. The bit error rate (BER) analysis in a frequency-nonselective Rayleigh fading channel is presented. The BER performance is evaluated and is confirmed by the computer simulation.

Iterative Overlap FDE for DS-CDMA without GI

Frequency-domain equalization (FDE) based on minimum mean square error (MMSE) criterion can replace the conventional rake combining with significantly improved bit error rate (BER) performance for the downlink DS-CDMA in a frequency-selective fading channel. Recently, a new MMSE-FDE technique that requires no GI insertion has been proposed to avoid inter-block interference (IBI) (this technique is called overlap FDE). However, the residual IBI is produced and degrades the BER performance. Furthermore, the presence of an inter-chip interference (ICI) after MMSE-FDE limits the BER performance improvement. In this paper, we propose an iterative overlap FDE for DS-CDMA downlink to suppress both IBI and ICI. In the iterative overlap FDE, joint MMSE-FDE and ICI cancellation is repeated a sufficient number of times and the middle part of M chips is picked up. The BER performance with the iterative overlap FDE is evaluated by computer simulation.

Space-Time Block Coded-Joint Transmit/Receive Antenna Diversity using more than 4 Receive Antennas

Antenna diversity is an effective technique for improving the transmission performance in a multi-path fading channel. Recently, we proposed the space-time block coded-joint transmit/receive antenna diversity (STBC-JTRD), which allows the use of an arbitrary number of transmit antennas without sacrificing the coding rate. However, in STBC-JTRD, the number of receive antennas is limited to 4. In this paper, we show the STBC-JTRD encoding allowing the use of more than 5 receive antennas. The bit error rate (BER) analysis in a frequency-nonselective Rayleigh fading channel is presented. The BER performance analysis is confirmed by computer simulation.

BER Performance Analysis of MC-CDMA with Overlap-FDE

Recently, multi-carrier code division multiple access (MC-CDMA) has been attracting much attention as a broadband wireless access technique for the next generation mobile communication systems. Frequency-domain equalization (FDE) based on the minimum mean square error (MMSE) criterion can take advantage of the channel frequency-selectivity and improve the average bit error rate (BER) performance due to frequency-diversity gain. The conventional FDE requires the insertion of the guard interval (GI) to avoid the inter-block interference (IBI), resulting in the transmission efficiency loss. In this paper, an overlap FDE technique, which requires no GI insertion, is presented for MC-CDMA transmission. An expression for the conditional BER is derived for the given set of channel gains. The average BER performance in a frequency-selective Rayleigh fading channel is evaluated by Monte-Carlo numerical computation method using the derived conditional BER and is confirmed by computer simulation of the signal transmission.

Frequency-domain pre-equalization for multicode direct sequence spread spectrum signal transmission

Severe frequency-selective fading, encountered in a broadband wireless mobile communication, significantly degrades the bit error rate (BER) performance of direct sequence spread spectrum (DSSS) signal transmission with rake combining. In this paper, frequency-domain pre-equalization transmission, called pre-FDE transmission, is presented for orthogonal multicode DSSS signal transmission. It is confirmed by the computer simulation that pre-FDE transmission can achieve a BER performance almost identical to that attainable by FDE reception.

Frequency-domain Space-Time Block Coded-Joint Transmit/Receive Diversity for The Single Carrier Transmission

Recently, frequency-domain pre-equalization (pre-FDE) transmission has been attracting attention for improving the broadband DS-CDMA (or single carrier (SC)) transmission performance in a frequency-selective fading channel. To further improve the transmission performance, antenna diversity technique is very effective. However, so far the joint use of pre-FDE and the receive diversity has not been fully discussed. Recently, we proposed the space-time block coded-joint transmit/receive diversity (STBC-JTRD) for the narrowband transmission in a frequency-nonselective fading channel. STBC-JTRD allows an arbitrary number of transmit antennas while limiting the number of receive antennas to 4. In this paper, we extend the STBC-JTRD to the case of frequency-selective fading channel and propose the frequency-domain STBC-JTRD for the SC transmission in a frequency-selective fading channel. The average bit error rate (BER) performance of the SC transmission with frequency-domain STBC-JTRD is evaluated by the computer simulation

BER Performance of Joint THP/pre-FDE

Recently, frequency-domain equalization (FDE) based on the minimum mean square error (MMSE) criterion has been attracting much attention to overcome the frequency-selective fading channel. The bit error rate (BER) performance of single- carrier (SC) transmission is significantly improved by using MMSE-FDE by obtaining the frequency-diversity gain while suppressing the inter-symbol interference (ISI). However, the residual ISI after MMSE-FDE limits the performance improvement. Recently, we have proposed a joint use of Tomlinson-Harashima precoding (THP) and FDE reception (joint THP/FDE) to suppress the residual ISI. However, joint THP/FDE requires the channel state information (CSI) at both the transmitter and receiver. In this paper, we replace FDE reception by pre-FDE and propose joint THP/pre-FDE that requires the CSI at the transmitter only, while providing almost the same BER performance as joint THP/FDE.

Frequency-domain equalisation for block CDMA transmission†

Frequency-domain equalization (FDE) technique may play an important role for broadband packet transmission using MC- and DS-CDMA. The downlink performance is significantly improved with FDE; however, the uplink performance is limited by the multi-access interference (MAI). To remove the MAI while gaining the frequency diversity effect through the use of FDE, frequency-domain block spread CDMA can be used. The performance can be further improved by the use of multi-input/multi-output (MIMO) antenna technique. Recently, particular attention has been paid to MIMO space division multiplexing (SDM) to significantly increase the throughput without expanding the signal bandwidth. In this paper, we present a comprehensive performance comparison of MC- and DS-CDMA using FDE.