In this letter, the performance of frequency-hopping spread-spectrum systems employing noncoherent reception and transmission diversity is analyzed for frequency-selective Rayleigh fading channels. Two different types of transmission diversity systems, a fast frequency-hopping (FFH) system and a multicarrier frequency-hopping (MCFH) system, are investigated. In order to combine received signals...

In this paper, a pilot assisted minimum mean square error multiuser channel estimation algorithm is proposed for quasi-synchronous CDMA systems. The doubly selective multiuser fading channel is represented as a time-varying chip-spaced tapped delay line filter with correlated filter taps. The multiuser channel tap coefficients at pilot symbol positions are estimated under the MMSE criterion wit...

In a high mobility environment, single-carrier (SC) space-frequency block coding (STBC) diversity achieves better bit error rate (BER) performance than SC space-time block coding (STBC) diversity. However, in a strong frequency-selective fading channel, the BER performance degrades due to the orthogonality distortion of SFBC codeword. In this paper, we propose a frequency-domain equalization (c...

This paper proposes a space-time block-coded orthogonal frequency-division multiplexing (STBC-OFDM) scheme for frequency-selective fading channels which does not require channel knowledge either at the transmitter or at the receiver. This paper proposed a generalized maximum likelihood estimation decoding algorithm. Due to the orthogonality nature of STBC, the rule for decoding was reduced to a...

Most existing space-time (ST) coding schemes have been developed for fiat fading channels. To offer antenna diversity gains, they rely on channel state information (CSI) acquired at the receiver through training, or, via blind channel estimation. Differential ST modulation obviates the need for (7S1 but is less effective in rapidly fading environments. This paper develops novel ST coders and de...

In this paper, two different dynamic cell coordination stratagies for frequency selective and flat fading are proposed for efficient subcarrier allocation in the joint consideration of adaptive modulation and variable frequency reuse in the channel-aware OFDMA downlink multicellular environment. Compared to a conventional OFDMA system without cell coordination, where system throughput may becom...

Single-carrier (SC) transmission with space-time block coded (STBC) transmit diversity can achieve good bit error rate (BER) performance. However, in a high mobility environment, the STBC codeword orthogonality is distorted and as consequence, the BER performance is degraded by the interference caused by the orthogonality distortion of STBC codeword. In this paper, we proposed a novel frequency...

~ince the Co.de Division Multiple Access (CDMA) system was proposed for the next generation of mobile communications, several multiuser detection· methods have been develope? to cope with the Multi-Access Interference inherent in the CDMA system. Fading and. multIpath ch~acteristi~sof the mobile radio channel present significant challenges to the designer of multiuser receivers. The fading phen...

Adaptive prediction iterative channel estimation is presented for combined antenna diversity and coherent rake reception of direct sequence spread spectrum (DSSS) signals. Its first stage uses pilot-aided adaptive prediction channel estimation, while the succeeding iteration stages use decision feedback and moving average filtering for channel re-estimation. The bit error rate (BER) performance...

In a frequency-selective fading channel, the transmission performance of single-carrier (SC) transmission significantly degrades due to severe inter-symbol-interference (ISI). In this paper, the joint use of space-time transmit diversity (STTD), receive antenna diversity and frequency-domain minimum mean square error (MMSE) equalization in SC transmission is studied. Space-time encoding and dec...