Siavash M. Alamouti

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This paper presents a simple two-branch transmit diversity scheme. Using two transmit antennas and one receive antenna the scheme provides the same diversity order as maximal-ratio receiver combining (MRRC) with one transmit antenna, and two receive antennas. It is also shown that the scheme may easily be generalized to two transmit antennas and M receive(More)
Motivation Life without modern wireless communications, as it existed before 1990, is now difficult to imagine. It empowers our modern life, enables modern societies to operate efficiently, and has had a major impact on modern politics, economy, education, health, entertainment, logistics, travel, and all industries. In order to have a productive life, we(More)
An adaptive scheme for trellis-coded modulation of MPSK signals called adaptive trellis-coded multiple-phase-shift-keying (ATCMPSK) is proposed for slowly Rayleigh fading channels. The adaptive scheme employs a slightly modified rate 112 convolutional encoder and the corresponding Viterbi decoder to realize a family of codes of different rates which are(More)
Smart antenna technology can greatly improve the coverage radius of wireless systems by focusing the transmitted signal (beam) toward desired users. However, beamforming has an important side effect as it creates a region, herein referred to as the complementary region, where some users in the network cannot sense the directional signals (beams). We have(More)
This paper presents a simple two-branch transmit diversity scheme. Using two transmit antennas and one receive antenna the scheme provides the same diversity order as maximal-ratio receiver combining (MRRC) with one transmit antenna, and two receive antennas. It is also shown that the scheme may easily be generalized to two transmit antennas and M receive(More)
This paper derives a maximum likelihood Doppler frequency estimator for orthogonal frequency division multiplexing (OFDM) systems in time-varying multipath channels. The proposed scheme is a frequency-domain approach that utilizes pilot subcarriers, which are commonly implemented in most practical systems. Time-varying fading causes intercarrier(More)
Multiple antenna systems can greatly improve the performance of wireless systems by providing better link quality, capacity and immunity to interference. A very simple structure for smart antennas is a fixed beamforming network (FBN) with beam selection. In [1] the performance of antenna and beam selection/combining techniques are compared. The channel(More)
In the last decade, we have witnessed revitalization of multi-carrier techniques, and in particular orthogonal frequency division multiplexing (OFDM) for wireless applications. For wireless applications, an OFDM air-interface is of interest, because it can turn a wideband frequency selective channel into narrowband frequency flat channels. This makes the(More)
This paper describes an implementation of the forward link physical layer of the wideband DS-CDMA as described in the preliminary ETSI W-CDMA specification for UMTS [1]. The channel definitions, the frame structure, and the transmission formats for the forward link channels are presented, and the implementation in SPW is described in detail. The description(More)
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