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This paper addresses signal compactness issues in MC-CDMA employing carrier interferometry codes using the measure of crest factor (CF). Carrier interferometry codes, applied to -carrier MC-CDMA systems, enable users to simultaneously share the system bandwidth with minimal degradation in performance (relative to the -orthogonal-user case). First, for a fully loaded ( and users)...
We study the uplink performance of MIMO systems in UTRA FDD using noise rise and system load as performance measures. Results show that the uplink coverage and capacity of the UTRA FDD mode are significantly improved by SIMO and MIMO techniques that require only minor modifications to existing 3GPP specifications. Receive diversity in base station increases coverage and capacity in a straightforward...
The capacity of a cellular multiuser MIMO system depends on various parameters, for example, the system structure, the transmit and receive strategies, the channel state information at the transmitter and the receiver, and the channel properties. Recently, the main focus of research was on single-user MIMO systems, their channel capacity, and their error performance with space-time coding. In general,...
The ability to predict transmission loss or field strength distribution is crucial for determining coverage in planning personal communication systems. This paper presents a practical method to accurately predict entire average transmission loss distribution in complicated urban environments. The method uses a 3D propagation model based on radiosity and a simplified city information database including...
Most of the performance studies devoted to the analysis of multicarrier systems in the presence of nonlinear distortion assume that the multicarrier signal can be modeled as a random Gaussian process regardless of modulation format, guard interval duration, and number of subcarriers. On the contrary, we present an analysis based on the discrete model of the multicarrier signal. It is shown that the...
In the downlink of a multiuser multiple-input multiple-output (MIMO) communication system, simultaneous transmission to several users requires joint optimization of the transmitted signals. Allowing all users to have multiple antennas adds an additional degree of complexity to the problem. In this paper, we examine the case where a single base station transmits to multiple users using linear processing...
In contrast to dirty-paper coding (DPC) which is largely information theoretic, this paper proposes a linear codec that can spatially multiplex the multiuser signals to realize the rich capacity of multiple-input multiple-output (MIMO) downlink broadcast (point-to-multipoint) channels when channel state information (CSI) is available at the transmitter. Assuming single-stream (or single-mode) communication...
Iterative multiuser detection in a single-carrier broadband multiple-input multiple-output (MIMO) system is studied in this paper. A minimum mean squared error (MMSE) low-complexity multiuser receiver is derived for space-division multiple-access (SDMA) space-time trellis-coded (STTrC) systems in frequency-selective fading channels. The receiver uses MMSE filtering to jointly detect several transmit...
This paper describes a multiuser scenario with several terminals acceding simultaneously to the same frequency channel. The objective is to design an optimal multiuser system that may be used as a comparative framework when evaluating other suboptimal solutions and to contribute to the already published works on this topic. The present work assumes that a centralized manager knows perfectly all the...
This paper examines the optimum design of FIR precoders or equalizers for multiple-input multiple-output (MIMO) frequency-selective wireless channels. For the case of a left-coprime FIR channel, which arises generically when the number of transmit antennas is larger than the number of receive antennas, the Bezout matrix identity can be employed to design an FIR MIMO precoder that equalizes...
Local multipoint distribution systems (LMDS), which are operating worldwide in the frequency range of 26 to 43 GHz, have large bandwidths of 0.1 up to 2 GHz but a limited area coverage of a few kilometers only. This is due to line-of-sight (LOS) constraints for reliable point-to-multipoint links as well as due to large propagation losses. The size of the macrocells illuminated by the base stations,...
A new blind channel estimation technique is proposed for space-time coded wideband CDMA systems using aperiodic and possibly multirate spreading codes. Using a decorrelating front end, the received signal is projected onto a subspace from which channel parameters can be estimated up to a rotational ambiguity. Exploiting the subspace structure of the WCDMA signaling and the orthogonality of the unitary...
We present a codeword adaptation algorithm for collaborative multibase wireless systems. The system is modeled with multiple inputs and multiple outputs (MIMO) in which information is transmitted using multicode CDMA, and codewords are adapted based on greedy maximization of the signal-to-interference-plus-noise ratio. The procedure monotonically increases the sum capacity and, when repeated iteratively...
We investigate the problem of scheduling for the uplink of a time-slotted multiuser multiple-input multiple-output (MIMO) system with sum capacity as the performance metric. We first consider scheduling users' transmissions for fixed transmit beamformers. Upper bounds for the sum capacity of the time-slotted system with the optimum scheduler are found via relaxing a set of structural constraints....
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