EURASIP Journal on Wireless Communications and Networking

http://link.springer.com/journal/13638

List of Papers (Total 2,828)

Downlink Space-Frequency Preequalization Techniques for TDD MC-CDMA Mobile Radio Systems

The paper considers downlink space-frequency preequalizations techniques for time division duplex (TDD) MC-CDMA. We consider the use of antenna arrays at the base station (BS) and analytically derive different preequalization schemes for two different receiver configurations at the mobile terminal: a simple despread receiver without channel equalization and an equal-gain combiner ...

Performance Evaluation of Public Key-Based Authentication in Future Mobile Communication Systems

While mobile hosts are evolving into full-IP enabled devices, there is a greater demand to provide a more flexible, reconfigurable, and scalable security mechanism in mobile communication systems beyond 3G (B3G). Work has already begun on such an "all-IP" end-to-end solution, commonly referred to as 4G systems. Fully fledged integration between heterogeneous networks, such as 2.5G, ...

Spreading Sequence Design and Theoretical Limits for Quasisynchronous CDMA Systems

For various quasisynchronous (QS) CDMA systems such as LAS-CDMA system which emerged recently, in order to reduce or eliminate the multiple access interference and multipath interference, it is required to design a set of spreading sequences which are mutually orthogonal within a designed shift zone, called orthogonal zone. For traditional orthogonal sequences, such as Walsh ...

Joint Performance Study of Channel Estimation and Multiuser Detection for Uplink Long-Code CDMA Systems

Although numerous channel estimation and multiuser detection approaches have appeared for long-code uplink CDMA systems, joint performance study of channel estimators and symbol detectors remains largely open. In this paper, we construct three typical symbol-level linear receivers upon existing channel estimation method, known as zero-forcing (ZF), minimum mean-square-error (MMSE), ...

A Low-Complexity Blind Multiuser Receiver for Long-Code CDMA

Receivers for long-code systems are for computational reasons usually based on simple matched-filter techniques, and hence suffer from multiaccess interference. Decorrelating RAKE and MMSE receivers do not have this problem but have not been widely studied due to the apparent complexity of the inversion of a large code matrix. Tong, van der Veen Dewilde, and Sung (IEEE Tr. Signal ...

Multilevel LDPC Codes Design for Multimedia Communication CDMA System

We design multilevel coding (MLC) with a semi-bit interleaved coded modulation (BICM) scheme based on low density parity check (LDPC) codes. Different from the traditional designs, we joined the MLC and BICM together by using the Gray mapping, which is suitable to transmit the data over several equivalent channels with different code rates. To perform well at signal-to-noise ratio ...

Two-Stage Maximum Likelihood Estimation (TSMLE) for MT-CDMA Signals in the Indoor Environment

This paper proposes a two-stage maximum likelihood estimation (TSMLE) technique suited for multitone code division multiple access (MT-CDMA) system. Here, an analytical framework is presented in the indoor environment for determining the average bit error rate (BER) of the system, over Rayleigh and Ricean fading channels. The analytical model is derived for quadrature phase shift ...

Single Carrier Cyclic Prefix-Assisted CDMA System with Frequency Domain Equalization for High Data Rate Transmission

Multiple-access interference and interfinger interference limit the capacity of conventional single-carrier DS-CDMA systems. Even though multicarrier CDMA posses the advantages of conventional CDMA and OFDM, it suffers from two major implementation difficulties such as peak-to-average power ratio and high sensitivity to frequency offset and RF phase noise. A novel approach based on ...

Overloaded CDMA Systems with Displaced Binary Signatures

We extend three types of overloaded CDMA systems, by displacing in time the binary signature sequences of these systems: (1) random spreading (PN), (2) multiple-OCDMA (MO), and (3) PN/OCDMA (PN/O). For each of these systems, we determine the time shifts that minimize the overall multiuser interference power. The achievable channel load with coded and uncoded data is evaluated for ...

Successive Interference Cancellation for DS-CDMA Systems with Transmit Diversity

We introduce a new successive interference cancellation (SIC) technique for direct sequence code division multiple access (DS-CDMA) systems with transmit diversity. The transmit diversity is achieved with a space-time block code (STBC). In our work we first consider hard decision SIC with an STBC, and then investigate the performance of soft decision SIC with an STBC. System ...

Delay Estimation in Long-Code Asynchronous DS/CDMA Systems Using Multiple Antennas

The problem of propagation delay estimation in asynchronous long-code DS-CDMA multiuser systems is addressed. Almost all the methods proposed so far in the literature for propagation delay estimation are derived for short codes and the knowledge of the codes is exploited by the estimators. In long-code CDMA, the spreading code is aperiodic and the methods developed for short codes ...

Design of Long Period Pseudo-Random Sequences from the Addition of -Sequences over

Pseudo-random sequence with good correlation property and large linear span is widely used in code division multiple access (CDMA) communication systems and cryptology for reliable and secure information transmission. In this paper, sequences with long period, large complexity, balance statistics, and low cross-correlation property are constructed from the addition of -sequences ...

An Approach to Optimum Joint Beamforming Design in a MIMO-OFDM Multiuser System

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 ...

Blind Channel Estimation for Space-Time Coded WCDMA

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 ...

A Practical Radiosity Method for Predicting Transmission Loss in Urban Environments

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 ...

Cochannel Interference Mitigation and Cooperative Processing in Downlink Multicell Multiuser MIMO Networks

Recently, the remarkable capacity potential of multiple-input multiple-output (MIMO) wireless communication systems was unveiled. The predicted enormous capacity gain of MIMO is nonetheless significantly limited by cochannel interference (CCI) in realistic cellular environments. The previously proposed advanced receiver technique improves the system performance at the cost of ...

Design of FIR Precoders and Equalizers for Broadband MIMO Wireless Channels with Power Constraints

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 ...

Iterative MIMO Turbo Multiuser Detection and Equalization for STTrC-Coded Systems with Unknown Interference

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 ...

Improving Capacity in LMDS Networks Using Trellis-Coded Modulation

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 ...

Performance Analysis of Capacity of MIMO Systems under Multiuser Interference Based on Worst-Case Noise Behavior

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 ...

Time-Slotted Multiuser MIMO Systems: Beamforming and Scheduling Strategies

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 ...

Performance Analysis of Multicarrier Systems in the Presence of Smooth Nonlinearity

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 ...

Analysis of Multiuser MIMO Downlink Networks Using Linear Transmitter and Receivers

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 ...

Greedy SINR Maximization in Collaborative Multibase Wireless Systems

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, ...

Robust Downlink Power Control in Wireless Cellular Systems

A serious shortcoming of current downlink power control methods is that their performance may be severely degraded when the downlink channel information is known imprecisely at the transmitter. In this paper, a computationally and implementationally simple centralized downlink power control method is proposed for cellular wireless communication systems using code division multiple ...