EURASIP Journal on Wireless Communications and Networking

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

List of Papers (Total 2,868)

Intersymbol Decorrelating Detector for Asynchronous CDMA Networks with Multipath

Most reported multiuser detection techniques for CDMA systems need the channel estimation including the delay spread and the parameters of the multipath channel of the desired user. This paper proposes an intersymbol decorrelating detector that makes use of the cross-correlation matrix constructed by the consecutively received symbols. The proposed detector is attractive for its ...

Software-Defined Radio—Basics and Evolution to Cognitive Radio

We provide a brief overview over the development of software-defined or reconfigurable radio systems. The need for software-defined radios is underlined and the most important notions used for such reconfigurable transceivers are thoroughly defined. The role of standards in radio development is emphasized and the usage of transmission mode parameters in the construction of ...

Extended Lock Range Zero-Crossing Digital Phase-Locked Loop with Time Delay

The input frequency limit of the conventional zero-crossing digital phase-locked loop (ZCDPLL) is due to the operating time of the digital circuitry inside the feedback loop. A solution that has been previously suggested is the introduction of a time delay in the feedback path of the loop to allow the digital circuits to complete their sample processing before the next sample is ...

Adaptive Transmitter Optimization in Multiuser Multiantenna Systems: Theoretical Limits, Effect of Delays, and Performance Enhancements

The advances in programmable and reconfigurable radios have rendered feasible transmitter optimization schemes that can greatly improve the performance of multiple-antenna multiuser systems. Reconfigurable radio platforms are particularly suitable for implementation of transmitter optimization at the base station. We consider the downlink of a wireless system with multiple transmit ...

Towards a Fraud-Prevention Framework for Software Defined Radio Mobile Devices

The superior reconfigurability of software defined radio mobile devices has made it the most promising technology on the wireless network and in the communication industry. Despite several advantages, there are still a lot to discuss regarding security, for instance, the radio configuration data download, storage and installation, user's privacy, and cloning. The objective of this ...

Supporting QoS in MANET by a Fuzzy Priority Scheduler and Performance Analysis with Multicast Routing Protocols

Mobile ad hoc network is an autonomous system of mobile nodes characterized by wireless links. The major challenge in ad hoc networks lies in adapting multicast communication to environments, where mobility is unlimited and failures are frequent. Such problems increase the delays and decrease the throughput. To meet these challenges, to provide QoS, and hence to improve the ...

Flexible Radio: A Framework for Optimized Multimodal Operation via Dynamic Signal Design

The increasing need for multimodal terminals that adjust their configuration on the fly in order to meet the required quality of service (QoS), under various channel/system scenarios, creates the need for flexible architectures that are capable of performing such actions. The paper focuses on the concept of flexible/reconfigurable radio systems and especially on the elements of ...

Multimode Communication Protocols Enabling Reconfigurable Radios

This paper focuses on the realization and application of a generic protocol stack for reconfigurable wireless communication systems. This focus extends the field of software-defined radios which usually concentrates on the physical layer. The generic protocol stack comprises common protocol functionality and behavior which are extended through specific parts of the targeted radio ...

A Reconfigurable Spiral Antenna for Adaptive MIMO Systems

We present a reconfigurable spiral antenna for use in adaptive MIMO systems. The antenna is capable of changing the sense of polarization of the radiated field. It is fabricated by using an RF-MEMS technology compatible with microwave laminate substrates developed within the author's group. The proposed antenna structure is built on a number of rectangular-shaped bent metallic ...

Adaptive Mobile Positioning in WCDMA Networks

We propose a new technique for mobile tracking in wideband code-division multiple-access (WCDMA) systems employing multiple receive antennas. To achieve a high estimation accuracy, the algorithm utilizes the time difference of arrival (TDOA) measurements in the forward link pilot channel, the angle of arrival (AOA) measurements in the reverse-link pilot channel, as well as the ...

New PN Even Balanced Sequences for Spread-Spectrum Systems

A new class of pseudonoise even balanced (PN-EB) binary spreading sequences is derived from existing classical odd-length families of maximum-length sequences, such as those proposed by Gold, by appending or inserting one extra-zero element (chip) to the original sequences. The incentive to generate large families of PN-EB spreading sequences is motivated by analyzing the spreading ...

Modular Software-Defined Radio

In view of the technical and commercial boundary conditions for software-defined radio (SDR), it is suggestive to reconsider the concept anew from an unconventional point of view. The organizational principles of signal processing (rather than the signal processing algorithms themselves) are the main focus of this work on modular software-defined radio. Modularity and flexibility ...

A Low-Complexity Approach to Space-Time Coding for Multipath Fading Channels

We consider a single-carrier multiple-input single-output (MISO) wireless system where the transmitter is equipped with multiple antennas and the receiver has a single antenna. For this setting, we propose a space-time coding scheme based on the concatenation of trellis-coded modulation (TCM) with time-reversal orthogonal space-time block coding (TR-STBC). The decoder is based on ...

Flexible Analog Front Ends of Reconfigurable Radios Based on Sampling and Reconstruction with Internal Filtering

Bandpass sampling, reconstruction, and antialiasing filtering in analog front ends potentially provide the best performance of software defined radios. However, conventional techniques used for these procedures limit reconfigurability and adaptivity of the radios, complicate integrated circuit implementation, and preclude achieving potential performance. Novel sampling and ...

Reconfigurable Signal Processing and Hardware Architecture for Broadband Wireless Communications

This paper proposes a broadband wireless transceiver which can be reconfigured to any type of cyclic-prefix (CP) -based communication systems, including orthogonal frequency-division multiplexing (OFDM), single-carrier cyclic-prefix (SCCP) system, multicarrier (MC) code-division multiple access (MC-CDMA), MC direct-sequence CDMA (MC-DS-CDMA), CP-based CDMA (CP-CDMA), and CP-based ...

Flexible Frequency Discrimination Subsystems for Reconfigurable Radio Front Ends

The required flexibility of the software-defined radio front end may currently be met with better overall performance by employing tunable narrowband circuits rather than pursuing a truly wideband approach. A key component of narrowband transceivers is appropriate filtering to reduce spurious spectral content in the transmitter and limit out-of-band interference in the receiver. In ...

Bit Error Rate Performance Analysis of a Threshold-Based Generalized Selection Combining Scheme in Nakagami Fading Channels

The severity of fading on mobile communication channels calls for the combining of multiple diversity sources to achieve acceptable error rate performance. Traditional approaches perform the combining of the different diversity sources using either the conventional selective diversity combining (CSC), equal-gain combining (EGC), or maximal-ratio combining (MRC) schemes. CSC and MRC ...

A Low-Complexity KL Expansion-Based Channel Estimator for OFDM Systems

This paper first proposes a computationally efficient, pilot-aided linear minimum mean square error (MMSE) batch channel estimation algorithm for OFDM systems in unknown wireless fading channels. The proposed approach employs a convenient representation of the discrete multipath fading channel based on the Karhunen-Loeve (KL) orthogonal expansion and finds MMSE estimates of the ...

Adaptive Iterative Soft-Input Soft-Output Parallel Decision-Feedback Detectors for Asynchronous Coded DS-CDMA Systems

The optimum and many suboptimum iterative soft-input soft-output (SISO) multiuser detectors require a priori information about the multiuser system, such as the users' transmitted signature waveforms, relative delays, as well as the channel impulse response. In this paper, we employ adaptive algorithms in the SISO multiuser detector in order to avoid the need for this a priori ...

Adaptive Space-Time-Spreading-Assisted Wideband CDMA Systems Communicating over Dispersive Nakagami- Fading Channels

In this contribution, the performance of wideband code-division multiple-access (W-CDMA) systems using space-time-spreading- (STS-) based transmit diversity is investigated, when frequency-selective Nakagami- fading channels, multiuser interference, and background noise are considered. The analysis and numerical results suggest that the achievable diversity order is the product of ...

Blind Decoding of Multiple Description Codes over OFDM Systems via Sequential Monte Carlo

We consider the problem of transmitting a continuous source through an OFDM system. Multiple description scalar quantization (MDSQ) is applied to the source signal, resulting in two correlated source descriptions. The two descriptions are then OFDM modulated and transmitted through two parallel frequency-selective fading channels. At the receiver, a blind turbo receiver is ...

Blind Multiuser Detection for Long-Code CDMA Systems with Transmission-Induced Cyclostationarity

We consider blind channel identification and signal separation in long-code CDMA systems. First, by modeling the received signals as cyclostationary processes with modulation-induced cyclostationarity, long-code CDMA system is characterized using a time-invariant system model. Secondly, based on the time-invariant model, multistep linear prediction method is used to reduce the ...

Soft-In Soft-Output Detection in the Presence of Parametric Uncertainty via the Bayesian EM Algorithm

We investigate the application of the Bayesian expectation-maximization (BEM) technique to the design of soft-in soft-out (SISO) detection algorithms for wireless communication systems operating over channels affected by parametric uncertainty. First, the BEM algorithm is described in detail and its relationship with the well-known expectation-maximization (EM) technique is ...

Estimation of Directions of Arrival by Matching Pursuit (EDAMP)

We propose a novel system architecture that employs a matching pursuit-based basis selection algorithm for directions of arrival estimation. The proposed system does not require a priori knowledge of the number of angles to be resolved and uses very small number of snapshots for convergence. The performance of the algorithm is not affected by correlation in the input signals. The ...

Opportunistic Carrier Sensing for Energy-Efficient Information Retrieval in Sensor Networks

We consider distributed information retrieval for sensor networks with cluster heads or mobile access points. The performance metric used in the design is energy efficiency defined as the ratio of the average number of bits reliably retrieved by the access point to the total amount of energy consumed. A distributed opportunistic transmission protocol is proposed using a combination ...