Software defined radios are increasingly used in modern communication systems, especially in cognitive radio. Since this technology has been commercially available, more and more practical deployments are emerging and its challenges and realistic limitations are being revealed. One of the main problems is the RF performance of the front-end over a wide bandwidth. This paper presents an analysis...

This paper describes a system architecture along with signal processing technique which allows a reduction in the complexity of a 3.1–10.6 GHz Ultra-Wideband radio. The proposed system transmits passband pulses using a pulser and antenna, and the receiver front-end down-converts the signal frequency by subsampling, thus, requiring substantially less hardware than a traditional narrowband approa...

In this paper, a robust adaptive MMSE Rake-equalizer receiver scheme is presented with channel estimation that has been transmitted in Direct Sequence-Ultra Wideband (DS-UWB) system. The DS-UWB has a fine path resolution by transmitting information with ultra short pulses. The Rake receiver is known as a technique that can effectively combine paths with different delays and obtain the path dive...

The problem of asynchronous direct-sequence code-division multiple-access (DS-CDMA) detection over the ultra-wideband (UWB) multipath channel is considered. A joint synchronization, channel-estimation, and multiuser detection scheme based on the adaptive linear minimum mean square error (LMMSE) receiver is presented and evaluated. Further, a novel nonrecursive least-squares algorithm capable of...

This article proposes a reconfigurable wideband transfer function design for quadrature Σ∆ A/D converters combined with digital post-compensation of frequency-selective mirror-frequency interference (MFI) induced by the inherent mismatches between the in-phase (I) and quadrature (Q) rails of the receiver. When receiving wideband waveforms, such as LTE signals, it is crucial for the compensation...

This paper proposes a new modulation for a Global Navigation Satellite System (GNSS) to efficiently utilize a given bandwidth. This modulation, referred to as Time-Multiplexed Multi-Carrier (TMMC), divides the available bandwidth into N sub-bands such that each sub-band resembles a Quadrature Phase Shift Keying (QPSK) modulation and at the same time allows the receiver to exploit the benefits o...

Future mobile terminals become multi-mode communication systems. In order to handle different standards, we propose to perform baseband processing in heterogeneous reconfigurable hardware. Not only the baseband processing but also error decoding differs for every communication system. We already proposed implementations of the baseband processing part of an OFDM receiver and a Wideband CDMA rec...

This paper outlines a technique which can use multiple transmit antennas to send more than one binary bit using the same number of transmit antennas over a single transmission. It uses Ultra Wideband orthogonal pulse position modulation to achieve this, with the receiver employing a Rake receiver and a Maximum Ratio Combiner optimal detector. This is done over a Space Time Spreading Time Hoppin...

Ultra Wideband (UWB) systems are receiving recently more attention due to its approval by FCC. The systems that have been already implemented are based in analog correlation. This thesis is part of an effort to implement a wholly digital Ultra Wideband receiver. Synchronization of a signal is a first step to perform the correct demodulation of the data contained in it. It is a problem whose com...