Bandwidth (signal processing)

About: Bandwidth (signal processing) is a research topic. Over the lifetime, 48550 publications have been published within this topic receiving 600741 citations. The topic is also known as: Bandwidth (signal processing) & bandwidth.

A 700-kHz bandwidth /spl Sigma//spl Delta/ fractional synthesizer with spurs compensation and linearization techniques for WCDMA applications

Abstract: A /spl Sigma//spl Delta/ fractional-N frequency synthesizer targeting WCDMA receiver specifications is presented. Through spurs compensation and linearization techniques, the PLL bandwidth is significantly extended with only a slight increase in the integrated phase noise. In a 0.18-/spl mu/m standard digital CMOS technology a fully integrated prototype with 2.1-GHz output frequency and 35 Hz resolution has an area of 3.4 mm/sup 2/ PADs included, and it consumes 28 mW. With a 3-dB closed-loop bandwidth of 700 kHz, the settling time is only 7 /spl mu/s. The integrated phase noise plus spurs is -45 dBc for the first WCDMA channel (1 kHz to 1.94 MHz) and -65 dBc for the second channel (2.5 to 6.34 MHz) with a worst case in-band (unfiltered) fractional spur of -60 dBc. Given the extremely large bandwidth, the synthesizer could be used also for TX direct modulation over a broad band. The choice of such a large bandwidth, however, still limits the spur performance. A slightly smaller bandwidth would fulfill WCDMA requirements. This has been shown in a second prototype, using the same architecture but employing an external loop filter and VCO for greater flexibility and ease of testing.

A new method for varying adaptive bandwidth selection

Abstract: A novel approach is developed to solve a problem of varying bandwidth selection for filtering a signal given with an additive noise. The approach is based on the intersection of confidence intervals (ICI) rule and gives the algorithm, which is simple to implement and adaptive to unknown smoothness of the signal.

Optimum Combining for Indoor Radio Systems with Multiple Users

Abstract: This paper studies the use of optimum combining to increase the capacity of narrow-band in-building radio communication systems with multiple users. We consider systems consisting of a base Station with numerous remotes in a Rayleigh fading environment and study the problem of more users requiring channels than the number of channels available. A system is described that, with multiple antennas at the base station but only one antenna at each remote, uses optimum combining to suppress interfering signals. We show that this system, with M antennas at the base station, can achieve an M -fold increase in the number of users or tolerate M - 1 interferers from other systems. Thus, with optimum combining, radio communications can be used in high-density, multiple-user environments, such as within buildings, even when only limited bandwidth is available.

Cooperative Intelligent Transport Systems: 5.9-GHz Field Trials

Abstract: The mobile outdoor radio environment is challenging for vehicular communications. Although multipath propagation offers diversity and benefits in non-line-of-sight (NLOS) conditions, simultaneous multipath and mobility results in a doubly-selective fading channel. In practice, this means that the channel parameters vary significantly in both time and frequency within the bandwidth and typical packet durations used in 802.11p/WAVE standards for short-range vehicular communications. This paper presents the results of extensive field trial campaigns conducted in several countries, totaling over 1100 km. These field trials are scenario based, focusing on challenging low-latency, high-reliability vehicle-to-vehicle (V2V) safety applications including intersection collision warning, turn across path, emergency electronic brake light, do not pass warning, and precrash sensing. Vehicle-to-infrastructure (V2I) applications are also considered. The field trials compared the performance of off-the-shelf WiFi-based radio equipment with a more advanced 802.11p compliant radio employing more sophisticated channel estimation and tracking. Field trial results demonstrate significantly improved performance using the advanced radio, translating into greatly increased driver warning times and stopping distances. In fact the results show that off-the-shelf WiFi equipment fails to provide sufficient stopping distance to avert accidents in some cases. During the field trials, channel sounding data were also captured. Analysis of these channel measurements reveals the critical importance of accurate channel estimation, tracking the channel in both time and frequency within each packet. Delay spread and Doppler spread statistics computed from the channel measurements validate previously reported results in the literature. The results in this paper, however, provide the first instance of channel measurements performed simultaneously to application performance evaluation. The objective is to firmly establish the link between radio channel characteristics and the performance of critical V2V safety applications.

Application of Electromagnetic Bandgaps to the Design of Ultra-Wide Bandpass Filters With Good Out-of-Band Performance

Abstract: In this study, a new technique for the design of ultra-wide bandpass filters with spurious suppression over a very wide band is presented. The method consists on the combination of a well-known analytical design approach to achieve wide bandwidths with an electromagnetic bandgap structure, which is fundamental for spurious suppression. To illustrate the technique, a microstrip of ultra-wide bandpass filter centered at 3.4 GHz with a bandwidth covering 4.8 GHz is implemented in an Arlon substrate (permittivity epsivr=2.4, thickness h=0.675 mm). Measured filter characteristics are good with in-band insertion losses below 0.90 dB and return losses better than 10 dB. Out-of-band performance is also good with spurious passband attenuation higher than 30 dB up to at least 20 GHz