The impact of non-ideal delay line (DL) along with group delay ripple (GDR) on the performance of ultra wide bandwidth (UWB) system has not yet been studied in previous literatures. In this paper, according to the currently designed DLs, we propose a statistical GDR model to achieve a practical UWB DL, and investigate the degradation in average bit error rate (BER) caused by the GDR for the transmitted-reference (TR) UWB communication systems. According to the analysis results, an improved autocorrelation receiver (AcR) is proposed. Through Monte Carlo simulations, the great performance improvement of the proposed AcR is verified by comparing it with the conventional TR AcR under non-ideal DL conditions. The proposed receiver framework is simple enough to enable a tractable analysis, and provides valuable insights for designing a practical TR UWB AcR that experiences GDR.

We present a carrier and sampling frequency offset estimation and compensation scheme for a multi-band orthogonal frequency division multiplexing (MB-OFDM) ultra-wideband (UWB) modem. We first perform initial carrier frequency offset (CFO) estimation and compensation during the preamble period, and then conduct the estimation and compensation of the residual CFO and sampling frequency offset (SFO) during the payload period. The proposed design scheme reduces the logic gate count of the frequency offset compensation block by about 10%, while it gives almost the same performance at the packet error rate (PER) of 10-4 in the CM1 channel. The frequency offset estimation and compensation block is implemented using 90 nm CMOS technology and tested.

This paper presents an ultra-wideband (UWB) bandpass filter (BPF) with sharp attenuation slope characteristics. The circuit structure consists of an inter-digital finger resonator, parallel-coupled lines and phase matching line. The design of the bandwidth was described by using the even and odd mode characteristic impedances in the resonator structure. The parallel-coupled lines were also designed in the same manner. The parameters of the resonator and two parallel-coupled lines in combination as the BPF were then optimized by the simulation with HFSS. The designed BPF was experimentally fabricated and its measured performances showed the bandwidth from 3.6 to 10 GHz with the 20 dB outband rejection. For the U.S. UWB band design, the matching line was inserted between the two parallel-coupled lines. The matching at both band edges was then qualitatively analyzed on the smithchart. The HFSS simulation results of the structure realized the bandwidth from 3.1 to 10.6 GHz with sharp attenuation slope characteristics for SWR < 2.0. The measurement results agree well with the simulation results.

This letter presents a criterion for selecting a transmit antenna subset when ZF detectors followed by Rake combiners are employed for spatial multiplexing (SM) ultra-wideband (UWB) multiple input multiple output (MIMO) systems. The presented criterion is based on the largest minimum post-processing signal to interference plus noise ratio of the multiplexed streams, which is obtained on the basis of QR decomposition. Simulation results show that the proposed antenna selection algorithm considerably improves the BER performance of the SM UWB MIMO systems when the number of multipath diversity branches is not so large and thus offers diversity advantages on a log-normal multipath fading channel.

Power patterns in the frequency domain are usually used to describe the antenna performance in narrowband communication systems; however, they are not sufficient for ultra wideband (UWB) antennas in wideband communication systems. In this paper, energy pattern and energy gain are introduced to describe the performance of UWB antennas. Numerical simulations and measurements are used to demonstrate the difference between power patterns and energy patterns for narrowband Yagi-Uda antenna, UWB CPW–fed bow-tie slot antenna, and UWB comb taper slot antenna. The results of simulations and measurements are agreement not only in energy pattern, but also in received voltage at various observation angles. For narrowband antennas, the energy patterns are similar to that of the power patterns in the main beam region. However, there are quite differences between power pattern in frequency domain and energy pattern in time domain for UWB antennas.

A signal model and weighted-average based estimation techniques are proposed to estimate the angle-of-arrival (AOA) parameters of multiple clusters for a low data rate ultrawide band (LR-UWB) based wireless positioning system. The optimal AOA estimation techniques for the LR-UWB wireless positioning system according to the cluster condition are introduced and it is shown that the proposed techniques are superior to the conventional technique from the standpoint of performance.

In this paper, the performance of a low duty factor (DF) hybrid direct sequence (DS) multiband (MB)-pulsed ultra wideband (UWB) system is evaluated over realistic propagation channels to highlight its capability of interference mitigation. The interference mitigation techniques incorporated in the DS-MB-UWB system is a novel design that includes the utilization of the frequency-agile multiple sub-band configuration and the coexistence-friendly low DF signaling. The system design consists of a Rake type receiver over multipath and multi-user channel in the presence of a coexisting narrowband interferer. The propagation channels are modeled based on actual measurement data. Firstly, by suppressing the power in the particular sub-band coexisting with the narrowband signal, performance degradation due to narrowband interference can be improved. It is observed that by fully suppressing the sub-band affected by the narrowband signal, a typical 1-digit performance improvement (e.g. BER improves from 10-3 to 10-4) can be achieved. Secondly, by employing lower DF signaling, self interference (SI) and multi-user interference (MUI) can be mitigated. It is found that a typical 3 dB improvement is achieved by reducing the DF from 0.5 to 0.04. Together, the sub-band power suppression and low DF signaling are shown to be effective mitigation techniques against environment with the presence of SI, MUI and narrowband interference.

A 6–10-GHz broadband low noise amplifier (LNA) and transmitting amplifier (TA) for direct sequence ultra-wideband (DS-UWB) are presented. The LNA and TA are fabricated with the 0.18-µm 1P6M standard CMOS process. The CMOS LNA and TA are checked by on-wafer measurement with the DC supply voltage of 1.5 V. From 6–10 GHz, the broadband LNA exhibits a noise figure of 5.3–6.2 dB, a gain of 11–13.8 dB, a P1 dB of -15.7 - -10.8 dBm, a IIP3 of -5.5 - -1 dBm, a DC power consumption of 12 mW, and an input/output return loss higher than 11/12 dB, respectively. From 6–10 GHz, the broadband TA exhibits a gain of 7.6–10.5 dB, a OP1 dB of 2.8–6.1 dBm, a OIP3 of 12.3–15.1 dBm, and a PAE of 8.8–17.6% @ OP1 dB, and a η of 9.7–21.1% @ OP1 dB, and an input/output return loss higher than 6.8/3.2 dB, respectively.

A MB-OFDM UWB transmitter with on-chip transformer and LO leakage calibration for WiMedia bandgroup 1 is presented. The measurements show a gain-flatness of 1 dB, an LOLRR of -53 dBc/-43 dBc (wi/o cali), an EVM of 2.2% with a power consumption of 22 mW and an area of 1.26 mm2.

In this letter, a prerake combining scheme for signal detection in ultra-wideband (UWB) multiple input single output (MISO) systems with a hybrid pulse amplitude and position modulation (PAPM) is analytically examined. For a UWB MISO system, the analytical BER performance of a prerake combining scheme with PAPM is presented in a log-normal multipath fading channel. The analytical BERs are observed to match well the simulated results for the set of parameters chosen. The prerake diversity combining UWB systems, which can significantly reduce the complexity of the receiver side compared to the rake diversity systems, improve the error performance as the number of transmit antennas increases.

Ultra-wide band (UWB) pulse radar has high range resolution, and is thus applicable to imaging sensors for a household robot. To enhance the imaging region of UWB radar, especially for multiple objects with complex shapes, an imaging algorithm based on aperture synthesis for multiple scattered waves has been proposed. However, this algorithm has difficulty realizing in real-time processing because its computation time is long. To overcome this difficulty, this letter proposes a fast accurate algorithm for shadow region imaging by incorporating the Range Points Migration (RPM) algorithm. The results of the numerical simulation show that, while the proposed algorithm affects the performance of the shadow region imaging slightly, it does not cause significant accuracy degradation and significantly decreases the computation time by a factor of 100 compared to the conventional algorithm.

UWB (Ultra Wide-Band) pulse radar is promising for surveillance systems because it has an outstanding high range-resolution. To realize an accurate UWB radar imaging system, we propose a new approach that employs multipath echoes from a target in an indoor environment. Using multipath echoes, the proposed system can accurately estimate images, even for targets in a shadow region where the targets are out of sight of the antenna. We apply a simple interferometry technique using the multiple mirror image antennas generated by multipath propagation. We find that this simple method also produces many undesired false image points. To tackle this issue, we also propose an effective false image reduction algorithm to obtain a clear image. Numerical simulations verify that most of the false image points are removed and the target shape is accurately estimated.

Antipodal Fermi antenna (APFA) that uses an antipodal feeding section is proposed and its fundamental characteristics are presented. It is shown that the cross polarization level is decreased by 5–10 dB by the presence of the corrugation. It is also found that high gain, low VSWR and low side lobes and low back lobes are obtained. The mechanism of operation principles is discussed by using FDTD analysis. It is found that the corrugation transforms the current of parallel line mode to the current of traveling wave radiation mode and the effective aperture is enlarged which yields high gain characteristics.

The applicability in harsh optical environments, such as dark smog, or strong backlight of ultra-wide band (UWB) pulse radar has a definite advantage over optical ranging techniques. We have already proposed the extended Synthetic Aperture Radar (SAR) algorithm employing double scattered waves, which aimed at enhancing the reconstructible region of the target boundary including shadow region. However, it still suffers from the shadow area for the target that has a sharp inclination or deep concave boundary, because it assumes a mono-static model, whose real aperture size is, in general, small. To resolve this issue, this study proposes an extension algorithm of the double scattered SAR based on a multi-static configuration. While this extension is quite simple, the effectiveness of the proposed method is nontrivial with regard to the expansion of the imaging range. The results from numerical simulations verify that our method significantly enhances the visible range of the target surfaces without a priori knowledge of the target shapes or any preliminary observation of its surroundings.

In this letter, the reliabilty of the generalized normal-Laplace (GNL) distribution used for modeling the multiple access interference (MAI) plus noise in time-hopping (TH) binary phase-shift keying (BPSK) ultra-wideband (UWB) systems is evaluated in terms of the probability density function and the BER. The multiple access performance of TH-BPSK UWB systems based on GNL model is analyzed. The average BER performance obtained by using GNL approximation well matches with the exact BER results of TH-BPSK UWB systems. The parameter estimates of GNL distribution based on the moments estimation method is also presented.

This letter provides a tight upper bound on the bit error rate (BER) over the Nakagami-m fading channel for the dual carrier modulation (DCM) scheme, which is adopted by the multi-band orthogonal frequency division multiplexing (MB-OFDM) ultra-wideband (UWB) system. Its tightness is verified with the existing result for Rayleigh fading channel, i.e., for m=1, which would be also valid for a more general fading environment.

We propose an improved TDoA (Time Difference of Arrival) localization scheme based on PSO (Particle Swarm Optimization) in UWB (Ultra Wide Band) systems. The proposed scheme is composed of two steps: the re-estimation of TDoA parameters and the re-localization of tag position. In both steps, the PSO algorithm is employed to improve the performance. In the first step, the proposed scheme re-estimates the TDoA parameters obtained by traditional TDoA localization to reduce the TDoA estimation error. In the second step, the proposed scheme with the TDoA parameters estimated in the first step, re-localizes the tag to minimize the location error. Simulation results show that the proposed scheme achieves better location performance than the traditional TDoA localization in various channel environments.

In this letter, we propose an effective preamble based on constant amplitude and zero auto-correlation (CAZAC) sequence for multi-input multi-output (MIMO) and cooperative WiMedia ultra-wideband (UWB) systems. The proposed preamble even provides better single-channel estimation performance than the preamble specified in the standard in severe UWB channel model. The effectiveness of the proposed design is confirmed through the mean square error (MSE) performance.

This paper develops planar circuit filters consisting of arbitrarily-shaped conductor patches and slots on a conductor-backed dielectric substrate, which are designed by an optimization technique based on the genetic algorithm. The developed filter has multiple resonators and their mutual couplings in the limited space by using both sides of the substrate, so that its compactness is realized. We first demonstrate the effectiveness of the present filter structure from some design samples numerically and experimentally. Then as a practical application, we design compact UWB filters, and their filter characteristics are verified from the measurements.

A differential BPSK transmitter for ultra-wideband impulse-radio communication has been presented in this paper. The transmitter, developed in a 65 nm CMOS process,is simple in design and occupies a core area of 0.0017 mm2. The differential Gaussian monocycle pulses (GMP) are generated using some logic blocks and delay elements. The generated GMP, having a center frequency above 5 GHz, meets the FCC regulations. Measured results show that the transmitter consumes 1.8 pJ/bit to transmit BPSK modulated GMP at a data rate of 2 Gb/s. The interface circuitries eliminate the need for external networks for chip to antenna matching. Using an off-chip differential bow-tie antenna, data can easily be transmitted up to a distance of 10 cm which made it suitable for low power far field non-coherent applications.