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This paper describes the Impulse Radio Ultra-Wideband (IR-UWB) system using linear chirp UWB pulses as symbols. The novel method of coherent or differentially coherent detection of chirp pulses in multipath channels is introduced. The method divides detection in the receiver between its analog and digital part; in the analog part of the receiver, r...
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... in numerical analy- sis provided here both the sampling and chirp receiver use the same low-complexity integrate and dump low-pass anti- aliasing filters which thus do not significantly influence overall implementation complexity. What is, from the implementation point of view, novel regarding both chirp receiver and chirp transmitter, shown on Fig. 4, is the chirp pulse generator that replaces IR-UWB short-pulse [10], [31], or short-pulse burst [32], [33] ...
Context 2
... model of the transmitter used in the system is shown on Fig. 4. The transmitter uses phase modulated chirp pulses of the form (7), as symbols. Since symbol period T sym is longer than chirp pulse duration T p , it is possible to use time hopping in the system. Time hopping in the multi- user environments reduces Multi-User Interference (MUI) and distributes it evenly among users in the system. ...
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A novel timing acquisition method is proposed for ultra-wideband (UWB) wireless communications in dense multipath environments. This method is based on the time reversal technique that employs the temporally reversed channel probing waveforms rather than initial source pulses as the carrier to send the timing preambles. The temporally reversed chan...
Citations
... Essentially, OCDM is a specialized chirp spread spectrum (CSS) technology that achieves the Nyquist signaling rate with optimal spectral efficiency, analogous to OFDM and frequency-division multiplexing (FDM). However, compared to traditional CSS systems, which are notorious for their poor spectral efficiency due to the non-orthogonal chirped waveforms [17]- [19], the chirps in OCDM are mutually orthogonal, and thus attain the maximum spectral efficiency at the so-called Nyquist signaling rate [7]. ...
In multiple-input multiple-output (MIMO) systems, channel estimation is of crucial importance to guarantee reliable recovery of ultra-high-speed MIMO signals. This paper proposes a novel channel estimation algorithm for the emerging MIMO-based orthogonal chirp-division multiplexing (OCDM) systems by utilizing the unique features of OCDM signals. In the proposed algorithm, a set of pilot signals is designed based on the Fresnel basis, which is essentially a family of orthogonal linear chirps. The pilots are assigned to different antennas for transmission occupying the same time slot and bandwidth. According to the convolution-preservation theorem of the Fresnel transforms, the transfer matrices of MIMO-OCDM systems can be readily estimated at the receiver without any inter-antenna interference, even if the pilots overlap in both the time and frequency domains. The proposed algorithm avoids bandwidth waste in conventional channel estimators, in which silent pilots will be required in time and/or frequency to ensure the received MIMO pilots separable. We show that the proposed algorithm is unbiased for the unique OCDM pilots and has better estimate accuracy and system performance. Finally, analysis and numerical results are provided to validate its advantages as a promising algorithm for emerging wireless access technology based on MIMO-OCDM.
... Essentially, OCDM is a specialized chirp spread spectrum (CSS) technique that achieves the Nyquist signaling rate with optimal spectral efficiency, analogous to OFDM and frequency-division multiplexing (FDM). However, compared to the traditional CSS techniques, which are notorious for their poor spectral efficiency because of the non-orthogonal chirped waveforms [12], the chirps in OCDM signal are mutually orthogonal, and thus attain the maximum spectral efficiency in terms of the Nyquist signaling rate. Moreover, in virtue of the spread-spectrum feature inheriting from CSS, OCDM shows superior resilience in combating various detrimental effects in communication systems, and thus outperforms other waveform modulation techniques, such as OFDM. ...
... Wideband antennas become increasingly important to meet the desire to use more various communication systems, such as ultra-wideband systems [1,2], cognitive radio systems [3], and white space systems [4,5]. Further, in software radios, the wireless system can be changed without replacing the antenna when it is wideband enough. ...
Abstract A wideband planar antenna, which is composed of a ground plate and a strip surrounding the plate, is proposed. Wideband impedance matching with fractional bandwidth over 130% is achieved by making the distance between the strip and the ground plate stepwise so that the distance becomes wider in the tip side. The electric field in the slot line changes its direction without changing the traveling direction at the stepped section, and it is enabled to leak and radiate while traveling. It was also found that the matching frequency band can be greatly extended to the high frequency side by bending and extending the slot line to surround the ground plate. The lowest impedance matching frequency can be controlled by the strip width at the tip with keeping wideband impedance matching property.
... By overlapping subbands and modulating with pseudorandom sequences, the scheme improves modulation efficiency in frequency and time domain. Analog and digital correlators are both adopted in [7]. The correlation by the former reduces the time-bandwidth product of a chirp signal and thereby reducing the complexity of post-stage digital processing. ...
Biorthogonal Fourier transform (BFT), consistent with the matched signal transform (MST), has been introduced to demodulate the M-ray chirp-rate signal which possesses good orthogonality in the BFT domain. Here, we analyze the characteristics of BFT detection in a further step, including the resolution capability of the multichirp-rate signal, the property of pulse compression, the closed-form bit-error rate in the additive white Gaussian noise (AWGN) channel, and the interference in the time-frequency dispersive channel. Even in the high Doppler environment, the shift in BFT detection is proven to be slight. In addition, we deduce that the orthogonality among received chirp rates in the BFT domain would be affected in the multipath dispersive environment. This causes the mutual interference among different chirp rates in a symbol and over symbols concurrently. The theoretical result shows that the chirp modulation parameter can be adjusted to obtain the trade-off between time and frequency dispersion. By the multipath model of chirp-rate signal, an auxiliary parallel interference cancellation (PIC) method is further introduced in multipath environment. Simulations verify our analyzed performance of BFT detection in the AWGN, Doppler, and multipath channels. The proposed interference cancellation algorithms are also proven to be effective.
... This results in Pulsed FM signal whose bandwidth is limited only by physical ability to shift a carrier frequency and by the ability to construct a receiver to demodulate it. The Chirp Spread Spectrum receiver can employ a matched filter to reassemble the time dispersed carrier power (Dotlic, 2011). This technique uses its entire allocated bandwidth to broadcast a signal, making it robust to channel noise. ...
... This results in Pulsed FM signal whose bandwidth is limited only by physical ability to shift a carrier frequency and by the ability to construct a receiver to demodulate it. The Chirp Spread Spectrum receiver can employ a matched filter to reassemble the time dispersed carrier power (Dotlic, 2011). This technique uses its entire allocated bandwidth to broadcast a signal, making it robust to channel noise. ...
Wireless Sensor Networks (WSNs) technologies have been successfully applied to a great variety of outdoor scenarios but, in practical terms, little effort has been applied for indoor environments, and even less in the field of industrial applications. This paper work presents an intelligent hybrid WSN application for an indoor and industrial scenario, with the aim of improving and increasing the levels of human safety and to avoid the denial of service (DoS) attacks. Since its operates on a wireless network, an adversary can always perform a DoS attack by jamming the radio channel with a strong signal. The main contribution of our work is to use a hybrid approach that handles the problem of jamming. The proposed solution improves security by protecting against DoS and returns near-optimal solutions. The paper shows the viability of our approach in terms of performance, scalability, modularity and safety.
... 15.4a group [17], the chirp signal is adopted to satisfy the requirement of FCC on the radiation power spectral mask for the unlicensed UWB systems. Meanwhile, the chirp signal achieves what a UWB system is supposed to do, i.e., ranging, measuring and communicating [18][19][20]. ...
... Inspecting Equ. (19) and (20), one can compare them with the definition of DFnT in Equ. (6), and find that they are exactly the IDFnT. ...
... To express Equ. (19) and (20) ...
Chirp waveform plays a significant role in radar and communication systems for its ability of pulse compression and spread spectrum. This paper presents a principle of orthogonally multiplexing a bank of linear chirp waveforms within the same bandwidth. The amplitude and phase of the chirps are modulated for information communication. As Fourier trans-form is the basis for orthogonal frequency division multiplexing (OFDM), Fresnel transform underlies the proposed orthogonal chirp division multiplexing (OCDM). Digital implementa-tion of the OCDM system using discrete Fresnel transform is proposed. Based on the con-volution theorem of the Fresnel transform, the transmission of the OCDM signal is analyzed under the linear time-invariant or quasi-static channel with additive noise, which can gener-alize typical linear transmission channels. Based on the eigen-decomposition of Fresnel transform, efficient digital signal processing algorithm is proposed for compensating chan-nel dispersion by linear single- tap equalizers. The implementation details of the OCDM system is discussed with emphasis on its compatibility to the OFDM system. Finally, simula-tion are provided to validate the feasibility of the proposed OCDM under wireless channels. It is shown that the OCDM system is able to utilize the multipath diversity and outperforms the OFDM system under the multipath fading channels.
... The purpose of this paper is to explore different IR-UWB receiver architectures for PPM and DPSK modulations and evaluate their performances in noise and multiple access interference environments. Furthermore, performances with and without chirp pulse compression [5] are examined; this is also a link of this work to IEEE 802.15.6-2012 IR-UWB PHY specs, since these includes chirp pulse as a transmitted IR-UWB waveform [1]. ...
... The symbol waveform used is a single ideally linear chirp pulse denoted c(t) with frequency sweep interval ∆f c and duration T p [5]; it is either DPSK or binary PPM modulated. Hence, the transmitted signal of the k-th symbol can be expressed as ...
... Considered receiver architectures with quadrature baseband signal processing is shown in Fig. 1. When the switch marked "S" is in the lower position, the receiver is in a chirp receiver configuration [5], while when "S" is in upper position receiver Fig. 1. Receiver architectures considered. ...
The paper analyses several modulation and detection pairs for Impulse-Radio Ultra-Wideband (IR-UWB) Body Area Networks (BANs). First, transceiver architectures with and without chirp pulse compression are described. After that, exact expressions for the bit error probabilities in noise are given. At the end, numerical analysis is performed that includes performances in noise and performances in multiple access interference, which are especially critical for medical IR-UWB BANs.
... The classic technique for signal dimension reduction that aims to remedy this effect is match-filtering pulse compression, in which the dimension of the received waveform is reduced by filtering it with a filter matched to the transmitted waveform; in the analog domain, this is usually implemented in Surface Acoustic Wave (SAW) technology. However, as we discussed in [2], implementation of SAW filtering of the received IR-UWB signal is technologically challenging for several reasons. I To make pulse compression more compatible with contemporary integrated circuit technology, we proposed chirp pulse compression in [2]. ...
... However, as we discussed in [2], implementation of SAW filtering of the received IR-UWB signal is technologically challenging for several reasons. I To make pulse compression more compatible with contemporary integrated circuit technology, we proposed chirp pulse compression in [2]. This pulse compression technique can be utilized if the transmitted waveform is a linear chirp pulse; the technique involves mixing the received waveform with a chirp pulse generated locally in the receiver, after which the signal is low-pass filtered. ...
... This pulse compression technique can be utilized if the transmitted waveform is a linear chirp pulse; the technique involves mixing the received waveform with a chirp pulse generated locally in the receiver, after which the signal is low-pass filtered. In [2], we analyzed the performance of this kind of pulse compression in classic DPSK detection, i.e., detection with matched-filtering and phase discrimination. We concentrated on the DPSK digital processing complexity and performance analysis with and without chirp pulse compression. ...
The paper investigates chirp pulse compression as a signal dimension reduction technique in non-coherent impulse-radio ultra-wideband (IR-UWB) communications. Two common types of non-coherent IR-UWB detection are considered, energy detection of IR-UWB pulse position modulated (PPM) symbols and sample-wise differential detection of differential phase shift keying (DPSK) IR-UWB symbols, as well as a newly introduced sample-wise differential detection of IR-UWB PPM symbols. A common problem with these low-complexity IR-UWB detection schemes is poor performance when the dimension of the symbol in detection is high, which is usually the case at low data rates and is especially pronounced in interference environments. Chirp pulse compression mitigates this problem by reducing the dimension of the symbol in detection along with very small fading factor, which also lowers the computational complexity in the case of digital implementation. In the analytic part of the paper, we develop a closed-form expression for the bandwidth and dimension of the signal after the chirp pulse compression, which was lacking before. Furthermore, a closed-form expression of the bit error probability in white noise with the above detection schemes is also given. In the numerical part of the paper, we compare the performance with and without chirp pulse compression of the above modulation/detection pairs in noise and interference environments.
... In this paper we will consider performance of IEEE 802.15.6 DPSK IR-UWB PHY with two receiver architectures shown in Fig. 3: the duty-cycled sampling receiver and the chirp receiver. These receiver architectures were described in our previously published work [2,3]. In short, during PSDU detection, both the duty-cycled sampling receiver and the chirp receiver operate only at a portion of T sym which is comparable or equal to T P L w . ...
... Hence, chirp receiver needs lower number of samples per symbol than sampling receiver, i.e. lower digital back-end complexity. However, regardless of the lower digital backend complexity, the performance of the chirp receiver is better than that of the sampling receiver in many scenarios studied [2,3]. = 32 ns. ...
The paper analyses performances of the two lowest data rates of impulse-radio ultra-wideband DPSK physical layer of recently published IEEE 802.15.6 Body Area Networks standard. Two receiver architectures suitable for the reception of symbols with signal structure described in specification of this physical layer, namely duty-cycled sampling receiver and chirp receiver, are introduced. Then, performance of these receiver architectures are analyzed through probabilities of error in different phases of packet reception. Analysis has been performed in the presence of different types of interference; namely frequency modulated ultra-wideband, WiMax and other co-located IEEE 802.15.6 impulse-radio ultra-wideband devices.
