New-Wave Radio

1.1 Impulse Radio (IR) Ultra Wideband (UWB) Communications Ultra wideband (UWB) communication is a fast emerging technology that offers new opportunities such as high data rates, low equipment cost, low power, precise positioning capability and extremely low interference Ghawami (2005). A wide range of possible UWB communication system applications includes radars due to UWB ultra high precision ranging at the centimeter level, wireless personal area networks (WPAN), sensor networks, imaging systems, UWB positioning systems, etc. Yang (2004), Kshetrimayum (2009). From a commercial point of view, the high data rates are the most attractive feature of UWB systems for which speeds of over 100Mb/s have been demonstrated Ghawami (2005). There exist three main types of UWB technologies: impulse radio (IR UWB), direct sequence (DS UWB), and multi-band orthogonal frequency division multiplexing (MB OFDM) Ran (2009). IR UWB communication technique is essentially different from all other communication techniques because it is carrier free and uses for communication between transmitters and receivers very narrow radio frequency (RF) pulses generated from the UWB pulse generator, while traditional transmission systems transmit information by varying the power, frequency, and/or phase of a sinusoidal wave in a modulation process Kshetrimayum (2009), Yao (2007). Consequently, complicated frequency mixers and local oscillators for carrier frequency up and down conversion are not necessary Yao (2007). IR UWB modulation techniques are especially important because the UWB spectrum has been made available by the Federal Communication Commission (FCC) and it can be used with IRs developed to date Lin (2005). Waveforms for IR UWB are designed to obtain a flat frequency response over the bandwidth of the pulse and to avoid a DC component. The large spectrum of a UWB signal may interfere with existing users. In order to keep this interference to the minimum, FCC specifies spectral masks for different applications, i.e. the allowed power output for specific frequencies Ghawami (2005). A contiguous bandwidth of 7.5GHz is available in the frequency interval of (3.1− 10.6)GHz at a maximum power output of −41.3dBm/MHz which is considered as extremely low Ghawami (2005). The power spectral density (PSD) of UWB systems defined as a ratio of the transmitted power P in watts and a signal bandwidth B in hertz is extremely low as compared to other communication systems due to the very wide bandwidth B of short pulses that are typically of nanosecond or picosecond order Ghawami (2005). The selection of the impulse signal type for IR UWB communication system is essential since it determines

The emerging feature-rich and high-data-rate wireless applications have put increasing demand on radio spectrum. The scarcity of spectrum and the inefficiency in its usage, as caused by the current radio spectrum regulations, necessitate the development of new dynamic spectrum allocation policies to better exploit the existing spectrum. The current spectrum allocation regulations assign specific bands to particular services, and grant licensed band access to licensed users only. Cognitive Radio (CR) will revolutionize the way spectrum is allocated. In a CR network, the intelligent radio part allows unlicensed users (secondary users) to access spectrum bands licensed to primary users, while avoiding interference with them. In this scheme, a secondary user can use spectrum sensing hardware/software to locate spectrum portions with reduced primary user activity or idle spectrum slots, select the best available channel, coordinate access to this channel with other secondary users, and vacate the channel when a primary user needs it. To achieve this, the transceiver in a CR system should have awareness of the radio environment in terms of spectrum usage, power spectral density of transmitted/received signals, and wireless protocol signaling, should be able to adaptively tune system parameters such as transmit power, carrier frequency, and modulation strategy. The transceiver should also be ended with an antenna system that can simultaneously operate over a wide frequency band (sensing) and a chosen narrow band (communication), or operate over an ultra-wide frequency band while possibly blocking signals in a narrow frequency range. Ultra-wideband (UWB) is a transmission technique that uses pulses with a very short time duration across a very large frequency portion of the spectrum. UWB is different from other radio frequency communication techniques in that it does not use RF carriers, but instead employs modulated high frequency pulses of low power with a duration of less than 1 nanosecond. From the perspective of other communication systems, the UWB transmissions are part of the low power background noise. Therefore UWB promises to enable the usage of licensed spectrum without harmful interference to primary communication systems, and can be used as an enabling technology for implementing CR. In this chapter, we offer a general overview of Cognitive Radio and dynamic spectrum access, discuss the advantages of using UWB as an enabling technology for CR, and give

Ultra wideband (UWB) technology has been widely researched for both radar and communication systems. However, detecting the presence of a signal is essential and challenging for many applications. In this paper, we propose a novel detector for UWB radar signals with UWB communication interference by exploiting the signal cyclic features. A single-cycle detector based on fundamental cyclic frequency of radar signal is proposed to detect UWB radar signal. Simulation results illustrate the possibility to detect the UWB radar signal under the coexistence of a UWB communication signal and the proposed scheme is compared with conventional detectors for UWB radar systems.

A novel method to generate ultra-wideband (UWB) signals based on two differential group delay modules and one Mach-Zehnder Modulator is proposed. Both simulation and experiments verified that the method could generate two kinds of UWB monocycles using low bit-rate non-return-to-zero data source (1Gbps). The monocycles have a fractional bandwidth of 127% at centre frequency 5.5GHz. Keywords: Ultra wideband (UWB), radio-over-fiber (RoF), differential group delay (DGD) 1. INTRODUCTION Ultra-wideband (UWB) is a fast emerging technology for short-range broadband wireless communication such as wireless personal area network and sensor network, etc. The UWB signal occupies wide bandwidth and has low power density, and it has immunity to multi-path fading [1]. As a carrier-free modulation scheme, direct-sequence impulse radio is more cost-effective and simpler compared with multi-band orthogonal frequency scheme. Since UWB is a room-scaled short range wireless communication technique, the wireless networks can operate mainly in indoor environment in standa lone mode. Considering the integration of UWB access networks and fixed wired networks, the combination of UWB-over-fiber technology and fiber-to-the-home (FTTH) technology is a competitive candidate for future wideband access networks [2]. So many all-optical schemes that fit for UWB-over-fiber technology to generate and distribute UWB impulses have been reported recently. Zeng et al. proposed two approaches to generate UWB impulses using one phase modulator (PM), and 25-km single mode fiber (SMF) or FBG to convert phase-modulated light to UWB pulses [3, 4]. Wang and Dong proposed UWB signal generation using cross-gain modulation or cross-phase modulation in semiconductor optical amplifier [5, 6], which requires two laser sources and may increase the system complexity. Chen proposed a scheme based on optical polarization time delay [7]. It is a simple method, but the elect rical signal source needs at least twice bit-rate compared to the carried data. Most of the schemes n eed an electrical Gaussian pulse source, which is comm only composed of a high-speed pulse pattern generator (PPG). This is an expensive construction, for which the PPG should work at least 10 Gbps. Furthermore, if data are carried on the UWB pulses, another modulator should be added to the systems, which increase the system cost and complexity. In this paper, we proposed and experimentally demonstrated a simple method to generate data-carried UWB monocycle pulses based on two differential group delay (DGD) modules and one Mach-Zehnder modulator (MZM). Instead of the data pattern “1000 0000 ”, which has one “1” followed by several “0”s to form the UWB signal, we use electrical non-return-to-zero (NRZ) data. The NRZ data modulate the optical signal in MZM to get an optical binary phase shift keying (BPSK) signal, which is then fed into two cascade DGD module s while the polarization of the light is carefully adjusted

Ultrawideband (UWB) is a promising technology for getting high data rate communications. UWB communications refer to the utilization of signals with a frequency range (3.1 to 10.6 GHz) on the condition of having a fractional bandwidth of 20% or absolute bandwidth of 500 MHz or higher. The limited power spectral density of − 41.3 dBm/MHz allows UWB communications to be safely deployed with existing wireless communication systems without causing any interference. Consequently, UWB communication systems have been proposed for different outdoor and indoor scenarios. A variety of applications are suitable for UWB communications ranging from infostations, wireless sensor networks (WSNs), on-body communications, in addition to consumer, medical and military applications. Recently, this technology shows a promising step for indoor positioning accuracy where the functioning of navigation systems such as Global Positioning System (GPS) or GLObal NAvigation Satellite System (GLONASS) might be degraded. In this paper, the fundamental properties of UWB communications are presented with an illustration on the present and future direction of this technology.

The inter-vehicles communication is becoming increasingly mandatory to improve the road safety and to allow a better transport management. The concept behind an intelligent vehicle consists in equipping this vehicle with an optimum number of sensors, in order to perceive the environment surrounding it and to ensure an automatic guidance control and the communication with the infrastructure and other vehicles. Among the most often used tools for this objective, we can cite the embedded radar. Moreover, the Ultra Wide Band (UWB) communication systems are under fast development and undergo progressive implementation. The principle of UWB technology is to transmit rather low power, carrier-less, signals occupying a very broad spectrum [1]. The spectral concentration of radiated power is thus extremely low, so that the other systems perceive UWB ones like background noise. In this article, a road radar based on UWB technology is studied. The proposed device allows, in a road environment, good resolution and increased precision for detection and localization of obstacles.

Recently, ultra wideband (UWB) communications have received increasing interest due to the high data rate achievable in a short distance. UWB communications can have strong interference mitigation capability. A multicarrier ultra wideband (MC-UWB) system has been introduced in (A.H. Tewfik, et al., (2002)) and (E. Saberinia, et al., (2002)). In the MC-UWB communication systems, multiple symbols are transmitted over different carriers simultaneously. The same symbol is retransmitted over different frequency bands by utilizing frequency hopping (FH) techniques. Frequency hopping and multicarrier technologies smooth the average power spectrum density of the system. In this paper, the expression of the power spectrum density of the MC-UWB system is derived. The radiated emission power for UWB communication systems is limited by the spectrum mask specified by wireless communication authorities, such as the federal communications commission (FCC) in United States. Different parameters in the MC-UWB system will have different effects on the power spectrum density and the maximal achievable data rate. The analysis of impact of parameters in the system on the power spectrum density will help the system designer select proper parameter set to fit in emission power regulation and the required data rate in practical UWB systems. Some examples of parameter selection are also given to illustrate the impact of different parameters in the system on the power spectrum density.

This paper introduces an indoor integrated navigation system for the auto-control of unmanned aerial vehicle (UAV) and robot that fuses inertial sensors and ultra wide band (UWB) networks. In this paper, we concentration on the problem of selecting the optimized UWB anchor node to obtain the distance measurement between the selected anchor node and the tag node for this indoor integrated navigation system. Taking the navigation accuracy and system power consumption into account according to the requirements and features of UWB system, we propose and analyze the performance of four kinds of anchor node selection algorithms, named alternation algorithm, powerfirst algorithm, accuracy-first algorithm and the optimized algorithm considering power and accuracy. In the fourth algorithm, we introduce dynamic local dilution of precision (DOP) values which reflect the impact of the geometric distribution of anchor nodes to guarantee precision and define a cost function of DOP values and UWB communication distance for a complementary consideration of power consumption. To fuse the inertial sensor data and the selected UWB distance measurement, an extended Kalman filter (EKF) is applied in this integrated system to correct the state errors. Simulations and experiments with low-cost Micro-electromechanical inertial sensors and Decawave UWB transceivers have been done to evaluate the performance of these four anchor node selection algorithms. The simulation and experiments results verify that the fourth algorithm proposed in this paper can achieve a good balance in system multiple demands of navigation accuracy and system power consumption.

When several ultra-wide band (UWB) communication systems coexist, multiuser interferences (MUI) are unavoidable. To cope with the MUI of UWB systems, the independent of UWB signals are investigated and a novel receiving method is proposed. At first several antennas are utilized to receive the transmitted signals of different UWB users, and the mixture signals are gained. Then the mixed signals are separated by independent component analysis algorithm to recover the transmitted signals of each UWB users. Finally, the information of each UWB users transmitted is demodulated. Computer simulations show that the proposed method can efficiently resist the interference of different UWB users.

An ultra wideband (UWB) technology is a potential candidate for implant body area networks (BANs), where wireless communications are established between inside and outside of a human body. The UWB can accomplish higher data rate than the other frequency band for the implant communication. However, due to its high frequencies, the UWB signals suffer from quite large attenuation in the implant communication link, which makes it difficult to achieve reliable communications. For achieving reliable communication, it is well known that a spatial diversity technique is efficient without any frequency extension. In our previous works, we developed a transmit polarization diversity antenna for the UWB implant communication. However, optimal UWB modulation scheme for transmit diversity were rarely discussed. In this paper, in order to investigate the optimal UWB modulation schemes for implant communication with transmit diversity, we compare the communication performances of UWB-impulse radio (UWB-IR) and multiband-orthogonal frequency division multiplexing (MB-OFDM). For this purpose, we first analyze the propagation characteristics in the implant UWB channel, which ranges from 3.4 GHz to 4.8 GHz, using a finite difference time domain (FDTD) numerical analysis technique. Then, we evaluate and discuss the communication performances of both modulation schemes for the transmit polarization diversity from the viewpoint of the BER and the required transmit power.

This thesis deals with current-mode techniques for ultra-wide band applications. An overview of ultra-wide band (UWB) wireless communications is presented. Two standards for UWB data communications, namely direct-synthesis UWB (DS-UWB) and Multi-band orthogonal frequency division multiplexing (MB-OFDM) UWB are presented. MB-OFDM UWB devices must hop among 14 UWB channels within 9.5 ns, imposing stringent constraints on design of frequency synthesizers. A review of the state-of-the-art frequency synthesizers for MB-OFDM UWB applications is provided. Current-mode phase-locked loops with active inductors and active transformers employed in both loop filters and voltage-controlled oscillators are proposed and their performance in analyzed. Current-mode phase-locked loops decouple the PLL dynamic range from the scaling down of the supply voltage. An active-inductor VCO with both coarse and fine frequency adjustment, a hybrid VCO with a step-down passive transformer loaded with an active inductor, and a hybrid VCO with a step-down passive transformer with a varactor are proposed and their performances are analyzed. These VCOs obtain wide frequency tuning ranges without relying on switched back networks. To meet the timing constraint of UWB frequency synthesizers, Current-mode techniques are further developed for UWB frequency synthesizers. An active inductor with a bank of switched capacitors is proposed to provide fast locking. The bank of switched capacitors eliminates the frequency acquisition locking time of the frequency synthesizer, allowing 9.5 ns phase locking time. The proposed current-mode phase-locked loops, active-inductors oscillators and hybrid oscillators were designed and implemented in TSMC-0.18 μm and IBM-0.13 μm CMOS technologies.

This paper investigates spectrum shaping in ultrawideband (UWB) communications in order to introduce spectral nulls to limit interference with narrowband signals. Each transmitted symbol is represented by a monocycle "coded" Gaussian pulse, where use of the monocycle Gaussian pulse ensures that the UWB spectrum mask established by the Federal Communications Commission (FCC) is met and where the codeword is designed to generate a spectral null at the frequency or frequencies being used by existing narrowband devices. Signals obtained with different spectrum shapings (e.g., Butterworth, Chebyshev, elliptical) and by introducing nulls at multiple interference frequency bands are discussed. The performance of a monocycle coded UWB system with a spectral null in the presence of narroband interference (NBI) using single carrier block transmission with frequency domain equalization (SC-FDE) is simulated and compared with that of an uncoded SC-FDE UWB system using a single Gaussian monocycle. Our results show that NBI can be effectively suppressed by transmitting and matched filtering the pulse with a spectral null at the interference frequency, therefore improving the robustness of SC-FDE UWB to NBI.

The performance of ultra wideband (UWB) communications are very important for short range wireless communication to consider with matched filter and correlation receivers are evaluated. The rectangular passband, modulated rectangular and modulated Gaussian waveforms, which is satisfied the UWB signal definition and Federal Communications Commission (FCC) indoor and outdoor limit spectral masks, are used as the transmitted UWB signal. The complex form of Friis' transmission formula is considered as the UWB free space channel. Therefore, the distortion effects caused from the channel are included. The BER performance of each waveform is shown and compared. The results are discussed in the conclusion.

Ultra Wideband (UWB) communications are steadily gaining acceptance worldwide, as theregulatory bodies of several countries define its frequency bands and rules of operation. OutofthemanytechnologiesavailabletogenerateanUWBsignal,twoofthemhavebeenfavored,in recent standardization activities, namely Orthogonal Frequency Division Multiplexing(OFDM) and Impulse Radio (IR). On one hand the IEEE 802.15.3a standard defines an UWBsignal based on OFDM, which consists of a large number of digitally-generated narrow sub-carriers. On the other hand, the IEEE 802.15.4a standard defines an UWB signal based onpulses of short duration, technology known as IR. In addition to these technologies includedin standards, other modulation schemes have been proposed for UWB, such as frequency-modulated UWB, or IR transmitting even shorter, sub-nanosecond pulses. The latter has theadvantage of providing very accurate ranging and localization estimates based on the time ofarrival, which can be measured with high precision thanks to the large signal bandwidth.In this chapter we will address the challenges encountered in the transmission and detec-tion of an Impulse Radio Ultra Wideband (IR–UWB) signal in environments with multipathpropagation. The main problem in such systems is that multipath produces time dispersionresulting in a very large number of resolvable paths at the receiver. We will argue that it isconsiderably difficult to design receivers that have both high efficiency in capturing the re-ceived signal energy and low complexity. The traditional approaches, such as correlating thereceived signal with a local template, or the RAKE Receiver, suffer from poor performancesince they have to lock to a single propagation path, or a small subset of them, respectively.Non-coherent receivers also fail to deliver the full potential of UWB; in particular, they do notprovide sufficient ranging accuracy.Motivated by this challenge, in this chapter we develop a receiver architecture based on afrequency domain filter bank. The receiver consists mainly of a stage of bandpass filters fol-

In this paper, we present the results of the measurements and modeling of the propagation channel for ultra wide band (UWB) communications in large indoor environments. The selected environment is a sports center of large dimensions ($51 \times 26$ m, 7.4m height) without intermediate obstacles so that there is always direct path (DP) between TX and RX and UWB technology can be used for critical communications of sensors. On this environment, narrow band and ultra wide band measurements have been made with a high resolution pulse channel sounder (8ns) at the nominal frequency of 3.9 GHz. Narrow band measurements have been used to model path loss for the DP, while for UWB measurements, the power delay profile have been used to obtain the statistics of the multipath of the channel. Combining both models has been possible to obtain a detailed characterization of the environment. The results constitute a complete characterization of this type of indoor environments for UWB signals and can be easily extrapolated to other environments with similar characteristics, allowing the use of UWB technology for applications of critical communications for sensors and other devices.