Tamas Krebesz

Budapest University of Technology and Economics · Department of Measurement and Information Systems

In-car wireless data communications systems require a short-range unlicensed radio communications technology that causes a very low-level of interference in the other, already deployed radio links and networks, offers low and medium data-rate, can re-use the already occupied radio frequency bands and assures low probability of message collisions. U...

In Software Defined Electronics (SDE), the software and hardware components are completely separated. Every information processing system from communications to measurement engineering is implemented in BaseBand (BB) on a SW platform and the interface between the baseband and RF/microwave domains is assured by a universal HW device. Due to the univ...

A specific method for the application of a universal software defined wireless platform is presented to determine system performance of communications system based on real field tests. On the platform every application can be implemented: the transmitter and the receiver establishing a wireless link, the communications channel and the algorithm to...

A universal software defined wireless platform and a specific method for its application is proposed here to perform field test measurements for performance evaluation of communications system. The platform implements every application, starting from the transmitter and receiver of wireless link, the virtual measurement instruments for the baseband...

Radio coverage is limited by two parameters: (i) energy per bit radiated by the transmitter and (ii) BER performance of the receiver. In Ultra-Wideband Impulse Radio (UWB IR) the former is limited by the FCC Regulations while the latter depends on the detection algorithm. The fact that prevents the use of UWB IR devices in real applications is the...

The analog signal processing is substituted everywhere by its digital counterpart because of its higher accuracy and flexibility, its much lower cost and because in digital signal processing there is no need for regular calibration as it is required in the analog systems. The most important feature of digital approach is that the HW and SW componen...

In low-rate UWB impulse radio the carrier pulses have very short duration that limits the energy per bit in an extremely low value. The low bit energy results in an unacceptable short radio coverage. In the paper new UWB carrier pulse generation techniques are proposed to increase the pulse duration considerably. In order to get an ultra wideband c...

óThe radio coverage is limited by the energy per bit transmitted. UWB pulses used in impulse radio are extremely short and, consequently, carry a very little energy per bit that results in an unacceptable short radio coverage. The energy per bit could be increased by enlarging the duration of UWB carrier pulse, however, this solution cannot be used...

The energy transmitted per bit limits the radio coverage. In impulse radio the UWB pulses used carry a very little energy since they are extremely short. As a consequence the radio coverage is unacceptable short. A solution to increase the energy per bit is the enlargement of the duration of UWB carrier pulse, however, this solution cannot be used...

Both the peak power and the average power of emission are limited in UWB systems in order to keep the interference caused in an already existing narrowband radio system low enough. It is frequently overlooked that these power limits have to be checked not over the transmitted UWB signal but at the output of a bandpass filter specified in the FCC re...

Since the coherent receivers are not feasible to implement low-cost ultra-wideband (UWB) impulse radio (IR) devices featuring extremely low power consumption, energy detector-based (ED-based) noncoherent receivers are more and more frequently chosen. The Pulse Polarity Modulation (PPM) scheme with a threshold compensated receiver is a promising can...

Transmitted reference (TR) modulation scheme and the autocorrelation receiver offer a simple and robust transceiver configuration for ultra-wideband (UWB) communications. Unfortunately, the TR UWB system has a poor noise performance. The paper shows that the noise performance of a TR autocorrelation system can be improved considerably by placing a...

To satisfy the huge demand for unlicensed handheld wireless networking devices, the Federal Communications Commission (FCC, USA) made the application of ultra-wideband (UWB) technology possible in 2002. Since then an IEEE standard has already been approved for the physical layer of the UWB impulse radio networking devices. Because of the ultra-wide...

Due to their robustness and simple system configurations the transmitted reference (TR) modulation scheme and autocorrelation receiver are preferred candidates for the implementation of cheap ultra wideband (UWB) impulse radio (IR) systems. Unfortunately, the results of simulations and field tests performed on built UWB IR TR systems have shown a r...

In an Ultra-WideBand (UWB) Low-Rate (LR) Wireless Personal Area Network (WPAN) application low-cost, low-power and low-complexity systems are expected to meet the requirements of the typical applications. These demands can only be satisfied by simple modulation schemes and easy to implement noncoherent receiver configurations. However performed fie...

Chaotic signals are ultra-wideband signals that can be generated with simple circuits in any frequency bands at arbitrary power level. The ultra-wideband property of chaotic carriers is beneficial in indoor and mobile applications where multipath propagation limits the attainable bit error rate. Another possible application is the ultra-wideband (U...

A systematic approach for the derivation of UWB detectors cannot be found in the literature. The detectors pub-lished up to now have been developed by inspection, using a heuristic approach. However, that solution prevents the optimiza-tion of UWB detector performance. A new approach is proposed here for the derivation of optimum waveform detectors...

Fourier analyzer concept that generalize the waveform communications to include chaotic carriers can be used to discuss and optimize detection problems. Using this new description it is possible to develop new detector configurations with improved performance for chaotic communications that may be used in ultra-wideband radio (UWB). Radio communica...

Radio communications via channels already occu-pied by conventional telecommunication systems can be estab-lished only by Ultra-WideBand (UWB) radio where the spectrum of transmitted signal covers an ultra-wide frequency band. The power spectral density (psd) of transmitted UWB signal is ex-tremely low and does not cause any noticeable interference...

For lack of empty radio bands, ultra-wideband (UWB) radio that allows the reuse of already occupied frequency bands is the only solution to accommodate new wireless data communication services. The recovery of the very short and extremely wideband wavelets used in UWB radio is not feasi-ble. This is why noncoherent demodulation techniques have to b...

For lack of empty radio bands, ultra-wideband (UWB) radio system allowing reuse of al-ready occupied frequency bands is the only solution to accommodate new wireless data communication ser-vices. Two types of UWB carriers are considered here, the frequency-shifted Gaussian pulse and chaotic signal with FM-DCSK modulation. A generalized model of tra...

In UWB systems three factors have to be consid-ered to design a radio link: (i) peak-and (ii) average power limits defined by FCC Regulations and (iii) low supply voltage available in handheld cheap devices. An exact mathematical model for the interpretation of FCC Regulations is derived. The radio cover-age of UWB networking devices is determined...

Since radio channels available have been assigned to traditional narrowband communication systems the only solu-tion to establish new radio communication links is the frequency reuse. This has to be achieved without causing interference in the conventional radio systems. Ultra WideBand (UWB) radio uses extremely wideband wavelets to decrease the Po...

Data communications is going to wireless everywhere, from computer keyboard to Internet, from sensor networks to embedded systems. The spread of wireless communications is blocked by the fact that the radio channels have been already assigned to conventional communication systems and except a very few and crowded ISM bands there are no empty channe...

Starting from the FCC Regulations and the IEEE UWB standard this contribution derives the required specifica-tions for the blocks of UWB transceivers. It shows that if CMOS technology is used then the coverage of UWB impulse radio is limited by the low supply voltage. To overcome this limit more than one UWB carrier pulse is used to keep transmitte...