Direction-of-arrival (DOA) estimation is very useful in many positioning applications and has been well studied verified via computer simulation. The main contribution of this work to design implement a real-time DOA estimator on software defined radio (SDR) platform. Because the RF receivers SDR platform are phase incoherent, requires calibration scheme avoid errors due differences between receivers. tested microwave anechoic chamber. Experimental measurements show that implemented can...

This paper presents a new design of an enhanced passive tag (EPT) that can extend the read range EPCglobal class-1 Generation-2 by attaching battery-assisted circuit (BAC) to integrated circuit. The BAC generates low-power unmodulated continuous wave with frequency outside operating band supply additional power tag. Empirical results demonstrate prototype EPT has much longer and is more resistant multipath fading than regular generation-2 Unlike semipassive depends on its local battery work,...

This study proposes a new joint direction of arrival (DOA) and time (TOA) estimation (JDTE) scheme for multi-band orthogonal frequency-division multiplexing (MB-OFDM) ultra-wideband systems with two-antenna receiver based on frequency-domain processing. Prior TOA DOA (JTDE) schemes first measure the TOAs from received waveforms at all antennas then obtain measurements. The proposed JDTE method estimates parameters directly antennas, where channel frequency response associated two antenna...

Performance degradation caused by multipath fading channel was investigated in a passive UHF RFID system. The problem is often mitigated using diversity combining techniques. In this letter, novel dual-antenna tag with polarization-time coded backscatter proposed. An system such kind of tags can use polarization technology to overcome the problem. proposed coding scheme not only lowers corresponding design complexity, but also effectively reduces detection errors modulated signal. Empirical...

A passive RFID tag derives its power from RF signal emitted by a reader and responds modulated backscatter signals to the reader. Because of large propagation loss, accessible range is hence limited. In addition, readability often influenced multipath fading problems. order mitigate problems, multi-carrier UHF system utilizes isolated sources which provide additional tags via carrier frequency different with operating frequencies. This approach however affects command demodulation circuit...

Abstract In this article, a beam‐switching array antenna system is devised to estimate the direction‐of‐arrival (DOA) of radio frequency (RF) signals.The contains 16 patch antennas arranged as uniform circular array. operation, four adjacent elements are connected RF tuners via switches create directive beam. By reconfiguring switch setups, rotating beam produced cover azimuth plane. The angle an incoming signal estimated by processing received strengths from setups curve‐fitting technique....

Radio frequency identification technology (RFID) is an essential in the realm of Internet things (IoT). One interesting topic IoT research to detect location object interest (OoI). An with attached RFID tag can be localized via determining backscatter signal source its associated tag. Various localization schemes have been proposed. With knowledge direction (ToI) helpful estimate ToI. This work presents new measurement results and some experimental angle arrival (AoA) estimation a commercial...

The “Gen2” specification for UHF passive RFID systems released by EPCglobal has become an intense research interest. A Gen2 tag derives its power from the RF wave emitted a reader and responds modulated backscatter signals to reader. Due large propagation loss, accessible range of is hence limited. Moreover, readability often influenced multipath fading problem. In order mitigate problems, multi-carrier system utilizing frequency diverse ability proposed in prior work. this work, thorough...

The "Gen2 " specification for UHF passive RFID system released by EPCglobal has become an intense research interest. A Gen2 tag derives its power from the RF wave emitted a reader and responds modulated backscatter signals to reader. Due large propagation loss, accessible range of is hence limited. Moreover, readability often influenced multipath fading problem. In this paper we propose multi-carrier that can effectively extend tag. addition, investigate multi-band property tags, which be...

The tag collisions result in lengthy inventory processes and incorrect identification problems a RFID system. EPCglobal Generation-2 (Gen2) specification proposes framed slotted ALOHA based anti-collision protocol, named slot-count algorithm or Q-algorithm, for UHF passive systems. In order to optimize the performance of frame size Q-algorithm determined by value (Q) needs be updated iteratively according number accessible tags. A Q selection scheme is addressed specification, which...

This work presents a new approach to airborne target localization in passive radar system. Using joint time-difference-of-arrival (TDOA) and direction-of-arrival (DOA) technique, each receiver is capable of estimating both TDOA DOA information far distant signal source. method uses the Ambiguity Function detect time delay between direct reflected multiple signals classification (MUSIC) algorithm estimate incident angle by target. can successfully localize that 70km away from receiver....

In this work, a 360 degrees direction-of-arrival (DOA) estimator using array switching technique is implemented on software defined radio (SDR) platform. The includes square antenna comprising 16 dipole antennas, which segmented as four 4-element uniform linear arrays (ULA). All elements are connected to RF switches and then receivers. By configuring the switch status via radio, one of ULA activated for DOA estimation multiple signal classification algorithm. well-known inaccurate near...

The applications of location-based service (LBS) grow rapidly and draw significant research attention recently. As the advance localization technology, not only LBS can be applied outdoors but also in indoor environments with abundant multipath channels. Angle-of-Arrival (AOA) estimation is a vital technology for signal source localization; however, its accuracy significantly affected by propagation. Ultra-Wideband (UWB) as one promising short-range communication technologies has been used...

Using an RFID reader to estimate angle-of-arrival (AoA) of a passive UHF tag backscatter signal has been extensively studied; however using AoA information multiple signals simultaneously is scant in literatures. This work presents experimental results simultaneous estimation two commercial tags receiver with four-element uniform linear array. The show that can be accurately estimated subspace-based methods without spatial smoothing processing. useful for localization applications and the...

A signal subspace‐based technique was used to estimate joint angles of departure (AODs) and arrival (AOAs) in an overloaded bistatic multiple‐input multiple‐output (MIMO) radar system. First, a spatial‐temporal scheme is expand the degrees freedom array. Thus, number target AODs AOAs that can be estimated higher than product transmit receive elements. The steering vectors are then obtained from eigenvectors, which contain spatial temporal information received signals. This enables highly...

Ultra-high frequency (UHF) multiple input output (MIMO) passive radio identification (RFID) systems have attracted the attention of many researchers in last few years. The system modeling and theoretical performance analysis these been well investigated revealed studies, yet prototype corresponding experimental results are scarce. In this study, measurements a 1 × 2 UHF RFID system, including MIMO tag its software-defined radio-based reader, taken microwave anechoic chamber, presented....

A multi-carrier UHF RFID system provides the required power of a passive tag via multiple carriers. It is proved that method can effectively extend access range since operating almost always satisfied. However, extension confined due to waveform distortion reader command at tag's demodulator. This work discusses this problem and proposes solution by adding an additional bandpass filter before envelope detector. Computer simulation results show proposed mitigates demodulation problem.