| 1. |
- Aghazadeh, S. R., et al.
(author)
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A 3-5-GHz, 385-540-ps CMOS true time delay element for ultra-wideband antenna arrays
- 2022
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In: AEU - International Journal of Electronics and Communications. - : ELSEVIER GMBH. - 1434-8411 .- 1618-0399. ; 149
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Journal article (peer-reviewed)abstract
- This paper proposes an all-pass filter-based true time delay (TTD) element covering a 3-5-GHz ultra-wideband (UWB) frequency. The proposed TTD element designed in a standard 0.18-mu m CMOS technology achieves a tunable delay range of 385-540 ps with 6-ps delay steps and maximum 11% absolute delay error over a 3-5-GHz frequency band. It exhibits an average 3.6-4.6-dB noise figure (NF) within the whole bandwidth. A four-channel beamforming receiver realized by the proposed TTD element is designed and examined in this paper, as well. With the maximum delay of 540 ps and 6-ps average delay resolution, a maximum steering angle of +/- 45 degrees with 5 degrees (18 steps) steering resolution is demonstrated for the beamforming receiver with 2-cm antenna spacing.
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| 2. |
- Aslam, Bilal, et al.
(author)
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Low-profile magnetically coupled dual resonance patch antenna for UHF RFID applications
- 2021
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In: AEU - International Journal of Electronics and Communications. - : Elsevier BV. - 1434-8411 .- 1618-0399. ; 133
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Journal article (peer-reviewed)abstract
- A novel low-profile metal mountable UHF RFID tag antenna is presented. The tag antenna design consists of two resonating patches with different resonant frequencies fed through a joint inductive loop. This design topology offers benefits such as bandwidth enhancement in the single band and the possibility of attaining a tunable dualband coverage in the UHF RFID band. The proposed antenna structure doesn't require any electrical connection (shorting pins/shorting plates/via holes) and therefore facilitates fabrication through a conventional RFID inlay manufacturing process. Fabrication and testing of a prototype of the proposed antenna design are carried out. The prototype antenna achieves free space and an on-metal reading range of better than 8 m and 11 m respectively in the US RFID band of 902-928 MHz.
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| 3. |
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| 4. |
- Cao, Zhanghua, et al.
(author)
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Secure random linear network coding on a wiretap network
- 2015
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In: AEU - International Journal of Electronics and Communications. - : Elsevier BV. - 1434-8411 .- 1618-0399. ; 69:1, s. 467-472
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Journal article (peer-reviewed)abstract
- We develop a secure random linear network coding scheme on wiretap networks where a wiretapper can only eavesdrop on a limited number of channels. On one hand, by refining Lima's "locked coefficients" method and applying the approach of one-time pad, our scheme can well protect message packets without decreasing network throughput. On the other hand, by treating ciphertext as noisy symbols, inspired by the physical layer technique, and applying Shamir's secret sharing scheme, our scheme can successfully protect secret random seed without any forms of key exchange or secret channels. Compared to existing schemes, our scheme has minimum information overhead, independency of hash functions, and no restriction on global encoding kernel. Finally, we analyze the computational complexity of our proposed scheme and rigorously prove that our scheme can achieve secure network communication. (C) 2014 Elsevier GmbH. All rights reserved.
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| 5. |
- Chedid, Michel, 1977-, et al.
(author)
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Realization of an active inductance for a low power high bandwidth DC power line communication network transceiver
- 2010
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In: AEU - International Journal of Electronics and Communications. - : Elsevier. - 1434-8411 .- 1618-0399. ; 64:10, s. 947-952
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Journal article (peer-reviewed)abstract
- An active inductor based on an improved gyrator circuit is proposed. The active inductor is developed to be implemented in a high impedance transceiver for a wearable DC power line communication network where requirements such as low power consumption, high bandwidth and numerous nodes support are prioritized. A load isolation step is introduced to ensure the stability of the active inductance's size on different load currents. The proposed gyrator circuit is analyzed and optimized by means of theoretical calculations. The theoretical results are then verified by simulations and experiments in the frequency range up to 10MHz.
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| 6. |
- Dong, X., et al.
(author)
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Impact of Doppler spread and adaptive modulation on TCP throughput in Rayleigh fading channels
- 2010
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In: AEU - International Journal of Electronics and Communications. - : Elsevier BV. - 1434-8411 .- 1618-0399. ; 64:11, s. 1082-1089
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Journal article (peer-reviewed)abstract
- A number of wireless systems have recently adopted adaptive modulation (AM) schemes to improve its efficiency. In this letter, our aim is to study the impact Doppler spread and adaptive modulation has on transmission control protocol (TCP) throughput in Rayleigh fading channels. We consider a finite state Markov channel (FSMC) model, which is a useful model for analyzing radio channel with nonindependent fading. Furthermore, we use a Markov model for TCP evolution and evaluate the TCP performance by computer simulations. In our simulations we have compared the TCP Reno scheme with TCP Tahoe scheme. The results indicate that a large Doppler spread leads to lower TCP throughput due to more frequent transitions of channel states and modulation schemes which make it difficult for the TCP congestion control mechanism to accommodate the dynamic link characteristics.
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| 7. |
- Durisi, Giuseppe, 1977, et al.
(author)
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High-SNR Capacity of Wireless Communication Channels in the Noncoherent Setting: A Primer
- 2011
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In: AEU - International Journal of Electronics and Communications. - : Elsevier BV. - 1434-8411 .- 1618-0399. ; 65:8, s. 707-712
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Journal article (peer-reviewed)abstract
- This paper, mostly tutorial in nature, deals with the problem of characterizing the capacity of fading channels in the high signal-to-noise ratio (SNR) regime.We focus on the practically relevant noncoherent setting, where neither transmitter nor receiver know the channel realizations, but both are aware of the channel law.We present, in an intuitive and accessible form, two tools, first proposed by Lapidoth & Moser (2003), of fundamental importance to high-SNR capacity analysis:the duality approach and the escape-to-infinity property of capacity-achieving distributions.Furthermore, we apply these tools to refine some of the results that appeared previously in the literature and to simplify the corresponding proofs.
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| 8. |
- Emadeddin, Ahmad, et al.
(author)
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Coupling reduction in an active highly integrated Tx phased array antenna with scanning capability
- 2023
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In: AEU - International Journal of Electronics and Communications. - : Elsevier BV. - 1434-8411 .- 1618-0399. ; 169
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Journal article (peer-reviewed)abstract
- This paper presents a novel method for analyzing and reducing the total coupled power in the Active Highly Integrated Phased Array Antennas (AIPAA), incorporating both the nonlinear impacts of the power amplifier (PA) transfer functions and the normalized scattering matrix. The proposed method introduces a new degree of freedom to reduce the coupling level utilizing two key factors: (i) the balance between the PAs’ transfer function gain and the coupled power difference to the PAs’ gate and drain/antenna ports, and (ii) the out-of-phase sum based on PAs’ transfer function phase response. The proposed method is theoretically demonstrated by accounting for all tones and also is subsequently simplified for the main tone. The method is practically validated by applying the method to a 1 × 5 AIPAA structure to reduce the total coupled power at its drain/antenna port. The results demonstrate a coupling reduction of −5 dB as an average with a maximum reduction of −20 dB, over a scan coverage of ±30∘ and 10% fractional bandwidth at 22 GHz for the center cell.
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| 9. |
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| 10. |
- Iqbal, Amjad, et al.
(author)
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SIW-based frequency-adjustable antenna for IoT-based duplex wireless devices
- 2024
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In: AEU - International Journal of Electronics and Communications. - München : Elsevier. - 1434-8411 .- 1618-0399. ; 173
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Journal article (peer-reviewed)abstract
- This paper proposes a compact and frequency-adjustable/reconfigurable dielectric (DR)-loaded eighth-mode substrate integrated waveguide (EMSIW) antenna for duplex wireless communications. The miniaturization of the resonators is realized using a rectangular slot and high isolation is achieved by keeping a reasonable space between them. The proposed design is simulated using a three-dimensional (3D) full-wave simulator, then analysed with a circuit model and finally validated experimentally. Frequency-reconfigurability in the suggested antenna is achieved by placing DRs with different permittivities in the designated holes that are realized in the open-ended portion of each resonator. Consequently, the lower- and high-resonant bands can be reconfigured from 4.70 to 5.23 GHz and from 5.55 to 6.34 GHz, respectively. It is worth mentioning that both resonant band can be independently reconfigured. Moreover, the inter-resonator coupling is always lower than −23.5 dB in the bands of interest. Furthermore, the peak realized gains are always greater than 4.7 dBi in the lower frequency band and 5.5 dBi in the higher one. The suggested antenna has stable radiation properties in both bands in all frequency ranges. Hence, this design is suitable for compact reconfigurable devices due to its compactness, large frequency ranges, stable radiation patterns, and high isolation. © 2023 Elsevier GmbH
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