Makale Koleksiyonu
https://hdl.handle.net/20.500.12511/4107
Article Collection2024-03-28T11:25:48ZDual-polarized wideband 5G N77 band slotted MIMO antenna system for next-generation smartphones
https://hdl.handle.net/20.500.12511/12393
Dual-polarized wideband 5G N77 band slotted MIMO antenna system for next-generation smartphones
Kiani, Saad Hassan; Münir, Mehr E.; Savcı, Hüseyin Şerif; Rmili, Hatem; Alabdulkreem, Eatedal; Elmannai, Hela; Pau, Giovanni; Alibakhshikenari, Mohammad
In this work, a slotted wideband eight-element multiple-input multiple-output (MIMO) antenna system is presented, which covers the N77 (3.2-4.2 GHz) frequency band. The MIMO antennas are printed on a 0.8-mm-thick FR-4 substrate with dimensions of $150\times75$ mm2. The antennas are placed along the length and width of the printed circuit board (PCB). The arrangement of antenna elements offers pattern and polarization diversity, enhancing the smartphone's ability to receive signals from various directions. The wideband characteristics in the frequency range of 3.25-4.49 GHz are achieved by utilizing a T-slot and an inverted C-slotted stub together. The radiation and total efficiency are found to be >60% for all the MIMO elements. For enhanced isolation between antenna elements placed along the width of the PCB, a slot is introduced, which ensures an isolation of 14.5 dB. This helps achieve an envelope correlation coefficient (ECC) < 0.025, diversity gain (DG) >9.95 dB, and a maximum channel capacity (CC) of 40 bps/Hz. The performance of the MIMO antenna is also assessed in the presence of a human, and comparable results are observed. In addition, the examination of the specific absorption rate (SAR) confirms that it remains well within the safety margins when in proximity to humans.
2024-01-01T00:00:00ZOrthogonal time frequency space multiple access using index modulation
https://hdl.handle.net/20.500.12511/12372
Orthogonal time frequency space multiple access using index modulation
Doğan Tusha, Seda; Tusha, Armed; Althunibat, Saud; Qaraqe, Khalid
Orthogonal time frequency space (OTFS) is a recent two-dimensional modulation technique utilizing delay-Doppler domain and nominated as a promising candidate waveform for beyond 5G communication systems. By leveraging both time and frequency selectivity of doubly-dispersive radio channels, it has shown a better performance compared to traditional schemes. OTFS offers different options for accommodating multiple users on a given resource block. This article introduces a novel OTFS based uplink multiple access scheme by means of index modulation (IM) in delay-Doppler domain. IM based OTFS multiple access (OTFS-IMMA) proposes the coexistence of multiple users over the same delay-Doppler resources. Unlike conventional OTFS multiple access schemes, OTFS-IMMA allows users to employ IM to activate a subset of the available delay-Doppler resources without a coordination by the base station. Although data collision may occur between the users, our analysis shows that the achievable performance is still better than other schemes. Moreover, the proposed OTFS-IMMA scheme paves the way for flexible resource utilization in OTFS-MA to satisfy various users' demands in beyond 5G systems. It has been shown via both mathematical analysis and simulations that the proposed OTFS-IMMA scheme offers significant enhancement not only on bit error rate performance but also on the overall system efficiency. In addition, the achieved performance gain through OTFS-IMMA further increases as the number of channel taps and/or the number of delay-Doppler bins increase.
2023-01-01T00:00:00ZError performance enhancement and complexity reduction in OFDM systems via coordinate interleaving under practical impairments
https://hdl.handle.net/20.500.12511/12349
Error performance enhancement and complexity reduction in OFDM systems via coordinate interleaving under practical impairments
Reşat, Mustafa Anıl; Tusha, Armed; Doğan Tusha, Seda; Özyurt, Serdar; Arslan, Hüseyin
In this work, subcarrier coordinate interleaving (CI) is implemented to orthogonal frequency division multiplexing (OFDM) systems with the aim of both enhancing the error performance and reducing the implementation complexity. To this end, the modulated symbols are independently chosen from a modified M-ary amplitude-shift keying signal constellation under a specific CI strategy. In addition to doubling the diversity level of the original OFDM scheme, the adopted CI approach also drastically reduces the inverse fast Fourier transform (IFFT) size at the transmit side by guaranteeing the first half of the input vector to be identical with the second half at the input to the IFFT block. It is further demonstrated that the proposed system has the ability to enhance the robustness against common practical impairments such as insufficient cyclic prefix and phase noise. The closed-form expression of symbol error probability of the system is derived and confirmed with the simulation results.
2024-01-01T00:00:00ZCyber–physical system architecture of autonomous robot ecosystem for industrial asset monitoring
https://hdl.handle.net/20.500.12511/12343
Cyber–physical system architecture of autonomous robot ecosystem for industrial asset monitoring
Kıvrak, Hasan; Karakuşak, Muhammed Zahid; Watson, Simon; Lennox, Barry
Driven by advancements in Industry 4.0, the Internet of Things (IoT), digital twins (DT), and cyber–physical systems (CPS), there is a growing interest in the digitalizing of asset integrity management. CPS, in particular, is a pivotal technology for the development of intelligent and interconnected systems. The design of a scalable, low-latency communication network with efficient data management is crucial for connecting physical and digital twins in heterogeneous robot fleets. This paper introduces a generalized cyber–physical architecture aimed at governing an autonomous multi-robot ecosystem via a scalable communication network. The objective is to ensure accurate and near-real-time perception of the remote environment by digital twins during robot missions. Our approach integrates techniques such as downsampling, compression, and dynamic bandwidth management to facilitate effective communication and cooperative inspection missions. This allow for efficient bi-directional data exchange between digital and physical twins, thereby enhancing the overall performance of the system. This study contributes to the ongoing research on the deployment of cyber–physical systems for heterogeneous multi-robot fleets in remote inspection missions. The feasibility of the approach has been demonstrated through simulations in a representative environment. In these experiments, a fleet of robots is used to map an unknown building and generate a common 3D probabilistic voxel-grid map, while evaluating and managing bandwidth requirements. This study represents a step forward towards the practical implementation of continuous remote inspection with multi-robot systems through cyber–physical infrastructure. It offers potential improvements in scalability, interoperability, and performance for industrial asset monitoring.
2024-01-01T00:00:00Z