The advanced notebooks, mobile phones, and Internet applications in today’s world that we use are all entrenched in classical communication bits of zeros and ones. Classical Internet has laid its foundation originating from the amalgamation of mathematics and Claude Shannon’s theory of information. However, today’s Internet technology is a playground for eavesdroppers. This poses a serious challenge to various applications that rely on classical Internet technology, and it has motivated the researchers to switch to new technologies that are fundamentally more secure. By exploring the quantum effects, researchers paved the way into quantum networks that provide security, privacy, and range of capabilities such as quantum computation, communication, and metrology. The realization of Quantum Internet (QI) requires quantum communication between various remote nodes through quantum channels guarded by quantum cryptographic protocols. Such networks rely upon quantum bits (qubits) that can simultaneously take the value of zeros and ones. Due to the extraordinary properties of qubits such as superposition, entanglement, and teleportation, it gives an edge to quantum networks over traditional networks in many ways. At the same time, transmitting qubits over long distances is a formidable task and extensive research is going on satellite-based quantum communication, which will deliver breakthroughs for physically realizing QI in near future. In this paper, QI functionalities, technologies, applications and open challenges have been extensively surveyed to help readers gain a basic understanding of the infrastructure required for the development of the global QI.

In this paper, an X-shaped fractal antenna with defected ground structure (DGS) is presented for multiband and wideband applications. The X shape is used due to its simple design and DGS is utilized to achieve size reduction with multiband and wideband features in the frequency range of 1–7 GHz. The proposed structure is fabricated on FR4 substrate with 1.6 mm thickness. We have proposed two different antennas both are having X-shaped fractal patch with a slotted ground plane to have more impedance bandwidth and better return loss. Various parameters like scale factor, width of ground plane, number of slots with their dimensions and feed line length are optimized to have size reduction and for enhancing the performance of antenna. Reflection coefficient shows the multiband and wideband features of proposed antenna. One of the proposed antennas covers various applications like IEEE802.11y at 3.65 and 4.9 GHz, IEEE 802.11a at 5.4 GHz, 802.11P at 5.9 GHz. Other antenna covers applications like IEEE802.16 at 3.5 GHz; 5 cm band for amateur radio and satellite and future 5 G communication systems over 6 GHz. The antenna designing was done using CST software and simulation results were compared with experimental results (using E5071C network analyzer).

The bit error rate expression of the binary phase‐shift keying modulation scheme has been derived in a frequency selective fading channel for the fractional Fourier transform (FRFT) based orthogonal frequency‐division multiplexing (OFDM) system in the presence of carrier frequency offset (CFO). The performance of the FRFT based OFDM system has been found to be better than FFT‐based OFDM at different values of FRFT angle parameter ‘α’.

Orthogonal Frequency Division Multiplexing (OFDM) has been adopted as a major data transmission technique by many wireless communication standards. Despite its several advantageous features, there are some major issues which should be resolved for getting its full advantages. This paper reviews these concerns of OFDM system in detail and present different available solutions of these problems. This paper gives a great insight of major problems like high peak-to-average power ratio (PAPR) problem, synchronization (time and frequency) problems. This paper also highlights the methods of inter-carrier interference (ICI) reduction available in literature.

In this letter, the performance of uncoded and SFBC OFDM system over two-wave with diffuse power (TWDP) fading environment is analyzed. A general closed-form expressions of average bit error rate (ABER) for both M-ary phase shift keying (MPSK) and M-ary quadrature amplitude modulation (MQAM) are derived using moment generating function (MGF) of TWDP fading distribution. The obtained results are verified with the benchmark results available in literature (i.e., Rayleigh and Rician). Numerical results with various TWDP fading channel parameter (K, ) and with different modulation orders for uncoded and SFBC OFDM systems show excellent agreement with simulation results.