scholarly journals Digital multicarrier modulation techniques for high data rates multimedia applications in present and future wireless communication systems

2013 ◽  
Vol 8 (4) ◽  
pp. 23-29
Author(s):  
Rabindra Bhojray ◽  
2021 ◽  
Vol 42 (4) ◽  
pp. 357-370
Author(s):  
M. A. Salhi ◽  
T. Kleine-Ostmann ◽  
T. Schrader

AbstractIncreasing data rates in wireless communications are accompanied with the need for new unoccupied and unregulated bandwidth in the electromagnetic spectrum. Higher carrier frequencies in the lower THz frequency range might offer the solution for future indoor wireless communication systems with data rates of 100 Gbit/s and beyond that cannot be located elsewhere. In this review, we discuss propagation channel measurements in an extremely broad frequency range from 50 to 325 GHz in selected indoor communication scenarios including kiosk downloading, office room communication, living rooms, and typical industrial environments.


2019 ◽  
Vol 2019 ◽  
pp. 1-9 ◽  
Author(s):  
Hamsakutty Vettikalladi ◽  
Waleed Tariq Sethi ◽  
Ahmad Fauzi Bin Abas ◽  
Wonsuk Ko ◽  
Majeed A. Alkanhal ◽  
...  

Terahertz (THz) links will play a major role in high data rate communication over a distance of few meters. In order to achieve this task, antenna designs with high gain and wideband characteristics will spearhead these links. In this contribution, we present different antenna designs that offer characteristics better suited to THz communication over short distances. Firstly, a single-element antenna having a dipole and reflector is designed to operate at 300 GHz, which is considered as a sub-terahertz band. That antenna achieves a wide impedance bandwidth of 38.6% from 294 GHz to 410 GHz with a gain of 5.14 dBi. Secondly, two designs based on the same dipole structure but with added directors are introduced to increase the gain while maintaining almost the same bandwidth. The gains achieved are 8.01 dBi and 9.6 dBi, respectively. Finally, an array of 1×4 elements is used to achieve the highest possible gain of 13.6 dBi with good efficiency about 89% and with limited director elements for a planar compact structure to state-of-the-art literature. All the results achieved make the proposed designs viable candidates for high-speed and short-distance wireless communication systems.


2018 ◽  
Vol 0 (0) ◽  
Author(s):  
Akshita Parmar ◽  
Abhishek Sharma ◽  
Chandni Guleria

AbstractOptical wireless communication is one of the emerging technologies. Over the last few years it has been the growing interests which have some indoor and outdoor applications. The demand for wireless communication has been growing day-by-day. With radio spectrum, there are some problems related to congestion, limitations on bandwidth as the number of users are increasing day-by-day. As a result, optical wireless communication systems are been used which provides high data rates, much higher bandwidth, unregulated spectrum and highly secured networks. In this paper a review is done on optical wireless communication. Various fields and applications are discussed like under water, space, aircrafts, light fidelity (Li-Fi), etc. Different light sources, coding schemes, modulation techniques are discussed. Also some of the challenges are discussed here.


2019 ◽  
Vol 0 (0) ◽  
Author(s):  
Ahmed Nabih Zaki Rashed

AbstractThis study has presented the complete comparison non return to zero (NRZ) and return to zero (RZ) modulation techniques for upgrading long haul optical wireless communication systems. Electrical signal to noise ratio is measured. Q-ranges factor are measured at the receiver side for different transmission distance from 500 to 1000  km. As well as the performance parameters of optical wireless communication systems are estimated at different transmission data rates with possible maximum transmission distance. NRZ modulation technique has outlined better performance than RZ modulation technique for upgrading optical wireless communication systems.


Author(s):  
Costas Chaikalis ◽  
Felip Riera-Palou

Modern and future wireless communication systems such as UMTS and beyond 3G systems (B3G) are expected to support very high data rates to/from mobile users. This poses important challenges on the handset design as they should be able to attain an acceptable operating bit error rate (BER) while employing a limited set of resources (i.e. low complexity, low power) and often, with tight processing delay constraints. In this chapter we study how channel decoding and equalisation, two widely used mechanisms to combat the deleterious channel effects, can be made adaptable in accordance to the instantaneous operating environment. Simulation results are given demonstrating how receiver reconfigurability is a promising method to achieve complexity/delay efficient receivers while maintaining prescribed quality of service (QoS) constraints.


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