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Multicarrier Modulation Schemes—Candidate Waveforms for 5G
Published in Athanasios G. Kanatas, Konstantina S. Nikita, Panagiotis Mathiopoulos, New Directions in Wireless Communications Systems, 2017
Konstantinos Maliatsos, Athanasios G. Kanatas
where pm,m=0,...,ν is the channel impulse response and s−ν,...,s−1 are the guard interval samples. In OFDM, the guard interval is called cyclic prefix, that is, the OFDM symbol is cyclicly extended. Thus, the cyclic prefix is given by () s−l=sN−ll=1,...,ν
Introduction to Broadband Wireless Networks
Published in Amitabh Kumar, Mobile Broadcasting with WiMAX: Principles, Technology, and Applications, 2014
The WLAN systems (802.11x) are intended for communications over short distances. This is reflected in the symbol times and guard times for these systems. For example, in 802.11a, the symbol duration is 3.2 μs and the guard interval is 0.8 μs. These values tailor well with the indoor environment and short delays. On the other hand, in Fixed WiMAX the same are 64 μs symbol time and 8 μs guard band. This gives the WiMAX system the capability to operate over large distances and still be able to manage the reflected signals within the guard band so that it does not interfere with the next symbol.
Block Transmission Techniques
Published in Paulo Montezuma, Fabio Silva, Rui Dinis, Frequency-Domain Receiver Design for Doubly Selective Channels, 2017
Paulo Montezuma, Fabio Silva, Rui Dinis
Consequently, the guard interval is a copy of the final part of the OFDM symbol which is added to the beginning of the transmitted symbol, making the transmitted signal periodic. The cyclic prefix, transmitted during the guard interval, consists of the end of the OFDM symbol copied into the guard interval, and the main reason to do that is on the receiver that integrates over an integer number of sinusoid cycles each multipath when it performs OFDM demodulation with the FFT [12]. The guard interval also reduces the sensitivity to time synchronization problems.
Novel Adaptive Filter Design for Filter Bank Multicarrier System Under Doubly Dispersive Channel Conditions
Published in IETE Journal of Research, 2018
Arunprakash Jayaprakash, G. Ramachandra Reddy
Due to ever-increasing data traffic volume, the technological attention is shifting from the fourth-generation, long-term evolution standards to future fifth-generation (5G) technologies. The 5G systems are expected to provide high throughput at very low latency, high spectral efficiency, giga-bit-data rate under increased data-traffic demand, etc. at low cost and reduced power consumption. Due to various advantages like high data rate transmission, robustness against inter symbol interference (ISI) and easy generation by fast Fourier transform, orthogonal frequency division multiplexing (OFDM) has been the favourite among orthogonal multicarrier communication techniques [1,2]. But there exist certain areas where OFDM fails to be the best choice to provide optimum spectral efficiency and link reliability, especially for communication under doubly dispersive channels. OFDM uses a guard interval called cyclic prefix in order to combat ISI, which reduces the throughput of the system. Under fast fading frequency-dispersive channels, the Doppler shift causes frequency offsets, which in turn result in inter carrier interference (ICI). The rectangular filter, which is the prototype filter in OFDM, causes spectral leakage to adjacent subcarriers, which ultimately leads to ICI. Since there is a need to improve the next-generation wireless access capacity and flexibility, filter bank multicarrier (FBMC) promises to be a better alternative than other multicarrier communication techniques [3–9]. In order to combat the detriments of OFDM, FBMC is considered in the next generation beyond OFDM multicarrier standards, especially as the potential waveform candidate for 5G systems. The performance of FBMC in WiMAX and beyond 3G context is studied in [10–15].