Out-of-band radiation and CFO immunity of potential 5G multicarrier modulation schemes

Üçüncü, Ali Bulut
In this study, generalized frequency division multiplexing (GFDM) and windowed cyclic prefix circular offset quadrature amplitude modulation (WCP-COQAM), which are candidate physical layer modulation schemes for the 5G systems, are compared to orthogonal frequency division multiplexing (OFDM) in terms of out-of-band (OOB) radiation levels and carrier frequency offset (CFO) immunity. GFDM and WCP- COQAM are shown to be superior to OFDM with respect to OOB emissions in some studies in literature. However, we consider that these comparisons are made under unfair conditions since OOB reduction techniques are not also applied to OFDM and the spectral efficiencies of the three modulations are not equal. Establishing fair comparison grounds accordingly, the simulation results yielded no significant OOB emission performance difference between the three modulation types. Further simulations considering some parameters related to the transmitted signals such as error-vector magnitude or average power under the effects of amplifier nonlinearity or digital-to- analog converter also revealed no significant difference between the three modulation types under LTE spectral mask requirements. The three modulation types are also compared in terms of their carrier frequency offset (CFO) immunities. To achieve better CFO immunity, advanced pulse shaping methods defined for offset quadrature amplitude modulation OFDM (OQAM- OFDM) are also applied to WCP-COQAM. This is possible since the two modulations are also proved to be equivalent in terms of orthogonality, which is one of the main analytic contributions of this thesis. However, the error rate performance simulations under CFO for various channel conditions did not improve CFO immunity for WCP-COQAM or GFDM compared to OFDM.


Prospects of FMCW-based frequency diverse array radar
Cetiner, Ramazan; Cetintepe, Cagri; Demir, Şimşek; Hizal, Altunkan (2019-11-01)
The linear frequency modulated (LFM) frequency modulated continuous wave (FMCW)-based frequency diverse array (FDA) radar concept is investigated in detail. The radar operates as a linear pulsed FMCW/FDA in the transmission (TX) mode while it operates as a pulsed FMCW/phased array (PA) in the receiving mode. The issues such as low signal-to-noise ratio (SNR) of FDA, the time-angle scanning and time-range ambiguities are studied. It is shown that the local instantaneous frequency bandwidth is much smaller th...
Graph-based joint channel estimation and data detection for large-scale multiuser MIMO-OFDM systems /
Tekin, Şeref Yaşar; Yılmaz, Ali Özgür; Department of Electrical and Electronics Engineering (2015)
In this thesis, a graph-based soft iterative receiver for large-scale multiuser MIMO-OFDM systems is proposed that performs joint channel estimation and data detection over time-varying frequency selective channel. In an uplink scenario, factor graph structures for the transmitter of users and the receiver of base-station are presented, which provide Gaussian message passing between nodes. Instead of LLR, reliability information of symbols are used to decrease complexity of the proposed algorithm. Training ...
Improving the efficiency of microwave power amplifiers without linearity degradation using load and bias tuning in a new configuration
Ronaghzadeh, Amin; Demir, Şimşek; Department of Electrical and Electronics Engineering (2013)
Advanced digital modulation schemes used in the wireless applications, result in the modulated RF signals with high peak to average power ratio which requires linear amplification. On the other hand, the demand for a longer talk time with less battery volume and weight, especially in hand-held radio units, necessitate more power efficient methods to be utilized in power amplifier design. But improved linearity and efficiency have always been contradicting requirements demanding innovative power amplifier and...
Experimental performance evaluation of direction finding by amplitude comparison for GSM applications /
Karadağ, Savaş; Demir, Şimşek; Department of Electrical and Electronics Engineering (2014)
In this thesis, radio direction finding (DF) systems are examined, implementation and measurements for GSM mobile phones are done by using 6-element uniform circular Vivaldi antenna array and uniform circular monopole antenna array which is used asWatsonWatt antenna. Although degrading in performance of DF is expected, only one receiver unit is used in angle-of-arrival (AOA) to measure received signal strength (RSS) from each antenna elements to obtain low cost and small sized set-up. Moreover three di eren...
Testbed implementation of a MIMO-OFDM data link at sub 6 GHz frequency bands using an SDR platform
Tamer, Ufuk; Yılmaz, Ali Özgür; Department of Electrical and Electronics Engineering (2018)
Studies in recent years concentrate on multiple input multiple output (MIMO) systems because of spectral efficiency and diversity advantages. In MIMO systems, a technique called orthogonal frequency division multiplexing (OFDM) is highly preferred since it turns wideband frequency selective channel into narrowband flat channels. Hence, the signal can be represented in time, frequency, and space with MIMO-OFDM. This brings a huge advantage on both multiplexing and diversity. Because of its popularity in the ...
Citation Formats
A. B. Üçüncü, “Out-of-band radiation and CFO immunity of potential 5G multicarrier modulation schemes,” M.S. - Master of Science, Middle East Technical University, 2015.