NOVEL MULTIPLE LEVEL SUBCARRIER ALLOCATION SCHEME IN SC-FDMA FOR LTE-A UPLINK

2016 ◽  
Vol 78 (8) ◽  
Author(s):  
Mohamed Melood A. Abdased ◽  
Mahamod Ismail ◽  
Rosdiadee Nordin
Keyword(s):  
Multiple Access ◽  
Average Power ◽  
Frequency Division ◽  
Robust Performance ◽  
Frequency Allocation ◽  
Single Carrier ◽  
Term Evolution ◽  
Lower Complexity ◽  
Papr Performance

Long Term Evolution-Advanced (LTE-A) uses Single-Carrier Frequency Division Multiple Accesses (SC-FDMA) for uplink, because it has robust performance against the Peak Average Power Ratio (PAPR), compared to Orthogonal Frequency Division Multiple Access (OFDMA). SC-FDMA schemes include Interleaved FDMA (IFDMA) and Localized FDMA (LFDMA), both of which are commonly practiced in LTE-A uplink. IFDMA allocates distributed frequency carriers for users, whereas LFDMA allocates localized frequency carriers for users. The frequency allocation in an IFDMA scheme exhibits better PAPR performance, whereas the advantage of LFDMA is its lower complexity requirements. In this paper, a new scheme is introduced that integrates IFDMA and LFDMA by using a variable interleave allocation of subcarriers in the bandwidth. Here, Generalized Interleaved Frequency Division Multiple Accesses (GIFDMA), is used as a master key that controls the allocation for interleaved and localized FDMA, also known as L/I FDMA. This integration of IFDMA and LFDMA has been derived theoretically and empirically. Simulations are conducted to investigate the effect of different parameters on the GIFDMA PAPR performance, which is compared to that of conventional IFDMA and LFDMA. The simulation results revealed that the proposed GIFDMA provides PAPR performance comparable to that of both LFDMA and IFDMA.

scholarly journals Investigation on the PAPR performance of odd-bit QAM constellations for DFT spread OFDM systems

2021 ◽  
Vol 21 (2) ◽  
pp. 1005
Author(s):  
Ahmed M. Sana ◽  
Amer T. Saeed ◽  
Yaseen Kh. Yaseen
Keyword(s):  
Communication Systems ◽  
Adaptive Modulation ◽  
Average Power ◽  
Transmission Efficiency ◽  
Distribution Functions ◽  
Cumulative Distribution ◽  
Ofdm Systems ◽  
Single Carrier ◽  
Papr Performance

<p>Adaptive quadrature amplitude modulation (QAM) is a crucial scheme that enables the modern communication systems to overcome the adverse effects of channel fluctuations and maintain an acceptable spectral efficiency. In order to enhance adaptive modulation even further, adoption of odd-bit QAM constellations alongside even constellations had been suggested to improve the transmission efficiency of adaptive QAM modulation. Hence, odd-bit QAM had been extensively studied, analyzed, and tested by many researchers for various patterns, sizes, and communication systems in terms of bit error rate (BER) and peak to average power ratio (PAPR). However, the PAPR performance of odd-bit QAM constellation with single carrier transmission systems adopted in the uplink of the 4G long term evolution (LTE) standards caught almost no research interest. In this paper, the PAPR performance of both cross and rectangular odd-bit QAM constellations are investigated for DFT-S-OFDM systems. Complementary cumulative distribution functions (CCDFs) and probability density functions (PDFs) curves for PAPR are also obtained. Finally, an equation for PAPR PDF is empirically derived for odd-bit cross QAM based DFT-S-OFDM. The results show that cross odd-bit QAM outperforms the rectangular odd-bit QAM in terms of PAPR by 1.02 dB for 8-QAM and 1.3 dB for 32-QAM. This proves that cross odd-bit QAM is a better choice in terms of PAPR for DFT-S-OFDM systems. </p>

Next Generation Wireless Multiple Access Technology OFDMA and SC - FDMA Performance Analysis

2013 ◽  
Vol 336-338 ◽  
pp. 1670-1675
Author(s):  
Lin Wan
Keyword(s):  
Multiple Access ◽  
System Capacity ◽  
Frequency Division ◽  
Theoretical Derivation ◽  
Access Technology ◽  
Single Carrier ◽  
Access Scheme ◽  
Basic Performance ◽  
Better Than

orthogonal frequency division multiple access (OFDMA) and single carrier frequency division multiple access (SC - FDMA) are the two kinds of 4 g wireless multiple access scheme. In the long term evolution (LTE) downlink link access scheme based on OFDMA, at the same time, the uplink access scheme based on SC - FDMA. In this article, we deduced the OFDMA and SC - FDMA basic performance difference, and then demonstrates the comprehensive performance comparisons between them. Theoretical derivation results show that the system capacity is better than that of SC - FDMA OFDMA. Then, we use the numerical simulation results confirm the conclusion. Keywords: OFDMA SC - FDMA basic capacity of the uplink transmission

scholarly journals Estimation Techniques for MIMO-OFDM-A Review

2021 ◽  
pp. 409-414
Author(s):  
Varsha Yadav ◽  
Prashant Garg
Keyword(s):  
Power Efficiency ◽  
Multiple Access ◽  
Average Power ◽  
Frequency Division ◽  
Mobile Terminals ◽  
3Gpp Lte ◽  
Synchronization Errors ◽  
Single Carrier ◽  
Moderate Power ◽  
Code Division Multiple

In the context of Third-Generation Partnership Project Long-Term Evolution (3GPP LTE), the target data rates are 100 Mb/s in downlink and 50 Mb/s in uplink, and other system features include flexible bandwidths and moderate power consumption of mobile terminals. While the previous 3GPP generations, namely, 3G UMTS and 3.5G HSPA, rely on code-division multiple access (CDMA), LTE adopts orthogonal frequency-division multiple access (OFDMA)-based technologies for its uplink and downlink. Due to high peak-to-average power ratio (PAPR) of OFDMA signals, the single- carrier frequency division multiple access (SC-FDMA), also known as discrete Fourier transform (DFT)-spread OFDMA, has been selected for the uplink transmission in 3GPP LTE systems. SC-FDMA has similar throughput performance as OFDMA but with lower PAPR to increase power efficiency and is less sensitive to frequency synchronization errors, which makes it favorable for mobile terminals.

scholarly journals Matched Filter Based Spectrum Sensing Technique for 4G Cellular Network

2019 ◽  
Vol 38 (4) ◽  
pp. 973-978
Author(s):  
Shadab Kalhoro ◽  
Fahim Aziz Umrani ◽  
Mustahsan Khanzada ◽  
Liaquat Ali Rahoo
Keyword(s):  
Spectrum Sensing ◽  
Multiple Access ◽  
Matched Filter ◽  
Research Work ◽  
Energy Detection ◽  
Secondary Users ◽  
Single Carrier ◽  
Term Evolution ◽  
Theoretical Results

Modern and fast developments of wireless technologies have directed to a great demand for resources. It can be seen in the study that the range of existing spectrum is not used effectively, therefore the frequency band should be observed to ensure proper usage and to have the information of primary or licensed user is very much essential. In this research work uplink of LTE (Long-Term Evolution) is observed through MF (Matched Filter) spectrum sensing technique of CR (Cognitive Radio) network. This method examines the existence of signals in minimum possible time, reduces the hindrances between secondary users, increases accurateness of sensing and provides finest choice of threshold. In Uplink the System model which is used is known as SC-FDMA (Single Carrier Frequency Division Multiple Access). Entire simulation/results are prepared in MATLAB environment. This study also provides graphical contrast of simulated and theoretical results of matched filter and energy detection technique.

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