Institute of Advanced Engineering and Science w w w . i a e s j o u r n a l . c o m International Journal of Informatics and Communication Technology (IJ-ICT) Vol.1, No.1, July 2012, pp. 43~53 ISSN: 2252-8776  43 Journal homepage: http://iaesjournal.com/online/index.php/IJICT Uplink and Downlink of LTE-Release 10 in Cellular Communications A.Z.Yonis*, M.F.L.Abdullah** * Departement of Communication Engineering, College of Electronics Engineering, University of Mosul, Iraq ** Faculty of Electrical and Electronic Engineering, University Tun Hussein Onn Malaysia Article Info ABSTRACT Article history: Received June 5 th , 2012 Revised June 10 th , 2012 Accepted July 15 th , 2012 In LTE-Advanced, orthogonal frequency division multiple access (OFDMA) has been selected as the multiple access scheme for downlink and single- carrier frequency division multiple access (SC-FDMA) for uplink. OFDM is an attractive modulation technique in a cellular environment to combat frequency selective fading channels with a relatively low- complexity receiver. However, OFDM requires an expensive and inherently inefficient power amplifier in the transmitter due to the high peak-to-average power ratio (PAPR) of the multicarrier signal. This paper, presents the main components of LTE-Advanced including the all the details of Uplink (SC- FDMA) and Downlink (OFDMA). Also this paper clarifies the main reasons of using SC-FDMA in uplink and using OFDMA in downlink only, in order to obtain flexible mobile communication technology. Keyword: LTE-Advanced SCFDMA OFDMA Copyright © 2012 Institute of Advanced Engineering and Science. All rights reserved. Corresponding Author: A.Z.Yonis, Departement of Communication Engineering, College of Electronics Engineering, University of Mosul Iraq, Mosul, 00964 Email: aws_zuher@yahoo.com 1. INTRODUCTION The LTE-A downlink transmission scheme is based on orthogonal frequency division multiple access (OFDMA), which is a multiuser version of the OFDM modulation scheme. In the uplink, single carrier frequency division multiple access (SC-FDMA) is used, which can be also viewed as a linearly pre- coded OFDM scheme known as discrete Fourier transform (DFT)-spread OFDM. However, SC-FDMA has been selected for the uplink due to the lower peak-to-average power ratio (PAPR) of the transmitted signal compared to OFDM. Low PAPR values benefit the terminal in terms of transmit power efficiency, which also translates into increased coverage. The processing sequence in the signal generation process is quite similar in downlink and uplink, the main difference comes from the elimination of the antenna mapping process and the addition of a DFT-spread block, which is the key process for the PAPR reduction [1]. OFDMA and SC-FDMA are the multiple-access versions of OFDM and a similar modulation scheme, Single-Carrier Frequency-Domain Equalization (SC-FDE). In order to compare the differences between the multiple-access methods, it is important to first cover the differences between their underlying modulation schemes. Section 2 of this paper discusses the current development of LTE-Advanced and the limited research directions related to the development of communication systems, while section 3 describes Long Term Evolution-Advanced downlink which is represent OFDMA. Long Term Evolution-Advanced Uplink is included in section 4 with the block diagram for SC-FDMA. Section 5 explains the downlink data transmission for ODFMA and in section 6 uplink data transmission LTE-Advanced technologies are considered. Section 7 and 8 contain the capacity of OFDMA and SC-FDMA respectively .While section 9 contains the summary and discussions of the main points for this paper which can be consider for reader to