International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395 -0056 Volume: 03 Issue: 04 | Apr-2016 www.irjet.net p-ISSN: 2395-0072 © 2016, IRJET ISO 9001:2008 Certified Journal Page 665 OFDM: Comparison with Multicarrier Techniques and Applications Jaipreet Kaur 1 , Hardeep Kaur 2 , Manjit Sandhu 3 1 Deptt. of ECE, Guru Nanak Dev University, Regional Campus Sathiala, jaipreet.ecesathiala@gndu.ac.in 2 Deptt. of Electronics Technology, Guru Nanak Dev University, Amritsar, hardeep.gndu@gmail.com 3 Deptt. of ECE, Guru Nanak Dev University, Regional Campus Sathiala, manjit_sandhu67@yahoo.com ---------------------------------------------------------------------***----------------------------------------------------------------- Abstract –Orthogonal Frequency Division Multiplexing (OFDM)is the promising candidate of a multiple carrier modulation technique because it does not require equalizers. OFDM is robust in adverse channel conditions and allows a high level of spectral efficiency. It effectively mitigates performance degradations due to multipath and is capable of combating deep fades in part of the spectrum. Orthogonal Frequency Division Multiplexing (OFDM) is an emerging multi-carrier modulation scheme, which has been adopted for several wireless standards such as IEEE 802.11a and HiperLAN2.In this paper, the comparison between other carriertechniques like single carrier transmission, multi carrier transmission, conventional multi carrier technique, CDMA, TDMA, FDMA. The wireless communication broadcasting, WLAN, WMAN who are implemented OFDM are detailedand compared here. The advantages and disadvantages of OFDM are discussed in this paper. Key Words:OFDM, CDMA, FDMA,TDMA, Broadcasting, WLAN, WMAN. 1. INTRODUCTION The demand for high data rate services has been increasing very rapidly and there is no slowdown in sight. Currently Global System for Mobile telecommunications (GSM) technology is being applied to wireless phone systems. But, GSM uses time division multiple access (TDMA), which has a high symbol rate leading to problems with multipath causing inter-symbol interference. Several techniques are under consideration for the next generation of digital phone systems, with the aim of improving cell capacity, multipath immunity, and flexibility.[1,2] These include CDMA and OFDM. In the beginning of 3G (Third Generation) era, CDMA technique was widely employed for most systems. Buttheir capability of supporting much higher data rate is limited. This is because they use multiple codes simultaneously, which may result in self-interference. So B3G (Beyond 3G), OFDM is used instead of CDMA. In IEEE802.11 series, the low date rate is working on CDMA (802.11b) but high date rate uses OFDM (802.11g and 802.11a). WiMAX is also using OFDM. OFDM is currently being used in several new radio broadcast systems including high definition digital television (HDTV) and digital audio broadcasting (DAB). A research has been done into the use of OFDM as a transmission method for mobile telecommunications systems. [5] 2. COMPARISON BETWEEN OTHER TECHNIQUES 2.1. Single carrier transmission In single carrier transmission, all data is sending on a single channel with very high data rate. The transmitted symbols are pulse formed by a transmitter filter. After passing the multipath channel in the receiver a matched filter is used to maximize signal to noise ratio. The system is characterized by the following conditions:  Transmission Rate: R= 1/T  Maximum channel delay: Td For the single carrier system this results in an ISI of: Td / T. The complexity involved in removing this interference in the receiver is tremendous. This is the main reason why the multi carrier approach has become so popular. [4] Fig-1:Basic structure of a single carrier system[4]