The Importance Of Multicarrier Techniques For A Single...

Chapter 1 Multicarrier techniques This section deals with the importance of multicarrier techniques. 1.1 Multi carrier techniques In a single carrier system, single fade causes the whole data stream and undergo distortion i.e frequency selective fading. The Single carrier systems also suffer with heavy Inter Symbol Interference . In telecommunication Inter Symbol Interference was a form of distortion of signal in which one symbol interferes with the subsequent symbol. Thus it causes an unwanted phenomena as the previous symbols have similar effect as noise thus making communication less reliable . ISI occurs when the signal bandwidth is less than the coherence bandwidth or when the delay spread is greater than symbol duration. To combat the problem multicarrier techniques have been proposed for high data rate transmission. Multicarrier techniques divide the whole bandwidth into large number of narrow band orthogonal subcarriers [1, 2]. Thus the signal bandwidth becomes very less compared with coherence bandwidth ensuring no ISI in time domain and flat fading in frequency domain. Multicarrier systems such as Or thogonal Frequency Division Multiplexing (OFDM) and Multi Carrier Code Division Multiple Access (MC-CDMA) were considered to be the best technologies for 4G wireless communication [1, 2]. Fig. explains the spectrum of multicarrier and single carrier systems. In the single carrier system the information symbols are loaded into one of