Reduction of out of band radiation in ofdm system, Computer Networking

THE high spectral efficiency makes OFDM a suitable technology to meet the demands of wireless data traffic. A currently discussed new application are OFDM based overlay systems. In this concept, an overlay system shares the same frequency band with a licensed system by filling existing frequency gaps with OFDM subcarriers. However, OFDM suffers from high out-of-band radiation caused by sidelobes of the modulated subcarriers. Well-known techniques for sidelobe suppression are windowing the transmission (Tx) signal in time domain and the insertion of guard bands. With the former method, the symbol duration is prolonged, whereas with the latter the scarce spectral resources are wasted. Both methods reduce the system throughput and, in general, do not achieve sufficient sidelobe suppression for OFDM based overlay systems. To overcome the drawbacks of the existing techniques for sidelobe suppression we propose the concept of cancellation carriers. The basic idea is to insert a few well-defined subcarriers, referred to as cancellation carriers (CCs), at both sides of the spectrum which are weighted such that their sidelobes cancel the sidelobes of the Tx signal. In, a similar concept based on the insertion of dummy tones has been proposed for amplitude shift-keying modulation in wire line applications. However, these dummy tones are restricted to carry weighted sums of the data on other subcarriers.

 

Posted Date: 3/13/2013 6:27:17 AM | Location : United States







Related Discussions:- Reduction of out of band radiation in ofdm system, Assignment Help, Ask Question on Reduction of out of band radiation in ofdm system, Get Answer, Expert's Help, Reduction of out of band radiation in ofdm system Discussions

Write discussion on Reduction of out of band radiation in ofdm system
Your posts are moderated
Related Questions

Thicknet Characteristics It Supports transmission rates up to 10 Mbps in Baseband mode Less expensive in comparison of fiber-optic cable however more expensive than ot

What are the Access methods used in LAN: i. Switched access: It is used in LANs which are assigned around CBXs. Electronic switching is techniques are used to provide access

Convergence time is slower for Distant Vector routing and is faster for Link State routing.

State the Security concerns The history of security concerns is not new. They have been of great worry to man and for many centuries man has been endeavouring to devise new tec

Question : a) Explain why pervasive computing can be termed as a "technology that disappears". b) List and briefly explain four main components of a MOTE used in Wireless

VLAN ( Virtual Local Area Network) is a concept of creating distinct broadcast domains. It is a network which aims at partitioning the physical network. VLAN comprises all the attr

Responsibility of Application Layer

Functions and features of the IPMonitor program are as follows:   a)  This program should be able to list out detail information of IP traffic which includes source IP address an

What is a dedicated server? A network server designated to provide one particular service is known as dedicated server. For example if a computer is assigned for database servi