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
Packet  Cost Both  distance vector and link  state  routing  are lowest  algorithms. Tow factors  govern  how  cost is applied to packets  in determines  a route. Cost  is a



Define the Class B Addresses? First two octets are the network number as well as the last two octets are the host number 16382 probable blocks for assignment to organi

Distributed Shared Memory (DSM) systems copy a shared memory abstraction on loosely coupled architectures in order to allow shared memory programming despite missing hardware suppo

The IP class procedure does not split the 32-bit address space into same size class and the classes do not have the same value of networks. A prefix of n bits gives 2n unique ne

Some of the ?elds of IP and ICMP datagrams will be ?xed, some will be settable by the application, and others will computed according to the situation. You must set all ?elds of th

Error Detection- 2D/LRC Adds an additional character (instead of a bit) A block of bits is prearranged in a table The Parity Bit for every data unit is calculate

How many types of twisted pair cable are there We can find two types of twisted pair cables, namely: Unshielded Twisted Pair Cable (UTP) and Shielded Twisted Pair Cable (STP).

Can you give an overview of the components in IPSec?