Change search
ReferencesLink to record
Permanent link

Direct link
Peak to Average Ratio Reduction in Wireless OFDM Communication Systems
Blekinge Institute of Technology, School of Engineering, Department of Signal Processing.
2006 (English)Independent thesis Advanced level (degree of Master (One Year))Student thesis
Abstract [en]

Future mobile communications systems reaching for ever increasing data rates require higher bandwidths than those typical used in today’s cellular systems. By going to higher bandwidth the (for low bandwidth) flat fading radio channel becomes frequency selective and time dispersive. Due to its inherent robustness against time dispersion Orthogonal Frequency Division Multiplex (OFDM) is an attractive candidate for such future mobile communication systems. OFDM partitions the available bandwidth into many subchannels with much lower bandwidth. Such a narrowband subchannel experiences now due to its low bandwidth an almost flat fading leading in addition to above mentioned robustness also to simple implementations. However, one potential drawback with OFDM modulation is the high Peak to Average Ratio (PAR) of the transmitted signal: The signal transmitted by the OFDM system is the superposition of all signals transmitted in the narrowband subchannels. The transmit signal has then due to the central limit theorem a Gaussian distribution leading to high peak values compared to the average power. A system design not taking this into account will have a high clip rate: Each signal sample that is beyond the saturation limit of the power amplifier suffers either clipping to this limit value or other non-linear distortion, both creating additional bit errors in the receiver. One possibility to avoid clipping is to design the system for very high signal peaks. However, this approach leads to very high power consumption (since the power amplifier must have high supply rails) and also complex power amplifiers. The preferred solution is therefore to apply digital signal processing that reduces such high peak values in the transmitted signal thus avoiding clipping. These methods are commonly referred to as PAR reduction. PAR reduction methods can be categorized into transparent methods – here the receiver is not aware of the reduction scheme applied by the transmitter – and non-transparent methods where the receiver needs to know the PAR algorithm applied by the transmitter. This master thesis would focus on transparent PAR reduction algorithms. The performance of PAR reduction method will be analysed both with and without the PSD constrained. The effect of error power on data tones due to clipping will be investigated in this report.

Place, publisher, year, edition, pages
2006. , 59 p.
Keyword [en]
PAR, OFDM, Active-Set, Tone reservation, PSD constraint
National Category
Signal Processing Computer Science Telecommunications
URN: urn:nbn:se:bth-5309Local ID: diva2:832683
Available from: 2015-04-22 Created: 2006-02-03 Last updated: 2015-06-30Bibliographically approved

Open Access in DiVA

fulltext(841 kB)75 downloads
File information
File name FULLTEXT01.pdfFile size 841 kBChecksum SHA-512
Type fulltextMimetype application/pdf

By organisation
Department of Signal Processing
Signal ProcessingComputer ScienceTelecommunications

Search outside of DiVA

GoogleGoogle Scholar
Total: 75 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Total: 68 hits
ReferencesLink to record
Permanent link

Direct link