Blind algorithms development for peak to average power ratio reduction in ofdm systems under frequency selective fading channels

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University of Dar es Salaam
Orthogonal Frequency Division Multiplexing (OFDM) presents itself as a multicarrier system whose envelope is characterized by a Gaussian distribution by its nature. This lead to a chance of multicarrier which are in phase to generate peaks whose power is larger compared to the average power of the signal. This phenomenon is termed Peak to Average Power Ratio (PAPR). This effect causes High Power Amplifier (HPA) to introduce intermodulation and out of band radiation as the signal goes through it thus degrade performance of OFDM systems. Employing linear power amplifiers is very expensive and they are very inefficient, thus it is better to find solution on mitigating PAPR effect in non-linear HPA through signal processing. Analysis of this effect has been covered in this work to relate PAPR and several performance parameters such as efficiency of the HPA and Signal to Inter-carrier ratio in Frequency Selective Channel (FSC) under IEEE 802.20 wireless broadband standard. A proposed solution which aspire the advantage of the signal transformation technique and distortion technique was proposed to reduce PAPR to a satisfactory level and performance. At a CCDF level of 10-3 the proposed algorithm has achieved 6.6 dB PAPR improvement and BER performance has degraded by 6.1 dB compared to original OFDM signal with no distortion under FSC. Also the technique is independent towards the user block size and number of subcarrier. The achieved improvement in PAPR and acceptable degradation in BER performance qualifies this algorithm as a better PAPR reduction algorithm in FSC, without forgetting the advantage of spectral efficiency observed as no side information is required.
Available in print form, University of Dar es Salaam at Dr. Wilbert Chagula Library(THS EAF TK5103.484.G32)
Orthogonal frequency division multiplexing, Wireless communication systems
Gadiel, G.M (2013)Blind algorithms development for peak to average power ratio reduction in ofdm systems under frequency selective fading channels, Master dissertation, University of Dr es Salaam, Dar es Salaam