Results 81 to 90 of about 275 (168)

A New OFDM System Based on Discrete Cosine Harmonic Wavelet Transform (DCHWT) for PSK and QAM

, 2015
This paper proposes a new orthogonal frequency division multiplexing (OFDM) system, based on discrete cosine harmonic wavelet (DCHWT) for PSK and 16-QAM modulated signals.
Kanmani, B, Narasimhan, SV, Suma, MN
core   +1 more source

Delta modulation techniques for low bit-rate digital speech encoding

, 1985
Includes bibliography.Two new hybrid companding delta modulators for speech encoding are presented here. These modulators differ from the Hybrid Companding Delta Modulator (HCDM) proposed by Un et al in that the two new encoders employ Song Voice ...
Irvine, James Moir
core  

Companding techniques for PAPR reduction of OFDM systems / Chung-Ping Liaw.

, 2011
[[abstract]]在無線通訊系統中，隨著時代科技的進步，系統的傳送速率被要求愈來愈快。而正交分頻多工技術是一種多重載波調變系統，有很好的無線傳輸高資料率使用在正交頻率通道，而且可有效地抑制ISI導致多重路徑衰減在無線通道上。 但是正交分頻多工技術有一個重大缺點，就是傳送信號有很高的均峰值(PAPR)，使得系統放大器需要較大的線性區域範圍，避免產生非線性失真，導致位元錯誤率增加以及頻譜外散的現象。不過，操作線性區域變大，卻也浪費了放大器的使用效率。 因此，在本文中 ...
廖重評, Chung-Ping Liaw
core  

Intelligent genetic algorithms for next-generation broadband multi-carrier CDMA wireless networks

, 2008
This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.This dissertation proposes a novel intelligent system architecture for next-generation broadband multi-carrier CDMA wireless networks.
Zhang, Yang
core  

A Simple and Effective Peak-To-Average Power Ratio Reduction Approach Based on Iterative Companding Transform and Filtering Framework of Orthogonal Frequency Division Multiplexing Signal

, 2017
The peak-to-average power ratio (PAPR) reduction in OFDM is an unresolved issue. Intense research has been carried out to solve the issue of peak power and to reduce the impact on overall system performance.
Thiagarajan, Thenappan T.
core  

The joint use of the walsh-hadamard transform and signal companding techniques for PAPR reduction in OFDM systems / Chien-Hung Chen, Miin-Jong Hao.

, 2011
[[abstract]]正交分頻多工系統最具有吸引力多載波調變機制方法之一，且具有很高頻譜效率及強力對抗多路徑衰減，即使有正交分頻多工系統的很多優勢，它有兩個主要缺點︰峰均值功率比和頻率的偏移問題。為了克服這些峰均值功率比問題，不同的方法已經被提出降低正交分頻多工系統的峰均值功率比問題。這些技術可被分成兩個種類︰信號攪拌和信號失真技術。在論文裡我們透過結合使用WHT和壓縮方法來降低OFDM傳送信號系統的峰均值功率比。首先WHT用來分解OFDM輸入序列的相互間關係。另一方面 ...
陳建宏, Chien-Hung Chen
core  

PERFORMANCE ENHANCEMENT OF OFDM IN PAPR REDUCTION USING NEW COMPANDING TRANSFORM AND ADAPTIVE AC EXTENSION ALGORITHM FOR NEXT GENERATION NETWORKSPERFORMANCE ENHANCEMENT OF OFDM IN PAPR REDUCTION USING NEW COMPANDING TRANSFORM AND ADAPTIVE AC EXTENSION ALGORITHM FOR NEXT GENERATION NETWORKS

, 2013
This paper presents a new hybrid PAPR reduction technique for the OFDM signal, which combines a multiple symbol representations method with a signal clipping method.
BAIG, CLEMENT RANJITH ANTHIKKAD & IRFAN AHMED
core  

Graph-guided adaptive companding for PAPR reduction in power-domain NOMA systems. [PDF]

PLoS One
Kumar A, Masud M, Alohali M, Pradhan PC, Nanthaamornphong A.   +4 more
europepmc   +1 more source

Transmitter-assisted joint data-aided channel estimation and PAPR reduction scheme in wireless fading channels. [PDF]

Sci Rep
Khan I, Hasan MM, Cheffena M.
europepmc   +1 more source

Joint Uniform Distribution Companding for Nonlinear Effects in OFDM Systems

, 2011
[[abstract]]正交分頻多工技術(OFDM)是一種高頻譜效率的多載波傳送技術，但OFDM傳輸技術其缺點有高的峰值對平均值之功率比值(PAPR)，因此要求系統中的功率放大器和類比數位轉換器皆要具有較大的線性動態範圍，所以會降低系統性能、增加硬體實現難度和系統成本。 降低OFDM系統PAPR的方法有很多，大體可以分為兩類：一類的方法是會產生信號失真，如截波(Clipping)、壓縮擴展(Companding)等，對系統而言複雜度較低，不需要增加系統的複雜度和時間延滯 ...
黃信雄, Hsin-Hsiung Huang
core