Dynamic Approach To Enhance Performance Of Orthogonal Frequency Division Multiplexing(OFDM) In A Wireless Communication Network

Abstract

Abstract-In the mobile radio environment, signals are usually impaired by fading and multipath delay phenomenon. This work modeled and simulates OFDM in a wireless environment, it also illustrates adaptive modulation and coding over a dispersive multipath fading channel whereby simulation varies the result dynamically. Dynamic approach entails adopting probabilistic approach to determining channel allocation; First an OFDM network environment is modeled to get a clear picture of the OFDM concept. Next disturbances such as noise are deliberately introduced into systems that are both OFDM modulated and non-OFDM modulated to see how the system reacts. This enables comparison of the effect of noise on OFDM signals and non-OFDM modulated signals. Finally efforts are made using digital encoding schemes such as QAM and DPSK to reduce the effects of such disturbances on the transmitted signals. In the mobile radio environment, signals are usually impaired by fading and multipath delay phenomenon. In such channels, severe fading of the signal amplitude and inter-symbol-interference (ISI) due to the frequency electivity of the channel cause an unacceptable degradation of error performance. Orthogonal frequency division multiplexing (OFDM) is an efficient scheme to mitigate the effect of multipath channel.

Критерії Вибору Спектрально-Ефективних Сигналів У Безпроводових Інформаційних Мережах

“…Взагалі, технологія OFDM є вельми популярною та корисною для безпроводових мереж. Опису OFDM присвячено велику кількість монографій [1-4] та статей [5][6][7][8][9][10][11][12][13][14][15]. Але практично в усіх доступних нам джерелах лише констатується факт використання OFDM без глибокого аналізу його характеристик, достоїнств та недоліків, обумовлених специфікою ортогонального мультиплексування.…”