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The limitations of channel bandwidth, time varying channel and fading are significant and fundamental problem in wireless communication, which leads to the difficulty of providing high Quality of Service. The traditional wireless communication systems are designed to provide good quality of services at the worst channel conditions. Wherein any attempts to increase the channel bandwidth, interference...
In this paper, the BER performance of OFDM-BPSK 16--QAM and 64--QAM system over various multhipath fading channel has been reported. Orthogonal Frequency Division Multiplexing (OFDM) is a key technique for achieving high data rates and spectral efficiency requirements for wireless communication systems. However in fading environments the bit error rate (BER) increases. The performance can be improved...
In this paper, stochastic delay differential equation (SDDE) and its application on communications are discussed. Based on SDDE, a novel communication scheme-delay time modulation (DTM) is proposed. In this modulation scheme, the information signal is conveyed by the delay time of a delayed linear Langevin equation, which exhibits a linear relationship with the variance of the SDDE system output....
We propose a selective detection scheme based on pulse repetition for coherent IR-UWB (impulse radio-ultra wide band) systems. For signal modulation and demodulation, we consider bi-phase modulation and on-off keying that are widely used in the coherent IR-UWB systems. The proposed selective detection scheme transmits the UWB signals by pulse repetition at the UWB transmitter to take system complexity...
Recently pi/4 shifted differential quadrature phase shift keying (pi/4-DQPSK) modulation has attracted much attention as it is used for high-capacity code division multiple access (CDMA) based digital cellular systems. One of the major reason behind this is the provision for differential detection which allows production of low complexity mobile units. In this paper, we present analytical expressions...
In this paper we derive optimal power allocation (PA) in space and time that minimizes BER for transmitter selection in multi-input-single-output (MISO) Rayliegh fading channels assuming perfect channel state information (CSI) is available at receiver and transmitter. This power allocation scheme achieves exponential diversity order with a single RF front end and requires feedback of the best channel...
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