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Collaborative communication produces significant (N2 where N is number of nodes used for collaboration) power gain and overcomes the effect of fading. With imperfect frequency synchronization significant but slightly less than N2 power can be achieved. As the N increases more power gain can be achieved at the expense of more circuit power. In this paper an energy consumption model for collaborative communication system with imperfect frequency synchronization is proposed. The model to calculate the energy consumed by the sensor network for local communication and communication with base station is presented. Energy efficiency model for collaborative communication for the off-the shell products (CC2420 and AT86RF212) are presented. It is also shown that significant energy can be saved using collaborative communication as compared to traditional SISO (Single input single output) for products. The break-even distance where the energy consumed by SISO and collaborative communication is also calculated. From results it is revealed that collaborative communication using 5 nodes produces efficient energy saving. [ABSTRACT FROM AUTHOR]

orthogonal frequency-division multiplexing (OFDM) communication systems, the frequency offsets in mobile radio channels distort the orthogonality between subcarriers resulting in inter-carrier interference (ICI). In this paper, First OFDM system is modeled and simulated under different channel conditions such as AWGN and Rayleigh fading. Subsequently pulse shaping technique for ICI power reduction in OFDM systems is investigated. A number of pulse shaping functions such as Rectangular pulse shape, Sinc power pulse (SP) and Improved sinc power pulse (ISP) have been considered for ICI power reduction. The performance of each pulse shaping function is evaluated and compared with each other using the parameters such as ICI power, SIR (Signal to Interference Ratio) and BER (Bit Error Rate). It is found that ISP pulse shape outperforms to all other pulse shaping functions by the above parameters. [ABSTRACT FROM AUTHOR]

Recurrent neural network (RNN) exhibits better performance in nonlinear channel equalization problem. In this present work a hybrid model of recurrent neural equalizer configuration has been proposed where a discrete cosine transform (DCT) block is embedded within the framework of a conventional RNN structure. The RNN module needs training and involves updation of the connection weights using the standard RTRL algorithm, which necessitates the determination of errors at the nodes of the RNN module. To circumvent this difficulty, an adhoc solution has been suggested to back propagate the output error through this heterogeneous configuration. Performance analysis of the proposed Recurrent Transform Cascaded (RTCS) equalizer for standard communication channel models show encouraging results. [ABSTRACT FROM AUTHOR]

A new MAC frame length design for maximizing the saturation throughput of the PCA scheme in the WiMedia Multiband-OFDM UWB systems is presented in this paper. The proposed design is carried out by extending the original EDCA model of the IEEE 802.11e into the Multiband-OFDM UWB protocol. The extended model considers the effects of the BER, the transmission opportunity limits and the uniqueness of WiMedia MAC timing structure. The station throughput is maximized when the length of the transmitted frame is set to an optimal value, and this optimal frame length increases exponentially when the value of the SNR is high. The optimal frame length is independent of the number of the active stations, data rate and the priority of the access categories. Therefore, a station can dynamically adapt the frame length according to the current SNR level so as to maximize its saturation throughput in the Multiband-OFDM UWB systems. [ABSTRACT FROM AUTHOR]

Collaborative communication produces high power gain, if the frequency and phase synchronization is achieved. In this paper a novel architecture is proposed for a collaborative communication system in the presence of AWGN and frequency offsets. The mathematical expressions are derived and verified through simulation for received power and bit error rate (BER) of the system. It is analyzed that using this collaborative communication model, the significant power gain and reduction in BER can be achieved even though the system is with imperfect frequency synchronization. The analysis of the model is performed using the parameters of off-the-shelf products. The analysis revealed that power gain decreases and BER increases as the frequency offsets (errors) are increases. [ABSTRACT FROM AUTHOR]