The application of Cumulative Decision Feedback (DF) technique for energy/complexity constrained Wireless Sensor Networks (WSN) is considered. Theoretical bit error probability and average rate of a BPSK modulated DF are derived together with PHY-MAC layers' energy efficiency model for DF and Forward Error Correction (FEC) techniques. Moreover, an empirical optimization, which in turn relies upon a low complexity SNR estimation method also derived in this letter, is applied to the DF technique in order to obtain maximum energy efficiency.

This paper presents the analysis on hidden node due to multiple transmission power level and its potential impact to system performance of White Space radio operating in the TV bands, a.k.a TV white space (TVWS). For this purpose, a generic interference model for determining the hidden node occurrence probability based on realistic physical (PHY) layer model is developed. Firstly, the generic hidden node interference model is constructed considering typical TVWS radio network deployment scenario. Emphasis is given on cases where the hidden node scenario involves multiple transmission power level. Secondly, the PHY layer design and channel propagation are modeled to analyze the realistic operating range of the TVWS radio. By combining the hidden node interference model and the PHY layer/propagation models, the realistic probability of hidden node occurrence is calculated. Finally, the performance degradation in the victim receiver due to interference generated by the potential hidden node is quantified. As a result, for urban environment, it is found that for networks consisting of devices with multiple transmit power level, the probability of hidden node occurrence is similar to that of networks consisting of devices with uni-transmit power level, provided that the interferer-victim separation distance in the former is 800 m farther apart. Furthermore, this number may increase to a maximum of 1.1 km in a suburban environment. Also, it is found that if the hidden node actually occurs, a co-channel interference (CCI) of -15 dB typically causes a degradation of 2 dB in the victim receiver.

The application of Orthogonal Space-Time Block Codes (O-STBC) as the encoding scheme in the presence of "non-quasi-static" fading was considered. A simple and efficient adaptive method of channel estimation based on the interpolation of estimates acquired at the pre-amble and post-amble of framed blocks of information is developed. Moreover, the proposed method is proven, both theoretically and by simulations, to outperform the alternative of channel tracking, despite its significant low complexity.