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A new design of distributed space time block coding for cooperative relay networks is presented in this paper. The Hadmard matrix and decode-and-forward approach are used at each relay node to generate the new efficient code. Each relay transmits its new code as a linear function of its received signal from the source node. This proposed method uses linear decoding process at the destination node to achieve full data transmission rate and doubling cooperative diversity order without any feedback link between the relay nodes and the destination node. The proposed scheme yields low encoding and decoding complexities at the relay and destination nodes. Furthermore, the simulation results show great performance enhancement without any feedback overhead as compared to regular reported methods.

In this paper, we proposed two Distributed Extended Orthogonal Space-Time Blok Coding (D-EO-STBC) schemes with two terminal nodes, four relay nodes all equipped with single antenna, represented in the first scheme, and two terminal nodes, two relay nodes equipped with dual antennas as a second scheme. Full-data rate and Full-transmission diversity are achievable. Moreover, the second scheme has an advantage of minimizing the decoding complexity at the relay nodes . The simulation results show that both proposed schemes have good performance.

This paper presents the application of quasi-orthogonal space time block coding (QO-STBC) with two constant feedback scheme. The feedback scheme employs two-constant feedback paths. This is applied to four transmit and N receiver antennas to achieve full transmit diversity gain and full data transmission rate with simple-wise decoding complexity at the receiver side. This proposed feedback scheme achieves full diversity order of 4 ×N at the receiver side by canceling the self-interference from adjacent symbols in QO-STBC codeword. The simulation results confirm that the feedback scheme significantly improves the performance over all existing feedback methods with reduced computational complexity and is based on the channel state information (CSI) available at the receiver side.

Hotels are considered one of the most energy consumers in the building sector and are thus responsible for quite large amounts of carbon dioxide emissions. The major part of this energy is utilized for water heating, space heating and cooling, and lighting. This study aims to estimate the energy potential of hot water in the hotel sector of Libya, and the opportunities of saving an important part of this energy through utilizing solar energy. The study depends on distributing questionnaires to a big sample of hotels over different cities in Libya. The information that was gathered from the questioners with other information from different sources is analyzed and projected all over Libya. The outcome of this study is to estimate a theoretical and technical potential of using solar energy in providing hot water to the hotel sector of Libya. Results have shown that there is a high potential of hot water in the hotel sector of Libya with over 18.54 (GWh/year while the technical potential of using solar energy for heating water is 25,386 m2 of collector area. The savings in using solar energy technology for water heating in the hotels in Libya is 1.3 million (L.D/year).

This paper proposes one-bit feedback extended orthogonal space-time block coding (EO-STBC) based on selection of cyclic phase rotation for asynchronous cooperative relay networks over frequency selective channels. The two relay nodes are assumed to be equipped with two half duplex antennas. Orthogonal frequency division multiplexing (OFDM) is implemented at the source node. A cyclic prefix (CP) is added at the source and relay nodes to mitigate the intersymbol interference (ISI) induced by multipath fading and timing errors between the relay nodes, which operate in a simple distributed STBC amplify-and-forward (AF) transmission type. This approach attains unity rate over each hop in the network and cooperative spatial diversity order 2R over the frequency selective fading channels. End-to-end frame error rate (FER) simulation results confirm that the proposed scheme significantly improves the performance over previous feedback methods with feedback limited to only one-bit per subcarrier based upon channel state information (CSI) available at the destination node.

In this paper, we select the best two relays from a set of available relays, each of which is equipped with two antennas, based on the instantaneous path gains. Closedloopquasi orthogonal space time block coding is then applied over the selected two relays to maximize cooperative diversity. parallel interference cancellation detection is also applied at the destination node to mitigate the problem of imperfect synchronization between the relay nodes. End-to-end bit errorrate simulations confirm that the selection scheme yields a significant improvement in performance over the conventional scheme without using relay selection. Furthermore, the biterror rate simulations confirm the advantages of the detection scheme for a range of levels of asynchronism, and that onlya small number of iterations is required in the parallel interference cancellation technique.