Telecommunications
Tamirat Yenealem; Robel Getachew
Abstract
Path loss models estimate the average path loss a signal experiences at a particular distance from a transmitter. However, each type of existing path loss propagation model is designed to predict path loss in a particular environment that may be inaccurate in other different; hence selecting the best ...
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Path loss models estimate the average path loss a signal experiences at a particular distance from a transmitter. However, each type of existing path loss propagation model is designed to predict path loss in a particular environment that may be inaccurate in other different; hence selecting the best path loss model and optimizing it will minimize that inaccuracy. This work presents a comparative analysis of five empirical path loss models, COST- 231, ECC-33, Hata, SUI, and Ericsson model, with respect to the measured data from the 14 selected sites in Hawassa city, Ethiopia at 1800 MHz frequency bands. A drive test methodology was adopted for data collection and Nemo Handy and Nemo Outdoor were used as measuring tools for the test. Error measuring tools such as root mean square error, mean absolute error, standard deviation, and mean absolute percentage error were used to select the terrain type of each site and the path loss model that best fits that site. The results show that not only Hawassa city consists of urban and sub-urban terrains but also ECC-33 and Hata are better estimators for Hawassa urban and sub-urban areas with RMSE of 4.18 and 7.86 respectively. The model tuning using the least square method reduced the RMSE of ECC-33 and Hata to 2.46 and 5.18 respectively. The reduction in RMSE shows that the tuned versions are close to the environment. Hence, using the tuned versions of the selected models will result in good cellular network design and enhance the service quality.
Telecommunications
Mehdi Basiri Abarghouei; Reza Saadat
Abstract
This paper proposes a new relaying protocol for transmitting from a cellular user to the base station with the joint cooperation of a Full-Duplex (FD)-enabled Device-to-Device (D2D) pair. In the proposed scheme, the receiver of the D2D acts as a relay, with the cooperation of its transmitter pair via ...
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This paper proposes a new relaying protocol for transmitting from a cellular user to the base station with the joint cooperation of a Full-Duplex (FD)-enabled Device-to-Device (D2D) pair. In the proposed scheme, the receiver of the D2D acts as a relay, with the cooperation of its transmitter pair via D2D communication between them. The cooperation approach of the D2D receiver is chosen as Adaptive Decode-and-Forward (ADF), while the cooperation strategy of the D2D transmitter is chosen as either ADF, Amplify-and-Forward (AF), or Hybrid relaying protocol. These scenarios are named "Decode and Joint Cooperation," "Amplify and Joint Cooperation," and "Hybrid and Adaptive Joint Cooperation," respectively. The Average Symbol Error Probability (ASEP) of the system is studied over independent and identically distributed (i.i.d) complex Gaussian (Rayleigh envelope) channels, with perfect Channel State Information (CSI) in the presence of Residual Self-Interference (RSI) at the FD relays, as well as Co-Channel Interference (CCI). Moreover, closed-form and high Signal-to-Interference-plus-Noise Ratio (SINR) tight ASEP approximations are established. The optimum power allocation is formulated based on the approximate relations, and the optimal solutions and their characteristics are discussed in detail. Analytical comparisons and simulations confirm the theoretical results and demonstrate significant performance improvements.