In wireless networks, propagation models are used to assess the received power signal and estimate the propagation channel. These models depend on the pathloss exponent (PLE) which is one of the main parameters to characterize the propagation environment. Indeed, in the wireless channel, the path loss exponent has a strong impact on the quality of the links and must therefore be estimated with precision for an efficient design and operation of the wireless network. This paper addresses the issue of path loss exponents estimation for mobile networks in four outdoor environments. This study is based on measurements carried out in four outdoor environments at the frequency of 2600 MHz within a bandwidth of 70 MHz. It evaluates the path loss exponent, and the impact of obstacles present in the environments. The parameters of the propagation model determined from the measurements show that the average power of the received signal decreases logarithmically with the distance. We obtained path loss exponents values of 4.8, 3.53, 3.6 and 3.99 for the site 1, site 2, site 3 and site 4, respectively. Clearly the density of the obstacles has an impact on the path loss exponents and our study shows that the received signal decrease faster as the transmitter and receiver separation in the dense environments.

Power control is a major issue in the deployment of 4G mobile networks. Indeed, environmental constraints (relief, Air, noise,...) affect the propagation channels of mobile network systems. The new multimedia services, which consume large amounts of radio resources (frequencies), then lead to an optimization of power control in the cellular coverage in the uplink direction. The aim is to optimize the capacity of radio resources in the cellular coverage based on a COST-231 Walfisch-Ikegami semi-empirical propagation model for power control in the upward direction. It is a question of studying the signal quality between a mobile station and the base station under the constraint of obstacles (Buildings) in order to evaluate the effect of propagation losses on the transmission power in Uplink using different frequencies of the network. Results show that the transmission power is strongly influenced by the path losses that depend on the carrier frequency. Higher the transmission frequency, the less the wave propagates due to propagation and penetration losses due to different barriers.

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