Long distance network link for TAx4 expansion

As a high-energy expansion of existing Telescope Array (TA) experiment, TAx4 SDs have been deployed and operated from Apr.2019. Network communication for inter-site and each detector also have been expanded to longer distance. Communication towers are located in off-grid. Those are operated by solar panel and batteries. In this report we describe hardware configuration and installation as well as operation status after the installation. We measure reception signals at communication towers and each detector sites. The reception depends on condition of terrain. There are several models and tools those are used for predicting received power considering elevation model. For future ground experiment of air shower observation, it is useful if attenuation of signal strength and communication quality could be estimated quantitatively. In this report, we present observed signal strength and its comparison with available attenuation models also.