 each base station. The accuracy and stability of the GNSS solution are also independent of other oper- ational aspects in mobile networks. They are not impacted by the downtime of other network elements, traffic congestion in the radio interface or transmission network, 8.7 Network Synchronization and Coordination Requirements Figure 8.24 GNSS synchronization solution. GNSS receiver Power and Synchronization control to signal to base station Base station system module and the size of the mobile network. The GNSS synchronization solution is therefore a very attractive solution for providing a highly accurate synchronization solution with performance that is independent of the operation of mobile network. Nevertheless, there are also a number of considerations that can be considered as disadvantages of the GNSS solution. They can, however, be viewed as subjective because they may depend on the operator's environment, which differs from one operator to another. The GNSS solution is viewed as an expensive solution because of the additional cost of the GNSS receiver and the installation costs that the operator need to incur for every base station site. The deployment of the GNSS receiver can sometimes be difficult because it often requires clear satellite visibility. This means that it may not be possible to install the GNSS receiver in locations such as an indoor building, urban canyon, or tunnel, where clear satellite visibility will be an issue. The accuracy and stability of the GNSS solution may be impacted by factors that are outside the operators' control such as bad weather condition, GPS jamming, or GPS spoofing. Problems such as GPS jamming can be very common in some countries, for example, via criminal activities or via military exercises. In the worst case, it can bring the whole network down, as the base station may have to shut itself down to avoid further inter- ference to the system. 8.7.9 Synchronization with ToP The disadvantages of the GNSS solution mentioned above create a demand for an alter- nati