Even though radio access and military radars are two separate radio services, coexistence has been difficult. While military radars can use a small amount of spectrum, radio access networks require large amounts. In order to avoid interference, both systems have to work together. However, there are many uncertainties about the potential for coexistence between them. Consequently, documentary research was conducted to assess whether any coexistence solutions could be developed.
The research consisted of three main parts. The first was to examine the current situation regarding military radars and radio access network. To assess the feasibility and viability of coexistence, experts were interviewed. Third, they examined possible technologies to allow coexistence between military radars or radio access network.
Due to their limited transparency of operation, military radars make coexistence difficult. They also use frequency hopping to avoid detection and interference. They may also need state-ofthe-art filtering methods. They may also have to ensure that their equipment is only used when necessary. They may also need to share data with a shared database.
Experts stressed the importance of inter-industry collaboration and the need to have greater involvement from policy and the economy. Experts also recommended the creation of agreements that allow for the sharing of data bases and the use radar imaging results in order to increase the accuracy of individual radar images. As an example of possible coexistence between radio access networks (radars and radio), the experts mentioned the US CBRS operating in the 3.55 to 3.7 GHz band.
On a scale of 0-10, the experts ranked the most viable coexistence options. The resource allocation coexistence, location-based and cognitive radio coexistence methods received the highest rankings. The researchers found that different information exchanged between the systems could lead to the classification of the methods into coordinated and uncoordinated.
Researchers also investigated the preconditions of frequency coexistence among military radars and radio access networks. The primary precondition was the ability of secondary users to detect the presence of primary users and avoid them. If they detect radar activity, secondary WAS users (including RLAN users) must switch channels within ten minutes. The users should also regularly check the channel availability.
These studies demonstrate that military radars can coexist with radio access devices. The technology is still in early stages of development and some methods may not be efficient enough to avoid interference. Therefore, more research is needed to find effective methods for spectrum sharing.
Researchers found that the most viable coexistence options between military radars, radioaccess networks, and radioaccess systems are resource allocation coexistence. They also recommend location-based techniques, cognitive radio coexistence, and location-based method. However, there were also some safety concerns.