Even though radio access and military radars are two separate radio services, coexistence has been difficult. Radio access networks use large quantities of spectrum while military radars only have a limited frequency allocation. Both systems must work together in order to avoid interfering. But there are still many unknowns about their potential coexistence. Documentary research was done to determine if coexistence solutions were possible.
The research method involved three main parts. First, they studied the current situation for radio access networks and military radars. Second, the researchers interviewed experts to evaluate the feasibility of possible coexistence. Third, they examined possible technologies to allow coexistence between military radars or radio access network.
Because they are not transparent in their operation, coexistence can be a problem for military radars. They also use frequency-hopping to avoid interference. They may also have to utilize state-of–the-art filtering technologies. Additionally, equipment may have to only be sent when needed. Additionally, they might need to give the necessary data to a shared base.
However, experts emphasized the importance of cross-industry coordination and the need for higher involvement from the economy and policy. The experts also suggested the implementation of agreements that involve the use of shared data bases and the use of radar imaging results to improve the accuracy of individual radar imaging. Experts also suggested the US CBRS, which operates in the 3.55-3.7GHz band, as an example of coexistence among radio access networks and radars.
The experts ranked coexistence methods from 0-10 on a scale. The resources allocation coexistence, coexistence based on location, and coexistence based on cognitive radio were the best-ranked coexistence options. The researchers also found that the methods were categorized into uncoordinated and coordinated methods, depending on how information was exchanged between the systems.
The researchers also looked into the preconditions that frequency coexistence is possible between military radars, radio access network, and radio frequencies. The primary condition is secondary users' ability to detect and avoid primary users. If they detect radar activity, secondary WAS users (including RLAN users) must switch channels within ten minutes. In addition, the users must perform a channel availability check regularly.
These studies show that there is a lot of potential for coexistence between radio access systems and military radars. This technology is still very early in development. The methods currently being studied may not be sufficient to prevent interference between the systems. Effective spectrum sharing strategies require more research.
Researchers discovered that the best options for coexistence among military radars and radioaccess network radios were the resource allocation coexistence and location-based methods. The cognitive radio coexistence methods are also feasible. However, there were also some safety concerns.