The escalating interest on the topic of coexistence between radar systems and broadband communication devices is a direct consequence of the significant portion of the international radio spectrum currently allocated to radar systems. However, studies show that their spectrum occupancy is low in the spatial, temporal, and frequency domains. The most promising radar bands for shared use are the L, S, and C bands located in the 960-1400 MHz, 2.7-3.6 GHz, and 5.0-5.85 GHz frequency ranges, respectively. These frequencies are sufficiently low to avoid high power consumption and the usage of highly directional antennas, and sufficiently high to offer considerable bandwidth to commercial services. Furthermore, they are close to the cellular and ISM bands used for 2G/3G/4G and wireless local area networks (WLAN), respectively, facilitating the production of low-cost devices capable of using all these frequencies.

Chapter Contents:

• 3.1 Radar systems—the incumbents
• 3.1.1 Classification of radar systems
• 3.1.1.1 By operating principle
• 3.1.1.2 By application
• 3.1.1.3 By waveform
• 3.1.1.4 By beam and scanning pattern
• 3.1.2 Radar environmental factors
• 3.2 Current regulation on radar spectrum sharing
• 3.2.1 5150–5925 MHz band
• 3.2.1.1 Radio environment
• 3.2.1.2 Policy history and context
• 3.2.1.3 Incumbent protection
• 3.2.2 3550–3700 MHz band in the United States
• 3.2.2.1 Radio environment
• 3.2.2.2 Policy history and context
• 3.2.2.3 Spectrum access system
• 3.2.2.4 Incumbent protection
• 3.3 Spatial sharing techniques
• 3.3.1 Geolocation database (GL-DB)
• 3.3.2 Spectrum sensing and DFS
• 3.3.2.1 Beaconing
• 3.3.3 Cooperative spectrum sensing
• 3.3.4 Radio environment map (REM)
• 3.4 Beyond traditional sharing schemes
• 3.4.1 Temporal sharing
• 3.4.2 Cognitive beamforming
• 3.4.2.1 Offline beamforming
• 3.4.3 Coexistence through cooperation and codesign
• 3.4.4 Open challenges
• 3.5 Secondary radio access technologies
• 3.5.1 LTE in unlicensed spectrum
• 3.5.2 Licensed LTE
• 3.5.3 WLAN
• 3.6 Conclusions
• 3.7 Looking ahead
• References

Inspec keywords: cellular radio; power consumption; broadband networks; radar; radio spectrum management

Other keywords: ISM bands; spectrum sharing; C bands; temporal domains; radar systems; power consumption; spatial domains; WLAN; S bands; 2G; frequency 2.7 GHz to 3.6 GHz; 3G; international radio spectrum; frequency 960 MHz to 1400 MHz; directional antennas; 4G; broadband communication devices; cellular bands; frequency 5 GHz to 5.85 GHz; L bands; frequency domains; spectrum occupancy; small cells; wireless local area networks

Subjects: Mobile radio systems; Radar equipment, systems and applications