Opportunistic Use of TV Frequency Bands In Tactical Radio Communication

Opportunistic spectrum access means that frequency spectrum is used by a secondary user whenever possible without degrading the communication capabilities of the primary user. In this report the possibility of using the technology opportunistic spectrum access to get access to additional broadband channels to the Armed Forces' radio system. The existing broadband channels are mainly used for voice and data traffic by the army. The armed forces' access to frequency space in the military UHF band intended for broadband channels is limited. Broadband channels is in this case channels with a bandwidth of 1 MHz within the frequency range 225-380 MHz. There are advantages both out of a coexistence perspective and out of an interference protection perspective if it is possible to use more broadband channels. Within the frequency range 380-694 MHz there are mainly four categories of allocations: TETRA, land mobile, meteorology and terrestrial TV. Frequency allocation for terrestrial TV is the category deemed most suitable to study for opportunistic use, while others are not judged to be suitable. The assessment is that there will be at least five 8-MHz channels available in northern Sweden. This means access to 40 wideband channels for a tactical radio system. Within each geographic area, the channels that have too high interference power from TV transmitters must be identified. These channels cannot be used by a tactical radio system because they cause excessive degradation of performance. Utilizing TV channels opportunistically provides access to greater bandwidth and thus increased system capacity and the possibility of allocating more radio networks. A higher carrier frequency will mean shortened communication ranges. The impact is particularly noticeable when the radio waves have to propagate through forests.