DOE OSTI2016
Introduction Verizon Wireless operates a nationwide commercial LTE system in Band 13 in the United States. FirstNet will deploy a nationwide Public Safety LTE system in the neighboring Band 14 spectrum to provide first responders with much needed broadband data services. The Idaho National Laboratory’s (INL) Wireless Test Bed (WTB) conducted interference testing between LTE Band 13 and Band 14 systems at typical vertical separation distances encountered on towers with co-located systems. The test configuration mimicked a co-location scenario where Band 13 and Band 14 systems are placed on the same tower with a vertical separation distance of 10 feet. The Band 13 and Band 14 interference testing was conducted in an open-air environment in a location off the INL Test Range that does not have RF emissions in either Band 13 or Band 14. A 30-mile area in the Little Lost River Valley in South Central Idaho was identified that is northwest of the INL range that meets that criterion. The GPS coordinates of the test area are 44° 9’ 14.89” N, 113° 21’ 56.58” W. Based on the noise floor measurements, very little RF noise is present in LTE Band 13 and Band 14 in the remote test location in the Little Lost River Valley in Idaho. This RF isolated area provides a great place to conduct testing of LTE Band 13 and Band 14 performance without effecting or being effected by existing LTE Band 13 or Band 14 systems. The Band 13 baseline average overall throughput was 72.0 Mbps which compares to an overall average throughput of 73.7 Mbps when both Band 13 and Band 14 were transmitting with a typical 10 foot vertical separation. This separation is also required for the antennas to be isolated from each other and not interfere with each other [2]. The Band 14 baseline average overall throughput was 65.2 Mbps which compares to an overall average throughput of 65.9 Mbps when both Band 13 and Band 14 were transmitting with a typical 10 foot vertical separation. These results indicate neither Band 13 nor Band 14 was affected by adjacent channel interference in a co-location scenario with 10 foot vertical separation between radiation centers. Horizontal separation testing should be conducted to verify interference would not exist in a nearby site scenario where Band 13 and Band 14 systems are placed on either adjacent towers or on rooftops of adjacent buildings in close proximity to each other. Interference testing should also be conducted between LTE Band 14 systems and the adjacent Public Safety Narrowband LMR systems. The 1 MHz guard band between LTE Band 14 and the LMR band may not be sufficient enough to prevent interference between these disparate systems. The LMR handsets transmit up to 5W in narrowband channels as narrow as 6.25 kHz bandwidth, which could de-sensitize the Band 14 eNodeB receivers especially in a near-far scenario.