A Case Study of Interference Between Public Safety Long Term Evolution (LTE) And Public Safety 700 MHz Land Mobile Radio

This technical white paper discusses measurements of Project 25 (P25) LMR receivers' performance when subjected to adjacent service interference from public safety LTE, and interference to LTE base stations from P25. There were three areas of interest in these measurements: (1) eNb1 and UE2 interference onto mobile LMR, (2) eNb and UE interference onto LMR repeater, and (3) P25 mobile and P25 repeater interference onto eNb.

For the mobile LMR case, PSCR personnel used a Motorola XTL-5000/0-5 and XTL-5000/0-3 radio. For both the mobile LMR case and the eNb case, PSCR personnel used Rohde & Schwarz signal generators to create the appropriate P25 and LTE test signals.

For the LMR repeater measurement, receiver performance was measured in situ at a public safety LMR trunk site. The type of LMR repeater deployed at this site was a Motorola GTR-8000 repeater.

Many public safety radio networks specify a minimum performance level of 2 percent bit error ratio (BER). 0ur measurements of adjacent service interference rejection, likewise, used 2 percent BER as a performance parameter.