Why b71 and n71 (600 Mhz) have uplink freq higher than downlink freq, whereas standard normally is U/L is lower than D/L usually?
In the conventional FDD terrestrial mobile systems, the mobile terminal transmits at the lower frequencies and the base station at the higher frequencies. This is because the system performance is generally constrained by the uplink link budget due to the limited transmit power of terminals. However, the compatibility studies between Mobile/Fixed Communications Networks and digital broadcast systems suggest that the reversed duplex direction results in better spectrum efficiency by minimising guard bands. Moreover, as the path loss difference between the highest frequency 862 MHz and the frequency 798 MHz is only about 0.6 dB (assuming free space propagation), the reversal of the duplex direction will not impact greatly the uplink coverage.
Therefore, it is proposed that the duplex direction for fixed/mobile applications in the 790 -862 MHz should be reversed, i.e. the uplink should be at the top of the harmonized sub-band.
Ok makes sense, bands 13, 14, 20 and 24 also have same way.
Yes… I analyzed this fact while deploying band20 in LTE few years back.