Frequency Reuse and System Capacity in Mobile Broadband Systems: Comparison between the 40 and 60 GHz Bands

Abstract

This paper addresses the comparison of characteristics between the bands of 40 and 60 GHz, prospectively allocated for Mobile Broadband Communication Systems. The key difference between the two bands is the oxygen absorption, which is negligible at 40 GHz, but presents high values at 60 GHz, decreasing from 14 dB/km (at 62 GHz) down to approximately 1 dB/km (at 66 GHz). The impact of this excess absorption is two-fold: on one hand it reduces the received signal power but on the other hand it also reduces the co-channel interference. These two quantities may not suffer the same amount of reduction, and hence differences in the reuse pattern may result. The results show that for the regular coverage geometries the difference in the reuse pattern obtained in both bands is not relevant, a value of 3 being achieved. Differences however exist in the range of maximum coverage distances values at 43.5 GHz being up to 20% larger than at 66 GHz. For irregular urban geometries the results obtained from specific cellular layouts, show that the reuse pattern is the same for both bands (in the range 5–7) for the the range of coverage distances where the system operation interference limited (say, for coverage distances less than 124 m). Again, larger coverage lengths can be achieved at 40 GHz, although with a higher associated reuse pattern.