**9. Conclusions**

334 Ultra Wideband – Current Status and Future Trends

from the values given before.

0

0.5

1

1.5

2

 **Capacity reduction (%)**

2.5

3

3.5

4

It shall be mentioned that if the critical distance is reduced from the 1m already considered down to 0.5m, the maximum accepted UWB power densities should be decreased by 6 dB

**Figure 19.** Capacity reduction as a function of the EIRP in (dBm/MHz) for multi UWB transmitters.

**Table 2.** Maximum allowed EIRP for different frequency bands with UWB activity factor of 100%.

**Table 3.** Maximum allowed EIRP for different frequency bands with UWB activity factor of 10%.

Frequency band in GHz Maximum allowed UWB EIRP in (dBm/MHz)

3.3-3.8 -88.0 (with DAA) -84.7 2.5-2.7 -90.7 -87.4 2.1-2.2 -77.4 -74.1 0.43-0.47 -91.0 -87.7

Frequency band in GHz Maximum allowed UWB EIRP in (dBm/MHz)


 **EIRP (dBm/MHz)**

3.3-3.8 -98.0 (with DAA) -94.7 2.5-2.7 -100.7 -97.4 2.1-2.2 -87.4 -84.1 0.43-0.47 -101.0 -97.7

Case A Case B

Case A Case B

The coexistence of UWB with 3G and 4G Cellular Systems has been studied in this chapter. In particular UMTS in the 2 GHz and in the 450 MHz (CDMA-450) frequency bands have been selected as examples of 3G cellular systems and the WiMAX system as example of 4G.

The methodology used to account for the impact of UWB interference on the coverage range and capacity of the interfered systems has been explained in detail. Finally it has been applied in a set of study cases in scenarios involving the 3G and 4G selected systems.

From the above given results we can conclude that the spectrum mask proposed by the FCC for indoor application (-51 dBm/MHz in the UMTS band and -41 dBm/MHz for the CDMA-450 band) is very high and cannot be tolerated by the mobile systems. From the results obtained we conclude that another spectrum mask with lower UWB power density has to be used.
