Another factor to consider when it comes to signal quality is coexistence. The wireless spectrum, as previously discussed, is crowded within the 2.4 GHz band. However, there are also other devices operating outside of this band which include GPS, GSM, 3G, and WiMax. The issue is that among all these standards, there is no established cooperation which can lead to interference. This can be solved through RF isolation such as shielding or filtering. There can also be coexistence issues inside a device when multiple RF technologies are operating simultaneously such as in combo chips with GPS, Bluetooth and/or Wi-Fi capability. This can also be solved through RF isolation between different bands and coordination in the same band in the case of Wi-Fi and Bluetooth both operating at 2.4 Ghz.