From MediaTek: "A look at power efficient modems in MediaTek Helio"
The latest MediaTek Helio processors have greatly increased the efficiency of 4G LTE-to-Wi-Fi hotspot use, giving up to 40% power saving. This is ideal for anyone working away from home or the office, enabling them to hook up a laptop or tablet to their smartphone (where available) and benefit from significantly improved battery life.
Source: https://www.mediatek.com/blog/mediatek-helio-a-look-at-its-power-efficient-modem