In this paper, we present UWB-TSCH, an adaptation of the Time Slotted Channel Hopping (TSCH) MAC layer design for IEEE 802.15.4 UWB PHY layer. This approach combines time division medium access with frequency hopping. It allows for UWB nodes to reach much higher channel occupancy than with ALOHA and to drastically reduce their energy consumption, allowing them to be used in low power wireless sensor networks. Moreover, we show that using multiple channels concurrently, localization schemes such as Time Difference of Arrival (TDoA) could reach in excess of 2400 localizations per second.