Resource allocation is a critical issue for Wireless Sensor Networks (WSNs) especially for Ultra-Wide Band (UWB) based networks. In this paper, we present frequency allocation scheme for an efficient spectrum management that is able to statically assign control channels and dynamically reuse data channels for Personal Area Networks (PANs) inside a Large- Scale WSN based on UWB technology. The frequency allocation problem is decomposed into two sub-problems: static control channel assignment and dynamic data channel allocation. The goal is two-folded: first, we aim to avoid congestion of control channel, second, to maximize simultaneous communications without suffering from interference in order to enhance throughput, decrease delay and minimize energy consumption.