ウェーブレットパケットを用いた与干渉低減型UWBに関する一検討

摘要

UWB（ultra-wideband）は，極めて広い周波数帯域を占有するため，既存の狭帯域無線システムと周波数を共用する必要があり，両システム間で相互干渉が生じる.いくつかの国のUWBに関する法律で，UWB端末にDAA（detection and avoidance：干渉検出回避）を備えていることが求められている.本検討では，既存の狭帯域システムとしてWiMax（world interoperability for microwave access）を例にとり，UWB信号によるWiMaxシステムのOFDM（orthogonal frequency-division multiplexing：直交周波数分割多重方式）信号への与干渉を低減する目的で，ウェーブレットパケットを用いた与干渉低減型UWBシステムを提案し，その性能評価を行った.%This paper proposes an interference mitigation scheme for ultra-wideband(UWB) communication systems by using wavelet packets. Since the UWB systems occupy very wide frequency spectrum, it is necessary to equip with some appropriate interference mitigation scheme for existing narrowband wireless systems. In this paper, OFDM(orthogonal frequency-division multiplexing) signal is considered as a conventional narrowband signal. OFDM is adopted as an air interface of WiMax (world interoperability for microwave access), wireless LAN, etc. In the proposed scheme, the UWB terminal detects the existing OFDM signal, and deletes the wavelet packet coefficients which correspond to the frequency band occupied by the OFDM signal. Simulation results demonstrate that the proposed scheme effectively mitigate the interference from the UWB signal to the existing OFDM signal.