Study on modulation and channel estimation for high rate UWB communication

Abstract

As interest of short range wireless communication systems increases, UWB becomes one of promising applications for indoor communication environment. A UWB system operates by using extremely short pulse with low power, which can support not only low rate but also high rate communication. The UWB system has some advantages such as highly accurate ranging, energy capturing from multi-path, and coexistence with other narrowband systems. To realize these advantages, researches on the properties of indoor channel should be accompanied. Because an indoor channel has many multi-paths in short time range contrast to the outdoor environment, the channel affects to the system more significantly. Thus, to develop a UWB system, an accurate estimation of channel delays and coefficients are required. In addition, high-order modulation for high rate communication is necessary in an UWB since PRP should be larger than maximum delay spread of the channel to avoid ISI. In this thesis, we propose a high-order modulation scheme and a new channel estimation method. The proposed modulation method make the system send 3 bit per one symbol from combination of PPM, PAM, and PSM. Besides, we also propose orthogonal and optimal pulse shaping to be utilized for PSM and satisfy FCC spectral mask. The proposed scheme is able to provide a high rate UWB system with an efficient modulation framework. MUSIC-based channel estimation is also proposed in this thesis. The proposed method utilizes MUSIC algorithm to estimate delay components of the indoor channel. Consequently, the proposed method can be applied to indoor channel with random delay distribution.