| Summary: | 碩士 === 國立成功大學 === 電腦與通信工程研究所 === 93 === With the development of wireless networks and micro electro mechanical systems, wireless sensor networks, a new kind of networks, have been studied popularly. In wireless sensor networks, the usage of bandwidth is not as important as in traditional networks, but the issues of low cost and low power consumption are emphasized. Due to above reasons, most standard which emphasize the high transmission rate in wireless networks are not suitable for wireless sensor networks.
IEEE 802.15.4 standard is the wireless transmission standard for low-rate wireless personal area networks (LR-WPANs), so it is very suitable for wireless sensor networks. Like IEEE 802.11x series standards, IEEE 802.15.4 defines the specifications of the physical (PHY) layer and media access control (MAC) layer. In PHY layer, IEEE 802.15.4 operates on two different frequency bands – 868/915 MHz and 2.4 GHz, and it offers transmission rates of 20kb/s, 40kb/s, and 250kb/s respectively.
Like in other standards for wireless communication, the transmission in IEEE 802.15.4 would be affected by the non-ideal channel effects, including noise, carrier frequency offset (CFO), carrier phase offset (CPO). In this thesis, we implement a synchronization algorithm which estimates and compensates the CFO and CPO but not affect the receiving of data by using the preamble field of IEEE 802.15.4 phy protocol data unit (PPDU) and differential decoding technology. We also provide a hardware architecture of IEEE 802.15.4 baseband processor. We demonstrate the effectiveness of the synchronization algorithm and architecture by simulations which include the influences of noise, CFO, and CPO.
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