Design Of Programmable Digital Baseband For IEEE 802.15.4 Based On FPGA

IEEE 802.15.4 protocol can be applied widely in the field of short-distance wireless communication, because of its low power consumption. Its network has large number of nodes. And it's an Ad-Hoc network. Especially in the popularization and application of the Internet of Things technology, more and more short-distance wireless communication systems tend to reference technologies which used in baseband for IEEE 802.15.4. A kind of digital baseband system for IEEE 802.15.4 based on FPGA which can be programed and transplanted is proposed in this paper. The OQPSK(offset-quadrature phase shift keying) modulation and half sine wave shaping used in traditional baseband for IEEE 802.15.4 are limited in resist channel noise and transmission distance. Programmable GMSK(Gaussian filtered minimum shift keying) modulation and Gaussian wave shaping are used in this paper to improve the performance of baseband for IEEE 802.15.4, providing a good foundation for its wider application.Programmable GMSK modulation and Gaussian wave shaping are used in the design of this paper to improve the performance of traditional baseband for IEEE 802.15.4. First, modules are designed by System Vue, such as partial modules, transmitting terminal module, receiving terminal module, etc. And simulation verification and comparative analysis are carried out via System Vue. Then using Quartus II to write Verilog HDL code, design timing simulation and debug system. The design is based on FPGA development board with EP2C35F672C6. IEEE 802.15.4 can be used for reference and transfer to design programmable digital short-distance wireless communication baseband which can enhanced in some aspects of performance. Main design contents are:1. Design all modules of programmable digital baseband for IEEE 802.15.4. Such as string conversion module, parallel-serial conversion module, modulation and demodulation module, etc;2. OQPSK modulation and half sine wave shaping are improved to programmable GMSK modulation and programmable Gaussian wave shaping;3. A kind of fast phase discrimination algorithm is used to improve the design of phase locked loop, which can improve the speed of phase discrimination;4. The system will be programmable to improve the flexibility in network applications. It can adapt parameters according to the environment.The programmable digital baseband for IEEE 802.15.4 has better channel adaptability and noise resisting ability. Experiments show that power spectrum of GMSK modulation will settle at-150 d B. Side lobe of signal attenuation can be faster. Bandwidth is narrower. GMSK modulation and Gaussian wave shaping won't increase many resources. So it can still integrate in a small chip. Because of the programmable design, the application fields of network can be further broadened. This paper will have important meaning in extending the using scope and increasing transmission distance of programmable digital baseband for IEEE 802.15.4.