應用於智慧型標籤基站接收機之軟體定義無線電模組 的實現

Abstract

本論文自訂應用於短距離無線通訊之智慧型標籤(Smart Badge)系統，使用416MHz生醫通訊頻帶(industrial Scientific Medical Band,ISM)進行傳輸，傳輸接收的調變方式為差分正交相移鍵控(Differential Quadrature Phase Shift Keying,DQPSK )，因智慧型標籤系統需要長時間運作，須具備省電，低複雜度特性。且本系統為多使用者對一傳輸系統，各封包會有不同的載波頻率偏移與時脈偏移。因此在每次接收封包時需要重新進行同步的估測與補償，且本系統為隨機存取模式通訊協定(random access type)，因此也需要封包的同步。 本系統是以商用的軟體定義無線電(Software Defined Radio, SDR)模組作為基站接收機DPS 演算法的驗證平台，演算法模擬環境為AWGN 通道SNR=10~15dB。利用模組的現有硬體資源配合PC 上的軟體達到系統的實現與驗證。對於未來的通訊協定的更動或是其他功能區塊的加入及整合有較及時的應變力。最後實驗結果呈現在Tx-Rx 距離0.5 公尺 可以使封包正確率達到86.54%。

In this paper we proposed a short-distance communication Smart Badge System which communicates through wireless channel and integrates the transceivers into licensed-free 416MHz bands. Modulation format of Smart Badge is DQPSL due to simplicity. The system design of Smart Badge is focusing on low complexity and dealing with some non-linear effect. The system is multiple users transmission system, every packet may have different Carrier frequency offset and clock offset, so each time we receive packet, we need to synchronize again. Besides our system adopts random access mode protocol that its packet arrival time is unknown, so packet synchronization is necessary. We design and implement a low complexity Smart Badge base station receiver based on software defined radio module. We choose bladeRF SDR module, because it is suitable for our system specification. Due to its zero-IF architecture, we need to deal with some non-linear effect by DSP functions. Such as IQ imbalanced compensation, AGC, DC offset compensation and packet detection and confirm. The parameter we choose is simulation by assume SNR=10-15dB. We use Matlab to implement DSP function. The PER is about 13.46%,