The technical feasibility of developing an Internet of Things multi-user communication system is evaluated based on a central digital multiband carrierless amplitude and phase transmitter, which broadcasts data on multiple channels for a number of low-cost/low-power devices. It addresses the issue of carrier synchronisation, which is critical in real-world implementations because of imperfections of devices and the delays of the system. A simulation model for the traditional Costas Loop is presented, along with performance results, which demonstrate the system's ability to synchronise with pull-in and lock ranges of ±800 and ±900 Hz, respectively. The loop requires 1.194 ms to be in the locked state, allowing the system to lock within 6 symbols period. In addition, the authors measured the performance of the system in the presence of noise and interference from other modulated bands. The results showed that noise and interference did not degrade the system's performance. Although the system was unable to lock when energy was present in adjacent bands, alternative options such as a high order phase-locked loop and hybrid frequency-division multiple access and time-division multiple access, can improve system performance without significantly increasing the cost and complexity of the devices.

中文翻译：

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基于可见光通信的物联网系统的多频段无载波幅度和相位调制中的载波同步

基于中央数字多频带无载波幅度和相位发射机评估开发物联网多用户通信系统的技术可行性，该发射机在多个通道上为许多低成本/低功耗设备广播数据。它解决了载波同步问题，由于设备的不完善和系统的延迟，这在现实世界的实施中至关重要。提出了传统 Costas Loop 的仿真模型以及性能结果，证明了系统分别与 ±800 Hz 和 ±900 Hz 的拉入和锁定范围同步的能力。该环路需要 1.194 ms 才能处于锁定状态，从而允许系统在 6 个符号周期内锁定。此外，作者测量了系统在存在噪声和其他调制频段干扰的情况下的性能。结果表明，噪声和干扰不会降低系统的性能。尽管系统无法锁定相邻频带中存在能量的时间，但替代选项（例如高阶锁相环以及混合频分多址和时分多址）可以在不显着增加成本和成本的情况下提高系统性能。设备的复杂性。