Today, Cloud Tranceiver wireless systems are everywhere, and the number of wireless devices and services continues to grow. Design a complete RF system is an interdisciplinary design challenge, Cloud Tranceiver analog RF front end is one of the most critical part. However, the introduction of integrated RF transceivers such as the AD9361 significantly reduces RF challenges for such designs. These transceivers provide a digital interface for analog RF signal chains, allowing easy integration into ASICs or FPGAs for baseband processing. Cloud Tranceiver The baseband processor (BBP) allows user data to be processed in the digital domain between the terminal application and the transceiver device. In addition, the use of Simulink and other system modeling tools can easily complete the baseband processor design. However, novice users may find it difficult to understand and solve this communication system problem. This paper attempts to design and implement a simple RF baseband processor for wireless transmission communication systems. Designed using the AD9361 FPGA reference design framework, the AD-FMCOMMS2-EBZ and Xilinx® ZC706 platforms are implemented.
In most cases, the RF front-end interface to the BBP is DAC and ADC. These are digital interfaces for analog signals. Therefore, the data can not be simply sent to the DAC input and the same data is expected to be obtained at the ADC output. The data is transmitted in serial form and the single bit data is mapped to the full resolution of the DAC. Likewise, the data is received in serial form and is demapped from the full resolution of the ADC. This provides ample redundancy. If these are 16-bit converters, the receiver will determine 1 or 0 from the possible 65536 data set. Cloud Tranceiver Only this, you can significantly simplify the decoding.
RF front-end devices such as the AD9361 are I / Q transceivers. If the input is a quadrature signal, these devices are most effective. These devices typically perform internal I / Q matching and correction along two data paths to offset any discrepancies between the two. The rule is that the real (I) signal is a cosine function and the imaginary part (Q) signal is a sine function.
Data requires timing information, bit spacing. The maximum possible bit interval is the sampling period. In order to keep the receiver simple, it takes enough time to decode the signal and make a decision. The simplest timing recovery method is zero crossing and peak detection. In this case, the peaks will be inconsistent. Therefore, Cloud Tranceiver select the zero crossing for bit interval detection and tracking. There are also carrier differences between the two systems. In some cases, at any point in the user's data, the sample may be blurred. Four samples are set for every half sinusoidal signal, and the bit interval is set to 8 samples. Thus, Cloud Tranceiver the effective transfer rate is the sampling frequency divided by 8.
Since the systems are not synchronized with each other, the receiver's signal will have amplitude, frequency, and phase errors. The demodulated signal is a signal in which the transmitted signal changes phase with respect to the local carrier. The carrier may be tracked for a while, Cloud Tranceiver select the data, Cloud Tranceiver and then track it. Therefore, the design needs to be prepared for partial data loss. Cloud Tranceiver To this end, the data is transmitted as a packet. Can repeatedly transmit multiple packets, rather than the entire data.
The receiver also supports statistical counters, such as the number of received, discarded, or corrected packets. These counters are used to measure and monitor performance metrics, Cloud Tranceiver including bit error rate and effective data rate.
All in all, Cloud Tranceiver the data is sent and received as a packet in serial form. Packets carry preamble and CRC. The data is modulated and demodulated by BPSK on the intermediate quadrature signal before the transceiver device. Thus, the intermediate signal frequency and the bit rate of the data are one eighth of the sampling rate.