Abstract
Beamforming methods need to be critically evaluated and improved to achieve the promised performance of millimeter wave (mmWave) 5G NR in high mobility applications like Vehicle-to-Everything (V2X) communication. Conventional beam management methods developed for higher frequency applications do not directly carry over to the 28 GHz mmWave regime, where propagation and reflection characteristics are vastly different. Further, real system deployments and tests are required to verify these methods in a practical setting. In this work, we develop mMobile, a custom 5G NR compliant mmWave testbed to evaluate beam management algorithms. We describe the architecture and challenges in building such a testbed. We then create a novel, low-complexity beam tracking algorithm by exploiting the 5G NR waveform structure and evaluate its performance on the testbed. The algorithm can sustain almost twice the average throughput compared to the baseline.
Testbed Architecture
We show that mMobile is well designed and can support 5G NR specifications. We established a link with 240 kHz subcarrier spacing with a bandwidth of 50 MHz. The radiated transmit power is fixed to an EIRP of 30 dBm. We demonstrate that \name can support a high throughput link with up to 256-QAM constellation with the bit error rate as low as 0.0022 without channel coding. We have also verified that our FPGA baseband platform can be used as gNB with high bandwidth of 400 MHz required for 5G NR. Finally, we show that our phased array module can produce the desired beam patterns when measured in an anechoic chamber.