Realtime power monitoring of wireless communication systems for high data rate links – first results
Fig. 1: Overall D-band system.
Fig. 2: Setup for measurements of the dissipated power per component.
Fig. 3: EVM and ACPR versus power consumption of the IF system. Not included is the power consumption of the modems.
Increasing demand for high data rate transmission via wireless communication infrastructure entails increasing power consumption beyond acceptable limits. Power-efficient operation of wireless communications infrastructure at D-band (110 – 170 GHz) and beyond has a strong impact on future wireless communication architectures. We are developing and validating a high data rate modular wireless transmission system at D-band, as depicted in Fig. 1. A transceiver system in the 60 GHz band as an intermediate frequency (IF) for the D-band system has been realized and studied for agile power reduction capabilities (see Fig. 2).
The system enables real-time monitoring of power consumption of each component. This allows for optimizing the power dissipation without trade-off in performance. The wireless system is designed around up to 10 WLAN modems operating on the IEEE 802.11ac standard with orthogonal frequency-division multiplexing (OFDM) to adapt to nonidealities of the wireless channel exploiting as much channel capacity as possible. Power monitoring was implemented for each component supply voltage terminal with an update rate of 300 µs.
We achieved first results on the impact of power dissipation of individual components on overall system performance in lab environment. Fig. 3 illustrates that the power consumption of the entire transceiver system can be reduced by 14.5 % providing error vector magnitude of 2.36 % and adjacent channel power ratio of −46.9 dBc while maintaining the initial link budget of the system. The study revealed that substantial power reduction can be achieved by dynamic adjustment of the DC supply voltages for the frequency multipliers and RF 60 GHz variable gain amplifiers inside the MMICs of the IF chain without affecting dramatically the overall performance of the wireless link budget. The power savings on other components were minor or directly impacted the performance and hence could not be realized.
This important result provides a means of monitoring and optimizing the modulation scheme and data rates with low latency at component level. The study can also be employed to analyse different wireless system architectures because the real-time power monitoring is performed on each individual component functionality. In the current version, a 10 Gbps data rate is envisaged, but can be scaled to higher values. In the next step, the full D-band system will be tested and transferred to a field study.