Power Allocation for 6G Sub-Networks in Industrial Wireless Control

The concept of sub-networks has been recently identified as an important component of 6G to enable high-demanding critical services with capabilities of hyper reliable low-latency communications (HRLLC) at the local area of the sub-network. In this paper, we formulate the power control problem for sub-networks as finding the transmit power vector, corresponding to the sub-networks, to minimize the sum interference-to-signal power ratios across all the sub-networks. We propose then a heuristic sequential iterative power allocation (SIPA) and an optimal power allocation based on gradient descent-based algorithm (GDPA). Extensive system simulations validated the proposed methods. In particular, the SIPA achieves significant performance gains over the fixed transmit power setting, with limited performance loss over the GDPA. In most cases, the proposed methods outperform the max-min power allocation with much lower feedback signaling overhead and complexity. Furthermore, to keep 99.9% of all the sub-network link instances to achieve reliability of 6 nines, the SIPA can save radio resources by about 27% compared to the fixed transmit power setting.