Distributed-Antenna RACH Power Offset for Accurate Pathloss Estimation
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Solution Overview
Problem
In antenna-distributed networks, conventional PRACH UL power control methods based on co-located antenna assumptions lead to inaccurate pathloss estimation and poor RACH performance due to varying reception capabilities of distributed antennas, resulting in inefficient UE Tx power and interference issues.
Innovation Solution
Introduce a new parameter in the RAR (Msg-2) indicating a reduced total Tx power for antenna-distributed networks, allowing UEs to adjust their Msg-3 transmission power based on this indicator, and enabling the gNB to determine a subset of antenna nodes for Msg-2 transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional PRACH UL power control methods based on co-located antenna assumptions are used, then the pathloss estimation is simplified, but the RACH performance deteriorates due to inaccurate pathloss estimation in antenna-distributed networks
Solution Approach 1:
The patent introduces a new parameter 'ra-PowerOffset' in the RAR message to compensate for the power difference between co-located and distributed antenna scenarios. This parameter adjustment allows the UE to correct its transmit power calculation based on the actual distributed antenna configuration, resolving the contradiction between simplified estimation and accurate performance.
2Ease of operation
If UE transmits Msg-3 using conventional power control calculations, then the transmission process is straightforward, but uplink interference increases due to inefficient power control
Solution Approach 1:
The gNB provides feedback through the 'ra-PowerOffset' parameter in the RAR message, enabling the UE to adjust its Msg-3 transmit power accordingly. This feedback mechanism allows the system to maintain simple operation for the UE while dynamically optimizing power levels to reduce uplink interference in distributed antenna networks.
3Area of stationary object
If all antenna nodes transmit Msg-2 with full power, then the coverage is maximized, but the uplink interference from subsequent Msg-3 transmissions increases
Solution Approach 1:
The patent dynamically adjusts the 'ra-PowerOffset' parameter based on the actual subset of antenna nodes used for Msg-2 transmission. When fewer antenna nodes transmit Msg-2, the offset is reduced, leading to lower Msg-3 transmit power from the UE. This resolves the contradiction by adapting the power parameters to the actual transmission configuration, maintaining coverage while reducing interference.
Data Source
AI summary
Improved techniques of include performing random access in an antenna-distributed network include introducing a new parameter, as reduced Tx power indicator, in the RAR of Msg-2 that indicates a reduced total Tx power of all antenna nodes of the antenna-distributed network. When the gNB receives a Msg-1, the gNB determines a subset of the distributed antenna nodes to which the gNB will send the RAR in the Msg-2 with the reduced total Tx power needed to transmit the Msg-2 to only those antenna nodes in the subset. The RAR includes a new parameter indicating the reduced total Tx power used to transmit the RAR to the UE. The UE then uses the value of the new parameter to estimate a pathloss for the Msg-3 and PUSCH transmission.