Base Station Reference Signal Null Subcarrier Interference Rejection
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Solution Overview
Problem
In 5G systems, low Signal to Noise Ratio (SNR) or Signal to Interference plus Noise (SINR) on received reference signals hinders reliable channel estimation, leading to ineffective uplink coverage due to increased inter-cell interference, which existing techniques struggle to mitigate effectively.
Innovation Solution
The method involves signaling antenna port numbers to user equipment (UE) for reference signal transmission, allowing base stations to estimate channel parameters using occupied subcarriers and interference parameters from null subcarriers, thereby reducing inter-cell interference through targeted port signaling and equalization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If maximum transmit power is increased to improve uplink coverage, then coverage range is extended, but inter-cell interference increases
Solution Approach 1:
The patent applies local quality by differentiating the treatment of subcarriers into occupied subcarriers (for channel estimation) and null subcarriers (for interference measurement). This localized differentiation allows the system to measure and compensate for inter-cell interference specifically on null subcarriers while maintaining normal transmission on occupied subcarriers, thereby addressing interference without reducing overall transmit power.
Solution Approach 2:
The patent changes the parameter of subcarrier allocation by introducing null subcarriers alongside occupied subcarriers. This parameter change enables the base station to obtain interference measurements from null subcarriers and apply interference rejection combining, effectively reducing inter-cell interference while maintaining maximum transmit power for coverage extension.
2Adaptability or versatility
If DMRS configuration is changed to support more layers, then MIMO capability is improved, but interference from other cells increases
Solution Approach 1:
The patent applies preliminary action by measuring interference on null subcarriers before data detection. The base station uses the measured interference parameters from null subcarriers to construct interference rejection combining weights, which are then applied to eliminate interference in the received signal. This preliminary interference measurement and compensation enable higher MIMO layers to be supported with reduced inter-cell interference impact.
3Measurement precision
If SNR on received reference signal is low, then channel estimation reliability deteriorates, but increasing transmit power increases interference
Solution Approach 1:
The patent introduces null subcarriers as an intermediary element that enables indirect measurement of interference conditions. By measuring interference on null subcarriers (which carry no data but experience the same interference environment), the system can compensate for low SNR conditions in occupied subcarriers without increasing transmit power, thus improving channel estimation reliability while avoiding additional interference.
Data Source
AI summary
Embodiments of the present disclosure relate to a base station (BS) and method for communication in a communication network. The method comprising signaling at least one antenna port number from multiple antenna port numbers to a UE. Also, the method comprises receiving a data and a reference signal (RS) corresponding to the UE. The data and the RS are received on one or more receive antennas of the BS, wherein the RS comprises occupied RS subcarriers and null subcarriers. A location of occupied RS subcarriers and null subcarrier positions are selected according to signaled antenna port. Next, channel parameters are estimated using the occupied subcarriers associated with the received RS, and interference plus noise parameters using the null subcarriers. Thereafter, equalizing the received data on the receive antennas using the measured channel parameters and the interference plus noise parameters for interference rejection and data detection.