NB-IoT UE Power Control for Dense Small Cell Interference
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Solution Overview
Problem
Narrowband Internet-of-Things (NB-IoT) systems face challenges in dense small cell deployments due to UL/DL link imbalance, leading to reduced downlink coverage and increased inter-cell interference, particularly in scenarios where base stations have lower power compared to macro-cells.
Innovation Solution
The implementation of techniques that allow NB-IoT user equipment (UE) to adjust transmit power based on system information messages, device class, and detected coverage level, including parameters like P_O_NPUSCH and alpha values, to optimize power control and reduce inter-cell interference while maintaining battery life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by stationary object
If base stations in dense small cell deployments operate with lower power compared to macro-cells, then device complexity and energy consumption are reduced, but downlink coverage is degraded and inter-cell interference increases
Solution Approach 1:
The patent changes the power control parameters (P_O_NPUSCH and alpha) dynamically based on coverage level detection. UEs in different coverage levels (DL_CL_UL_CL pairs) are assigned different parameter sets, allowing base stations to operate at lower power while maintaining adequate coverage and reducing interference through optimized power adjustment factors
Solution Approach 2:
The system implements dynamic power control where UEs detect their coverage level and report it to the network. The network then adjusts power control parameters dynamically based on the reported coverage level, enabling adaptive power management that reduces interference while maintaining coverage for low-power small cell operations
2Use of energy by stationary object
If base stations in dense small cell deployments operate with lower power compared to macro-cells, then operational costs are reduced, but downlink coverage is degraded
Solution Approach 1:
The patent applies parameter changes by adjusting power control parameters (P_O_NPUSCH and alpha) based on detected coverage levels. This allows the system to extend downlink coverage area through optimized power control without requiring increased base station transmit power, enabling cost-effective small cell deployment
Solution Approach 2:
The system employs feedback mechanisms where UEs detect and report their coverage level to the network. This feedback enables the network to adjust power control parameters appropriately, ensuring adequate downlink coverage is maintained even when base stations operate at lower power levels
3Area of stationary object
If transmit power is increased to improve downlink coverage, then coverage area is expanded, but inter-cell interference increases
Solution Approach 1:
The patent changes power control parameters based on coverage level detection rather than simply increasing transmit power. By adjusting the alpha parameter (power control adjustment factor) and P_O_NPUSCH (nominal power) according to detected coverage levels, the system achieves adequate coverage while controlling interference through precise power management
Solution Approach 2:
The system applies local quality by providing different power control parameters to UEs in different coverage levels. Instead of uniform power increase across all cells, each UE receives customized power control parameters based on its specific coverage conditions, achieving local optimization that balances coverage and interference
Data Source
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AI summary
An apparatus of a Narrowband Internet-of-Things (NB-IoT) user equipment (UE) includes processing circuitry. To configure the NB-IoT UE for open loop transmit power control, the processing circuitry is to decode a narrowband system information block (NB-SIB) to obtain a narrowband physical random access channel (NPRACH) resource set and power control information associated with the NPRACH resource set. A random access channel (RACH) preamble is encoded for transmission with or without repetitions to a base station during a RACH procedure and using the NPRACH resource set. The transmission has transmission power based on the power control information. A narrowband uplink resource assignment received during the RACH procedure is decoded. A connection setup completion message is encoded for transmission to the base station using the narrowband uplink resource assignment.