Uplink Traffic Load Control via Path Loss Estimation
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Solution Overview
Problem
Conventional CDMA-based wireless mobile communication systems face limitations in controlling uplink traffic load, especially in multi-carrier systems, where existing methods like ROT index cannot be applied, leading to interference and inefficiencies in power control.
Innovation Solution
A method and system for controlling uplink traffic load in a multi-cell wireless mobile communication system by dividing the full frequency band into sub-frequency bands, where mobile stations estimate path loss values from both home and neighbor cells, and base stations allocate appropriate transmission power and data rates to minimize interference and optimize system capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If ROT index-based power control is used in conventional CDMA systems, then uplink power control can be performed, but the method cannot be applied to multi-carrier communication systems and requires MS to stop transmission for measurement
Solution Approach 1:
The patent changes the measurement parameter from ROT index (which requires transmission stop) to path loss estimation based on reference signal reception. The MS estimates path loss by comparing received reference signal power with transmitted power information, allowing continuous transmission while obtaining necessary measurement data.
Solution Approach 2:
The patent introduces reference signals as an intermediary measurement target. Instead of measuring thermal noise directly by stopping transmission, the MS measures reference signal power from the BS, which serves as an intermediary to derive path loss information without interrupting normal uplink transmission.
2Reliability
If MS transmits at high power to overcome path loss, then signal reception at BS is improved, but interference to other MS signals increases
Solution Approach 1:
The patent implements feedback-based path loss compensation. The MS estimates path loss and reports it to the BS, which then provides uplink power control commands adjusted for the estimated path loss. This feedback loop allows the MS to transmit at appropriate power levels that compensate for path loss without causing excessive interference to other users.
Solution Approach 2:
The patent applies local path loss compensation where each MS estimates its own specific path loss to its serving BS and receives individualized power control commands. This localized approach allows each user to optimize its transmission power independently based on its specific channel conditions, improving reception quality without causing uniform interference across all users.
3Productivity
If frequency bands are divided into sub-frequency bands with neighbor cell reuse, then system capacity is improved, but interference between cells increases
Solution Approach 1:
The patent changes the interference management parameter from power control alone to path loss-based power control. By estimating path loss using reference signals and incorporating this information into power control decisions, the system can better manage interference in frequency reuse scenarios, allowing higher system capacity while controlling inter-cell interference through more precise power adjustment.
Data Source
AI summary
A method is provided for controlling an uplink traffic load in a wireless mobile communication system. A mobile station (MS) receives a reference signal from each of a base station (BS) of its home cell and a BS of a neighbor cell; calculates a power difference between the received reference signals to estimate a path loss value for each individual BS, and reports the estimated path loss value to the BS of the home cell. The BS of the home cell receives the estimated path loss value for each individual BS from the MS; and determines and allocates uplink traffic transmission power and a data rate to the MS taking the estimated path loss value into consideration. The MS transmits an uplink traffic signal taking into account the uplink traffic transmission power and the data rate allocated from the BS of the home cell.