Transmission Power Offset Arbitration in Soft Handoff
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Solution Overview
Problem
Conventional mobile communication systems face challenges in rapidly controlling the transmission rate of uplink user data due to increased processing load and delay in radio network controllers, leading to inefficient data transmission during burst data, resulting in low-speed, high-delay, and wasted radio bandwidth and hardware resources.
Innovation Solution
A transmission power control method that notifies radio base stations of offsets between the transmission power of relative transmission rate control channels and dedicated physical channels, allowing for dynamic adjustment of transmission power during soft-handover to ensure reliable communication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the radio network controller integrally controls multiple radio base stations to determine transmission rates, then the transmission rate can be adjusted according to hardware resources and radio resources, but the processing load and processing delay in the radio network controller increase, making fast control (per 1-100ms) difficult
Solution Approach 1:
The patent segments the transmission rate control function from the radio network controller to the radio base station level. Each radio base station independently controls transmission rates for its served mobile stations, eliminating the need for centralized processing of fast rate adjustments. This segmentation enables fast control (1-100ms) at the edge of the network while reducing the processing load on the radio network controller to only slow-rate adjustments (few hundred ms to few seconds).
Solution Approach 2:
The patent introduces a two-layer control architecture: a slow control layer at the radio network controller for strategic resource allocation, and a fast control layer at the radio base station for tactical transmission rate adjustments. This dimensional separation of control speeds allows the system to achieve fast response times without overburdening the central controller.
2Device complexity
If transmission rate control is performed slowly (few hundred ms to few seconds) to reduce processing load, then the radio network controller can handle the control functions, but burst data transmission suffers from low speed and high delay
Solution Approach 1:
The patent divides control functions into two time scales: slow control (few hundred ms to few seconds) remains at the radio network controller for resource allocation, while fast control (1-100ms) is delegated to radio base stations for immediate transmission rate adjustments. This segmentation enables burst data to be handled quickly without increasing the processing load on the radio network controller.
Solution Approach 2:
The radio network controller performs preliminary resource allocation and configuration before burst traffic occurs, setting up the framework for fast control. When burst data arrives, the radio base station can immediately adjust transmission rates within the pre-configured parameters without waiting for controller intervention, thus reducing transmission delay.
3Speed
If radio resources are reserved for high-speed communications to enable fast transmission rate control, then burst data can be transmitted efficiently, but radio bandwidth resources and hardware resources in the radio base station are wasted during low-traffic periods
Solution Approach 1:
The patent implements dynamic transmission rate control at the radio base station, allowing transmission rates to be adjusted in real-time (1-100ms) based on actual traffic conditions. During burst data transmission, high transmission rates are activated; during low-traffic periods, rates are reduced or resources are released. This dynamic adjustment eliminates the need for permanent resource reservation, avoiding waste while enabling fast transmission when needed.
Solution Approach 2:
The system changes transmission rate parameters dynamically based on traffic demand. The radio base station monitors traffic conditions and adjusts transmission rate parameters (e.g., modulation scheme, coding rate, resource block allocation) in real-time. This parameter flexibility allows the system to achieve high-speed transmission during bursts while conserving resources during idle periods.
4Reliability
If the mobile station performs soft-handover with multiple cells, then communication reliability is improved, but the transmission power of the relative transmission rate control channel cannot be properly controlled, causing the control channel to fail to reach the mobile station
Solution Approach 1:
The patent implements feedback mechanisms where the mobile station measures the reception quality of the relative transmission rate control channel from each serving cell during soft-handover. Based on these measurements, the mobile station provides feedback to the radio base station, which then adjusts the transmission power of the control channel. This closed-loop feedback ensures the control channel reaches the mobile station reliably even during handover between multiple cells.
Solution Approach 2:
The system dynamically changes transmission power parameters of the relative transmission rate control channel based on soft-handover conditions. When the mobile station is in soft-handover with multiple cells, the serving radio base station adjusts the control channel power parameter to compensate for path loss and interference, ensuring reliable reception. This parameter adaptation maintains control channel reliability throughout the handover process.
Data Source
AI summary
A transmission power control method for controlling a transmission power of an E-RGCH for uplink user data transmitted from a cell controlled by a radio base station to a mobile station, includes: notifying, from a radio network controller to at least one radio base station controlling a first cell and a second cell, offsets between the transmission power of the E-RGCH and a transmission power of a DPCH, when a mobile station is performing a soft-handover with the first and second cell; determining, at the first cell, a transmission power of a first E-RGCH based on a notified offset, and transmitting the first E-RGCH to the mobile station using the determined transmission power; and determining, at the second cell, transmission power of a second E-RGCH based on a notified offset, and transmitting the second E-RGCH to the mobile station using the determined transmission power.