Outage-Based OLPC for Faster Initial Convergence
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Solution Overview
Problem
The existing outer loop power control methods in WCDMA-based cellular networks, particularly the BLER-Based OLPC, suffer from slow initial convergence, leading to increased interference and reduced system capacity, especially in discontinuous transmission services where the communication channel is used intermittently.
Innovation Solution
The proposed method employs an Outage-Based OLPC approach, where the target signal-to-interference ratio (SIRtarget) is calculated as the sum of two components: SIRoutage-tgt and SIRBLER-tgt, with SIRoutage-tgt set to a high initial value and SIRBLER-tgt based on previous transmission values, allowing for faster initial convergence by resetting these values at the start of each transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If BLER-Based OLPC is used to determine target SIR, then communication reliability is improved, but initial convergence speed deteriorates
Solution Approach 1:
The patent applies preliminary action by pre-determining the initial target SIR value based on outage probability calculations before transmission begins. Instead of starting with a conservative high value and slowly converging, the system pre-calculates an optimal initial target SIR that accounts for fading conditions and interference levels, enabling faster convergence while maintaining reliability from the start of transmission.
2Reliability
If high target SIR is maintained during initial convergence, then communication security is improved, but system capacity deteriorates due to increased interference
Solution Approach 1:
The patent applies dynamics by making the target SIR adaptive rather than static. The system dynamically adjusts the target SIR based on real-time measurements of interference levels, fading conditions, and outage probability. This allows the target SIR to be high enough to ensure security when needed but lower when conditions permit, thereby maximizing system capacity while maintaining communication security.
Solution Approach 2:
The patent changes the parameter of target SIR from a fixed conservative value to a dynamically calculated value based on outage probability. By changing how the target SIR is determined (from BLER-based to outage-based with pre-calculation), the system achieves both security and capacity improvement by optimizing the parameter according to actual channel conditions rather than using a static conservative approach.
3Reliability
If slow convergence is used to ensure secure communication, then reliability is improved, but loss of time increases
Solution Approach 1:
The patent eliminates convergence time loss by performing the target SIR calculation in advance based on outage probability. The initial target SIR is pre-determined before transmission starts, so no time is lost during transmission for gradual convergence. The system achieves secure communication immediately by using the pre-calculated optimal target SIR rather than slowly converging from a conservative initial value.
Data Source
AI summary
An adjustment of the target signal to interference ratio (SIRtarget) at the start of each transmission (N) uses an Outage-Based OLPC method, which establishes the ratio (SIRtarget) as the sum of a first component (SIRoutage-tgt) that adjusts quickly to the conditions of the communications channel and a second component (SIRBLER-tgt) that is adjustable according to a target block error rate (BLERtarget) The stored values of the two components (SIRoutage-tgt, SIRBLER-tgt) in at least one prior transmission (N−1) are used obtain convergence of the target ratio (SIRtarget) by setting the initial value in the transmission (N) for the first component (SIRoutage-tgt) equal to a value higher than the average values for the first component (SIRoutage-tgt) and setting the initial value in said transmission (N) for the second component (SIRBLER-tgt) and setting the initial value in said transmission (N) for the second component (SIRBLER-tgt) equal to the average of the values of the second component (SIRBLER-tgt).