Outer Loop Power Control Threshold Using Pilot Channel
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Solution Overview
Problem
Existing communication systems face challenges in reliably determining the packet error rate (PER) on traffic channels, especially during bursty data transmissions or when the PER is very small, which affects outer loop power control and channel quality.
Innovation Solution
The method involves determining an outer loop power control threshold for a traffic channel based on selected outputs from other channels, such as the pilot channel, to estimate the packet error rate and set appropriate power control settings, even when direct measurement from the traffic channel is not possible.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If direct counting techniques are used to determine PER, then the measurement is simple, but the PER determination is unreliable during bursty transmissions or when PER is very small
Solution Approach 1:
The patent uses a pilot channel as an intermediary to estimate traffic channel PER when direct measurement is unreliable. The pilot channel provides a reference signal that can be used to infer traffic channel conditions through signal-to-noise ratio measurements, solving the problem of unreliable PER determination during bursty transmissions or very low PER conditions
Solution Approach 2:
The patent creates a model or estimate of the traffic channel PER by using pilot channel measurements. Instead of directly measuring traffic channel PER in difficult conditions, the system copies the measurement approach from the pilot channel, which has more continuous and reliable signal availability
2Reliability
If outer loop power control threshold is adjusted to maintain target PER, then service quality is improved, but transmit power increases
Solution Approach 1:
The patent implements outer loop power control by continuously monitoring actual PER and adjusting the power control threshold accordingly. When PER exceeds the target, the threshold is increased to improve service quality; when PER is below target, the threshold is decreased to reduce transmit power, creating a feedback loop that balances quality and energy consumption
3Reliability
If more sub-packets are transmitted in incremental redundancy, then error correction capability is improved, but transmission time increases
Solution Approach 1:
The patent uses incremental redundancy where the transmitter sends an original coded packet first, and only transmits additional redundant sub-packets if the initial transmission is not successfully decoded. This partial action approach provides error correction capability only when needed, avoiding unnecessary transmission time for packets that are successfully received on the first attempt
Data Source
AI summary
Outer loop power control for a traffic channel includes using at least one output from another channel to determine an appropriate control threshold such as a signal-to-noise ratio when selected channel conditions exist. One example traffic channel condition comprises having insufficient data transmission to provide a direct measurement of packet error rate. Another example traffic channel condition used to determine when to use the other channel output is a transmission mode on the traffic channel. An example output used for setting the control threshold is a chip energy to noise ratio of a pilot channel associated with the traffic channel.