Outer-loop power control using maximum likelihood decoding
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Solution Overview
Problem
Wireless communication systems face challenges in detecting and identifying packets on burst-oriented rate indicator channels with high probability, especially in systems where conventional cyclical redundancy check (CRC) methods incur significant overhead, making it difficult to accurately identify good and bad frames and adjust power control loops effectively.
Innovation Solution
The implementation of a method using a maximum likelihood decoder to analyze the presence of packets on the rate indicator channel, determining packet validity based on likelihood thresholds, and confirming with the corresponding burst-oriented data channel, allowing for low overhead and high probability identification of frames, even in sporadic transmission scenarios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cyclical redundancy check (CRC) is used for error detection on rate indicator channel, then error detection capability is improved, but transmission overhead increases significantly
Solution Approach 1:
The patent extracts the error detection function from the data channel and implements it separately on the rate indicator channel using parity bits. Instead of appending full CRC bits to every data transmission, the system calculates parity based on the data rate information and transmits only the parity result on the rate indicator channel, thereby separating the error detection mechanism from the main data payload.
Solution Approach 2:
The patent changes the error detection parameter from full CRC (8-10 bits) to simplified parity bits (1 bit). This parameter change reduces the overhead from 8-10 bits per transmission to just 1 bit, while still providing sufficient error detection capability for the rate indicator channel's control information.
2Reliability
If CRC bits are appended to each data transmission on rate indicator channel, then error detection probability is improved, but transmission power increases significantly
Solution Approach 1:
The patent extracts only the essential error detection function (parity check) from the full CRC mechanism, transmitting only the parity result on the rate indicator channel. This extraction reduces the number of bits requiring transmission power from 8-10 bits to just 1 bit, significantly reducing power consumption while maintaining adequate error detection for control information.
Solution Approach 2:
The patent applies partial error detection using only parity bits rather than full CRC, which is sufficient for the rate indicator channel's control information. This partial action provides adequate error detection probability for detecting bad frames while avoiding the excessive power consumption of full CRC implementation.
3Measurement precision
If maximum likelihood decoding is used to detect packets on rate indicator channel, then packet detection accuracy is improved, but computational complexity increases
Solution Approach 1:
The patent segments the decoding process into two stages: first decoding the rate indicator channel to obtain the data rate, then using that rate information to guide decoding of the main data channel. This segmentation allows maximum likelihood decoding to be applied selectively and efficiently, improving packet detection accuracy without requiring full maximum likelihood decoding of the entire transmission.
Solution Approach 2:
The patent performs preliminary decoding of the rate indicator channel before decoding the main data channel. By first obtaining the data rate information through maximum likelihood decoding of the rate indicator, the system prepares the necessary parameters for subsequent data decoding, improving overall detection accuracy while distributing computational complexity across two simpler stages rather than one complex stage.
Data Source
AI summary
Systems and methods for evaluating packets and frames in a wireless communication system having multiple reverse-link channels including a spontaneous, burst oriented transmission channel and its corresponding rate indicator channel. One embodiment comprises a base station monitoring the rate indicator channel, decoding the rate indicator channel using a maximum likelihood decoder and detecting the presence of a packet on the rate indicator channel by comparing a likelihood with a threshold, and analyzing the validity of a frame on the burst oriented channel based on the presence and content of packets received on the rate indicator channel.