Multi-Stage Demodulator for Symbol Block Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing symbol block detection methods in DS-CDMA and non-spread systems face challenges with intersymbol interference (ISI) due to dispersive channels and MIMO transmission, leading to high computational complexity, especially in systems like HSPA and LTE, where maximum likelihood detection becomes impractical due to the large number of possible symbol combinations.
Innovation Solution
Incorporating a decoder into the Multi-Stage arbitration (MSA) process to produce modem bit likelihood values, which are used to construct candidate symbol values, reducing the number of combinations to be considered and thereby decreasing computational complexity through stages of detection assistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If maximum likelihood detection is used to detect symbol blocks, then detection accuracy is improved, but computational complexity becomes prohibitively large
Solution Approach 1:
The detection process is divided into multiple stages: a first stage performs initial detection assistance to identify candidate symbol values, and a second stage performs final detection using reduced candidate combinations. This segmentation reduces computational complexity while maintaining detection accuracy by processing symbol blocks in manageable stages rather than evaluating all possibilities simultaneously.
Solution Approach 2:
The first stage of detection assistance performs preliminary identification of candidate symbol values before the final detection stage. By pre-filtering and identifying the most likely candidate symbol values in advance, the system reduces the search space for the second stage, thereby reducing overall computational complexity while preserving accuracy.
2Device complexity
If the number of candidate symbol combinations is reduced, then computational complexity is decreased, but detection reliability may be compromised
Solution Approach 1:
The detection process uses feedback from the first stage to guide the second stage. The first stage identifies candidate symbol values and this information feeds back to constrain the second stage's search space. This feedback mechanism ensures that the reduced candidate combinations in the second stage are still reliable candidates, maintaining detection reliability while reducing complexity.
Solution Approach 2:
The first stage performs preliminary identification of the most likely candidate symbol values before the final detection. This preliminary action filters out unlikely combinations in advance, ensuring that the reduced set of candidates considered in the second stage maintains high reliability, thus balancing complexity reduction with accuracy preservation.
Data Source
AI summary
Teachings presented herein offer a technique for using a demodulator to improve a demodulation process. For example, a demodulation unit according to an embodiment of the present invention may be a multi-stage demodulator and may include: a demodulator configured to receive a baseband signal and configured to produce modem bit likelihood values based on the received baseband signal; a decoder configured to receive and process the modem bit likelihood values to produce improved modem bit likelihood values; a candidate value generator configured to produce, based on the improved modem bit likelihood values, candidate symbol values for a group of one or more symbols; and a detector configured to receive the baseband signal and the candidate symbol values and configured to produce one of (a) final modem bit estimates and (b) candidate symbol values for a group of symbols.