Asymmetric Modulation for Nonuniform Systematic Bits
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Solution Overview
Problem
Existing wireless communication systems face performance loss when modulating nonuniform source bits using systematic codes, as they assume uniform distribution, leading to inefficiencies.
Innovation Solution
Implement asymmetric modulation schemes for nonuniform systematic bits, mapping higher probability bits to lower energy points and lower probability bits to higher energy points on the constellation graph, while uniformly modulating parity bits, and transmitting an indication of the empirical distribution to the receiver.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If symmetric modulation is used for nonuniform source bits, then the modulation process is simple, but performance loss occurs due to mismatch with nonuniform distribution
Solution Approach 1:
The patent applies asymmetry by using different modulation schemes for systematic bits and parity bits. Specifically, asymmetric modulation is applied to nonuniform systematic bits while symmetric modulation (e.g., QPSK) is used for uniformly distributed parity bits. This resolves the contradiction by adapting the modulation approach to the statistical properties of different bit types, improving performance without excessive complexity
Solution Approach 2:
The patent implements local quality by applying different modulation strategies to different parts of the coded data. Systematic bits, which have nonuniform distribution, receive asymmetric modulation treatment, while parity bits with uniform distribution use symmetric modulation. This localized approach optimizes each component according to its specific characteristics
2Productivity
If asymmetric modulation is applied to nonuniform systematic bits, then communication efficiency is improved, but device complexity increases
Solution Approach 1:
The patent segments the coded data into two distinct parts: systematic bits and parity bits. Each segment is then modulated using an appropriate scheme based on its statistical properties. This segmentation allows asymmetric modulation to be applied only where needed (to systematic bits) rather than to the entire data stream, limiting the increase in complexity
3Reliability
If higher probability bits are mapped to lower energy points, then error rate is reduced, but energy distribution becomes asymmetric
Solution Approach 1:
The patent changes the modulation parameters specifically for systematic bits by using asymmetric modulation that maps higher probability bits to lower energy constellation points. This parameter adaptation reduces the error rate for the more frequent bit values while accepting asymmetric energy distribution as a necessary trade-off for improved reliability
Data Source
AI summary
Methods, systems, and devices for wireless communications are described. A user equipment (UE) generates multiple systematic bits for a message, where the systematic bits are nonuniformly distributed over a time period such that a first bit value has a first probability of occurrence during the time period and a second bit value has a second probability that is greater than the first probability of the occurrence. The UE modulates the systematic bits according to an asymmetric modulation rule such that the first bit value corresponds to a first constellation point on a constellation graph and the second bit value corresponds to a second constellation point that is relatively closer to a center of the constellation graph than the first constellation point based on the second probability being greater than the first probability. The UE transmits the message including systematic bits modulated according to the asymmetric modulation rule.