Lattice-Partition NOMA Base Station Power Allocation
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Solution Overview
Problem
Existing wireless communication systems face challenges in achieving high sum capacity performance in lattice-partition (LP)-based downlink non-orthogonal multiple access (NOMA) due to impractical continuous Gaussian input signals and increased decoding complexity and delay in user equipment (UE) receivers.
Innovation Solution
A base station configured with a processor and transceiver modulates bits of strong and weak UE differently, allocating varying transmission powers to most significant bits (MSBs) and least significant bits (LSBs) to optimize power distribution, allowing for higher sum capacity without successive interference cancellation (SIC) at UE receivers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If continuous Gaussian input signals are used at the base station to achieve theoretical capacity region, then sum capacity performance is improved, but practical implementation becomes infeasible
Solution Approach 1:
The patent transforms the continuous Gaussian input signals into discrete lattice partition-based signals by changing the signal parameter domain from continuous to discrete. This allows the system to achieve near-theoretical capacity while enabling practical implementation through discrete signal processing at the base station.
Solution Approach 2:
The patent employs practical discrete modulation schemes that can be implemented with standard communication hardware, replacing the idealized continuous Gaussian signals. This substitution maintains acceptable performance while enabling real-world deployment with available technology.
2Measurement precision
If successive interference cancellation (SIC) is applied at UE receivers to decode desired message signals, then decoding accuracy is improved, but decoding complexity and delay increase
Solution Approach 1:
The patent extracts and eliminates the need for SIC by using lattice partition-based NOMA where UEs can directly decode their intended signals without requiring complex interference cancellation procedures. This removes the harmful complexity while preserving decoding accuracy.
Solution Approach 2:
Instead of using SIC to cancel interference after reception, the patent inverts the approach by designing the modulation scheme such that interference is inherently managed through lattice partitioning, allowing direct decoding without sequential interference cancellation steps.
3Measurement precision
If SIC is applied at UE receivers to achieve desired message signals, then decoding performance is improved, but decoding delay increases
Solution Approach 1:
The patent performs preliminary signal processing and power allocation at the base station using lattice partitioning, so that UEs receive pre-processed signals that can be decoded directly without requiring time-consuming SIC operations at the receiver side.
Data Source
AI summary
The invention discloses a base station and a modulation method supporting lattice-partition-based downlink non-orthogonal multiple access. The modulation method includes: modulating at least one most significant bit (MSB) of weak user equipment (UE) into a first signal with first transmission power; modulating at least one least significant bit (LSB) of the weak UE into a second signal with second transmission power, where the second transmission power is less than the first transmission power; and modulating at least one second MSB of strong UE into a third signal with third transmission power, where the third transmission power is between the first transmission power and the second transmission power.