NOMA-HARQ Power Optimization for Spectral Efficiency
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Solution Overview
Problem
Current 5G specifications do not effectively address spectral efficiency in Hybrid Automatic Repeat Request (HARQ) feedback, particularly for low latency applications, leading to inefficiencies in resource allocation and increased power consumption.
Innovation Solution
The implementation of Non-Orthogonal Multiple Access (NOMA)-HARQ, which schedules new incoming packets alongside retransmissions on the same physical resources, using power optimization to ensure reliability and reduce resource usage, by leveraging power domain differentiation and successive interference cancellation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If new packets and retransmissions are scheduled on separate physical resources (orthogonal multiple access), then reliability is maintained, but spectral efficiency deteriorates and power consumption increases
Solution Approach 1:
The patent merges new packet transmissions and retransmissions onto the same physical time-frequency resources, allowing simultaneous transmission of multiple packets to different users. This non-orthogonal scheduling approach combines resources that were previously allocated separately, thereby improving spectral efficiency while maintaining reliability through power domain separation and successive interference cancellation
Solution Approach 2:
The patent transitions from orthogonal resource allocation (separate time-frequency resources) to non-orthogonal allocation by introducing power domain differentiation as an additional dimension. Users are separated not by time or frequency but by their allocated power levels, enabling multiple users to share the same time-frequency resources while maintaining distinguishable signals through power optimization
2Reliability
If retransmissions are performed with dedicated resources, then reliability is ensured, but latency increases and power consumption increases
Solution Approach 1:
The patent enables continuous utilization of physical resources by allowing new packets to be transmitted in the same resources allocated for retransmissions. Instead of dedicating resources exclusively to retransmissions (which would leave them idle when no retransmissions are needed), the system continuously uses these resources for both retransmissions and new transmissions, reducing latency and improving resource utilization
Solution Approach 2:
The patent combines retransmission traffic and new transmission traffic into the same physical resource pool, eliminating the need for separate dedicated retransmission resources. This merging allows the system to achieve both reliability (through proper power allocation for retransmissions) and low latency (by avoiding resource allocation delays)
3Device complexity
If orthogonal multiple access is used for HARQ feedback, then interference management is simplified, but spectral efficiency deteriorates
Solution Approach 1:
The patent changes the fundamental parameter used for user separation from orthogonal dimensions (time, frequency) to the power domain. By optimizing power allocation parameters, the system enables non-orthogonal multiple access where users share time-frequency resources but are separated by their allocated power levels, thereby improving spectral efficiency while managing interference through power control and successive interference cancellation
Data Source
AI summary
A device of a receiver, a method and a machine readable medium to implement the method. The method includes: determining a residual rate to identify a decoding estimate for a first packet sent from a wireless first transmitter; determining a grouping of transmitters including the first transmitter and a wireless second transmitter scheduled to transmit a second packet; performing power optimization by determining lowest necessary transmission powers corresponding, respectively, to transmissions of the first packet from the first transmitter and of the second packet from the second transmitter, wherein the transmissions of the first and second packets are within a same time-frequency resource and together define a signal to be received at the receiver; and encoding for transmission to the first and second transmitters information on the signal based on the residual rate, the grouping and the power optimization.