Multi-user receiver power grouping for interference cancellation
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Solution Overview
Problem
Existing multiuser receivers struggle to operate reliably in wireless communication systems where power levels of received signals vary significantly, leading to near-far power imbalances due to Doppler effects and impractical power control in mesh networks, causing interference and reduced information capacity.
Innovation Solution
A method and receiver design that groups signals by power levels and iteratively processes them, using an MMSE equalizer to cancel multiuser interference within power bands, allowing for reliable signal estimation and demodulation across a wide range of signal strengths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If traditional power control is used in mesh networks with high-speed moving nodes, then power control can be implemented, but the power control cannot keep up with the spatial changes between nodes due to Doppler effects, causing near-far power imbalance
Solution Approach 1:
The invention segments the received signal into multiple user signals based on power level groups. Instead of treating all signals uniformly, the receiver divides them into groups (e.g., strong signals, medium signals, weak signals) and processes each group separately through successive interference cancellation, allowing reliable detection despite power imbalances caused by Doppler effects
Solution Approach 2:
The invention changes the processing parameter from uniform power-level treatment to power-level-based grouping. By adapting the signal processing approach according to the power level characteristics of different user signals, the system can handle the near-far problem without requiring perfect power control
2Adaptability or versatility
If multiuser receivers process signals with widely varying power levels using traditional methods, then they can operate in mesh networks, but stronger signals produce excessive interference to weaker signals
Solution Approach 1:
The invention extracts and removes the contribution of strong signals from the total received signal before processing weaker signals. By identifying and subtracting the dominant signal components, the receiver eliminates their interfering effect on weaker signals, enabling successful detection of all users regardless of power differences
Solution Approach 2:
The invention converts the harmful interference from strong signals into a beneficial feature by using the strong signals as reference to cancel interference. The very signals that cause interference are also used to generate cancellation patterns that remove their harmful effect, turning the near-far problem into a solvable structure
3Reliability
If receivers use narrow power range assumptions, then power control can be effective, but the receiver cannot handle signals spanning multiple orders of magnitude in power level
Solution Approach 1:
The invention implements a dynamic signal processing approach where the receiver adapts its processing strategy based on the actual power levels of received signals. Instead of assuming a fixed narrow power range, the system dynamically identifies power level groups and adjusts its interference cancellation strategy accordingly, enabling operation across multiple orders of magnitude
Data Source
AI summary
A method for acquiring signals received from multiple users in a single burst groups signals by power and sequentially processes the signal groups. A received sum of a plurality of user signals received in a burst is stored, and the transmitted symbols for each signal within a first group of the stored signals is estimated. A modified set of signals is then determined that excludes the signals of the first group. From the modified set of signals, the method continues by canceling multiuser interference among signals within a second group, and estimating transmitted symbols for each signal within the second group. The first and second groups includes all signals within a power band that defines the group, and the first band represents a higher power band than the second. Such iterative processing may continue for sequentially lower power bands until all signals are processed. A receiver is also detailed.