Interference-Canceling Receiver Timing Alignment for Multipath Latency
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Solution Overview
Problem
In wireless communication systems, multipath interference causes intra-channel and inter-channel interference, leading to errors in signal decoding, reduced capacity, and decreased data rates, which existing technologies have not adequately addressed.
Innovation Solution
A generalized interference-canceling receiver is developed to align and cancel intra-channel and inter-channel interference using symbol estimation and interference estimation techniques, employing Rake combining, equalization, and Hadamard transforms, with different subsystems operating at varying clock speeds to manage latency and processing requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If interference cancellation is performed using multiple subsystems operating at different clock speeds, then interference reduction effectiveness is improved, but latency management and processing synchronization become more complex
Solution Approach 1:
The receiver is divided into multiple independent subsystems (first and second subsystems) that operate at different clock speeds, with each subsystem performing specific interference cancellation functions. This segmentation allows each subsystem to be optimized for its specific function while managing complexity through modular design.
Solution Approach 2:
A buffer is introduced as an intermediary component between subsystems operating at different clock speeds. The buffer absorbs timing differences and data rate mismatches, enabling synchronization without requiring all subsystems to operate at the same clock frequency, thus managing the complexity of multi-speed operation.
2Measurement precision
If multiple segments of interference estimates are processed to generate a single segment of interference cancelled signal, then interference cancellation accuracy is improved, but processing time increases
Solution Approach 1:
Interference estimates are computed in advance for multiple segments before the actual interference cancellation is needed. By performing these computations preliminarily and storing the results in buffers, the system reduces real-time processing requirements while maintaining high cancellation accuracy.
Solution Approach 2:
The interference estimation process is divided into multiple segments that can be processed independently and in parallel. This segmentation allows the system to accumulate precise estimates from multiple segments without requiring sequential processing, thereby reducing total processing time while maintaining accuracy.
3Productivity
If different subsystems operate at different processing clock speeds, then processing efficiency is improved, but latency and alignment management become more difficult
Solution Approach 1:
The system employs dynamic buffering and timing adjustment mechanisms that adapt to different clock speeds of various subsystems. Buffers are dynamically sized and managed to accommodate latency variations, allowing subsystems to operate at optimal different speeds while maintaining overall system synchronization.
Solution Approach 2:
Buffers serve as intermediary elements between subsystems with different clock speeds, absorbing timing differences and enabling each subsystem to operate independently at its optimal speed without directly coupling their timing requirements, thus managing latency effectively.
Data Source
AI summary
An interference cancelling receiver combines data from multiple paths after aligning to transmitter timing, and uses either an equalizer or a Rake receiver to compute symbol estimates. Interference estimates are generated from the symbol estimates, and multiple interference estimates are combined after re-aligning the interference estimates to receiver timing. At least two segments of symbol estimates are computed for each segment of interference cancelled data.Various techniques may be employed for controlling the latency and sequencing of these operations, and the subsystems within the canceller may use different processing clock speeds.