Interference-Tolerant Packet Detection Using Cross-Correlation Bank
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Solution Overview
Problem
Existing wireless communication systems using OFDM face challenges in accurately detecting packets due to interference from adjacent channels, leading to false triggers and reduced throughput, as conventional algorithms struggle to differentiate between in-band and overlapping signals.
Innovation Solution
A system that cross-correlates incoming signals with a bank of reference signals to distinguish between desired and undesired packets, using a threshold comparison to reject interference and optimize packet detection, even in the presence of frequency offsets, by selecting appropriate phases and patterns for cross-correlation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional packet detection algorithms are used, then packet detection is performed, but false triggers occur due to interference from adjacent channels
Solution Approach 1:
The patent divides the packet detection process into multiple independent correlation operations, each targeting a specific frequency offset range. By segmenting the detection task across multiple correlators with different correlation parameters, the system can distinguish between signals at different frequency offsets, preventing false triggers from adjacent channels while maintaining reliable detection of in-band packets.
Solution Approach 2:
The patent applies different correlation parameters and threshold criteria to different frequency offset ranges. Each correlator operates with locally optimized parameters suited to its specific frequency offset range, allowing the system to handle different signal conditions with appropriate local characteristics rather than using a uniform detection approach.
2Measurement precision
If filtering is applied to separate channels, then frequency separation is achieved, but cannot alleviate false triggering due to overlapping signals
Solution Approach 1:
The patent replaces traditional frequency filtering mechanisms with a correlation-based detection mechanism. Instead of using filters to separate channels in the frequency domain, the system uses correlation operations with specific time-domain patterns to distinguish between signals at different frequency offsets, achieving both channel separation and false trigger avoidance simultaneously.
3Object-affected harmful factors
If adjacent channel packets are processed, then interference is handled, but inband signal detection is lost due to false triggers
Solution Approach 1:
The patent performs preliminary correlation operations to identify and classify packets before full processing. By preliminarily determining whether a packet is from an adjacent channel or in-band through correlation with reference signals, the system can handle interference packets without blocking inband signal detection, maintaining data throughput while managing interference.
4Reliability
If multiple correlation operations are performed, then interference rejection is improved, but system complexity increases
Solution Approach 1:
The patent implements a limited number of correlation operations with specific correlation parameters rather than exhaustive correlation across all possible frequency offsets. By using a manageable set of correlation templates and parameter combinations, the system achieves effective interference rejection without excessive computational complexity, balancing performance and implementation cost.
Data Source
AI summary
The present invention provides a system for obviating interference effects in packet detection within a wireless communications network. A plurality of reference signals is provided—a first of which corresponds to desired packets, and the remainder of which correspond to undesired packets or interference. A plurality of cross-correlation constructs corresponds, respectively, to the plurality of reference signals. Each cross-correlation construct correlates an incoming signal to a plurality of repetitions of its respective reference signal. An analysis construct compares output from each cross-correlation construct with other cross-correlation construct outputs, and with a threshold value, to determine which incoming signal corresponds to desired packet data. Once this incoming signal is identified, packets from the signal may be reliably received.