Software Spread Spectrum Receiver Correlation Aggregation

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Solution Overview

Problem

Current software-based GNSS receivers face challenges in achieving high flexibility, low cost, and power efficiency, particularly in handheld devices, due to high processing loads and memory requirements, which limit their ability to process multiple signal formats and maintain real-time tracking performance with low signal power.

Innovation Solution

A digital processing unit with a correlation module and aggregation module that divides incoming data samples into blocks, correlates them with local code replicas, and aggregates results to reduce the number of accumulation results, enabling efficient Doppler shift compensation and decoding with multi-bit operands, while minimizing processing requirements and memory usage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a software-based receiver solution is used to enable flexibility in processing multiple signal formats, then adaptability is improved, but processing load and power consumption increase

Engineering Contradiction:

Improveability to process multiple signal formatsVSAvoidpower consumption

Core Design Contradiction:

Adaptability or versatilityVSUse of energy by moving object

Solution Approach 1:

The incoming data stream is divided into multiple data blocks that can be processed in parallel. Each block is correlated with local code replicas independently, and results are aggregated to produce the final decoded signal. This segmentation enables efficient utilization of SIMD instructions and reduces the processing burden on the microprocessor.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Carrier vectors representing Doppler shifts are pre-generated and stored in a compressed vector table before signal processing begins. During real-time operation, the receiver retrieves and applies these pre-computed vectors to compensate for Doppler effects, avoiding the need for complex real-time calculations and reducing processing load.

Inventive Principle:

Principle #10Preliminary action

2Adaptability or versatility

If traditional software-based baseband processing is used, then flexibility is improved, but processing speed and real-time performance deteriorate

Engineering Contradiction:

Improvesoftware-based processing flexibilityVSAvoidprocessing speed

Core Design Contradiction:

Adaptability or versatilityVSProductivity

Solution Approach 1:

The baseband processing is segmented into distinct stages: data block division, correlation with local code replicas, aggregation of intermediate results, and Doppler compensation using pre-generated carrier vectors. This structured segmentation enables optimized execution of each stage and facilitates parallel processing.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The receiver processes incoming data in periodic blocks, with each block undergoing correlation and aggregation operations. This periodic block-based processing rhythm allows the system to maintain real-time performance while utilizing software-based flexibility, as each block can be processed independently and efficiently.

Inventive Principle:

Principle #19Periodic action

3Adaptability or versatility

If multiple receiver chains are included to process different signal formats, then adaptability is improved, but device size and cost increase

Engineering Contradiction:

Improvemulti-mode reception capabilityVSAvoiddevice size

Core Design Contradiction:

Adaptability or versatilityVSVolume of moving object

Solution Approach 1:

The receiver implements a universal software-based processing platform that can handle multiple signal formats (GPS, Galileo, GLONASS) through programmable algorithms rather than dedicated hardware chains. The same processing infrastructure processes different signal types by loading appropriate signal-specific parameters and code replicas, eliminating the need for multiple physical receiver chains.

Inventive Principle:

Principle #6Universality (Multi-functionality)

4Use of energy by moving object

If single-bit operand solutions are used to reduce processing load, then power consumption is reduced, but measurement precision deteriorates

Engineering Contradiction:

Improvepower consumptionVSAvoidsignal processing accuracy

Core Design Contradiction:

Use of energy by moving objectVSMeasurement precision

Solution Approach 1:

The patent transitions from single-bit to multi-bit operand processing by utilizing packed data structures that represent multiple bits within a single data word. This dimensional change in data representation enables more precise signal processing while maintaining processing efficiency through vectorized operations and reduced instruction counts.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Data Source

PatentUS8811143B2Software based spread spectrum signal processing

Publication Date: 2014.08.19 QUALCOMM TECH INT

AI summary

A digital processing unit for use in a spread spectrum signal receiver, the digital processing unit being adapted to receive an incoming stream of data samples and in response thereto produce a decoded signal, the digital processing unit comprising a correlation module adapted to correlate data blocks formed from the incoming stream of data samples with a local code replica segment to produce a first number of intermediate accumulation results and an aggregation module adapted to receive the first number of intermediate accumulation results and to combine the first number of consecutive ones of said intermediate accumulation results to form a target number of aggregated accumulation results, said target number being less than or equal to the first number.