WLAN Adapter Packet Filtering to Reduce Host CPU Load

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Solution Overview

Problem

The high processing requirements of wireless local area network (WLAN) adapters pose a significant load on the host microprocessor of personal computers, making it challenging to implement MODEM functions without impacting other applications, unlike in wireline networks where cost savings were achieved by moving processing to the host processor.

Innovation Solution

Implementing a technique that minimizes unnecessary host CPU interrupts by classifying and filtering receive packets on the interface card based on waveform identification, rate determination, and modulation type, allowing the host CPU to perform MODEM functions only for relevant packets, thereby reducing processing load.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the host processor performs MODEM functions for all receive packets, then complete packet processing is achieved, but the CPU load increases significantly impacting other applications

Engineering Contradiction:

Improvepacket processing completenessVSAvoidCPU available processing capacity

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The interface card performs preliminary waveform identification and classification of receive packets before they reach the host CPU. By pre-processing packets to determine their modulation type and data rate at the interface card, the system filters out packets that don't require CPU processing, thereby reducing CPU load while maintaining complete processing capability for relevant packets.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent extracts the waveform identification and packet classification functions from the host CPU and relocates them to the interface card. This extraction allows the CPU to focus only on processing packets that pass the filter, significantly reducing its processing burden while maintaining reliable packet processing for relevant data.

Inventive Principle:

Principle #2Taking out (Extraction)

2Reliability

If the host processor processes all incoming packets, then no data is lost, but unnecessary processing interrupts CPU tasks reducing overall system efficiency

Engineering Contradiction:

Improvedata reception completenessVSAvoidCPU time spent on unnecessary processing

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The interface card acts as an intermediary between the wireless receiver and the host CPU. It performs waveform identification and packet classification as an intermediate processing stage, filtering out unnecessary packets before they interrupt the CPU, thus reducing CPU time spent on unnecessary processing while ensuring complete data reception for relevant packets.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Productivity

If dedicated signal processors are used for MODEM functions, then processing load on host is reduced, but hardware cost increases

Engineering Contradiction:

Improvehost processor available capacityVSAvoidadapter cost

Core Design Contradiction:

ProductivityVSEase of manufacture

Solution Approach 1:

The patent makes the host CPU multi-functional by enabling it to perform both general computing tasks and selective MODEM processing. Through software-based waveform identification and packet classification at the interface card, the host CPU can handle wireless processing functions without requiring dedicated hardware, thereby reducing hardware cost while maintaining host processor capacity for other applications.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent uses software-based processing at the interface card as a cost-effective alternative to expensive dedicated signal processors. By implementing waveform identification and packet classification through software on the interface card rather than dedicated hardware, the system reduces adapter cost while maintaining sufficient processing capability for relevant packets.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Data Source

PatentUS7577122B1Method for minimizing receive packet processing for a personal computer implementation of a wireless local area network adapter

Publication Date: 2009.08.18 DATASPHERE LLC

AI summary

A method and wireless local area network (WLAN) adapter for the reduction of receive packet processing in a communications system receiver. The method includes establishing a set of criteria which identifies a packet as one requiring demodulation. The method further includes detecting a packet preamble to trigger at least one waveform identification function and determining with the at least one waveform identification function of the detected packet meets an established criteria for demodulation. The established criteria may include at least one of data rate, modulation type, signal to noise ratio, or coding rate. If the detected packet meets the established criteria for demodulation, a host processor may be interrupted to begin demodulation.