CSMA Wireless Protocol for Electronic Shelf Labels

Solution Overview

Problem

Existing wireless electronic shelf label (ESL) systems face challenges in minimizing power consumption and optimizing communication protocols to handle a large number of end nodes with limited power resources, leading to inefficient power usage and channel occupancy during data retrieval delays.

Innovation Solution

A communication protocol and scheduling method that involves end nodes sending data request packets and entering low power mode, with network coordinators transmitting response packets after a predefined time interval, allowing nodes to wake up only when responses are expected, thereby reducing unnecessary power consumption and channel occupancy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If the network coordinator communicates with electronic labels through wireless link using conventional protocols, then data can be transmitted, but power consumption increases and channel occupancy is inefficient due to unknown delays during data retrieval

Engineering Contradiction:

Improvepower consumptionVSAvoiddelay

Core Design Contradiction:

Use of energy by moving objectVSLoss of time

Solution Approach 1:

The network coordinator performs preliminary actions by retrieving data from the database and preparing response packets before the electronic label needs to wake up. The coordinator stores the requested data in advance, so when the label wakes up at the expected time, the response is already ready for immediate transmission, eliminating waiting delays and reducing the label's power consumption.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The electronic label operates in periodic cycles, alternating between sleep mode and active mode. The label wakes up at predetermined intervals to send requests and receive responses, then returns to sleep mode. This periodic operation pattern minimizes power consumption while maintaining communication functionality.

Inventive Principle:

Principle #19Periodic action

2Productivity

If the end node remains active to receive response packets, then data can be received without delay, but power consumption increases significantly

Engineering Contradiction:

Improvedata retrieval efficiencyVSAvoidpower consumption

Core Design Contradiction:

ProductivityVSUse of energy by moving object

Solution Approach 1:

The network coordinator performs preliminary actions by retrieving data from the database and preparing response packets before the electronic label needs to wake up. The coordinator stores the requested data in advance, so when the label wakes up at the expected time, the response is already ready for immediate transmission, eliminating waiting delays and reducing the label's power consumption.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The electronic label autonomously determines when to wake up and when to sleep based on predetermined time intervals and expected response times. The label independently manages its power state transitions without requiring continuous coordination, optimizing its own power consumption while ensuring it is awake to receive necessary data.

Inventive Principle:

Principle #25Self-service

3Reliability

If the transmission channel is occupied during data retrieval delays, then response packets can be transmitted immediately, but other devices cannot use the channel efficiently

Engineering Contradiction:

Improveresponse deliveryVSAvoidchannel utilization

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The network coordinator performs preliminary actions by retrieving data from the database and preparing response packets before the electronic label needs to wake up. The coordinator stores the requested data in advance, so when the label wakes up at the expected time, the response is already ready for immediate transmission, eliminating waiting delays and reducing the label's power consumption.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS8532005B2End node and network coordinator using a CSMA based protocol

Publication Date: 2013.09.10 QORVO UTRECHT BV

AI summary

A communication protocol based on CSMA between a node, in particular an electronic label, and a network coordinator is disclosed. The node comprises:—a transceiver provided for communication with a network coordinator, wherein the transceiver handles a transmission channel based on CSMA;—a processing unit provided for processing data received via the transmission channel and displaying the data on a display unit. The electronic label is arranged to perform:—sending recurrently a data request packet;—going to a low power mode after sending the data request packet; and—waking-up for receiving a data response packet a predefined time interval after beginning sending the data request packet. The network coordinator is arranged to transmit the data response packet the predefined time interval after receiving the beginning of the data request packet. The invention provides a protocol based on CSMA with very low power operation in which a multitude of end nodes could receive from a network coordinator their corresponding data.