Multicast Reliability in IEEE 802.11n Power Saving Networks

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Solution Overview

Problem

In wireless network protocols like IEEE 802.11n, multicasting faces challenges due to power saving features that require stations to be awake at specific times, leading to inefficiencies as not all multicast addresses may be listening simultaneously to receive data.

Innovation Solution

Modifying the traffic specification frame (TSPEC) and power save multi-poll (PSMP) sequence flow to ensure stations are awake during multicast data reception and transmit acknowledgments within scheduled uplink times, using a modified TSPEC frame with a multicast flag and address, and extending the PSMP frame to include multicast addresses for synchronized transmissions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If power saving multi-poll (PSMP) protocol is used to reduce power consumption, then energy efficiency is improved, but multicast data delivery reliability deteriorates because stations cannot be simultaneously awake to receive multicast data

Engineering Contradiction:

Improvepower consumptionVSAvoidmulticast data delivery

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The access point determines the service interval and uplink transmission times in advance before multicast transmission begins. Stations are pre-scheduled to wake up at specific times to receive multicast data and send acknowledgments, ensuring they are awake and ready to receive data without continuous power consumption

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The PSMP protocol establishes periodic service intervals with scheduled downlink and uplink transmission times. Stations wake up periodically at predetermined times to receive multicast data during downlink slots and send acknowledgments during uplink slots, balancing power saving with reliable data delivery

Inventive Principle:

Principle #19Periodic action

2Reliability

If stations wake up at scheduled times to receive multicast data, then data delivery reliability is improved, but power consumption increases due to frequent wake-ups

Engineering Contradiction:

Improvemulticast data receptionVSAvoidpower consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The access point pre-determines and communicates the service interval and specific uplink transmission times to stations before multicast transmission begins. This allows stations to enter sleep mode for extended periods and only wake up at the predetermined times when they need to receive data or send acknowledgments, minimizing unnecessary wake-ups and power consumption

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

Stations autonomously manage their power consumption by waking up only at the pre-scheduled times indicated in the PSMP frame. Each station independently determines its wake-up times based on the service interval and its specific uplink transmission slot, eliminating the need for continuous monitoring or centralized control of individual station power states

Inventive Principle:

Principle #25Self-service

Data Source

PatentEP2025103B1Reliable multicast in a network having a power saving protocol

Publication Date: 2016.08.24 INTEL CORP

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AI summary

A reliable multicast for a power saving protocol such as IEEE 801.11n is described. A TSPEC frame is modified to carry the multicast address, which address can be represented in a short-hand form with, for instance, and AID. During the downlink times, the AID may also be used to identify the multicast downlink allocation in a PSMP frame.