21-04-00xx-00-0021-layer2.5functionality layer 2.5 functionality peretz feder ajay rajkumar lucent...

21-04-00xx-00-0021-Layer2.5functionality

Layer 2.5 Functionality

Peretz Feder

Ajay Rajkumar

Lucent Technologies

May 13, 2004


Objectives

1. To crystallize the concept and boundary of layer 2.5

2. To describe the scope of the triggers with relation to Layers 3 and 2.5

3. Define interfaces to mobility management at layer 3

4. Identify the decision entity and its relation to the executive entity


IETF based Layer 3 • Mobility mechanism is Mobile IP Handover capable• Layer 3 mobility is not optimized for real time

applications• Objective is to improve or assist layer 3 handover

performance• Do we have the mandate to change it in 802.21? • Lets explore layer 3-


Layer 2.5 Boundary Definition

Mobile Node Network

PHY1 PHY

MAC MAC

LLC LLC

MN Trigger State machineentity

Network TriggerState machine

entity

IP and MIP IP and MIP

Measurements

L2.5SAP

L2.5SAP

L2.5L2.5

Transport & Higher Transport & Higher

PHY2

MAC

RLP/RLC

System attributes

Handover command

Handover attributes(e.g. SLA directory)

Query (e.g. access cost)

PLME

MLME

Local TriggersAccess 2

Local TriggersAccess 1


Mobility Model• Multi radio interface at the MT• Network may not control (or own) all the interfaces

available to the MT• Propose to include a layer 2.5 entity at the MT that

selects one of the available interfaces. However, the selection mechanism is vendor specific!!

• Network has peer-to-peer relation with the state machine entity

• Network assisted through handover recommendation• Network assisted through SLA directory update• Upon decision, L2.5 invokes the layer 3 (IP) handover

mechanism providing it a single access choice


Layer 2.5 Selection Entity• Selects a preferred access and let layer 3 execute

without delay • How? Process all the triggers and apply a vendor

specific algorithm• Triggers include locally measured attributes,

loading conditions, available QoS, normalized signal quality

• Hints include cost of link, roaming agreements, network provided neighboring list


Example: Preference Rules Translated into Decision Matrix

Air-interface

3GHigh 3GMedium 3GLow 3GUnavailable

802.11High 802.11 802.11 802.11 802.11

802.11Med 802.11 802.11 802.11 802.11

802.11Low 3G 802.11 802.11 802.11

802.11NA 3G 3G 3G Work offline or sleep

802.11medium_threshold is preferred over 3Ghigh_threshold

802.11low_threshold is preferred over 3Gmedium_threshold


Example: Preference Rules Translated into Decision Matrix

Interface 802.3 802.3 802.3 802.3NA

802.11High 802.3 802.3 802.3 802.11

802.11Med 802.3 802.3 802.3 802.11

802.11Low 802.3 802.3 802.3 802.11

802.11NA 802.3 802.3 802.3 Work offline or sleep

802.3 is preferred over 802.11any_threshold


Recommendation• Don’t attempt to fix layer 3 deficiencies • Develop layer 2+ entity that assists layer 3 mobility• Don’t waste time defining the selection algorithm• Make layer 3 execute the handover decision• Define the interface to L3. Bidirectional SAP or

Ethertype_21?– 3G can’t talk the Ethertype language

– MIB is too slow

21-04-00xx-00-0021-layer2.5functionality layer 2.5 functionality peretz feder ajay rajkumar lucent...

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