Carlo Giannelli - unibo.it · 2012. 9. 3. · Bologna, Italy — 18.09.2009 Carlo Giannelli 1/41. Agenda Social sharing . of connectivity resources – single/multi-hop wireless networks

Context-aware Middleware forMulti-hop Multi-path

Heterogeneous Connectivityin Social Sharing Scenarios

18.09.2009DEIS, Università degli Studi di Bologna,

Viale Risorgimento, 2 - 40136 Bologna [email protected]

Carlo Giannelli

Bologna, Italy — 18.09.2009 Carlo Giannelli 1/41

AgendaSocial sharing of connectivity resources

– single/multi-hop wireless networks– sharing of Internet connectivity and peer-to-peer services

State-of-the-art thorough analysis– CAMPO model and taxonomy– from traditional homogeneous to novel heterogeneous wireless scenarios

several communication technologiesinfrastructure and peer points of access/services

Multi-hop Multi-path Heterogeneous Connectivity (MMHC)– middleware for context-aware dynamic reliable connections to the Internet– context information: node mobility, path throughput, energy availability– MMHC vs. IEEE 802.11s– two-phase procedure

local-phase: reliable remote connection establishmentglobal-phase: available paths enhancing to ensure long-term availability

– MMHC middleware architecture

Ongoing work– from Internet-based to p2p-driven networking– incentives to resources exploitation fairness in semi-cooperative environments– cluster-based mobility and smart environment management


The Wireless ScenarioClient: node requiring connectivity, e.g., user PDAConnector: node providing connectivity, e.g., UMTS Base Station (BS)Channel: active client-connector IP connection, e.g., IEEE 802.11 association and DHCP configuration

Handover procedure– a client node changes current connector while

movingEvaluation process

– context gathering: which information is important?

– metric application: which is the most suitable connector?

Internet

Connectors

Channels

ClientNode

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Bologna, Italy — 18.09.2009 Carlo Giannelli

Single/Multi-hop Wireless Networking

Single-hop networking: direct communication among nodes– ad-hoc: point-to-point communication

Bluetooth Piconet or IEEE 802.11 IBSS– infrastructure: communication mediated by special purpose

equipment IEEE 802.11 AP or UMTS BS

Multi-hop networking: communication among distant nodes based on packet routing performed by intermediate nodes– different hypothesis on

availability of infrastructure componentsmobility degree of communicating and intermediate nodes

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WMN, MANET, Opportunistic Networking

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Wireless Mesh Network, WMN– intermediate nodes are mainly infrastructure-based, aiming at creating highly reliable

backbones, e.g., IEEE 802.11s– communicating nodes move frequently, intermediate nodes are rather static

Mobile Ad-hoc NETwork, MANET– intermediate nodes are based on ad-hoc connectivity: best-effort connectivity– both communicating and intermediate nodes move frequently, but there is enough time

to create sufficiently reliable paths among nodes

Opportunistic Networking– similar to MANET, but without a path among communicating nodes– intermediate nodes opportunistically forward packets whenever interact with other

nodes “closer” to the destination: suitable in unreliable environments

backbone



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Social Sharing of Connectivity Resources (1)

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Novel scenario taking full advantage of the many context information and networking opportunities

peer-to-peer connectivitysimultaneous exploitation of multiple interfacesaverage node mobility (between MANET and WMN)

Internet sharingInternet connectivity provisioning based on dynamic context-aware routing rules configuration

Peer-to-peer service sharingtime/hop-bounded service discovery/invocation in heterogeneous ad-hoc networks

Quality of Service controlincentive-based to push for actual connectivity/service sharing


Social Sharing of Connectivity Resources (2)

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Bluetooth

Internet

UMTSIEEE 802.11

IEEE 802.11(ad hoc)

Carol

Alice

Alice

Bob

(Alice moves)

AP BS

1) Alice’s client autonomously selects the free-of-charge IEEE 802.11 connector

2) Alice provides connectivity via Bluetooth

3) Carol provides her lesson’s notes via a file sharing service

4) Bob accesses Carol’s notes via Alice

5) When Alice moves, she gets connectivity via Carol and then re-establish active connections


CAMPO Model (1)Thorough state-of-the-art surveyMany specific research areas, e.g., infrastructure-based and peer-to-peerNovel model and taxonomy:

– proposals grouping based on differences and similarities

– novel researchers field comprehension

CAMPO: Context-aware Autonomic Management of Preferred network Opportunity

– most suitable interface and connector based on user preferences, runtime environment, connectivity reliability

A common model for– basic term definition

channel: {application, interface, connector}intra/inter/vertical handover

– two selection mechanismsinterface and connector selector

Application

Active InterfaceNetworkDomainUnused Interface

Connector

ba

cc

Applications ConnectorsInterfaces

a) Intra-horizontal, b) Inter-horizontal and c) vertical handover

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CAMPO Model (2):4G and ABC

4G (4th Generation)– one interface per time, selected without

user intervention <N:1:1>– infrastructure-based connectors– dynamic connection migration among

interfaces

ABC (Always Best Connected)– several interfaces simultaneously– infrastructure and peer connectors– only-one/multiple channels per interface

<N:M:M> / <N:M:L>

Social Sharing– Internet connectivity + peer-to-peer services– user's behavior active monitoring– reward-based mechanisms

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N 1 1 1

cc

<N:M

:M>

<N:M

:L>


CAMPO Taxonomy (1)Three categories to underline specific similarities and differences:– management scope

working environment capabilities– evaluation process

context gathering: which information are important?metric application: which interface/connector is the most suitable one?

– continuity management trigger: when performing a handover?switcher: how to update active channels?

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interfacemobile node

environment

Internet

contextgathering

metricapplication trigger switcher

Evaluation Process Continuity Management


CAMPO Taxonomy (2)

Management scope:– interface: switch on/off, select a connector– mobile node: only one/multiple interfaces– environment: external components support

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distributed

single-on

envi-ronment

interface

client-side

interface-only

interface-connector

infrastructure

peer

location

roleevaluation

continuity

mobilenode multiple-on

ManagementScope


CAMPO Taxonomy (3)Primary operations of CAMPO systemsEvaluation process– available channels suitability

input: context informationprocessing: how to exploit inputoutput: channel suitability, best channels

Continuity management– update active channels at service

provisioning timeintegration: relationship between origin and destination connectorsgranularity: every-/per-channel migrationvisibility: external support

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ContinuityManagement

per channel

per node re-routing

endpoint updategranularity

visibilityend-to-end

transparent

integrationtight

loose

proxy

intra-domaininter-domain

intra-horizontalinter-horizontal

vertical

pureproxy

re-addressing

AAA, billing

extensible

abstractionlevel

flexibility

variations

objective

dynamic

embedded

physicalnetwork

application

selectedentity

interfaceconnector

localglobal

static

input

processing

output provideddata

single valueevaluation set

EvaluationProcess


CAMPO Taxonomy (4)

A survey positioning about 80 work– many systems provide only partial solutions– deployment scenario: connector scope, single-on– evaluation process: local scope, function, connector– continuity management: loosely-coupled, per-node, proxy

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Lessons Learned

Context-aware evaluation process– dynamic adaptation of the execution environment– trade-off between effectiveness and expressiveness

Hybrid deployment scenarios– infrastructure and peer connectors– multi-hop multi-path heterogeneous connectivity

Decentralized connectivity management– collaborating components distributed on different

nodes, eventually even on the infrastructure side

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Homogeneous Wireless Scenario

Current scenario: static, infrastructure-based, one-hopOne communication interface at a time

– the client node does not change wireless interfaceHorizontal handover

– infrastructure connectors only– origin and destination connectors based on the same wireless technology

IEEE 802.11– connectors are IEEE 802.11 Access Points (APs)– metric based on Received Signal Strength Indication (RSSI) and Signal

to Noise Ratio (SNR), usually embedded in interface firmware

Already available many heterogeneous wireless interfaces on the same mobile node– IEEE 802.11, Bluetooth, GPRS/UMTS– bandwidth, power consumption, coverage range


Social Heterogeneous Wireless Scenario

Heterogeneous interfaces– the client node exploits multiple wireless

interfaces, even simultaneouslyHeterogeneous connectors

– can be infrastructure or peer nodes– single-/multi-hop paths

Connectivity management– managing interfaces/connectors/channels/paths

considering several context data to take advantage of the many networking opportunities

Heterogeneity and cooperation increases client node capabilities:– heterogeneous connectors enable the most suitable form of connectivity

Bluetooth to limit power consumption, IEEE 802.11 to get larger bandwidth– peer connectors extend connectivity opportunities via multi-hop paths

UMTS link accessed via Bluetooth through a peer connector

peer

infrastructure

Internet

IEEE 802.11

Bluetooth

UMTS

Client Node

peerconnector





Social Scenario:Design Guidelines

Trade-off between static and dynamic management– re-evaluation of connectivity opportunities to

modify available channelsreconfigure routing rules

– static approaches achieve sub-optimal solutions– dynamic approaches impose non-negligible monitoring/managing overhead

Trade-off between local and global management– monitoring scope greatly impact on required solution

local knowledge: easy to gather but with limited expressivenessglobal knowledge: best resource exploitation but with networking overhead and delay

Trade-off between single- and multi-path granularity– basic solution: every flow of every client sent to the same destination

aggregated routing rules – client-granularity: different flows of the same client sent to the same destination

per-client routing rules– flow-granularity: each flow is managed differently

per-request routing rules16/41


MMHC: Multi-hop Multi-pathHeterogeneous Connectivity

Full exploitation of already available wireless interfaces– multi-hop paths, eventually based on heterogeneous single-hop links– dynamic connectivity evaluation and management– connectivity provisioning in a peer-to-peer fashion– context-aware evaluation metric

Efficient connectivity support via proper trade-off among – static and dynamic management

time-consuming single-hop connections performed reactively (rather static)efficient routing rules modifications performed proactively (dynamic)

– local and global managementlocal management to quickly provide Internet connectivityglobal management to incrementally improve connectivity capabilities

– single- and multi-path granularityaggregated connectivity to the Internetdifferentiated access to peer to peer services

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MMHC: Objectives1) Novel metric considering a wide set of context information at

different abstraction levelstraditional RSSI/SNR based evaluation processes are not enoughevaluation metric specifically designed for heterogeneous wireless scenarios

2) Two-phase procedure to separately consider path establishment and enhancement

local-phase: connectors suitable for path realization to maximize reliability and throughputglobal-phase: long-term connectivity based on additional context information, eventually slight modifications of the network topology

3) Static and dynamic managementreactive approach for single-hop connectivityproactive approach for multi-hop path reconfiguration


IEEE 802.11s for Extended Service Set mesh networking

Multi-hop connectivity at lower OSI layers, by extending IEEE 802.11

– efficiency: no en/decapsulation of data into/from higher layer protocols

– availability: compatibility with the many already available IEEE 802.11a/b/g interfaces

Node roles– STA: mobile client STAtion only getting connectivity– MAP: Mash Access Point providing connectivity to STAs– MP: Mesh Point performing as intermediate node (not

providing connectivity to STA)– MPP: Mesh Portal interconnecting the mesh network and

the InternetPath establishment

– metric: airtime cost reflecting the amount of channel resources consumed by transmitting a frame over a particular link

– path selection: hybrid reactive/proactive

19/18

Internet

MPP

MPMAP

MAP

STA

STA STA





MMHC vs. IEEE 802.11sBoth IEEE 802.11s and MMHC support multi-hop wireless connectivity, but with relevant differencesRoles

– IEEE 802.11s: STA, MP, MAP, MPP– MMHC: clients, (peer) connectors

Technology– IEEE 802.11s: only standard-compliant interfaces– MMHC: interconnection of heterogeneous networks

Layer– MAC protocol– interconnection of IP networks

Evaluation metric– IEEE 802.11s: low-level radio-aware link metric– MMHC: meaningful context information

IEEE 802.11s and MMHC are complementary, not competitors

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Internet

MPP

MPMAP

MAP

STA

STA STA

premere sulla necessità di

sfruttare il contesto





Context AwarenessProvide highly reliable/durable paths (crucial issue in mobile wireless networks) with sufficient quality (to maximize user satisfaction)Path reliability– peer connectors are less reliable, since may abruptly move away– monitor client node and peer mobility to provide reliability

Path quality– quality mainly depends on wireless technology, number of

active clients, and number of hops to the Internet – coarse-grained estimation of actual throughput

Path durability– interrupt the connectivity to limit power consumption– residual battery level to ensure path long-term durability

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ConnectorsInfrastructure-based connectors– e.g., IEEE 802.11 access point and UMTS base station– always reliable and fixed

Peer-based connectors– e.g., IEEE 802.11 ad-hoc and Bluetooth– trusted and untrusted– fixed and mobile– joint and transient

connector

jointtransient

fixed

peer(un/trusted)

mobile

infrastructure(trusted)

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Transient connector– e.g., a mobile node in the same sidewalk but with opposite direction– not suitable for connectivity since has a high probability of becoming

unavailableJoint connector

– e.g., PDA connector in the same train wagon– greater durability → suitable for connectivity

Client-connector mutual distance inferred by monitoring connector RSSI variability

– CMob to evaluate client node mobility degree [0,1]– Joint to evaluate peer connector relative mobility degree [0,1]

ClientNode

joint

transient

Path Reliability (1)

Connector type RSSI variability Mobility state

fixedalmost constant still client nodegreatly variable moving client node

mobilealmost constant joint connectorgreatly variable transient connector






RSSIgathering

Low-PassFilter

ParameterComputation

StateEstimation

DFT (16/4 values)IDFT (first harmonic)

DFT(16/4 values)

RSSIsequences

filtered RSSI

sequences

firstharmonic modules

CMobJoint

upper/lowerbounds

Discrete Fourier Transform (DFT) applied twice to– low pass filter RSSI fluctuations due to signal noise– estimate CMob (fixed infrastructure connectors) and Joint (peer

connectors)


Single-hop: EstimatedEndurance– (1-CMob) • CoverageRange (for APs/BSs)– Joint • CoverageRange (for mobile peers)

Multi-hop: PathMobility at kth hop– EstimatedEndurancek (single-hop, i.e., k=1)– EstimatedEndurancek • PathMobilityk-1 (multi-hop, i.e., k>1)



Node B and C are still → high EE

Node A is in motion → low EE

Node D automaticallyselects the path on the right

– nodes B and C have same EE but different PM

– node C provides much higher reliability (PMB=0.49 vs. PMA=0.14)

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A

D

InternetInternet

AP1 AP2

C PMAP2 = 0.7

EEAP2 = 0.7EEAP1 = 0.7

PMAP2 = 0.7

EEA = 0.2

EEB = 0.7

PMC = 0.49

PMA = 0.14

Lessons learned: push for paths composed by joint nodes

B

PMB ≈ 0.01

EEC = 0.7


Path Quality (1)Coarse-grained estimation of multi-hop paths throughput

– adopted wireless technology: e.g., Bluetooth represents a bottleneck– number of active clients: fair bandwidth sharing– number of hops to the Internet: 20-30% per-hop degradation

Heterogeneous wireless interfaces provided by different manufactures, e.g., IEEE 802.11 Orinoco Gold, Buffalo and PRO/Wireless interfaces

– heterogeneous interfaces better mimics actual wireless environments– greater performance with homogeneous hardware

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Path Quality (2)

EstimatedThroughput (ET):– NominalBandwidth (NB) (for APs/BSs)– (1 – HopDegr) • MaxThr / #clients (for mobile peers)

where MaxThr=min{previous hop ET, current hop NB}

– ETAP = NBAP = 4 Mbps– ETA = (1-0.2) • 4 Mbps / 3 clients = 1.07 Mbps– ETB = (1-0.2) • 1.07 Mbps / 2 clients = 0.428 Mbps

Lessons learned: push for short paths with few clients, particularly when exploiting Bluetooth

InternetAP

A

B

27/41


Path Durability (1)Expected long-term path durability due to energy consumption

– avoid paths composed by mobile peers with low battery levelsprobably unavailable in a short time

– fairly exploit energy of mobile peers not overloading only one path traversing traffic increase power consumption

ResidualPathEnergy at kth hop– NodeBatteryLevelk (single-hop, i.e., k=1)– NodeBatteryLevelk • ResidualPathEnergyk-1 (multi-hop, i.e., k>1)

AveragePathEnergy at kth hop– NodeBatteryLevelk (single-hop, i.e., k=1)

– (multi-hop, i.e., k>1)1( ) ( 1)k kAveragePathEnergy k NodeBatteryLevelk

− ⋅ − +

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Path Durability (2)

A

C D

E

InternetInternet

BS1 BS2

F

B NBL = 0.40

APE = 0.45RPE = 0.20

NBL = 0.07

NBL = 0.95

APE = 0.40RPE = 0.40

NBL = 0.50

APE = 0.95RPE = 0.95

APE = 0.51RPE ≈ 0.07

NBL: NodeBatteryLevelRPE: ResidualPathEnergyAPE: AveragePathEnergy

F selects BS2-B-D instead of BS1-A-C

– slightly lower APE: 0.45 instead of 0.51

– but sufficiently great RPE: 0.20 instead of 0.07

Lessons learned: push for battery level fair exploitation

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Ongoing WorkCurrent MMHC prototype is mainly focused on Internet connectivity

– main goal is to provide multi-hop Internet access to nodes– peer-to-peer communication limited to subnets

Extending Internet connectivity provisioning via peer-to-peer networking

– incremental knowledge of the (whole) wireless environment– local (vs. Internet) service provisioning/discovery/invocation

Pushing for service/connectivity provisioning– supporting trust and fairness in semi-cooperative environments

30/41


Peer-to-peer Information Delivery

Supporting context information spreading among NAT-separated but interconnected networks

– not only top-down but also bottom-up and sibling information delivery

Information delivery with no global knowledge of network topology– multiple single-hop information dissemination among

neighbor nodes– time/hop bounded information delivery

Service discovery/provisioning as a special case of context distribution– context-aware service discovery/selection– automatic service rebinding

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Connectivity Fairness in Multi-hop Wireless Networks

Connectivity starvation in multi-hop multi-client paths

– closest node achieves almost all the bandwidth

Decentralized fairness management– traffic monitor to perceive starvation– traffic control to

maximize local trafficavoid traffic starvation

Incentives for connectivity sharing based on low/high level context information

– traversing vs. generated packets– number of invoked/offered services– number of connected nodes

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Conclusions & Ongoing Work

MMHC supports multi-hop multi-path connectivity exploiting off-the-shelf heterogeneous equipment– IEEE 802.11, Bluetooth, Ethernet

MMHC proposes innovative context data suitable for heterogeneous wireless scenarios

– node mobility, path throughput, energy availabilityMMHC main goal is to provide reliable connections in wireless mobile environments– throughput as secondary objective

Ongoing work– from Internet-based to peer-to-peer connectivity– security issues: peer mutual authentication, user incentives,

dynamic level of trust management– spontaneous smart environments based on dynamic clustering

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Any question?

Prototype code and implementation insights:– http://lia.deis.unibo.it/research/MAC/– http://lia.deis.unibo.it/research/MACHINE/– http://lia.deis.unibo.it/research/MMHC/– http://lia.deis.unibo.it/Staff/CarloGiannelli/



MMHC Local PhaseMain goal: quickly achieve connectivity to the Internet

– locally gathers RSSI and estimates CMob/Joint– performs single-hop reliable connections based on

EstimatedEndurance (completely distributed evaluation)– select the most suitable path based on PathMobility and

EstimatedThroughput (distribution of few crucial context information)

Local phase path selection metric: select the path with best trade-off among PathMobility and EstimatedThroughput:

– avoid highly unreliable paths– maximize throughput

Reactively activated at path disruption

Greater priority to connection reliability than quality

36/41


MMHC Global PhaseMain goal: ensure long-term availability enhancing connectivity capabilities

– periodically interact with nearby node to collect PathMobility, EstimatedThroughput, AveragePathEnergy and ResidualPathEnergy

– trigger path modification whenever a link is broken (reactive), ResidualPathEnergy lowers below 0.1 (proactive), or PathMobilitylowers below 0.3 (proactive)

– select the path with best trade-off among EstimatedThroughput and AverageBatteryEnergy

avoid nodes with low battery levelfairly exploit available pathsachieve high connectivity quality

Maximize user perceived quality of service– available paths periodic monitoring and proactive reconfiguration– enhance connectivity opportunities via the role-switch procedure

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Role-switch ProcedureA client can work as bridge among different networks

– the peer connector contribute providing the physical network, e.g., performing as Bluetooth master

– a client starts forwarding data via one of its available paths: it acts as a gateway

Note: role-switch aim at providing only Internet connectivity

F has two paths to the InternetWhen A fails C exploits F as gatewayBoth C and E keep connectivity to the Internet via F

C D

E

InternetInternet

BS1 BS2

F

BA

38/41


MMHC Design

Full NetworkExploitation

SuitablePaths

SuitableChannels

MobilityDegree

Connector monitoring and interface managing(mobile client requirements, e.g., user and OS)

Channel monitoring and routing rule managing(mobile client and remote node requirements)

peer-to-peer service provisioning

Met

ric A

pplic

atio

n

Raw data gathering andmobility degree estimation

RoutingManager

ConnectorManager

P2PManager

Mobility& Peer

Estimator

ComponentName

ProvidedFeature Performed actions

Eva

luat

ion

Pro

cess

AvailableConnectors

Low-level components uniform and aggregated access provisioning

NetworkInterfaceProviderC

onte

xt G

athe

ring

BestPath

One-shot selection among available channels(application specific requirements)

PathApplication

Selector

39/41


MMHC ArchitectureNetwork Interface Provider– homogeneous access to

heterogeneous interfaces on different operating systems

Connector Manager– single-hop connections based

on node mobility

Routing Manager– context information remote

distribution– multi-hop paths based on

estimated connectivity availability and throughput

Network Interface Providerpr

ovid

e co

nnec

tivity

single-hopopportunities

multi-hoppaths

ConnectorManager

connect

IEEE 802.11 Bluetooth UMTS

RoutingManager

local noderequirements

single-hopconnections

receive remote context

send local context

40/41


Network Interface ProviderNetwork Interface Provider (NIP) provides a homogeneous access to heterogeneous interfacesFeatures: set of capabilities common to interfaces

– get available connectors, to get available connectors list and related information such as RSSI

– perform as peer connector, to offer connectivity in a peer-to-peer fashion

– connect to a connector, to perform a connection with a given connector

Network Interface Provider

provideconnectivity

single-hopopportunities

connect

IEEE 802.11 Bluetooth

IEEE 802.11 standard– scan of available ESSID (Extended

Service Set ID)– connectivity provisioning via IBSS

(Independent Basic Service Set)– association to a given AP

41/41


Connector ManagerConnector Manager (CM) establishes single-hop channels with remote devices

1) connectors discovery via any interface2) connectors evaluation based on mobility degree3) requires layer2 connections with most suitable connector of

each interface4) activates layer3 configuration via DHCP client

CM does not interact with remote nodes– mobility degree achieved locally in

a lightweight manner– requirements in terms of maximum

node-connector mutual mobilitysingle-hopopportunities

ConnectorManager

connect

local noderequirements


42/41


Routing ManagerRouting Manager (RM) handles multi-hop paths to the Internet1) context information exchange with one-hop distant nodes2) single-hop distant links evaluation3) routing rule modification to provide suitable multi-hop

paths

multi-hoppaths

RoutingManager


receive remote context

send local context

RM has a wider perspective– mobility, throughput and energy

of paths– discard unreliable paths due to

mobility, then achieve a trade-offamong throughput and energy

43/41


MMHC Performance ResultsTime consuming single-hop creation and efficient path reconfiguration

– CM: reactive (rather static) – RM: proactive (greatly dynamic)

MMHC overhead is negligible– connection establishment delay mainly

due to specific characteristics of wireless technologies

0200400600800

1000

new path path recovery

path change

Res

pons

iven

ess

(mill

isec

onds

)

Routing Manager

3,04

14,37

0,14

0,12

0,12

3,43

2,04

3,29

0,00

2,00

4,00

6,00

8,00

10,00

12,00

14,00

16,00

18,00

20,00

22,00

IEEE 802.11 Bluetooth

Cum

ulat

ive

Tim

e (s

econ

ds)

Automatic DHCP configuration

Wi-Fi association/ Bluetooth PAN connection MMHC connector evaluation

Wi-Fi scan/ Bluetooth inquiry

Connector Manager44/41

Documents

Carlo Giannelli - unibo.it · 2012. 9. 3. · Bologna, Italy — 18.09.2009 Carlo Giannelli 1/41. Agenda Social sharing . of connectivity resources – single/multi-hop wireless networks