Research topic: Multimedia Communication over ... - Kau

20070925 Karlstad University

Research topic:

Multimedia Communicationover

Wireless Mesh Networks

Marcel Castro


Education background

� Bachelor in Electrical Eng. - Federal University of Goias, Goiânia, Brazil – 2000

� Master or Science in Electrical Eng. – State University of Campinas (UNICAMP), Campinas, Brazil - 2004

� PhD in Computer Science – Karlstad University (KAU), Karlstad, Sweden - present


Outline

� Introduction� Wireless Mesh Networks� Usage Scenarios� Challenges

� Current Work and Contributions� VoIP over hybrid MANETs � Routing Metrics Evaluation� Multimedia Communication over P2P in WMNs

� Future Work


Wireless Mesh Networks

Wireless routers

Gateways

Printers, servers

Mobile clients

Stationary clients

Intra-mesh wireless links

Stationary client access

Mobile client access

Internet access links

Node Types Link Types


Usage ScenariosResidential/Home Networks

Campus/Community/Public

Office

Access Router/GW


Mesh Networks: Challenges� Transmission Range

� Directional Antenna or MIMO � Multiple Frequencies� Multi-radio interfaces

� Multihop Routing� Route Selection with multiple radios� Multiple paths� Routing to/from gateway

� Security, Privacy� Malicious Users� Admission Control

� Self Management� Minimal human intervention – avoid network operator

� Smart Spectrum Utilization� Use of non-interference channels

� Capacity� Header Compression� Aggregation of traffic� Priorization

� Mobility� Multihop Handover� Mobile Gateways

� Service Scalability� Quality of Service� Real-time applications

Gat

eway

1

InternetInternet

Gateway 2


Outline



� Future Work


VoIP over Hybrid MANETs

� Voice over IP� Very hot topic in 3G� Uses packetized voice over RTP/UDP/IP

• High overhead for small voice packets when used over standard 802.11

� Signalling via SIP involves 2 centralized entities: Registrar and Proxy

User A User BMobile Communication Devices

Wireless Sensors

Mobile PDAs

Laptops

Mobile Ad Hoc NetworkMobile Ad Hoc Network

Mobile Communication Devices

Wireless Sensors

Mobile PDAs

Laptops

Mobile Ad Hoc NetworkMobile Ad Hoc NetworkInternet ConnectivityInternet Connectivity

Telecom Network

Public Internet

Wireless Access Networks

e.g. GPRS/UMTS/WLAN

Telecom Network

Public Internet

Wireless Access Networks

e.g. GPRS/UMTS/WLAN


� Possible Solutions Analyzed*� Standard Approach� Proxy located at Gateway

� Distributed SIP

� SIP and Service Discovery� Peer-to-Peer SIP

Motivation and Characteristics� Key Issue: How to provide VoIP services?

� Potential performance degradation• Self Interference due to forwarding

• Routing required

� Call Setup Delay:• below 5 sec for user satisfaction and interworking with ISDN:

– SIP signaling delay, network dependent

– SIP processing delay, proxy dependent– Amount of signaling traffic

* * M.C. Castro, A.J. Kassler, “ SIP based Service Provisioning for hybrid MANETs” . IWT2007, Brazil, Feb. 2007

InternetAR2

AR3

Proxy/ Registrar

INVITE,..Media

SIP Request/ResponseRTP Media SamplesLink Connectivity

AR1


Standard Approach - Simulation� A brief insight through ns-2 simulation:

� Hybrid MANETs, MNs in grid, � Different voice background traffic:

• ITU G729: 8Kbps, 20ms• Bidirectional Exponential traffic

– talk/silence: 350ms/650ms

• Distance btw source/destination: 2-7 hops• Out-In: 25%-75%

� SIP INVITE TA• SIP Request payload: 500 bytes• SIP Response payload: 300bytes

� Performance in terms of:• SIP Call setup delay:

– Time btw SIP INVITE and 200 OK

• SIP Call Blocking Probability• SIP msg loss

AODV-UU Hello Interval: 1sRouting towards Gateway

using tunneling

Link speed of 5Mbps / 2ms

IEEE 802.11gData Rate = 24Mbps

Carrier Sence = 500mReceived Threshold = 250mNode space in grid = 200mTwoRayGround:Frequency: 2.4GHzTransmission Power = 100mWTx/Rx Antenna height = 1,5mTx/Rx Antenna gain = 1dBSesitivity = -85dBm


Standard Approach - Simulation*ITU-T E.721, Network grade of service parameters and target valu es for circuit-switched services in the evolving is dn , May 1999.

0

0,1

0,2

0,3

0,4

0,5

0,6

0,7

0,8

0,9

1

4 8 12 16 24 32

Number of background flows

Ca

ll b

lock

ing

pro

ba

bili

ty (

<5

sec)

7 hops 1 gatew ay

5 hops 1 gatew ay

2 hops 1 gatew ay

0

50

100

150

200

250

300

350

400

450

500

4 8 12 16 24 32

Number of background flows

Nu

mb

er o

f SI

P IN

VIT

E m

essa

ges

Re-invitations due to SIP timeout - 2 hops Re-invitations due to SIP t imeout - 5 hops

Re-invitations due to SIP msg dropped - 2 hops Re-invitations due to SIP msg dropped - 5 hops

Alternative Approaches

Desired� Call Setup Delay (s)

� Blocking Probability

� SIP msg. drops


Proxy located at Gateway

� Gateway acts as SIP proxy/registrar on behalf of MANET nodes� MANET nodes need to have information about the proxy

� Static configuration, or

� Autoconfiguration: Extension of GW discoverymechanism to inform MN about Gateway SIP Capability .

* M.C. Castro, A.J. Kassler A.J., “ Challenges of SIP in Internet Connected MANETs” , Proc. of Int. Symposium of Wireless Pervasive Computing, Puerto Rico, February 2007.

InternetAR2

AR3

Proxy/ Registrar

INVITE,..

Proxy/Registrar

SIP Request/ResponseRTP Media SamplesLink Connectivity

AR1

Media


Proxy located at Gateway

� Call Setup Delay where Proxy at AN/GW

�Call Setup Delay versus number of hops

�PLR versus number of hops


Outline


� Current Work and Contributions� VoIP over hybrid MANETs� Routing Metrics Evaluation� Multimedia Communication over P2P in WMNs

� Future Work


Routing Metrics in WMNs

Related Work:

� QoS related approach:� Calculate spare bandwidth� Perform admission control on new flow

• [Chen & Heinzelman, JSAC05]

� Best-effort approach:� Various routing metrics



� Routing Metric should count:� Path Length� Link Capacity� Packet Loss Ratio� Interference:

• Inter-flow interference:

• Intra-flow interference:



� ETX – Expected Transmission Count [De Couto et al., MobiCom03]

� WCETT – Weight Cumulative ETT[Draves et al., MobiCom04]

� MIC – Metric of Interference and Channel Switching[Yang et al., WiMesh05]


Why new metrics ?

� Metric needs to incorporate existing traffic and self-traffic:

Self-traffic


How to do it ?

� Use MAC timers

� Carrier sense and hidden

terminal information

[Saha, PhD thesis, Rice Univ., 07]

[Yin et al., JWCMC06]


Where to use it ?

� Packet Aggregation

� Traffic aware routing

DIFS Backoff SIFS DIFS Backoff SIFS DIFS Backoff

DATA

SIFS t

MAC

IPUDP

RTP

AUDIOMAC

IPUDP

RTP

AUDIO

ACK

MAC

IPUDP

RTP

AUDIO

ACK ACK

DIFS Backoff

DATA

SIFS

saved transmission time

t

MAC

IPUDP

RTP

AUDIO IPUDP

RTP

AUDIO IPUDP

RTP

AUDIOIP

AH

ACK


Outline



� Future Work


P2P in WMNs

� Advantages of P2P over centralized infrastructure:� Significant autonomy from central servers� Exploits resources at the edges of the Internet

• storage and content• CPU cycles

� Resources at edge have intermittent connectivity, being added & removed

� Classification:� Unstructured P2P file sharing: Napster, Gnutella, KaZaA,

search theory, flashfloods� Structured DHT systems: Chord, CAN, Pastry, Tapestry,

Bamboo, etc


Broad definition

❒ P2P file sharing❍ Napster, Gnutella, KaZaA, etc

❒ P2P communication❍ Instant messaging

❒ P2P computation ❍ seti@home

❒ DHTs & their apps❍ Chord, CAN, Pastry, Tapestry

❒ P2P apps built over emerging overlays❍ PlanetLab


Peer-to-Peer SIP

P2P overlay

Alice128.59.19.194

REGISTERINVITE alice

128.59.19.194

No central server, but potentially higher search latency

Alice’s host128.59.19.194Client-server� maintenance, configuration, controlled infrastructure

[email protected] =>128.59.19.194INVITE [email protected]

Contact: 128.59.19.194columbia.edu

Cross-layer design:-Interaction between P2P Protocols (DHT maintenance) and SIP -All SIP users participate in the P2P overlay

Cross-layer design:-Interaction between P2P Protocols (DHT maintenance) and SIP -All SIP users participate in the P2P overlay


Peer-to-Peer SIP – cont.� P2P SIP Functions

� Lookup: Find a node that is responsible for given ID through INVITE• Node answers 200OK if responsible, otherwise 302 moved temporarily

� Join the P2P overlay• Send REGISTER to Bootstrap node with nodeID, build up finger table

� Leave the P2P• Leaving node stores ressources at predecessor

� Distributed hash table (DHT)� Manage SIP user location

• Node-ID 683 = hash([email protected])

� Overlay maintanance� P2P protocol, e.g: OpenDHT, or� SIP REGISTER may transport DHT

� Internet connected MANET� Hierarchy of P2P SIP network

• GW must act as P2P SIP proxy/registrar

Node ANode-ID 023

Node BNode-ID 245

Node CNode-ID 520

Alice’s NodeNode-ID 503

Bob’s NodeNode-ID 683

INVITE

302 Bob’s Node

2. INVITE

Alice trying to contact Bob


P2P SIP with DHT in hybrid MANET � Problems

� Which protocol is used to maintain P2P SIP Overlay?• Reuse SIP REGISTER for maintaining overlay structure• Use OpenDHT for register and SIP for INVITE TA

� Performance of DHT in MANET under mobility and high churn rate? � Interworking with external networks:

• Need P2PSIP node to act as gateway to external networks • How P2PSIP finds those gateways ?

� How to contact external nodes?� Cross register OR� Locate user during call setup

• DNS – GW or Bootstrap nodes represent the domain

• P2P SIP Hierarchy– GW reachable from global and local P2P SIP Network


Current Status

� VoIP over Hybrid MANETs� Four proposals described� Scalability versus number of hops, gateways, and

different number of traffics.� Simulation in NS-2: SIP + AODV-UU


Outline



� Future Work


Future Plans

� VoIP over Hybrid MANETs� Evaluate SIP over P2P in simulation and testbed (using Linksys

WRT54GL)

� Packet Aggregation� Design of optimal Aggregation Technique using Traffic-aware Routing

Metric� Evaluation of packet aggregation over testbed

� P2P Systems in WMNs� Cross-layer adaptation (physical location, link condition, …) � Support of Quality of Service (Admission control, class of service, …)


Thank you!Marcel C. Castro

[email protected]/~marccava


Backup Slides


Node Joining – Extended SIP Msg

� Iterative search increases reliability

Bootstrap NodeNode-ID 023

Node BNode-ID 245

Joining NodeNode-ID 503

1. REGISTER

302 Node B

2. REGISTER

302 Node C3. REGISTER

200 OK

4. Joining node after joinNode-ID 503

Node CNode-ID 520Key = Hash(10.0.0.53) =

Node-ID 503

REGISTER sip:10.0.0.23 SIP/2.0To: <sip:[email protected];user=node>From: <sip:[email protected];user=node>Contact: <sip:[email protected];user=node>Expires: 600DHT-NodeID: <sip:[email protected];user=node>;algorithm=sha1;overlay=chat;expires=600Require: dhtSupported: dht


User Registration – Extended SIP Msg

� User’s node must register in DHT

Node ANode-ID 023

Node BNode-ID 245



Key = Hash([email protected])=

Alice -> 234

1. REGISTER

302 Node B

2. REGISTER

200 OKAlice-> Alice’s Node

� SIP REGISTER used for nodes and users

Node CNode-ID 520

REGISTER sip:10.0.0.23 SIP/2.0To: <sip:[email protected]; resourceID=234>From: <sip:[email protected]; resourceID=234>Contact: <sip:[email protected]>Expires: 600DHT-NodeID: <sip:[email protected];user=node>;algorithm=sha1;overlay=chat;expires=1200Require: dhtSupported: dht


Contacting a User – Extended SIP Msg

Node ANode-ID 023

Node BNode-ID 245

Node CNode-ID 520


Alice -> 234

Bob -> 723

Alice-> Alice’s Node

Bob-> Bob’s Node

� DHT used for initial location


1. INVITE

302 Bob’s Node

2. INVITE

REGISTER sip:10.0.0.23 SIP/2.0To: <sip:[email protected];resourceID=723>From: <sip:[email protected]; resourceID=234>DHT-NodeID: <sip:[email protected];user=node>;algorithm=sha1;overlay=chat;expires=800Require: dhtSupported: dht


Session Establishment

Node ANode-ID 023

Node BNode-ID 245

Node CNode-ID 520


Alice -> 234

Bob -> 723

Alice-> Alice’s Node

Bob-> Bob’s Node

� Standard SIP used for connection

� No reliance on DHT


Research topic: Multimedia Communication over ... - Kau

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