Post on 20-Apr-2022
20070925 Karlstad University
Research topic:
Multimedia Communicationover
Wireless Mesh Networks
Marcel Castro
20070925 Karlstad University
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
20070925 Karlstad University
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
20070925 Karlstad University
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
20070925 Karlstad University
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
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Usage ScenariosResidential/Home Networks
Campus/Community/Public
Office
Access Router/GW
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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
20070925 Karlstad University
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
20070925 Karlstad University
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
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� 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
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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
20070925 Karlstad University
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
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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
20070925 Karlstad University
Proxy located at Gateway
� Call Setup Delay where Proxy at AN/GW
�Call Setup Delay versus number of hops
�PLR versus number of hops
20070925 Karlstad University
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
20070925 Karlstad University
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
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Routing Metrics in WMNs
� Routing Metric should count:� Path Length� Link Capacity� Packet Loss Ratio� Interference:
• Inter-flow interference:
• Intra-flow interference:
20070925 Karlstad University
Routing Metrics in WMNs
� 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]
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Why new metrics ?
� Metric needs to incorporate existing traffic and self-traffic:
Self-traffic
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How to do it ?
� Use MAC timers
� Carrier sense and hidden
terminal information
[Saha, PhD thesis, Rice Univ., 07]
[Yin et al., JWCMC06]
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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
20070925 Karlstad University
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
20070925 Karlstad University
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
20070925 Karlstad University
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
20070925 Karlstad University
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
REGISTERalice@columbia.edu =>128.59.19.194INVITE alice@columbia.edu
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
20070925 Karlstad University
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(bob@kau.se)
� 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
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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
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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
20070925 Karlstad University
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
20070925 Karlstad University
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, …)
20070925 Karlstad University
Thank you!Marcel C. Castro
marccava@kau.sewww.cs.kau.se/~marccava
20070925 Karlstad University
Backup Slides
20070925 Karlstad University
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:503@10.0.0.53;user=node>From: <sip:503@10.0.0.53;user=node>Contact: <sip:503@10.0.0.53;user=node>Expires: 600DHT-NodeID: <sip:503@10.0.0.53;user=node>;algorithm=sha1;overlay=chat;expires=600Require: dhtSupported: dht
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User Registration – Extended SIP Msg
� User’s node must register in DHT
Node ANode-ID 023
Node BNode-ID 245
Alice’s NodeNode-ID 503
Alice’s NodeNode-ID 503
Key = Hash(alice@example.com)=
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:alice@example.com; resourceID=234>From: <sip:alice@example.com; resourceID=234>Contact: <sip:alice@10.0.0.53>Expires: 600DHT-NodeID: <sip:503@10.0.0.53;user=node>;algorithm=sha1;overlay=chat;expires=1200Require: dhtSupported: dht
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Contacting a User – Extended SIP Msg
Node ANode-ID 023
Node BNode-ID 245
Node CNode-ID 520
Alice’s NodeNode-ID 503
Alice -> 234
Bob -> 723
Alice-> Alice’s Node
Bob-> Bob’s Node
� DHT used for initial location
Bob’s NodeNode-ID 683
1. INVITE
302 Bob’s Node
2. INVITE
REGISTER sip:10.0.0.23 SIP/2.0To: <sip:bob@example.com;resourceID=723>From: <sip:alice@example.com; resourceID=234>DHT-NodeID: <sip:503@10.0.0.53;user=node>;algorithm=sha1;overlay=chat;expires=800Require: dhtSupported: dht
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Session Establishment
Node ANode-ID 023
Node BNode-ID 245
Node CNode-ID 520
Alice’s NodeNode-ID 503
Alice -> 234
Bob -> 723
Alice-> Alice’s Node
Bob-> Bob’s Node
� Standard SIP used for connection
� No reliance on DHT
Bob’s NodeNode-ID 683