MeshDynamics MD4000 Mesh Network Products - Installation Guide
VOIP and Video on a City-wide Scale - Meshdynamics
Transcript of VOIP and Video on a City-wide Scale - Meshdynamics
© 2002-2005 MeshDynamics, Inc. -- Patents Pending. All rights reserved 1Oct –19-2005
VOIP and Video on a City-wide Scale
© 2002-2005 MeshDynamics, Inc. -- Patents Pending. All rights reserved 2Oct –19-2005
VOIP packets inefficient over 802.11 protocols
• Intended for asynchronous not isochronous networking. • Poor latency and jitter control , degrades with more clients
Backhaul must contain jitter and latency over multiple hops Access Point software should help remove contention at the source
© 2002-2005 MeshDynamics, Inc. -- Patents Pending. All rights reserved 3Oct –19-2005
Mesh Backhaul Architecture Comparison for VoIP
Backhaul must contain jitter and latency over multiple hops Access Point software should help remove contention at the source
© 2002-2005 MeshDynamics, Inc. -- Patents Pending. All rights reserved 4Oct –19-2005
Mesh Backhaul Architecture Comparison for VoIP
AP
AP
AP
VoIP packets contend with service radios & other backhaul links
Structure MeshTM with Multi-Radio, Multi-Channel Backhaul1-Radio Ad Hoc Mesh
AP0AP0VoIP packets do not contend with service radios or other backhaul links
A-H
A-H
Backhaul must contain jitter and latency over multiple hops Access Point software should help remove contention at the source
© 2002-2005 MeshDynamics, Inc. -- Patents Pending. All rights reserved 5Oct –19-2005
Mesh Backhaul Architecture Comparison for VoIP
AP
AP
AP
Structure MeshTM with Multi-Radio, Multi-Channel Backhaul“Dual Radio Mesh”
AP0
VoIP packets do not contend with service radios or other backhaul links
VoIP packets contend with service radios & other backhaul links
AP0
AP
AP
Backhaul must contain jitter and latency over multiple hops Access Point software should help remove contention at the source
© 2002-2005 MeshDynamics, Inc. -- Patents Pending. All rights reserved 6Oct –19-2005
Small packets (e.g VOIP) inefficient over 802.11
Typical Data Packet = 1500 bytes (1.44mS, incl .4mS ovhd)
Data
Overhead Data
Overhead
Data
Overhead
VoIP Packet (G.711 Codec) = 230 bytes (.56 mS, incl .4mS ovhd)
VoIP Packet (G.729 Codec) = 90 bytes (.46, incl .4mS ovhd)
Backhaul must contain jitter and latency over multiple hops Access Point software should help remove contention at the source
© 2002-2005 MeshDynamics, Inc. -- Patents Pending. All rights reserved 7Oct –19-2005
Increase VOIP capacity with “bulk containers”
TCP/IP
AAA/ AES ENCRYPTION w/ TEMPORAL KEYS
Send Bulk Containers-To pack more VOIPPackets into backhaul
PACKETCLASSIFIER
VOIPCONCATACCESS POINT
KERNELREAL TIME
EXTENSIONSDRIVERS WITH VLAN SUPPORTThe containers must
leave every XX ms
LINUX KERNEL
ETHERNET
802.11 SERVICE RADIOS
Backhaul must contain jitter and latency over multiple hops Access Point software should help remove contention at the source
© 2002-2005 MeshDynamics, Inc. -- Patents Pending. All rights reserved 8Oct –19-2005
Concatenation Performance Results- Satisfaction
MOS Estimate for 36 simultaneous calls over 4 hops with VOIP concat. Voice quality around 4.22 – satisfied to very satisfied
© 2002-2005 MeshDynamics, Inc. -- Patents Pending. All rights reserved 9Oct –19-2005
Concatenation Performance Results- Latency
One way delay experienced by the 36 simultaneous callers
1. Cannot exceed 20 ms. (Shipments leave every 20 ms)
2. Random Distribution based on when packet enters system
08-18 ms, expected average = 10 ms
© 2002-2005 MeshDynamics, Inc. -- Patents Pending. All rights reserved 10Oct –19-2005
Concatenation Performance Results- Jitter
Jitter experienced by 36 simultaneous callers : < 3 ms
© 2002-2005 MeshDynamics, Inc. -- Patents Pending. All rights reserved 11Oct –19-2005
Concatenation Performance Results- Packet Loss
Max consecutive lost datagrams for 36 simultaneous callers
© 2002-2005 MeshDynamics, Inc. -- Patents Pending. All rights reserved 12Oct –19-2005
Structured MeshTM Backhaul Characteristics
Backhaul has low latency and jitter because
1. No degradation over multiple hops – needed for city wide mesh2. Efficient Bulk container transport of VOIP packets
Backhaul must contain jitter and latency over multiple hops Access Point software should help remove contention at the source
© 2002-2005 MeshDynamics, Inc. -- Patents Pending. All rights reserved 13Oct –19-2005
Time Division Multiple Access is “regular”
• Everyone is allocated a time slot• Intended for isochronous communications • Predictable latency and jitter control
• Challenge: TDMA like behavior within 802.11 framework
© 2002-2005 MeshDynamics, Inc. -- Patents Pending. All rights reserved 14Oct –19-2005
1. Give each phone a “time slice” to send
Remove RF contention
Reduce back off window =>
Predictable Latency/Jitter
AP
© 2002-2005 MeshDynamics, Inc. -- Patents Pending. All rights reserved 15Oct –19-2005
2. Use a common “bulk container” to receive
Use this time slice to send backA “bulk” packet for all phones.
1. No contention on send path2. No contention on recv. Path
-> Better VOIP Performance
AP
© 2002-2005 MeshDynamics, Inc. -- Patents Pending. All rights reserved 16Oct –19-2005
Each Phone has time to do “Other Stuff”.
AP
Free time
© 2002-2005 MeshDynamics, Inc. -- Patents Pending. All rights reserved 17Oct –19-2005
Each Phone has time to do “Other Stuff”.
DATA APAP APVOICE AP
1 32
Bulk receive
Send and Receive Data on 2nd AP. Use this timefor Mobility Scanning.
Send one VOIP Packet from Phone To AP
© 2002-2005 MeshDynamics, Inc. -- Patents Pending. All rights reserved 18Oct –19-2005
Summary
Backhaul has low latency and jitter because
1. No degradation over multiple hops – needed for city wide mesh2. Bulk container transport of VCIP packets
Access Point with “TDMA like“ enhancements for:
1. No contention on send cycle with Time Slices2. No contention on receive cycle, with bulk broadcast
Backhaul must contain jitter and latency over multiple hops Access Point software should help remove contention at the source