Radio over IP (RoIP) is a technology that has emerged over the last 10 years and has provided a powerful and flexible mechanism for linking radios and dispatch consoles. RoIP has some inherent limitations and numerous technical challenges. This workshop will provide an overview of the technology, the key standards and some of the technical issues. The workshop will cover on the following issues: - The difference between RoIP and VoIP — how radio systems differ from phone systems - Implementing one-to-one connections - Implementing many-to-many connections - Risk management: identifying network issues affecting RoIP/VoIP quality, maintenance and redundancy - Design elements: building blocks; calculating network bandwidth requirements The implications of RoIP for dispatch consoles will be also be discussed: how dispatch console to radio connections can be implemented with RoIP and how RoIP can be used to provide fault-tolerant dispatch architectures. Finally, the workshop will look at the impact of new technologies such as IPv6, wireless broadband and the switch to digital radio on the RoIP landscape. Paul Whitfield, Team Leader: Software Engineering, Omnitronics

1. Presenta(on
Title:
Advanced
Radio
Over
IP
Speaker:
Paul
Whi<ield
@CommsConnectAus
#comms2014
COMMS
CONNECT
2014

2. COMMS
CONNECT
2014
Overview
• Introduc(on
to
RoIP
• VoIP
Protocols
– Real
Time
Protocol
– Session
Ini(a(on
Protocol
• Voice
Quality
Issues
• IP
based
console
architecture

3. COMMS
CONNECT
2014
Radio
over
Internet
Protocol
• Voice
over
IP
for
Radio
– No
standard
• Proprietary
Solu(ons
• Digital
Radio

4. COMMS
CONNECT
2014
Networks
• IP
Networks
– Local
Area
Networks
– Wide
Area
networks
– The
Internet

5. COMMS
CONNECT
2014
Network
Providers
• DSL
• Satellite
• Microwave
• 3G
/
4G
Mobile
networks

6. COMMS
CONNECT
2014
Benefits
of
RoIP
• Lower
Cost
• Reliability
• Remote
management
• Interoperability
• Flexibility

7. COMMS
CONNECT
2014
How
is
RoIP
different?
• No
central
service
provider
• Half/Full
Duplex
• Push
To
Talk
/
Busy
• Connec(on
“Health”

8. COMMS
CONNECT
2014
Applica(ons
of
RoIP
• Remote
access
to
Radios
• Point-­‐to-­‐point
radio
interconnec(on
– (also
point
to
mul(point)
– Cross-­‐banding
• Radio
to
Dispatch
console
• Radio
to
phone
gateway

9. Remote
Access

10. Interoperability

11. IP
Based
Dispatch
Solu:on

12. COMMS
CONNECT
2014
VoIP
• Telephone
model
• Assumes
a
service
provider
(external)
– One-­‐to-­‐one
calls
– Short
dura(on
calls
• Audio
only

13. COMMS
CONNECT
2014
RoIP
• Single
Organisa(on
• Dedicated
Links
• Peer-­‐to-­‐peer
• Includes
one-­‐to-­‐many

14. COMMS
CONNECT
2014
VoIP
Standards
• Real
Time
Protocol
–
RTP
– Voice
• Session
Ini(a(on
Protocol
–
SIP
– Call
management

15. COMMS
CONNECT
2014
Standards
-­‐
Advantages
• Vendor
Independent
• Easier
to
interface
to
VoIP
• Off
the
shelf
voice
recorders
• Recognised
by
– Routers
/
Firewalls
– Network
Tools

16. COMMS
CONNECT
2014
Standards
-­‐
Disadvantages
• Complicated
• Not
an
exact
fit
• Interoperability
is
not
guaranteed.

17. COMMS
CONNECT
2014
Real
Time
Protocol
• Standard
for
Audio
and
Video
– RFC
3550
and
RFC
3551
• Telephony,
Video
conferencing
and
Television
• Real
Time
is
more
important
that
100%
reliable.

18. COMMS
CONNECT
2014
Real
Time
Protocol
• Supports
Unicast
(one
to
one)
• Supports
Mul(cast
(one
to
many)
• Detects
lost
packets
• Detects
out
of
order
packets
• Compensates
for
packet
jieer

19. COMMS
CONNECT
2014
UDP
–
User
Datagram
Protocol
• Used
by
RTP
(but
why?)
– Datagrams
– Simple
– Stateless
• No
retransmission
CommsConnect
2013
IP
UDP
RTP
SIP
TCP
HTTP

20. COMMS
CONNECT
2014
Transmission
Control
Protocol
• Reliable
• Ordered
• Not
real-­‐(me
CommsConnect
2013

21. COMMS
CONNECT
2014
Issues
• What
are
the
issues
with
RoIP?

22. COMMS
CONNECT
2014
Delay
• Two
Types
of
delay
– Constant
-­‐>
Latency
– Variable
-­‐>
Jieer
• Jieer
delay
requires
audio
buffering

23. COMMS
CONNECT
2014
Sources
of
Delay
• Framing
Packe(sa(on
–
20
ms
• Sojware
Processing
• Jieer
Buffering
• Network
Delay
• Typical
delay
– 100
milliseconds
one
way.

24. COMMS
CONNECT
2014
Audio
Delay
Sender
Codec
Packe(sa(on
Processing
Receiver
Processing
Jieer
Buffer
Codec
Network

25. COMMS
CONNECT
2014
Radio
with
Delay
• ½
Duplex
systems
are
more
tolerant
of
delay
• Push
to
Talk
synchronisa(on
with
audio
• Radio
with
setup
(mes
can
be
an
advantage
– Fast
track
the
Push
To
Talk

26. COMMS
CONNECT
2014
Echo
• Sources
of
Echo
– Telephone
Hybrids
– Side-­‐tone
– Dispatch
operator
audio
/
cross-­‐talk
• Full
Duplex
audio
with
Echo
+
Delay
is
a
problem

27. COMMS
CONNECT
2014
Packet
Loss

28. COMMS
CONNECT
2014
Packet
Loss
• RTP
uses
UDP
–
packets
can
get
lost
L
• RTP
Detects
packets
have
been
lost
• Packet
Loss
Concealment
(PLC)

29. COMMS
CONNECT
2014
Echo
Cancela(on
• DSP
algorithm
–
Adap(ve
Filter
• Take
(me
to
converge
• Issues
with
“Double
Talk”
• Acous(c
Echo

30. COMMS
CONNECT
2014
Reference
Sound:
G.711

31. COMMS
CONNECT
2014
Packet
Loss:
20
%
G7.11

32. COMMS
CONNECT
2014
Packet
Loss:
20%
GSM

33. COMMS
CONNECT
2014
Prac(cal
Packet
Loss
• WiFi
/
Radio
• Microwave
Links
• Normal
wired
networks
work
or
they
don’t
– 0
%
or
100%
– Conges(on

34. COMMS
CONNECT
2014
Prac(cal
Tip
• Ping
• Basic
test
tool.

35. COMMS
CONNECT
2014
Encoding
Voice
–
World
Fair
1939

36. COMMS
CONNECT
2014
Voice
Encoders
/
Decoders

37. COMMS
CONNECT
2014
Codecs
• Coder
/
Decoder
• Compression
Lossy
• Require
low-­‐latency

38. COMMS
CONNECT
2014
G.711
• 8-­‐Bit,
8
kHz
:
64
000
bits
per
second
• Standard
• Widely
supported
-­‐ µ-­‐law
and
A-­‐law
-­‐ RTP
Payloads
0
and
8.

39. COMMS
CONNECT
2014
G.726
• Adap(ve
Differen(al
Pulse
Code
Modula(on
ADPCM
• Various
Data
Rates:
48000,
32000,
24000,
16000
bits
per
second

40. COMMS
CONNECT
2014
GSM
• 2G
Mobile
Phone
• Full
Rate
–
13
000
bits
per
second
• Patents

41. COMMS
CONNECT
2014
G729
• 8000
bits
per
second
• Patent
License
required
• Can
not
carry
tones
• G729A
–
lower
quality
/
lower
calcula(ons

42. COMMS
CONNECT
2014
IMBE
/
AMBE
• Improved
Mul(-­‐Band
Excita(on:
7200
bps
• Advanced
Mul(-­‐Band
Excita(on:
3600
bps
• Digital
Radio:
– APCO
P25,
DMR-­‐AIS,
NXDN
and
MotoTRBO
• Covered
by
Patents
• Includes
error
correc(on

43. COMMS
CONNECT
2014
High
Compression
Codecs
• Effect
on
Tones
• AMBE2+
Includes
Tone
Detec(on
• Cascades
– Compress
/
Uncompress
/
Recompress

44. COMMS
CONNECT
2014
Codec G.711 G726-­‐32 GSM G729
AMBE
(with
FEC)
Packet
Duration
(milliseconds) 40 40 40 40 40
Samples
per
Packet 320 320 320 320 320
Packets
per
second 25 25 25 25 25
Overhead
per
Packet
(IP+UDP+RTP) 40 40 40 40 40
Packet
Size
320 160 66 40 18
Bandwidth
bits
per
second 72000 40000 21200 16000 11600
Radio
over
Internet
Protocol
:
Bandwidth
Calculator

45. COMMS
CONNECT
2014
Codec G.711 G726-­‐32 GSM G729
AMBE
(with
FEC)
Packet
Duration
(milliseconds) 80 80 80 80 80
Samples
per
Packet 640 640 640 640 640
Packets
per
second 12.5 12.5 12.5 12.5 12.5
Overhead
per
Packet
(IP+UDP+RTP) 40 40 40 40 40
Packet
Size
640 320 132 80 36
Bandwidth
bits
per
second 68000 36000 17200 12000 7600
Radio
over
Internet
Protocol
:
Bandwidth
Calculator

46. COMMS
CONNECT
2014
Codec G.711 G726-­‐32 GSM G729
AMBE
(with
FEC)
Packet
Duration
(milliseconds) 20 20 20 20 20
Samples
per
Packet 160 160 160 160 160
Packets
per
second 50 50 50 50 50
Overhead
per
Packet
(IP+UDP+RTP) 40 40 40 40 40
Packet
Size
160 80 33 20 9
Bandwidth
bits
per
second 80000 48000 29200 24000 19600
Radio
over
Internet
Protocol
:
Bandwidth
Calculator

47. COMMS
CONNECT
2014
Connec(ng
Mul(ple
Radios
/
Consoles
• Unicast
–
Normal,
Point-­‐to-­‐Point
• Broadcast
–
One
to
everyone
– Local
Area
Network
Only
• Mul(cast
–
One
to
Many

48. COMMS
CONNECT
2014
Mul(cast
• One
to
many
• Source
device
sends
1
copy
– Routers
create
more
copies
if
required
• Des(na(on
devices
must
“join”
Mul(cast
group
• Requires
network
router
support
(IT
support)
• Not
supported
on
the
Internet

49. COMMS
CONNECT
2014
Conferencing
• Connect
Mul(ple
sites
/
operators
via
Unicast
• Forward
RTP
packets
– Simple
– Minimises
delay
– S(ll
have
the
“source”
metadata
• Decode
/
Mix
/
Retransmit
– Complicated
– More
delays

50. COMMS
CONNECT
2014
VoIP
Recording
• Mul(cas(ng
+
Conferencing
• Network
Tap
at
router

51. COMMS
CONNECT
2014
Session
Ini(a(on
Protocol
• Signalling
protocol
for
– Telephone
calls
– mul(media
• RFC
3261
• Similar
to
HTTP
-­‐
Text
based.
• Long
and
complicated
standard

52. COMMS
CONNECT
2014
What
does
SIP
do?
• Register
with
Central
Server
• Signalling
protocol
• Makes
and
Breaks
calls
• Nego(ates
how
audio
is
encoded
• What
network
address
/
ports
• Nego(ate
device
capabili(es

53. COMMS
CONNECT
2014
Uniform
Resource
Iden(fier
sip:username:password@host:port

54. COMMS
CONNECT
2014
Example
SIP
Packet
INVITE sip:bob@biloxi.com SIP/2.0
Via: SIP/2.0/UDP pc33.atlanta.com;branch=z9hG4bK776asdhds
Max-Forwards: 70
To: Bob <sip:bob@biloxi.com>
From: Alice <sip:alice@atlanta.com>;tag=1928301774
Call-ID: a84b4c76e66710@pc33.atlanta.com
CSeq: 314159 INVITE
Contact: <sip:alice@pc33.atlanta.com>

55. COMMS
CONNECT
2014
Session
Descrip(on
Protocol
• Included
in
SIP
“offer”
and
“answer”
• Describes
– IP
Addresses
– IP
Ports
– RTP
Payload
Values
and
Codecs

56. COMMS
CONNECT
2014
Example
Content-Type: application/sdp
Content-Length: 178
v=0
o=3 123456 654321 IN IP4 192.168.20.67
s=Radio Over IP Session
c=IN IP4 192.168.20.67
t=0 0
a=sendrecv
a=floor
m=audio 10000 RTP/AVP 100
a=rtpmap:100 DMR-AIS/8000

57. COMMS
CONNECT
2014
Prac(cal
Tip
• Wireshark
is
your
friend.
• Essen(al
network
tool.
• Supported
for
all
major
sojware
pla<orms
• Can
play
VoIP
calls
that
use
G.711

58. COMMS
CONNECT
2014
SIP
and
Digital
Radio
• Digital
Radio
Standards
based
on
SIP
– P25
ISSI
/
P25
CSSI
– DMR-­‐AIS

59. COMMS
CONNECT
2014
What
SIP
does
not
do.
• Transport
audio
• Transport
Radio
Informa(on
(or
does
it?)
• Detect
link
failures

60. COMMS
CONNECT
2014
Network
Address
Transla(on
• IPv4
–
Private
and
Public
IP
Addresses
CommsConnect
2013

61. COMMS
CONNECT
2014
SIP
and
NAT
• NAT
in
router
changes
IP
addresses
– Public
<-­‐>
Private
• SIP
message
contain
IP
addresses
and
IP
Ports
the
router
can
not
change
them

62. COMMS
CONNECT
2014
How
to
fix
it
• SIP
Applica(on
Level
Gateways
– Detect
and
modify
the
SIP
messages
on
the
fly
• Virtual
Private
Networks
(VPN)
• Interac(ve
Connec(vity
Establishment
ICE
– Uses
STUN
and
TURN
to
make
the
connec(on

63. COMMS
CONNECT
2014
ICE
• Includes
mul(ple
addresses
/
ports
in
the
Session
Descrip(on
• Systema(cally
try
all
possible
values
un(l
one
works.

64. COMMS
CONNECT
2014
Detec(ng
Link
Failure
• RTP
keep-­‐alive
messages
• SIP
keep-­‐alive
messages

65. COMMS
CONNECT
2014
Digital
Radio
• Extra
Informa(on
– Radio
ID
– Call
Type
(Broadcast,
Group,
Individual)
– Radio
Status
/
Text
Messaging

66. COMMS
CONNECT
2014
RTP
and
Extra
Informa(on
• Push
To
Talk
/
Busy
– Telephone
Events
– Custom
Packet
Type
– RTP
Extension
• Used
by
Digital
Radio

67. COMMS
CONNECT
2014
Security
• Encryp(on
for
SIP
(call
setup)
– Transport
Layer
Security
(TLS)
• Encryp(on
for
Voice
– SRTP
– ZRTP

68. COMMS
CONNECT
2014
New
Developments

69. COMMS
CONNECT
2014
Digital
Radio
• Mul(ple
Standards
• Not
interoperable
– How
to
bridge
radios?

70. COMMS
CONNECT
2014
IPv6
• Coming
soon
to
a
network
near
you
• Eliminates
need
for
NAT/STUN/TURN
• IPv4
and
IPv6
can
co-­‐exist
• Not
widely
supported
(yet).

71. COMMS
CONNECT
2014
Dispatch
Console
Architecture
• RoIP
provides
more
op(ons
for
Dispatch
console
solu(ons.

72. COMMS
CONNECT
2014
Dispatch
Consoles
• SIP
Connec(ons
• Direct
RTP
Connec(ons
– Requires
sta(c
IP
addresses
• Mul(cast
Connec(ons
• Central
Server
IP
Connec(ons

73. COMMS
CONNECT
2014
PC
Console
Clients
–
No
Server
• Reduce
single
failure
points
• Flexible
• Cost
effec(ve
-­‐
less
equipment
• Scaling
Issues
– Every
console
connects
to
every
device
– Firewall
configura(on

74. COMMS
CONNECT
2014
Console
Architecture:
No
Server
DMR
Talk
Group
2
P25

75. COMMS
CONNECT
2014
Console
Server
• Remote
connec(ons
• Linking
between
radios
• Single
point
configura(on
• Centralised
diagnos(c
/
management
tools
• Provide
failover
and
redundancy

76. COMMS
CONNECT
2014
Console
Architecture:
Server

77. COMMS
CONNECT
2014
Consoles
-­‐
Mul(ple
Servers
• Same
Console
-­‐
mixed
channels
• Load
sharing
Site
1
Site
2
SERVER
1
SERVER
2
Digital
Radio
Gateway
Digital
Radio
Gateway

78. COMMS
CONNECT
2014
Consoles
–
Redundant
Servers
• Main
and
Standby
-­‐
Failover
Site
1
Site
2
MAIN
Site
3
Digital
Radio
Gateway
STANDBY
Digital
Radio
Gateway
Digital
Radio
Gateway

79. COMMS
CONNECT
2014
Direct
Digital
Radio
Connec(ons
• Minimise
delays
• Less
equipment
• Cannot
mix
audio
without
decoding
• Scaling
Issues
– Number
of
connec(ons
&
Licensing
– P25
DFSI
supports
single
connec(on
Link

80. COMMS
CONNECT
2014
Digital
Radio
Gateway
• Interoperability
– Standard
interface
– Protocol
conversion
• Linking
between
Radios
• Scalable
– Support
mul(ple
connec(ons
– Isolate
Low
Bandwidth
radio
links
Link

81. COMMS
CONNECT
2014
www.omnitronicsworld.com
hep://omnitronicsworld.com/download-­‐
understanding-­‐roip-­‐networks-­‐white-­‐paper/

82. www.comms-­‐connect.com.au
Conference
materials
available
soon
at
COMMS
CONNECT
2014
@CommsConnectAus
#comms2014