VSAT technology

1. Considerations for 3G
and 4G over VSAT
Michele Di Paolo
VP, Mobile Network Operator (MNO) Solution and
Business Development
ComtechEFData

2. Considerations for 3G
over VSAT
2

3. 3
UMTS (3G) Topology
• The Universal Mobile Telecommunications
System (UMTS) is a third generation mobile cellular
system

4. 4
Considerations for 3G over VSAT
• MNO expectations:
– Deliver services with terrestrial level KPIs*.
– Respect existing network transport (L2 transport)
– Respect MNO defined QOS
– High availability
• Keys to achieving MNO expectations:
– Low jitter and delay variations
– Support L2 protocols (VLAN/MPLS) and L3
– 3GPP Compliant QOS performance
– Error free delivery (AUPC/ACM)
(*) Note: KPIs does not mean necessarily user experience (throughput, response time)

5. 5
Maintaining highest KPI
• Most significant KPI moving forward to 3G is RRC (Radio
Resource Control) Success Rate which manages the control
plane between RNC and the Ue and is responsible for Radio
Resource management.
• Jitter in excess of 10msecs resulting in packets not being
delivered on time, retransmissions, dropped Ues, etc.
It is not just about delivering bandwidth
RRC KPI
Success rate
of 99.95%
recorded.

6. 6
Maintaining highest throughput
• 3G NodeB manages UL traffic from the Ues.
• Additional delay and/or jitter variation in UL traffic is
detected at RNC which sends congestion notification to
NodeB to throttle down UL.
• This results in FLOW control which negatively impact UL
and DL traffic which we can be called the Bart effect.

7. 3G throughput expectations
• TCP session throughput expectation across GEO satellite
<1Mbps/session.
• “Packet loss is a real issue for 3G Iub with reported 5% RAN
packet being considered lost/delayed over TDMA”… source
Ericsson.
• The disruptive effect of packet loss, congestion control, etc
can reduce effective real-life speeds to 160kbps or less.
7

8. 8
Comtech QOS benefits
• Comtech QOS builds upon years of deploying 2G/3G
networks over SCPC. 3GPP compliant QOS scheme
required to manage and prioritize traffic to ensure
highest available KPIs.
• Reduced jitter provides highest throughput by
reducing detected “packet loss” common across
TDMA.

9. 9
Packet per second considerations
• Requires highly capable processing engines to deal with high
packet per second rates found in 3G environment.
• Expect 2000 packets per 1 Mbps of 3G traffic!
• Comtech provides high pps capable remotes modems
(ranging from 35kpps to 350kpps) able to handle whatever
3G sent to it.

10. Overhead: Iub Voice
Comtech EF Data Confidential 10
• IP NodeB voice is supported via R99 techniques
which call for voice to be encapsulated in
IP/UDP/tunnels and so also carry significant
overhead.
– L2/L3 overhead greater than 50%
• Comtech header compression provides savings on the
order of 55% (AMR 12.2) to 75% (AMR 4.7).
Total bytes 4
# of Bytes 14 8 20 8 7 1 1 12-32 2 4
L1 HDR L2 HDR IP HDR UDP HDR FP HDR MAC HDR RLC HDR AMR CODEC FP CRC FCS
COMP HDR
# of Bytes 1-3
50 23-43
COMP PAYLOAD
variable

11. Overhead: Iub Data
Comtech EF Data Confidential 11
• Data (3G) consists of multiplexed traffic from multiple
users segmented into 40/80 bytes slices every
2msec.
• Iub data average overhead is in the range of 27%.
• Comtech Header and payload compression can
deliver 30% savings.
Total bytes 4
# of Bytes 14 8 20 8 7 1 1 12-1600 2 4
L1 HDR L2 HDR IP HDR UDP HDR FP HDR MAC HDR RLC HDR DATA (3G) FP CRC FCS
COMP HDR
# of Bytes 1-3
50 23-1600
COMP PAYLOAD
variable

12. Why can’t we optimize 3G
performance?
• PDU are segments/slices of traffic from End User
equipment which are multiplexed together at the RNC to fill
a 2msec burst time at the NodeB (and encrypted !)
12tr
FP
MUX
User traffic is segmented into 40 and 80 bytes
PDU at the RNC.
The RNC multiplexes up to 21 or 42 PDU into a
single FP mux equivalent to 2msec radio burst.

13. Do we need Jumbo frames?
• 3 types of HSDPA codes per cell are defined which also defines
the type and size of PDU and FP frames.
• HSDPA can support 5, 10, and 15 codes per cell across 3 cells.
• Comtech supports Jumbo frames capable of
supporting 3G HSDPA deployments.
13
Codes/
cell
PDU
(bytes)
PDU/FP FP MTU
(bytes)
PPS/
cell/
BW/ cell
(Mbps)
Iub BW/ cell (Mbps)
5 40 21 840* 500 3.4Mbps 4.3Mbps
10 80 21 1680** 500 6.8Mbps 8.5Mbps
15 80 42 3360** 500 13.6Mbps 17.1Mbps
5
5
5
10
10
10
15
15
15

14. 14
High availability and QOS
• Comtech couples QOS and two way AUPC/ACM
required to maintain highest site availability.
> 17 dB Fade
(VSAT BW
reduced
~80%)

15. 15
Conclusion on 3G
• Need to maintain highest level of KPI by minimizing delay and
jitter
• Support for different MNO backhaul preferences - L2
(VLAN/MPLS) and/or L3 IP processing
• Need to support high pps rate, provide effective 3GPP
compliant QOS and high availability mechanisms to ensure
RIGHT traffic is prioritized and delivered.
• Most efficient waveforms providing best spectral efficiency on
forward and return carriers.
Comtech EFData modes support the right feature sets to support and
maximize throughput of 3G service over VSAT. 3G considerations are
tougher than 4G requirements and so 3G prevail when 3G and 4G are
deployed together.

16. Introduction to LTE
(and what it means for end users throughput.)
16

17. Coverage per technology
17
Source: Ericsson Mobility Report

18. 18
Growth of mobile broadband
• With introduction of low cost handsets in 3G and 4G,
expected growth of Smartphone subscribers
expected to skyrocket in years to come.
• Cost of smartphones coming down rapidly
GSM 15 dollar, 3G 25 dollar, LTE 75 dollar

19. 19
Apps driving the agenda
• For mobile broadband users, app coverage is
increasingly important, driving minimum required data
speeds considerations for mobile operators.
• The minimum downlink speeds needed for a good
app experience are:
– > 1 Mbps for web browsing
– > 3 Mbps for Facebook
– > 5 Mbps for YouTube HD videos
– > 10 Mbps for Ultra HD (UHD) videos such as 4K
• Entertainment (video) and social media (Facebook,
Instagram, Snapchat) continue to be drivers to
bandwidth.

20. 20
Why LTE over Satellite?
• Do not confuse LTE with ultra high speed only! It is
more efficient at any data rate.
– most 3G NodeB need > 50 Kbit/s at all times
– LTE overhead is ~10%. 2G and 3G is 20% to 50% -> more
of payload translated in to usable data to end user
– LTE manages Radio resources from the eNb
allowing for quick reaction radio allocation when
traffic is ready to forward (vs 3G where radio was
managed by RNC across the VSAT)

21. 21
Why LTE over Satellite?
• Only mobile technology which enables protocol
optimization to provide improved QOE.
– Todays 2G/3G services are slow or not performing
well enough to fulfill the broadband experience.
– 2G/3G traffic cannot be optimized for satellite due to
2G Abis and 3G Iub data formatting.
– LTE simple encapsulation alows easy access to
mobile subscriber user traffic for multi-facetted
optimization.

22. 24
How much backhaul is enough?
• Reality check.. 90% of subscribers in
rural are medium to far distance from
tower.
• eNb selects from 28 MCS (Modulation
and Coding Scheme) to find best match
for transmission.
• Assumption for average BW:
– 10% close, 60% medium, 30% far -> 50/60Mbps

23. Optimizing LTE for
Quality of Experience
25

24. 26
LTE Network Topology
Key backhaul interface is S1
interface between the Serving
GW and the eNb.
Main advantage of LTE eNb vs 3G RNC/NodeB is the unification of the radio
resource and packet management into the eNb.

25. 27
Ue HTTP
Ue TCP
Ue IP
GTP
UDP
IP
L2
L1
HTTP
TCP
IP
Ue HTTP
Ue TCP
Ue IP
GTP
UDP
IP
L2
L1
S1
PDCP
RLC
MAC
L1
PDCP
RLC
MAC
L1
HTTP
TCP
IP
SGW/PGW (4G)) Internet
eNb (4G)
Ue)
TCP Session#1
LTE Traffic encapsulation
• LTE traffic between SGW/PGW and the eNb is
encapsulated across GPRS Tunneling Protocol.
• Opening up the GTP tunnel allows for vendors to
provide optimization solutions across actual Ue traffic

26. 28
Why optimize LTE protocol?
• High bandwidth = better Quality of Experience (QoE)
• TCP (underlying protocol on the Internet) performs
poorly over high delay links like VSAT
• Contributors to poor QOE:
– Web sites complexity has grown: 4 yrs ago average website
size was 750kB and consisted of 20-30 objects. Today, average
website in 2MB+ and consist of 200+ objects across dozens of
domain/hosts.
– Problem 1: DNS lookups must be performed to identify hosts
server addresses on the internet before object DL can commence.
Over terrestrial links DNS lookups account for roughly 1/3 the time
to DL the site.
– Problem 2: Typical browsers can open 6 simultaneous TCP
sessions per domain. If there are dozens of objects to DL from a
particular domain, those are managed sequentially.

27. 29
Contributors to poor QOE
– Problem 3: TCP “Slow Start mechanism” highly sensitive to network delay
(greater the delay, the longer it takes TCP session to ramp up). More than
80% of web downloads are small files (<100kbytes) which means TCP
seldom reach full speed and most transfers are in “Slow Start”.
– Problem 4: Autoplay media downloads and buffers traffic slowing down
other object downloads.
– Problem 5: Encryption. Encryption. Encryption.
– Problem 6: End-to-end (UE to Web server) TCP sessions transmission are
600 1200 1800 2400 3000 3600 4200 4800
0
10000
20000
30000
40000
50000
100kB transfer over VSAT
msec
Bytes

28. Understanding Internet Traffic
• Sandvine predicts that “by the end of 2017… Internet traffic that
is more 75 to 80% encrypted in most markets. “
• It is expected that Internet encryption levels will stabilize at
roughly 90% within the next 2 yrs.
30
Internet Traffic (2015)
Encrypted Not Encrypted
Internet Traffic (2016)
Encrypted Not Encrypted
Internet Traffic (2017)
Encrypted Not Encrypted

29. 31
LTE Optimization solutions
LTE optimization objectives:
– Provide mobile users a better internet/broadband experience
though faster reaction time and DL speeds.
– More efficient backhaul bandwidth utilization (backhaul link is fuller
.. Longer)
– More efficient remote site radio management since DL are faster
thereby allowing radio resources to be re-allocated more often.
– Local acknowledgements at the remote so re-transmissions are
managed locally (no end to end retransmissions across satellite).
– Optimization solution to scale to meet widest range of support LTE
capability deployments (integrated solution vs external appliance).
– Critical -> transparency to ensure accurate Bytes IN vs Bytes OUT
for billing purposes
Optimization: as fully perfect, functional, or effective as possible

30. 32
Improve Mobile User Experience
• Over traditional IP networks (such as ISP or enterprise
networks), TCP acceleration has been used to mitigate and
resolve those performance limitations to improve Internet user
experience.
– TCP acceleration provides breaking of long end-to-end 3WHS
control loops to several smaller control loops by intercepting and
relaying TCP connections within the network
@
No TCP Acceleration –long end-to-end 3WHS (SYN,
SYN-ACK, ACK) and “slow start” for TCP ramp up.
VSAT
With TCP Acceleration – local 3WHS and local ACKs
mitigates the “slow start” for TCP.
Local TCP session Local TCP session
Packet secure “relay”

31. 33
TCP Acceleration benefit
• Faster throughput ramp up
• Higher throughput
• Faster packet loss recovery .. important in the case of
supporting LTE over Ka band.

32. 34
TCP Acceleration Comparison
• Performance: TCP Acceleration
– Comtech/FX features TurboStreaming (CEFD patented IP TCP
optimization engine) allowing efficient multiplexing of website objects into
persistent TCP connection (speeds up time to first byte, reduces TCP 3
way handshake allowing faster transfers for smaller files on the web)
(https://www.comtechefdata.com/files/articles_papers/WP-QoE%20for%20LTE.pdf)
– Other vendors: standard SCPS implementation with no multiplexing (each
object has to go through end to end TCP 3WHS). SCPS is good for single
long file transfers but not designed for todays “busy” web where there are
many short file transfers..

33. 35
DNS Caching
• DNS Caching is often performed in ISP environment to
“speed up” host address resolution over VSAT.
– Example: Modern websites such as CNN require 70+ DNS
inquiries, DNS inquires take 1/3rd
of the time to DL a site and so
DNS caching significantly improves website QOE (see cnn-with-
dns-caching video)
– LTE optimization should provide DNS Caching to eliminate long
VSAT delays in Host name resolution WHILE preserving and
respecting BYTE counts for billing.
• Comtech/FX feature: DNS Caching provides local DNS
cache lookup to eliminate long VSAT delays in Host
name resolution.
• Other vendors: Not supported.

34. 36
Session Capacity Support
• Performance : Session and capacity support
– Capacity requirement:
 Observed need for greater than 4000 TCP sessions for as little as
single LTE site 20Mbps deployment.
 Observed need for 20000+ sessions in support of 150Mbps link.
– Comtech/FX : Comtech provides integrated support for GTP
optimization (up to 5000 TCP sessions), with standalone FX
appliances available to support higher demanding remote
capacity sites (up to 20000). Hub site support up to 100k
sessions.
– Other vendors: Typically, other vendors do not have the range
of options Comtech has.

35. 37
Deployment options
• Deployment option: not just IP transport
– LTE is typically deployed across L2 networks using either
VLAN, MPLS or multiples of those labels. In order to provide a
transparent service and facilitate deployment, LTE over VSAT
needs to be supported in same manner as terrestrial.
– Comtech/FX : Can support multiple L2 labels including MPLS
and VLANs while performing GTP optimization.
– Other vendors: Typically, limited to single VLAN and IP so
cannot be a completely transparent solution to the MNO.

36. 38
What about overhead?
• LTE is very efficient at the radio level BUT it comes with significant
overhead. Considering L2 transport, each GTP packet has 94bytes
of overhead.
• Internet packet distribution: 55% < 100, 15% < 1200, 35% >1200
bytes, LTE overhead would average 12%.
– Example:
 TCP ACK is 4bytes but requires 98byte across LTE (20x overhead to payload ratio)
 TCP average packet size of 700bytes + 94bytes overhead = 12% overhead!!
EPC/LTE overhead (94 bytes per user TCP payload)
MAC = 14 bytes, VLAN = 4 bytes, IP = 20 bytes, UDP = 8 bytes, GTP = 8 bytes,
Ue IP = 20 bytes, Ue TCP = 20 bytes

37. 39
Bandwidth savings
• Bandwidth saving: reduced overhead means more
BW for more user traffic.
– Comtech/FX : Reducing transport bytes is always a prioirty for
CEFD and so CEFD implements overhead optimization in two
stage across our integrated solution so overhead is reduced
from 94 bytes to 2 byte across satellite.
– Other vendors: No overhead bandwidth savings is implemented
to save LTE overhead.
EPC/LTE
MAC = 14 bytes
VLAN = 4 bytes
IP = 20 bytes
UDP = 8 bytes
GTP = 8 bytes
Ue IP = 20 bytes
Ue TCP = 20 bytes
Total = 94 bytes overhead
Comtech Total = 2 bytes overhead

38. 40
Effectiveness of LTE Protocol
Optimization
Technique Technology Benefit
BW saving
optimizations
Image resizing, object caching, byte
caching
Data traffic savings: ???:
too much encryption).
Voice traffic: 50% or more
TCP Acceleration: Optimizes the TCP protocol across
VSAT eliminating the speed barrier of
modern OS.
Good (standard SCPC is
good for large transfers but
not as effective for small
transfers).
DNS Caching provides local DNS cache lookup to
eliminate long VSAT delays in Host
name resolution.
HIGH (speeds up time to
first byte and total DL time)
Web evolution (http2
and/or CEFD
Turbostreaming)
efficient multiplexing of single domain
objects into persistent high bandwidth
TCP connection
HIGH (multiplexing allows
small and large object
multiplexing into same TCP
flows allowing higher BW
and efficiency)

39. 41
Comparison GTP Optimizers
Product
TCP session
support
Speed rating
(LAN+WAN)
DNS
Caching Payload Compression
HPRO 5000 150Mbps Y Y (embedded on modem)
FX1010C 20000 200Mbps Y Y (GZIP)
FX4010C 30000 600Mbps Y Y (GZIP)
FX5020 100000 1Gbps Y Y (GZIP)
Note : Don’t settle for less. TCP session support is most important and
more important than speed to supporting LTE/GTP optimization...
Ensure high level of TCP support.

40. 42
Comtech positioning (1/2)
• Comtech/FX provide complete optimization solution
ringing together:
– Superior Performance Enhancement Proxy (Turbostreaming
more advantageous than SCPS).
– Faster reaction time by :
 providing unique local DNS caching.
 Multiplexing object downloads from single hosts reducing
3WHS delays.
– Scalability with wide range of integrated and standalone
appliances to meet range of customer requirements.
– Deployable across L2 and/or L3 networks with either VLAN
and/or MPLS labels.
– Bandwidth savings: overhead reduction.

41. 43
Comtech positioning (2/2)
• High speed forward and return capabilities.
Uncompromised performance with enough pps to handle
the load.
• Two way true ACM for highest site availability.
• As higher BW tend toward Ka/Ku, dynamic two way BW
management and 3GPP compliant QOS is required to
maintain high availability and KPIs.

42. 44
LTE Conclusion
• Performance optimized LTE over VSAT – Available, proven,
deployed with major operators worldwide.
• Traditional deployment options:
– Rural Macro cells: combine LTE with existing 2G/3G to provide highest
consumer coverage options.
– Rural Macro cells and small cells: exciting deployment options using CA
concepts.
• New markets:
– Small cells: fill “blank” spots in network coverage.
– Metro-edge market: provide highspeed LTE overlay capacity to existing
terrestrial backhaul.
Comtech offers integrated LTE optimization providing highest LTE
performance over most efficient dynamic bandwidth platform on the
market today.

43. Comtech EF Data
2114 West 7th Street
Tempe, AZ 85281
USA
Tel +1.480.333.2200
FAX +1.480.333.2540
sales@comtechefdata.com
www.comtechefdata.com