Networks at the Speed of Light
pave the way for the tactile internet
Walter Haeffner
Vodafone Distinguished Engineer
Symposium “Das Taktile Internet” – 1 October 2013 – Vertretung des Freistaats Sachsen in Berlin
Networks at the Speed of Light
We have no Warp like Star Trek- We cannot go faster
In vacuum (or air) the speed of light is about
300.000 km/sec. In one millisecond light travels
about 300 km in vacuum.
In a fiber the speed of light is about 200.000
km/sec. In one millisecond light travels about
200 km in fibers. Research: hollow fibers
which allow for 97% speed of light!
Similar, in cooper signals (not electrons) travel
with about about 200.000 km/sec.
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Networks at the Speed of Light
Networks must transfer Data faster and faster
Fast browsing requires more than just bandwidth
Today, an average web browser session has to deal with multiple
TCP connections to different resources, without being able to load
everything in parallel. Typically, the response time should be less
than 50 milliseconds (ms) for each individual TCP/IP connection.
Video & voice calls are strongly affected by delay
For fluid calls, the mouth to ear delay should be less than 150 ms.
In video calls / conferences lip synchronization enters the scene. A
skew of less than 20 ms is considered imperceptible. Above 50 ms,
viewers will begin to notice the audio/video mismatch
Cloud-based applications are very delay sensitive
The time difference between a player performing an action and the
result of that action appearing on the screen should be less than
100 ms. In some fast action games, latency in excess of 70 or 80
ms may be unacceptable.
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Networks at the Speed of Light
Some Applications require Responses in the Milliseconds
Remote controlled robotic surgery
Earliest remote surgery conducted 7 Sept. 2001 between New York
and Strasbourg over dedicated fiber for guaranteed connectivity and
minimal lag. Working with force feedback handles and a mean lag
of 155 ms required a lot of training. Aim is latency well below 10 ms.
Collective robotic mind in the cloud
Provide cloud scale computation at extremely low latency to bring
the efficiency of robotic assistance to manufacturing, health care,
and research. Would need < 10ms latencies for sensorial actions
that require dynamic reactions. Typically 1ms results in a mm.
Real time memory for the disabled
Collect, store and process real time audio and visual impressions.
Deliver context relevant information real time to assist people with
brain injuries or Alzheimer. Give context dependent instructions in
real time to remind the disabled to perform necessary actions.
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Networks at the Speed of Light
Our current Internet is not close to support tactile Apps
Recent Customer Experience
RTT
500 ms
Source: Cisco Analysis of Ookla Speedtest Data, 2011
400 ms
Mobile (3G)
Fixed
300 ms
 Germany: ~ 10 msec – 60 msec
200 ms
 Transatlantic: ~ 150 - 200 msec
100 ms
0 ms
RTT
50 ms
MEA
LAT APAC CEE NAM
WE
Expected Customer Experience in LTE
Source: Epitiro Ltd.: LTE ‘Real World’ Performance Study (TeliaSonera)
40 ms
LTE Internet RTT - today:
2013 Germany
30 ms
 Germany ~ 35 msec – 40 msec
20 ms
 Transatlantic: ~ 150 - 200 msec
10 ms
0 ms
1 October 2013
DSL Internet RTT - today:
6pm
6am
6pm
6am
6pm
6am
6pm
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Networks at the Speed of Light
More Bandwidth Doesn’t Matter (Much)
HTTP Page Load Time
Packet Loss 0%, RTT 60 ms
PLT (ms)
PLT (ms)
HTTP Page Load Time strongly depends on Round Trip Time (RTT)
HTTP Page Load Time
Bandwidth constant at 5 Mbps
Bandwidth
Round Trip Time
Above 5 Mbps for web page downloads RTT more important than bandwidth
 Internet Today: RTT 50 ms – 250 ms independent on available bandwidth
 Music, videos, other large files utilize bandwidth much better than web pages
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Networks at the Speed of Light
RTT cannot always be improved by just more Bandwidth
parts of a web page
round trip time (ms)
video stream
diameter ~ bandwidth
Most important:
Design your networks for low latencies!
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Networks at the Speed of Light
Policies control Content Delivery, Caching, Pre-Fetching
RTT 20 ms – 40 ms
RTT 5 ms – 10 ms
RTT 10 ms – 200 ms
Mobile Core Cloud
Access
Cache
Backbone
World Wide Internet
Cache
Edge
Core
LTE: RTT UE – eNB ~ 10 ms
HSPA: RTT UE – NB ~ 20 ms
5th Gen: RTT UE - eNB ~ 1 ms
Delay within
network equipment is
order of µsec.
~ 100µs latency for a
16 Byte RPC between
modern Linux servers
Using caches and by that avoiding some thousand km Internet can
potentially improve page load times by some hundred milliseconds
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Networks at the Speed of Light
Tactile Internet Applications require new Architectures
Speed of light requires to move tactile application close to the user
 Invent new silicon architectures allowing massive parallel computing power
 Invent super fast memory with by now unseen high storage density
 All that with low power consumption, small heat dissipation
 Build a high performance computer center in a cabinet
RTT 3 ms – 5 ms
tactile
apps
 Move this as close as possible to the radio
micro
cloud
 How many CPU kernels do we need?
low
latency
apps
mini cloud
supporting
a radio cluster
Backbone
Network
micro
cloud
RTT 10 ms – 20 ms
1 October 2013
micro
cloud
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Networks at the Speed of Light
Mini and Micro Cloud Centers in a Box
Building blocks of a network in a box (mini/micro mobile network cloud)
Cloud Platform
for User Applications
tactile apps (traffic steering),
low latency apps (gaming)
Web caches etc. ….
Cloud Platform
for Network Functions
Network control functions
policy control, optimizers,
security etc. …
3GPP
Access Functions
3GPP interfaces to radio
equipment…
Typical cloud paradigm builds on inexpensive commodity computing hardware. But
low latency, beyond 4G networks for the next decade 2020 – 2030 will require new high
performance silicon for radio and powerful mini/micro clouds to ensure requested computing
power and package density in combination with new, more distributed system and network
architectures to fight the speed of light limit in todays networks architectures.
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Networks at the Speed of Light
And beyond – if Physics allows 
And for this kind of mobile networking...
we have to wait some more time …
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