Technology Vision 2020
Reducing network latency to
milliseconds
Nokia Networks
Contents
Executive summary
3
Latency – a key experience driver
4
Why does latency matter to users?
4
Why reduce latency?
5
Why 1 s overall latency experience translates into a 50
ms two way network response time
6
Networks have to be even faster
7
Real time services
8
Advanced network concepts build on low latency
9
Performance gain of intersite co-ordination depends on
latency
10
Throughput: The higher the achieved bandwidth, the
lower the latency
11
Radio and backhaul evolution to meet future latency
requirements
11
Proximity: Bring content and processing power closest to
the user
13
Shorten the real path through the network
14
Optimizing queuing to minimize router delay
14
LTE for device to device communication
14
Control: From reaction to automated prediction and
network level orchestration
15
Application-aware networks. Network-aware applications
16
Dynamic Experience Management (DEM) - supplement
reaction with prediction
17
Network level orchestration
17
Control the endpoints
18
SDN to dynamically control networks
18
Executive summary
Network latency refers to the time taken by a network to respond to an action initiated by an end-user through any application. The growing number of real-time apps will demand that end-to-end network latency be reduced to milliseconds, so there is no perceivable lag for end users while browsing or watching videos, playing games or even controlling a drone or robot from a
mobile device. Achieving millisecond latency is a major challenge as it reflects
orders of magnitude reduction from latency values measured in today’s mobile networks.
The latency of networks is an important measure of quality of service. As latency rises, users’ quality of experience of many applications declines and could lead to churn.
Lowering latency is an important way in which operators can differentiate by
improving the overall customer experience of existing and future applications with the chance to charge them at a premium, providing new monetization opportunities. Today’s video services, web browsing and gaming are all latency-sensitive. Advanced gaming applications in particular can require latencies below 10 milliseconds to achieve a good experience.
In fact, reducing latency is even more critical for operators to launch the next wave of applications such as augmented reality, virtual reality and dynamic machine type communications (e.g. car to car), as they will simply not work properly if network delays are too high. In addition, the booming use of the cloud by enterprises and consumers for all kinds of services means that ‘networks’ act as a bridge between users and services, and thus need to have instant response times.
Minimal network latency is also critical to exploit the benefits of advanced
network design concepts that require fast coordination and transmission
between different network entities, including the Centralized Radio Access
Network (RAN) and inter-site coordination.
Today’s mobile broadband networks typically contribute a substantial portion of the overall response time that many users experience. There is considerable scope for operators to reduce the sources of network-induced delay, primarily in three focus areas – throughput, control and proximity.
• Throughput: The latest innovations in radio and backhaul reduce latency
drastically by providing higher throughput, eliminating the bottlenecks that cause delays. Examples include Dual Connectivity with Carrier Aggregation, which connects a device to two LTE base stations at the same time,
maximizing the bandwidth available to a service, Coordinated Multi Point (CoMP) and smart scheduling.
• Control: As well as merely increasing capacity, it is vital to introduce
some control to manage the traffic more effectively. Technologies such as Quality-of-Service (QoS) differentiation, policy control across network
latency-sensitive traffic to take a different path through the network or
receive preferred treatment over plain data transfers, automatically and
efficiently.
• Proximity: Latency is about proximity, the physical distance and the number of involved network entities that data must traverse. Although caching of content can work for some applications, apps such as cloud gaming demand instant responses, which cannot be cached. The answer is to move the processing and storage for time-critical services closer to the edge of the network.
Technology Vision 2020
Nokia Technology Vision 2020 focuses on enabling mobile networks able to deliver Gigabytes of data per user per day, profitably and securely. Technology Vision 2020 comprises six technology pillars and paves the way for 5G:
• Supporting up to1,000 times more capacity to meet accelerating data demand
• Reducing latency to milliseconds to prepare for the applications of the future
• Teaching networks to be self-aware and simplify network management by extreme automation
• Personalizing network experience to enable the business models of the future
• Reinventing telco for the cloud to create on-demand networks that are agile and scalable
• Flattening total energy consumption despite accelerated traffic growth
Latency – a key experience driver
Latency has always been a key network performance measure. Yet its
significance for mobile broadband operators and their subscribers is
sometimes overshadowed as ever higher data rates are headlined.
Why does latency matter to users?
Response time is relevant every time humans interact with machines. Some
20 years ago, three response time limits were defined by Nielsen*.
0.1 second gives the feeling of instantaneous response - that is, the
outcome feels like it was caused by the user, not the computer. This level of responsiveness is essential to support the feeling of direct manipulation.
1 second keeps the user’s flow of thought seamless. Users can sense a delay,
and thus know the computer is generating the outcome, but they still feel in control of the overall experience and that they’re moving freely rather than waiting on the computer.
10 seconds keeps the user’s attention. From 1–10 seconds, users definitely
feel at the mercy of the computer and wish it was faster, but they accept it. After 10 seconds, users start thinking about other things, making it harder to
concentrate on the task once the computer finally does respond.
Currently, the way users interact with devices is evolving quickly. Interaction is moving from typing to speech, from click to touch and from movements to gestures. Interaction and communication are becoming much more natural, meaning end users are becoming less tolerant of latency.
Similar values are still used for user interface design, as the GNOME Human
Interface Guidelines 2.2.3** show.
*Nielsen Response time limits. http://www.useit.com/papers/responsetime.
html
** GNOME Human Interface Guidelines 2.2.3, version 3.12.2. https://developer. gnome.org/hig-book/3.12/index.html.en
Why reduce latency?
There are two key reasons why latency matters more than ever.
Firstly, the industry is motivated to minimize latency, as doing so opens up potentially lucrative business opportunities arising from futuristic applications that simply will not work properly if network delays are too high. Latency determines the perception of speed in about 80 percent of all mobile broadband uses.
A number of drivers are behind this trend. As the statistics about download and use of apps illustrate, consumers and enterprises are becoming
dependent on the cloud for all kinds of services. The strategic vision
formulated by Sun Microsystems back in 1997 that “the network becomes the computer” is already true. The cloud however relies on low latency network connections as most cloud services and applications are sensitive to latency. This is illustrated by the use of music streaming instead of simple downloads. The world’s computing and storage power is widely distributed around the globe in thousands of data centers, which in future will have performance and storage capacities we can’t imagine today. The cloud world depends on having low latency network connections.
Another driver is augmented reality. The benefit of these types of application
depends on the fact that the required information is available here and now,
as it is highly context specific.
Virtual reality is also developing. An example is the Oculus Rift which uses custom tracking technology to provide ultra-low latency 360° head tracking, allowing users to seamlessly look around a virtual world just as they would in real life. Every subtle movement of the head is tracked in real time, creating a natural and intuitive experience. With latency of more than a few milliseconds, users would feel disoriented and would not enjoy the virtual reality experience.
Dynamic machine type communications (MTC) are also increasingly common. These include applications such as car to car, auto pilot pre-crash warning
and collision detection/prevention. Other latency sensitive mission critical
MTC applications are telesurgery, railway surveillance and smart grid demand response.
In addition to the well-known voice and video services, an increasing number of real-time apps will test the performance of networks. These apps will also increasingly rely on fast access to cloud content. Applications containing video
will account for nearly 70 percent of mobile traffic by 2020. (Source: Cisco
Virtual Networking Index 2014).
Secondly, minimal network latency is critical to exploit the performance enhancements provided by advanced network concepts that require fast
coordination and transmission between different network entities, including
the Centralized Radio Access Network (RAN) and LTE Advanced features with inter-site or inter-cell coordination.
Why 1 s overall latency experience translates into a 50 ms
two way network response time
The loading time of web pages is a typical example of response time directly
affecting a subscriber’s seamless web experience.
Studies of consumer responses to shopping site performance (Source: Rheem, Carroll. Consumer Response to Travel site performance. s.l. :
PhoCusWright Inc., 2010) indicate that people in 1999 expected loading times of eight seconds. With 65 percent of today’s 18-24 year olds expecting a site to load in two seconds or less, we can predict that people will expect a one second loading time in the near future.
Of course, web page performance is strongly dependent on several aspects that are in the hands of web developers and web hosters. Advanced web
developers know the rules, such as using compressed files, avoiding lots of
small images, use of optimized images, avoiding bad requests and redirects. Moreover, there is a need to consider the dynamic and diverse development of web browsers and servers as we seek to improve customer experience. Speed is one of the most important competitive advantages in a very competitive browser market. There are some features, such as opening several parallel TCP connections and http pipelining, which attempt to deal particularly with high latency.
What does this mean for network latency?
Statistics (Source: httparchive.org) show that the average size of the top 1,000 web pages has reached more than 1 MB - and this data needs to be
typically requested from 100 resources and from more than 10 different
domains. This means the browser must connect with several TCP connections to several domains and has to load all these resources. This takes time, especially considering that due to their hierarchical structure, not all the elements can be loaded in parallel. This results in an unexpected requirement
for the network - the two-way response time should be less than 50 ms to achieve a 1 s overall latency.
Networks have to be even faster
Online gaming and remote office applications are demanding. If we look
at typical values, half of the latency of 80 ms required to experience
instantaneous responsiveness of multiplayer games and remote office
applications is consumed at the endpoints. This means that only 40 ms can be spent for the path through the network.
• Client: 1 ms control signal processing
• Server: 20 ms processing and video frame computation • 10 ms fast video encoding
• Client: 10 ms fast video decoding and processing - screen response can add some ms
The network budget for both ways is around 40 ms, comprising sending the control signals uplink and several packets with the video frame downlink.
Figure 1. Response time and network budget for enterprise cloud application and online gaming
1 ms
processing max. 20 mstransmission
10 ms
decoding max. 20 mstransmission
20 ms processing
10 ms encoding
Client Network Server
80 ms from action to response
The perceived latency of services comprises processing in the user
equipment, in systems at the server side and travel through the network. Thus the network performance has to be much better than the desired or required overall value. With more demanding services and related improvements in
clients and servers, efforts to reduce latency will focus even more on the
network.
Awareness of how latency affects the customer experience has motivated
over-the-top (OTT) providers to tailor their messaging protocols to minimize
latency over today’s networks. However, since the biggest factors affecting
latency are in the networks, operators are better placed to address the issue
and also potentially benefit commercially by reducing latency.
Real time services
The latency requirements of applications and services are mostly determined
by human perceptions regarding response time, fluid conversation,
smoothness of playback and quality of experience in general. In some cases,
latency requirements are defined by business or application areas such as financial trading, surveillance and smart grids.
As we have seen, users expect a full web page to be loaded in less than 1 s. As loading web pages typically involves multiple requests to multiple servers, this can translate to network latency requirements lower than 50 ms.
Real-time voice and video communication requires network latencies between 100 and 170 ms.
Advanced apps like cloud gaming and tactile touch/response applications
can push latency requirements down to single digit milliseconds. Remotely controlled vehicles or high frequency trading need single digit millisecond latency.
* Field measurements 2013 ** Cisco Global Cloud Index White Paper 2013
1ms 10 ms 100 ms 1,000 ms
Nokia 4G
mobile networks* global averagemobile networks**
Grid protection Smart Metering Web page loading Channel zapping Game (1stperson) Touch/response Voice calling Video calling Car pilot HF Trading >2 s 1 100……5500 mmss 1 1……1100 mmss 1 15500 mmss + +110000 mmss 1,000 ms 1,000 ms 5 500 mmss 1 10000 mmss + +7700 mmss 5 5……2200 mmss 1 1....55 mmss 1 100 mmss 4 400 mmss < <<< 11 mmss Audio/ Visual interaction Muscular reaction Tactile interaction Machine to machine interaction
Max. response time
Max. network budget
5 50000 mmss
For mobile networks its a challenge to meet the latency values for real-time services
Advanced network concepts build on low latency
A 3GPP feature roadmap has been developed to improve Radio Access
Network (RAN) performance, but also affects fronthaul and backhaul latency
requirements. New RAN concepts provide tight site and cell interworking and precise synchronization to improve the performance of available network resources. This becomes particularly essential in dense deployments, where interference is a major issue and power and spectrum need to be used most
efficiently.
One of these concepts is Centralized RAN (C-RAN), which links together multiple base stations and uses interference to achieve throughput gains,
especially in dense traffic areas with a large number of smart devices. It
doubles the average uplink capacity across a cell, while uploads at the cell edge can be up to ten times faster.
C-RAN builds on the real-time availability of information from several radio receivers at the central site in addition to the inter-site coordination.
The concept depends on low latency connections between remote radio sites and the central site. Functions co-located in traditional site architectures are separated and some are pooled in a central site, but still need to be as tightly coupled as before. To achieve the required latency values of less than
1 ms between the radio sites and central baseband functions, dedicated fiber
Performance gain of intersite co-ordination depends on
latency
CoMP and its newer development enhanced COMP (eCoMP), which can turn interference into a useful signal and boost capacity and performance at the
cell edge, can only benefit from inter-site alignments if the backhaul latency is very low. Depending on the conditions, the threshold for benefitting
from inter-site over intra-site eCoMP can be as low as a few milliseconds. Simulations and proof of concept tests show that with 1-2 ms latency, inter-cell scheduling can achieve around 10 percent inter-cell-edge gain over intra-inter-cell scheduling. Yet, with a backhaul latency of only 10 ms, gains were negligible. Today, latency values of 100 ms for the backhaul may still be adequate.
However, for forthcoming throughput and efficiency targets, the gain from
coordination of neighboring radio sites or cells will be essential. The actual gain depends strongly on the latency of the connection between these sites, particularly when the devices are moving.
This means that low backhaul latency is a key enabler to exploit the benefits of
advanced RAN features.
Figure 3. Advanced network concepts require ultra-low latency across sites Gain from coordination
limited by latency
enhanced Coordinated Multi Point (eCoMP)
Multi-cell coordinated scheduling
max. 1-5 ms latency to achieve effect over intra-site eCoMP
Centralized RAN
t
*Research simulation and PoC, 1-2 ms latency provides ca. 10% cell-edge gain
max. 10 ms latency for effect over intra-cell scheduling * Performance backhaul latency LTE eNB LTE eNB LTE eNB
Radio data in real-time
RF RF Level 3Level 2 Level 1 OAM BB Central site
t
max. 0,5 ms latency for fronthaul between radio sites and site with centralized functions **
**from measurements in live network and lab simulations
5 ms
After understanding the importance of latency reduction, the question is, how do we solve the latency challenge? The Nokia Networks approach is to focus
on more effective bandwidth, optimized proximity and network control, with
Throughput: The higher the achieved
bandwidth, the lower the latency
Put simply, in most cases, the bigger the pipe available to an application, the
lower the latency. Yet simply overprovisioning bandwidth is not efficient and
often not possible and it is not the nominal bandwidth or channel capacity of a network that is important, but the throughput or achieved, usable bandwidth for a particular application. The achieved bandwidth can be dramatically smaller than the nominal bandwidth for a number of reasons, leading to higher perceived latency.
Millions of users or connected things mean that most network resources are shared, potentially leading to congestion, packet loss and the challenge of optimal prioritizing or scheduling, taking into account Quality of Service (QoS) rules.
Queuing and processing in network nodes also affects the throughput for certain higher traffic load conditions.
Another consideration limiting the throughput is that protocols for reliable transmission with acknowledgements, such as TCP, have limits on the usable bandwidth. These stem from the need to avoid exceeding the network capacity and receiver capacity. Many methods of optimization are employed and network vendors are working on enhancing protocols. Self-aware and dynamically self-optimizing networks can use these methods to greatly improve the throughput.
Radio and backhaul evolution to meet future latency
requirements
Innovations in LTE radio access are already setting a benchmark in providing speedy networks, reducing RTT (Round trip time) values by more than 50
percent compared to HSPA. In ideal conditions, a figure of 10 ms can be
reached and measurements in commercial LTE networks show average RTTs as low as 20 ms. This is a great step ahead and available for a variety of conditions and requirements. Yet it will not solve all future latency demands beyond 2020. As part of research into 5G there are proposals to further improve the achievable bandwidth and reduce the latency to 1-5 milliseconds using new approaches.
A number of advanced concepts are set to improve throughput, as we already see today with the introduction of LTE-Advanced features such as Carrier Aggregation or Coordinated Multi Point (CoMP). But the evolution goes on. Dual Connectivity with inter-site Carrier Aggregation, which is a candidate for forthcoming 3GPP releases would connect a device to two base stations at the same time. With this, the scheduler can select from more available
radio resources, increasing the probability that appropriate capacity can be allocated. Research is underway on even more advanced hybrid multi-connectivity to substantially improve the throughput, particularly for mobility use cases where a user device is moving between radio cells.
Steady innovation in the protocol area, especially in the radio domain, will also increase the throughput. In addition, Nokia Smart Scheduler is being further developed in its role of smartly assigning spectrum in the LTE RAN for best-in-class downlink and uplink latency experience.
Self-aware networks automatically optimize their performance based on measurements, analysis, pattern comparison and corrective measures. These principles, proven for the RAN, can also be applied to transport networks for higher achieved bandwidth or throughput and thus reduced latency for a service.
A Nokia Networks study shows that fiber deployments aimed at providing
broadband access to households and enterprises in many countries will also become available to many radio sites. This provides a large amount of
bandwidth in addition to advanced, flexible microwave solutions and can
reduce latency where other technologies have reached their limits.
HSPA LTE 5G
Technology evolution for 1000x capacity will improve latency > Pushing efficiency,
spectrum usage, flexible small cells
> Self-aware networks for radio and transport
Fiber availability to 2/3rd
of the sites will improve latency in the future
Proximity: Bring content and processing
power closest to the user
There is one absolute constraint on latency - distance and the speed of light.
A user located in Europe accessing a server in the US will face a 50 ms
round-trip time, due simply to the physical distance involved, no matter how fast
and efficient the network is. The only way to improve this will be to reduce
the distance between devices and the content and applications they are accessing.
Today’s content distribution networks already provide storage functionality, or caching, at the peering points in the network and are suitable for static content. However, many future applications such as cloud gaming depend on dynamically generated content that cannot be cached. This means that both the processing and storage for time-critical services needs to be moved closer to the edge of the network.
An example solution of how to make use of proximity is Nokia Liquid Applications which implements the principle of ‘Mobile-edge Computing’ by placing applications and services in close proximity to where people and objects connect, enabled by the Radio Applications Cloud Server (RACS). The RACS enables localized processing, content storage and access to real-time radio and network information in the base station. By turning their base
stations into local hubs for service creation and delivery, operators can offer
a service experience that is local and personal and works hand-in-hand with existing charging, messaging and location-based services.
Another promising development is Software Defined Networking (SDN).
Applied to mobile network functions such as gateways, SDN can bring
applications and network resources closer to the end user. A Proof of Concept with a large Asian operator showed that, in advance of a planned large event, with many visitors expected from another region or country, the network can
be adapted to better cope with the traffic from these users.
Connections can be reconfigured via software to account for the increased traffic between home and event domains. The known top applications used
by visitors or the special applications for the event can also be provided from
a local data center to reduce cross-domain traffic. Network resources in the
event domain, where the probability of overload is high, can be increased
by configuring free resources or using the resources of less critical network
Shorten the real path through the network
In addition to geographical proximity, it is important to consider and minimize the real end-to-end network path, which can be much longer than the
geographical distance might indicate. The reduction in the number of involved
entities along the path through the network is an effective way to reduce
latency considerably.
For example, even when a client device and a web server being accessed are both in the same city, if a distant peering point is involved, data must travel a long distance and thus create unexpectedly high RTT values.
Reducing the number of hops should also be considered as a first measure
to simply reduce the number of network elements in the path processing the signal. This can also be achieved through architecture evolution that leads to fewer network elements for a domain, as the evolution of RAN from HSPA to LTE showed, or when protocol evolution means that higher layers of the protocol are processed in fewer elements.
Optimizing queuing to minimize router delay
In a packet network, many hops will consist of routers, each adding a contribution to the end-to-end latency. When the router and the packet
network are properly planned and configured, modern routers will contribute
only a few milliseconds to the latency. However, in the case of congestion or
buffer oversizing, this value can go up to 100 ms per router due to queuing
issues.
This means that reducing the number of hops can reduce latency significantly,
especially under non-optimal conditions.
LTE for device to device communication
Vehicles are increasingly becoming a new platform for technology adoption, very similar to phones or tablets. An example is Google, which has added a
traffic layer to Google Maps, sourced from other Android users, to inform users about traffic jams and other road issues.
A number of companies have announced the formation of alliances to speed up innovation in the car industry. Some of these innovations will require not only a reliable, but also a low latency connection to the network, particularly
when it comes to reacting quickly to road or traffic condition information. Why milliseconds matter has been explained comprehensively by Nokia*.
LTE solutions can also provide valuable advantages for future local device-to-device, device to infrastructure or machine type communication, also comprising novel approaches such as Mobile Edge Computing (MEC) or LTE Direct (LTE-D). By adding intelligence to mobile network radio sites, minimal latency and coverage can be achieved at low cost. This was shown by Connected Driving, a Vehicle-to-Infrastructure showcase based on MEC.
The key advantage of mobile broadband networks with LTE is that it provides all the options of proximity depending on the needs - services or content from the cloud would be delivered as usual via the mobile broadband network. For time-sensitive services, latency can be as low as 10 ms with proximity, while still being able to exchange information over a distance of several 100 meters or kilometers. For instant reaction, direct communication between devices can also be supported by LTE.
* Milliseconds matter for accidents, HERE and Nokia Networks explain
(http://360.here.com/2014/09/10/milliseconds-matter-accidents-here-nokia-networks), LTE edge computing advances Connected Car road hazard
alerts
(https://blogs.nsn.com/mobile-networks/2014/09/10/lte-edge-computing-advances-connected-car-road-hazard-alerts)
Optimized queuing ISP A
ISP B
Network path Number of hops
20ms 10ms 10ms 10ms 10ms 20ms 10ms
Reduce physical distance
Reduce logical distance
Cable length 0 ms 0 km distance10,000 km 20 ms 10 ms 30 ms 40 ms 50 ms delay
Tap the full potential with network planning, optimization, implementation
µs µs x0 ms Processing Serialization, propagation Queuing IP IP IP IP IP
Figure 5. Proximity bringing content and processing power close to the user
Control: From reaction to automated
prediction and network level orchestration
Equally as important as effective bandwidth is controlling the real, dynamic conditions, such as traffic load, along the end-to-end path in the network. As an example, a high traffic load leads to queuing of packets, which delays their
Overprovisioning bandwidth in all network domains is simply not efficient.
Good network design in combination with smart adaptation of the network are needed to optimize latency under real, dynamic conditions such as changing
traffic loads, along the end-to-end path in the network.
Network-level orchestration
• Distributed experience agents • Collaborative sensing and analysis • Common control across resources
Dynamic QoE management Insight-based, preventive actions across radio and transport
Application aware networks QoS across radio and core
Network aware applications Mobile Throughput Guidance Signaling 4 times higher QoE
than with
todays QoS management
Network
conditions such as
radio coverage,
tra
ffi
c load, QoS settings,
strongly impact latency.
And can change quickly.
Cont ro l n et w or k co nd iti ons
Figure 6. From reaction to automated prediction and network-level orchestration
Application-aware networks. Network-aware applications
Network performance is often separately optimized in the access, the transport and the core domains. However, using core network capabilities
alone to inspect data traffic at the application level for applying the
appropriate policy rules and enforcement would not help to deliver the application with the same QoS to the user. Including the RAN gives operators the means to introduce application prioritization through transport
differentiation across core and radio access networks. This enables operators to create application-specific packages with personalization and targeted pricing to reflect measurable quality.
An example is Nokia’s 3G application aware RAN innovation, which combines core intelligence on applications with RAN information of cell load and radio link conditions at the bearer level.
On the other hand, information about network capabilities provided to the application or content servers or to management systems can be leveraged to adapt the delivery of services. This leads to optimized utilization of available network resources and thus best latency experience (beside others).
An example is Google’s, Nokia’s and Vodafone’s joint IETF draft submission* on
a Mobile Throughput Guidance Inband Signaling Protocol to make best use of mobile network capacity.
Dynamic Experience Management (DEM) - supplement
reaction with prediction
It has long been proven that QoS differentiation enhances service experience, such as video streaming, as our White Paper “Netflix over a QoS enabled LTE
network”, February 2013, shows. As research results indicate, an analytics server will be able to measure and analyze the Quality of Experience (QoE) from big data and to make decisions in real-time. Nokia research has achieved 23 ms from request to action in a recent proof of concept project.
Tactile applications, safety solutions (car to car) or mobility solutions will increase latency requirements beyond the technically feasible reaction time. The only way forward is to supplement fast reaction with insight-based, preventive QoS-ensuring action. At the same time, the availability of insights from devices and network elements and the increasing ability to evaluate such big data in real-time, means applications will be ever more aware of optimized devices, networks and conditions.
Advanced analytics will make it possible to predict user or device movement and the location of coverage holes, overloaded areas or other critical
conditions. This knowledge will be applied to dynamic LTE traffic steering and Wi-Fi offloading as well as other dynamic control methods, such as automated backhaul transport configuration using SDN, to adapt the network in advance.
The key for best latency experience as part of the QoE is a fast loop control with predictive elements for each session or service. Measurement, analytics, decisions and related actions have to happen all in real-time to ensure that the network is optimized according to current and expected conditions and
defined targets.
Nokia Dynamic Experience Management (DEM) focuses on the user’s experience, including measured and perceived latency, and addresses all elements of the optimization process. The principles and architecture are thoroughly tested and proven.
Network level orchestration
Technologies such as QoS differentiation and policy control are already available for commercial deployment, allowing traffic streams to be treated according to their specific needs. Latency-sensitive traffic will then take a different path through the network or receive preferred treatment over other traffic. Dynamic automatic adaptation, taking account of numerous insights,
will be the future.
The enabler of such systems is continuous monitoring and managing of latency as a key network quality parameter, to identify and improve bottlenecks in the network. In Nokia research projects customer experience agents for SON (software entities on network elements) collect user plane, control plane and end-to-end insights, including latency. They perform distributed collaborative QoS measurements and application-level QoE
and deciding the measures needed to meet the desired network performance, including latency values.
Control the endpoints
The state transitions of devices play an important role in latency and the network can also have a big impact. As an example, LTE latency depends on the device state: idle to call setup is approximately 100 ms, while from a
connected state the RTT is around 10-20 ms. The trade-off between power efficiency and latency reduction needs to be considered carefully.
SDN to dynamically control networks
SDN in the telco cloud data center offers speed and automation, allowing
service chaining and data center automation. Beyond this, SDN in the mobile
backhaul, aggregation and backbone allows traffic optimization, bandwidth
allocation and the enabling of RACS services to reduce latency.
To support SDN control, SON agents can collect information from the network such as delay, loss, throughput, queue length, number of active bearers and
devices. This will be used to reconfigure the network elements, reducing latency dynamically, automatically and efficiently.
Nokia offers all-IP transport solutions, including fully integrated options, for
high scalability, high capacity, low delay and best synchronization to meet the connectivity, backhaul and fronthaul requirements of a modern mobile broadband network.
However, new technology not only needs to be available, it needs to be leveraged professionally. This is why professional network planning and optimization is so essential for a valuable low latency network base.
Conclusion
Low latency is essential to offer a quality experience for many services such
as video streaming and online gaming. It will become even more important for new applications such as augmented reality, virtual reality and dynamic machine type communication. It is also necessary to realize advanced concepts that boost network performance, which are based on inter-site or inter-cell coordination.
Reducing latency requires increasing the throughput, absolute control of network resources and putting processing assets nearer the users. Low
latency is a chance for operators to differentiate, while it also introduces new
revenue opportunities.
As the awareness of the value of low latency traffic increases, the service
quality can be charged at a premium, providing network operators with new monetization options. An example of this was the early 2014 agreement
between Netflix and Comcast and Verizon to get faster streaming video connection for Netflix users.
Most of the technologies to drive down network latency to the required level exist today. For latency values of single-digit milliseconds and even less, network architecture evolution, new concepts and technologies will be needed, as the ongoing discussions on 5G technologies are revealing.
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