Fondazione Ugo Bordoni

QoS and new services:scenarios and perspectives

Guido Riva(griva@fub.it)

QoS: new challenges

• Mobile communications – as well as fixed telecoms – are facing strong modifications, from both a technological and service viewpoint.

• Technology: new standards are ready to enter the market (LTE), while mature (GSM) and recent (WCDMA/HSPA) ones are consolidating or expanding their penetration.

• Service: market structure is rapidly evolving and increasing its segmentation. Different needs and higher requirements.

• How are network offerings and customers expectations matching? Which are the major issues to consider?

QoS: the motivations• A pro-competitive environment must be based on the

effective choice of the consumer• Different options for the consumer are mainly characterized

by three distinct factors:– The price– The offered services– The guaranteed

(expected/promised/agreed)quality for each service

• These factors are interrelated:– Price - quality trade offs– Different services ⇒ differentiated prices ⇒ specific

grade of service or quality parameters– QoS and price are the two sides of the same coin:

• A fall in QoS is equivalent to a hidden price increase

ServicesServices

PricePriceQualityQuality

QoS: the quality cycle

• Focus on: the customer’s viewpoint and the provider’s viewpoint

Customer’s QoSrequirements

QoS offeredby provider

QoS experiencedby customer

QoS achievedby provider

Customer DomainOperator/ Provider

Domain

Alignmentgap

Executiongap

Perceptiongap

Valuegap

• Four viewpoints of QoS (ITU-T E.800)

• Different aspects of QoS:related or notto NP (Network Performance)

Users need access to comparable, reliable and independent information about price, quality and offered service

QoS: technical aspects

• We focus on technical aspects, i.e. more related to network performance

• We have to take into account also terminal performance, both as a device and as a network element

• Specificities of mobile systems:– High time variability of

communications– Geographical/spatial/

environmental influences– Multiplatforms service /

market segmentationSource: ETSI TS 102 250 Part 1

QoS: indicators

• We have different classes of indicators (and parameters)

Service retainabilityService retainability

Service integrityService integrity

Service accessService access

Network accessNetwork access

Network availabilityNetwork availability e.g. Coverage

e.g. Login

e.g. Blocking

e.g. MOS

e.g. Dropping

QoS: 4-layer model

• Data services are strongly increasing

• New services are activated

• Relevant QoS parameters are different for each service

• 2G, 3G, 4G: some services are specific, others are shared

QoS: measurements

• Pros & cons of the drive test or counters approachDrive tests Counters

Pros Cons Pros ConsExternal viewpoint: more objective

Representative viewpoint?

All events are considered

Internal viewpoint: objectivity?

Similar to the user perception

Representative of user perception?

All users with their different terminals

How to sense quality level during sessions?

Simultaneous networks comparison

Dependency on many factors: weights?

Isolation of selected spatial or time domain

Pinpointing limited to cell area average

Lack of coverage can be considered

How can be translated in a good estimate?

Accurate reporting of failure causes

Not aware of lack of coverage (holes)

Test paths can be tailored to the actual needs

High # of tests required for good statistical accuracy

Deep insights of network troubles

Sensible infos: accessibility? authenticability?

QoS: approach comparison• Tests are easily felt by the user as more close to or representative

of its experience

• Statistical accuracy requires a careful ‘experiment’ design

• Higher specificity at the expense of greater difficultiesSmall hands & big insights ?

• Counters are fully comprehensive, but more distant from easy user appreciation, less sympathetic

• They can provide a synthetic and universal picture

• The main drawbacks are in the manufacturer’s specific algorithms (lack of univocity) and in the ‘walled garden’ nature of the network data repository

Big hands & small insights ?

QoS: user behaviour• How QoS influences user behaviour and this

feedbacks the QoS measurement approach?• Example (ETSI TS 102 250-7 V1.1.1, Sec.6)

There is a radio network coverage problem for a series of tunnels in a newly built motorway area. Mobile users will frequently get their calls dropped when they pass this area on the motorway. Initially when the motorway opened the call drop rate measured in the network was high, since most of the calls are dropped. However, after some time the mobile users frequently passing this problem area will learn that the call will drop, and starts to avoid making calls when passing that point. The drop rate in the network will go down but the problem has actually not been solved.If the same area is also monitored by e.g. automatic end-point test equipment the drop rate will not go down, since the end-point test tool calling frequency is not reduced due to the coverage problem.

• Apart from the specific case, user behaviour can be driven by other factors, as well related to QoS. The two different measurements approaches can evidence different results, providing useful infos

QoS: multistandards networks

• Mobile networks are more and more evolving towards multistandards networks: from 2G to 3G to 4G …

• Besides different services associated to the different technological platforms…

• … we have to take into account the users/terminals fragmentation in each standard and the associated ‘long-tail’ dismissal process

• In addition, frequency bands associated to a given standard can expand, adding a diversification of the terminal floor based even on the allowed bands (dual-band, tri-band, four-band terminals …)

• Even in case of traditional services (e.g. voice), QoS experienced by users can be assorted

QoS: environmental impact

• Different operating bands result in different propagation conditions which add on to the environmental variability of the communication channel

QoS: open issues

• How to provide consumers with understandable, comparable and pertinent QoS parameters in presence of:– many different terminals / standards– many user profiles / service demand– many usage scenarios

• How to exploit the pros of both measurement approaches (field test and counters)– Coordinated approach to inspect specific situation?– Weighting factors trained by network infos?– Network parameters integrated by coverage holes

infos?• How to characterize new services as VoIP?

QoS & tarifs: open issues

• How to easily relate the QoS indicators to the different plans? Is an effective and informed choice endorsed?

• Mobile network fairness is intrinsicly a difficult task– How QoS vs plans relationship help overcome– Example: volume vs time charging in data comms

• In latest mobile networks, user profiling is quite a necessity (e.g. for CAC strategies, RRM)– How can the consumer be protected from unfair

degradations– Envisage a basic and guaranteed QoS level

(e.g.minimum value for specific parameters)?• SLA: only between operators and providers/MVNO?

Thank you

(griva@fub.it)