radio challenges and opportunities for large scale small cell deployments

Radio Challenges and Opportunities for

Large Scale Small Cell Deployments Keima Wireless

Small Cell SIG Event

Cambridge, Oct 2012

Cell Planning 1947 to 1984

• “Mobile radiotelephones” first encounter interference

effects in 1946.

• The cellular concept1,2 invented c. 1946.

• Cell planning is managing interference while we:

– increase site numbers; and

– shrink the reuse distance.

2 D.H. Ring, Bell Labs – Telephony – Wide Area Coverage, 11 December 1947

1 J.R. Brinkley – J.I.E.E. – 1946, 93, Part III, pp.159-166

“Cellular” Design in New York

Disruptive Events – Racal vs. British Telecom

• The start of the macro era:

• Cell Phones for the Masses…

• The new Vodafone network was launched on 1st January

1985. The smaller company’s innovative approach to

network planning allowed them to compete with the

UK’s biggest company.

• Vodafone became the largest mobile network …

• Predicted coverage, Guildford 1984

• Main input: terrain

Cell Planning since 1984

Quantity of

Spectrum

Cell Spectrum

Efficiency

Number of

How do we provide capacity to match Cooper’s demand progression?

“Cellular” Design in New York

Macros

Disruptive Event - iPhone

The growth of data demand has doubled

Every 1 year

A rate greater than Cooper’s predictions.

Macros networks no longer effective.

Reduction in the cell size => small cells

The “Super Cooper” Expansion Challenges 1

1984 & 2012: cell location is still the key factor

64 QAM

Small Cell

Size : 100m

Macro Cell

Size : 500m

Wi-Fi AP

Size : 40m

Quantisation Error

• Cell Radius, R.

• Quantisation1

ΔX < R/40

• So, if a cell is ~ 400 m, ΔX < 10 m.

1 Pete Bernardin and Kanagalu Manoj – IEEE Transactions on Vehicular Technology, Vol 49, No. 5, 2000

• We need to model the environment to 1 m accuracy.

Quantisation

Type R ΔX

Macro 500 m 12.5 m

Small Cell 100 m 2.5 m

Wi-Fi 40 m 1 m

Boston

Boston, raster clutter @ 25m

Boston, PV clutter @ 0.5 m

Boston

JFK Airport

Demand estimates should take account of non uniformity. Techniques that

cannot identify usage clustering at the scale of the cell radius will have

limited use.

Non Uniform Demand

64 QAM

Clusters of

demand

Clustering Accuracy

• New small cells should be placed to coincide with areas of highest demand (e.g. hotspots) to maximise capacity.

• Small cells have radii ~100 m which means their spectrally efficient 64-QAM zones are ~50 m or less.

• Demand estimates should take account of non uniformity and be capable of resolving clustering accuracy <50 m.

• Geotagged social data (Twitter, foursquare, …) use Wi-Fi assisted GPS for location accuracy (including indoors) ~ 20 m or less …

• (And using the Bernadine rule, we must use 1 m quantisation to resolve such small demand clustering.)

Images generated in Overture by Keima

Twitter London

1.5 km

Twitter London

0.8 km

Twitter London

High demand areas

Twitter London

Demand is complex:

Road users;

Pedestrians;

Residential;

Business;

Railroads;

Overall Demand (composite map)

Indoor Demand

Outdoor Demand

What is the deployment focus?

Macro / outdoors, continuous coverage;

Macro / high mobility demand, highways;

Small cells / outdoors, hotspots;

Small cells + Wi-Fi / offload, POIs;

Outdoor Demand with Small Cells (light blue) and Wi-Fi + Small Cells (dark blue)

Interference Continuum - Macro / Small Cell Power

Difference

Macros are 10 – 20 dB more powerful

Distant macros can have a significant effect on small cells

Interference

It is important to deal with such an interference continuum by

predicting the signal and interference across entire cities.

Interference continuum

Boston

Combinatorial Explosion – Complex interplay of dependent

objectives.

Cell planners will have to consider for each new cell during future

100,000+ rollouts:

Location, configuration and technology parameters;

Backhaul proximity and wireless clearance;

Rental costs;

Latency;

N2012 ~ 290,000

Macros

500 km

N2015 ~ 600,000

Macros + Small Cells (estimate)

500 km

Cells will only be deployed in areas where there is a positive

return on investment.

Return on investment should consider:

Sites that pay their way by locating near high demand “hotspots”;

Sites with manageable interference impact; AND

Backhaul or rental costs are affordable.

Only by considering ALL objectives can we maximise return on

investment: plan small cells holistically.

• Automation seeks to maximise RoI by considering:

– Optimal traditional towers;

– Optimal utility poles;

– Optimal wall mounting;

– Suggesting search ring;

– Backhaul costs; rental costs;

– Etc.

Example 1

• New York Case Study:

– Low powered small cells (1W);

– Street furniture: lighting fixtures, kiosks, power lines, etc.;

– Primary and secondary attachments;

– Wireless and fiber backhaul;

– High spectral efficiency.

Total candidate set: > 470,000

Small cells (1W) required: 1852 Primary location – green

Secondary location – orange

Manhattan

All candidate locations are street

furniture elements -> road alignment

0.5 km

Manhattan

0.5 km

Manhattan

Number of cells

follows demand

Holistic

Analyses

Manhattan

Wireless @ 60 GHz

0.5 km

Manhattan

Wireless @ 10 GHz

0.5 km

Manhattan

Fibre Routes

Manhattan

0.5 km

Manhattan

1 Mbps cell edge performance

Manhattan

Location is key to maximise spectral efficiency

Data accuracy more important than ever (1m resolution)

Interference continuum

Different environments and different cell types

Non uniform demand

Design focus is to maximise spectrum utilisation

Demand clusters served by 64 QAM zone

Automation

Deployable business case depends on holistic network design

The “Super Cooper” Expansion Conclusions

Example 2

• London Case Study:

– Low powered small cells (2 W) + Wi-Fi systems;

– Street furniture: lighting fixtures, kiosks, power lines, etc.;

– Wireless and fibre backhaul;

– High spectral efficiency.

Indoors Demand Outdoor Demand with selected Small Cells and Wi-Fi

Small cell service area Wi-Fi service area

NLOS Connections

London

10 GHz Fresnel Connections

London

60 GHz Fresnel Connections

London

Thank You

Contact Us

Iris Barcia iris.barcia@keima.co.uk

Simon Chapman simon.chapman@keima.co.uk

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