The Radio Environment MapSami Lunnamo

Presentation outline

REM

Definitions

Requirements

Challenges

Design

Location and

mobility

Database

WS availability

Layered REM

REM - Definitions• Geolocation service• And more

• Centralized database• Radio environment data

• Predictions of spectrum opportunities• Cognition cycle

REM – Definitions - Analogy

REM

- Location (x, y, z)- Geographical

location- Radio spectrum

profile

Tourist map of Beijing, source: http://images.chinatravel.com/city/beijing/beijing-city-map-large.jpg

REM – Requirements• Normal CR requirements• Safety• Efficiency

• Centralized service• Availability• Reliability• Throughput• Latency• Security

REM – Challenges – Signal overhead• Communication between REM and CR• Amount of relevant data• Quality of connection

• Balance between overhead and benefits of REM

REM

Clipart from bestclipartblog.com

REM – Challenges - Validity• REM is collection of data• How long will any data be valid?

• Information exchange between layers of REM

REM – Challenges – Spectrum opportunities• Ability to detect and predict spectrum opportunity

• Model-driven scheme to calculate opportunities• Loss-ratio can be close to 0%

Hey, I have data I’d like to

send

REM

Nope, no free bands here Bands

REM – Challenges - Locations• Determining a location is error-prone and expensive

• Could CRs use base station location as substitute for knowing own location accurately?

• Mobile CRs

• One-off events and wireless microphones

REM – Challenges - Bootstrapping• New client

• Connecting with REM through base station

• Chicken-and-egg

REM – Design – Spectrum opportunities• Model-driven schemes vs. Data-driven schemes

• Longley-Rice (L-R) with terrain data• Climactic effects, soil conductivity, permettivity, Earth’s curvature

and surface refractivity• 8% spectrum opportunity loss and even less false positives

• In practice, no one model is sufficient alone

REM – Design - Location• Different channels open in different areas• If using base station location, REM would have to use channels

that are open and available in every part of the coverage area• 80% spectrum opportunity loss• Location granularity• 4km = 80% loss• 800m = ~0% additional loss

• Bootstrapping beacon• Data of available channels

REM – Design - Mobility• Mobile CRs location is constantly changing

• CR might travel to an area where it uses a channel in use by PU • Old data about spectrum availability

• Protection range for channels

• Polling frequency for spectrum updates• 96 km/h, 60sec, 1.6km = 20% loss• 96 km/h, 30sec, 800m = 0% loss

REM – Design – Database• What kind of data should the database contain?

• TV transmitter data• Tower locations, antenna heights, transmit powers…

• Client data• Locations, IDs, channels, transmit powers…

• Cache

REM – Design – Layered REM• Distributing and decentralizing

• Layers• REM SA and REM Managers

• Subsidiarity• Data stored and analysed in least centralized node possible• National – regional – local

• Proportionality• Data with shorter life span needs to be readily available• REM SA and manager within quick reach

REM - Summary• Geolocation service• Analysis and historical data of spectrum opportunities• Can detect and use ~92% of all spectrum opportunities in area• No false positives

• Accommodates mobile CRs• Mobility doesn’t cause breach of safety requirement

• Layered architecture gives robustness and eliminates overhead

• Uses broadcast beacons to bootstrap new clients