(qualcomm) ecall antenna…
TRANSCRIPT
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Ralf Weber
eCall RF Aspects
9th AECS Meeting, June 7-9, 2015,
St. Petersburg, Russia
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3 Standards & Industry Organizations (QSIO)
Outline
Introduction Cellular network concept Network coverage examples MSD performance in weak coverage Impact of in-car propagation loss Conclusions
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4 Standards & Industry Organizations (QSIO)
Introduction eCall – Save Lives in an Emergency
Goal – eCall should allow emergency organizations for faster response times by providing
automatic and manual calls in case of an incident
Typical use case – Car crash in rural or urban outdoor environments
eCall requires mobile network coverage for TS12 emergency services – Voice services have the most reliable performance in todays networks – Call prioritization of TS12 emergency services are guaranteed by networks operators
Caveat
– Network operators have to provide emergency services only in regions where they have network coverage
– Network coverage is a design criteria determined by commercial considerations and regulatory requirements
– Network availability highly depends on type and placement of antenna systems
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5 Standards & Industry Organizations (QSIO)
Cellular Network Concept
Source: GSMA
A network consists of base stations covering limited areas (cells) Coverage continuity is achieved by partially overlapping cells Devices determine best suited cells based on receive power measurements
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6 Standards & Industry Organizations (QSIO)
Coverage Example – Urban Area
Areas of weak or no 112 service
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7 Standards & Industry Organizations (QSIO)
Coverage Example – Rural Area
Example taken from https://www.vodafone.co.uk/explore/network/uk-coverage-map/index.htm
Regions of outdoor-only coverage can span several km
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8 Standards & Industry Organizations (QSIO)
-106 -105 -104 -103 -102 -101 -100 -99 -980
5
10
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25
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40
45
RSSI [dBm]
BLE
R [%
]
MSD successMSD failed
Expected IVS Performance Weak Coverage Environment
Weak Speech
Good Speech
Good RF Weak RF
Small number of MSD failures at low RSSI + high BLER
Measured MSD failures after
successful call setup
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9 Standards & Industry Organizations (QSIO)
Simplified Cell Border Scenario Network planning case for outdoor coverage
Cell A Cell B
RX Power Cell B RX Power Cell A HO/reselection
region
HO/reselection threshold
Min. required RX power
Cell A out-of-service Cell A service area
IVS served by
Cell A
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10 Standards & Industry Organizations (QSIO)
Simplified Cell Border Scenario Good Case: External antenna
Cell A Cell B
RX Power Cell B RX Power Cell A HO/reselection
region
HO/reselection threshold
Min. required RX power
Cell A out-of-service Cell A service area
IVS looks for better
cells
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11 Standards & Industry Organizations (QSIO)
Simplified Cell Border Scenario Good Case: External antenna
Cell A Cell B
RX Power Cell B RX Power Cell A HO/reselection
region
HO/reselection threshold
Min. required RX power
Cell A out-of-service Cell A service area
IVS reselects to Cell B
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12 Standards & Industry Organizations (QSIO)
Simplified Cell Border Scenario Good Case: External antenna
Cell A Cell B
RX Power Cell B RX Power Cell A HO/reselection
region
HO/reselection threshold
Min. required RX power
Cell A out-of-service Cell A service area
IVS served by
Cell B
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13 Standards & Industry Organizations (QSIO)
Simplified Cell Border Scenario Propagation loss due to in-car antenna placement
Cell A Cell B
RX Power Cell B RX Power Cell A HO/reselection
region
HO/reselection threshold
Min. required RX power IVS cannot make a
call
Coverage hole
Propagation loss Propagation loss
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Conclusions
Voice/TS12 emergency calls - Networks are configured to prioritize all emergency calls - Voice services are typically the best optimized by operators - Call setup and retention performance for eCall are the same as for normal voice/TS12 calls
Network coverage (managed by operators)
- Urban areas: Network optimized for indoor and outdoor scenarios - Rural areas: Network optimized for outdoor scenarios (may or may not include in-car
scenario) - Typical network planning parameters:
Indoor propagation loss: 20 dB In-car propagation loss: 10 dB External antenna gain: 3-6 dBd
eCall performance
- eCall and voice/TS12 calls experience performance degradations when coverage gets weak - eCall performance is reliable even at BLER values exceeding coverage target for voice/TS12 - Service continuity of emergency calls can only be achieved if device integration is following
the typical use case scenario assumed by operators, i.e. outdoor or in-car
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15 Standards & Industry Organizations (QSIO)
Conclusions (cont’d)
The issue of antenna placement in the car (e.g. IVS embedded antenna) - In-car propagation loss can reach ≥20dB in modern cars (e.g. due to shielded windows) - Reduced cell coverage can lead to call setup failures or call drops in cell border areas
GNSS performance - Similar considerations apply for GNSS antenna systems - Combination of 2G/3G and GNSS antennas possible - Position accuracy requirements that are currently defined for eCall on EU and UN level
may not be achieved by internal antennas
Recommendations for antenna system and placement
- Integrated external antenna system gain should achieve typical minimum 3dBd or more - Antenna system should be crash resistant or provide enough redundancy - Use of only internal antennas is highly discouraged - Car type-approval regulation should consider to include antenna requirements to avoid
implementation deficiencies leading to significant performance impacts
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16 Standards & Industry Organizations (QSIO)
Thank You ! Questions?
Contact: - Ralf Weber (rweber @ qualcomm.com)