1 © 2005 Nokia SDR ETSI Nokia.ppt / 08.02.2007 / HOS
Considerations for SDR Implementations in Commercial Radio Networks
Hans-Otto ScheckNokia NetworksP.O.Box 301 FIN-00045 Nokia [email protected]
ETSI Software Defined Radio (SDR) / Cognitive Radio (CR) WorkshopFriday 9th February 2007 - Sophia-Antipolis, France
2 © 2005 Nokia SDR ETSI Nokia.ppt / 08.02.2007 / HOS
End to end reconfigurability – E²R Vision
3 © 2005 Nokia SDR ETSI Nokia.ppt / 08.02.2007 / HOS
Why Software Defined Radio?
• UMTS – the “Universal Mobile Telecom Standard” isn’t the all universal solution• Even if there would be an universal standard it would not necessarily be the
single dominating standard
• To have a standard, open and flexible architecture for a wide range of communication products - life cycle cost reductions.
• Enhanced wireless roaming by extending the capabilities of current and emerging commercial air-interface standards.
• Over-the-air download of new features and services as well as S/W patches.
• Joint Tactical Radio – DoD initiative:Unified communication across commercial, civil, federal and military organizations.
4 © 2005 Nokia SDR ETSI Nokia.ppt / 08.02.2007 / HOS
The SDR BTS and its components
• The RF Block: “Software Defined RF”• From antenna to digital interface (OBSAI & CPRI)• Analog & digital signal processing• Frequency specific components
• The BaseBand Block: “Software Defined BB”• From digital interface (OBSAI, CPRI) to digital interface (transport)• Pure digital signal processing• Frequency independent
• The Transport Block: “End to end service”• Cellular specific networks (E1/T1 transmission, RNC, …)• IP networks
5 © 2005 Nokia SDR ETSI Nokia.ppt / 08.02.2007 / HOS
The SDR for commercial and consumer radio networks• Cellular industry: Growing number of incompatible radio technologies
Call for “technology agnostic” spectrum allocation• Consumer industry: Growing number of different applications. From low
rate RFID to high speed WLAN
• Fundamental difference between wide area and local area systems:
Wide Area• Spectral efficiency and cell planning• Coordinated spectrum usage
(minimize interference by design)• High performance RF
(TX power, RX sensitivity & blocking)Is SDR and cognitive radio feasible?
Local Area• No cell planning• Uncoordinated spectrum usage• Short term spectrum allocation• BTS (WLAN) listens before transmit• Low performance TRXSDR and cognitive radio essential
6 © 2005 Nokia SDR ETSI Nokia.ppt / 08.02.2007 / HOS
BTS Throughput vs. Interference
Node-BAvg. SINR ->
avg. cell throughput
Min. throughputat the cell edge
UL traffic on DPCH
• There is no “tolerable” interference level!• Low interference affects the BTS similar like increased noise• Every minute amount of interference reduces the capacity of a
system. The effect might be tolerable in the beginning, but increases gradually with usage of the interfering system
• Gradually decreasing capacity is difficult to detect • Will be compensated with TX power and/or additional sites• Increases gradually both CAPEX and OPEX• With fatal effects on the competitiveness of the network
Clean spectrum is an essential asset!
7 © 2005 Nokia SDR ETSI Nokia.ppt / 08.02.2007 / HOS
HW limits the capacity• Radio
• “Radiotelegraphy”: Transmission of news by radiation of electromagnetic waves. • C = W log2(1 + S/N) (Shannon) E = mc2 (Einstein)
• Software• Immaterial ware, non-apparative (m=0) functional parts of an installation.
• The downlink power (PA) is shared between the users • GSM: # of timeslots per carrier, # of carriers per TRX• WCDMA: Service (BW) used by each user, noise (interference, network load)
• Cell breathing is a SDR feature!
0%
20%
40%
60%
80%
100%
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7
Traffic load factor
Relative cell size
Increased load 800 kbps⇒ Decreased coverage
Low load 200 kbps⇒ Large coverage
128 kbps
64 kbps
8 kbps
128 kbps
64 kbps
8 kbps 144 kbps64 kbps
64 kbps
144 kbps
144 kbps
64 kbps64 kbps
144 kbps64 kbps
64 kbps
144 kbps
144 kbps
64 kbps64 kbps
• Traffic load has direct effect on the cell size
• Radio Resource Management provides means to control cell breathing in network optimisation
8 © 2005 Nokia SDR ETSI Nokia.ppt / 08.02.2007 / HOS
Spectrum Usage
1500 1600 1700 1800 1900 2000 2100 2200
WCDMAGSM1800Power(W)
GSM19001
Frequency(MHz)
WCDMADL
WCDMAUL
GSM1800UL
GSM1900UL
GSM 1900DL
GSM 1800DL
RX filter to protect theGSM1800 RX from it’s TX
RX filter to protect theGSM1900 RX from it’s TX
10-15
A wideband RF filter would leave the vulnerable RX LNAs unprotected from the high TX power!
GPS
WCDMA RX filter
GPS RX filter
11 -04© HOS
9 © 2005 Nokia SDR ETSI Nokia.ppt / 08.02.2007 / HOS
Why do we need RF Antenna Filters?
Commonly agreed radio rulesWithin GSM band
“Violent”, non-standardcompliant transmitters
100kHz GSM band 12GHz
Power(dBm)
Frequency
0
-10
-20
-30
-40
RX filter
GSM blocking spec.
Wanted channel
>25dB of additionalblocking robustness
12 -04© HOSIntermodulation
10 © 2005 Nokia SDR ETSI Nokia.ppt / 08.02.2007 / HOS
Noise in the TX
Modulator&
Digital filter
Modulator&
Digital filterD/AD/A Up-conversion
to RF
Up-conversionto RF PAPA Antenna
filter
Antennafilter
RFfilter
RFfilter
Noise floor: -165dBm/Hz -155dBm/Hz -115dBm/Hz -100dBm/HzPower: -10dBm 30dBm 43dBm
Noise(dBm/Hz) RF & antenna filter
Frequency
PA noise floor-100
-173
TX band RX band
RX noise floor
11 © 2005 Nokia SDR ETSI Nokia.ppt / 08.02.2007 / HOS
RF filters in wireless local area systems
-130dBm/Hz-145dBm/Hz
Noise(dBm/Hz)
-100PA noise floor
-173
TX band RX band
RX noise floor
RF & antenna filter
Wide Area Radio Local Area Radio
Reduced TX power
(20W to 20mW)
Reduced RX sensitivity
(<3dB to ~40dB)
12 © 2005 Nokia SDR ETSI Nokia.ppt / 08.02.2007 / HOS
Filter technology
Multimode ceramicresonator
Conductor loaded ceramic resonator
Resonator Q / Filter size@ 2GHz
100000
10000
1000
100
Coaxial duplex filterIL < 0.5dBAtt. >70dBPmax ~100W
1l
1ml
1µl
Pictures not in scale!
BAW filterIL = 3 dBAtt.= 25dBPmax ~2W
1.5l
Local area RF filterLocal area RF filter (<75µl)
Wide area RF filter (1.5l)
13 © 2005 Nokia SDR ETSI Nokia.ppt / 08.02.2007 / HOS
Cellular Standard Development
1992 2002 20101992 2002 2010
3G Radio
EDGE
Rel.4
Rel.6
HSDPA
Rel.7
Rel.5
03 -06© HOS
Rel.99
1G Radio 2G Radio
Analog CellularGSM P1
GPRSGSM P2
• Three radio generations • Over ten S/W releases within 30 years of cellular development
• Three radio generations • Over ten S/W releases within 30 years of cellular development
Frequency Hopping
VariableData Rates
Multi-Standard
WB channel equalization,
MIMOHSUPA
Variablemodulation
Com
plex
it y LTE
Voice VoiceData
14 © 2005 Nokia SDR ETSI Nokia.ppt / 08.02.2007 / HOS
Signal processing flexibility has its price
Flexibility
Power consumption(mW/MOPS)
Dedicatedlogic
Dedicatedlogic
µ Processorµ Processor
Memory
µ Processorµ Processor
Memory
µ Processor
Memory
Addr.MAC
µ Processor
Memory
Addr.MAC
0% (H/W) 100% (S/W)
0.01
0.1
1
10
ASIC
0.001
CPUFPGA
µProcessor
Memory
SatelliteProcessor
SatelliteProcessor
SatelliteProcessor
µProcessor
Memory
SatelliteProcessor
SatelliteProcessor
SatelliteProcessor
DSP
10 -06© HOS
Maximize flexibility
Minimize size & H/W cost
15 © 2005 Nokia SDR ETSI Nokia.ppt / 08.02.2007 / HOS
Conclusions
1. SDR is already implemented in existing cellular systems.2. Cellular networks provides us with a country / continent wide coverage and
uninterrupted services.3. Local area and peer to peer radio networks provide high speed in-building
coverage. 4. RF requirements for wide area and local area networks are not compatible
• Wide area: clean spectrum, network planning, high performance RF• Local area: ad-hoc spectrum usage, cognitive radio, low cost RF
5. End to end services require a seamless handover between different radio access networks