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Energy Efficient E‐band transceiver for backhaul of the future networks
Project reference: FP7‐ICT‐317957Project Coordinator: CEIT (Spain)Contact Name: Dr. IgoneVélez ([email protected])Start date: 01/12/2012End date: 31/05/2016
mmWWorkshop, Valencia, 2015/11/20 2
Mobile Backhaul requirements
Microwave/ mmW backhaul
Index
E-band transceiver requirements
Results
mmWWorkshop, Valencia, 2015/11/20 3
• Mobile backhaul •connection between cell sites
• core network (controller site)
RANRAN
RAN
Backhaul
Mobile backhaul
mmWWorkshop, Valencia, 2015/11/20 4
Future Networks: C‐RAN
RRH
BBU
CPRI
Antenna
RRH
BBU
CPRI
Antenna
Cell site cabinet
RRH
CPRI
RRH RRH
Fronthaul
Backhaul
Backhaul
CentralizedBBU
Communication between RRH and BBU require a capacity in the order of Gbps
mmWWorkshop, Valencia, 2015/11/20 5
Backhaul network challenges
• Network scale/densification• The introduction of Small cells
•vast expansion of the backhaul network and the number of sites that must be connected and managed.
• Short link length backhaul will be predominant.
• Network capacity• The transition to 5G, and the addition of small cells are all strategies to address growing capacity demand. • The backhaul network must also scale in capacity or risk becoming a bottleneck.
• Network Architecture• C-RAN poses big challenges to the backhaul mainly for Capacity and latency requirements.
Capacity up to 10 Gbps must be backhauled
mmWWorkshop, Valencia, 2015/11/20 6
Mobile Backhaul
• Possible technologies:– Fiber
• It has the capacity and latency requirements of CPRI.• High CAPEX
– Fiber deployment seems to be prohibitively expensive in thecoming years.
– Copper• It does not have enough capacity and presents an excessivelatency to address the requirements of CPRI interconnect.
– Microwave• Best when looking at both the OPEX and CAPEX.
mmWWorkshop, Valencia, 2015/11/20 7
Mobile Backhaul requirements
Microwave / mmW backhaul
Index
E-band transceiver requirements
Results
mmWWorkshop, Valencia, 2015/11/20 8
Traditional Microwave
60 GHz – Unlicensed
Millimetre – E-Band
Frequency Band and spectrum resources for Point‐to‐point link
mmWWorkshop, Valencia, 2015/11/20 9
Available Channel size
The most popular channel sizes are 28MHz and 56MHz
In some Frequency bands channel aggregation is permitted:i.e.: 59‐64GHz up to 2.5GHz
E‐Band: 71‐76 &81‐86GHz ‐ up to 4.75GHz bandwidth‐ Channels of size multiple of 250 MHz
Potential to transmita capacity up to 10 Gbps
mmWWorkshop, Valencia, 2015/11/20 10
Mobile Backhaul requirements
Microwave backhaul
Index
E-band transceiver requirements
Results
mmWWorkshop, Valencia, 2015/11/20 11
• E‐ Band transceiver:– Highly integrated SiGe circuit
E3Network Requirements
81 – 86 GHz
71 – 76 GHz
FDD
Frequency Bands GHz71‐76 Go
81‐86 returnRF interface FDD
Capacity Gbps 10
Network Interface Ethernet 10 Gbps
Latency us 30
Availability at 1km % 99.995
mmWWorkshop, Valencia, 2015/11/20 12
ETSI EN 302 217‐2‐2 Annex Ea: Frequency bands 71 GHz ‐ 86 GHz
Beyond commercial backhaul links
E3Network
E3Network transceiver will increase: • Spectral efficiency
mmWWorkshop, Valencia, 2015/11/20 13
• State‐of‐the‐art E‐band transceivers: GaAs– Cost of mm2 of GaAs is twice that of SiGe– GaAs chips are mechanically fragile
• Difficult machine handling • Increases test costs
– GaAs have much higher defect density• Transceiver in a single chip impossible
– Complicates assembly process– Degrades the reliability of the link
• E3Network: SiGe based single chip FE– Simplify assembly process and improve reliability– Self‐healing techniques to reduce power consumption.
Beyond commercial backhaul links
mmWWorkshop, Valencia, 2015/11/20 14
State‐of‐art: Analogue multi‐line approach
PA
LNAMixers
Mixers
PLL
Dup
lexe
r
Net
wor
kIn
terf
ace
Net
wor
kIn
terf
ace
N ChannelsModulator
Digital dataInput
mmW-Transceiver
IF Module Digital modem• Drawbacks:– Increased area – Power consumption will be penalised.
mmWWorkshop, Valencia, 2015/11/20 15
Selected architecture: Analogue single‐line approach
PA
LNAMixers
Mixers
PLL
Dup
lexe
r
Net
wor
kIn
terf
ace
Net
wor
kIn
terf
ace
mmW-Transceiver
IF Module Digital modemD
emod
ulat
or+
Dec
oder
Enco
der +
Mod
ulat
or
LPFVGA ADC
PLL
mmWWorkshop, Valencia, 2015/11/20 16
Technical specifications
Transmitted signal
characteristics
Number of analogue lines 1Number of digital sub‐bands per analogue line 2Channel separation (MHz) 2000Roll‐off 15%Modulation order 6Code rate 0.875
-3 -2 -1 0 1 2 3-120
-110
-100
-90
-80
-70
-60
-50
-40
GHz
dBW
/MH
z
dbb1 dbb2
mmWWorkshop, Valencia, 2015/11/20 17
Mobile Backhaul requirements
Microwave backhaul
Index
E-band transceiver requirements
Results
mmWWorkshop, Valencia, 2015/11/20 18
Final front‐end of TX (implemented in SiGe 55nm)
PA
Signal generation(IF + mmW)
IQ modulator
mmW mixer
mmWWorkshop, Valencia, 2015/11/20 19
I/Q modulator(implemented in SiGe 55nm)
DescriptionThe IQMOD_CEIT_v1 is a CMOS I&Q modulator up-converter. This deviceprovides a small signal conversion loss of 5dB with -18dBc of sidebandrejection. The circuit up-converts a baseband signal (DC to 3,5 GHz) to afrequency of 15 – 21 GHz, with an output 1-dB compression point of -1 dBm.The required LO power is +16dBm.
Main Specifications
Output Frequency 15 – 21 GHz
BB Input Frequency 0 – 3,5 GHz
LO Frequency 15 – 20 GHz
LO Power +16dBm
OCP1dB > ‐3 dBm (Typical ‐1dBm)
Avg. Conversion Gain ‐5 dB
Input Reflection Coeff. < ‐10 dB
Output Reflection Coeff. < ‐10 dB
DC Power Consumption 61 mW
Chip size 0.98mm x 1.09mm
1.09
mm
0.984mm
mmWWorkshop, Valencia, 2015/11/20 20
mmW TX(implemented in SiGe 55nm)
DescriptionThe EBTX-CEIT-v1 is an E-Band transmitter chip that converts a 16-21 GHzsignal to the 71-76 GHz and 81-86 GHz bands using a 55-65 GHz LO signal.The average conversión gain is 23dB and the maximum output 1-dBcompression point is 14.4 dBm and it is better than 11.2 dBm across both bands.The required LO power is 0dBm for both bands.
Main Specifications
Output Frequency 71 – 86 GHz
IF Input Frequency 14 – 24 GHz
LO Frequency 55 – 65 GHz
Required LO power 0 dBm
OCP1dB > 12.9dBm @ 71‐76 GHz band (max. 14.4 dBm @ 71 GHz)> 11.2 dBm @ 81‐85 GHz band (max. 13.13 dBm @ 81 GHz)
Avg. Conversion Gain 23 dB
Input Reflection Coeff. < ‐7 dB @ 14‐25 GHz
Output Reflection Coeff. ‐12 dB @ 72 GHz, <‐4dB @ 71‐86 GHz
DC Power Consumption 580 mW
Chip size 2.06mm x 0.79mm
0.79
mm
2.06mm
mmWWorkshop, Valencia, 2015/11/20 21
mmW TX ‐improved version(implemented in SiGe 55nm)
DescriptionThe EBTX-CEIT-v2 is an E-Band transmitter chip that converts a 16-21 GHzsignal to the 71-76 GHz and 81-86 GHz bands using a 55-65 GHz LO signal.It is an improved version of the EBTX-CEIT-v1 transmitter. The averageconversión gain is 23dB and the output 1-dB compression point is higherthan +18 dBm across both bands. The required LO power is 0dBm for bothbands
Main Specifications (simulation values)
Output Frequency 71‐86 GHz
IF Input Frequency 16‐21 GHz
LO Frequency 55‐65 GHz
Required LO power 0 dBm
OCP1dB > 18 dBm
Avg. Conversion Gain 23 dB
Input Reflection Coeff. < ‐10 dB
Output Reflection Coeff. < ‐10 dB
DC Power Consumption 560 mW
Chip size 2.06mm x 0.79mm0.
79m
m
2.06mm
mmWWorkshop, Valencia, 2015/11/20 22
WP2: Fully‐integrated RX board(implemented in SiGe 55nm)
Signal generation(IF + mmW)
mmW Receiver+ I/Q Demodulator
mmWWorkshop, Valencia, 2015/11/20 23
• High bandwidth (2 GHz)– Challenging DBB implementation in FPGA– High sampling frequency in ADC/DAC– Hard requirements for the base‐band analogue filters
Selected architecture: Challenges
33dBc @ 1.8GHz10dBc from DAC
response
mmWWorkshop, Valencia, 2015/11/20 25
Measurements Results of Tx IF Board & mmW& PA
Pout=-7.5dBmPPA ̴ -1.5dBm
P-1dB-Mixer ̴ 0dBm
mmWWorkshop, Valencia, 2015/11/20 26
Measurements Results of Tx IF Board & mmW& PA
Pout=-6dBmPPA ̴ 0dBm
P-1dB-Mixer ̴ 0dBm
mmWWorkshop, Valencia, 2015/11/20 27
• High order modulation (64QAM)– Very sensitive to transmission impairments
•Phase noise• I/Q imbalance
– Challenging requirements for SiGe based analogue components•Compensation techniques must be applied in a mixed‐signal approach – self‐healing algorithms required
Selected architecture: Challenges
mmWWorkshop, Valencia, 2015/11/20 28
• TX I/Q imbalance compensation
Self‐healing : TX I/Q imbalance compensation
Effect of I/Q imbalancewithout self-healing (IRR=28 dB)
Correction of I/Q imbalancewith self-healing (IRR>35 dB)
mmWWorkshop, Valencia, 2015/11/20 29
• Extracted gain and phase imbalance variation over time
– Measurements taken in 8 different days:
– Gain and phase imbalance of thesystem vary very slowly over time
– Calibration routine can be done fromtime to time
Self‐healing: TX I/Q imbalance compensation
mmWWorkshop, Valencia, 2015/11/20 30
• Constellation at the receiver
Rx Measurement Results
Real-1 -0.5 0 0.5 1
-1
-0.5
0
0.5
1
Window 17, DS1 payload, Equa
mmWWorkshop, Valencia, 2015/11/20 31
• C‐RAN poses big challenges to the backhaul in Capacity and latency requirements:– Capacity up to 10 Gbps must be backhauled
• Millimetre wave technology working at E‐band is able to transmit 10 Gbps.– Using a SiGe transceiver + self‐healing techniques
Conclusions
Energy Efficient E‐band transceiver for backhaul of the future networks
Project reference: FP7‐ICT‐317957Project Coordinator: CEIT (Spain)Contact Name: Dr. IgoneVélez ([email protected])Start date: 01/12/2012End date: 31/05/2016