Multiband / Multimode Radio - Virginia Tech
Transcript of Multiband / Multimode Radio - Virginia Tech
NIJ Communications Technologies Spring TWG MeetingA PROGRAM OF THE NATIONAL INSTITUTE OF JUSTICE
Multiband/Multimode RadioEllingson / Hasan – April 2, 2008
Multiband / Multimode RadioSteve Ellingson ([email protected])
S.M. Shajedul Hasan ([email protected])
April 2, 2008
S.M. Hasan with a laboratory evaluation/demonstration prototype
NIJ Communications Technologies Spring TWG MeetingA PROGRAM OF THE NATIONAL INSTITUTE OF JUSTICE
Multiband/Multimode RadioEllingson / Hasan – April 2, 2008
Aud
io S
witc
h /
IP R
oute
r
Selected VoiceChannels
Selected Data Channel
Combine Many Radios into One*At least 13 bands relevant to Public Safety
x Many channels per band = A lot of radios!(*Above figure is just a functional description.)
Frequency Bands:VHF LO (25-50 MHz)VHF (138-174 MHz)220 MHzUHF (406-512 MHz)700 MHz P.S.800 MHz P.S.Cellular & PCS2.4 GHz ISM4.9 GHz P.S.
Concept / Research Direction
Developing a prototype radio capable of operation over a large range of frequency bands now in use for public safety applications.
Goal: Seamless Interoperability
NIJ Communications Technologies Spring TWG MeetingA PROGRAM OF THE NATIONAL INSTITUTE OF JUSTICE
Multiband/Multimode RadioEllingson / Hasan – April 2, 2008
I.M. M
UX
138-174
220-222
406-512
764-862
4.9 GHz Down
UHF
VHF
4.9 GHz Up
~ 10 dB
(BPF)
LO
ShortWhip
Ext.Ant.
~ 30 dB
A/D
A/D
D/A
D/A
FPGA
µP e
mul
atio
n
EmbeddedAntennas
800 MHz / PCS Cellular Chipset
2.4 GHz WLAN Cellular Chipset
CO
DEC
Oth
er I/
O
Touc
hscr
een
Knob
s
PTT
SPKRMIC
Technology Overview
VT Tranceiver Board usingMotorola Direct Conv. RFIC100-2500 MHz, 6.25 kHz – 10 MHz BW
VT Antenna-Tranceiver I/FRF Multiplexer
Baseband ADC/DAC(4 MSPS x 14/10 b) +Ref. Freq. Synthesizer
Baseband processing uses SoPC-centric approach; Currently100% Verilog HDL
- Baseband Mod/Demod- PTT Voice- Ethernet
NIJ Communications Technologies Spring TWG MeetingA PROGRAM OF THE NATIONAL INSTITUTE OF JUSTICE
Multiband/Multimode RadioEllingson / Hasan – April 2, 2008
Timeline for Activities• Formal Deliverables
• Phase I (Concept) Technical Report – Done• Phase II (Design) Technical Report – Done• Phase IV (Evaluation) Technical Report – July 2008 • Final Report – Oct 2008
• Currently in Phase III (Integration) – extended to accommodate Motorola RFIC and SoPC mods, which were changes from the original architecture.
• Phase IV (Evaluation)• Various lab demos available now• Extensive laboratory testing planned as part of Phase IV• Field demos planned ~ June 2008
NIJ Communications Technologies Spring TWG MeetingA PROGRAM OF THE NATIONAL INSTITUTE OF JUSTICE
Multiband/Multimode RadioEllingson / Hasan – April 2, 2008
Previous (Fall 2007) Prototype
RF Mux& R/T
RFIC4DemoBoard
ADC/DACBoard
Altera EP2S60 FPGA Board
PowerTI AIC32CODEC(under board)
138-174 MHz 220-222 MHz406-512 MHz764-900 MHz
Motorola SDR RFIC Ver. 4
4 MSPS basebandADC/DAC
Analog FM mode
SoPC approach:No µP; Instead completely implemented in FPGA
7 x 20 in. as shown here
Ethernet
NIJ Communications Technologies Spring TWG MeetingA PROGRAM OF THE NATIONAL INSTITUTE OF JUSTICE
Multiband/Multimode RadioEllingson / Hasan – April 2, 2008
Spring 2008 Prototype138-174 MHz 220-222 MHz406-512 MHz764-900 MHz
Motorola RFIC Ver. 4
4 MSPS basebandADC/DAC
Analog FM mode
SoPC approach:No µP; Instead completely implemented in FPGA
Since Fall 2007:- Battery- Touchscreen- Directly-integrated
off-the-shelf handset antenna
- Audio I/F with PTT
Three board stack integrates antenna, RF Mux, transceiver RFIC, ADC / DAC,ref. freq. synthesizer
Altera EP2S60 FPGA Board
Touchscreen
Ethernet
Battery underneath
AudioI/F
Off-the-shelf antenna
NIJ Communications Technologies Spring TWG MeetingA PROGRAM OF THE NATIONAL INSTITUTE OF JUSTICE
Multiband/Multimode RadioEllingson / Hasan – April 2, 2008
Direct Conversion Redux• Simplest way to accommodate wide tuning range, but traditionally
unacceptable because…• I/Q Imbalance is a problem – sideband rejection• 2nd order nonlinearity is a problem• 1/f noise in band is a problem• Initial BPF needs to tune, or a filter bank is required
NIJ Communications Technologies Spring TWG MeetingA PROGRAM OF THE NATIONAL INSTITUTE OF JUSTICE
Multiband/Multimode RadioEllingson / Hasan – April 2, 2008
RF CMOS Changes Everything• Idea: Implement RFICs using same inexpensive process used for
dense, high-speed digital circuitry
• Traditional objection: CMOS is fiendishly difficult to use for RF due to process variations and inaccurate design models
• These problems can now be largely mitigated by:• Implementing design to be robust to variations• Exploiting availability of nearby logic to enable radio to tweak chip
as needed
• Dense (90 nm!): Can put many copies of an RF path on a single chip
• RF and baseband can go on the same chip, if you are very careful about mitigating digital noise in the RF sections
NIJ Communications Technologies Spring TWG MeetingA PROGRAM OF THE NATIONAL INSTITUTE OF JUSTICE
Multiband/Multimode RadioEllingson / Hasan – April 2, 2008
Motorola Direct Conversion RFIC
SPI
FREF
FEXT
RXBB_IP
RX1P
LLOP_B
TX1P
AOC_TXRF
GND
VDD1_2
VDD2_5
1 GHz ReferencePLL / VCO
1 GHzReference
1 GHzReference
AGC_RX
Tx FEEDBACKQuIET
++
++
++
SUB
Chop Clock
RECEIVEQuIET
1 GHzReference
DYNAMIC MATCHING
Chop Clock
DYNAMIC MATCHING
Chop Clock
TxQuIET
QuIETDM
1 GHzReference
RX_QGEN_LOQuadGen
QuadGen
QuadGen
TX_QGEN_FWD_ LO
TX_QGEN_FB_LO
RxMixers
TxMixersTx FBMixers
Chop
Chop
1.2 V
1.2 V
1.2 V
2.5 V
2.5 V
RF_FB_INP
CP_PLL
TANKN
Multiple pads
Multiple pads
Mux
Mux
To Rx B B I
To Rx BB Q
Tx ReverseBB I Channel
Tx ReverseBB Q Channel
SPIControlledFuntions
RX1N
RX2PRX2N
RX3PRX3N
RX4PRX4N
RX5PRX5N
TX1N
TX2PTX2N
TX3PTX3N
LLON_B
RF_FB_INN
TX_BB_QNTX_BB_QP
TX_BB_INTX_BB_IP
RESETMISOMOSI
SPI_CLKCSEL
RXBB_IN
RXBB_QPRXBB_QN
TANKP
Multiple pads
DM
DM
DM
5 RX Paths (1 output) 90 nm CMOS 3 TX Paths (1 input) No inductorsRX F ~ 5 dB QFP-128RX IIP2 ~ +60 dB < 400 mA @ 2.5V (RX+TX)RX IIP3 ~ – 5 dBm
Tunes 100 - 2500 MHz (continuous) BW: 6.25 kHz – 10 MHz (many steps)Sideband Rejection ~ 40 dB, up to 60 dBInternal DDSs for LO generationExcellent mitigation of 1/f noise
Specs (Verified by VT in Independent Testing)
G. Cafaro et al., “A 100 MHz – 2.5 GHz Direct Conversion CMOSTransceiver for SDR Applications,” 2007 IEEE RFIC Symp., June 2007.
NIJ Communications Technologies Spring TWG MeetingA PROGRAM OF THE NATIONAL INSTITUTE OF JUSTICE
Multiband/Multimode RadioEllingson / Hasan – April 2, 2008
Advantages of RFIC-Based Direct Conversion in this Project
• Scalable – Same architecture works for reduced or increased number of simultaneous channels/bands (just add/remove chips)
• Reduced power (extended battery life) – lower power/channel and unneeded RFICs (or RFIC sections) can be shut down.
• Increased number of channels can be monitored simultaneously, even across bands: Scanner-like capability, “White space” seeker(s) for frequency-agile cognitive radio
• Con: Optimization requires calibration and tweaking of many parameters (over a low-bandwidth serial port)
NIJ Communications Technologies Spring TWG MeetingA PROGRAM OF THE NATIONAL INSTITUTE OF JUSTICE
Multiband/Multimode RadioEllingson / Hasan – April 2, 2008
Direct Conversion Transceiver Sections (2nd Gen.)
4-Band Transceiver Board40 mA (RX) + 40-90 mA (TX) + 80 mA/DDS @ 9V< 25 cm2 to implement on a 4-layer PCBAbout $100 in parts to implement, excluding PCB.
TR#22 for Fall 2007 version
ADC / DAC / LO Synthesizer BoardADC/DAC: 130 mA @ 9V, running 4 MSPS< 50 cm2 to implement on a 4-layer PCBADC ~ $21 (1k), DAC ~ $10 (1k)
These two boards stack vertically with the RFFE board using MMCX connectors (no RF cables)
NIJ Communications Technologies Spring TWG MeetingA PROGRAM OF THE NATIONAL INSTITUTE OF JUSTICE
Multiband/Multimode RadioEllingson / Hasan – April 2, 2008
Antenna-Transceiver Integration• Meeting selectivity specs is
one of the big challenges for this architecture
• Our approach: RF multiplexer optimized to antenna impedance with external noise dominance constraint
• No antenna tuning! • Simultaneous access to
multiple bands
“Transducer power gain” for RF multiplexer optimized for a 20 cm long monopole antenna
“External noise dominance” inVHF-High and 220 MHz bandsRF Front
End (RFFE)Board
(TR#25)
NIJ Communications Technologies Spring TWG MeetingA PROGRAM OF THE NATIONAL INSTITUTE OF JUSTICE
Multiband/Multimode RadioEllingson / Hasan – April 2, 2008
SDR Baseband Processing• Virtually all modern radios are “software defined” in the sense that
some functionality is implemented in software on a µP
• Modern notion of SDR emphasizes reconfigurability – achieving this in software requires large memory spaces, cache, etc.
• For an all-mode radio, SDR is useful primarily in that it may simplify the design by reducing the number of independent basebandsections, but it is not clear that it is better in any other sense (cost, size, weight, power). Truth here is somewhat application-specific.
• µP-based SDR makes sense if implementation in procedural languages or conformance to an existing architecture/paradigm isrequired. Not clear this makes sense for a “new start” radio which is not so contrained, however.
NIJ Communications Technologies Spring TWG MeetingA PROGRAM OF THE NATIONAL INSTITUTE OF JUSTICE
Multiband/Multimode RadioEllingson / Hasan – April 2, 2008
Alternative SoPC Strategy• SoPC – “System on a Programmable Chip”. Typically refers to use of a
single Field Programmable Gate Array (FPGA) to perform all computing in an embedded system
• Key idea: Dedicated microprocessors are overkill for many applications, whereas FPGAs are often essential for other reasons and can take on many functions traditionally assigned to microprocessors through “soft core” implementation.
• In an SoPC system, compute functions are assigned either to FPGA LEs(via HDL-derived firmware) or software (via a soft-core processor), and the previously awkward partition between FPGA firmware and microprocessor software is eliminated.
• Now relatively simple to implement “soft core” processing on an FPGA (Altera: Nios II, Xilinx: MicroBlaze)
NIJ Communications Technologies Spring TWG MeetingA PROGRAM OF THE NATIONAL INSTITUTE OF JUSTICE
Multiband/Multimode RadioEllingson / Hasan – April 2, 2008
SoPC in Contrast to SDR• In some sense, an SoPC-based radio is the opposite of SDR – we want to
implement as much as we can in efficient firmware (HDL), and strip the (inefficient) µP down to the minimum acceptable functionality
• In another sense, SoPC subsumes SDR, since we are talking about implementing software-defined functionality on firmware-defined processors!
• Potential advantages include cost, power, speed -- because only the functionality which is needed is implemented
• Explicit concurrency. This is a huge advantage over traditional SDR.
NIJ Communications Technologies Spring TWG MeetingA PROGRAM OF THE NATIONAL INSTITUTE OF JUSTICE
Multiband/Multimode RadioEllingson / Hasan – April 2, 2008
Our Baseband Strategy• Prototype currently implemented on an Altera Stratix II FPGA (EP2S60).
Massive overkill (60k LEs) but board familiar and readily available. Implemented directly via FPGA:• Analog FM waveform• Synthesis of 4 MHz ADC/DAC clocks • Interfaces to codec, ethernet, and display controller chips
• In our project, it appears that we will not need to implement a soft-core processor: We are currently 100% Verilog HDL.
• Target FPGA is Altera Cyclone III; 25k LEs, about $50 (chip). Power consumption is variable and hard to predict, but state-of-the-art power management features are available.
NIJ Communications Technologies Spring TWG MeetingA PROGRAM OF THE NATIONAL INSTITUTE OF JUSTICE
Multiband/Multimode RadioEllingson / Hasan – April 2, 2008
Challenges Remaining• Front End (Multiplexing/Duplexing). Now: Quite difficult to
design suitable multiplexers. MEMS may eventually make this easy.
• Antennas: Vehicles: Not a show-stopper, but existing solutions are ugly (“porcupine effect”). Handhelds: Need attention. We are at the physical limits; bending metal into new shapes will not help. Have ideas.
• Power amplifiers: Not scary; broadband (100-1000 MHz) ~1W solutions exist. However order of magnitude improvement and power/cost reduction are desirable
• Power supply noise in integrated configuration –Potentially limiting sensitivity (problem common to most low/zero IF architectures)
• New operational/security/training issues to manage
NIJ Communications Technologies Spring TWG MeetingA PROGRAM OF THE NATIONAL INSTITUTE OF JUSTICE
Multiband/Multimode RadioEllingson / Hasan – April 2, 2008
Outreach• Technical Reports – available via web site
• 25 since project start• Many include detailed design information, CAD files, etc.
• Public Presentations & Papers• MissionCritical Communications Article, March 2007• Presentations at IWCE 2006, 2007, 2008• Presentation+paper at SDR Forum 2006
• Liaison with Industry• Motorola Research Labs – RFIC collaboration• Tyco (M/A-COM) & EF Johnson – Discussions
NIJ Communications Technologies Spring TWG MeetingA PROGRAM OF THE NATIONAL INSTITUTE OF JUSTICE
Multiband/Multimode RadioEllingson / Hasan – April 2, 2008
Thanks!
Web Sites:http://www.ece.vt.edu/swe/chamrad/http://www.ece.vt.edu/swe/http://wireless.vt.edu/
U.S. Dept. of JusticeNational Institute of Justice
Grant 2005-IJ-CX-K018
Acknowledgements:Motorola: G. Cafaro, B. Stengle, N. CorrealMahmud Harun (student)Rithirong Thandee (student)
Short Course & Demo:Wireless @ Virginia Tech Annual Symposium and Summer SchoolJune 4-6, 2008