Millimeter-wave Mobile Broadband: Unleashing 3-300GHz Spectrum

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Godwin Taylor
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2 Outline Introduction Mobile broadband growth The myth of traffic and revenue gap The national broadband plan mmw spectrum History of millimeter wave communications Unleashing 3-300GHz spectrum LMDS and 70/80/90 GHz bands mmw Propagation characteristics Free Space Propagation Material penetration loss Oxygen and water absorption Foliage absorption Rain absorption Diffraction Ground reflection mmw Mobile Broadband (MMB) network architecture Stand-alone MMB system MMB base station grid Hybrid MMB + 4G systems Deployment and antenna configuration MMB air-interface design Duplex and multiple access schemes Frame Structure Channel coding and modulation Dynamic beamforming with miniature antennas Beamforming fundamentals Baseband beamforming Analog beamforming RF beamforming Beamforming in fading channels Radio frequency components design and challenges RF transceiver architecture MMB RF transceiver requirement mmwave Power amplifier mmwave LNA MMB system performance Link budget analysis Link Level performance Geometry distribution System throughput analysis Summary Copyright 011 by the authors. All rights reserved.

3 Outline Introduction Mobile broadband growth The myth of traffic and revenue gap The national broadband plan mmw spectrum History of millimeter wave communications Unleashing 3-300GHz spectrum LMDS and 70/80/90 GHz bands mmw Propagation characteristics Free Space Propagation Material penetration loss Oxygen and water absorption Foliage absorption Rain absorption Diffraction Ground reflection mmw Mobile Broadband (MMB) network architecture Stand-alone MMB system MMB base station grid Hybrid MMB + 4G systems Deployment and antenna configuration MMB air-interface design Duplex and multiple access schemes Frame Structure Channel coding and modulation Dynamic beamforming with miniature antennas Beamforming fundamentals Baseband beamforming Analog beamforming RF beamforming Beamforming in fading channels Radio frequency components design and challenges RF transceiver architecture MMB RF transceiver requirement mmwave Power amplifier mmwave LNA MMB system performance Link budget analysis Link Level performance Geometry distribution System throughput analysis Summary Copyright 011 by the authors. All rights reserved. 3

4 Outline Introduction Mobile broadband growth The myth of traffic and revenue gap The national broadband plan mmw spectrum History of millimeter wave communications Unleashing 3-300GHz spectrum LMDS and 70/80/90 GHz bands mmw Propagation characteristics Free Space Propagation Material penetration loss Oxygen and water absorption Foliage absorption Rain absorption Diffraction Ground reflection mmw Mobile Broadband (MMB) network architecture Stand-alone MMB system MMB base station grid Hybrid MMB + 4G systems Deployment and antenna configuration MMB air-interface design Duplex and multiple access schemes Frame Structure Channel coding and modulation Dynamic beamforming with miniature antennas Beamforming fundamentals Baseband beamforming Analog beamforming RF beamforming Beamforming in fading channels Radio frequency components design and challenges RF transceiver architecture MMB RF transceiver requirement mmwave Power amplifier mmwave LNA MMB system performance Link budget analysis Link Level performance Geometry distribution System throughput analysis Summary Copyright 011 by the authors. All rights reserved. 81

5 RF Transceiver Transceiver key RF components Antenna, Filters, Power Amplifier (PA), Low-Noise Amplifier (LNA), Oscillator (VCO), Mixer and Data converters (DAC/ADC) Copyright by the authors, all rights reserved

6 Nonlinear Device In the most general sense, the output response of a nonlinear circuit can be modeled as a Taylor series in terms of the input signal voltage v = a + a v + a v + a v +L i i 3 i where the Taylor Coefficients are defined as a a a = v dv0 = dv ( 0) d v0 = dvi i v i v = 0 i = 0 and higher order terms vi vo Copyright by the authors, all rights reserved

7 Gain Compression Consider the case where a single frequency sinusoid is applied to the input of a nonlinear device such as a power amplifier v = V cosω t i 0 0 v = a + a V cosω t + a V cos ω t + a V cos ω t +L cos ω0t v0 = a0 + a1v 0 cosω0t + av cosω0t + cos ω0t a3v 0 cos ω0t + a3v L v0 = a0 + av0 + a1v 0 + a3v 0 cosω0t av0 cos ω0t + a3v 0 cos3ω 0t +L 4 Voltage gain at frequency ω 3 3 a1v 0 + a3v G = = a + a V V 4 a is negative in most practical amplifiers Copyright by the authors, all rights reserved

8 Intermodulation Distortion Consider two-tone input voltage consisting of two closely spaced frequencies ω1 ω ω1 ω 3ω 1 3ω i o ( cosω cosω ) v = V t + t 0 1 ω ω ω ω 1 1 ω ω + ω ω1 1 3 ( cosω cosω ) ( cosω cosω ) ( cosω cosω ) ω + ω 1 v = a + a V t + t + a V t + t + a V t + t + L ω + ω 1 1 vo = a0 + a1v 0 cosω1t + a1v 0 cosωt + av0 ( 1+ cos ω1t ) + av0 ( 1+ cos ωt ) av0 cos( ω1 ω) t + av0 cos( ω1 + ω) t + a3v 0 cosω1t + cos 3ω 1t + a3v 0 cosωt + cos 3ω t a3v 0 cosωt + cos( ω1 ω) t + cos( ω1 + ω) t a3v 0 cosω1t cos( ω ω1 ) t cos( ω ω1 ) t L Output spectrum consists of harmonics of the form mω + nω m, n = 0, ± 1, ± ± 3, L 1 These combinations of the two input frequencies are called intermodulation products 1 Copyright by the authors, all rights reserved

9 Third-Order Intercept Point (IP3) P ω 1 = 1 a V ω ω = 3 0 = 3 0 P 1 a V a V 4 3 These two powers are equal at the third-order IP Let input signal voltage at the IP be V 1 9 a V = a V 3 V IP 6 1 IP 3 IP = 4a 3a 1 1 P P a V a = ω 1 V0 = V = IP 1 IP = 3a3 IP Copyright by the authors, all rights reserved

10 Mixer f IF frf = flo ± fif f RF fif = frf ± flo f LO f LO f LO f IF f LO + f IF 0 fif flo 0 f LO frf frf flo = fif f RF + f LO ( ) ( ) ( ) vrf t = K vlo t vif t = K cos π flot cos π fift K vrf ( t) = cos π ( flo fif ) t + cos π ( flo + fif ) t ( ) ( ) ( ) vif t = K vlo t vrf t = K cos π flot cos π frft K vif ( t) = cos π ( frf flo ) t + cos π ( frf + flo ) t Copyright by the authors, all rights reserved

11 Image Frequency fim = flo fif frf = flo + fif frf = flo fif fim = flo + fif 0 fif flo 0 fif flo f IF f IF f = f f = ( f + f ) f = f IF RF LO LO IF LO IF f = f f = ( f f ) f = f IF IM LO LO IF LO IF f = f f = ( f f ) f = f IF RF LO LO IF LO IF f = f f = ( f + f ) f = f IF IM LO LO IF LO IF -f IF is mathematically identical to f IF because the frequency spectrum of any real signal is symmetric about zero frequency, and thus contains negative as well as positive frequencies A received RF signal at the image frequency f IM is indistinguishable at the IF stage from the desired RF signal of frequency f RF Copyright by the authors, all rights reserved

12 Homodyne (Zero-IF) Receiver 1+ cos ω RFt I ( t) = cosωrft cosωrft = cos ωrft = After low pass filtering 1 I ( t) = 1 cos ωrf t Q ( t) = sinωrft sinωrft = sin ωrft = After low pass filtering ( ) Q t = 1 Benefits Drawbacks Less hardware Low power consumption No IF stage and hence no image filter LO Leakage DC offset errors I/Qmis-match Flicker (or 1/f) noise Copyright by the authors, all rights reserved

13 Super-heterodyne Receiver f LO f IF Benefits Drawbacks Good sensitivity Good selectivity High Q filter High performance oscillator LNA output impedance matched to 50 ohm is difficult Integration of HF image reject filter is a major problem Copyright by the authors, all rights reserved

14 Wideband-IF Receiver I ( t) cos ( ω ) IF t I ' ( t ) sin ( ω ) IF t ω LO ( ) Q t cos ( ω ) IF t Q ' ( t ) Benefits Drawbacks Image cancellation by IR mixer IR Mixer Image rejection from the RF front-end preselection filter Good phase noise performance Copyright by the authors, all rights reserved

15 Wideband-IF Receiver (Image Rejection) Low-side injection Signal of interest Image ωrf ωlo = ωlo ωim = ωif ( ) ( ) ( ) = ( ) + ( ) x cos ω t α = x cosα cosω t + x sinα sinω t RF RF RF RF RF RF x cos ω t β = x cos β cosω t + x sin β sinω t IM IM IM IM IM IM I t xrf cos ωrft α xim cos ωimt β cosωlot 1 1 = xrf { cos( ωift α ) + cos ( RF LO ) } IM cos( IF ) cos ( IM LO ) ω + ω t α + x ω t + β + t ω + ω β Q ( t ) = x RF cos ( ω RF t α ) + x IM cos ( ω IM t β ) sin ω LO t 1 1 = xrf { sin ( ωift α ) + sin ( ωrf ωlo ) t α } xim sin ( ωift β ) sin ωim ( ) + ωlo t β After low-pass filtering ( ) = ( ) ω ( ) ω = α + ( ω + β ) ( ) = ( ) ω + ( ) ω = α + ( ω t + β ) { } { } 1 1 I ( t) = xrf cos ( ωift α ) xim cos ( ωift β ), Q( t) xrf sin ( ωift α ) xim sin ( ωift β ) + + = I ' t I t cos IFt Q t sin IFt xrf cos xim cos IFt 1 1 Q ' t I t sin IFt Q t cos IFt xrf sin xim sin IF After low-pass filtering 1 1 I '( t) = xrf cos α, Q '( t ) = xrf sinα Copyright by the authors, all rights reserved

16 Low-IF Receiver ( π f t) cos LO ( π f t) sin LO ( π f t) cos LO Benefits Drawbacks Potential advantages of both heterodyne and homodyne receivers. The IF frequency is just one or two channels bandwith away from DC, which is just enough to overcome DC offset problems. Image reject mixer which is implemented in digital baseband ADC dynamic range Copyright by the authors, all rights reserved

17 Downlink RF Transceiver Requirement Base station transmitter Transmit antennas / antenna arrays 0 30 db antenna gain, horn antennas or phase antenna arrays ( elements) Power amplifier 0 50 dbm, >0% efficiency, EVM < 5% for OFDM waveform Packaging Integrated solution of antenna array / PA / MMIC / RFIC to minimize transmission loss Mobile station receiver Receive antenna arrays 6 18 db antenna gain, phase antenna arrays (4 64 elements) Receiver sensitivity < -80dBm Total Rx chain Noise Figure < 7dB Similar solutions exist today! 60GHz CMOS RFIC with phase antenna array (BWRC) 60GHz Single-chip integrated antenna and RFIC (GEDC) Packaging Integrated solution of antenna array / LNA / MMIC / RFIC to minimize transmission loss Copyright by the authors, all rights reserved 94

18 Uplink RF Transceiver Requirement Mobile station transmitter Transmit antenna arrays 6 18 db antenna gain, phase antenna arrays (4 64 elements) Power amplifier 0 3 dbm, >0% efficiency, EVM < 5% for 16QAM single-carrier waveform Packaging Integrated solution of antenna array / PA / MMIC / RFIC to minimize transmission loss Power consumption on the order of 100mW ~ 1W Base station receiver Receiving antennas / antenna arrays 0 30 db antenna gain, horn antennas or phase antenna arrays ( elements) Receiver sensitivity < -95 dbm Total Rx Noise Figure < 5dB Packaging Integrated solution of antenna array / PA / MMIC / RFIC to minimize transmission loss Copyright by the authors, all rights reserved 95

for satellite and radar Cost in 10K s of US$ (too expensive for cellular) Need to

19 Travelling Wave Tube (TWT) Power Amplifier TWT amplifiers have been extensively used for high power applications at millimeter wave frequencies Provides KWs to MWs power for satellite and radar Cost in 10K s of US$ (too expensive for cellular) Need to consider solid-state amplifier design for MMB Copyright by the authors, all rights reserved

20 Solid-state Power Amplifier Gallium-Nitride based power amplifier Wide bandgap materials such as gallium nitride (GaN) or silicon carbide (SiC) have much larger bandgaps than conventional semiconductors Gallium-nitride High Electron Mobility Transistor (GaNHEMT) devices have breakdown voltages 10 times higher than GaAs HEMT devices, allowing GaN HEMT devices to operate with much higher voltages Source: Gallium Nitride (GaN) Microwave Transistor Technology For Radar Applications, Microwave Journal, January

21 Solid-state Power Amplifier State-of-the-art for solid-state mmwave PAs 11 Watts at 34 GHz (D. C. Streit, et. al., The future of compound semiconductors for aerospace and defense applications, CSIC 005) 84 mwat 88 GHz (M. Micovic, et. al., W-Band GaNMMIC with 84mW output power at 88 GHz, IMS 010) 5. Watts at 95 GHz with a 1-way radial-line combiner (James Schellenberg, et. al., W-Band, 5W solidstate power amplifier/combiner, IMS 010) Source: Gallium Nitride (GaN) Microwave Transistor Technology For Radar Applications, Microwave Journal, January

22 Cascaded Constructive Wave Amplifier Source: J. Buckwalter and J. Kim, ISSCC 009 Forward wave is amplified as it propagates along the transmission line Backward wave is attenuated as it propagates Distribution of N cascaded traveling wave stages Active devices along the transmission line provide feedback Relative phase of transmission line and active device determines amplification/ attenuation.

23 Low-Noise Amplifier [1/] Single Stage 60 GHz LNA Source: Javier Alvarado, PhD thesis, May 008 Gain Noise Figure Power Consumption 1-dB compression point 1 db 5 db over GHz 4.5mA from a 1.8 V source +1.5dBm Efficiency 17.4% Process IBM0.1 μm, 00 GHz f T, SiGe technology.

24 Low-Noise Amplifier [/] Two Stage 3 3GHz LNA = + IP3, tot IP3,1 IP3, Source: El-Nozahi et al, IEEE JOURNAL OF SOLID-STATE CIRCUITS, FEB 010 G Gain Noise Figure Power Consumption IP3 Efficiency Process 1 db dB over 3 3 GHz 13mW from a 1.5 V source -4.5dBm to -6.3dBm[stage1=-dBm, stage=7dbm] NA Jazz Semiconductor 0.18 m BiCMOS

25 Outline Introduction Mobile broadband growth The myth of traffic and revenue gap The national broadband plan mmw spectrum History of millimeter wave communications Unleashing 3-300GHz spectrum LMDS and 70/80/90 GHz bands mmw Propagation characteristics Free Space Propagation Material penetration loss Oxygen and water absorption Foliage absorption Rain absorption Diffraction Ground reflection mmw Mobile Broadband (MMB) network architecture Stand-alone MMB system MMB base station grid Hybrid MMB + 4G systems Deployment and antenna configuration MMB air-interface design Duplex and multiple access schemes Frame Structure Channel coding and modulation Dynamic beamforming with miniature antennas Beamforming fundamentals Baseband beamforming Analog beamforming RF beamforming Beamforming in fading channels Radio frequency components design and challenges RF transceiver architecture MMB RF transceiver requirement mmwave Power amplifier mmwave LNA MMB system performance Link budget analysis Link Level performance Geometry distribution System throughput analysis Summary Copyright 011 by the authors. All rights reserved. 10

26 MMB downlink budget Key system configuration parameters Base station Txpower: 35dBm 40dBm Base station Txantenna gain: 17 db 3 db Mobile station Rx antenna gain: 3 db 10 db MMB link downlink budget analysis Case 1 Case Case 3 Case 4 Case 5 Case 6 Case 7 Case 8 Transmit Power (dbm) Transmit Antenna Gain (dbi) Carrier Frequency (GHz) Distance (km) Propagation Loss (db) Other losses Receive Antenna Gain (db) Received Power (dbm) Bandwidth (MHz) Thermal Noise PSD (dbm/hz) Noise Figure Thermal Noise (dbm) SNR (db) Implementation loss (db) Spectram Efficiency Data rate (Mbps) Path loss formula: PL = log 10 d with d in km (free-space loss + 0dB) Copyright 011 by the authors. All rights reserved. 103

27 MMB uplink budget Key system configuration parameters Mobile station Txpower: 0dBm 3dBm Mobile station Txantenna gain: 3 db 10 db Base station Rx antenna gain: 17 db 3 db MMB uplink budget analysis Case 1 Case Case 3 Case 4 Case 5 Case 6 Case 7 Case 8 Transmit Power (dbm) Transmit Antenna Gain (dbi) Carrier Frequency (GHz) Distance (km) Propagation Loss (db) Other losses Receive Antenna Gain (db) Received Power (dbm) Bandwidth (MHz) Thermal Noise PSD (dbm/hz) Noise Figure Thermal Noise (dbm) SNR (db) Implementation loss (db) Spectram Efficiency Data rate (Mbps) Path loss formula: PL = log 10 d with d in km (free-space loss + 0dB) Copyright 011 by the authors. All rights reserved. 104

28 Link Budget Analysis Summary MMB downlink budget Low end: 35 dbmtxpower, 17 db Txantenna gain, 3 db Rx antenna gain, 5 db implementation loss 180 Mbps on 500 MHz bandwidth at 500 meters High end: 40 dbmtxpower, 3 db Txantenna gain, 10 db Rx antenna gain, 5 db implementation loss) 145 Mbps on 500 MHz bandwidth at 500 meters MMB uplink budget Low end: 0 dbmtxpower, 3 db Txantenna gain, 17 db Rx antenna gain, 5 db implementation loss 9.9 Mbps on 50 MHz bandwidth at 500 meters High end: 3 dbmtxpower, 10 db Txantenna gain, 3 db Rx antenna gain, 5 db implementation loss 139 Mbps on 50 MHz bandwidth at 500 meters Conclusion Assuming free-space plus 0dB path loss, MMB can provide 100 Mbps ~ Gbps cell-edge throughput on the downlink and 10 Mbps ~ 100 Mbps cell-edge throughput on the uplink at 8 GHz for cell radius of 500 meters. Copyright 011 by the authors. All rights reserved. 105

Layered decoding Maximum number of iterations

30 System Level Performance 19 cells wrap-around 1 sectors per cell 1 horn antenna per sector 0 db antenna gain 17.5 o 3-dB beamwidthin azimuth domain 10 o 3-dB beamwidthin elevation domain 30 db front-to-back ratio Base station Txpower = 13, 16, 19, dbm/mhz Mobile station uniformly dropped in the coverage area Copyright 011 by the authors. All rights reserved. 107

31 Geometry with Single Rx Antenna Site-to-site distance = 500 meters 3dB worse 5%-tile geometry than cellular Interference limited Single Rx antenna with -1 db antenna gain No Rx beamforming PLF1: PL = log 10 d with d in km 1dB Lognormal shadowing 8dB Lognormal shadowing for cellular Cellular, 33dBmPerMHz 13dBmPerMHz, PLF1, NoBF 16dBmPerMHz, PLF1, NoBF 19dBmPerMHz, PLF1, NoBF dbmpermhz, PLF1, NoBF Copyright 011 by the authors. All rights reserved. 108

32 Geometry with Single Rx Antenna Site-to-site distance = 500 meters Single Rx antenna with -1 db antenna gain No Rx beamforming PLF: PL = log 10 d with d in km 1dB Lognormal shadowing 8dB Lognormal shadowing for cellular 6 db worse 5%-tile geometry than cellular Cellular, 33dBmPerMHz 16dBmPerMHz, PLF, NoBF dbmpermhz, PLF, NoBF 13dBmPerMHz, PLF, NoBF 19dBmPerMHz, PLF, NoBF Copyright 011 by the authors. All rights reserved. 109

33 Mobile station Rx beamforming ϕ = φ + kd cosθ Nϕ sin = AF ϕ sin RxBeam 1 RxBeam RxBeam 3 RxBeam 4 4-element uniform linear array N=4, d=λ/, k=π/λ 4 fixed beams (φ=0, π/, π, 3π/) Mobile station orientation is random ~ U[0, π) Mobile station selects the beam that maximizes geometry Copyright 011 by the authors. All rights reserved. 110

34 Geometry with Rx Beamforming Site-to-site distance = 500 meters 4-element antenna array with - 3 db antenna gain per element Rx beamforming PLF1: PL = log 10 d with d in km 1dB Lognormal shadowing 8dB Lognormal shadowing for cellular The same 5%-tile geometry as cellular Interference limited Cellular, 33dBmPerMHz 16dBmPerMHz, PLF1, RxBF dbmpermhz, PLF1, RxBF 13dBmPerMHz, PLF1, RxBF 19dBmPerMHz, PLF1, RxBF Copyright 011 by the authors. All rights reserved. 111

35 Geometry with Rx Beamforming Site-to-site distance = 500 meters 4-element antenna array with - 3 db antenna gain per element Rx beamforming PLF1: PL = log 10 d with d in km 1dB Lognormal shadowing 8dB Lognormal shadowing for cellular 0-3dB worse 5%-tile geometry than cellular Cellular, 33dBmPerMHz 16dBmPerMHz, PLF, RxBF dbmpermhz, PLF, RxBF 13dBmPerMHz, PLF, RxBF 19dBmPerMHz, PLF, RxBF Copyright 011 by the authors. All rights reserved. 11

36 System Throughput Analysis MMB system performance analysis assumptions Number of cells 19 Number of sectors per cell 1 Site to site distance 500 meters Carrier frequency 8 GHz System bandwidth 500 MHz Path loss model log 10 d, or log 10 d Base station Txpower 40, 43, 46, or 49 dbm Base station Tx antenna configuration Single horn antenna Base station Tx antenna gain 0 db Log-normal shadow fading STD 1 db Mobile station Rx noise figure 7 db Mobile station Rx antenna configuration Single antenna, or Rx beamforming with 4-element ULA Mobile station Rx antenna gain -1 db for single antenna case, -3 db for ULA case System overhead (cyclic prefix, control channels, etc.) 40% Transceiver implementation loss 3 db Copyright 011 by the authors. All rights reserved. 113

37 System Throughput PLF provides higher system throughput than PLF1 Cell throughp put (Mbps) PLF1, NoBF PLF, NoBF PLF1, RxBF PLF, RxBF 30xLTE cell throughput (4Tx MIMO per sector, 3-sector cell, 0MHz system bandwidth) Base station transmit power per sector (dbm) RxBFsignificantly improves system throughput Copyright 011 by the authors. All rights reserved. 114

38 Cell-edge performance PLF1 allows better celledge throughput than PLF cell-edge throug ghput (Mbps) PLF1, NoBF PLF, NoBF PLF1, RxBF PLF, RxBF Base station transmit power per sector (dbm) RxBFsignificantly improves system throughput Copyright 011 by the authors. All rights reserved. 115

39 Outline Introduction Mobile broadband growth The myth of traffic and revenue gap The national broadband plan mmw spectrum History of millimeter wave communications Unleashing 3-300GHz spectrum LMDS and 70/80/90 GHz bands mmw Propagation characteristics Free Space Propagation Material penetration loss Oxygen and water absorption Foliage absorption Rain absorption Diffraction Ground reflection mmw Mobile Broadband (MMB) network architecture Stand-alone MMB system MMB base station grid Hybrid MMB + 4G systems Deployment and antenna configuration MMB air-interface design Duplex and multiple access schemes Frame Structure Channel coding and modulation Dynamic beamforming with miniature antennas Beamforming fundamentals Baseband beamforming Analog beamforming RF beamforming Beamforming in fading channels Radio frequency components design and challenges RF transceiver architecture MMB RF transceiver requirement mmwave Power amplifier mmwave LNA MMB system performance Link budget analysis Link Level performance Geometry distribution System throughput analysis Summary Copyright 011 by the authors. All rights reserved. 116

40 Summary Millimeter wave spectrum (3-300GHz) can potentially provide the bandwidth required for mobile broadband applications for the next few decades and beyond. Opportunity to open 00 times the spectrum currently allocated for cellular below 3GHz. Propagation and other losses due to rain, foliage and penetration through building materials needs better understanding Millimeter waves are also attractive for mobile application due to small component sizes such as antennas. Further research is needed towards components and devices that meets mobile application demand of higher power and efficiency Wireless community should take on the growing data demand by exploiting millimeter wave spectrum paving the way for multi-gbps mobile broadband. Copyright 011 by the authors. All rights reserved. 117

mm Wave Communications J Klutto Milleth CEWiT

mm Wave Communications J Klutto Milleth CEWiT Technology Options for Future Identification of new spectrum LTE extendable up to 60 GHz mm Wave Communications Handling large bandwidths Full duplexing on