Millimeter Wave for 5G Features and implications (inspired by UT research)

Transcription

1 Millimeter Wave for 5G Features and implications (inspired by UT research) Professor Robert W. Heath Jr. Wireless Networking and Communications Group Department of Electrical and Computer Engineering The University of Texas at Austin Thanks to the National Science Foundation Grant No. NSF-CCF , NSF-CCF , NSF- CCF , the Intel / Verizon 5G program, the U.S. Department of Transportation through the Data-Supported Transportation Operations and Planning (D-STOP) Tier 1 University Transportation Center, the the Texas Department of Transportation under Project , and gifts from Nokia, MERL, Huawei, and Toyota.

2 Millimeter wave spectrum for 5G <1 GHz 5.2 GHz 555 MHz 2.4 GHz 100 MHz 900 MHz 2.6 MHz CmWave 28 GHz 1.3 GHz MmWave 39 GHz 37/42 GHz 1.4 GHz 2.1 GHz 20 GHz x100 GHz 60 GHz 7 GHz E-band 10 GHz total 6 GHz Unlicensed 100 GHz Even more spectrum More spectrum, in bands not previously used for cellular * T. Rappaport et al., Millimeter wave mobile communications for 5G cellular: It will work! IEEE Access, ** W. Roh et al., "Millimeter-wave beamforming as an enabling technology for 5G cellular communications: theoretical feasibility and prototype results,, IEEE Commun. Mag.,, 2014 *** A. Osseiran et al.,"scenarios for 5G mobile and wireless communications: the vision of the METIS project," iieee Commun. Mag., May

3 Implications of millimeter wave spectrum Shared licensed access possible to reduce cost, give carriers access to more spectrum* satellite communications Cognitive radio for shared spectrum with satellite or radar* carrier A cellular communications surface movement radar (K, Ka bands) Different propagation models** carrier B Antennas are much smaller** * J. Andrews, F. Baccelli, and R. Heath Fundamental Prop. of MmWave Networks: Signal, Intf., and Connectivity NSF grant for $1M. ** S. Rangan, T.S. Rappaport, E. Erkip, "Millimeter-Wave Cellular Wireless Networks: Potentials and Challenges,, Proc. IEEE, 2014 *** See UT s response to FCC NOI comments here 3

4 X capacity improvement Higher data rates in 5G with mmwave % 28 sparse 28 dense 72 sparse 72 dense Average 28 sparse 28 dense 72 sparse 72 dense Robert W. Heath Jr. (2015) Baseline 2 GHz: 50 MHz, 4x4 MIMO Upper cmwave 28 GHz: 500 MHz, 64x4 SISO mmwave 72 GHz: 2 GHz, 400x25 SISO MmWave can provide high peak, average, and outage rates (if dense) * * T. Bai and R. W. Heath Jr., Coverage and rate analysis for millimeter wave cellular networks, IEEE Trans. Wireless Commun., Feb ** T. Bai, A. Alkhateeb, and R. W. Heath, Jr., ``Coverage and Capacity of Millimeter Wave Cellular Networks," IEEE Communications Magazine, Sept

5 Implications of mmwave on new 5G scenarios Robert W. Heath Jr. (2015) AUTONOMOUS ROBOTS small size equipment Vehicle driving cloud mmwave base station VIRTUAL REALITY high data rate AUTONOMOUS DRIVING high data rates V2X COMMUNICATIONS low latency MmWave high data rates are required in different 5G scenarios 5

6 ROH_LAYOUT.qxp_Layout 1/30/14 1:20 PM Page 109 Robert W. Heath Jr. (2015) The conformal topology further maximizes the range of the beamsteering scanning angles in the azimuth plane. Moreover, the slanted topology conforms to the cellular device and enables the Globecom 2014 Workshop - Mobile Communications in Higher Frequency Bands designed mmwave antenna array to appear as an extremely low profile metallic trace line that Baseband Transmitter Receiver encompasses the edges of the PCB. The channel width of Array ant.which is even LNA the trace lines is less than 0.2 mm, (a) PA. lessdac than the 1 mm spacing.. required from the FFT ADC IFFT... surface mount techpcb edges for conventional 16-element array 1 nologies (SMTs). From thenvantage pointmimo of the a a Nr... Nc RF chains.... layout, t Nct RF chains.. hardware the inclusion of a total of 32 channel.. Phase shifters. r H mmwave antenna elements requires a negligible antenna footprint. Based. on this antenna solu<0.2 mm..... antenna system may FFT ADC IFFT tion,dac a truly massive MIMO Mixer actually be realizable for mmwave 5G in the RF beamformer RF beamformer long term. The beam patterns of each set of phased antennas are synthesized by the 28 GHz Figure 2. Block diagram ofarray a hybrid beamforming architecture. RF unit, composed of 32 6-bit phase shifters, power amplifiers, and low noise amplifiers for the transmit and receive paths, respectfully. presented in [5], where linkand system-level simulation results are provided with various The phases of the 28 GHz RF signal are indinumbers of transmit/receive antennas and RF vidually controlled to form a beam in the chains. Using a 500 MHz intended bandwidth at 28 GHz, direction along the azimuth plane. [5] presents some notableeach results forgrid theantenna hybrid element within the two RF/antenna mesh beamforming system including 8 db gain over sets ofanantenna arrays is connected with the element array 2 the conventional spatial GHz multiplexing scheme RF unit through K type coaxial connecand 8 Gb/s average sector throughput with 16 Superframe 30000*TB tors. The required RF signal phase information (b) antennas with 4 RF chains at the base station required steer the main lobe beam are stored Modem and 8 antennas with a single RFtochain at the Figure 3. Photographs of the mmwave 5G antenna system prototype: a) and retrieved from the in-house designed basemobile station. standalone view of the antenna array with K type coaxial connectors; b) band modem. integrated inside a Samsung cellular phone and zoomed in views of the The modem analog front-end (AFE) is conmmwave antenna region. nected to the RF port of the RF unit to transmmwave BEAMFORMING mit and receive the complex analog baseband P ROTOTYPE me 750*TB signal. The analog beamforming algorithm used BS In this section, we presentina this detailed description work is designed to search for and identims of the mmwave beamforming fy theprototype strongest develtransmit and receive beam Array antenna Diagnostic monitor oped and tested at the DMC R&D within Center, direction 45Samms. The current size of the sung Electronics, Korea, including system RF unit and baseband modem prohibits full Figure 3. Configuration of the mmwave beamforming prototype. configuration, key parameters, and capabilities. implementation inside the cellular phone protothe main purposes of the mmwave prototype type in this research. We are exploring a numare to check the feasibility of mmwave bands ber of different approaches to completely 8 antennas into a sub-array, thus requiring only for sufficiently large geographical coverage for integrate the mmwave array, RFper unit, 4 RF units channel instead of 32. The reduccellular services and support for mobility even inantenna baseband modem in the foreseeable future. tion in the number of RF paths results in a NLoS environments. As and a result, an mmwave In the meantime, the mmwave cellular phone reduction of antenna gain at the desired angle adaptive beamforming prototype was developed prototype containing two sets of 16-element (except antenna boresight), a reduction of beam including RF units, array antennas, baseband mesh grid antenna isscanning tested andranges, mea- and an increase in side lobe modems, and a diagnostic monitor (DM),arrays as levels, but still meets the overall beamforming shown in Fig. 3. sured in conjunction with a reference mmwave * Cudak, M. et. al., "Experimental mm wave 5G cellular system," in Globecom (GC Wkshps), 2014 requirements. Both transmit and receive array prototype antennas baseworkshops station as illustrated in Fig. 4.The resulting full width at half of the beam at the antenna have two channels and each 32 antenthecomprises measurement scenario maximum is confined(fwhm) to an ** W. Hong; K. Baek; Y. Lee; Y. Kim; S. Ko, "Study and prototyping of practically large-scale mmwave antenna systems 5G cellular devices," in IEEE boresight is approximately 10 for horizontally and na elements arranged in LOS the form of a uniform environment inside a laboratory located in 8 cm gain 20 vertically with an overall beamforming planar array (UPA) with 8the horizontal and 4 verheadquarters of Samsung Electronics, Commun. Mag., 2014 of 18phone dbi. In addition, a set256 of beam patterns tical elements, confined within ansouth area of 60 mm elements (16 16)isarray Suwon, Korea. The cellular proto(~24 dbi antenna gain) predefined to reduce the feedback overhead 30 mm.technology This small footprint wascellular made possi*** W. Roh et al. "Millimeter-wave beamforming as an enabling for communications: type 5G is fixed at a distance of 6 m away from thetheoretical feasibility and prototype results," in required for the adaptive beamforming operable by the short wavelength of the carrier frebase station prototype. Afterward, both mesh tion between the transmitter and the receiver, quency at GHz. Two channels at the IEEE Commun. Mag., 2014 antenna are connected two GHz Carrier frequency where to thethe overlapped beam patterns cover the transmit and receive arraygrid antennas arearrays designed available downlink channels of the RF unit and area with amicrowave intended service unique beam identito support various schemes such **** G. M. Rebeiz et. al. Millimeter-wave large-scale phased-arrays formulti-antenna 5G systems Proc. IEEE MTT-S International Symposium, the device (DUT). A beam. These Bandwidth/duplexing 520 MHz / TDD fiertest (ID) for each beam IDs are as MIMO and diversity. designated The arrayas antenna is under Use of directional and adaptive antenna arrays MIMO decoder S/P Prototype 64 element dielectric lens by Nokia* Baseband combiner S/P P/S Antenna arrays provide larger aperture P/S vs Baseband precoder MIMO encoder gether to form a TTI or slot. The payload 140 NSC-CP blocks containing 1 pilot k and 138 data blocks. 5 slots form a frames form a TDM superframe. At a rate, one slot period is exactly 100 us, one e superframe is 20 ms identical to 4G. ailable ADC rate have the system running mpling rate of 1.5 GHz. The numerology stem is captured in Table 1. Prototype phased arrays by Samsung **, *** system uses a standard LTE turbo decoderror correction. Multiple LTE physical mapped into three consecutive NCP-SC 8 cm Figureuse 6. Experimental BS Early mmwave devices will simplemmwave adaptive beam steering A dielectric lens focuses the mmwave energy like an optical lens focuses light. The size and curvature of the lens determines the gain and beamwidth of the antenna. Figure 7 shows a block diagram of the dielectric lens system. In this case, the gain of the antenna is 28 db and the corresponding half-power beamwidth (HPBW) is 3 degrees in both azimuth 6

7 Implications of adaptive arrays Beam training is a source of overhead Interference is bursty, SINR may be better* stronger interference weaker interference MIMO is posible, but power consumption is an issue Narrow beams reduce Doppler, require pointing** * A. Thornburg, T. Bai, and R. W. Heath, Jr., "Interference Statistics in a Random mmwave Ad Hoc Network, ICASSP 2015 ** Vutha Va, and Robert W. Heath, Jr, "Basic Relationship between Channel Coherence Time and Beamwidth in Vehicular Channels,'' IEEE VTC Fall,

8 Blockage is a major channel impairment X line-of-sight non-line-of-sight blockage due to buildings blockage due to people hand blocking User Handset X Base station Blocked by users body self-body blocking Need models for blockage & system analysis including blockage * W. Roh et al. "Millimeter-wave beamforming as an enabling technology for 5G cellular communications: theoretical feasibility and prototype results," in IEEE Commun. Mag., ** M. Akdeniz, Y. Liu, S. Sun, S. Rangan, T. Rappaport, E. Erkip, Millimeter Wave Channel Modeling and Cellular Capacity Evaluation, IEEE JSAC June

9 Implications of blockage High BS density and multibase connective provide diversity user with no coverage Indoor users not covered by outdoor infrastructure blocked interferer upper array blocked with fingers Handset diversity or user training lower array blocked by person unblocked interferer used for macro diversity Blockages reduce the impact of interference * T. Bai and R. W. Heath Jr., Coverage and rate analysis for millimeter wave cellular networks, IEEE Trans. Wireless Commun., Feb * *T. Bai and R. W. Heath Jr., Analysis of self-body blocking effects in millimeter wave cellular systems, in Proc. of Asilomar Conf., Nov

10 Power consumption may be high with mmwave Robert W. Heath Jr. (2015) Power at 60 GHz 1GHz BW LNA RF Chain ADC 20mW 40mW 200 mw mw Baseband processing Baseband Precoding LNA RF Chain ADC Alternative mmwave MIMO architectures are needed * R. Heath, N. Gonzalez-Prelcic, S. Rangan, A. Sayeed, W. Roh Overview of signal processing techniques for millimeter wave MIMO systems, under review IEEEE JSTSP

11 Implications of power consumption Design low power analog processing network RF Chain 1-bit ADC ADC Reduce resolution to operate with few bits **, *** RF combining Baseband Combining W RF N r L r N s RF Chain 1-bit ADC ADC W BB Adopt a hybrid architecture with many fewer RF chains than antennas * Non negligible power consumption at BB when running at Gsa/s * O. El Ayach, S. Rajagopal, S. Abu-Surra, Z. Pi, and R. Heath, Spatially sparse precoding in millimeter wave MIMO systems, IEEE Trans. Wireless Commun., 2014 **A. Alkhateeb, J. Mo, N. G. Prelcic, and R. W. Heath Jr, MIMO Precoding and Combining Solutions for Millimeter-Wave Systems, IEEE Commun. Mag *** Jianhua Mo and R. W. Heath, Jr., ``Capacity Analysis of One-Bit Quantized MIMO Systems with Transmitter Channel State Information, ' IEEE Trans. on Signal Processing,

12 Multiuser or massive MIMO at mmwave Less out of cell interference 256 antennas or BS Large MS Low channel dimensionality Incorporate blockage Large arrays are a natural application of massive MIMO techniques * F Boccardi, RW Heath Jr, A Lozano, TL Marzetta, P Popovski, Five Disruptive Technology Directions for 5G, IEEE Communications Magazine,

13 * T. Bai, R. Vaze, and R. W Heath, Jr., Analysis of Blockage Effects on Urban Cellular Networks, IEEE Trans. Wireless, ** T. Bai and R. W. Heath, Jr., Uplink massive MIMO SIR analysis: how do antennas scale with users? Proc. of Globecom Longer version on arxiv. *** T. Bai; R. Heath, "Asymptotic SINR for millimeter wave massive MIMO cellular networks," in Proc. of SPAWC, Robert W. Heath Jr. (2015) Implications of using mmwave for massive MIMO MmWave massive MIMO needs dense BS deployment Hybrid precoding Number of users limited by RF configuration Hybrid combining Hybrid combining Hybrid combining Choice of carriers depends on base station density MmWave provides large gain in area throughput in small-cell regime

14 The future is bright for mmwave Robert W. Heath Jr. (2015)

15 TRANSPORTATION joint radar and communication V2X communications radar aided comm. prototyping WEARABLES MIMO SIGNAL PROCESSING compressive channel estimation SU and MU hybrid precoding multi stream beam training INFORMATION THEORY COMMUNICATION THEORY stochastic geometric analysis of mmwave cellular overcoming blockage mmwave massive MIMO coverage and rate analysis capacity with low resolution ADCs Cooperative networks NETWORKS Cloud RAN 15