Experimental mmwave 5G Cellular System

Transcription

1 Experimental mmwave 5G Cellular System Mark Cudak Principal Research Specialist Tokyo Bay Summit, 23 rd of July Nokia Solutions and Networks 2015 Tokyo Bay Summit 2015 Mark Cudak

2 Collaboration partnership on the journey to 5G 2020 Olympics 2019 WRC Phase 1 standard GPP work item GPP 5G study begins 2015 Field testing, WRC Delivery of mmwave Demo 2 Nokia Solutions and Networks 2015

3 5G Scalable air interface design across frequency bands Expanding the spectrum assets to deliver capacity and experience Spectrum availability LOS Spectrum Antenna size Network layer 90 GHz 30 GHz ~Nx1GHz carrier bandwidth Dynamic TDD Very small Low rank MIMO and beamforming Ultra high capacity and data rates 10 GHz 6GHz ~Nx100 MHz carrier bandwidth Dynamic TDD Small High Rank MIMO and beamforming Boosting capacity and data rates Cell size LOS/NLOS 3 GHz 10 cm 300 MHz 1m ~Nx10 MHz carrier bandwidth FDD and TDD Medium - large High Rank MIMO and beamforming Providing base coverage and capacity 3 Nokia Solutions and Networks 2015

4 mmwave System Concept A much anticipated solution to meet 4G data demand is network densification - 4G small cells will be deployed at street-level - Micro/pico base stations deployed on lamp posts and sides of buildings. - A pico base station will be deployed every city block or roughly 120 meter site-to-site. The mmwave system concept is intended to complement this small cell deployment - Higher frequency cellular transceivers co-located with the 4G base stations. - Simultaneously provide backhaul for 4G and access/backhaul for 5G. User device synchronized to multiple BS s 4x4 array with ½ wavelength spacing User 120 m site-to-site distance 4 Nokia Solutions and Networks 2015

5 mmwave Massive MIMO/Beamforming Solution Power consumption is one critical aspect for mmwave deployments. - ADCs capable of sampling a 2 GHz BW signal will be a major factor in power consumption. - Full digital baseband transceiver behind each element would consume an unacceptable amount of power. - Analog (aka RF-radio frequency) beam forming techniques will be employed to steer the array elements on the panel. The antenna panel would host a highly integrated mmwave circuit - Array of patch antenna elements bonded to an antenna distribution layer with power amplifiers, low noise amplifiers and phase shifters. - Signal summed and down converted on the die and mixed down to where it could be generated or sampled by DAC and ADC - A separate antenna panel would be used for each orthogonal polarization. RFIC Die signal distribution Antenna distribution layer Baseband Distribution layer LO & PWR distribution layer ADC DAC Φ Φ Φ Φ Σ RF xn LO 2x2 RFIC 5 Nokia Solutions and Networks 2015

6 5G mmwave Challenges & Proof Points Unique difficulties that a mmwave system must overcome - Narrow beamwidths, provided by these high dimension arrays - High penetration loss and diminished diffraction. Two of the main difficulties are: - Acquiring and tracking user devices within the coverage area of base station using a narrow beam antenna - Mitigating shadowing with Base station diversity and Rapidly Rerouting around obstacles when user device is shadowed by an opaque obstacle in its path. Other 5G aspects the current experimental system addresses: - High peak rates and cell edge rates (2.3 Gbps peak, 100 Mbps cell edge) - Low-latency (< 1ms) 6 Nokia Solutions and Networks 2015

7 5G Experimental System Frame Structure Analog beamforming has implications for the modulation format used on the mmwave link - Beamforming weights are wide-band and, for OFDM, all subcarriers within a TTI must share the same beam - Time division multiplexing (TDM) is favored over frequency division multiplexing (FDM) - TDM suggests low PAPR modulation techniques can be considered to reduce the PA backoff and maximize the transmission power The mmwave link utilizes single carrier modulation to maintain a low. PAPR - PAPR is further reduced using π/2 shifting of BPSK, π/4 shifting of QPSK The QAM symbols are grouped into blocks of 512 symbols The modulation format is called Null Cyclic Prefix Single Carrier (NCP-SC)[8] - The QAM symbols are grouped into blocks of 512 symbols - M data = 480 and M cp = 32 provides 40 ns RMS delay spread resilience. - The null cyclic prefix can be increased or decreased on a per TTI basis without impacting the overall system numerology. The experimental system operates with a 1 GHz bandwidth using the 512 symbol NCP-SC block. A commercial system is envisioned to use a 1024 symbol NCP-SC block to achieve a 2 GHz bandwidth. - Achieves 10 Gbps peak rate with 2x2 MIMO Superframe 30000*TB RESRVED TDM Slot 150*TB TDD Frame 750*TB Payload Burst NCP-SC Block Frame & Slot Timing Modulation & Coding 5G Modulation Coding Rate Data Rate Modulation (Gbps) BSPK QPSK QPSK QPSK 16 QAM QAM 16 QAM QAM F sampling F B T B Slot Frame Superframe (GHz) (Blocks/s) ( μs) ( μs) ( μs) (ms) E E MData-12 MData-11 MData-10 MData-9 MData-8 MData-7 MData-6 MData-5 MData-4 MData-3 MData-2 MData-1 MData MCP-2 MCP-1 MCP QAM Data Symbols TB NCP-SC Numerology Block M Data M CP Format A B NULL Padding 7 Nokia Solutions and Networks 2015

8 Nokia 5G mmwave beam tracking demonstrator First 5G demos CEATEC 2014 Mobile device Access point 70 GHz band 1 GHz bandwidth Lens antenna with 64-beam switching 3 beam width 8 Nokia Solutions and Networks 2015

9 Steerable Lens Antenna A dielectric lens focuses the mmwave energy like an optical lens focuses light. Feeder LCP module - Size and curvature of the lens determines the gain and beamwidth of the antenna. - Antenna gain 28 db and the corresponding half-power beamwidth (HPBW) is 3 degrees in both azimuth and elevation. BPA LNA T/R switch Switch tree 3 levels SP4T Feeder array 4x16 Lens 95 mm Direction of the beam can be selected by moving the position of the focal point at the base of the lenses patch antennas are switched by 3 levels of SP4T switches that determine which one of the 64 elements is excited for transmission or selected for reception. - The HPBWs slightly overlaps that a gain within 3dB can be maintained over the steering range of the lens. Half Power Beam 71 GHz θ = +/- 4 degrees φ = +/ degrees The combination of the lens and feeder array may be steered +/- 4 degrees in elevation and +/- 17 degrees in azimuth. The 3-level switching matrix can be switched with 1 us settling time and driven by the baseband processing unit and switched in synchronization with the TDM slot structure. 9 Nokia Solutions and Networks 2015

10 meters Experimental Scenarios Two major milestones are planned for experimental system - Milestone 1: Single-link (current phase) - Milestone 2: Multi-link Milestone 1 focuses on the basic challenges of acquiring and tracking a mobile subscriber with a narrow beam. - The BS is elevated several meters above ground with a few degrees for down-tilt. - The HPBW pattern is then projected onto ground to provide the coverage area for the experiment. - An example on the right shows one such HPBW projection for a BS height of 4 meters with an 8 degree down-tilt. - The coverage area on the ground forms a 30 m by 30 m area in which to conduct the experiment. The 3 degree HPBW represents an exceptionally challenging example for mmwave deployment. - Comparable array of patch antennas would ~ 32 by 32 (1024 elements) Expected HPBW will be much larger - 8 by 8 array will provide 13 degree HPBW - 16 by 16 array will provide 6.5 degree HPBW 10 Nokia Solutions and Networks h γ d min Coverage Area 27m by 34m θ θ d max AP Height = 4m, Downtilt = 8 degrees d min = h * cotan( γ + θ ) d max = h * cotan( γ - θ ) where γ = downtilt θ = maximum angle relative boresight meters

11 5G mmwave Outdoor AH campus Parameters Operating Frequency Bandwidth Modulation Antenna Beamwidth Antenna Steering Range Value 73 GHz 1 GHz Null Cyclic-Prefix Single Carrier 16 QAM Single Stream (SISO) 3 degrees 34 degrees Azimuth 8 degrees Elevation Outdoor 73 GHz very promising Maximum Range of 200meters 11 Nokia Solutions and Networks 2015

12 Play Video. 12 Nokia Solutions and Networks 2015

13 mmwave PoC 2GHz BW supporting 10 Gbps Peak rate New platform designed by NI to meet Nokia s 5G specification 74 GHz Receiver IF Downconverter Baseband Receiver Processing Data Parameters Value 74 GHz Receiver IF Downconverter Baseband Receiver 74 GHz Transmitter IF IF Upconverter Analog Baseband Baseband Transmitter Digital Baseband Operating Frequency ~74 GHz 74 GHz Transmitter IF Upconverter Baseband Transmitter Processing Data Bandwidth 2 GHz Peak Rate ~10 Gbps Modulation Null Cyclic-Prefix Single Carrier R=0.9, 16 QAM 2x2 MIMO Antenna Horn Antenna 10 Gbps peak rate using a prototype of NI s mmwave platform- demonstrated at 5G Brooklyn summit 13 Nokia Solutions and Networks 2015

14 Summary Experimental systems are critical to proving that higher frequencies can be used to achieve 5G objectives. The 73.5 GHz, 1 GHz BW experimental system with a steerable 28 db gain, 3 degree HPBW antenna can help prove many of the 5G concepts. Initial work on a single link system demonstrates the feasibility of acquiring and tracking user devices within the coverage area of base station using a narrow beam antenna 10 Gbps Peak Rate can be achieved using 2 GHz BW, 16 QAM and 2x2 MIMO Future work will include a multi link system will demonstrate how shadowing can be mitigated with base station diversity and rapidly rerouting around obstacles 14 Nokia Solutions and Networks 2015