Millimeter Wave Communication in 5G Wireless Networks By: Niloofar Bahadori Advisors: Dr. J.C. Kelly, Dr. B Kelley
Outline 5G communication Networks Why we need to move to higher frequencies? What are the characteristics of mmwave band communications? What are the challenges in using mmwave? What are the existing solutions? Application of mmwave in 5G framework. Future works
5G networks Source: Cisco Visual Networking Index (VNI) Mobile, 2016
5G networks Network Specification 5G 4G Peak Data Rate 10 Gb/s 100 Mb/s Mobile Data Volume 10 Tb/s/km " 10 Gb/s/km " E2E Latency 5 ms 25 ms Energy Efficiency 10% current consumption Number of Devices 1 M/km " 1 k/km " Mobility 500 km/h - Reliability 99.999% 99.99%
5G networks Existing solutions to improve network capacity: Increase Available BW Carrier Aggregation Cognitive Radio Spectrum Reuse D2D Communication Small Cell network Increase Spectral Efficiency Massive MIMO Spectrum Sharing Carrie #1: 20 MHz Carrie #2: 20 MHz Carrie #3: 20 MHz Carrie #4: 20 MHz Carrie #5: 20 MHz 100 MHz Even though some of these techniques can boost performance significantly, there is no clear roadmap on how to achieve the so far defined 5G performance targets.
U.S. Frequency Allocation The Radio Spectrum AM Broadcast TV Broadcast Cellular Communication Wi-Fi Equivalent Spectrum UWB 3.1 10.6 GHz, high data rate in PAN LMDS 28-30 GHz broadband, fixed wireless, point-tomultipoint for last mile application Source: U.S. Dept. of Commerce, NTIA Office of Spectrum Management
mmwave Communication Microwave band is referred to as Sweet spot due to its favorable propagation characteristics Low frequency bands have been almost used up It is difficult to find sufficient frequency bands in the microwave range for 5G improvements mmwave with high bandwidth can be a potential solution for 5G communication However, wave propagation in mmwave band has specific characteristics that should be considered in design of network architecture 3 GHz 57-64 164-200 300 GHz 54 GHz 99 GHz 99 GHz Cellular communication Oxygen molecule Absorption Water Absorption Candidate Bands 27.5 28.35 31.225 31.3 29.1 29.25 71-76 31.075 31.225 81-86 31.0 31.075 92-95 Potential available bandwidth
mmwave Characteristics Atmospheric Absorption Raindrops are roughly the same size as the radio wavelengths (millimeters) and therefore cause scattering of the radio signal The rain attenuation and molecular absorption characteristics of mmwave propagation limit the range of mmwave communications The rain attenuation and atmospheric absorption do not create significant additional path loss for cell sizes on the order of 200 m. Source: E-band technology. E-band Communications. [Online]. Available: http://www.e-band.com/index.php?id=86.
mmwave Characteristics High Propagation Loss and Sensitivity to Blockage mmwave communication suffers from high propagation loss PL f " Electromagnetic waves have weak ability to diffract around obstacles with a size significantly larger than the wavelength For example, blockage by a human attenuate the link budget by 20-30 db Only LOS communication is efficient. NLOS path LOS path Frequency Band (GHz) PLE- LOS PLE- NLOS Rain Attenuation @200 m (db) Oxygen Absorption @200 m (db) 28 1.8~1.9 4.5~4.6 0.9 0.04 38 1.2~2 2.7~3.8 1.4 0.03 60 2.23 4.19 2 3.2 73 2 2.45~2.69 2.4 0.09 F d = PL(d, ) + 10nlog 5, d d, Path-loss Exponent (PLE) NLOS suffer from high attenuation
mmwave Characteristics Directivity To combat severe propagation loss, high gain, directional antennas are employed at both transmitter and receiver Beamforming is a key enabling technology of mmwave communication With a small wavelength, electronically steerable antenna arrays can be realized as patterns of metal on circuit board 5 mm 16 antennas Integrated Circuit Directional antenna High gain at one direction very low gain in all other directions Source: F. Gutierrez, S. Agarwal, K. Parrish, and T.S. Rappaport, On-Chip Integrated Antenna Structures in CMOS for 60 GHz WPAN Systems, IEEE Journal on Selected Areas in Communications, vol. 27, no. 8, October 2009, pp. 1367 1377.
mmwave Characteristics Due to the size of antenna at mmwave, large array of antenna can be realized on both BS and device mmwave communication is inherently Directional The directivity of transmission enables concurrent transmissions with low multi user interference. 256 or more antennas at Base station Large array at mobile station, 4-32 antennas Challenges: MIMO cause higher power consumption Beamforming add overhead to system To make the transmitter and receiver direct their beams towards each other, the procedure of beam training is needed.
mmwave Characteristics Blockage mmwave are highly sensitive to blockage, Building blockage Body blockage Hand Blockage Design requirements: High density of infrastructure required to cover areas around buildings Need rapid switching between LOS and NLOS paths Array diversity on the handset Solutions Multiple path can be computed when one is blocked the remaining can be used. adds the complexity and overhead of the beamforming process Switch between different mode of communication Coordinating B.S B.S Building B.S
Applications Small-Cell Networks Massive densification of small-cells has been proposed to achieve the 10000 fold increase in network capacity. Smallcells deployed underlying the macrocells as WLANs or WPANs are a promising solution for the capacity enhancement in the 5G cellular networks. Increasing quality of link Less power consumption Decreasing latency Decreasing number of users assigned to each BS Improve network coverage area Device-to-Device Communication Device to Device Communication which is used to transfer data between devices without using the main infrastructure is one of the promising approaches in 5G networks Less power consumption Spectral efficiency With huge bandwidth, and low interference of mmwave band communication, can be used in small-cell access and backhaul networks, and direct communication among devices Source Niu, Yong, et al. "A survey of millimeter wave communications (mmwave) for 5G: opportunities and challenges." Wireless Networks 21.8 (2015): 2657-2676.
Summary Benefits: Higher bandwidth Small wavelength A large array of antenna can be realized in a small area Directivity Less MUI Challenges High propagation loss Absorption by rain and Oxygen molecule Blockage Sensitivity Needs model for blockage only LOS communication is efficient Beamforming add overhead to system Spectrum Large Array and Narrow Beam More spectrum Larger channel Reduce interference Spectrum reuse Ultra-fast Broadband Communication
Future Work In our proposed system model, D2D communication is enabled in a mmwave small-cell network. Network exploit mmwave and microwave resource to overcome the uncertainty of the mmwave environment caused by blockages. Our goal is to maximize number of satisfied applications scheduled at both frequency bands, based on their context information Application maximum tolerable Delay Size of the Data Channel State information Probability of LOS communication in mmwave band We are looking to find optimal solution for the optimization problem. A proper method to capture the uncertainty in mmwave LOS channel. mmwave Band Microwav e Band Small-cell BS underlying a macrocell One time slot n application are running simultaneously
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