UofT Wireless Lab A 5G Paradigm Based on Two-Tier Physical Network Architecture Elvino S. Sousa Jeffrey Skoll Professor in Computer Networks and Innovation University of Toronto Wireless Lab 1 IEEE Toronto 5G Summit 2015 (Nov 14/2015)
UofT Wireless Lab Cellular System Evolution • 1G, 2G, 3G, 4G, clear. 1 – Analog, 2 - digital voice, 3 - voice plus variable data, 4 LTE-Advanced (Internet access). 1978 – 2012, or about 8 years/generation • Computing: Similar approach to classification of generations (1G-4G, 1953 – 1982). • 5 th generation? ... Not clear and we could also loose interest in calling it a generation (at least from technology standpoint). • One difference: Terminology here driven by industry group and standards. • Currently we see the search is on for 5G, and it seems simultaneously for beyond 5G. 2 IEEE Toronto 5G Summit 2015 (Nov 14/2015)
UofT Wireless Lab Classification by Generations • Going forward it will be more like looking to the past, as opposed to 1-3G. • 4G to some extent was coined after the fact. • 4G defining features: OFDM on wider bandwidths, MIMO • But MIMO not widely implemented because of terminal constraint 3 IEEE Toronto 5G Summit 2015 (Nov 14/2015)
UofT Wireless Lab Key to Network Capacity • Goal of wireless systems is to provide not only sufficient user capacity (in terms of capability of modulation scheme) but also network capacity • Ultimately network capacity depends on More efficient physical layer, interference control Quantity of Spectrum Cell size (Small Cells) 4 IEEE Toronto 5G Summit 2015 (Nov 14/2015)
UofT Wireless Lab My Take on Recent History • My view of 4G (evolution to higher capacities beyond 3G) • 2003 white paper – “Autonomous infrastructure wireless networks – 4G is Here”. • 2007? – Femto cells • Later – “small cells”. • Reality: Data offloading - WiFi integrated into all smart phones 5 IEEE Toronto 5G Summit 2015 (Nov 14/2015)
UofT Wireless Lab Future Goal • Current data usage (typical plans) • In home Internet access: Typical plan 90 GB/month • Cellular typical plan: 3 GB/month • Ratio: 30:1, or one month to one day. • Goal: Make wireless access (“as accessible” as wired access, i.e. 1:1. 6 IEEE Toronto 5G Summit 2015 (Nov 14/2015)
UofT Wireless Lab 1000x Capacity • Common goal, referred to currently, is 1000x capacity • Not achievable with improvements in modulation and even spectrum allocation. • Solution: small cells • Problem: Infrastructure to deploy small cells may be costly. 7 IEEE Toronto 5G Summit 2015 (Nov 14/2015)
UofT Wireless Lab Some Architectural Approaches • Femtocells Use existing network connection points Business issues (private, public femtocell) Third party traffic on network connection point? • Small Cells • Larger than Femtocells • Infrastructure Cost • Cloud RAN Best for Intercell-Interference control Rigidity in expansion Organic growth at physical layer? Back-haul/Front-Haul Approaches 8 IEEE Toronto 5G Summit 2015 (Nov 14/2015)
UofT Wireless Lab Alternative to Small Cells • Increase the efficiency of existing cells sites. • Achieve large capacities by use of “large antennas” at the “terminal”. • Space division multiplexing at the “Terminal”. 9 IEEE Toronto 5G Summit 2015 (Nov 14/2015)
UofT Wireless Lab Two-Tier Networks • Primary Nodes ( P node ): Classical Base station with Large Antenna and Power Capability. • Secondary Nodes ( S node ): “Transceiver” with “large” capability for spatial processing. D1 – Distance to P node. • User Equipment ( UE ). Small, with usual antenna and power limitations. D2 – Distance to S node. • D1 >> D2. • Tier 1 spectrum more precious depending on ratio D1/D2. 10 IEEE Toronto 5G Summit 2015 (Nov 14/2015)
UofT Wireless Lab Two-Tier Network Architecture Tier 1 P node Tier 2 S node 11 IEEE Toronto 5G Summit 2015 (Nov 14/2015)
UofT Wireless Lab Spectrum • Tier 1 – Licensed • Tier 2 – Licensed or Unlicensed? 12 IEEE Toronto 5G Summit 2015 (Nov 14/2015)
UofT Wireless Lab Physical Layers • Tier 1 – Cellular Technologies, e.g. 4G, 5G, evolution. Key: Interference Management • Tier 2 – Cellular Technologies, WiFi and evolutions, LTE-U, Bluetooth, other technologies 13 IEEE Toronto 5G Summit 2015 (Nov 14/2015)
UofT Wireless Lab S Node Sharing Options • Dedicated to a user terminal. – Active vs. Passive • Shared among a user account. • Shared among public users. 14 IEEE Toronto 5G Summit 2015 (Nov 14/2015)
UofT Wireless Lab S Node Design – Use Cases • Generic Nodes based on “Antenna Size”, and or configurations, i.e. antenna design • Fixed nodes for home? • Fixed nodes for commercial applications? • Nodes for vehicle (generic or specific to vehicle model). • Notes for buses, street cars, trains? • Portable organically deployed nodes, e.g. construction site. 15 IEEE Toronto 5G Summit 2015 (Nov 14/2015)
UofT Wireless Lab Role for Millimeter Wave Spectrum • Use mmWave in Tier 1 for Line-of-sight scenarios (use cases). • S Node: Capability for both microWave and mmWave on Tier 1 interface, self- configurable (mmWave, microWave) to handle blocked propagation cases. 16 IEEE Toronto 5G Summit 2015 (Nov 14/2015)
UofT Wireless Lab Public/Private Networks • Tier 1 P nodes – Public – Slower to deploy • Tier 2 S nodes – Private or Public? – Organic deployment 17 IEEE Toronto 5G Summit 2015 (Nov 14/2015)
UofT Wireless Lab Physical Layer Design • Tier 1 – S node – S node fixed • Easy channel estimation (reference signals) • Easier Power Control • Easier resource allocation and antenna adaptation – S node mobile (e.g. vehicle, or bus) • Predicable motion • Advantages in channel estimation, power control, antenna adaptation, resource allocation • Tier 2 - UE – Current approaches in smartphones (cellular & WiFi), other technologies 18 IEEE Toronto 5G Summit 2015 (Nov 14/2015)
UofT Wireless Lab S Node Antenna Design • Massive Beam-forming • Massive MIMO • Other spatially efficient technologies – e.g. for mmWave. 19 IEEE Toronto 5G Summit 2015 (Nov 14/2015)
UofT Wireless Lab Tier 1 Signal Design • New Strategy for pilot signal design • LTE pilot approach does not scale for large MIMO. When one antenna transmits, all the others are off! • Signal design based on class of use cases. • Different modes depending on use case and S node class. 20 IEEE Toronto 5G Summit 2015 (Nov 14/2015)
UofT Wireless Lab Optimum Ratio of D2 to D1 • UE has two options – Connect directly to P node – Connect through S node • Strategy for selection of P node or S node – Distance/power consideration – Spectral efficiency (need D2 not too large) – Traffic Load at P node. – Latency issues? 21 IEEE Toronto 5G Summit 2015 (Nov 14/2015)
UofT Wireless Lab Network Optimization: Self- Organizing S Node • First time when the S node is turned on, it goes into initialization mode and self-configuration. • Network environment learning • Optimization of Tier 1: P node to S node link. • In the initialization mode the S node senses the spectrum and chooses a band with minimum interference and if necessary it communicates with nearby co-channel S nodes to perform self- configuration. 22 IEEE Toronto 5G Summit 2015 (Nov 14/2015)
UofT Wireless Lab Indoor Use Case? • Indoor cells vs. Coverage from the outside. • Two systems (macro/femto) or continuum? • Do we isolate indoors? • Could even modify construction • Advantage of isolating indoors vs. Flexibility of capturing external signals 23 IEEE Toronto 5G Summit 2015 (Nov 14/2015)
UofT Wireless Lab Vehicular Use Case? • Vehicular movement is regular. • Room for better smart antennas. • Many possibilities here for a new system architecture. Antenna custom design to model. • Initial benefits: (hot spot at night?, one wireless account?). Other better benefits . 24 IEEE Toronto 5G Summit 2015 (Nov 14/2015)
UofT Wireless Lab Vehicular Scenarios • Vehicle in the city – high level MIMO link to P node or other highly directional antenna • Vehicle at home – user at home, evening and night • Vehicle in the country side – link range extension • Vehicle in the highway (remote area) – reduce density of base stations required to cover highways. 25 IEEE Toronto 5G Summit 2015 (Nov 14/2015)
UofT Wireless Lab Summary • Two approaches for large cellular network capacities – Small Cells • Need the associated infrastructure • Ultimately achieves the highest capacities – Two-Tiering • Organic deployment of S nodes • Antenna offloading • Public/private • S node public sharing vs. private • Tier 2 technologies? 26 IEEE Toronto 5G Summit 2015 (Nov 14/2015)
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