Presentation on theme: "Multi-tier Topologies in Future Wireless Broadband Networks"— Presentation transcript:
1 Multi-tier Topologies in Future Wireless Broadband Networks IEEE Presentation Submission Template (Rev. 9)Document Number:IEEE C /0004Date Submitted:Source:Kerstin Johnsson, Shilpa Talwar, Nageen Himayat, S. YehIntel CorporationVenue:San Diego, CA, USABase Contribution:NonePurpose:For discussion in the Project Planning AdhocNotice:This document does not represent the agreed views of the IEEE Working Group or any of its subgroups. It represents only the views of the participants listed in the “Source(s)” field above. It is offered as a basis for discussion. It is not binding on the contributor(s), who reserve(s) the right to add, amend or withdraw material contained herein.Release:The contributor grants a free, irrevocable license to the IEEE to incorporate material contained in this contribution, and any modifications thereof, in the creation of an IEEE Standards publication; to copyright in the IEEE’s name any IEEE Standards publication even though it may include portions of this contribution; and at the IEEE’s sole discretion to permit others to reproduce in whole or in part the resulting IEEE Standards publication. The contributor also acknowledges and accepts that this contribution may be made public by IEEEPatent Policy:The contributor is familiar with the IEEE-SA Patent Policy and Procedures:< and <Further information is located at < and < >.
2 Trend towards personal and mobile devices Device PerspectiveMacro- BS (1km)Micro- BS (500m)Pico-BS (300m)Communications evolution lags computingFemto-AP(100m)Soft-AP(WiFi/ WiMax)MID(Mobile Hotspot/ Mobile PAN)PersonalizationMobilityMainframeWe started this process by looking at this area through the view of the 2010 user – here is the question we decided that user would face- As a likely technology use leader you may well already seeing the beginnings of thisLaptopNetbookDesktopTrend towards personal and mobile devices
3 Multi-tier Networks Spectrum Utilization Overlay multiple tiers of cells, macro/pico/femto, potentially sharing common spectrumClient can be viewed as center of additional tier (see client co-op)Tiers can be heterogeneous (WiFi)WiFi-AP(Offload macro-BS)Macro-BSFemto-AP(Indoor coverage & offload macro-BS)Pico-BS(Areal capacity)Client CooperationWired backhaulRelayWireless backhaulCoverage Hole
4 Advantages of Multi-tier Networks Significant gains in Areal Capacity through aggressive spectrum reuse and use of unlicensed bandsCost structure of smaller cells (Pico & Femto) is more favorableIndoor coverage is improved through low cost femto-cellSmall Cell ScenarioAreal capacity gain* from spectral efficiency improvement and increase spatial reuseSparse FAP deploymentDense FAP deploymentPublicPrivateFAP Tx Power0 dBm3415210 dBm363814415420 dBm3539135Capacity gain comes from:Spectral Efficiency ImprovementSpatial reuse of frequencyEx: 150x ~ 1.5(average SE gain) x 100 FAP’s*Areal capacity gain = (System Capacity with Femto-APs deployed) / (System Capacity without Femto-APs)Source: Johansson at al, ‘A Methodology for Estimating Cost and Performance of Heterogeneous Wireless Access Networks’, PIMRC’07.Significant savings in Cost per Bit from Multi-tier Networks
5 Challenge: Inter-tier Interference Need to protect control & data signals from inter-tier interferenceFemto-cells cause significant INT to macro-users and other femto-cellsPower control improves interference only slightlyMacro and femto on diff carriers prevents INT, but lowers throughput and significantly decreases trunking efficiency and RRM flexibilitySimple FFR on macro & femto reduces INT; but more sophisticated FFR and/or Femto-Free Zones (FFZ) required to fully protect macro-usersTx SchemeMax FAP Tx PwrOutdoor Outage (%)Indoor Outage (%)50% Outdoor rate (Mbps)50% Indoor rate (Mbps)No FAP2531.80.060.05Co-channel (10MHz)-10dBm18.104.22.168dBm22.214.171.124Tx SchemeOutdoor Outage (%)Indoor Outage (%)50% Outdoor rate (Mbps)50% Indoor rate (Mbps)FFR + NO FAP on 10 MHz3.017.00.070.03FFR Macro on 5 MHz, Femto on diff 5 MHz0.20.0610.7FFR + FFZ + 0dBm FAP power on 10 MHz0.511.3Interference reduction for Control Signals remains unresolved
6 Challenge: MobilityHandovers across small cells can be highly inefficientIntelligent handover mechanisms required to determine when intra- or inter-tier handover is beneficialExample 1: If a macro-user moves into the coverage area of a high data rate femto-cell, the first instinct is to handover. However, the benefit/cost of handover depends on the user’s mobility.Example 2: Although a femto-user may have better channel quality to the macro-ABS, it may benefit from remaining associated to the femto-ABS if the femto load is significantly less.handoff
7 Challenge: Network Management Scalability is key feature in multi-tier networksSelf-organization and management across tiers will be crucial to maintaining low OPEX and quick network responseMay facilitate network management to merge network elementsNeed to consider new network elementsExample: what is the optimum middle ground between consumer owned & deployed private femto-AP (low cost) versus operator owned & deployed public pico-BS?
8 Summary & Recommendations Multi-tier networks promise significant improvements in total network, average user, and indoor user throughputHowever, to realize these gains, next generation standard should develop protocols to control interference across network tiers, perform handover intelligently, and manage network elements efficiently.