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Deployment Cost Efficiency in Broadband Delivery with Fixed Wireless Relays

Deployment Cost Efficiency in Broadband Delivery with Fixed Wireless Relays. Licentiate Proposal by Bogdan Timus. Overview. Motivation Previous work Problem formulation Study approach Parallel relaying – preliminary results Channel scheduling – preliminary results

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Deployment Cost Efficiency in Broadband Delivery with Fixed Wireless Relays

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  1. Deployment Cost Efficiency in Broadband Delivery with Fixed Wireless Relays Licentiate Proposal by Bogdan Timus Bogdan Timus, 2006.07.30 ICWMC Bucharest Romania

  2. Overview • Motivation • Previous work • Problem formulation • Study approach • Parallel relaying – preliminary results • Channel scheduling – preliminary results • Preliminary and expected conclusions • Work left to be done • Time schedule Bogdan Timus, 2006.07.30 ICWMC Bucharest Romania

  3. Why … … wireless broadband access (WBA)? • Success of the internet • Mobility expected; cables disliked • Everybody talks about it! • Customary assumption in many studies • What is that? (bit-rate) • How is it consumed? (mobile, nomadic, fixed) … fixed cellular-relay architecture? • Claim: “cellular not affordable for WBA” • Claim: “lower cost with relays than with cellular” • Research hypes: ad-hoc relaying, cooperative relaying Bogdan Timus, 2006.07.30 ICWMC Bucharest Romania

  4. The answers … • depend on many non-technical aspects • are too tedious to answer exhaustively “One million euro” questions: • Is “relaying” a good business case? • Under which circumstances? • What fundamental fact makes relaying better than direct connection? Bogdan Timus, 2006.07.30 ICWMC Bucharest Romania

  5. Sensitivity analysis Problem formulation 1. Cellular-relaying (large scale): same service, lower cost than purely cellular architecture?” 2a.Parallel relaying: how much better than selection diversity (routing)? 2b. Cross-layer optim: how much is the best? 3. How much we gain/loose by: antenna height and gain, position planning, etc.? Bogdan Timus, 2006.07.30 ICWMC Bucharest Romania

  6. Study approach (1/4) • Analyze several study cases • Large scale usage of relays • Intuitive (expected) relay gains • Avoid niche-applications • Study the basic aspects with simple models • One relay • Time-invariant, flat channel • Simple propagation • No interference • Study the more advanced aspects • Sensitivity to relaying schemes • Sensitivity to deployment, unit characteristics, propagation, etc. • Interference handling (scheduling) Bogdan Timus, 2006.07.30 ICWMC Bucharest Romania

  7. Performance measure Study approach (2/4) General scenario and assumptions: • Greenfield operator • All built at once • Build for coverage (95%, outdoors) • Minimum bit-rate (input parameter) • Focus: last mile infrastructure cost per km2 Bogdan Timus, 2006.07.30 ICWMC Bucharest Romania

  8. Local access points (indoor to outdoor) WAN – purely cellular Cellular-relaying architecture Fixed relays Greenfield op. Incumbent op. Coverage Relaying terminals Capacity Study approach (3/4) Research context Wireless backhaul rural hotspots Wide area uniform traffic Indoor coverage urban Research area Bogdan Timus, 2006.07.30 ICWMC Bucharest Romania

  9. Study approach (4/4) Link budget (parallel relaying) • Basic understanding • Is relaying good enough? • One-relay amplify-and-forward • Random deployment • Single-slope propagation • 2. Better with more complex schemes? • Selection versus combining diversity • 3. Better in other environments? • Urban propagation • Below and over rooftop deployment • Power sensitivity, UL/DL, etc. • 4. How much better with planning? • Random versus planning by pruning Bogdan Timus, 2006.07.30 ICWMC Bucharest Romania

  10. Study approach (4/4) Link budget (parallel relaying) Resource allocation (STDMA) • Basic understanding • Is relaying good enough? • One-relay amplify-and-forward • Random deployment • Single-slope propagation • Basic understanding • Is cell-based allocation enough? • TDMA per cell • Regular deployment • Single-slope propagation • 2. Better with more complex schemes? • Selection versus combining diversity • 2. Does heuristic STDMA help? • Simple routing • Centralized, heuristic STDMA • Power, rate adaptation, etc. • 3. Better in other environments? • Urban propagation • Below and over rooftop deployment • Power sensitivity, UL/DL, etc. • 3. Does optimal STDMA help? • Simple routing • Ideal centralized algo • Power, rate selection, schedule. • 4. How much better with planning? • Random versus planning by pruning Bogdan Timus, 2006.07.30 ICWMC Bucharest Romania

  11. Direct transmission freq freq time time Relaying branch Direct transmission Parallel relaying (1/3) Specific assumptions • High peak rate, low average • No interference • Non ergodic channels • Short messages, low delay • Time invariant channels • Amplify and Forward (AF) • Ideal preamble Bogdan Timus, 2006.07.30 ICWMC Bucharest Romania

  12. Parallel relaying (2/3) The basic dilemma Bogdan Timus, 2006.07.30 ICWMC Bucharest Romania

  13. Not quite • ideal preamble + non ergodic • transmission diversity gains • Better with more complex schemes? • Selection diversity (routing) • Relaying SIMO • Relaying MIMO Yes,if • Better in other environments? • Urban propagation • Below and over rooftop deployment • Power sensitivity, UL/DL, etc. • Yes (as expected) • UL: power asymmetry • If micro base • NO • If macro urban • Roof vs street • How much better with planning? • Random versus planning by pruning 2-3 times Parallel relaying(3/3) Preliminary results: • Is relaying good enough? • Single slope, random relays, SIMO Bogdan Timus, 2006.07.30 ICWMC Bucharest Romania

  14. Tight channel reuse (1/2) Specific assumptions • Long messages • Time invariant channels • Decode and Forward (DF) • User rate fairness Intermediary goal Bogdan Timus, 2006.07.30 ICWMC Bucharest Romania

  15. Does heuristic STDMA help? • Simple routing • Centralized, heuristic STDMA • Power, rate adaptation, etc. Yes,if Tight channel reuse (2/2) • Is cell-based allocation enough? • TDMA per cell • Regular deployment • Single-slope propagation No, if fading > 2 dB • How much does optimal STDMA help? • Simple routing • Ideal centralized algo • Power, rate selection, schedule. Bogdan Timus, 2006.07.30 ICWMC Bucharest Romania

  16. Preliminary and expected conclusions • Unlikely for a large scale usage of relays to bring large cost savings. • Relay planning is useful if the planning costs are small compared with the site and equipment cost. • Traditional network planning and deployment aspects are more important that the actual relaying techniques • MAC for tight resource reuse is essential Bogdan Timus, 2006.07.30 ICWMC Bucharest Romania

  17. Original contributions • A method to convert technical enhancements brought by relaying techniques into (financial) cost terms • … Or a way to tell if better is good enough • A framework (models and methods) in which to evaluate different relaying techniques from a techno-economical point of view. • … Or how to compare apples and oranges. • A framework (the same) in which to analyze the cost-performance trade-off of algorithms, site design options, etc. (e.g. site planning, antenna height and gain, power). Bogdan Timus, 2006.07.30 ICWMC Bucharest Romania

  18. Preliminary time plan • Parallel relaying data w.38 • Final results UL, • Start simulations planning • STDMA data w.39 • Preliminary results processed • Writing on the thesis w.40-41 • Week 40: Chap.1 (Intro), chap 2. (models) • Week 41: chap. 3 (parallel), chap 4. (STDMA) • First draft 20 oct (w.42) • Contact with the opponent established 1 nov. • Defense ??? Bogdan Timus, 2006.07.30 ICWMC Bucharest Romania

  19. Thank you Bogdan Timus, 2006.07.30 ICWMC Bucharest Romania

  20. Coverage Costs with an Amplify-and-Forward Relaying Scheme ICT, Madeira, Portugal, 2006,9-12 May Bogdan Timus, 2006.07.30 ICWMC Bucharest Romania

  21. A Coverage Analysis of Amplify-and-Forward Relaying Schemes in Outdoor Urban Environment ICWMC, Bucharest, Romania, 2006, 29-31 July Bogdan Timus, 2006.07.30 ICWMC Bucharest Romania

  22. Coverage Costs of One Amplify-and-Forward Relaying in Outdoors Urban Environment PIMRC, Helsinki, Finland, 2006, 11-14 September Bogdan Timus, 2006.07.30 ICWMC Bucharest Romania

  23. Planned versus Ad-hoc Deployment of Fixed Amplify-and-Forward Relays AdHoc06, Johannesberg, Sweden, 2006, 3-4 May Bogdan Timus, 2006.07.30 ICWMC Bucharest Romania

  24. Break-Even Costs in a Cellular Multihop System with Fixed Relays WPMC, Ålborg, Denmark, 2005, September Bogdan Timus, 2006.07.30 ICWMC Bucharest Romania

  25. Previous work Fundamental relaying theory • Cover • Kumar, Gupta Parallel relaying Channel scheduling Recent projects • BRAIN, MIND - relaying concepts and architectures • AWSI / LCI - cost and affordability • WINNER - relaying in 5 GHz band • WiMAX forum Bogdan Timus, 2006.07.30 ICWMC Bucharest Romania

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