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Sitzung des vorbereitenden Berufungsausschusses Kommunikationsnetze Mo. 19. Dezember 2005

Stand und zukünftige attraktive Arbeitsgebiete für den Lehrstuhl für Kommunikationsnetze Prof. Dr.-Ing. Bernhard Walke Kommunikationsnetze, RWTH Aachen walke@comnets.rwth-aachen.de. Sitzung des vorbereitenden Berufungsausschusses Kommunikationsnetze Mo. 19. Dezember 2005.

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Sitzung des vorbereitenden Berufungsausschusses Kommunikationsnetze Mo. 19. Dezember 2005

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  1. Stand und zukünftige attraktive Arbeitsgebiete für den Lehrstuhl für KommunikationsnetzeProf. Dr.-Ing. Bernhard WalkeKommunikationsnetze, RWTH Aachenwalke@comnets.rwth-aachen.de Sitzung des vorbereitenden Berufungsausschusses Kommunikationsnetze Mo. 19. Dezember 2005

  2. Wireless Technology Positioning Mobility / Range High Speed Vehicle VehicularRural FlashOFDM (802.20) Long Term 3G Evolution >2008 GSMGPRS VehicularUrban 3G/WCDMA Pedestrian Walk HSDPA EDGE Nomadic IEEE802.16e Fixed urban DECT Fixed Indoor WLAN(IEEE 802.11x) IEEE802.16a,d User data rate Personal Area bluetooth 100 Mbps 1 10 0.1

  3. Facts in Communication Networks and Protocols • Digital networks: Fully automated operation; IP Multimedia Sub-System (IMS) is hot issue for future research • Application layer data transmission rate • Core Network: excessivly high up to Tera bit/s • Wired local loop: ISDN (128 kbit/s) ->xDSL (6-20->1000 Mbit/s) • Wireless (WLAN) 5 Mbit/s -> 25 - 1000 Mbit/s) • Mobile communication: increasing from ISDN to 100 Mbit/s data rate • Increase in # of air interfaces competing -> multimode operation • Multi-homing: Use of multiple networks/services at same time • Radio resource control for wireless access networks: challenging • Resource Re-use Partitioning (interference avoidance) • Internet Protocol IPv6/8 to be understood/developed • Quality of Service responsive network design: challenge • Security & Privacy in comms. nets needs efficient solutions • Multi operator network co-operation is unsolved • Low cost mobile Internet access will need another decade to come • Next wireless/mobile generation will not be the final one

  4. Status and future research funds in ComNets‘ working domain: Network Design and Evaluation Research • „Broadband for All“ is a main goal in Europe: The research funding in large scale will continue over the next decade • Networks and Protocols Research • large amount of unsolved problems • ComNets (& MobNets) don‘t have severe academic competition in EU • Is key for the development & operation of distributed systems like power plant, automated factory, networked IT centre, process control plant, Airbus, in car/in home infrastructure, etc. • Current position of ComNets • EU funds expenditures ranking in 2004: RWTH=ComNets is rank 4 for all broadband disciplines, including PHY • Exceptionally strong BMBF funding: cooperation with many companies • About 1.450 ComNets research publications downloads per month • 3rd parties‘ funds appear available for at least another decade • ComNets students‘ profile perfectly fits the markets‘ needs • AWRC and UMIC cluster will need ComNets‘ current expertise • ComNets during the last 15 years had an average per year of • 7 peer reviewed journal articles, 35 peer reviewed conference papers • 43 Diploma theses • 3.4 Ph.D. theses 1 monography, 2 course books, all published by J. Wiley&Sons 2000+

  5. Download Statistics from 1/2001 to 10/2005 Total number of documents downloaded: 84.681  Average of 1435 downloads/month

  6. Paper Downloads by Country in 2005

  7. Einordnung ComNets/MobNets Technologien und Plattformen: Produktion/Entwicklung wandern tendenziell in Weltregionen mit geringen Lohnstückkosten aus. Prozessoren, Chips, Bauelemente, Platinen, USB Stick, usw. Internet, Mobilfunknetz, Glasfasernetz, Hochregallager, Automatisierte Fertigung, Fabrik, Airbus, Transrapid SMS, MMS, Google/Yahoo Navigation, Steuerungssoftwarefür komplexe Platt-formen und Systeme, Middleware & embedded Software PC,Server, Mobile Phone, Funkstrecke, Lokales Netz, Motor/Umformer, Transformator, Elektrofahrzeug ComNets/MobNets Research/Teaching Schaltungstechnik

  8. Multimedia Internet Service Platform

  9. ComNets Simulation Concepts 2 7 3 reading 1 6 4 5 packet call Layered structure: Link level…focussing the radio transmission System level…focussing the entire network behaviour Protocol level…focussing radio network protocols

  10. Current Work at ComNets I Channel CP Remove CP Append FFT IFFT Preamble Extract Preamble Insert Pilot Exractt Pilot Insert Channel Estimate Equal Demodulate Modulate Bit-Deintleave Bit-Intleave ByteDeintleave ByteIntleave Depuncture Puncture Conv. Decode Conv. Encode RS Decode RS Encode Descramble Scramble Sink Source Link Level Simulator of the OFDM transmission chain • SystemC based including C++ code • Detailled implementation of transmitter and receiver, including scrambler, RS/CC codec, interleaving, Modulation etc. • Channel: AWGN, SUI-1 und SUI-5 • IEEE 802.16a conformant Result: Channel model: Bit error rate = f(C/(N+I)) *SUI=Standford University Interim (for outdoors morpho)

  11. System Level Simulations • Stochastic event driven simulation for traffic performance evaluation of mobile radio networks based on implementation of • Radio network protocols (simplified) • Radio resource management strategies • Multi-cellular radio propagation environment • Multi-network / multi-system coexistence • Time-variant traffic and actual interference characteristics • Input from link-level simulation • ComNets’ expertise in entire network evaluation • ComNets tools are being used to drive standardisation of current and future wireless/mobile systems

  12. Radio access mode Duplex mode (FDD, TDD) Carrier frequencies (FDMA) Bandwidth Radio frame Time slot structure (TDMA) Spreading (CDMA) Radio resource management Thresholds Timer Target values Scenario description Services Type (voice, web, video) Characteristics Switching (circuit, packet) Priority Associated bearer service Evaluation Value ranges Resolution Station data Position, mobility Power range Protocol Level Simulation: Parameters

  13. Leistungsbewertung: Simulationsumgebung Lastgenerator stochastisches WAP Modell FTP HTTP SMTP Sprache Status AVL MM WTP TCP UDP Protokollmodell IP Instanz Basisstation Mobilstation LLC LLC MAC MAC Kanalmodell PHY PHY BU TU RA HT U m statistische Auswertung Histogramm Momente LRE PDF/CDF

  14. Netz-Architektur für GSM und den General Packet Radio Service (GPRS)

  15. GSM/GPRS Protokoll-Stapel

  16. Wartenetz Modell und Anwendung zur Modellierung eines Teilnehmer-Rechensystems • qij = Übergangsraten Matrix • stationsspezifische Bedienstrategie • Wartepuffer mit Prioritäten • Ergebnisse: P(Nj = nj); Wartezeitverteilung Stationsauslastung Durchsatz pro Auftragsklasse usw.

  17. Modellierung: Quelle für Sprachpakete über GPRS Modell der Verkehrsquelle Wartemodell mit stochastischen Ankunfts- und Bedienprozessen und Bedienstrategie

  18. Zustands-Übergangsdiagramm einer Markov Kette Zustand= aktive Sprachquellen N(t)=i, Pufferbelegung Übergänge aus den Zuständen N(t) = i. Aus N(t) sind (nach je 60 ms Übergänge zu N(t+1) = i+1, N(t+1) = i-1 und N(t+1) = i-3 möglich entsprechend den Übergangswahrscheinlichkeiten: Zustand: i,j i = aktive Sprachquellen j = Pakete im Puffer

  19. Mathematische Verkehrsleistungs-Analyse für GPRS Sprache Komplementäre Verteilungsfunktion der Warteschlangenlänge für verschiedene mittlere Sprach-Phasenlängen (mittlere Sprachpausenlänge =1 s) 95-Perzentil der Wartezeit von Sprachpaketen bei 10 Sprachquellen

  20. UMTS (2000): System Throughput & BER 1 No. of Mobile Stations = 10 No. of Mobile Stations = 30 No. of Mobile Stations = 60 0.9 No. of Mobile Stations = 100 No. of Mobile Stations = 150 No. of Mobile Stations = 200 0.8 No. of Mobile Stations = 250 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 0 0.2 0.4 0.6 0.8 1 Block Error Probability Block Error Rate at 256 kbit/s the BLER increases with increased Number of Stations, reducing throuphput accordingly. Maximum System Throughput for WWW traffic reached with 64 kbit/s DTCH

  21. Cell Capacity over Distance is Inverse to the Needs Range limitation of broadband APS by • high attenuation at high frequencies • limited transmission power (EIRP) • Unfavourable radio propagation conditions, e.g., in urban areas • Increased # of BS needed with increased carrier frequency to cover a given area • High CAPEX and OPEX • High cost/bit transmitted High capacity available close to AP only. Under constant user density: • Number of users increases with d • Cell capacity offered per area element differs from capacity requested by users • Future trend makes it more worse New Deployment Concepts required to • bring broadband to wider area than possible with one base station in current systems • Reduce the cost/bit transmitted by 2 to 3 orders of magnitude Sources: B. Walke, H. Wijaya, D.C. Schultz: The Application of Relays in Infrastructure-based Future Mobile Radio Network Deployment Concepts Submitted: VTC 2006 Spring, Melbourne, Australia T. Irnich, D.C. Schultz, R. Pabst, P. Wienert: Capacity of a Relaying Infrastructure for Broadband Radio Coverage of Urban Areas. Proceedings of the 10th WWRF meeting, New York, 10/2003

  22. Relay Enhanced Cells (REC)Using Fixed Relay Stations (FRS) Pros: • Relays in REC • don’t need a wired backbone access (lowers CAPEX and OPEX) • Full flexibility of relays (re-)positioning • Relays introduced to a cell can • enlarge the coverage area bbbbb(using antenna gain) • Increase capacity at cell border • balance the capacity/area element • reduce transmission power • increasing public acceptance • Reducing co-channel interference • (Movable) Relays support • fast network rollout, • outdoor to indoor service • Exploitation of macro-diversity (co-operative relaying) AP FRS • Cons: • In band relays consume radio resources • Out of band relays need multiple transceivers • Relays introduce extra delay Source: Walke, Bernhard; Wijaya, Harianto, Schultz, Daniel C.: The Application of Relays in Infrastructure-based Future Mobile Radio Network Deployment Concepts. Submitted: VTC 2006 Spring, Melbourne, Australia

  23. Cellular Multi-hop deployment in highly shadowed environment 2. 3. 1. Channel Group 1 Channel Group 2 AP Source: ComNets 2003 Line of Sight

  24. Capacity at Relay (FRS) with Antenna Gain 25 20 6.67 Mbit/s FRS 1 capacity (Mbit/s) 15 FRS 4 AP FRS 2 10 FRS 3 5 FRS sub-cell AP sub-cell 0 0 5 10 15 20 25 30 35 40 FRS receive antenna gain (dBi) P. Gupta and P. R. Kumar: The capacity of wireless networks. IEEE Transactions on Information Theory, 46(2):388 - 404, 2000: Multi-hop reduces capacity. Pabst, Ralf; Esseling, Norbert; Walke, Bernhard: Fixed Relays for Next Generation Wireless Systems - System Concept and Performance Evaluation. Journal of Communications and Networks, Vol.7, No. 2, p.p. 104-114, Korea, 06/2005: Spectrum capacity can be increased by multi-hop, if mesh hops are narrow beam based. • All AP capacity “transferred” to one FRS sub-cell • Capacity of FRS rises with antenna gain until highest PHY mode can be applied • Cost of relaying: 6.67 Mbit/s of AP capacity at 30 dBi gain (example: IEEE 802.11a PHY using a WiMax like MAC protocol)

  25. ComNets Vision of a Mobile Low Cost Internet Access: Relay-based Cellular Wireless Mobile Broadband System Relay Enhanced Cell Access Point 1. Hop Relay 2. Hop Relay Source: Walke, Bernhard; Pabst, Ralf; Schultz, Daniel C.: A Mobile Broadband System based on Fixed Wireless Routers. Proc. ICCT 2003 Intern. Conf. Comm. Techn., 04/2003

  26. Reuse shift parameter for a N = 12 Relay-Cell clusterand Cell Radius R

  27. Single-Hop and Relay Enhanced Cell Throughput compared (3 FRS) 346m single hop cell 200m central cell Area= Iso-throughput curves 200m Esseling, Norbert: Ein Relaiskonzept für das hochbitratige drahtlose lokale Netz HIPERLAN/2, ABMT 42, 1. Auflage Jul/2004, 307 Seiten, ISBN: 3-86130-169-5 www.comnets.rwth-aachen.de/Dissertati.178.0.html 200m

  28. End-to-End Throughput Downlinkalong y-Axis

  29. Single-Hop and Relay Enhanced Cell Throughput compared (3 FRS) 346m single hop cell 200m central cell Area= At 11,8 dbi Iso-throughput curves 200m Esseling, Norbert: Ein Relaiskonzept für das hoch bitratige drahtlose lokale Netz HIPERLAN/2, ABMT 42, 1. Auflage Jul/2004, 307 Seiten, ISBN: 3-86130-169-5 www.comnets.rwth-aachen.de/Dissertati.178.0.html 200m

  30. Multi-hop Relay TechnologiesR.Pabst, B. Walke, D.C. Schultz:Relay-Based Deployment Concepts for Wireless and Mobile Broadband Radio. In IEEE Communications Magazine, p.p. 80-89, New York, US, 09/2004 Time domain relay(FWR) Frequency domain relay Frequency domain relaywith pure forwarding

  31. Forwarding Concept: Case 2 FRS 1 FRS 4 AP FRS 2 FRS 3 TMP-MT TMP-MT • One carrier frequency • Exploitation of environment •  2 Groups of FRSs that can serve their MTs in parallel MTs served by FRS#1 MTs served by FRS#3 MTs served by FRS#2 MTs served by FRS#4 FRS#1served by AP FRS#3served by AP FRS#4served by AP MTs served by AP FRS#2served by AP TAP-FRS Time

  32. Coordination Across BSResource Partitioning MTs served by FRS#A3 MTs served by FRS#A4 MTs served by FRS#B1 MTs served by FRS#B3 MTs served by FRS#B2 MTs served by FRS#B4 MTs served by FRS#C1 MTs served by FRS#C3 MTs served by FRS#C2 MTs served by FRS#C4 TMP-MT TMP-MT Time Slot to Feed FRSs Time Slot Z Time Slot X Time Slot Y MTs served by FRS#A1 MTs served by FRS#A2 Cell Type A FRS#A1served by AP FRS#A2served by AP FRS#A3served by AP FRS#A4served by AP MTs served by AP A Cell Type B FRS#B1served by AP FRS#B2served by AP FRS#B3served by AP FRS#B4served by AP MTs served by AP B Cell Type C FRS#C1served by AP FRS#C2served by AP FRS#C3served by AP FRS#C4served by AP MTs served by AP C TAP-FRS Time

  33. Coordination Across BSs FRS 1 FRS 4 AP FRS 3 FRS 2 • Only one Carrier Freq. Required to cover the scenario • Distance between “co-channel” sub-cells: 460 m FRS 4 AP FRS 1 FRS 3 FRS 2 FRS 3 AP FRS 2 FRS 1 FRS 4 FRS 3 FRS 4 AP FRS 1 FRS 2 Cell Type A FRS 2 FRS 1 FRS 3 FRS 4 AP Cell Type B FRS 4 AP FRS 1 FRS 2 FRS 3 Cell Type C FRS 1 FRS 3 FRS 4 AP FRS 2

  34. Mesh Network applied to IEEE 802.11 WLAN:ComNets Proposal MN MN IEEE802.11e IEEE802.11e CFP CFP CP CP • Works under IEEE 802.11 PCF mode • MPs operate as PC (point coordinator) • Beacons with the format of IEEE 802.11’s from the PC inform nodes of the CFP (contention free period) and CP (contention period) • MN works during CFP, IEEE 802.11 on CP Note: Beacon Guard time • Coexistence of MN with IEEE 802.11e MN The guard times are fixed Source:Zhao, Rui; Walke, Bernhard; Hiertz, Guido: W-CHAMB (Wireless CHannel Oriented Ad-hoc Multi-hop Broadband): A new MAC for better support of Mesh networks with QoS, Contribution toIEEE 802.11 WLAN Working Group Session, September 2004, p. 5, Berlin, Federal Republic of Germany, 09/2004 ComNets 2004 And: Wijaya, Harianto: Broadband Multi-Hop Communication in Homogeneous and Heterogeneous Wireless Lan NetworksABMT 46, 1. Auflage Feb/2005, 237 Seiten, ISBN: 3-86130-175-X, available at: www.comnets.rwth-aachen.de/Dissertati.178.0.html

  35. Mesh Network (MN) and IEEE 802.16 combined.ComNets proposes dedicated mesh network protocol MN MN IEEE802.16 IEEE802.16 Periodic Periodic Frame specific Frame specific • Provides meshing of APs and Relays and MS access in the same channel within a Relay Enhanced Cell (REC) • Base Station/Relay Node are called MeshPoint (MP) • MN connects MPs in RECs and MPs of adjacent RECs using MAC-frame periodic slots • IEEE 802.16 MAC frame serves MSs on first hop to MP Note: Beacon Guard time Coexistence of MN with IEEE 802.16 MN The guard times are fixed Source: Mangold, S.; Habetha, J.; Choi, S.; Ngo, C.: Coexistence and interworking of IEEE 802.11a and ETSI BRAN HiperLAN/2 in multi-hop scenarios. In 3rd IEEE Workshop Wireless Local Area Networks, Boston, 09/2001

  36. Possible IEEE 802.16 WiMAX Mesh Solution • BSs connected by MN on separate frequency channel • IEEE 802.16 between BS and SSs or RNs (one-hop forwarding possible)

  37. Coexisting WLANs: The Game Model • Overlapping WLANs are represented by a player • Each player has a strategy to determine what action to select • An action specifies a behavior • The players optimize the payoff (i.e. outcome) of the game

  38. Basic Service Sets are modeled as players that attempt to optimize their outcomes The coexistence problem is modeled as a repeated, stage-based game WLAN Spectrum Coexistence Scenario: Two 802.11e QBSSs sharing one Channel QSTA: Quality Station HCF: Hybrid Coordinator Function

  39. Nash Equilibrium Definition: “No player can gain a higher payoff in deviating from Nash Equilibrium” • stable and thus predictable point of interaction player -i defecting stable point of interaction player i defecting

  40. Strategies in Multi Stage Games (I) • Strategies describe the alternatives a player has for an action within a Multi Stage Game • Consideration of interaction with decisions of influenced players • Strategies modeled as state machines (1) COOP (2) GRIM (3) RANDOM • Example: Dynamic trigger strategy TitForTat (TFT) – the player cooperates if the opponent cooperates and vice versa (4) TFT

  41. Strategies in Multi Stage Games (II) • Multi Stage Games of multiple strategies, evaluated in terms of observed throughput (Θ) and (TXOP) delay TFT versus various strategies RANDOM versus various strategies • TFT: Player’s behavior follows the opponent’s leading to predictable MSG outcomes  QoS guarantee • RANDOM: frequent fluctuation in behavior implies instable game course  unsatisfying QoS degradation

  42. ComNets Concept for a Flexible Protocol Stack • Protocols share a lot of commonalities, that can be exploited in an efficient multi-mode capable wireless system • Generic Protocol Stack as “toolbox of parameterizable protocol functions” • Generic part: Tradeoff of general usability vs. implementation effort

  43. WINNER Multi-Mode Protocol Architecture (2) management that is specifically optimized for the mode1and mode2 in use  probably more efficient Stack Management alternatively: (1) generic management more flexible

  44. Reference Structure of Layer or Sublayer (N) Layer Modes Convergence Manager ((N)-MCM): • Facilitates the structuring of an arbitrary layer into generic and specific parts • Responsible for composition and (re-)configuration • Controlled by the stack management  Optimization potential is marked up in questioning the necessity of indicated differences

  45. Realization of the Flexible Protocol Stack • Functionality of the Layers is composed from a toolbox of functional units • Mode-specificness can either be specific modules or specific configuration / parameterization of the stack, individual layers or even functional units • Reference Implementation for WINNER Layer 2 currently performed at ComNets

  46. Spectrum Requirement Estimation at a Glance Market info Calculation algorithm Radio technology info Future services Scenarios definition Capabilities Offered traffic Traffic distributionto Radio Access Techniques (RAT) & Radio Environments Availability/ Coverage Required Quality of Service (QoS) Capacity dimensioning Technical spectrum requirements Adjustments & weighting

  47. General Approach for Capacity Calculation • In packet based systems QoS constraints require certain amount of free capacity System Throughput Mean Delay PhysicalLayerThroughput MACLayerThroughput Delay Target RLCLayerThroughput Usable fraction of system capacity underload overload Tmax = Crlc System Load 100% System Load

  48. Packet-switched Capacity Calculation • Required system capacity calculated from M/G/1/FCFS/NONPRE queue (“head of the line priority queue“) • Throughput requirements per SC derived under steady state operation • To meet the delay requirement of a Traffic Class needs proper dimensioning of capacity C Parameters of the model: • λi : arrival rate of packets with priority i • βi(i) : i-th moment of service duration of packets with priority I • C: capacity searched for Highest priority Priority 1 λ1 β1, β1(2) Server Priority 2 λ2 C β2, β2(2) Priority N λN βN, βN(2) Lowest priority

  49. Aggregate Spectrum Requirement • Results shown above do not include last step of new methodology (i.e., accounting for multiple operators, guard bands, FSU, etc.) • Some parameters for PS capacity calculation have been reasonably chosen, other choice would have led to different results • Small difference resulting is more or less coincidence, since a number of effects partly compensate each other • The scenario considered is not a likely scenario to be looked at in spectrum requirement calculation in preparation for WRC-07 • Comparison shows that results are in line with earlier results • New methodology’s concepts and algorithms represent state of the art

  50. Communication Networks (Walke): “We do mostly layers 2..4” Broadband Wireless Transport Platforms Mesh Netwks. & Relaying for cellular Fixed and Mobile Networks Convergence IEEE 802.11/15/16/21 Standardization Wireless Networks & Interworking Transport Services & Protocols 4 Adaptive Protocol Stack Software Spectrum Co-existence Research Traffic Performance Evaluation (Theory of Large Systems) Radio Resource & Mobility 3 Control Location Based Services 3 Medium Access & Link Control 2 Protocols Smart Antenna Protocol 1-2 Support

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