A O T. Heterogeneous Networks and Mobility User Perspective. Agententechnologien in der Telekommunikation Sommersemester Lecture

Transcription

1 Heterogeneous Networks and Mobility User Perspective Agententechnologien in der Telekommunikation Sommersemester 2009 Thomas Geithner Lecture Agententechnologien in betrieblichen Anwendungen und der Telekommunikation

2 Structure of the Lecture Scenarios General Problems Some Problem Details Future Improvements / IEEE Application Example: StrokeNet StrokeNet Solution Measurements Side Effects during Network Handovers Agententechnologien in der Telekommunikation - 2

3 Different Scenarios Mobility High mobile environments (e.g. car) semi-mobile / nomadic usage Applications Real-time and critical (e.g. telemedicine, industrial applications) Interactive applications (e.g. WWW) Background applications (e.g. system update service) Hardware environment Small device (e.g. Smart Phone/PDA/Handheld) Notebook Vehicular environment (car PC) Ship / Train / Aircraft Agententechnologien in der Telekommunikation - 3

4 Different Scenarios (2) Access technologies PAN / CAN: Bluedooth, Zigbee, IrDA LAN: WLAN (WiFi) MAN: WiMAX, Flash-OFDM (Flarion) WAN: 3G (UMTS, HSPA) GAN: Satellite (Inmarsat BGAN) Agententechnologien in der Telekommunikation - 4

5 Scenario - Example #1: Smartphone / PDA Applications: VoIP / Video, , WWW Access technologies: 3G + WiFi Low energy resources #2: StrokeNet Telemedicine in ambulance cars Applications: Videoconference (high quality, critical) Technologies: 3G + Flash-OFDM High energy resources Agententechnologien in der Telekommunikation - 5

6 General Problems Network detection NIC needs to be active Example #1: WiFi needs to be active How to detect an alternative network while a connection is active? Depends on technology Network subscription Networks needs to be preconfigured WiFi: al lot of different authentication methods, access data for each network (Key, Password, Certificate) 3G: SIM card (Multi-SIM solutions) Usually, contract with provider(s) required Quality evaluation of connected and unconnected networks Agententechnologien in der Telekommunikation - 6

7 General Problems (2) Network selection Decision strategy can depend on many parameters Handover process Seamless handover? Fast intra-technology or inter-technology handover Make-before-Break scenarios Mobility solution (e.g. MIPv4/v6, SIP etc.) Possibly, connection interruption not avoidable (e.g. WiFi WiFi on the same NIC) Agententechnologien in der Telekommunikation - 7

8 General Problems (3) Quality of Service Different network capabilities, depending on technology and operator support Technology and provider independent solutions? Resource management in conjunction with handover process ( Make-before-Break for resource allocation) Agententechnologien in der Telekommunikation - 8

9 Problem: Quality Evaluation Quality parameters: bandwidth, delay, jitter, loss rate Depends on many factors Signal strength and noise level SNR, related to channel coding Radio propagation and channel multiplexing Moving speed Network interferences (e.g. different WiFi networks on the same channel) Collisions (e.g. in WiFi hidden node problem ) Network load Agententechnologien in der Telekommunikation - 9

10 Problem: Quality Evaluation (2) Only some parameters can be evaluated without established connection (e.g. SNR) Measurement on different network layers Physical layer: SNR, bit error rate MAC layer: L2 packet loss (only on the link) Network layer: L3 packet loss (including whole network), delay jitter Quality can vary very fast Measurement interval? Detailed quality evaluation can be expensive (processing power, energy consumption) Agententechnologien in der Telekommunikation - 10

11 Problem: Handover Decision Goal: estimate link loss or quality decrease before application is affected Only possible within scenario limitations How fast are the expected changes What applications are used Which access networks are available Avoid high network switch frequency but aspire fast reaction In some scenarios, additional parameters can be used Current position and geographical database Detailed history and self-learning decision algorithm Agententechnologien in der Telekommunikation - 11

12 Problem: Handover Process Goal: seamless handover Strategies Fast intra-technology handover (e.g. switching between two cells in a 3G network) Make-before-Break Requires al least two simultaneous connections Mostly, access technology independent mobility solution (e.g. MIPv4/v6, SIP) In some cases, seamless handover not possible E.g. switching between two WiFi networks (general case) Agententechnologien in der Telekommunikation - 12

13 Handover Break-before-Make MN WLAN1 WLAN2 DHCP2 HA Association Disconnect Authentication Dataflow interrupted DHCP MIP Agententechnologien in der Telekommunikation - 13

14 Handover Make-before-Break MN WLAN1 WLAN2 DHCP2 HA Association Authentication DHCP MIP Disconnect No dataflow interruption, but side effects possible Agententechnologien in der Telekommunikation - 14

15 Example: Mobile IP Mobile Node Access Link Mobile IP Tunnel (active) Mobile IP Tunnel (inactive) Access Network 2 Access Network /24 Internet Home Agent Agententechnologien in der Telekommunikation - 15

16 Example: Mobile IP without Route Optimization Mobile Node Access Network 2 Foreign Node Access Link Mobile IP Tunnel (active) Mobile IP Tunnel (inactive) Data Flow Access Network 1 Internet /24 Home Agent Agententechnologien in der Telekommunikation - 16

17 Example: Mobile IPv6 with Route Optimization Mobile Node Access Network 2 Foreign Node Access Link Mobile IP Tunnel (active) Mobile IP Tunnel (inactive) Data Flow Access Network 1 Internet /24 Home Agent Agententechnologien in der Telekommunikation - 17

18 Problem: Quality of Service Different capabilities in access technologies Resource reservation Packet prioritization (traffic classes) Not implemented by all operators No standardized way for management In IP networks, no general end-to-end resource reservation possible No standard protocol or interface to allocate network resources in the access network No information about network utilization available Agententechnologien in der Telekommunikation - 18

19 Future Improvements Distributing / exchanging additional information Other available networks (distributed from access networks) Costs and roaming partners Network capabilities (bandwidth, QoS, security) User situation (provided from user to operator) Other available networks (users view) Current link quality Notification on events (e.g. link going down, new network found etc.) Combining operator perspective and user perspective Network initiated handover (NIH) and mobile initiated handover (MIH) possible Agententechnologien in der Telekommunikation - 19

20 Future Improvements (2) Upcoming standard: IEEE Media Independent Handover Services Abstract model for handover related messages Covers local and remote communication Independent of network technology, but focus in 802.X and 3G networks Current state: draft Alternative Standard: RFC 5184 Unified Layer 2 (L2) Abstractions for Layer 3 (L3)-Driven Fast Handover Similar goals as IEEE Simpler model Current state: experimental Agententechnologien in der Telekommunikation - 20

21 IEEE Layers Upper layer: handover decision and mobility management MIH Function Lower layers: interaction with network technologies Interaction Information Service: distribute general information Command Service: commands from upper layers Event Service: notifications from lower layers image source: IEEE P802.21/D05.00 Agententechnologien in der Telekommunikation - 21

22 IEEE (2) MIH message MIH frame format TLV data encapsulation Hierarchical structure Message transport Generic encapsulation (ethernet frame) Special L2 encapsulations, e.g. into WLAN beacons (for information service) L3 encapsulation (e.g. IP), not covered by standard image source: IEEE P802.21/D05.00 Agententechnologien in der Telekommunikation - 22

23 IEEE SAPs SAPs (service access points) MIH SAP: local communication to higher layers MIH_LINK SAP: local communication to lower layers MIH_NMS SAP: local communication for management functions MIH_NET SAP: remote communication image source: IEEE P802.21/D05.00 Agententechnologien in der Telekommunikation - 23

24 IEEE Events MIH Events (examples) Link Events: Link_Up, Link_Down, Link_Going_Down, Link_Detected, Link_Parameter_Report MIH Events: MIH_Link_Up, MIH_Link_Down, MIH_Link_Going_Down, MIH_Link_Detected, MIH_Link_Parameter_Report image source: IEEE P802.21/D05.00 Agententechnologien in der Telekommunikation - 24

25 IEEE Event Subscription image source: IEEE P802.21/D05.00 Agententechnologien in der Telekommunikation - 25

26 IEEE Commands MIH Commands (examples) Link Commands: Link_Event_Subscribe, Link_Capability_Discover, Link_Configure_Thresholds, Link_Get_Parameter, Link_Action MIH Commands: MIH_Get_Link_Parameter, MIH_Configure_Link, MIH_Net_HO_Candidate_Query, MIH_Net_HO_Commit, MIH_NM_HO_Complete image source: IEEE P802.21/D05.00 Agententechnologien in der Telekommunikation - 26

27 IEEE Command Sequence Agententechnologien in der Telekommunikation - 27 image source: IEEE P802.21/D05.00

28 IEEE Example Messge image source: IEEE P802.21/D05.00 Agententechnologien in der Telekommunikation - 28

29 IEEE Example MIH image source: IEEE P802.21/D05.00 Agententechnologien in der Telekommunikation - 29

30 IEEE Example NIH image source: IEEE P802.21/D05.00 Agententechnologien in der Telekommunikation - 30

31 Application Example StrokeNet Project goal: remote diagnosis support for potential stroke patients Technical solution Video conference system (high quality) H.264 with 192 kbit/s (incl. audio) UMTS/HSDPA and Flash-OFDM connection Mobile IPv4 Agententechnologien in der Telekommunikation - 31

32 Application Example StrokeNet Robust base system PC/104 based car PC Power supply 8-30V Power consumption 8-12W No moving parts Read-only file system Access technologies UMTS/HSDPA (max. 384 kbit/s upstream) Flash-OFDM (max. ~600 kbit/s upstream) Agententechnologien in der Telekommunikation - 32

33 Application Example StrokeNet Mobility Management Modular design Abstract interfaces (XML and UDP/TCP) Independent modules for link handling Establishing connection Link monitoring Additional components GPS Mapping Server Status GUI Additional functionality VPN Network monitoring (SNMP) Agententechnologien in der Telekommunikation - 33

34 Application Example StrokeNet Decision Process Every CM evaluates link state and quality Link state Signal strength Ping packets Information send to DE If necessary, DE selects new access network and triggers handover Agententechnologien in der Telekommunikation - 34

35 Application Example StrokeNet MN DE FOFDM UMTS MIPv4 HA signal strength low decision process trigger handover to UMTS binding update binding acknowledge handover to UMTS performed Agententechnologien in der Telekommunikation - 35

36 Measurements StrokeNet Handover performance measurements UDP traffic generator between MN and test host (HA LAN) 200 kbit/s one packet every 40 ms Forced handover every 15 s Packet sniffer (tcpdump) + packet timestamps Time synchronization between test host and MN (<1ms) NTP over LAN (separate connection for time synchronization required) GPS (in future), needs system adaption Agententechnologien in der Telekommunikation - 36

37 Measurements Throughput Agententechnologien in der Telekommunikation - 37

38 Measurements Interarrival Time Agententechnologien in der Telekommunikation - 38

39 Measurements One Way Delay Agententechnologien in der Telekommunikation - 39

40 Measurements Interarrival Time during Handover Agententechnologien in der Telekommunikation - 40

41 Measurements Street Test Agententechnologien in der Telekommunikation - 41

42 Measurements Throughput Agententechnologien in der Telekommunikation - 42

43 Measurements Handover Times Agententechnologien in der Telekommunikation - 43

44 Side effects Packet loss Depends on handover mechanism No packet loss in StrokeNet scenario TCP bandwidth adaption Switching from channel with high throughput to channel with lower throughput congestion TCP reduces bandwidth Temporary transfer interruption for some seconds Agententechnologien in der Telekommunikation - 44

45 Side effects (2) Jitter Must be handled on higher layers (e.g. jitter buffer) Can cause problems on TCP (packet loss assumed) Source Net 1 Net 2 Dest. 40 ms Packet 1 Packet 2 15 ms Packet 1 80 ms 105 ms Packet 2 Agententechnologien in der Telekommunikation - 45

46 Side effects (3) Out-of-order reception Must be handled on higher layer Leads to problems on TCP (packet loss assumed) Source Net 1 Net 2 Dest. Packet 1 40 ms Packet 2 15 ms 80 ms Packet 2 Packet 1-25 ms Agententechnologien in der Telekommunikation - 46

47 Side effects (4) Most side effects can be solved on higher layers E.g. jitter buffer, retransmit mechanisms In some cases, limitations unavoidable E.g. TCP and out-of-order reception Alternative solutions, e.g. improved versions of TCP Application, access networks and mobility mechanisms must be coordinated Agententechnologien in der Telekommunikation - 47

48 Conclusion Seamless mobility is possible today, at least in some scenarios and with limitations (e.g. no QoS) Users may have other goals than network operators With future technologies, the user mobility can be improved Concepts, to bring users and operators goals together Agententechnologien in der Telekommunikation - 48

49 Next Week Date Title of the Lecture Overview of the Course and Organizational Issues Introduction to Telecommunications and Current Trends Next Generation Networks (NGN) Service Control - IP Multimedia Subsystem (IMS) Heterogeneous Networks and Mobility - User Perspective Heterogeneous Networks and Mobility - Network Operator Perspective IPv4 / IPv6 & Mobile IP Authentication, Authorization and Accounting (AAA) Protocols Network Management Game Theory in Telecommunications Standardization Bodies & Activities in Telecommunications Written In-Class Exam Agententechnologien in der Telekommunikation - 49

50 Agententechnologien in der Telekommunikation - 50