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Seamless Mobility in WiMAX Nada Golmie and Richard Rouil Advanced Networking Technologies Division National Institute

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Seamless Mobility in WiMAX Nada Golmie and Richard Rouil Advanced Networking Technologies Division National Institute

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    1. Seamless Mobility in WiMAX Nada Golmie and Richard Rouil Advanced Networking Technologies Division National Institute of Standards and Technologies Gaithersburg, MD 20899 USA www.antd.nist.gov/seamlessandsecure.shtml

    2. 2

    3. 3 Seamless Future Networks The reality of networks today consist of a combination of different access & core network technologies. The vision for the future is to be always connected = anytime, anywhere. This is not achieved using a single technology, but using different networks stitched together in order to form a network of networks, where users can roam seamlessly and securely across different infrastructures always utilizing the best resources available. The reality of networks today consist of a combination of different access & core network technologies. The vision for the future is to be always connected = anytime, anywhere. This is not achieved using a single technology, but using different networks stitched together in order to form a network of networks, where users can roam seamlessly and securely across different infrastructures always utilizing the best resources available.

    4. 4 Everyday Usage Scenarios Who are are the users and what are the mobility usage scenarios that we eluded to? They range from everyday scenarios for commercial and business applications. For example: Usage case#1: A user unplugs his laptop from the Ethernet port and walks to a conference room where there is wireless connectivity Usage Case#2:A mobile user using VoIP walks out of his office, gets into his car and drives out of town Usage Case#3: A mobile user is walking in a train station / airport and is roaming across domains and service providers Who are are the users and what are the mobility usage scenarios that we eluded to? They range from everyday scenarios for commercial and business applications. For example: Usage case#1: A user unplugs his laptop from the Ethernet port and walks to a conference room where there is wireless connectivity Usage Case#2:A mobile user using VoIP walks out of his office, gets into his car and drives out of town Usage Case#3: A mobile user is walking in a train station / airport and is roaming across domains and service providers

    5. 5 Emergency Response Scenario Of course, there are also very good usage scenarios for public safety / and emergency response. An ambulance is called at the scene of a car crash. A paramedic initiates a communication to a hospital via a wide area cellular link for the relay of low bit-rate video in order to assess the severity of the accident. The paramedic decides to consult with a specialist via the same link. The paramedic request the download of patient’s medical record from the hospital server: the transfer is too slow, the paramedic decides to use the ambulance satellite link. Only the down-link is available and the up-link is still provided over the wide-area cellular link. Connectivity with the hospital is managed over a wireless local area network between paramedic and the ambulance. Of course, there are also very good usage scenarios for public safety / and emergency response. An ambulance is called at the scene of a car crash. A paramedic initiates a communication to a hospital via a wide area cellular link for the relay of low bit-rate video in order to assess the severity of the accident. The paramedic decides to consult with a specialist via the same link. The paramedic request the download of patient’s medical record from the hospital server: the transfer is too slow, the paramedic decides to use the ambulance satellite link. Only the down-link is available and the up-link is still provided over the wide-area cellular link. Connectivity with the hospital is managed over a wireless local area network between paramedic and the ambulance.

    6. 6 Military Usage Scenario We see military communications as another good usage scenario for fluid combat, intelligence gathering, urban warfare. We see military communications as another good usage scenario for fluid combat, intelligence gathering, urban warfare.

    7. 7 Key Challenges Scalability – roaming from any access network to any other access network (2G, 3G, 4G, Wi-Fi, Wi-Max, Bluetooth, Satellite, Ethernet) Standard handover interfaces – interoperability between different vendor equipment. Cross-layer solutions - extensions to layer 1 & layer 2 functionalities in order to optimize higher layer mobility architectures (MIPv4, MIPv6, SIP). QOS guarantees during handover – no disruption to user traffic: extreme low latency, signaling messages overhead and processing time, resources and routes setup delay, near-zero handover failures and packet loss rate Security – user maintains the same level of security when roaming across different access networks. The next question we ask, is what are the key challenges in order to achieve this vision of seamless mobility? We list a few here and we will elaborate later on each point: Scalability – lots of technology-to-technology solutions, how well do these solutions scale? Standard handover interfaces in order to enable vendor & equipment interoperability. Cross-layer solutions across the protocol stack – mobileIP or layer 3 solutions require optimization & extensions in order to provide a faster and lighter handover, and be able to manage multiple interfaces & flows. QOS in terms of delay, throughput, loss requirements And last but not least is security, and the main question here is how to keep the same level of security when roaming from one network to the other? The next question we ask, is what are the key challenges in order to achieve this vision of seamless mobility? We list a few here and we will elaborate later on each point: Scalability – lots of technology-to-technology solutions, how well do these solutions scale? Standard handover interfaces in order to enable vendor & equipment interoperability. Cross-layer solutions across the protocol stack – mobileIP or layer 3 solutions require optimization & extensions in order to provide a faster and lighter handover, and be able to manage multiple interfaces & flows. QOS in terms of delay, throughput, loss requirements And last but not least is security, and the main question here is how to keep the same level of security when roaming from one network to the other?

    8. 8 Seamless & Secure Mobility Project

    9. 9 Our results on mobility in IEEE 802.16 Network entry in IEEE 802.16 Network entry evaluation results Mobility support in IEEE 802.16e Channel scanning algorithm

    10. 10 Network entry evaluation

    11. 11 Synchronization

    12. 12 Initial Ranging

    13. 13 Registration

    14. 14 Network Entry: summary

    15. 15 Mobility support in IEEE 802.16e In IEEE 802.16e, a MS can scan for potential target BSs while maintaining connection with current BS. There are 4 possible scanning modes: Scan without association: no ranging during scanning Association level 0: contention based ranging Association level 1: dedicated ranging slot Association level 2: level 1 with ranging responses sent over the backbone Exchange of information with neighboring BSs such as DCD and UCD messages Broadcast of neighboring information (DCD and UCD messages) to connected MSs Synchronization between scanning MS and serving BS to reduce packet loss Messages exchange Negotiation of scanning time

    16. 16 Channel Scanning in IEEE 802.16e

    17. 17 Proposed solution Objectives of the Adaptive Channel Scanning (ACS) algorithm: minimize the disruptive effects of scanning on the application traffic by using the QoS traffic requirements. Assumptions: Neighboring BSs exchange information over the backbone The messages are extended to fit the information required by the algorithm Stage 1: estimate the time needed by a MS to scan the possible neighboring stations Stage 2: compute the interleaving of channel scanning and data transmission intervals R. Rouil, N. Golmie, “Adaptive channel scanning for IEEE 802.16e” in the Proceedings of Military Communications, MILCOM 2006, October 2006.

    18. 18 ACS stage 1: scanning time estimation The scanning time consists of two elements: Synchronization latency: DCD and UCD messages are provided by the serving BS. The MS only waits for DL_MAP and UL_MAP messages, generally located in each frame. Association latency: depends on the association level provided by the neighbor BS.

    19. 19 ACS stage 2: Interleaving of channel scanning and data transmission intervals The information used is: Quality of Service of the applications Available bandwidth Number of concurrent scanning stations The algorithm computes the following information: Channel scanning duration Duration between scanning iterations Number of scanning iterations

    20. 20 ACS algorithm: Example of scanning allocation

    21. 21 Evaluation results: simulation scenario

    22. 22 Simulation results for 1 MS

    23. 23 Simulation results for 3 MS

    24. 24 Demos Homogeneous handovers in IEEE 802.16 and 802.16e Heterogeneous handovers between IEEE 802.11 and IEEE 802.16

    25. 25 Scenario: Handovers in IEEE 802.16 and 802.16e

    26. 26 Simulation Parameters

    27. 27 Handover configuration parameters No Triggers: The movement detection is based on Layer 3 Neighbor Discovery The reception of a RA indicates the new network. Since the node is not aware of the new link, no RS is sent. Simulation parameters: RA interval for the simulation U[1s,10s] Prefix lifetime 18s Link Triggers: Device is MIH enabled and receives Link Detected/UP/Down triggers. The triggers are generated by the media to indicate new network or loss of connection Link Detected upon reception of DL_MAP message; UCD=DCD= 5s Link Up upon successful registration Link Down when the synchronization messages are not received within the Lost_UL_Map=Lost_DL_Map= 600ms (Max value in spec) Link Going Down when the power received is below the Link Going Down Threshold: 3.559572e-9W

    28. Place for video

    29. 29 Scenario: Heterogeneous handovers

    30. 30 Simulation parameters

    31. 31 Link Going Down trigger parameters Device is MIH enabled and receives Link Detected/UP/Down/Going Down triggers Link Going Down triggers are based on the received power (relative to the receiver sensitivity) Timeline: Handover 802.11-802.16: 17s, due to Link Going Down 802.11: Pt=0.0134W, RxThreshold: 5.25089e-10 W, Going Down Threshold:  6.301068e-10 W, F= 2.4Ghz Handover 802.16-802.16: 53s, due to Link Going Down 802.16: RxThreshold: 2.96631e-09W, Going Down Threshold: 3.559572We-9, Pt = 15W, F=3.5 GHz Handover 802.16-802.11: 98s, due to detection of new AP, Link UP

    32. Place for video

    33. 33 Contributions to IEEE 802.21 N. Golmie, S. Woon, “Performance measurements for Link Going Down Trigger,” IEEE 802.21 Media Independent Handover Working Group Contribution #21-05-419, January 2006. R. Rouil, N. Golmie, “Effects of IEEE 802.16 link parameters and handover performance for select scenarios,” IEEE 802.21 Media Independent Handover Working Group Contribution #21-06-0524, March 2006. N. Golmie, U. Olvera, R. Salminen, “Media Independent Handover QOS Framework and parameters,” IEEE 802.21 Media Independent Handover Working Group Contribution #21-06-0493, March 2006. N. Golmie, U. Olvera, R. Salminen, “QOS Proposal,” IEEE 802.21 Media Independent Handover Working Group Contribution #21-06-0598, May 2006. R. Rouil, N. Golmie, “MIH primitives and scenarios,” IEEE 802.21 Media Independent Handover Working Group Contribution #21-06-0614, May 2006. N. Golmie, U. Olvera, R. Salminen, R. Rouil, S. Woon, “Implementing Quality of Service based handovers using the IEEE 802.21 framework,” IEEE 802.21 Media Independent Handover Working Group Contribution #21-06-0687, July 2006 N. Golmie, R. Rouil, “QOS Updates,” IEEE 802.21 Media Independent Handover Working Group Contribution #21-07-011, January 2007

    34. 34 Conference papers S. Lee and N. Golmie, ‘’Power Efficient Interface selection scheme using paging for WLAN in Heterogenous wireless networks,” to appear in the Proceedings of the International Conference on Communications,” ICC 2006, June 2006. S. Woon, N. Golmie, and A. Sekercioglu, “Effective Link Triggers to Improve Handover Performance,” to appear in the Proceedings of the International symposium on Personal Indoor and Mobile Radio Communications, PIMRC 2006, September 2006. R. Rouil, N. Golmie, “Adaptive channel scanning for IEEE 802.16e” to appear in the Proceedings of Military Communications, MILCOM 2006, October 2006.

    35. 35 Tools for Public Download IEEE 802.16 NS-2 model IEEE 802.21 mobility package Some documentation Available on: http://www.antd.nist.gov/seamlessandsecure/download.html

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