Vertical Handoff in. Heterogeneous Wireless Networks

Transcription

1 Vertical Handoff in Heterogeneous Wireless Networks Enrique Stevens Navarro March 10th, 2006 UBC-IEEE Workshop on Future Wireless Systems Presentation Outline Heterogeneous Wireless Networks Always Best Connected Mobility Management Handoff Management Vertical Handoff WLAN/Cellular Interconnection Project research at the Communications Group 2 1

2 Heterogeneous Wireless Networks A mi of radio access technologies will co-eist. 3 Heterogeneous Wireless Networks Different Access Technologies (radio interfaces) and overlapping coverage. Different Network Architectures and Protocols for transport, routing and mobility management. Different Service Demands from mobile users (lowdata-rate, high-data rate, voice, etc) Different Operators in the market. 4 2

3 Always Best Connected (ABC) 5 Always Best Connected (ABC) [1] The ABC concept allows a person connectivity to applications using the devices and access technologies that best suit his/her communication needs. The ABC scenario generates great compleity and a number of requirements. Technical solutions. Business relationships. Subscriber handling. [1] E. Gustafsson and A. Jonsson, Always Best Connected, IEEE Wireless Communications, February

4 Mobility Management Different Wireless Networks are complementary to each other, their integration will allow mobile users to be connected using the best available access network that fits their needs. To deal with this problem, Mobility Management Techniques are required Mobility Management Location Management Handoff Management 7 Mobility Management Location Management: It enables the system to track the locations of mobile terminals (MT). Handoff Management: It is the process by which an MT keeps its connection when it moves from one point of attachment (base station or access point) to another. Handoff or handover Horizontal Handoff (HHO) Vertical Handoff (VHO) 8 4

5 Handoff Management Requirements Reduction of signaling and processing overhead. Minimize packet loss and delay (seamless HO). QoS guarantees during the process and transfer of contet. Use of any triggers or metrics available to decide when and where (planned HO). Efficient use of network and MT resources. Enhanced scalability, reliability and robustness. Allow inter-technology handoff (VHO). 9 Horizontal vs. Vertical Handoff [2] Horizontal Handoff Vertical Handoff [2] M. Stem and R. Katz Vertical handoffs in wireless overlay networks, Mobile Networks and Applications,

6 Handoff Metrics Horizontal HO mainly use received signal strength (RSS) to decide the handoff But Vertical HO? RSS? Offered bandwidth? Price? Power consumption? Speed?. Handoff Metrics 11 Vertical Handoff Process Step 1: System Discovery The MT must know which wireless networks are reachable. Step 2: Handoff Decision The MT then evaluates the reachable wireless networks to make a decision. Step 3: Handoff Eecution If the MT decides to perform a VHO, it eecutes the VHO procedure required to be associated with the new wireless network. 12 6

7 Step 1: System Discovery Periodic beacons from AP. Signal measurements. Database query. Handoff metrics gathering. Bandwidth, cost, delay, SNR, power, etc. Periodic / Adaptive network scanning. All interfaces always on. 13 Step 2: Handoff Decision Fuzzy Logic / Neural Networks. Multiple Attribute Decision Making. Decision based on utility / cost functions. User triggered. Decision based on proposed policies: Always use the cheapest network. Always use the interface with lower power consumption. Always use the WLAN. Always use the network with more bandwidth. Decision + stability period. (Avoid ping-pong effect) 14 7

8 Step 3: Handoff Eecution Network Layer: Mobile IP v4 vs. Mobile IP v6. Transport Layer: Stream Control Transmission Protocol (SCTP). Transmission Control Protocol (TCP). Application Layer: Session Initiation Protocol (SIP). Application-based. Infrastructure-based approach End-to-end approach. 15 WLAN Cellular Networks Important case of heterogeneous wireless networks integration. Two architectures are proposed: Tightly-coupled inter-working. Loosely-coupled inter-working. 16 8

9 WLAN Cellular Networks [3] [3] M. Buddhikot, G. Chandranmenon, S. Han, Y. Lee, S. Miller and L. Salgarelli, Integration of and 3G Wireless Data Networks in Proc. of IEEE Infocom WLAN Cellular Networks Integration Some interoperability open issues: When to switch?, VHO policies: WLAN to Cellular Cellular to WLAN Seamless handoff (level of integration). Packet loss and VHO latency. Load balancing between networks. QoS guarantees and transfer of contet. Security and Authentication. Billing and revenue sharing. Implementation. 18 9

10 WLAN Cellular Networks Integration Standardization efforts: Both 3GPP and 3GPP2 are working in the interworking with WLAN as an etension of their radio access networks. IEEE Media Independent Handover Group is working toward the seamless handoffs between: IEEE 802.XX family. IEEE 802.XX and 3G Cellular Between ESSs. 19 Current Research: Comparison of different decision algorithms proposed for vertical handoff. Four algorithms: SAW (Simple Additive Weighting) [4] TOPSIS (Technique for Order Preference by Similarity to Ideal Solution) [4] MEW (Multiplicative Eponent Weighting) [5] GRA (Grey Relational Analysis) [6] [4] W. Zhang, Handover Decision Using Fuzzy MADM in Heterogeneous Networks in IEEE WCNC 04, March [5] K. Yoon and C. Hwang, Multiple Attribute Decision Making: An introduction, Sage Publications, [6] Q. Song and A. Jamalipour, A Network Selection Mechanism for Net Generation Networks in IEEE ICC 05, May

11 Decision Matri Networks to Select - WLAN - CDMA GSM/GPRS : M : M N 2N : MN M Number of networks. N Number of parameters Parameters to Consider - Bandwidth - Delay - Jitter - Bit Error Rate (BER) 21 Decision Methods SAW TOPSIS A * SAW = arg ma i M N j= 1 w r j ij * * A TOP = arg ma ci i M MEW GRA A * MEW w j = arg ma ij i M * A GRA = arg ma Γ0, i i M 22 11

12 Performance Comparison A set of importance weights are calculated according to the QoS requirements of the four traffic classes: conversational, streaming, interactive and background. Simulation: the connection lifetime of the mobile follows an eponential distribution and each network evolves according to a Markov chain. Every time that the status of a network changes the mobile terminal must decide which network to use. 23 Avg. bandwidth (Kbps) Avg. bandwidth (Kbps) Avg. bandwidth (Kbps) Avg. bandwidth (Kbps) SAW MEW TOPSIS GRA (a) Conversational (b) Streaming (c) Interactive (b) Background Average Bandwidth (Kbps) 24 12

13 SAW MEW TOPSIS GRA Avg. delay (ms) Avg. delay (ms) Avg. delay (ms) Avg. delay (ms) (a) Conversational (b) Streaming (c) Interactive (b) Background Average Delay (ms) 25 Students working in the project: Name Enrique Stevens Navarro Jie Zhang Program PhD PhD Area Vertical Handoff Vertical Handoff Jun Wang PhD Pricing Strategies 26 13

14 Summary: Heterogeneous Wireless Networks Mobility Management Handoff Management and Vertical Handoff WLAN/Cellular Inter-working Research 27 Contact Information: Enrique Stevens Navarro Office: Kaiser Thank You! 28 14