wireless

Integration of Heterogeneous Wireless Access Technologies:

Integration of Heterogeneous Wireless Access Technologies A challenging research opportunity

Presentation Outline:

Presentation Outline Introduction to Heterogeneous Wireless Research Research at Berkeley ( Video presentation ) Research at Cambridge Finally, Discuss a paper published on July 2004 by Cambridge Group entitled “ Client Based Handoff Mechanism for Mobile IPv6 Wireless Networks” Authors – Leo with Univ. of Cambridge Glenford with AT & T Laboratories

Introduction Take a look at a heterogeneous wireless environment ….. :

Introduction Take a look at a heterogeneous wireless environment ….. The integration of heterogeneous wireless networks is one of the most important research area in the wireless field

Constituents of the Heterogeneous Environment:

Constituents of the Heterogeneous Environment Table -Diversity in existing and emerging wireless access technologies

Slide 5:

Research challenges in Heterogeneous Wireless Networks Provide ubiquitous Internet access to the Mobile Node Shield the Mobile Node from Network Heterogeneity Maintain the same level of Service Improvements to the Mobile IPv6 protocol Pricing Models for such heterogeneous networks

Research at Berkeley:

Research at Berkeley Project title - BARWAN ( Bay Area Research Wireless Access Network) Heterogeneous Test bed - San Francisco Bay Area (Satellite, GPRS, WLAN, Infra Red) Goal - To demonstrate a scalable architecture that can support ubiquitous wireless access across multiple overlaid networks. Highlights - 1) Uses a proxy server to truncate data depending on the mobile device. 2) Policy Based Handoff over Heterogeneous Wireless Access Networks.( J. Helen was the first to propose this handoff)

Bay Area Research WAN ( BARWAN) :

Bay Area Research WAN ( BARWAN)

Research at Cambridge:

Research at Cambridge Project Name - Cambridge Open Mobile Systems ( COMS ) Laboratory - Communication Engineering Goal – Supporting Seamless Mobility in Mobile IPv6 Networks Test bed – Mobile IPv6 based GPRS/3G- WLAN- LAN and a Blue tooth Personal Area Network.

Research at Cambridge (COMS)..contd:

Research at Cambridge (COMS)..contd Highlights of the COMS project Client Based Algorithm for fast horizontal handovers GPRS/WLAN/LAN loosely coupled MIPv6 based test bed Analysis of MIPv6 performance during vertical handovers Methods to minimize vertical handover latency Analysis of UDP/TCP performance for vertical handoffs

Research Paper (Cambridge):

Research Paper (Cambridge) Title -Client Based Handoff Mechanism for Mobile IPv6 Networks Problem Statement - The current proposed protocol MIPv6 specification does not support a suitable vertical handoff mechanism. Solution- A efficient handoff Mechanism is proposed and tested real time on a heterogeneous test bed

Slide 11:

Let us refresh Some Basics of Handoff- Handoff is defined as a process used to allow a call/data transfer to continue as the mobile terminal moves btw cells

Slide 12:

Hard handoff vs. Soft handoff Hard handoff- break before make Soft handoff – Make before break Vertical Handoff vs. Horizontal Handoff Vertical Handoff- Between Different Networks Horizontal Handoff- Between Same Networks Decision to handoff is based on the received signal strength or S/I ratio. Some Basics..contd

Slide 13:

Two types of handoff mechanisms were investigated at Cambridge Network controlled handover - Mobile N ode reports the received signal strengths from various base stations to the network Network then controls the handover Network-controlled handover is unsuitable for vertical handovers, since each network will have to be aware of the characteristics of all the other wireless networks to be able to take the decision. Client controlled handover - Mobile Node controls the handover The mobile node can take into account various factors such as the state of transport connections, the applications running on the mobile, the traffic conditions in all available overlapped cells

Slide 14:

Tasks implemented by Client Handover Mechanism control and force handovers , determine the best link , handover at the appropriate time , and resume active TCP connections . Client Handover Sequence of operation Receives IPv6 router advertisements( RA) from nearby access points Advertisements are stored in Mobile Host RA cache Advertisement information include signal strength, link-layer metrics along with time stamp. RA cache is examined to determine the next access point to which the mobile node should be attached TCP connections are forced to resume swiftly avoiding TCP slow start and packet loss.

Slide 15:

Throughput of a UDP data stream versus the handover frequency Blue line- Mobile IP Redline- Mobile IP with client based handover Simulation results at COMS test bed

Slide 16:

What lead to such a performance…?????? Fast Router Advertisement: Reduces network detection time However Router advertisement frequency can be reduced with larger network size Router Advertisement(RA) caching: Helps us proactively decide next attachment point The detection time for RA lookup during handover execution is eliminated, improving overall performance Binding Update bi-casting:Reduces registration time R_t For a given network - Round Trip Time (RTT) = Minimum Latency Bi-cast Binding updates – Allows registration earlier through a smaller network having lower RTT.

Slide 17:

Table – This shows how Binding Update Bi-casting reduces registration time

Summarizing……..:

Summarizing…….. Introduced Heterogeneous wireless research particularly at Berkeley and Cambridge research laboratories Introduced a better handover approach called as client based handover mechanism for Mobile IPv6 The improvements in the proposed approach were – Faster Router Advertisements Router Advertisement Caching Bi- cast Binding updates And Thank you everyone for your attention !