a speed adaptive mobile internet protocol over wireless local a rea network jun tian nov. 15 th 2005...

A SPEED ADAPTIVE MOBILE INTERNET PROTOCOL OVER WIRELESS LOCAL

AREA NETWORK

Jun Tian

Nov. 15th 2005

Final Defense Presentation

1. Instruction2. Related Works 3. Performance of MIP over WLAN at

Different Speeds 4. Quantitative Analysis of the MIP over

Wireless LAN Handoff Latencies 5. A Speed Adaptive MIP and Its Performance

Evaluation 6. Summary and Future Works

Contents

Internet Users by Regions

Source: eTForecasts

1 MotivationTrend 1- more and more mobile users

The worldwide number of Internet users will reach nearly 1 billion in mid 2005. The U.S. continues to lead with over 185M Internet users forecasted for year-end 2004. There is little Internet user growth in the developed countries, but in the next five years many Internet users will be supplementing PC Internet usage with Smartphone and mobile device Internet usage. Internet usage is growing strongly in China, which surpassed Japan for second place in 2003. The growth of Internet users will continue in the developing countries for another decade.

“Much of future Internet users growth is coming from populous countries such as China, India, Brazil, Russia and Indonesia. These countries will also see strong growth of wireless web usage and for many new Internet users the cell phone will be their only Internet access device. ”

-- September 3, 2004 - Computer Industry Almanac

Wireless Internet Usage and Projections

Year-End 2001 2004 2007

Worldwide

Internet Users (millions) 533 945 1,460

Wireless Internet User Share

16.0% 41.5% 56.8%

USA

Internet Users (millions) 149 193 236


4.5% 27.9% 46.3%

Asia-Pacific



34.8% 50.9% 60.4%

W. Europe



13.9% 49.6% 67.0%

Source: September 3, 2004 - Computer Industry Almanac

1 MotivationTrend 1- more and more mobile users

IP Backbone/InternetMobile IP

Multi-mode terminal w/MobileIP client& IPSec Client

PublicWLAN

802.11 Access Points

Ethernet

802.11 Access Points

Ethernet

WLANGateway, HA, FA

Home AAA ServerEnterprise

Corporate LAN

VPNFirewall

CDMA2000

Mobile devices can connect to office networks anytime from anywhere….through

CDMA

EDGEWCDMA

GSM

1 MotivationTrend 2- MIP connect the world

1 MotivationTrend 3- Moving speed accelerates wealth accumulation

Japanese Maglev Test speed 581 km/h (361 mph)

Shanghai China's maglev train: 429km/h (267mph )

France's Lignes a Grande Vitesse (LGV): commercial speed of 320km/h(198mph)

German maglev (magnetic levitation): 400 kilometers per hour(248mph)

High Speed Trains

1mbps—550m

11mbps—160m

6mbps—100m

36mbps—20m

1 MotivationTrend 4- small cell to keep a high throughput

802.11b data rate 1mbps 2mbps 5.5mbps 11mbps

Office distance 50m 40m 35m 25m

Outdoors distance 550m 400m 270 160m

Data rate vs distance

Small Wireless CellsAdvantage:•Higher throughput •More number of users

•Diameter of cell decreases by Nnumber of cells in a certain area increases by N²number of available channels increases by N²

Disadvantage:•Mobile host crosses cells more often

More number of handoffs

1 MotivationMobilityMobility

Outdoors

Indoors

Office

Fixed

Walk

Vehicle

0.10.1 11 1010 100 Mbps100 Mbps

Mobility vs data rateMobility vs data rate

Walk

WLAN

GSM

IS-95

IS-136

EDGE

WCDMA

CDMA2000

WPAN

Code Division Multiple Access 2000

Enhanced Data-rate for GSM Evolution

Wide band Code Division Multiple Access

WPAN: Bluetooth(802.15): 0.7-2 Mb/s data WPAN: Bluetooth(802.15): 0.7-2 Mb/s data rates,rates, Cable replacement, Short distances, up Cable replacement, Short distances, up to 10 m.to 10 m.

3G, Wide Area Network(WAN) coverage

WLAN: 802.11WLAN: 802.11

2G

802.11 n

Rapid Mobility?

Could Mobile IP combine all them together

and fulfill its job at high speed

2.1 Network Layer Handoff Management 2.2 Wireless LAN 2.3 Wireless LAN Handoff Management 2.4 Low Latency Handoff Mechanisms for MIP

over 802.11 Network 2.5 Location Tracking

2. Related worksMIP

Hierarchical MIP

Cellular IP

HAWAII

802.11, 11a, 11b, 11g standards

Define the MAC and PHY layer of OSI

Infrastructure, ad hocHandoff management frame

Handoff procedure

Techniques to Reduce IEEE 802.11 Handoff latency:.

Techniques to Reduce IEEE 802.11 Handoff latency

Mishra in [Mish03]: L2 handoff latencies discovery 90% and reauthentication 10%.

In [Mish04], Mishra proposed to reduce reauthentication latency by IAPP.

Kim in [Kim04] and Shin in [Shin04], propose selective scanning algorithms to reduce discovery latency. …..

These are L2 only algorithms

Malki in [Malk02] proposed two mobility protocols, pre- and post-registration, using L2 trigger.

In pre-registration, MN may communicate both oFA and nFA.

In post-registration, data cached in nFA before the registration completed.

These are cross layer solutionsGPS or signal strength to triangulate the location of MN

2.1 Network Layer Handoff ManagementMacro and Micro Mobility

Home Network

INTERNET

Home Agent

GFA

Micro-mobility handoff

Macro-mobility handoff

Macro mobility

Micro mobilitydomain

GatewayFA

Handovers in Micro Mobility transparent outside the domain

Mobile IP

HMIP

CIP

HAWAII

Register (HA)

Home Agent (HA)

Home Network

Correspondent Node (CN)

Foreign Agent (FA)

Foreign Network

Mobile Node(MN)

• When mobile node (MN) moves to a foreign network it obtains acare-of-address (COA) from the foreign agent (FA) that registers it with the home agent (HA)• COA is used by HA to tunnel packets to MN

SolicitationAdvertisement (FA,COA)

Register

Mobile Node

• Each mobile node has a home network, home address and home agent

Packets sent by MN godirectly to CN

- Triangle Routing

2.1 Network Layer Handoff ManagementMobile IP –Macro-mobility management

Specified in RFC3344- C. Perkins, Nokia Research Center, August 2002

- Reverse Tunnel

2.1 Network Layer Handoff ManagementHierarchical Mobile IP –Micro-mobility

• Tree-like structure of FAs • Hierarchical Tunneling • Registration is Regionalized inside a domain To eliminate Handoff Traffic•Regional Registration Request & Reply

FA1

FA2 FA3

FA4 FA5 FA6 FA7

MH

HA

INTERNET

MNFA1

MNFA2

MNFA4

MNCOA

MNFA3

MNFA6

MNCOA

MH MH

CN

MNCOA

MNFA5

Binding

Problems addressed in this dissertation

• Studying the effect of Rapid Mobility on the performance of Mobile Networking Protocol. In particular, we examine:– How speed affects the performance ?

• Performance/speed relationship

– What constructs the handoff latency ? • A global view of the handoff latency

– Breakdown the handoff latency to see: • Where does the latency come from ?• How much ?• What should we do with them ?• A deep examination of the handoff latency

• Designing and Implementing high performance and scalability solution or protocols for rapid mobility


• Studying the effect of Rapid Mobility on the performance of Mobile Networking Protocol. In particular, we examine the effects of:–



– Breakdown the handoff latency to see: • A deep examination of the handoff latency

• Where does the latency come from ?• How much ?• What should we do with them ?


How speed affects the performance ?

Experimental Scenario: In this scenario, a rapid moving MN will travel trough 8 APs. Each AP is wired to a FA. The distance between every two consecutive APs is d= 250m, 500m or 1000m. The moving speed of MN is V, varying from 10m/s to 80m/s.

3. Performance at different speeds

FA1

HA

CN

AP1

internet

FA2

AP2

FA3

AP3

FA4

AP4

FA5

AP5

FA6

AP6

FA7

AP7

FA8

AP8

RAMON: a Rapid Mobile Network emulator


Originally developed by Edwin A. Hernandez in 2002.

Rebuilt and extended by Jun Tian since 2003.

Architecture of RAMON


FA1

192.168.1.1HUB1 AP1

192.168.1.3Attenuator1

Antenna1

ControllerFA2

192.168.2.1HUB2 AP2


Antenna2

FA3

192.168.3.1HUB3 AP3


Antenna3

Emulator

192.168.1.2

192.168.2.2

192.168.3.2

192.168.4.2

COM

COM

192.168.4.1

HA

10.3.3.14

Internet

MN

192.168.4.5

Attenuators are program controllable

Attenuators are program controllableAttenuators are pro-gram controllable

•manipulates the Attenuators

•A router

•Run emulation

•Control Attenuators

By increasing or decreasing the signal strength of one AP, we can emulate the MN moving towards or away from the AP. By varying the increasing or decreasing speed of the signal strength, we can emulate the speed change of the MN.

Speed 20 m/s distance 1000m

time-sequence graph throughput graph


Speed 80 m/s distance 1000m



Speed10 distance 500m



Speed40 distance 500m



3. Performance at different speedsTable 1: Average Throughput at Different Speeds and AP Distances.

Speed (m/s)AP

distance (m)

Bytes transferred (kB)

Travel Time (s)

Average throughput (kB/s)

Total handoff time(s)

Effective time(s)

PMaxavg

(kB/s)

Handoff Rate

(FAs/s)

20 1000 78000 396 196.970 58 338 232.5 0.02

40 1000 33000 197 167.512 57 140 234.31 0.04

60 1000 16700 130.5 127.969 56 74.5 234.07 0.06

80 1000 9200 98.5 94.359 57 41.5 232.673 0.08

10 500 78500 397 197.733 58 339 233.01 0.02

20 500 33100 198 167.172 56 142 234.4 0.04

30 500 16600 129 128.682 56 73 232.86 0.06

40 500 9200 98 93.877 58 40 232.8 0.08

Conclusion 1:

•The total handoff time doesn’t change with speed

Conclusion 2 :

•Effective time/total travel time ratio drops when speed goes up

•This is the reason why high speed has low throughput



Average Throughputs vs Speeds.

Analysis: Let

Pavg--Average throughput

PMaxavg – Average throughput without handoff

Ttravel– Total travel time

Teffective – Total effective time for ftp transmission

Thandoff- Total handoff time while traveling

Khandoff – The number of handoffs while traveling

thandoff – Average handoff time among 7 times of handoff

Pavg = (Pmaxavg / Ttravel ) x Teffetive

= Pmaxavg (Ttravel – Thandoff ) / Ttravel

= Pmaxavg (1 – Thandoff / Ttravel)

= Pmaxavg( 1 – Khandoff x thandoff / Ttravle)

= Pmaxavg( 1 – (Khandoff / Ttravle ) x thandoff ))


Conclusion 3: Above analysis Pavg = Pmaxavg( 1 – (Khandoff / Ttravle ) x thandoff ))

Conclusion 1 thandoff doesn’t change

The change of Pavg is caused by Khandoff / Ttravel ratio.

The performance of MIP over WLAN is related to the ratio of the number of handoffs/ total travel time, which is the MN handoff rate rh .

rh = v/d. The ratio of speed and cell size(AP distance).

This is different from what was previously believed.


3. Performance at different handoff rate

At handoff rate 0.02 FAs/s, the average throughput is 197.35 kB/s . When the handoff rate goes up to 0.08 FAs/s, the average throughput drops to 94.118 kB/s

80

100

200

0 0.02 0.04 0.06 0.08

Handoff rate FA/s

Kby

tes/

sec

120

140

160

180


• Studying the effect of Rapid Mobility on the performance of Mobile Networking Protocol. In particular, we examine the effects of:– How speed affects the performance ?






Answer:

Pavg = Pmaxavg( 1 – rh x thandoff )) equation 2




– • A global view of the handoff latency




What constructs the handoff latency ?

4. MIP over WLAN handoff latency

thandoff = tL2handoff + tL3handoff + tL4handoff (equation 1)

1 MN moves, signal decay or signal interruption causes MN probe request to all channels, available AP’s probe response to MN, MN selects best nAP and sends Authentication request and after gets Authentication ACK sends Reassociation Request

and gets Reassociation Response. L2 handoff finished.

GFA

FA 1 FA 2

HA

CN

AP2AP1

MN

2. MN finds an nFA on its local network by the Agent Discovery process. After received 3 time of Agent Advertisement from nFA, MN sends Registration Request. nFA forward it to HA or GFA. HA or GFA reply with

Registration Reply. L3 handoff finished.

3 Then MN begin to recover interrupted

communication. L4 latency

Global view of MIP/WLAN handoff

Problems addressed in this research• Studying the effect of Rapid Mobility on the performance of Mobile

Networking Protocol. In particular, we examine the effects of:– How speed affects the performance ?


– What constructs the handoff latency ?• A global view of the handoff latency




Answer:

thandoff = tL2handoff + tL3handoff + tL4handoff (equation 1)




–


4. Quantitative Analysis of the MIP over Wireless

LAN Handoff Latency A deep examination of the handoff latency

Breakdown the handoff latency to see:

•Where does the latency come from ?

•How much ?

•What should we do with them ?

MN

nAP

HA

nFA

L2 movement detection

MIP agent discovery

MIP registration

oAP oFA

MIP Advertisement

Registration Request

Registration Reply

Data packageL3 HO signalL2 HO signal

CN

TCP ACKProbe request

Probe response

Reassociation requestAuthentication

Reassociation responseL2 reassociation

TCP retransmission

L2 AP searchingL2

L3

L4

L2 movement detection delay: The strength of received signal degrades below a certain threshold, this may be caused by collision, radio signal fading, or AP is out of range. The STA(MN) detect the lack of radio connectivity based on weak received signal reported by the physical layer or failed frame transmissions. During this period, the TCP ACKs sent by MN to CN keeping lost, as well as the TCP packets from oFA to MN.

L2 searching delay: If transmission remains unsuccessful, the STA start scanning each channel by bradcasting a probe-request frame and waiting for probe respones.L2 reassociation: MN sends reassociation request to selected AP and waits for reassociation responseL3 agent discovery delay: MN got agent advertisement from nFA through nAP. If MN is using active mode, it will send agent solicitation ask for agent advertisement.L3 registration delay: MN sends registration request to HA or GFA and waits for reply.

L4 TCP retransmission belay: The retransmission timer at the sender is doubled with each unsuccessful retransmission attempt, in order to reduce the retransmission rate. Thus when the MN is reconnected, TCP will take a long time to recover from such a reduction and data will not be transmitted for a period of time. ( TCP exponential backoff retransmission policy)

4. Quantitative Analysis of the MIP over Wireless LAN Handoff Latency

A deep examination of the handoff latency

• Studying the effect of Rapid Mobility on the performance of Mobile Networking Protocol. In particular, we examine the effects of:

–




•How much ?


Answer

tL2handoff = tL2detection + tL2seraching + tL2reassociation (equation 3)

tL3handoff = tmipagentdicovery + tmipregistration (equation 4)

tL4handoff = ttcp-back-off (equation 5)

thandoff = tL2detection + tL2seraching + tL2reassociation + tmipagentdicovery + tmipregistration + ttcp-back-off ( equation 6)




–




•How much are the latencies ?




Experimental Scenario: In this scenario, a rapid moving MN will travel trough 8 APs. Each AP is wired to a FA. The distance between every two consecutive APs is d= 250m, 500m or 1000m. The moving speed of MN is V, varying from 10m/s to 80m/s. Pick out 20 experiments data.

FA1

HA

CN

AP1

internet

FA2

AP2

FA3

AP3

FA4

AP4

FA5

AP5

FA6

AP6

FA7

AP7

FA8

AP8



exp#

Delay

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 avg avg

L2 movement detection 1.033

1.064

1.133

1.032

1.044

1.131

1.009

1.120

1.023

1.039

1.100

1.013

1.021

1.006

1.104

1.003

1.110

1.100

1.302

1.098

1.074

L2 AP searching 0.061

0.044

0.063

0.100

0.065

0.057

0.056

0.060

0.059

0.076

0.045

0.049

0.051

0.043

0.069

0.064

0.054

0.064

0.056

0.044

0.059

1.143

L2 reassociation 0.005

0.009

0.006

0.008

0.003

0.004

0.010

0.006

0.026

0.005

0.030

0.010

0.009

0.017

0.006

0.013

0.010

0.006

0.009

0.004

0.010

MIP agent discovery 2.996

1.945

3.023

2.563

2.756

2.578

2.436

3.001

2.213

3.008

2.770

2.545

3.001

2.600

2.598

2.674

2.783

3.012

2.349

2.404

2.660 2.746

MIP registration 0.073

0.042

0.052

0.050

0.052

0.043

0.060

0.704

0.054

0.053

0.041

0.042

0.065

0.046

0.047

0.062

0.054

0.057

0.070

0.062

0.086

TCP back_off 5.058

6.01 5.345

5.323

5.125

5.004

5.625

5.002

4.998

5.006

5.728

4.768

5.202

5.312

4.544

4.806

5.705

5.602

5.71 5.172

5.253

5.253

Handoff Latency 9.226

9.511

9.622

9.076

9.045

8.817

9.196

9.893

8.373

9.187

9.714

8.427

8.896

9.024

8.368

8.622

9.716

9.841

9.496

8.784

9.142

9.142



MN

nAP

HA

nFA

1.074 L2 movement detection

2.660 MIP agent discovery

0.086 MIP registration

oAP oFA

MIP Advertisement

Registration Request

Registration Reply

Data packageL3 HO signalL2 HO signal

CN

TCP ACKProbe request

Probe response0.059 L2 AP searching

Reassociation requestAuthentication

Reassociation response0.010 L2 reassociation

5.253 TCP retransmission

L2 delay1.143

L3 delay2.746

L4 delay5.253

Handoff delay : 9.142

Conclusions:

•The largest latency is due to TCP, then Layer 3.

•If we reduce the L2 and L3 delay, L4 delay will be reduced exponentially.

•This dissertation focuses on L3 latency.



5. Speed Adaptive Mobile IP

Handoff Rate rh = v/d MN moves through how many APs per second.

rh = Khandoff / Ttravel (equation 7)

Where Khandoff is the number of handoffs occurred during the MN traveling. Ttotal is MN’s total travel time.

Lower handoff rate has higher throughput

To reduce rh without changing total travel time, have to decrease the number of handoffs. The optimal is Khandoff = 0

Pavg = Pmaxavg( 1 – rh x thandoff )) (equation 2)

Let N be total FA numbers on the way MN traveling. Let’s assume somehow M is the number of FAs MN can communicate with without L3 handoff delay, which means M is the number of FAs MN has registered to at that moment.

The optimal is let M = N. But this costs too much resources, especially when the number of active MNs is large. Also we don’t know how long will the MN travel at the beginning.


We call M the FA set size that MN registered.

Questions:

1. How to decide FA set size M

2. How to guarantee MN can communicate with a FA set almost like to do with a single FA.

1 hhandoff rtM

where thandoff is the handoff time, rh is the handoff rate. Here we use the experimental average handoff time 9.142s for thandoff. rh is dynamic. For example, at speed 40m/s, AP distance 500m, M = | 9.142 x 40/500 | + 1 = 2. At speed 80m/s, AP distance 500m, M = 3.

For Q1


(equation 8)

For Q2, How to guarantee MN can communicate with a FA set almost like to do with a single FA.

Current FA pre-registers MN with M potential FAs to reduce L3 handoff latency, at the same time let IP packets be multicast to those M FAs in this FA set. So MN won’t feel any handoff delay at the IP level.

By above 2 steps, the set of FAs that MN can talk to without L3 latency was extended from one point in stationary state, to a line at high speed.


rh = 0 0<rh < 0.109 0.109<rh< 0.218 0.218<rh< 0.328

M = 1 M = 2 M = 3 M = 4

FA Set Size vs Handoff Rate

Speed extension

MN’s registration message is extended by speed extension. According to Mobile IP Vendor/Organization-Specific Extensions[RFC3115]. Two Vendor/Organization Specific Extensions are allowed for MIP, Critical (CVSE) and Normal (NVSE) Vendor/Organization Specific Extensions. The basic difference is when the CVSE is encountered but not recognized, the message containing the extension must be silently discarded, whereas when a NVSE is encountered but not recognized, the extension should be ignored, but the rest of the Extensions and message data must still be processed. We use the NVSE extension.


Normal Vendor/Organization Specific Extension

Type = 134 for NVSE extension.

Length is the size in bytes of the extension, not including the type and length bytes.

Verdor/org-ID is assigned in RFC 1700. set 5205.

Vendor-NVSE-Type Indicates the particular type of Vendor-NVSE-Extension. Set as 12 for speed extension.

Vendor-NVSE-Value: the value of MN moving speed.


FA1

HA

CN

AP1

MN

internet

FA2

AP2

FA3

AP3

FA4

AP4

1

2

3

4

5

6 7

89

10 11

12

13

Whenever the MN needs to handoff to a new FA set, after it gets that many times of agent advertisements which is determined by speed(step 1),

it sends a registration request with up-to-date moving speed information to the very first FA in a new FA set (step 2). This FA will calculate the handoff rate and M

The first FA relays the registration request to upper FA or HA(step 3).

Meanwhile, it decapsulates the speed extension, refill the MIP header and authentication extension and then forward it to other FAs(M-1 FAs) in this FA set(step 4).

These other FAs relay the registration request to upper FA or HA as well(step 5).

When the GFA or HA received these registration requests, it builds up tunnels downwards to each FA and responses with registration reply(step 6 and 7). When the FA received the registration reply, it builds up tunnel upwards to the GFA or HA.

Whenever the MN setups the Link-layer contact with the FA, the later forwards the registration reply to the former(step 8, 9 or 10).The MN gets the care-of-address from agent advertisement message(step 10 or 9) or registration reply message(step 9 or 10), and begins data communication.

At the same time, it still sends registration request to the new FA set with up-to-date speed information (step 11). The very first FA in this set decupsulate the message and set up a new FA set. Forward registration request.(12, 13) and repeat the above process.


Time-sequence graph at speed 60m/s and AP distance 1000m

Same scenario as above except SA-MIP is installed.5. Speed Adaptive Mobile IP

Time-sequence graph at speed 80m/s and AP distance 1000m

5. Speed Adaptive Mobile IPSame scenario as above except SA-MIP is installed.

Average throughput at different speeds and AP distances.


Speed (m/s)

AP distance

(m)

Bytes transferred

(kB)

Travel Time(s)

Arg throughput

(kB/s)

Handoff Rate

(FAs/s)

20 1000 85000 399 213.03 0.02

40 1000 37500 198 189.39 0.04

60 1000 19400 130 149.23 0.06

80 1000 11600 99 117.17 0.08

10 500 84400 398 212.06 0.02

20 500 37400 198 188.89 0.04

30 500 19500 131 148.55 0.06

40 500 11500 98 117.34 0.08

Average Throughput of Speed-Adaptive MIP


80

100

200

0 0.02 0.04 0.06 0.08

Handoff rate FA/s

Kby

tes/

sec

120

140

160

180

SA -MIP

MIP

(212.55 - 197.35) /197.35 = 7.69%

(189.14 - 167.34) /167.34 = 13.02%

(148.89 - 128.32) /128.32 = 15.97%

(117.25 - 94.12) /94.12 = 24.58%

220

6. Summery and Future Works

Contributions: Evaluate the rapid mobility of MIP over wireless LAN in a

laboratory environments. Depicted the relationship between the performance and the

moving speed of MN Quantitatively analyzed the handoff latencies of the MIP

over wireless LAN Speed Adaptive MIP is proposed and evaluated

Future WorksSpeed adaptive scheme should be applied to layer 2 and layer 4 handoff latencies.

Publications:

1. J. Tian, A. Helal, "Rapid Mobility of MIP over WLAN," International Conference on Computer Networks and Mobile Computing (ICCNMC'05), Zhangjiajie, China, Aug 2-4, 2005. Lecture Notes in Computer Science, Springer-Verlag GmbH, ISSN: 0302-9743, ISBN: 3-540-28102-9, Volume 3619/2005

2. Jun Tian and A. Helal, "Performance of MIP over WLAN in Rapid Moving Environments," The 4th ACS/IEEE International Conference on Computer Systems and Applications, Dubai/Sharjah, UAE, March 8-11, 2006

3. J. Tian and A. Helal, "Speed Adaptive MIP" submitted to the IEEE Wireless Communication&Network Conference, to be held in Las Vegas, NV, April 2006

4. J. Tian and A. Helal, "Speed Adaptive MIP over Wireless LAN," Submitted to Journal of Wireless Communications and Mobile Computing

• backups

1.1 Network Layer Handoff ManagementCellular IP –Micro-mobility(Campbell )

•Inside the CIP network, Uplink data packets are routed from MN to the gateway on a hop-by-hop basis. •The path taken by these packets is cached in route cache of base stations. •CIP uses mobile originated data packets to maintain reverse path. This path is used to route downlink packets addressed to a mobile host.

CIP routing

CIP BS

IP router

CIP Node

IP routing

IP tunnelling

HAMobile IP enabled Network

MN

GW

Cellular IP network

10Mb2ms

802.11

BS1

BS2

BS3

BS4

1.1 Network Layer Handoff ManagementCellular IP –Micro-mobility

HAMobile IP enabled Network

Active MN

GW

Cellular IP network

Idle MN

Paging update packet

Routing update packet

Routing and Paging Update

1.1 Network Layer Handoff ManagementCellular IP –Micro-mobility

MN listen/send to only one BS(TDMA network )

Hard Handoffpacket loss cannot be eliminated

MN listen/send to two or more BS simultaneously (CDMA network)

Semi-Soft Handoffgood performance eliminates packet loss

Handoff

Rebuilding of RAMON:

• Update hardwire: 3 FA, MN, new CISCO 350 APs, control board(Tarek Kaissi)

•Re-construct the testbed: NAT on HA, routing table on Emulator(help from Edwin)

•Software installation and configuration:

•Linux kernel 2.4.20,

•HUT dynamic MIP implementation version 0.8.1 (Helsinki University of Technology)

•Erase architecture delay


L2 movement detection delay: The strength of received signal degrades below a certain threshold, this may be caused by collision, radio signal fading, or AP is out of range. The STA(MN) detect the lack of radio connectivity based on weak received signal reported by the physical layer or failed frame transmissions. During the period, the TCP ACK sent by MN to CN keeps lost.

L2 searching delay: If transmission remains unsuccessful, the STA start scanning each channel by bradcasting a probe-request frame and waiting for probe respones.

L2 reassociation: MN sends reassociation request to selected AP and waits for reassociation response.

tL2handoff = tL2detection + tL2seraching + tL2reassociation (equation 4)

L3 agent discovery delay: MN got agent advertisement from nFA through nAP. If MN is using active mode, it will send agent solicitation ask for agent advertisement.

L3 registration delay: MN sends registration request to HA or GFA and waits for reply.

tL3handoff = tmipagentdicovery + tmipregistration (equation 4)

L4 TCP retransmission belay: The retransmission timer at the sender is doubled with each unsuccessful retransmission attempt, in order to reduce the retransmission rate. Thus when the MN is reconnected, TCP will take a long time to recover from such a reduction and data will not be transmitted for a period of time. ( TCP exponential backoff retransmission policy)

tL4handoff = ttcp-back-off (equation 5)

thandoff = tL2detection + tL2seraching + tL2reassociation + tmipagentdicovery + tmipregistration + ttcp-back-off ( equation 6)



FA1

HA

CN

AP1

MN

internet

FA2

AP2

FA3

AP3

FA4

AP4

1

2

3

4

5

6 7

89

10 11

12

13

Whenever the MN needs to handoff to a new FA set, after it gets that many times of agent advertisements which is determined by speed(step 1),

it sends a registration request with up-to-date handoff rate information to the very first FA in a new FA set (step 2).

The first FA relays the registration request to upper FA or HA(step 3).

Meanwhile, it decapsulates the speed extension, refill the MIP header and authentication extension and then forward it to other FAs(M-1 FAs) in this FA set(step 4).

These other FAs relay the registration request to upper FA or HA as well, just like the request comes from the MN(step 5).

When the GFA or HA received these registration requests, it builds up tunnels downwards to each FA and responses with registration reply(step 6 and 7).

When the FA received the registration reply, it builds up tunnel upwards to the GFA or HA. Whenever the MN setups the Link-layer contact with the FA, the later forwards the registration reply to the former(step8, 9 or 10).

The MN gets the care-of-address from agent advertisement message(step 10 or 9) or registration reply message(step 9 or 10), and begins data communication.

At the same time, it sends registration requests to the new FA with up-to-date speed information (step 11). This new FA decapsulates the message, sets up a new FA set, forwards the request(12,13)

and repeats the above process.


a speed adaptive mobile internet protocol over wireless local a rea network jun tian nov. 15 th 2005...

Documents

growth of internet users

new internet users

future internet users

mobile device internet

pc internet usage

wireless internet user

internet access device

little internet user