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VERTICAL QOS MAPPING OVER WIRELESS

INTERFACES

Marchese, M.; Mongelli, M.;Wireless Communications, IEEE

Volume 16,  Issue 2,  April 2009 Page(s):37 - 43

Report : Jai- Shiarng ChenDepartment of Communications Engineering CCU

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Outline

Introduction The technology-independent service access

point TI-SAP model Vertical QoS mapping problem Reference scheme for dynamic QoS mapping

over TI-SAP interface Example results conclusions

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Introduction

Modern telecommunication networks Different portions and technologies

The end-to-end Qos is challenged Over heterogeneous Horizontal QoS

Source to the destination The protocol used and the network features

Vertical QoS Composed of layered architectures

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Introduction(cont.)

Qos achieved at each layer of the network Define an interface between adjacent layers

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Introduction(cont.) Establish a QoS-oriented between layers A good example

European Telecommunications Standards Institute (ETSI)

Broadband satellite multimedia(BSM) Satellite-dependent(SD)

Physical , MAC and link control Satellite-independent(SI)

IP and upper layers Satellite independent –service

access point(SI_SAP) Offer QoS service

The architecture is generalized Different physical supports Wire and wireless

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Introduction(cont.)

The idea is to extend Technology-dependent(TD) Technology-independent(TI) Technology independent-service access point(TI-SAP)

Use specific hardware/software solution, often covered by patents

TD and TI communication without affecting TD-layer implementation

Dynamic bandwidth adaptation at TI-SAP Vertical QoS mapping

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The technology-independent service access point

TI-SAP within a wireless portion Overall IP-based heterogeneous

network composed of wide area networks

Wireless portion is located in the middle

Between two generic WANs

The lower must offer a QoS Guarantee to the upper layer

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TI-SAP model

TI-SAP include Abstract queue Identifies a specific QoS level Transfer packets from the TI to the TD layer

A battery of buffers at the TI-SAP Any network node is implemented Different levels of QoS

Different QoS service TI layer can access and modify the abstract queue

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TI-SAP model TI resource management entry

Allocates and manage resource (IP)

TD resource management entry Physically allocates the required

resource Network control center(NCC)

Bandwidth is allocated– Different remote stations

QoS mapping management entry Receive resource require from TI The entry maps it on the lower layer Applied at the TD layer

Translate the request(reservation , release and modification actions)

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Vertical QoS mapping problem

Change of information unit The information come from upper layer Overhead

TI layer is encapsulated within new frame composed information TD layer must consider the additional bits of the header

Heterogeneous traffic aggregation Bandwidth must be adapted at TD

Queue number decreases from upper to lower layer

Fading effect Must handle time-vary-channel

condition Such as satellite and wireless links

10Reference :M. Marchese, QoS over Heterogeneous Networks, John Wiley & Sons, 2007.

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Vertical QoS mapping problem (cont.)

Joint problem Fading effect can be modeled

A multiplicative stochastic process 0(total outage)to 1(free error channel) The model can be iterated

Bandwidth adaptation Very challenging RTD guarantee to TI layer queue Equivalent bandwidth(EqB)

– Minimum service rate to guarantee a certain degree of QoS

– Single QoS constraint

The complexity of overall input flow process– Almost non-applicable

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Reference scheme for dynamic QoS mapping over TI-SAP interface

Allocate bandwidth periodically at the TD layer After receiving the QoS constraints through TI-SAP

RTD(tk) allocation the instant tk

An information vector TD buffer Simply the error e(tk)

Above 0, minimum additional amount of bandwidth – Enable the satisfaction of QoS constraints

Below 0, over-provisioned bandwidth– Maximum amount of bandwidth that can dropped without violating QoS

Minimum bandwidth that guarantees the QoS constraints In the interval [tk-1 , tk] 12

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Reference scheme for dynamic QoS mapping over TI-SAP interface(cont.)

RTF(tk) = RTD(tk–1) + wk e(t⋅ k) wk is a weight

Arrived and lost bits at the TD-layer Compute the loss rate that can be tolerated Check the bandwidth under-provision or over-provision

Estimation of the bandwidth requirement

Allocate the bandwidth in the next interval consequently

Reference chaser bandwidth controller(RCBC) Use the sensitivity of the system performance

Variations of the allocation bandwidth Weight : Wk dynamically over time 13

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Example results Trunk of 50 VoIP TI -> TI-SAP -> TD

ATM at TD layer

Only one IP queueand one ATM queue

Performance metric Packet loss

2 。 10 -2

Packet delay 20 ms

Bandwidth reallocation Every minute

Buffer size TI : 1600bytes

(20 VoIP packet) TD: 3710 byte

(70 ATM cell)

Four peaks Reduction factor

change14 Quick reaction and bandwidth adaptation

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Conclusion

Dynamic schemes based on measure Quickly to change in traffic Performance parameter

Complex mathematical traffic models Unsuitable for real network conditions

Future research Implementation detail of bandwidth adaptation

mechanisms Implement RCBC within a TI-SAP-based architecture

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Thank you

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BSM architectureBroadband satellite multimedia

CSF-1: The interface between the IETF protocols and the Client function (internal to the IP layer).

• CSF-2: The interface between the peer IETF Client [interworking] functions. • CSF-3: The interface between the Client function and the Server function(s). 17

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ETSI BSM protocol stack

18Reference : ETSI, Satellite Earth Stations and Systems (SES), Broadband Satellite Multimedia, IP over Satellite, ETSI Technical Report, TR 101 985 V1.1.2, November 2002.