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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 Chen
Department of Communications Engineering CCU
CN Group
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)


Satellite-independent(SI)


Physical , MAC and link control
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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
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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

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Such as satellite and wireless links
Reference :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
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In the interval [tk-1 , tk]
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Reference scheme for dynamic QoS
mapping over TI-SAP interface(cont.)
 RTF(tk) = RTD(tk–1) + wk ⋅ e(tk)

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


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Variations of the allocation bandwidth
Weight : Wk dynamically over time
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 Trunk of 50 VoIP
 TI -> TI-SAP -> TD

Example results
ATM at TD layer
 Only one IP queue
and 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
change
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 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 architecture
Broadband 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.
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 • CSF-3: The interface between the Client function and the Server function(s).
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ETSI BSM protocol stack
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Reference : ETSI, Satellite Earth Stations and Systems (SES), Broadband Satellite Multimedia, IP
over Satellite, ETSI Technical Report, TR 101 985 V1.1.2, November 2002.
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