VERTICAL QOS MAPPING OVER WIRELESS INTERFACES

1. VERTICAL QOS MAPPING OVER WIRELESS INTERFACES Marchese, M.; Mongelli, M.;Wireless Communications, IEEEVolume 16,  Issue 2,  April 2009 Page(s):37 - 43 Report : Jai- Shiarng ChenDepartment of Communications Engineering CCU

2. 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

3. 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

4. Introduction(cont.) • Qos achieved at each layer of the network • Define an interface between adjacent layers

5. 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

6. 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

7. The technology-independent service access point • The lower must offer a QoS • Guarantee to the upper layer • 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

8. 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

9. 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)

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

11. 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

12. 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]

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

14. 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 change • Quick reaction and bandwidth adaptation

15. 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

16. Thank you

17. 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).

18. ETSI BSM protocol stack 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.