1. Integrating SIP and IEEE 802.11e to Support Handoff and Multi- grade QoS for VoIP Applications Jen-Jee Chen,Ling Lee,Yu-Chee Tseng National Chiao Tung University,Hsin-Chu,30010,Taiwan Proceeding of the 2nd ACM international workshop on QoS and Security for wireless and mobile networks

2. NCU-Broadband Abstract  There is a need to guarantee QoS for VoIP calls while supporting as many calls as possible  Besides the bandwidth limitation, the codec, packetization interval and delay budget may influence the number of supported calls  Proposed resource degrade and upgrade algorithms as calls enter and leave a QAP.

3. NCU-Broadband IEEE 802.11e MAC protocol  QAP, QSTA  HCF includes EDCA and HCCA which similar to DCF and PCF  TXOP : Transmission opportunity  Four ACs : AC_BK,AC_BE,AC_VI,AC_VO  Admission Control in EDCA : ADDTS request and ADDTS response

4. NCU-Broadband SIP and SDP  SIP is a protocol for establishing an IP multimedia session  Messages send in a SDP message body

5. NCU-Broadband The proposed QoS mechanisms  Call Admission Control (CAC), which is performed whenever a new call or a handoff call arrives at a QAP  Resource Adjustment (RA) algorithm, which is change bandwidth allocation among on-going calls

6. NCU-Broadband Message flows of CAC procedure A : Resource Estimation at QAP B : QAP selection at the caller C : Resource Reservation at QAP D : ADDTS Request by the caller E : ADDTS Response by the QAP

7. NCU-Broadband Resource Estimation at the QAP  QSTA sends Probe Request or INVITE that contains codec and PI  QAP use codec,PI and data rate to calculate Medium Time  MT is larger than B deg, then drop or reply with code 408

8. NCU-Broadband Resources Reservation at QAP  If it is a handoff call, it will be accept if the request MT is no more than B deg ; otherwise, the call is reject.  If it is a new call, there are two cases :  The call with the best QoS level will be degraded first. If there are multiple choices, the one with the lowest physical layer will be degrade first.

9. NCU-Broadband Example of Resource Reservation

10. NCU-Broadband ADDTS Request and Response  Caller :  Minimum_data_rate  Mean_data_rate  Maximum_data_rate  Medium_Time  QAP:  TXOPBudget[AC i ]  TxAdDn[AC i ][TSID]  TxAdUp[AC i ][TSID]  TxAdDn[AC i ]  TxAdUp[AC i ] Resource Reservation at QAP :

11. NCU-Broadband Resource Adjustment algorithm  Triggered by two events :departure of calls and transmission rate change of existing calls  The call with the worst QoS level will be upgrade first; if there are multiple choices, the one with the highest physical rate will be upgrade first

12. NCU-Broadband Examples of RA

13. NCU-Broadband Simulations on channel utilization and good put

14. NCU-Broadband Dropping rate and blocking rate

15. NCU-Broadband Influence of P r and Traffic Charastic

16. NCU-Broadband Conclusions  CAC and RA mechanisms can make better use of the network resources