1. LYU9903 QoS Schemes in Wireless Networks Ho Pun Mo (97678721) & Ng Maggie (97746133) Supervised by Prof. Lyu Rung Tsong, Michael Marked by Prof. Ng Kam Wing 25 April, 2000

2. Outline Introduction Review – What we have done in the last semester QoS Schemes – Wireless QoS Scheme Wired QoS Scheme Real-time Video Application Performance Evaluation Conclusion

3. Introduction

4. Summary of Our Project Applying QoS in wireless environment Integrating our QoS scheme (wireless) and LYU9802’s QoS scheme (wired) Implementing Real-time Video Player Performance Evaluation of using QoS on video application

5. Our Difficulties QoS in WLAN is a fresh topic Few papers/references are available Must tackle with hardware to achieve good result We have used a few weeks to ponder what we can do Need to deal with MAC layer Concern on quality control rather than producing a product/applying an algorithm!

6. REVIEW What we have done in the last semester

7. Measurement Compare the bandwidth usage with and without QoS With QoS enabled Real-time audio application used more bandwidths The mp3 player could play smoothly Without QoS enabled Mp3 player and FTP competed for bandwidths The mp3 player had “click” sounds

8. Ported the System to Wireless Using LYU9802’s QoS scheme in the wireless environment and it works! Measurement just like the wired one, except that more time was needed to play the mp3 and FTP applications

9. QoS Schemes

10.       Server Client

11. Schemes We Have Thought Of Decrease error rate Hardware-oriented!  Improve the hand-off mechanism Not enough reference!  Access points must be involved!  Use a workstation to simulate access point Overhead introduced!  etc.

12. QoS Scheme for WLAN We ain’t focusing on general methods (It is too harsh!  ) Ad-hoc method is used and therefore assumptions have been taken Many areas can be improved for the wireless environment – we will focus on a specific aspect For video/audio applications over WLAN

13. What to do? In one sentence Reserving bandwidth before sending How to do? Scenario At least two notebooks (with wireless equipment) An access point connecting to a wired network A server connecting to the wired network above

14. Algorithm Fact Packets are regular for real-time applications Objective Reducing collision probability when real-time packets are traveling through the air Method Broadcasting a “signal” packet between two consecutive real-time packets While receiving the “signal” packet, one would stop sending packets for a fixed time

15. Assumptions The environment is “clean” No node will remove from or enter into the coverage of the access point Only one real-time client is running

16. Implementation System call To send signal packets How?

17. Implementation Adding new system call /usr/include/asm/unistd.h #define __NR_vfork190 #define __NR_lyu9903signal191 /usr/include/bits/syscall.h #define SYS_lyu9903signal __NR_lyu9903signal /usr/src/linux/arch/i386/kernel/entry.S.long SYMBOL_NAME(sys_vfork).long SYMBOL_NAME(sys_lyu9903signal).rept NR_syscalls - 190.long SYMBOL_NAME(sys_ni_syscall).endr 191

18. Implementation Problem! System call should be resided in kernel The function call for sending the signal packets is resided in the driver The driver is a module, that is, it is not part of kernel

19. Implementation Solution /usr/src/linux/kernel/sys.c asmlinkage int sys_lyu9903signal() { printk(“Please insert a WaveLAN card\n”); return 0; } When called, it will print out: Please insert a WaveLAN card

20. wvlan_cs.c extern int init_module(void) { …. orig_sys_lyu9903signal = sys_call_table[__NR_lyu9903signal]; sys_call_table[__NR_lyu9903signal] = new_sys_lyu9903signal; …. } extern void cleanup_module(void) { …. Sys_call_table[__NR_lyu9903signal] = orig_sys_lyu9903signal; ….} When the card is inserted, it is loaded. When the card is ejected, it is unloaded. When it is loaded, the driver will alter the system call table in the kernel, making the new system call pointing to the function for sending signal packets When it is unloaded, it will restore the location of the system call

21. Implementation How to send signal packets? WaveLAN packet frame structure

23. Implementation Useful functions hcf_put_data() To transfer transmit message data parts or control information to the WaveLAN PCMCIA card hcf_get_data() To obtain received message data parts or control information from the WaveLAN PCMCIA card hcf_send() Start sending packets

24. QoS Scheme for Wired LAN Components Bandwidth Reservation – RSVP Packet Scheduling – CBQ

25. Bandwidth Reservation RSVP

26. Packet Scheduling CBQ

27. QoS Scheme = RSVP + CBQ       Server Client

28. Link Structures Ethernet Others FTP Video 8M 10M 2M Link structure for No QoS iproute2+tc noqos.wireless #! /bin/sh TC=tc IP=ip DEVICE=eth0 BW="10Mbit” LIMIT="2Mbit” REMAIN="8Mbit” $TC qdisc \ add dev $DEVICE root handle 1: \ cbq bandwidth $BW avpkt 1000 mpu 64 $TC class \ add dev $DEVICE parent 1: classid :1 est1msec 8msec \ cbq bandwidth $BW rate $REMAIN allot 1514 maxburst 50 avpkt 1000 \ bounded isolated prio 1 split 1:0 defmap 0xffaa $TC class \ add dev $DEVICE parent 1: classid :4 est 1msec 8msec \ cbq bandwidth $LIMIT rate $LIMIT allot 1514 maxburst 50 avpkt 1000 \ bounded isolated prio 7 split 1:0 defmap 0x0001

29. Ethernet Others IEEE802.11 8M 10M 2M VideoFTP 1M2M Link structure for QoS qos.wireless [stuff deleted] $TC class \ add dev $DEVICE parent 1: classid :2 est 1sec 8sec \ cbq bandwidth $LIMIT rate $LIMIT allot 1514 maxburst 50 avpkt 1000 \ bounded isolated prio 4 split 1:0 defmap 0x0005 $TC qdisc \ add dev $DEVICE parent 1:2 handle 4: \ cbq bandwidth $LIMIT avpkt 1000 mpu 64 $TC class \ add dev $DEVICE parent 4: classid :3 est 1sec 8sec \ cbq bandwidth $FTP rate $FTP weight $FTP \ allot 1514 maxburst 50 avpkt 1000 \ bounded isolated prio 8 split 4:0 defmap 0x0004 $TC class \ add dev $DEVICE parent 4: classid :4 est 1sec 8sec \ cbq bandwidth $VIDEO rate $VIDEO weight $VIDEO \ allot 1514 maxburst 50 avpkt 1000 \ bounded isolated prio 1 split 4:0 defmap 0x0001

30. Real-Time Video Application

31. Video Application Purpose Demonstration Design Client/server model Using TCP/IP Video Format: MPEG-1 Decoder is present on the client side QoS is embedded

32. Overview

33. Implementation Client/Server Model Using TCP/IP Streaming Send Rate ~1.3Mbps QoS Using RAPI to access RSVP parameters

34. RAPI RAPI: Application Programming Interface for RSVP Used by Application to request QoS Communication between RSVP daemon and application

35. RAPI Objects Session - RSVP assigns QoS to an specific multipoint- to-multipoint data flow Data sender - the data source Data receiver - make QoS requests

36. Inside the QoS request: flowspec Rspec Tspec filterspec

37. rapi_reserverapi_sender

38. Performance Evaluation

39. Experiment Experiment is done to evaluate the effect of QoS on video application Real-time Video Application, FTP application are used

40. Experiment Scenario

41. Experiment Results

42. Results Analysis With QoS: Video Application has higher priority Video Application received more and steady bandwidth Video played more smoothly Both Video & FTP applications used up less time

43. Results Analysis Without QoS: Applications competed for bandwidth Video application did not received steady bandwidth Video application did not played smoothly Both video & FTP applications used up more time Conclusion: QoS makes effect on real-time video application

44. Conclusion

45. Q & A Thank You!