Planning for VoWiFi

2. Planning for VoWiFi Jai Rawat, AirTight Networks jai.rawat@airtightnetworks.net

3. Agenda • Wireless Medium Characteristics • RF Basics • VoWiFi Deployment Challenges • VoWiFi Deployment Best Practices/Solutions • Interactive Workshop • Take Away • Q&A

4. Wireless Medium Characteristics • Access Point (AP) coverage depends on • Building material • Building layout • AP location • Mount type (ceiling, wall, desktop) • Antenna type and orientation • AP transmit power • Transmit protocol (802.11 a/b/g) • Coverage is not static/predictable • Fluctuates constantly due to multipath and moving objects • Interference due to neighbor APs or other sources of noise • Packet collisions

5. RF Basics

6. 10W 101 Power 10-3 10-6 Source RF Basics : What is dB? (= 40 dBm) dB: relative measure of signal strength at log scale dBm: absolute measure with 1mW power defined as 0 dBm Path loss from source to d2 = 70dB 1mW (= 0 dBm) 10,000 times 1,000 times 40 dB 1 W d2 30 dB (= -30 dBm) d1

7. Antenna Basics High gain directional Dipole Isotropic 0 dBi 2.2 dBi 14 dBi

8. Sample RF Propagation • Wi-Fi is invisible • RF does not propagate in circles • Different vendor products behave differently • Site layout and construction have a significant impact Resulting in • Coverage holes • Dead spots

9. VoWi-Fi Deployment Challenges

10. Voice over Wi-Fi Deployment Challenges • Planning • Monitoring • Security

11. VoWiFi Challenges: Planning What is my security exposure? What is the estimated network performance? What is an Optimum network design ? Am I getting a minimum connectivity speed everywhere? Where should APs to be placed? Can I quickly run what-if scenarios? What kind of APs and Antennas ? What is the optimal AP configuration to minimize interference and maximize coverage? How many Access Points do I need?

12. VoWiFi Challenges: Planning • Capacity Planning • AP Placement and Configuration Planning

13. Planning: 1. Capacity Planning • What type of applications will be deployed? Do they require QoS? • Data, Voice, Video, other services? • How much network capacity is needed for each of these application types? • Dedicated capacity for QoS applications • What is the projected growth for these applications?

14. Planning: Example Capacity Planning • 200 sqft/user • 8 hour work day • 150 Mb of avg data traffic/user over WLAN • Peak usage is 3x (i.e. need to assume 450 Mb data traffic/user) • 0.15 ERLANG of voice load • VoIP connection requires 64Kbps in each direction Assumes 100% wireless

15. Planning: 2. AP Placement Planning • Determine coverage requirements • Are you coverage limited or capacity limited? • What is the required signal strength? • How can you ensure proper coverage? • How many APs? • Location? • What is the optimal AP configuration? • Power, channel, antennas etc • How do you minimize interference?

16. Planning: AP Placement Which signal coverage are you going to assume?

17. Building Material Matters

18. Building Material Matters Concrete construction Dry wall Construction (better coverage with fewer APs)

19. AP Placement Matters Better Coverage with 4APs APs placed inside wiring closet [ Incomplete coverage ]

20. AP TX power matters

21. Coverage target matters

22. Protocol Matters • 802.11b • 11, 5.5, 2, or 1 Mbps • 802.11g, 802.11a • 54, 48, 36, 24, 18, 12, 9, 6 Mbps • 802.11 b/g have a greater range than 802.11a but only have 3 non-overlapping channels • Observed throughput is 50% or lower than the link speed

23. AP Placement Planning Methods • Ad hoc deployment • Best Practices • Site Surveys • Predictive Planning • Predictive Planning with site calibration

24. Ad hoc deployment • Unplanned growth - deploy as you need additional coverage or capacity • Was good 5 yrs ago • Works for 1-2 AP ‘Home’ networks

25. Best Practices • Rule-of-thumb planning • Better than no planning (ad-hoc) • Good for Small deployments 4-5 AP network

26. Site Surveys • On-site visit to take measurements • Can take site characteristics into account • Good for medium to large scale business

27. Predictive Planning • Use of software modeling tools to predict coverage • Accurate Results • Ability to play with ‘What If’ scenarios • Scalable • Good for all size deployments

28. Predictive Planning with Site Calibration • Predictive planning combined with a sample on-site measurement • Good accuracy • Accounts for modeling and other human errors • ‘What If’ scenarios • Scalable

29. 95% 120% Increase in Network Performance 100% 80% 60% 60% 50% 35% 40% Reduction in Planning Cost 20% 0% RF Predict Best Practices Ad-hoc Deployment Site Surveys 0% Reduction in Planning Time 20% 5% 10% 10% 1% 3% 10% 40% 60% 80% Reduction in Equipment Cost 54% 100% 71% 69% 120% 100% 100% 100% Predictive Planning vs. Alternative Methods

30. Voice over Wi-Fi Deployment Challenges • Planning • Monitoring • Security

31. VoWiFi Challenges: Monitoring • Link capacity fluctuates over time • Link quality is not guaranteed

32. Coverage Fluctuates Signal fluctuates because of multipath fading and people movement. Provision enough link margin ( ~ 10dB) for reliable coverage

33. Link Capacity Fluctuation • Channel is shared & all active devices have equal access to the medium • Data/Voice is carried on the same channel and data applications tend to hog all available capacity • Issue 1 & 2 being addressed by 802.11e • Interference from neighbor APs can reduce channel capacity (SIR should be well above 15 dB) • Noise from other EM sources can also reduce channel capacity. (SNR ratio should be well above 15 dB)

34. Link Quality is not Guaranteed • Packet loss rate is higher due to • Interference from co-channel and adjacent channel WLAN devices • Noise from other sources (Microwaves, bluetooth etc) • Collisions in the medium • Frequent connection/reconnection due to • Hand-offs • Quality of signal – client may start scanning for better connection • Dead spots

35. Solution: Live Monitoring Sample Live Monitoring Charts Required to ensure on-going optimal network performance

36. Voice over Wi-Fi Deployment Challenges • Planning • Monitoring • Security

37. VoWiFi Challenges: Security • Wi-Fi is inherently insecure • Signal bleeds through walls and windows • No central point of control • Easy to break in if proper security standards are not used • Legacy VoWiFi devices don’t support latest security standards • Wi-Fi networks can be easily disrupted • DoS attacks are easy to launch • Usual security precautions don’t work against DoS

38. Solution: Live Security Wireless Intrusion Prevention System (WIPS) • Provides 24 x 7 security coverage • Three key functions: • Detects and automatically classifies wireless events & devices – to determine which are threats are which are not • Robustly prevents (multiple) wireless threats • Accurately locates wireless threats

39. Deployment Best Practice

40. Deployment Best Practice • Plan • Anticipate performance needs of VoIP application in advance. Deploy/configure WiFi infrastructure to obtain the best possible performance • Monitor • Monitor for changes that cannot be anticipated at the planning stage. Adjust network configuration to respond to environment changes • Secure • Protect against malicious threats that can disrupt VoIP application • Protect VoWiFi infrastucture vulnerabilities that can easily be exploited to breach corporate network security

41. Deployment Best Practice

42. Take Away • Analyze current and future requirements • Use a planning tool to help meet the requirements • Perform on-site measurements if necessary • Invest in a live monitoring and security system

43. n a l P VoWiFi r o t i n S o e M c u r e Questions?