Planning for VoWiFi Jai Rawat, AirTight Networks

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

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 ( 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

RF Basics

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

Antenna Basics Isotropic Dipole High gain directional 0 dB i 2.2 dB i 14 dB i

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

VoWi-Fi Deployment Challenges

Voice over Wi-Fi Deployment Challenges Planning Monitoring Security

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

VoWiFi Challenges: Planning 1.Capacity Planning 2.AP Placement and Configuration Planning

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?

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 Call radius50 ft Users39 Active Phone Lines12 Concentration X:13.25 Bandwidth (Mbps) Voice Uplink0.77 Voice Downlink0.77 Data Downlink3.25 Data Uplink1.63 Total Throughput6.41 Assumes 100% wireless

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?

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

Building Material Matters Material typeAttenuation in 2.4Ghz band 6” Brick wall4.4 dB Concrete slab10 dB Dry walls4 dB Cubicle [Wood/Sheetrock] 2 dB

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

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

AP TX power matters AP TX power# AP required (for similar coverage) 100 mW3 50 mW5 30 mW7 20 mW8 5 mW9 1 mW10

Coverage target matters Coverage target [TX Power 100mW] Number of AP required -70 mW7 -75 mW5 -80 mW4 -85 mW3

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

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

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 Negatives Not scalable Bad Performance Interference Less Reliability Suboptimal AP utilization Low (No) Manageability

Best Practices Rule-of-thumb planning Better than no planning (ad-hoc) Good for Small deployments 4-5 AP network Negatives Site characteristics are not modeled Low reliability Underperforming network Suboptimal AP Utilization Can be very misleading

Site Surveys On-site visit to take measurements Can take site characteristics into account Good for medium to large scale business Negatives Cost Repetitive and Time Consuming May not be scalable Doesn’t provide a complete picture

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 Negatives Accuracy is only as good as the site model created May not be possible to model certain environments

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 Negatives Cost – requires site visit

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

Voice over Wi-Fi Deployment Challenges Planning Monitoring Security

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

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

Link Capacity Fluctuation 1.Channel is shared & all active devices have equal access to the medium 2.Data/Voice is carried on the same channel and data applications tend to hog all available capacity Issue 1 & 2 being addressed by e 3.Interference from neighbor APs can reduce channel capacity (SIR should be well above 15 dB) 4.Noise from other EM sources can also reduce channel capacity. (SNR ratio should be well above 15 dB)

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

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

Voice over Wi-Fi Deployment Challenges Planning Monitoring Security

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

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

Deployment Best Practice

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

Deployment Best Practice Factors affecting WiFi performance Pre-deployment Planning Live Monitoring Detect & Prevent Threats Site layout, construction material Co-channel interference from deployed AP Co-channel interference from neighbor APs and clients Can only be estimated when the network is in operation Usage, Contention, Traffic Dynamic and can only be measured when the network is operational NoiseNoise level can change over time Security (e.g. DoS attacks) Need to detect & respond in real-time

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

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