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White Paper

Audiovisual communication in a wireless IPTV network for fans in sports venues

São Paulo, 25th October, 2013

Author:

Eduardo Mace, Managing Director and Lead Innovator, DX Networks

Consultants:

Virgilio do Amaral, Communications Expert (ex-VP Telefonica Brazil, ex-VP Direct TV Brazil)

Erick Galassi, Lead R&D at DX Networks

About This document is a analysis of the challenges in, and strategies used for, deploying multicast/unicast

video to smartphone applications with wireless connectivity in several high-density environment

configurations where capacity, reliability and mission critical delivery tasks are essential. It is a summary

of options for both the technical expert as well as the high-level business executive in the process of

decision-making.

Introduction Many sports venues drive fan engagement by offering a full set of video feeds that give an insider’s view

of the event unfolding, which in turn should allow for a better event experience for the fans. The

average fan that attends events of sports venues – from golf courses to football stadiums – has the

ability to watch video using his smartphone, and the connectivity options for the majority of devices to

receive data streams are limited to Wi-Fi, 3G and Bluetooth. Of the communication layers only Wi-Fi

offers a path for video stream delivery to the current smartphone.

As more Wi-Fi capable devices enter the market the average number of devices in any given area of a

network increases. In the case of extremely dense venues such as sports venues, these dense

populations introduce stress on the network and require specific design considerations. There are a

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number of factors that can impact a high-density Wi-Fi distribution and smartphone ready environment,

including:

1. Network performance requirements

2. Number and density of clients

3. Wi-Fi capabilities of clients

4. Current RF environment

5. Wi-Fi capabilities of AP (access point) hardware

6. Number and density of APs

7. AP mounting and antennas

8. Network and server Infrastructure

9. Device application requirements

Each of these conditions can potentially cause severe network degradation. This document addresses

strategies used to resolve performance issues and increase overall experience for the in-venue sport fan.

There are many types of sports environments and each may have its own unique requirements. This

document will address how DX is a fundamental in overall video delivery, distribution and delivery

solution for environments such as those found in stadiums and arenas, plus offer possible

implementation strategies for open field sports.

Challenges Most sports venues have a dense population of devices which in turn require unique Wi-Fi network

design and flexible infrastructure to application strategies. Different sports venues have different

coverage areas and target capacities. The key difference here is capacity as shown below:

Table A. - Coverage vs capacity in dense Wi-Fi environments

Description Coverage Capacity

Number of APs Prefer low Prefer high

Limiting factor Path loss Interference – spectrum and multi-path

Obstacles Bad Good

Radio Frequency (RF) Lower is better Higher is better

Antenna Omni is better for area Directional is better for range

MIMO is better

AP placement Higher is better Lower is better

RF Metric Signal-to-noise ratio Signal-to-interference-plus-noise ratio

The desired capacity for a given application like video streaming has to consider not only the RF

environment but also how the network will respond to the challenge of delivering through this medium.

The first thing that any high density design should determine and document are the key performance

metrics. The service requirements for the target applications define the minimum device requirements

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for successful operation. These are vital to calculate the number of devices per AP and, from that, the

number of required APs. The second significant part of the design is the number of APs required to meet

the KPIs. This number is critical but cannot be determined based on KPIs alone. There are several other

factors that will impact overall performance, AP capacity and consequently the number of APs. These

factors include:

Number of devices expected on the Wi-Fi network

Device capability

RF interference

Log On’s experience has been to work with Stadiums and Arenas in Brazil that have a capacity ranging

from 45,000 to 72,000 seats.

This document covers the use of a video application using the DX platform in the server side with a DX

browser application at the client side, and addresses the most common or significant criteria for a

successful deployment in this configuration, using standard but specialized hardware and software from

different vendors. As with any high-density venue, specific deployments may have slightly different

requirements. However, the principles outlined below are applicable for any size venue.

KPI metrics are the ultimate measure of a successful deployment. Therefore, they should be as accurate

as possible. Under estimating requirements will result in poor performance and a design that does not

meet required needs. Over estimating could potentially result in a network that interferes with itself and

reduces overall capacity.

Key Performance Indicators (KPI) for a sports video application and network, with examples:

1. Minimum resolution and bandwidth required to satisfy smartphone video playback

a. Standard Definition video (480 lines) as a minimum resolution for game action sports

b. Audio can be sent at 22KHz, mono, 16-bits in AAC that gives 48Kbps as a minimum -

might not be necessary for video playback in some sports

c. Video sent using h.264 can be at a minimum of 650 Kbps for adaptive unicast streaming

and 950 Kbps for multicast streaming

2. Minimum, maximum and average number of Wi-Fi enabled devices – for soccer stadium in Brazil

with 45.000 seats:

a. Minimum smartphone carrying attendees: 8,000

b. Maximum smartphone carrying attendees: 35,000

c. Average number lies within 16,000 to 20,000 smartphones

3. The expected number of active Wi-Fi devices at peak traffic time

a. Free service main game: 11,000

b. Paid service main game: 2,800

4. Maximum latency and jitter tolerated

a. Game action sports - normally from capture to delivery latency can be tolerated up to

10 second in the case of soccer. Value might be lower for other sports.

b. Racing animal action sports – normal tolerance up to 5 seconds

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c. Racing machine action sports – tolerance drops to 2 to 3 seconds

5. Service coverage area

a. Soccer Stadium – Seats arranged in oval shaped circle with maximum radius of 100 m

and 50 m vertical with range of 60 m.

b. Horse Racing Arena – Seats arrange in line with 800 m horizontal by 30 m vertical, range

of 50 m.

Using these example KPIs a unicast adaptive stream delivery strategy would require an average of 1

Mbps stream with a peak of 2.800 active streams for the paid service, thus making overall bandwidth 2.8

Gbps in a single Ethernet network leading to the APs. Although this requirement can be satisfied by

current network technology, and, on the server side, unicast streams - especially those using adaptive

technology have high latency times - which are variable per user and can increase with usage time as

bandwidth is demanded can cause a peak on some APs. Also, unicast streams do not scale locally in a

single delivery network, thus limiting the total number of simultaneous users.

Standard IP multicast over Wi-Fi scales easily within the network and are designed to work with

available bandwidth at the APs, without needing to consider the number of active clients. One

consideration in using standard IP multicast over Wi-Fi is that environment conditions and venue design

can make video data packet arrival at the client device multiply, with multi-path effects, causing

demodulation and delivery filters at the client to hinder video quality with artifacts and video signal loss.

Several vendors like Cisco and Aruba have developed antennas, APs, routers, switches and analysers

that can use mixed mode multicast and unicast streams in different parts of the network, which solve

the issues of standard IP multicast over Wi-Fi by prioritizing video over data and converting multicast to

unicast at the best possible data rate at each AP.

Most sports venues use Wi-Fi to allow internet access as well as internal video stream traffic. In this

mixed mode network video streams eat away internet bandwidth. The best strategy is to build a

dedicated video IP delivery network (IPTV) using different Wi-Fi SSIDs and channels from the venues

own setup. This dedicated IPTV is built to be setup easily and can balance the bandwidth traffic at the AP

to allow the main videos to be sent via multicast streams with the remaining bandwidth used for unicast

video streams and data, without interfering with the venues internet connectivity.

Servers

and DX

platform

A/V

Content

Data

Content

Other

Content

Dedicated

IPTV network

Device and

DX

Browser

application

Unicast or

Multicast

Video

Figure 1. – DX Model for Arenas

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As from mid-2013, we recommend setting up wireless networks that use IEEE 802.11ac because of its

future prospects, higher bandwidth and downward compatibility with a, b, g and n type Wi-Fi networks,

as shown below:

Table B. Compatibility and coexistence of 802.11a, 802.11n, and 802.11ac devices

Receiver Role Transmitter

Receiver

802.11a 802.11n 802.11ac

Intended

recipient

802.11a 802.11n device drops

down to 802.11a PPDUs -

Procedure Protocol Data Units

802.11ac device drops

down to 802.11a PPDUs

802.11n 802.11n device drops

down to 802.11n PPDUs

802.11ac

Third-party

recipient

802.11a Waits for the packet length

as indicated in the legacy

portion of the preamble, then

an extra EIFS (so no collisions)

Waits for the packet length

indicated in the legacy

portion of the preamble, then

an extra EIFS (so no collisions)

802.11n as above

802.11ac

Deployment The deployment of a dedicated mobile IPTV network for sports venues starts at the video capture, and

ends with video playback at the user’s smartphone device. This process is separated by five or six layers

of deployment depending on how the video capture is being done at the sports venue.

The crucial aspect of any IPTV network is capacity, or how reliable is the video stream delivery to the

end device. In that respect Log On conducted a series of tests with some local partners in Brazil to

determine latency, bandwidth and coverage, using a Wi-Fi (802.11n) network in a 40.000 seat capacity

stadium in Brazil.

The table below illustrates the throughput reached at the venue with the venues application conducting

a CTS-RTS throughput test at the beginning, with no prioritization for any data:

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Figure 2. - Mixed Wireless Client Performance per AP - 802.11a, b, g and n data rates

In this test using thirty connections, the application throughput to the end user would be 830 Kbps with

all legacy 802.11a connections or 3.8 Mbps with all 802.11n connections. A mix drives throughput down.

This graph shows a moment of the test but over time other variables come into play, with varying user

density, environmental interference and noise, all of which affected the throughput.

With a dedicated IPTV results should be better especially with multicast, as to measure latency it is

necessary to optimize each of the layer in the deployment of the IPTV network from video capture to

device playback:

1. Video capture and post-production

2. Video head-end

3. IT Server infrastructure

4. Network infrastructure

5. Mobile device

6. Mobile application

In these six layers there are more than 12 processes that contribute to overall latency times in a live

IPTV network, all of which need to be optimized and reliable for mission-critical video latency times. Two

crucial layers for reliability of the deployment are the Wi-Fi component of the network layer, the mobile

device layer and the application layer. From the video encoder output in the last part of the head-end

layer, we accessed the times below in each process:

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Table C. - Channel switching in IPTV Multicast over 802.11n network to a static client

Multicast Request, Receive and Display Layer Typical Latency Cumulative

Latency

1 Get IP address and metadata Application/Server < 10 ms

2 Receive IP address Server/Application < 10 ms

3 Send for Access rights Application/Server ~ 10 ms

4 Receive for Access rights Server/Application ~ 10 ms

5 Send Join for channel Y Application/Network < 10 ms

6 AP/Router/Switch gets Join for channel Y Network < 10 ms ~ 40 - 60 ms

7 Router/Switch sends Channel Y to AP Network ~ 30 – 50 ms ~ 70 – 110 ms

8 Routing core aggregate network latency Network ~ 20 – 60ms ~ 90 – 170ms

9 Wi-Fi Latency (multicast > unicast AP) Network ~ 80 – 200 ms ~ 170 - 370 ms

10 De-jitter buffer/Error control Device ~ 300 ms ~ 470 - 670 ms

11 Wait for keyframe Application ~ 250 ms - 500ms ~ 720 ms – 1.17s

12 Video buffer Application ~ 500ms - 1s ~ 1.22s – 2.17s

13 Decode and display Application ~ 50ms ~ 1.27s – 2.175s

As can be derived from the above time readings, the application and the server setup respond for three

quarters of the latency times. In normal IPTV networks these time readings would double due to the

necessary controls in the channel switching times on the server side, and need to adhere to standard in

the application layer.

Deployment can be severely impacted by RF SINR in Wi-Fi and closed Stadium are typically insulated

from interference, but suffer from other challenges like multi-path, especially with excessive power to

the antennas, depending on conditions. MIMO antennas solve that issue but add to latency times when

in auto-channel mode, so in this case it was turned off for better performance.

The Wi-Fi APs in the network layer have a certain capacity, and the number and coverage of APs need to

be determined, to guarantee the capacity of video delivery over the IPTV network. Modern 802.11n or

a/c access points have the capacity to allow up to 512 active connections at once. The maximum

number of client devices a single AP can support with the required KPIs is then calculated as:

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AP aggregate throughput / Minimum bandwidth per client

With a 802.11n AP and a MIMO antenna, the maximum capacity for the example is:

Number of associated clients in the free service = 11,000

Estimated number of concurrent active devices = 50% of 11,000 = 5,500

Minimum bandwidth per client = 1 Mbps

Latency tolerance = low

RF in peak usage = very high

Percentage of retransmissions/loss due to interference = 5%

Estimated throughput per AP = 36 Mbps*

These figures are then calculated:

Maximum clients per AP to meet capacity = 36 (36 Mbps / 1 Mbps per client)

Minimum APs required for number of active devices = 153 APs (5,500 / 36)

Total APs for 11,000 “associated” devices = 22 (11,000 / 512). This number must be

lower than the line above.

Minimum seats covered by AP = 262 (40,000 / 153). This number must fall below total

APs connection capacity.

Using these guides, 153 APs are required assuming the client devices are distributed evenly across all

APs. However this is not a guarantee – some venues change seating areas based on event type, some

open area sports have devices moving about. It is always a good idea to allow for additional APs to cover

the eventuality of higher concentrations where needed, or even to consider a SSID strategy that allows

rudimentary roaming for a moving client. To accurately estimate the weighted average capacity per AP a

simulation of the venue to calculate the SINR of each AP and the entire service area is needed. Most

venues will require additional APs to cover areas outside the main arena. Coverage for concourses,

coaching, player ready area and backstage staging will increase the AP count.

A high density Wi-Fi deployment for a sports venue should rely on configuring the beams of the APs

antennas in an adequate form as to cover all the devices, and use up to three Wi-Fi channels as required

by the venue as in the figure below:

Figure 3 ­ Each colored region is a 3‐dBm beam width coverage of an AP

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When calculating the distances to retain SINR low it is necessary to make the RF analysis as suggested in

appendix A.

* - The 36 Mbps figure above is associated with the OFMD table for -75dBm in 802.11n networks

User Experience The sports fan that downloads the application to his device (iOs, Android or Windows 8) will see a light

video application of less than 8 MB. This application is based on the DX browser and has been

configured at the server side to connect to an undisclosed SSID, then to look for a local IP address that

has either a multicast or unicast video address attached to it and start playing that stream. As the DX

browser application is a full screen video application that hides the status of the phones connection, the

end user is not aware that his internet connection has been put on hold, because he is now connected

to the dedicated IPTV Wi-Fi network. The video browsing of DX allows in video click-through, rapid

channel switching and interactive widgets. Fan engagement features can be easily developed to take

advantage of server side control, the user’s integrated camera and other features of the phone.

IN VENUE NETWORK

CLOUD INFRASTRUCTURE - DX

SIMPLE SCHEMATICS FOR A MOBILE IPTV NETWORK FOR IN VENUE / OUT OF VENUE VIDEO

INTERNET 3G/4G

WI-FI

WI-FI

IN PLACE AT MOST VENUES

DEDICATED IPTV WI-FI NETWORK

IPTV ONLY

ENCODERS

VIDEO CAPTURE

Once the user has downloaded to the smartphone device the DX browser application, it can also extend

seamlessly to out-of-venue mode, through the use of IP and rights filters with DX’s AWS cloud video

distribution architecture. Opening up opportunities in building relationships with a sports fans through

their smartphones with applications like the second screen and video commerce capabilities.

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Additional capabilities of the DX browser application are: server side channel generation, on-line same

channel surfing, playback features, audio-only option, favorites, video marks and social sharing. For a

look at the DX Platform on the server side please visit our website at http://www.dx.tv.br .

Conclusion Great concern is given to the deployment of the wireless component of a multicast network as to ensure

quality of service, and careful planning and implementation in this component is necessary to good

coverage and great capacity of the network as whole. It is through the management of the end-user

application on the mobile device and its server side aspects that we achieve low latency times and rich

interactive media features for fan engagement.

The exploration of a dedicated mobile IPTV network can have a profound impact on sports venue

services and fan engagement. Through the use of the comprehensive deployment process summarized

here any venue can have their own IPTV for in-venue and out-of-venue fan engagement.

DX Networks, São Paulo, 25th October, 2013

Eduardo Mace, Managing Director and Lead Innovator, DX Networks

Consultants:

Virgilio do Amaral, Communications Expert (ex-VP Telefonica Brazil, ex-VP Direct TV Brazil)

Erick Galassi, Head of R&D, DX Networks at Log On

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Appendix A - Wi-Fi RF ANALYSIS

EN303 & others BCM 4330 & others

Smartphone devices min avg Mobile phones TX Power 14 21 Mobile phones RX Sensitivity -70 -87 M-Antenna Cable loss/Supression 3 0 M-Antenna Gain (2.4 GHz) 2 7

MOBILE EIRP 13 28 MOBILE TX SIGNAL (RSSI) -72.02

-71.87

should be lower than

MER - noise, phase noise, carrier suppr., distortion, etc. STADIUM 10% 5% GOLF COURSE

Distance (miles) dBi dBi Distance (miles)

FREE SPACE PATH LOSS (2.4GHZ) 0.045 77.29 95.11 0.35

72.45

563.5

WAP/ANTENNA TX SIGNAL (RSSI) meters -38.29 -55.11 meters

WAP/ANTENNA EIRP 39 40

Horizontal coverage (metres) at end point 31.80

247.31

CISCO TERRAWAVE Dense MIMO Antenna AIR-ANT25137NP-R M6140140MP1D0006 W-Antenna Gain (2.4 GHz) 13 14 W-Antenna Cable loss 3 3 W-Antenna Ports (2.4 GHz) 3 4 W-Antenna H range (degrees) 35 35 CISCO CISCO 2.4 GHz / External WAP Aironet 1530E Aironet 1530E WAP TX Power 29 29 WAP RX Sensitivity -73 -73 this number

WAP Antennas 3 3