Provide Internet access to thousands of people at the same time and place?

Question

I'm planning an event annually where we're expecting over 6,000 attendees in the same big room (it's about 60,000 ft²). There is no wireless network installed, and last year, the cellular network got heavily saturated, so 3G/LTE connectivity was mostly unusable.

I'd really like to provide a more reliable Internet access to everyone, but I have no idea where to start. Could wireless routers be powerful enough to support so many clients, if installed strategically? Or do you know any equipment that could boost the cellular network in the room, just for that evening?

I'm normally familiar with wireless networks, but with this kind of scale I really have no clue... Thanks in advance for your help!

Answer 1

I agree with the previous answer. It is a daunting task to provide reliable wireless Internet access for 6000+ users.

For the past 5 years, I have worked for a company that is specialized in WiFi coverage for schools (some of them with over 1000 users). Big headache.

Firs of all you will need to define what type of service you would like to provide. For example browsing the web is not as demanding as watching Youtube.

Let's asume you want to give a good quality of service for each user while browsing webpages. This will set you at a data rate of 500Kbps per user. This number comes from ITU-T's recommendation for maximum time of non-realtime content load for a good MOS score (10 seconds). For example for a 480p youtube video this means = 1.5Mbps.

Also you need to consider the simultaneity coefficient of concurrent clients trying to access webpages. In a study me and my team conducted on over 10 facilities this proved to be close to 40%. This means that you could consider the simultaneous bandwidth you would need would be 0.4*500Kbps*6000 = 1.2Gbps. That is a big pipe!!

If you can afford to get such bandwidth from your ISP then your next concern is what type of WiFi will my users have (802.11n, b, g or, if you are lucky, 802.11ac). Let's assume you will have mostly new cellphones (802.11n dual-band and above), then you will have a total throughput per cell (per 802.11 5GHz radio, do not even try to turn 2.4GHz on) of 120Mbps (for 30 clients). Due to moderate interference this capacity will drop about 40%. These numbers come from a guide of high density WLAN network design by Cisco and from empirical data me and my team collected on real world cases.

So that leaves you, due to your capacity need of 1.2Gbps, with a need for 17 Access points, that need to be configured properly in order to get the least interference from adjacent cells (for an open environment this means almost every AP in sight). This config should:

• Be centrally administered
  • Tx power auto-adjust for minimum cell size.
  • Force station roaming, no sticky clients please!!
• Forbid slow clients (minimum PHY data-rate of 24Mbps).
• Configure MIMO technology for maximum cell isolation.
• etc.

You also need to buy the correct AP for this type of scenario. Brands that have WiFi stadium coverage should suffice. Such brands are, among others:

• Ruckus Wireless
• Cisco
• Meraki
• Extreme Networks
• Meru
• Xirrus

To sum up, these brands cover stadiums with over 20000 people watching videos at half-time, so it is possible to cover 6000 on an open space. You just need to have the proper configuration and RF planning in order to squeeze the last drop of spectrum from 802.11.

Hope this helps!!

Answer 2

I have been deploying event WiFi networks for 9 years. 6000 people in one room is a challenge. To deliver a good service will take a significant investment in time and money. Franco's advice on bandwidth and spectrum usage is very good, here are some additional tips from an event wifi 'veteran'.

If you have not previously designed, deployed and managed a high density WiFi network for an event I would strongly suggest working with a consultant or specialist Event WiFi company. I have contacts worldwide if you need recommendations/introductions.

Having said that, some tips....

1. How many concurrent users do you need to support? You state 6000 users are in the same room at the same time, the profile of these users is critical. Is it a technology focused audience? Will they have more than one device? Do you expect all users to be connected and active (using their device online) at the same time?

Answering these questions will give you some idea of how many concurrently active devices need to be supported at one time. For our purposes here we will say that 3000 concurrently active devices must be supported.

2. Spectrum planning. In a wired network capacity planning is simple for wireless it is exceptionally complex. The shared resource is the bandwidth available in the air, this is a finite resource and has tobe managed very carefully.

Firstly you should expect to use only 20MHz channels for both 802.11a and 802.11gn.

Secondly, disable all legacy data rates (or set the network to OFDM only depending on the particular vendor's nomenclature). Essentially, you are turning off 802.11b.

Third. Coverage. Identify areas where you will have very high crowd density and device usage. You must deploy enterprise grade hardware as Franco correctly states. My experience is with Ruckus (my personal favourite), Xirrus and Cisco. I have also used Ubiquiti extensively but this is best suited to small scale deployments and office type networks.

A note here about physical access point location. In large venues we typically see a very high roof space. That can make life hard for delivering a good signal so my recommendation for your circumstance is to mount Access points approx 1m to 2m max above head height using tripods where necessary.

Make your cell sizes, the area of coverage for each access point as compact as possible. This is achieved manually by reducing transmit power. Both Cisco and Ruckus have very good automatic cell adjustment systems within their controllers.

Band steering. This forces 5GHz capable clients to connect with 5GHz radios. Different vendors have different names for this function but they all operate in a similar fashion. Why do you want clients on 5GHz? It is like a 16 lane superhighway vs the 3 lane motorway of 2.4GHz.

3. Bandwidth. 10Mbps per 100 users is our standard rule unless you are expecting a great deal of video traffic (inbound or outbound).

4. Switching. POE enabled gigabit switches are a must have, core to edge. You should put all guest WiFi in separate vlan to management, organisers, exhibitors etc.

5. Routing/Firewalls. Your DHCP scope planning is important here. Also consider dynamic vlans to separate broadcast domains and reduce broadcast traffic in the air.

6. keep SSIDs/Networks to a minimum. More SSIDs = more broadcast traffic (and it's exponential) and you want to keep as much spectrum available for client traffic as possible.Guest network (open), Organisers network (WPA2/AES), exhibitor/Contractor network (WPA2/AES).

7. Caffeine sources. Must be of high quality and within arms reach. Coffee is good, Red Bull only in extreme circumstances...such as working straight for 24+ hours. If you pursue a career in this field you will be doing that.

8. Rate limiting. A topic of much discussion in our world. I belong to the "let it fly" camp. Don't limit client bandwidth, get the traffic on and off the air as fast as possible in order to best utilise available spectrum. Most client traffic is bursty unless it is streaming video.

9. Apple updates. They can kill a network. Block access or ask users to refrain from upgrading their iOS or 65 apps on your network.

10. Please share the 7 deadly sins of conference wifi with your guests.

Good Luck!

Answer 3

It would actually be easier to network the entire room with ethernet and switches and run everyone through a data cap per line with the requirement that anyone who needs access has to register beforehand and bring a device capable of wired access.

Disclaimer: While I have worked with wireless a lot and have read and attempted to research large installs I do not have any first hand experience with anything over 100 users per room, this is just some of what I have learned from years of puzzling over possibilities and reading varied sources.

In my experience it's very difficult to get good performance out of wireless APs that are installed in any area with less than 50ft of clearance (just in general terms) + you would have the added difficulty of actually providing enough internet to service the backbone for the wireless.

Sadly the cellular option probably isn't possible due to the same wireless limitations that are common with APs, regardless these are some things you will want to look into to check the overall usefulness of that option.

• "So I would try improve the cellular reception instead. However you will have to keep in mind that cellular reception is wireless just like wireless internet just on a better standard so you will run into some of the same limitations. You will also be limited by the amount of nearby towers and the bandwidth going to those towers so I would strongly encourage giving the local cellular providers a call and seeing what kind of limitations are common for a given area/number of towers. Even if you improve the signal it won't be any good if the local towers can't keep up with it."

Things to keep in mind if you try to go the wireless AP route.

If you do have to service all the visitors with just wireless access points then I would encourage you to give up on seamless coverage and instead try to layer 2.4 and 5 ghz radios using each radio as a way to increase the distance between radios on the same frequency and band. Just make sure to mark the areas that only have 2.4 and only have 5ghz coverage so everyone won't be caught off guard (I know it's not a good solution but it's the easiest and cheapest way to do it). Keep in mind that if you are assuming that there will be at least 6000 devices at moderate usage levels so it's possible that you will need as many as 240 APs (25 devices per AP, although you can reduce the number of AP by relying on a per radio count I'm not sure if that would be helpful). The radio strength of each AP will need to be set to the lowest strength allowed and it would be best if they were centrally managed to allow automatic dropping of clients that go more than a set distance from the AP (based on the client wireless strength).

If you do attempt to provide internet, make sure to provide enough for everyone attending and actively ban the use of any wireless hotspots since they will only increase the number of wireless conflicts. I would encourage the registration of any visitors devices in advance so you can sort them into 5ghz, 2.4 ghz and low/high bandwidth groups and plan accordingly. Remember to count phones in addition to mobile computing devices and try to see if the visitors will be uploading content to the internet while present. In all honesty I see this as an almost impossible task but it should be doable with enough funds, make sure to bring someone onsite that has experienced it firsthand to minimize issues.