Inside – schemes of arrangement of players in the field, statistics on a match and players, plus strimingovy video from cameras that it was possible to see close up in persons on the tablet or phone what occurs. Well and at once repetitions of important points from different foreshortenings.
On radio inspection
Result of inspection of a membrane
For all this fast Wi-Fi of high density and with the minimum interferentsionalny phenomena is necessary. Here not to stick normal hotspot – good examination of radio inspection, plus the special equipment is necessary. Result – 150 cunning access points with beamforming after enough nontrivial works.
Why HD, and in what complexity?
High density concerning Wi-Fi is quite vague and conditional concept. Very much simplifying, this such network condition where there are so many active users how many the wireless network executed on classical design is not able to digest (access points with the omni-directional antennas which are comfortably working at most from 20-30 by clients at the radio interface and with a radius of covering of 15 meters at typical office). Respectively, the special covering (that subscribers and points did not interfere with each other) is required, and still a large number of clients imposes requirements to the flow capacity of all elements of a network: controller, switches, routers, firewalls and, actually, Internet access channels.
During creation of a wireless network for objects with a high density of subscribers which the stadium is, it is required to consider the following factors:
- The total quantity of subscribers – stadium at a full load accomodates 33 000 potential users. Respectively, our network in dive can be loaded in about 30 thousand connections to stream video.
- Density of placement of subscriber devices – the fans sitting in the stands are placed very densely, on 10 square meters 280 people on average accommodate. A key indicator on which rather suitable architecture of a network is checked — required passing capability on the subscriber. Each access point has a certain band passing in a radio channel, evenly sharing between clients, and covering radius. The density of clients is higher, the more clients will be connected to one access point, and the less will be flow capacity on each client. Are logical an output is to put bigger quantity of the end, but we are limited in free radio resources in the range of 2,4 GHz (there are only 3 not crossed channels – 1, 6 and 11), in the range of 5 GHz it is simpler – there are 11 channels, but not all mobile devices support 5 GHz. Therefore, respectively, refuse from 2,4 we cannot. Respectively – it is necessary to reduce a range of points or more precisely to create direction characteristics to reduce a negative impact by the next points working at the same frequencies and optimum to distribute radio resources.
- The characteristics of object of implementation influencing distribution of a signal – a bowl of stadium are a big open space in which an inevitable interference between access points;
The wireless network built on traditional design will not cope with objectives. As a result big losses of packets, a large number of retransmit, and, as a result — extremely low data transmission rate, unstable work of services would turn out.
Reduction of areas of coverage of access points is reached for the account:
- use of specialized narrowly targeted antennas (is more detailed about it below);
- shutdowns of low channel speeds (to 12 Mbps);
- shutdowns of processing of packets of subscribers with the low level of a signal (RX-SOP);
- decelerations of power of the transmitter;
It not all. Still it is required:
- To protect a HD covering zone from Wi-Fi echo. The negative phenomena I can render the points located in VIP-zones, lobbies near outputs in the field on a covering of a spectator zone of a bowl of stadium. The same recipe – control of power and a radio covering.
- To reduce utilization of a radio channel: not to use more than four SSID (to ideally use one) in visual zones since each SSID demands sending separate Beacon of a packet and each broadcasting SSID answers null probe request; to fight with the client - the provoked noises, having suggested the audience to be connected to network Wi-Fi since the attached device begins to send probe request many times more rare; as much as possible to eliminate from an area of coverage of a wireless network foreign access points and Ad Hoc of the device as sources of an interference and generators beacon, probe request, probe response of packets and to refuse use of "adjacent" Wi-Fi of networks and to use a single wireless network.
What was used the equipment
At stadium in Krasnodar Krai we used the solution Cisco Connected Stadium Wi-fi which is turning on new narrowly targeted Cisco AIR-ANT25137NP-R and AIR-ANT2566P4W-R antennas, high-performance dual-band access points of Cisco Aironet 3502P and 3702E in combination with program algorithms for automatic adjustment of a wireless network depending on constantly changing radio-frequency situation and also the CleanAir technology which includes access points with the embedded intellectual hardware functions allowing to reveal, classify and reduce influence of radio-frequency noises. For ensuring monitoring and network management the solution switched on multifunction controllers of wireless networks Cisco WLC 8510 and software of management of infrastructure of Cisco Prime Infrastructure.
Cisco AIR-ANT25137NP-R antenna:
The narrowly targeted sector antenna with support of MIMO. Has 6 elements, on 3 for work in 2.4 and 5 GHz. The BOTTOM beam angle in the range of 2.4 GHz makes 36 ° in the horizontal plane and 36 ° in the vertical plane, in the range of 5 GHz — 55 ° and 48 ° respectively. The body of the antenna provides protection against external influence of dust and moisture on the class IP65. It is developed especially for work together with access point of Cisco Aironet 3502P in the conditions of the high density of clients. It is applied to a covering of stands of stadium.
Cisco AIR-ANT2566P4W-R antenna:
The sector antenna with support of MIMO. Has 4 elements which are at the same time working in 2.4 and 5 GHz. The BOTTOM beam angle in the range of 2.4 GHz makes 65 ° in the horizontal plane and 105 ° in the vertical plane, in the range of 5 GHz — 55 ° and 110 ° respectively. The body of the antenna provides protection against external influence of dust and moisture on the class IP54. It is used together with access point of Cisco Aironet 3702E. The press of zones, zones close to an output in the field and rooms with a high density of subscribers is applied to a covering of stands of stadium, VIP boxes.
Access point of Cisco Aironet 3502P:
The "stadium" dual-band access point which is specially developed for use in places of high concentration of users. The access point is designed and certified for work with the narrowly targeted antennas having gain amount to 13 dB (2.4 GHz) and 7 dB (5 GHz), for example, such as the Cisco AIR-ANT25137NP-R antenna described above. Has enhanced features of settings of a radio transmitter that is irreplaceable at similar installations. It is supplied with the built-in spectrum analyzer (CleanAir technology) that allows to find and avoid radio-frequency noises of any origin. Supports the IEEE 802.11n standard and a configuration of MIMO 2x3 with two space flows.
Access point of Cisco Aironet 3702E:
Dual-band access point with support of the IEEE 802.11ac standard and a configuration of MIMO 4x4 with three space flows. It is supplied with the built-in spectrum analyzer (CleanAir technology) that allows to find and avoid radio-frequency noises of any origin. The press of zones, zones close to an output in the field and rooms with a high density of subscribers, and also in zones with a low density of subscribers together with the dipolar omni-directional antennas AIR-ANT2524DW-R is applied together with the sector AIR-ANT2566P4W-R antenna to the first rows of stands of stadium, VIP boxes.
Controller of a wireless network Cisco WLC 8510:
Centralized control access points is exercised of the high-performance Cisco WLC 8510 controller. This model of controllers supports simultaneous by management up to 6000 access points. Provides the flow volume of 10 Gbit / with and supports simultaneous work to 64000 users that is irreplaceable for similar installations. Fault tolerance of system is reached by consolidation of two controllers in a cluster. Switching time from the active controller on reserve makes less than a second without rupture of sessions of clients.
The controller of a wireless network is responsible for such functions as ensuring safe seamless roaming, automated management of an air (management of carrier frequency and power of radio transmitters of access points), elimination of "holes" in a covering at failure of access points, switching of users from the loaded points on less loaded, detection and avoiding of cross impact of wireless devices and noises, detection of invasions into a wireless network, providing security policies and the politician of QoS.
We were lucky, and the customer addressed while concrete was not filled in yet, and the stadium was only designed. It meant that we could mortgage spaces for the equipment, cable passages and other infrastructure in advance. It is important because except directly Wi-Fi we did still IP TV and Digital Signage — in other words, huge screens with what occurs in the field.
In total at stadium it was necessary to combine about 50 subsystems. For my department everything began with design of our infrastructure. The problem is that the exact arrangement of radio equipment can be revealed only after understanding, what in general forms and from what materials there will be a stadium. It as a sound – needs to be measured to receive an exact picture of distribution of waves. Respectively, in the project we thought over that we could fixed (in particular, it is especially good that it was succeeded to mortgage trasses and these here special slots for the equipment are one photo lower). At this stage there is no understanding, for example, who will do in general a roof therefore it is not enough exact data.
At design we long approved installation sites: let's allow, in passes where people go, it is impossible to install the equipment which will stick out. It requirements of firefighters. We offered options with a shtrobleniye and openings in steel concrete constructions, but here operation decided that the object will begin to fall from such holes ahead of time. Also on this node the architect had esthetic requirements — and in the project mortgaged more than durability. The combination of an esthetics and increase of durability allowed to convince operation, and we designed shtroba for the hidden installation of antennas and access points in thermoboxes.
The following stage — a stage of working documentation. When it became clear who what system does, and is approximately clear what will be applied solutions (at first concrete and constructions is studied, later there was a preparation of working documentation on engineering and automated systems). Feature of a stage is that on building there are changes and sometimes it is necessary to enter editions to working documentation. The main task — to provide all necessary. That there was no it "and here the partition is taken down to hell". It is important to think in advance also because the project has to be within the budget. Here for us the major part – to carry out radio inspection "on live" when concrete is only mortgaged. That is here in it here a status of stadium:
On radio inspection
The following stage of SMR – the most cheerful part on which it is necessary to argue and uphold many solutions with contractors on adjacent systems. Also it is necessary to cooperate with contract which, let us assume, do a roof on which it is necessary to provide fixture which has to allow to operate system easily. We rolled this stage on large objects more than once, especially got a lot of experience on stadiums – we did IT infrastructure and a sound of stadiums of CSKA and Spartak (30 and 44 thousand places respectively).
Here as usual — there is a lot of contractors, and nobody wants to wait for the others during the works. It concerned us too — one contractor laid a plate without our thermoboxes, and it was necessary to look for new thermoboxes for installation. We added the new rule – to carry out purchase after creation of a test node, additional components can be necessary. No matter as well the node was designed by all organizations.
In what complexity of a task?
The main task is evenly to cover a bowl taking into account what users will sit very densely. For increase in density of a covering antennas with a small area of a covering are used, at the expense of it more access points without negative interference are established.
Are for this purpose necessary:
- High gain antennas at frequencies and 2,4 and 5 GHz.
- Surely – with a multichannel reception-transmission (MIMO) 4*4 for increase in flow capacity in a radio channel (but happens that receivers have no MIMO or 1*1). Data transmission rate depends on the MIMO type on client side.
- Further, we consider that we on this project the receiver (the exchange service station, for example, phone) and the transmitter (our antenna) have to be on a line of sight. It is necessary to create all conditions for this purpose that it was executed in the most part of cases.
- It is in the future good to use the standard 802.11ac, but not all devices of users will support it. As well as not all devices of users work for 5 GHz. On future this very good solution – the standard 802.11ac will have a support of MU-MIMO. Multi user MIMO unlike normal Single user MIMO sends a frame to a great number of receivers, but not one. That is the access point with 4 antennas can send one flow to 3 user devices at once to time.
I remind, we did it when only the part of constructions was ready:
Here directly so, on an adhesive tape we test
There was no opportunity to inspect an upper tribune due to the lack of the winch and the crane. More precisely, they were, but it was not possible to approach under a roof. It was necessary to conduct examination on the lower tribune and to do a projection to an upper tribune.
It was very difficult to decide on distance from the antenna on the crane to a tribune in a vertical. We measured distance by the laser. The handheld transceiver did not work for the operator of the crane, it was necessary to shout and use gestures. Process was long. We moved a crane cradle during the day to inspect a quarter, after we projected on an upper tribune results.
On a cradle the measuring equipment fastens, and then …
It rises …
Also represents a piece of a roof.
When the roof was partially ready, called spidermen for check of result. For them we instructed, gave them handheld transceivers. Generally, quickly taught them to do procedure which could not be made without admissions. Thus, carried out an inspection of results of radio inspection and transferring of a projection. As we understood that if the inclination of a tribune both upper, and lower is identical, then results of measurement will match — and this theory was confirmed.
Such schemes turned out here:
Cisco Connected Stadium Wi-Fi is used not only in Krasnodar Krai. These systems supply the American stadiums. Specifically by technical part the acquired experience is. It was far more interesting to the customer to look at financial and practical results of implementation of such infrastructure. Probably, one of the best examples – Connected Stadium system implementation at CONSOL Energy Center stadium (for a soccer team of NHL "Pittsburgh Pingvinz"). There was also HD Wi-Fi, a set of screens as here such:
And the split screens noticeable from stands. And so, the number of advertisers doubled, and sponsor's receipts increased three times. The brand of stadium became more recognizable also memorable. 80% of the audience saved content which they watched at stadium, having relayed it in social networks.
The stadium is not completed now yet. On our subsystem – now we implement system of broadcasting of video of a traffic through Wi-Fi for special mobile application. Feature is that data are transferred to devices by means of multicast. Application of broadcasting of stream video through multicast-mailing considerably reduces load of communication channels, resources of a radiosreda and resources of network equipment. This effect is reached because data from a source are transferred not individually to each receiver (unicast) that produces copies of a uniform traffic, and that the source sends the single copy given along the general route to those receivers who subscribed to newsletter. Benefit of this approach: adding of new users does not involve need of increase in network transmission capacity along the general route to consumers of service. Respectively, load and of the intermediate equipment decreases.
I will answer questions in comments or by mail AFrolov@croc.ru.
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