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Mojo Networks @IPL 2018 - Part 2

by Nadeem Akhtar on Jun 19, 2018
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The Holkar Stadium is located in the the city of Indore, approximately 600 km northeast of Mumbai. With a total capacity of 27000, the stadium became the temporary home of the Kings XI Punjab cricket franchise during the second half of Indian Premier League (IPL) 2018 season.

In comparison with the Sawai Man Singh Stadium (SMS) Stadium in Jaipur which we reviewed in a previous blog, there were two key differences in the stadium layout and structure. First, Holkar stadium has covered stands. Hence, walls and ceilings could be used for mounting access points. Second, the stands are multi-level. Therefore, cross-floor interference minimization was very important. As a result of this, the deployment strategy was quite different compared to the WiFi deployment at SMS Stadium.

From the capacity perspective, the estimated AP count for the bowl area was 270. However, the actual number of APs deployed was around 15% more, after taking into account the internal structure of the stands, seating arrangements etc. The O90-N45 directional AP was used for the bowl area. The stadium outer periphery was covered with outdoor, omnidirectional O-90 APs while in the indoor areas such as cafes and offices, C-75 indoor AP was used.

Stadium WiFi image 1

As the stands are all covered, both ceilings and walls could be used for mounting the APs. Existing structures such as beams and pillars were used to create RF isolation. An important consideration here was to void RF spillage across floors, in addition to minimising interference between APs on the same floor. The use of O90-N45 directional AP, coupled with careful selection of AP transmit power and downtilt ensured the desired RF coverage with sufficient overlap between cells, while minimising the interference.  In most of the areas, transmit power was kept low as each AP needed to cover only 10-15m of distance with RSSI higher than -65 dBm.

Stadium WiFi image 2

A complication in this deployment arose when LTE antennas were deployed in both East and West stands, in close proximity of the WiFi Access Points. As the LTE transmitters were operating in 2.3 GHz band, there was strong non-WiFi interference to APs operating on Channel 1. To mitigate this problem, in the affected sections, only channels 6 and 11 were allocated to the APs. A trio of APs that would normally be on channels 1,6 and 11 were assigned channels 11,6 and 11, respectively, bearing in mind that channel 11  was least affected by LTE.

Stadium WiFi image 3

The stadium hosted 4 matches during the IPL 2018 season, played over a period of 10 days. 3 of the matches were playing in the night, starting at 8 PM while the one match (3rd in the series), was played in the afternoon, starting at 4 PM. During all the the matches, 2 SSIDs were radiated - Open SSID for anyone to connect using OTP-based authentication and Private SSID for 4G offload, only for Jio customers.

Stadium WiFi image 4

Highlights

  • 416 APs (indoor and outdoor) deployed to cover the entire stadium including bowl area, offices, food court, corporate boxes.
  • Average data usage per match was 1.5TB
  • 60% traffic on the 5GHz band
  • 17% traffic from 4G offload
  • Average data rate 23 Mbps

In the next blog, we will talk about the challenges faced in these deployments and the learnings gained.

This blog was co-authored by Nadeem Akhtar and Ketan Garg. Part 1 of the blog series is available here.

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Topics: WiFi, Cloud Managed, featured