By Haig Sarkissian – Wireless 20/20
What happens when you put 80,000 people in a stadium and arm them with smartphones that transmit and receive high speed data? They will likely generate massive amounts of data traffic. Users at event venues are known to be taking pictures and videos and sharing them on their social network sites or with friends and family. They are often viewing video clips of replays of their favorite game or checking on facts and statistics of their team. This trend is expected to accelerate over time as more people are likely to use more data during these events. Unfortunately, today’s stadiums are not equipped with the network gear necessary to support this massive data.
Stadiums represent one of the most challenging settings for MNOs, who have been struggling to provide sufficient data capacity to fans. Initially, distributed antenna systems (DAS) were deployed in order to provide 2G and voice coverage, followed by 3G data capacity. But these systems were quickly overwhelmed by the tremendous growth in data traffic, driven by smartphones, mobile laptops and tablets. Service providers and venue owners are on their second or third rip-and-replace cycles of their networks. They are trying to understand the magnitude of data consumption during a four-hour event and predict the pace of growth in the future, in search for a network solution that will meet the growing demand of their users for the coming years and avoiding frequent rip-and-replacement of their networks.
To help Mobile Network Operators (MNOs) and venue owners simulate the impact of deploying Wi-Fi and 4G capacity in high-traffic density venues, such as stadiums, arenas and airports, Wireless 20/20 has introduced a new WiROI Venue Tool that simulates the impact of tens of thousands of users using smart phones in a venue and aids MNOs in determining whether to deploy a Wi-Fi network or an LTE Small Cell network, or both in combination, in order to provide sufficient data capacity. The WiROI Tool can be used to project data growth over a 10-year period to help analyze how a network could be deployed to meet the growing needs of users. The following case study was prepared using the WiROI Venue Tool.
Stadium Case Study
Assuming a stadium holds 80,000 people, out of which 50 percent are equipped with smart phones, the challenge of providing data capacity for 40,000 users packed in a 250 by 200 meter area (50,000 square meters) becomes obvious. In order to provide 6 Mbps service with an oversubscription rate of 30:1, which translates to a minimum speed of 200 Kbps, the radio access capacity required would be 8 Gbps (40,000 by 200 kbps) during the busy hour.
Small Cells to the Rescue
Small cells are an ideal solution for providing capacity in high-traffic and high-density environments. A typical small cell, which can provide 40 Mbps capacity per sector (4bps/Hz over 10 MHz bandwidth), seems to be a great match for this capacity challenge. It will take 200 (8 Gbps/40 Mbps) small cells to provide such capacity, if omni-directional small cells were used. If small cells capable of three sectors are used, then the number of small cells needed would be 200/3 = 67 in the first year. As the number of users equipped with data consuming devices increases over the years, and if data consumption per user increases by just 20 percent year-over-year, the number of omni-directional small cells needed would grow to over 2,000 over a 10-year period.
One of the challenges of a small cell network is that it is usually specific to a single service provider and provides coverage and capacity to the users of the service provider for which the network was installed. If AT&T deploys a small cell network at a venue, it is unlikely that Verizon or Sprint subscribers will be able to use this small cell network. In addition, in order to make maximum utilization of 3G and 4G bandwidth, it is imperative that each service provider installs a small cell network to serve its own subscribers. Table 1 shows the number of cell sites and the aggregate amount of capacity as a result of deploying multiple small cell networks by the leading service providers in a given venue.
Multi-Service Provider Small Cells
Deploying four separate small cell networks will carry a high installation and cabling cost. The DAS industry has figured out how to install a single DAS system that is able to support multiple service providers. Obviously, a single fiber wiring system could provide connectivity for multiple service providers’ small cell networks. Ideally, a Small Cell Hotel platform, promoted by companies like Ubiquisys, acquired by Cisco in April 2013, may hold the key to economically deploying multi service provider small cell networks. DAS companies like Mobile Access, TE Connectivity and SOLID are attempting to meet the challenge of installing a robust wiring infrastructure that could handle the increasing capacity needs of stadiums. Technological innovation, along with evolving business models, will determine when and if we will see a consolidated approach to small cell deployments in such venues as the stadium.
WiFi Provides a Hand Where Small Cells Need it Most
There are many benefits that WiFi technology brings to a stadium environment. First, it adds a significant chunk of spectrum in the 2.4 GHz and 5.8 GHz bands, which can carry additional traffic. Second, WiFi is available in most smart phones and it is carrier neutral―meaning subscribers of all carriers can benefit from it.
WiFi comes in 802.11a,b,g,n flavors. There is also 802.11ac technology coming down the pipeline. Dual band WiFi access points can add significant capacity to small cells in a stadium environment, where the cell radii of WiFi and small cells are comparable. An 802.11bg access point in the 2.4 GHz band can easily provide an additional 10-20 Mbps capacity when embedded into a small cell. An 802.11n access point in the 5.8 GHz capacity can provide significant increase in network capacity. Although theoretical speeds of 802.11n access points can reach 300 Mbps, the average throughput is limited by the mix of devices connected to it. Today’s smart phone supports 20-40 Mbps speeds, which will dictate the average throughput of an 802.11n access point. Dual bend WiFi access points embedded in small cells can add 30-60 Mbps capacity while utilizing the same enclosure and backhaul of the 3G/4G small cells.
WiROI Venue Modeling Tool
The WiROI Venue Tool allows MNOs and venue owners to calculate the impact on OpEx and CapEx, as well as visualize the impact of offloading traffic from the LTE 4G network to a Wi-Fi network, allowing MNOs to analyze the most efficient deployment, determine the investment required, and optimize their configuration of the offload network to maximize ROI.
In the Stadium case study, deploying WiFi, in addition to Small Cells, yielded the minimum number of installations in order to provide the growing demand of a stadium while minimizing the total cost of ownership for installing and operating the network.
(For a complete analysis and assumptions, refer to the case study details here.)
The WiROI Venue Tool can estimate the capacity requirements over a 10-year period by simulating subscriber growth and changing usage patterns. This model can then be used to effectively plan a technology roadmap to help ensure that the network deployed does not quickly become obsolete.
The stadium represents a microcosm of what the future may look like in public venues and high traffic density areas. This model will provide valuable learning for equipment vendors, systems integrators and service providers on planning future-proof high capacity networks.
About the Author
Haig Sarkissian is the Principal Consultant for Wireless 20/20. Mr. Sarkissian brings 25 years of experience in the telecommunications industry with focus on the wireless communication markets. As a consultant he advises leading 3G/4G service providers and OEMs on strategy, target market definition, technology assessment & selections, as well as partnership development and investments. His clients span from start-ups to Fortune 100 companies. Prior to his consulting career, Sarkissian was VP of Sales and Marketing at Data Race and held senior management positions at AT&T. He holds a BSEE from Pratt Institute and an MSEE from Polytechnic University.