Market research, financial analysis and consulting on wireless technologies and services
Boosting coverage and capacity with active DAS. The transition from passive DAS to active DAS. A white paper sponsored by Corning

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Most wireless traffic originates indoors. According to the HetNet Forum, 70% of mobile voice connections and 80% of mobile data connections are from indoor locations. A sporting event can generate 1 TB of mobile traffic, requiring multiple frequency bands and sectors for each mobile operator. The burden of these connections on network resources is even higher, because transmission from indoor locations to macro cells typically requires modulation schemes that are less efficient and reduce cell capacity. As a result, consistent coverage and high capacity density in indoor locations have become top priorities for mobile operators, both to give subscribers a better QoE and to extract a higher performance from existing network resources. The pressure to improve service in indoor locations is getting more intense as traffic load – and congestion – grow and the outdoor macro network is no longer sufficient to support the services that subscribers demand. This leads to subscriber dissatisfaction and churn, and to lost revenues. 

However, coverage and high capacity in indoor locations are hard to achieve reliably and cost effectively, even with in-building infrastructure. In-building deployments are operationally difficult because venue owners control access to equipment location in the premises. To facilitate deployment and operations, mobile operators often rely on neutral hosts to deploy and manage in-building networks such as DAS. Planning operating an in-building network is also complex, because the coverage and capacity are not uniform across the venue or through time; some areas are used more intensely than others, and some only at certain times of the day or during special events. The need to support multiple access technologies – including Wi-Fi – and multiple operators adds further complexity to in-building networks.

The challenges are similar for both DAS and the main alternative, small cells, as well as hybrid solutions that combine some features of small cells and DAS. One big advantage that DAS has over small cells is the ease of supporting a neutral-host model in which multiple mobile operators can share common infrastructure and operation costs. Operators have yet to develop a scalable and cost-effective model for small cells that supports a neutral-host model. As a result, mobile operators will continue to use DAS for coverage in public venues. With the increasing use of BYOD policies for enterprise mobility, DAS will remain also an important option for enterprise venues in which support for multiple mobile operators is a requirement.

In this paper, we compare two solutions available to mobile operators – passive DAS and active DAS – and discuss how they relate to traffic and capacity requirements, venue topologies, and manageability. The increasing capacity and coverage requirements of indoor networks in high-traffic venues drive mobile operators to transition from the long-established passive DAS to future-proof active DAS, which provides higher performance, scalability, flexibility and functionality – but also comes with a higher price tag and greater complexity. In-building networks require a substantial long-term investment from mobile operators, so it is crucial that they select a robust and future-proof solution that meets their growing needs for both coverage and capacity.

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