Good Article to read - DAS vs. Small Cell Understood

DAS vs. Small Cell Understood

By Michelle Choi of Lease Advisors

The increased use of small cells to supplement cell towers within cellular networks is a significant recent development in the wireless industry. Small cells—typically referring to femtocells, picocells, metrocells, and microcells—are designed with base station capabilities through frequency reuse, which reduces backhaul requirements. Meanwhile, Distributed Antenna Systems (DAS) is comprised of radio units connected by fiber cables to a central hosting location with macrocell base stations. Both DAS and small cells transmit cellular signals from multiple radio frequency (RF) radio heads, but have fundamental differences in capabilities, structure, installation, cost and equipment lifetime that make each suitable in particular situations. One of the biggest differences between DAS and small cells is the ability to support multiple frequencies and carriers. Multiple operators can share a DAS system by connecting their base stations to the shared RF distribution system, making it more affordable. DAS hosts 2G, 3G and 4G frequencies between 700-2500 MHz, while small cells exclusively are single carrier and frequency. DAS also is essentially one large cell while small cells are a network of individual cells. The centralized management of DAS allows the operator to change coverage and capacity of each node within the cell accordingly. DAS was designed to meet the needs of growing networks and has the capability to cover miles, while small cells were designed to deliver over small areas. The installation requirements, costs and lifetimes of DAS and small cells often determine which solution is appropriate depending on resources and needs. DAS networks require careful technical design when positioning antennas and planning for future growth. If designed properly, DAS can cater to future changes with a lifetime of five years while small cells can support future standards like LTE but may need to be swapped upon introduction of a new band of spectrum. The cost of a DAS radio head is more expensive than a small cell, but it would be more accurate to compare cost per Mbps (megabits per second) or per operator. With DAS, the cost per additional band and operator begins to decrease while capacity increases, so there is a tipping point between the cost structures. In which situations are DAS or small cells more appropriate? Small cells are suitable for smaller, low-density applications. As coverage and capacity requirements increase, cost analysis prefers DAS, which are designed to handle large deployments with high density; this makes more sense than deploying hundreds of small cells. Small cells would be suitable for small businesses less than 100,000 sq. ft. DAS becomes a better option for larger buildings, and a combination of DAS and small cells makes the most sense for large venues like stadiums.