What is a Distributed Antenna System?

Video Description

Distributed antenna systems are almost always referred to as DAS. In simple terms, a DAS is a group of antennas placed throughout a structure or site to boost signal coverage. There are different kinds of DAS differentiated by the types of components that make up the system. Types of DAS we will discuss are fiber backhaul DAS, small cell and off-air DAS. These different types of DAS are differentiated by how they interact with the carrier's cellular network. Fiber backhaul DAS are commonly used in large venues such as stadiums, arenas, and airports. They are appropriate for sites that need both signal coverage and added capacity like a concert or sporting event. These systems are often referred to as legacy DAS, big iron DAS, or traditional DAS. These systems can be expensive, often costing anywhere from two hundred thousand US dollars to over one million dollars. Fiber backhaul DAS require an operator agreement or retransmission agreement, RTA, which can take time to acquire especially if needed from multiple operators. Projects can take up to two years to complete and require specialized equipment such as a base station, dedicated fiber for backhaul, and RF expertise to design, install, and maintain. Installing fiber backhaul DAS is essentially like building a brand new small cellular network to serve just that site. They are appropriate to use when capacity and coverage are needed and the cost is justifiable. Small cells are low-power base stations that are placed throughout a venue and connected first to a base station controller and gateway and then to the carrier's network. Small cells add capacity and coverage to a venue and require backhaul to the carrier's network, but it often doesn't have to be dedicated like for fiber backhaul systems. Similar to legacy DAS, small cells require carrier coordination. In multi-carrier environments, small cells are often not able to be connected to all the carrier's networks or different vendors products are required to cover all carrier networks. This process can complicate and increase the cost of a small cell solution. Off-air DAS systems take advantage of the carriers investment in the outdoor cellular networks. These systems utilize strategically placed antennas to interact with the carrier's network. They do not require fiber or a wired backhaul connection. Within the off-air DAS category, there are two types of systems. The first is passive DAS that use bi-directional amplifiers or BDAs to rebroadcast signals. These repeaters use passive components throughout, resulting in noticeable signal loss and signal degradation. The advantage of an off-air passive DAS is cost. These systems are relatively inexpensive compared to alternatives. When installed correctly, to remediate a specific issue in a small space, a cheap repeater may work. But for reliable commercial use, a more robust solution will pay off in the long run. The other type of off-air DAS is an intelligent off-air DAS. These systems provide outstanding network coverage using active signal amplification components as part of the DAS at an affordable cost. Intelligent off-air DAS will take care of coverage issues quickly by pulling in signals off-air from the outdoor network and using active components to deliver strong reliable connectivity in any indoor space. These systems are appropriate to use in spaces up to one million square feet and where the capacity of the macro network is sufficient. The advantage of intelligent off air gas over passive off air gas is the strength, quality, and coverage footprint of the signal being distributed, offering a noticeably better experience for device end users. For more information about intelligent off- air cellular coverage solutions, visit nextivityinc.com.