Several key factors are driving the evolution of cell site architectures, with the primary driver being the increasing demand for bandwidth and capacity. This demand is being addressed in a number of differing ways:
While new 3G and 4G technologies like HSPA+ and LTE are being introduced, there is also a need to continue to support legacy technologies like GSM and CDMA for the foreseeable future. The RF path has many directions!
Consequently, radio networks are being required to support multiple technologies (GSM, UMTS and LTE or CDMA, WiMAX, and LTE) in multiple frequency bands simultaneously. Therefore, there is a growing need to integrate the electronics and hardware in a typical base-station to minimize site footprint and lower costs.
Over the last decade, cell site architectures have been evolving from the legacy cell site architecture where large radios are located remote from the antennas, to an architecture wherein a separate RF portion of the radio can be located more closely to the antenna.
This separation of the digital radio, BBU (Base Band Unit), from the analog radio, RRH (Remote Radio Head), allows for a reduction of the equipment footprint at the site and for a more efficient operation of the network. A digital fiber optic link provides the connection between the BBU and RRH, now referred to as FTTA or Fiber to the Antenna.
Traditional design of cellular installations – antenna towers and their adjacent base stations – places the transmitting and receiving components in climate-controlled cabinets or shelters, connected to the antenna arrays via coaxial cable.
As cellular technology has grown more sophisticated in the ways voice and data are managed across the network, the overall power requirements for base stations have inched steadily downward. At the same time, advancements in amplifier technology have moved power efficiency for these stations upward, resulting in fewer power stages required in a given base station. And of course, network providers and service operators have always sought less expensive ways to deliver quality connectivity to their customers.
The new thinking in base station design, embodied in the remote radio head, reflects the emerging realities that drive all of these trends, improving efficiency and reducing operational costs. The difference is in the “distributed base station” concept, which separates the baseband signal processing unit, or BBU, from the RF front-end equipment, collectively called the remote radio head .
Learn more about these technologies at the CommScope Infrastructure Academy. The SP6000 course looks at the complete RF Path, while the SP6920 looks at advanced antenna technology and the SP6170 course covers FTTA. Get CommScope Certified today.