June 16, 2011 - Sumitomo Electric Industries, Ltd. has successfully developed a remote radio head (RRH) used in a cellular base station for Long Term Evolution (LTE) service, the next generation mobile communication. With this RRH, Sumitomo Electric has realized a wireless output power of 80 W at 2.1 GHz at a low power consumption of less than 270 W, achieving the industry’s highest class efficiency.

RRH for LTE Base Station
The next generation wireless broadband systems, such as LTE and WiMAX networks, have recently come into practical use. In these systems, a new design scheme has been increasingly implemented, where the wireless transceiver known as RRH is separated from the base station to be placed beneath the antenna. This scheme has now become the mainstream in this field for the following advantages:
-Locating the RRH closer to the antenna prevents the power loss caused while transmitting through a long cable. Consequently, the amplifier output to the antenna is lowered, and the total power consumption by the RRH is reduced.
-Conventionally, the base station main equipment needs to be installed near an antenna. With the independent RRH, this is not required, effectively increasing the options for the installation.

In response to this trend, Sumitomo Electric developed the RRH for a WiMAX base station in 2010. The Company has also developed this year a new RRH for an LTE base station by incorporating a higher efficiency power amplifier and the original pre-distorter. This newly developed RRH demonstrates a wireless output of 80 W at a lower power consumption of less than 270 W, achieving an improved efficiency of more than 30%.

Features of the newly developed RRH

(1) High efficiency power amplifier utilizing Envelop Tracking technique
In the orthogonal frequency division multiplexing (OFDM) system, which is applied for LTE and WiMAX wireless communication standards, the modulated signal amplitude fluctuates largely with time. Envelop Tracking technique controls supply voltage to the amplifier in response to the fluctuation, thus significantly improving the efficiency of the power amplifier.

(2) Reduced power consumption, body size and weight
The combined use of a high efficiency amplifier and the original pre-distorter successfully reduces power consumption by the RRH. This improvement minimizes the energy consumed by the entire system as well as operational costs spent by communications companies. This is also beneficial for base stations, which can serve for a longer time after a power outage. Furthermore, its smaller and lighter (less than 20 kg) body eases the installation, allowing the antenna pole or tower to be simplified.

(3) Multi-carrier System
The RRH employs a multi-carrier system to support multiple users in response to the increase in the number of subscribers.

(4) Optical interface
The base station employs the industry-standard Common Public Radio Interface (CPRI).

Based on the specifications of this product, Sumitomo Electric intends to continue its development efforts for the early commercialization of the RRH for LTE base stations. The Company has also created a web site featuring the RRH with the aim of introducing its RRH lineup to the global market.