BeamHop: A New Member of LTE Base Station Family

At Mobile Asia Expo 2012, ZTE launched its LTE BeamHop solution and demonstrated the LTE A8808 active antenna system (AAS) based on BeamHop. The product is a major breakthrough for high-end wireless markets. It allows operators to quickly and easily benefit from LTE by leveraging their existing 2G and 3G base stations.

Telecom operators are seeking to build new LTE networks while maintaining their existing 2G and 3G networks. As a result, more wireless systems operating at different frequency bands have appeared, and sites where antennas are installed have become more complicated. It is difficult and expensive for operators in developed countries and regions to rent sites for antennas. Base stations of different systems are often co-sited in central cities and in hotspot areas so that 2G/3G can evolve to LTE. Because the available antenna sites are scarce, operators have a pressing need to simplify their existing antenna sites.

Operators also need to smoothly introduce LTE into their existing 2G/3G networks. They seek a simple LTE overlay network for evolution to LTE at low TCO. This, in turn, has caused base stations to become smaller, multiband multimode radio cellular devices that consume less power and perform better. AAS is cost-efficient and can help operators benefit from LTE by leveraging their existing 2G and 3G base stations.

AAS is a new trend in base station architecture (Fig. 1). Current BBU+RRU architecture includes an RF transceiver unit that is close to the antenna. This reduces RF signal insertion loss and improves efficiency. In the new AAS architecture, the BBU also transmits baseband signals to the active antenna unit as in the BBU+RRU architecture. The difference is that an AAS divides transceiver channels using an antenna oscillator with a smaller granularity. The active antenna oscillator is reconfigurable for flexible beam control, dynamic resource allocation and sharing, and MIMO functioning. AAS has a distinct advantage over distributed base stations. It saves antenna site space, improves system reliability, and has no loss.

ZTE’s LTE BeamHop AAS integrates the LTE radio unit into the antenna. By coordinating the multichannel RF and antenna oscillator, AAS implements beamforming and RF signal receiving/transmitting.

ZTE’s LTE BeamHop AAS is the leading commercial solution for active antennas. It supports integration of active and passive antennas, reduces feeder connections, and increases transmission power of the base station and sensitivity of the receivers. This significantly boosts network capacity and coverage. The BeamHop solution also supports MIMO, beamforming, and flexible configuration to suit different coverage scenarios. A new LTE network can be deployed without the need for additional antenna site space. The solution facilitates network construction engineering and is extremely competitive in the developed European and American market where site rent is expensive.

How can an operator deploy an LTE overlay network using the BeamHop solution? ZTE’s LTE A8808 AAS consists of both active and passive antennas. The passive part supports existing GSM and UMTS networks (1800−2100 MHz), and the active part is used for the newly added LTE network (2.6 GHz). When an LTE overlay is deployed on the 2G/3G base station site, the passive part of the AAS can replace the original 2G/3G antenna. The AAS is installed in the same way as the original antenna. 2G/3G RRU is connected to the passive antenna interface, and the connection of antenna feeder remains unchanged. A new LTE overlay network is deployed using the active part of the AAS, and the common public radio interface (CPRI) of the AAS is connected to the BBU’s LTE CPRI. The DC power input interface of the AAS is connected to the power cabinet through the power cable (Fig. 2).

The BeamHop solution is effective for ZTE to tap into high-end European and American wireless markets. ZTE has been committed to developing innovative active antenna products that support wider bandwidth spectrum and more bands. In the era of data services, the BeamHop solution simplifies multinetwork structure and helps operators smoothly evolve their networks for low engineering and construction costs. It is a cost-efficient solution for operators to evolve to 4G.