ZTE SmallerCell Solution for LTE Indoor Coverage

The mobile broadband (MBB) is a technical and customer-required trend in the ecosystem. With the technology evolution LTE will be a unique choice for the MBB services. It is forecasted that by 2015, 94% of traffic will be data and 74% of this will be generated indoors. From 3G operation experience more than 50% mobile traffic occurs in the in-building areas and almost 80% high speed data services happen indoor. So the indoor coverage will be a key issue in the MBB stage.

There are some system requirements for indoor coverage, such as large capacity with the easy way to be upgraded. In this case it can begin with a small capacity and be smoothly upgraded to a lager capacity in the coming future to provide enough resources to mass users. In the equipments side they should be low cost and low power consumption with small size, portable and easy installation. The easy operation and maintenance are also requirements for the indoor coverage system.

Solutions for indoor coverage

In 2G and 3G stage there are some traditional solutions for indoor coverage, for example, macro cell penetration coverage, signal source plus distributed antenna system, and repeaters. Macro cell penetration is a good choice with low frequency band and low data rates. But the high frequency band and high order modulation are weak factors for indoor coverage. LTE will mainly focus on 2.6GHz and cannot have a good penetration for indoor data services. Macro cell is mainly for coverage and commercial showcase of LTE deployment.

The three distributed antenna systems are common usage in the industry. They are passive, active and fiber distributed antenna system. The deployment and upgrade cost of the distributed antenna system is a key issue which operators care about. The traditional signal resource is just a base station without easy way to upgrade.

The repeater solution is mostly applied in the low data rates scenarios. The radio repeaters and fiber repeaters are with hard way to support high capacity.

With the evolution of chipset and hardware architecture there introduced some new ideas for the indoor coverage. In the HSPA stage people introduce the femtocell equipments for the voice and data provision. In the GSM area there also have some kinds of pico equipments for the low data rates and voice provision. All of these types of solutions are not very massive application because of the cost and competitive reasons. The GSM coverage is good enough for the indoor areas because of its long time deployment, low frequency band and with better penetration. The 3G femtocell solution is still on the pre-commercial stage without mature business models. The cost and quite complicated network architecture make it difficult to do fast deployments.

LTE is a real MBB technology with flat network architecture with all IP backhaul support. In LTE stage the real actual traffic and capacity will be provided with smaller cells for high dense area, and these smaller cells are mostly for the indoor services.

ZTE’s SmallerCell solution for LTE indoor coverage

With the many years’ experiences in the indoor coverage, ZTE dedicate to provide the SmallerCell solution for the LTE coverage and mostly focus on the indoor high data rates services. The SmallerCell indoor coverage solution can satisfy different scenarios with different requirements for coverage and capacity. The following figure shows the SmallerCell solution from ZTE,  

Figure 1 ZTE SmallerCell indoor coverage solutions for different scenarios

The femto eNode B is mainly applied in the small coverage and low capacity requirement. It supports up to 4 active users and the total throughput is 50Mbps for downlink, 20Mbps for uplink. The femto gateway is optional in the network, which serves as concentrator on C- plane for many femto eNode Bs.

The solution of micro eNode B plus indoor distributed system (IDS) is a choice for the legacy IDS system. It can maximally reuse the existing resources and make it highlight with small size, lower power consumption and easy installation.

The pico eNode B and pico RRU solution is another choice for large coverage and mid-high capacity indoor areas.

The indoor coverage applications with ZTE SmallerCell solution

The IDS is not available in most buildings, especially supporting 2.6GHz spectrum band. The operators focus more on the fast deployment and easy maintenance in the in-building network infrastructure. Pico eNode Bs are the right choice to meet such requirements. Here are the ZTE’s pico eNode Bs applications for in-building coverage. As shown in follows, the pico eNode B can support not only embedded antennas but also the out-connecting antennas. It’s very flexible to install pico eNode Bs in the right places.  

Figure 2 The SmallerCell solution with pico eNode B networking

When deploying the pico eNode Bs operators care more about the power supply, the installations, the cell capacity, the networking and the backhaul.

In ZTE’s SmallerCell solution the pico eNode B supports 220V AC/110V AC or DC power supply. Taking the DC power supply into considerations, they can be dedicated power lines or the reconstructive telephone cables. With less than 3.5 liter and 3Kg, the pico eNode B is very easy to be installed. The eNode B supports up to 64 active users with 150Mbps in downlink and 75Mbps in uplink. With the help of fractional frequency reuse (FFR) and X2 interface support, the pico eNode B can be flexible networking. The pico eNode B supports FE and GE port with IP clock synchronizations. All the features of ZTE’s pico eNode B are tailor-made from the operators’ requirements.

The pico RRU solution is another choice for the high capacity and high coverage scenarios. ZTE present this solution mainly focusing on the flexible networking and mid-high capacity requirements. The pico RRUs can be applied with the baseband unit (BBU) for the new building coverage. They can also share the macro eNode B’s capacity for the whole building coverage or hot spots, blind spots supplement. The networking and application scenarios are shown in the following figure.　

Figure 3 The SmallerCell solution with pico RRU networking

The advantage of RRU networking is that the capacity is decided by the BBU or the macro eNode B. It’s capable of upgrading with an easy way. When deploying with more than three RRUs, the P-Bridge will be applied to concentrate traffics from RRUs. The power supply of pico RRU can be AC or DC. If adopting DC power supply the P-Bridge is like a power HUB to distribute power to different RRUs by UTP-5 cables.

Conclusions

ZTE has put sufficient resources into the LTE R&D programs, and devoted themselves to delivering tailor-made and future-proof qualitative LTE products and services. ZTE are increasingly committed to carrying out benefits to operators with higher competitive ability and promoting industry development and maturity. With the SmallerCell solution, ZTE is dedicated to be a pioneer to support MBB indoor coverage evolution.