According to the latest statistics from the Global Mobile Suppliers Association (GSA), operators in 112 countries around the world have commercially launched 331 LTE networks. It is expected that by the end of 2014, the number of commercial LTE networks around the world will reach 350. With the advent of the global LTE construction wave, domestic operators have also accelerated the pace of LTE construction. There are two types of LTE in China, TD-LTE and FDD LTE, including FDD 1.8GHz, FDD 2.1GHz and TDD 2.6GHz. The 190MHz TDD spectrum and 120MHz FDD spectrum are carefully prepared for the TDD/FDD fusion network. The FDD LTE spectrum is narrower than TD-LTE, and it can take advantage of the good low-frequency band to achieve fast and effective coverage and achieve spectrum diversity. It is foreseeable that if Chinese operators collectively embark on the road of fusion network, not only will TD-LTE establish a complete and powerful industrial chain in China, but even the focus of the FDD LTE industrial chain will shift to China.

The increase in frequency bands makes the antenna feed system increasingly complex, and the deployment of antennas has become a major problem in LTE construction. Under the overall deployment strategy of TDD/FDD hybrid networking, the network is constantly adjusted to meet the needs of development, such as visible coverage, variable area, and dynamically adjustable capacity. Operators hope to ensure that the antenna deployment once meets the network evolution in the next 5 to 7 years, while taking into account the overall investment return and meeting the deployment requirements of "fast, good, and economical". However, the practical problems such as "difficult to obtain" antenna space, "difficult to deploy" due to complex antenna surface, "difficult to go to the station" due to near-end adjustment of tilt angle, and "difficult to access" due to residents' obstruction have also become the most headache for operators.

To solve the antenna deployment problem in the LTE era, multi-frequency ultra-wideband antennas have become the best choice for operators. Multi-frequency ultra-wideband antennas meet the hybrid networking mode of various TDD/FDD scenarios. One antenna supports multiple frequency bands, which can solve the problem of antenna space. At the same time, it reserves possible additional frequency bands to meet the future network evolution and effectively protect the long-term investment of operators.

According to the actual scenario, TDD/FDD hybrid networking is divided into three scenarios: dense urban areas and hot spots, general urban areas, rural areas and suburbs. Demand analysis is carried out for different scenarios, and appropriate antenna selection suggestions are provided in combination with network deployment strategies.

Scenario 1: Dense urban areas and hot spots

Dense urban areas and hot spots have the most concentrated traffic and high demand for data services. They are the main investment areas for operators. The deployment strategy considers the simultaneous construction of FDD and TDD. Due to the coverage differences between different frequency bands, the requirements for downtilt angles are also different. At the same time, dense urban areas and hot spots have high requirements for communication quality. The network needs to be adjusted frequently. When selecting antennas, the need for independent adjustment of different frequency bands needs to be considered.

Taking the LTE full-band (LTE1.8GHz/LTE2.1GHz/LTE2.6GHz) as the target network, in the case of limited antenna space, it is recommended to use a quad-band 8-port antenna (790~960/1710~2690/1710~2170/2490~2690MHz), support TDD 2T2R/FDD 2T2R, support independent adjustment of each frequency band, and support simultaneous deployment of 800MHz and LTE1.8GHz/LTE2.1GHz/LTE2.6GHz.

If the antenna space is not tight, you can choose a three-band 6-port antenna (1710~2690/1710~2170/2490~2690MHz), which supports TDD 2T2R/FDD 2T2R, supports independent adjustment of each frequency band, and supports simultaneous deployment of LTE1.8GHz/LTE2.1GHz/LTE2.6GHz.

Choosing these two antennas for deployment in dense urban areas and hot spots can effectively solve the problem of tight antenna space and reduce the difficulty of property coordination. Remote independent downtilt adjustment and real-time network optimization ensure optimal coverage of different frequency bands.

Scenario 2: General urban areas

General urban areas take into account both coverage and capacity, and at the same time require a reduction in comprehensive investment costs. Considering that the network optimization frequency in general urban areas is relatively low, a combiner can be used to access LTE1.8GHz and LTE2.1GHz on the same port to reduce antenna complexity and deployment costs.

Taking the LTE full-band (LTE1.8GHz/LTE2.1GHz/LTE2.6GHz) as the target network, in the case of limited antenna space, it is recommended to use a three-band antenna with 6 ports (790~960/1710~2690MHz), support TDD 2T2R/FDD 2T2R, support 800MHz and LTE1.8GHz/LTE2.1GHz simultaneous deployment, and reserve LTE2.6GHz to meet future evolution. If the antenna space is not tight, a dual-band 4-port antenna (1710~2690MHz) can be used to support TDD 2T2R/FDD 2T2R, support LTE1.8GHz/LTE2.1GHz simultaneous deployment, and reserve LTE2.6GHz to meet future evolution.

Choosing these two types of antennas for deployment in general urban areas can effectively solve the problem of limited antenna space and avoid the difficulty of property coordination caused by the addition of new systems in the future. The newly added 2.6GHz can adjust the downtilt angle independently to avoid affecting the optimized network.

Scenario 3: Suburban and rural areas

In suburban and rural areas, the traffic volume is low and the demand for data services is not high. The main goal is to achieve wide coverage. It is recommended to select nTnR antennas to improve the network uplink capacity and coverage effect in the same coverage area to meet the needs of wide coverage.

For FDD deployment, if the antenna space is tight, it is recommended to use a tri-band 6-port antenna (790~960/1710~2180MHz), support FDD 1.8GHz 2T4R, and support 800MHz and LTE1.8GHz simultaneous deployment. If the antenna space is not tight, it is recommended to use a dual-band 4-port antenna (1710~2180MHz), support FDD1.8GHz 2T4R.

For operators, the antenna deployment cost should take into account the comprehensive costs such as the cost of a single antenna itself, the cost of antenna acquisition and property coordination, and the rental of the antenna space. If a multi-band ultra-wideband antenna is selected, the cost of the first deployment of the antenna will be higher, but a single antenna greatly reduces the antenna rental cost. In the future, the antenna feed system for newly added frequency bands does not need to be changed, which reduces the cost of adding antennas, property coordination and manual installation costs. The reduction in the number of antennas also makes it easier to manage the entire antenna feed system, improving network optimization and management efficiency. Multi-band ultra-wideband antennas effectively reduce long-term TCO and protect customers' long-term investment, and have gradually become the mainstream antenna choice in the LTE era.

With the increasing application of multi-band ultra-wideband antennas, the industry chain has also become very mature. At present, quad-band and tri-band antennas have been used on a large scale in many European countries. With the large-scale deployment of LTE networks in China, multi-band ultra-wideband antennas will help domestic operators build high-quality LTE networks.