In April this year, China Mobile officially launched the centralized procurement of wireless network main equipment for the fifth phase of the 4G network project.

The total procurement scale is about 406,000 base stations and about 1.03 million carrier frequencies. Among them, there are 324,000 new base stations with about 800,000 carrier frequencies, and 82,000 base stations with capacity expansion and about 230,000 carrier frequencies. This scale is the total scale of the five-phase project procurement, and the scale of each supplier will be finally determined according to the actual construction needs of the provincial company.

It is reported that this centralized procurement adopts the method of single-source procurement, and the suppliers include ZTE, Huawei, Ericsson, Nokia, Datang Mobile, Shanghai Bell, Putian and other seven manufacturers. According to the plan, this year's 4G network will focus on guaranteeing scenarios such as "high speed, high traffic, high-rise buildings, and limited uplink". The unique demand scenarios have also spawned the wide application of two key technologies, small cells and multi-antennas.

The proportion of small sites has risen

According to industry insiders, in China Mobile's centralized procurement, small stations accounted for nearly half of the scale, which is the highest in all previous centralized procurements.

In my opinion, this is a very natural phenomenon. After 4 rounds of large-scale construction in the early stage, the number of 4G base stations of China Mobile has reached 1.51 million, basically completing the global coverage of the domestic value market, laying a foundation for its victory in the fierce 4G competition.

However, with the continuous expansion of user scale and changes in user behavior, streaming media services represented by video have gradually become the main source of traffic for 4G networks. If China Mobile wants to achieve greater commercial value in this era of "big connections" and "big video", it must strengthen its in-depth coverage capabilities and continue to increase network capacity. The 4G heterogeneous network represented by small stations has become the hot spot.

According to the previous expectations of the industry, the ratio of macro station to small station is more reasonable in the case of 1:3, which means that there is still a lot of market space for small stations. However, in actual deployment, global operators, including the domestic market, do not deploy a large number of small stations. There are several reasons for this.

The first is demand. The transformation from coverage to capacity requires the transformation of user business form and behavior, which requires continuous market cultivation; secondly, cost, although the single-site cost of small sites is much smaller than that of macro sites However, as an important part of the heterogeneous layered network, the return on investment of the small site is not high, and the network investment income has shown a marginal effect. The third is the difficulty of technical implementation. Although the site form of the small cell is different from that of the macro cell, it is necessary to implement carrier-class features such as protection, delay, and reliability of the macro cell on the small cell. operate.

Commercial multi-antenna technology

In this centralized procurement, in addition to small stations, China Mobile put forward commercial requirements for large-scale antennas and formally purchased them.

As the world's largest mobile communication operator, China Mobile has been planning for the future since a long time, and has improved the existing network capabilities through the 4Gization of 5G technology. Among the many 5G technologies, Massive MIMO/3D MIMO can be said to be the most special. It adopts similar phased array radar technology, through more accurate beamforming ability and multi-user multiplexing system multi-stream capability, to achieve a significant improvement in spectral efficiency, aiming at high capacity, high-level coverage, high interference, and uplink capability improvement in the network Other scenes have good effects.

More importantly, this is a very tricky method. It does not need to change the terminal form and does not completely depend on the terminal industry chain, so that operators can advance the technical dividends of 5G with a small investment. Moreover, large-scale antenna arrays are the key technology of 5G, and the current investment can be fully utilized in the subsequent evolution, and the smooth evolution will also well protect the historical investment.

At present, China Mobile has carried out 3D-MIMO pre-commercial verification in 50 cities in 29 provinces, and has achieved 3D-MIMO multi-scenario commercial deployment in Hangzhou, Shenzhen, Hefei, Luoyang, Shijiazhuang and other places. From the verification results, the introduction of 3D-MIMO can effectively solve some of the problems in "three highs and one restriction (high floors, high traffic, high interference, and limited uplink)". More importantly, with the powerful beamforming capability of 3D MIMO, operators can greatly enhance the user experience at the network edge, thus helping operators to achieve high-definition video experience anytime, anywhere.

However, as a new technology, Massive MIMO still has a certain gap in its industrial maturity and support capability. Among them, the performance-to-price ratio of Massive MIMO is not ideal. Large-scale antennas, the more the number of antennas, the higher the performance, but the cost also increases.

Taking 64 antennas as an example, the procurement cost is equivalent to 3-5 times that of 8 antennas commonly used in 4G networks, and the overall performance is improved by 2-3 times. Therefore, in terms of the construction cost of a single station, the large-scale antenna does not show an advantage over the traditional 8-antenna. However, from an overall point of view, due to the higher capacity of large-scale antennas and more flexible coverage, the difficulty of site selection and optimization caused by the addition of stations and capacity expansion is reduced, the construction cost is reduced, and the maintenance cost is also greatly reduced. Especially in the context of today's increasingly scarce sites, the comprehensive advantages of large-scale antennas have become prominent. At present, with more industrial support, 64 channels and 128 antennas may be a reasonable choice for 3D MIMO commercial use.