Mobile Base Station: Introduction of soft Base station

1 Introduction

With the continuous improvement of people's living standards, people pay more attention to health and environmental protection, which objectively makes it more and more difficult for wireless cellular network operators to find suitable cellular sites. For mobile operators, especially the new mobile operators, in the early stage of a network, hope to use a wide-coverage, low-density density of equipment to build a network in order to achieve the minimum cost of achieving the largest coverage purposes, so that the vast number of users to enjoy the good quality network services. However, with the continuous growth of user size and the continuous enrichment of business needs, the network also needs to continuously expand and adjust. Due to technical reasons, in the network expansion and adjustment process, the original continuous coverage of the network, often appear a blind spot or even a piece of blind area, or just the opposite, in some areas to form a traffic heat island, resulting in traffic overflow. At the same time, some special complex terrain coverage, such as subways, basements, indoor, suburban, road, etc., is also a headache. Traditionally, due to the limitations of technology and equipment, operators and network design departments often use the common base station plus repeater to solve these problems. The disadvantage of this approach is that it will bring about increased interference, high drop rate, maintenance difficulties and so on. How to use a technical means to make the network appear "soft" characteristic, make the network has the self-adaptive ability in the planning and optimization, make the expansion, network planning and optimization, business provision and so on become more easy is the question that people always think. In order to solve these problems, a new kind of base station-Soft base station (Soft base station) has been proposed with adaptive ability solution.

The so-called soft base station, refers to in a covered area, a radio frequency unit (called a sub station) is connected with a large capacity baseband processing resource pool (called the main unit) through a fiber or other digital transmission medium, and a shared baseband processing resource, a master clock unit and an operation maintenance platform between RF units, In order to achieve the surrounding adjacent areas covered by the base station system. (Computer science)

2 features of soft base station

2.1 Distributed Overlay (distributed converge)

Because the main unit of the soft base station is connected with the sub station through digital optical transmission equipment, the sub station and the main unit can be separated from the large distance, in the beginning of the network through the main unit pull out of the station, can form a continuous coverage of large areas, especially to solve the urban and suburban continuous coverage problem, Compared with the traditional base station of the same capacity, its covering area can be increased several times or even dozens of times times. Since the sub station of the soft base station contains only the RF part, the volume can be miniaturized, which makes the soft base station flexible to adapt to the complex terrain such as subway, basement and high-rise building, and the coverage under the harsh environment conditions. The series of the base station can be applied to the coverage of expressway, railway and so on. The characteristics of the outdoor design of the 40~60℃ can be adapted to the harsh outdoor environment, which can work well in the environment.

2.2 Softer switching (softer handover)

The sub station of the soft base station shares the base-zone resource pool with the main unit, and the child station can be considered as a sector of the primary unit. The macro-diversity merging of different sectors of the same base station can be carried out in the base station, and the switching between different sectors is softer, so the relationship between the sub station and the Sub station and its main unit is switched to softer switching. The more soft switching macro diversity adopts the maximum ratio merging, which increases the system capacity and reduces the load of the RNC.

2.3 Soft Planning (soft network deployment)

The sub station can be regarded as the remote sector of the main unit, or it can be regarded as a different logical base station of the main unit, and its neighboring base station is unified for PN code planning and carrier frequency planning, and the network planning is simple and easy.

2.4 Soft sites (soft site)

The area covered by the sub station if because of the increase of traffic volume, the growth of data business or the optimization of network adjustment and so on, we need to build large capacity base station, only by adding baseband treatment board on the sub station can become the independent small base station of the main unit and flexibly adapting to the network construction.

2.5 Soft service capability (soft service provision)

Sub-station is only the main unit of the RF remote, the system upgrades only to the main unit can be adapted to network upgrades and business upgrades, network upgrades and business upgrades become very simple.

2.6 Soft compatibility (soft compatibility)

The soft base station has good multi standard, multi-band compatibility, the main unit by calling different software can support different standards, different frequencies and different versions of the user, while the RF remote configuration of different RF devices can support different standards and frequencies, can fully meet the needs of network upgrades, protect user investment.

2.7 Soft Base zone resources (soft capacity)

The base zone of the main unit side of the soft base station adopts resource pool design, and the base zone resource pool is dynamically shared between the different standard sub stations of the soft base station and the different frequencies of the same standard. As a result of the statistical multiplexing of channel resources, the utilization of resources is greatly improved, which means that more resources than regular base stations can achieve the capacity effect of conventional stations. For each child station, the main unit assigns hardware resources to it dynamically according to its requirements. Therefore, the hardware resources of each child station are changed with the time dynamic. Therefore, the baseband resource presents a soft characteristic for the sub station.

3 Technical advantages of soft base station compared with conventional base station + repeater scheme

Compared with the conventional base station + repeater scheme, the soft base station absorbs the advantages of conventional base station + repeater scheme and abandons its disadvantage. The concrete manifestation in the following several aspects:

(1) Increase capacity, expand coverage, reduce interference

The repeater is simply an extension of the primary base station cover and does not provide additional capacity; Repeater uses the same frequency
Forwarding, intermodulation, space interference is serious, reduce the capacity of the donor base station, while bringing down the high rate of speech
Poor quality, switching success rate is low.

The sub station itself is a base station, with the main unit continuous coverage of the more soft switching relationship, due to the increase in gain, reduce interference, increase capacity, expand the coverage area.

(2) Easy to manage and maintain

Repeater needs to establish a set of independent maintenance system, power supply, environment and equipment warning information without uniform standards, can not be unified with other network network management. Repeater stations must be maintained on a regular basis, resulting in heavy maintenance work at a later stage. The sub station of the soft base station is a logical base station, which can be unified with the main unit, and the maintenance and environment monitoring information is reported to the Network Management center through the main unit IUB interface. Maintenance-free, automatic restart after power off.

(3) Easy location

In order to avoid interfering with the main base station, the station site selection of repeater is very high, and the difficulty of selecting stations is often the bottleneck of the whole project construction.

The station site of the soft base station is the same as that of the regular base station, and the location is relatively easy because of its small size and the characteristic of the outdoor environment design.

(4) Support accurate positioning

As the repeater expands the coverage of the main base station, the information obtained by the location query is the latitude and longitude of the base station, which cannot be precisely positioned. The logical base station characteristic of the sub station of the soft base station, the information obtained by the location query is the latitude and longitude of the soft base station, so it supports the precise positioning.

(5) Saving investment

The investment of repeater does not increase the capacity, average per user, increase the cost of investment. Soft base station more soft switching features increased system capacity, average per user, reduced investment. At the same time, because of the shared baseband processing resource pool and the master clock unit between the sub stations and between the sub stations and the main cells, the coverage of the neighboring areas can be realized with fewer baseband processing resources, so it is more provincial than the direct new base station investment.

(6) Higher resource utilization

Because of the dynamic sharing among the sub stations of the main unit baseband processing resources, the resource utilization is greatly improved, and the equipment cost of each user is reduced in disguise.


4 UT soft Base station Solution


Figure 5-1 ut Kangda soft base station scheme