ZTE TD-SCDMA radio network solution

While focusing the technical characteristics of TD-SCDMA, ZTE is the first manufacturer in the industry that has developed and launched distributed Node B (BBU + RRU). The core idea is to separate the baseband part from the RF part so that the shared baseband resource pool (BBU) is placed in a centralized location, and is connected to the RRU through optical fibers for cost-effective, flexible and quick networking. 
 
　　　　　　　　　　　　　　　　　　　　　　  Figure Distributed Node B (BBU + RRU) Principles

Currently, ZTE provides serialized BBUs and RRUs, the combination of which can meet coverage requirements in various wireless scenarios.

• Large/medium-capacity BBU-ZXTR B328: A large-capacity BBU with the smallest size and power consumption available in the industry, working to meet various large-capacity applications.
• Small-capacity BBU-ZXTR B322: As the smallest BBU (19-inch wide, 2U high) in the industry, it can be mounted either in a rack with a 2U space or on a wall outside the equipment room, helping to meet quick networking needs.
• 4-channel RRU-ZXTR R04: The only 6-carrier tower unit available in the industry, featuring easy expansion. Each channel has a transmitting power of 2W for maximized coverage.
• 1-channel RRU-ZXTR R01: The smallest signal source equipment in the industry specially designed for indoor use, featuring flexible installation, with a transmitting power of 2 W for maximized coverage.

　　　　　　　　　　　　　　　　　　　　　　　    Figure  ZTE TD-SCDMA Serialized Node Bs

 

Serial Number	BBU + RRU Combination	Node B Type
1	B328 + R04	Large/medium-capacity macro Node B
2	B322 + R04	Small-capacity macro Node B
3	B322 + R04	Small-capacity multiple-channel micro Node B
4	B322 + R01	Small-capacity distributed micro Node B
5	B328 + R01	Large-capacity distributed micro Node B
6	B328 + R04 + R01	Large-medium-capacity macro Node B  concurrently allowing for micro coverage

　　　　　　　　　　　　　　　　　　　　　　　　　 Table  ZTE TD-SCDMA Serialized Node B Combination

• Outdoor “third dimension coverage” solution

Network coverage must take into account coverage in special scenarios such as macro coverage, micro coverage and street corners. The TD-SCDMA downtown “cubic coverage” solution: This solution is based on TD-SCDMA multiple-channel characteristics, and takes into account the traditional hierarchical coverage idea. For different coverage scenarios, 8/6/4/1 smart antennas are flexibly selected to concurrently allow for special coverage while providing macro coverage in downtown areas. At the same time, using the flexible-deployment advantages of BBU + RRU, it can meet requirements for coverage in special scenarios without increasing the number of cells, to reduce call drop, balance traffic, and improve network operation indices such as successful handover ratio.

　　　　　　　　　　　　　　　　
　　　　　　　　　　　　　　  Figure  Downtown “third dimension Coverage” Solution

• Indoor “Multiple-Channel” coverage solution

The indoor “multiple-channel” coverage solution fully exploits the characteristics of the BBU + RRU distributed micro Node B. Compared with the traditional micro Node B indoor coverage solution, this solution effectively reduces interference between users, improves coverage quality and user experience, and achieves independent planning of coverage and capacity. In addition, the RRU signal source reliably covers the area without needing any trunk amplifiers. This makes it easier to make good use of an older GSM distributed system, while the multi-channel solution CAPEX and OPEX provide lower cost.

　 
　　　　　　　　　　　　　　　　　　　  Figure  Indoor “Multiple-Channel” Coverage Solution

• HSDPA solution

n the early stages of building the TD-SCDMA network, the equipment hardware must support HSDPA functionality. As the HSDPA service grows, Node B must support 6-carrier/sector. Only this method can ensure that when the network is subsequently upgraded, no outdoor hardware units need to be added or replaced. This saves upgrade costs, while expediting the upgrade process, helping to ensure smooth transition of services.
All ZTE serialized Node B hardware supports HSDPA functions, while the RRU supports six carriers. In the future, HSDPA services can be easily provided via software upgrade.

• TD/GSM hybrid networking solution

In building 3G networks, the early phase of 3G building should rely on the 2G network to reduce overall networking cost via hotspot or local coverage, while considering current 2G network investment along with advantages in network integrity and coverage. In hot downtown areas, to provide continued service capability of 3G services, operators usually consider continued 3G coverage, while the continued coverage of the suburbs and the entire network is provided by the 2G networks.
ZTE recommends adopting a solution of voice (CS domain) TD GSM one-way handover and data (PS domain) TD GSM two-way re-selection. This solution requires a small amount of network transformation, only needing an upgrade of the BSS system information on the radio side. It also supports description of TD cells, thus the upgrade brings low risk. In addition, it fully exploits the coverage advantages of the GSM network, and user perception is no different from a two-way handover. The network roaming time is short to ensure service quality for TD users. The ZTE TD-SCDMA product can support TD/GSM handover and roaming with only a software upgrade to effectively implement TD/GSM hybrid networking.