Enhanced coverage technology of WCDMA NodeB

WCDMA soft capacity refers to a certain extent, the network coverage and system capacity can be exchanged. Because the success of 3G market relies on good network coverage, the enhancement of coverage technology becomes the focus of major operators. With the development and accumulation of GSM and CDMA, ZTE has applied a variety of coverage enhancement techniques in its serialized Node B: 4-day line receiving technology, OSTR Technology, PRU technology, transmitter diversity and high sensitivity receiver. The application of these overlay enhancement technology has greatly improved the quality of wireless network, not only the intangible appreciation of the operators ' investment, but also the service quality of 3G end users.

1. 4 Day Line receiving technology

WCDMA is a self jamming system, the useful signal of the system is almost submerged in all kinds of noise, so it needs an effective method to extract it. 4-day Line receiver is one of the diversity techniques, which can increase the number of finger in rake receiver, greatly improve the sensitivity of the system, and reduce the system's launch requirements for eb/no. The experiment shows that the receiving diversity of 4-day line can increase the sensitivity of the system to up to 23dB, and achieve -130DBM (the protocol is only -125dbm), compared with the ordinary receiving diversity. As the current user terminals generally do not support multiple antennas to receive, so 4-day line reception is mainly used for uplink reception. (Computer science)

Theoretically, the 2dB coverage gain can be in exchange for capacity rise 20~30%, which is of great significance in the initial stage of network construction, considering that the initial number of users and traffic density is small, operators ' business strategy is to cover as many users as possible with limited funds to attract users to use and join WCDMA network. Therefore, this phase of the coverage strategy should be "low traffic, large coverage", 4-day line technology can be a good way to meet this requirement.

2. OTSR Technology

OTSR, which is called omni-direction emission sector receiving technology, is an effective way to reduce investment cost in the initial stage of network construction.

In zhongxing Node B with OTSR technology, the downlink transmitter uses 13 power splitter for omni-direction launch, logically the whole node B is equivalent to a cell, the external form maintains the function of 3 sectors, but its power amplifier, the base to deal with the board resources can be reduced to the normal launch mode of 13. In order to guarantee the effective coverage of the network, 3 sectors were received on the uplink and then merged in the baseband processing board. This implementation pattern can bring up to 6dB of receive gain, thereby effectively increasing the area of uplink coverage.

Generally speaking, the OTSR saves the network construction cost on the downlink link, but effectively increases the network coverage in the uplink.

3. PRU Technology

Remote RF Unit PRU (Remte Radio) is a new type of distributed network coverage mode, it will be large-capacity Acer cellular base station in the central room available, the baseband part of the centralized processing, using optical fiber Node B in the RF module to the remote RF unit, To the site identified by the network planning, thus saving a large number of computer rooms required by the conventional solution, and the conversion between capacity and coverage can be achieved by using large capacity macro base stations to support a large number of optical fiber pulls away.

On the basis of Pru, ZTE has put forward a brand-new network model for WCDMA network: "Operation-dimensional factory", its core idea is to separate baseband processing part from RF module, to centralize the processing of baseband data with "baseband pool", and to pull the RF part to the remote module Pru, Thus constituting a distributed overlay network. The research shows that the network construction of the same scale can save 25% of the initial investment cost by using "Operation-Dimension Factory", and the operating cost of the network can be saved 30%.

4. Emission diversity

The diversity technology is realized by using the independent multipath signal in the Nature wireless communication environment, because of the low possibility of deep fading, it can select two or more signals to merge in multiple signals, which can improve the instantaneous signal-to-noise ratio and average signal-to-noise ratio of the receiving end. The diversity techniques supported in ZTE Node B serialization base station include time diversity, frequency diversity, antenna, space and diversity.

The transmit diversity technology of ZTE Node B design can greatly improve the reception performance of the user terminal, thus increasing the effective coverage range of the system, and the actual test shows that the effective coverage area of the Node B with transmit diversity technology can be increased by about 2dB. In theory, if the effective coverage to improve the 6dB, the system will increase the coverage area 1 time times!

5. High Sensitivity receiver

The sensitivity of the receiver directly affects the coverage of Node B, which also determines the user capacity of the system. In the 3GPP protocol, the reference value of receiver sensitivity is -121dbm, and the receiving sensitivity of ZTE Serial Node B is up to -125dbm due to the use of advanced baseband processing algorithm and RF technology.

These overlay enhancement technology has carried on the overall enhancement to the baseband processing, the RF part as well as the wireless propagation performance, the effective use these technologies, may improve the network coverage 6~2db, thus causes the area to increase 1 time times. Based on this, ZTE's serialized Node B has more outstanding performance and more powerful coverage capability.