Analysis of wireless network planning in WCDMA outfield test

After years of development, the mobile communications industry has entered a period of rational development, but also face more and more fierce competition, the future of competitive 3G network should have a higher cost-effective, provide a sound service and first-class network quality, of course, must also be a good network design to fully protect investment. The third generation WCDMA system has introduced the Code Division multiple Access (CDMA), its coverage and load have relevance, so the coverage and load of the community must be combined to consider, at the same time WCDMA will provide a multiple business environment, all kinds of business coverage as well as the upper and lower rows should be considered separately; Planning also takes into account the power control, user distribution, business QoS, mobility and multipath environment, and so on, which makes WCDMA wireless network design planning more complex than GSM programming.

This year, Alcatel Shanghai Bell and Shanghai Telecom, Beijing Netcom Cooperation, the establishment of two WCDMA field test network to participate in the Ministry of Information Industry organization of Mtnet outfield test. Through the test network, the two sides deeply understand the function of WCDMA system and the performance of wireless network, test and evaluate WCDMA business capability, get the basic parameters and means of network design, planning and optimization, accumulate experience of network operation and maintenance, and prepare for large-scale construction of WCDMA commercial network.

The following is a brief introduction of Alcatel Shanghai Bell's fine wireless network planning in Shanghai WCDMA field verification:

1. Shanghai MIIWCDMA Outfield Test Network overview

Shanghai Mii WCDMA Field test Network is composed of a set of UMTS system based on commercial. Including application platform, core network and wireless network, including the RNC two sets, NodeB10 sets, a total of 28 communities (of which 9 directional stations, 1 omni stations). All outfield base stations are connected to the central room RNC through the e12mbps line link. These sites are mainly located in the Xujiahui area, which has a high-density commercial area and a typical urban terrain. (Computer science)

2. Network Planning in Shanghai WCDMA external field Verification

Although the Shanghai outfield only has more than 10 base stations, but also needs the fine network design and the plan, can design the suitable commercial network, obtains the test the success. The success of network planning can be verified from wireless performance test, and it is important to have pilot coverage test, business coverage test, switching test, drop rate test and so on.

Pilot coverage test is carried out in no-load and loading mode, respectively measuring the coverage of the pilot in each base station coverage area. Because the base station of outfield test net is mostly located in the high traffic density urban area, the average pilot coverage range of base station is 1.0km~1.6km. In addition, for different services in different environments (amr12.2kbps, cs64kbps, ps64kbps, ps128kbps, ps384kbps) to test their coverage, through testing can see the AMR business no-load situation, The coverage distance is 1.2km~1.8km, and the coverage of PS384 service can reach about 1.2km, that is, the coverage of low transmission rate service is slightly larger than that of high transmission rate business.

For network coverage, be aware of such two points. The factors that usually affect coverage include the following factors, which should be considered in the design of the network:

• Antenna height, antenna azimuth/dip angle, base station transmitting power, different landform topography;

• Loss on transmission paths, such as reflection, diffraction, diffraction, block of tall buildings, and so on.

Reasonable coverage should be determined according to the results of the wireless network planning:

• The coverage radius of densely populated urban area should not be too large, the best value of network design should be 0.5km~1.5km;

• Too large coverage radius will cause more interference to other communities, affecting the capacity of the system.

The wireless network planning of Shanghai WCDMA field is carried out by using Alcatel9155 tools, and the practical measurement can verify the rationality of station site selection, the height of base station antenna, azimuth angle and the correctness of dip angle. The results show that the actual measured value of pilot field and the predicted value of the network planning are very close to the Shanghai outfield, which proves the accuracy of the Alcatel9155 planning tool and provides a good foundation for future wireless network planning and optimization. In the wireless network performance test of Shanghai WCDMA field, the service signaling and data transmission rate of Alcatel Shanghai Bell are in full compliance with MII test specifications. Among them, soft handoff success rate reached 99.8%, wireless drop rate is zero.

As can be seen from the above tests, Alcatel Shanghai Bell's wireless network design and planning are very accurate, fully able to meet the construction of a competitive 3G commercial network requirements.