20.antenna selection(v0.1)

CDMA Antenna Selection

Improve coverage and reduce exceed-

area handoff；

Improve network quality, enhance

resource utilization efficiency

Reduce the time of network optimization,

and save manpower and material

resources；

Reasons

Frequency and polarization Radiation pattern, horizontal BW, vertical BW and gainDowntiltNull fill and side lobe suppressionFront to Back Ratio,max input power,third order intermodulationsuppression, isolation and so on

Main contents of antenna selection

correspond with system frequency

meet bandwidth requirement

Frequency

Urban：double-polarization antennas；

Suburban and rural：single polarization antennas；

Polarization

Horizontal BW, vertical BW and gain should be considered together.

Horizontal BW, vertical BW and gain

small horizontal BW antenna is suitable for dense urban where the quantities of BTS sites and traffic are large and coverage radius is small；large horizontal BW antenna is suitable for rural and open area where the traffic is small and coverage radius is large

Horizontal BW

small vertical BW antenna is suitable for areas where terrain is plain, buildings are distributed separately and average height is low. Large vertical BW antenna is suitable for complex and big fall terrain. In areas where buildings are densely located and average height is high, if antenna height is lower than average height around, large vertical BW antenna is recommended, otherwise small vertical BW antenna is recommended

Vertical BW

Urbanhorizontal BW: 65°, vertical BW: 7°～10°gain 15～18dBiSuburban and rural

Directional antenna: horizontal BW: 90°, vertical BW: 5°～7°gain: 15～18dBi

Omni antenna: vertical BW: 5°～7°gain: 9～12dBi

Advice for different terrain and clutter (1)

Open area such as water, desert Directional antenna:

horizontal BW: 90° or 105 °, vertical BW: 5°～7°

gain: 14～18dBiOmni antenna:

vertical BW: 5°～7°gain: 9～12dBi

Advice for different terrain and clutter (2)

Narrow and long areas such as road, railway

If the way is straight, antenna should be of 20°～30°

horizontal BW, 5°～7° vertical BW and high gain.

If the way is winding or village and small town need

to be covered at the sides of the way, antenna with

large horizontal BW, 5°～7° vertical BW can be

used.

Advice for different terrain and clutter (3)

Complex and large fall terrainif the height of antenna is higher than that of

coverage areas, the vertical BW can be 10°～18°;if the fall is very large and many coverage areas is higher than the antenna, the vertical BW can be

18°～30°.

Advice for different terrain and clutter (4)

Urban α = arctg ( H / L ) * 180 / π + β/2 – e_γ

Suburban, rural,highway and seaα = arctg ( H / L ) * 180 / π – e_γα: original downtilt，degree；H: height of antenna，meter；L: distance between antenna and coverage boundary, meter；β: vertical BW, degree ；e_γ: electrical downtilt of antenna， degree

Downtilt

sites with small coverage radius and big ; high-level position sites in urban ;Sites with relatively high-level, such as hilltop;high position sites with omni antenna;In other situations that big downtilt is need。

Application situations of electrical downtilt

upper side lobe suppression < －18dBlower null fill > －20dB

Null fill and side lobe suppression

Front to Back Ratio：>25dB。Max input power：>200W。third order intermodulation suppression：

<-150dBC@2×43dBm。Isolation：>30dB。VSWR： <1.5。

Other parameters