When the TD-SCDMA mainline amplifier is opened, the relationship between the gain adjustment and the influence of the base station must be reasonably grasped on the basis of ensuring link balance, and the mainline amplifier should be properly debugged. The mainline amplifier will also play its biggest role in the large-scale construction of the TD-SCDMA network effect.
With the construction of the TD-SCDMA network, a large number of TD-SCDMA indoor coverage systems have been constructed accordingly. A high-quality TD-SCDMA indoor coverage system is particularly important for mobile operators to improve the overall network quality of TD-SCDMA and increase users' recognition of the new 3G network.
The TD-SCDMA network works in the 2GHz frequency band, and the radio link propagation loss of electromagnetic waves and the propagation loss of RF cables are relatively large. TD-SCDMA indoor coverage must develop high-power active amplification equipment to solve the problem of insufficient coverage power. Trunk amplifiers play an important role in the optimal coverage of 2G mobile communication system networks, and are the most effective means of solving indoor coverage and the most important active power amplification equipment. Because of the characteristics of TD-SCDMA network and system equipment, the application of TD-SCDMA trunk amplifier in TD-SCDMA indoor coverage is more urgent.
The engineering application of the TD-SCDMA trunk amplifier is basically the same as the 2G dry amplifier. In addition to the unique synchronization issues that need to be considered separately, the most important factors in the application are: power utilization, input power control, avoid output oversaturation, up and down Problems such as link balance.
TD-SCDMA dry amplifier gain setting
The gain of the dry put is usually designed to be comparable to the path loss of the dry put to the base station. When the downlink input power in the area covered by the dry amplifier is particularly small (that is, the path loss of the dry base station is particularly large), the gain of the dry amplifier cannot become very large, and the coverage of the dry amplifier will be reduced. When the downlink input power of the area covered by the dry amplifier is large, the dry amplifier should be able to properly control its gain, that is, the dry amplifier should have the function of gain adjustment.
When the path loss of the dry put to the base station is fixed, the higher the uplink gain of the dry put, the greater the influence of the noise of the dry put on the base station noise. An obvious example is that when the uplink gain of the dry put is equal to the path loss of the dry put to the base station, and the noise factor of the dry put is equal to the noise factor of the receiver of the base station, the thermal noise of the dry put superimposed on the input end of the base station will cause The thermal noise of the base station is raised by 3dB. If the gain of the dry put is higher than the path loss of the dry put to the base station, then the influence of the dry heat release noise will be greater. In addition, if the gain of the dry amplifier is too high, the output noise floor of the dry amplifier will be very high, and the spurs of the dry amplifier will be higher than the specifications. In addition, if the gain of the dry amplifier is too low, it is likely that the dry amplifier cannot output at full power in actual use, which will result in a reduction in the coverage of the dry amplifier. The gain setting of the dry amplifier must be considered in combination with various factors.
Design considerations for dry-discharge output power
The total power of the TD-SCDMA base station system is 2W, and the PCCPCH power ratio is generally 29dBm or 26dBm. The total power of the base station varies with the load, but the PCCPCH power is almost unchanged, so we all use the PCCPCH power to calculate the coverage of the system and the link budget for indoor coverage.
The trunk amplifier is a relay device for transparent transmission, and it cannot identify whether the system receives PCCPCH power or service power. When the dry release is turned on, the stable power signal read out in the time domain of 5ms in the frequency spectrum is used as the output of the entire TS0. Therefore, the relationship between TS0 and the total power needs to be considered when the dry release is opened for debugging. The following table shows the typical TS0 power configuration of 2W indoor RRU.
According to the above configuration, the full power of TS0 is about 30.6dBm, and the maximum output power of TS4, TS5, and TS6 is 33dBm when the RRU of full power is 2W and full power is occupied, so the output power of TS0 is 2.4dB lower than the rated power of the base station. Although the main line amplifier has ASLC (Automatic Time Slot Level Control) function, in order to avoid unexpected problems that may occur after the output power of the over-saturation is dry, the output power of the dry-opening should be consistent with the ratio of the TS0 to the rated power of the base station itself , That is, the TS0 power output of the dry discharge is 2.4dB less than the rated power (if the TS0 power configuration is different, this value will change, because the indoor capacity planning is generally considered to be 75%, so the TS0 power configuration produces a change within 1.2dB for dry discharge Normal use will not affect).
Upstream gain setting during dry commissioning
The setting of the uplink gain for dry-release mainly needs to consider the impact on the donor base station. The use of dry put will increase the bottom noise level of the donor base station, thereby affecting the base station's receiving sensitivity and uplink capacity. How can the impact on the base station be small?
The bottom noise level of the base station itself:
PNode = KTB + NFNodeB = -113 + 5 = -108dBm
(KTB Gaussian environmental noise; base station system noise figure NFNodeB = 5dB.)
After the heat radiation noise is amplified and the transmission path loss, the thermal noise level that reaches the input end of the base station receiver:
PIN = KTB + NFrep + Gu-PLoss
(NFrep dry puts upstream noise coefficient; Gu dry puts upstream gain; Ploss puts to base station path attenuation value.)
The base station thermal noise level rises ROT (RiseOverTher-mal): ROT = 10log [(10PNode / 10 + 10PIN / 10) / 10PNode / 10]
It can be seen that the noise increase of the base station by the dry-release is mainly determined by factors such as the uplink noise figure, uplink gain, and path loss of the dry-release, because the uplink noise figure and path loss are usually fixed values, and the only variable is the uplink gain Gu. When the dry-release power is equal to the base station power, the dry-release downlink gain design is equal to the path loss; when the dry-release power is greater than the base station power, the downlink gain design is greater than the path loss. When the dry put down line is a full-gain rated output, the downlink gain is Gd and the dry put noise figure is 5dB.
We hope that the contribution of the dry put to the thermal noise of the base station is as small as possible. In this case, as the uplink gain of the dry put is reduced, the degree of base station noise increase becomes smaller and smaller until it can be ignored. At this time, it is necessary to consider the uplink and downlink balance and Relationship. In addition, the relationship between the effect of dry-release on the noise floor of the base station and the power of dry-release is: under the same conditions, the higher the dry-release power, the higher the gain or path loss of the rated output changes, resulting in an increased impact on the base station.
Uplink and downlink gain and link balance
In the required coverage area, the normal transmission of the upper and lower links is guaranteed, and the signals received by the base station and the terminal can be demodulated, thereby ensuring the normal establishment of two-way communication. We believe that the system is balanced in these areas.
Simply consider the indoor link balance as follows:
2W base station transmit power (PCCPCH): 29dBm
Edge field strength design (PCCPCH): -85dBm
Downlink loss 29-(-85) = 114dB
UE maximum transmit power: 24dBm
Reached base station power: 24-114 = -90dBm
Base station receiving sensitivity: -110dBm
Upstream gain adjustable margin: 20dB
Considering the optimization of the overall network, there is a certain margin for the UE's transmit power. The uplink gain of the dry put is reduced by 10 dB compared to the downlink gain. It can also fully meet the requirements of the uplink and downlink balance. When the indoor coverage adopts the dry put, it can be appropriately adjusted to reduce The uplink gain of the dry put is to avoid interference with the base station as much as possible while meeting the coverage requirements.
When the dry put is used for indoor coverage, due to the limitation of the edge field strength, as long as the indoor (green) area can communicate with the uplink and the downlink, the uplink and downlink are considered to be balanced. While outdoors, there is no marginal field strength restriction, and we hope that the smaller the gap between the uplink and downlink coverage (the red area), the better.
From the above analysis, it can be seen that the output ratio of TS0 should be consistent with the source base station to avoid the oversaturation of the power amplifier after too many users are connected to the network. When the project is opened, it is necessary to reasonably master the gain adjustment and the basis of link balance. The relationship between the influence of the base station and the correct adjustment of the trunk amplifier will also play its biggest role in the large-scale construction of the TD-SCDMA network.
PC Cable:MINI DIN,D-SUB,SCSI.The display connecting line includes the data cable connecting the host computer and the display screen, and the power cable connecting the power supply.
The common data cable types are: HDMI cable, VGA cable and DVI cable. There is also a DP cable for notebook!
This product is suitable for computer and automatic connection cable with rated voltage of 500V and below. K type B low density polyethylene (LDPE) with oxidation resistance is used for insulation of cable ground wire core. Polyethylene has high insulation resistance, good voltage resistance, small dielectric coefficient and small influence of dielectric loss temperature and variable frequency. It can not only meet the requirements of transmission performance, but also ensure the service life of the cable. One
In order to reduce the mutual crosstalk and external interference between loops, the cable adopts shielding structure. According to different occasions, the shielding requirements of cables are as follows: the combined shielding of twisted pair, the total shielding of cable composed of twisted pair, and the total shielding after the combined shielding of twisted pair.
Shielding materials include round copper wire, copper strip and aluminum / plastic composite belt. Shielding pair and shielding pair have good insulation performance. If there is potential difference between shielding pair and shielding pair, the transmission quality of signal will not be affected.
PC Cable
ShenZhen Antenk Electronics Co,Ltd , https://www.antenkconn.com