, and the dwpts length of 2nd half frames is 1 ms. Uppts and sub-frame 2 are used as the uplink, and sub-Frames 7 and 9 are used as the downlink.Physical resources
Basic time unit
Antenna Port
LTE uses antenna ports to differentiate space resources. The definition of an antenna port is defined from the receiver's perspective. That is, if the receiver needs to
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What is the effective omni-direction radiation power?
In fact, the directional transmitting antenna is often used, so that the transmitter power is concentrated in a particular direction and the energy is greatly enhanced in this particular direction.
assuming that the energy in a particular direction is greater than the non-directi
the device has good compatibility and can improve the performance of the device. If there is a problem, it will not be caused by the product of different companies.
Ii. Typical Installation Problems of Wireless Networks
1. Because the installation location is not selected, you need to change the installation location afterwards.
Solution: when selecting the installation location, ensure that there should be sufficient visible space between the antennas, and then consider whether installation an
present, wireless routers in the indoor launch power generally does not exceed 20dBm. The higher the transmitting power of the wireless router, the higher the signal strength, but more than the specified range will cause large electromagnetic radiation and interference.
antenna gain: the greater the gain, the stronger the signal strength, at present, most of our routers antenna gain 3dBi.
interface, internal slots only PCMCIA interface length half, so the use of very easy to cause a miscarriage of error.
The Mini PCI interface is the most common built-in interface in the notebook, which is essentially a scaled-down version of the PCI interface, which is very rich in the type of network card. The main advantage is that the network card inside the notebook, easy to use and safe, not in need of use when not found. The disadvantage is that you need to reserve the
points is in line with the communication distance of bridge equipment.
Can use the point to point Way direct transmission: a building to place a wireless network bridge, the top placement side directional antenna; B building also placed a bridge without a network, the top of a directional antenna. Wireless network bridge between the two places through the feeder and the local
. Contactless IC Card In addition to the card contains IC card circuit, also contains the relevant RF transceiver circuit and antenna coil. IC card can receive the signal of reader and writer in a certain distance, and realize non-contact reading and writing.RF Identification Card
Radio Frequency identification card (RF card, RFID card), also known as contactless IC card (contactless Smart card) or contactless IC card, contactless card, inductio
One, the current family for wireless router + notebook + desktop use, if the desktop and notebook and wireless router in a room, but the phenomenon is also very frequent drop line.
If you connect to a router's desktop, dial-up stability, long work does not drop the line, then you can judge the fault may come from the wireless router, we can improve the quality of the router's power, heat, and so on, if the problem has not been resolved, we have to speed limit, the average distribution of two co
In general, the process of CDMA network optimization is divided into three stages: single base station configuration confirmation, community optimization and system-wide optimization (or global optimization), each phase completes different tasks.
Single Base station configuration confirmation
The goal is to confirm the installation integrity of the BTS and the accuracy of the data. The verification parameters include:
(1) The Base station equipment debugging: the base station equipment debugg
wireless network will also cause electromagnetic interference, so the placement of wireless routers should also try to stay away from these appliances.
Extended Antenna enhancement signal
Because the size of the antenna gain directly affects the signal emission intensity and the ability to receive, and some of the routers in the market are removable design, so the wireless router to replace a high gain
other signal channels more than two.
In addition, a lot of home appliances in the work of the wireless network will also cause electromagnetic interference, so the placement of wireless routers should also try to stay away from these appliances.
Third, extended antenna enhancement signal
Because the size of the antenna gain directly affects the signal emission intensity and the ability to receive, and
Round () functionReturns a numeric value that is the result of rounding operations by the specified number of decimal places syntax round (number, decimal_places) numbers: The numeric value to be rounded up decimal_places: rounding, fractional numbers (preset to 0) return value type numeric Example select round (123.456, 0) from dual; Backhaul 123 Select Round (123.456, 1) from dual; Backhaul 123.5 Select R
I. Questions about enhancing wireless signals
As you know, wireless signal loss may occur due to transmission distance, media, or other factors, shortening the transmission distance and reducing the transmission speed. Therefore, to improve the wireless transmission performance and improve the wireless routing signal, you can start from the following aspects.
◆ High-gain antenna preferred
Both wired and wireless networks have signal attenuation. Compa
= Corrected_valueresampler.sample_freq_out=corrected_value0x05 GPS Active AntennaSecurity researchers use a low noise amplifier (Noise amplifier LNA) antenna with ceramic patch days as an active GPS antenna to reduce overall noise. Showing the Garmin ga27c GPS antenna, we can see a piece of ceramic patch on its PCB board:Garmin GA-27 active
interference
If the noise intensity of your network bandwidth exceeds the -85DBM, then RF interference is likely to impair network performance. In this case, the user's retry rate will exceed 10%, and the user will feel the network speed is affected. This can happen, for example, when a wireless user is in the same room as a running microwave oven. If you decide that the problem is caused by radio frequency interference, you have to find out where the interference comes from and try to remove
present, wireless routers in the indoor launch power generally does not exceed 20dBm. The higher the transmitting power of the wireless router, the higher the signal strength, but more than the specified range will cause large electromagnetic radiation and interference.
Antenna gain: The greater the gain, the stronger the signal strength, at present, most of our routers antenna gain 3dBi.
Working Band: T
router until you hear a "click" of a network card. Now that the "one wireless router" and "one broadband network cable" have been successfully connected, the process of installing the wireless router has already been completed, and then let us know about the wireless router.
In addition to what we have just mentioned, wireless router, a number of network cable interface, a wireless router also has a power interface, as a network equipment, wireless routers need independent power supply, that i
When the router is published, there are some technical terms, such as 802.11AC, 5G, gigabit, dual frequency, 2*2 antenna, Wi-Fi, and also the conclusion that "10 times times Faster", "Top Configuration", "Global X". Under the manufacturer propaganda, some people think that the product is good to be bad, also some people think the manufacturer is bragging x. This article is the wireless router knowledge popularization, each followed by a selection of s
, the entire system is typically a wireless system, such as the Code division used in multiple antenna systems, 3G mobile phone systems (wireless systems) multiple Access (CDMA) systems, even DSL systems (wired systems) that generate crosstalk (crosstalk) using multiple phone lines.
This paper will first introduce the history background and operation of MIMO, and discuss the extent to which MIMO can extend WLAN transmission range.
The development pr
sources to interfere, which naturally causes the WLAN transmission speed slows down. In addition, wireless network transmission distance is limited, although the general wireless router nominal transmission distance can reach 100~300 meters, but in the actual use if there is a barrier, this distance will be shortened dramatically and will lead to slow data transmission speed.
Knowing the slow speed of transmission, we can begin to solve the problem with a targeted approach. First in the layout
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