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The author:(作者)aaapublished in(发表于) 2013/12/6 12:32:50 Speed is faster， bigger than 3G 4G radiation？ ，
Speed is faster, bigger than 3G 4G radiation?-4G,TDLTE,3G-IT information Speed is faster, bigger than 3G 4G radiation?
Q:
4G business immediately, 4G said propaganda network much faster than 3G. So, 4G radiation is actually greater than the 3G? Mobile phone radiation harmful to you?
A:
A, 4G speed is promoted not by radiation
Network speed is indeed a lot faster than the 3G of the 4G, in accordance with the Shannon theorem, network speeds depending on the channel bandwidth and transmission signal to noise ratio of the signal.
For example, we use the traffic to:
We can 4G Internet, as transportation from Beijing to Tianjin. If you want to have more cars per unit of time (the 4G the network faster than 3G), what are the methods?
1, expanding the width of the highway (expanded bandwidth);
2, reduce potholes and obstacles on the road (channel noise reduction);
3, increasing vehicle speed (extending signal transmission power).
4G is, as far as possible promote the previous two entries, and the third (as power increases to the base station and terminal design brings a lot of trouble, especially in mobile phone. ）
3G mobile channel bandwidth is 1.6MHz, Telecom is 1.25MHz, Unicom is 5Mhz (late improvement), and currently TD-LTE channel bandwidth is 20MHz. This upgrade directly improved the speed of 4G. At the same time, 4G for channel noise control progress, also improves the final network speeds.
By the previous two implementations, 4G on the premise of no additional radiation to achieve faster speeds than 3G times.
But these are not the end of the 4G technological advances. In order to further enhance the speed, 4G by MIMO, OFDM technology, the establishment of a special Multicarrier transmission, which improves the efficient use of spectrum. This is also further enhanced the speed of 4G.
B, 4G, and 3G of radiation higher than who?
We'll watch and 3G contrast. After several years of construction and operation of the network, base station radiation 3G less than 2G has been extensively tested and validated. 4G era, it is actually the same principle.
We know that the 4G network mostly in high-frequency, direct impact of this is signal attenuation of fast, small base station coverage. To this end, the 4G base station density must be higher than 3G, so as to achieve network available.
But the base station density, radiation has increased? The other way around. Just say, 4G base station because of the need to build a single base station coverage area is small, the main factor that coverage of small signal power of a single base station is low, that is, less radiation.
At the same time, 4G in network efficiency higher than 3G, will also have a unit power consumption savings.
But this is only the base station. We also need to take into account the mobile phone side. Transmits signals between the handset and the base station is the power of dynamic regulation, taken farther away when the signal is lower, cell phones in order to join the network, the higher the transmit power. Thus, as far away from the base station are not healthier. This has nothing to do with 3G or 4G, is the fundamentals of wireless communications.
But there is a premise that all regular sale of mobile phones, its signal under the worst conditions, and radiation are in conformity with the relevant standards.
Third, correct understanding of cell phone radiation
Ionizing radiation and non-ionizing radiation radiation is divided into two. Higher risk of ionizing radiation, short-term accept 1Sv shop radiation can lead to disease. We are more familiar with ionizing radiation, including the atomic bomb exploded, x-ray scanning, and even by plane.
Measuring ionizing radiation unit, Sipho (Sv), according to professional determination, eating a banana, radiation is 0.1 μ Sv (note that the unit is micro-West, 1 Sv is equal to 1 million μ Sv), with a one-year cumulative radiation is 1 μ Sv CRT monitors, to fly from New York to Los Angeles is 40 μ Sv ... ... After the explosion at the Chernobyl nuclear power plant leak, standing next to the reactor is 50Sv--10 minutes of ionizing radiation equivalent to 100duowanci flown, 500 million bananas to eat.
Mobile phone radiation is non-ionizing radiation, are higher security category. For the moment, there is no scientific validation indicate that radiation from mobile phones will bring direct or indirect damage to the human body. As long as it is the formal channel verification after we buy the product, can rest assured that the normal use.
网速更快了，4G辐射比3G更大吗？ - 4G,TDLTE,3G - IT资讯网速更快了，4G辐射比3G更大吗？
问：
4G马上商用了，宣传上说4G的网络速度比3G快很多。那么，4G的辐射是否也相应的比3G更大？手机辐射对人体有害吗？
答：
一、4G网速提升不是靠辐射
4G的网络速度确实比3G快很多，根据香农定理，网络速度主要取决于信道带宽和传输信号的信噪比。
我们用交通来举例：
我们可以把4G上网，看做从北京到天津的交通运输。如果要在单位时间内通过更多的汽车（即让4G网络比3G更快），有哪些方法呢？
1、扩大高速公路宽度（扩大信道带宽）；
2、减少公路上的坑洼和障碍（降低信道噪声）；
3、提高汽车车速（扩大信号发射功率）。
4G的做法是，尽量提升前面两项，而控制第三项（因为功耗增加会给基站设计和终端设计带来很大麻烦，特别是手机端。）
3G时代移动的信道带宽是1.6MHz，电信是1.25MHz，联通是5Mhz（后期有改进），而目前TD-LTE采用的信道带宽为20MHz。这提升直接改善了4G的网速。同时，4G对于信道噪声的控制也有所进步，同样提升了最终的网络速率。
通过前面两条的实现，4G可以在不增加辐射的前提下，实现了比3G时代更快的网速。
但这些还不是4G技术进步的终点。为了进一步提升速度，4G通过MIMO、OFDM等技术，建立了特殊的多载波传输，即提升了频谱的利用效率。这也进一步提升了4G速度。
二、4G辐射和3G比谁更高？
我们先看3G和2G的对比。经过几年的网络建设和运营，3G基站辐射小于2G已被广泛测试和验证。到了4G时代，其实也是同样的原理。
我们知道，4G网络大部分在高频段，这带来的直接影响就是信号衰减快，基站覆盖范围小。为此，4G基站密度必须高于3G，这样才能实现网络正常可用。
但基站密度大，是否辐射也增加？恰恰相反。刚刚说了，4G基站需要多建的原因是单个基站覆盖面积小，覆盖面积小的主要因素就是单个基站的信号功率低，也就是辐射更低。
同时，4G比3G在网络利用效率上更高，也会带来单位功耗的节省。
但这只是基站端的情况。我们还需要考虑到手机端。手机与基站之间传输信号的功率是动态调节了，两者距离越远信号越差的时候，手机为了联接网络，发射的功率就越高。因此，离基站越远并不是越健康。这与3G还是4G无关，是无线通信的基本原理。
但有一个大前提，即所有正规出售的手机，在其信号最差的条件下，辐射也是符合相关标准的。
三、正确认识手机辐射
辐射分为电离辐射和非电离辐射两种。电离辐射的危险性较高，短期接受1Sv的店里辐射就可能致病。我们比较熟悉的电离辐射包括原子弹爆炸、X光扫描、甚至是坐飞机。
衡量电离辐射的单位叫西弗（Sv），根据专业机构测定，吃一根香蕉的辐射是0.1µSv（注意，单位是微西弗，1 Sv等于100万µSv），用一年CRT显示器的累计辐射是1µSv，坐飞机从纽约到洛杉矶是40µSv……在切尔诺贝利核电站泄漏爆炸后，站在反应堆旁边10分钟的电离辐射是50Sv——相当于坐100多万次飞机，吃5亿根香蕉。
而手机辐射属于非电离辐射，是安全性更高的类别。从目前看，没有任何科学验证表明手机辐射会给人体带来直接或间接的损害。只要是正规渠道购买经过相关验证的产品，都是可以放心正常使用的。
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