Why is my phone even Wi-Fi speed is always stuck in 75Mbps? Wi-Fi speed with doubts - once you understand!

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Why is my phone even Wi-Fi speed is always stuck in 75Mbps? Wi-Fi speed with doubts - once you understand!

(2017-02-21 10:57:48)

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Wi-fi mobile phone

Category: the Wi-Fi

Why is my phone even Wi-Fi speed is always stuck in 75Mbps? Wi-Fi speed with doubts - once you understand!

There is always a doubt before, "Why small night phone never reach the router marked speed (deficit Little Night also studied so long to buy it - - -)?"

After more than a year of exploration, sudden epiphany one day apart, the mind os ... (and paid the tuition T_T). Liberal arts students to speak, with a daily information technology; this part to "wifi speed" as the protagonist, a list of each of the (degree of) factors. In the end is a poor congenital or acquired differences?

Benpian the technical specifications and the discussion is based on the evolution of the Taiwan-based different regions (supplementary specification that allows channels) will vary Please also note.

First, the specification generation

As technology advances, a new generation of faster and faster wifi specifications. Different each generation of new technology is not introduced in sequence, using listed first band with maximum speed.

wifi generations	Technical Specifications	Use Band	The maximum theoretical speed
The first generation	802.11	2.4GHz	2Mbit/s
The second generation	802.11b	2.4GHz	11Mbit/s
Third Generation	802.11g	2.4GHz	54Mbit/s
Fourth Generation	802.11n	2.4GHz/5GHz	150Mbit / s (single antenna)
Fifth Generation	802.11ac	5GHz	443Mbit / s (single antenna)

Note: In fact, before there is n a, but Taiwan was not open because it did not promote open 5GHz.

Second, the number of antennas

N the number of previously only an antenna, In response to the increased bandwidth limited situation (network access) efficiency, the development of a multiple access technique: MIMO. Note, however, the transmitting end (e.g., a router) with two antennas, the receiving end (e.g., wireless LAN) also have only two antennas using MIMO, and when a speed or else the antenna is the same Oh. Here are the number of antennas and the highest (theoretical) speed.

Technical Specifications	Single antenna	MIMO 2x2	MIMO 3x3	MIMO 4x4	The number of antennas MIMO
802.11n	150Mbit/s	300Mbit/s	450Mbit/s	600Mbit/s	Up to four
802.11ac	443Mbit/s	867Mbit/s	1300Mbit/s	1730Mbit/s	Up to eight

Third, the bandwidth size

Hey ~ ~ focus here is an example of the message header, directed name N300 smart antenna wireless router to defeat down T_T, the results are not running the phone more than 72Mbps speed, strange, anti-ei rub Ha thief? It turned out that the first application of the second point, "Mobile *" only one antenna, so the first half cut 300 becomes 150.150 and because of bandwidth and then cut half ... 75 weeping TT. n standard bandwidth is 20MHz, can be selectively transferred into 40MHz, the speed will be doubled. The following lists the present embodiment the number of antennas at different speeds and bandwidth corresponding to the bandwidth specification wifi. Another may be compatible down ac 20MHz, 40MHz.

N300	Single antenna	MIMO 2x2
20MHz	75Mbit/s	150Mbit/s
40MHz	150Mbit/s	300Mbit/s

Technical Specifications	bandwidth
802.11	20MHz
802.11b	20MHz
802.11g	20MHz
802.11n	20MHz/40MHz
802.11ac	80MHz/160MHz

* Normally only a mobile phone antenna.

Saya's first router can not manually adjust bandwidth. The actual depend on various brands. Brush with free software (note the risk), then ... you can manually adjust. But not that it is faster than 40MHz 20MHz (at 2.4GHz time), because the theory is not completely equal to the actual use (2.4GHz band) too many people (so new specifications towards 5GHz), choose a large bandwidth but affect stability degrees, and even the speed decreasing instead of increasing.

Fourth, channel interference

Under the band will again distinguish between channels.

2.4GHz在台灣有1（2.412GHz）、2（2.417GHz）、3（2.422GHz）、4（2.427GHz）、5（2.432GHz）、6（2.437GHz）、7（2.442GHz）、8（2.447GHz）、9（2.452GHz）、10（2.457GHz）、11（2.462GHz），11個頻道（或稱通道）可用。因為標準頻寬是20MHz，所以選1、6、11才能被免與別人打架（波形會受到干擾進而影響穩定度與速度），圖中可見不是笨機器就是壞孩子...。40MHz的話就...干擾多多了喔— —"。另外若兩台路由器都選同一個頻道，兩台機器會協議(?)類似多重存取技術，時間上、空間（路徑）上錯開來，波形不會被干擾。可參考下圖。

2.4GHz在全世界都屬於開放(不需要申請使用執照)的頻段，因此藍牙、無線滑鼠、微波爐......都擠在這個頻段，這些就不是wifi分析儀可以抓得到的了。因此像上點所說新規格要邁向5GHz。看右圖~用的人少少~_~還是中華電信架的XD

嘿~你發現了嗎？n有2.4GHz與5GHz可以選擇，速度卻一樣，就是為了避免干擾喔。

至於5GHz頻段：因為頻道間隔為40MHz，所以802.11ac的標準頻寬80MHz就能不再受到鄰居箝制，擺脫802.11n的惡夢啦～

五、加密方式

齁齁齁～你知道加密方式會影響速度嗎？答案是會的喔～

WEP（不安全）排除～

WPA有兩種可以選：

使用TKIP最高速度只能到54Mbit/s～再排除

剩下AES啦！

AES與完全不加密傳輸速度只差一點點，小夜測試雙天線150>144；單天線75>72。還算可以接受啦~

六、距離阻隔

隨著距離越遠訊號越弱，但室內不比室外空曠，除了上述提到的各種干擾源，會削弱訊號還有粉多呢。

其一是金屬，其二水泥牆，對訊號干擾最明顯。本來在路由器旁邊放了一個錫盤，拿到後訊號穩定很多，有興趣的可以觀察看看～隔一道金屬門、兩道牆壁試試看。

Some routers have "wisdom antenna" can track the location of the receiving terminal to adjust the signal to find a "wind tunnel" yo ~ only seen in high-end routers in many dry barrier.

Seven, the number of users

This is as we all know but often overlooked factor - experience living in a small night school classrooms from deep ... a number of people in a position relatively far away from the router to start frequently break Le ˙ ˙ ㄡ public wifi big drawback Poof.