Cisco 802.11ac Access Points: Gigabit Wi-Fi Threshold Passed

    As soon as the first wave of gigabit Wi-Fi was ratified - 802.11ac, Cisco, as one of the participants in the development of the standard, released the first ac-access points. They are the personification of the Cisco High Density Experience: an approach to building high-speed Wi-Fi networks with a high density of connections.

    First, let's get acquainted with the main driving factors for the development of gigabit Wi-Fi. It’s not always clear why transferring data at such speeds, when you use web surfing, watch videos on youtube or read posts on Facebook. This will happen at a speed of 100 Mbit / s or 500 Mbit / s - the connected user, by and large, doesn’t care.

    The advantages of the new standard lie slightly in other planes. The first of these is the density of connections to the access point. The nature of the wireless broadcast is such that only one device can transmit at a time. And if it works at a low speed, then other devices have little time to transfer their portion of information. As soon as we increase the connection speed of clients, which allows us to use the new standard 802.11ac, airtime begins to be used more efficiently. For a unit of time, more information can be transmitted, which means that more users can work on one access point. Further in the article, we will give an example when 100 clients were connected to one such Cisco 2700 access point at the same time.

    The second important advantage is the battery life of the mobile device. It is logical to assume that if a smartphone or tablet spends less time transmitting a unit of information, its battery will last longer until the next charge. This video perfectly shows that when downloading a file to a mobile smartphone via Wi-Fi, the battery charge on the 802.11ac client is saved exactly 2 times!

    In May, Cisco announced the 2700 Series Access Points with full 802.11ac first wave support. This means that the maximum transmission speed in the radio channel can be 1.3 Gbit / s. The access point is equipped with three transmitting and four receiving radio elements (MIMO 3x4) and has a new distributed memory architecture.

    Cisco Access Point 2700 Series

    The High Density Experience approach, which involves connecting a large number of clients at high speeds, includes several mechanisms:

    - New architecture of access points. Unlike competitive solutions on the market, the Cisco 2700 and the previously released older sister, the Cisco 3700, have additional memory on each radio interface. The traditional design with a single memory pool has been replaced by an improved one: at new Cisco points, each radio chip (2.4Ghz and 5Ghz) has its own 128MB buffer. This allows you to achieve higher efficiency in prioritizing packets from clients without overloading the central processor. The so-called TurboBoost architecture allows you to achieve better performance than competitors. This is confirmed by independent Miercom reports .

    - Increase the transfer rate of the client device using Client-Link 3.0 technology. The so-called Transmit Beamforming mechanism allows you to form a directional beam towards the client. Receiving signals to different antenna elements, the access point calculates the time difference with which the signal arrived at each antenna. And then it corrects these phase shifts when sending a signal in the direction of the client device. It is due to the fact that the signals, folding in phase, increase the overall amplitude, the transmission speed for such a client increases. The uniqueness of Client-Link 3.0 technology is that it works for all types of clients: 802.11 a / b / g / n / ac.

    - Cisco Optimized Roaming- a mechanism to disable “stuck” customers. Clients on the edge of the access point’s coverage begin to transmit data at low speeds, eating airtime. All this harms other customers and reduces their overall speed. It is the optimization of Cisco roaming that allows you to force disconnect such "stuck" mobile devices, forcing them to look for a new access point or use a 3G network.

    New access points have already been tested in battle. The proof that they cope with a large number of customers and at the same time demonstrate a high average speed is the Cisco test conducted in conjunction with the NSA Show.Without the use of special engineering firmware and specialized settings, the Cisco 2700 access point was able to demonstrate the simultaneous connection of 100 clients of various types.
    Among them were both 802.11ac and 802.11n mobile devices. At the same time, the total total data transfer rate was 316.9Mbit / s. This is an effective data rate at the TCP / UDP level.

    Source: NSA Show (

    Support for 802.11ac standard, new hardware architecture and optimized roaming mechanisms allow using the new Cisco 2700 access point and her older sister Cisco 3700 to implement the High Density Experience approach, which significantly increases the number of connected clients, data transfer speed, and the ability to transfer more capacious traffic and use mobile apps.

    Useful Content About:
    - 2700 Series Access Point
    - 3700 Series Access Point
    - High Density Experience (HDX) Approach

    Yuri Dovgan
    Cisco Systems Engineer

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