Datacom
19/07/2021
DM955 – Efficient Connectivity with AC Wi-Fi

By Luis Wolfarth – Telecom Applications Engineer

As the demand for connectivity in wireless devices grows, the technologies used in the implementation of Wi-Fi networks have been constantly evolving. The challenges to be overcome are the growing need for bandwidth (Mbps), low latency, range and signal stability (interference tolerance). The work done on the rules governing Wi-Fi networks has significantly improved the user experience, where the most common application is Internet access.

Wireless devices in homes today represent the largest volume of equipment that accesses the Internet. Wired networks, once the most common way to bring Internet to residential devices, are now the exception in homes, as previously equipment with Internet access was limited to personal computers. Currently, an increasing range of equipment is presented, including smartphones, smart speakers (Alexa and Google Home), monitoring cameras, smart vacuums, smart TVs, air conditioning, refrigerators, etc. Anyway, we are entering the era of the "Internet of Things" or IoT (Internet of Things) and the wireless interface is usually available in these gadgets.

DATACOM already has in its portfolio the UN model DM985-424 (Read the article), which has an advanced Wi-Fi interface to support applications that demand high performance. To give providers more application possibilities, Datacom has also launched a Wi-Fi router, the DM955.

In this article, we will see how the 5th generation Wi-Fi, supported by the ONU DM985-424 and the DATACOM DM955 Wireless Router,  adheres to the contemporary needs of residential broadband Internet access, which today already delivers rates in the order of hundreds of Mbit/s. The article also presents the advantages of 5th generation Wi-Fi (IEEE 802.11ac), which using the MU-MIMO and Beamforming techniques guarantees an excellent throughput and signal coverage with low latency and stability.

 

Interferences

In Telecommunications it is common to denote the "transmission medium" which is where information will be sent or received. When using a wired network, the transmission medium is cables and these elements were designed so that the signals used are confined without interfering with adjacent wired networks, for example your neighbor's wired network is not able to interfere with your wired network .

Wireless networks use space as a transmission medium - here on Earth it is more common to refer to as "air" - where frequency bands of electromagnetic signals are used that we call "transmission channels" and fortunately, with a correct implementation , a device operating on transmission channel A is not capable of interfering with a device operating on transmission channel B. However, if both operate on the same channel, we will inevitably have the effects of interference, and that is where your neighbor comes into this story.

Interferences, depending on their degree, will be tolerated by the devices and possibly be imperceptible, but if they are too large the communication of wireless devices with the router will fail and without knowing the problem, the Internet provider will probably be blamed as responsible. In practice, what happens are technology limitations, often depending on the spectral conditions of the environment, it is possible to work around the problem of interference through router settings, however, we know that customizing the router settings at the subscriber's home is not scalable and it may not be a permanent solution. It is better then to use devices with more modern implementations (standards) of wireless networks that consider the current requirements for the use of Wi-Fi technology.

 

Advantages of Wi-Fi 5 and using the DM955

Before describing the advantages of Wi-Fi 5, let's review the characteristics of the most popular implementations to briefly understand the main aspects of each:


Note: the WiFi Alliance created a nomenclature that was retroactively added to the standards defined by the IEEE so the idea is to pass on to users the concept of generation of the WiFi technology being referred to. For example, 802.11ac is being WiFi 5 or fifth-generation WiFi.

 

In 1999 the first commercial version (802.11b – WiFi 1) was published using the 2.4GHz frequency supporting 1 to 11Mbit/s in one (1) channel. Within this frequency band, 11 to 14 transmission channels are established (2401 to 2495MHz), each channel has a bandwidth of 20MHz and overlaps the adjacent channels. In practice, within the spectral usage standards established in Brazil, using 2.4GHz we have 3 channels that do not overlap, being channel 1 (F0 = 2412MHz), channel 6 (F0 = 2437MHz) and channel 11 (F0 = 2462MHz). Channel distribution within the 2.4GHz band is maintained since then regardless of the WiFi standard operating at this frequency.

In 2003 the 802.11g (WiFi 3) standard was published, using more complex modulation techniques within 2.4GHz, it was possible to increase throughput (bandwidth) using only one (1) channel while basically maintaining similar signal range capabilities as the standard. 802.11b.

In 2009, WiFi 802.11n (WiFi 4) was presented where, in addition to the possibility of using more than one channel to increase throughput, it uses MIMO (Multiple Input Multiple Output) technology. With multiple antennas the receiver can optimize signal interpretation in a digital processor reducing the destructive effect of interference and maximizing gain. The transmitter in turn can optimize the transmission using multiple antennas where it is not necessary for the receiver to have the same number of antennas as the transmitter, varying from device to device. Transmission can take place on isolated signals where each signal is sent by an antenna to each receiver or the signals can be sent in full to multiple receivers via multiple antennas simultaneously. Thus, the 802.1n standard is capable of operating at rates from 54 to 600 Mbit/s that vary with the number of antennas used by the transmitter/receiver set, channel width (20 or 40MHz) and operating frequency (2.4GHz or 5GHz) ).

Finally, in 2013 we had the publication of the 802.11ac standard (WiFi 5) which operates exclusively at 5GHz and can reach from 433Mbit/s to 1.3Gbit/s in 80 or 160MHz channels. AC networks use MU-MIMO (Multiple Users MIMO), which, in addition to operating with multiple antennas for transmission and reception, is capable of sending and receiving signals from different devices simultaneously (Multiple Users), allowing a higher throughput capacity and reducing the latency at levels very close to a wired network with virtually zero jitter.

Another big highlight of the technology is the use of Beamforming, a technique that, like MIMO, also uses multiple antennas where the same signal is received by several antennas in reception, where each antenna is interpreted as a distinct signal, and later these several signals receive phase correction so that they can be internally summed, generating constructive interference with each other, significantly increasing the receiver's sensitivity.

In transmission, also making use of multiple antennas, Beamforming can, in the case of a distant device, transmit the same signal with different phase delays so that after traveling the paths with different distances, they arrive phase-aligned to the receiver antenna which again will cause constructive signal interference.

Finally, the Beamforming technique ends up being able to generate directional signal propagation lobes with the combination of antennas with omni-directional characteristics being the signal dynamically directing to the distant device as it moves through the environment. The implementation of Beamforming depends on the hardware characteristics of the Wi-Fi Router being transparent to the connected devices that will benefit from this technique.

 

Residential accesses with more bandwidth

Now that we've seen the main features of the most popular versions of wireless networks, let's look at the final product historically delivered by ISPs. Last-mile technologies, that is, Internet access technologies that reach the subscriber's address, also received evolutions that in practice reflected in the increase in the bandwidth in Mbit/s and the decrease in the propagation latency of the signal arriving and leaving the modem of the subscriber.

The use of residential Wi-Fi was introduced and popularized along with broadband Internet access via metallic access, the most common technologies being ADSL (metallic telephone pair) and HFC (coaxial cable for pay TV). At that time, Internet service transmission rates were often lower than the Mbit/s capacity of the wireless router present in the subscriber's home, so rates from 1 to 54Mbps on Wi-Fi were more than enough to consume the bandwidth Internet service contracted in its entirety. With the emergence of GPON (Gigabit Passive Optical Network) technology began to appear offers of Internet plans up to 1Gbps, however, 

the Wi-Fi technology used by the subscriber can be a bottleneck preventing the consumption of the entire contracted Internet bandwidth. The way of consumption and the purposes of using the Internet also end up raising the requirements of wireless routers. The number of connected devices, the rate in Mbit/s demanded by each device, the latency (delay) requirements, the stability and range of the signal are increasingly present needs.

In practice the requirements to be met by a modern residential wireless router are:

  • Ability to service a large number of mobile devices simultaneously

The MU-MIMO (Multiple User MIMO) technology introduced by 802.11ac (WiFi 5) is able to make a single wireless router behave virtually as if it were multiple routers in this way each user has their own dedicated signal boosting thus the capability of simultaneous devices.

  • Support large data rate in wireless Mbit/s adhering to installed access technology (advent of GPON)

The MIMO technology introduced by 802.11n (WiFi 4) and MU-MIMO introduced by 802.11ac (WiFi 5) significantly increase the rate in Mbit/s by using greater channel width and modulation techniques that deliver greater throughput.

  • Avoid interference (usually caused in the 2.4GHz band)

The 5GHz frequency suffers less from interference for three main reasons: the first reason is the lower number of wireless routers currently operating at this frequency, the second aspect is the lower signal propagation capacity at 5GHz, so external signals operating in this band will be much less present, and the third aspect is not to suffer interference by other domestic devices such as microwave oven, cordless telephone, bluetooth device, among others. The use of the 5GHz frequency is made possible by 802.11n (WiFi 4) and 802.11ac (WiFi 5).

  • Have a Wi-Fi signal with low latency and no jitter (online games, VPNs)

The MU-MIMO technology introduced by 802.11ac (WiFi 5) allows individual and simultaneous data streams to different devices connected to the same wireless router, so the router does not need to wait for the completion of communication from a device to start communication with another, with that the latency introduced in the applications of each user will be minimal and the jitter practically nil.

  • Have reasonable signal range

We know that one of the advantages of using 2.4GHz is its range due to its greater ability to bypass obstacles, so naturally it is able to provide greater signal coverage. However, as we reviewed earlier at this frequency we suffer from interference that can severely disrupt user applications. The use of the 5GHz frequency naturally decreases its propagation due to its lower ability to bypass obstacles, however, with the use of the Beamforming technology introduced in the 802.11ac version (WiFi 5) a coverage similar to 2.4GHz can be achieved as the signal can be virtually targeted at devices that are far away from the wireless router.

 

Final considerations

A modern wireless router, for backwards compatibility reasons, must be able to support the previous generations of Wi-Fi and support the current requirements for offering residential Internet services. It was with this in mind that Datacom launched the DM955, a Wireless Gigabit Dual Band AC1200 Router.

The DM955, with 802.11ac dual band Wi-Fi technology, provides a reliable and extremely fast network for users. The 2.4GHz band offers speeds of up to 300Mbps, perfectly handling everyday tasks such as email and web browsing, while the 5GHz band offers up to 866Mbps throughput, ideal for streaming UHD video and online gaming. line.

The Datacom wireless router has four external antennas that emit Wi-Fi signals to every room in the subscriber's home.

The DM955 compensates for ambient shadows and keeps the user connected by taking advantage of fast Wi-Fi access, whether in the living room, kitchen, bedroom or any room in your home.

The DM955 also has the remote management feature through the TR-069 protocol. With this feature, the ISP can manage all routers installed on its subscribers through the cloud. The TR-069 management allows the ISP to perform remote diagnostics and tests, reducing operational costs.

If you have any technical questions regarding our portfolio, please do not hesitate to contact our support team via email suporte.prevendas@datacom.com.br, or contact your account manager directly to receive a proposal.

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