All wireless communicationincluding wifioccurs due to electromagnetic interactions which is one of the four fundamental interactions in nature.
In simplest terms this means that a moving charged particle will have a magnetic field associated with it which will be perpendicular to the direction of charge.
[If charge is moving up and down the magnetic force will move sideways. If charged particle is moving sideways magnetic force will move up and down]
Similarly a changing magnetic field will have an electric force associated with it that will be perpendicular to the direction of the magnetic field.
[In the figure above the electric charge represented by E in red moves up and down the magnetic field represented by B in blue moves sideways]
As a result of electromagnetism the charged and magnetic particles move forever. On and on like a wave. An electromagnetic wave.
This wave exhibits both electric and magnetic properties.
So that if you transmit a wave ,generated by an oscillating current, through an antenna at point “a” you can receive it ,as an oscillating current, from another antenna at point “b”.
The Mathematics
Now an electromagnetic wave has certain properties that can be represented mathematically. These are
Wavelength — Length of the wave between to symmetric points. Such as length between highs and lows.
Frequency — Number of times the wave oscillates/repeats.
Amplitude — The max height of the wave. How high/low can it go. Amplitude is related to strength of the wave.
Phase — The value of a wave at a particular time and a point. A wave is constantly changing. The phase determines it at a particular instant.
These properties allow us to perform calculations on waves. We can add,subtract and compare waves just like we do with real numbers.
The engineering
Engineering solves the practical problem of transmitting useful information on a wireless wave.
It does that by modulating the signal with information before transmitting it via an antenna.
The receiving antenna extracts the current from the wave which can then be demodulated into the information that was transmitted.
Wifi is concerned with providing the physical channel for transmission of information and a mechanism for accessing that channel.
[In osi model this corresponds to layer 1 and layer 2]
Some points to note
Wifi frequency like 2.4 gHz causes the current to oscillate 2.4 billion times per second before the wave is transmitted. At the receiver this oscillating current is converted into digital bits that can be understood by computer.
Most modern wifi devices use QAM to modulate (or transmit useful information on) both Amplitude and Phase of the wave.
Wifi is a shared channel access. Meaning a single channelis shared by multiple devices (known as carrier sense multiple access) but only one at a time (for collision avoidance)
References
Nice video explaining the engineering behind wifi modulation
If the shape of an antenna is symmetrical, its radiation pattern will have the same symmetry
Directivity is a very important concept in antenna theory that deals with how much power can be radiated by an antenna in what direction. If we understand directivity we can better design systems that make use of antennas for transmission. If the situation calls for it we may even use different types of antennas to design our cellular network.
But to understand the directivity of antenna we need to know about it’s radiation patterns. That is how does an antenna radiate? What does it’s radiation look like in the real world?
So let’s get to it.
Based on radiation patterns an antenna can be classified into three types
1. Isotropic antennas
2. Omni directional Antennas
3. Directional antennas
Before we talk about the radiation pattern of the antennas it’s important to note that our classification deals with the degree of radiance.
What this means is that while all antennas radiate in all directions they do so inequally. And hence this classification is based on how much power is radiated in a direction as compared to others.
Further note that we will be taking about radiation in a 3D system. Like the real world our plane will have length, breadth and height represented by different axes.
Isotropic Antennas:- Isotropic Antennas radiate equally in all directions. It’s radiation pattern is a sphere of radius r. Where r is the maximum distance of radiation from from the point of origin that is the place where our antenna is located.
An Isotropic antenna does not exist in the real world . It’s conceptual and is used to compare the radiance of other antennas.
Why does it not exist?
Well that’s because we can’t control the radiation from an antenna. Once it starts to transmit the transmissions will keep going on and on untill all the power is lost via absoption or dissipation. Isotropic antenna suggests that it should radiate whithin the boundary of a perfect sphere which is not possible. But it serves as a good reference point.
Omnidirectional: An Omni antenna radiates in multiple directions but only in a 2d plane. So if for example the antenna rising at a height from the ground plane will radiate along the length and the breadth of the ground.
As is the case with any Omni antenna the radiation is greatest near the source and it falls off as the distance from the source increases.
Omni antenna is highly effective for point to multipoint conncetions. A case where there is one antenna broadcasting signal to multiple devices. Like wifi networks that we use in our home.
Directional Antenna: A directional antenna radiates more power in one direction. The waves are represented by an elongated front lobe in one direction and multiple smaller lobes in other directions. The lobe exactly opposite to the main/front/elongated/directional lobe is called ,wait for it, the back lobe!!! It’s the back lobe because it’s opposite to the front lobe!!! (well who could have thought?)
As expected the max distance and power is transmitted over the front lobe along the direction the antenna is supposed to transmit.
These types of antennas are focussed and are used for long distance point to point conncetions.
Useful in cases where one antenna has to transmit data to another antenna far away like in wireless backhaul or satellite communication in dish TV etc.
5 years ago, in April, 2014 one plus technology announced their developer friendly one plus one smart phone. For its time it featured a very powerful hardware that rivaled and in some cases even surpassed that of high end phones. And despite its premium hardware it was still priced as a mid ranged phone.
Powering one plus one was a Qualcomm Snapdragon 801 [1] Processor which among other things enabled
A 3g modem
A dual band, 80 mhz, 2 stream, MIMO wifi with a peak speed of 857 mbps ( which was nearly 6 times the speed of cellular 3g connection)
And a built in storage of 16 GB (with a 64 GB variant available)
One plus one was a huge success selling in excess of a million units world wide.
But what did “developer friendly” actually mean? Why was it such a big deal?
To understand the answer to these questions we need to take a bit of detour.
Android is an opensource operating system originally released by google. Today it runs on majority of smart phones . Android is built on top of linux kernel which also is an opensource software.
The original goal of Android was to provide the developers as well as users with a platform on which they could customize their operating system experience. However this goal of opensource operating system in a smart phone was only a partial success.
Many vendors took android as the base and built their own os for the hardware that they sold. And subsequently made it difficult for users to swap out the vendor operating system with the one they liked. These operating systems rarely received any updates once the device was phased out. So that even though your device was capable of delivering good performance you were left with no option but to buy a new phone to enjoy more features. Thus defeating the purpose of android as an open operating system.
Among many attempts made to solve this issue of lock in one that stood out the was the effort made by google and Motorola to offer stock android in their nexus and moto g phones. This was done to address the problems of regular updates, unwanted bloatware and ease of flashing.
A photograph taken on a One plus phone.
One plus one went a step further. Instead of using stock Android it came with a custom opensource variant by the name of cynogen mod.
Cynogen mod was a fork of Andorid that contained all of the base features that made the android so popular. In addition it added its own features to overcome some of the limitations placed by the vendor’s operating systems on hardware. Like restrictions tethering that allowed the users to share their internet connection with their friends via a hotspot [2]. With active installs in over 50M devices the popularity of cynogen mod spoke for itself.
Back in 2014 one plus one was like a breath of fresh air. Featuring an unlocked bootloader and an opensource, community developed fork of android it encouraged experimentation and allowed the developers to build their own operating systems to be used on one plus one machines.
What could you do with a custom operating system?
For a regular user the two advantages of a custom operating system were freedom from
Bloatware. No longer would they have to deal with apps they had no use for.
Restrictions on the hardware they have bought. With a custom operating system all the limitations on the hardware set by the carrier or the manufacturer could be overridden.
The custom operating system for the consumer was more about getting rid of what you didn’t want. In the business setting it allowed for more flexibility in the device usage. You were not held back by the restrictions placed by the vendors.
Sadly cynogen mod closed its doors in 2016. The development is continued by lineage os a community maintained fork of cynogen. One plus too moved on with its own operating system [3] but not before making its mark on andorid phone market.
As the first premium quality phone to embrace custom operating systems one plus one won the hearts of developer community world wide. Selling in excess of a million units it is still known today as one of the most well supported custom ROM devices. Even today one plus brand is synonymous with customization. Its Never Settle motto continuously encourages users to get more out of their device. One plus became popular not only in the consumer segment but also in the workplaces due to its adaptability.
With the latest installment in the series one plus 7 just out, 5 years after the original this would be a good time to remember how community software support got one plus where it is today and hope that more phone manufacturers can learn a few lessons from the encouragement one plus has given to the developer community.
Never Settle? Indeed.
At workwork we provide lineage os support on android phones for use as mobile computing device in the workplaces. Lineage os technology lets you
Create System Profiles that can be triggered either manually or automatically such as by connecting to a wifi access point. System profiles are invaluable in a business setting. You can turn an android phone in to a handheld business computer and that can be operated by your employees. Multiple profiles means that different employees can use the same phone for keeping a record of their activities, taking guest orders or even as kiosks in a mall or an airport.
Secure your device. By default the OS does not contain any way to download the apps from the app store. All of the basic features required to use the phone effectively are bundled in. You can set permissions on individual app. Set access to hardware on a per app basis. And in case you want allow downloads of new apps from the play store.
Integrate your device with the rest of your IT network via wifi or by direct usb connection. View system logs. Install additional apps. Run custom scripts. With lineage you have full control over your device. Do as you please.
Like what you hear? Don’t hesitate to send an email to
[2] “ Verizon this week began pushing smartphone updates that cripple some devices’ innate ability to be used as a mobile hotspot - for free. Specifically, Verizon pushed an update to the HTC Thunderbolt that blocked the devices embedded hotspot functionality, making the device less valuable and less useful to consumers. Why? Verizon wants to ensure that users have to pay an additional $20 a month mobile hotspot fee.” https://www.techdirt.com/article…
[3] Due to some disputes with the cynogen mod one plus started shipping their own operating system while still supporting user installed custom roms (meaning flashing a new rom did not void your warranty)
Its not that we particularly enjoy reading a dry declaration on the FCC website. Just like you we prefer to be peacefully sleeping in our bed when the clock is ticking past 2 AM. Yes sir. Sleep is a wonderful thing.
But then just as the spirit becomes a bit sluggish, and just as the night starts to clear the stage for dawn, we remember our commitment to our readers, you, who have never failed to keep your promise of coming up with deep un-examined questions on the fundamentals wireless technology.
Questions that compel us to pore over pages of legal documents, hardware specifications and protocol definitions late into the night. We do this only to reciprocate the feeling of trust you have shown in us. Night and day we keep a close watch on wifi technologies to make sure we can answer all your queries and help you make the best possible decision.
Here we round up this week’s of discussion with members on quora that has us cross examine google’s new wifi router. Clear off few doubts on wifi calling and make a couple of recommendations on wireless headsets. Hope you find them useful. As always if you’ve got any questions of your own don’t hesitate to reach us using the contact details given below. Enjoy your Sunday.
Well since you’re specifically asking for a disadvantage it is lack of redundancy. With the wifi internet access point you’ll probably be using a fixed line. While in case of 4g hotspots you will have to depend entirely on wireless connections.
Its good to have different providers for backup in case something does go wrong. It probably won’t but what if it does? If for some reason your mobile connection is not working you’ll at-least have a fixed line broadband to fall back on to.
Secondly. When you use a wifi you’ll purchase a wireless router. If you choose a router well you can do way more than just access the internet. You can use it as a home media server. A backup storage for your photos/important documents. As a chat server for offline chatting. Wireless lan parties. You can play counterstike with your friends! Or stream videos to your phone offline.
Possibilities are endless. But to do that you’ll need to know how to flash it and how to administer a networked machine. In case you don’t you can always learn!
In short a router gives you way more options beyond simple connectivity. A 4g connection while it may have good speed is only limited to internet access.
Wifi calling is technically known as voice over wlan (vowlan or vo-wifi).
It is important to understand that wifi is no different from wired lan. Only it has no wires. In terms of OSI model a wifi network is still a physical layer.
Therefore vowlan is simply voice over IP. You can use any of the VOIP protocols to communicate over vowlan.
Even though the range of wifi is small it is very useful in internal communication and setting up networks in emergency situations. Within a building. In a hospital, school ,college , airports. Any device that is connected to the same network can be addressed.
Wifi is a cheap way to build your own local network. With vowlan you can use voice to communicate with connected devices. There is no special technology involved because wifi is still treated as a PHYSICAL network by the devices running applications. To them it’s no different than a LAN.
Google wifi is a dual band router that supports both 2.4ghz and 5ghz frequencies. Google wifi is based [1] on qualcomm’s IPQ4019 System On Chip [2]
IPQ4019 chip is a part of qualcomm’s Dakota family of self organizing network chips (SON) that enable the routers to manage their own wifi configuration. Among its many features [3] is the ability to select the best wifi channel and band for the connected device automatically [3] and it is this feature that is used in the google wifi product that automatically “places you on on the least congested channel.”
Other features include MU-MIMO [4] and Beamforming.
With that out of the way how much max speed can the device deliver?
Well qualcomm claims that it’s chip has a Peak speed of 1.733 Gbps so google wifi is essentially a gigabit wireless router.
In theory this might be possible because the chip uses a max bandwidth of 80 MHZ and it has 2 transmission and 2 receiving channels (See MIMO [4] )
To verify we can check mcs index table [5] and calculate the max possible speed and compare it with the advertised speed.
Lets see [6] …. 866.7 *2 which comes out to be 1733.4 mbps or 1.733 gbps. So the theoretical speed indeed checks out.
In reality however you may not hit that speed because you client devices (laptop and mobile phones) may not have MIMO support. Even then a speed of 866 mbps is fast.
So yes google wifi supports 5ghz and is gigabit fast. Thanks to qualcomm!
[6] 866.7 the max possible theoretical speed with a modulation [7] of 256 QAM, a 5/6 coding rateon a single antenna with 80 MHZ bandwidth. Multiplied by 2 because we have 2 antennas.
Thank you for A2A. When choosing be sure to select on these parameters
The playback time
The charging time
Bluetooth version supported (4 is the most widely supported while 5 is the latest version)
The max distance at which the device works without a hitch.
boAt seems to be the popular mid range wireless headphones provider in India at the moment. I’m not sure what your budget is Rockerz looks nice and it seems to be on discount
Thank you for A2A. One plus 7 pro is built on top of Qualcomm Snapdragon 855 chipset [1]. So lets start with the good news. Here’s the WLAN specs of the chipset:-
As we can see the chip is “ax- ready”. But that is no reason to jump in joy because the actual support has to be configured by the vendor. One plus 7 uses wifi 6 compatible chip but it does not itself support it. Here are the WLAN specs of the phone[2]:-
Wi-Fi 802.11 a/b/g/n/ac. Multiple protocol support so that even if your router uses an older wifi protocol your phone will be able to access it. WIFI 802.11 ac is the current, most popular deployment in devices. It is also known as WIFI 5. Unfortunately as we can see there is no support for 802.11ax that means wifi 6 is not supported. But even on wifi 5 it has a 2×2 MIMO and a theoretical max speed 1.733 gbps. Not bad!
Dual-band. Dual band usually means that your wifi base station can work on multiple frequencies. So when your phone is in a hotspot mode it can transmit signals on both 5ghz and 2.4ghz band. While it is is client mode it can access signals on 2.4 ghz or 5ghz band. Please note that this is a hardware property. The actual support for switching between the bands has to be provided by the OS of the system.
WiFi Direct . Think of it as Bluetooth equivalent of wifi. Both the devices need to be wifi direct compatible in order for this to work. The functionality is usually built into the phone and you don’t need to download any external application,
Hotspot capabilities.
General thoughts on why wifi 5 is good enough for now and why you might not need wifi 6
FIrst of all it should be noted that 802.11 ac is capable of gigabit speeds. Even a single channel transmission on 160 MGHZ can reach 866.7 mbps. With MU-MIMO you can multiply this many times. The maximum being 6933.3 with 8 streams [3]. So wifi 5 is already pretty fast. Considering that to stream HD movies you merely need a speed of 25 mbps even a single stream wifi 5 radio will be more then enough for a normal consumer.
Whenever a new version of wireless protocol comes up it requires changes in both base station as well as client hardware. These changes take a long time to propagate in the design and manufacturing of devices.
Wifi 6 or 802.11ax was announced last year. It is expected to gain deployment support in devices by the end of 2019. However I believe that it would be a few more years before it becomes more common.
Even if you buy a WIFI 6 device it will not be of much use today because you have neither many clients (in case you use your mobile as a wifi 6 hotspot) nor many compatible base stations [4] (in case you want to connect your phone to a router) that can work with these protocols. Further as you use wifi for your internet access consider how much speed your ISP provides. Its more likely that you’ll exhaust your ISP bandwith than your WI-FI bandwidth.
To truly enjoy the wifi 6 experience you need to wait for the ecosystem to develop. In the mean time wifi 6 is good enough.
workrock 