Have you ever wondered why your phone has three radios (LTE, Wi-Fi and Bluetooth), while your tablet and computer typically have two (Wi-Fi and Bluetooth)? For that matter, why do you know names like Wi-Fi, Bluetooth and LTE? What about 5G or Zigbee?
At the same time that wireless data-communication technology and standards are still in development, new standards and proprietary technologies (like Zigbee) are clamoring for attention. How do we separate the noise from what is real and important? Should consumers care about any of this? Figure 1, below, offers an impression of the variety of wireless technologies that play a role in our daily lives.
Despite all the marketing chatter, it is relatively easy to look at the bigger picture and understand where things are going. And as it is often the case, it can be helpful to remind ourselves how we got to where we are today.
Maybe a Little Bit of Technology First
There are only three things of overriding importance in radio technology, and we experience them all in our daily lives. These three things are range, data rate and power.
- We experience range as our phone is connected to a base station (or not), or when our laptop is connected to the router at home, or when our headset is connected to our phone. And we all know from experience what happens if a device gets “out of range.”
- We are also quite familiar with data rate, particularly when we watch videos or listen to music. Wi-Fi has been the king of data rate until now, but we have been able to receive similar data rates with LTE and 5G – though perhaps at a higher price.
- Finally, while we have grown accustomed to regularly recharging our phones and laptops, we are reminded of the importance of power consumption in those annoying moments when we discover that our smaller devices, like headsets or Fitbits, are not charged when we are ready to use them.
These three items fit together in an interesting way, a sort of basic law of physics. Try to improve one, and the two others must give way. Of course, general overall improvements have been made over time on all three, but the relationship between them is the same.
For instance, if you want increased data rate, then you must either lose range or increase the output power. Wi-Fi today, with its higher speeds (data rate), has less range than in the past and more often needs repeaters – this is one of the motivators for distributed Wi-Fi, or mesh Wi-Fi. This same relationship holds true for Zigbee (“low power Wi-Fi”). It essentially gets the same range as Wi-Fi, at a low data rate, but with significantly lower power, thereby achieving a very long battery life.
There is a fourth element in this equation, also based on physics, that we may be less aware of in our daily lives. That element is frequency. Higher frequencies reduce range or require higher power to achieve the same range. But higher frequencies have the advantages of more bandwidth and, thus, higher data rates. This explains the tendency for higher data rates to “look for” higher frequencies. The newest versions of Wi-Fi are in the 60 GHz frequency band, with targets up to 100 Gb/s (.11ay).
Back to the Radios Present in Phones and Laptops
Clearly a lot more can be said about this, but to a large extent, these parameters are the reasons you have three radios in your phone. One radio (LTE) to get the range to connect to the closest base station in your neighborhood; one radio (Wi-Fi) to get performance when you are at home or in the office; and one radio (Bluetooth) to enable short-range connectivity to the small devices that you carry with you, like your phone headset or your Fitbit.
Why, then, do laptops and tablets usually only have two radios? There is a logical answer, but we must also understand a bit of history.
A Brief History: the Technology Players
In a relatively short period of time, we have seen three new technologies develop and converge:
- The phone, to remotely connect us via low-speed data communications.
- Radio/TV, to broadcast audio/video, via cable or satellite, with one-way high-speed data communications.
- The computer, including two-way high-speed networking that pulls everything together. All the communication was initially over a wired cable (copper or fiber), but when the convenience of wireless came along, it became ubiquitous.
As technology progresses, the differences between phones, TVs, laptops and tablets are slowly disappearing. In a way, they are all becoming “networked computers,” but each still has its own history of wireless communication standards as each experienced its own transition from wired to wireless technology. Phones and computers had a more dynamic path, but because TVs are largely static (nonmobile) devices, the cable/satellite industry mostly stayed in its own wired world.