Press Backgrounders

ULP WIRELESS CONNECTIVITY BACKGROUNDER

Ultra low power wireless connectivity technology backgrounder

Nordic's proprietary ultra low power 2.4GHz wireless connectivity is a proven coin cell-powered RF technology in use in millions of products in the PC peripherals, consumer, sports, gaming, healthcare, toys and automation sectors across the world. This backgrounder describes the technology in detail

 

The convenience of wireless

 

If you need two devices to communicate, a wireless link is very convenient. Although wired connections are cheap and reliable, they are prone to wear and damage. And, given the choice, manufacturers would prefer to shy away from adding a connector because it compromises reliability and provides a path for the ingress of moisture and dust to sensitive electronics.

 

With a wireless connection there are no wires to become tangled and no restraints on where the two devices to be connected are positioned (provided they are within the radio’s operational range, which is typically 10 meters or more for Personal Area Network (PAN) applications).

 

Moreover, wireless connections allow spontaneity. It’s unlikely, for example, that two users are going to be able to transfer e-business cards from one smart phone to another without wireless technology; it’s impractical to carry the multitude of cables that would be required to ensure your smart phone is going to connect with those from different manufacturers.

 

Nordic Semiconductor saw the potential for short-range wireless connections over a decade ago. We now predict rapid increases in the applications and growth of wireless technology. Our experience is that consumers don’t like cables and place a lot of value on the added convenience and freedom of wireless products. This is particularly true if the cost of such products is comparable to traditional wired alternatives.

 

At Nordic we know reliable transmission over the specified range is of the utmost importance when designing a wireless link. We design and manufacture robust wireless links that are as reliable as equivalent wired connections. Our wireless links include features that ensure long battery life, while constantly checking the integrity of the link to offer protection against interference from other radio sources.

 

Nordic's product families are aimed at applications in the PC peripherals, sports & fitness, gaming, toys, mobile phone accessories, healthcare, consumer electronics, and industrial & home automation sectors. The nRF24L Series (together with the Nordic Gazell™ protocol stack) is the market leading solution for wireless PC peripherals and is ideal for wireless mice, keyboards, remote controls, trackpads, and presenters. The nRF51 Series, Nordic's third generation of 2.4GHz ULP wireless connectivity solutions build on the older product's legacy

Nordic chips power the wireless communication of sports watches. (Courtesy: Garmin)

Nordic chips power the wireless communication of sports watches. (Courtesy: Garmin)

 

Use of the 2.4GHz band and avoiding interference

 

The unlicensed portions of the electromagnetic (EM) spectrum were originally reserved internationally for non-commercial use for industrial, scientific and medical purposes and are often collectively referred to as the “ISM” band(s). The ISM bands are defined by the ITU-Radiocommunications Bureau (ITU-R) in sections 5.138 and 5.150 of the Radio Regulations.

 

Some of these bands are: 433.05-434.79MHz (centre frequency 433.92MHz, typically called “433MHz”), 902-928MHz (centre frequency 915MHz, “915MHz”), 2.4-2.5GHz (centre frequency 2.45 GHz, “2.4GHz”) and 5.725-5.875 GHz (centre frequency 5.800GHz, “5.8GHz”). There are many others, including for example a band centred on 868MHz.

 

It is important to note (in the words of the ITU-R) that: “the use of these frequency bands for ISM applications is subject to special authorisation by the local administration, in agreement with other administrations whose radiocommunication services might be affected”. In other words, some countries may ban the use of certain allocated ISM bands on their territory.

 

This creates regional variation. For example, the 433 and 868MHz bands are popular in Europe, 433MHz is common in Japan, while 915MHz is only available for unlicensed use in the US, Australia, and Israel. In contrast, the 2.4GHz band is accepted virtually globally. This universal acceptance of 2.4GHz has not escaped manufacturers looking to export their products worldwide, and Nordic is no exception. While the company has manufactured 433 and 915MHz products for many years it now focuses its wireless development efforts on 2.4GHz products.

 

It’s also no coincidence that IEEE.802.xx international standards such as Wi-Fi®, Bluetooth™ wireless technology and ZigBee® employ the 2.4GHz band (as well as 868 and 915MHz for regional variants), along with proprietary forms or wireless Ethernet or USB.

 

As more and more companies produce products that use this portion of the radio spectrum, designers have to deal with the possibility of interference from radio signals from other sources. In fact, regulations governing the ISM parts of the spectrum state “a device must expect interference”.

 

...to continue reading this technology backgrounder, please download the PDF.

 

The complete document is 5,435 words and includes sections on: The convenience of wireless; Use of the 2.4GHz band and avoiding interference; Ultra-low power operation; Adding a wireless link to portable devices; System-on-Chip vs. Single-Chip-Connectivity, and Beyond the standard.