Building the IoT Backbone: 2.4GHz is Already Delivering on Its Promise

The Internet of Things (IoT) needs a strong backbone to support the volume and diversity of devices, applications and platforms that are coming online. Companies developing applications want to deliver them to the widest available market, and companies deploying IoT devices and solutions want to be able to utilize the same ones in Berlin and Hong Kong as they do in Los Angeles. A ubiquitous solution benefits everyone.

The 2.4 GHz ISM (industrial, scientific and medical) band is available worldwide, is cost-free, and benefits from extremely favorable regulatory conditions. Because the spectrum requirements are the same from one country to another, one radio works anywhere in the world.

One World, One Band
Utilizing one simple global band is key to unlocking access to the billions of IoT devices which will ultimately exist by the end of this decade. Managing these devices with anything other than a global band results in significant resource and capital costs for businesses, which in turn negate the benefits of which the IoT was intended. 

Utilizing a sub-GHz band or cellular for IoT has three distinct disadvantages:

• Multiple bands = multiple radios – There are more than 40 bands available across the globe. Providing global coverage with the sub-GHz band and especially cellular, requires supporting dozens of radios, resulting in extremely high module costs.
   
• Costly Carrier Certification – In addition to module costs, certification is required for each and every carrier whose network supports that module. Today, that certification can cost between $40,000 and $100,000 per carrier, making the cost and time required to support an IoT endpoint with dozens of bands and hundreds of carriers implausible.
   
• Technology Fragmentation – When looking at the activity in 3GPP, there are simultaneous activities around LTE (News - Alert)-M, NB-IoT, EC-GSM, 5G-IoT and others.  Typically, standardization is about eliminating fragmentation, but ironically, 3GPP seems to be only increasing fragmentation.

Unlicensed vs. Licensed
Licensed spectrum is a valuable and scarce resource. Through auctions, lobbying and various other methods, national governments allocate licenses for a wide range of uses. Because of this, licensed spectrum is expensive. For cellular communications, it is estimated that 40 percent of the total cost of building a network is spectrum costs. The high value of spectrum is a key reason cellular operators are constantly migrating to newer technologies. With the ever-increasing demand for bandwidth from smart phones, tablets and streaming video, it is critical that carriers move to the highest revenue use for this limited, expensive asset.

Unlicensed spectrum provides an alternative, with specific areas set aside for all users who follow a set of rules designed to ensure that many devices can operate in these shared radio frequencies. Technologies that can operate successfully under the rules of these frequency bands can go to market quickly and avoid the huge costs of licensed spectrum – in fact, even the cellular industry is beginning to test the unlicensed spectrum (Wi-Fi, call hand-off, LTE-U, etc.) to limit spectrum costs.

Coverage and Capacity
As mentioned above, network technologies which operate successfully within the 2.4 GHz band can reap the benefits that the spectrum has to offer--without compromising coverage and capacity.

Coverage (a metric of how much network infrastructure is required to reliably cover a region) is crucial to building a profitable public network. Poor propagation (a major criticism of the 2.4 GHz band) must be overcome through smart engineering.  Companies such as Ingenu have resolved this through antenna diversity and receiver sensitivity innovations.

Capacity (a metric of how many devices, on average, may be supported by a piece of network infrastructure) is proportional to the amount of spectrum available.  Not only does the 2.4 GHz band exist everywhere, it has a whopping 80 MHz of spectrum available everywhere. That’s a factor of 100x more than most of the sub GHz bands that are 500 kHz or less. In addition, many countries have duty cycle limitations on the sub GHz spectrum (often less than 1 percent on-time), which has a detrimental effect, especially on downlink capacity. The 2.4 GHz band imposes no such constraints.

When it comes to IoT connectivity, there are a variety of technologies competing to become the backbone of choice. Networks that effectively utilize the 2.4 GHz band can offer true global reach while reducing device and operational costs. The inherent characteristics of the 2.4 GHz band offer better range and capacity, and ultimately provide an alternative to achieving ubiquitous network coverage for IoT devices.

About the Author: Dr. Myers is a recognized expert in wireless communication systems and digital signal processing theory. Prior to co-founding Ingenu, Dr. Myers was a founder of CommASIC, where he developed the WBSP processor and its first application to the 802.11 a/b/g physical layer. Earlier in his career he led and/or contributed to numerous other physical layer designs for cellular applications and government satellite systems.