What Does The IoT Ultra-High Density Requirement Mean?

IoT networks are expected to connect billions of devices in the next several years. One ambitious 5G requirement is to serve massive Internet of Things (IoT). Accordingly, it demands an ultra-low energy (10+ years of battery life), deep coverage and ultra-high density (~1 million nodes per sq. Km?). As such, 5G networks require each base station to be able to receive a high volume of access requests from end-device in a short period, say 30 minute.  Are these really necessary or even possible with the existing IoT technologies?
Obviously these requirements are highly expected for the IoT networks operated in high population density cities, where a large portion of IoT end-devices will be deployed.  For example, as shown in the table below, the population density in Chennai, India is 25,854 per Km2. If in average it is assumed that one IoT device per capita and the coverage of one IoT base station is 4 Km in radius, the number of the served IoT devices per base station is expected to be 25,854 x 3.14 x 16 = 1,298,905.  This means, considering a 30-minute period and assuming that there is no retransmission in a 4 km IoT network deployed in Chennai, India, the expected access capacity is 1,298,905 access per 30 minutes.

The top 20 city districts with the highest population densities. Source: Wikipedia

On the hand, for LoRaWAN, if assuming a 125kHz channel bandwidth, spreading factor of 12, and 23dBm RF output, then the shortest access packet length is 172ms preamble + 262ms payload = 434ms access packet.  As such the maximum non-collision access density is 33.2 access packets per kHz and the maximum non-collision access capacity is 331,600 accesses per 30 minutes per 10MHz. This means that the expected access capacity demand for Chennai, India is FOUR times of the no-collision maximum access capacity of the LoRaWAN network. In other words, LoRaWAN may not be able to handle the traffic demand by  Chennai, India.

And similarly for LTE, if assuming LTE PRACH Format 3 and 23dBm RF output, then the maximum non-collision access density is 1,728 access packets per kHz and the maximum non-collision access capacity is 17,280,000 accesses per 30 minutes per 10MHz. This means that the expected access capacity for Chennai, India is only 7.5% of the no-collision maximum access capacity of a LTE network.

Why is there such a big difference?  Obviously it is because of the system designs. LoRaWAN includes too much hardly avoidable overhead.

Comments

UbiBot said…
IoT technology is used in many different business sectors for better growth of organisation. Through IoT platform in business it help to secure data and reducing costs without reducing services. Thank you for sharing this great blog.
November 2, 2019 at 2:15 AM
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