Many Internet of Things (IoT) use cases, such as stationary wireless sensors transmitting data infrequently (e.g., meters for reading water levels or electricity usage), are characterized by low bit rates, the need to cover remote and difficult-to-reach locations with long communication ranges, the need for low cost of the wireless modules, and the need to minimize battery usage. A class of wireless networks called Low-Power Wide Area (LPWA) networks are targeting such use cases. The LPWA space is fairly complicated with multiple solutions competing for the users. LPWA technologies and players include among others LoRA, Sigfox, Ingenu, Weightless, Narrowband IoT (NB-IoT), Long-Term Evolution Machine Type Communications Category M1 (LTE-M or LTE MTC Cat M1), and Extended Coverage GSM for Internet of Things (EC-GSM-IoT). The last three of these are 3GPP (Third Generation Partnership Project) technologies operating in licensed spectrum. We will take a closer look at these 3GPP technologies in this blog post.
The benefits that EC-GSM-IoT, LTE-M and NB-IoT offer include [GSMA]:
GSMA argues that operators have a clear preference to use standardized, licensed spectrum LPWA technologies due to the limitations of LPWA technologies operating in unlicensed spectrum, including capacity, scalability, security, and regulatory constraints [GSMA].
3GPP Release 12 specified a Cat-0 UE (Category 0 User Equipment) with the objective to reduce device complexity to the level of GSM/GPRS (General Packet Radio Service) devices [GSMA]. Release 13 specified Cat-M1 UEs that reduce complexity further from Cat-0, increase coverage by a minimum of 15 dB and improve battery life (to up to over 10 years), while also reusing the LTE installed base. Cat-M1 offers many similar features as regular LTE UEs, such as connected mode mobility and seamless handoffs. Cat-M1 UEs can even integrate voice in IoT applications.
Cat-M1 uses the same spectrum as legacy LTE, that is, between 450 MHz and 3.5 GHz [GSMA]. It requires 1.4 MHz of bandwidth. Both the downlink and uplink peak bitrates are 1 Mbit/s, while latency is 10-15ms [WP].
EC-GSM-IoT is based on eGPRS [GSMA]. It is designed to be a high capacity, long range and low complexity cellular system for IoT. It can be introduced into an existing GSM network as a software upgrade. EC-GSM-IoT is designed to offer coverage for M2M devices in locations with challenging radio coverage conditions.
EC-GSM-IoT uses the same spectrum as GSM, that is, the 850-900 MHz and 1800-1900 MHz bands [GSMA]. The downlink and uplink peak bitrates are 474 kbit/s (EDGE) or 2 Mbit/s (EGPRS2B) [WP]. Latency is 700ms - 2s.
NB-IoT reuses the principles and building blocks of the LTE physical layer and higher protocol layers. It offers extended coverage compared to traditional GSM networks. Higher protocols and signaling and physical layer processing requirements are greatly simplified to reduce UE power consumption and complexity. NB-IoT reduces device complexity below that of LTE-M and GSM, with the potential to rival module costs of unlicensed LPWA technologies [ER]. It enables a device cost under $5 per module [ER-2]. NB-IoT enables a battery life of up to over 10 years. NB-IoT can coexist with 2G, 3G, and LTE. It is specifically tailored for ultra-low-end IoT applications [ER].
NB-IoT can be deployed in 2G, 3G or 4G spectrum (e.g., from 450 MHz to 3.5 GHz) [GSMA]. Sub-2 GHz bands are preferred for applications requiring good coverage. The bandwidth requirement is 180 kHz for in-band and guard-band deployment or 200 kHz for standalone deployment. NB-IoT’s downlink peak bitrate is 250 kbit/s [WP]. Uplink peak bitrate is 250 kbit/s in the case of multi-tone or multi-subcarrier or 20 kbit/s (single-tone or single sub-carrier). Latency is 1.6-10 seconds.
[ER] Cellular Networks for Massive IoT, Ericsson White Paper, https://www.ericsson.com/assets/local/publications/white-papers/wp_iot.pdf
[ER-2] NB-IoT: a sustainable technology for connecting billions of devices, https://www.ericsson.com/en/publications/ericsson-technology-review/archive/2016/nb-iot-a-sustainable-technology-for-connecting-billions-of-devices
[GSMA] 3GPP Low Power Wide Area Technologies, GSMA White Paper, https://www.gsma.com/iot/wp-content/uploads/2016/10/3GPP-Low-Power-Wide-Area-Technologies-GSMA-White-Paper.pdf
[WP] NarrowBand IoT, https://en.wikipedia.org/wiki/NarrowBand_IOT
The benefits that EC-GSM-IoT, LTE-M and NB-IoT offer include [GSMA]:
- Low power consumption, enabling devices to last for up to 10 years on a single charge
- Optimized transmission of small amounts of data
- Low wireless module unit cost
- Simplified network topology and deployment
- Improved outdoor and indoor penetration coverage
- Secured connectivity and strong authentication
- Possibility to Integrate with the operator’s IoT platform (assuming that the operator is offering not only connectivity, but also an IoT platform)
- Network scalability due to the use of licensed spectrum and traffic management
GSMA argues that operators have a clear preference to use standardized, licensed spectrum LPWA technologies due to the limitations of LPWA technologies operating in unlicensed spectrum, including capacity, scalability, security, and regulatory constraints [GSMA].
LTE Cat-M1 (LTE-M)
3GPP Release 12 specified a Cat-0 UE (Category 0 User Equipment) with the objective to reduce device complexity to the level of GSM/GPRS (General Packet Radio Service) devices [GSMA]. Release 13 specified Cat-M1 UEs that reduce complexity further from Cat-0, increase coverage by a minimum of 15 dB and improve battery life (to up to over 10 years), while also reusing the LTE installed base. Cat-M1 offers many similar features as regular LTE UEs, such as connected mode mobility and seamless handoffs. Cat-M1 UEs can even integrate voice in IoT applications.
Cat-M1 uses the same spectrum as legacy LTE, that is, between 450 MHz and 3.5 GHz [GSMA]. It requires 1.4 MHz of bandwidth. Both the downlink and uplink peak bitrates are 1 Mbit/s, while latency is 10-15ms [WP].
EC-GSM-IoT
EC-GSM-IoT is based on eGPRS [GSMA]. It is designed to be a high capacity, long range and low complexity cellular system for IoT. It can be introduced into an existing GSM network as a software upgrade. EC-GSM-IoT is designed to offer coverage for M2M devices in locations with challenging radio coverage conditions.
EC-GSM-IoT uses the same spectrum as GSM, that is, the 850-900 MHz and 1800-1900 MHz bands [GSMA]. The downlink and uplink peak bitrates are 474 kbit/s (EDGE) or 2 Mbit/s (EGPRS2B) [WP]. Latency is 700ms - 2s.
NB-IoT
NB-IoT reuses the principles and building blocks of the LTE physical layer and higher protocol layers. It offers extended coverage compared to traditional GSM networks. Higher protocols and signaling and physical layer processing requirements are greatly simplified to reduce UE power consumption and complexity. NB-IoT reduces device complexity below that of LTE-M and GSM, with the potential to rival module costs of unlicensed LPWA technologies [ER]. It enables a device cost under $5 per module [ER-2]. NB-IoT enables a battery life of up to over 10 years. NB-IoT can coexist with 2G, 3G, and LTE. It is specifically tailored for ultra-low-end IoT applications [ER].
NB-IoT can be deployed in 2G, 3G or 4G spectrum (e.g., from 450 MHz to 3.5 GHz) [GSMA]. Sub-2 GHz bands are preferred for applications requiring good coverage. The bandwidth requirement is 180 kHz for in-band and guard-band deployment or 200 kHz for standalone deployment. NB-IoT’s downlink peak bitrate is 250 kbit/s [WP]. Uplink peak bitrate is 250 kbit/s in the case of multi-tone or multi-subcarrier or 20 kbit/s (single-tone or single sub-carrier). Latency is 1.6-10 seconds.
References
[ER] Cellular Networks for Massive IoT, Ericsson White Paper, https://www.ericsson.com/assets/local/publications/white-papers/wp_iot.pdf
[ER-2] NB-IoT: a sustainable technology for connecting billions of devices, https://www.ericsson.com/en/publications/ericsson-technology-review/archive/2016/nb-iot-a-sustainable-technology-for-connecting-billions-of-devices
[GSMA] 3GPP Low Power Wide Area Technologies, GSMA White Paper, https://www.gsma.com/iot/wp-content/uploads/2016/10/3GPP-Low-Power-Wide-Area-Technologies-GSMA-White-Paper.pdf
[WP] NarrowBand IoT, https://en.wikipedia.org/wiki/NarrowBand_IOT
