With the continuous development of mobile communication technology, the global Internet of Things (IoT) is about to usher in rapid growth. Among international operators, AT&T, Verizon, KDDI, KPN, Orange, NTT DoCoMo, Telefonica, Telstra, and Telus have successively launched commercial eMTC services.
In China, China Telecom took the lead, and after establishing the 800MHz networking capability, it aims to construct 300,000 NB-IoT base stations in one go. China Unicom signed a dual-exclusive agreement with Jasper, early on determining NB-IoT as its development direction.
However, China Mobile, which was the first to propose the technology, has been indecisive between NB-IoT and eMTC. The main reason for this indecision lies in the strengths of both standards, while China Mobile’s TDD network complicates its decision-making.
This article systematically organizes and analyzes the main performance characteristics of NB-IoT and eMTC in ten aspects. After ten rounds of debate, let us re-examine what the best decision for China Mobile should look like.
In the network construction of the Internet of Things, there are many application scenarios to meet. So, in which scenarios are NB-IoT and eMTC competing? There are mainly three scenarios, let’s take a look at them one by one.
IoT applications can be mainly divided into three categories based on requirements for rate, latency, and reliability:
Scenario 1: Low latency and high reliability services. This type of service has high requirements for throughput, latency, or reliability, with typical applications including vehicle networking and remote medical services;
Scenario 2: Medium-demand services. This type of service has moderate or low throughput requirements, some applications have mobility and voice requirements, and there are certain limitations on coverage and cost. Typical services include smart home security and wearable devices;
Scenario 3: LPWA (Low Power Wide Area) services. The main characteristics of LPWA services include low power consumption, low cost, low throughput, wide (deep) coverage, and a huge number of involved terminals. Typical applications include metering, environmental monitoring, logistics, and asset tracking.
Among the above types of services, LPWA services have become the main battlefield for global operators competing for connections due to the large scale of connection demands. NB-IoT and eMTC are mainly competing on this battlefield.
II. Who Were the Defeated Opponents
As NB-IoT and eMTC have come this far, which network standards have they defeated along the way?
Currently, there are multiple IoT communication technologies that can support LPWA services, such as GPRS, LTE, LoRa, and Sigfox, but they face the following issues:
1. Terminal battery life cannot meet requirements. For example, the current GSM terminal standby time (excluding services) is only about 20 days. In some typical LPWA applications such as metering, the cost of battery replacement is high, and in certain special locations such as deep wells and chimneys, replacing batteries is very inconvenient.
2. Unable to meet the application demands of massive terminals. One major characteristic of IoT terminals is their large quantity, thus requiring networks that can simultaneously connect a large number of users. However, currently designed networks for non-IoT applications cannot meet the demand for simultaneous access of massive terminals.
3. Insufficient network coverage in typical scenarios. For example, coverage blind spots exist in deep wells and underground garages, where outdoor base stations cannot achieve full coverage.
4. High costs. For companies deploying IoT, one important reason for choosing LPWA is the low deployment cost. The mainstream communication technology for smart home applications is WiFi. Although the price of WiFi modules has dropped below 10 RMB, IoT devices supporting WiFi typically still require wireless routers or wireless APs for network access, or can only communicate within a local area network. Cellular communication technology has high deployment costs for enterprises, with the most common 2G communication modules generally costing over 30 RMB, while 4G communication modules can exceed 200 RMB.
5. High transmission interference. This mainly refers to non-cellular IoT technologies, which transmit based on unlicensed spectrum, leading to high transmission interference, poor security, and unreliable transmission.
The aforementioned points have become obstacles to the development of LPWA services. Compared to these standards, NB-IoT and eMTC have obvious advantages.
1. Coverage
NB-IoT: The design goal is to enhance coverage by 20dB over GSM. Assuming a maximum coupling loss of 144 dB for GSM, the maximum coupling loss for NB-IoT is designed to be 164 dB. Its downlink mainly relies on increasing the maximum retransmission times of each channel to achieve increased coverage. Despite the NB-IoT terminal’s uplink transmission power (23 dBm) being 10 dB lower than GSM (33 dBm), the narrowing of transmission bandwidth and the increase in maximum retransmission times allow it to operate under a maximum path loss of 164 dB.
eMTC: Its design goal is to enhance by about 15 dB over the maximum path loss of LTE (140 dB), with a maximum coupling loss of up to 155 dB. This technology’s coverage enhancement mainly relies on channel repetition, making its coverage about 9 dB worse than NB-IoT.
In summary, the coverage radius of NB-IoT is about 4 times that of GSM/LTE, while the coverage radius of eMTC is about 3 times that of GSM/LTE. The coverage radius of NB-IoT is 30% larger than that of eMTC. The coverage enhancements of NB-IoT and eMTC can be used to improve the deep coverage capability of IoT terminals, enhance network coverage, or reduce site density to lower network costs, etc.
2. Power Consumption
Due to the geographic location or cost reasons, most IoT applications face difficulties in updating terminals, making power consumption a crucial factor for whether IoT terminals can be commercialized in special scenarios.
NB-IoT: The design goal for terminal battery life in the 3GPP standard is 10 years. In actual design, NB-IoT introduces energy-saving modes such as eDRX and PSM to reduce power consumption. This technology employs various methods to enhance battery efficiency, such as reducing the peak-to-average power ratio to improve power amplifier (PA) efficiency, minimizing periodic measurements, and only supporting single processes, to achieve the design expectation of a 10-year lifespan. However, in practical applications, the battery life of NB-IoT is closely related to the specific business model and the coverage area of the terminal.
eMTC: Under relatively ideal scenarios, the expected battery life can also reach around 10 years. Its terminals also incorporate PSM and eDRX energy-saving modes, but actual performance still needs further evaluation and validation in different scenarios.
3. Module Cost
NB-IoT: It adopts simpler modulation and coding methods to lower the requirements for memory and processors; it uses half-duplex methods, eliminating the need for duplexers, thereby reducing out-of-band and blocking indicators, among other methods. Currently, under the market scale, its module cost can be below 5 USD. As the market scale expands, scale effects may further reduce its module cost. The specific amount and timeline depend on the speed of industry development.
eMTC: It has also optimized costs to some extent based on LTE to meet IoT application demands. Under the initial market scale, its module cost can be below 10 USD.
4. Connection Count
The connection count is a key factor for the large-scale application of IoT.
NB-IoT: Its initial design goal was 50,000 connections per cell. Based on initial calculations and evaluations, the current version can basically meet the requirement. However, whether this design goal can be achieved depends on factors such as the business model of each NB-IoT terminal in the cell, requiring further testing and evaluation.
eMTC: Its connection count has not been specifically optimized for IoT applications, and it is expected that its connection count will be less than that of NB-IoT technology, with specific performance needing further testing and evaluation.
5. Future Function Enhancements
Location Function: In the R13 version of NB-IoT technology, to reduce terminal power consumption, PRS and SRS were not designed in the system. Therefore, currently, NB-IoT can only locate through the base station side E-CID method, with relatively coarse precision. Of course, future upgrades will further consider enhancing location accuracy features and designs.
Multicast Function: In IoT services, base stations may need to send the same data packets to a large number of terminals simultaneously. In the R13 version of NB-IoT, there are no corresponding multicast services, requiring data to be sent to each terminal individually, wasting significant system resources and extending overall information transmission time. The R14 version may consider multicast characteristics to improve related performance.
Mobility/Service Continuity Enhancement Function: In R13, NB-IoT was mainly designed and optimized for stationary/low-speed users, not supporting neighbor cell measurement reporting, and therefore cannot perform connected state cell switching, only supporting idle state cell reselection. The R14 phase will enhance UE measurement reporting capabilities, supporting connected state cell switching.
6. Voice Support Capability
For standard-definition and high-definition VoIP voice, their voice rates are 12.2 kbps and 23.85 kbps, respectively. The network must provide at least 10.6 kbps and 17.7 kbps application layer rates to support standard-definition and high-definition VoIP voice.
NB-IoT: Its peak uplink and downlink throughput rates are only 67 kbps and 30 kbps, respectively, so it cannot support voice functions in a networking environment.
eMTC: Its FDD mode uplink and downlink rates can basically meet voice requirements, but from an industry perspective, current support is limited. For the eMTC TDD mode, due to limitations on uplink resources, its voice support capability is weaker than that of the eMTC FDD mode.
7. Mobility Management
NB-IoT: In the R13 version, it cannot perform cell switching or redirection in a connected state, only allowing cell reselection in an idle state. In subsequent versions, the industry may propose mobility management requirements in a connected state for certain vertical industry demands.
eMTC: Since this technology is optimized based on LTE, it can support connected state cell switching.
8. Impact of Network Deployment on Existing Networks
The ease of network deployment and the cost of network construction are likely the most important considerations for operators during decision-making.
NB-IoT: For operators that have not deployed LTE FDD, the deployment of NB-IoT is closer to the deployment of a brand-new network, involving the construction or renovation of wireless networks and core networks and adjustments to transmission structures. Additionally, if there is no existing free spectrum, adjustments to the existing network spectrum (usually GSM) will be required (Standalone mode). Therefore, the implementation cost is relatively high.
For operators that have already deployed LTE FDD, the deployment of NB-IoT can largely utilize existing equipment and spectrum, making it relatively simple. However, regardless of which standard is used for construction, independent deployment of the core network or upgrading existing network equipment is necessary.
eMTC: If a 4G network has been deployed in the existing network, deploying the eMTC network on this basis allows for software upgrades in the wireless network and similar software upgrades in the core network.
9. Business Models
NB-IoT: It excels in coverage, power consumption, cost, and connection count, but cannot meet mobility and medium rate requirements, or voice service demands, making it more suitable for low-rate LPWA applications with relatively low mobility requirements;
eMTC: While currently weaker than NB-IoT in coverage and module cost, it has advantages in peak rate, mobility, and voice capability, making it suitable for IoT application scenarios with medium throughput, mobility, or voice capability requirements. Operators can choose relevant IoT technologies for deployment based on actual applications in their existing networks.
Therefore, experts have long held the view that under the eMTC network, application scenarios are richer, and the relationship between applications and people is more direct, relatively leading to higher ARPU values.
10. Summary of NB-IoT and eMTC Performance
Looking at it now, China Mobile’s choice is crucial for the development of China’s IoT industry. On one hand, China Mobile is troubled by the uncertainty of the FDD license issuance time, as well as the much higher cost of building an NB-IoT network compared to the other two operators, and has been hesitating; on the other hand, the eMTC backed by international operators does indeed have unique advantages, but the scale brought by the two standards has not met expectations, which keeps chip and module prices high, further hindering industrial development.
This makes it difficult for China Mobile to make a decision, as an incorrect choice would carry enormous opportunity costs and network costs.
Author: Wang Feng
Source: WeChat Public Account: and (ID: andcm1984)
Submission Email for Network Optimization Mercenaries: [email protected]
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