According to Gartner and IDC research reports, the global Internet of Things connection will exceed 10 billion in 2020, and cellular connections account for more than 10%. In order to meet the connection needs of more and more long-distance IoT devices, low-power wide area networks (LPWA) have emerged. Narrowband Internet of Things (NB-IoT) focuses on the LPWA IoT market and is an emerging technology that can be used globally. With its wide coverage, large capacity, low speed, low cost and low power consumption, it stands out among many LPWA technologies and has become the focus of attention in the industry.
Development and characteristics of NB-IoT
Development of NB-IoT
NB-IoT standardization process
In September 2015, NB-IoT technology was officially written into the 3GPP protocol. In June 2016, 3GPP announced the completion of the NB-IoT standard. The end of the NB-IoT standardization work means that the core protocol for the Internet of Things in Release 13 has been completed.
Operator's promotion of NB-IoT
The birth of new technologies is not necessarily operator-driven, but the rapid development of new technologies is usually driven by operators. From an international perspective, operators have realized the future of the Internet of Things, the new blue ocean, and increased the layout of NB-IoT: South Korea's KT plans to invest 150 billion won to build a new NB-IoT network; Vodafone accelerates the layout of the Internet of Things, Establish NB-IoT open lab, which will study network solution verification, new application innovation, equipment integration, business model research and product qualification verification; DoCoMo will develop M2M business as an important component of its ubiquitous network strategy, through the establishment of platform and embedded The module promotes the development of the M2M market; Sprint promotes the M2M market through an open development strategy. From the domestic perspective, the NB-IoT deployment schedules of the three major operators have been finalized: China Mobile plans to carry out system verification in 2016 and NB-IoT commercialization in 2017; China Unicom plans to promote key cities by the end of 2016 or early 2017. The commercial deployment will be commercially deployed nationwide in 2018; China Telecom plans to deploy an 800 MHz based NB-IoT network in the first half of 2017.
NB-IoT features
The technical characteristics of NB-IoT are mainly reflected in four aspects.
cover
NB-IoT improves coverage by mainly improving power spectral density, transmission repetition and uplink Inter-site CoMP.
Power Spectral Density. NB-IoT adopts narrowband design, downlink bandwidth is 180 kHz, the same transmit power, NB-IoT power spectral density is equivalent to GSM, 8 dB higher than CDMA; NB-IoT uplink bandwidth is 3.75 kHz minimum, GSM terminal transmit power maximum support 2 W, therefore, the NB-IoT uplink power spectral density is 7 dB higher than GSM and 25 dB higher than CDMA.
Send a duplicate. NB-IoT supports up to 128 repetitions. In practice, it generally takes 8 repetitions in the downlink and 16 repetitions in the uplink to obtain a gain of 9 to 12 dB.
Upstream Inter-site CoMP. The NB-IoT uplink introduces IntersiteCoMP technology to achieve a gain of 3 dB. Therefore, NB-IoT can increase the uplink by at least 20 dB, which can meet the wide coverage requirements of suburban and rural areas, as well as deep coverage of urban areas, even in underground garages, basements, underground pipes and other signals. The place can also be covered.
capacity
The low rate requirements of the IoT service and the insensitivity to delay determine that NB-IoT has the characteristics of small packet data transmission and extremely low terminal activation ratio. Moreover, NB-IoT greatly improves spectrum efficiency by reducing air interface signaling overhead. According to the evaluation of related equipment manufacturers, NB-IoT has 50 to 100 times higher uplink capacity than 2G/3G/4G, and can provide 50 to 100 times the access number of existing wireless technology.
Power consumption
3GPP introduced the power-saving mode (PSM) and eDRX technology in the related series of standards, and NB-IoT truly has low power consumption. PSM is a new feature in 3GPP Release 12. In this mode, the terminal is still registered in the network, but the signaling is unreachable, so that the terminal stays in deep sleep for a longer time to save power, and is suitable for delay. Sensitive service; eDRX is a new function in 3GPP Release 13, which is a long-period DRX, which further extends the sleep period of the terminal in idle mode. The longest period is about 3 h, which reduces the signaling processing of the receiving unit, which is relatively large compared to PSM. Improved downlink reachability.
The NB-IoT target is for a typical low-rate, low-frequency sub-business model, with a capacity battery life of more than 10 years. According to the simulation data of 3GPP TR45.820, PSM and eDRX are deployed in a harsh environment with a coupling loss of 164 dB. If the terminal sends 200 B messages once a day, the battery life can reach 12.8 years at 5 Wh.
cost
The terminal chip usually consists of a baseband processing module, a radio frequency module, a power amplifier module, a power management module, and a flash/RAM. Compared with 4G smartphones or other terminals, NB-IoT terminals use narrowband bandwidth of 180 kHz, and baseband modules have low complexity; low data rate and protocol stack simplification can greatly reduce the size of Flash/RAM; single antenna, half-double The way of working can effectively simplify the RF module. Currently, NB-IoT terminal chips can be as low as $1.
NB-IoT frequency deployment plan and recommendations
NB-IoT frequency deployment mode
3GPP defines three deployment scenarios for NB-IoT: Stand-alone, Guard-band, and In-band (see Figure 1).
Independent deployment mainly uses the idle spectrum of the existing network or the new spectrum to deploy NB-IoT.
The protection band deployment utilizes the bandwidth of the LTE network band of the existing network to maximize the utilization of spectrum resources.
In-band deployment utilizes RBs in the LTE network band of the existing network to deploy NB-IoT.
Carrier available frequency analysis
Since TD-LTE does not currently support NB-IoT, it can only be deployed in the FDD band. The licensed FDD bands are mainly Carrier A's CDMA 800 MHz and LTE 1.8/2.1 GHz, Carrier B's (E) GSM 900 MHz and DCS 1.8 GHz, Carrier C's GSM 900 MHz, DCS 1.8 GHz, LTE 1.8 GHz, WCDMA 2.1. GHz. The details are shown in Table 1.
The NB-IoT deployed by the operator can be based on the existing 4G frequency band or the existing 2G and 3G frequency bands (if the NB-IoT is deployed in the 2G and 3G bands, it must first obtain the permission of the national competent authority), or apply for a new one from the country. Band deployment, but applying for a new band deployment is not only difficult, but may not be smoothly upgraded based on the existing network in engineering implementation.
Frequency deployment recommendations
Recommendations for deploying frequency bands
NB-IoT can achieve good wide coverage and deep coverage due to its own technical characteristics. Regardless of the frequency band, as long as the operator achieves better coverage in the 2G, 3G or 4G network in the frequency band, then the NB-IoT network can be deployed based on the frequency band and the existing base station resources to achieve wide coverage and deep coverage. The goal. However, the following two problems are considered: the lower the frequency band, the better the coverage, and the lower the cost of network construction. With the scale deployment of 4G networks and the gradual commercialization of VoLTE services, the services of 2G and 3G networks will gradually move to 4G networks. Migration, the frequency of 2G, 3G networks will gradually retire. It is recommended that NB-IoT networks be deployed in the low-band, such as the CDMA800 MHz and (E) GSM 900 MHz bands, for areas with special conditions for low-band deployments, or for deployment in the 1.8 GHz band.
Recommendations for frequency deployment
Protective tape deployment
In the early stage of LTE re-cultivation of LTE in the 2G and 3G low-band LTE, due to the limitation of frequency resources and the demand for user capacity, LTE with 1.4 or 3 MHz bandwidth is often considered. After the service is completely migrated, LTE is upgraded to 5 MHz. Even a bandwidth of 10 MHz. However, the current LTE 1.4 and 3 MHz bandwidth does not support the protection band deployment mode, and the NBIoT frequency is located in the LTE protection band, and the capacity of both systems will be affected. Therefore, it is recommended that the NB-IoT deployment should not be considered in the initial stage.
In-band deployment
The NB-IoT is deployed in the LTE frequency band and occupies the bandwidth of one RB. In the in-band deployment mode, the bands of the two systems are adjacent, and the degree of mutual influence between the two systems is larger than that of the guard band. To avoid interference, 3GPP defines that the power spectral density of the NB-IoT spectrum and adjacent LTE RBs should not exceed 6 dB. Due to the limitations of PSD, the coverage of NB-IoT is relatively limited in in-band scenarios. When NB-IoT and LTE are not deployed in a 1:1 co-station, there is co-channel interference between NB-IoT and LTE, and the isolation band needs to be set properly.
Independent deployment
For the CDMA 800M band, the spectrum with 895 kHz bandwidth between the 283 and 880 MHz is not utilized, and the NB-IoT can be deployed independently in this band. According to operator A's current 800 MHz frequency re-cultivation strategy, the initial stages of 78 CDMA carrier frequencies (carrier frequencies 37, 78, 119, 160, 201, 242, and 283) are intermediate segments 78, 119, 160, and 201. The CDMA carrier frequency is re-cultivated into LTE. Therefore, deploying NB-IoT on the idle frequency at the upper boundary of CDMA can not only make full use of frequency resources, but also does not have the same-frequency interference of NB-IoT and LTE, but only needs to consider NB-IoT and CDMA, military CDMA and other different systems. Interfere with coexistence issues.
For the (E) GSM 900 MHz band, the GSM carrier bandwidth is 200 kHz and the NB-IoT carrier bandwidth is 180 kHz, which can be used for NB-IoT deployment. This method can be deployed without an LTE system, but it is necessary to reserve 100-300 kHz as an isolation band between the NB-IoT and the GSM system. The specific choice of deployment in (E) GSM 900MHz can be determined by combining interference with systems such as GSM-R, CDMA, and GSM.
NB-IoT network deployment and recommendations
Carrier's existing low-band network analysis
Operator A: Its low-band 800 MHz network carries the current 2G and 3G services, and the network has the comparative advantage of wide coverage and deep coverage. The Ministry of Industry and Information Technology has no letter [2016] No. 193 to agree that Carrier A will carry out LTE networking in the 800MHz frequency band.
Carrier B: The 900 MHz band is one of Carrier B's 2G bands with a bandwidth of 24 MHz (including GSM-R 4 MHz). At present, the re-cultivation of LTE in this frequency band has not been approved by the government authorities, but for the construction of NB-IOT, it is expected that the LTE FDD license for this frequency band will be available by the end of 2016.
Carrier C: The 900 MHz band is one of Carrier C's 2G bands with a bandwidth of only 6 MHz. The Ministry of Industry and Information Technology has no letter [2016] No. 194 to agree that Carrier C conducts LTE technology tests for the 900 MHz band in several provinces and cities. However, for Carrier C, it has only 6MHz bandwidth resources in the 900 MHz band, and the choice of networking mode will be a problem.
Network deployment proposal
Option 1: NB-IoT after LTE first
The basic idea
In the case of low-band 2G, 3G frequency with retire conditions and re-farming LTE licensed, it is recommended to deploy low-band LTE networks while requiring network synchronization to carry NB-IoT capabilities. This enables smooth upgrade through low-band LTE networks and supports NB-IoT service deployment.
implementation plan
Low-band cultivating LTE network can achieve coverage level of 2G and 3G networks in this frequency band. NBIoT is deployed based on LTE network after re-cultivation. There are two ways: NB-IoT and LTE site 1:1 construction, one step in place; make full use of NB-IoT 20 dB coverage gain, select LTE coverage station upgrade to NB-IoT, to achieve similar coverage with LTE network. When there is capacity demand in the later stage, select the corresponding LTE site to upgrade to NB-IoT according to different scenarios.
Since the investment mainly occurs in the LTE phase, it is recommended to adopt the 1:1 construction mode of NB-IoT and LTE sites.
Option 2: LTE after NB-IoT
The basic idea
If it is not possible to vacate enough frequencies in the low-band to support the deployment of LTE in the short-term, you can first build a NB-IoT network with lower bandwidth requirements in the low frequency band, and require synchronization to upgrade to LTE. When the frequency condition is met, the low-band LTE network deployment is realized through smooth upgrade.
implementation plan
According to the survey, among the existing 2G networks of operators, only a few GSM devices can support G/N/F dual channels, which can be upgraded to NB-IoT and LTE. Some GSM devices support G/N single channel and can be upgraded to NBIoT. Other devices do not support direct upgrade to NB-IoT or LTE. They can only be replaced or newly created. The upgrade is first to NB-IoT, and then the original equipment is replaced in the LTE phase. The investment mainly occurs in the LTE phase. It is recommended that NB-IoT be built with the existing site 1:1; deploy NB directly by replacing or newly creating. In the case of -IoT, the investment mainly occurs in the NB-IoT deployment phase. It is recommended to fully utilize the NB-IoT 20 dB coverage gain, select the coverage station to deploy NB-IoT, and later re-cultivate LTE and then upgrade the non-NB-IoT station.
Solution 3: Simultaneous deployment of LTE and NB-IoT is relatively simple. Simultaneous deployment of NB-IoT in low-band 2G and 3G networks. It is a special case of Option 1.
According to the current plan, all standards of 3GPP and CCSA for NB-IoT will be completed in the next few months, and the scale and scope of operators' pilot and deployment of NB-IoT will continue to expand. For some problems that may occur in the pre-deployment and deployment process of NB-IoT networks, this paper has carried out targeted research, expounded the specific application schemes of NB-IoT various frequency deployment methods, and proposed NB-based on the existing network. IoT network deployment plan and recommendations.
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