Software-defined radio system for providing low-cost, limited private rural service.

Description

/ 14 Software-Defined Radio System for Providing Low-Cost Private Rural Limited Service Field of invention

[001] The present invention pertains to the wireless network communications sector. It is a software-defined radio (SDR) system that extends local internet coverage over a long distance around a farm or rural industry, constituting a private rural 4G network in the 700 MHz SLP (Private Limited Service) frequency band, compatible with IoT (Internet of Things) devices that use the LTE-M (Log Term Evolution for Machines) or NB-IoT (Narrowband Internet of Things) protocol. Fundamentals of the invention

[002] The present invention is based on the following technologies: SDR, 4G cellular communication system, LTE-M and NBIoT wireless communication protocols, as well as open 4G software. Also related to the present invention are Anatel regulations on the use of frequency bands for SLP and the concept of an isolated private network.

[003] SDR is an emerging concept in the field of wireless communication systems. It allows defining a wireless communication system in which signal processing tasks are performed through software instead of specific hardware. Currently, there are several manufacturers of SDRs, which are marketed as boards or modules, with USB or PCI interfaces for connection to a "host" such as a PC, depending on the model. In the present invention, low-cost SDR models are used regardless of their interface.

[004] The 4G system is the 4th generation cellular technology used worldwide for mobile communication. The main radio technology (air interface) used is LTE (“Long Term Evolution”), which is a wireless standard for transmitting data at high bit rates such as HD video streaming. 4G is a standardization of 3GPP (“3rd generation” standard). Petition 870250012893, dated 17 / 02 / 2025, page 6 / 28 / 14 The Generation Partnership Project”) and, since its inception in 2008, various features have been added to the technology each year in the form of “releases.” Particularly important for the present invention is release 13, which introduced the LTE-M and NB-IoT wireless communication protocols in addition to LTE.

[005] A 4G base radio station is called an eNB (or eNodeB). In terms of transmission power, an eNB is classified by 3GPP as: macro eNB (“Wide Area Base Station”), micro eNB (“Medium Range Base Station”), and femtocell (“Local Area Base Station”), as shown in Table 1. Depending on the terrain and antenna height, the cell radius of a macro eNB can reach 30 km, while the cell radius of a micro eNB can reach up to 2 km. However, as shown in Table 1, the cost of a macro eNB is much higher than that of a micro eNB. Typically, a macro eNB operates in lower frequency bands allocated to the mobile operator, aiming to obtain the greatest possible coverage, while the micro eNB operates in higher frequencies to cover shadow areas left by the macro eNB, or to relieve traffic congestion from the macro eNB as well as offer greater throughput to the user.Thus, the radius of a micro eNB cell is smaller than that of a macro eNB not only due to lower transmission power, but also because it operates at higher frequencies. A femtocell, on the other hand, typically operates indoors and competes with WiFi, operating at high frequencies with a small coverage radius but offering high throughput to the user. The system of the present invention is classified as a micro eNB with the following advantages: a) Significantly larger cell radius of approximately 5 km, because instead of operating at high frequencies, it operates at 700 MHz. Better coverage is obtained in the 700 MHz frequency range, as these frequencies propagate over greater distances and penetrate obstacles better than higher frequencies; b) Lower cost than presented in Table 1 thanks to the use of low-cost SDRs.

[006] eNBs utilize MIMO (“Multiple-Input Multiple-Output”) technology in order to take advantage of multipath effects to increase throughput instead of causing interference. The efficiency of MIMO technology in rural areas tends to be lower compared to urban areas due to less pronounced multipath effects, greater distances involved, and lower frequencies used to achieve this. Petition 870250012893, dated 02 / 17 / 2025, p. 7 / 28 / 14 greater coverage and penetration. For these reasons and to keep costs low, the present invention utilizes SISO (“Single Input Single-Output”) technology. Table 1: Cellular base station classes according to 3GPP Class Macro eNB (or eNodeB) Micro eNB (or eNodeB) Femto cell BS (“Base Station”) Type Macro cell Micro cell Pico cell Transmission power No upper power limit < 38 dBm or 6.3 W < 24 dBm or 0.25 W Cell radius 1 km to 30 km 200 m 2 km 4 m 200 m Average equipment cost (US$)(*) 100,000.00 - 250,000.00 5,000.00 - 15,000.00 150.00 - 1,000.00 (*) Sources: Telecom industry reports, supplier prices and consultations with industry experts.

[007] LTE-M or LTE-MTC (Long-Term Evolution Machine Type Communication) is a wireless communication protocol for LPWAN (“Low-power, wide-area networks”). It is a protocol for IoT applications standardized by 3GPP. LTE-M includes eMTC (enhanced Machine Type Communication), also known as LTE CatM1, whose specification was completed in 3GPP release 13. The SDR system of the present invention is a flexible system that can add, via software, the LTE-M protocol to LTE and is referred to in this case as a 4G / LTE / LTE-M system.

[008] NB-IoT (“Narrowband Internet of Things”) is also a wireless communication protocol for LPWAN and competes with LTE-M. Like LTE-M, the NB-IoT specification was finalized in 3GPP release 13. In general, the Petition 870250012893, dated 17 / 02 / 2025, page 8 / 28 / 14 NB-IoT offers a lower bit rate than LTE-M, but allows for longer battery life for IoT devices, since sensor connections using NB-IoT consume less energy than LTE-M. The SDR system of the present invention is a flexible system that can add, via software: a) The NB-IoT protocol to LTE, in which case it is called a 4G / LTE / NB-IoT system; b) The NB-IoT protocol to LTE and LTE-M, in which case it is called a 4G / LTE / LTE-M / NB-IoT system.

[009] Among various SDR applications, open-source 4G cellular system software implementations, including protocol layer stacks and physical layer, are widely used in research. The two main open-source 4G cellular system software packages are: srsRAN and Openairinterfeace5G (OAI), developed by Software Radio Systems (SRS) and the French organization OSA, respectively. Up to the present invention, open-source 4G software is not complete in its functionality to the extent that it can be used in commercial products, which need to be properly certified. For example, none of the open-source software packages implement the test models (E-TM: E-UTRA Test Models) defined by 3GPP, which are necessary for evaluating LTE signal characteristics in certification tests.Regarding the LTE-M protocol, only OAI has an implementation, but it does not operate in conjunction with the LTE protocol in a way that allows simultaneous connection and data transmission between 4G mobile phones and LTE-M devices. As for the NB-IoT protocol, OAI has attempted an implementation, but its EPC (“Evolved Package Core”: the network core of a 4G network) implementation is not compatible with the NB-IoT protocol. In the present invention, the E-TM test models were implemented for LTE radio technology and approved in homologation tests conducted in a laboratory accredited by Anatel. Subsequently, the LTE-M and NB-IoT protocols were implemented and integrated with LTE radio technology, tested, and validated in a real field environment.

[0010] SLP is a telecommunications service of restricted interest, operated nationally and internationally under a private regime, encompassing multiple applications, including: data communication, video and audio signals, voice, and text. SLP is regulated in Brazil by Anatel through Resolution No. 617, of June 19, 2013. Among the various frequency bands available for SLP, four are... Petition 870250012893, dated 02 / 17 / 2025, page 9 / 28 / 14 suitable for rural areas in terms of coverage: 225 - 270 MHz (45 MHz), 410 - 415 MHz / 420 - 425 MHz (3GPP band 87), 452.5 - 457.5 MHz / 462.5 - 467.5 MHz (3GPP band 31) and 703 - 708 MHz / 758 - 763 MHz (3GPP band 28). The first band mentioned is not a 3GPP standard and therefore does not have availability of COTS (Commercial Off-The-Shelf) terminals, such as smartphones and LTE-M and NB-IoT sensors, which is a major disadvantage. The 400 MHz frequency bands, despite belonging to the 3GPP standard, have very little availability of COTS terminals. The 700 MHz bands belong to the 3GPP standard and have the advantage of a high availability of COTS terminals.

[0011] Private Networks are considered by Anatel Resolution No. 73, of November 25, 1998, as networks for telecommunications services of restricted interest, which is that intended for the use of the operator itself or provided to specific groups of users, the main type being SLP. A 4G private network can be of the following types: a) Isolated Private Network; b) Private Network with Shared RAN (“Radio Access Network”); c) Private Network with Shared RAN and Control; d) Contracted Private Network. The present invention applies to a rural Isolated Private Network (RPI), which is a network in a rural region independent of the mobile operator, and may be connected to the public internet network through a firewall. All network functions are located within the logical perimeter of the user's installation (for example, the rural factory or farm headquarters).The rural industry / farm or a technology operator is responsible for the overall operation of the network and uses its own frequency band.

[0012] Currently, several companies such as Huawei, Nokia, Motorola, etc., are manufacturers of 4G systems. However, these systems, hereinafter referred to as conventional 4G systems, have been developed to serve large urban centers, where several eNB stations are needed per geographic service area. Each eNB serves the data traffic of a large number of users and requires a high-capacity backhaul. Additionally, urban areas have many obstructions and high user mobility. To meet this scenario, a conventional 4G system incorporates complex functionalities from the 3GPP specifications such as handover and MIMO (Multiple-Input Multiple-Output). Also, for the purposes of planning, operation and optimization flexibility of Petition 870250012893, dated 02 / 17 / 2025, page 10 / 28 / 14 performance in urban areas, operates in various frequency bands and with different bandwidths. Therefore, conventional 4G systems are high-cost and economically unfeasible for most rural RPI cases. Additionally, manufacturing a conventional 4G system demands high specialization, not only in software production but also in highly complex hardware, such as the production of boards with high baseband processing capacity and specific radio frequency (RF) boards. In the present invention, the high cost and complexity of manufacturing a 4G system is avoided by using low-cost SDR combined with several peculiar aspects of a rural RPI, which allow for software and hardware simplification, resulting in cost reduction and manufacturing simplification: a) In a rural RPI, an eNB with wide coverage is needed.a) Thus, the “handover” function is no longer important, as there will typically be only one or a few eNBs per rural RPI. b) In a rural RPI, even if it is geographically extensive, the user density is low and IoT devices require low bit rates. Thus, data traffic through an eNB in ​​a rural RPI is so low that it can be handled by a low-capacity, low-cost backhaul such as a StarLink antenna. c) In a rural RPI, SISO (“Single-Input Single-Output”) antenna technology can be used to simplify the system and lower its cost, since the use of MIMO in rural areas tends to result in low gain, as explained in paragraph

[006] . d) In a rural RPI, the 4G system must operate at low frequencies and with narrow frequency bandwidth.In the case of the 700 MHz frequency band (band 28 of 3GPP), a 4G system for rural RPIs should operate in FDD mode with a bandwidth of 5 MHz, which facilitates the use of low-cost commercial SDRs.

[0013] Low-cost commercial SDR models present the following limitations for application as a radio unit in a 4G system: a) Internal clock accuracy: does not meet the clock stability specification of ± (0.1 ppm + 12 Hz) for eNB. b) ACLR (“Adjacent Channel Leakage power Ratio”): does not meet the requirement for undesirable emissions outside the channel band for eNB, specified at 44.2 dB relative to the LTE signal power at maximum load. In the present invention, these problems are overcome as follows: a) Internal clock accuracy: through the use of a high-precision external clock tied to the GPS signal. b) Petition 870250012893, dated 17 / 02 / 2025, page 11 / 28 / 14 ACLR: To mitigate unwanted emissions, the bandwidth of the SDR digital transmission filter is optimized to increase attenuation outside the channel bandwidth without impacting LTE signal quality.

[0014] Thus, the present invention consists of a low-cost SDR system, where the physical layer and 4G / LTE, LTE-M and / or NB-IoT protocol software are optimized, in terms of performance, for the SLP frequency band at 700 MHz, propagation characteristics and data traffic of a typical rural RPI.

[0015] Additionally, the present invention is a low-cost system that meets the Anatel homologation requirements, as verified through tests in accredited laboratories, and has the capacity to provide HD video streaming and data transmission services at low bit rates.

[0016] HD video streaming is transmitted using the 4G / LTE standard, while low bitrate data transmitted by IoT devices uses the LTE-M or NB-IoT protocol.

[0017] Unlike a conventional eNB, the system of the present invention allows for its installation and operation by the user. A conventional eNB is integrated and connected to the mobile operator's network core. Additionally, it operates within frequency bands licensed to the mobile operator and not to the user. Therefore, it is not possible for a conventional eNB to be operated by the user from a technical standpoint (dependence on the mobile operator's network core) and due to legislation regarding the use of frequency bands. In the present invention, the dependence on the mobile operator's network core and the restriction on the use of licensed frequency bands are resolved as follows: a) To resolve the dependence on the mobile operator's network core, the system of the present invention has its own embedded configurable network core.In this way, it functions as an eNB that does not need to connect to the network core of any mobile operator, facilitating its installation as "plug and play" and its operation by the user himself. b) Licensed frequency bands: the system of the present invention operates in a frequency band intended for SLP at 700 MHz, whose authorization for use can be granted to the user himself according to Anatel regulations. Petition 870250012893, dated 17 / 02 / 2025, page 12 / 28 / 14 Brief description of the drawings

[0018] The system of the present invention is described below with reference to its typical embodiments and with reference to the following appended figures: Figure 1 presents the inventive concept of extending internet coverage provided by the present invention. Figure 2 illustrates a typical embodiment of the present invention with two omnidirectional or sectorial antennas. Figure 3 presents the results of the ACLR tests of the LTE signal in the E-TM 1.1 test mode of the present invention. Figure 4 presents the results of the ACLR tests of the LTE radio signal in the E-TM 1.2 test mode of the present invention. Figure 5 illustrates a cell provided by the present invention with two omnidirectional antennas. Figure 6 illustrates a 1-sector cell provided by the present invention with two sector-type antennas. Figure 7 illustrates a typical embodiment of the present invention with 4 sector-type antennas. Figure 8 illustrates a 2-sector cell provided by the present invention with 4 sector-type antennas. Figure 9 illustrates a typical embodiment of the present invention with 6 sector-type antennas. Figure 10 illustrates a 3-sector cell provided by the present invention with 6 sector-type antennas. Figure 11 illustrates a typical embodiment of the energy subsystem of the present invention. Petition 870250012893, dated 17 / 02 / 2025, p. 13 / 28 / 14 Description of the invention

[0019] The present invention relates to an SDR system that extends local internet coverage to a distance of approximately 5 km, depending on the height of the antennas and terrain, and can be installed and operated by the user himself, as illustrated in Figure 1. The internet in the local environment (1) is provided via satellite (11) through an antenna (2) and a WiFi router (3), but can be provided by any other means such as, for example, radio link. The WiFi router (3) provides wireless internet coverage (6) of 100-200m radius. The system of the present invention (4) connects to the WiFi router (3) at one of its LAN ports via a network cable (5). Depending on the height of its antennas (7) and the terrain (8) of the region, the system of the present invention provides an extended internet coverage (9), creating a rural 4G RPI, up to a distance of approximately 5 km. Thus, the surroundings (10) of the rural industry / farm now have internet coverage.The rural 4G RPI can be configured, via software, to support the following 3GPP standards: a) 4G / LTE: this standard provides internet coverage compatible with conventional 4G devices such as cell phones, cameras, 4G / WiFi routers, etc., and allows HD video streaming; b) 4G / LTE / LTE-M: standard compatible with conventional 4G devices and IoT devices that use the LTE-M protocol for low-rate (measured) data transmission; c) 4G / LTE / NB-IoT: standard compatible with conventional 4G devices and IoT devices that use the NB-IoT protocol; d) 4G / LTE / LTE-M / NB-IoT: standard compatible with conventional 4G devices and LTE-M and NB-IoT devices.

[0020] The system of the present invention, illustrated in more detail in Figure 2, consists of a low-cost SDR (13), mini-PC (12), RF power amplifier (14), high-precision clock generator tied to the GPS signal (15), transmission antenna (16) and reception antenna (17). The mini-PC (12) incorporates, in addition to the drivers and software of the SDR itself (13), the physical layer and 4G / LTE, LTE-M and / or NB-IoT protocol software, as well as the network core (EPC). The software is minimized and optimized for the SLP frequency band at 700 MHz, characteristic of the propagation and data traffic of a typical rural RPI. Because the system operates in the SLP frequency band and has its own embedded network core, it can operate independently of a mobile operator, as well as be installed and used by Petition 870250012893, dated 17 / 02 / 2025, page 14 / 28 / 14 own user. To meet the homologation requirements, all E-TM test models are implemented. Additionally, a digital filter is implemented in the SDR transmitter (13) so that the LTE signal, in the various E-TM test models, meets the ACLR requirements for micro eNB. The RF amplifier (14) is used to amplify the LTE signal at the SDR output (13) to the power level limits of a micro eNB. The high-precision clock generator tied to the GPS signal (15) is necessary to meet the frequency stability requirements of micro eNB. As illustrated in figure 7, in the case of using more than one pair of antennas, it is necessary to use a “splitter” for transmission (34) and another for reception (35), since low-cost SDRs have only one Tx antenna port and one Rx antenna port.

[0021] The system of the present invention, having its network core embedded and operating in the 700 MHz frequency band for SLP, has easy installation, which is of the “plug and play” type. Additionally, being a low-power consumption system, powered by the power supply of a mini-PC itself, it allows it to be powered by low-power solar panels in places without power infrastructure. Examples of embodiments of the invention

[0022] Figure 2 illustrates a typical embodiment of the present invention on a low-cost hardware consisting of: mini-PC (12), SDR module (13), PA (“Power Amplifier”) module (14), high-precision clock generator module tied with GPS signal (15), GPS antenna (18), transmitting antenna (Tx) (16) and receiving antenna (Rx) (17).

[0023] As mentioned in paragraph

[0013] , low-cost commercial SDRs do not meet the clock frequency stability specification of ± (0.1 ppm + 12 Hz) for micro eNB. In the present invention, to solve this problem, an external clock received from a high-precision clock generator module tied with the GPS signal (15) is used.

[0024] A sample of the illustrated embodiment in Figure 2, developed for LTE technology, was submitted to homologation tests in the laboratory of Petition 870250012893, dated 17 / 02 / 2025, page 15 / 28 / 14 CPqD, which is accredited by Anatel. The tests were carried out in the 700 MHz band, using a low-cost SDR (13) from Lime Microsystems, model LimeSDR mini 2.0, and an external clock received from a clock generator module tied with the low-cost GPS signal (15), brand Leo Bodnar Electronics, model “Mini Precision GPS Reference Clock”.

[0025] Table 2 presents the results obtained from frequency stability measurements. The columns of Table 2 are: a) Channel and Fc (MHz): these are the channels tested and their center frequencies in MHz, respectively; b) BW (MHz): this is the bandwidth in MHz of each of the channels tested, and in the present invention, a bandwidth of 5 MHz is of interest; c) Modulation: these are the modulations used in each of the channels according to the test requirements; d) Test Mode: these are the E-TM test models defined by 3GPP, which are not implemented in open 4G / LTE software, but have been implemented in the present invention; e) PPM and Frequency Error (Hz): these show the results obtained from frequency stability measurements; f) Limit: this is a frequency stability requirement for micro eNB according to 3GPP and Anatel standards.The results obtained show that, although the oscillator used on the LimeSDR mini board has a frequency stability of ±2.5 ppm, the frequency stability achieved is on the order of ±0.01 ppm, thanks to the adopted high-precision external clock strategy. Therefore, in terms of frequency stability, the results in Table 2 demonstrate that the system of the present invention meets the 3GPP and Anatel homologation requirements for micro eNB.

[0026] Furthermore, as mentioned in paragraph

[0013] , low-cost commercial SDRs also do not meet the ACLR requirement for eNB. In the present invention, undesirable emissions are mitigated by increasing the attenuation of the SDR's digital transmission filter outside the channel bandwidth. Figure 3 shows the results obtained from ACLR tests with the LTE signal at maximum load in E-TM 1.1 mode, where the following are presented: a) The spectrum of the LTE signal (Tx1) at maximum load in E-TM 1.1 mode. b) Undesirable emissions in the upper adjacent channel (Adj-Upper), upper adjacent channel +1 (Alt1-Upper), lower adjacent channel (Adj-Lower) and lower adjacent channel -1 (Alt1-Lower). As shown, the undesirable emissions due Petition 870250012893, dated 17 / 02 / 2025, p. 16 / 28 12 / 14 to LTE signal with maximum load in E-TM 1.1 mode are below the specified limit of -44.2 dB.

[0027] Similarly, Figure 4 shows the results of the ACLR tests with the LTE signal at maximum load in E-TM 1.2 mode (Tx1). As shown, also in ETM 1.2 mode, the unwanted emissions of the LTE signal at maximum load in this mode are below the specified limit of -44.2 dB.

[0028] Therefore, the results of homologation tests presented in table 2 and figures 3 and 4 demonstrate the technical validity of the embodiment of the present invention illustrated in figure 2 for commercial applications. Table 2. Frequency stability results Channel Fc (MHz) BW (MHz) Modulation Test Mode PPM Frequency Error (Hz) Limit 9235 760.5 5.00 64QAM E-TM3.1 0.01470 11.18 (±0.1 ppm +12Hz) 9435 780.5 0.01455 11.36 9635 800.5 0.01102 8.82 9235 760.5 5.00 16 QAM E-TM3.2 0.01335 10.15 (±0.1 ppm +12Hz) 9435 780.5 0.01677 13.09 9635 800.5 0.01240 9.93 9235 760.5 5.00 QPSK E-TM3.3 0.01440 10.95 (±0.1 ppm +12Hz) 9435 780.5 0.01521 11.87 9635 800.5 0.01560 12.49 9235 760.5 5.00 64 QAM E-TM2 0.01661 12.63 (±0.1 ppm +12Hz) 9435 780.5 0.01092 8.52 9635 800.5 0.01197 9.58

[0029] As can be seen in Figure 2, to reduce costs and due to the limited number of RF ports on low-cost SDR boards, the system of the present invention consists of separate antenna ports for Tx (24) and Rx (22), where the Tx port (24) is the output of the PA (14). The input port (23) of the PA (14) is connected directly to the output port (21) of the SDR (13) via a coaxial cable (26). The Tx (16) and Rx (17) antennas can be of the omni or sector type. If they are of the omni type, the result is a theoretically circular wireless internet coverage, called an omni cell (32). Petition 870250012893, dated 17 / 02 / 2025, page 17 / 28 / 14 as illustrated in figure 5. If the Tx (16) and Rx (17) antennas are of the sector type, only a part of the coverage of an omni cell is obtained, called a 1 sector cell (33), as illustrated in figure 6. The distance, ds, from the edge of the 1 sector cell (33) to the location of the Tx (16) and Rx (17) antennas is greater than the radius, do, of an omni cell (32). This characteristic of greater coverage distance, using sector type antennas, can be advantageous depending on the desired geographic format of internet coverage.

[0030] The typical embodiment illustrated in figure 2, although submitted to homologation tests with 4G / LTE software embedded in the mini-PC (12), is also valid for the following software: 4G / LTE integrated with LTE-M (4G / LTE / LTEM), 4G / LTE integrated with NB-IoT (4G / LTE / NB-IoT), 4G / LTE integrated with LTE-M and NB-IoT (4G / LTE / LTE-M / NB-IoT). The physical layer, eNB protocol layers and network core protocol layers processing are performed in the mini-PC (12).

[0031] Figure 7 illustrates a typical embodiment of the present invention where 4 sector antennas are used as follows: - Tx antennas: (16) and (36); - Rx antennas: (17) and (37). For the use of 4 antennas, as the system of the present invention has only 1 Tx output port (24) and 1 Rx input port (22), a “2-way Splitter” module is used on the Tx (34) and another on the Rx (35). As shown in Figure 8, in this embodiment with 4 sector antennas, a 2-sector cell is obtained: a) Sector 1 (38): Tx antenna (16) and Rx antenna (17); b) Sector 2 (39): Tx antenna (36) and Rx antenna (37).

[0032] Figure 9 illustrates a typical embodiment of the present invention using 6 sector antennas: - 3 Tx antennas: (16), (36) and (42); - 3 Rx antennas: (17), (37) and (43). The use of 6 sector antennas results in a 3-sector cell, whose shape is almost circular, as illustrated in Figure 10, formed by: a) Sector 1 (44) which is the area covered by the Tx (16) and Rx (17) antennas; b) Sector 2 (45) which is the area covered by the Tx (36) and Rx (37) antennas; c) Sector 3 (46) which is the area covered by the Tx (42) and Rx (43) antennas. As illustrated in Figure 9, since the system of the present invention has only 1 Tx output port (24) and 1 Rx input port (22), a “3-way Splitter” module is used on the Tx (40) and another on the Rx (41). The remainder of Petition 870250012893, dated 17 / 02 / 2025, page 18 / 28 / 14 components is the same as the embodiment shown in Figure 2, as are the processes performed on each of them. The advantage of the embodiment of the present invention with 6 antennas is the achievement of a larger coverage area compared to the 2 previous embodiments with 2 and 4 antennas shown in Figures 2 and 7, respectively.

[0033] The system of the present invention is low energy consumption. In the embodiments illustrated in Figures 2, 7 and 9, all the energy of the system of the present invention is derived from the mini-PC's own power supply (12), as illustrated in Figure 11. The power supply (48) connects to a 100-240 VAC power point, via a standard ABNT male plug (47), consumes a maximum of 1.8 A and provides a power of up to 120 W, which is sufficient for the entire system of the present invention. The output of the power supply (48) is diverted to the power input of the mini-PC (12) and to the input of a DC-DC converter (44), which supplies power to the PA (14). Thus, the system of the present invention is low power consumption and can be installed in places where there is no power infrastructure or internet access point, such as in the field of a farm / rural industry.In such locations, the system of the present invention can be powered by a low-power solar panel and connected to an internet access point via a StarLink router and antenna. Petition 870250012893, dated 17 / 02 / 2025, page 19 / 28

Claims

1 / 2 CLAIMS 1. System characterized by operating in the private limited service (SLP) frequency band at 700 MHz defined by Anatel, employing a low-cost commercial SDR (“Software Defined Radio”) module or board.

2. System according to claim 1, characterized by having its own embedded network core for operation independently of a mobile operator or without the need for connection to the network core of a mobile operator.

3. System according to claim 1, characterized by its "plug and play" installation, allowing it to be performed by the user themselves, as well as its operation.

4. System according to claim 1, characterized by allowing the creation of a private rural 4G network, of the isolated type, by the user himself, compatible with conventional 4G terminals (cell phones, 4G / WiFi routers, cameras, etc.), IoT devices that use LTE-M protocol and / or IoT devices that use NB-IoT protocol, depending on the embedded software package.

5. System according to claim 1, characterized by low-cost hardware consisting of a mini-PC, SDR module or board, RF power amplifier module, high-precision clock generator module linked to a GPS signal, and a pair of antenna ports, one for the transmitting antenna (Tx) and the other for the receiving antenna (Rx), allowing for omnidirectional or sectorized cell operation depending on the type of antennas used.

6. System according to claim 1, characterized by using "splitter" modules for operation with more than one pair of antennas. Petition 870250012893, dated 17 / 02 / 2025, page 26 / 28 2 / 2 7. System according to claim 1, characterized by using as "backhaul" any internet access point provided by any means such as radio, Starlink antenna, etc.

8. System according to claim 1, characterized by having all the necessary energy supplied by the power supply of the mini-PC that comprises its hardware.

9. System according to claim 1, characterized by its low consumption, allowing the necessary energy to be supplied by a low-power solar panel. Petition 870250012893, dated 02 / 17 / 2025, pp. 27 / 28

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