Patent Application
20230092573
The invention relates to the extension of a Low Power Wide Area Network (LPWAN), especially a Long Range Wide Area Network (LoRaWAN), a specification for wireless battery-powered systems in a regional, national or even global network. LoRaWAN serves the key requirements of the Internet of Things (IoT), in particular secure bidirectional communication, localisation and mobility. The LoRaWAN specification is a layered protocol (Media Access Control MAC) and is designed for large public networks with a single operator. It is based on the LoRa modulation scheme of the company Semtech and offers seamless cooperation of different systems and techniques without the need for inflexible, local, complex installations.
The network architecture of LoRaWAN is typically built in a star topology, with gateways acting as transparent bridges that relay messages between end devices and a central network server, end devices and back-end. The gateways are connected to a corresponding network server via a standard IP connection, while the end devices use single-hop wireless communication (LoRa) to one or more gateways. The endpoint communication is usually bidirectional and also supports the operation of, for example, multi-cast enabling software upgrade over the air or other ways for bulk distribution of messages to reduce transmission time over the air communication. Communication between gateways and end devices is spread over different data rates and frequency channels, where the choice of data rate is a trade-off between message duration and communication range. Through so-called spread spectrum technology, communications at different data rates do not interfere with each other, creating a series of virtual channels that increase the capacity of the respective gateways. LoRaWAN data rates range from 0.3 kbps up to 50 kbps. To maximise the battery life of the overall network capacity and end devices, the LoRaWAN network server manages the RF output and data rate for all end devices individually using an adaptive data rate scheme. While LoRaWAN defines the communication protocol and system rights for the network, the LoRa layer enables a wide-range wireless communication link. LoRa involves wireless communication with very low power consumption. LoRaWAN refers to a network protocol using LoRa chips for communication and is based on a base station that can monitor eight frequencies with multiple spreading factors with almost 42 channels. With its star topology (LoRaWAN) and energy-saving signal transmission technology (LoRa), the LoRaWAN network technology is specifically designed for the energy-efficient and secure networking of end devices in the Internet of Things and is also particularly suitable for outdoor use.
This Internet of Things places various demands on the network technology used. The architecture is designed for thousands of end devices, which can be located far away, in populated and non-populated areas and in places that are difficult to access, and includes sensors that monitor the water flow or irrigation systems, as well as consumption meters and much more. The requirements of the outdoor application must safely support battery-powered end devices while greatly simplifying installation and maintenance, thus only communication operation can be considered. Strict power consumption specifications for end devices must also be taken into account, as they must operate for several years on a single battery only.
LoRa has particularly low energy consumption and is based on chirp frequency spread modulation in accordance with U.S. Pat. No. 7,791,415 B2. Licences for use are issued by the company Semtech. LoRa uses licence-free communication frequencies in the range below 1 GHz, such as 433 MHz and 868 MHz in Europe or 915 MHz in Australia and North America, and thus enables a range of more than 10 kilometres in rural areas with very low energy consumption. LoRa technology consists on the one hand of the physical LoRa protocol and on the other hand of the LoRaWAN protocol, which is defined and managed as the upper network layer by the industry consortium “LoRa Alliance”. LoRaWAN networks implement a star-shaped architecture by means of gateway message packets between the end devices and the central network server. The gateways (also called concentrators or base stations) are connected to the network server via the standard internet protocol, while the end devices communicate with the respective gateway via communication using LoRa (chirp Spread Spectrum modulation) or FSK (frequency modulation). The connection is thus a single-hop network in which the end devices communicate directly with one or more gateways, which then forward the data traffic to the internet. Conversely, the data traffic from the network server to an end device is only routed via a single gateway. Data communication basically works in both directions, but data traffic from the end device to the network server is the typical application and the predominant mode of operation. By bridging greater distances with very low energy consumption, LoRaWAN is particularly suitable for IoT applications outside of residential areas, such as for automatic irrigation systems or the measurement of environmental parameters in agriculture.
At the physical level, LoRaWAN, like other communication protocols for IoT applications, uses spread spectrum modulation. It differs by using an adaptive technique based on chirp signals, in difference to conventional DSSS (direct sequence spread spectrum signalling). Chirp signals offer a compromise between reception sensitivity and maximum data rate. A chirp signal is a signal whose frequency varies over time. LoRaWAN technology is inexpensive to implement because it does not rely on a precise clock source. The ranges of LoRa extend up to 40 kilometres in rural areas. In the city, the advantage is good building penetration, as even basements can be reached. The power requirement is very low, at around 10 nA and 100 nA in stand-by mode. Thus, a battery life of up to 15 years is achievable.
In addition to the physical layer, LoRa/LoRaWAN defines two further layers. Layer 2 is the LoRaWAN link layer, which provides basic message integrity protection based on cyclic redundancy checks and enables basic point-to-point communication. The third layer adds the network protocol function, which is defined by LoRaWAN. The LoRaWAN protocol allows end devices to send data to and receive data from the internet, especially to and from a cloud application, using a gateway (also called a concentrator or base station).
There are different variants for the end devices. Class A includes communication according to the ALOHA access procedure. With this procedure, the device sends its generated data packets to the gateway, followed by two download-receive windows, which can be used for a data reception. A new data transfer can only be initiated by the end devices during a new upload. Class B end devices, on the other hand, open download receive windows at specified times. For this purpose, the end device receives a time-controlled beacon signal from the gateway. In this way, a network server knows when the end device is ready to receive data. Class C end devices have a permanently open download receive window and are thus permanently active, but also have increased power consumption.
LoRaWAN uses a star network architecture in which all end devices communicate via the most appropriate gateway. These gateways take care of routing and, if there is more than one gateway within range of an end device and the local network is overloaded, they can also redirect communication to an alternative.
Some other IoT protocols (for example Zig Bee or Z-Wave), on the other hand, use so-called mesh network architectures to increase the maximum distance of an end device from a gateway. The end devices of the mesh network forward messages to each other until they reach a gateway, which transmits the messages to the internet. Mesh networks are self-programming and adapt dynamically to environmental conditions without the need for a master controller or hierarchy. However, in order to be able to forward messages, the end devices of a mesh network must be ready to receive either constantly or at regular intervals and cannot be put into stand-by for long periods of time. The consequence is a higher energy demand of the end devices for forwarding messages to and from the gateways as well as a resulting shortening of the battery life.
The star network architecture of LoRaWAN, on the other hand, allows the end devices (especially class A and B) to put themselves into the power-saving stand-by mode over long periods of time and thus ensures that the battery of the end devices is loaded as little as possible and can thus be operated for several years without changing the battery. The gateway acts as a bridge between simple protocols optimised for battery life (LoRa/LoRaWAN), which are more suitable for resource-constrained end devices, and the Internet Protocol (IP), which is used to provide IoT services and applications. After the gateway receives the data packets from the end device via LoRa/LoRaWAN, it sends them via the Internet Protocol (IP) to a network server, which in turn has ports to IoT platforms and applications.
However, existing LoRaWAN networks also have undesirable limitations. One such limitation is in particular the use of the standard IP protocol between gateway and network server. Especially when used in rural areas, where network coverage for mobile communication (3G, 4G/LTE or even 5G) is sparse or non-existent and a wired internet connection would be too costly, a gateway often cannot be operated due to the lack of an internet connection. LoRa networks can therefore so far only be used where the maximum communication range between the gateway connected to the internet and the end devices is not exceeded. Due to the star network architecture, the range of a LoRaWAN network is thus limited to the maximum range of the single-hop connection between the gateway and the end device. This limitation applies in particular to remote, rural areas where there is neither a wired internet connection nor suitable mobile network coverage (5G, 4G/LTE, 3G).
It is already known that the range of communication networks can be increased by meshing the end devices and thus the range limitation of a single communication connection can be lifted. In these so-called meshed multi-hop communication networks, the end devices talk to each other and pass the data among themselves without any special hierarchy until an end device can finally pass the data to a gateway.
Although the implementation of such a meshed multi-hop communication network in the end devices solves the problem of range limitation from the gateway to the end device by forwarding the data packets from one end device to another end device, it is not compatible with the LoRaWAN specification because special end devices with an additional meshed function are used here. Since standard LoRaWAN end devices can only contact a gateway directly and are not able to communicate directly with other end devices, standard LoRaWAN end devices cannot operate with this range extension. Range extension by implementing a meshed multi-hop communication network in the end devices is therefore not compatible with the LoRaWAN network standard.
An example of this is the development platform for LoRa end devices from the company PyCom (LoPy4 and FiPy), with which a multi-hop communication network can be implemented in the LoRa end devices, analogous to ZigBee or Z-Wave. Although this development platform can solve the problem of range limitation from the end device to the gateway by forwarding the data packets from one end device to another, it is not compatible with the LoRaWAN specification because it allows the mesh function to work only between end devices based on LoPy4 or FiPy. Existing LoRaWAN end devices cannot benefit from this range extension as they can only contact a gateway directly and are not able to communicate with the gateway indirectly across other end devices.
One approach for implementing a mesh network architecture in the field of WiFi is the 802.11s standard, which defines a deterministic access procedure for WLAN networks that uses time segments instead of competing access to the shared medium. For routing between nodes, 802.11s does not use an IP routing protocol, but the MAC layer, in order to take into account the specific and changing characteristics of the communication link. A hybrid wireless mesh protocol developed specifically for mesh is usually used here. The 802.11s standard provides for the installation of dozens of access points that are connected to each other. Forwarding via several access points, also known as multi-hop, is the rule. In extreme cases, only one of these needs to be connected to a LAN or WAN. Each node can perform one, two or three different network functions: Mesh points pass data to the next node, mesh access points exchange data with end devices and mesh point portals form the gateways to the wired network world. For the end devices, the mesh network appears like a simple WLAN. Since the 802.11s standard is defined for WLAN network architectures, it is not possible to apply this standard directly to LoRaWAN networks, which in turn are based on the LoRa communication standard.
An advantageous solution to increase the range limitation of LoRaWAN networks without having to accept incompatibility with existing LoRaWAN end devices is the implementation of a mesh functionality in the gateways. If LoRaWAN networks are extended with mesh gateways, a larger range or area coverage can be realised in areas without access to the Internet with a LoRaWAN network. This only requires individual gateways that are connected to the network server via an IP protocol. Since the communication protocol between gateways and end devices can remain unchanged, this solution approach maintains compatibility with existing LoRaWAN end devices and does not require any adaptation of the end devices to the mesh functionality. However, an unlimited network size is not possible here either, because according to the LoRaWAN protocol, class A end devices only have two receive windows and therefore the time span in which they expect a response is limited. If this time is exceeded, a timeout error occurs and communication with at least this one end device breaks down. The maximum size of such a LoRaWAN mesh gateway network is thus limited to a few hops due to the runtime extension of the responses.
The objective of the invention therefore is to provide a solution for range limitation from the network server to the end device, with which existing LoRaWAN-compatible end devices also benefit from range extension without having to implement additional functions in the end devices or being limited to class C end devices when using the end devices.
To solve this objective, the present invention proposes that a LoRaWAN mesh gateway network comprises at least one network server, a plurality of gateways and a plurality of end devices. According to the invention, at least one gateway comprises an ACK generation unit. The ACK generation unit is adapted to generate an ACK signal (from English “acknowledgement”). The ACK signal is used during a data transmission to confirm the receipt of a data packet. The ACK signal ensures that a message from the end device to a gateway is correctly sent to the gateway. The end device does not require to have a permanently active download receive window and therefore be permanently active, as in the case of a class C end device, but can also be a class A or B end device according to the LoRaWAN specification, for example. The power consumption and the service life of the end device are thus increased.
In another embodiment of the invention, the ACK signal generation unit comprises a processor and a memory. The processor and memory are standard components and therefore inexpensive to manufacture.
In an advantageous embodiment of the invention, the LoRaWAN mesh gateway network has different gateway types. The gateway types differ in terms of their communication ports for communication with other gateways, a network server or end devices and the resulting type of communication.
In another embodiment of the invention, the LoRaWAN mesh gateway network has a border gateway and a front-end gateway. The division of the gateways into front-end gateways and border gateways significantly extends the range of the LoRaWAN network, while still allowing the use of LoRaWAN-compatible end devices that can be distributed and networked far into impassable areas that cannot be reached with conventional communication networks.
In an advantageous embodiment of the invention, the front-end gateway comprises the ACK signal generation unit. The front-end gateway communicates with other gateways as well as with one or more end devices. By means of sending an ACK signal from the front-end gateway to an end device, it is ensured that a message from the end device to a gateway is correctly sent to the gateway. The end device does not have to have a permanently active download receive window and therefore be permanently active, as in the case of a class C end device, but can also be, for example, a class A or B end device according to the LoRaWAN specification. The power consumption and the operating time of the end device are thus increased.
In another embodiment of the invention, the front-end gateway has a first front-end gateway communication port for communication with a end device and a second front-end gateway communication port for communication with another front-end gateway and/or a border gateway. The front-end gateways and the border gateways are connected to each other by means of the first communication port via a meshed multi-hop network, so that the front-end gateway does not need a direct connection while communicating with the end devices. End devices are directly connected to a front-end gateway by means of a single-hop communication network via the second communication port.
An ACK generation unit in the sense of the present invention is a sub-server unit integrated into a gateway that performs functionalities and objectives intended for the network server according to the LoRaWAN protocol. ACK signals in the sense of the present invention are messages, commands and functions stored on the gateway or generated by a gateway.
They may include the following MAC commands of the LoRaWAN protocol (LoRaWAN 1.1 Specification of Oct. 11, 2017 (Final Release):
In a further embodiment of the invention, each front-end gateway is suitable for wireless point-to-point communication with a plurality of end devices using single-hop LoRa or FSK using the LoRaWAN protocol. This allows the network according to the invention and its components (gateways, end devices) to be distributed and linked far into impassable areas that cannot be reached with conventional communication networks.
In another embodiment of the invention, the front-end gateway and the boundary gateway are combined with a plurality of mesh gateway devices and at least one of the mesh gateway devices does not have a direct IP connection. The front-end gateways and the border gateways are interconnected via a multi-hop meshed network so that the front-end gateway does not require a direct connection. The invention enables range extension of LoRaWAN networks by interconnecting a multi-hop network using front-end gateways, thus maintaining full compatibility to the LoRaWAN specification.
In another embodiment of the invention, a border gateway is provided for communicating with the network server at a standard IP connection and using the LoRaWAN protocol. The network communicates with the network server at a standard IP connection using the LoRaWAN protocol. This increases the range of the network when compatible with the LoRaWAN protocol.
In another embodiment of the invention, the border gateway has a first border gateway communication port for communication with a network server and a second border gateway communication port for communication with a front-end gateway. The two border gateway communication ports differ in terms of their communication ports for communication with other gateways, a network server and the resulting type of communication.
In another embodiment of the invention, the front-end gateways are each integrated with a border gateway in a mesh gateway. Front-end gateways and the border gateways are combined in one device. Hereby, the integrated front-end gateways communicate with each other by means of a multi-hop communication network, while at least one integrated border gateway is connected to the network server NS via the standard Internet protocol.
In another embodiment of the invention, the LoRaWAN mesh gateway network is a multi-hop wireless network. Gateways are interconnected via a meshed multi-hop network so that the gateway does not need a direct connection while communicating with the end devices. This simultaneously extends the range of the LoRaWAN network because the gateways are connected to each other via the meshed multi-hop network and can thus forward the data from the end devices to the internet network server. Herby, the range limitation provided by the LoRaWAN standard of a direct connection between the end device and the gateway is removed.
The objective is further solved by means of the method for communication in a LoRaWAN mesh gateway network. Advantageous embodiments of the invention are shown in the dependent claims.
The method for communicating in a LoRaWAN mesh gateway network has five procedural steps: In the first step, a message is generated in an end device. The message is generated as a data packet by means of a processor located in the end device. In the second step, the message is sent from the end device to a gateway. Sending to a gateway is preferably wireless, but wired sending is also possible. In the third procedural step, the message is received on a gateway. In the fourth process step, an ACK signal is generated in the gateway. The ACK signal (from English “acknowledgement”) is a signal used in a data transmission to confirm receipt. In the fifth procedural step, the ACK signal is sent from the gateway to the end device.
By means of the method according to the invention, it is ensured that the message from the end device to a gateway is correctly sent to the gateway. The end device does not require to have a permanently active download receive window and therefore be permanently active, as in the case of a class C end device, but can also be, for example, a class A or B end device according to the LoRaWAN specification. The power consumption and the service life of the end device are thus increased.
In another embodiment of the invention, the message is sent from the end device to the gateway via a single-hop connection. The connection from the end device to the gateway is therefore a direct connection with only one hop of the data packet (the message).
In another embodiment of the invention, the ACK signal is sent from the gateway to the end device via a single-hop connection. The gateway to end device connection is also a direct connection with only one hop of the ACK signal. In this case, the network server can be reached by the end device via a multi-hop connection.
In another embodiment of the invention, the first gateway forwards the message to a second gateway and/or the network server. This achieves a range extension of LoRaWAN networks by interconnecting the multi-hop network using gateways, thus maintaining full compatibility to the LoRaWAN specification. At least one gateway communicates with the network server via a standard IP connection and using the LoRaWAN protocol.
In a further embodiment of the invention, the ACK signal is generated and/or sent by a front-end gateway. The front-end gateways are connected to each other and to other gateways via a meshed multi-hop network, so that the front-end gateway does not need a direct connection to communicate with the end devices. This simultaneously extends the range of the LoRaWAN network because the front-end gateway is connected to the border gateway via the meshed multi-hop network and can thus forward the data from the end devices to the Internet network server.
In another embodiment of the invention, the network communicates with the network server via a standard IP connection using the LoRaWAN protocol. This provides full compatibility. The invention enables range extension of LoRaWAN networks by interposing a multi-hop network using front-end gateways, thus maintaining full compatibility to the LoRaWAN specification. For this purpose, at least one gateway is provided to communicate with the network server via a standard IP connection and using the LoRaWAN protocol.
In a further embodiment of the invention, at least one front-end gateway communicates with at least one border gateway via a wireless point-to-point link. The front-end gateways and the border gateways are connected to each other via a meshed multi-hop network, so that the front-end gateway does not need a direct connection while communicating with the end devices. This simultaneously extends the range of the LoRaWAN network because the front-end gateway is connected to the border gateway via the meshed multi-hop network and can thus forward the data from the end devices to the internet network server.
In a further embodiment of the invention, at least one of the front-end gateways communicates with at least one of the border gateways via a wired network connection. The wired connection is in particular insensitive to interference radiation and therefore a reliable way of connection.
In a further embodiment of the invention, at least one of the front-end gateways communicates with at least one of the border gateways via a WLAN network. The front-end gateways and the boundary gateways are interconnected via a meshed multi-hop wireless network. The WLAN network uses time slices instead of competing access.
In a further embodiment of the invention, at least one of the front-end gateways communicates with at least one of the border gateways via an LTE network. Due to the use of an LTE network, compatibility with a standardised mobile network is realised.
The messages, commands and functions stored on the gateway or generated by a gateway may include the following MAC commands of the LoRaWAN protocol (LoRaWAN 1.1 Specification of 11 Oct. 2017 (Final Release)):
The invention is explained in more detail below by way of example with reference to the drawings. These show in
a Schematic structure of an end device
b Schematic structure of a front-end gateway
c Schematic structure of a border gateway
d Schematic structure of a mesh gateway
While in a conventional standard LoRa network end devices EDn are directly connected to the gateways Gn by means of a single-hop communication network, according to the invention the gateways Gn are divided into several front-end gateways FGDn and border gateways BGDn. The front-end gateways FGDn now communicate with each other via a multi-hop communication network MHD, while at least one of the front-end gateways FGDn also communicates with a border gateway BGDn. This then sends the data directly to the network server NS by means of an Internet protocol IP. Alternatively and in a particularly advantageous embodiment, the front-end gateways FGDn and the border gateways BGDn are combined in one device, namely in so-called “mesh gateways” MGD. Hereby, the integrated front-end gateways FGDn communicate with each other by means of a multi-hop communication network MHD, while at least one integrated border gateway BGDn is connected to the network server NS via the standard Internet protocol IP.
A front-end gateway FGD (
A border gateway BGD (
A mesh gateway MGD is a combination of front-end gateway FGD and border gateways BGD in one device. Therefore, the mesh gateway MGD has one communication port each to an end device ED for exchanging data and sending the ACK signal, to a gateway FGD, MGD and to the network server NS. The communication ports of the mesh gateway MGD use different communication channels so that the sender can be assigned via the communication channel used.
As can be seen from the examples, this type of communication and division of the gateways Gn into front-end gateways FGDn and border gateways BGDn considerably expands the LoRaWAN network, whereby LoRaWAN-compatible end devices EDn can still be used, which can be distributed and networked far into impassable areas that cannot be reached with conventional communication networks.
The front-end gateways FGDn and the border gateways BGDn are connected to each other via a meshed multi-hop communication network MHD. This means that the front-end gateway FGDn does not need a direct internet connection 8 while it communicates with the standard end devices EDn. The range of the LoRaWAN mesh gateway network 1 is significantly extended because the front-end gateway FGDn is connected to the border gateways BGDn via the meshed multi-hop communication network MHF and can forward the data of the end devices EDn to the internet network server NS. This removes the range limitation of the direct connection between end devices EDn and gateways Gn envisaged by the LoRaWAN standard.
At the same time, the invention provides full compatibility with commercially available LoRa end devices EDn because the front-end gateway FGDn and the standard LoRaWAN communication protocol adhere to the standard LoRa connection. On the other hand, the border gateway BGDn also uses the standard Internet protocol IP for communication with the LoRaWAN network server NS, so that complete compatibility is also established on this side. The invention therefore enables range extension of LoRaWAN networks by interposing a multi-hop communication network MHF by means of front-end gateways FGDn, thereby maintaining full compatibility with the LoRaWAN specification. This type of LoRaWAN mesh gateway network 1 is particularly suitable in remote, rural areas where there is neither a wired internet connection nor suitable mobile network coverage (5G, 4G/LTE, 3G) and thus the star-shaped network topology envisaged by the LoRa network, in which the gateway Gn requires a direct internet connection IP, is not possible.
Of course, the invention is not limited to the embodiments shown. Further embodiments are possible without abandoning the basic idea.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2020 103 418.0 | Feb 2020 | DE | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2021/053347 | 2/11/2021 | WO |
