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en:iot-open:networking2:wireless [2023/11/18 16:21] – pczekalski | en:iot-open:networking2:wireless [2023/11/23 16:11] (current) – pczekalski | ||
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- | ====== Media Layers - Wireless Network Protocols ======= | ||
+ | ====== Media Layers - Wireless Network Protocols ======= | ||
+ | {{: | ||
Wireless connections define core communication for IoT devices. A vast and growing amount of protocols, their variations and the dynamic IoT networking market all present a non-solid situation where old " | Wireless connections define core communication for IoT devices. A vast and growing amount of protocols, their variations and the dynamic IoT networking market all present a non-solid situation where old " | ||
<figure iot-protocols> | <figure iot-protocols> | ||
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Moreover, WiFi itself offers only 1-to-1 (figure {{ref> | Moreover, WiFi itself offers only 1-to-1 (figure {{ref> | ||
<figure wifionetoone> | <figure wifionetoone> | ||
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<figure wifistar> | <figure wifistar> | ||
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- | WiFi has become a more and more popular choice for not-so-constrained IoT devices because they need to implement a full TCP/IP stack, and those devices that are also not so constrained with power resources. A list of WiFi standards and related transmission speeds is present in Table {{ref> | + | WiFi has become a more and more popular choice for not-so-constrained IoT devices because they need to implement a full TCP/IP stack, and those devices that are also not so constrained with power resources. A list of WiFi standards and related transmission speeds is present in table {{ref> |
<table Ref.Tab.1.1> | <table Ref.Tab.1.1> | ||
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Bluetooth offers various " | Bluetooth offers various " | ||
- | Now Bluetooth covers two branches: BR/EDR (Basic Rate/ | + | Now Bluetooth covers two branches: BR/EDR (Basic Rate/ |
- | Classical (before BLE and 4.0) Bluetooth networks can create ad-hoc, so-called WPAN (Wireless Personal Area Networks), sometimes referenced as Piconets. Bluetooth Piconet can handle up to 7 + 1 devices, where 1 device acts as Master and can contact up to 7 Slave devices. Only the Master device can initiate a communication. Fortunately for the IoT approach, much Bluetooth hardware can act as Slave and Master simultaneously, | + | Classical (before BLE and 4.0) Bluetooth networks can create ad-hoc, so-called WPAN (Wireless Personal Area Networks), sometimes referenced as Piconets. Bluetooth Piconet can handle up to 7 + 1 devices, where 1 device acts as Master and can contact up to 7 Slave devices. Only the Master device can initiate a communication. Fortunately for the IoT approach, much Bluetooth hardware can act as Slave and Master simultaneously, |
<figure net_bt_scatternet> | <figure net_bt_scatternet> | ||
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Bluetooth Low Energy (BLE) uses a simplified state machine implementation and thus is more constrained-devices friendly. It offers a limited range and is designed to expose the state rather than transmit streamed data. However, it provides a speed reaching up to about 1.4 Mbps (2 Mbps aerial throughput) if needed. It uses a 2.4 GHz band but is designed to avoid interference with WiFi AP and clients. Communication is organised into three advertising channels (located " | Bluetooth Low Energy (BLE) uses a simplified state machine implementation and thus is more constrained-devices friendly. It offers a limited range and is designed to expose the state rather than transmit streamed data. However, it provides a speed reaching up to about 1.4 Mbps (2 Mbps aerial throughput) if needed. It uses a 2.4 GHz band but is designed to avoid interference with WiFi AP and clients. Communication is organised into three advertising channels (located " | ||
- | Latest Bluetooth implementations (protocol version 5.0 and newer, implemented in mid-2017) offer a Bluetooth mesh network extending ubiquitous connectivity via a many-to-many communication model dedicated to IoT devices, lighting, Industry 4.0, etc. The Bluetooth mesh is layer-organised, | + | Latest Bluetooth implementations (protocol version 5.0 and newer, implemented in mid-2017) offer a Bluetooth mesh network extending ubiquitous connectivity via a many-to-many communication model dedicated to IoT devices, lighting, Industry 4.0, etc. The Bluetooth mesh is layer-organised, |
<figure bt-5-mesh> | <figure bt-5-mesh> | ||
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<figure gsm_generations> | <figure gsm_generations> | ||
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<figure gsm-net> | <figure gsm-net> | ||
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- | GSM protocols are proprietary, | + | GSM protocols are proprietary, |
On the one hand, the GSM network seems to be a good solution for extended distant IoT networks. They have many disadvantages, | On the one hand, the GSM network seems to be a good solution for extended distant IoT networks. They have many disadvantages, | ||
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Z-Wave is a protocol similar in principle to the ZigBee, but hardware is cheaper; thus, it is more towards inexpensive home automation systems. Like in ZigBee, Z-Wave operates on different frequencies depending on the world region, usually between 865 MHz and 926 MHz. The transmission speed is up to 200 kbps, and the range is 100m. A single Z-Wave network is pretty limited in the number of concurrent devices in one network, that is, only 232 devices. Each Z-Wave network has a unique ID, and each node (device) in a network has a unique 8-bit identifier. | Z-Wave is a protocol similar in principle to the ZigBee, but hardware is cheaper; thus, it is more towards inexpensive home automation systems. Like in ZigBee, Z-Wave operates on different frequencies depending on the world region, usually between 865 MHz and 926 MHz. The transmission speed is up to 200 kbps, and the range is 100m. A single Z-Wave network is pretty limited in the number of concurrent devices in one network, that is, only 232 devices. Each Z-Wave network has a unique ID, and each node (device) in a network has a unique 8-bit identifier. | ||
- | === Thread | + | == Thread == |
- | Another standard ((Thread Stack Fundamentals, | + | Another standard ((https:// |
== NFC == | == NFC == | ||
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Sigfox ((https:// | Sigfox ((https:// | ||
- | == LoRaWAN == | + | == LoRa and LoRaWAN == |
- | LoRa (Long Range) is the technology for data transmission with a relatively low speed (20 bps do 41 kbps) and a range of about 2 km (new transceivers can transmit data up to 15 km). It uses CSS (Chirp Spread Spectrum) modulation in the 433 MHz or 868 ISM radio band. The cell topology is the star, with the gateway at the central point. End devices use one-hop communication with the gateway. A LoRaWAN gateway is usually connected to the standard IP network with a central network server. The LoRa technology is supported as LoRaWAN by LoRa Alliance ((https:// | + | LoRa (Long Range) is the technology for data transmission with a relatively low speed (20 bps do 41 kbps) and a range of about 2 km (new transceivers can transmit data up to 15 km). It uses CSS (Chirp Spread Spectrum) modulation in the 433 MHz or 868 ISM radio band. |
+ | |||
+ | A chirp signal is characterized by a continuous frequency sweep over time. This means that the frequency of the transmitted signal starts at some lower frequency and continuously increases throughout the transmission of a single symbol. In LoRa the starting frequency differs depending on the symbol encoded, and while the modulated signal achieves the maximal value of the frequency starts from the minimal one. It means that each chirp uses the whole available bandwidth. Chirp Spread Spectrum modulation makes LoRa signals less susceptible to interference and noise and allows LoRa to achieve long-range communication. LoRa modulation is characterized by two parameters: | ||
+ | * **Spreading Factor** determines the speed of the signal frequency change over time. Higher spreading factors result in a longer communication range but lower data rates. It also defines the number of bits encoded by one chirp. | ||
+ | * The **Bandwidth** of the LoRa signal determines the amount of spectrum occupied by the transmitted signal. It can be 125, 250 or 500 kHz. It also specifies the sampling frequency of the signal in the receiver. | ||
+ | Having these parameters it is possible to calculate the efficient data rate (in bps). | ||
+ | Because the range of LoRa communication is long, transmitters can interfere, so some rules for the maximum time of occupation of the channel were introduced. In the European Union, the maximum percentage of transmission time known as the Duty Cycle is 1%. This gives a maximum transmission time of 864 seconds per day. Transmission should be as short as possible, and the delay between following transmissions should last a few minutes. The duty cycle together with bandwidth and spreading factor makes it possible to calculate the maximum payload of the frame and the bitrate. Some online calculators help set LoRa parameters to fulfil the local regulations ((https:// | ||
+ | |||
+ | The cell topology is the star, with the gateway at the central point. End devices use one-hop communication with the gateway. A LoRaWAN gateway is usually connected to the standard IP network with a central network server. The LoRa technology is supported as LoRaWAN by LoRa Alliance ((https:// | ||
There are 3 classes of devices in LoRa: | There are 3 classes of devices in LoRa: | ||
* Class A: where downlink is active only after the device uses uplink in a particular time window (twice). It has the greatest energy efficiency among other classes. Downlink opportunity appears asynchronously, | * Class A: where downlink is active only after the device uses uplink in a particular time window (twice). It has the greatest energy efficiency among other classes. Downlink opportunity appears asynchronously, | ||
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<figure Sample_6LoWPAN> | <figure Sample_6LoWPAN> | ||
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- | 6LoWPAN devices can be just nodes (Hosts) or nodes with routing capability (Routers) as presented in Figure | + | 6LoWPAN devices can be just nodes (Hosts) or nodes with routing capability (Routers) as presented in figure |
The Edge Router implements a gateway between 6LoWPAN and the regular IPv6 (IPv4) network. It aims to translate " | The Edge Router implements a gateway between 6LoWPAN and the regular IPv6 (IPv4) network. It aims to translate " | ||