understanding key transmission settings for lora® p2p and mesh

Learn how to configure the parameters for LoRa® P2P and Mesh communication. This guide covers settings including frequency, TX power, bandwidth, and spreading factor.

LoRa communications allow end devices to operate within a mesh network or establish direct communication between two devices using LoRa P2P (Point-to-Point). In both scenarios, key parameters must be configured on any LoRa device. This article offers a brief introduction to these parameters.

Essential LoRa P2P & Mesh Communication Settings

Although LoRa has been on the market for years, it remains relatively unknown, and its parameters are not easily understood. To better grasp the concept, consider a familiar device: the walkie-talkie. 

Walkie-talkies are commonly used by security personnel and staff at public events and provide a useful analogy for LoRa communication.

For walkie-talkies to communicate effectively, users need to agree on:

• Being on the same channel

• The volume of their speech

• The speed of their talking

• The clarity of their enunciation

• The number of times they say "hello" before delivering their message

• Whether they are listening or speaking at any given moment

   

LoRa vs. Walkie-Talkies: Understanding Transmission Parameters

The following table highlights the similarities between LoRa parameters and walkie-talkie features to enhance understanding of how LoRa communication functions.

Think of these parameters as the knobs on a walkie-talkie, which are used to adjust the channel, transmission power, and other settings, allowing LoRa devices to communicate reliably with one another.

Key LoRa Parameters Explained

Now, let’s take a closer look at what the LoRa parameters actually are.

LoRa Tx Power

• What it is: Transmit power, measured in decibels relative to 1 milliwatt (dBm).

• Why it matters: Higher transmit power typically results in a longer communication range but also increases power consumption and may be subject to regional regulations.

• Possible values: Generally ranges from 2 dBm to 22 dBm for sub-GHz modules.

• How to choose: Use a lower value if battery life is a priority or if local regulations impose limits. Select a higher value for maximum range, provided it complies with legal regulations.

• Analogy: It’s like shouting versus whispering. Shouting allows you to be heard from farther away but requires more energy and may not be allowed everywhere.

LoRa Bandwidth

• What it is: The bandwidth setting for LoRa communication. A setting of “0” typically corresponds to 125 kHz, while other values may represent narrow bandwidths, such as 62.5 kHz or 41.7 kHz.

• Why it matters: Narrower bandwidths (indicated by higher numerical values in some configurations) provide better range but lower data rates, meaning it transmits less data per second.

• Possible values:

  • 125 kHz (default and most common)

  • 250 kHz

  • 500 kHz

  • 62.5 kHz

  • 41.7 kHz

  • 31.25 kHz

  • 20.8 kHz

  • 15.6 kHz

  • 10.4 kHz

  • 7.8 kHz (very narrow, enables long range but results in very slow transmission)

• How to choose: Use 125 kHz for typical use, short distances, or higher data rates. Choose narrower bandwidths like 62.5 kHz for longer range or low-power applications where speed is less critical.

• Analogy: Think of it like the width of a water pipe: a wider pipe moves more water faster but may not push it as far if the pressure is low.

LoRa Spreading Factor

• What it is: The Spreading Factor (SF) is a key parameter that influences range, transmission speed, and energy consumption. A higher SF means better signal sensitivity, resulting in a long range but slower data rates.

• Why it matters: SF7 provides a good balance between speed and range. If you require more distance, consider increasing the SF to SF8, SF9, etc. But keep in mind that this will reduce transmission speed.

• Possible values: SF6 to SF12

• How to choose: Use a higher spreading factor (SF) for long-distance or low-signal environments where slower data rates are acceptable. Use a lower SF when you need faster data over shorter distances.

• Analogy: It’s similar to speaking slowly and clearly versus speaking quickly and mumbling. Clear, slow speech travels farther and is easier to understand, but it takes longer to convey your message.

Coding Rate (Error Correction in LoRa P2P)

• What it is: LoRa employs forward error correction to enhance reliability. The coding rate determines the level of redundancy added to each message. A typical value of “1” corresponds to a coding rate of 4/5, which means one additional bit of error correction for every four bits of data. Higher values indicate increased error correction, expressed in LoRa terms, which is expressed as 4/x.

• Why it matters: Higher coding rates provide better protection in noisy or long-range conditions but reduce data throughput.

• Possible values:

  • 4/5

  • 4/6

  • 4/7

  • 4/8

• How to choose: Use a higher coding rate when communication is susceptible to interference or when reliability is crucial. In cleaner environments or for faster data requirements, select a lower coding rate.

• Analogy: It’s like repeating yourself several times to ensure you're understood effectively, but it takes longer to convey the message.

LoRa Frequency

• What it is: The radio channel the device uses to send and receive data, measured in Hz.

• Why it matters: All LoRa devices must agree on the same frequency to communicate effectively.

• Possible values:

  • EU: 868,000,000 to 868,600,000 Hz (868 MHz band)

  • US: 902,000,000 to 928,000,000 Hz (915 MHz band)

• How to choose: LoRa operates over the ISM band, which varies by region. Refer to the official LoRa regional parameters to determine the correct frequency for your location.

• Analogy: It’s like tuning an FM radio to a specific station, such as 100.3 MHz—if you’re not on the exact frequency, you won’t receive the signal.

Preamble Length (Synchronization in LoRa Transmissions)

• What it is: The preamble is a sequence of symbols sent before the actual data to help the receiver synchronize with the incoming signal.

• Why it matters: A typical value is 8. Increasing the preamble can assist the receiver in detecting very weak signals, but it also adds a slight delay to transmission time.

• Possible values:

  • 6 to 65,535 (theoretically), though 8 is the standard in most cases.

• How to choose: If you are experiencing missed data due to synchronization issues or are operating over very long distances, consider increasing the value. Otherwise, 8 is a reliable default.

• Analogy: Like saying “Hello… hello… hello…” At the beginning of a conversation, it gives the listener time to tune in and be ready to receive the message.

Symbol Timeout (LoRa RX Mode Configuration)

• What it is: This parameter configures the device to remain in Receive mode, waiting for incoming data packets.

• Why it matters: Without this setting, the device may automatically switch between transmit and receive modes. By enabling this parameter, the device is always ready to listen, similar to a walkie-talkie locked on the “listen” channel.

• Possible values:

  • RX_MODE_NONE: Not in receive mode

  • RX_MODE_RX or RX_MODE_CONTINUOUS: Constantly listening

  • RX_MODE_SINGLE: Listens for a single packet, then stops

  • TX_MODE_TX: Transmit mode

• How to choose: Use RX_MODE_CONTINUOUS if the device needs to be always ready to receive. For devices that primarily transmit or only need to listen occasionally, adjust the mode as necessary.

• Analogy: Like a walkie-talkie that remains locked in listening mode, always prepared for someone else to speak.

How the Settings Work Together

To get your LoRa device operational, you need to configure the transmission channel (frequency) and the transmission power (Tx Power). These settings should align with your application requirements. You can also adjust the bandwidth and spreading factor to optimize the balance between range and power consumption.

To minimize the risk of lost data packets, set appropriate values for the preamble length and symbol timeout. Lastly, ensure your device is always prepared to receive by properly configuring the symbol timeout, which will enhance its reliability as a listener.

LoRa P2P Configurations (AT Commands & APIs)

Now that we've explained the configuration terms, let's apply them in practice.

Use RUI3 AT Commands for LoRa P2P

Command:

AT+P2P=909600000:7:0:0:8:22

The parameters here are

AT+P2P=<Frequency>:<Spreading Factor>:<Bandwidth>:<Code Rate>:<Preamble Length>:<TX Power>

The symbol timeout has to be set with a separate command:

AT+SYMBOLTIMEOUT=0

Receive mode is enabled with

AT+PRECV=xx

Where xx can be:

• 0 = RX off

• 1 to 65532 = RX time in milliseconds

• 65533 = Continuous RX mode with TX enabled

• 65534 = Continuous RX mode; to transmit data, RX must be stopped first using AT+PRECV=0

• 65535 = Continuous RX mode until a transmission is received, after which the transceiver enters standby mode.

Configure LoRa P2P with RUI3 API

api.lora.pfreq.set(909600000); // frequency for transmission
api.lora.ptp.set(22); // Max TX power
api.lora.pbw.set(0); // 0 = 125kHz, can try 3 (62.5kHz) or 4 (41.67kHz) for longer range
api.lora.psf.set(7); // Can try 8, 9, 10 for longer range
api.lora.pcr.set(0); // Can try 1, 2 or 3 for longer range
api.lora.ppl.set(8); // "standard"

Set Up LoRa P2P on WisBlock API

// Settings for LoRa P2P and LoRa Mesh`
g_lorawan_settings.p2p_frequency = 909600000 // frequency for transmission
g_lorawan_settings.p2p_tx_power = 22; // Max TX power
g_lorawan_settings.p2p_bandwidth = 0; // 0 = 125kHz, can try 3 (62.5kHz) or 4 (41.67kHz) for longer range
g_lorawan_settings.p2p_sf = 7; // Can try 8, 9, 10 for longer range
g_lorawan_settings.p2p_cr = 1; // Can try 2, 3 or 4 for longer range
g_lorawan_settings.p2p_preamble_len = 8; // "standard"
g_lorawan_settings.p2p_symbol_timeout = 0; // "standard"
// Force listening`
g_lora_p2p_rx_mode = RX_MODE_RX;

Updated July 28, 2025 05:47