Comparison and Upgrade Guide for Semtech SX1276 SX1262 LR1121 LR2021

The latest fourth generation LoRa chip LR2021 released by Semtech brings FLRC high speed mode and multi band support. For users who are currently using SX127x or SX126x, the main focus at present is whether it is worth upgrading and what the cost of migration is.

Before reading this article, do you also have the following confusion?

• Is it necessary to upgrade from Gen 1 or Gen 2 or Gen 3 to Gen 4 (LR2021)? Where are the points of improvement?

• How much has the upper limit of the rate actually increased (LoRa or FLRC or FSK)? Can it support image transmission, audio, or larger packets?

• Will the coverage distance and penetration capability, also known as Link Budget, shrink at higher rates?

• Regarding power consumption, are there changes in RX, sleep, or transmission current?

• How exactly should Sub-GHz plus 2.4 GHz plus S-band (satellite) be used? Do I have to use satellite?

• Can the new chip still connect to old LoRaWAN base stations? Can it communicate with older models of LoRa devices?

• Are protocols like Sidewalk or Wi-SUN FSK supported natively by the chip, or do I need to develop the protocol stack myself?

• How do the front end, antenna, crystal oscillator (is TCXO saveable), PCB area, and BOM cost change?

• Is it better to mount the chip myself, or is it safer to buy a LoRa2021 module like the one from G-NiceRF directly?

• What is the cost of migration? Can old code be reused? Are the changes to software drivers and registers significant?

Abstract and Implementation Suggestions

Before we go deep into technical details, we need to clarify the core value of LR2021 Gen 4 first. The biggest selling point of this chip lies in the introduction of the FLRC modulation with a higher rate, which can reach up to 2.6 Mbps. At the same time, it improves the rate of traditional LoRa to 125 kbps. In addition, it emphasizes compatibility with multiple PHY and multiple protocols, and possesses multi band capabilities for Sub-GHz, 2.4 GHz, and S-band.

If you need to implement a project quickly, you can refer directly to the parameters of the LoRa2021 module from G-NiceRF. This module supports a voltage of 1.8 V to 3.6 V, and the sleep current is not higher than 2 µA. In terms of reception power consumption, the RX current is less than 6 mA under the Sub-GHz band, while it is less than 7 mA under the 2.4 GHz band. Regarding transmission power consumption, the current is less than 110 mA under the 433 MHz band. Its FLRC mode supports a maximum of 2.6 Mbps. Under the Sub-GHz band, the sensitivity can reach -143 dBm (under conditions of BW 62.5 kHz and SF12).

Comparison of Same Scope

When comparing chips of different generations, we often encounter the problem of inconsistent parameter scopes. To avoid the error of "comparing apples to oranges", we must set strict conditions when comparing sensitivity, rate, and power consumption.

Regarding sensitivity, we cannot look only at the limit values on the first page of the data sheet. We must pay attention to the specific Spreading Factor (SF) and Bandwidth (BW). For example, -148 dBm is often a theoretical value at extremely low rates. However, in engineering, we should pay more attention to the performance when SF12 is combined with a bandwidth of 125 kHz or 62.5 kHz.

Regarding rate, we must distinguish between the LoRa rate and the FLRC or FSK rate. "Maximum 300 kbps" or "2.6 Mbps" claimed by many chips usually refers to FSK or FLRC modes, rather than LoRa modulation.

Regarding power consumption, we need to compare sleep current (Sleep), reception current (RX), and transmission current (TX) under specific power levels separately. Only by comparing under the same working mode can we evaluate the impact on the life of the battery objectively.

Semtech LoRa IP Generation Evolution Route

To make it convenient for everyone to compare, we divide LoRa IP into four generations according to the official scope of Semtech.

Gen 1 First Generation

Represented by SX1272, SX1276, SX1278, and SX1279. This is the most classic LoRa chip and was widely used in early IoT projects.

Gen 2 Second Generation

Represented by SX1261, SX1262, SX1268, and LLCC68. It mainly improved performance in low power consumption and has currently become the main force for replacement in the market. In addition, there is the 2.4 GHz SX1280 or SX1281 series that supports FLRC.

Gen 3 Third Generation

Represented by LR1110, LR1120, and LR1121. The characteristics of this generation are enhanced multi band and satellite communication capabilities. Also, satellite link capabilities were added in some models, making them suitable for complex scenarios of global deployment.

Gen 4 Fourth Generation

This is the latest LR2021. Officially called LoRa Plus, it focuses on introducing high rate FLRC and stronger multi protocol support on the basis of inheriting the LoRa IP of previous generations.

Core Parameter Comparison

The table below summarizes the key indicators of the four generations of chips to help everyone consult them quickly.

Generation Detail and Engineering Pain Point Analysis

Gen 1 SX1276

As the first generation product, SX1276 solved the basic problem of long distance communication and became the de facto industry standard. The sensitivity of it is -148 dBm, and it integrates a power amplifier of +20 dBm. The maximum link budget can reach 168 dB. Although the programmable rate of it can reach 300 kbps, this mainly refers to the FSK mode.

With the development of technology, Gen 1 began to seem weak in power control and integration. Many new projects no longer choose it as the first choice. However, when maintaining old systems, it still has value in existence. It is necessary to note that one should not mistake the limit sensitivity of it for the achievable indicator in engineering when SF12 is combined with a bandwidth of 125 kHz.

Gen 2 SX1262

For applications that only need Sub-GHz LoRa, Gen 2 provides a better choice. The reception current of SX1262 decreased to 4.6 mA, the transmission power increased to +22 dBm, and the maximum link budget reached 170 dB. Under the same conditions, the power consumption performance of it is far better than Gen 1.

When implementing engineering, migrating from Gen 1 to Gen 2 requires attention to changes in software and hardware. The SPI driver method has changed somewhat, and the RF front end circuit also needs adjustment. If the application is sensitive to the life of the battery and does not require extremely high rates, SX1262 is currently still a choice with extremely high cost performance.

Gen 3 LR1121

Gen 3 represents the expansion of Semtech into the fields of multi band and satellite communication. LR1121 covers the Sub-GHz band from 150 MHz to 960 MHz, and at the same time supports 2.4 GHz as well as S-band and L-band satellite frequency bands.

For ordinary users, whether Gen 3 is needed depends on whether you truly need satellite connection or global frequency band coverage. If the product only needs to run on ground networks in specific regions, the system complexity of Gen 3 might bring unnecessary costs.

Gen 4 LR2021

LR2021 is called "LoRa Plus". The core of it lies in solving the pain point of the low transmission rate of LoRa. Official data from Semtech shows that LR2021 supports Sub-GHz, 2.4 GHz ISM, and licensed S-band frequency bands, and is backward compatible to ensure the ecosystem of LoRaWAN.

The most striking feature is the FLRC mode, where the rate can reach up to 2.6 Mbps. The LoRa mode has also increased to 125 kbps. Compared to SX1262, the sensitivity in the Sub-GHz band increased by 4.5 dB, and the tolerance for frequency deviation increased. This means it can not only transmit further but also transmit faster.

LR1121 vs LR2021

Compared with the module of the previous generation LR1121, it has undergone several important upgrades on the basis of the third generation chip LR1121. For example, it introduced the Fast Long Range Communication (FLRC) modulation technology. This allows the maximum transmission rate of it to reach 2.6 Mbps. Moreover, the upper limit of the rate of LoRa modulation also increased to 125 kbps. In contrast, chips like LR1121 of the previous generation focused more on traditional LoRa and (G)FSK modulation and could not provide this kind of high rate physical layer capability.

In terms of reception performance, the sensitivity of LR2021 in the sub-GHz band reached -141.5 dBm (@LoRa 125 kHz). This indicator is better than the -141 dBm of LR1121. Furthermore, this high performance is achieved under a simpler Direct-Tie architecture. In addition, LR2021 supports an offset of up to +/- 33% Bandwidth (BW), whereas previous generations of chips like LR1121 were usually limited to +/- 25% BW. At the same time, the phase noise performance of LR2021 is also very good. When meeting strict regional regulations such as ARIB in Japan, there is no need to lower the transmission power or add expensive filters as before.

In terms of power management and channel listening, LR2021 added the Fast Channel Activity Detection (Fast CAD) function. Through an adaptive threshold mechanism, it significantly shortened the detection time. It reduced the average detection duration from about 5 symbols to 1.5 symbols. Therefore, in application scenarios of "Listen Before Talk" (LBT), the power consumption can be reduced by approximately 70%. In addition, LR2021 also supports Multi Spreading Factor CAD (Multi-SF CAD), which can listen to up to 4 different spreading factors simultaneously. This greatly improved the efficiency of signal capture.

To improve the anti-interference ability in harsh RF environments, LR2021 added a brand new convolutional coding scheme (CR8 and CR9) and combined it with long interleaving technology. This enhanced the resistance of the device to Fast Fading and burst interference, ensuring the stability of long distance communication. Finally, the interior of the chip integrates a high efficiency SIMO (Single-Input Multiple-Output) DC-DC converter. The efficiency of it exceeds 85%. While maintaining high power transmission of +22 dBm, it provides better battery life.

Simply put, if we compare LR1121 to an explorer, then LR2021 is like giving this explorer faster running shoes (FLRC 2.6 Mbps), sharper ears (stronger frequency offset tolerance), and stronger endurance (Fast CAD), allowing him to run longer and more reliably in a more complex wilderness.

Decision on Implementation from Chip to Module

Choice of Module or Self Design

In actual product development, using a module directly is usually more cost effective than mounting chips by oneself. RF design involves complex impedance matching, harmonic filtering, and electromagnetic compatibility issues. Designing by oneself not only extends the development cycle but also faces risks of production consistency and ESD protection.

The LoRa2021 module from G-NiceRF has already provided typical application circuits, pin definitions, and mechanical dimensions, and provided demonstration code. It saves a large amount of low level debugging time for developers and ensures stability at the hardware level.

LoRa2021 Module Key Parameters Table

To facilitate selection, we have organized the core parameters of the LoRa2021 module.

Migration Service

G-NiceRF provides comprehensive technical support services for users upgrading from the old generation to LR2021. The stability of LoRa technology has been verified in many large scale projects. For example, in the large scale complex scenario application of "Run for Time" on Hunan TV in 2015. In the CCTV Spring Festival Gala of 2016 and 2018, it provided support for robot communication. It undertook on site communication guarantees at the 2019 Wuhan World Military Games and the 2021 CPC Centenary Celebration. By 2024, this technology had already achieved batch deployment in the full duplex audio modules of the State Grid.

In addition to module supply, G-NiceRF also provides supporting products including intelligent antennas. The service covers full stack value added solutions such as ODM or OEM customization, multi level MESH networking protocols, and OTA aerial upgrades.

Scenario Selection

To help everyone make the final decision, we summarized several typical scenarios.

If you need low speed small packets and extremely long battery life, and only work in the Sub-GHz band, Gen 2 SX1262 is still an excellent choice. The reception current of it is extremely low, the ecosystem is mature, and the cost is also relatively low.

If you need higher throughput, for example transmitting low resolution pictures, audio fragments, or need larger data packets, then LR2021 is the best choice. The FLRC mode of it provides bandwidth that traditional LoRa cannot reach.

If you need satellite communication or global deployment, then you should focus on considering LR1121 or LR2021. The multi band capabilities of them can simplify SKU management and adapt to frequency band regulations of different countries.

FAQs

Will Link Budget drop when LR2021 uses FLRC high speed mode (2.6 Mbps)?

Yes, the high speed mode usually uses higher effective bandwidth or higher symbol rates for the sake of rate. The equivalent noise is larger, and the error correction gain is smaller. Therefore, the reception sensitivity will be significantly worse, and the link budget will decrease accordingly.

The sensitivity of LoRa (Sub-GHz) can reach -141.5 dBm (SF12/125 kHz).

The sensitivity of FLRC (Sub-GHz) at a higher rate point is -101.5 dBm (1.95 Mbps).

Using "Link Budget = Tx Power - Rx Sensitivity" for a rough calculation:

LoRa: 22 - (-141.5) ≈ 163.5 dB

FLRC: 22 - (-101.5) ≈ 123.5 dB

It differs by about 40 dB.

The LR2021 chip increased frequency offset tolerance. Is it true that TCXO is not needed?

In a room temperature environment, and when using standard or wider bandwidth, ordinary crystal oscillators can usually be used.

However, if the device needs to work under extreme temperatures, uses narrow band communication, requires high precision applications, or is used as a master device or gateway, then using TCXO is still recommended or mandatory.

Are Sidewalk, Wi-SUN, and Thread of LR2021 "built-in" to the chip?

No. LR2021 only provides the bottom layer transceiver capabilities (PHY or modulation) needed by these protocols and does not contain the complete protocol stack.

It can be compatible with Amazon Sidewalk, Wi-SUN, Z-Wave etc., but needs to be used together with the protocol stack of a third party or the master control MCU. So, LR2021 is more like a radio frequency transceiver that supports multiple modulations, rather than a SoC that comes with complete network protocols.

Can old code be reused when migrating from SX1262 to LR2021?

Application Layer or Business Logic Layer: Most can continue to be used, such as sensor collection, data encoding, power consumption strategies, task scheduling etc. They will not need to be rewritten because of the chip upgrade.

RF Driver Layer or Register Interface: Usually cannot be reused directly. The driver needs to be transformed or replaced. The command format of LR2021 is different from SX1262. If your existing project is written directly based on the command set or driver of SX1262 (or deeply bound to a certain SX126x driver), you must at least do a rewrite of the "driver adaptation layer" when migrating to LR2021.

LoRaWAN Protocol Stack: It depends on which stack you use. Even if the logic of LoRaWAN can be reused, you must also be prepared for the work of replacing or transplanting the radio driver adaptation layer.

Can LR2021 connect to old LoRaWAN gateways?

In most cases it can, because it is compatible with the standard LoRa or LoRaWAN air interface.

However, two points must be noted:

1. The modulation mode must be correct. If using a non LoRaWAN mode like FLRC 2.6 Mbps, the old gateway cannot receive it.

2. The frequency band must be correct. Old gateways generally only support Sub-GHz (such as EU868, US915, AS923) and do not support 2.4 GHz. As long as the transmission parameters of the terminal conform to the LoRaWAN specifications of the corresponding region, it can connect normally.

Appendix

Data Sources

The key data cited in this article all come from the official Data Sheet of Semtech and the Specification of the G-NiceRF LoRa2021 Module. It is recommended to download the latest version of the documents for verification before design.

1. G-NiceRF LoRa2021 Multi-Band Wireless Module V1.2

2. LR2021 Datasheet v1.1

3. LR1121 Datasheet

4. SX1261/SX1262 Datasheet

5. SX1276-7-8-9 Datasheet

Recommended Reading

How to Choose the Most Suitable LoRa Module for IoT Projects – A helpful resource for understanding broader selection criteria beyond chip specifications.

Explanation of Key Nouns

FLRC (Fast Long Range Communication)：

This is the most core feature of LR2021. FLRC is not traditional LoRa spread spectrum modulation, but a high speed physical layer scheme that combines GMSK modulation, Forward Error Correction (FEC), and interleaving technology. It allows the wireless transmission rate to jump directly from the Kbps level to 2.6 Mbps.

Link Budget：

This is the engineering core indicator that determines "how far the device can transmit". The calculation formula is: Link Budget = Transmission Power - Reception Sensitivity.

Fast CAD (Fast Channel Activity Detection)：

This is the core mechanism for LR2021 to achieve extreme low power consumption listening. CAD is used to detect whether there is a signal in the channel without fully entering the reception mode. The Fast CAD of LR2021 shortens the average detection duration from about 5 symbols to 1.5 symbols through an adaptive threshold.

Direct-Tie (Direct Connection Architecture)：

This is the key to the simplification of hardware design and the optimization of BOM cost. It is a matching circuit design without an external radio frequency switch. It allows the Power Amplifier (PA) and the Low Noise Amplifier (LNA) to connect directly to the antenna through a passive matching network, without needing expensive external switching chips.

Convolutional Coding (CR8/CR9)：

This is the reliability guarantee for complex and harsh environments. It is a Forward Error Correction (FEC) scheme newly added to LR2021. CR8 is a 2/3 code rate, and CR9 is a 1/2 code rate. It provides overlap protection by distributing data information across multiple adjacent symbols.