Bluetooth LE 1M vs 2M vs Coded PHY: Key Differences
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Based on the provided Bluetooth Core Specification, following is an explanation of the different Bluetooth Low Energy (BLE) Physical Layers (PHYs) viz. LE 1M, LE 2M and LE coded.
1. Bluetooth BLE PHYs: LE 1M vs. LE 2M vs. LE Coded
The Physical Layer (PHY) dictates how the radio transmits raw data (symbols) over the air. Bluetooth LE offers different PHY options to allow developers to balance data speed, range and power consumption.
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LE 1M PHY (The Standard): This is the mandatory, default physical layer for all Bluetooth LE devices. It transmits at a rate of 1 Megasymbol per second (1 Msym/s). Because it is “Uncoded” (meaning 1 symbol represents exactly 1 bit of data), it yields a raw data rate of 1 Megabit per second. It offers the standard BLE range and power consumption profile.
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LE 2M PHY (High Speed): This is an optional “Uncoded” PHY designed for higher throughput. It transmits at twice the speed of the standard PHY: 2 Megasymbols per second (2 Msym/s), yielding a raw data rate of 2 Mb/s. Because it transmits data twice as fast, the radio is turned on for half the time, which can actually save battery power when transferring larger amounts of data. However, transmitting at higher speeds slightly reduces the effective reliable range.
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LE Coded PHY (Long Range): This is an optional PHY designed to drastically increase the transmission range without increasing the transmitter’s power output. It achieves this by using Forward Error Correction (FEC) coding. It transmits at the standard 1 Msym/s, but it requires multiple symbols to represent a single bit of data to ensure the receiver can accurately decode weak signals over long distances.
- S=2 Coding: 2 symbols represent 1 bit, yielding a data rate of 500 kb/s.
- S=8 Coding: 8 symbols represent 1 bit, yielding a data rate of 125 kb/s.
- Trade-off: Because it takes up to 8 times as many symbols to send the same amount of data, the “radio on time” is significantly longer (up to 8 times longer than LE 1M), which consumes more battery and takes up more airtime.
Summary Comparison Table
| Feature | LE 1M PHY | LE 2M PHY | LE Coded PHY |
|---|---|---|---|
| Primary Purpose | Standard BLE communication. | High throughput / Faster data transfer. | Extended range (Long Range). |
| Mandatory / Optional | Mandatory | Optional | Optional |
| Symbol Rate | 1 Msym/s | 2 Msym/s | 1 Msym/s |
| Coding Scheme | Uncoded (1 symbol = 1 bit) | Uncoded (1 symbol = 1 bit) | Coded (S=2 or S=8) |
| Raw Data Rate | 1 Mb/s | 2 Mb/s | 500 kb/s (S=2) or 125 kb/s (S=8) |
| Radio-On Time | Standard | Half the time of LE 1M | Up to 8x longer than LE 1M |
| Range | Standard | Slightly less than LE 1M | Up to 4x the range of LE 1M |
References & Further Reading
- Bluetooth SIG : Bluetooth Core Specification Version 6.3, May 5, 2026.
- Bluetooth SIG : Bluetooth Technology Overview
Continue Learning Bluetooth Basic Concepts
- What are new features in Bluetooth 6.3 Version
- Bluetooth GATT Vs. ATT Vs. GAP : Key Comparison
- Bluetooth Service Vs. Characteristic Vs. Descriptor
- Bluetooth Central Vs. Peripheral : Key Differences
- Bluetooth pairing Vs. Bonding Phase
- Bluetooth Notifications Vs. Indications
- Bluetooth Channel Sounding Vs. RSSI
- Bluetooth Direction Finding Methods : AoA Vs. AoD
- Bluetooth Error Codes Guide : Meanings, Causes & Fixes
Continue Learning Bluetooth Technology
- Bluetooth Basics Tutorial
- Bluetooth Low Energy (BLE) Basics Tutorial
- Bluetooth Protocol Stack & Device State Diagram
- Bluetooth Physical Layer Modules
- Bluetooth MAC Layer Overview
- Bluetooth Channel Frequency List
- Bluetooth Network Security
- Bluetooth Low Energy (BLE) Connection Establishment Procedure
- Bluetooth Profiles: HFP, HSP, A2DP, AVRCP, PBAP & MAP
- Bluetooth Mesh Node Types & Protocol Stack Layer Functions