1. Introduction

ZigBee’s 2.4GHz ISM band operation makes it susceptible to Wi-Fi interference, multipath fading, and co-channel congestion. Proper RF testing and channel selection are critical for ensuring reliable mesh networking, especially in dense environments like smart homes and industrial IoT.

EBYTE’s ZigBee modules (e.g., E180-ZG120A, E18-2G4Z27SI, E180-Z8910SP) provide configurable RF parameters, including:
✔ 16 selectable channels (11–26)
✔ Programmable TX power (up to 20dBm)
✔ RSSI monitoring for signal strength analysis
✔ LBT (Listen Before Talk) for interference avoidance

This guide covers test methodologies, interference sources, and optimization techniques

2. ZigBee Channel Selection & Frequency Planning

2.1 Available ZigBee Channels (2.4GHz Band)

Key Insight:

• Channels 11, 15, 20, 25 are recommended by the ZigBee Alliance for minimal Wi-Fi interference.

• EBYTE modules default to Channel 11 but can be reconfigured via AT commands:

  AT+CHANNEL=25      // Switch to Channel 25 (2475 MHz)

3. RF Performance Testing Methodology

3.1 Key Metrics to Measure

3.2 Test Setup for EBYTE Modules

1. Hardware:

• EBYTE Module: E180-ZG120A (Coordinator) + E18-2G4Z27SI (End Device).

• Attenuator: To simulate distance (e.g., 3dB = ~2x range reduction).

• Interference Source: Wi-Fi router (Ch. 6), Bluetooth device.

2. Software:

• EBYTE Configuration Tool (channel/power adjustment).

• ZigBee sniffer (e.g., Texas Instruments Packet Sniffer).

3. Procedure:

• Measure RSSI at 1m, 10m, 50m with obstacles (walls, metal).

• Introduce controlled interference (Wi-Fi on Ch. 6) and observe PER.

4. Interference Sources & Mitigation Strategies

4.1 Common Interference Sources

4.2 EBYTE Module Anti-Interference Features

1. Channel Blacklisting

• Problem: Persistent interference on Ch. 20 (2450 MHz).

• Solution: Disable problematic channels:

  AT+BLACKLIST=20     // Ignore Channel 20 during scans

2. Adaptive Power Control

• Dynamic TX Power Adjustment:

  AT+TXPOWER=10       // Lower TX power to 10dBm (default: 20dBm)

  
  

• Reduce power in high-density networks to minimize co-channel interference.

3. LBT (Listen Before Talk)

• How It Works:

• Module checks channel RSSI before transmitting.

• If noise > threshold (e.g., -85dBm), delays transmission.

• Enable via:

  AT+LBT=ON           // Enable LBT (E180-ZG120A/B)

5. Case Study: Smart Factory Deployment

5.1 Challenge

• Environment: 50+ ZigBee nodes (E180-Z8910SP routers + E180-Z6907A sensors).

• Interference: Industrial Wi-Fi (Ch. 6), Bluetooth scanners.

• Symptoms: 15% PER, sporadic dropouts.

5.2 Solution

1. Channel Replanning:

• Switched from Ch. 20 → Ch. 25 (2475 MHz).

• Blacklisted Ch. 15 (2425 MHz, Wi-Fi-heavy).

2. Power Optimization:

• Reduced router TX power from 20dBm → 14dBm (lower cell overlap).

3. LBT Enablement:

• Cut collision-induced retries by 40%.

Results:
✔ PER dropped to 0.8%.
✔ Battery life improved by 22% (less retransmission)

6. Troubleshooting RF Issues

Pro Tip:
Use EBYTE’s EbyteRFTest tool to log RSSI trends over time.

7. Conclusion & Module Recommendations