Overview: With the widespread adoption of 5G and IoT technologies, the volume of services carried by wireless networks is growing exponentially. Performance bottlenecks and interference issues have become core factors restricting user experience. This article begins with performance indicator analysis, identifies interference source characteristics, and combines channel optimization and power control techniques. Through enterprise case studies, it verifies the effectiveness of the solutions, providing a feasible path for wireless operation and maintenance in complex environments.

From home WiFi to industrial-grade WLAN, wireless networks have deeply penetrated production and daily life. According to IDC statistics, the number of connected IoT devices worldwide will exceed 75 billion by 2025. This massive influx of access leads to channel congestion and increased interference, with throughput in some scenarios reaching only 40% to 60% of the nominal value. Accurately identifying interference and developing scientific optimization strategies have become crucial to ensuring network stability.

I. Analysis of Core Performance Indicators of Wireless Networks

Signal Strength and Signal-to-Noise Ratio (SNR)

Signal Strength: Measured in dBm. Ideal coverage requires a range of -40dBm to -70dBm; packet loss rate increases significantly below -85dBm.
SNR: Reflects the ratio of useful signal to noise. ≥25dB is sufficient for high-definition video and other applications; below 15dB requires improvement through antenna adjustment or AP additions.

Throughput and Bandwidth Utilization

Throughput: Affected by channel width and modulation method. For example, 802.11ax (WiFi 6) theoretically has a single-stream rate of 1.2Gbps, but in practice, due to interference and terminal compatibility, the single-user rate often remains at 300Mbps~500Mbps.
Channel Bonding: 20MHz→40MHz can increase bandwidth, but adjacent channel interference must be avoided.

Latency and Jitter

Latency Requirements: Industrial control and remote medical applications require latency <10ms. Latency Components: Propagation delay (1μs/m), processing delay (AP/terminal forwarding time), queuing delay (channel congestion). Impact of jitter: Jitter exceeding 5ms can cause audio stuttering and video tearing.

II. Classification and Characteristics of Wireless Network Interference Sources

Co-channel Interference: "Signal Collision" Due to Channel Overlap

2.4GHz Band: With only 3 non-overlapping channels (1, 6, 11), the "hidden node" problem easily occurs when multiple APs share the same channel and their coverage overlaps.
5GHz Band: Although there are 24 non-overlapping channels (China region), high-density deployment (shopping malls, stadiums) still causes interference due to channel reuse.

Adjacent Channel Interference: "Edge Effect" of Spectrum Leakage

Spectrum Distribution: The wireless signal spectrum has a bell-shaped distribution. When the distance between adjacent APs is less than 10 meters, the edge of the strong signal intrudes into the weak signal channel. Example: The AP on channel 6 has excessive power, which will interfere with channels 5 and 7, increasing the demodulation error rate of weak signal terminals by more than 30%.

Non-Wireless Interference: "Invisible Obstacles" in the Electromagnetic Environment

Microwave Oven: Generates broadband noise when operating at 2.45GHz, covering the entire 2.4GHz channel, with an interference radius of up to 5 meters.

Metal Obstructions: Elevator shafts and steel structures cause signal attenuation of 80%~90%, creating blind spots. Other devices: Bluetooth and ZigBee devices still conflict with WiFi during high concurrency.

III. Core Technologies and Practices for Performance Optimization

Channel Dynamic Planning: From "Fixed" to "Intelligent"

Three-Step Method: Scan - Analyze - Allocate.

Tools: Ekahau and AirMagnet collect AP data to generate spectrum heatmaps.
Strategy: Prioritize channels with good interference index (channel occupancy <30%, SNR >20dB), and avoid overlapping channels in 2.4GHz.
Automation: Enable automatic switching for enterprise-level APs (e.g., Cisco DNA Center), scan every 15 minutes, and adjust if thresholds are exceeded.

Fine-Grade Power Control: Balancing Coverage and Interference

Indoor Power: Set 15dBm~20dBm for 2.4GHz and 18dBm~23dBm for 5GHz, avoiding power differences between adjacent APs exceeding 6dBm.
Outdoor Power: Power can be increased to 25dBm with directional antennas, requiring on-site surveying and coverage boundary delineation.
Multi-Story Buildings: Maintain consistent power within the same floor, reduce power by 3dBm~5dBm between floors above and below to reduce vertical interference.

Topology Reconfiguration: From "Single" to "Microcellular"

High-Density Scenarios: Conference rooms and classrooms utilize "microcellular" networking, deploying one 802.11ax OFDMA-enabled AP every 50-80 square meters, serving 30+ terminals. Load Balancing: When an AP connects to more than 30 terminals or CPU utilization exceeds 70%, new terminals are guided to connect to an idle AP. Coverage Gap Solution: Mesh nodes are used in elevator lobbies and basements, extending coverage via wired or 5GHz backhaul.

IV. Case Study: Interference Location and Elimination

Background

Scenario: A 1500㎡ office area of an internet company. Equipment: 12 802.11ac APs. Problem: Employees reported video stuttering and file transfer speeds <10Mbps. Initial inspection showed 85% occupancy on channel 6 (2.4GHz).

Location Process

Spectrum Analysis: Three strong interference signals were found on the 2.4GHz band, exhibiting periodic peaks every 2 minutes. On-site Investigation: Interference spiked when three microwave ovens were operating in the break room, causing the SNR of surrounding APs to drop from 28dB to 12dB. Data Capture: Wireshark showed a 25% retransmission rate for terminals near the break room (normal <5%).

Optimization Measures

Channel Adjustment: The 2.4GHz channel was switched to non-overlapping channels on 1, 4, and 5GHz. Power Control: The 2.4GHz power of APs near the break room was reduced from 20dBm to 15dBm. Environmental Management: Peak usage times for microwave ovens and meetings were staggered, and a shielding net was installed.

Results Verification: Indicator Improvements: After one week, 2.4GHz utilization was <40%, and 5GHz remained stable at 55%. Performance Improvements: Video stuttering was eliminated, and file transfer speeds reached 50Mbps~80Mbps. Satisfaction: Employee satisfaction increased from 35% to 92%.