USB v.s. WiFi

When comparing local Wi-Fi to USB, it's important to consider both latency (the delay in data transmission) and bandwidth (the amount of data that can be transferred over a period of time). Here's a general comparison:

Latency

USB (Universal Serial Bus)

• Lower Latency: USB connections generally have significantly lower latency compared to Wi-Fi. This is because USB is a direct, wired connection. Data travels along a dedicated path, with minimal processing or waiting time.

• Typical Latency: For most USB versions (especially USB 3.0/3.1/3.2 and later), the latency introduced by the USB interface itself is often in the range of microseconds (µs) or very low single-digit milliseconds (ms). For high-speed applications like gaming peripherals (mice, keyboards), USB is crucial for responsiveness.

• Factors Affecting USB Latency:

  • USB Version: Newer versions (USB 3.x, USB4) have improved protocols and higher speeds, which can also contribute to slightly lower effective latency.

    
    

  • Device Quality: The quality of the USB controller, cables, and the connected device itself can influence latency.

    
    

  • Polling Frequency: For some devices (like mice), the polling rate (how often the device reports its status to the host) impacts perceived latency.

    
    

Local Wi-Fi

• Higher Latency: Wi-Fi inherently introduces more latency than wired connections. This is due to several factors:

  
  

  • Wireless Medium: Radio waves are less reliable than cables. Signals can be affected by interference, obstacles (walls, furniture), and distance, requiring retransmissions and error correction.

    
    

  • Half-Duplex Communication: Most Wi-Fi operates in half-duplex mode, meaning devices can either transmit or receive at any given time, but not both simultaneously. This "listen before transmit" mechanism adds overhead.

    
    

  • Shared Medium: All devices on a Wi-Fi network share the same airwaves. This leads to congestion, collisions, and the need for protocols to manage access, all of which add delay.

  • Processing Overhead: Wireless protocols involve more complex error checking, encryption, and routing compared to direct USB connections.

• Typical Latency: Local Wi-Fi latency can range from a few milliseconds (ms) in ideal conditions (close to the router, no interference, modern Wi-Fi 6/6E/7) to tens or even hundreds of milliseconds in congested or poor signal environments. For online gaming, fluctuations in Wi-Fi latency (jitter) are particularly problematic.

  
  

Bandwidth (Data Transfer Rate)

USB

• High and Consistent Bandwidth: USB offers very high theoretical bandwidth, which is typically quite consistent and less prone to external interference.

• Typical Bandwidth (Theoretical Maximums):

  • USB 2.0: 480 Mbps (Megabits per second)

    
    

  • USB 3.0 (SuperSpeed): 5 Gbps (Gigabits per second)

  • USB 3.1 Gen 2 (SuperSpeed+): 10 Gbps

    
    

  • USB 3.2 Gen 2x2: 20 Gbps

    
    

  • USB4: Up to 40 Gbps (and potentially higher with Thunderbolt 4 compatibility)

    
    

• Real-world performance will always be lower than theoretical maximums due to protocol overhead, device limitations (e.g., hard drive speed), and CPU processing. However, USB generally delivers a large percentage of its theoretical speed.

  
  

Local Wi-Fi

• Variable and Influenced Bandwidth: Wi-Fi bandwidth is highly variable and significantly affected by numerous factors.

• Typical Bandwidth (Theoretical Maximums - highly optimistic):

  • Wi-Fi 4 (802.11n): Up to 300-600 Mbps (single channel, depends on MIMO/antenna configuration)

  • Wi-Fi 5 (802.11ac): Up to 1.3 Gbps (for multi-antenna configurations, can reach several hundred Mbps in typical real-world use)

  • Wi-Fi 6 (802.11ax): Up to 9.6 Gbps (theoretical aggregate, real-world much lower, but better efficiency)

  • Wi-Fi 6E/7: Can reach even higher theoretical speeds (tens of Gbps) by utilizing wider channels and new frequency bands.

• Real-world performance for Wi-Fi is often a fraction of the theoretical maximums due to:

  • Distance and Obstacles: Signal strength degrades significantly with distance and obstructions.

    
    

  • Interference: Other Wi-Fi networks, Bluetooth devices, microwaves, and even cordless phones can interfere.

    
    

  • Client Device Capabilities: The quality of the Wi-Fi adapter in your device matters.

  • Network Congestion: More devices on the same Wi-Fi network reduce available bandwidth for each.