---
title: WiFi 与蓝牙
url: https://doc.liz6.com/hardware/07-wireless-communications/01-wifi-and-bluetooth
locale: zh
area: hardware
tags:
- hardware
- 无线通信
date: 2026-06-30
modified: 2026-07-11
description: WiFi 与蓝牙 WiFi (802.11) 世代演进 | 世代 | IEEE | 频段 | 最大速率 | 关键技术 | 年代 | |------|------|------|----------|----------|------| | WiFi 4 | 802.11n | 2.4/5 GHz | 600 Mbps …
---

# WiFi 与蓝牙

## WiFi (802.11)

### 世代演进

| 世代 | IEEE | 频段 | 最大速率 | 关键技术 | 年代 |
|------|------|------|----------|----------|------|
| WiFi 4 | 802.11n | 2.4/5 GHz | 600 Mbps | MIMO, 40MHz | 2009 |
| WiFi 5 | 802.11ac | 5 GHz | 6.9 Gbps | MU-MIMO, 160MHz, 256QAM | 2013 |
| WiFi 6 | 802.11ax | 2.4/5 GHz | 9.6 Gbps | OFDMA, 1024QAM, TWT | 2019 |
| WiFi 6E | 802.11ax | +6 GHz | 同6 | 多了 6GHz 干净频谱 | 2021 |
| WiFi 7 | 802.11be | 2.4/5/6 GHz | 46 Gbps | 320MHz, 4096QAM, MLO | 2024 |

### 关键概念

#### 频段
```
2.4 GHz: 拥挤 (微波炉/BT/Zigbee 都在这), 穿墙好
  信道 1~13 (中国), 仅 3 个不重叠信道 (1/6/11)

5 GHz: 干净、信道多、带宽大, 穿墙差
  信道多, 可捆绑 80/160 MHz

6 GHz (WiFi 6E/7): 全新频谱, 几乎没有干扰
  但穿墙更差, 目前仅室内用
```

#### OFDM / OFDMA
```
OFDM (WiFi 4/5): 每次传输占用整个信道
  → 小包也占满, 效率低

OFDMA (WiFi 6+): 把信道切分为 RU (资源单元)
  → 多个设备同时传输, 类似 LTE
  → 大幅降低延迟, 提高多设备效率

类比: OFDM = 单车道, OFDMA = 多车道
```

#### MIMO / MU-MIMO
```
MIMO: 多天线同时收发
  2×2: 2 发 2 收 (常见手机/笔记本)
  4×4: 4 发 4 收 (高端路由器)

MU-MIMO: 同时向多个客户端发送数据
  WiFi 5: 仅下行, WiFi 6: 上下行都支持
```

#### MLO (Multi-Link Operation) — WiFi 7
```
同时使用 2.4G + 5G + 6G 多频段传输
→ 更高吞吐 + 更低延迟 + 更好的可靠性
→ 一个频段被干扰可无缝切到另一个
```

---

## 蓝牙 (Bluetooth)

### Classic vs BLE

| 特性 | BR/EDR (Classic) | BLE (Low Energy) |
|------|-------------------|-------------------|
| 物理信道 | 79 个 1MHz | 40 个 2MHz |
| 速率 | 1~3 Mbps | 125kbps~2Mbps |
| 功耗 | ~1W (持续) | ~0.01~0.5W |
| 延迟 | ~100ms | ~3ms |
| 拓扑 | 微微网 (Piconet) | 星型/广播/Mesh |
| 音频 | A2DP/HFP | LE Audio (LC3) |
| 典型应用 | 音箱/耳机/车机 | 穿戴/IoT/信标 |

### BLE 版本
```
4.0: 基础 BLE
4.2: 安全增强, 包长扩展
5.0: 2M PHY, 长距离编码, 广播扩展
5.1: 寻向 (AoA/AoD → 厘米级定位)
5.2: LE Audio, 等时通道 (给 TWS 耳机)
5.3: 信道分类, 连接子事件
5.4: 周期性广播响应 (电子价签)

其实 BLE 4.2 就够大部分场景了
5.0+ 主要带来: 更快、更远、更省电
```

### BLE 连接流程

<svg viewBox="0 0 720 400" xmlns="http://www.w3.org/2000/svg" font-family="-apple-system,'Source Han Sans CN','Microsoft YaHei',sans-serif" role="img" aria-label="BLE 连接建立流程:外设广播,中心设备扫描请求与响应后发起连接请求,最终建立连接">
  <defs>
    <marker id="ble-arr" markerWidth="10" markerHeight="8" refX="8" refY="3" orient="auto"><path d="M0,0 L8,3 L0,6 Z" fill="#475569"/></marker>
  </defs>
  <rect width="720" height="400" fill="#ffffff"/>
  <text x="360" y="28" text-anchor="middle" font-size="17" font-weight="700" fill="#1f2933">BLE 连接建立流程:广播 → 扫描请求/响应 → 连接请求</text>

  <rect x="60" y="55" width="180" height="34" rx="6" fill="#eef2ff" stroke="#c7d2fe"/>
  <text x="150" y="77" text-anchor="middle" font-size="13" font-weight="700" fill="#3730a3">外设 (Peripheral)</text>
  <rect x="480" y="55" width="180" height="34" rx="6" fill="#f0fdfa" stroke="#99f6e4"/>
  <text x="570" y="77" text-anchor="middle" font-size="13" font-weight="700" fill="#0f766e">中心设备 (Central)</text>

  <line x1="150" y1="89" x2="150" y2="300" stroke="#cbd5e1" stroke-width="1.3" stroke-dasharray="4 3"/>
  <line x1="570" y1="89" x2="570" y2="300" stroke="#cbd5e1" stroke-width="1.3" stroke-dasharray="4 3"/>

  <text x="360" y="118" text-anchor="middle" font-size="12" font-weight="700" fill="#3730a3">① 广播 (Advertising)</text>
  <line x1="150" y1="125" x2="562" y2="125" stroke="#475569" stroke-width="1.6" marker-end="url(#ble-arr)"/>

  <text x="360" y="158" text-anchor="middle" font-size="12" font-weight="700" fill="#334155">② 扫描请求 (Scan Request)</text>
  <line x1="570" y1="165" x2="158" y2="165" stroke="#475569" stroke-width="1.6" marker-end="url(#ble-arr)"/>

  <text x="360" y="198" text-anchor="middle" font-size="12" font-weight="700" fill="#0f766e">③ 扫描响应 (Scan Response)</text>
  <line x1="150" y1="205" x2="562" y2="205" stroke="#475569" stroke-width="1.6" marker-end="url(#ble-arr)"/>

  <text x="360" y="238" text-anchor="middle" font-size="12" font-weight="700" fill="#334155">④ 连接请求 (Connection Request)</text>
  <line x1="570" y1="245" x2="158" y2="245" stroke="#475569" stroke-width="1.6" marker-end="url(#ble-arr)"/>

  <rect x="150" y="270" width="420" height="26" rx="6" fill="#dcfce7" stroke="#4ade80"/>
  <text x="360" y="287" text-anchor="middle" font-size="12" font-weight="700" fill="#166534">⑤ 建立连接</text>

  <rect x="60" y="318" width="600" height="60" rx="8" fill="#f0fdfa" stroke="#99f6e4"/>
  <text x="76" y="340" font-size="12.5" fill="#115e59">连接参数决定响应速度与功耗的取舍:连接间隔 (Connection Interval) 7.5ms~4s —— 短 = 低延迟/高功耗,长 = 高延迟/低功耗。</text>
  <text x="76" y="360" font-size="12.5" fill="#115e59">延迟 (Slave Latency) = 从机可跳过应答的次数;超时 (Supervision Timeout) = 多久无响应算断连。</text>
</svg>


### 经典蓝牙 vs BLE 选型
```
持续音频 → Classic (A2DP)
偶尔数据 + 低功耗 → BLE
需要 iOS 后台通信 → BLE (Apple 对 BLE 友好)
HID 键盘/鼠标 → BLE (HID over GATT)
文件传输 → Classic (或 WiFi Direct)
TWS 耳机 → BLE 5.2+ (LE Audio)
```

---

## WiFi 与蓝牙共存

### 同频干扰
```
2.4GHz 是 WiFi + BT + Zigbee + Thread + 微波炉 的战场

WiFi 和 BT 都在同一设备中:
  → 时分复用 (TDM): 交替使用天线
  → 共存接口: 蓝牙告诉 WiFi "我要发包了", WiFi 暂停

实现: 大多数 WiFi/BT 组合芯片内部有共存机制
     (MTK/Realtek/Broadcom/Qualcomm 各有实现)
驱动侧问题常导致共存失效 (如你的 MT7927)
```

### 组合芯片
```
消费电子中 WiFi 和 BT 几乎总是同一芯片
  MT7921/7925/7927 (MTK)
  AX200/AX210 (Intel)
  BCM 系列 (Broadcom)

走 PCIe/USB/SDIO 接 Host
蓝牙部分通常通过 USB 暴露 HCI 接口
```

---
*关键词: WiFi6, WiFi7, 802.11ax, OFDMA, MIMO, BLE, GATT, LE Audio, 共存*