https://www.quora.com/What-are-the-main-differences-between-Bluetooth-4-0-4-1-and-4-2-in-the-Layers-Baseband-LMP-L2CAP-app-Layer
http://sina.com.hk/news/article/20131223/0/5/0/-38766.html?cf=o.digital
BLE4.1相比BLE4.0的区别是：
1）与4G网络合并共处，减少干扰
2）可以同时做主和从，提供速度
3）ipv6
4）简化了设备的连接过程
V4.0 到V4.1 硬件不需要改变。
BLE4.1和BLE4.2的区别：
http://www.semiconductorstore.com/blog/2015/BLE-4-2-vs-BLE-4-1/1548
Key Bluetooth 4.2 Features Not Available with Bluetooth 4.1
IoT Capabilities:
Low-power IP (IPv6/6LoWPAN)
Bluetooth Smart Internet Gateways (GATT)
With BLE 4.2 Bluetooth Smart sensors can transmit data over the internet.
Security:
LE Privacy 1.2
LE Secure Connections
With new, more power efficient and highly secure features, BLE 4.2 provides additional benefits allowing only trusted owners to track device location and confidently pair devices.
Speed:
250% Faster
10x More Capacity