Funny! Ubuntu14 cannot identify the problem of wireless networks!

Funny! Ubuntu14 cannot identify the problem of wireless networks!
The laptop is installed with ubuntu14 and cannot identify the wireless network. With the ifconfig command, wlan0 cannot be found in the output result. Then, Baidu searches for the keyword "ubuntu14 cannot identify the wireless network, A lot of articles have been published for a query, refresh, and click here to see the solutions for the same version. I carefully read the solution steps, which are roughly like this:

First, determine the wireless network adapter type: lspci-vnn-d 14e4:

My NIC:

. 0 Network controller [0280]: Broadcom CorporationBCM4313802.11bgn Wireless Network Adapter [14e4: 4727] (rev 01) Subsystem: Broadcom Corporation Device [14e4: 0510] Flags: bus master, fast devsel, latency 0, IRQ 17 Memory at 99100000 (64-bit, non-prefetchable) [size = 16 K] Capabilities: <access denied> Kernel driver in use: bcma-pci-bridge

First install the b43-fwcutter tool, as follows: Download b43-fwcutter source code: Installation (a). make (B) sudo make install driver download driver file: http://www.lwfinger.com/b43-firmware/broadcom-wl-5.100.138.tar.bz2 < This driver should be useful to bcm43xx and other network adapters.> Use the b43-fwcutter tool to install the driver to load the driver modprobe b43 for other types of wireless network cards, refer to: http://wireless.kernel.org/en/users/Drivers/b43#devicefirmware