LENOVO的Y430P笔记本，网卡显示如下：

$ lspci

07:00.0 Ethernet controller: Qualcomm Atheros QCA8171 Gigabit Ethernet (rev 10)
08:00.0 Network controller: Broadcom Corporation BCM43142 802.11b/g/n (rev 01)

其中，无线网卡BCM43142在ubuntu 14.04系统WIF上网不稳定，WIFI的信号强度在－80DB左右:

user@xubu:~$ sudo iwconfig
[sudo] password for user:
wlan0     IEEE 802.11abg  ESSID:"abc"  
          Mode:Managed  Frequency:2.452 GHz  Access Point: C8:4A:55:01:A2:73  
          Bit Rate=48 Mb/s   Tx-Power=13 dBm   
          Retry  long limit:7   RTS thr:off   Fragment thr:off
          Encryption key:off
          Power Management:off
          Link Quality=38/70  Signal level=-72 dBm  
          Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0
          Tx excessive retries:4  Invalid misc:214   Missed beacon:0

当WIFI还正常连网时，tcpdump -nei wlan0却显示ARP-Request得不到网关的回应数据:

17:07:20.014725 ARP, Request who-has 192.168.1.1 tell 192.168.1.11, length 46

但是同样的电脑， 从安装的WINDOWS 7系统连接同样的WIFI，信号强度一样，却一直正常访问。难道是在LINUX下的驱动有问题？