no wlan after install of 16.04 (dell xps15)

[robert rottermann]

Hi there,
I installed ubuntu 16.04 on my dell xps 15.
Unfortunately wlan does not work any more.

no wlan is offered in the system settings, and
and no wlan device is in the /etc/network/interfaces.

root at lappi:/home/robert# cat /etc/network/interfaces
# interfaces(5) file used by ifup(8) and ifdown(8)
auto lo
iface lo inet loopback

this is what lspci displays:

root at lappi:/home/robert# lspci -vnn -d 14e4:
06:00.0 Network controller [0280]: Broadcom Corporation BCM4352 802.11ac 
Wireless Network Adapter [14e4:43b1] (rev 03)
     Subsystem: Dell BCM4352 802.11ac Wireless Network Adapter [1028:0019]
     Flags: bus master, fast devsel, latency 0, IRQ 18
     Memory at f7a00000 (64-bit, non-prefetchable) [size=32K]
     Memory at f7800000 (64-bit, non-prefetchable) [size=2M]
     Capabilities: [48] Power Management version 3
     Capabilities: [58] MSI: Enable- Count=1/1 Maskable- 64bit+
     Capabilities: [68] Vendor Specific Information: Len=44 <?>
     Capabilities: [ac] Express Endpoint, MSI 00
     Capabilities: [100] Advanced Error Reporting
     Capabilities: [13c] Device Serial Number c4-8e-00-ff-ff-00-00-01
     Capabilities: [150] Power Budgeting <?>
     Capabilities: [160] Virtual Channel
     Capabilities: [1b0] Latency Tolerance Reporting
     Capabilities: [220] #15
     Kernel driver in use: bcma-pci-bridge
     Kernel modules: bcma

any ideas what I could do?
thanks
robert