Low wifi signal level

My notebook HP Pavilion p170nr has very poor wi-fi receiving. Even near wi-fi router it shows about half of indicator level. On Windows 8.1 everyting work fine.

sudo lspci -vvnn | grep -A 9 Network
08:00.0 Network controller [0280]: Broadcom Corporation BCM43142 802.11b/g/n [14e4:4365] (rev 01)
 Subsystem: Hewlett-Packard Company Device [103c:2230]
 Control: I/O- Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx-
 Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx-
 Latency: 0, Cache Line Size: 64 bytes
 Interrupt: pin A routed to IRQ 18
 Region 0: Memory at b5500000 (64-bit, non-prefetchable) [size=32K]
 Capabilities: [40] Power Management version 3
  Flags: PMEClk- DSI- D1+ D2+ AuxCurrent=0mA PME(D0+,D1-,D2-,D3hot+,D3cold+)
  Status: D0 NoSoftRst+ PME-Enable- DSel=0 DScale=2 PME-

lsb_release -rd
Description: Ubuntu 14.04.1 LTS
Release: 14.04

uname -a
Linux black-pavilion 3.13.0-43-generic #72-Ubuntu SMP Mon Dec 8 19:35:06 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux

sudo dmidecode -s bios-version
F.12

sudo dmidecode -s bios-release-date
08/18/2014

ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: bcmwl-kernel-source 6.30.223.141+bdcom-0ubuntu2
ProcVersionSignature: Ubuntu 3.13.0-43.72-generic 3.13.11.11
Uname: Linux 3.13.0-43-generic x86_64
NonfreeKernelModules: wl
ApportVersion: 2.14.1-0ubuntu3.6
Architecture: amd64
CurrentDesktop: Unity
Date: Tue Dec 23 09:53:18 2014
InstallationDate: Installed on 2014-11-23 (29 days ago)
InstallationMedia:

SourcePackage: bcmwl
UpgradeStatus: No upgrade log present (probably fresh install)