  The increased usage of IEEE 802.11 Wireless LAN (WLAN) in residential
environments by unexperienced users leads to dense, unplanned and chaotic
residential WLAN deployments. Often WLAN Access Points (APs) are deployed
unprofitable in terms of radio coverage and interference conditions. In many
cases the usage of the neighbor's AP would be beneficial as it would provide
better radio coverage in some parts of the residential user's apartment.
Moreover, the network performance can be dramatically improved by balancing the
network load over spatially co-located APs.
  We address this problem by presenting Neighborhood extensible WLAN (NxWLAN)
which enables the secure extension of user's home WLANs through usage of
neighboring APs in residential environments with zero configuration efforts and
without revealing WPA2 encryption keys to untrusted neighbor APs. NxWLAN makes
use of virtualization techniques utilizing neighboring AP by deploying
on-demand a Wireless Termination Point (WTP) on the neighboring AP and by
tunneling encrypted 802.11 traffic to the Virtual Access Point (VAP) residing
on the home AP. This allows the client devices to always authenticate against
the home AP using the WPA2-PSK passphrase already stored in the device without
any additional registration process.
  We implemented NxWLAN prototypically using off-the-shelf hardware and open
source software. As the OpenFlow is not suited for forwarding native 802.11
frames, we built software switch using P4 language. The performance evaluation
in a small 802.11 indoor testbed showed the feasibility of our approach. NxWLAN
is provided to the community as open source.
