The traditional IEEE 802.11
PAP does not permit to track the movement of the associated MTs that disrupted the continuity of established connection, which therefore degrades the service provision. Thus, we construct a logical access point (
LAP) to abstract the connection, MT associated with AP, as virtual AP (VAP). The abstraction of physical AP (
PAP) provides a platform to facilitate the programmable control plane and the mobility management functions. The
LAP is a logical entity that resides in the
PAP with an extended SDN/NFV abstraction, which releases the IEEE 802.11 protocol stack complexity to forward the operations to the centralized controller. Furthermore,
LAP acts as the SDN agent [
18] that is responsible for performing the multiple tasks either generated by the SDN controller or the local network. More specifically, the first task is to assign a unique BSSID per client that generates beacon and acknowledgment. Secondly, it sets the initial configuration parameters such as IP address, MAC address, and SSID for the MT and holds the related module information into the OpenFlow tables. Each
PAP can host multiple
LAPs with different BSSID to give abstraction of a general handover procedure to its associated users. Simultaneously,
LAP also maintains the same VAP for each associated MT with adjacent
PAPs, to enable the seamless handover which can be achieved while MT associated with several
PAPs is in the signal overlapping range. The migration of
LAP among adjacent
PAPs can be performed without a re-association process and also skipped the additional MAC layer procedures that provide an illusion of the consistent connection at the user side. Third, it detects the load of
PAP using the OpenWRT mwan3 package [
9] which includes the outbound traffic load information that we further elaborated in Eq.
1.
$$ {N}_{\mathrm{L}}\mathrm{A}\mathrm{P}={\displaystyle \sum_{n=1}^N{\mathrm{CS}}_{\mathrm{A}}^n}/{\displaystyle \sum_{m=1}^M{\mathrm{CS}}_{\mathrm{P}}^m} $$
(1)
where CS
A denotes the current active state of
LAP that contains the current traffic load (bytes) information of MT within a specified time period. Meanwhile, CS
P denotes the current passive state of
LAP for the connection interval time and sleeping time. If the current state CS is bigger than a threshold, the
LAP reflects an active state (CS
A), and if the CS is smaller, the
LAP reflects a passive state (CS
P). At the same time,
N is the number of
LAP in CS
A, and
M is the number of
LAP in CS
P.