NeXt generation/dynamic spectrum access/cognitive radio wireless networks: a survey
Computer Networks: The International Journal of Computer and Telecommunications Networking
Novel collision detection scheme and its applications for IEEE 802.11 wireless LANs
Computer Communications
Packet Delay Metrics for IEEE 802.11 Distributed Coordination Function
Mobile Networks and Applications
UCS'06 Proceedings of the Third international conference on Ubiquitous Computing Systems
Adaptive rank estimation for spherical subspace trackers
IEEE Transactions on Signal Processing
Two algorithms for fast approximate subspace tracking
IEEE Transactions on Signal Processing
Plane rotation-based EVD updating schemes for efficient subspacetracking
IEEE Transactions on Signal Processing
Fast, rank adaptive subspace tracking and applications
IEEE Transactions on Signal Processing
Efficient mobility management for vertical handoff between WWAN and WLAN
IEEE Communications Magazine
Performance analysis of the IEEE 802.11 distributed coordination function
IEEE Journal on Selected Areas in Communications
IEEE Journal on Selected Areas in Communications
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The existence of multiple wireless networks with different radio access technologies and protocols makes the radio environment heterogeneous. In order to provide the best Quality of Service available from the active networks, and satisfy the concept of always best connected, one can take advantage of this heterogeneity by developing multi-mode terminals able to smartly switch from one interface to another. This switching process, known as vertical handover (VHO), requires some relevant metrics to be measured by the terminal in order to decide whether to trigger a VHO or not. Using multiple antennas, we propose to track the number of active sources and employ the results in CSMA/CA networks for VHO. The proposed algorithm is developed using a Markov chain model for sources enumeration at any given time. We also use a three state Markov model for CSMA/CA networks and show how this algorithm can be applied to recursively obtain two informative metrics about the channel state, namely the channel occupancy rate and the collision rate. Numerical simulations confirm that the proposed algorithm performs well for practical SNR values. The proposed algorithm relies on a physical layer sensing and requires no connection to the access point, no synchronization, no signal demodulation and no frame decoding. This particularity ensures a seamless handover with a time/energy economy.