A Cross-Layer Location-Based Approach for Mobile-Controlled Connectivity

Table 1

Classification of handover algorithms on the basis of decision metrics and performance results.

VHO Decision Metric	VHO algorithm	Main aspects	Performance
RSS	Ayyappan and Dananjayan [7]	This technique considers both hard and soft MCHO version between WLAN and CDMA networks. The RSS parameter is monitored against unwanted power level fluctuations.	Throughput
	Inzerilli and Vegni [8]	This approach is an MCHO technique between WLAN and CDMA networks. It focuses on the minimization of ping-pong effect by channel estimation techniques and waiting time parameter.	Throughput and handover frequency
	Xie and Wu [9]	The algorithm makes handoff decisions after analyzing the signal strength fluctuation caused by slow fading through FFT. The method strongly reduces the number of handovers. It can be applied to both horizontal and vertical handovers.	Handover frequency and delay
	SINR	Yang et al. [10]	This technique results in a QoS oriented VHO, since the SINR factor is strictly affecting the QoS level.	Throughput
		Vegni et al. [11]	It is an MCHO technique between WLAN and CDMA networks. The goal is to limit the ping-pong effect by preventive vertical handovers. Since the SINR factor is combined with RSS parameter, the technique results in combined-metric based VHO approach for preventing unnecessary VHOs.	Throughput and handover frequency
QoS		Vegni et al. [12]	In this technique the QoS parameters are both subjective and objective. This approach is an MCHO and network-assisted VHO technique between WLAN and UMTS networks, in an IEEE 802.21 network architecture.	Seamless connectivity
	Jesus et al. [13]	The handover technique is QoS-oriented and is based on context-aware information coming from both the network and the user. The handover decision is negotiated by both the MT and the network (i.e., UMTS and WLAN) in an IEEE 802.21* network architecture.	Maximum allowed number of active users
	Speed	Vegni and Esposito [14]	This technique is a vehicle-controlled VHO, based on speed and handover delay. It addresses on VANETs.	Throughput and handover frequency
Esposito et al. [15]		This approach results in a vehicle-controlled VHO for improving QoS metrics.	Throughput, jitter, delay and handover frequency
Chen et al. [23]		This is a novel network mobility management protocol for VANETs, by exploiting traditional vehicle-to-vehicle communications.	Handoff delay and packet loss rate
Location		Wang et al. [16]	This technique is limited on a horizontal handover approach, for both hard and soft versions. The MT’s location is exploited for adaptive handovers.	Dropped calls and outage probability
		Kibria et al. [24]	It is an MT controlled VHO technique, based on MT’s location information to predict handovers.	Hysteresis margins
	Inzerilli et al. [18]	This method is driven by MT’s location in order to prevent vertical handovers between WLAN and UMTS networks. The limitation of ping-pong effect is acted by the use of the waiting time parameter.	Throughput and number of vertical handovers

*The IEEE 802.21 standard provides quick handovers of data sessions across heterogeneous networks with small switching delays and minimized latency [27]. The handover procedures could become more flexible and appropriate with this standard, by exploiting the Media Independent Handover (MIH) functional model. The IEEE 802.21 focuses on protocol aspects rather than handover algorithms. In this table the IEEE 802.21 is not investigated since it is out of the scope of this paper.