Handover

About: Handover is a research topic. Over the lifetime, 24219 publications have been published within this topic receiving 296416 citations. The topic is also known as: handoff.

Millimeter-Wave Evolution for 5G Cellular Networks

Abstract: SUMMARY Triggered by the explosion of mobile traffic, 5G (5th Generation) cellular network requires evolution to increase the system rate 1000 times higher than the current systems in 10 years. Motivated by this common problem, there are several studies to integrate mm-wave access into current cellular networks as multi-band heterogeneous networks to exploit the ultra-wideband aspect of the mm-wave band. The authors of this paper have proposed comprehensive architecture of cellular networks with mmwave access, where mm-wave small cell basestations and a conventional macro basestation are connected to Centralized-RAN (C-RAN) to effectively operate the system by enabling power efficient seamless handover as well as centralized resource control including dynamic cell structuring to match the limited coverage of mm-wave access with high traffic user locations via user-plane/control-plane splitting. In this paper, to prove the effectiveness of the proposed 5G cellular networks with mm-wave access, system level simulation is conducted by introducing an expected future traffic model, a measurement based mm-wave propagation model, and a centralized cell association algorithm by exploiting the C-RAN architecture. The numerical results show the effectiveness of the proposed network to realize 1000 times higher system rate than the current network in 10 years which is not achieved by the small cells using commonly considered 3.5 GHz band. Furthermore, the paper also gives latest status of mm-wave devices and regulations to show the feasibility of using mm-wave in the 5G systems.

Communications system and a method therefor

Abstract: A handoff method is shown in the figure providing for the mobile station to transfer its communications between two time domain systems including the steps of initiating time adjusted operation by a mobile station on a flexible time domain system and informing the flexible time domain system of at least one particular activity requirement of the mobile station.

Effect of vertical handovers on performance of TCP-friendly rate control

Abstract: An intersystem or vertical handover is a key enabling mechanism for next generations of mobile communication systems. A vertical handover can cause an abrupt change of up to two orders of magnitude in link bandwidth and latency. It is hard for end-to-end congestion control to adapt promptly to such changes. This is especially a concern for slowly responsive congestion control algorithms, such as TCP-Friendly Rate Control (TFRC). TFRC is designed to provide a smooth transmission rate for real-time applications and, therefore, is less responsive to changes in network conditions than TCP. Using measurements and simulation, we show that TFRC has significant difficulties adapting after a vertical handover. TFRC receives only a fraction of TCP throughput over a fast link, but can be grossly unfair to concurrent TCP flows after handover to a slow link. We show that two proposals based on overbuffering and an explicit handover notification are effective solutions to these problems. Using them, TFRC can quickly adapt to new link characteristics after a handover, while otherwise maintaining a smooth transmission rate.

An Enhanced Handover Scheme for Mobile Relays in LTE-A High-Speed Rail Networks

Abstract: Recently, the mobile relay technique has been discussed to support communication services for Long-Term Evolution Advanced (LTE-A) high-speed rail networks. In the network, there are several mobile relays in a train. User equipment (UE) devices connect to in-car mobile relays instead of outside evolved NodeBs (eNBs). Mobile relays establish backhaul links with the serving donor eNBs (DeNBs) and coordinate control and data flows for UE devices. Since the train travels in high speed, mobile relays suffer from frequent handovers between DeNBs. We observe that the defined handover procedures in LTE-A specifications may incur message overhead and lengthen handover time. In this paper, we propose an enhanced handover scheme, which contains two procedures. The first procedure is an enhanced measurement procedure, which can accelerate the measurement procedure when the mobile relay knows that the train is moving toward some neighbor DeNBs. The second procedure is a group in-network handover procedure, which can aggregate similar in network handover procedures in the core network. Performance evaluations indicate that our design can conserve both time and messages when handover.

Handover management architectures in integrated WLAN/cellular networks

Abstract: The integration of existing cellular systems with new wireless access technologies, such as wireless LANs, has attracted considerable attention during the past few years. The challenges to be addressed include authentication, security, QoS support, and mobility management. Efficient mobility management, and especially handover management, is considered one of the major factors toward a seamless provision of multimedia applications across networks of different technologies. A large number of solutions have been proposed in an attempt to tackle all relevant technical issues concerning handover management. In order to evaluate these solutions, a more systematic categorization is needed. This survey gives an overview of the most recent handover management architectures for integrated WLAN/Cellular networks, focusing mainly on 802.11-based WLANs and GPRS/UMTS cellular networks. The various proposals are categorized based on the point of system integration, their main characteristics are presented, and their advantages and shortcomings are discussed in an overall evaluation section.