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.

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

Internet of Things is expanding the network by integrating huge amount of surrounding objects which requires the secure and reliable transmission of the high volume data generation, and the mobile relay technique is one of the efficient ways to meet the on-board data explosion in LTE-Advanced (LTE-A) networks. However, the practice of the mobile relay will pose potential threats to the information security during the handover process. Therefore, to address this challenge, in this paper, we propose a secure handover session key management scheme via mobile relay in LTE-A networks. Specifically, in the proposed scheme, to achieve forward and backward key separations, the session key shared between the on-board user equipment (UE) and the connected donor evolved node B (DeNB) is first generated by the on-board UE and then securely distributed to the DeNB. Furthermore, to reduce the communication overhead and the computational complexity, a novel proxy re-encryption technique is employed, where the session keys initially encrypted with the public key of the mobility management entity (MME) will be re-encrypted by a mobile relay node (MRN), so that other DeNBs can later decrypt the session keys with their own private keys while without the direct involvement of the MME. Detailed security analysis shows that the proposed scheme can successfully establish session keys between the on-board UEs and their connected DeNB, achieving backward and forward key separations, and resisting against the collusion between the MRN and the DeNB as the same time. In addition, performance evaluations via extensive simulations are carried out to demonstrate the efficiency and effectiveness of the proposed scheme.

Achieve Secure Handover Session Key Management via Mobile Relay in LTE-Advanced Networks

In Long Term Evolution-Advanced (LTE-A) networks, Mobile Relay Nodes (MRNs) are installed in fast moving buses and trains to connect the passengers' devices to evolved Node B (eNB) However, since the MRNs and eNBs are installed in open environment, they can be compromised to launch security and privacy attacks In this paper, we propose a privacy preserving intra Mobility Management Entity (MME) group handover scheme in LTE-A networks for repeated trips Comparing to the existing schemes, the proposed scheme is devised to achieve the following requirements First, the MRNs should be able to authenticate the received messages so that the messages sent from external attackers can be dropped by the MRNs rather than forwarding them to the core network Second, the proposed scheme also aims to reduce the computational and signaling overhead and establish secure session keys Third, the scheme aims to prevent MRNs and eNBs from tracking passengers' locations especially if they take same trip regularly Our analysis demonstrates that the proposed scheme can achieve our security and privacy objectives Our performance evaluations demonstrate that the proposed scheme requires a few number of messages and low computation overhead

Privacy-Preserving Intra-MME Group Handover via MRN in LTE-A Networks for Repeated Trips

A network node in a cellular telecommunications system hands over responsibility for serving a wireless communication equipment from a serving cell to a target cell, wherein the wireless communication equipment is situated in a first aircraft that is in-flight. An aircraft position, an aircraft velocity, and an aircraft direction are determined. For each candidate cell of a number of candidate cells, a level of beam distortion that would result from a beam directed from the candidate cell to the first aircraft is predicted. The target cell is selected from the candidate cells by identifying which of the candidate cells has a least amount of predicted beam distortion. The target cell is then signaled to prepare for a handover of responsibility for serving the wireless communication equipment.

Cell selection for airborne mobile cellular communications equipment

Mobile cellular radio systems have become complex multi-layered systems with a mixed architecture of macro and micro cells; therefore, a dynamic method of triggering the handover algorithm in such systems is invaluable and required. In this paper the authors develop a simple handover mechanism to adapt for a fast moving mobile station requesting a handover, in which the authors utilise a Doppler frequency estimation in the downlink for adjustment and apply it to a long-term evolution (LTE) network. This method is beneficial for high speed mobiles in macro and/or micro cells, in which for the latter the cell radius is small and needs a dynamic algorithm to respond in a timely manner. The main objective of this study is to investigate the performance of the proposed algorithm; hence, a system layout is specifically designed for this study. Other factors, such as interference, which may affect the performance of the suggested system are not addressed here. The main concern is to study and compare the proposed algorithm to the standard handover algorithm currently implemented in LTE. Simulations at the system level show a marked decrease in the average number of handovers requested.

Doppler frequency estimation-based handover algorithm for long-term evolution networks

A dynamic method to trigger the handover algorithm in LTE networks is proposed. The method utilizes Doppler frequency estimation in the downlink for adjustment. This method is beneficial for high speed mobiles in micro cells, where the cell radius is small and needs a dynamic algorithm to respond in a timely manner. Comparison to the practical handover triggering method, which is currently implemented in LTE is evaluated1. Simulations at the system level show a marked decrease in the average number of handovers.

https://www.researchgate.net/profile/Sami_Muhaidat/publication/261210184_Intra-frequency_handover_algorithm_design_in_LTE_networks_using_Doppler_frequency_estimation/links/54ace6c60cf2479c2ee85623.pdf

Omar Altradt

Papers

Intra-frequency handover algorithm design in LTE networks using Doppler frequency estimation