Long Term Evolution User Research Articles

The vulnerability and enhancement of AKA protocol for mobile authentication in LTE/5G networks

The Long-Term Evolution (LTE)/5G network connects much of the world’s population to provide subscriber’s voice calls and mobile data delivery, with security provided by the Authentication and Key Agreement (AKA) defined by 3GPP, which makes the LTE/5G network more secure than all its predecessors. Primarily due to the access limitations of LTE systems, the vulnerabilities of AKA protocol and potential attacks have not received much investigation, which is essential to LTE users with a tremendous amount of cellular services. In this study, we focus on two questions: (i) what are the vulnerabilities that can be exploited to carry out attacks in practice? and (ii) how to design an enhanced AKA protocol against such attacks? We examine the detailed procedures of Evolved Packet System (EPS)-AKA protocol by 3GPP, and have identified three types of attacks with respect to catching, location tracking, and jamming. We have designed and implemented attacks with commercial equipment to evaluate their threats in practice. In addition, we propose an enhanced AKA protocol that essentially relies on asymmetric encryption rather than symmetric in the AKA protocol and additional digital signatures to countermeasure these attacks. Finally, we verified our solution through formal verification to prove that our solution can mitigate the newly found vulnerabilities.

QoS-based Packet Scheduling Algorithms for Heterogeneous LTE-Advanced Networks: Concepts and a Literature Survey

The number of LTE (Long-Term Evolution) users and their applications has increased significantly in the last decade, which increased the demand on the mobile network. LTE-Advanced (LTE-A) comes with many features that can support this increasing demand. LTE-A supports Heterogeneous Networks (HetNets) deployment, in which it consists of a mix of macro-cells, remote radio heads, and low power nodes such as Pico-cells, and Femto-cells. Embedding this mix of base-stations in a macro-cellular network allows for achieving significant gains in coverage, throughput and system capacity compared to the use of macrocells only. These base-stations can operate on the same wireless channel as the macro-cellular network, which will provide higher spatial reuse via cell splitting. Also, it allows network operators to support higher data traffic by offloading it to smaller cells, such as Femto-cells. Hence, it enables network operators to provide their growing number of users with the required Quality of Service (QoS) that meets with their service demands. In-order for the network operators to make the best out of the heterogeneous LTE-A network, they need to use QoS-based packet scheduling algorithms that can efficiently manage the spectrum resources in the HetNets deployment. In this paper, we survey Quality of Service (QoS) based packet scheduling algorithms that were proposed in the literature for the use of packet scheduling in Heterogeneous LTE-A Networks. We start by explaining the concepts of QoS in LTE, heterogeneous LTE-A networks, and how traffic is classified within a packet scheduling architecture for heterogeneous LTE-A networks. Then, by summarising the proposed QoS-based packet scheduling algorithms in the literature for Heterogeneous LTE-A Networks, and for Femtocells LTE-A Networks. And finally, we provide some concluding remarks in the last section.

An Opportunistic Power Control Scheme for Mitigating User Location Tracking Attacks in Cellular Networks

Cellular networks have been successfully evolved over the decades. Especially, Long-Term Evolution (LTE) has been exceedingly successful and the security threats against LTE systems have increased rapidly. Particularly, <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">tracking</i> LTE user devices has been shown to be effective as the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">temporary</i> user identifiers (IDs) are easily extracted and used to locate targeted devices by passive eavesdroppers. We notice that naive approaches, such as frequent updates of temporary user IDs, are <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">insufficient</i> to mitigate user-tracking attacks since the new and old temporary IDs for the same user device are easily <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">linkable</i> by adversaries who can measure the wireless channel characteristics between the user device and herself. In this paper, we propose an opportunistic uplink power control scheme to minimize the probability of successful user tracking by an adversary whose location is unknown. We devise the notion of average inference error probability in order to measure the level of users’ location privacy. Moreover, we derive the closed-form expression of the approximated average inference error probability and formulate an optimization problem to maximize the average inference error probability under a constraint of an allowable power budget for each user. Against a passive adversary, our proposed power control scheme effectively degrades an adversary’s inference ability by 50% when 10 users are scheduled in each transmission time slot, which will lead to almost 100% inference error at the adversary over multiple time slots.

Interference mitigation with spectrum sharing and aggregation for SDN based cognitive networks

The Cognitive Radio based Software Defined Network (CR-SDN) integrated with 5G technology provides a promising solution for improving wireless broadband coverage. Cognitive radio technology allows users to communicate with an unlicensed spectrum when it is empty. The proposed Cognitive Radio based Software Defined Networking architecture (CR-SDN) allows Wireless Fidelity (Wi-Fi) and Long Term Evolution (LTE) users to access the Television White Space (TVWS) network whenever there is no vacant band available in Wi-Fi and LTE networks. Wi-Fi and there is a possibility whenever the LTE band interference between two users communicating in the same frequency band simultaneously. This interference should be mitigated, and the spectrum should be shared efficiently among the available users. In this paper, the proposed Interference Mitigation with Spectrum Sharing and Aggregation (IMSSA) technique mitigates the interference and shares the spectrum effectively among licensed and unlicensed users. This technique also aggregates the vacant spectrum within the licensed band (TV band and LTE band) and shares the aggregated band among LTE and Wi-Fi users for achieving a higher data rate. Adaptive Q Learning also made based on the spectrum management adaptive spectrum management, spectrum and a frequency band selection scheme used include dynamic access. This offers high spectrum efficiency and aggregation efficiency for ensuring network performance. The mobility management framework which is adopted in the proposed algorithm undertakes an efficient handover process whenever link failure occurs. In this proposed method, to evaluate the performance following parameter there are transmission rate, primary user analysis and transmission power.

Power-Aware Coexistence of Wi-Fi and LTE in the Unlicensed Band Using Time-Domain Virtualization

The rapid increase of mobile devices requires more network capacity as limited licensed spectrum is diminishing access to long-term evolution (LTE) users. As increasing licensed spectrum becomes costly, a cost-effective solution that improves network capacity is needed. Another overlooked issue is spectrum efficiency, where unused resources could be allocated to more LTE users. This article proposes two solutions to address network capacity and spectrum efficiency: moving into unlicensed spectrum and implementing wireless resource virtualization. In addition, as these solutions enhance data rate, thus increasing power consumption, this article includes power-aware optimization as a solution. Operating in the unlicensed band poses a challenge as 5-GHz bands are predominately used by Wi-Fi systems. Based on this challenge, we are proposing a time-sharing wireless resource virtualization (WRV)-based LTE/Wi-Fi coexistence solution that considers joint resource/access point (AP) allocation and power control problems for both technologies. Accordingly, we formulate a mixed-integer nonlinear programming problem and solve using the Lagrangian dual decomposition. We also propose low-complexity heuristics to solve these problems. Results show that the coexistence of Wi-Fi and LTE can be achieved in the unlicensed band with improved power savings using virtualization. Moreover, there is little to no difference in power savings in heterogeneous-traffic scenarios as the algorithm prioritizes maximizing rate to minimizing power.

Device-to-Device Communications Underlaying Cellular Networks: To Use Unlicensed Spectrum or Not?

In this paper, we consider device-to-device (D2D) communications as an underlay to the cellular networks over both licensed and unlicensed spectrum, where Long Term Evolution (LTE) users utilize the spectrum orthogonally while D2D users share the spectrum with LTE users. In the system, each LTE and D2D user can access the licensed or unlicensed band for communications. To maximize the total throughput of the system, we leverage stochastic geometry to derive the throughput for each kind of users by modeling the deployment of users as Poisson point processes (PPPs), and investigate the spectrum access problem for these users. Since the problem is NP-hard, we propose a sequential quadratic programming (SQP) based algorithm to obtain the corresponding suboptimal solutions. Theoretically, we evaluate the system performance by analyzing the throughput regions. Simulation results validate the accuracy of the geometric analysis and verify the effectiveness of the proposed algorithm.

Tunable Duplexers: Downlink Band Isolation Requirements for LTE User Equipment

Tunable duplexers based on self-interference cancellation present a promising alternative to fixed-frequency duplexers (e.g., surface acoustic wave devices), however the level of transmit-to-receive (Tx–Rx) isolation they provide is typically lower compared to acoustic devices. This letter quantifies the impact of reduced isolation on receiver (Rx) noise figure (NF), and determines minimum isolation requirements for Tx-Rx isolation in cellular handset transceivers. Measurements of Tx noise power spectral density from a cellular handset power amplifier are combined with theoretical analysis and long term evolution (LTE) downlink throughput simulations to assess the impact of isolation on the NF and sensitivity. Although lower duplexer isolation can lead to substantial desensitization for some duplex separation/bandwidth combinations, achieving LTE compliant sensitivity requires only 38 dB of isolation in the Rx band. LTE sensitivity specification compliance is therefore readily achievable with current tunable duplexing technologies.

Scheduling for VoLTE: Resource Allocation Optimization and Low-Complexity Algorithms

We consider scheduling and resource allocation in long-term evolution (LTE) networks across voice over the LTE (VoLTE) and best-effort data users. The difference between these two is that VoLTE users get scheduling priority to receive their required quality of service. As we show, strict priority causes data services to suffer. We propose new scheduling and resource allocation algorithms to maximize the sum or proportional fair (PF) throughout amongst data users while meeting VoLTE demands. Essentially, we use VoLTE as an example application with both a guaranteed bit-rate and strict application-specific requirement. We first formulate and solve the frame-level optimization problem for throughput maximization; however, this leads to an integer problem coupled across the LTE transmission time intervals (TTIs). We then propose a TTI-level problem to decouple scheduling across TTIs. Finally, we propose a heuristic scheme, with extremely low complexity. The formulations illustrate the details required to realize resource allocation in an implemented standard. The numerical results show that the performance of the TTI-level scheme is very close to that of the frame-level upper bound. Similarly, the heuristic scheme works well compared to TTI-level optimization and a baseline scheduling algorithm. Finally, we show that our PF optimization retains the high fairness index characterizing PF-scheduling.

Proposing packet-key based end-to-end security architecture for the post-LTE networks

Abstract This paper proposes the end-to-end security scheme with packet key mechanism to perform ciphering of user traffic between two User Equipments (UEs) attached to the different Long Term Evolution (LTE) networks. In LTE system, each UE derives its master key after a mutual authentication is performed between the UE and its local LTE network. In this paper, two end-to-end UEs use their own master keys to generate real-time packet keys where different packet keys are applied to encrypt packet stream data on a packet basis. Because the life cycle of the packet key is same as a packet period, the proposed security scheme significantly improves the security strength for end-to-end LTE users. This paper also analyzes the security strength of the proposed packet key system as well as the degree of latency for the session initialization, real-time packet encryption, and real-time packet decryption.

Efficient LTE/Wi-Fi Coexistence in Unlicensed Spectrum Using Virtual Network Entity: Optimization and Performance Analysis

Long-term evolution (LTE) operation in the unlicensed spectrum is a promising solution to address the scarcity of licensed spectrum for cellular networks. Although this approach brings higher capacity for LTE networks, the Wi-Fi performance operating in this band can be significantly degraded. To address this issue, we consider a coordinated structure, in which both networks are controlled by a higher level network entity. In such a model, LTE users can transmit in the assigned time-slots, while Wi-Fi users can compete with each other by using $p$ -persistent carrier sense multiple access (CSMA) in their exclusive time-share. In an unsaturated network, at each duty cycle, the time-division multiple access (TDMA) scheduling for LTE users and $p$ values for Wi-Fi users should be efficiently updated by the central controller. The corresponding optimization problem is formulated and an iterative algorithm is developed to find the optimal solution using complementary geometric programming and monomial approximations. Aiming to address the quality-of-service assurance for LTE users, an upper bound for average delay of these users is obtained. This analysis could be a basis for the admission control of LTE users in unlicensed bands. The simulation results reveal the performance gains of the proposed algorithm in preserving the Wi-Fi throughput requirement.

Transport Network Capacity Planning And Analysis Operator X Using Overbooking Method In Jombang Rawa Area

The high quality of high-speed communication services is now a requirement for LTE (Long Term Evolution) users, resulting in high traffic capacity requirements. Jombang Rawa area is one area that has a high traffic capacity. To overcome this problem, X operator rolled out a mobile network project called roll out project that aims to provide sufficient LTE network capacity for operator X customers. In the project, the capacity of the transport network is done using a microwave backhaul which aims to support the new LTE site so that there is no bandwidth shortage in the new site path. The method used to obtain the appropriate traffic for the new site path is the overbooking calculation method. Based on Overbooking calculations of 102 sites, there are 22 sites that require a propose bandwidth capacity solution. Using the overbooking method there is a configuration upgrade as a solution to deal with trafficked paths.

Coexistence of DC and CSMA in SRD channel access and resilience to LTE interference: A simulator‐based analysis

AbstractThe foreseen increased use of short‐range devices (SRDs) will boost the competition for radio channel access in license‐exempt frequency bands. Therefore, it is important to find out the most efficient SRD configurations in terms of their performance in high‐contention scenarios; moreover, it is crucial to ensure that SRD networks do not impair the radio systems that operate in neighboring licensed spectrum, and vice versa. This paper addresses the previous issues by simulating a building automation application scenario, where 2 channel access mechanisms, namely duty cycling (DC) and carrier sense multiple access (CSMA), are evaluated independently and in coexisting scenarios, and, also, in the presence of a Long‐Term Evolution (LTE) user equipment. The CSMA protocol analysis shows that very high or very low transmission powers decrease its performance, and thus, either this parameter has to be calibrated or the gateways location has to be adjusted; for the DC protocol, its performance is only affected by the number of gateways within the SRD network, which should be as high as possible. Regarding the coexistence of the DC and CSMA schemes, the results show that CSMA‐based SRDs can successfully operate in the presence of a significant number of DC‐based SRDs, whereas the contrary is not true. Lastly, it is proven that an LTE user equipment may harm the SRD network, although this effect can be mitigated by adjusting the SRDs transmission power; furthermore, the SRDs interference on LTE systems is found to be negligible.

Opportunistic Coexistence of LTE and WiFi for Future 5G System: Experimental Performance Evaluation and Analysis

To alleviate the problem of scarce spectrum resources and meet the ever-increasing of mobile broadband data traffic demands, Licensed Assisted Access (LAA)-Long Term Evolution (LTE), operating in the unlicensed spectrum, is a promising solution. Considering that the unlicensed spectrum is shared by a few incumbent systems, such as IEEE 802.11 (i.e., WiFi), one main target is to guarantee the friendly and harmonious coexistence of LTE with other wireless systems in the unlicensed spectrum. Both listen-before-talk (LBT) and duty cycle methods are regarded as effective ways to solve the coexistence problem in academia and industry so far. Although there are a large number of theoretical researches on LTE in unlicensed spectrum (LTE-U), field trail results are still lacking. In this paper, an experimental testing platform is deployed to model the realistic environment. This paper focuses on three aspects. First, a typical indoor field trial scenario in 5.8 GHz unlicensed bands is deployed, and the performance of LTE-U and WiFi, including coverage and capacity, is evaluated. Specifically, a methodology to determine the proper clear channel assessment energy detection (CCA-ED) threshold for LTE-U is proposed to implement the friendly coexistence between LTE-U and WiFi systems. Second, supplementary downlink (SDL) and Cell ON/OFF mechanisms are investigated to verify the fair coexistence between LAA and WiFi in the unlicensed spectrum. Third, the Enhanced Cell ON/OFF scheme, which introduces Clear to Send (CTS)-to-Self (CTS2S) message, is discussed and evaluated. Based on the built testbed, we obtain threefold conclusions. First of all, introducing LTE into unlicensed spectrums can greatly improve the spectrum efficiency and optimize wireless resources. Furthermore, test results and analyses show that a proper CCA-ED threshold is necessary for coexisting friendly and fairly among different systems, and experiments are also provided to validate the feasibility of the suggested method in various scenarios. Second, experimental results show that SDL mechanism guarantees relatively friendly and harmonious coexistence between LAA and WiFi only in the sparse scenario, while basic Cell ON/OFF mechanism is more effective to ensure coexistence between LAA and WiFi than the SDL. Finally, with the introduction of CTS2S message, the Enhanced Cell ON/OFF scheme is able to achieve more peaceful coexistence between LTE and WiFi users employed in the same bands compared with the Basic Cell ON/OFF scheme.

Electromagnetic Compatibility Problems in LTE Mobile Networks 800 MHz Frequency Band

This paper examines the LTE UE (Long-Term Evolution User Equipment) in 800 MHz frequency band (the so-called digital dividend) interference to Short Range Devices (SRD) in the band of 863 MHz–870 MHz. The fundamental objective of this research is to evaluate the probability of interference and influence of LTE UE emission mask in this regards. The study was performed in two methods: theoretical – simulations with SEAMCAT software and practical – measurements to verify gathered results in simulations. The results of this paper characterize the required technical conditions for LTE mobile networks deployment in 800 MHz band. DOI: http://dx.doi.org/10.5755/j01.eee.21.6.13770

Receiver memory management method for HARQ in LTE-based satellite communication system

Summary For the successful deployment of the long term evolution (LTE)-based mobile satellite service, the price of a user terminal is one of the major factors. A user terminal for the LTE-based satellite communication needs to be implemented with a similar hardware size that is used for a terrestrial LTE user terminal. However, for quality of service provision, the satellite user terminal needs a larger size of memories than the terrestrial terminal does. This is very evident by considering that the N-channel stop and wait hybrid automatic repeat request requires proportionally increasing memory size by the propagation delay, resulting in unmanageable amount of memories in the satellite system. To resolve this problem, we propose an efficient memory management method at the user terminal when the size of memory is insufficient. The simulation results in this paper reveal that the proposed method can increase the throughput about 20.7% when a user terminal is operated under very low throughput condition with an insufficient memory size, compared with the case without memory management scheme. In addition, we show that the additional throughput gain can be obtained by the packet scheduling using the information of receiver memory status. Copyright © 2015 John Wiley & Sons, Ltd.

Adapting LTE M-2-M Protocol Standard to Fulfil Latency Requirements for IEC 61850 GOOSE Messages

Generic Object Oriented Substation Event (GOOSE) Messages face a great challenge in its communication requirements especially in latency point of view. The appearance of the Long-Term Evolution (LTE) has opened a new way that can be used due to its great performance, compared with previous wireless technologies. In order to use LTE technology within the GOOSE message transfer, several points must be put into consideration, and additional requirements need to be within both LTE User Equipment (UE) side and network side. In this paper, we are going to adapt part of the LTE standards to fulfil the requirements of GOOSE messages which needs latency more than or equal to 20 ms, using an experimental approach. The results show that LTE can satisfy the target requirements of latency within the acceptable Bit Error Rate (BER).

Interference Effects of Low-Power Devices on the UE Throughput of a CR-Based LTE System

Recently, the use of mobile devices has increased, and mobile traffic is growing rapidly. In order to deal with such massive traffic, cognitive radio (CR) is applied to efficiently use limited-spectrum resources. However, there can be multiple communication systems trying to access the white space (unused spectrum), and inevitable interference may occur to cause mutual performance degradation. Therefore, understanding the effects of interference in CR-based systems is crucial to meaningful operations of these systems. In this paper, we consider a long-term evolution (LTE) system using additional spectra by accessing the TV white space, where low-power devices (LPDs) are licensed primary users, in addition to TV broadcasting service providers. We model such a heterogeneous system to analyze the co-existence problem and evaluate the interference effects of LPDs on LTE user equipment (UE) throughput. We then present methods to mitigate the interference effects of LPDs by ‘de-selecting’ some of the UEs to effectively increase the overall sector throughput of the CR-based LTE system.

CoPoMo: a context‐aware power consumption model for LTE user equipment

ABSTRACTIncreasing the battery lifetime of power‐hungry mobile devices has become a major research target for mobile operators. Based on extensive measurement campaigns with the most recent Long Term Evolution (LTE) devices, we introduce a new Markovian power consumption model, which takes into account the chosen system parameters (such as the number of physical resource blocks) as well as the context of a user in terms of radio channel conditions and service characteristics (non‐real‐time vs. real time). One key advancement of this generic model is its stochastic nature, which allows for determining the average power consumption of a device based on usage profiles including location information and service statistics. We have conducted comprehensive system simulations using realistic channel characteristics derived from ray‐tracing analyses and validated the new model. Finally, we show that the proposed context‐aware power consumption model enables quantitative analyses of the trade‐off between network resource allocation and enhanced battery lifetime. © 2013 The Authors. Transactions on Emerging Telecommunications Technologies published by John Wiley &amp; Sons, Ltd.

Interference Rejection Combining in LTE Networks

Long Term Evolution (LTE) provides high spectral efficiency within one cell, but it is shown to be highly vulnerable to inter-cell interference. While LTE as well as Wideband Code Division Multiple Access (WCDMA) suffers uplink interference especially with a frequency reuse factor of one, WCDMA has some inherent layer 1 mechanisms to alleviate these effects, namely macro-diversity and spreading codes. In contrast, LTE user data are more localized in the time/frequency domain, calling for different mechanisms for interference reduction in the receiver. For the higher layers, techniques such as fractional power control or fractional frequency reuse can be used to mitigate the interference but are shown to be sub-optimal. For layer 1, interference rejection combining (IRC) is described as an efficient alternative to increase uplink bit rates in areas where cells overlap. IRC principles in the presence of radio fading channels are detailed, while strategies for both interference suppression and signal-to-interference-plus-noise ratio (SINR) maximization are considered. Taking a didactic approach, we compare multiple antenna receiver techniques (maximal ratio combining (MRC), IRC, multiple input multiple output (MIMO)), analyze the key factors of IRC efficiency (the number of receiving antennas and interferers, time synchronization, interference over thermal, and scheduling decisions), and provide link level performance comparisons. We also provide implementation considerations for integrating the IRC in the current eNodeB receiver. As the purpose of this paper is to give a basic level introduction to IRC applied to the LTE uplink and highlight the respective surroundings, the IRC approach will be covered rather intuitively by illustrations without a great deal of theoretical detail. © 2012 Alcatel-Lucent.

Resource scheduling in downlink LTE-advanced system with carrier aggregation

In this paper, we focus on the resource scheduling in the downlink of long term evolution advanced (LTE-A) assuming equal power allocation among subcarriers. Considering the backward compatibility, the LTE-A system serves LTE-A and long term evolution (LTE) users together with carrier aggregation (CA) technology. When CA is applied, a well-designed resource scheduling scheme is essential to the LTE-A system. Joint scheduling (JS) and independent scheduling (INS) are two resource scheduling schemes. JS is optimal in performance but with high complexity. Whereas INS is applied, the LTE users will acquire few resources because they can not support CA technology. And the system fairness is disappointing. In order to improve the system fairness without bringing high complexity to the system, an improved proportional fair (PF) scheduling algorithm base on INS is proposed. In this algorithm, we design a weigh factor which is related with the number of the carriers and the percentage of LTE users. Simulation result shows that the proposed algorithm can effectively enhance the throughput of LTE users and improve the system fairness.