Performance Evaluation of LTE and Wi-Fi Coexistence in Unlicensed Bands
02 Jun 2013-pp 1-6
TL;DR: A simulator-based system- level analysis in order to assess the network performance in an office scenario shows that LTE system performance is slightly affected by coexistence whereas Wi-Fi is significantly impacted by LTE transmissions.
Abstract: The deployment of modern mobile systems has faced severe challenges due to the current spectrum scarcity. The situation has been further worsened by the development of different wireless technologies and standards that can be used in the same frequency band. Furthermore, the usage of smaller cells (e.g. pico, femto and wireless LAN), coexistence among heterogeneous networks (including amongst different wireless technologies such as LTE and Wi-Fi deployed in the same frequency band) has been a big field of research in the academy and industry. In this paper, we provide a performance evaluation of coexistence between LTE and Wi-Fi systems and show some of the challenges faced by the different technologies. We focus on a simulator-based system- level analysis in order to assess the network performance in an office scenario. Simulation results show that LTE system performance is slightly affected by coexistence whereas Wi-Fi is significantly impacted by LTE transmissions. In coexistence, the Wi-Fi channel is most often blocked by LTE interference, making the Wi-Fi nodes to stay on the LISTEN mode more than 96% of the time. This reflects directly on the Wi-Fi user throughput, that decreases from 70% to ≈100% depending on the scenario. Finally, some of the main issues that limit the LTE/Wi-Fi coexistence and some pointers on the mutual interference management of both the systems are provided.
Citations
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01 Sep 2015
TL;DR: A new access control mechanism for downlink cellular networks using the unlicensed band is proposed and the numerical results demonstrate that the proposedAccess control mechanism guarantees the UBE's target performance under various network circumstances.
Abstract: Licensed band communication systems have recently begun trying to utilize unlicensed bands. Due to lack of coordination, however, this spectrum utilization results in strong interference to other unlicensed band equipment (UBE). This problem highlights the need for coexistence scenario that will prevent UBE performance degradation. In this paper, we propose a new access control mechanism for downlink cellular networks using the unlicensed band. First, we analyze the impact of the cellular networks on the UBE outage performance. Based on the analysis, we then obtain a decision threshold for the unlicensed band access control. In the proposed control mechanism, the decision threshold is adaptively controlled by considering the density of the UBE. The numerical results demonstrate that the proposed access control mechanism guarantees the UBE's target performance under various network circumstances.
Cites background from "Performance Evaluation of LTE and W..."
...A recent movement has involved licensed band communication systems attempting to share an unlicensed band with other unlicensed band equipment (UBE) [2]....
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...In this coexistence scenario, however, the cellular networks severely degrade the UBE performance if no modification is made to the legacy access scheme [2]....
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06 Nov 2017
TL;DR: This demo presents a highly configurable packetized-LTE PHY open-source framework for coexistence experiments that allows the evaluation and comparison of different coexistence techniques.
Abstract: Spectrum scarcity has been driving cellular operators to utilize unlicensed spectrum in conjunction with licensed bands to deliver mobile data to its Long-Term Evolution (LTE) users, offloading the fully allocated LTE bands. However, the use of LTE in unlicensed spectrum creates numerous challenges as the fair coexistence with other technologies. A myriad of experimental works tackles the problems involved in the coexistence of different radio access technologies (RAT) in unlicensed spectrum, however, they do not cover all aspects of the problem and fail to provide the framework adopted in the experiments for reproducible research. Therefore, in this demo we present a highly configurable packetized-LTE PHY open-source framework for coexistence experiments. The framework allows the evaluation and comparison of different coexistence techniques.
Dissertation•
27 Jun 2017
TL;DR: In this paper, the authors propose a solution semi-distribuee de faible complexite for attenuer the surcharge de communication d'une solution centralisee que nous proposons egalement.
Abstract: L'Internet des objets (IoT) fait reference a la croissance continue des reseaux d'objets du quotidien qui s'interconnectent entre eux ou avec d'autres systemes Internet via les capteurs sans fil qui y sont attaches. L'IoT promet un futur ou des milliards de terminaux intelligents seront connectes et geres via une gamme de reseaux de communication et de serveurs bases dans le cloud, permettant ainsi l'apparition d'un large spectre d’applications de surveillance et de controle. Les communications machine-a-machine (M2M), egalement connues sous le nom de “Machine-Type-Communication” (MTC) par les reseaux cellulaires, constituent une technologie cle permettant d'activer partiellement l'IoT. Les communications M2M sont un nouveau paradigme qui facilite la connectivite omnipresente entre une myriade de dispositifs sans ou avec intervention humaine limitee. La demande croissante de connectivite a mis au defi les operateurs de reseau a concevoir de nouveaux algorithmes d'allocation de ressources radio pour gerer l'echelle massive des communications MTC.Contrairement aux technologies d'acces radio traditionnelles, adaptees aux communications usuelles, dites de humain-a-humain (H2H), l'objectif de cette these est de developper de nouvelles techniques de partage de ressources radio efficaces et adaptatives pour les MTC dans un scenario de coexistence H2H/M2M. Dans le cadre de cette these, notre premiere contribution consiste en la proposition d'un systeme d'acces multiple adapte pour resoudre a la fois les problemes lies a la rarete des ressources radio, a la scalabilite et a la surcharge de la station de base (BS). A cette fin, nous proposons de decomposer les operations de communication en les groupant. Ainsi, les MTC correspondent a des communications locales en liaison montante entre des dispositifs connus sous le nom de “Machine-Type-Device” (MTD), et un cluster head appele “Machine-Type- Head” (MTH). Nous examinons ainsi la necessite d'agreger la technologie M2M et le “dispositif-a-dispositif” (D2D), considere comme composante majeure des reseaux cellulaires evolutifs du futur. Nous modelisons le probleme de partage de ressources radio entre les MTDs et les utilisateurs H2H sous la forme d’un graphe biparti et developpons un algorithme de partage de ressources radio pour MTC base sur les graphes afin d’attenuer les interferences co-canal et donc ameliorer l'efficacite du reseau. En outre, une solution semi-distribuee de faible complexite est developpee pour attenuer la surcharge de communication d'une solution centralisee que nous proposons egalement. Ensuite, dans une deuxieme contribution de cette these, nous nous interessons a examiner comment les dispositifs M2M peuvent partager les ressources radio disponibles sans pour autant degrader les performances des applications H2H. Par consequent, nous proposons un systeme de partage de ressources efficace en terme de spectre et de puissance. Nous introduisons a l'algorithme de partage de ressources radio base sur les graphes une fonction adaptative de controle de puissance utilisant l'un des deux mecanismes suivants : un controleur proportionnel integral derive (PID) et la logique floue. Enfin, comme troisieme contribution de cette these, nous developpons un systeme de partage de ressources radio efficace en terme de puissance et entierement distribue pour les MTC. Nous utilisons la theorie des jeux et modelisons le probleme de partage de ressources par un jeu hybride ou les dispositifs M2M rivalisent pour les ressources radio et basculent de facon opportuniste entre un jeu non-cooperatif et un jeu cooperatif. Une evaluation des performances des solutions derivees dans le contexte des reseaux LTE est menee. Les resultats des simulations montrent que les solutions proposees ont un impact significatif sur la maximisation de l'efficacite de l'utilisation du spectre, l'attenuation de l'effet negatif sur les services H2H et la prolongation de la duree de vie des batteries des MTDs
08 Nov 2017
TL;DR: This paper presents LTE-LAA and Wi-Fi physical layer simulation results in unlicensed frequency bands in indoor environments in the case of two antennas at the transmitter and receiver sides and shows that LTE outperformsWi-Fi based on BCC decoder.
Abstract: This paper presents LTE-LAA and Wi-Fi physical layer simulation results in unlicensed frequency bands in indoor environments in the case of two antennas at the transmitter and receiver sides. As expected, the results show that LTE outperforms Wi-Fi based on BCC decoder. The general trend is the higher the bit rate is, the greater the LTE gain is compared to Wi-Fi. Tables of quality are provided: for a target BER, the required SNR for both systems are given. Furthermore, the LTE coverage distance gain compared to Wi-Fi system is discussed.
TL;DR: In this article , a context-aware network feature relationship-based optimization (CANEFRO) approach is proposed and validated through decision matrix analysis, which investigates the use of more precise higher-order network feature relationships (NFRs) in optimization formulations and the consequent tradeoff that arises between the increase in convergence time (Speed) and the nearness to optimal results (Accuracy).
Abstract: Unlicensed cellular networks are being deployed worldwide by cellular operators to meet the rising data demands. However, the unlicensed band has existing incumbents such as Wi-Fi and radar systems. This creates a highly dynamic environment, making harmonious unlicensed coexistence difficult. Consequently, conventional optimization techniques are not sufficient to offer latency-critical applications and services. A data-driven hybrid optimization approach is necessary for optimal network performance with low convergence times. However, a largely unexplored problem in dense unlicensed network optimization is the accuracy-speed trade-off, that is, achieving high accuracy in optimization objectives with minimal time costs. This work seeks to address this problem through a hybrid optimization approach that combines machine learning and network optimization. It investigates the use of more precise higher-order network feature relationships (NFRs) in optimization formulations and the consequent trade-off that arises between the increase in convergence time (Speed) and the nearness to optimal results (Accuracy). In addition, it demonstrates the relevance of context awareness of network conditions and the traffic environment to mitigate the trade-off. To that end, a context-aware network feature relationship-based optimization (CANEFRO) approach is proposed and validated through decision matrix analysis. The experiments were carried out on a coexistence testbed consisting of both unlicensed LTE standards (LTE-U & LAA) and two Wi-Fi standards (802.11n/ac) on multiple channel bandwidths. In addition, LTE-U & LAA are contrasted on signaling and user data traffic data models and resource block allocation performance. More importantly, CANEFRO demonstrates the impact of the network context on the degree of feature relationship ( $2^{nd}$ & $3^{rd}$ degree polynomials), objective of optimization (SINR and Capacity), and the network use case (Accuracy vs. Speed). CANEFRO is also used to contrast LTE-U & LAA optimization performance. In particular, the decision matrix analysis demonstrates a higher decision score for LAA by as much as 42% compared to LTE-U.
References
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TL;DR: An overview of the techniques being considered for LTE Release 10 (aka LTEAdvanced) is discussed, which includes bandwidth extension via carrier aggregation to support deployment bandwidths up to 100 MHz, downlink spatial multiplexing including single-cell multi-user multiple-input multiple-output transmission and coordinated multi point transmission, and heterogeneous networks with emphasis on Type 1 and Type 2 relays.
Abstract: LTE Release 8 is one of the primary broadband technologies based on OFDM, which is currently being commercialized. LTE Release 8, which is mainly deployed in a macro/microcell layout, provides improved system capacity and coverage, high peak data rates, low latency, reduced operating costs, multi-antenna support, flexible bandwidth operation and seamless integration with existing systems. LTE-Advanced (also known as LTE Release 10) significantly enhances the existing LTE Release 8 and supports much higher peak rates, higher throughput and coverage, and lower latencies, resulting in a better user experience. Additionally, LTE Release 10 will support heterogeneous deployments where low-power nodes comprising picocells, femtocells, relays, remote radio heads, and so on are placed in a macrocell layout. The LTE-Advanced features enable one to meet or exceed IMT-Advanced requirements. It may also be noted that LTE Release 9 provides some minor enhancement to LTE Release 8 with respect to the air interface, and includes features like dual-layer beamforming and time-difference- of-arrival-based location techniques. In this article an overview of the techniques being considered for LTE Release 10 (aka LTEAdvanced) is discussed. This includes bandwidth extension via carrier aggregation to support deployment bandwidths up to 100 MHz, downlink spatial multiplexing including single-cell multi-user multiple-input multiple-output transmission and coordinated multi point transmission, uplink spatial multiplexing including extension to four-layer MIMO, and heterogeneous networks with emphasis on Type 1 and Type 2 relays. Finally, the performance of LTEAdvanced using IMT-A scenarios is presented and compared against IMT-A targets for full buffer and bursty traffic model.
1,044 citations
"Performance Evaluation of LTE and W..." refers background in this paper
...4GHz band has already been established [7], and the recent inclusion of features on LTE standard [12] are promoting its usage on pico and femto cells, it is possible that in the near future coexistence between LTE (-ADV) and Wi-Fi will become important....
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TL;DR: Concepts underlying the "property" and "commons" debate are presented, options for spectrum reform are clarified, and the trade-offs of spectrum sharing are described.
Abstract: Many complain about severe spectrum shortage. The shortage comes from outdated spectrum policies that allows for little sharing. Regulators have granted licenses that offer exclusive access to the spectrum. When these licensees are not transmitting, the spectrum sits idle. A new technology regarding spectrum shortage enables more spectrum sharing that unleashes innovative products and services, provided that we adopt the appropriate spectrum policies. Two camps are pushing for extreme reform, one for "property rights" and the other for "spectrum commons". This article presents concepts underlying the "property" and "commons" debate, clarifies options for spectrum reform, and describes the trade-offs of spectrum sharing
592 citations
"Performance Evaluation of LTE and W..." refers background in this paper
...One of the most promising techniques for dealing with the lack of available spectrum is the concept of spectrum sharing [1] ....
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22 Apr 2007
TL;DR: An adjusted Shannon capacity formula is introduced, where it is shown that the bandwidth efficiency can be calculated based on system parameters, while the SNR efficiency is extracted from detailed link level studies.
Abstract: In this paper we propose a modification to Shannon capacity bound in order to facilitate accurate benchmarking of UTRAN long term evolution (LTE). The method is generally applicable to wireless communication systems, while we have used LTE air-interface technology as a case study. We introduce an adjusted Shannon capacity formula, where we take into account the system bandwidth efficiency and the SNR efficiency of LTE. Separating these issues, allows for simplified parameter extraction. We show that the bandwidth efficiency can be calculated based on system parameters, while the SNR efficiency is extracted from detailed link level studies including advanced features of MIMO and frequency domain packet scheduling (FDPS). We then use the adjusted Shannon capacity formula combined with G-factor distributions for macro and micro cell scenarios to predict LTE cell spectral efficiency (SE). Such LTE SE predictions are compared to LTE cell SE results generated by system level simulations. The results show an excellent match of less that 5-10% deviation.
580 citations
"Performance Evaluation of LTE and W..." refers methods in this paper
...For physical layer (PHY) abstraction, Shannon-fitting [14] is employed to predict the PHY performance at the system-level....
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09 Jun 2013
TL;DR: This paper considers two of the most prominent wireless technologies available today, namely Long Term Evolution (LTE), and WiFi, and addresses some problems that arise from their coexistence in the same band, and proposes a simple coexistence scheme that reuses the concept of almost blank subframes in LTE.
Abstract: The recent development of regulatory policies that permit the use of TV bands spectrum on a secondary basis has motivated discussion about coexistence of primary (e.g. TV broadcasts) and secondary users (e.g. WiFi users in TV spectrum). However, much less attention has been given to coexistence of different secondary wireless technologies in the TV white spaces. Lack of coordination between secondary networks may create severe interference situations, resulting in less efficient usage of the spectrum. In this paper, we consider two of the most prominent wireless technologies available today, namely Long Term Evolution (LTE), and WiFi, and address some problems that arise from their coexistence in the same band. We perform exhaustive system simulations and observe that WiFi is hampered much more significantly than LTE in coexistence scenarios. A simple coexistence scheme that reuses the concept of almost blank subframes in LTE is proposed, and it is observed that it can improve the WiFi throughput per user up to 50 times in the studied scenarios.
324 citations
"Performance Evaluation of LTE and W..." refers background in this paper
...This kind of approach has started to be investigated in [16], where LTE/Wi-Fi coexistence is enabled by LTE blank subframe allocation....
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27 Aug 2007
TL;DR: A channel hopping design is prototype using PRISM NICs, and it is found that it can sustain throughput at levels of RF interference well above that needed to disrupt unmodified links, and at a reasonable cost in terms of switching overheads.
Abstract: We study the impact on 802.11 networks of RF interference from devices such as Zigbee and cordless phones that increasingly crowd the 2.4GHz ISM band, and from devices such as wireless camera jammers and non-compliant 802.11 devices that seek to disrupt 802.11 operation. Our experiments show that commodity 802.11 equipment is surprisingly vulnerable to certain patterns of weak or narrow-band interference. This enables us to disrupt a link with an interfering signal whose power is 1000 times weaker than the victim's 802.11 signals, or to shut down a multiple AP, multiple channel managed network at a location with a single radio interferer. We identify several factors that lead to these vulnerabilities, ranging from MAC layer driver implementation strategies to PHY layer radio frequency implementation strategies. Our results further show that these factors are not overcome by simply changing 802.11 operational parameters (such as CCA threshold, rate and packet size) with the exception of frequency shifts. This leads us to explore rapid channel hopping as a strategy to withstand RF interference. We prototype a channel hopping design using PRISM NICs, and find that it can sustain throughput at levels of RF interference well above that needed to disrupt unmodified links, and at a reasonable cost in terms of switching overheads.
300 citations
"Performance Evaluation of LTE and W..." refers background in this paper
...However, it is observed that the coexistence of heterogeneous systems in the same frequency bands causes a meaningful degradation on the system performance (e.g., Wi-Fi and Bluetooth [3], Wi-Fi and ZigBee [4], Wi-Fi and WiMAX [5])....
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..., Wi-Fi and Bluetooth [3], Wi-Fi and ZigBee [4], Wi-Fi and WiMAX [5])....
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