A Space-Time Analysis of LTE and Wi-Fi Inter-Working
01 Nov 2016-IEEE Journal on Selected Areas in Communications (IEEE Press)-Vol. 34, Iss: 11, pp 2981-2998
TL;DR: A new framework to analyze the network performance of several inter-working strategies for the LTE and the Wi-Fi, taking into account the intra-cell time efficiency and the signal and inter-cell interference with spatial randomness is proposed.
Abstract: Cooperative inter-working of the long-term evolution (LTE) and the wireless fidelity (Wi-Fi) networks have drawn much attention recently, and several strategies have been proposed to enhance their network capacity. In this paper, we propose a new framework to analyze the network performance of several inter-working strategies for the LTE and the Wi-Fi. The proposed framework considers both the LTE and the Wi-Fi systems, both the downlink (DL) and the uplink (UL) transmissions, and the generated interference in both the time and the spatial domains. Based on such a framework, we theoretically analyze for the first time the performance of a Wi-Fi network, taking into account the intra-cell time efficiency and the signal and inter-cell interference with spatial randomness. Moreover, we study the performance of: 1) a coexisting architecture where Wi-Fi coexists with an ideal carrier sense multiple access (CSMA) duplex system, which represents an upper bound performance for the LTE Release 14 licensed assisted access network and 2) a brand-new architecture that allows UL on LTE and DL on Wi-Fi, referred to as the Boost architecture. We derive analytical results for both the DL and the UL network performances in terms of the signal quality distribution and the total area system throughput (AST) in these two architectures, and quantify their performance gain compared with the traditional disjoint LTE Wi-Fi architecture. Simulation results validate our analysis results, and show that, in a typical outdoor scenario, the coexisting architecture and the Boost architecture can, respectively, increase the total AST up to 11% and 25%, compared with the traditional disjoint LTE Wi-Fi.
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TL;DR: In this article, a comprehensive survey of these three spectrum sharing technologies is provided and a novel analytical framework is proposed to evaluate the network performance of these technologies by incorporating both spatial and time domain analyses and integrating different types of cells in one network as a whole.
Abstract: The dynamic exploitation of unlicensed spectrum by mobile operators is becoming a trend of future 5G networks, with several efficient solutions being standardized for enabling spectrum sharing. Solutions with various design philosophies diversify the network architectures and protocols. Among them, LAA aims at the physical-layer coexistence of LTE and WiFi within the unlicensed spectrum, while LWA and LWIP focus on aggregating the link capacity of LTE in the licensed spectrum and WiFi in the unlicensed one. In this article, a comprehensive survey of these three spectrum sharing technologies are provided. Moreover, a novel analytical framework is proposed to evaluate the network performance of these technologies by incorporating both spatial and time domain analyses and integrating different types of cells in one network as a whole. Simulation results are provided to compare the system throughput of these spectrum reuse technologies.
13 citations
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TL;DR: The impact of coexistence of Wi-Fi networks on the performance of DSRC is discussed through an analytical framework based on stochastic geometry, and uplink and downlink transmissions are analyzed, with voice and background traffic being the highest and lowest priority traffic, respectively.
Abstract: The proliferation of high data-rate applications and services in next-generation WLANs, as well as the significant increase in the number of Wi-Fi devices, is triggering the search for more bandwidth. For this, the Federal Communications Commission (FCC) is considering a proposal to permit devices, such as those that use the IEEE 802.11 (Wi-Fi) protocol, to operate in the 5.9 GHz band allocated to the intelligent transportation system (ITS). However, the nature of these bands poses a challenge since ITS dedicated short range communications (DSRC) networks use them to share safety-critical messages and may be subject to severe interference from other coexisting transmissions. We discuss the impact of coexistence of Wi-Fi networks on the performance of DSRC through an analytical framework based on stochastic geometry. We consider the recent IEEE 802.11ax Wi-Fi standard, and analyze uplink and downlink transmissions, with voice and background traffic being the highest and lowest priority traffic, respectively. We also validate the fixed contention window size of the derived stochastic geometry model using NS-3 simulations. The proposed framework can serve to increase awareness among regulatory bodies of the extent to which coexistence will adversely affect the performance of DSRC.
10 citations
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TL;DR: A novel UAV-aided small-cell content caching network is proposed and analyzed, where joint transmission (JT) is considered in the dense small- cell networks and mobile UAVs are employed to shorten the serving distance.
Abstract: Unmanned aerial vehicles (UAVs), featured by the high-mobility and high-quality propagation environment, have shown great potential in wireless communication applications. In this paper, a novel UAV-aided small-cell content caching network is proposed and analyzed, where joint transmission (JT) is considered in the dense small-cell networks and mobile UAVs are employed to shorten the serving distance. The system performance is evaluated in terms of the average cache hit probability and the ergodic transmission rate. From the analytical results, we find that (i) the proposed UAV-aided small-cell network shows superior caching performance and, even with a small density of UAVs the system’s cache hit probability, can be improved significantly; (ii) the content’s optimal caching probability to maximize the cache hit probability is proportional to the (K+1)-th root of its request probability, where K is the number of small-cell base stations that serve each user by JT; (iii) caching the most popular content in UAVs may lead to a low transmission rate due to the limited resource offered by the low-density UAVs. Simulation results are presented to validate the theoretical results and the performance gain achieved by the optimal caching strategy.
1 citations
Cites background from "A Space-Time Analysis of LTE and Wi..."
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TL;DR: A new framework to model and evaluate the performance of LAA/Wi-Fi coexistence based on marked Poisson point process (MPPP) and Markov chain model is proposed and results show the validity of the proposed model with the overestimation of the LAA and Wi-Fi nodes density in MPPP model.
Abstract: In Release 13 of the 3rd Generation Partnership Project standard, the deployment of long-term evolution (LTE)/ LTE-advanced to the unlicensed spectrum called licensed-assisted access (LAA) was introduced to satisfy the high demand of traffic data with a new type of services mostly multimedia streams. The unlicensed spectrum is a shared resource between different radio access terminals such as Wi-Fi and radar system, and listen before talk (LBT) in LTE side makes this coexistence possible. In this letter, we propose a new framework to model and evaluate the performance of LAA/Wi-Fi coexistence based on marked Poisson point process (MPPP) and Markov chain model. The proposed model captures the back-off procedure in the spatial and time domain to provide a more realistic analysis of the channel busy probability and the signal to interference plus noise ratio coverage probability. Numerical results show the validity of the proposed model with the overestimation of the LAA and Wi-Fi nodes density in MPPP model.
1 citations
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References
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TL;DR: In this paper, a simple but nevertheless extremely accurate, analytical model to compute the 802.11 DCF throughput, in the assumption of finite number of terminals and ideal channel conditions, is presented.
Abstract: The IEEE has standardized the 802.11 protocol for wireless local area networks. The primary medium access control (MAC) technique of 802.11 is called the distributed coordination function (DCF). The DCF is a carrier sense multiple access with collision avoidance (CSMA/CA) scheme with binary slotted exponential backoff. This paper provides a simple, but nevertheless extremely accurate, analytical model to compute the 802.11 DCF throughput, in the assumption of finite number of terminals and ideal channel conditions. The proposed analysis applies to both the packet transmission schemes employed by DCF, namely, the basic access and the RTS/CTS access mechanisms. In addition, it also applies to a combination of the two schemes, in which packets longer than a given threshold are transmitted according to the RTS/CTS mechanism. By means of the proposed model, we provide an extensive throughput performance evaluation of both access mechanisms of the 802.11 protocol.
7,899 citations
Book•
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29 Aug 2011
TL;DR: Scrase et al. as discussed by the authors provide a comprehensive system-level understanding of LTE, built on explanations of the theories which underlie it, and provide a broad, balanced and reliable perspective on this important technology Lucid yet thorough, the book devotes particular effort to explaining the theoretical concepts in an accessible way.
Abstract: Where this book is exceptional is that the reader will not just learn how LTE works but why it works Adrian Scrase, ETSI Vice-President, International Partnership Projects LTE - The UMTS Long Term Evolution: From Theory to Practice provides the reader with a comprehensive system-level understanding of LTE, built on explanations of the theories which underlie it The book is the product of a collaborative effort of key experts representing a wide range of companies actively participating in the development of LTE, as well as academia This gives the book a broad, balanced and reliable perspective on this important technology Lucid yet thorough, the book devotes particular effort to explaining the theoretical concepts in an accessible way, while retaining scientific rigour It highlights practical implications and draws comparisons with the well-known WCDMA/HSPA standards The authors not only pay special attention to the physical layer, giving insight into the fundamental concepts of OFDMA, SC-FDMA and MIMO, but also cover the higher protocol layers and system architecture to enable the reader to gain an overall understanding of the system Key Features: Draws on the breadth of experience of a wide range of key experts from both industry and academia, giving the book a balanced and broad perspective on LTE Provides a detailed description and analysis of the complete LTE system, especially the ground-breaking new physical layer Offers a solid treatment of the underlying advances in fundamental communications and information theory on which LTE is based Addresses practical issues and implementation challenges related to the deployment of LTE as a cellular system Includes an accompanying website containing a complete list of acronyms related to LTE, with a brief description of each (http://wwwwileycom/go/sesia_theumts) This book is an invaluable reference for all research and development engineers involved in LTE implementation, as well as graduate and PhD students in wireless communications Network operators, service providers and R&D managers will also find this book insightful
3,452 citations
"A Space-Time Analysis of LTE and Wi..." refers background in this paper
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TL;DR: The proposed model is pessimistic (a lower bound on coverage) whereas the grid model is optimistic, and that both are about equally accurate, and the proposed model may better capture the increasingly opportunistic and dense placement of base stations in future networks.
Abstract: Cellular networks are usually modeled by placing the base stations on a grid, with mobile users either randomly scattered or placed deterministically. These models have been used extensively but suffer from being both highly idealized and not very tractable, so complex system-level simulations are used to evaluate coverage/outage probability and rate. More tractable models have long been desirable. We develop new general models for the multi-cell signal-to-interference-plus-noise ratio (SINR) using stochastic geometry. Under very general assumptions, the resulting expressions for the downlink SINR CCDF (equivalent to the coverage probability) involve quickly computable integrals, and in some practical special cases can be simplified to common integrals (e.g., the Q-function) or even to simple closed-form expressions. We also derive the mean rate, and then the coverage gain (and mean rate loss) from static frequency reuse. We compare our coverage predictions to the grid model and an actual base station deployment, and observe that the proposed model is pessimistic (a lower bound on coverage) whereas the grid model is optimistic, and that both are about equally accurate. In addition to being more tractable, the proposed model may better capture the increasingly opportunistic and dense placement of base stations in future networks.
3,042 citations
"A Space-Time Analysis of LTE and Wi..." refers methods in this paper
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Book•
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TL;DR: This rigorous introduction to stochastic geometry will enable you to obtain powerful, general estimates and bounds of wireless network performance and make good design choices for future wireless architectures and protocols that efficiently manage interference effects.
Abstract: Covering point process theory, random geometric graphs and coverage processes, this rigorous introduction to stochastic geometry will enable you to obtain powerful, general estimates and bounds of wireless network performance and make good design choices for future wireless architectures and protocols that efficiently manage interference effects. Practical engineering applications are integrated with mathematical theory, with an understanding of probability the only prerequisite. At the same time, stochastic geometry is connected to percolation theory and the theory of random geometric graphs and accompanied by a brief introduction to the R statistical computing language. Combining theory and hands-on analytical techniques with practical examples and exercises, this is a comprehensive guide to the spatial stochastic models essential for modelling and analysis of wireless network performance.
2,327 citations
"A Space-Time Analysis of LTE and Wi..." refers methods in this paper
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TL;DR: A tractable framework for SINR analysis in downlink heterogeneous cellular networks (HCNs) with flexible cell association policies is developed and the average ergodic rate of the typical user, and the minimum average users throughput - the smallest value among the average user throughputs supported by one cell in each tier is derived.
Abstract: In this paper we develop a tractable framework for SINR analysis in downlink heterogeneous cellular networks (HCNs) with flexible cell association policies. The HCN is modeled as a multi-tier cellular network where each tier's base stations (BSs) are randomly located and have a particular transmit power, path loss exponent, spatial density, and bias towards admitting mobile users. For example, as compared to macrocells, picocells would usually have lower transmit power, higher path loss exponent (lower antennas), higher spatial density (many picocells per macrocell), and a positive bias so that macrocell users are actively encouraged to use the more lightly loaded picocells. In the present paper we implicitly assume all base stations have full queues; future work should relax this. For this model, we derive the outage probability of a typical user in the whole network or a certain tier, which is equivalently the downlink SINR cumulative distribution function. The results are accurate for all SINRs, and their expressions admit quite simple closed-forms in some plausible special cases. We also derive the average ergodic rate of the typical user, and the minimum average user throughput - the smallest value among the average user throughputs supported by one cell in each tier. We observe that neither the number of BSs or tiers changes the outage probability or average ergodic rate in an interference-limited full-loaded HCN with unbiased cell association (no biasing), and observe how biasing alters the various metrics.
1,140 citations
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