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Proceedings ArticleDOI

Performance Evaluation of LTE and Wi-Fi Coexistence in Unlicensed Bands

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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Dissertation
01 Jan 2015

8 citations


Cites background from "Performance Evaluation of LTE and W..."

  • ...This mechanism allows the reduction of collisions with Wi-Fi and other coexisting mechanisms in ISM band [7], [6]....

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  • ...Regarding this matter, the work in [6] considers two thresholds of antenna power transmitter, where one is for identifying transmissions related to Wi-Fi stations (STAs) and another for LTE user equipments (UEs) in line of interference avoidance and better coexistence of these two mechanisms....

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  • ...Because of the above reasons, the authors of [6] introduced the concepts of Interference plus Noise Ratio (SINR) at each node engaged in transmission and Almost Blank Subframes (ABS) [8] which mute some frames in one layer and prevent the interference in others....

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  • ...Page | 2 better than Wi-Fi which is considerably impacted and forced by LTE to remain in listen mode for long time [6], [7]....

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Journal ArticleDOI
TL;DR: This paper detects and identifies cross-technology interference on off-the-shelf WiFi cards by monitoring the sequence of receiver errors and proposes two methods to recognize the source of interference based on artificial neural networks and hidden Markov chains.
Abstract: In this paper, we show that inter-technology interference can be recognized using commodity WiFi devices by monitoring the statistics of receiver errors. Indeed, while for WiFi standard frames the error probability varies during the frame reception in different frame fields (PHY, MAC headers, and payloads) protected with heterogeneous coding, errors may appear randomly at any point during the time the demodulator is trying to receive an exogenous interfering signal. We thus detect and identify cross-technology interference on off-the-shelf WiFi cards by monitoring the sequence of receiver errors (bad PLCP, bad FCS, invalid headers, etc.) and propose two methods to recognize the source of interference based on artificial neural networks and hidden Markov chains. The result is quite impressive, reaching an average accuracy of over 95% in recognizing ZigBee, microwave, and LTE (in unlicensed spectrum) interference.

8 citations


Cites background from "Performance Evaluation of LTE and W..."

  • ...Although most of the current studies are based on simulations (see [6]), preliminary empirical results show that WiFi performance can be critically affected even when LTE links operate at the minimum bandwidth of 1....

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  • ...Preliminary empirical and simulation results [6] show that WiFi performance can be critically affected even when LTE links operate at the minimum bandwidth of 1....

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Journal ArticleDOI
TL;DR: It is argued that all this can be achieved in a cost-effective way if the network is flexible and reconfigurable, and two of the building blocks of the Flex5Gware architecture, namely on-the-fly MAC reconfiguration and dynamic multi-cell coordinated resource scheduling, can leverage context and content information to make reconfigured decisions.
Abstract: 5G networks will have to offer extremely high volumes of content, compared to those of today’s. Moreover, they will have to support heterogeneous traffics, including machine-to-machine, generated by a massive volume of Internet-of-Things devices. Traffic demands will be variable in time and space. In this work, we argue that all this can be achieved in a cost-effective way if the network is flexible and reconfigurable. We present the Flex5Gware network architecture, designed to meet the above requirements. Moreover, we discuss the links between flexibility and reconfigurability, on the one side, and context awareness and content awareness, on the other; we show how two of the building blocks of the Flex5Gware architecture, namely on-the-fly MAC reconfiguration and dynamic multi-cell coordinated resource scheduling, can leverage context and content information to make reconfiguration decisions. Our evaluation, conducted by both prototyping and simulation, show that this brings significant benefits in terms of improved coexistence of heterogeneous access networks and reduced latency. We terminate our paper by discussing how the Flex5Gware architecture aims at influencing future system standardization and leveraging the benefits of some key 5G networking enablers described in the paper.

8 citations


Cites background from "Performance Evaluation of LTE and W..."

  • ...This is quite different from current approaches, for example, in the coexistence scenario between LTE in unlicensed bands and WiFi, where the utilization of bandwidth reduction [27], duty-cycling muting, or blank subframes [26] is unilaterally taken by LTE, while the implementation of listen-before talk before transmitting LTE frames requires to build new LTE radio [27, 28]....

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Proceedings ArticleDOI
10 Jun 2014
TL;DR: This solution consists of a new architectural logical point-to-point optical link that brings the macro layer indoors that provides higher bandwidth, no eavesdropping, frequency reuse, low latency, interference and network management, and cell selection.
Abstract: In this work we present an innovative solution to reach good quality of service while using mobile broadband indoors: the fiber radio-dot. This solution consists of a new architectural logical point-to-point optical link that brings the macro layer indoors. This solution provides higher bandwidth, no eavesdropping, frequency reuse, low latency, interference and network management, and cell selection. We tested the solution in the lab achieving an EVM of 0.75 %rms, SFDR of around 95 dBxHz 2/3 and an LTE transmission of 75 Mbit/s.

8 citations


Cites background from "Performance Evaluation of LTE and W..."

  • ...In a simulator-based system-level analysis of LTE and Wi-Fi coexistence in unlicensed bands [10] the authors conclude that LTE outperforms Wi-Fi in similar scenarios and Wi-Fi performance is degraded when it operates seamlessly with LTE due to the LTE interference at the Wi-Fi side....

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Journal ArticleDOI
TL;DR: An embedded Markov chain is developed to characterize the dynamic behavior of the contention arising from bursty MTC and Wi-Fi data traffic in the LAA framework, and a distributed scheme that randomly spreads the MTC access processes through the available time period achieves a near TDMA performance.
Abstract: The existence of relatively long LTE data blocks within the licensed-assisted access (LAA) framework results in bursty machine-type communications (MTC) packet arrivals, which cause system performance degradation and present new challenges in Markov modeling We develop an embedded Markov chain to characterize the dynamic behavior of the contention arising from bursty MTC and Wi-Fi data traffic in the LAA framework Our theoretical model reveals a high-contention phenomenon caused by the bursty MTC traffic, and quantifies the resulting performance degradation for both MTC and Wi-Fi data traffic The Markov model is further developed to evaluate three potential solutions aiming to alleviate the contention Our analysis shows that simply expanding the contention window, although successful in reducing congestion, may cause unacceptable MTC data loss A TDMA scheme instead achieves better MTC packet delivery and overall throughput, but requires centralized coordination We propose a distributed scheme that randomly spreads the MTC access processes through the available time period Our model results, validated by simulations, demonstrate that the random spreading solution achieves a near TDMA performance, while preserving the distributed nature of the Wi-Fi protocol It alleviates the MTC traffic contention and improves the overall throughput by up to 10%

8 citations


Cites background from "Performance Evaluation of LTE and W..."

  • ...Most existing literatures [8]–[12] study the fair share of the unlicensed spectrum between LTE traffic in the Channel Occupancy Time and Wi-Fi traffic in the Idle Period....

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  • ...Simulation evaluations were conducted in [8] and [9] to reveal that Wi-Fi performance would deteriorate significantly while LAA system performance would be only slightly affected....

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References
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Journal ArticleDOI
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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Journal ArticleDOI
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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Proceedings ArticleDOI
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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Proceedings ArticleDOI
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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Proceedings ArticleDOI
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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Trending Questions (1)
What is the difference between LTE and FIOS Internet?

Simulation results show that LTE system performance is slightly affected by coexistence whereas Wi-Fi is significantly impacted by LTE transmissions.