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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17 Dec 2015
TL;DR: According to the simulation results, LBE and FBE have the least effects on collisions and latency of Wi-Fi, respectively and whenWi-Fi and LBE is co-examined, it shows the best performance for the total devices.
Abstract: Recently, it is highly issued to extend wireless communication service on licensed band to unlicensed band as a part of effective utilization of the limited spectrum resources. Because Wi-Fi service is widely used in the targeted unlicensed band, the co-existence performances of Wi-Fi with the wireless communication service should be investigated. In this paper, several co-existing methods such as LBE and FBE methods based on listen-before-talk (LBT) and duty cycle (DC) methods are investigated. For the fair sharing spectrum, the number of collisions and latency are derived in situations when various co-existence methods are applying with Wi-Fi. The scenarios are evaluated using Monte-Carlo simulations. According to the simulation results, LBE and FBE have the least effects on collisions and latency of Wi-Fi, respectively. Further more, when Wi-Fi and LBE is co-existed, it shows the best performance for the total devices.
6 citations
25 Oct 2018
TL;DR: This paper tries to ensure the fair coexistence between Wi-Fi and LTE by proportionally changing the maximum packet length for each network by applying an optimization and a heuristic approach and shows that a fair share of the medium can be achieved by changing the ratio of packet length.
Abstract: Utilizing the unlicensed spectrum for the Long Term Evolution (LTE), enables the service providers to significantly increase the capacity of the network. However, LTE has to coexist with other network technologies and especially Wi-Fi. LTE employs the Licensed Assisted Access (LAA) protocol and applies the Listen Before Talk (LBT) technique to efficiently share the communication channel with Wi-Fi. Nonetheless, there is still a big gap in throughput performance between the two technologies, with the LAA-LTE considerably outperforming Wi-Fi. This unfair behavior becomes more severe in a saturation mode scenario, where the two networks are fully loaded. In this paper, we try to ensure the fair coexistence between Wi-Fi and LTE by proportionally changing the maximum packet length for each network by applying an optimization and a heuristic approach. The ultimate goal is to equalize the overall throughput for Wi-Fi and LAA or equalize the individual throughput attained for each communicating device. An admission control scheme is also studied to allocate incoming users between the two networks, while trying to balance the throughput distribution. Our results show that by changing the ratio of packet length between Wi-Fi and LAA-LTE a fair share of the medium can be achieved.
6 citations
Cites background from "Performance Evaluation of LTE and W..."
...Specifically, it has been observed that throughput of Wi-Fi systems can be considerably affected in presence of co-channel interference from LTE systems [14], [7]....
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Dissertation•
01 Jan 2019
TL;DR: Stochastic geometry is used to model and analyze di↵erent coexistence scenarios and spectrum sharing frameworks in 5G networks for multiple radio access technologies and proposes an innovative FD enabled D2D cognitive setup that carefully studies the improvement in system performance while taking into account the cost of these gains in5G networks, using stochastic geometry tools.
Abstract: Opportunistic Spectrum Access has recently become the most desirable solution for greatly improving the performance of telecommunication systems. It has proven to be a viable solution to cope with the challenging problem of spectrum scarcity and also it has been widely explored in 5G networks, so that multiple random access technologies can coexist in a cognitive setup. In 5G networks, such secondary technology candidates like Device-to-Device (D2D) communications, and Licensed-Assisted Access are envisioned to opportunistically exploit spectrum opportunities and coexist with primary technologies like LTE or WiFi. Moreover, Full Duplex (FD) technology is envisioned to play a significant role in 5G networks by allowing a user to transmit and receive on the same frequency band.
In this thesis, we present a comparative performance analysis of the spectral efficiency in a heterogeneous system where a cellular network allows the FD-Enabled D2D network to use opportunistically its spectrum while ensuring protection for its transmission/reception through guard zones. The main contributions and emphasis of this work are to explore the spectrum opportunities for secondary users by: firstly, deriving their probability of successful transmissions, deciding the feasible mode of operation (half-duplex, full-duplex or silent); and secondly, incorporating the protection zone for primary users. We assess the overall system performance, analyze the impact of different access mechanisms and propose an efficient mode selection for secondary users.
Such a systematic analysis of the integrated technologies requires a rigorous and critical evaluation of the performance gains and the costs incurred in terms of increased interference. Also, ultra-dense and random network models are envisioned in future networks especially in the urban scenario, hence, pre-deployment average system performance over various deployment scenarios can in fact be advantageous. In this thesis, we use stochastic geometry to model and analyze different coexistence scenarios and spectrum sharing frameworks in 5G networks for multiple radio access technologies. We also assess different coexistence methodologies for secondary users to fairly and peacefully coexist with primary users while ensuring the interference protection for primary users.
In summary, FD enabled heterogeneous networks have not been critically studied in previous literature, and for this reason a comprehensive study on the use of FD to existing systems is needed. This thesis proposes an innovative FD enabled D2D cognitive setup and carefully studies the improvement in system performance while taking into account the cost of these gains in 5G networks, using stochastic geometry tools.
5 citations
TL;DR: The present paper provides a technical overview about the most relevant vehicular communication technologies including IEEE 802.11p, IEEE 802.11bd, LTEV2X and NRv2X, which motivate the already started transformation of vehicle industry by enabling basic safety features and more efficient traffic management, as well as cooperative maneuver execution towards high-level automated driving.
Abstract: The present paper provides a technical overview about the most relevant vehicular communication technologies including IEEE 802.11p, IEEE 802.11bd, LTEV2X and NRV2X. IEEE 802.11p is the most matured one Wi-Fi based technology, and its successor, the IEEE 802.11bd is expected to be released in 2021. As CV2X (Cellular Vehicle to Everything) technologies, LTEV2X (Long Term Evolution V2X) and NRV2X (New Radio V2X) are discussed in this paper. The former one is already available, while the latter one’s final specification will be finalized in 2020 by the 3GPP (Third Generation Partnership Project). These four technologies also motivate the already started transformation of vehicle industry by enabling basic safety features and more efficient traffic management, as well as cooperative maneuver execution towards high-level automated driving. The comparison of these technologies is essential to clarify their benefits completely. These technologies are considered as competitors, however, it is expected that they will coexist in the same geographical region. Thus, they will share on the same unlicensed frequency bands in 5.9 GHz domain. Therefore, different coexistence scenarios are also discussed in the paper to see how their advantages could be utilized.
5 citations
Cites background from "Performance Evaluation of LTE and W..."
...In Cavalcante et al. (2013) and in Zhang et al. (2015), the authors showed by simulations that the WiFi system throughput can be degraded by up to 68 %, if an LTE system also operates in the same frequency....
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Patent•
09 Apr 2013TL;DR: In this article, a signal structure is constructed to match a structure of an interfering signal with a repetitive time structure, which is then used to cancel the interference caused by the interfering signal.
Abstract: Systems, methods, apparatuses, and computer program products for interference cancellation are provided. One method includes forming, by a wireless system, a signal structure to match a structure of an interfering signal with repetitive time structure. The method may further include using the formed signal structure to eliminate interference caused by the interfering signal. The signal structure includes parts that are synchronized with the repeated parts of the interfering signal structure to cancel the repetition of the interference, and the signal structure further comprises another part synchronized with the non-repeated parts of the interference signal.
5 citations
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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