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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18 Jun 2019
TL;DR: This work considers a disaggregated base station setup, based on the current standards for 5G-NR, with capabilities to incorporate heterogeneous technologies for serving the UEs, and develops signalling between the heterogeneous Distributed Units and the Central Unit, and applies a spectrum coordination algorithm for optimal use of the wireless spectrum.
Abstract: Cloud-RAN paves the way for flexible network management and control in the upcoming 5G and beyond networks. The base station disaggregation in different functional elements facilitates the incorporation of heterogeneous technologies in the user access network (e.g. 5G-NR, LTE, WiFi). Network densification and integration of heterogeneous technologies enables larger network capacity through the aggregation of multiple links, thus assisting the transition from the existing network infrastructure to innovative 5G networks. Nevertheless, as Ultra-Dense Heterogeneous Networks may operate in the same wireless spectrum, their performance potential may be hindered through the operation in overlapping frequencies. Thus, efficient coordination is required between the involved heterogeneous technologies. In this work, we consider a disaggregated base station setup, based on the current standards for 5G-NR, with capabilities to incorporate heterogeneous technologies for serving the UEs. We develop signalling between the heterogeneous Distributed Units and the Central Unit, and apply a spectrum coordination algorithm for optimal use of the wireless spectrum. We use OpenAirInterface as our development platform, and evaluate our results in a real testbed setup.
3 citations
Cites background from "Performance Evaluation of LTE and W..."
...Similarly, in [11] authors observe the coexistence between WiFi and LTE within the same spectrum, paved by the suggestions for enabling LTE to opportunistically access the unlicensed bands in order to increase the channel capacity [12]....
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11 Jun 2018
TL;DR: Numerical results from the models show that initial contention window size is an important parameter for LAA system to adjust for either Throughput or Channel Occupancy Time fairness but both the specifications cannot be met simultaneously.
Abstract: License Assisted Access (LAA) is a feature in 3GPP Rel-13 which is the global standard for LTE deployment in the unlicensed band. While the availability of large amount of extra spectrum in unlicensed band is always desirable, the coexistence of LAA and WiFi with an acceptable fairness is a primary challenge. This paper extends the works previously done on evaluation of downlink throughput performance of LAA and WiFi coexistence using analytical framework based on Markov Chains, to evaluate performance of the channel occupancy time for fully saturated traffic. Numerical results from the models show that initial contention window size is an important parameter for LAA system to adjust for either Throughput or Channel Occupancy Time fairness but both the specifications cannot be met simultaneously. The results also show that the trade-off is more significant when the number of LAAs outnumber WiFis and the case is no different using a single channel or two channels for transmission. Abstract)
3 citations
Cites background from "Performance Evaluation of LTE and W..."
...This difference in channel access heavily accounts for the degradation of WiFi performance when LTE operates in its normal channel access mechanisms [2] [3] [4]....
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01 Dec 2019
TL;DR: An energy detection dynamic adjustment based on Unimodal Bandits (EDDA-UB) algorithm is proposed to optimize energy detection threshold for LAA eNBs and shows the superiority on fair performance and improves the network performance in throughput.
Abstract: Toward fair coexistence with Wi-Fi, the Listen-Before-Talk (LBT) procedure has been recommended for Licensed-assisted access (LAA) in 3GPP Release 13. The energy detection threshold determines the access opportunity of LAA nodes, which plays a critical role in fairness performance on coexistence network between Wi-Fi and LAA. In this paper, an energy detection dynamic adjustment based on Unimodal Bandits (EDDA-UB) algorithm is proposed to optimize energy detection threshold for LAA eNBs. First, the impact of LAA deployment on Wi-Fi is formulated as the optimal problem with considering the fairness. To solve it, the EDDA-UB algorithm is proposed to learn the optimal energy detection threshold in time varying environment. Simulation results show that the proposed algorithm has a better convergence. Compared with existing constant or adaptive energy detection algorithm, the proposed EDDA-UB algorithm shows the superiority on fair performance and improves the network performance in throughput.
3 citations
Cites background from "Performance Evaluation of LTE and W..."
...Deploying LTE in the unlicensed band without any modification will significantly penalize Wi-Fi transmissions [4], because there is no mechanism to manage the LTE interference at the Wi-Fi side....
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01 Oct 2017
TL;DR: Simulation results demonstrate that the M-LBT mechanism can improve the total system throughput while guaranteeing fairness between LTE-U and WiFi.
Abstract: Unlicensed spectrum, unlike its licensed counterpart, has to be shared by multiple technologies and hence the performance is heavily impacted by cross-technology interference. In this paper, we focus on the co-existence mechanism design of LTE-U and WiFi in the unlicensed spectrum. We propose a modified-LBT (M-LBT) mechanism for LTE-U coexisting with WiFi in unlicensed band. Moreover, a precoding algorithm is designed to utilize spatial resource. Meanwhile, a user selection scheme can be applied to balance fairness and efficiency of LTE-U users. Simulation results demonstrate that the M-LBT mechanism can improve the total system throughput while guaranteeing fairness between LTE-U and WiFi.
3 citations
Cites background from "Performance Evaluation of LTE and W..."
...In [4], the authors perform a performance evaluation of coexistence between LTE-U and Wi-Fi systems and summarize some challenges faced by different technologies....
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Patent•
NEC1
TL;DR: In this paper, the authors proposed a method for operating a plurality of wireless networks, comprising at least two different wireless networks and each network comprising one or more stations, connected to each other within the respective network and forming said respective network.
Abstract: The present invention relates to a method for operating a plurality of wireless networks, comprising at least two different wireless networks, a first wireless network, 'FWN', and a second wireless network, 'SWN', each network comprising one or more stations, 'FWN-S', 'SWN-S', connected to each other within the respective network and forming said respective network, wherein transmission between said SWN-S within the SWN is performed via channels, wherein after each successful transmission a channel is free of transmissions for a predetermined time period, 'PTP', and wherein said FWN and said SWN operate at least in part in overlapping frequency bands, comprising the steps of Blocking a channel in the SWN by a FWN-S, connected to said FWN and SWN within an overlapping frequency band, wherein the time for performing blocking after a busy channel is smaller than a PTP and Indicating part of a total airtime said channel in the SWN will be occupied by said FWN-S for transmission, wherein the total airtime is computed as a sum of time slots used for transmission, their number being computed such that the transmission performance of said SWN is not degraded more than the level of transmission performance is degraded if said FWN-S would be operating for transmission within said SWN only
3 citations
References
More filters
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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